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		<mainTitle nfc="0"><title>Low cost shore protection</title>:<titleExt>a guide for engineers and contractors</titleExt>/<respStmt>U.S. Army Corps of Engineers.</respStmt></mainTitle>
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			<subject cat="top">Shore protection</subject>
			<subject cat="geo">United States.</subject>
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		<locClass>
			<subject cat="top">Coastal engineering</subject>
			<subject cat="geo">United States.</subject>
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			<subject cat="top">Beach erosion</subject>
			<subject cat="geo">United States.</subject>
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                                                                                   4-:4 -@--

 LOW COST SHORE PROTECTION

                                    a Guide for Engineers and Contractors
             TC
             223
             L6
             1981
<pb n="2" />

                        The U. S. Army Corps of Engineers
                        presents this     information as a
                        public service.     Inclusion of any
                        shore protection device or method
                        does not necessarily constitute a
                        government recommendation or en-
                        dorsement, nor is it guaranteed
                        that any particular method will be
                        successful for a specific applica-
                        tion.
<pb n="3" />

           LOW COST SHORE PROTECTION
                                       a Gilide for Engineers and Contractor$

                                US Department of Commerce
                            NOAA Coatital Services Center Library
                                 2234 South Hobson Avenue
                                 Charleston, SC 29405-2413
<pb n="4" />

                                    TABLE OF CONTENTS

                                                                         Page

          INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . .     5

               Low Cost Shore Protection . . . . . . . . . . . . . . .     5
               The Shoreline Erosion Control Demonstration Program.    .   5
               Shoreline Processes . . . . . . . . . . . . . . . . . .     6

          THE EROSION PROBLEM  . . . . . . . . . . . . . . . . . . . .    15

               The Importance of Shoreform . . . . . . . . . . . . . .    15
               The Causes of Erosion . . . . . . . . . . . . . . . . .    18

          A LOOK AT THE OPTIONS  . . . . . . . . . . . . . . . . . . .    21

               No Action . . . . . . . . . . . . . . . . . . . . . . .    21
               Relocation  . . . . . . . . . . . . . . . . . . . . . .    21
               Bulkheads and Seawalls  . . . . . . . . . . . . . . . .    22
               Revetments  . . . . . . . . . . . . . . . . . . . . . .    24
               Breakwaters . . . . . . . . . . . . . . . . . . . . . .    25
               Groins  . . . . . . . . . . . . . . . . . . . . . . . .    26
               Beach Fills . . . . . . . . . . . . . . . . . . . . . .    28
               Vegetation  . . . . . . . . . . . . . . . . . . . . . .    28
               Infiltration and Drainage Controls   . . . . . . . . . .   29
               Slope Flattening  . . . . . . . . . . . . . . . . . . .    29
               Perched Beaches . . . . . . . . . . . . . . . . . . . .    29
               Structures and Fills  . . . . . . . . . . . . . . . . .    31
               Structures and Vegetation . . . . . . . ... . . . . . .    31

          THE DESIGN PROBLEM . . . . . . . . . . . . . . . . . . . . .    33

               Functional Design . . . . . . . . . . . . . . . . . . .    33
               Structural Design . . . . . . . . . . . . . . . . . . .    36

          SHORE PROTECTION METHODS . . . . . . . . . . . . . . . . . .    65

               Bulkheads . . . . . . . . . . . . . . . . . . . . . . .    65
               Revetments  . . . . . . . . . . . . . . . . . . . . . .    77
               Breakwaters . . . . . . . . . . . . . . . . . . . . . .    96
               Groins  . . . . . . . . . . . . . . . . . . . . . . . .   110
               Beach Fills . . . . . . . . . . . . . . . . . . . . . .   118
               Vegetation  . . . . . . . . . . . . . . . . . . . . . .   121
               Perched Beaches . . . . . . . . . . . . . . . . . . . .   133

          PROPRIETARY DEVICES AND SPECIALTY  MATERIALS  . . . . . . . .  135

          OVERVIEW OF THE DESIGN PROBLEM . . . . . . . . . . . . . . .   139

               Characterization of the Site   . . . . . . . . . . . . .  139
               Water Levels  . . . . . . . . . . . . . . . . . . . . .   139
               Wave Conditions . . . . . . . . . . . . . . . . . . . .   140
               Selection of Devices  . . . . . . . . . . . . . . . . .   143

                                           3
<pb n="5" />

                                    TABLE OF CONTENTS
                                        (Continued)

                                                                         Page

          PERMIT REQUIREMENTS   . . . . . . . . . . . . . . . . . . . .  145

          OTHER HELP . . . . . . .. . . . . . . . . . . . . . . . . . .  147

                Corps of Engineers Offices  . . . . . . . . . . . . . .  147
                State Coastal Zone Management Offices . . . . . . . . .  148
                Other Sources of Information  . . . . . . . . . . . . .  153
                Suggested Reading . . . . . . . . . . . . . . . . . . .  154

          GLOSSARY . . . . . . . . . . . . . . . . . . . . . . . . . .   161

          LITERATURE CITED . . . . . . . . . . . . . . . . . .. . . . .  171

                                            4
<pb n="6" />

          LOW COST SHORE PROTECTION

                                   a Guide for Engineers and Contractors

                                      INTRODUCTION

               The purpose of this report is to familiarize engineers and
         contractors with various established methods of low cost shore
         protection. It is written for the individual who is knowledgeable
         in general civil engineering design and construction, but not a
         specialist in coastal engineering or shoreline protection.          This
         report can be used 'without other references, but many topics are
         discussed with only minimal detail, so some additional reading may
         be necessary to gain a better understanding of the text.             The
         Suggested Reading section at the end of the report lists a full
         range of readily available books, reports, and publications that
         are recommended for additional background study.

         LOW COST SHORE PROTECTION

               In distinguishing between low cost and cheap, one should
         remember that practically any method of shore protection, if pro-
         perly implemented, is expensive.        significant investments are
         required to achieve the durability      needed to resist even small
         waves.   Low cost simply means that the various measures are com-
         mensurate with the value of individual residential or commercial
         properties. The total cost of implementation will vary with the
         different alternatives, but in all cases, there should be a suit-
         able (and affordable) range of solutions.

               The methods described in this report are usually appropriate
         for use only in sheltered waters. That is, they are generally not
         intended for open coast sites where they would be exposed to the
         undiminished attack of large oceanic waves. Use of most of these
         structures in such areas is definitelV not recommended and entails
         a considerable risk of failure.

         THE SHORELINE EROSION CONTROL DEMONSTRATION PROGRAM

               From 1975 to 1980, the U. S. Army Corps of Engineers conducted
         a program to develop and demonstrate low cost methods of shore
         protection.    This program was mandated by Section 54 of Public
         Law 93-251, the Shoreline Erosion Control Demonstration Act of
         1974. Working with the Soil Conservation Service, the Corps desig-
         nated 16 demonstration sites throughout the Atlantic, Gulf, and

                                            5
<pb n="7" />

         Pacific coasts, Alaska and the Great Lakes.         These sites were
         chosen because they represented a broad cross section of shoreform.
         and environmental conditions.     This would permit wide application
         of the results obtained to other sites located throughout the
         country.   At each of these sites, various structures and kinds of
         vegetation were established to evaluate their effectiveness in the
         local environment.    Twenty-one additional supplemental sites were
         also chosen where existing shore protection devices had previously
         been established by others.

              The devices at all 37 sites were intensively monitored over a
         period of months.    Data that were collected included daily visual
         observations of wave heights and directions, quarterly surveys of
         beach and offshore profiles, quarterly color aerial photos, quart-
         erly sediment sampling and gradation analyses, and monthly site
         visits with ground level photos.

         SHORELINE PROCESSES

              Before developing a comprehensive solution for a client, it is
         first necessary to understand the coastal processes that are con-
         tributing to the erosion problem. The following sections present
         basic information about shoreline processes that will serve as a
         foundation for later discussions.     These sections are not exhaus-
         tive in their depth of coverage and cannot replace detailed and
         widely accepted texts such as the Shore Protection Manual [U.S.
         Army Corps of Engineers (1977c)].

         Wave Action

              While waves are always present on the open coast, they are not
         continuous in sheltered waters.     Nonetheless., they are still the
         major cause of erosion in these areas. Several basic wave charac-
         teristics are important. The wave height is the vertical distance
         between the wave crest and trough, the period is the time (in
         seconds) it takes two successive wave crests to pass a stationary
         point, and the wavelength is the distance between successive crests
         (Figure 1).   Using linear wave theory (the simplest case), these
         characteristics are given by the expressions;

                                        L = CT                               (1)

         where L = wavelength in feet,
               C = wave celerity (speed) in feet/second,
         and   T = wave period in seconds;
                                        C = 21 tanh   2Ttd                   (2)
                                            27E        L )
         where d = water depth in feet;                            2
         and   g = acceleration due to gravity, 32.2 feet/second

                                            6
<pb n="8" />

                                       WAVELENGTH

                           WAVE
                           CREST

                                              WAVE
                                             HEIGHT
           STILLWATER

            LEVEL

                                                   WAVE TROUGH

                    WAVE PERIOD IS. THE TIME REQUIRED FOR SUCCESSIVE CRESTS TO
                    PASS A STATIONARY POINT.

                        Figure 1        Characteristics of Waves
                                               2       (_In d )
         and                              L =-q-T tanh   L                      (3)
                                             2n

              As a wave moves through deep water       (depths greater than one-
         half the wavelength), the celerity and        wavelength remain essen-
         tially constant, because for d/L &gt; 0.5 (deep water); the expression
         tanh [2nd/L] approaches unity. Therefore, since the period remains
         constant, the celerity and wavelength also do not vary. However,
         when a wave approaches the shallower water near the shore (where
         d/L &lt;0.5), Equations (2) and (3) cannot be simplified by ignoring
         tanh [2nd/L].     From Equation (2), the celerity decreases with
         depth; the wave slows as it enters shallower water. The same is
         true with the wavelength, L, as can be seen from Equation (3),
         where it appears on both sides of the equation and an iterative
         solution is required.

              As the wave continues to move in shoaling water, its profile
         begins to steepen and its gently rolling shape changes to a series
         of sharp crests with intervening flat troughs. At some point, this
         process can continue no longer and the wave breaks at the shore.
         The break point is a function of the wave height, period, water
         depth and bottom slope, but as a first approximation, assume that
         the wave breaks when the height is about 0.78 times the depth. For
         example, a 5-foot high wave breaks in a water depth of about 6.4
         feet.
            IILLWATE@R
                              \@@@WA

                                             7
<pb n="9" />

                Important wave properties are demonstrated when a train
          (series) of regular waves meets a solid barrier such as an offshore
          breakwater (Figure 2). Wave diffraction occurs when the waves pass
          the breakwater and wave energy is transferred along their crests to
          the quiet area in the   shadow of the   structure. This   causes waves
          to form in the shadow    zone  that are smaller than in   the adjacent
          unprotected zone.

                                            DIFFRACTION
                                              ZONE \
                                            Small Waves)

                                      BREAKWATER

             UNPROTECTED
                 ZONE
             (Large Waves)

                                           REFLECTION
                                              ZONE
                                          Crossing Waves)

                  Figure 2         wave Diffraction and Reflection

               Wave reflection occurs on the offshore side of the breakwater.
          While waves passing the structure are diffracted, the portions
          striking the breakwater are reflected like a billiard ball from a
          cushion.   If the structure is a smooth vertical wall, the reflec-
          tion is nearly perfect; and if the wave crests are parallel with
          the breakwater, the reflected and incident waves will reinforce
          each other to form standing waves twice as high as the incident
          waves.  This could cause considerable bottom scour at the toe of,
          and offshore from, the structure.      I f the waves approach at an
          angle, no standing waves will form, but the resulting water sur-
          face, with crossing wave crests, will be rough, and choppy. These
          short-crested waves could also cause, considerable bottom scour.

               The final important wave characteristic is evident when waves

                                            8
<pb n="10" />

         break either on a beach or structure -       The uprush of water after
         breaking is called runup and it expends the wave I s remaining en-
         ergy.   The runup height depends on the roughness and steepness of
         the structure or beach and the characteristics of the wave.             In
         general, increased roughness reduces runup.

         ,Sediment Transport

               The large variety of littoral (shoreline) materials include
         rock, boulders, cobbles, gravels, sand, silt, and clay. A number
         of classification systems have been developed to identify the'se
         materials, and typical scales of sizes are given in Figure 3.

               Rock characterizes cliff shorelines, such as along the coasts
         of northern California. Boulders are often present at the base of
         such cliffs because of rock fracturing and weathering. Cobbles and
         gravels are prevalent beach materials in the Pacific Northwest,
         Alaska, and the Great Lakes area. Sand, the most common shoreline
         material, is found in virtually all coastal areas. -Silts and clays
         generally occur on bluff shorelines or marshes, such as along the
         Great Lakes and various bays.

               Littoral materials are derived from the deterioration and
         erosion of coastal bluffs and cliffs; the weathering of rock mater-
         ials found inland and transported to the shore by rivers and
         streams; the disintegration of shells, coral or algae to form
         carbonate materials; and the production of organic material (gen-
         erally peat) by coastal marshes and wetlands.

               Failure or erosion of a bluff causes material to be deposited
         at the base. Waves sort this material and carry the fine-grained
         silts and clays offshore where they settle to the bottom.              The
         original deposit is eventually reduced to sand and gravel fractions
         which form a beach. Eventually, if no other littoral material is
         carried to the site by waves, even the sand and fine gravel will
         disappear down the coast or offshore, leaving only coarse gravels
         behind. However, a new supply of material may be deposited on the
         beach by a fresh failure of the bluff, and the process begins
         again. In many cases, therefore, the littoral materials comprising
         beaches are often derived from erosion of the shoreline itself.

               Rivers and streams that carry sediments eroded from the inland
         land mass are a second source of littoral material, particularly
         during floods. Material from this source is predominantly smaller
         than sand, particularly for large rivers.        These silts and clays
         are largely deposited far offshore.          Smaller rivers that flow
         through sandy drainage areas may carry significant quantities of
         sand during floods.     However, the total contribution of sand by
         rivers and streams is probably considerably less than from erosion
         of the shores themselves.

               Coral reefs, shells, and other plant or animal matter are a
         third material source.       They gradually break and weather into

                                             9
<pb n="11" />

                         American Society for               Colloids           Clay                    Silt                     Fine               Coarse                              Gravel
                          Testing Materials                                                                                     Sand                Sand

                         American Association of           Colloids             Clay                   Silt                     Fine              Coarse            Fine        medium      Coarse          Boulders
                         State Highway Officials                                                                                Sand                Sand           Gravel       Gravel      Gravel

                                                                                                Silt                  very     Fine                     Ve
                         U.S. Department of                      Clay                                                 Fine                              Coarse    Fine Gravel        Coarse Gravel          Cobbles
                           Agriculture                                                                                Sand     Sand                     Sand

                         Civil Aeronautics                             Clay                           Silt              Fine Sand           Coarse Sand                                 Gravel
                         Administration

                         Unified Soil Classification
                         (Corps of Engineers,                            Fines (Silt or Clay)                                Fine Sand            Medium       Coarse        Fine          Coarse           Cobbles
                         Department of the Army,                          Distinction  Based On Plasticity                                         Sand         Sand        Gravel         Gravel
                         and Bureau or Reclamation)

                                                                                    0     co 0
                                                       WIM                                                                                                                                                      T

                                                                                                                                      0    0
                                                       U.S. Standard Sieve Sizes                                                                                                      I   I                 I

                                                       Phi Scale

                                                                      Figure 3                         Common         Soil       Classification Systems
                                                                                                      [After          Winterkorn and Fang (1975)]
<pb n="12" />

          carbonate sands which are, for instance, the primary components of
          beaches south of Palm Beach, Florida. Swamps, marshes, and coastal
          wetlands produce peats and other organic matter, also a source of
          littoral material.    Too light to remain in place under continued
          wave action, they are ultimately washed offshore unless stabilized.

               Littoral materials are transported along the shore by wave
          action. Approaching from deeper water, the shoreward portion of a
          wave moves in progressively more shallow water than the section
          farther of fshore.  This portion begins to slow, which causes the
          wave to bend (refract) until breaking at an angle to the beach.
          This creates considerable turbulence that temporarily suspends the
          bottom sediments and carries them up the foreshore (beach face) in
          the general direction of wave advance.       The motion stops a short
          distance up the beach, and then reverses direction back down the
          slope.  However, the downrush does not retrace the same path, but
          rather, moves directly down the foreshore in response to gravity.
          The next wave repeats the process, moving the material downdrift
          along the beach.

               Littoral transport occurs not only by rolling bedload, as
          above, but also by the movement of suspended sediment. The waves
          generate a longshore current that flows through the area where they
          break (breaker zone).     Alone, it is generally too weak to move
          appreciable quantities of sediment; however, the turbulence from
          breaking waves suspends sediments that can then be moved downdrift
          by the longshore current.       This sediment generally settles out
          within a short distance, but the next wave provides additional
          movement. Therefore, longshore transport is caused by the zig-zag
          movement of bedload up and down the beach, and the turbulence and
          action of the wave-induced longshore current.

          Water Level Variations

               The water surface elevation itself constantly changes with
          time.   The stillwater level, or the water level with no waves
          present, changes because of three processes; astronomical tides,
          storms, and periodic lake level variations.

               Astronomical Tides. Tides are generated by the gravitational
          attraction between the-earth, moon, and sun, and are classified as
          diurnal, semidiurnal, or mixed. Diurnal tides have only one high
          and one low each lunar day.      Semidiurnal tides have two approxi-
          mately equal highs and two approximately equal lows daily. Mixed
          tides are intermediate between them and typically have two highs
          and lows that occur each day. However, in contrast to semidiurnal
          tides, there is a large inequality, or difference in height, be-
          tween either successive high or successive low waters. (Figure 4).
          Most Atlantic coast tides are semidiurnal and the heights of suc-
          cessive highs or lows are approximately equal.        Gulf and Pacific
          coast tides tend to be mixed, and in most cases, there is a dis-
          tinct inequality between successive highs or lows.

                                            11
<pb n="13" />

                              0        6         12        18         0         6      12         18        0         6        12 hours
                    - 12 ft.                                          I   -     I      I
                    -10                                    -Tidal     Day
                    -8                                                Tidal Period

                       6

                    -4

                    -2
                    -0-Datum
                    --2

                    --4 ft.

                                                                   SEMIDIURNAL

                             0         6         12        18         0         6      12         18        0         6        12 hours
                    -12 ft.                                                 Flo Iad Tide            bb Tide
                    -10            High Tide,,,
                    -8

                    -6

                    -4

                                                                                                                     @40
                    - O-Daturn
                    --2
                    --4 ft.                                                     Tide

                                                                      DIURNAL

                             0         6         12        18         0         6      12         18        0         6        12 hours
                    -12  f t.                                                         Tidal Day                       igher High WateF
                    -10                                                                 1 [-Tidal     Period
                    -8                                                               Lo er Hi     Water
                    -6                                Tidal Rise
                    -4

                    -2
                    -0-Dotum
                    --2                                                             Tidal Range           Higher Low Water
                                                     Lower Low Water
                         f t.                              I      ---1-                 1         1         1         1    ,   1.      1
                                                                         MIXED
                                                   Figure 4                     Types of Tides

                                                                                Wiegel                53)]
                                                           rN

                                                                                                                      H
                                                                                                     Pe,,od-,

                                                                                                       r
                                                                                                  Aote

                                                                                12
<pb n="14" />

              In addition, the tidal range, or difference in elevation
         between the high and low waters, tends to fluctuate throughout the
         month.   These tidal range variations are caused by changes in the
         distance between the earth and moon (perigean and apogean tides),
         the declination of the moon (equatorial and tropical tides), the
         declination of the sun, and the phase of the moon (spring or neap
         tides).   (See GlossarV.)     The tides are highest during spring,
         perigean and tropical tides and are particularly high when these
         are approximately in phase.
              Tides are also present on the Great Lakes, but they are small
         and not significant for practical problems of shore protection
         design.
              Some key tidal datums, shown on Figure 5, are important be-
         cause of their wide use. Not shown are datums for the Great Lakes,
         where all levels are ultimately referenced to the International
         Great Lakes Datum (see GlossarV). Each lake has a designated chart
         datum [Low Water Datum   (LWD)] based on the IGLD.

             MHHW    A  A   A    A                             A   A
              MHW It 11 It 11 11   It R A                   It I
              MSL  A   A      A
              MTL
             MLW                     11 If V_                V
            MLLW          V           V V

                                 5             9             13
                                           D A Y S

                    Figure 5          Illustration of Tidal Datums
                                         [After Harris (1981)]

              Storm Ef fects.    The passage of storms tends to increase the
         stillwater level through two principal mechanisms:             atmospheric
         pressure effects, and stress caused by storm winds blowing across
         the water.   Atmospheric pressure differences across a large water
         body cause a rise in the water level in the lower pressure area
         (inverse barometer effect). Water surface rises of one or two feet
         are common in niany areas under this effect.

              Enclosed water bodies (such as the Great Lakes) can also
         respond to storm forces by seiching. This       occurs when storm winds
         or pressure effects drive the water surface higher at the downwind
         end of a lake. The passage of the storm front releases this water,
         and causes a periodic oscillation within the basin that will con-
         tinue for several cycles.       On the Great Lakes, seiching is most
         pronounced on Erie, because its long axis more closely matches
         predominant storm tracks and its relatively shallow depths lead to
         higher storm setup levels.

                                            13
<pb n="15" />

               Wind stress also tends to drive the water on shore to above
          normal heights (storm setup). This continues until the tendency
          for the water to flow back to its normal level balances the forces
          driving it on shore.   The high winds associated with storms also
          generate large waves, with their effects being felt in addition to
          the elevated storm surge levels.

               Lake Level Variations.   Water levels in the Great Lakes are
          also subject to periodi-C changes.   Records of lake levels dating
          from 1836 reveal seasonal and annual changes which are due to
          variations in precipitation annually, and from year to year. Lake
          levels (particularly Ontario and Superior) are also partially con-
          trolled by regulatory works operated jointly by Canadian and U. S.
          authorities, and these may result in minimizing lake level changes.
          Average monthly lake level elevations showing data for the past
          calendar year and present year-to date, and a forecast for the next
          six months, are published monthly by the U. S. Army Corps of Engi-
          neers, Detroit District (see Other Help Section).

                                           14
<pb n="16" />

                                  THE EROSION PROBLEM

          THE IMPORTANCE OF SHOREFORM

               The land-sea boundary in characterized by many shapes and con-
          figurations.   Geologists have devised elaborate classification
          systems to describe these various features.      For the purposes of
          understanding basic shoreline processes and for designing appro-
          priate corrective measures, however, it will only be necessary to
          informally classify shorelines as either bluffs, low erodible
          plains (including sandy beaches), or wetlands. Many shorelines, of
          course, contain two or even all three of these basic features.

          Bluff Shorelines

               A distinction will be drawn between bluffs and cliffs. Cliffs
          will be defined as shorelines composed of relatively sound rock.
          These rarely undergo severe or sudden erosion problems, but may
          experience slow, steady retreat over a long period of years. Such
          shorelines generally cannot be treated with low cost solutions
          because available alternatives are usually less durable than the
          cliff rock itself.

               On the other hand, bluffs are composed of sediments such as
          clay, sand, gravel, or erodible rock and erosion problems are often
          present along these kinds of shorelines. The most prevalent causes
          of bluff erosion are toe scour by wave action, surface runoff, and
          drainage and infiltration problems that lead to slope stability
          failures.

               An important factor to consider is whether a bluff is high or
          low.  While no precise definition is possible, many writers have
          described high bluffs as those being greater than 20 or 30 feet
          high or, using a different criterion, a low bluff might be clas-
          sified as one that can stand alone, while a high bluff must either
          be protected, or otherwise treated, to remain standing.

               In evaluating conditions at a site, it is necessary to deter-
          mine which of the above processes is primarily responsible for the
          erosion problem. Slope stability problems that are not aggravated
          by toe undercutting should be treated using established civil
          engineering techniques of slope stability analysis and design.
          Typical solutions could include vertical or horizontal drains,
          slope regrading and terracing, surface drainage controls, elimi-
          nation of unnecessary surcharges at the top of the slope, and
          buttressing the toe.

            . Wave action at the toe which undermines the bluf f can be
          treated using a low cost shore protection device.      Important fac-
          tors in selecting a device will include the relative steepness of
          the offshore bottom slope, and whether a sand beach is present at
          the base of the bluff. These are often derived from bluff materi-
          als that have fallen from above, and they provide a buffer against

                                           15
<pb n="17" />

          normal wave action and may serve as a suitable foundation for
          various protective devices. During severe wave activity, however,
          waves can reach the bluff itself and erode or undercut the toe.
          Depending on the strength and characteristics of the bluff materi-
          als, this may cause the bluff to fail in a relatively short time.

               The slope of the offshore bottom is also important.       I f the
          offshore slopes are steep, deep water is closer to shore, larger
          waves can reach the bluff, and maintenance of a protective beach is
          more difficult.    Conversely, flat offshore slopes inhibit heavy
          wave action at the bluff and provide for potentially better protec-
          tive beaches.

          Low Erodible Plains and Sand Beaches

               These are the most common shoreforms throughout most areas of
          the United States. They are primarily composed of sands and grav-
          els that gently rise from the water's edge and seldom attain a
          height of more than five to ten feet above the stillwater level.

               Figure 6 is a definition sketch of an ideal  ized beach profile.
          Waves approach from offshore, finally breaking and surging up the
          foreshore. Above the foreshore, the profile flattens considerably
          to form a broad berm which is not reached by normal wave activity.
          The beach berm will sometimes be backed by a low scarp leading to a
          second berm and eventually to a bluff or sand dune.

               The profile will reach some equilibrium shape in response to
          normal water levels and wave activity. This equilibrium will be
          disturbed   and erosion will begin if the long-term water level
          rises  or predominant wave heights increase.      For a water level
                                              - NEARSHORE(littoral) ZONE
                  UPLANDW-       BEACH          (extends through breaker zone)
                             BACKSHORE  __F70RE-                       OFFSHORE
                                         SHORE

           BLUFF or
                                  RM
           ESCARPMENT
                                            SURGE
           BEACH SCARP                                    BREAKERS

           HIGH WATER LEVEL
           LOW WATER LEVEL
                   CREST OF BERM----/

                                       PLUNGE POINT

                                                                  BOTTOM

                       Figure 6        An Idealized Beach Profile
                     [After U.S. Army Corps of Engineers (1977c))

                                            1.6
<pb n="18" />

         rise, a new equilibrium profile will eventually form with the same
         shape as the old, but shifted landward and upward.           Similarly,
         increased wave activity causes a nearshore bar to grow as the beach
         erodes.  Eventually, as this bar grows and the depths of water
         decrease, the larger waves will break farther offshore.            This
         weakens their attacks on the beach and equilibrium is restored.

              At open coast sites, the return to normal water levels and
         waves will initiate a healing process that may return the profile
         to essentially its initial position.       This is because the flat
         swells tend to move sand back to the beach from the nearshore bar.
         At sheltered sites, however, these swells are not present, so the
         healing process  never occurs, and storm-caused erosion losses tend
         to be permanent.

              Changes in  the sediment supply from updrift will also cause
         movement of the  profile. A decrease in the supply will cause the
         beach to erode,  and the profile will retreat landward, while still
         maintaining the  same shape. Conversely, an increase in the supply
         will cause accretion and the profile will advance toward the water.

         Wetlands and Marshes

              Although they are treated separately in this section, wetlands
         and marshes usually occur in combination with sand beaches or low
         erodible plains.    For federal regulatory purposes, wetlands are
         defined as:

                   "Those areas that are inundated or saturated by surface
              or groundwater at a frequency and duration sufficient to
              support, and under normal circumstances do support, a pre-
              valence of vegetation typically adapted to life in saturated
              soil conditions. Wetlands generally include swamps, marshes,
              bogs, and similar areas."       [U. S. Army Corps of Engineers
              (1977b)]

              Marsh plants are primarily herbaceous (lack woody stems) and
         include grasses, sedges and rushes. The species present depend on
         location and whether the marsh is low (regularly flooded) or high
         (irregularly flooded).

              Until recently, marshes were considered undesirable and regu-
         larly drained and filled for new development or agriculture. Their
         value has now been recognized as an important environmental re-
         source, but they also protect the shore by absorbing the energy of
         approaching waves and trapping sediment that is being carried along
         by currents.    These shore protection qualities     are particularly
         important when the marsh fronts a sandy beach or other area where
         erosion is to be prevented.      In that case, the   marsh provides a
         front line of defense for the shore. While it may not provide full
         protection, it may, at least, partially dampen wave action and
         allow for less massive and costly backup protection.

                                           17
<pb n="19" />

           THE CAUSES OF EROSION

           Wave Action

                Wave action is the most obvious cause of shoreline erosion.

           Littoral Material Supply

                Stable shorelines    are in a state of dynamic equilibrium.
           Waves keep the littoral   materials in constant motion in the down-
           drift direction, and the  shoreline remains stable provided there is
           an equal supply of material from updrift. When the updrift supply
           is deficient, the shoreline erodes.

                A substantial portion of the littoral material supplied to
           shorelines is the result of updrift erosion.       If large amounts of
           the updrift shoreline are suddenly protected, material is lost to
           the littoral system.    This decreases the supply to the downdrift
           shore, resulting in erosion problems unless that land is also
           protected.

                Determining the longshore transport direction is sometimes
           necessary. This is usually a difficult task because it depends on
           wave directions that can vary considerably with the seasons.
           Summer winds (and waves) may be from one predominant direction,
           while winter storm winds may be from an entirely different quad-
           rant.  When the winds and waves change direction, the transport
           direction also changes (transport reversal).

                The gross longshore transport rate is the quantity of sand
           (usually in cubic yards per year) that moves past a fixed point in
           either direction. The net longshore transport rate is the quantity
           that moves in the predominant direction minus the quantity that
           moves the other way. The net transport rate is specified by both
           quantity -and direction (e.g., 10,000 cubic yards per year to the
           east).

                Transport rates are important when considering accretion
           .devices such as breakwaters and groins because it is necessary to
           judge the effects of device construction on the littoral system,
           particularly with respect to potential downdrift damages. A pre-
           cise estimate will not usually be possible, but it may be feasible
           to examine similar structures or harbor works that have been con-
           structed in the past for evidence of accretion over known periods
           of time.    If nothing else, this should reveal the predominant
           transport direction and a crude measure of the possible transport
           rate.  This should be an acceptable level of precision for small
           scale, low cost devices.

           Slope Stability

                Slope stability analysis is covered in standard geotechnical
           engineering textbooks [e.g., Lambe and Whitman (1969) and Winter-

                                             18
<pb n="20" />

       korn and Fang (1975)]. Major stability problems are most likely at
       high bluff shorelines where the heights are 20 feet or more.
       Except where toe protection is needed, slope stability problems on
       high bluffs tend to be beyond the range of low cost solutions.

                                       19
<pb n="21" />

                                 A LOOK AT THE OPTIONS

               Three basic choices are possible in response to an erosion
         problem: no action, relocation of endangered structures, and posi-
         tive corrective measures.     The latter includes devices that di-
         rectly armor the shore, those that intercept and dissipate wave
         energy, and those that retain the earth slopes against sliding.
         Each alternative requires an evaluation of the planned land uses,
         money and time available, and other effects that may result from
         the decision.

         NO ACTION

               This is a decision-aid that can be used to evaluate different
         alternatives.   Because even low cost solutions can require sub-
         stantial investments, it is preferable to closely estimate poten-
         tial losses using this alternative, particularly if no dwellings
         are directly threatened, and only undeveloped land or inexpensive
         structures are in danger.     Also, erosion problems are sometimes
         caused by temporary factors (e.g., unusually high Great Lakes
         levels) that may abate. The resulting erosion, therefore, may slow
         before any action is taken.      This could eliminate the immediate
         need for protective devices, or it could mean choosing a smaller
         scale, less expensive, device.

         RELOCATION

               In most cases, some action is necessary.        It may be less
         expensive to relocate endangered structures than to invest in shore
         protection. Relocation can be to an entirely different site or it
         can be a setback farther from the water at the present site. The
         required setback must be carefully evaluated because the consid-
         erable expense of moving a building could be wasted if the setback
         is insufficient.

               The first step is to evaluate the long-term erosion rate.
         This  is difficult because reliable historical data on past shore-
         line  positions is often lacking. Possible sources of data include
         a time sequence of aerial photographs or shoreline maps.        If the
         property owner has occupied the site for many years (say 25 or
         more), and has observed slow shoreline retreat during that time,
         the annual erosion rate could be approximated by dividing the total
         amount of retreat by the number of years of observation.            For
         instance, if the shoreline steadily receded     300 feet in 30 years,
         the estimated average erosion rate is about     10 feet/year. A set-
         back of 100 feet could produce an additional   10 years of life for a
         structure, provided erosion continues at the   same rate.

               Conversely, if the shoreline was stable   for years and suddenly
         retreated 300 feet in only 5 years, relocation on the same site may
         be risky and not generally advisable unless considerable setback
         room is available.

                                           21
<pb n="22" />

          BULKHEADS AND SEAWALLS

               The terms bulkhead and seawall are often used interchangeably.
          In a strict sense, however, bulkheads are retaining walls whose
          primary purpose is to hold or prevent sliding of the soil while
          providing protection from light-to-moderate wave action. Seawalls,
          on the other hand, are structures whose primary purpose is to
          protect the backshore from heavy wave action. Their massive size
          generally places them beyond the low cost range. Also, they are
          not generally needed in sheltered waters where large waves are not
          generated (except perhaps in the Great Lakes).

               Bulkheads can be used to protect eroding bluffs by retaining
          soil at the toe, thereby increasing stability, or by protecting the
          toe from erosion and undercutting. They are also used for reclama-
          tion where a fill is needed in advance of the existing shore.
          Finally, bulkheads are used for marina and.other structures, where
          deep water is needed directly at the shore .(Figure 7).

               Construction of a bulkhead does not insure stability of a
          bluff.   If a bulkhead is placed at the toe of a high bluff steep-
          ened by erosion to the point of incipient failure, the bluff above
          the bulkhead may slide, burying or moving the structure toward the
          water. To increase the chances of success, the bulkhead should be
          placed lakeward of the bluff toe, and if possible, the bluff should
          be graded to a flatter, more stable slope.

               Bulkheads protect only the land immediately behind them and
          offer no protection to adjacent    areas up- or downcoast, or to the
          fronting beach.   In fact, their  vertical faces reflect wave energy
          which may cause increased scour and could lead to a loss of any
          existing fronting beach.    If the downdrift beaches were previously
          supplied by erosion of the land    now protected, they may erode even
          more quickly.   If a beach is to   be maintained adjacent to a bulk-
          head, additional structures such   groins or detached breakwaters may
          be required.

               Bulkheads may be either cantilevers or anchored (like sheet
          piling), or gravity structures (like sand-filled bags). Cantilever
          bulkheads require adequate embedment to retain soil, and are used
          where low heights are sufficient. Toe scour reduces their effec-
          tive embedment and can cause failure.         Anchored bulkheads are
          usually used where higher structures are needed. They also require
          adequate embedment (although less than cantilever bulkheads) to
          function properly, but they tend to be less susceptible to toe
          scour.

               Gravity structures eliminate the need for heavy pile driving
          equipment and are often appropriate where subsurface conditions
          hinder pile penetration. However, they require strong foundation
          soils to adequately support their weight, and they normally do not
          sufficiently penetrate the ground to develop reliable soil resis-
          tance on the offshore side.     Therefore, they depend primarily on
          shearing resistance along the base of the bulkhead to support the

                                            22
<pb n="23" />

                                                RETAIN BLUFF

              LAND  RECLAMATION                   DOCKING STRUCTURE

                         Figure 7       Uses of Bulkheads

        applied loads.   Gravity bulkheads also cannot prevent rotational
        slides in materials where the failure surface passes beneath the
        structure.  Their use, therefore, is generally limited to rela-
        tively low heights where their cost is comparable to cantilever
        sheet pile bulkheads.

                                        23
<pb n="24" />

          REVETMENTS

               A revetment is placed on a slope to protect it and adjacent
          uplands against scour (Figure 8).      It depends on the underlying
          soil for support, so it must be built on a stable slope. An un-
          stable bank must first be properly graded before construction.
          Fill material, when needed to achieve a uniform grade, must be
          adequately compacted.

           OVERTOPPING
                APRON

                                              ARMOR LAYER

                                                                          M H W

                                                            TOE
                                                                          MLW
                                                         PROTECTION
               GRADED STONE
                   FILTER

                       Figure 8         Typical Revetment  Section

               Revetments protect only the land immediately behind them and
          provide no protection to adjacent areas. Erosion may continue on
          adjacent shores, and near the revetment may be accelerated by wave
          reflection from the structure, although not as seriously as with
          vertical-faced bulkheads. Also, the downdrift shore may experience
          increased erosion if it was formerly supplied with material eroded
          from the now protected area.     If a beach is to be maintained in
          front of a revetment, additional structures such as groins or
          detached breakwaters may be required.

