[From the U.S. Government Printing Office, www.gpo.gov]







                               State of Mississippi





                   MARINE CONSTRUCTION STANDARDS


                 FOR SHORELINE EROSION CONTROL AND


                     SHOREFRONT ACCESS FACILITIES















                          Zl









                       Department of Wildlife, Fisheries and Parks

                            Bureau of Marine Resources











                              State of Mississippi

                         MARINE CONSTRUCTION STANDARDS
                       FO SHORELINE EROSION CONTROL AND
                          SHOREFRONT ACCESS FACILITIES





                                  September 1991



                                       by

                      OFFSHORE & COASTAL TECHNOLOGIES, INC.
                                  P.O. Box 1679
                 Z7@      Vicksburg, Mississippi 39181



                                       for


                              STATE OF MISSISSIPPI

                   Department of Wildlife, Fisheries and Parks

                           Bureau of marine Resources
                              2620 Beach Boulevard
                           Biloxi, Mississippi 39531



                   This document was f unded in part through a
                   federal grant administered by the Office of
                        @@Om















                   Ocean and Coastal Resource Management under
                   provisions of the Coastal Zone Management
                   Act of 1972, as amended.




















                        The State of Mississippi Department
                        of Wildlife, Fisheries and Parks
                        presents this information as a public
                        service. Inclusion of any shoreline
                        erosion control or shorefront access
                        method does not necessarily consti-
                        tute a recommendation, nor is it a
                        guarantee that any particular method
                        will be successful for a specific
                        application.










                                  TABLE OF CONTENTS







                    PURPOSE  . . . . . . . . . .. . . . . . .      1


                    GENERAL DESIGN   . . . . . . . . . . . . .     2
                          Design Considerations   . . . . . . .    2
                          Design Methodology    . . . . . . . .  10

                    SHORELINE EROSION CONTROL STRUCTURES     . . 11


                          Description of Shorelines   . . . . .  11
                          Shore Protection Methods  . . . . . .  12
                          Impacts of Various Erosion
                          Control Structures    . . . . . . . .  14
                          Specific Design Recommendations        16
                               Bulkheads                         16
                               Revetments                        18
                               Breakwaters                       19
                               Vegetation                        22

                    SHOREFRONT ACCESS FACILITIES    . . . . . .  24
                          Description of Access Facilities. .    24
                          Specific Design Recommendations . .    25
                               Small Craft Launch Ramps          25
                               Piers                             29
                               Berthing Facilities               33
                               Dredged Boat Slips                36
                               Boat Houses                       37


                    CONCLUSION   . . . . . . . . . . . . . . .   38


                    REFERENCES   . . . . . . . . . . . . . . .   39










                                       PLFRPOSE

                    The objective of this pamphlet is to present
                    alternatives for shoreline erosion pro-
                    tection    and   shorefront    access     while
                    protecting or enhancing coastal habitats.

                    This set of standards is intended to be
                    useful in aiding the understanding of
                    options available to individuals for shore-
                    line erosion control and shoreline access.

                    This publication presents an overview of
                    typical designs for coastal structures,
                    including shore erosion control structures
                    and structures associated with shoreline
                    access.    It does not provide a complete
                    guide for design and construction of these
                    structures.   A variety of sources such as
                    publications of the U.S. Army Corps of
                    Engineers can provide additional, more
                    detailed information on specific design
                    problems. Coastal Engineers and experienced
                    local contractors can also help ensure a
                    successful project.      Additional guidance
                    relating to construction and environmental
                    considerations    can   be   found    in    the
                    Mississippi Coastal Program, also published
                    by the Mississippi Department of Wildlife,
                    Fisheries, and Parks.

                    All persons must obtain authorization for
                    any project in the tidal waters of the State
                    of   Mississippi    from    the    Mississippi
                    Department of Wildlife, Fisheries, and Parks
                    before construction begins.        Also, the
                    Vicksburg or Mobile District Corps of
                    Engineers    should   be   contacted     before
                    projects are begun in non-tidal waters of
                    the State.