               A revetment consists of an armor layer, filter and toe. The
          armor must resist the waves, and the slope must be sufficiently
          flat to provide stability. Typical armor materials include quarry-
          stone and 'various concrete blocks. The filter supports the armor
          against settlement, provides drainage of groundwater through the
          revetment, and prevents the retained soil from being washed through
          the armor layer by waves or groundwater     seepage.   Toe protection
          prevents displacement of the seaward edge   of the revetment.

               Overtopping by green water (not white spray) may cause erosion
          at the top of the revetment.      Problems from overtopping can be
          minimized by choosing a structure height    that is greater than the

                                            24
<pb n="25" />

        expected runup height, or by providing an overtopping apron at the
        top of the revetment.

             Flanking is another potential problem that can be prevented by
        tying each end of the revetment into adjacent shore protection
        structures or the existing bank. However, if the bank recedes, the
        ends will have to be periodically extended to maintain contact.

        BREAKWATERS

             Breakwaters are constructed offshore to dissipate the energy
        of approaching waves and form a protected shadow zone on their
        landward sides.    (Figure 9).   The ability of waves to transport
        sediment is a function of the wave height-squared, so a relatively
        modest decrease in incoming wave heights can have a major effect on
        sediment transport. For instance, if incoming waves are reduced to
        70% of their original height after passing a breakwater, their
        ability to move sediment will decrease to 0.70 x 0.70 or 49% of
        their original capacity.       Therefore, longshore-moving littoral
        drift will tend to accumulate behind the structure. The ability of
        a breakwatpr to trap sand is a function of its distance offshore,
        length parallel to shore, porosity, and spacing (where more than
        one breakwater is used).

                                       ORIGINAL
                                       SHORELINE                DOWNDRIFT
                                                                EROSION

                                                 1_@RESULTING SHORELINE
                                            -.Ole     (NATURAL ACCRETION)
           APPROACHING
           WAVE CRESTS

                                             BREAKWATER

                      Figure 9        Plan View of a Breakwater
                                """rM 0 C @Al 1A1 A 'I

                                          25
<pb n="26" />

                        If accretion continues until the breakwater is joined to the
                shore, the resulting system would act as a large groin that would
                totally block the sand supply to the downdrift beach. This could
                cause significant erosion damages. Therefore, the area landward of
                the breakwater.should be partially filled with sand after construc-
                tion is completed. This may allow sand to continue past the struc-
                ture and on to the downdrift beach without causing serious erosion
                problems.

                        Breakwaters are either fixed or floating. Fixed breakwaters
                are large masses of heavy material that rest on the bottom. Float-
                ing breakwaters are constructed of buoyant materials such as logs,
                hollow concrete boxes and scrap rubber tires. The latter are most
                popular because of their durability and ready, no-cost availa-
                bility. Floating breakwaters are generally effective in sheltered
                waters where short-period (less than five seconds) waves are dis-
                sipated as they pass floating structures.                                Such waves have short
                lengths that may be less than the width of the breakwater.

                GROINS

                       Groins are constructed perpendicular to shore and extend,
                finger-like, out into the water. Used singly or in groups known as
                groin fields, they trap sand or retard its longshore movement
                (Figure 10).           Sand tends to accumulate on the updrift side of a

                                                                   WAVE CRESTS

                       NO rE.
                         rhe resulting shoreline will
                         gradually transition to Ineel
                        the original shoreline on
                        either side of the groin field

                                               BREAK POINT
                                               FOR LARGE WAVES

                                                         X*M

                                                 RESULTING SHORELINE
                                                    (pre-f illed)

                                   ORIGINAL                             RESULTING
                                   SHORELINE                            SHORELINE
                                                                        (natural accretion)

                                            Figure 10               Effects of Groins

                                                                      26
<pb n="27" />

         groin while erosion occurs downdrift. This will cause the shore-
         line to rotate and aline itself with the crests of the incoming
         waves, gradually decreasing the angle between the waves and the
         shore. In turn, the longshore transport rate will decrease and the
         shoreline will stabilize. The fillets of sand that collect on the
         updrift sides of the groins act as protective buffers. Storm waves
         attack these accumulations first, before reaching the unprotected
         backshore.

              Without the sand fillets, groins cannot protect the shoreline
         from wave action, nor are they effective where the waves approach
         perpendicular to shore.     Groin installations also require an ade-
         quate sand supply and are not effective where the littoral mater-
         ials are finer than sand.     Silts and clays tend to move in suspen-
         sion and are not retained by groins on the beach.
              When a groin is first built, the sand trapped on its updrift
         side is no longer available to downdrift beaches and erosion may
         result.   When the updrift fillet is completely formed, the sand
         will pass around or over the groin to the downdrift shore, but at a
         slower rate than before it was built. If erosion of the downdrift
         shore is unacceptable (it usually is), an alternative is to build
         more than one groin and fill the area between with sand. This
         minimizes the downdrift damages and limits the erosion at the
         groin's shoreward end.

              Groins can be built either high or low with respect to the
         existing beach profile. High groins effectively block the supply
         of sand to downdrift beaches, provided sand cannot pass through
         them.  Low groins, built to be overtopped by waves either during
         storms or at a given tide level, permit sand to pass over them and
         nourish downdrift beaches.

              A groin's length must be sufficient to create the desired
         beach shape while still allowing sand to pass around its outer end.
         If a groin extends seaward past the breaker zone, the sediment
         moving around the structure may be forced too far offshore to
         return to the adjacent downdrift beach. If it is too short, it may
         not trap enough sand to provide the desired beach.

              The correct spacing of individual groins within a field is
         often difficult to determine and is a function of their length and
         the desired final shoreline shape.       If groins are too far apart,
         excessive erosion can occur between them.       If spaced too closely,
         they may not function properly. This is particularly true for long
         groins where sand passing around their ends must follow a curved
         path back to the beach. If the groins are too close toqether, the
         sand will be unable to reach the beach before it is again forced
         seaward by the next downdrift groin.

              A groin must be built to resist wave forces, currents, the
         impact of floating debris, and earth pressures created by the dif-
         ference in sand levels on both sides.       As with other structures,

                                            27
<pb n="28" />

          groins must resist toe scour, and must be constructed to prevent
          failure due to flanking (erosion at their landward end).

          BEACH FILLS

              Beach fills are quantities of sand placed on the shoreline by
          mechanical means, such as dredging from offshore deposits or over-
          land hauling by trucks. The resulting beach provides some protec-
          tion to the area behind it and also serves as a valuable recrea-
          tional resource.

              The beach fill functions as an eroding buffer zone.          Its
          useful life will depend on how quickly it erodes; a rapid succes-
          sion of severe storms can completely eliminate a new fill in a
          short time.  The owner must then be prepared to periodically re-
          nourish (add more fill) as erosion continues. Beach fills gener-
          ally have relatively low initial costs but periodic maintenance
          costs needed for adding new fill.

          VEGETATION

              A planting program to establish desired species of vegetation
          is an inexpensive approach to shoreline protection and erosion
          control. Depending on where stabilization is desired, species from
          one of two general groups should be selected to insure adequate
          growth.

              Found on parts of shorelines flooded periodically by brackish
          water, species of grasses, sedges, and rushes occur in marshes of
          moderate to low energy shorelines.  once extensive and widely dis-
          tributed, marsh areas were viewed  in the past as useless and were
          subjected to filling and diking.    However, their destruction has
          lessened as their importance in    the ecosystem and to shoreline
          protection has been realized.

              upland species (shrubs and trees but particularly grasses) are
          especially adapted to growing in the low-nutrient, low-moisture
          environment of the higher beach elevations, where they are subject
          to abrasion by windblown sand particles. Used to trap sand and
          stabilize the beach, upland vegetation also improves the beauty of
          a shoreline, prevents erosion during heavy rain, diminishes the
          velocity of overland flow, increases the soil's infiltration rate,
          and provides a habitat for wildlife.

              Even though vegetation provides significant help in stabiliz-
          ing slopes and preventing erosion, vegetation alone cannot prevent
          erosion from heavy wave action or prevent movement of shoreline
          bluffs activated by groundwater action. In these instances, struc-
          tural devices augmented with vegetation are recommended.
              The effectiveness of vegetation is also limited by character-
          istics of the site.    For instance, the site requirements which

                                          28
<pb n="29" />

        determine the effectiveness of 'a tidal marsh planting include:
        elevation and tidal regime, which determine the degree, duration,
        and timing of plant submergence; slope of the site; exposure to
        wave action; type of soil; salinity regime; and oxygen-aeration
        times. Plants which are specially adapted for higher beach eleva-
        tions must tolerate rapid sand accumulation, flooding, salt spray,
        abrasion by wind-borne sand particles, wind and water erosion, wide
        temperature fluctuations, drought, and low nutrient levels. Appro-
        priate species also vary with geographical location, climate, and
        distance from the water (vegetative zone).

        INFILTRATION AND DRAINAGE CONTROLS

             Infiltration and drainage controls are often needed to achieve
        stability along high bluff shorelines. Although many factors lead
        to slope stability problems, the presence of groundwater is one of
        the most important, since the majority of slope failures and land-
        slides occur during or after periods of heavy rainfall or increased
        groundwater elevations.    Infiltration controls prevent water from
        entering the ground, while drainage controls remove water that is
        already present in the soil.

             Infiltration can be controlled by appropriate ditches and
        swales, and by sealing the ground surface.        Surface cracks that
        develop when a slope begins to f ail can be an easy path for water
        to enter, exert hydrostatic pressures, and lead to further insta-
        bility.   Such cracks should be promptly filled with compacted,
        relatively impermeable soil (preferably clay) to reduce the poten-
        tial for such detrimental effects.

             Drainage of the subsurface can be accomplished using vertical
        or horizontal drains.    Standard design techniques and methods are
        described in civil engineering references such as Winterkorn and
        Fang (1975).

        SLOPE FLATTENING

             A bluff slope may be flattened to enhance its stability when
        adequate room exists, and there is no interference with the desired
        land use.   Freshly excavated slopes should be planted to prevent
        erosion from surface runoff.     It may also be necessary to build a
        revetment or bulkhead at the toe of the slope to protect against
        wave action.

        PERCHED BEACHES

             A perched beach (Figure 11) combines a low breakwater or sill
        and a beach fill perched, or elevated, above the normal level.

                                          29
<pb n="30" />

                         SPLASH
                         APRON
                 MHW

                 ROCK
                 SILL                             BEACH FILL

                         FILTER
                        CLOTH

                                CROSS- SECr101V 4-A

                                                   MHW

                                                   BEACH FILL
                        ROCK SILL

                                     PLAN VIEW

                            Figure 11       Perched Beach

         This alternative provides a broad buf fer against wave action while
         offering a potentially excellent  recreational site. The sill can
         be constructed of various materials, but it must be impermeable to
         the passage of the retained beach sand by using, for instance, a
         filter cloth behind and beneath the structure. The cloth prevents
         the fill from escaping through any large voids in the sill and also
         stabilizes the structure against settlement. While a graded stone
         core could also be used in a rock sill in place of filter cloth,
         the limited height of such sills generally precludes use of multi-
         layered structures of this kind.   The figure also shows a splash
         apron which is provided to prevent scour and erosion of the beach
         fill from overtopping waves.
                                                           Al

                                          30
<pb n="31" />

             Perched beaches can be provided where offshore slopes are mild
        enough to permit the use of a sill in shallow water at a reasonable
        distance from shore.

        STRUCTURES AND FILLS

             In addition to perched beaches, fills can also be incorporated
        in groin systems and with breakwaters.      in fact, auxiliary fills
        are almost mandatory in most cases, otherwise serious erosion
        problems can occur downdrift.

        STRUCTURES AND VEGETATION

             While vegetation is one means of controlling shoreline ero-
        sion, its most serious deficiency is its restriction to areas of
        limited fetch because it cannot become established in heavy wave
        environments.   Vegetation can be used in areas experiencing con-
        siderably heavier wave activity, however, if it is placed in the
        shadow of a structure such as a breakwater. The use of temporary
        structures is particillarly appealing because they provide protec-
        tion while the plants need it, and can then be removed later when
        the plantings have matured.

                                          31
<pb n="32" />

                                    THE DESIGN PROBLEM

          FUNCTIONAL DESIGN

          Shoreform Compatibility

               Certain approaches are better suited to particular shoreline
          configurations than others.      It is important to choose a method
          appropriate to the dominant shoreform at the site.

               Bluff Shorelines.     The no action alternative can be appro-
          priate for blufFs---slr-nce it does not disrupt natural shoreline pro-
          cesses and requires no investment for protective structures.
          Eventually, however, the property may be totally destroyed by ero-
          sion.  While relocation does not disrupt shoreline processes, and
          it can permanently eliminate any threat to buildings, it can cost
          as much as or more than a protective structure.            Bulkheads are
          ideally suited, either for full-height retention of low bluffs, or
          as toe protection for high bluffs. Constructed of readily avail-
          able materials and easily repaired if damaged, they are parti-
          cularly useful where offshore slopes are steep. They can, however,
          induce toe scour and loss of beach material. Revetments are mar-
          ginally effective in bluff situations.         Low bluf fs that can be
          flattened to a stable slope may be effectively protected by revet-
          ments, but high bluffs generally cannot be regraded.           Revetments
          can protect the toes of high bluffs, either alone, or in conjunc-
          tion with another device. Breakwaters reduce wave energy reaching
          the bluff but do not provide positive toe protection.           They may
          build or maintain a beach (if an adequate sand supply exists) which
          provides some protection against normal waves, but would be inef-
          fective against storm waves. Use of breakwaters generally requires
          gentle offshore slopes. Groins protect only to the extent they can
          build or hold a beach.       since they require a sand supply, they
          would not work in an area of clay or silt bluf fs unless sand were
          imported. Beach fills provide some protection against normal wave
          action but would be ineffective during storms.         Vegetation would
          provide little protection until well established and even then,
          does not positively protect against large storm waves.            Drainage
          controls are mandatory if groundwater adversely affects slope sta-
          bility. However, they provide no toe protection and can be expen-
          sive.   Slope flattening provides     a permanent solution for slope
          stability problems, but does not protect against continued wave
          action. It also requires adequate     room at the top of the bluff for
          the slope. A perched beach would      protect against normal waves but
          would be ineffective during storms. A combination approach can be
          the best solution. For instance, drainage controls should be used
          as needed, possibly with slope flattening. Toe protection could be
          provided with a revetment and a fronting sand beach to provide
          additional protection (provided offshore slopes are mild). Vegeta-
          tion planted on the regraded slope would prevent erosion from
          runoff,, and other species could be used to stabilize the beach
          fill.
               Sand Beaches.    The no action and relocation alternatives are
          applicable as they were for bluffs. Bulkheads are generally inap-

                                             33
<pb n="33" />

          propriate unless an elevated featurej, such as a promenade or
          parking lot, is needed.     Vertical bulkheads induce toe scour and
          wave reflections, and could cause erosion of the beach fronting the
          bulkhead.   Revetments are better for protecting features directly
          behind the beach since they absorb wave energy better and are more
          flexible when settlement occurs.      They have an adverse aesthetic
          effect on the beach, however, and they can limit use or access to
          the shore.    Use of   revetments by a single landowner is often a
          problem because they   are subject to flanking. Breakwaters are also
          well suited because    they trap and hold sand moving along-, on- or
          offshore.   They can cause extensive downdrift damages, however,
          because the trapped    sand cannot reach adjacent beaches. They are
          also expensive to build. Groins can effectively build beaches on
          their updrift sides but can also cause accelerated downdrift ero-
          sion.  Their functional behavior is complex and difficult to pre-
          dict.   Beach fills retain the natural form and character of the
          beach and enhance its recrdational potential.         Local sources of
          suitable sand are not always available, however,      and fills require
          periodic renourishment.     Vegetation, effective in many sheltered
          areas, has low initial costs and enhances the natural appearance
          and beauty of the shoreline.       Unfortunately, foot and vehicular
          traffic damage plantings.     Drainage controls and slope flattening
          are not applicable.     Perched beaches can be used in some areas
          where fills alone would be too large to be economical, or where
          larger wave action is a problem. Combination approaches are often
          excellent, such as a perched beach that is further stabilized by
          vegetation.

               Wetlands.   Structures built near wetlands are usually placed
          at a low bluf f or beach behind the marsh. For protection of the
          marsh itself, vegetation is the only appropriate alternative. To
          assist in establishing plantings, however, small temporary break-
          waters may be required. Beach fills or perched beaches may also be
          used to provide , a suitable substrate for planting in some areas.

          Applicability to Shoreline Uses

               Some methods lend themselves more readily than others to
          particular shoreline uses. It is important to choose a method that
          performs its function and does not interfere with the planned use
          of *the shoreline.   No action obviously does not enhance shoreline
          uses, although continued erosion may have an adverse impact.
          Relocation involves similar considerations.       Bulkheads create an
          access problem unless stairs are provided. Vertical structures may
          also cause wave reflections that can erode the remaining beach
          material. Bulkheads are necessary when some water depth for boat-
          ing activities is needed at the shore.         Revetments of randomly
          placed rough stone may hinder access to the beach.        Smooth struc-
          tures, such as concrete blocks, cause less difficulty for walkers.
          Breakwaters provide an area sheltered from waves, but they can
          hinder circulation and cause water quality problems. Beaches built
          behind breakwaters have enhanced recreational potential.            Rough
          stone structures may provide an improved habitat for certain fish

                                             34
<pb n="34" />

         species but may be hazardous to climbers. High structures may also
         intrude on the view of the water and be aesthetically undesirable.
         Groins may hinder travel along the beach, but any sand they trap
         improves the beach conditions.     Beach fills enhance recreational
         uses of the shore, but increased turbidity during construction can
         temporarily harm certain fin and shellfish species.         Vegetation
         greatly improves the natural habitat but hinders other uses of the
         beach because traffic through the plantings must be restricted.
         Drainage controls have little impact on shoreline uses and slope
         flattening reduces the available land at the shore.            Perched
         beaches provide a recreational beach. A vertical sill may 'pose a
         hazard to bathers because of the sudden step to deeper water, but
         it may provide improved access for fishing. A rock sill may pro-
         vide a natural habitat for fin and shellfish and may not be as
         hazardous to bathers.

         Conditions in the General Area

              Conditions in the local area can strongly influence the selec-
         tion of an alternative.    One of the most important considerations
         is the possible effects on downdrift properties. Accretion devices
         (breakwaters and groins) trap sand moving along the beach and tend
         to starve the downdrift shoreline.    If this would cause damages to
         neighboring properties,  the area behind the breakwater or updrift
         from the groin must be   partially filled so that littoral material
         bypasses the structure,  and downdrift damages are avoided.

              shoreline composition is also important. Accretion devices do
         not function in areas where little sand is in transit because they
         do not sufficiently calm the water to permit settlement of silts
         and clays.    Slopes and soil composition are also important for
         determining appropriate plant species.

              Finally, climatic and other environmental conditions must be
         considered.   Plant species obviously must be planted where the
         climate permits survival and growth. Salinity is critical for many
         species which can only tolerate changes of salinity within a narrow
         band. Warm salt water more easily corrodes steel and other metals
         than cold fresh water.     Warm salt water is also the habitat of
         marine borers that attack submerged timber structures.        On the
         other hand, fresh water lakes freeze in the winter, subjecting
         structures to large forces and abrasion from ice sheets.      In some
         areas this may require more sturdy construction than would be
         required for resisting wave action at the site.

         Summary

              The factors relating each available alternative to shoreform
         and shoreline use are summarized on Tables 1 and 2.

                                           35
<pb n="35" />

                                                                  Table

                                                 METHODS APPLICABLE TO VARIOUS SHOREFORMS

                          Alternative*               High Bluffs         Low Bluffs          Beaches           Wetlands
                No Action                           Rarely             Rarely             Rarely             Rarely
                Relocation                          Sometimes          Sometimes          Sometimes          Sometimes
                Bulkheads                           Usually            Almost always      Sometimes          Rarely
                Revetments                          Sometimes          Almost always      Almost always      Rarely
                Breakwaters                         Rarely             Rarely             Almost always      Sometimes
                Groins                              Almost.never       Almost never       Almost always      Almost never
                Beach Fills                         Almost never       Almost never       Almost always      Rarely
                Vegetation                          Almost never       Almost never       Sometimes          Almost always
                Infiltration and Drainage
                   Controls                         Almost always      Usually            Almost never       Almost never
                Slope Flattening                    Rarely             Usually            Almost never       Almost never

                Perched Beaches                     Rarely             Rarely             Almost always      Sometimes

                 Applicability is for the alternative used alone in    the given situation. Combination devices are
                 not included.

                                                                  Table 2

                                           COMPATIBILITY OF ALTERNATIVES WITH SHORELINE USES

                          Alternative                 Strolling          Bathing            Fishing            Boating

                No Action                           Sometimes          Sometimes          Usually            Usually

                Relocation                          sometimes          Sometimes          Sometimes          Sometimes

                Bulkheads                           Usually            Sometimes          Almost always      Almost always
                .Revetments                         Usually            sometimes          Usually            Usually

                Breakwaters                         Almost always      Almost always      Almost always      Usually

                Groins                              Usually            Almost always      Almost always      Usually

                Beach Fills                         Almost always      Almost always      Usually            Almost always

                Vegetation                          Almost never       Almost never       Almost always      Rarely

                Infiltration and
                  Drainage Controls                 Almost always      Almost always      Almost always      Almost always
                slope Flattening                    Almost always      Almost always      Almost always      Almost always
                Perched Beaches                     Almost always      Almost always      Almost always      Usually

             STRUCTURAL DESIGN

                      If the chosen alternative involves construction of a physical
             shore protection device, several key problems must be resolved
             before an adequate structural design is completed. The first step
             is an evaluation of the potential water level and design wave
             height at the site.                  Other considerations include toe protection,
             filtering, flank protection, structure height, and various environ-
             mental factors.

                                                                     36
<pb n="36" />

         Water Levels

              A design water level must be determined before the wave height
         used to design structures can be found.            In tidal waters, the
         elevation of the mean spring or diurnal tide is a sufficient star-
         ting point for low cost protection.          Table 3 is reproduced from
         Tide Tables published by the National ocean Survey (See Water
         fe__Veli___1T_nthe OTHER HELP Section).   For instance, at Station       37,
         6R-ford, Maryland, the mean tide range is 1.4 feet, the spring         range
         is 1.6 feet, and the mean tide level is +0.7 feet above chart          datum
         (MLW). The average spring tide, therefore, is +1.5 feet above MLW
         (Figure 12).    An increment should be added to account for storm
         setup effects. Local experience should dictate, but values of two
         or three feet are probably reasonable for storm setup.

              Attention should be drawn to the use of Mean Low Water (MLW)
         as datum in the previous discussion. This has been the datum used
         by the National Ocean survey in the past for east coast navigation
         charts.    In the future, however, the NOS will begin to adopt Mean
         Lower Low Water (MLLW) as datum for all nautical charts in the
         United States.      This change will occur gradually as charts are
         periodically revised and reissued.

               On the Great Lakes, the Monthly Bulletin of Lake Levels for
         the Great Lakes (see Water Leve_ls-@1_nthe Other Help Sec on) sum-
         i-ar-ii-eswat-e-F-Tevels for the previous year and the current year to
         date, as well as projected lake levels for the next six months.
         For each lake, a curve is also given for the long-term average lake
         level (1900 to the present) (See Figure 13).           A suggested design
         water level is the greater of (a) the water level midway between
         the long-term average and the recorded maximum average monthly
         water level or (b) the highest monthly water level that has oc-
         curred during the preceding year. For instance, on Lake Michigan,
         the highest average water levels occur in July when they are about
         2.0 feet above chart datum (576.8 feet). (Low Water Datum (LWD) is
         +576.8 feet IGLD for Lake Michigan.) The maximum observed monthly
         water level for July on Lake Michigan was observed in 1974 at +4.2
         feet. A water level midway between them is +3.1 feet. The maximum
         observed monthly water level during the previous year was +3.0
         feet, so the chosen water level should be the greater of the two or
         +3.1 feet (579.9 feet).

               Storm setup or seiche values should be added to obtain a final
         water level.     Figure 14 contains suggested values from Help Your-
         self [U. S. Army Corps of Engineers (1978d)] superimposed on a map
         of the Great Lakes. The design lake level, therefore, will be the
         sum of the lake level found in the previous step and the storm
         setup value.

         Wave Heights

               Waves at a site are generated either by wind action or moving
         vessels. At most locations, however, wind action is more critical

                                              37
<pb n="37" />

                                                                                                                 POSITION                   DIFFERENCES                 RANGES
                                              No.                                PLACE                                                   Time            Height                        Mean
                                                                                                                                                                                       Tide
                                                                                                                 Lot.         Long.                                     Mean   Spring  Level

                                                                                                                 .  I         . I                                       feet   feet    feet
                                                               VIRGINIA - Continued
                                                    Chesapeake Bay, Eastern Shore                  Con.          N.           W. on HAMPTON ROADS, p.88
                                                                Time meridian, 75'W.
                                           1959     Occohannock Creek            -------------------             37 33        75 55 +2   02 +2  32     -0.8      0.0    1.7    2.0     0.9
                                           1961     Pungoteague Creek            -------------------             37 40        75 50 +2   22 +2  37     -0.8      0.0    1.7    2.0     0.8
                                           1963     Onancock, Onancock Creek            ------------             37 43        75 45 +2   52 +3  09     -0.7      0.0    1.8    2.2     0.9
                                           1965     Watts Island--7       ---------------------                  37 48        75 54 +2   59 +3  02     -0.9      0.0    1.6    1.9     0.8
                                           1967     Tangier Sound Light          -----------------               37 47        75 58 +2   51 +2  48'*0.64      *0.64     1.6    1.9     0.8
                                           1969     Muddy Creek Entrance         ----------------                37 51        75 40 +3   14 +3  43     -0.3      0.0    2.2    2.6     1.1

                                                                          MARYLAND
                                                          Chesapeake Bay, Eastern Shore
                                           1971     Ape Hole Creek, Pocomoke Sound               ------          37 58        75 49 +3   24 +3  48     -0.2      0.0    2.3    2.8     1.1
                                                    Pocomoke River
                                           1973           Shelltown       -----------------------                37 59        75 38 +3   29 +4  06     -0.1      0.0    2.4    2.9     1.2
                                           1975           Pocomoke City          -------------------             38 05        75 34 +5   46 +6  05     -0.9      0.0    1.6    2.0     0.8
                                           1976           Snow Hill, city park          ------------             38 10        75 24 +7   32 +7  43     -0.6      0.0    1.9    2.3     1.0
                                           1977     Janes Island Light           ------------------              37 58        75 55 +3   51 +3  50     -0.7      0.0    1.8    2.2     0.9
                                           1979     Crisfield, Little Annemessex River-                          37 59        75 52 +3   47 +3  55     -0.5      0.0    2.0    2.4     1.0
                                           1981     Long Point, Big Annemessex River               ----          38 03        75 48 +4   16 +4  36     -0.4      0.0    2.1    2.5     1.0

                                           1983     Teague Creek, Manokin River              ---------           38 06        75 50 +4   35 +4  55     -0.4      0.0    2.1    2.5     1.0
                                           1985     Ewell, Smith Island          -----------------               38 00        76 02 +3   56 +4  21  *0.64     '0.64     1.6    1.9     0.8
                                           1987     Solomons Lump Light          -----------------               38 03        76 01 +4   13 4-4 15     -0.8      0.0    1.7    2.0     0.8
                                           1989     Holland Island Bar Light            ------------             38 04        76 06 +4   13 +4  20  *0.56     *0.56     1.4    1.7     0.7
                                           1991     Sharkfin Shoal Light         ----------------                38 12        75 59 +4   43 +4  56     -0.3      0.0    2.2    2.6     1.1
                                           1993     Great Shoals Light, Monie Bay               -------          38 13        75 53 +4   57 +5  12     -0.2      0.0    2.3    2.8     1.2
                                                    Wicomtco River
                                           1995           Whitehaven      ----------------------                 38 16        75 47 +5   24 +5  37     -0.1      0.0    2.4    2.9     1.2
                                           1997           Salisbury       -----------------------                38 22        75 36 +6   18 +6  14     +0.5      0.0    3.0    3.6     1.5
                                                    Nanticoke River
                                           1999           Roaring Point          -------------------             38 16        75 55 +4   57 +5  25     -0.2      0.0    2.3    2.8     1.2
                                           2001           Vienna   --------------------------                    38 29        75 49 +7   30 +7  36     -0.2      0.0    2.3    2.8     1.2
                                           2003           Sharptown       -----------------------                38 32        75 43 +8   16 +8  18     0.0       0.0    2.5    3.0     1.3
                                           2005     Fishing Point, Fishing Bay             ----------            38 18        76 01 +5   01 +5  24     0.0       0.0    2.5    3.0     1.2
                                           2007     Hooper Strait Light          -----------------               38 14        76 05 +4   52 1+4 57     -0.8      0.0    1.7    2.0     0.8
                                                                                                                                         on BALTIMORE, P.80
                                           2009     Hooper Island Light          -----------------               38 15        76 15 -5   07 -5  23     +0.4      0.0    1.5    1.8     0.7
                                           2011     Barren Island         -----------------------                38 20        76 16 -4   52 -5  07     +0.2      0.0    1.3    1.5     0.6
                                                    Little Choptank River
                                           2013           Taylors Island, Slaughter Creek-                       38 28        76 18 -3   27 -3  14     +0.2      0.0    1.3    1.5     0.6
                                           2015           Woolford, Church Creek           ----------            38 30        76 10 -3   25 -3  10     +0.3      0.0    1.4    1.6     0.7
                                           2017           Cherry Island, Beckwiths Creek-                        38 34        76 13 -3   21 -3  11     +0.2      0.0    1.3    1.5     0.6
                                           2019           Hudson Creek           --------------------            38 35        76 15 -3   49 -3  31     +0.3      0.0    1.4    1.6     0.7
                                           2021     Sharps Island Light          -----------------               38 38        76 23 -3   51 -4  00     +0.2      0.0    1.3    1.5     0.6
                                                    Choptank River
                                           2023           Choptank River Light          ------------             38 39        76 11 -3   17 -3  18     +0.3      0.0    1.4    1.6     0.7
                                           2025           Cambridge       -----------------------                38 34        76 04 -2   54 -2  50     +0.5      0.0    1.6    1.8     0.8
                                           2027           Choptank        ------------------------               38 41        75 57 -2   13 -1  58     +0.5      0.0    1.6    1.8     0.8
                                           2029           Dover Bridge           --------------------            38 45        76 00 -0   57 -0  56     +0'.6     0.0    1.7    2.0     0.8
                                           2031           Denton   --------------------------                    38 53        75 50 +0   13 +0  22     +1.1      0.0    2.2    2.5     1.1
                                           2033           Greensboro      ----------------------                 38 58        75 49 +1   18 +1  08     +1.4      0.0    2.5    2.9     1.2
                                           2035           Wayman Wharf, Tuckahoe Creek             ----          38 53        75 57 +0   53 +0  25     +1.3      0.b    2.4    2.8     1.2
                                                    Tred Avon River                                              I               I                  I                   I      I
                                           2037           Oxford   --------------------------                    38 42        76 10 1-3  05- -3 00     +0.3      0.01   1.4    11.6    0.7   1
                                           2039           Easton Point           --------------------            38 46        76 06 -2   59 -2  50     +0.5      0.0    1.6    1.8     0,8
                                           2041     Deep Neck Point, Broad Creek               --------          38 44        76 14 -3   10 -3  01     +0.3      0.0    1.4    1.6     0.7
                                           2043     St. Michaels, San Domingo Creek                -----         38 46        76 14 -3   08 -3  06     +0.3      0.0    1.4    1.6     0.7
                                           2045     Avalon, Dogwood Harbor            --------------             38 42        76 20 -3   08 -3  03     +0.2      0.0    1.3    1.5     0.6
                                           2047     Poplar Island         -----------------------                38 46        76 23 -3   12 -3  18     +0.1      0.0    1.2    1.3     0.6
                                           2049     Ferry Cove, Eastern Bay             -------------            38 46        76 20 -3   01 -3  04     -0.1      0.0    1.0    1.2     0.5

                                                                          Table 3                                Sample          Tide Table
                                                                    [U.-S. Department                            of Commerce                    (1976)]

                                                                                                                 38
<pb n="38" />

                                                          + 1.1MLW

                                                          + 1.4' M LW
                                                             (MEAN HIGH WATER)

                 0. 7'   0.8' (MEAN SPRING RANGE  2)

                                                               MLW
                                                            (MEAN TIDE LEVEL)

                    0.7' (MEAN TIDE RANGE - 2)

                                                          +0.0' MLW

             Figure 12        Reference Water Levels at Oxford, Maryland

                                             39
<pb n="39" />

                                                                                                                                    1980                                                                                                              1981                                                                   1982
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                                                                                            EXAMPLE
                                                                                      CHOOSE GREATER OF.'
                                                                                      (a) Midway between long term average (Thin Line) and highest recorded
                                                                                              monthly level. These are points (a)
                                                                                      W Highest water level recorded in previous 12 months (Thick Line).
                                                                                              These ore points (b).

                                                                                      LEGEND

                                                                                                               Actual monthly water levels for post 15 months
                                                                                      =No                      Projected monthly water levels for next 6months
                                                                                      -                        Average monthly water levels; 1900 to present
                                                                         ,
                                                                                      @QAT E)                  Extreme monthly high and low water levels                                                                                                                                                     I                             tR
                                                                         4

                                                                                                                                    Figure 13                                                   Design Lake Levels
                                                                                            [After U.S. Army Corps of Engineers (1981a)j

                                                                                                                                                                                                                               40
<pb n="40" />

                                                                                                  NOTE'
                                                                                                  Values of storm setup are in feet.

                                                              S
                                    /.0)        X,  .
                                  .0          (/.0)

                                               41

                                                                                (0-9) (0.8)

                                                         (2.2                                      (08) f-I* -P

                                                                                                                                                        00
                                                                                                         -0)                             ONTARIo
                                                                     0 0)                                                             X, -     (0.7)

                                                                      0-0)                                                      (4.8)                 VL

                                                                 &lt;
                                                                 .j                                   2,0            (2.0
                                                               0.7)                                  0)
                                                                                                             03
                                                                                                        (19)                     P E N N.

                                                                  I N D I A N A                     0   H I o

                                                Figure 14                   Storm     Setup values for the Great Lakes
                                                                            [After U. S. Army Corps of Engineers (1978d)]
<pb n="41" />

          for design. The design wave will be the lesser of (a) the maximum
          height generated by wind acting along the critical fetch or (b) the
          maximum breaker height that can reach the site during design water
          level conditions. In other words, if the wind can produce a larger
          wave than can be supported at the site, the available depth will
          control, not the wind.

               The height of wind-driven waves depends on several factors:
          wind speed, duration, fetch length and depth.         When considering
          wind speed, it is important to realize that there must be sustained
          wind action to effectively generate waves.        Brief gusts reaching
          high velocities do not last long enough to cause wave growth. The
          fastest-mile is a convenient way to characterize both wind speed
          and duration.    The maximum fastest-mile is the highest speed that
          occurs with a sufficient duration for the wind to travel one mile.
          In other words, a 60 mile/hour wind must last for one minute to
          travel one mile, whereas a 30 mile/hour wind must last for two
          minutes.    Figures 15 and 16 are maps of the continental United
          States, including Alaska, which display the maximum fastest-mile
          wind speed contours for 10- and 25-year return periods. For exam-
          ple, the 10-year fastest-mile wind speed at New York City is
          60 mph, and at Charleston, South Carolina it is 75 mph.

               A brief review of the concept of return period is needed
          because the public   ,tends to be confused about its meaning.        For
          instance, when told that a device will withstand the 10-year wave
          at a site, most people will probably conclude that the structure
          will be safe for the next ten years. Or, if design wave conditions
          have occurred recently, they may assume that these will not occur
          again for another ten years.        Neither of these perceptions is
          correct.   What is really meant can be illustrated by an example.
          For instance, if over a long time (e.g., 100 years), 10 episodes
          with waves of a certain size were observed, the return period for
          that wave height, based on the available statistics, would be 10
          years (100 years of record/10 observed episodes).

               Return periods can be used to assess the risk involved in a
          particular decision.    The probability, P,    that-a particular-event
          with return period, Tr,, will occur during     a period of time, 1, is
          given by,

                                     P    1     1        x 100                  (4)
                                                    TJ I

          Table 4 contains probabilities of occurrence (percentages). for
          events with 10- or 25-year return periods as a function of various
          project durations. For example, consider an individual who wishes
          to protect his shoreline for 10 years.         Using methods explained
          later, the designer chooses a 10-year design wave. The chance of
          experiencing the design wave during a structure's 10-year life is
          65 percent. If this is an unacceptable level of risk, the designer
          may then provide protection against a larger design wave, say 25
          years.   In that case, there is an 34-percent chance of the 25-year

                                             42
<pb n="42" />

                            90       0
                                                                                   0                                              60
                          80                                                                         0                                c
                          7       ......
                                                                 ..........           . ........                 6

                                                                                                                             0

                                                                              7
                                                                      ............                                         0
                                                                                                                          80

                                                                  ..........
                                5
                                                                           1, . ........ .*                          0
                                     5                                               .........
                                  9                   6                                                i.........

                                                                6                                 0     70           0
                                                    0                             70

                                                                                                               8
                                90                                         60

                                80
                                40                         8                                 [After Thom (1968))

                     Figure       15              Fastest-Mile Wind Speeds:10-year Return Period

                            10    7

                            00                                                                                                      70
                          80                                                                                                        80
                                                                         70

                                                                   ............

                                                 ......    80                                                  ......

                          6
                                                                          0                                                 0
                                                       ...... .......                                                       100
                                                                                    ...........
                                5
                                                                                                                       00
                                  50   0                                                                             0

                                                                      0                                  ........

                                                                                                                     100
                                                    70                        8
                                                                                                             90
                                                                                                             10

                                90                            0
                                96                                                              [After Thom (1968)]

                     Figure       16              Fastest-Mile Wind Speeds:25-year Return Period

                                                                               43
<pb n="43" />

          wave occurring during the structure's 10-year life. If this is an
          acceptable level of risk, the design can proceed on that basis.

                                       Table 4

                     PERCENT CHANCE OF DESIGN  EVENT OCCURRENCE

                  Project Life          Design Condition Return Period
                     (years)                        (years)
                                               10                 25

                                               10                  4
                       2                       19                   8
                       5                       41                 18
                       10                      65                 34
                       15                      79                 46
                       20                      88                 56
                       25                      93                 64
                       30                      96                 71
                       40                      99                 80
                       50                      99                 87

               Returning  to the problem of    the design wave,   the critical
          fetch must be   identified before it is possible to     calculate the
          wave height.   Fetch length is the distance across water that wind
          blows to generate waves. At a constant wind speed, the longer the
          fetch, the larger the generated waves, up to an equilibrium point
          beyond which there is no further wave growth unless the wind speed
          increases. Figure 17 shows a proposed site for a shore protection
          project.  The critical fetch must be determined in order to esti-
          mate the design way height. The longest fetch is labeled Q in
          the figure.   Line @b   , although shorter than Line           crosses
          significantly deeper water.
               In general, greater depths along the fetch will cause greater
          wave heights because of decreased bottom frictional effects. The
          fetch lines on Figure 17 have been divided into a series of equal
          length segments.   As shown on the figure, by noting the depth at
          each division point, the average depth along the fetch can be
          determined.   Care should be taken, however, to avoid including
          depths which are the result of small-scale depressions or rises
          that are not typical of the area, but which the fetch line happens
          to cross.   Small features such as rocks would not significantly
          affect wave growth and should be excluded in favor of a depth that
          is more typical to that area. The average depth must also be
          adjusted to correspond with the design water level.       If, for in-
          stance, the design water level is +2.8 fee MLW, then the average
          fetch depth would be 10. 0 feet for Line 1         and 14.4 feet for
          Line

               The final step in determining wind-driven wave heights is to
          refer to Tables 5, 6, 7, 8, and 9, and select the tables that
          bracket the average fetch depth. The wave height can then be found
          by using the fetch length and the fastest-mile wind speed. In the

                                           44
<pb n="44" />

                                                       FETCH LINE                                                                                                    4

                                                                                      2
                                           DEPTHS                              DEPTHS
                                           5           6                       3              10             12@                                                            7`                    6 5
                                                                                                               W9                                                        18 S#'.
                                                                                                                                                                           .9-
                                                       1                       12             10          1.5--@jfa    2
                                           6           1                       18             6           .. . 9' 11
                                                                                                          '2 `- 11                                                       &amp;....
                                           9           3                       18                                    PA                                                          R   '14-                                                       SCA
                                                                                                                                     10
                                     27                10                      14                               w     10        12                   do                         2                 4
                                     12                5                       13                                                        12 12 %-2               1
                                                                                                                                                                                                                           0
                                                                                                                                         Marke,
                                  Avg:        7.21       MLW Avg:                 11.6' MLW                                              .........
                                                                                                                                                 13

                                                                                                                                                  14
                                 Fetch Length: Fetch Lengt                                                                                                               'I 2r*                                                    NAUTICA
                                                                                                 h:
                                                                                                                                                                                          V5
                                           2.80        nm                      2. 10 nm
                                                                                                                                               Pile PA      t:PiI*-PA'Z--- 10  12    ii,
                                                                                                                                               12:
                                           3.20        mi                      2.40 mi
                                                                                                                                                    -7    9               36
                                                                                                                                                              bleto    1.
                                                                                                                                                         R
                                           V,,

                                                                                                                                                                   2

                                                                                                                                                                                                              J@
                                                                                                                                                        16.                                                        4                            3
                                           wg@                                                            R                                         - -
                                                                                                                                                                 2                                                                              4
                                                                                                                                                    14                                   -4@

                                                                                                                                     3 W
              LrI
                                                                                          9                                                                Ito    I
                                                                                                       14                                                                                         9
                                                                                                                                                        R
                                              9 0                                   . .......                                                                                             8
                                                                      10
                                           Z,- --% 9          lu               S*      12                                            -5                    _7
                                                                                                                       M                                                                                       2
                                                                               10
                                                                                                                                     el
                                                                                                                                                                                                                   GI
                                      4                                                                                                            3      3
                                                                                                                                                               2
                                                                                                                                                                                                                              .4

                                                                                                                     7
                                                                                                                                         4143
                                                                                                                                                                                                                               3%               ."2
                                                                                                                            20..'    18,
                                                                                                                                               4

                                                                                                                                               3
                                                                                                                          15
                                                                                                                                     15               Film    U
                                                                                                                                               Doi?,.      V;
                                                                                                                                                                                                                                                3
                                                                                                                           14
                                           Z7 Eel n                                           3                                                   @-t`fsft note 6)
                                                                                                                                         8     ..-6  4 R,i2,,
                                                       R                                                             19,                                                                           5                                      3
                                                       -4-                                                                      ::9                              atI%I-
                                                       A?'PA":                                                              @6:            3
                                                       7                                                                                                                                             s1k
                                                                                   4                                                                                                                 4
                                                2'
                                                                  A
                                                                                                 19                           W      4                                                                                             NO    -E 8
                                                                  2- PA . .....
                                                                                  9                                                                                                                                   Bridge Creeki privately
                                                                               14see 15ft 4 M 1                                                2
                                                                               F
                                                                                              . 4@                              :    4                                                                             tained channet is marked b
                                                                               Piles PA 13         21
                                                                                                                                                                                                                   beacorls I thru
                                                                               Figure            17                     Identification of                                    Fetch Lengths at a Site
<pb n="45" />

                                                                                           Table 5

                                                                     WIND-GENERATED WAVE HEIGHTS AND (PERIODS)
                                                                    FETCH LENGTHS WITH AVERAGE DEPTHS = 5 FEET

                        Wind
                        Speed                                                              Fetch Length (miles)
                        (mph)    0.5       1.0       1.5      2.0       2.5       3.0      3.5       4.0       4.5      5.0       6.o       7.0      8.0       9.0      10.0

                        10       0.5       0.5       0.5      0.5       0.5       0.5      0.5       0.5       0.5      0.5       0.5       0.5      0.5       0.5      0.5
                                 (1.0)     (1.0)     (1.0)    (2.0)     (2.0)     (2-0)    (2.0)     (2.0)     (2.0)    (2.0)     (2.0)     (2.0)    (2.0)     (2.0)    (2.0)

                        20       0.5       0.5       1.0      1.0       1.0       1.0      1.0       1.0       1.0      1.0       1.0       1.0      1.0       1.0      1.0
                                 (1.0)     (2.0)     (2.0)    (2.0)     (2-0)     (2.0)    (2-0)     (2.0)     (2.0)    (2.0)     (2.0)     (2-0)    (2.0)     (2.0)    (2.0)

                        30       1.0       1.0       1.0      1.0       1.5       1.5      1.5       1.5       1.5      1.5       1.5       1.5      1.5       1.5      1.5
                                 (2.0)     (2.0)     (2-0)    (2.0)     (2.0)     (3.0)    (3-0)     (3.0)     (3.0)    (3.0)     (3.0)     (3.0)    (3.0)     0.0)     (3.0)

                        40       l.'O      1.5       1.5      1.5       1.5       1.5      1.5       1.5       1.5      1.5       1.5       1.5      1.5       1.5      1.5
                                 (2.0      (2.0)     (3.0)    (3.0)     (3.0)     (3.0)    (3.0)     (3.0)     (3.0)    (3.0)     (3.0)     (3.0)    (3.0)     (3.0)    (3.0)

                        50       1.5       1.5       1.5      1.5       1.5       2.0      2.0       2.0       2.0      2.0       2.0       2.0      2.0       2.0      2.0
                                 (2.0)     (3.0)     (3.0)    (3.0)     (3.0)     (3.0)    (3.0)     (3.0)     (3.0)    (3.0)     (3.0)     (3.0)    (3-0)     (3.0)    (3.0)

                        55       1.5       1.5       2.0      2.0       2.0       2.0      2.0       2.0       2.0      2.0       2.0       2.0      2.0       2.0      2.0
                                 (2.0)     (3.0)     (3.0)    (3.0)     (3.0)     (3.0)    (3.0)     (3.0)     (3.0)    (3.0)     (3.01     (3.0)    (3-0)     (3.0)    (3.0)

                        60       1.5       2.0       2.0      2.0       2.0       2.0      2.0       2.0       2.0      2.0@      2.0       2.0      2.0       2.0      2.0
                                 (2.0      (3.0)     (3.0)    (3.0)     (3.0)     (3.0)    (3.0)     (3.0)     (3.0)    (3.0)     (3.0)     (4.0)    (4.0)     (4.0)    (4.0)

                        65       1.5       2.0       2.0      2.0       2.0       2.0      2.0       2.0       2.0      2.0       2.0       2.0      2.0       2.0      2.0
                                 (3.0)     (3.0)     (3.0)    (3.0)     (3.0)     (3-0)    (3.0)     (3.0)     (3.0)    (4.0)     (4.0)     (4.0)    (4.0)     (4:0)    (4.0)

                        70       2.0       2.0       2.0      2.0       2.0       2.0      2.0       2.0       2.0      2.0       2.0       2.0      2.0       2.0      2.0
                                 (3.0)     (3.0)     (3.0)    (3.0)     (3.0)     (3.0)    (3.0)     (4.0)     (4.0)    (4.0)     (4.0)     (4.0)    (4.0)     (4.0)    (4.0)

                        75       2.0       2.0       2.0      2.0       2.0       2.0      2.0       2.0       2.0      2.0       2.0       2.0      2.0       2.0      2.0
                                 (3.0)     (3.0)     (3.0)    (3.0)     (3.0)     (3.0)    (4.0)     (4.0)     (4.0)    (4.0)     (4.0)     (4.0)    (4.0)     (4.0)    (4.0)

                        80       2.0       2.0       2.0      2.5       2.5       2.5      2.5       2.5       2.5      2.5       2.5       2.5      2.5       2.5      2.5
                                 (3-0)     (3.0)     (3.0)    (3.0)     (3.0)     (4.0)    (4.0)     (4.0)     (4.0)    (4.0)     (4.0)     (4.0)    (4.0)     (4.0)    (4.0)

                                                                                           Table 6

                                                                     WIND-GENFRATED WAVE HEIGHTS AND (PERIODS)
                                                                    FETCH LENGTHS WITH AVERAGE DEPTHS = 10 FEET

                        Wind
                        Speed                                                              Fetch Length (miles)
                        (mph)    0.5       1.0       1.5      2.0       2.5       3 0      3 5       4 0       4 5      5 0                 7 0      8 0       9 0      10.0

                        10       0.5       0.5       0.5      0.5       0.5       0.5      0.5       0.5       0.5      0.5       0.5       0.5      1.0       1.0      1.0
                                 (1.0)     (1.0)     (1.0)    (2.0)     (2.0)     (2.0)    (2.0)     (2.0)     (2.0)    (2-0)     (2-0)     (2-0)    (2.0)     (2.0)    (2.0)

                        20       0.5       1.0       1.0      1.0       1.0       1.0      1.0       1.5       1.5      1.5       1.5       1.5      1.5       1.5      1.5
                                 (2.0)     (2.0)     (2.0)    (2.0)     (2.0)     (2.0)    (2.0)     (2.0)     (2.0)    (2-0)     (2.0)     (3.0)    (3.0)     (3.0)    (3.0)

                        30       1.0       1.5       1.5      1.5       1.5       1.5      2.0       2.0       2.0      2.0       2.0       2.0      2.0       2.0      2.0
                                 (2.0)     (2.0)     (2.0)    (3.0)     (3.0)     (3.0)    (3.0)     (3.0)     (3-0)    (3.0)     (3.0)     (3-0)    (3.0)     0.0)     (3.0)

                        40       1.5       1.5       2.0      2.0       2.0       2.0      2.5       2.5       2.5      2.5       2.5       2.5      2.5       2.5      2.5
                                 (2.0)     (2.0)     (3.0)    (3.0)     (3.0)     (3.0)    (3.0)     (3.0)     (3.0)    (3.0)     (3.0)     (3-0)    (4.0)     (4.0)    (4.0)

                        50       1.5       2.0       2.5      2.5       2.5       2.5      2.5       2.5       3.0      3.0       3.0       3.0      3.0       3.0      3.0
                                 (2.0)     (3A)      (3.0)    (3.0)     (3.0)     (3.0)    (3.0)     (4.0)     (4.0)    (4.0)     (4-0)     (4.0)    (4.0)     (4.0)    (4.0)

                        55       2.0       2.5       2.5      2.5       2.5       3.0      3.0       3.0       3.0      3.0       3.0       3.0      3.0       3.0      3.0
                                 (3.0)     (3.0)     (3.0)    (3.0)     (3.0)     (4.0)    (4.0)     (4.0)     (4.0)    (4.0)     (4.0)     (4.0)    (4.0)     (4.0)    (4.0)

                        60       2.0       2.5       2.5      3.0       3.0       3.0      3.0       3.0       3.0      3.0       3.0       3.0      3.5       3.5      3.5
                                 (3.0)     (3.0)     (3.0)    (4.0)     (4.0)     (4.0)    (4-0)     (4.0)     (4.0)    (4.0)     (4.0)     (4.0)    (4.0)     (4.0)    (4.0)

                        65       2.0       2.5       3.0      3.0       3.0       3.0      3.0       3.5       3.5      3.5       3.5       3.5      3.5       3.5      3.5
                                 (3.0)     (3.0)     (3.0)    (4.0)     (4.0)     (4.0)    (4.0)     (4.0)     (4.0)    (4.0)     (4.0)     (4.0)    (4.0)     (4.0)    (4.0)

                        70       2.5       3.0       3.0      3.0       3.5       3.5-     3.5       3.5       3.5      3.5       3.5       3.5      3.5       3.5      3.5
                                 (3.0)     (3.0)     (3.0)    (4.0)     (4-0)     (4.0)    (4.0)     (4.0)     (4.0)    (4.0)     (4.0)     (4.0)    (4.0)     (4.0)    (4.0)

                        75       2.5       3.0       3.0      3.5       3.5       3.5      3.5       3.5       3.5      3.5       3.5       3.5      3.5       3.5      3.5
                                 (3.0)     (3.0)     (3.0)    (4.0)     (4.0)     (4.0)    (4-0)     (4.0)     (4.0)    (4.0)     (4.0)     (4.0)    (4.0)     (4.0)    (4.0)

                        80       2.5       3.0       3.5      3.5       3.5       3.5      3.5       3.5       3.5      4.0       4.0       4.0      4.0       4.0      4.0
                                 (3.0)     (3.0)     (4.0)    (4.0)     (4.0)     (4.0)    (4-0)     (4.0)     (5.0)    (5.0)     (5.0)     (5.0)    (5.0)     (5.0)    (5-0)

                                                                                                  46
<pb n="46" />

                                                                                    Table 7

                                                                WIND-GENERATED WAVE HEIGHTS AND (PERIODS)
                                                               FETCH LENGTHS WITH AVERAGE DEPTHS = 15 FEET

                     Wind
                     Speed                                                          Fetch LeZ!th (miles)
                     (mph)    0 5      1 0      1 5      2 0      2 5      3 0      3 .5         0    4 5      5 0      6 0      7 0      8 0      9 0      10.0

                     10       0.5      0.5      0.5      0.5      0.5      0.5      0.5      0.5      0.5      0.5      0.5      1.0      1.0      1.0        1.0
                              (1-0)    (1.0)    (1.0)    (2.0)    (2.0)    (2.0)    (2.0)    (2.0)    (2.0)    (2.0)    (2.0)    (2.0)    (2.0)    (2.0)    (2.0)

                     20       0.5      1.0      1.0      1.0      1.0      1.5      1.5      1.5      1.5      1.5      1.5      1.5      1.5      2.0      2.0
                              (2.0)    (2.0)    (2.0)    (2.0)    (2-0)    (2-0)    (2.0)    (2.0)    (2.0)    (2.0)    (2.0)    (3.0)    (3.0)    (3-0)    (3.0)

                     30       1.0      1.5      1.5      1.5      2.0      2.0      2.0      2.0      2.0      2.0      2.5      2.5      2.5      2.5      2.5
                              (2.0)    (2.0)    (2.0)    (3-0)    (3.0)    (3-0)    (3.0)    (3-0)    (3.0)    (3.0)    (3.0)    (3.0)    (3.0)    (3.0)    (3.0)

                     40       1.5      2.0      2.0      2.0      2.5      2.5      2.5      2.5      3.0      3.0      3.0      3.0      3.0      3.0      3.0
                              (2.0)    (3.0)    (3.0)    (3.0)    (3.0)    (3.0)    (3.0)    (3.0)    (3.0)    (3.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)

                     50       2.0      2.0      2.5      2.5      3.0      3.0      3.0      3.5      3.5      3.5      3.5      3.5      3.5      3.5      4.0
                              (2.0)    (3.0)    (3.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4-0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)

                     55       2.0      2.5      3.0      3.0      3.0      3.5      3.5      3.5      3.5      3.5      4.0      4.0      4.0      4.0      4.o
                              (3.0)    (3.0)    (3.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)

                     60       2.0      2.5      3.0      3.5      3.5      3.5      3.5      4.0      4.o      4.0      4.0      4.o      4.o      4.0      4.5
                              (3.0)    (3.0)    (3.0)    (4.0)    (4-0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (5.0)    (5.0)

                     65       2.5      3.0      3.5      3.5      3.5      4.0      4.o      4.0      4.0      4.0      4.5      4.5      4.5      4.5      4.5
                              (3.0)    (3.0)    (3.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4-0)    (4.0)    (4.0)    (5.0)    (5.0)

                     70       2.5      3.0      3.5      4.0      4.0      4.0      4.0      4.5      4.5      4.5      4.5      4.5      4.5      4.5      4.5
                              (3.0)    (3.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (5.0)    (5.0)    (5.0)    (5.0)    (5.0)

                     75       2.5      3.5      3.5      4.0      4.0      4.5      4.5      4.5      4.5      4.5      4.5      5.0      5.0      5.0      5.0
                              (3.0)    (3.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (5.0)    (5-0)    (5.0)    (5.0)    (5-0)

                     80       3.0      3.5      4.0      4.0      4.5      4.5      4-.5     4.5      5.0      5.0      5.0      5.0      5.0      5.0      5.0
                              (3.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (5.0)    (5-0)    (5.0)    (5.0)    (5.0)    (5.0)    (5.0)    (5.0)

                                                                                    Table8

                                                               WIND-GENERATED WAVE HEIGHTS AND (PERIODS)
                                                              FETCH LENGTHS WITH AVERAGE DEPTHS = 20 FEET

                     Wind
                     Speed                                                          Fetch Leuth (miles)
                                                                                      .5     4.0
                     (mph)    0 5      1 0      1 5      2 0      2 5      3 0      3 5               4 5      5 0               7 0      8 0      9 0      10.0

                     10       0.5      0.5      0.5      0.5      0.5      0.5      0.5      0.5      0.5      0.5      1.0      1.0      1.0      1.0      1.0
                              (1.0)    (1.0)    (1.0)    (2.0)    (2-0)    (2.0)    (2.0)    (2.0)    (2.0)    (2.0)    (2.0)    (2-0)    (2.0)    (2.0)    (2.0)

                     20       0.5      1.0      1.0      1.0      1.0      1.5      1.5      1.5      1.5      1.5      1.5      1.5      2.0      2.0      2.0
                              (2.0)    (2.0)    (2.0)    (2.0)    (2.0)    (2.0)    (2.0)    (3.0)    (3.0)    (3.0)    (3.0)    (3.0)    (3.0)    (3.0)    (3.0)

                     30       1.0      1.5      1.5      1.5      2.0      2.0      2.0      2.0      2.5      2.5      2.5      2.5      3.0      3.0      3.0
                              (2.0)    (2.0)    (3.0)    (3.0)    (3.0)    (3.0)    (3.0)    (3.0)    (3.0)    (3.0)    (3.0)    (3.0)    (3.0)    (4.0)    (4.0)

                     40       1.5      2.0      2.0      2.5      2.5      2.5      3.0      3.0      3.0      3.0      3.5      3.5      3.5      3.5      3.5
                              (2.0)    (3.0)    (3.0)    (3.0)    (3-0)    (3.0)    (3-0)    (4-0)    (4.0)    (4.0)    (4.0)    (4-0)    (4.0)    (4.0)    (4.0)

                     50       2.0      2.5      2.5      3.0      3.0      3.5      3.5      3.5      3.5      4.0      4.0      4.0      4.0      4.5      4.5
                              (3.0)    (3-0)    (3.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)

                     55       2.0      2.5      3.0      3.0      3.5      3.5      4.0      4.0      4.0      4.0      4.5      4.5      4.5      4.5      4.5
                              (3.0)    (3.0)    (3.0)    (4.0)    (4.0)    (4-6)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (5.0)    (5.0)    (5.0)

                     60       2.0      3.0      3.0      3.5      4.0      4.0      4.0      4.0      4.5      4.5      4.5      5.0      5.0      5.0      5.0
                              (3.0)    (3.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (5.0)    (5.0)    (5.0)    (5.0)    (5-0)

                     65       2.5      3.0      3.5      4.0      4.0      4.5      4.5      4.5      4.5      5.0      5.0      5.0      5.0      5.0      5.5
                              (3.0)    (3.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (5.0)    (5.0)    (5.0)    (5-0)    (5.0)    (5-0)

                     70       2.5      3.5      4.0      4.0      4.5      4.5      4.5      5.o      5.0      5.0      5.0      5.5      5.5      5.5      5.5
                              (3.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (5.0)    (5.0)    (5.0)    (5.0)    (5.0)    (5.0)    (5.0)    (5.0)

                     75       3.0      3.5      4.0      4.5      4.5      5.0      5.0      5.0      5.0      5.5      5.5      5.5      5.5      6.0      6.0
                              (3.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (5.0)    (5.0)    (5.0)    (5.0)    (5.0)    (5.0)    (5.0)    (5.0)    (5-0)

                     80       3.0      4.0      4.5      4.5      5.0      5.0      5.5      5.5      5.5      5.5      5.5      6.0      6.0      6.0      6.o
                              (3-0)    (4.0)    (4.0)    (4.0)    (4.0)    (5.0)    (5.0)    (5.0)    (5.0)    (5-0)    (5.0)    (5.0)    (5-0)    (5.0)    (5.0)

                                                                                          47
<pb n="47" />

                                                                                       Table 9

                                                                    WIND-GENERATED WAVE HEIGHTS AND (PERIODS)
                                                                  FETCH LENGTHS WITH AVERAGE DEPTHS = 25 FEET

                        Wind
                        Speed                                                          Fetch Length (miles)
                        (mph)    0 5      1 0      1 5      2 0      2 5      3 0      _3 5     4 0      4 5      5 0      6.0      7.0      8.0      9.0      10.0

                        10       0.5      0.5      0.5      0.5      0.5      0.5      0.5      0.5      0.5      0.5      1.0      1.0      1.0      1.0      1.0
                                 (1-0)    (1-0)    (1.0)    (2.0)   (2.0)     (2.0)    (2.0)    (2.0)    (2.0)    (2.0)    (2.0)    (2-0)    (2.0)    (2.0)    (2.0)

                        20       0.5      1.0      1.0      1.0      1.0      1.5      1.5      1.5      1.5      1.5      1.5      2.0      2.0      2.0      2.0
                                 (2.0)    (2.0)    (2.0)    (2.0)   (2.0)     (2.0)    (2.0)    (3.0)    (3.0)    (3.0)    (3.0)    (3.0)    (3.0)    (3.0)    (3.0)

                        30       1.0      1.5      1.5      2.0      2.0      2.0      2.0      2.5      2.5      2.5      2.5      2.5      3.0      3.0      3.0
                                 (2.0)    (2.0)    (2.0)    (3.0)   (3.0)     (3.0)    (3.0)    (3.0)    (3.0)    (3.0)    (3-0)    (3-0)    (4.0)    (4.0)    (4.0)

                        40       1.5      2.0      2.0      2.5      2.5      3.0      3.0      3.0      3.0      3.5      3.5      3.5      4.0      4.0      4.0
                                 (2.0)    (3.0)    (3.0)    (3.0)   (3.0)     (3.0)    (3.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4-0)    (4.0)    (4.0)    (4.0)

                        50       2.0      2.5      3.0      3.0      3.5      3.5      3.5      4.0      4.0      4.0      4.5      4.5      4.5      4.5      5.0
                                 (3.0)    (3.0)    (3.0)    (3.0)   (4.0)     (4.0)    (4-0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (5.0)    (5-0)

                        55       2.0      2.5      3.0      3.5      3.5      4.0      4.o      4.0      4.5      4.5      4.5      5.0      5.0      5.0      5.0
                                 (3.0)    (3-0)    (3.0)    (4.0)   (4.0)     (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (5-0)    (5.0)    (5.0)    (5.0)

                        60       2.0      3.0      3.5      3.5      4.0      4.0      4.5      4.5      4.5      5.0      5.0      5.0      5.5      5.5      5.5
                                 (3.0)    (3.0)    (3.0)    (4.0)   (4.0)     (4.0)    (4.0)    (4.0)    (4.0)    (4.0)    (5.0)    (5-0)    (5.0)    (5.0)    (5.0)

                        65       2.5      3.0      3.5      4.0      4.5      4.5      4.5      5.0      5.0      5.0      5.5      5.5      5.5      6.0      6.0
                                 (3.0)    (3.0)    (4.0)    (4.0)   (4.0)     (4.0)    (4.0)    (5.0)    (5.0)    (5.0)    (5.0)    (5-0)    (5.0)    (5.0)    (5.0)

                        70       2.5      3.5      4.0      4.5      4.5      5.0      5.0      5.0      5.0      5.5      5.5      6.0      6.0      6.0      6.5
                                 (3.0)    (3.0)    (4.0)    (4.0)   (4.0)     (4.0)    (4.0)    (5.0)    (5.0)    (5.0)    (5.0)    (5-0)    (5.0)    (5.0)    (5.0)

                        75       3.0      3.5      4.0      4.5      4.5      5.0      5.5      5.5      5.5      6.0      6.0      6.0      6.5      6.5      6.5
                                 (3.0)    (3.0)    (4.0)    (4.0)   (4.0)     (4.0)    (5.0)    (5.0)    (5-0)    (5.0)    (5.0)    (5.0)    (5.0)    (5.0)    (5-0)

                        80       3.0      4.0      4.5      5.0      5.0      5.5      5.5      6.0      6.0      6.0      6.5      6.5      6.5      7.0      7.0
                                 (3.0)    (4.0)    (5.0)    (5.0)   (5-0)     (5.0)    (5.0)    (5.0)    (5.0)    (5.0)    (5.0)    (5-0)    (5-0)    (6.0)    (6.0)

                     example,             fetch line                1 was 3.@ miles                      long with an average depth of
                     10.0 feet (design wa@er level at +2.81 MLW). Assuming a                                                                            10-year,
                     fastest-mile wind speed of 65 miles/hour, the wave height                                                                         would be
                                                                                              2 , with an average depth of 14.4
                     3.0 feet (Table 6). Along Lineo
                     feet, the wave height would be 3.5 feet (interpolating between
                     Tables 6 and 7), despite the fact that its fetch length is                                                                        only 2.4
                     miles. This should be used for design. The wave periods are given
                     in parentheses on the tables below the wave heights.                                                                                In both
                     cases, the wave period is 4.0 seconds.
                                 Alternate, more precise, methods of determining the wave
                     height and period by using shallow water wave forecasting equations
                     are given in U. S. Army Corps of Engineers (1977c) (1981b) and
                     (1981c).               The two later references will eventually supersede the
                     first and are preferred by many coastal engineering specialists.
                     Their use, however, involves more elaborate procedures so, for the
                     sake of brevity and simplicity, only the equations from the first
                     reference will be given.                                     Either the tables or the equations are
                     adequate for design of low cost shore protection.

                                 The wave height, H, is,

                                                                                             48
<pb n="48" />

                                                             0.0125 (@F  0 42
         H = 0.283 U 2 tanh 0.530     d) 0.75  tanh                   2)         (5)
                9                   @U2               tanh   0.530  @d  0.71
                                                                    U 2)

         and the period, T, is
                                                             0.077 (_qFy .25
                    U              (gdY.375                         U 2
         T = 2.40 1- tanh 0.833      -         tanh                              (6)
                    9               U2                              (_gd
                                                      tanh  10. 833 U 2T*375

         where U = the wind speed in feet/second;
               F = the fetch length in feet;
               d = the depth in fee@;
         and   g = 32.2 feet/second .

         Note: The above equations are in dimensionless form and can be
                used with any consistent set of units.

              Wave heights so determined should then be checked against the
         maximum possible breaking wave at the design water level.             This
         should be evaluated using Figure 18 and the depth at the toe of the
         structure, or if appropriate, the minimum depth offshore from the
         structure.   With the design water depth at the toe of the struc-
         ture, d ; the wave period, T; and the fronting bottom slope, m; the
                 s
         breaker height, H       can be found as a function of d           For   @n-
                           ,b'
         stance, if d  s = 3.0 feet, m = 1:33, and T       4.0 secone?s,' d /gT
         0.00582, and H /d = 0.98; therefore H            3.0 x 0.98 = 2N (say
         3. 0) feet.   TR minimum depth along 'feibch line          is near Cedar
         Point where the depth is 1 foot at MLW, and 3          .@)feet under the
         design water level.     This would not control for this case (it is
         greater than d ), but it should be checked in every instance.
         Fetch line ('D &amp;es not cross similar shoal areas.
              If the wind-driven wave height was 3.5 feet, it should not be
         used for design because only a 3.0-foot wave can be supported-B-ased
         on the available minimum depth at the structure. The final design
         wave height, therefore, should be 2.9 (3.0) feet in this case. To
         restate the rule, the design wave height should be the lesser of
         the maximum wind-generated wave along the fetch, or thei-m-a-'ilimum
         possible. breaking wave at the structure or at points offshore.
              Figure 19 gives appropriate locations for measuring the depth
         at the structure, d  s

                                            49
<pb n="49" />

                                3.5
                                                   I-       ff   +I-f+i-
                                - -------- --                                Ow
                                3.0                                                              breaker travel
                                                      III                                          distance

                                                                                  6
                                                                                                            Hb
                                                                                                                                      Design SWL
                                                                    Uff
                                                                                     . .............
                                                                             :j           ..4. d,

                                                                                                                                    Nearshore slope
                                2.0                      af
                           Hb
                            d

                                1.5

         Ln
                                                                                                                                                            J.
                                         T:

                                                                                                                                                            T,
                                                                                                 MINE song=
                                1.0
                                                                                         MEIN
                                                                                                            noun

                                0.5

                                        ----------

                                  0     --------
                                   0         0.002       0.004       0.006       0.006        0;010       0.012        0.014       0.016       0.018       0.020
                                                                                               d
                                                                                               9T'

                      Figure 18                Dimensionless Design Breaker Height Versus Relative Depth at Structure
                                                        el
                                               [Wegg         (1972)]
<pb n="50" />

               ds
                                                   ds

                                                          M

                                                REVETMENTS

              BULKHEADS
                                                         ds

                                                           M
                                                 GROINS

                                                               d
                                                                S

                                                 PERCHED BEACHES

                BREAKWATERS

             Figure 19      Depth at Structure for Various Devices

       Strength

            Shore protection structures must be strong, and this can only
       be achieved by using either massive and heavy components that
       cannot be dislodged by waves, or smaller components that interlock
       to form a large mass. The problem with small interlocking units,
       such as concrete blocks, is that they exhibit little reserve
       strength. That is, once damages occur, they generally progress to
       complete failure.

       Flexibility

            Flexibility is also desired because it allows structures to
       compensate for settlement, consolidation and toe scour. The revet-
       ment shown on Figure 20 illustrates this point. The massive indi-
       vidual concrete slabs could not be moved by waves, but the struc-
       ture failed because it was not able to adjust to erosion that
       occurred around the ends and through cracks between the slabs.

       Toe Protection
               @ds
                     M

                                          __""4@ds M
                                                 r

            Toe protection is supplemental armoring of the beach surface
       in front of.a structure which prevents waves from scouring or

                                       51
<pb n="51" />

                                                     21 June 1979

                   Ong,

                                                     7 August 1979
                                                    4W

                Figure 20      Flexibility as a Structural Requirement

          undercutting it. Failure to provide toe protection invites almost
          certain failure. A typical example is shown on Figure 21.

          Filterin

               Filtering, although one of the most important technical design
          details of shore protection structures, is probably the most ne-

                                          52
<pb n="52" />

                                                    BULKHEAD
                BULKHEAD                         (WITH TOE PROTECTION)
              (NO TOE PROTECTION)

          SCOUR AT                                     FILTER
            TOE                                        CLOTH

                  Figure 21        Typical Example of Toe Protection

        glected, and leads to more failures than any other cause. The con-
        sequences of not providing proper filtering are illustrated on
        Figure 22. Without filtering, the soil particles are easily trans-
        ported through the armor layer, which continues to settle as the
        bank erodes. A properly designed f ilter blocks the passage of the
        soil particles while still allowing for hydrostatic pressure relief
        beneath the structure (Figure 23).

             A filter layer can be provided through the use of either
        graded aggregates or a synthetic filter fabric.         Filter criteria
        for graded filters are covered in standard references such as
        Winterkorn and Fang (1975). Bertram        (1940) developed one widely
        used criterion as given below:
                         D15 (filter)  &lt; 4 to 5 &lt;  D15( filter)                (7)
                         D85 (soil)                D15 (so")

              The left side of the equation is   intended to prevent piping of
        fine-grained soil through   the filter. That is, the 15-percent size
        of the filter material, D       (percent  finer by weight), must be no
        more than 4 or 5 times          D85  size of the protected soil. The

                                           53
<pb n="53" />

                                                                                         MLWV
                      INI TIA L
                     POSITION        Soil and water posses through        GRA DED
                                     gaps between stones                   STONE
                       MLW                                               FIL TER

                                                                                                       4_/-Soil particles
                                                                                                           cannot penetrate
                                                                                                          filter.
                                                                          Water easily flows throug
                                                @Groundwater              structure
                                                    f low

                                                                                       MLW V

                    FIAIA L                                              S)`NrHE r/C
                    POSMON           Erosion                             FIL TER
                                     continu'es                           CLOTH                                   SSW
                        M L W

                                                                                                   Synthetic filter cloth

                                                                                            Water can pass throuah filter
                                                                                            cloth but soil particles cannot

                                     Figure 22                                           Figure 23
                      Inadequate or No Filtering                                 Proper Filter Design

                right side of the equation provides for adequate permeability of
                the filter (several times greater than the adjacent soil).                                                 It
                requires the D              size of the filter to be-at least 4 or 5 times the
                D       f the soil.            This criterion should provide adequate permea-
                bility for structural bedding layers, but may be insufficient for
                groundwater drains.

                     . Several organizations have developed further restrictive
                criteria for filters.                    For instance, the Bureau of Reclamation
                allows no filter aggregates larger than 3.0 inches, and the Corps
                of Engineers specifies that,

                                                       D
                                                         50 (filter)        &lt; 25                               (8)
                                                         D50 (soil)

                In other words, the D                    of the filter cannot be greater than 25
                                                    50
                times the D             of the soil.            This is intended to insure that the
                gradation cUves of the filter and soil are generally parallel.

                                                                     54
<pb n="54" />

              For perforated or slotted pipe, the D      of the filter must be
         greater than the hole width or slot diameteP

                                   D85 (filter)  &gt; (1.0 to 1.2)       (9)
                                  Hole Diameter

                                  D85 (filter) &gt;  (1.2 to 1.4)       (10)
                                  Slot Width

              These and other criteria for graded filters are illustrated on
         Figure 24.

              The above criteria also apply to the armor layer in relation
         to the filter layer.    That is, the armor layer must retain the
         filter layer as the filter retains the soil. In some cases, two
         filter layers may be required to provide the necessary transition
         from the soil to the armor.

              Synthetic filter fabrics, available in woven and non-woven
         varieties, can be used in place of graded stone filters.         Woven
         cloths, manufactured of high strength nylon or other synthetic
         fibers, provide a uniform mesh with a constant opening size which
         can be matched to the soil characteristics.        Non-woven cloths,
         manufactured from masses of somewhat randomly oriented fibers
         bonded together by chemicals, heat or pressure, come in various
         standard thicknesses.    Unlike woven cloths, however, they lack
         uniform-sized openings, their principal advantage being lower cost.