                                    GENERAL DESIGN

                      Design Considerations

                      In designing a structure, numerous decisions
                      on structure location, height and shape must
                      be made.   The factors most important to
                      structure design include water levels, wave
                      heights, and envi'ronmental impacts.   Other
                      considerations include toe protection, soil
                      properties, filtering, and flank protection.

                      Water Levels determine required elevations
                      of structures to prevent overtopping and
                      structural damage.    In tidal waters, the
                      water level is a combination of the tide and
                      a storm surge.   Spring tide levels, typi-
                      cally around 2 feet in Mississippi, can be
                      determined from Tide Tables published by the
                      National Ocean Survey. Storm surge levels
                      can be determined from local experience or
                      from Federal Emergency Management Agency
                      (FEMA) publications.   Typical storm tides
                      range from 4 to 7 f eet in coastal waters.
                      In extreme hurricanes the storm tide can
                      reach up to 20 f eet.   Most structures in
                      protected coastal waters have finished
                      elevations of 3 to 5 feet above mean high
                      tide, while structures in unprotected areas
                      reach heights of 7 feet above mean high
                      tide.

                      Wave heights can be limited by the depth of
                      water at the site.    The maximum breaking
                      wave height is approximately equal to the
                      depth of water. If the bottom material in
                      front of a structure is easily eroded, such
                      as sand or soft mud,, the water depth at the
                      toe of the structure may increase over time.
                      In this case either toe scour protection
                      should be provided, or allowance should be
                      made for increased water depth due to scour.


                                           2








                     Wave Runup determines the height to which a
                     shoreline erosion control structure should
                     be constructed to avoid overtopping and
                     damage to the back of the structure. Runup
                     is shown in the figure below.









                                                     WAVE RUNUP ELEVATION
                      WIND GENERATED WAVES          WAVE RUNUP

                                                      DESIGN WATER LEVEL


                                             STORM SURGE


                                                         TIDE LEVEL








                     Figure 1, Wave Runup
                     (University of Wisconsin Sea Grant, 1987)

                     Runup will typically range from equal to the
                     design wave height for a stone revetment to
                     twice the wave height for a vertical face
                     bulkhead.


                     Typically it is not cost effective to
                     eliminate all overtopping by building an
                     extremely tall structure. In many cases it
                     will be more economical to allow some
                     overtopping during large storms.       In this
                     case,    the    structure     design     should
                     incorporate measures to minimize erosion
                     behind    the   structure     due   to     wave



                                            3








                      overtopping. This can include a rock apron
                      or paving behind a bulkhead or revetment, or
                      erosion resistant vegetation such as turf
                      grass planted behind the structure.

                      Design Level refers to the level of
                      protection   for   which   a   structure     is
                      designed. For instance, a structure can be
                      designed to survive a storm which occurs on
                      the average of once in 10 years more cheaply
                      than it can be designed to withstand a storm
                      which occurs on the average of once in 25
                      years. However, the risk that the structure
                      will be damaged during it's lifetime will be
                      greater for the 10 year design than the 25
                      year design.

                      It is recommended that permanent residential
                      protection structures be designed for a
                      minimum return period of 10 years, and
                      preferably 25 years.     Structures designed
                      for 10 year return periods can be expected
                      to require regular significant maintenance
                      costs.    Structures designed for 25 year
                      return periods will require less regular
                      maintenance, but may occasionally be damaged
                      by large storms. Major projects should be
                      designed for a 50 to 100 year return period.














                                            4








                    Toe Protection is armoring in front of a
                    structure to prevent waves from removing the
                    sediment and undercutting the structure.
                    Bulkheads typically require rubble toe
                    protection, as illustrated in Figure 2.
                    Stone structures often have additional
                    material placed at the toe to prevent scour
                    and damage to the structure.