              Guidance on the selection of filter fabrics is contained in
         Plastic Filter Fabric [U. S. Army Corps of Engineers (1977a)].
         Selection is based on the equivalent opening size (EOS), which the
         Corps defines as "the number of the U. S. Standard Sieve having
         openings closest in size to the filter fabric openings". Material
         will first be retained on the sieve whose number is equal to the
         EOS. The EOS of commonly used filter fabrics is given in Table 10.
         The appropriate filter fabric should be selected as follows:

              For granular soils with less than 50 percent by weight fines
         (minus No. 200 materials)
                        85% Passing Size of Soil        &gt;
                      Opening Size of the E57ssieve    -

              For other soils, the EOS should not be less than 70
         (0.0083 in.).   Furthermore, to reduce problems with clogging, no
         fabric should be used whose EOS is greater than 100 (openings
         smaller than the mesh of a No. 100 sieve). Also, no filter fabric
         should be used alone if the underlying soil contains more than 85
         percent of particles finer than the No. 200 sieve. In those cases,

                                          55
<pb n="55" />

                                        CLEAR SQUARE OPENINGS                     US STANDARD SiEVE NUMBERS
                                        10. Sn2"Ihe' r'WW,W 1                     Be- 1@@ 30 40 50 70 100          200           HYDROMETER ANALYSIS
                                                                                                                   II I          TYPICAL
                                                                                                                                              MATERIALS
                                                                                                                                              FILTER

                                                                                                SHEET ASPHAL
                                        so                                                      SAND,              ASTMOK)73D    10                  K
                                                               CONCRE                                              AVERAGE
                                                                  SAN             00@                              PROPERT
                                                                                                                   IES:                       M12 CU FTIMIN
                                 W                               ASTMD633                                          ASPHALT SAND .15 .35       .03   .03
                                                                                                                   :ONCRETE SAND .3 .75       24    .07

                                                                                                                   CONCRETE GRAVEL
                                                                                                                   WTONO4 7      12           2.5  &gt; 50
                                                                                                                                              It
                                 W                               ICONCRETE        GRAa                             2.. 70 314    25           35 2.5
                                                                      ASTM 3 3
                                 U.                                               C                                21/2"TO I Ve* 40 52        56 1.5
                                                                    V4"TO NO.4
                                 W          Al                      2" TO 3/4"
                                                      r
                                                                    2 1/2"TO I W                                   if- APPROXIMATE FINEST LIMJT
                                        20                                                                         OF FILTER MATERIALS

                                        0
                                        100 8 6 4 3 2        108 6   -4 3         2  16 6 4 3 2                    .1 8 64 3 2   .0 1 1)      643 2 .001
                                                                                  GRAIN SIZE MILLIMETERS
                                 COWES [@SE            --I FINE I CO-A-RSTT-MOIUM               I FINE             SILT OR CLAY(PLAS          OR NON-
                                                    GRAVEL                            SAND
                                                                                                                                              PTr TIC,
                                                                                                                                              LAS
                                        100                          4            810 16  30 4D50 70 100           200
                                                                                                                                 RELATION     OF FILTER
                                                                                                                                              AND BASE
                                                            \,.fINEST    LIMIT    OF
                                                                                  SAN                              D             R BASE OF    PLASTIC CLAY
                                                               Ncol!@!!@          ESN                              658           WITH LOW PERMEABILITY,
                                        so                               ALT A                                                   CONCRETE SAND FILTER
                                                          k I ["KWILTERS
                                                                                                                                   MAY BE USED.

                                                                                                                                              OR BASE OF
                                        )-60-                                                                                                 NONPLASTIC SILT',-
                                                                                                                                              ROCK FLOUR
                                                                                                                                              VARVED SILT, IN
                                                                                     D                                 D500
                                        z                                                                                                     THIS RANGE USE
                                        U. COARSEST MATERIAL                                                                                  ASPHALT SAND
                                          TO BE USED                                                                                            FILTER.
                                        z AGAINST C014CRE74
                                        U                                                                          INEST BASE
                                        W SAND FILTER LAYER
                                        1K                           i                I 1@                                       , .1(              1
                                                                  MOST FAVORA                                      FOR CONCRET
                                                                                  IT BLE                           SAND FILTER,
                                        Q. 20                        COMPOS E FILTER      -. X@                                               @4           -
                                                                                  VIb'SAND                         FOR 70% SAM;
                                                                                  30% GRAVEL DI! F                 30%GR&amp;'El-FILTERA
                                                                 N      I I' -        - .                          9\            -            D
                                        0                        1 N I I I I . I I 1111-@-Jx I I I I
                                        106-8 6 4 3 2         108 6 4 3 2             18   6 4    3                2.1 8 6 4 3   2.01 8 6 4 3 2 .001

                                        General requirements:
                                                                    D
                                        1. To avoid head loss in filter:  015B    &gt; 4, and permeability of filter must be large enough to suffice for the partic-
                                        ular drainage system.
                                                                                                ;,0 F
                                                                                                D _                D
                                                                                                50 B               &lt; 25, ;1 E
                                        2. To avoid movement of particles from base: D85 B &lt; 5,                    11
                                                                                                                   5B &lt; 20
                                        For very uniform base material (C. &lt; 1.5): DIS F/D85 D may be increased to 6
                                        For broadly graded base material (C. &gt; 4): ' DIS F/1315 B may be increased to 40
                                        3. To avoid movement of filter in drain pipe perforations or joints:
                                        N5 F/slot width &gt; (1. 2 to 1. 4)          D85 F/hole diameter &gt; (1.0 to 1. 2)
                                        4. To avoid segregation filter should contain no sizts latter than 3*-
                                        5. To avoid internal movement @bf fines, filter should have no more than 57. passing No. 200 sieve.

                                                                 CO                                                FT @3         FO
                                                         %                                                                                    I

                                                                                           F@
                                                                                                                   INE
                                                                                                                   S
                                                                                                                   FOR
                                                                                                                   SAI

                                        Figure 24                  Design criteria for Protective Filters
                               [U.S. Navy, Naval Facilities Engineering Command (1971)]

                                                                                                56
<pb n="56" />

                                         Table 10

                        FILTER FABRIC EQUIVALENT OPENING SIZES

                                Fabric                           EOS

                    Filter X                                     100
                    Laurel Erosion Control Cloth                 100
                    Monsanto E2B                                 80
                    Polyfilter X                                 70
                    Mirafi 140                                   50
                    Nicolon 66424                                50
                    Nicolon 66429                                40
                    Polyfilter GB                                40
                    Nicolon 66487                                30
                                      [U.S. Army Corps of Engineers (1977a)]
           *Note:   Manufacturer's  product lines are subject to change.
                   Check with the   supplier to verify current products and
                   specifications.

         an intermediate sand layer may provide the necessary transition
         layer from the in-situ soil to the filter fabric.

              The Corps of Engineers also limits the gradient ratio of the
         filter fabric to a maximum of 3. This is defined as the hydraulic
         gradient through the fabric and the one inch of soil immediately
         above the fabric (i ) divided by the hydraulic gradient over the
         two inches of soil 16e`tween one and three     inches above the fabric
         (i 2).

                                    Gradient Ratio      &lt; 3,                  (12)
                                                     12 -

         Where i and i are measured by a constant head permeability test
         conduct@d as s@lcified by the Corps in the earlier cited reference.

         Flank Protection

              Flank protection is important because any shore protection
         structure, such as a revetment or bulkhead, is vulnerable as ero-
         sion continues around its ends.     if not prevented by flank protec-
         tion, the land eventually erodes from behind      the structure, which
         then fails to function adequately.         Figure 25 illustrates what
         happens when flank protection is not provided.

              Return sections can be provided either        during the original
         construction or later, as erosion progresses. For instance, sheet
         pile bulkheads along low bluffs can easily be      tied into the exist-
         ing bank during the initial work. This is not generally possible
         for high bluffs.    Revetments must nearly always be progressively
         lengthened as erosion continues. They should be tied to the exis-
         ting bank or high ground during initial construction, however.

                                            57
<pb n="57" />

                                               F&gt;&lt;1

                  EXISTING
                     RELINE               BULKHEAD--,,,
                                            Z

                                   (initial Construction)
                                                   "M"*'@@@BREA7KING@@
                                                                 WAVES

                                                             RETREATED
                                                              SHORE@@...___
                    ...................... . . . . ....................................
                                          BULKHEAD--\

                 BREAKING
                 WAVES            (Without Flonk Protection)

                                                 A%

                                                                       ...........................

             RETURN                       BULKHEAD                       RETURN
              WALLS                                                      WALLS

                        BREAKING WAVES

                                   (With Flonk Protection)

                            Figure 25       Flank Protection
                                                                         RETURN
                                                                         WAL  LS

                                            58
<pb n="58" />

          Structure Height

                Waves breaking against an inclined structure will run up to an
          elevation higher than the stillwater level depending on the rough-
          ness of the structure.      Smooth concrete surfaces experience higher
          runup than rough stone slopes.          Vertical structures also cause
          splashing and can experience overtopping. If possible, the struc-
          ture should be built high enough to preclude severe overtopping.
          White spray does little damage, but solid jets of "green" water
          should be avoided.       The required height of the structure will
          depend on the computed runup height based on the wave and structure
          characteristics. Detailed guidance is presented in Stoa (1978) and
          (1979). The runup height, R, can be found by a more. approximate
          method as given below.

                First, find the wavelength at the structure by using either
          Figure 26 or Equation (3) with the known depth at the structure and
          the design wave period. The definition         sketch for runup is shown
          on Figure 27.     For SMOOTH impermeable       slopes, the runup, R'. is
          given in Seelig (1980) by,
                                               (C2 \fH/ds+ C3)
                           R = HC     0.12 1!                                      (13)
                                  1 (      H )'

          where:    L =    the local wavelength from Figure 26 or Eq. (3),
                   d =     the depth at the structure (feet),
                    R =    the approaching wave height (feet), and
          Cl. C 2"  C3 =   coefficients given below.
                     Structure Slope*           C1         C2          C3

                         Vertical              0.96       0.23       +0.06
                         1 on 1.0              1.47       0.35       -0.11
                         1 on 1.5              1.99       0.50       -0.19
                         1 on 2.25             1.81       0.47       -0.08
                         1 on 3.0              1.37       0.51       +0.04

            Interpolate  linearly  between  these values for   other slopes.

                For ROUGH slopes, Seelig    (1980) gives    the runup as,
                                      R      0.69 @    ) H                         (14)
                                            1 + 0.5

          where:                           tan 0                            (15)
                                          NFH-/ L 0
                                      L0= 5.12 T   2                               (16)
          and                         6 = the structure slope (e.g., tan e
                                           0.25 for a slope of 1V on 4H).

                                              59
<pb n="59" />

               14

               13

               12

               10
                9-                                                              12     14
                                                                         10
                8-                                              8
            0                                  4
            Z   7-                        3
            w                       2
            CL
                6-

                5-                                                WATER  DEPTH, d
                4                                                      (f t.)

                3-

                2

                0
                0   10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200
                                               Wavelength, L (ft.)

                           Figure 26      Local Wavelength Given Depth and Period
                                          [After Giles and Eckert (1979)]
<pb n="60" />

                                                                       R

               L               ds           M

                               if  -0

                   Figure 27       Wave Runup Definition Sketch

             For STEPPED slopes, Stoa (1979) recommends using 70 to 75
        percent of the smooth slope runup if the risers are vertical, and
        86 percent if the edges are rounded.

             A rough approximation of the runup height can be obtained from
        Table 11.  However, the values in the table tend to represent the
        upper bound of the available data and may result in over design.
        Equations (13) and (14) or the methods given in Stoa (1978) and
        (1979) are recommended.

             If it is impossible or undesirable to build a structure to the
        recommended height, a splash apron should be provided at the top of
        the structure.   These are generally constructed of rock and they
        prevent the ground at the top from being eroded and undermining
        that portion of the structure.

        Environmental Factors

             Many different materials can be used to construct shore pro-
        tection structures, including rock, concrete, timber, metal and
        plastics.  The choice often depends on the desired permanence of
        the protection.   Durable materials usually cost considerably more
        than shorter-lived materials used for temporary protection.        The
        choice of materials is important because the coastal environment is
        a harsh testing ground for all man-made structures.       Aside from
        wave forces, which are formidable in and of themselves, a host of
                                  z
                                            M

                                         61
<pb n="61" />

                                   R                              m                   R
                           m              SWL wn                   1.5               2.25 H
                                            10                   2.5                 1 .75 H
                        SMOOTH FACE                              4.0                 1 .50H

                                                                  m                  E-
                              .1 TR      SWL, -ai-F                - 5               1.25H
                                                         H
                                                        -L       2.5                 1.00H
                                           10                    4.0                 0.75H

                        ROUGH FACE

                                          SWL V
                           m                                       1.5               2.OOH
                                                         L

                        STEPPED FACE

                                        -SWL   V       HF
                                                                                     2.00 H

                                     10

                        V4FRT/CAL FACE
                                            W L         TH

                                            10

                                         SWI

                                          SWL

                                         Sw@L
                                   1@
                                     'o

                                 Table 11            Wave Runup Heights

                                                       62
<pb n="62" />

        chemical, biological and other factors can degrade structural
        materials. A brief review of these follows.
             Corrosion and Freezina.  Corrosion is a primary problem with
        metals in bra    h and saline water. This is particularly true in
        the splash zone, where the materials are subjected to continuous
        wet-dry cycles.  Plain carbon steel, for instance, probably has a
        life of less than five years under some conditions.        Corrosion-
        resistant steel marketed under various trade names is useful for
        some applications. Aluminum sheet piling can also be used in many
        areas in place of steel.     Stainless, galvanized, or other cor-
        rosion-protected steel, or wrought iron can be used for bolts and
        other fasteners.   However, care should be taken not to mix dis-
        similar metals in structures where they directly contact each
        other. The resulting galvanic action will.quickly corrode the more
        active metal of the pair (e.g., aluminum is more active than stain-
        less steel).

             Concrete can be degraded by chemical reaction with salt water
        and by freeze-thaw cycles.    Guidance on producing suitable high
        quality concrete is presented in Mather (1957). Aggregates should
        be durable and not reactive with cement. Dense (cement rich) mixes
        should be used, typically about 7 bags of portland cement per cubic
        yard. Types II or V should be used in salt water, while Types I or
        II are, acceptable in fresh and brackish water.       Potable water
        should generally be used, but brackish or salt water may sometimes
        be acceptable for mass concrete.      Fresh water, however, should
        always be used for reinforced concrete.      Maximum water content
        should be no more than 5 1/2 gallons per bag of cement, including
        the moisture content of the aggregates. Finally, air entrainment
        (typically 4 to 7% of the concrete volume) is necessary to minimize
        damages from freeze-thaw cycles.

             Marine Borer Activity. Timber structures submerged in brack-
        ish and salt water are subject to damage from marine borers. Any
        wood or timber used for bulkhead or other construction in areas of
        moderate borer activity should be treated with 20 pounds of creo-
        sote or 2.5 lbs. of preservative salts per cubic foot of timber.
        Where borer activity is severe, 20 pounds of creosote and 1.5
        pounds per cubic foot of preservative salts in a dual-treatment
        process is recommended for all lumber.      Timber piles should be
        dual-treated with 20 pounds of creosote and 1.0 pound of preserva-
        tive salts per cubic foot in such areas [American Wood Preservers'
        Association (1977)].

             Ultraviolet Light.   The ultraviolet component of sunlight
        rapidly degrades untreated synthetic fibers such as those used for
        filter cloth or sand bags, totally deteriorating them in less than
        one season if heavily exposed. Any fabric used for shore protec-
        tion devices should be stabilized against ultraviolet light. This
        typically involves adding carbon black to the synthetic compound
        which gives the finished product a black or dark color in contrast
        to the white or light gray color of unstabilized cloth.          Even
        filter cloth covered by a structure should be stabilized since

                                         63
<pb n="63" />

          small cracks or openings in the. structure could admit enough light
          to destroy the cloth.

               Abrasion.    Abrasion damage occurs in all structures where
          waves move coarse sediments such as sand and gravel back and forth
          across their faces.     Coarse gravels and cobbles can also cause
          impact damages when hurled by large waves.      Little can be done to
          prevent abrasion damages beyond the use of      durable rock and con-
          crete as armoring in critical areas such as     along the sand line of
          sheet pile groins.     It is here that such structures typically
          experience the greatest amount of abrasion.

               Ice Forces. Ice forces are primarily a problem on cold region
          waterbodies such as the Great Lakes.        Ice covers will typically
          vary with the size and location of the waterbody, and local cli-
          matic conditions.    Large bodies, such as the Great Lakes, usually
          develop partial ice covers, while smaller embayments within them
          may be totally covered.
               The ice covers are never totally stationary and movement
          creates several categories of ice forces on structures.        For in-
          stance, dynamic forces result from wind and current-driven ice
          sheets or floes.    Vertical-faced structures will experience large
          horizontal forces, while inclined faces will tend to reduce the
          total force acting on the structure. Static ice forces result from
          thermal expansion and contraction of relatively stationary ice
          sheets.   Fractured ice forces arise from broken pack ice driven
          against a structure.     Uplift and drawdown forces are associated
          with the adhesion of floating ice sheets to structures.

               Water level fluctuations caused by seiches, tides, or reser-
          voir operation can result in significant damage to pile-supported
          structures. Water level recession can cause considerable downward
          loadings that force the piles deeper into the bottom. Conversely,
          water surface rises will pull the piles upward. I As this occurs,
          the soil will collapse beneath the pile tips and will prevent
          return to their original positions. A series of such actions can
          jack the piles completely out of the bottom.

               Possible preventative measures include air bubbler systems and
          pile sleeves, but these must be evaluated on an individual case
          basis.   Relatively comprehensive summaries of current methods. for
          evaluating ice forces on structures are given in Neill (1976),
          Wortley (1978) and the U. S. Army Corps of Engineers (1980b).

               Vandalism and Theft.    The final factor is the susceptibility
          of the structure to vandalism. If this may be a problem, materials
          should be selected which cannot easily be cut, carried away, dis-
          mantled or otherwise damaged.       For instance, sand-filled fabric
          bags are easily slashed by knives, small concrete blocks can be
          stolen, and wire mesh baskets can be opened with wire cutters and
          the contents scattered.

                                            64
<pb n="64" />

                             SHORE PROTECTION METHODS

             This section will examine specific devices, including struc-
        tures and vegetation, in more detail. Where past performance data
        are available, these will be incorporated in the discussion.

        BULKHEADS

             Because bulkheads normally have vertical faces for ease of
        construction and cost efficiency, wave reflections are maximized,
        increasing the potential for overtopping and scour in front of the
        structure. Since scour can be a serious problem, toe protection is
        necessary for stability.     Typical toe protection consists of
        quarrystone large enough to resist movement by wave forces, with an
        underlying layer of granular material or filter cloth to prevent
        the soil from being washed through voids in the scour apron.

        Sheet Pile Bulkheads

             Wave Height Range: Above five feet.

             Sheet piling is available in different materials, including
        steel, aluminum and timber. These are used in structures that may
        be either cantilevers or anchored (Figure 28).      Detailed design
        procedures are available in standard references such as the Steel
        Sheet Piling Design Manual [U. S. Steel Corporation (1975)].

                                                Fill        Cop
                 Fill,_/_'@ CCap       Original
                                                                 Sheet Pile
                                      ground surface"

                                                                  Wale
                            Sheet Pile

                                                                    //777-
           Originall          -777W07               Tie-Bock
           ground surface
                                          Anchor-
                                         (dead man)

                                                           Li

                                                   ANCHORED

           CANFILEVER

           Figure 28       Cantilever and Anchored Sheet Pile Bulkheads

                                         65
<pb n="65" />

               A cantilever bulkhead derives its support solely from ground
          penetration; therefore, the sheet piles must be driven deep enough
          to resist overturning.      Cantilever bulkheads are susceptible to
          failure due to toe scour because this reduces the effective embed-
          ment of the piling.

               An anchored or braced bulkhead gains additional support
          against seaward deflection from embedded anchors or from battered
          structural piles on the seaward side. Anchors are commonly a row
          of piles or deadmen driven or buried a distance behind the bulk-
          head.   Connections between the anchors and wall should be wrought
          iron, galvanized or other suitably corrosion-protected steel.
          Plain carbon steel should not be used for long-term protection.
          Horizontal wales are generally located in the upper one-third of
          the wall height above the dredge line. For low bulkheads, they may
          be at or near the top of the structure. The wales distribute to
          the anchors, the lateral loads on the structure. An anchor system
          is not well suited to sites with buildings close to the shoreline
          because of the distance needed between      the bulkhead and anchors.
          In that case, brace piles may be used in place of anchoring.

               Subsurface conditions determine the     type of sheet piling that
          can be used.   Steel sheet piling can be    driven into hard soil and
          some soft rock.     Aluminum and timber     sheet piling can only be
          driven or jetted into softer soil.

               The advantages of sheet pile bulkheads are their relatively
          long and maintenance-free lives, and their uniform appearance.
          Their disadvantages include the special pile-driving equipment
          required to install them.

               Treated Timber.    Well-designed and built timber structures
          have long been i7e-cognized as viable and economical materials for
          bulkhead construction (Figure 29).        Figure 30 illustrates the
          common types of timber sheeting used. As mentioned earlier, only
          specially treated timber should be used for marine construction. A
          plan view and cross section of a typical timber bulkhead are shown
          on Figure 31.   The actual dimensions will vary. depending on site
          conditions.

               Granular material is preferred for backfill.       If anchor piles
          are used, backfilling should begin over them, and then proceed to
          the bulkhead. The joints between sheets should be kept as tight as
          possible.   The use of filter fabric is advisable as an added pre-
          caution to prevent loss of soil through cracks. Supplemental drain
          holes should be placed at regular intervals to further facilitate
          the movement of water from behind the structure, and th@se must
          always be backed with filter.cloth or properly graded crushed-stone
          T'Ilters.

               only corrosion-resistant or protected metals should be used
          for hardware and fasteners. Wrought iron anchor rods with turn-
          buckles and bolts have good durability. Galvanized fasteners are
          also recommended. Carbon steel should not be used unless protected

                                            66
<pb n="66" />

                                                                               @3"
                 __ ;qo-

                             Figure     29         Timber     Sheet  Pile   Bulkhead
                             (Photo    Courtesy of Koppers Company, Inc.)

                                          716* DEEP BY        518.DEEP BY
                                          1 314* WIDE
                                          GROOVE.             1 116' WIDE
                                          EACH SIDE           TONGUE

                                                       0   01

                                                                                        3/4' DEEP BY
              1 5/6' SQUARE                            E!L@                             1 1/4' WIDE
                OAK SPLINE_____6-                                I' OFFSET              GROOVE

                                                       0   0                      1    FROM ONE 4*x10'
                                                                                     -OR 4*xl2' ROUGH
                                          FROM ONE
                                          6'x12'                 FROM THREE
                                       -ROUGH                    2'x10' OR
                                          FASTENED  WITH TWO     2'xl2* ROUGH
                                          112* DIAM. DOLTS AND
                                          TWO 30d NAILS AT
                                          18' CENTERS -

                               SPLINED              WAKEFIELD           TONGUE AND
                                                                           GROOVE

                           Figure 30            Typical Timber Sheet Sections
                                                 [Winterkorn and Fang (1975)]
                                                                    -FS@E@
                              FI'll                    \   '*'           JE QE
                                                       TH  WO
                                                       'LTS  AND
                                                          T
                                                       .3 A@

                                                           67
<pb n="67" />

                                                                                              1V

                                                            I" diam. x 18'-2" Tie Rods
                                                            with Turnbuckles
                          E@'x 8" x 10'- 0" Wale            spaced        10'-0"
                                                                                                     Wale 6" x 8" 16'-0'

                                                                                                                NOTE.'
                                                               Sheet  Piling T 8 G                              Actual dimensions
                                                               3"x 12 ' or 3" x 10                              depend on site
                                                               12' -0" long                                     conditions.

                             Mean High Water

                                                                                                 'til"-First Stage
                                                                                                       of Filling
                                                            2 /2" Drain Holes
                                                                20'- 0"
                                                                                        U -6" x 8" x 8' x 6" Tie
                                                                                             0 10'-0"

                                    Figure 31                      Plan View and Cross Section of
                                                                    Typical Sheet Pile Bulkhead
                                       [American Wood Preservers Institute (1970)]

                 with special coatings, such as coal-tar epoxy or other bituminous
                 materials.               Minimize the number of washers under bolt heads and
                 nuts to reduce the length of exposed bolt shanks, and provide a
               @tight fit between bolted timbers so that the bolt shanks are not
                 exposed in the gaps. Bolt holes should be no more than 1/16 of an
                 inch larger than the shank to insure a tight fit. Finally, washers
                 should be provided under bolt heads and nuts to insure that these
                 bear evenly on the timber members.

                           Steel.           Steel sheet piling, probably the most widely used
                 bulkhead material (Figure 32), can be driven into hard, dense soilsf
                 and soft rock. The interlocking feature of the sheet pile sections
                 (Figure 33) provides a relatively sand-tight fit that generally
                 precludes the need for filters. This close fit may also be essen-
                 tially water-tight, so regularly spaced weep holes are recommended.

                                                                                  68
<pb n="68" />

                     Figure 32      Steel Sheet Pile Bulkhead

                            BETHLEHEM        FRODINGHAM
                                    Z-SECTIONS

                                     LARSSEN
                                    U-SECTION

                      Figure 33      Steel Sheet Pile Sections
                        [After  Winterkorn and Fang (1975)]

        These, and lifting holes in the piling, should be backed with
        properly graded stone filters or filter fabric to prevent the loss
        of backfill.

             Aluminum. Aluminum sheet pile sections are similar to steel.
        Design and installation are accomplished using conventional methods
        and equipment.    Its primary advantages over steel are lighter
        weight and superior corrosion resistance. Individual sheets can be
        carried and maneuvered by one man, and most drilling and cutting
        can be performed with simple hand tools.     Its main disadvantage,
        compared to steel, is that it is less rugged when driven and cannot
        penetrate logs, rocks or other hard obstructions. Figure 34 is a
        photograph of an aluminum bulkhead.

                                         69
<pb n="69" />

                                   F
                                    57

                                               771

              40'.

                                                              z7____r

                    -A&amp;L

                    Figure 34      Aluminum  Sheet Pile Bulkhead
                     (Photo Courtesy of Koppers Company, Inc.)

             Asbestos-Cement. Sheet piling made of this material has been
        tried in several lo ations.   Indications are that it often suffers
        significant and rapid deterioration in a marine environment
        [Watson, Machemehl, and Barnes (1979) ] and should be used with
        caution when long life is desired.

        Post Supported Bulkheads

             Post supported bulkheads consist of regularly spaced posts,
        usually timber, driven into the ground with an attached facing
        material that forms a retaining wall. The posts,. support compon-
        ents of the bulkhead, resist the exerted earth pressures. As with
        sheet piling, a post supported bulkhead can be - either a cantilever
        or anchored.

             One advantage is that the posts can sometimes be installed
        using only an auger, and the facing material can then be placed by
        hand. The cost of the bulkhead depends on the required spacing of
        the posts, and the type of soil being augured.

                                         70
<pb n="70" />

             Hogwire Fencing and Stacked Bags

             Wave Height Range: Below five feet.

             Hogwire fencing attached to posts can be used to support sand
        bags stacked on the landward side of the fence (Figure 35) to form
        a relatively inexpensive structure.  The sand bags are vulnerable
        to tearing, however, if after being undercut   by toe scour, they
        slide against the hogwire fencing.

              Figure 35      Hogwire Fencing and Stacked Bag Bulkhead

             For best performance, use small-mesh wire with a PVC coating,
        because bare wire fencing tends to cut the bags. Tearing of the
        front row of bags can be prevented by filling them with a sand-
        cement mixture. Burlap bags can be substituted for the more expen-
        sive bags when a sand-cement mixture is used.    The material and
        seams of  all sand-filled bags must be resistant to ultraviolet
        light.

             Place the bottom bags and fencing in a trench excavated to at
        least the  depth of anticipated toe scour.    Anchor or brace the
        posts, or embed them deeply, allowing for loss of support because
        of toe scour. Provide adequate drainage of the retained embankment
        and place stone at the toe of the bulkhead.

                                        71
<pb n="71" />

              Treated Timber

              Wave Height Range: Below five feet.

              Horizontal, pressure-treated planks can be spiked to the
         landward side of posts which are anchored to deadmen or piles in
         the backfill. The planks must be backed   by filter cloth or graded
         stone to prevent  soil losses through the cracks. Riprap toe pro-
         tection should be provided (Figure 36).

                                 Ur
                                             1A

                                                Z41*
                                                     J71@0

                                                    4%

                                                          --A

                       Figure  36      Treated Timber Bulkhead

              Untreated Logs

              Wave Height Range: Below five feet.

              Horizontal, untreated logs can be attached to the landward
         side of posts in areas like the Pacific Northwest where there is an
         abundance of such logs.   The same precautions about adequate toe
         protection and filtering also apply.      However, the large gaps
         between logs make adequate filter design more difficult.       If a
         filter cloth is used, it should follow the log contours so that it
         is not excessively stressed by bridging large gaps. However, it is
         vulnerable to damage or vandalism, which would jeopardize the
         entire structure because of the resulting loss of retained fill.
                                           ,W* @
                                          I'A

                                          72
<pb n="72" />

              Used Rubber Tires

              Wave Height Range: Below five feet.

              Used tires can be strung over two rows of treated posts set in
        a staggered pattern, with the tires abutting each other and         filled
        with gravel (Figure 37). The posts can be tied back to logs         buried
        in the backfill with filter cloth placed behind the tires           before
        backfilling.    Under wave action, the gravel tends to wash         out of
        the tires, and the backfill can then escape. Although used tires
        can generally be obtained free, the      cost of the structure is pro-
        bably comparable to other bulkheads      because of the required close
        post spacing.

                                                  4

                                            M,
                                                V
                                                        P

                 Figure 37        Used  Rubber  Tire and  Post Bulkhead

              Railroad Ties and  Steel   H-Piles

              Wave Height Range: Below five feet.

              Steel H-piles can be driven at regular intervals and railroad
        ties  placed between the flanges of adjacent piles to form a bulk-
        head  (Figure 38). The toe of the structure should be protected by
        armor stone, and proper filtering and granular backfill are needed
        behind the structure. A 12-inch steel channel, welded to the top
        of the H-piles, serves to aline the piles and retain the railroad
        ties.   The structure has performed well and would be particularly
        useful  where subsurface rock prevents driving sheet piling. How-
        ever,  its cost is probably higher than other effective devices.

                                            73
<pb n="73" />

                                                                Wail

                                                  %N,

                                                         rob%,

                                               -ViL IL
                                             7V,
                                   qh Wa

                 Figure 38       Railroad Ties and Steel  H-Pile Bulkhead

          Miscellaneous Bulkheads

               Longard Tu es

               Wave Height Range:   Below five feet.

               A Longard tube is a  patented, woven, polyethylene tube, filled
          with sand at installation (Figure 39) and available in 40- and
          69-inch diameters, and lengths up to 328 feet.       Like sand-filled
          bags, performance depends on the fabric remaining intact, and the
          tube completely filled. When filled, the tube is dense and heavy,
          yet flexible enough to settle if depressions occur. A properly in-
          stalled Longard tube is placed on a woven filter cloth extending
          10 feet seaward of the tube.        A small 10-inch tube, factory-
          stitched to the seaward edge of the filter cloth, settles under
          wave action to provide toe protection.

               The primary advantage of a Longard tube is the ease and speed
          with which it can be filled once equipment and materials are in
          place.   Repairs are possible using sewn-on patches.        The . major
          disadvantage is its vulnerability to vandalism and damage by water-
          borne debris.   A sand-epoxy coating can be applied to      dry tubes
          after filling to provide significantly greater protection by deter-
          ring vandals and preventing puncture holes from enlarging.         This
          coating cannot be applied to wet tubes. However, the tube must not
          be allowed to roll after the coating is applied, as uncoated sur-
          face areas would then be exposed, and distortion of the tube may

                                            74
<pb n="74" />

                         Figure 39       Longard Tube Bulkhead

        .cause the existing coating to flake off. other disadvantages are
         that a large supply of good quality sand is required to fill the
         tube, patented filling equipment must be used, and only specially
         licensed contractors can perform the work.

              The Longard tube depends on its weight to resist overturning
         and on friction to maintain its position.       It is designed to pro-
         tect the toe of the bank from wave attack, and not necessarily to
         resist earth pressures.     The tube should not be placed directly
         against the base of a bank or overtopping waves may continue to
         cause erosion. It should be placed far enough from the toe so that
         overtopping waves will form a sand berm between the tube and the
         bank. Wave energy will be absorbed by this berm, and further bank
         erosion may  be prevented.    Placement of other devices or another
         tube on top, to increase the structure height and prevent overtop-
         ping, is not  recommended.

              Stacked Used Tires

              Wave Height Range: Below two feet.

              Because used tires are readily available at most sites at no
         cost, many have tried to use them for shoreline protection devices.
         The bulkhead on Figure 40 was made with scrap tires interconnected
         (both vertically and horizontally) by galvanized spikes and push-
         nuts. The tires were stacked in a staggered pattern over a filter
         cloth, and granular material was       used both as backfill in low
         areas, and as fill in the tires.       Three rows of galvanized steel
         anchors secured the structure to the beach. The structure progres-
         sively failed because the interconnections between the tires were

                                            75
<pb n="75" />

                                            A

                      Figure 40       Stacked Used  Tire Bulkhead

          inadequate to hold it together.       The gravel washed out of the
          tires, eventually allowing them to   be lifted by waves. This system
          is not recommended in view of better and less costly alternatives.

               This structure illustrates a common problem with using scrap
          tires. While their availability is a strong temptation to use them
          in shore protection devices, tires are extremely rugged, and usu-
          ally cannot be securely fastened together except by considerable
          labor and expense.    In almost all cases, failure results because
          interconnections do not perform as expected.

               Used Concrete Pipes

               Wave Height Range: Below two feet.

               This bulkhead is constructed by standing used concrete pipes
          on end, side-by-side, and then filling them with granular soil
          (Figure 41).   This bulkhead is economical and practical only when
          there is an available supply of used concrete pipes and where a low
          structure is adequate.

               A filter must be provided behind the structure to relieve
          hydrostatic pressures.    If a filter cloth is used, it should be
          forced deeply into the grooves between pipes to avoid ballooning
          and bursting the cloth. The wall should not be more than two pipe
          diameters high without an anchoring system. Also, the pipes should
          be entrenched to provide stability and toe protection.         A con-
          tinuous concrete cap (not pictured) could be cast across the tops
          of all pipes to insure performance as a unit. This type of bulk-
          head may not last long because of possible rapid deterioration of
          the concrete pipes.

                                            76
<pb n="76" />

                     Figure 41      Used Concrete Pipe Bulkhead

        REVETMENTS

             The armor layer of a revetment maintains its position under
        wave action either through the weight or interlocking of the indi-
        vidual units.   Revetments may be classified as flexible, semi-
        rigid, or rigid. Flexible armors, such as quarrystone, riprap, or
        gabions, retain their protective qualities even if the structure is
        severely distorted, such as when the underlying soil settles, or
        scour causes the toe of the revetment to sink. A semi-rigid armor
        layer, such as interlocking concrete blocks, can tolerate minor
        distortion, but the blocks may be displaced if they are moved too
        far to remain locked to the surrounding units. once one unit'is
        completely displaced, such revetments have little reserve strength
        and displacement will generally continue to complete failure.
        Rigid structures may be damaged and fail completely if subjected to
        differential settlement or the'loss of support by underlying soil.
        Grout-filled mattresses of synthetic fabric and reinforced concrete
        slabs are examples of rigid structures.

        Rubble

             Rubble revetments are constructed of one or more layers of
        stone, or concrete pieces derived from the demolition of sidewalks,
        streets and buildings.   Stone revetments are constructed of either
        two or more layers of uniform-sized pieces (quarrystone), or a
        gradation of sizes between upper or lower limits (riprap). Riprap

                                         77
<pb n="77" />

            revetments are somewhat more difficult to design and inspect be-
            cause of the required close control of allowable gradations and
            their tendency to be less stable under, large waves. For that rea-
            son, graded riprap revetments should be used with caution, but they
            are acceptable for the majority of low cost shore protection appli-
            cations.    Quarrystone structures are more easily designed and in-
            spected and are recommended.

                  The primary advantage of a rubble revetment is its f lexibil-
            ity, which allows it to settle into the underlying soil or experi-
            ence minor damage and still continue to function. Because of its
            rough surface, it also experiences less wave runup and overtopping
            than a smooth-faced structure. The primary disadvantage is that
            placement of the stone or concrete armor material generally re-
            quires heavy equipment.

                  To insure good performance, prepare the existing ground to a
            stable slope.     in most cases, the steepest recommended slope would
            be 1 vertical on 2 horizontal (1:2). Fill material should be added
            where needed   to achieve a uniform slope, but it should be free of
            large stones    and should be firmly compacted before revetment con-
            struction proceeds.      Properly sized filter layers should be pro-
            vided to prevent the loss of the slope material through voids in
            the revetment stone. If using filter cloth, an intermediate layer
            of smaller stone below the armor layer may help distribute the load
            and prevent rupture of the cloth.

                  No individual armor unit should be longer than three times its
            minimum dimension.     In other words, avoid using plate-like or cyl-
            inder-shaped pieces; stones should be angular and blocky, not
            rounded.    The toe of the revetment should be located one design
            wave height (but at least three feet) below the existing grade line
            to prevent undercutting.       In lieu of deep burial, a substantial
            sacrificial berm of additional rubble (with filtering) should be
            provided at the toe.

                  Quarrystone and Riprap

                  Wave Height Range: Above five feet (Quarrystone).

                                        Below five feet (Riprap).

                  Stone revetments are a proven method of shoreline protection
            (Figure 42).    They are durable and can be relatively inexpensive
            where there is a local source of suitable armor stone. Quarried
            stone should be clean, hard, dense, durable, and free of cracks and
            cleavages.    Figure 43 shows a typical cross section of a stone
            revetment. The weight of the armor stones should be determined by
            the following formula as given in the Shore Protection Manual
            [U. S. Army'Corps of Engineers (1977c)].
                                                     w H  3
                                                      r
                                        W              1)3 cot  0                    (17)
                                             KD (Sr

                                                78
<pb n="78" />

                                 AIL

                                                                       W'd

                           ELMO&amp;.,,-

                        Figure 42       Quarrystone Revetment

        where W =  weight of an individual armor stone (pounds);
              wr=  unit3weight (saturated surface dry) of the rock (lbs/
                   feet

              H =  wave height (feet);
              S =  specific/grav4ty of the armor stone    (wr/w );  where3 w
              r    64.0 lbs feet   for salt water and 62.4 'Us/feet        Yor
                   fresh water;

          cot 0 =  Slope of the structure expressed as horizontal units/l
                   vertical;
              KD=  Stability coefficient from Table 12.

                                      Table 12

                     Stability Coefficients for Stone Revetments
                           Armor Unit                  KD

                        Quarrystone

                          Smooth rounded               2.1
                                  ngul
                          Rough a    ar                3.5

                        Graded riprap                  2.2

                                          79
<pb n="79" />

                            FIRST UNDERLAYER (STONE WEIGHT=W/10)

                                    ARMOR (2 LAYERS)
                                    (STONE WEIGHT =W)

                                                         NOTE.' Use either stone or
                                                              filter fobric(Both are
                                                              shown to illustrate
                                                              their use -only one is
                                                               needed)

            GRADED STONE                                                     MLW
            FILTER (IF USED IN
            PLACE OF FILTER FABRIC)

                                                                    TOE PROTECTION-
                                                                    BURY AT LEAST
                                                                    THREE FEET OR
                                                                    ONE DESIGN WAVE
                                FILTER FABRIC (IF                j  HEIGHT BELOW THE
                                (IF USED IN PLACE OF                BOTTOM
                                GRADED STONE FILTER

                       Figure 43        Typical Quarrystone Revetment

                Tables 13, 14, and 15 contain solutions for Equation 17 with
           an illustrative example of their use.

                If uniform guarrystone is used, the individual stones should
           range from 0.75W to 1.25W with 75 percent of the stones weighing W
           or more.    For graded riprap, W corresponds to W        50      and the
           recommended gradation is 3.6 W    5.0 to 0 -22 W      RlpraVlrhhould be
           limited to areas where the de!.@_3:gn wave hei'gCn)t' is less than five
           feet.

                If a graded stone filter is employed, it may be significantly
           more fine-grained than the armor layer. This may require the use
           of an intermediate layer of stone between the armor and the filter.
           This layer -should consist of units about 1/10 the weight of stone
           in the armor layer.     This intermediate layer is also recommended
           when a filter cloth is employed because it provides bedding and.
           resists tearing or puncturing of the cloth under the heavy armor
           stone.

                Concrete

                Wave Height Range: Below five feet.

                A concrete rubble revetment utilizes. a waste product that is
           otherwise difficult to dispose of in an environmentally acceptable
           manner. The concrete should have the durability to resist abrasion
           by water-borne debris and ice pressure.       In addition, all protrud-
           ing reinforcing bars should be burned off prior to placement.
           Numerous concrete rubble revetments have failed in the past, but

                                              80
<pb n="80" />

                      TABLE 13                         TABLE 14                        TABLE 15
                 ESTIMATED WEIGHT                         CORRECTION                CORRECTION FOR

                  OF ARMOR STONE                          FOR SLOPE                      UNIT WEIGHT

                WAVE           ESTIMATED SLOPE                CORRECTION             UNIT       CORRECTION
               HEIGHT             WEIGHT                           FACTOR         WEIGHT           FACTOR
                    H                 W                                              Wr
                  (f 0               0b)           (ft/ft)             K I         0b/ft3)              K 2

                  0.5                    1          1:2                1.0           120                4.3
                  1.0                   10          1:2@               0.8           130                2.8
                  1.5                   20                            -0.7           135                2.4
                                                0
                                                 'eel: 3  mmmelillOw
                  2.0                   50          1: 3@              0.6           140                2.0
                  2.5                 100   #4      1: 4               0.5           145                1.7
                  3.0 mmmmENSP-1 60**               1: 4@              0.4           150                1.5
                  3.5                 260           1: 5               0.4           155mmmogwo-1.3
                  4.0                 390           1: 5@              0.4           160                1.1
                  4.5                 550           1: 6               0.3           165                1.0
                  5.0                 750                                            170                0.9
                  5.5                1000                                            175                0.8
                  6.0                1300                                            180                0.7
                  6.5                1650                                            185                0.6
                  7.0                2100                                            190                0.6

                 EXAMPLE

                GIVEN.' The wave height (H) is 3.0 feet and the structure
                           slope is 1 on 3 (1 Vertical on 3 Horizontal) and one
                           cubic loot of rock weighs 155 lbs (wr)

                  FIND:
                           The required weight of armor stone (W) from the
                           tables (Dashed Line)

                                      W = 160 lbs x 0.7 x 1.3 = 145 lbs

                                                               81
<pb n="81" />

          this has generally been attributable to neglect of f ilter require-
          ments.   Figure 44 shows two cross sections that would probably be
          more sucessful than random dumping on a slope. The upper section
          uses three layers of concrete rubble, shaped so that the longest
          dimension is no greater than three times the shortest, thus in-
          creasing stability and minimizing uplift on the slabs from wave
          forces. The revetment shown on Figure 45 is similar, except only
          one layer of rubble was used.      It subsequently suffered damages,
          but more than one layer of rubble may have improved its perfor-
          mance.   The lower 'section on Figure 44 utilizes shaped-rubble
          stacked on a slope to create a stepped face.

                            3 LAYERS OF
                            CONCRETE RUBBLE

                                                                       MHW

                   FILTER
                   CLOTH
                                                             N\-EXISTING
                                                                 GROUND LINE

                       FILTER.                                            MHW
                       CLOTH

                                                          EXISTING
                                                          GROUND LINE

                   Figure 44      Concrete Rubble Revetment Sections

          Concrete Blocks

               Concrete blocks for semi-rigid armor layers are designed with
          various intermeshing or interlocking features, and many of the

                                            82
<pb n="82" />

                                                                    . . ..... ... . . ....

                                                                    77

                                 AVI

                     77

                                 IL

                     Figure 45       Concrete Rubble Revetment

       units are patented (Figure 46).      Blocks have the advantage of a
       neat, uniform appearance. Many units are light enough to be in-
       stalled by hand once the slope has been prepared. The disadvantage
       of concrete blocks is that the interlocking feature between units
       must be maintained.     once one block is lost, other units soon
       dislodge, and complete failure may result. A stable foundation is
       required since settlement of the toe or subgrade can cause dis-
       placement of the units and ultimate failure. Also, some concrete
       block revetments have smooth faces that can lead to significantly
       higher wave runup and overtopping.

            Gobi (Erco) and Jumbo Blocks and Mats

            Wave Height Range: Below five feet (blocks).

                                 Above five feet (mats).

            Gobi blocks are patented units that weight about 13 pounds
       each. Erco blocks are similar but they are offered by a different
       licensed manuf acturer.   Jumbo blocks are large-sized Erco blocks
       that weigh about 105 pounds each.        The units are designed for
       hand-placement on a filter cloth or they are factory-glued to
       carrier strips of filter cloth.      The latter are called Gobimats

                                         83
<pb n="83" />

                                                                  COBBLETOP

                                                                                  15

                                                                                                                                                               2

                                                                  FILTER FABRIC

                                      JUMBO BLOCK                         GOBI (ERCO)         BLOCK                         SHIPLAP BLOCKS

                                                                 4

                                                                                                                       55/e
                                                                                        2.5'

         00                             MONOSLAB
                                      (TURFBLOCK)                                 NAMI RING
                                                     161-                                                                      LOK-GARD BLOCK

                                                                     8"

                                                           CONTROL BLOCKS
                                                                                                                                                      3.0

                                                                         16"

                                                         8                                                             1.55"R(TYP)
                                                                                                                3.3"R(TYP)
                                                                                                                 4.5"R(TYP)
                                                 STANDARD CONSTRUCTION BLOCK                                              TERRAFIX BLOCK
                                                                    Figure 46                Revetment         Blocks'
                                                                              ic@

                                                                                                                                                  R-3

                                                        [After U.S. ArMy Corps of Engineers (1981d)]
<pb n="84" />

       (Etcomats) or Jumbo Ercomats, depending on the size of the units.
       If the blocks are glued to both sides of the carrier strip, back-
       to-back, they are called double Gobimats (Ercomats) or double Jumbo
       Ercomats. Mats are preferred at sites where vandalism or theft is
       possibile. Both single and double mats require machine placement.

            Block and mat revetments have generally performed well.         A
       large project on the Gulf of Mexico in Louisiana has weathered
       several hurricanes and tropical storms with only moderate damage to
       the block sections and little or no damage to the mat        portions.
       Figure 47 is a photograph of an existing revetment.

                                        41     vll@

                                                        7777,"

                         Figure 47       Ercomat Revetment

            Turfblocks or Monoslabs.

            Wave Height Range: Below five feet.

            Turfblocks are designed for hand placement on a f ilter with
       the long axis parallel to the shoreline (Figure 48).       Each block
       measures 16 x 24 x 4.5 inches and weighs approximately 100 pounds.
       Field installations have not yielded conclusive results, but their
       performance should be similar to Jumbo Erco blocks.       Their thin,
       flat shape requires a stable foundation, as any differential set-
       tlement beneath the blocks makes them susceptible to overturning
       under wave action.

                                         85
<pb n="85" />

                          law",

                          lw@

                               W"M             pad
                                         000.

                         AO* AMW
                             44%,
                            4A __                           I t -., -*__
                                       *"I'-                     *rft@
                                                  @@Zl Pba           0   t n
                                                            t

                          Figure 48      Turfblock Revetment

              Nami Rings

              Wave Height Range: Below five feet.

              The Nami Ring is a patented concrete block shaped like a short
         section of concrete pipe, 2.5 feet in diameter by 1-foot high, and
         weighing 240 pounds.    The rings are placed, side-by-side, on a
         slope over filter cloth. Better performance has been observed when
         the rings are joined together with tie rods. Sand or gravel caught
         up in the wave turbulence tends to be deposited inside the rings
         and in the'voids between adjacent rings, adding to the stability-of
         the section and protecting the filter cloth.      Because of their
         shape, Nami Rings are susceptible to severe abrasion and damage by
         water-borne cobbles and, therefore, should be used primarily in
         sandy environments.

                                          86
<pb n="86" />

              Control Blocks

              Wave Height Range: Above five feet.

              Control blocks come in various sizes and are similar to stand-
        ard concrete construction blocks, except that protrusions in the
        block ends provide a tongue- and-groove interlock between units.
        Designed to be hand-placed on a filter cloth with the cells ver-
        tical, the blocks can be alined with their long axes parallel to
        shore, but optimum     performance   probably results from placement
        perpendicular to the water's edge    (Figure 49).

                            PIZ

                                                         Figure 49
                                                 Control  Block Revetment
                                  Awe
                        IV
                                                 (Note:   Perpendicular orienta-
                                                 tion of  blocks with the water-
                                                 line   is preferred over the
                                                parallel orientation shown in
                                                 this photograph.)

              4
              K

              Concrete Masonry Blocks

              Wave Height Range: Above five feet.

              Standard construction masonry blocks should be hand-placed on
        a filter cloth with their long axes perpendicular to the shoreline
        and the hollows vertical. Their general availability is a primary
        advantage, but they are highly susceptible to theft. They form a
        deep, tightly fitting section which is stable provided the toe and
        flanks are adequately protected.        Their primary disadvantage is
        that standard concrete for building construction is not suffi-
        ciently durable to provide more than a few years service in a
        marine environment.     Special concrete mixes should be used when
        possible

                                           87
<pb n="87" />

                               Shiplap Blocks

                               Wave Height Range: Below five feet.

                               Shiplap- blocks are formed by joining standard concrete patio
                     blocks with an epoxy adhesive.                                      At 100 pounds or more per unit,
                     they are designed for hand placement on a filter. The same precau-
                     tions about concrete mixes apply here. These blocks are discussed
                     in Hall and Jachowski (1964). 'A photograph                                                  and     cross-section of
                     one revetment are shown on Figures 50 and 51.

                                                                                                                                       ki

                                                                                     E,
                                                                                          4
                                                                                                          "74       M'
                                                                                                                                       A

                                                                                         K

                                                                             N,A

                                                 Figure 50                     Shiplap Block Revetment

                                                                                                                                  Wood railing

                                                       16                                                                         Concrete sidewalk
                                                                                                                                    3'- d' x 6" thick

                                                                                        Original ground line,
                                EPOXY
                                Glued
                                 Joint
                                                                  ts-
                                           C                      Z-
                                         Concrete Block Detoils                                                Woven plastic filter cloth

                                          MLW
                                   -Z@Stone     toe protection--_&gt;                                 6' Layer    to 12 stone

                                 2" x 6" Timber
                                                         Toe cutoff wall would be required
                                                          for a sand beach.

                                          Figure        51              Shiplap Block Revetment Section
                                                 [U.S. Army Corps of Engineers (1977c))

                                                                                      88
<pb n="88" />

             Lok-Gard Blocks

             Wave Height Range: Below five feet.

             Lok-Gard blocks join together using a tongue-and-groove system
        (Figure 52).    The 80-pound,   patented units are designed to be
        hand-placed on a filter with their long axes perpendicular to the
        shoreline.   Since a Lok-Gard revetment has a smooth surface, in-
        creased runup heights must be  considered in the design.

                                             01

                                           TK&gt;

                                                  ItT

                       Figure 52       Lok-Gard Block Revetment

             Terrafix Blocks

             Wave Height Range: Above five feet.

             Terrafix blocks are patented units that join together with a
        mortise and tenon system, and have two cone-shaped projections
        which fit holes in the bottom of the adjacent block (Figure 46).
        In addition, holes through the center of each block allow for
        stainless steel wire connection of many individual blocks.          The
        uniform interlocking of the 50-pound units creates a neat, clean
        appearance (Figure 53).

             Stacked Bags or Mats

             Wave Height Range: Below five feet.

             Several manufacturers produce bags and mats in various sizes
        and fabrics that are commonly filled with either sand or a lean

                                          89
<pb n="89" />

                                                       Figure 53
                                                Terrafix Block Revetment

                                              (Photo Courtesy of Erosion
                                                     Control Products, Inc.)

          mixture of concrete for use in revetments. While no special equip-
          ment is required for sand-filled units, a mixer, and possibly a
          pump, are needed for concrete-filled units. Bags should be filled
          and stacked against a prepared slope with their long axes parallel
          to the shoreline and joints offset as in brick work (Figure 54).
          Grout-filled bags can be further stabilized by steel rods driven
          through the bags.

               The advantage of a bag revetment is its ease of construction
          and moderate cost.   Sand-filled bags are relatively flexible and
          can be repaired if some of the original bags are dislodged.        In
          addition, stacked bag's are suitable as temporary emergency protec-
          tion measures. Among their disadvantages, they are limited to low
          energy areas, have a relatively short service life compared to
          other revetments, and generally have an unattractive appearance.
          Since concrete-filled structures are rigid, any movement or dis-
          tortion from differential settlement of the subgrade can cause a
          major failure that would be hard'to repair.    Sand-filled bags are
          highly susceptible to damage and possible failure from vandalism,
          impact by water-borne debris and deterioration of material and
          seams by sunlight.    The smooth, rounded contours of bags also

                                          90
<pb n="90" />

                               I uclw
                                         low*

                      Figule 54      Stacked Bag Revetment

           Fig ure 55     Grout-Filled Mattress (Fabriform) Revetment
                (Photo Courtesy of Construction Techniques, Inc.)

       present an interlocking problem and they should be kept flatter and
       underfilled for stability.

            Mattresses are designed to be laid flat on a prepared slope,
       joined together, and then filled (Figure 55).    They form a large
       mass of pillow-like concrete sections with regularly spaced filter
       meshes for the passage of water. They should always be installed
       according to the manufacturer's recommendations.

                                       91
<pb n="91" />

                Bags or mattresses should be placed only on a stable slope.
           While a stacked bag revetment can be placed on a steeper slope than
           a mattress, it should not exceed 1 vertical on 1.5 horizontal. A
           stacked bag revetment should be at least two bags thick, preferably
           with the outside layer concrete-filled and the interior bags sand-
           filled.   When sand is used as filler material, the bag or mat
           fabric, and its seams, must be resistant to ultraviolet light.
           Figure 56 shows a nonstabilized bag after six months of exposure.
           Where vandalism or   water-borne  debris are likely, only     concrete-
           filled units should be  used.

                                             Al

                               7,

                                         AF

                                             AW

           Figure 56       Deterioration of Sand   Bags Under Ultraviolet Light

                Some  form of toe protection should     be provided, or the toe
           should be buried well below the anticipated scour depth. Also, an
           adequate  filter system, such as a properly installed and sized
           filter cloth, should be installed.

                some types of bags and mats which have been used in the past
           are described below.

                     Burlap Bags.    Burlap bags are recommended only when
                filleT @witn concrete because of rapid deterioration in the
                shoreline environment and the ease with which they can be
                torn.

                     Sand Pillows.    Sand Pillows are ultraviolet-resistant
                bags made from a woven acrylic fabric.       They weigh approxi-
                mately 100 pounds when filled. Because of their resistance to
                sunlight, they are suitable for sand-filling in some areas.

                                             92
<pb n="92" />

                  Dura BacLs. Dura Bags are large (4 x 12 x 1. 7 feet), and
             must be filled in place using a pumped sand-slurry or con-
             crete. Their large size makes them more resistant to movement
             under wave attack. Fabricated of ultraviolet-resistant mater-
             ial, they can be used in installations exposed to sunlight.

                  Fabriform Nylon Mat.    The mat is designed to be filled
             with a highly fluid, lean-cement mixture. The exterior cloth
             envelope serves primarily as a form until the grout hardens.
             Fabriform is a patented product, available in several fabric
             styles, including some with filter points (weep holes) to
             provide slope drainage.     Fabriform mats should be installed
             according to the manufacturer's instructions.

        Miscellaneous

             Gabions

             Wave Height Range: Above five feet.

             Gabions are rectangular baskets or mattresses made of gal-
        vanized, and sometimes PVC-coated, steel wire, in a hexagonal mesh
        (Figure 57).    Subdivided into approximately equal sized cells,
        standard gabion baskets are 3 feet wide, and available in lengths
        of 6, 9 and 12 feet and heights of 1, * 1. 5 and 3 feet. Mattresses
        are either 9 or 12 inches thick. At the job site, the baskets are
        unfolded and assembled by lacing the edges together with steel
        wire. The individual baskets are then wired together and filled
        with 4- to 8-inch diameter stone. The lids are finally closed and
        laced to the    baskets,  forming a large, heavy    mass (Figure 58).

                 &amp;

                                  e4
                                      461@*

                         Figure 57       Unassembled Gabions

                                          93
<pb n="93" />

                               41

                                                    -, Va",

                           Figure 58      Gabion  Revetment

              One advantage of a   gabion  structure is that it can be built
         without heavy equipment.    Gabions are flexible and can maintain
         their function even if    the foundation settles.   They can be re-
         paired by opening the baskets, refilling them, and then wiring them
         shut again.

              The disadvantage of a gabion structure is that the baskets may
         be opened by wave action.       Also, since structural performance
         depends on the continuity of the wire mesh, abrasion and damage to
         the PVC coating can lead to rapid corrosion of the wire and failure
         of the baskets.    For that reason, the baskets should be tightly
         packed to minimize movement of the interior stone and subsequent
         damage to the wire.    Rusted 4nd broken wire baskets also pose a
         safety hazard.   Gabion structures require periodic inspections so
         that repairs are made before serious damage occurs.

              To insure best performance, use properly sized filler rock.
         Interior liners or sandbags to contain smaller sized material are
         not recommended.   The baskets should be filled tightly to prevent
         movement @of the stone and they should be refilled as necessary to
         maintain tight packing.

              Gabions should not be used where bombardment by water-borne
         debris or cobbles is present, or where foot traffic across them is
         expected..

                                          94
<pb n="94" />

              Steel Fuel Barrels

              Wave Height Range: Below five feet.

              This type of revetment is limited to remote areas with an
        abundance of used fuel barrels of little salvageable value (Fig-
        ure 59). Due to rapid corrosion of the barrels in warm water, the
        system is only reliable in arctic regions. The barrels should be
        completely filled with coarse granular material to preclude damage
        by floe ice and debris, and the critical seaward barrels should be
        capped with concrete.      Also,  partial burial of the barrels in-
        creases stability.

                   ,low"

                     Figure 59        Steel Fuel Barrel Revetment

              Concrete Slabs

              Wave Height Range: Below five feet.

              Photographs of a typical structure were shown on Figure 20.
        The structure failed for a number of reasons, including improper
        filtering, inadequate toe protection, and lack of flank protection.
        Placed on a flatter slope, and with due regard for proper design
        considerations, this type of structure can provide low cost protec-
        tion when large   slabs are available.

              Fabric and  Ballast

              Revetments  using a fabric filter cloth as the slope's armor
        layer, held in    place by some form of ballast, have not been suc-
        cessful and are   not recommended.

                                           95
<pb n="95" />

          BREAKWATERS

               Breakwaters are either floating or fixed.         Floating break-
          waters function at or near the water's surface and must be firmly
          anchored to prevent displacement. Fixed breakwaters are construct-
          ed on the bottom and may or may not pierce the water's surface.
          When they do not, they are called sills.    Their height and porosity
          determines how effectively they dissipate   wave energy.

               By trapping sand on their landward     side, breakwaters protect
          the shore while simultaneously enhancing    recreational uses. Unlike
          groins, they are able to trap sand moving   both parallel and perpen-
          dicular 'to shore.    Unfortunately, this   sand-trapping (accreting)
          ability can also cause erosion of downdrift beaches. In most cases
          heavy construction equipment, often barge mounted, is necessary for
          breakwater construction.

          Floating Breakwaters

               Wave Height Range: Below five feet.

               Floating breakwaters can be constructed of virtually any
          buoyant material such as rubber tires, logs, timbers, and hollow
          concrete modules.    Floating breakwaters are particularly advan-
          tageous where offshore slopes are steep and fixed breakwaters would
          be expensive because of deep water.      They can also be used where
          the tidal range is large and fixed breakwaters would be subjected
          to widely varying degrees of submergence. Floating breakwaters are
          also excellent for temporary installations, such as where vegeta-
          tion requires protection while becoming established.

               Floating breakwaters have several disadvantages as well. They
          are effective only against short-period waves (less than five
          seconds), which are those most commonly present in sheltered loca-
          tions where low cost protection is most appropriate.        Also, they
          may regarded as eyesores in some areas, they tend to collect float-
          ing debris, and they may require more maintenance than fixed break-
          waters.

               Rubber Tires.    Two possible arrangements are shown on Fig-
          ure 60. The upper configuration, known as a Wave-Maze, is patented
          and cannot be used without payment of royalties (See Other Help
          Section).   The bottom configuration was developed by the Goodyear
          Tire and Rubber Company for promotional purposes and may be used
          without royalties. The use of other configurations is limited only
          by the imagination of the designer.

               The basic elements of design for floating tire breakwaters are
          listed below.

                     Length.   The length parallel to shore should be suf-
               f
                    'E
                icie t- to provide the desired protection and will vary with
               the structure's distance from shore.

                                            96
<pb n="96" />

                             NCHOR
                             CHAIN

                                  WAVE-MAZE                                 +
                                   DESIGN

                                                                             BOLTS

                                If

              Ff It

                                BAY

                             GOODYEAR
                              DESIGN

                    Figure 60         Floating Tire Breakwater Modules
                     [After U.S. Army Corps of Engineers (1978b)]

                                                97
<pb n="97" />

                    Width.  The width should be chosen to yield a satisfac-
              tory decrease in the transmitted wave height (the wave height
              behind the structure). No definite criteria would apply, but
              wave height reductions of 30 percent may be an acceptable
              starting point for design.       This would reduce the energy
              reaching the protected shoreline to about 49 percent of that
              of the incident waves (0.7 x 0.7=0.49).       if later experience
              shows this to be an unsatisfactory or excessive level of pro-
              tection, the breakwater can be made wider or narrower by
              adding or removing modules, or its distance from shore or
              length can be changed.

                    The design breakwater width is a function of the wave-
              length at the site. With a known water depth and wave period,
              the wavelength can be found using either Figure 26, or Equa-
              tion (3).   Figure 61 gives the wave transmission coefficient,
              K    as a function of the design wave height. The transmitted
              W@@e height is determined by multiplying the incident wave
              height by K     For instance, if the local wavelength, L, is 80
              feet, and V breakwater width, W         of 40 feet is proposed,
              W /L is 0.50, and K is 0 90.      I?tLe incident wave height is
              5@@ feet, the translitted* wave    will be 4.5 feet. This wave
              will contain 0.9 x 0.9, or 81     percent of the energy of the
              incident wave.    This may not be a satisfactory level of pro-
              tection in many cases.

                    Draft.   Increased depth of penetration in the water
              column increases the effectiveness of floating breakwaters.
              In general, the draft should be greater than one-half the
              design wave height. Two-layer structures or the use of truck
              or tractor tires will achieve greater draft.

                    Flotation.   The air trapped within the top of vertical
              tires provides sufficient flotation in most cases.       In quiet
              water, the air is eventually dissolved by the surrounding
              water and the structure sinks.       wave action, however, re-
              plenishes the air supply, but care must be taken not to use
              tires with puncture holes.     More permanent flotation is pos-
              sible with styrofoam blocks or foam injected into the crowns
              of the tires.    In salt water, marine growth that is not peri-
              odically removed will eventually sink the structure.           Sand
              also collects in the tires and can sink them, but this can be
              prevented by drilling holes in the bottoms of the tires.         In
              that case, flotation aids such as styrofoam blocks should be
              used.

                    Fastening Materials.    Stainless and galvanized steel
              cable; polypropylene, nylon, Poly-D and Kevlar rope; gal-
              vanized and raw steel chain; and rubber conveyor belt edging
              have been used for tying tires together.       Davis (1977) pre-
              sented the results of tests using all of these, and found that
              conveyor belt edging was the most satisfactory.        The others
              failed because of either corrosion, abrasion by the tires,
              fatigue, or deterioration from other factors.        Steel cables
              sawing through the tires have caused some, devices to fail.

                                            98
<pb n="98" />

              1.20

              1.00                                                                        100

              0.80                                                                        64

                                                                                               M
                                                                                               z
                                                                                               M
           0 0.60                                                                         36

     @10
           0

           0

                                                                                               z
           E 0.40                                                                          16

                                                                                               rn
                                                                                               0
              0.20                                                                         4

                                                                                           0
                 0       0.20     OAO      0.60     0.80     1.00     1.20     1.40
                                Ratio of Breakwater Width to Wavelength'(Wst/L)
                        Figure 61     Transmitted Wave Height Versus structure Width
                                       [Giles and Eckert (1979)]
<pb n="99" />

              Rubber belt edging, a scrap material derived from the manufac-
              ture of conveyor belts, is available from several rubber
              companies and comes in a wide range of widths and thicknesses.
              For tire breakwater construction, the belting should be at
              least 2 inches wide and 0.375 inches thick.

                   Anchorage.   Floating tire breakwaters must be securely
              ancho:Fe-dto prevent displacement. Mooring loads can be deter-
              mined from Figure 62. Danforth and other embedment anchors,
              as well as screw anchors and large concrete blocks, have been
              used with mixed results.    They are probably best suited for
              seasonal use in a mild wave climate, but they tend to creep
              over long periods in soft bottoms and are not always desirable
              for permanent installations. In those cases, driven piles are
              generally the best means of stable anchorage over long peri-
             .ods.  Giles and Eckert (1979) provide guidance on anchorage
              systems.

                   Other Materials. other floating materials can be used in
              place of scrap rubber tires. Bundles of logs can be chained
              together or other barriers can be fabricated from treated
              timber. Modules of lightweight concrete filled with flotation
              foam have also been successful. The proportioning and design
              factors presented for rubber tire breakwaters would also apply
              to these.

         Fixed Breakwaters and Sills

              An important feature of a fixed breakwater is its height,
         which determines how much wave energy passes over the structure.
         In building a fixed breakwater, some settlement should be antici-
         pated in the structure's design height, the actual amount being a
         function of the soil type, the weight of the structure, and type of
         foundation.

              Longard Tubes

              Wave Height Range: Below five feet.

              The advantages and disadvantages of Longard tube bulkheads
         generally apply to breakwaters. An added disadvantage is that the
         protective epoxy coating cannot be applied to wet tubes so that
         damages are more likely. Therefore, they should not be used where
         the tube may be exposed to vandalism or water-borne debris. Fig-
         ure 63 contains before and after views of a Longard tube slashed by
         vandals, eventually causing it to entirely deflate.

              The tube should be installed over a layer of synthetic filter-
         cloth with factory-sewn, 10-inch Longard tubes on each edge to
         reduce the potential for failure due to toe or heel scour. Where a
         69-inch tube cannot provide sufficient height, an alternate break-
         water system should be used.

                                          100
<pb n="100" />

                    120

                    100

                    80

                 V

                    60
                 C

                  0040

                    20

                                                                  [Giles and Eckert (1979)]
                      0
                      0                                                       4            5
                                              Incident Wave Height (ft.)
                         Figure 62       Mooring Loads for Floating Tire Breakwaters
<pb n="101" />

                                                    8 march 1979

                                        00
                                    7

                                                 F15 November 19791

                                                                 A
                                     Figure 63
               Before and After Views of a Longard Tube Breakwater

             Sand-Filled Bags

             Wave Height Range: Below five feet.

             Sand-filled bag breakwaters are constructed of stacked bags in
        a staggered pattern (Figure 64).   The integrity of the structure

                                        102
<pb n="102" />

                     Figure 64       Sand-Filled  Bag Breakwater
        depends on the individual bags remaining in place and intact. The
        bags and seams must be resistant to ultraviolet light to preclude
        deterioration from prolonged sunlight exposure. They should not be
        used where vandalism is expected or where the structure will be
        exposed to water-borne debris.      Lighter bags (100-pound range),
        like those used for revetments, are displaced when exposed to even
        moderate waves.    Larger units, such as Dura Bags, are recommended
        even through they are more difficult to handle and require filling
        in place.

             A filter cloth should be placed under the bags to reduce
        settlement in soft bottoms (Figure 65).         During construction,
        bag-to-bag abutment should be insured to minimize wave transmission
        through gaps between bags.

                                                     12-FOOT LONG NYLON SANDBAG

                                  1. 7'                          _?1HW

                 ANCHOR
                 SANDBAG

                     FILTER CLOTH                     10,
                                          201
                                           4

                     :G

                 Figure 65       Sand-Filled Bag Breakwater Section
                   [After U.S. Army Corps of Engineers (1978c)]

                                          103
<pb n="103" />

               Grout-Filled Bags

               Wave Height Range: Below five feet.

               The major advantage of grout-filled bags is that the units
          hold their shape after the fabric deteriorates or is torn. Again,
          use of larger bags is recommended because the smaller ones are
          susceptible to displacement.    In addition, larger units reduce the
          number of bag contact points where openings may develop.

               The recommendations made for sand-filled bags also apply to
          grout-filled bags, except that vandalism is not a major concern.

               Gabions

               Wave Height Range: Below five feet.

               The same basic design considerations for gabion revetments
          also hold here.    The wire mesh should be PVC-coated, the baskets
          should be tightly packed, and a filter cloth should be used beneath
          the structure to help control settlement. A gabion mat should be
          provided around the structure to protect against scour.           Tight
          packing of the stone is particularly important to avoid large
          distortion of the baskets under wave action.         A typical cross
          section and photograph of a gabion breakwater are shown on Fig-
          ures 66 and 67.

                                        18'_O
                    2'-0         9-0                 7'-Ok'
           wire              -0     3'- 0" 2'-d'
           Mes

                                                  OFFSHORE
                                                    SIDE

                                                                 DESIGN WATER
                                                Stone            LEVEL
           0

           (.0

                                              Existing Lake Bottom@@J
                                              (depth from take bottom to bedrock varies)

                   Figure 66      Typical Gabion Breakwater Section
                    [After U.S. Army Corps of Engineers (1978a)]
                                                S

                                           104
<pb n="104" />

                             At

                        Figure 67     Gabion Breakwater

            Z-Wall

            Wave Height Range: Above five feet.

            A Z-Wall is a patented device constructed with reinforced
       concrete panels set on edge in a zigzag fashion (Figure 68). The
       structure is designed  for placement close to the shore on the

                                                . ...... ...
                       Figure 68      Z-Wall Breakwater

                                      105
<pb n="105" />

          existing bottom without the use of a filter. A single bolt acts as
          a hinge that interconnects adjacent panels and allows for non-uni-
          form settlement, but with limited tolerance; so that Z-Walls are
          sensitive to bottom conditions.     If the tolerable differential
          settlement is exceeded, the panels tend to lean against or pull
          apart from each other, causing the concrete to spall in stressed
          areas. The nuts on the connecting bolts tend to unwind under wave
          agitation, and should be inhibited by the use'of double nuts and
          destruction of the exposed threads behind the nuts. Otherwise, the
          end units may fall away if the nuts unwind completely.

              The Z-Wall performs best at a site with a firm bottom. The
          six-foot panel height limits its use to relatively shallow water.

              Surgebreaker

              wave Height Range: Above five feet.

              A Surgebreaker is a modular device constructed with patented,
          3,700-pound, precast, reinforced concrete modules (Figure 69) with
          vent holes to release wave pressure buildup. The triangular mod-
          ules are 4 feet high and 7 feet wide -    They are designed to be
          placed side-by-side on the existing bottom with the flatter sloped
          face of the device toward the waves (Figure 70).

                                   V

                                                          4A

                                        4.2,

                         Figure 69      Surgebreaker Modules

                                          106
<pb n="106" />

          iJ"
                                                         '@gzl

                                                                      qe

               R,

                     Figure 70      Surgebreaker Breakwater

            Sandgrabber

            Wave Height Range: Below five feet.

            A patented configuration of interconnected concrete construc-
       tion blocks (Figure 71), the Sandgrabber is a device that allows

                                                     4,

                           Figure 71      Sandgrabber

                                       107
<pb n="107" />

          for some differential settlement of the blocks by using U-shaped,
          galvanized-steel connecting rods. The hollow blocks allow waves to
          wash sand through, trapping the coarser, water-borne particles
          behind the structure.     The Sandgrabber must be installed by a
          franchised contractor.

               The current design does not use any form of toe protection,
          nor is the structure placed on a filter. As a result, the struc-
          ture normally settles unevenly and rotates seaward into a scour
          trench.  Because of these movements, the allowable amount of dif-
          ferential settlement is sometimes exceeded and the resulting stress
          of the U-ties against the concrete blocks may crack or break them.
          This can eventually lead to complete collapse of the structure.
          Weak concrete hastens the process, so compressive strength tests
          should be performed on each batch of blocks before construction. A
          precaution when using a Sandgrabber, or any other breakwater, is to
          avoid downdrift erosion damages.       Backfilling with sand should
          prevent any potential problems.

               Quarrystone

               Wave Height Range: Above five feet.

               A stone breakwater is structurally similar to a stone revet-
          ment (Figure 72) and stone sizes should also be selected by using
          Equation (17).   However, the stability coefficient, K   D   should be
          selected from Table 16, rather than Table 12.

                                                                    %V

                                         IrA

                                                  _'T
                                                     AT
                                                                  04

                   r

                         Figure 72       Quarrystone  Breakwater

                                           108
<pb n="108" />

                                       Table 16

                            KD VALUES FOR STONE BREAKWATERS

                                                       Structure
                                    Structure Trunk    Head (End)     Slope
              Armor        Layers          KD              K D        cot 0

        Quarrystone
          Smooth rounded     2             2.1             1.7      1.5 to 3.0

          Rough angular      2             3.5             2.9      1.5
                                                           2.5      2.0
                                                          12.0     13.0

        Graded riprap              Not Recommended

             A major advantage of a quarrystone breakwater is that the
        structure does not necessarily fail when differential settlement
        occurs. Through the years, stone has been used for more breakwater
        construction than any other material. It is time-tested and can be
        quite economical if suitable rock is available locally.

             Timber Piles and Brush

             Wave Height Range: Below two feet.