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




                    SCOUR AT                      FILTER
                      70E                         CLOTH















                    Figure 2, Typical Bulkhead Toe Protection
                    (U.S. Army Corps of Engineers, 1981)

                    Filtering is generally required if fine
                    material is to be confined by a structure.
                    A filter layer can either consist of graded
                    stone, a synthetic filter fabric, or often
                    a combination of the two.     The ef f ect of
                    inadequate or no filtering versus a proper
                    filter design is illustrated in Figure 3.



                                         5
















                                WITHOUT FILTER           WITH FILTER




                            INIrIAL
                            POSMON   Soil and water posses through ML@LV
                                     gaps between stones
                             MLW&                    GRADED
                                                     SrONE
                                     J               FIL rER




                                                                       -S-11111 rticies
                                                                       cannot penetrate
                                           @Ground.oter
                                                                       filter.
                                            flow
                                                     Water east rough
                                                     structure

                            FINAL
                           POSMON    Erosion                MLW
                              MLWV   continue        SYNrHErIC
                                                     FIL rER
                                                     cLorH



                                                                  Synthetic filter cloth

                               a. n -                          Water con pass throuith filter
                                                               Cloth but soil particles cannot
                                                                                I
                          Figure 3, Filtering for Stone Structures
                          (U.S. Army Corps of Engineers, 1981)


                          Flank Protection is often required because
                          many shoreline erosion control structures
                          are vulnerable to erosion around the end of
                          the structure, which can lead to failure.
                          Return sections are recommended during
                          initial construction, as shown in Figure 4,
                          although in many cases periodic increases in
                          the length of the return structure may be
                          necessary as erosion in adjacent unprotected
                          areas continues.




                                                     6










                                    @E XIST ING
                                      SH0RELINE               BULKHEAD@@
                                              L/ Z., @11 7171-1111-1177@
                                                             if X* No XXX

                                                       (initial Construction)         BREAKING
                                                                                      WAVES




                                                                                  RETREATED
                                                                                  SHOff@_._
                                                               BULKHEAD-\
                                    BREAKING@
                                     WAVES            (Without Flonk Protection)













                                 RETURN                        BULKHEAD
                                  WALLS


                                            BREAKING WAVES



                                                        (With Flank Protection)
                                   ETURN
                                  WALLS


                                              I A I1 1-11 @ I





                               Figure 4, Schematic Flank Protection
                               (U.S. Army Corps of Engineers, 1981)



                                                                7







                       Soil Properties are important to the long
                       term   stability   of coastal structures.
                       Settlement, pile embedment, toe stability
                       and scour are determined by the surface soil
                       properties.

                       For small private projects, the knowledge of
                       local contractors is often the best source
                       of information on requirements for pile
                       embedment, settlement and scour. For larger
                       projects, a soils exploration program will
                       be.justified.


                       General suitability of various general soil
                       types for coastal structures is as follows:

                       Gravel: Difficult driving for sheet piling.
                       Excellent for stone structures. Not usually
                       found in Coastal Mississippi except near
                       rivers.

                       Sand, Silty Sands:    Good for sheet piling,
                       but toe protection will be required.
                       Suitable for stone structures, but stone
                       structures  will also generally require toe
                       protection.    Commonly found along beaches
                       and rivers. Sheet pile embedments typically
                       range from  6 to 12 feet.     Pile embedments
                       range from 15 to 30 feet. Embedment lengths
                       should be evaluated by an experienced
                       engineer or contractor for suitability for
                       a particular location and situation.

                       Fine Grained Soils: Good for piles if firm.
                       If soft, long embedment lengths may be
                       required.    Good for stone structures if
                       firm.   Excessive settlement may occur if
                       soft. Sheet pile embedments typically range
                       from 10 to 20 feet.    Pile embedments range
                       from 25 to 40 feet.        Embedment lengths
                       should be evaluated by an experienced


                                             8







                    engineer or contractor for suitability for
                    a particular site.