             A brush breakwater is constructed of two parallel rows of
        posts driven into the offshore bottom, connected across the top
        with timber crossties, and filled with brush. Brush should be cut
        longer than the space between the posts and placed parallel to the
        structure alinement.    Not suitable for permanent protection, this
        breakwater can be used for temporary sheltering of young vegeta-
        tion.

             Used Tires and Timber Piles.

             Wave Height Range: Below two feet.

             Timber piles can be driven into the bottom, so that every
        three piles form a triangular pattern, and used automobile tires
        can then be stacked on the piles. Just above the top tires, the
        triangularly grouped piles should be interconnected using 2 x 6-
        inch planks bolted to the piles (Figure 73). The structure, whose
        stability depends on the depth of pile penetration, has proven
        effective against mild wave action.

                                          109
<pb n="109" />

                 Figure 73      Used Tire and Timber Pile Breakwater

         GROINS

              Important design considerations for groins include their
         height, length, spacing (if there are more than one) and the lit-
         toral transport rate. Their height determines how much sand can
         pass over the structure.   Low groins, which essentially follow a
         foot or two above the natural beach profile, are widely used be-
         cause they stabilize the beach but do not trap excessive amounts of
         sand and thereby cause downdrift damages. The groin length should
         not extend past the breaker zone or else it may force the bypassing
         sand too far offshore and cause downdrift erosion damages.       The
         groin spacing should generally be two or three times the groin
         length.

              Groins can be built as sheet pile structures that depend on
         ground penetration for support, or as gravity structures that
         resist movement solely because of their weight. In either case, it
         is essential to prevent or adequately plan for bottom scour.     For
         sheet pile structures, scour reduces their amount of embedment and
         makes them vulnerable to tipping.     Rigid gravity structures can
         settle unevenly and be damaged if undermined by scour.

                                         110
<pb n="110" />

       Stacked Bags

            Wave Height Range: Below five feet.

            A stacked bag groin is similar to a stacked bag breakwater
       (Figure 74).   The bags can either be sand- or grout-filled.          As
       with breakwaters, larger bags are recommended because lighter,
       smaller bags are too susceptible to displacement.        The recommen-
       dations for bag breakwaters also apply to groins. The bags in the
       photo were filled between wooden forms to achieve their blocky
       shape, but this was unnecessary. When installed properly, stacked
       bag groins have performed well; however,     they should only be con-
       sidered a short-term  solution when filled  with  sand.

                                                           Oy

                 ZANIMM

                          Figure 74       Stacked Bag Groin

       Gabions

            Wave Height Range: Above five feet.

            The recommendations for gabion revetments generally apply.
       The groin should be underlain with filter cloth to inhibit settle-
       ment, and all baskets should be made from PVC-coated wire mesh.
       Tiers of baskets should be tied together with appropriately sized
       wire to prevent shifting of upper tiers over lower tiers, and tight
       packing is needed to minimize distortion of the baskets and damage
       to the wire. Adequate toe protection is required to prevent set-
       tlement and basket distortion.      Thin gabion mattresses are ideal
       for this purpose.

            Figure 75 shows a gabion groin.

                                         ill
<pb n="111" />

                              Figure 75      Gabion Groin

          Steel Fuel Barrels

               Wave Height Range: Below five feet.

               The use of steel fuel barrels for construction is only econo-
          mical in remote arctic areas where used barrels are readily avail-
          able and they have no other salvage value.      Barrel groins have
          worked well where littoral transport characteristics are suitable
          for shore stabilization with a low groin.    The barrels should be
          completely filled with gravel to protect them from crushing by ice
          floes or from damage due to floating debris. They should also be
          capped with concrete for additional strength, and entrenched to
          prevent undermining by scour on the downdrift side.

          Quarrystone

               Wave Height Range: Above five feet.

               Quarrystone, a durable and time-tested material for shore
          protection, should always be considered where locally available.
          Figure 76 contains a typical crbss section and profile of a quarry-
          stone groin. The stone should be sized using Equation (17) and
          values from Table 16.   Figure 77 is a photograph of a quarryston%
          groin.

                                          112
<pb n="112" />

                                                                        Variable

                                                                                                           Water Level Datu
                                                w.,

                                                                          PROFILE

                                 NOTE: Dimensions and details to be         Vortes
                                        determined by particular
                                        site conditions.

                                                                                                           Armor Stone

                                                                    Core Stone (Quarry Run)

                                                                      CROSS-SECTION

                               Figure 76                    Quarrystone Groin Section and Profile
                                                            [U.S. Army COrPs of Engineers (1977c)]

                                  a' @ ®r

                                                                       A

                                                Figure 77                    Quarrystone Groin

                                                                            113
<pb n="113" />

          Longard Tubes

               Wave Height Range: Below five feet.

               Longard tubes have performed fairly well when remaining intact
          (Figure 78).   Failure has usually resulted from holes or tears in
          the fabric and loss of sand fill. Longard tubes are probably best
          as a short term or emergency measure because of their vulnerability
          to damage. When used as a groin, the Longard tube should be under-
          lain by a  filter cloth with 10-inch tubes factory-stitched to each
          side. The filter cloth helps to prevent     settlement, and  the small
          tubes hold the cloth in place.

                                     . . .. . ......

                                                                  14,

                           Figure  78      Longard Tube Groin

          Sheet Piling

               Wave Height Range: Above five feet.

               Sheet pile groins, an old and proven means of shore protec-
          tion, can be constructed of timber, steel, or aluminum sheeting.
          Toe protection or adequate embedment is required to insure the
          structure's stability. The general recommendations given for sheet
          pile bulkheads also apply to groins. Figure 79 contains a section
          and profile, and Figure 80 a photograph of a typical sheet pile
          groin.

                                           114
<pb n="114" />

                                                     Riprop Along Updrift Face of Grain              Steel Cap
                                  Riprop Along Downdriff Face of Groin        A

                                    L. W. 0.
                                                                                                    ..Sand Fill
                                                                                                        wn,

                                                                                           Existing Lake Bottom
                                                            Assumed Clay Line                                             MEMO-

                                                                           -.j
                                                                              A

                                                                                                tone Toe Protection

                                                                                            _LWD@
                                                                                            -L-
                                                                              Fi 11; i

                                                                   Assumed Clay Line

                                                                    Steel Sheet Pilin

                                                                              SECTION A-A

                                            Figure 79                     Sheet Pile Groin Section
                                             [U.S. Army Corps of Engineers                                (1977c)]

                                            tj,

                                             Figure 80                     Timber Sheet Pile Groin
                                                                    Steel Sheet PH, 7g

                                                                                  115
<pb n="115" />

          Timber and Rock

               Wave Height Range: Below five feet.

               Many structural forms are possible for timber and rock groins.
          Figure 81 shows a timber crib structure that retains a stone f ill.
          Care must be taken to insure that the rock is larger than the gaps
          between the timbers.   Rock has escaped from the offshore compart-
          ment of the groin in the figure for that reason. Treated timbers
          should be used; and to insure structural stability, they should be
          securely fastened together with long wrought iron or coated steel
          rods, threaded at the ends to accommodate washers and nuts.

               Alternate arrangements for timber groins are possible.      Two
          rows of round structural piles can be driven or augered deep into
          the beach, with timber planking spiked to the piles. The piles can
          be placed close together with the planking set in the space between
          (Figure 82), or the piles can be more widely separated to form a
          crib-type structure (Figure 83).

                                        Q_

                           Figure 81      Timber Crib Groin

                                          116
<pb n="116" />

                                            f fjAp
                                                                                       Nio

                                                                                       NO

                                                 Figure 82                    Timber Plank              Groin

                                                                                                        -71

                                                 Figure        83              Timber Plank              Groin
                                                    f@, Av

                                                                               117
<pb n="117" />

           BEACH FILLS

                 Beach fills are constructed by mechanical means such as dredg-
           ing and pumping from offshore deposits, or by overland hauling and
           dumping by trucks. The resulting beach provides some protection to
           the area behind it, while also serving as a valuable recreational
           resource.

                 An excess of fill will have to be placed initially because the
           finer material will be lost from the beach as the waves sort the
           deposit.    The amount of overfill needed to account for these ini-
           tial losses depends on the textural characteristics of the fill and
           the in-place material. These are compared by using measures of the
           mean grain size and sorting of the sand.samples as given by Hobson
           (1977).    Sorting is an indication of the range of particle sizes
           that are present. A well sorted sample contains particles that are
           approximately the same 'size.        A poorlg sorted sample contains a
           gradation of particle sizes.

                 Mean grain sizes and sorting are expressed in phi units.
           These are defined as,
                                       -1092  d (mm)                                  (18)
           where, d          the particle diameter in millimeters.
           Note,     (mm)
                                1092 d(mm) =  logio d   (mm) /loglo(2).
           Therefore,
                                       -3.32 loglod  (mm)                             (19)
                 Table 17 compares the millimeter and phi size scales.

                                              Table 17

                              PHI VERSUS MILLIMETER PARTICLE SIZES
                                    d (mm)

                                     256                   -8
                                       64                  -6
                                       8                   -3
                                       4                   -2
                                       2                   -1
                                                            0
                                     0.5                    1
                                    0.25                    2
                                   0.125                    3
                                  0.0625                    4

                                                 118
<pb n="118" />

               An estimate of the mean particle size is
                                           M = 084 + 016                          (20)
                                                    2

         where 084   and 016  are points on the gradation curve that represent
         the  percentage of the sample that is coarser than the particular
         phi size. Phi sorting can be estimated by
                                           S =084 - 016                           (21)
                                                   2

               Figure 84 provides a fill factor that specifies the amount of
         fill material needed to produce a given volume of in-place materi-
         al. The axes are defined in terms of the mean particle size of the
         borrow (fill) and native (in-place) material (Mb and Mn),   and the
         sorting of the borrow and native material (Sb  and Sn).    For in-
         stance, if Mb  = 3. 0, Sb = 2.0, M = 3.50 and S = 1.00;  the fill
         factor from figure 84 is 1.2.  Therefore, if a  beach containing

                  Figure 84      Fill Factors for Beach Fills
                                 [After Hobson (1977)]

							119
<pb n="119" />

           1, 000 cubic yards of sand is desired, it will be necessary to
           initially place about 1, 200 cubic yards of sand from the borrow
           source.

                 Figure 85 illustrates the important design factors to consider
           when constructing a beach fill.          The berm elevation should be
           chosen to decrease the likelihood of overtopping by waves during
           storms.   The berm width is determined by geometry to provide for
           the volume of fill to be placed, or for the shoreline use require-
           ments.   The beach s.lope should be chosen to parallel the existing
           profiles and slopes.       This is based on the assumption that the
           existing beach   is in equilibrium with the wave forces and that the
           new beach will eventually assume a similar shape. The shaping of
           the beach fill    profile can either be done by equipment at the time
           it is placed,     or it can be reshaped by waves.          The final equi-
           librium slope    will depend on the texture of the fill material,
           coarser-grained sand resulting in a steeper beach slope than pre-
           viously existed.

                 If fill is placed over a short length of shoreline, it will
           create a projection that will be subject to increased wave            attack.
           Therefore, it is generally preferable to make the transition to the
           existing shoreline over a longer distance.            This may require a
           cooperative effort involving a number of landowners.             If this is
           impractical, protective structures such as groins may be required
           to retain the fill.
                    BERMt

                     EXISTING
                     BOTTOM                                             -DESIGN WATER
                                                                              LEVEL

                                                                           LOW WAT E R

                                  INITIAL FILL PLACEMENT

                              ERODED BOTTOM EQUALS
                              DEPOSITED VOLUME

                                                                     -;;-,-DESIGN WATER
                                                                              LEVEL

                   FINAL SLO E                                         -LOW WATER
                            C
                   DEPENDS ON COARSENES
                    OF THE SAND

                             FILL RESPONSE TO STORM WAVES
                                  Figure 85         Beach Fill

                                               120
<pb n="120" />

        VEGETATION

             Vegetation has been used for stabilizing shorelines either as
        a substitute for, or supplement to, structures. Vegetation is an
        inexpensive, and generally easy, approach to providing erosion
        control.   It is not, however, applicable to all situations.          it
        cannot always prevent erosion, nor can it stop the recession of
        bluffs caused by groundwater seepage.      In order to confront these
        types of problems, it is necessary to consider a combination solu-
        tion such as a structural device and vegetation.

             Vegetation uses are limited by site characteristics such as
        climate, soil properties, wave exposure, and salinity regimes. The
        following discussion will focus on species which may be used for
        marsh, beach, dune and slope plantings.        For each species, the
        applicable geographical region and planting    specifications will be
        described.   Further information on these      and other species not
        mentioned in this report can be obtained from county offices of the
        Soil Conservation Service, state coastal zone management programs,
        or Corps of Engineers districts.

        Marsh Plants

             Coastal marshes are those herbaceous plant communities which
        are normally inundated or saturated by surface or groundwater.
        They may be narrow fringes along steep shorelines or they may cover
        wide areas in shallow, gently sloping shore regions typically found
        in bays and estuaries (Figure 86).     In saltwater marshes, salinity
        is generally equal to or slightly less than seawater (35 parts per
        thousand salt).    Freshwater marshes experience water level fluc-
        tuations resulting from groundwater table and seasonal climatic
        changes.

             To establish a coastal marsh, the site must be evaluated based
        on geographic area, tidal elevation and range, salinity, fetch
        length, and soil properties.      The vegetation prevalent in three
        saltwater marsh regions and the Great Lakes are discussed below.
        Planting specifications are summarized in Table 18.        The suita-
        bility of a site for marsh plantings can be evaluated using Fig-
        ure 87.

             Atlantic Coast Marshes.    Common vegetation found in Atlantic
        coast marshes is describe    riefly below.

                   Smooth Cordgrass (Spartina alternaflora).      This is the
             dominant marsh grass from Newfoundland to about central
             Florida.   It is well adapted to soils not exposed to air that
             range from coarse sands to silty clays. Three distinct height
             forms are recognized. The tall form is generally found along
             tidal creeks and drainage channels, the short form grows on
             flat or gently sloping areas away from channels, and the
             medium form, when present, is found in transition areas be-
             tween stands of the short and tall forms.

                                          121
<pb n="121" />

                                                                                  Table 18

                                                                 PLANTING SPECIFICATIONS FOR MARSH PLANTS

                             Type                 Planting Time    Plant Form Recommended              Spacing              Tidal Range and Plant Location

                 Atlantic Coast Marshes

                 Smooth cordgrass                 March-May        sprigs                    31 apart                       &lt; 4.51 range-plant MLW to MHW
                 (Spartina alternaflora)                           15 week old seedlings     1.51 apart                     &gt; 4.51 range-plant MTL to MHW
                                                                   6 month old seedlings     1.5' apart
                                                                   or plugs
                 Saltmeadow cordgrass             March-May        Sprigs                    31 apart                       MHW to estimated highest tide
                 (Spartina patens)                                 15 week old seedlings

                 Black needle rush                Spring           Seedlings                 As 1-5 percent of cordgrass    Ab ove MHW
                 (Juncus roemerianus)                                                        plantings

                 Common reed                      Spring           Sprigs                    1.5'-3.01 apart                Above MHW
                 (Pbragmites communis)

                 Mangroves                        Late February-   Seedlings                 1.51 apart                     Generally MTL and above
                   Black (Avicennia germinans)    March            Established plants        61-101 apart
                   Red (Rhizophara mangle)
                   White (LaguncUlaria racemosa)

                 Gulf Coast Marshes

                 Gulf cordgrass                   March-May        Sprigs                    1.5'-3.01 apart                MHW and above
                 (Spartina spartinae)                              15 week old seedlings     1.51 apart
                                                                   6 month old seedlings     1.51 apart

                 Saltgrass                        spring           Seedlings                 1.5'-3.01 apart                MHW and above
                 (Distichlis spicata)

                 Pacific Coast Marshes

                 Pacific cordgrass                April            sprigs                    1.5'-3.01 apart                Below MTL
                 (Spartina foliosa)

                 Pickleweed                       spring           sprigs                    0.51-3.01 apart                MHW to estimated highest tide
                 (Salicornia spp.)                                 Seeds                     5-10 seeds/sq ft.

                 Sedge                            April-June       Seedlings                 1.4'-3.01 apart                Above MTL
                 (Carex lyngbyei)

                 Tufted hair grass                April-May        Seedlings                 1.5'-3.01 apart                Above MLHW
                 (Deschampsia caespitosa)

                 Arrowgrass                       April-June       Seedlings                 1.51-3.01 apart                Above MTL
                 (Triglochlin maritima)
<pb n="122" />

             A

                         Figure 86      Marsh Vegetation

                 Smooth cordgrass can be planted with a better chance of
            success than any other coastal marsh species native to the
            United States. Its ideal salinity range is 10 to 35 parts per
            thousand. Two to four weeks after planting, 30 to 45 lb/ac of
            a fertilizer which contains equal parts of available nitrogen
            and phosphate should be applied.

                 Saltmeadow Cordgrass (Spartina patens).   This species is
            extensive in the irregularly flooded high marsh zone along the
            Atlantic coast.   It is able to withstand extended periods of
            both flooding and drought, growing in spots where the surface
            drainage is poor and water ponds during rainy periods.        it
            cannot, however, tolerate the daily flooding of the intertidal
            zone.   Saltmeadow cordgrass is a valuable stabilizer in the
            zone between smooth cordgrass and the upland grass species.

                 Two to four weeks after planting, 30 to 45 lb/ac of
            fertilizer containing equal parts of nitrogen and phosphate
            should be applied.

                                       123
<pb n="123" />

                                   I* SHORE                                              2., DESCRIPTIVE CATEGORIES                                                                               3*
                                            VARIABLES                                                                    (SCORE AS INDICATIRM )
                                         FETCH -AVERAGE                                  Score: 0 Score: 2 Score: 4 Score: 6 Score: 8 Score: 10
                                   AVERAOI MIANU                                               LIEU             3.1                6.1             9.1               12.1            awmat
                                   * UMFTM (MILES)                                                              11.91              13.81           13.71             (7.6)
                                   * OPEN WATER SEAMED                                                                                                                                THAN
                                                                                                                to                 to              to                to
                                   KOMCM TO                                                    30                                                                                     1S.0
                                   ME NMI Of 4S                                                11.81
                                                                                                                6.0
                                                                                                                                   9.0             12.0              IS.0              (9-41
                                   EITKISOWM?EBKKAI
                                                       ____NZE7                                                 13.71              IS.6)           (7.51             19.4)
                                   b.FETCH-LONGEST                                       SCOW 0 ScoEs: 2 Score: 4                            1 Score: 6          Score: 8 Score: 10
                                   MUST DISTANCE                                               LESS             4.1                8.1             12.1              16.1            mmAnn
                                   IS UNETERS (MILES)
                                                                                               THAN             12.6)              IS.11           (7.61             110.11
                                   OF OPEN RAT" ND"u                                                                                                                                   THAN
                                   KWMUW Is                                                    .4.0             to                 to              to                to               20.0
                                                                                               (2.5)
                                   ME UWE IM as                                                                                                                                       112.6)
                                                                                                                  .0               12.0            16.0              20.0
                                                  PER
                                   DIM SIDE If      PENDICULAN.                                                 (5.0)              17.51           (10.01            (12.61
                                   c. SHORELINE                                          Score: 0                           Score: 2 -                           Score: 4
                                            GEOMETRY                                                              COVE                      NWWU1T                                HUD"ND
                                                                                                                                            sixwom                                                OR
                                                                                                                                                                                  ST"mm
                                            SENERAL SRAPE Of ME SNOOELINI                                                                                                        S1101miNE

                                            AT ME PONT OF INTEREST

                                            PLUS 211 METERS (no FT

                                            ON EITNIER SIDE                                                     . . . . . . . . . . . . . . . .
                                                                                                                                                                                                  ZN

                                                                                         Score       0
                                   d. SHORE SLOPE                                                                                            I Score: 4
                                         SLIM OF ME PLANTM6 AREA,                                        GRADUAL
                                         I VERTICAL To NORinmik )                                                         LESS                                   STEEP
                                                                       5;;;;;;w                   1 to IS ON                                       MORE THAN 1 to                          is
                                   a.    SEDIMENT                                        Score: 0               Score: 2           1 Score: 4                1 Score: 6       1 Score: 8
                                               61ARE SITE of S[glMENIS                         SILT a                 FINE              MIEDIUM               COASISE
                                                                                               CLAY                   SAND         I       SAND                  SAND         I     GRAVEL
                                   f.    BOAT TRAFFIC                                    Score : 0                           Score : 8                           Score: 16
                                         PROXIMITY Of SITE TO 1AVIUIIOj CMAMNELS               NO NAVIGATION                       NAVIGATION CHANNEL                NAVIGATION CHANNEL
                                                                                               CHANNEL WITHIN
                                         FIR LAASE VESULS                                       I KILOMETER                        WITHIN I KILOMETER                WITHIN 100 METERS
                                         It SOUL RECREATIONAL CUR                              10.6 MILES 1                        10.6 MILES I                             133OPF)
                                   g. WIND                                               Score: 0                            Score : 4                           Score: 8
                                                                                                    SHIELTIENIIED                  DOES NOT FACIE                           FACES 0
                                            ME ORIENTATION Of ME gf[                                                               IN THE DIKCTION OF                THE DIIIIECTION OF
                                            10 RELAIIIIII 11 LOCAL WINDS                               FROM                        PWEVAIUNG WINDS                   MVAIUNG WINDS
                                                                                                       WIND                                 on                                  on
                                                                                                                              FIIIEQUENT STORM WINDS             LFREQUENT STORE WINDS
                                                            4, CUMULATIVE WAVE CLIMATE SCORE

                                   SCORE                   1 TO 10: USE SPRIGS AT 3-FOOT SPACINGS IN 10-FOOT
                                                                                         (MINIMUM) ZONES.
                                                        11 TO 20:                        USE SPRIGS*OR 15-WEEK SEEDLINGS AT D2-FOOT
                                                                                         SPACINGS IN 10-FOOT (MINIMUM) ZONES.
                                                        21 To 30: USE 5-7 MONTH SEEDLINGS OR PLUGS AT D2--FOOT
                                                                                         SPACINGS IN 20-FOOT (MINIMUM) ZONES.
                                                       ABOVE 30:                         DO NOT PLANT

                                                Figure 87                                      site Evaluation Form for Marsh Plants
                                                                                    [After U.S. Army Corps of Engineers (1980)]

                                                                                                                      124
<pb n="124" />

                   Black Needle Rush (juncus roemerianus). This species is
              extensive along the Ttlantic coast south of New England.           It
              is found in high marshes where it is f looded only by wind-
              driven tides or in areas near the edge of uplands where fresh-
              water seepage regularly occurs.        It is a good stabilizer,
              although difficult to propagate, yet under favorable condi-
              tions it will invade areas already populated by cordgrasses.

                   Common Reed (Phragmites communis). The common reed grows
              4.5 to 12 feet    tall and is widely distributed in brackish
              (salinity range   1 to 35 ppt) to freshwater areas above the
              mean high water   level.   It is easy to transplant and provides
              good stability;   however, it does tend to compete with other
              plants and may   become a nuisance by crowding out more desir-
              able species.

                   Mangroves.    Three species of mangrove--black (Avicennia
              germinans), red (Rhizophora mangle), and white (Laguncularia
              racemosa) --occur along the south Atlantic coast, primarily in
              Florida.   Mangroves are good stabilizers, but they require
              considerably more- time (2 or 3 years) than grasses to become
              established. During this time, - the plants are susceptible to
              possible damage from tides, traffic, and browsing animals.
              Mangrove seeds, seedlings, or plants are best planted in
              established cordgrass stands, which provide stability until
              the mangroves are established.

                   Slow-release (e.g., Osmocote) or a magnesium-ammonium-
              phosphate fertilizer can be placed in the planting hole if
              needed, especially for the larger transplants. Daily watering
              may be required if flooding does not occur.

              Gulf Coast Marshes.    The vegetation found in gulf coast mar-
        shes  does not substantially differ from south Atlantic coast mar-
        shes.   Grasses, primarily saltgrass and gulf cordgrass, are preva-
        lent, while smooth cordgrass, saltmeadow cordgrass, and black
        needle rush are also common.

                   Gulf Cordgrass (Spartina spartinae).       Gulf cordgrass is
              found al-ong the gulf coast from southwest Louisiana to Texas.
              It performs well above the mean high water level.             It is
              propagated like saltmeadow, cordgrass, using the same pro-
              cedure.

                   Saltgrass (Distichlis spicata).       Saltgrass is generally
              limited to the more saline, high marshes along the gulf coast.
              The plant is usually found in a mixture with saltmeadow cord-
              grass or black needle rush, and is rarely the dominant species
              except in poorly drained areas or in narrow bands. Saltgrass
              is more difficult to establish than the cordgrasses and usu-
              ally is allowed to volunteer into cordgrass plantings.

              Pacific Coast Marshes.      Vegetation   in marshes along the
              'T'_                                         the Atlantic coast.
        Pacific coast is more diverse than along

                                           125
<pb n="125" />

          Pacific cordgrass is found along the central and southern Cali-
          fornia coasts.   Pickleweed! sedges, arrowgrass, and tufted hair
          grass are common along the northern Pacific coast.

                    Pacific Cordgrass (Spartina follosa).   It is similar to
               smooth cordgrass, hilt, it takes longer to establish. It domi-
               nates below the mean tide level of intertidal marshes. Plants
               and sprigs should be inserted by hand in holes made in soft,
               fine-textured soils. Fertilizers should contain equal quanti-
               ties of available nitrogen and phosphate.

                    Pickleweed (Sallcornia spp. ).   From mean high water to
               extrei'ehigh tide, various species of pickleweed can be used
               upslope of Pacific cordgrass.    It will spread both by seeds
               and vegetatively (by rhizomes and tillers), but because it is
               shallow-rooted, it is probably not as useful for stabilization
               as Pacific cordgrass. Pickleweed may be easily established by
               seeding or by transplanted peat-pot seedlings, and in fact, it
               often invades disturbed surfaces during the first growing
               season.

                    Sedge (Carex 1Vngbgei).   Sedge marshes are usually found
               in areas such as river deltas where silty soils exist. They
               grow above the mean tide level and are not especially salt
               tolerant. The plant may respond to nitrogen and phosphorous
               under deficient conditions. It appears to be one of the best
               marsh plants available in the Pacific Northwest.

                    Tufted Hair Grass (Deschampsia caespitosa).    This plant
               predominates in high marshes subject to flooding' only by
               higher high tides.    It is a   good sediment accumulator and
               stabilizer once established.   It is generally easy to trans-
               plant and quick to establish. Fertilizers should be applied
               where nutrient deficiencies are suspected.

                    Arrowgrass (Triglochlin maritima).      This plant will
               frequently invade and colonize disturbed     marshes, trapping
               sediments and debris and helping to create a substrate for
               other plants. Planting should follow the method described for
               sedges.

               Great Lakes Marshes. Marshes of the Great Lakes are generally
          limited in extent, and confined primarily to the protected shores
          of bays and inlets of Lakes Huron and Michigan. Establishing fresh
          water marshes may not provide as satisfactory a level of erosion
          prevention as saltwater marshes. ' The landowner interested in
          establishing fresh water marshes should consider the common reed,
          rushes (Scirpus spp. ) 'such as spike rush, bulrush, and great bul-
          rush, and, in some instances, upland grasses such as reed canary
          grass (Phalaris arundinacea).    More specific information may be
          obtained from those sources suggested at the beginning of this
          section.

                                          126
<pb n="126" />

        Beach and Dune Plants

             The protection of the upland portions of sandy shorelines can
        be accomplished through the creation of barrier dunes and the sta-
        bilization of present dunes.       Vegetation used to initiate the
        building of barrier dunes is specially adapted to the more severe
        environment of the beach area (Figure 88). Barrier dune formation
        can occur naturally, but it is usually slow and in some areas does
        not happen.    Utilization and proper management of the natural
        processes can accelerate the development.

           f

             AV
                                                       ;YI

                                                              NO

                                                                          IZ

                                                                           7,

                           Figure 88       Dune Vegetation

             The beach provides a     generally  harsh environment for plant
        growth.   Plants must tolerate rapid     sand accumulation, flooding,
        salt spray, sandblasts, wind and water erosion, wide temperature
        fluctuations, drought, and low nutrient levels. Plants capable of
        stabilizing coastal dunes do, however, occur in most coastal
        regions where there is sufficient rainfall to support plant growth.
        These regions and several of the most successful species are dis-
        cussed below.

                                          127
<pb n="127" />

                             Planting specifications for several selected beach grass
                    species are summarized in Table 19.

                                                                                Table 19

                                                         SELECTED BEACH AND DUNE GRASS PLANTING SPECIFICATIONS

                                                                                                      Species
                                                                                         Beach Grass
                                    Element                         American                Panic              European               Sea Oats

                      Planting Season
                        Late fall to early winter               Yes+                     Yes                Yes                    No
                        Midwinter                               Yes+                     Optimum            Yes                    Optimum
                        Late winter to early spring             Optimum+                 Optimum            Optimum                Yes
                        Early spring to mid-spring              Yes                      Yes                Yes                    No

                      Available Source
                        Transplants
                        Commercial                              Yes                      Yes                Yes                    Yes
                        Wild harvest                            Yes                      Yes                Yes                    Yes

                      Seed
                        Commercial                              No                       No                 No                     No
                        Wild harvest                            Yes                      Yes                Yes                    Yes

                      Planting Density
                        Eroding site                            18-inch centers          18-incb centers    18-inch centers        18-inch centers
                        Noneroding site                         24-inch centers          24-inch centers    24-inch centers        24-inch centers
                        Stems per transplant                    3                        1                  3                      1

                      Fertilization, Fi st Growing Season             o
                        Composition NPK6                        3-1-0                    2-1-1              7-0-0                  2-1-1
                        Rate lbs/acre (annual)                  200                      24                 40                     240
                        Application periods                     March                    April              April                  April
                          (equal applications in                May                      June                                      Julie
                         months indicated)                      July                     August                                    August
                                                                September

                      Illegal to harvest in some states.
                      +Season not recommended for Great Lakes.
                      "NPK--Nitrogen-Phosphorous-Potassim.
                      o
                      3-1-1 in Great Lakes.               [After U.S. Army Corps of Engineers (1977c)ll

                             North Atlantic Region. Extending from the Canadian border to
                   the Virginia capes, American beachgrass is the dominant dune sta-
                  bilizing plant in this region; bitter panicum offers promise as a
                   companion plant.

                                      American Beachgrass                         (Ammophila              breviligulata).                       This
                             species is probably the most widely used for the initial
                             stabilization of blowing sand because it grows rapidly and can
                             effectively trap sand by the middle of the first growing
                             season. Once established, it multiplies quickly. It prefers
                             cool weather and plants start growing in early spring and
                             continue through fall under the most favorable conditions.
                             The grass can be transplanted over a long planting season with
                             a good chance of survival. American beachgrass is available
                             commercially or may also be harvested from wild stands.
                             Seedlings are the preferred method of planting. Starting from
                             seed is usually uneconomical because seed supplies are un-
                             reliable and weeds are difficult to control.

                                      American beachgrass should be planted 8 to 10 inches deep
                             in loose, dry sand. Shallow planting is the most common cause

                                                                                   128
<pb n="128" />

              of failure, therefore it is better to place the plant too deep
              than too shallow.       Transplants may be made from October
              through May with the optimum period being February through
              April. The seedlings should be one or more healthy, vigorous
              stems (culms), with one to three seedlings per hill.           First
              year growth is related to the size of the seedlings (number of
              stems) planted.     Spacing varies with the characteristics of
              the site, but a strip of beachgrass 24 to 40 feet wide,
              planted 18 inches apart, will generally be effective by t         'he
              last half of the first growing season. A more practical (and
              less expensive) method for planting would be 4 rows of 18-inch
              spacings at the approximate center of the proposed dune. This
              plot should be flanked on both sides, by four rows each of
              plants spaced 24, 36, and 48 inches.

                   Newly planted stands of American beachgrass will often
              respond to the application of 90 to 135 pounds of nitrogen and
              30 to 45 pounds of phosphorous per acre. These fertilizations
              should be divided into three applications. The first should
              be applied as new growth emerges, with subsequent applications
              at 4- to 6-week intervals.

                    Bitter Panicum (Panicum amarum).      This grass is indige-
              nous along the Atlantic coast from Connecticut southward. It
              is best used as a companion to American beachgrass, especially
              in those areas where the beachgrass is subject to severe
              attack by the disease soft scale.

                    Bitter panicum should generally be planted at the same
              time and with the same methods as American beachgrass. since
              it prefers warm weather, it may be wise to wait until April to
              plant.   Bitter panicum can be transplanted as mature primary
              stems or as tillers. Primary stems must be used during late
              winter and spring until tillers become available.               Young
              tillers, with some roots and rhizomes attached, grow with very
              little delay and are the preferred method of planting when
              available. Plants should be placed 8 to 10 inches deep in the
              soil.   Bitter panicum should be planted as a percentage (10-
              20%) of the total beachgrass planting and in the same pattern.
              Pure stands of bitter panicum are not usually successful
              except in very small spots, such as those where beachgrass has
              been reduced by insects or disease. Fertilizer applications
              are similar to those recommended for beachgrass.

              South Atlantic Region. This region extends from the Virginia
         capes to Key West.    Sea oats is the dominant plant. However, both
         American beachgrass and bitter panicum, when planted in combination
         with sea oats, will successfully establish dunes, especially in the
         northern part of the region.

                    Sea Oats (Uniola paniculata). More persistent than other
              stabilizing pecies, sea oats does not provide much initial
              protection.    It grows slowly, is difficult to propagate, and
              is not widely available commercially.           However, sea oats

                                            129
<pb n="129" />

              provide excellent protection when established.        To provide
              initial protection, sea oats should be planted in mixes with
              American beachgrass and bitter panicum to the Carolinas and
              with bitter panicum farther south. As the other grasses thin
              out, sea oats will spread and dominate the dune.

                   Planting is similar to bath American beachgrass and
              bitter panicum. Plants should be placed 8 to 10 inches deep,
              because they are slow starters and the depth is required to
              prevent dessication and blowouts.     Transplanting can be suc-
              cessful at any time given proper moisture conditions and
              healthy transplants. -Optimum planting months are January and
              February, although in more severe climates, February to April
              are better.   Single stem transplants perform as well as mul-
              tiple , stem plantings under most conditions.       Two-year-old,
              nursery-grown plants appear to be the best stock for trans-
              plants.

                   Since sea oats is generally planted as part of a mixture,
              it is recommended that one or two rows of sea oats (or every
              10th to 20th row in extremely large plots) be planted no
              closer than 24 inches. A moderate application of nitrogen and
              phosphate similar to that recommended for American beachgrass
              can be used to speed establishment of new plantings and to
              maintain growth and vigor in sand-starved areas.

                   Saltmeadow Cordgrass (Spartina patens).      This plant is
              more commonly used in marsh plantings (see prior d    iiscussion),
              but it will frequently invade a beach area and create small
              dunes which will support other vegetation. It is particularly
              well suited for this use on low, moist sites where periodic
              saltbuildup occurs.

                   Plants should be set 6 to 8 inches deep to stay in the
              moist zone. For dune stabilizing plantings,     'the optimum time
              is late winter and spring; however, saltmeadow cordgrass can
              be transplanted in the early summer providing sufficient
              moisture is available.     Vigorous, multi-stemmed transplants
              from uncrowded nursery stands are recommended. With vigorous
              plants, adequate nutrients, and favorable moisture, saltmeadow
              cordgrass can be planted 16 to 24 inches apart in a single
              species planting. The transplants will usually benefit from a
              total of 90 to 135 pounds of nitrogen per acre applied over
              two to three applications during the first year.       Subsequent
              fertilization should deliver similar amounts of nitrogen in
              single applications over the following two or three years.

                   Bermuda Grass (Cynodon dactglon). Although this is not a
              prominent dune species, it can be used very effectively in
              special situations.    The coastal hybrid is deep rooting and
              rapidly establishing and can be used to revegetate areas where
              American beachgrass has been killed by insects or disease.
              Turf hybrids will, when properly managed, perform well on the
              dune environment, where they form a more traffic resistant
              stand than other types of vegetation.

                                          130
<pb n="130" />

                   Sprigs of Bermuda grass, spaced 18 to 24 inches ap          .art,
              should adequately stabilize the dune once they are estab-
              lished.   For turf development, a spacing of 12 inches should
              be used.    Sprigs may be planted from early spring to the
              beginning of summer where adequate moisture is available.
              Sprinkling the sprigs during dry spells will help to assure
              the survival of the plants. Bermuda grass requires more
              nutrients than other dune grasses.         As soon as new growth
              begins in the spring, 30 to 45 pounds of nitrogen per acre
              should be applied every 4 weeks until the end of summer.
              Traffic resistant turf can be developed by applying 450 to 900
              lb/ac of 10-10-10 formula fertilizer in the early spring and
              supplementing that with 45 to 70 pounds of nitrogen per acre
              every 4 weeks through the summer.

              Gulf Region.    The region extends from the gulf coast              of
        Florida to the Mexican border. sea oats and bitter panicum are the
        dominant dune stabilizing species. other species include railroad
        vine and saltmeadow cordgrass.       Establishment of sea oats, bitter
        panicum, and saltmeadow cordgrass should follow prior recommenda-
        tions.    Local variations exist, and the landowner should consult
        local agricultural extension agents and others about differences in
        technique and management of plantings of these species.

                   Railroad Vine (Ipomea pes-caprae). This plant is one of
              the more prominent pioneer species in this region. It is not
              generally planted because it is somewhat less effective in
              trapping sand than dune grasses.       It is, however, capable of
              rapidly spreading over foredunes, and transplants of the vine
              may be included as part of a grass establishment planting.

              North Pacific Region.     This region extends from the Canadian
        border to Monterey, California.       European beachgrass and American
        dunegrass are the dominant sand stabilizing plants of the region.
        American beachgrass may also be applicable in the area.

                   European Beachgrass (An2mophila arenarla). This plant is
              inexpensive and uspX-widely in this region.             Although it
              effectively traps sand, it forms dense stands with little
              outward spread, causing the resulting dunes to have steep
              windward slopes.    Another disadvantage is that it will often
              exclude native species, making it difficult to establish mixed
              plantings.

                   Planting should not be done when the temperature exceeds
              600 F or is below freezing. Moist sand should be within 3 to
              4 inches of the surface and the minimum planting depth is 12
              inches.   The optimum conditions of moisture and temperature
              for planting usually occur during the late fall, winter, and
              early spring months in this region. Three to five stems per
              hill are recommended for transplanting since establishment of
              dense stands is imperative with the wind conditions in this
              area.   Spacing and planting patterns should be adapted to the
              site, but generally, an 18- x 18-inch planting with three to
              five stems per hill is sufficient. A pattern of several rows

                                            131
<pb n="131" />

              with plants spaced 12 x 12 inches, bordered by several rows
              each of plants spaced 18 x 18, 24 x 24, and 36 x 36 inches,
              will build a stable foredune at less expense than a uniformly
              spaced planting.   When rapid growth begins (early April), 35
              to 55 pounds of nitrogen per acre should be applied.

                   American Dunegrass (ElVmus mollis). Although this grass
              is naEl-veto the northwest, it is more difficult and expensive
              to propagate than either European or American beachgrass. The
              grass tends to produce low, gently sloping dunes, often pre-
              ferable to those dunes built by European beachgrass.

                   American dunegrass should be set 12 inches or more deep
              in moist sand. satisfactory planting occurs primarily in the
              months when the grass is dormant; late November through Febru-
              ary in the northern portion of the region, and not at all in
              the southern extent.    Planting should be limited to tempera-
              tures below 550 F. Planting several stems per hill would be
              desired; however, due to the expense, a close spacing of 12
              inches with one viable stem makes better use of scarce plant-
              ing stock.   An application of 35 pounds of nitrogen per acre
              from a soluble source is recommended as new growth starts.

              South Pacific Region.    This region extends from Monterey,
         California, to the Mexican border. While some of the beach grasses
         discussed above (e.g., European beachgrass) are applicable in the
         .northern portions of this region, the dominant plants are forbs
         such.as the sea fig.

                   Sea Fig (Carpobrotus edulis and C. aequilaterus).        Sea
              fig is effective as a sand stabilizer but not good as a dune
              builder.   It is quite easy to establish; cuttings 4 to 6
              inches long should be placed about 18 to 24 inches apart in
              moist sand.   An occasional application of nitrogen at a rate
              of 30 to 35 pounds per acre is recommended to maintain the
              plants once established.

              Great Lakes Region.   Dune development is mostly confined to
         the Michigan and Indiana shores of Lake Michigan; however, the
         discussion which follows is applicable to all the shores of the
         Great Lakes. American beachgrass is the dominant species-.- Native
         species, especially prairie sandreed, will often invade naturally.
         Once the dunes have been stabilized'. volunteer or planted species
         of upland vegetation can be established.     Species of grasses sug-
         gested would include reed canary grass, big bluestem, little blue-
         stem, and switchgrass, all native to the area. These grasses may
         be planted from early May to the middle of June at a rate of about
         0.5 pounds of seed per 1,000 square feet. All require full sun and
         may be mowed occasionally. Reed canary grass is especially useful
         in wet spots.

              Various ground covers may also be planted. The species which
         may be utilized are best suggested by local agricultural experts.

                                          132
<pb n="132" />

        The same holds true for shrubs and trees.       When planting grasses
        and ground covers, application of 12 pounds of 12-18-12 fertilizer
        per 1,000 square feet is recommended.

             An additional problem which landowners in the Great Lakes
        region have is the stabilization of bluffs. Often, structural
        corrections are required in concert with vegetation.          Once the
        structural stabilization is accomplished, vegetative cover will aid
        in preventing erosion, reducing seepage, and slowing runoff.

             The type of vegetation which can be established on bluff
        slopes is dependent upon the slope angle.       Slopes steeper than 1
        on 1 generally preclude successful vegetation, 'but slopes flatter
        than 1 on 3 can be planted as a lawn and maintained in the usual
        manner.   Slopes between 1 on 3 and 1 on 1 can be planted with
        grasses which will not be mowed, ground covers, trees and shrubs,
        or combinations of these three. As mentioned before, local exper-
        tise (e.g., agricultural extension agents) can aid the landowner in
        selecting suitable species and in describing the most practical
        methods of establishment and maintenance.

        PERCHED BEACHES

             Perched beaches are constructed by placing sand fill behind a
        low breakwater or sill. Sills can be constructed of virtually any
        material described earlier for fixed breakwaters. Beach material
        should be chosen in accordance with guidelines previously given for
        beach fills.    Proper filtering should be provided beneath and
        behind the sill to prevent settlement and loss of retained fill.
        In some cases, navigation markers may be required.

        Sheet Piling

             Sheet pile sills are similar to bulkheads.          Timber sheet
        piling will generally require filter cloth backing of the shoreward
        face to prevent loss of backfill through joints in the sheeting.
        This is not generally a problem with steel or aluminum sheet pil-
        ing.   Sheet pile sills also form an abrupt step to deeper water
        which may be hazardous to bathers, particularly children.

             The same precautions about adequate embedment and toe protec-
        tion -for bulkheads also apply to sills.

                                          133
<pb n="133" />

          Concrete Boxes

               Precast, open concrete boxes (for use in drainage structures)
          can be placed side-by-side and filled with sand to form a sill
          (Figure 89).   During placement, the. gaps between adjacent boxes
          must be minimized to prevent excessive wave transmission through
          the structure and to help retain the perched beach. Filter cloth
          backing is required   and toe protection should be provided on the
          offshore side.

                                                 air

                           Figure 89       Concrete Box Sill

                                           134
<pb n="134" />

                    PROPRIETARY DEVICES AND SPECIALTY MATERIALS
             The devices and many of the materials discussed in this report
        are not generally available or familiar to local suppliers. Table
        20 covers principal manufacturers that are active nationwide.
        Inclusion of manufacturers in this directory does not necessarily
        represent an endorsement or recommendation of their products by the
        government.   In fact, some items listed herein were not recommened
        for specific applications in this report.

                                      Table 20

                    PROPRIETARY DEVICES AND SPECIALTY MATERIALS

        Device or Material                      Manufacturer

        Erco Blocks               Erosion Control Systems, Inc.
        Ercomat                   3349 Ridgelake Drive
                                  Suite 101-B
                                  Metairie, Louisiana 70002
                                  504/834-5650

        Fabric Bags               Advance Construction Specialities, Inc.
          Advance                 P. 0. Box 17212
                                  Memphis, Tennessee 38117
                                  901/362-0980

          Acrylic Sand Pillows    Monsanto Textiles Company
                                  Customer Service Center
                                  P. 0. Box 5564, Station B
                                  Greenville, South Carolina 29606
                                  803/242-6700

          Dura Bags               Erosion Control, Inc.
                                  205 Datura Street
                                  Suite 319
                                  West Palm Beach, Florida 33401
                                  305/655-3651

          Fabriform               Construction Techniques, Inc.
                                  11900 Shaker Boulevard
                                  Cleveland, Ohio    44120
                                  216/623-0679

        Filter Cloth              Advance Construction Specialities, Inc.
                                  P. 0. Box 17212
                                  Memphis, Tennessee 38117
                                  901-362-0980
                                  (Woven and Nonwoven)
                                  darthaqe Mills
                                  124 West 66th Street
                                  Cincinnati, Ohio    45216
                                  513/242-2740
                                  (Woven)

                                          135
<pb n="135" />

                                           Table 20
                                           (continued)

           Device or Material                       Manufacturer

                                       Celanese Fibers Marketing,Company
                                       Department CE0504
                                       1211 Avenue of the Americas
                                       New York, New York 10036
                                       800/223-9811 (exc. New York, Alaska,
                                       Hawaii)
                                       212/764-8224
                                       (Nonwoven)

                                       DuPont Company
                                       Room 38095
                                       Wilmington, Delaware 19898
                                       (Nonwoven)

                                       Menardi-Southern
                                       Division of United States Filter
                                       Soil and Erosion Control Department
                                         Headquarters
                                       3908 Colgate
                                       Houston, Texas 77017
                                       713/643-6513
                                      -(Woven and Nonwoven)

                                       Nicolon Corporation
                                       Erosion Control Products
                                       Suite 1990
                                       Peachtree Corners Plaza
                                       Norcross (Atlanta), Georgia 30071
                                       404/447-6272
                                       800/241-9691
                                       (Woven)

                                       Erosion Control Products, Inc.
                                       Route 5
                                       Box 406
                                       Daphne, Alabama 36526
                                       205/626-3510
                                       (Woven and Nonwoven)

           Gabions                     Maccaferri Gabions, Inc.
                                       P. 0. Box 43A
                                       Williamsport, Maryland 21795
                                       301/223-8700

                                       Terra Aqua Corporation
                                       Division of Bekaert Steel Wire Corporation
                                       P. 0. Box 7546
                                       Reno, Nevada 89510
                                       702/329-6262

                                             136
<pb n="136" />

                                      Table 20
                                      (continued)

         Device or Material                     Manufacturer

         Gobi Blocks               Nicolon Corporation
         Gobimat                   Erosion Control Products
                                   Suite 1990
                                   Peachtree Corner Plaza
                                   Norcross (Atlanta), Georgia 30071
                                   404/447-6272
                                   800/241-9691

         Jumbo Blocks              Erosion Control Systems, Inc.
         Jumbo Ercomat             3349 Ridgelake Drive
                                   Suite 101-B
                                   Metairie, Louisiana 70002
                                   504/834-5650

         Lok-Gard Blocks           Coastal Research Corporation
                                   1100 Crain Highway, S.W.
                                   Glen Burnie, Maryland 21061
                                   301/761-0584

         Longard Tube              Edward E. Gillen Company
                                   218 West Becher Street
                                   Milwaukee, Wisconsin 53207
                                   414/744-9824

         Nami Ring                 Robert Q. Palmer
                                   5027 Justin Drive, N.W.
                                   Albuquerque, New Mexico 87114

         Sandgrabber               Sandgrabber, Inc.
                                   3105 Old Kawkawlin Road
                                   Bay City, Michigan 48706
                                   517/686-6601

         Surgebreaker              Great Lakes Environmental Marine, Ltd.
                                   39 South LaSalle Street
                                   Chicago, Illinois 60603
                                   312/332-3377

         Terrafix Blocks           Erosion Control Products, Inc.
                                   9151 Fairgrounds Road
                                   West Palm Beach, Florida 33411
                                   305/793-5650

         Turfblock (Monoslab)      Anchor Block Company
                                   P. 0. Box 3360
                                   St. Paul, Minnesota 55165
                                   612/777-8321

                                         137
<pb n="137" />

                                        Table 20
                                        (continued)

           Device or Material                     Manufacturer

           Wave-Maze                Robert L. Stitt
                                    10732 E. Freer Street
                                    Temple City, California

           Z-Wall                   The Fanwall Corporation
                                    670 Old Connecticut Road
                                    Farmingham, Massachusetts 01701
                                    617/879-3350

                                          138
<pb n="138" />

                             OVERVIEW OF THE DESIGN PROBLEM

         CHARACTERIZATION OF THE SITE

              The site to be considered is a sheltered location within an
         estuary. The shoreline is a low bluff about nine feet high. At
         mean low water (MLW), it is fronted by a 15-foot-wide beach. The
         stillwater level is at the toe of the bluff at mean high water
         (MHW).   The bluff slope is approximately 1:1, and the soil is
         fine-grained, mostly sand and silt, with a heavy overgrowth of
         brush and other plants (Figure 90). The number of trees standing
         in the water and lying on the beach is evidence of a long-term and
         chronic erosion problem.      The beach itself consists of fine- to
         coarse-grained material, mostly sand, but      with a   significant frac-
         tion of gravel and cobbles. The       offshore  bottom slope is approxi-
         mately 1 on 33.

                           Figure 90       Design Problem   Site

         WATER LEVELS

              The spring tide range and mean tide level were determined by
         reference to Tide Tables [U.S. Department of Commerce (1976)].
         Local experience indicated that two feet of storm setup was ap-
         propriate.    The site profile and water levels are summarized on
         Figure 91.

                                            139
<pb n="139" />

                              ,-EXISTING BLUFF

                                                                                                  + 3.60' M LW                      DESIGN SWL
                                                                                                                             -4
                                                                                                          MLW                       SPRING   TIDE LE
                                 +0.5' LW_                                         - - - - - -      0.00' MLW                       LOW TIDE LEVE           1.
                                                                           EXISTING OFFSHORE SLOPE-)
                                                                                                               5d

                                                                    FROM LOCAL EXPERIENCE                     FROM TIDE TABLES
                                                                    STORM SURGE z 2,0 FT.                     SPRING TIDE RANGE= 1.70 FT.
                                 (1) BLUFF HEIGHT=9'                                                          MEAN TIDE LEVEL= + 0. 75 FT MLW
                                 (2) BLUFF SLOPE - I on I                                            rho sprinalide ronae is centerdon the meon tide 1"elot 40.75'ML
                                 (3) OFFSHORE SLOPE - Ion 33
                                 (4) MEASURED DEPTH 50' OFFSHORE= 1.5'at MLW                                DESIGN
                                 (5) DEPTH AT SPRING TIDE - 3. C                                            STILLWATER LEVEL                     + 3.60 MLW
                                 (6) STORM SURGE= 2.0'
                                 (7) DESIGN WATER DEPTH -(5)+(6)z3.I',2.O'-5.1'
                                 (8) DESIGN WAVE HE)GHTzDESIGN DEPTH xO.8z5.IxO.8z4.O`                                                          @2.0
                                                                                                          SPRING TIDE LEVEL                        .1.60 M_LW
                                                                                                            MEAN TIDE LEVEL              0.85,     -0.75 MLVJ

                                                                                                     MEAN LOW WATER (MLW)                          0.00

                              Figure 91                         Profile and Physical Conditions at the Site

                     WAVE CONDITIONS

                                 The fastest-mile windspeed for the site is:

                                           10-year: 65 mph

                                 Fetch lengths at the site were displayed earlier on Figure 17.
                     This is reprodu                            as Figure 92 for the convenience of the reader.
                                 Fetch Line t
                                           Length: 2.80 nm x 1.15 = 3.22 mi
                                                               2.80 nm x 6080 = 17,025 ft

                                           Average Depth: 7.2 ft at MLW
                                                                            10.8 ft at design stillwater level

                                 Fetch Line

                                           Lenqth: 2.10 nm x 1.15 = 2.41 mi
                                                               2.10 nm x 6080 = 12,770 ft

                                           Average Depth: 11.6 ft at MLW
                                                                               15.2 ft at design stillwater level
                                 Using Tables 5 to 9, or Equations (5) and (6), find the design
                                                                                                                                        ,ING "TU@EVE@L@O'
                                                                                                                                          T6@L @EC_20
                                                                                                                                                   V
                                 +0  M L W -

                     wave height and period (10-year return period).

                                                                                            140
<pb n="140" />

                                                                                                                                                                           V
                                                                FETCH LINE                                                                                                   .4
                                                                                            2
                                            DEPTHS                                   DEPTHS
                                                                                                                                                                                                            6 5
                                         5                      6                    3            10                12                                                     36        7",
                                                                                                                                                                                  :8
                                                                                                                             .:Mkri
                                                                1              12                 10               @0,04        2                                                                    T,
                                                                                                                                                                                    :9       .............
                                         6                      1              18                   6
                                                                                                                                                  2.:
                                         9                                     18                                            PAS                  10                                      R                                                                 SCA
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                                                                                                                       )W:, 10                    12                                      2                  4
                                        27                      10             14                                                                                                                  IF                                    I                -
                                                                                                                                                  24'Mk,
                                        12                      5              13                                                                 .12                      12 ".2 5T
                                                                                                                                                  ma,ke,
                                    Avg: 7.2'                   MLW        Avg:        11.6' MLW                                                                           13'' ".4                                                            NAUTICA
                                                                                                                                                  Piles                    4.
                                    Fetch Length:                         Fetch Length:                                                                                    -'.14 .3
                                            2.80 nm                                  2.10 nm                                                                               2'
                                                                                                                                                                           10      10
                                                                                                                                                                           P,te PA
                                                                                                                                                                                     Files PA
                                            3.20 mi                                  2.40 mi                                                                               12i
                                                                                                                                                                                   3       14      3:   4

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                                                                                                                                                  16 :7:                                                 5
                                                4                                                                                                                          :31Pi-                                          3 1
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                                                                                                                                                  15                       Dot
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                                                                                                     a                                                                     Aft'
                                                                                                                                                                                  "17"
                                                 . ............                                                                                                                                                   4
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                                                 4              M6

                                                                        R
                                                                                                                                                  7                                  R                                                           NO         0
                                                                       '2' PA  ..........               19                                        4
                                                                                                                                                                                                                                   Bridge Creek privatel
                                                                                             :17

                                                                                                                                                                                                                                                     is marked
                                                                R          _NFI 4sec 15ft 4 M       1  J&amp; A4                                                                                                             I      tained channel
                                                                                     Piles PA 13
                                                                                                                                                                                                                                beacons I thru 19.
                                                                                                                                                  Ard

                                                                                                              Figure                              92                       Fetch Lengths at the Site
<pb n="141" />

                Fetch Line(Dwith F     3.2 mi and WS = 65 mph:

                     Table 6: d = 10 ft; H = 3.0 ft;,T = 4.0 sec,

                     Table 7: d = 15 ft; H = 4.0 ft; T = 4.0 sec

                Therefore, by interpolating for d      10.8 ft; H =   3.2 ft; and
          T   4.0 sec.
                Fetch Line Q with F = 2.4 mi and WS     65 mph:

                     Table 7: d     15 ft; H = 3.5 ft; T = 4.0 sec,

                     Table 8: d     20 ft; H = 4.0 ft; T = 4.0 sec

                Therefore, by interpolating for d         15.2 ft; H      3.5 ft;
          and T = 4.0 sec.
                Fetch Line(D is more critical for design, therefore, use

                                          H = 3.5 feet,

                                     and T = 4.0 seconds.
                This value should be checked against the maximum bre@aking wave
          at the site or just offshore.      (Recall that Fetch Line U1. crosses
          a shoal area near Cedar' Point where the depth is ap roximately 3
          feet under the design stillwater level. Fetch Line )i@l         however,
                                                                   . UZ I
          was more critical for design purposes). With the design stillwater
          condition, the depth at the bluff toe, d     s = 3.1 feet (Figure 90).
                From Figure 18 with,
                                 ds /gT2= (3.1)/32.2 (4.0)2     0.0060,

                          and        m = 0.03

                                 Hb/ds = 0.98
                therefore,          Hb = 3.1 x 0.98 = 3.0 ft
                Therefore, for shoreline protection, use a design wave height
          of 3.0 feet, because that is the maximum that can occur at the site
          under design water level conditions. For any offshore structures,
          such as breakwaters or perched beach sills, the maximum breaker
          height should be checked based on the design depth at the toe of
          the structure.

                                            142
<pb n="142" />

        SELECTION OF DEVICES

        Landowner's Criteria

              1.   No recreational use of the beach for bathing or fishing
                   is anticipated.

              2.   The owner eventually hopes to extend an existing dock to
                   deeper water for berthing a pleasure boat.

              3.   No structures are planned at the top of the bluf f that
                   would interfere with any shore protection devices.

              4.   The shore protection plan should provide about ten years
                   of protection with minimal maintenance requirements.

        Alternatives

        No Action             Inappropriate.   Unacceptable to the landowner.
                              Current erosion  rates represent a considerable
                              financial   loss   at prevailing real estate
                              prices.

        Relocate              Inappropriate.   The land is now undeveloped.
                              The owner will  build a retirement home with a
                              large setback   from the shore.    He desires to
                              stop erosion now.

        Bulkhead              Appropriate. Equipment access to the job site
                              presents no problems. Steps can be added later
                              for access to the dock.      Recreational use of
                              the beach is not a high priority.

        Revetment             Appropriate.   There is sufficient room for a
                              regraded slope.

        Breakwaters           Inappropriate.   Scour at the bluf f toe would
                              not be positively prevented.

        Groins                Inappropriate.    There is little sand-sized
                              material in alongshore transport at the site.

        Beach Fill            Inappropriate.    Fill provides     no    positive
                              protection against toe scour. No recreational
                              beach is desired.    The plan must have minimal
                              maintenance requirements.

        Vegetation            Inappropriate.   Plantings provide no positive
                              protection to the bluff toe.    Coarse soils are
                              not suitable for plantings.

                                           143
<pb n="143" />

          Infiltration and     Inappropriate.   Drainage and infiltration are
          Drainage Controls    not problems at this site.

          Slope Flattening     Inappropriate.   Suitable only in combination
                               with a revetment.     Slope stability is not a
                               basic problem.

          Perched Beach        Inappropriate.   Could be used in combination
                               with a toe protection structure for the bluff
                               (revetment or bulkhead) and vegetation to help
                               retain the beach fill, but this would conflict
                               with owner's desire to extend the existing dock
                               for berthing a pleasure boat. Also, a recrea-
                               tional beach is not desired.

                                           144
<pb n="144" />

                                  PERMIT REQUIREMENTS

               Federal, state, and possibly local permits are required for
          construction in, across, under, or on the banks of navigable waters
          of the United States.     Federal permits are coordinated by the
          applicant and the states through division and district offices of
          the U. S. Army Corps of Engineers, and they are issued as a result
          of two laws, Section 10 of the Rivers and Harbors Act of 1899, and
          Section 404 of the Clean Water Act of 1977, as amended. Section 10
          of the 1899 act requires permits for structures and dredging in
          navigable waters of the United States, which are those coastal
          waters subject to tidal action and inland waters used for inter-
          state or foreign commerce.   In tidal areas, this includes all land
          below the mean high water line.

               On the Great Lakes, permits are required under this section
          for construction lakeward of the highwater mark, the definition of
          which varies from state to state, and may differ from the federal
          definition.  Where doubt exists, an appropriate state agency or
          Corps district office can provide assistance.

               Section 404 of the Clean Water Act mandates a federal permit
          for discharges of dredged or fill material in waters of the United
          States, which include'navigable waters as under Section 10 permits,
          as well as tributaries and wetlands adjacent to navigable waters of
          the United States.   Jurisdiction extends inland to the headwaters
          of streams at a point where the average flow is five cubic feet per
          second. Wetlands are defined as "those areas that are inundated or
          saturated by surface or ground water at a frequency and duration
          sufficient to support, and that under normal conditions do support,
          a prevalence of vegetation typically adapted for life in saturated
          soil conditions. Wetlands generally include swamps, marshes, bogs
          and similar areas" [U. S. Army Corps of Engineers (1977b)].

               A standard application form (ENG Form 4345) must be obtained
          from the local Corps district office. The application must include
          a description of the proposed construction, "including necessary
          drawings, sketches or plans; the location, purpose, and intended
          use of the proposed activity; scheduling of the activity; the names
          and addresses of adjoining property owners; the location and dimen-
          sions of adjacent structures; and the approvals required by other
          federal, interstate, state or local agencies for the work, includ-
          ing all approvals received or denials already made" (U. S. Army
          Corps of Engineers (1977b)).

               Upon receipt of the application, a public notice inviting
          comments on the application is normally issued. The comment period
          is generally 30 days, although it may be longer or shorter, depend-
          ing on the circumstances.    Applications are generally coordinated
          with the appropriate federal, state, and local agencies as well as
          adjacent property owners, sometimes leading to comments that re-
          quire modification of the original proposal. Beyond these possible
          modifications, if the comments received and study conducted by the

                                          145
<pb n="145" />

           Corps reveal no overriding public interest or environmental prob-
           lems, the application is approved and a permit issued. Although
           variations exist, the process normally requires 75 to 90 days for
           routine applications.     Controversial applications can take con-
           siderably longer.

                The Corps has adopted a number of conditional general permits
           on a regional and nationwide basis to reduce red tape and paper-
           work.   No separate application is required for activities where
           general permits have been issued. Applicants should check with the
           local District Engineer to determine if the proposed work is cov-
           ered by a general permit and what conditions may apply.

                Additional information pertinent to local areas is available
           through Corps of Engineers' district offices, or certain state and
           local agencies.    Permit applications should be initiated early to
           avoid unnecessary delays later.

                                            146
<pb n="146" />

                                                                       OTHER HELP

                CORPS OF ENGINEERS OFFICES

                          It is imperative to contact the Corps early to preclude un-
                necessary delays later in the permit application processing. Corps
                offices are also possible sources of information on water levels,
                wave action, and other physical conditions at a site. Mail addres-
                ses, office locations, and phone numbers for Corps personnel fa-
                miliar with coastal processes are given in Table 21.
                                                                               Table 21

                                                                     CORPS OF ENGINEERS OFFICES

                                      Address                                   Phone                            Jurisdiction

                   U. S. Army Engineering Division, New England          617/894-2400 X-554      Atlantic coast from Maine to the Connecticut-
                   424 Trapelo Road                                                              New York Line
                   Waltham, Massachusetts 02154

                   U. S. Army Engineering District, New York             212/264-5174            Atlantic coast of New York and the New
                   26 Federal Plaza                                                              Jersey coast north of Manasquan Inlet
                   New York, New York 10007

                   U. S. Army Engineering District, Philadelphia         215/597-4714            Atlantic coast of New Jersey and Delaware
                   U. S. Custon House                                                            from Manasquan Inlet, south to the Delaware-
                   2nd,:dnd Che:tnut Street                                                      Maryland Line, including Delaware Bay and
                   Phi   elphi , Pennsylvania 19106                                              the C&amp;D Canal

                   U. S. Army Engineering District,  Baltimore           301/962-2545            Atlantic and Chesapeake Bay shorelines of
                   P. 0. Box 1715                                                                Maryland
                   Baltimore, Maryland 21203
                   Office Location: 31 Hopkins Plaza
                   Baltimore, Maryland 21201

                   U. S. Army Engineering District, Norfolk              804/441-3764            Atlantic and Chesapeake Bay shorelines of
                   803 Front Street                                                              Virginia
                   Norfolk, Virginia 23510

                   U. S. Army Engineering District, Wilmington           919/343-4778            Atlantic coast and interior bays and sounds
                   P. 0. Box 1980                                                                of North Carolina
                   Wilmington, North Carolina 28402
                   Office Location: 308 Federal Building
                   Wilmington, North Carolina

                   U. S. Army Engineering District, Charleston           803/724-4248            Atlantic Coast of South Carolina
                   P. 0. Box 919
                   Charleston, South Carolina 29402
                   Office Location: Federal Building
                   334 Meeting Street
                   Charleston, South Carolina 29402

                   U. S Army Engineering District, Savannah              912/944-5502            Atlantic coast of Georgia
                   P* 0. Box 889
                   Savannah, Georgia 31402
                   Office Location: 200 E Saint Julian Street
                   Savannah, Georgia 31402

                   U. S. Army Engineer District, Jacksonville            904/791-2204            Atlantic coast of Florida and Gulf coast of
                   P. 0. Box 4970                                                                Florida to the St. Marks River
                   Jacksonville, Florida 32201
                   Office Location: 400 West Bay Street
                   Jacksonville, Florida 32202

                   U. S. Army Engineering District, Mobile               205/690-3482            Gulf Coast of Florida from the St. Marks
                   P. 0. Box 2288                                                                River west Louisiana-Mississippi line
                   Mobile, Alabama 36628
                   Office Location: 109 St. Joseph Street
                   Mobile, Alabama 36602

                   U. S. Amy Engineering District, New Orleans           504/838-2480            Gulf coast of Louisiana
                   P. 0. Box 60267
                   New Orleans, Louisiana 70160
                   Office Location: Foot of Prytania Street
                   New Orleans, Louisiana 70160

                                                                                147
<pb n="147" />

                                                                                 Table 21
                                                                                (Continued)

                                          Address                                  Phone                           Jurisdiction

                       U. S. Army Engineering District, Galveston           713/764-1211 X -314    Gulf coast of Texas
                       P. 0. Box 1229
                       Galveston, Texas 77553
                       Office Location: 110 Essayons Boulevard
                       400 Barracuda Avenue
                       Galveston, Texas 77550

                       U. S. Army Engineering District, Los Angeles         213/688-5400           Pacific coast of California from the Mexican
                       P. 0. Box 2711                                                              border north to Cape San Martin
                       Los Angeles, California 90053
                       Office Location: 300 North Los Angeles Street
                       Los Angeles, California 90012

                       U. S. Army Engineering District, San Francisco       415/556-5370           Pacific coast of California from Cape San
                       211 Main Street                                                             Martin north to the California-Oregon line
                       San Francisco, California 94105                                             including San Francisco Bay

                       U. S. Army Engineering District, Portland            503/221-6477           Pacific coast of Oregon
                       P. 0. Box 2946
                       Portland, Oregon 97208
                       Office Location: Mulnomah Building
                       319 S.W. Pine
                       Portland, Oregon 97204

                       U. S. Army Engineering District, Seattle             206/764-3555           Pacific coast of Washington and Puget
                       P. 0. Box C-3755                                                            Sound
                       Seattle, Washington 98124
                       Office Location: 4735 East Marginal Way    South
                       Seattle, Washington

                       U. S Army Engineering District, Alaska               907/752-3925           Coast of Alaska
                       P. 0. Box 7002
                       Anchorage, Alaska 99510
                       Office Location: Building 21-700
                       Elmendorf Air Force Base, Alaska

                       U. S. Army Engineering Division, Pacific Ocean       808/438-2837           Hawaii and the Pacific Trust Territories
                       Building 230
                       Ft. Shafter, Hawaii 96858

                       U. S. Army Engineering District, Detroit             313/226-6791           U. S. shorelines of Lakes Superior, Huron
                       P. 0. Box 1027                                                              and St. Clair; the Lake Michigan shoreline
                       Detroit, Michigan 48231                                                     except in Illinois and Indiana; Lake Erie
                       Office Location: Patrick V. McNamara Building                               shoreline of Michigan
                       477 Michigan Avenue
                       Detroit, Michigan 48226

                       U. S. Army Engineering District, Chicago             312/353-0789           Lake Michigan shoreline of Illinois and
                       219 S. Dearborn Street                                                      Indiana
                       Chicago, Illinois 60604

                       U. S. Army Engineering District, Buffalo             716/876-5454 X-2230    U. S. shorelines of Lakes Ontario and Erie
                       1776 Niagara Street                                                         except in Michigan
                       Buffalo, New York 14207

                   STATE COASTAL ZONE MANAGEMENT OFFICES

                            State coastal zone management of f ices can also be sources of
                   information and assistance.                                    Table 22 contains                     addresses             and
                  phone numbers of offices for states that operate coastal zone
                  management programs.

                                                                                148
<pb n="148" />

                                      Table 22

                   STATE COASTAL  ZONE MANAGEMENT PROGRAM OFFICES

             State                    Office Address and Phone Number

        Alabama                   Coastal Area Board
                                  P. 0. Box 755
                                  Daphne, Alabama 36526
                                  205/626-1880

        Alaska                    Division of Policy Development and
                                   Planning
                                  office of the Governor
                                  Pouch AP
                                  Juneau, Alaska 99801
                                  907/465-3541

        California                California Coastal Commission
                                  631 Howard Street, Fourth Floor
                                  San Francisco, California 94105
                                  415/543-8555

        Connecticut               Director, Coastal Area Management Program
                                  Department of Environmental Protection
                                  71 Capitol Avenue
                                  Hartford, Connecticut 06115
                                  203/566-7404

        Delaware                  Coastal Management Program
                                  office of Management, Budget, and Planning
                                  James Townsend Building
                                  Dover, Delaware 19901
                                  302/736-4271

        Florida                   office of Coastal Zone Management
                                  Department of Environmental Regulation
                                  Twin Towers Office Building
                                  2600 Blair Stone Road
                                  Tallahassee, Florida 32301
                                  904/488-8614

        Georgia                   Coastal Resources Division
                                  Department of Natural Resources
                                  1200 Glynn Avenue
                                  Brunswick, Georgia 31520
                                  912/264-4771
        Hawaii                    Department of Planning and Economic
                                    Development
                                  P. 0. Box 2359
                                  Honolulu, Hawaii 96804
                                  808/548-4609

                                         149
<pb n="149" />

                                        Table 22
                                      (Continued)

              State                         Office Address and Phone

          Illinois                  Illinois Coastal Zone Management Program
                                    300 North State Street, Room 1010
                                    Chicago, Illinois 60610
                                    312/793-3126

          Indiana                   State Planning Services Agency
                                    143 West Market Street
                                    Indianapolis,-Indiana 46204
                                    317/2@2-1482

          Louisiana                 Coastal Management Section
                                    Department of Natural Resources
                                    P. 0. Box 44396
                                    Baton Rouge, Louisiana 70804
                                    504/342-7898

          Maine                     State Planning Office
                                    Resource Planning Division
                                    189 State Street
                                    Augusta, Maine 04333
                                    207/289-3155
          Maryland                  Department of Natural Resources
                                    Tidewater Administration
                                    Tawes State Office Building
                                    Annapolis, Maryland 21401
                                    301/269-2784

          Massachusetts             Executive Office of Environmental Affairs
                                    100 Cambridge Street
                                    Boston, Massachusetts 02202
                                    617/727-9530

          Michigan                  Department of Natural Resources
                                    Division of Land Use Programs
                                    Stephens T. Mason Building
                                    Lansing, Michigan 48926
                                    517/373-1950

          Minnesota                 State Planning Agency
                                    550 Cedar Street, Room 100
                                    St. Paul, Minnesota 55155
                                    612/296-2633

                                           150
<pb n="150" />

                                        Table 22
                                      (continued)

              State                         office Address and Phone

        Mississippi                Bureau of Marine Resources
                                   Department of Wildlife conservation
                                   P. 0. Box Drawer 959
                                   Long Beach, Mississippi 39560
                                   601/864-4602

        New Hampshire              office of State Planning
                                   2-1/2 Beacon Street
                                   Concord, New Hampshire 03301
                                   603/271-2155

        New Jersey                 Bureau of Coastal Planning and Development
                                   Department of Environmental Protection
                                   P. 0. Box 1889
                                   Trenton, New Jersey 08625
                                   609/292-9762

        New York                   Coastal Management Unit
                                   Department of State
                                   162 Washington Street
                                   Albany, New York 12231
                                   518/474-8834

        North Carolina             Department of Natural Resources and
                                     Community Development
                                   Box 27687
                                   Raleigh, North Carolina 27611
                                   919/733-2293

        Ohio                       Department of Natural Resources
                                   Division of Water
                                   1930 Belcher Drive, Fountain Square
                                   Columbus, Ohio 43224
                                   614/466-6557

        Oregon                     Land Conservation and Development
                                      commission
                                   1175 Court Street, NE
                                   Salem, Oregon 97310
                                   @503/378-4097

        Pennsylvania               Department   of   Environmental    Resources
                                   Third and Reily Streets
                                   P. 0. Box 1467
                                   Harrisburg, Pennsylvania 17120
                                   717/783-9500

                                          151
<pb n="151" />

                                         Table 22
                                       (continued)

               State                         office Address and Phone

          Rhode Island              Coastal Resources Management Program
                                    Washington County Government Center
                                    Tower Hill Road
                                    South Kingstown, Rhode Island 02879
                                    401/789-3048

          South Carolina            South Carolina Coastal Council
                                    wildlife and Marine Resources Department
                                    1116 Bankers Trust Tower
                                    Columbia, South Carolina 29201
                                    803/758-8442

          Texas                     Natural Resources Division
                                    Texas Energy and Natural Resources
                                     Advisory Council
                                    E.R.S. Building
                                    200 East 18th Street
                                    Austin, Texas 78701
                                    512/475-0773

          Virginia                  Council on the Environment
                                    Ninth Floor, Ninth Street Office Building
                                    Richmond, Virginia 23219
                                    804/786-4500

          Washington                Department of Ecology
                                    PV-11
                                    State of Washington
                                    Olympia, Washington 98504
                                    206/753-4348

          Wisconsin                 Office of Coastal Management
                                    Department of Administration
                                    General Executive Facility 2
                                    101 South Webster Street
                                    Madison, Wisconsin 53702
                                    608/266-3687

                                           152
<pb n="152" />

        OTHER SOURCES OF INFORMATION

        Hydrographic Charts

             Hydrographic charts are     available for a small fee for all
        U. S. coastal waters.     These provide information on water depths
        and fetch lengths to determine the exposure of a site to wave
        action.   Identification of the specific chart and important infor-
        mation about the available chart series are contained in the Nau-
        tical Catalogs given  below. ,

             Catalog No. 1 -  Atlantic and Gulf coasts,
             Catalog No. 2 -  Pacific coast and Hawaii,
             Catalog No. 3 -  Alaska,
             Catalog No. 4 -  Great Lakes.

             For information  or mail orders write to:

                   Distribution Division, C44
                   National Ocean Survey
                   Riverdale, Maryland 20840
                   301/436-6990

             Counter sales are also available at that location as well as
        regional offices of the National Ocean Survey at:

             439 West York Street
             .Norfolk, Virginia 23510

         and

             1801 Fairview Avenue East
             Seattle, Washington 90102

             Charts can also be obtained from the U. S. Coast Guard at the
        locations given below.

             3rd District
             Governors Island
             New York, New York 10004

             9th District
             1240 East 9th Street
             Cleveland, Ohio 44199

        Water Levels

             Tide Tables are available for all coastal areas of the United
        States. These contain predictions of high and low tide elevations
        and their time of occurrence for one calendar year at primary tide
        stations.   Values of time and elevation differences from the pri-
        mary station are also given for numerous secondary stations, as are
        the mean, spring or diurnal tidal ranges for all stations. Tide
        Tables are available from the Distribution Division, National Ocean
        §urvey, at the address above.

                                          153
<pb n="153" />

              Lake levels are also available in summary form through the
         Monthly Bulletin of Lake Levels for the Great Lakes. This contains
         the current level for each of the lakes, a s  Iix-month projection of
         future lake levels, and the historic high and low lake levels. The
         Monthly Bulletin is available, free, from the:

              Department of the Army
              Detroit District, Corps of Engineers
              P. 0. Box 1027
              Detroit, Michigan 48231

         SUGGESTED READING

              Numerous booklets, brochures, and reports, many of them free,
         are available for further study in selected topics and subjects
         presented in this report. Most government reports include either
         their NTIS or GPO accession numbers. Use the NTIS number to order
         documents from:

              National Technical Information Service (NTIS)
              Attention: Operations Division
              5285 Port Royal Road
              Springfield, Virginia   22161
              703/557-4650

         Use the GPO number to order documents from:

              Superintendent of Documents
              U. S. Government Printing office (GPO)
              North Capitol and H Streets, N.W.
              Washington, D.C.   20401
              202/783-3238

                                         154
<pb n="154" />

         Shore and Lake Processes

         Beach Processes and Sedimentation, Komar, P., Prentice-Hall, Engle-
         wood Cliffs, New Jersey, 1976, 464 pp.

         Coastal Processes and Beach Erosion, Caldwell, J. M., R 1-67, U. S.
         Army Coastal Engineering Research Center, January 1967, (NTIS
         #652 025).

         Ebb and Flow: The Tides of Earth, Air and Water, Defant, A., Ann
         Arbor Science Library Series, University of Michigan Press, Ann
         Arbor, Michigan, 1958.                        1

         Land Against the Sea,   Rayner, A. C., editor, MP 4-64, U. S. Army
         Coastal Engineering Research Center, May 1964, (NTIS # 453 227).

         Landslides:   Analysis and Control, Special Report 176, Transpor-
         tation Research Board, National Academy of Sciences, Washington,
         D.C., 1978, 234 pp.

         Mechanics of Coastal Landslides and the Influence of Slope Para-
         meters, Edil, T. B. and Vallejo, L. E., Engineering Geology,
         Vol. 16, 1980, pp. 83-96.

         New Distributions   of Extreme Winds in the United States, Thom,
         H.C.S., Journal,    Structural Division, ASCE, ST 7, July 1968,
         pp. 1787-1801.

         Our New Beach: How It Works, Dade County Beach Erosion Control and
         Hurricane Protection Project, U. S. Army Engineer District, Jack-
         sonville, Jacksonville, Florida, 20 pp. (free).

         A Primer of Basic Concepts of Lakeshore Processes, Duane, D. B.,
         et. al., MP 1-75, U. S. Army Coastal Engineering Research Center,
         January 1975, (NTIS# A008 010).

         Proposed Criteria for Interpreting Stability of Lakeshore Bluffs,
         Edil, T. B. and Haas, B. J., Engineering Geology, Vol. 16, 1980,
         pp. 97-110.

         Shoreline Erosion and Landslides in the Great Lakes, Edil, T. B.
         and Vallejo, L. E., Proceedings of the 9th International Conference
         on Soil Mechanics and Foundation Engineering, 1977, Vol. 2,
         pp. 51-58.

         Shore Processes and Shoreline Development, Johnson, D. W., Wiley-
        .London, 1919, 584 pp.

         Shore Protection Manual (Vols. I, II, and III), U. S. Army Coastal
         Engineering Research Center, 1977, (GPO Stock # 008-022-00113-1).

         Waves and Beaches:   The Dynamics of the Ocean Surface, Bascom, W.,
         Anchor Books, Garden City, New York, 1964.

                                         155
<pb n="155" />

           Shore Protection (General)

           Consumer Investment in Shoreline Protection, Braden, P., Michigan
           Sea Grant Program, 2200 Bonisteel Boulevard, Ann Arbor, Michigan
           48109.

           Harmony With the Lake:     Guide to Bluff Stabilization, Division of
           Water Resources, Illinois Department of Transportation, Room 1010,
           Marina City Office Building, 300 North State Street, Chicago,
           Illinois 60610, (free).

           Help Yourself, North Central Division, U. S. Army Corps of Engi-
           neers, 536 South Clark Street, Chicago, Illinois 60605, (free).

           Low Cost Shore Protection:     Final Report on the Shoreline Erosion
           Control Demonstration Program, Office, Chief of Engineers, U. S.
           Army Corps of Engineers, Washington, D. C., 20314, (1981).

           The Michigan Demonstration Erosion Control Program in 1976, Brater,
           E. F., et al., University of Michigan Coastal Zone Laboratory,
           Michigan Sea Grant Technical Report No. 55, February 1977.

           A Pictorial History of Selected Structures Along the New Jersey
           Coast, Vesper, W. H. and Essick, M. G., MP 5-64, U. S. Army Coastal
           Engineering Research Center, October 1964, (NTIS # 612 764).

           Shore and Beach, American Shore and Beach Preservation Association,
           P. 0. Drawer 2087, Wilmington, North Carolina 28401, (published
           quarterly: $20 annually).

           Shore Ero, sion Control: A  Guide for Waterfront Property Owners in
           the Chesapeake Bay Area, Baltimore District, U.S. Army Corps of
           Engineers, P.O. Box 1715, Baltimore, Maryland 21203, 62 pp.,
           (free).

           Shoreline Erosion Control, Philadelphia District, U. S. Army Corps
           of Engineers, Attention: -NAPEN-P (SECDP), Custom House, Second and
           Chestnut Street, Philadelphia, Pennsylvania 19106 (free).

           Shore Protection Guidelines: National Shoreline Study, Office,
           Chief of Engineers, U. S. Army Corps of Engineers, Washington,
           D. C., August 1971, 59 pp.

           Waves Against the Shore: An Erosion Manual for the Great Lakes
           Region, Lake Michigan Federation, 53 West Jackson Boulevard, Suite
           1710, Chicago, Illinois 60604, January 1978.

           What You May Need to Know About Owning Shore Property, Great Lakes
           Communicator, Volume II, No. 5, February 1981.

                                             156
<pb n="156" />

          Shore Protection Design

          AWPI Technical Guidelines for Pressure-Treated Wood (1970).
          S2 Bulkheads:  Design and Construction - Part I
          S3 Bulkheads:  Design and Construction - Part II
          S4 Bulkheads:  Design and Construction - Part III
          S5 Bulkheads:  Hardware and Fasteners
          Pl Timber Piling
          American Wood Preservers Institute, 1651 Old Meadow Road, McLean,
          Virginia  22101.

          Building Salt Marshes Along the Coast of the Continental United
          States,  Woodhouse, W. W., SR 4, U. S. Army Coastal Engineering
          Research Center, May 1979, (GPO #008-022-00133-6).

          Concrete Shore Protection, Portland Cement Association, 33 West
          Grand Avenue, Chicago, Illinois, 1955.

          Designing for Bank Erosion Control with Vegetation, Knuston, P. L.,
          R 78-2, U. S. Army Coastal Engineering Research Center, February
          1978, (NTIS #A051 571).

          Designing Retaining Walls, Bulkheads and Seawalls of Treated
          Timber, American Wood Preservers Institute (address given above).

          Determination of Mooring Load and Transmitted Wave Height for a
          Floating Tire Breakwater, Giles, M. L., and Eckert, J. W., U. S.
          Army Coastal Engineering Research Center, CETA 79-4, September
          1977, (NTIS # A077 905).

          Dune Building and Stabilization With Vegetation,              Woodhouse,
          W.W., Jr., SR-3, U.S. Army Coastal Engineering Research Center,
          September 1978, (GPO #008-022-00124-7).

          Evaluation of Potential Use of Vegetation for Erosion Abatement
          Along the Great Lakes, Hall, V. L., and Ludwig, J. D., U. S. Army
          Coastal Engineering Research Center, MP 7-75, June 1975, (NITS
           A014 137).

          Evaluation of Tying Materials for Floating Tire Breakwaters, Davis,
          Albert P. J., University of Rhode Island, Marine Technical Re-
          port 54, April 1977.

          Factors Affecting the Durability of Concrete in Coastal Structures,
          Mather, B., TM 96, U. S. Army, Beach Erosion Board, June 1957,
          (NTIS #158 634).

          Floating Tire Breakwaters, Gifford, C. A., et. al, Marine Advisory
          Program, 6022 McCarthy Hall, University of Florida, Gainesville,
          Florida, September 1977, (SUSF-SG-77-002).

          How to Build a Floating Scrap Tire Breakwater, Kowalski, T.and
          Ross, N., Marine Advisory Service, University of Rhode Island,
          Narragansett Bay Campus, Narragansett, Rhode Island 02882.

                                           157
<pb n="157" />

           Planting Guidelines  for Marsh Development and Bank Stabilization,
           Knuston, P. L., CETA 77-3, U. S. Army Coastal Engineering Research
           Center, August 1977, (NTIS #A046 547).

           A Practical Design Method for Flexible Marine Retaining Walls,
           Kaiser Aluminum and Chemical Sales, Inc., 300 Lakeside Drive,
           Oakland, California 94643.

           Review of Design Elements for Beach'Fill Evaluation, Hobson, R. D.,
           U. S. Army Coastal Engineering Research Center, TP 77-6, June 1977,
           (NTIS # A042 748).

           Revised Wave Runup Curves for Smooth Slopes, Stoa, P. N., U. S.
           Army Coastal Engineering Research Center, CETA 78-2, July 1978,
           (NTIS # A058 407).

           The Role of Vegetation in Shoreline Management, Great Lakes Basin
           Commission, P. 0. Box 999, Ann Arbor, Michigan 48106, .(single cop-
           ies, free).

           Salt Marsh Establishment and Development, Garbisch, E. W., Jr., et
           al., U. S. Army Coastal Engineering Research Center, TM 52, June
           1975, (NTIS # A014 136).

           Simplified Design Methods of Treated Timber Structures for Shore,
           Beach and Marina Construction, Ayers, J. and Stokes, R., U. S. Army
           Coastal Engineering Research Center, MR 76-4, March 1976, (NTIS
            A022 337).

           Steel Sheet Piling Design Manual, U. S. Steel Corporation, 1975,
           (ADUSS 25-3848-05).

           SurveV of Coastal Revetment TVpes, McCartney, B. L., U.- S. Army
           Coastal Engineering Research Center, MR 76-7, May 1976, (NTIS
           # A026 255).

           Vse of Plastic Filters in Coastal Structures, Barrett, R. J., Pro-
           ceedings of the 10th International Conference   on Coastal Engineer-
           ing, Tokyo, September 1966.

           Variations in Groin Design, Berg, D. W. and     Watts, G. M., U. S.
           Army Coastal Engineering Research Center, R 4-67, September 1967,
           (NTIS # 659 172).

           Wave Runup on Rough Slopes, Stoa, P. N., U. S. Army Coastal Engi-
           neering Research Center, CETA 79-1, July 1979, (NTIS # A073 354).

           Woven Plastic Cloth Filters for Stone Seawalls, Dunham, J. W. and
           Barrett, R. J., Journal, Waterways, Harbors and Coastal Engineering
           Division, ASCE, Vol. WWI, February 1974, pp. 13-22.

                                          158
<pb n="158" />

         Permits and Regulations

         Permi t Program:  A Guide for Applicants, EP 1145-2-1, U. S. Army
         Corps of Engineers, Washington, D. C.

         Regulations to Reduce Coastal Erosion, Wisconsin Coastal Zone
         Management Program, State Office of Planning and Energy, GEF I1,
         101 South Webster Street, Madison, Wisconsin 53702, (free).

         RegulatorV Program of the Corps of Engineers, Federal Register,
         Tuesday, 19 June 1977.

         Shore Management Guidelines:    National Shoreline Studg, Office,
         Chief of Engineers, U.S. Army Corps of Engineers, Washington, D.C.,
         August 1971.

                                        159
<pb n="159" />

                                      GLOSSARY

         Accretion - Accumulation of sand or other beach material at a point
         due to natural action of waves, currents and wind. A build-up of
         the beach.

         Alongshore - Parallel to and near the shoreline; same as LONGSHORE.

         Apogean Tides - Decreased tidal ranges that occur each month when
         the moon is farthest from the earth (apogee).

         Backhoe - Excavator similar to a power shovel except that the
         bucket faces the operator and is pulled toward him.

         Bar - Fully or partly submerged mound of sand, gravel, or other
         unconsolidated material built on the bottom in shallow water by
         waves and currents.

         Beach - Zond of sand or gravel extending from the low water line to
         a point landward where either the topography abruptly changes or
         permanent vegetation first appears.

         Beach Fill - Sand or gravel placed on a beach by mechanical meth-
         ods.

         Beach, Perched - See PERCHED BEACH.

         Bluff - High, steep bank at the water's edge.     In common usage, a
         bank composed primarily of soil. See CLIFF.

         Boulders   Large stones with diameters over 10 inches. Larger than
         COBBLES.

         Breaker    A wave as it spills, plunges, or collapses on a shore,
         iia-tural obstruction, or man-made structure.

         Breaker Zone - Area offshore where waves break.

         Breaking Depth - Stillwater depth where waves break.

         Breakwater - Structure alined parallel to shore, sometimes shore-
         connected, that provides protection from waves.

         Bulkhead - Structure that retains or prevents sliding of land or
         protects the land from wave damage.

         Clav - Extremely fine-grained soil with individual particles less
         tRzat 0.00015 inch in diameter.

         Cliff - High steep bank at the water's edge.      In common usage, a
         bank composed primarily of rock. See BLUFF.

                                          161
<pb n="160" />

           Cobbles - Rounded stones with diameters ranging from approximately
           3 to 10 inches.      Cobbles are intermediate between GRAVEL and
           BOULDERS.

           Crest   Upper edge or limit of a shore protection structure.

           Culm   Single stem of grass.

           Current - Flow of water in a given direction.

           Current, Longshore - Current in the breaker zone moving essentially
           parallel to shore and usually caused by waves breaking at an angle
           to shore. Also called alongshore current.

           Deep Water - Area where surface waves are not influenced by the
           bottom.  Generally, a point where the depth is greater than one-
           half the surface wavelength.

           Diffraction- Progressive reduction in wave height when a wave
           spreads into the shadow zone behind a barrier after the wave has
           passed its end.

           Diurnal - Period or cycle lasting approximately one day. A diurnal
           tide has one high and one low in each cycle.

           Downdrift   Direction of alongshore movement of littoral materials.

           Dune - Hill, bank, bluff, ridge, or mound of loose, wind-blown
           i-aterial, usually sand.

           Duration - The length of time the wind blows in nearly the same
           directi'on across a FETCH (generating area).

           Ebb Tide - Part of the tidal cycle between high water and the next
           low. The falling tide.

           Equatorial Tides - Tides that occur semimonthly as the result of
           the moon beinTover the equator.      At these times the tendency of
           the moon to cause an inequality in mixed tides is minimized.

           Equilibrium - State of balance or equality of opposing forces.

           Erosion - Wearing away of land by action of natural forces.

           Fetch - Area where waves are generated by wind which has steady
           a@irection and speed. Sometimes called FETCH LENGTH.

           Fetch Length - Horizontal direction (in the wind direction) over
           which a wind generates waves.       In sheltered waters, often the
           maximum distance that wind can blow across water.

           Filter Cloth - Synthetic textile with openings for water to escape,
           but which prevents passage of soil particles.

                                           162
<pb n="161" />

          Flood Tide - Part of the tidal cycle between low water and the next
          high.      rising tide.

          Glacial Till - Unstratified glacial drift consisting of unsorted
          clay, sand, gravel, and boulders intermingled.

          Gravel   Small, rounded granules of rock with individual diameters
          ranging from 3.0 to 0.18 inches. Gravels are intermediate between
          SAND and COBBLES.

          Groin - Shore protection structure built perpendicular to shore to
          trap sediment and retard shore erosion.

          Groin Field - Series of groins acting together to protect a section
          of beacS_.Also called a groin system.

          Grout - Mixture of portland cement, fine aggregates (usually sand),
          and water.   Usually used to seal openings or fill bags or other
          containers.'

          H-Pile- Straight length of structural steel with an H-shaped cross
          ie`ction designed for driving into the earth.

          High Tide    Maximum elevation reached by each rising tide.       see
          also TIDE.

          High Water   See HIGH TIDE.

          High Water Line - Intersection of the level of MEAN HIGH WATER with
          the shore.   Shorelines on navigation charts are approximations of
          the high water line.

          Hogwire - Short, smooth-wire fencing of the kind normally used to
          enclose a pig sty.

          Impermeable - Not having openings large enough to permit water to
          freely pass.

          International Great Lakes Datum (IGLD) - Common reference datum for
          the Great Lakes area based on mean water level in the St. Lawrence
          River at Father Point, Quebec, and established in 1955.

          Intertidal Zone   Land area alternately inundated and uncovered by
          tides. Usually considered to extend from MEAN LOW WATER to MEAN
          HIGH WATER.

          Lee - Sheltered; part or side facing away from wind or waves.

          Leeward - Direction toward which wind is blowing or waves are
          travelling.

          Littoral Material - Sediments moved in the LITTORAL ZONE by waves
          and currents. Also called littoral drift.

                                         163
<pb n="162" />

          Littoral Transport    Movement of LITTORAL MATERIAL by waves and
          currents.

          Littoral Zone - Indefinite zone extending from the shoreline to
          just beyond the breaker zone.

          Longshore - Parallel to and near the shoreline:      same as ALONG-
          SHORE.

          Longshore Transport Rate - Rate of transport of littoral material
          parallel to shore.    Usually expressed in cubic yards per year.

          Low Tide - Minimum elevation reached by each falling tide.

          Low Water Datum (LWD) - The elevation of each of the Great Lakes to
          which are referenced the depths shown on navigation charts and the
          authorized depths of navigation projects.

          Low Water Line - Intersection of the low tide level with shore.

          Marsh - Area of soft, wet, or periodically inundated land, gener-
          ally treeless, and usually characterized by grasses and other low
          growth.

          Mean Higher High Water (MHHW)   Average height of the daily higher
          high water over a 19-year period.    Only the higher high water of
          each of the high waters of a tidal day is included in the mean.

          Mean High Water (MHW) - Average height of the daily high waters
          over a 19-year period.    For semidiurnal or mixed tides, the two
          high waters of each tidal day are included in the mean.          For
          diurnal tides, the single daily high water is used to compute    the
          mean.

          Mean Lower Low Water (ML@@ - Average height of the daily lower   low
          waters of a 19-year period. Only the lower low water of each pair
          of low waters of a tidal day is included in the mean. Long used as
          the datum for Pacific coast navigation charts, it is now gradually
          being adopted for use across the United States.

          Mean Low Water (MLW) - Average height of the low waters over a
          19-year period.   For semidiurnal and mixed tides, the two low
          waters of each tidal day  are included in the mean.   For a diurnal
          tide, the one low water of each tidal day is used in the mean.
          Mean Low Water has been   used as datum for many navigation charts
          published by the National Ocean Survey, but it is being phased out
          in favor of Mean Lower Low Water for all areas of the United
          States.

          Mean Sea Level - Average height of the sea surface over a 19-year
          period. Not necessarily equal to MEAN TIDE LEVEL.

                                         164
<pb n="163" />

          Mean Tide Level - Plane midway between MEAN HIGH WATER and MEAN LOW
          WATER.  Not necessarily equal to MEAN SEA LEVEL.          Also called
          half-tide level.

          Mixed Tide - A tide in which there is a distinct difference in
          height      een successive high and successive low waters.          For
          mixed tides there are generally two high and two low waters each
          tidal day.   Mixed tides may be described as intermediate between
          semidiurnal and diurnal tides.

          Module - A  structural component, a number of which are joined to
          make a whole.

          National Geodetic Vertical Datum (NGVD) - Datum of the United
          States geodetic level net.     Mean Sea Level varies slightly from
          this datum from place to place along the shores of the nation.

          Neap Tides - Tides with decreased ranges that occur when the moon
          is at first or last quarter, and the pull of the. sun and moon are
          in opposition to each other.     The neap range is smaller than the
          mean range for semidiurnal and mixed tides.

          Nearshore - In beach terminology, an indefinite zone extending
          seaward from the shoreline well beyond the breaker zone.

          Nourishment - Process of replenishing a beach either naturally by
          longshore transport, or artificially by delivery of materials
          dredged or excavated elsewhere.

          offshore - (1) (Noun) In beach terminology, comparatively flat zone
          of variable width extending from the breaker zone to the seaward
          edge of the Continental Shelf.     (2) (Adjective) Direction seaward
          from the shore.

          OvertopRinq -  Passing of water over a structure from wave runup or
          surge actlon.

          Peat - Residual product produced by partial decomposition of or-
          ganic matter in marshes and bogs.

          Peat Pot (vegetation) - Pot formed from compressed peat and filled
          @i_i@ther with soil or peat moss in which a plant or plants, grown
          from seed, are transplanted without being removed from the pot.

          Perched Beach - Beach or fillet of sand retained above the other-
          wise normal profile level by a submerged dike or sill.

          Perigean Tides   Increased tidal ranges that occur each month when
          the moon is closest to the earth (perigee).

          Permeable - Having openings large enough to permit free passage of
          appreciable quantities of sand or water.

                                          165
<pb n="164" />

          Pile - Long, heavy section of timber, concrete or metal driven or
          Te-tted into the earth or seabed as support or protection.

          Pile, Sheet - Pile with a generally slender, flat cross section
          driven into the ground or seabed and meshed or interlocked with
          like members to form a diaphragm, wall, or bulkhead.

          Piping - Fluidizing of backfill or an embankment to the extent that
          large quantities of material are pumped by wave action through
          holes under or through a bulkhead or revetment.

          Plasticity - As applied mainly to clay, the relative ease with
          which the material yields or deforms under pressure.

          Plug - core containing both plants and underlying soil, usually cut
          with a cylindrical coring device and transplanted to a hole cut by
          the same device.

          Polyvinyl Chloride (PVC) - Plastic material (usually black) that
          forms a resilient coating suitable for protecting metal from corro-
          sion.

          Profile, Beach - Intersection of the ground surface with a vertical
          plane that may extend from the top of the dune line to the seaward
          limit of sand movement.

          PVC - (see POLYVINYL CHLORIDE).

          Ravelling - Progressive deterioration of a revetment under wave
          iiE`tion.

          Refraction (of water waves) - (1) Process by which direction of a
          wave moving in shallow water at an angle to the contours is
          changed. Part of the wave advancing in shallower water moves more
          slowly than the part still advancing in deeper water, causing the
          wave crest to bend toward alinement with the underwater contours.
          (2) Bending of wave crests by currents.

          Revetment - Facing of stone, concrete, etc., to protect a scarp
          embankment, or shore structure against erosion by waves or cur-
          rents.

          Rhizome - Underground stem or root stock. New shoots are usually
          produced from the tip of the rhizome.

          Riprap - Layer, facing, or protective mound of stones randomly
          placed to prevent erosion, scour, or sloughing of a structure or
          embankment; also, the stone so used.

          Rubble - (1) Loose, angular, waterworn stones along a beach.     (2)
          Rough, irregular fragments of broken rock or concrete.

                                         166
<pb n="165" />

          Runup - The rush of water up a structure or beach on breaking of a
          wave.   Amount of runup is the vertical height above stillwater
          level that the rush of water reaches.

          Sand - Generally, coarse-grained soils having particle diameters
          between 0.18 and approximately 0.003 inches.         Sands are inter-
          mediate between SILT AND GRAVELS.

          Sandbag - Cloth bag f illed with sand or grout and used as a module
          in a shore protection device.

          Sand Fillet- Accretion trapped by a groin or other protrusion in
          the lit     1 zone.

          Scour - Removal of underwater material by waves or currents, espe-
          a=ally at the base or toe of a shore structure.

          Screw Anchor - Type of metal anchor screwed into the bottom for
          holding power.

          Seawall - Structure separating land and water areas primarily to
          prevent erosion and other damage by wave action.        See also BULK-
          HEAD.

          Semidiurnal Tide - Tide with two high and two low waters in a tidal
          day, each high and each low approximately equal in stage.

          Setup, Wind - Vertical rise in the stillwater level on a body of
          water caused by piling up of water on the shore due to wind action.
          Synonymous with wind tide and STORM SURGE. STORM SURGE usually
          pertains to the ocean and large bodies of water. Wind setup usu-
          ally pertains to reservoirs and smaller bodies of water.

          Shallow Water - Commonly, water of such a depth that surface waves
          are noticeab y affected by bottom topography.       It is customary to
          consider water of depths less than one-twentieth the surf ace wave-
          length as shallow water.

          Sheet Pile - see PILE, SHEET.

          Shoal - (noun) Rise of the sea bottom from an accumulation of sand
          or other sediments.      (verb) - (1) to become shallow gradually.
          (2) To cause to become shallow. (3) to proceed from a greater to a
          lesser U-epth of water.

          Shoot - Collective term applied to the STEM and leaves or any
          growing branch or twig.

          Shore - Narrow strip of land in immediate contact with the sea,
          including the zone between high and low water lines. A shore of
          unconsolidated material is usually called a beach.

                                           167
<pb n="166" />

           Shoreline - Intersection of a specified plane of water with the
           shore or beach (e.g., the high water shoreline would be the inter-
           section of the plane of mean high water with the shore or beach).
           The line delineating the shoreline on National Ocean Survey nauti-
           cal charts and surveys approximates the mean high water line.

           Sill - Low offshore barrier structure whose crest is usually sub-
           merged, designed to retain sand on its landward side.

           Silt - Generally refers to fine-grained soils having particle
            r__
           Uiameters between 0.003 and 0.00015 inches.        Imtermediate between
           CLAY and SAND.

           Slope - Degree of inclination to the horizontal. Usually expressed
           as a ratio, such as 1:25 or 1 on 25, indicating 1 unit vertical
           rise in 25 units of horizontal distance; or in degrees from hori-
           zontal.

           Sloughing - Process where a weakened mass of soil fails and moves
           downslope.

           Sprig - Single plant with its relatively bare roots, as pulled
           apart from a clump and used for transplanting.

           Spring Tides - Increased tidal ranges that occur semimonthly when
           the moon is new or full and the pull of the sun and moon are nearly
           in phase. The spring range is larger than the mean range for semi-
           diurnal or mixed tides.

           Stem - Main axis of a plant, leaf-bearing and flower-bearing, as
           air-s-tinguished from the root-bearing axis.

           Stillwater Level - Elevation that the surface of the water would
           assume if all wave action were absent.

           Storm Surqe - Rise above normal water level on the open coast due
           Eo -action of wind on the water surface. Storm surge resulting from
           a hurricane also includes the rise in level due to atmospheric-
           pressure reduction as well as that due to wind stress. See SETUP,
           WIND.

           Suspended Load - Material moving in suspension in a turbulent
           field.

           Swell - Wind-generated waves travelling out of their generating
           area.   Swell characteristically exhibits a more regular and longer
           period and has flatter crests than waves within their fetch.

           Tidal Period - Interval between two consecutive like phases of the
           tide.
           Tidal IRanqe - Difference in height between consecutive high and low
           (or higher high and lower low) waters. The mean range is the dif-

                                             168
<pb n="167" />

          ference in height between mean high water and mean low water. The
          diurnal range is the difference in height between mean higher high
          water and mean lower low water.    For diurnal tides, the mean and
          diurnal range are identical.   For semidiurnal and mixed tides, the
          spring range is the difference in height between the high and low
          waters during the time of spring tides.

          Tide - Periodic rising and falling of water resulting from gravi-
          Ta-T-lonal attraction of the moon, sun and other astronomical bodies
          acting upon the rotating earth.    Although the accompanying hori-
          zontal movement of the water resulting from the same cause is also
          sometimes called tide, it is preferable to designate the latter as
          tidal current, reserving the name TIDE for vertical movement.

          Tide, Ebb - See EBB TIDE.

          Tide Station - Place at which tide observations are being taken. A
          primary tide station is a location where continuous observations
          are taken over a number of years to obtain basic tidal data for the
          locality. A secondary tide station is operated over a short period
          of time to obE-ain data for a specific purpose.

          Tiller - A plant shoot which springs from the root or bottom of the
          original plant stalk.

          Topography - Configuration of a surface, including relief, position
          of streams, roads, buildings, etc.

          Transplant - SHOOT or CULM removed from one location and replanted
          in another.

          Trough of Wave - Lowest part of a waveform between successive
          crests. Also, that part of a wave below stillwater level.

          Tropical Tides - Tides that occur  .semimonthly when the declination
          of the moon is maximized.   During these times, the diurnal range
          tends to be greatest.

          Updrift - Direction opposite the predominant movement of littoral
          materials in longshore transport.

          Wake (boat) - Waves generated by the motion of a vessel through
          water.

          Wale - Horizontal beam on a bulkhead used to transfer horizontal
          loads against the structure laterally along it and hold it in a
          straight alinement.

          Waterline - Juncture of land and sea. This line migrates, changing
          with the tide or other fluctuation in water level. Where waves are
          present on the beach, this line is also known as the limit of
          backrush. (Approximately, the intersection of land with the still-
          water level.)

                                         169
<pb n="168" />

          Wave - Ridge, deformation, or undulation of the surface of a
          liquid.

          Wave Climate - Normal seasonal wave regimen along a shoreline.

          Wave Crest - Highest part of a wave or that part above the still-
          water level.

          Wave Diffraction - See DIFFRACTION.

          Wave Direction - Direction from which a wave approaches.

          Wave Height    Vertical distance between a crest and the preceding
          trough.

          Wavelength     Horizontal distance between similar points on two
          successive waves measured perpendicular to the crest.

          Wave Period - Time in which a wave crest traverses a distance equal
          to one wavelength. Time for two successive wave crests to pass a
          fixed point.

          Wave Refraction   See REFRACTION (of water waves).

          Wave Steepness   Ratio of wave height to wavelength.

          Wave Train   Series of waves from the same direction.

          Wave Trough   Lowest part of a wave form between successive crests.
          Also, that part of a wave below stillwater level.

          Weep Hole - Hole through a solid revetment, bulkhead, or seawall
          for relieving pore pressure.

          Wind Setu2 - See SETUP, WIND.

          Windward   Direction from which wind is blowing.

          Wind Waves - (1) Waves being formed and built up by wind.         (2)
          Loosely, any waves generated by wind.

                                         170
<pb n="169" />

                                  LITERATURE CITED

         American Wood Preservers' Association, "Standard C18-77: Standard
         for Pressure Treated Material in Marine Construction", 1977.

         American Wood Preservers Institute, 11AWPI Technical Guidelines for
         Pressure  Treated Wood - S2 Bulkheads:    Design and Construction -
         Part 1", 1970.

         Bertram, G. E., "An Experimental Investigation of Protective
         Filters", Harvard University Publication 267, January 1940.

         Davis, A. P., Jr., "Evaluation of Tying Materials for Floating Tire
         Breakwaters", Marine Technical Report 54, University of Rhode
         Island, April 1977.

         Giles, M. L. and Eckert, J. W., "Determination of Mooring Load and
         Transmitted Wave Height for a Floating Tire Breakwater", CETA 79-4,
         U. S. Army Corps of Engineers, Coastal Engineering Research Center,
         Ft. Belvoir, Virginia, September 1979.

         Hall, J. V., Jr., and Jachowski, R. A., "Concrete Block Revetment
         Near Benedict, Maryland", MP 1-64, U. S. Army Corps of Engineers,
         Coastal Engineering Research Center, Ft. Belvoir, Virginia, January
         1964.

         Harris, D. L., "Tides and Tidal Datums in the United States", SR 7,
         U. S. Army Corps of Engineers, Coastal Engineering Research Center,
         Ft. Belvoir, Virginia, February 1981.

         Hobson, R. D., "Review of Design Elements for Beach Fill Evalua-
         tion", TP 77-6, U. S. Army Corps of Engineers, Coastal Engineering
         Research Center, Ft. Belvoir, Virginia, June 1977.

         Lambe, T. and Whitman, R. W., Soil Mechanics, John Wiley and Sons,
         Inc., New York, 1969.

         Mather, B., "Factors Affecting the Durability of Concrete in
         Coastal Structures", TM-96, U.S. Army Corps of Engineers, Beach
         Erosion Board, Washington, D. C., June 1957.

         Neill, C. R., "Dynamic Ice Forces on Piers and Piles: An Assess-
         ment of Design Guidelines in Light of Recent Research", Canadian
         Journal of Civil Engineering, Vol. 3, 1976, pp. 305-341.

         Seelig, W., "Estimation of Wave Transmission Coefficients for
         Overtopping of Impermeable Breakwaters", CETA 80-7, U. S. Army
         Corps of Engineers, Coastal Engineering Research Center, Ft.
         Belvoir, Virginia, December 1980.

         Stoa, P. N., "Revised Wave Runup Curves for Smooth Slopes", CETA
         78-2, U. S. Army Corps of Engineers, Coastal Engineering Research
         Center, Ft. Belvoir, Virginia, July 1978.

                                        171
<pb n="170" />

           Stoa, P. N., "Wave Runup on Rough Slopes", CETA 79-1, U. S. Army
           Corps of Engineers, Coastal Engineering Research Center, Ft.
           Belvoir, Virginia, July 1979.

           Thom, H.C.S., "New Distributions of Extreme      Winds in the United
           States", Journal of the Structural Division,     ASCE, No. ST7, July
           1968, pp. 1787-1801.

           U. S. Army Corps of Engineers, "Plastic Filter   Fabric", Civil Works
           Guide Specification CW 02215, Office, Chief of Engineers, Washing-
           ton, D. C., 1977a.

           U. S. Army Corps of Engineers, "Regulatory Program of the Corps of
           Engineers", Federal Register, Vol. 42, No. 138, Washington, D. C.,
           Tuesday, 19 July 1977b.

           U. S. Army Corps of Engineers, "Shore Protection Manual", Coastal
           Engineering Research Center, Ft. Belvoir, Virginia, 1977c.

           U. S. Army Corps of Engineers, "Geneva State Park, Ohio, Shore
           Erosion Control Demonstration Program, Preconstruction Report",
           Engineer District, Buffalo, February 1978a.

           U. S. Army Corps of Engineers, "Pickering Beach, Delaware: Precon-
           struction Report", Engineer District,     Philadelphia., April 1978b.

           U. S. Army Corps of Engineers, "Kitts    Hummock, Delaware: Precon-
           struction Report", Engineer District,     Philadelphia, April 1978c.

           U. S. Army Corps of Engineers, "Help     Yourself:   A Discussion of
           Erosion Problems on the Great Lakes      and Alternative Methods of
           Shore Protection", Engineer Division, North Central, September
           1978d.

           U. S. Army Corps of Engineers, "Bank    Erosion Control with Smooth
           Cordgrass and Saltmeadow Cordgrass on   the Atlantic Coast", TN-V-2,
           Coastal Engineering Research Center,    Ft. Belvoir, Virginia, March
           1980a.

           U. S. Army Corps of Engineers, "Engineering and Design: Ice Engi-
           neering",  Engineering Circular 1110-2-220, Washington, D. C.,
           October 1980b.

           U. S. Army Corps of Engineers, "Monthly Bulletin of Lake Levels for
           the Great Lakes", Engineer District, Detroit, March 1981a.

           U. S. Army Corps of Engineers, "Method of Determining Adjusted
           Windspeed, U . for Wave Forecasting", CETN-I-5, Coastal Engineering
           Research Cen er, Ft. Belvoir, Virginia, March 1981b.

           U. S. Army Corps of Engineers, "Revised Method for Wave Forecasting
           in Shallow Water", CETN-1-6, Coastal Engineering Research Center,
           Ft. Belvoir, Virginia, March 1981c.

                                           172
<pb n="171" />

        U.S. Army Corps of Engineers, "Low Cost Shore Protection: Final
        Report on the Shoreline Erosion Control Demonstration Program,"
        Office, Chief of Engineers, Washington, D.C., 1981d.
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                                                    1981

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