                    Organic Soils, Peats: Generally not accept-
                    able unless piles bear on an underl@Lying
                    strata.   May result in large settlement of
                    stone structures unless the layer is thin.
                    These soils usually occur in low lying areas
                    such as marshes.















































                                           9







                      Design Methodology

                      1)  For erosion control structures, obtain
                      cross-sections of . the bank to be protected
                      at 50 foot intervals, extending from the
                      upland bank to minus 1 or 2 feet below mean
                      low water.    Reference horizontal measure-
                      ments. to a local baseline, and vertical
                      measurements to mean low water.


                      For offshore access structures, measure
                      water depths at the estimated location of
                      the structure.

                      2) Estimate design water levels (tide plus
                      storm surge) and potential wave heights to
                      determine the design wave height for the
                      site. Check the breaking wave height at the
                      structure.   Use the lesser of the design
                      wave height and the breaking wave height for
                      design.

                      3) For erosion control structures, estimate
                      the wave runup on the structure.      If the
                      structure will be overtopped, consider using
                      vegetation or a stone or shell apron behind
                      the structure to reduce erosion. A certain
                      level of erosion behind the structure may
                      have to be accepted during large storm
                      events.

                      4) Obtain information on soils in the area
                      of construction.   Based on soils choose an
                      appropriate design and size of structure.

                      5) Lay out the structure using the cross-
                      section survey. Check with the Mississippi
                      Department of Wildlife, Fisheries and Parks,
                      Bureau of Marine Resources agency for
                      environmental limitations on construction
                      and for information on the permitting
                      process.



                                            10









                     SHORELINE EROSION CONTROL STRUCTURES

                     There   are   a   variety    of    publications
                     regarding     shoreline     erosion    control
                     available which can provide additional
                     detail on design methods.      Among the most
                     useful are "Low Cost Shore Protection -A
                     Guide For Engineers and Contractors" (U.S.
                     Army Corps of Engineers, 1981) and "Shore
                     Protection Manual" (CERC, 1984). It is
                     advised that these sources be reviewed prior
                     to attempting to design any shoreline
                     erosion control structure.


                     Description of Shorelines

                     Shorelines can consist of a variety of
                     shoreform. types, each with its own erosion
                     problems.    Different shoreforms call for
                     different shore erosion control solutions.


                     Banks are steep shoreforms consisting of
                     soft erodible material such as clay, sand or
                     gravel. Bank erosion is typically due to a
                     combination of seepage of groundwater within
                     the bank, and erosion by wave action at the
                     base.      The   most   appropriate    erosion
                     protection may consist of a combination of
                     a   drainage    system   plus   wave   erosion
                     protection such as a revetment at the toe.

                     Marshes are areas that are saturated with
                     water for much of the time and support
                     vegetation adapted to saturated conditions.
                     Previously often drained or filled to create
                     new upland areas, marshes are now protected
                     by    federal     and    state     regulations.
                     Protection of marshes will often consist of
                     a non-structural solution incorporating the
                     planting of erosion resistant marsh grasses.


                                              11








                      Beaches are the most common shoref orm in the
                      United States.   Beaches are typically very
                      dynamic, with the sediment moving onshore,
                      offshore, and along shore in response to
                      wind and wave conditions.     Cutting of f or
                      interrupting the movement of sediment by
                      jetties   or groins can often have a
                      detrimental effect to beaches adjacent to
                      the construction.



                      Shore Protection Methods

                      Bulkheads are vertical walls which retain
                      fill and protect the shoreline behind the
                      structure from erosion, as shown below.




                          SHORELINE MODIFICATION
                                                    DOCKING STRUCTURE




















                      Figure 5, Typical Uses of Bulkheads
                      (U.S. Army Corps of Engineers, 1981)




                                            12







                    Revetments are sloping erosion control
                    structures, generally made out of stone laid
                    over a prepared base including filter cloth
                    and bedding stone.

                    Breakwaters provide shoreline erosion con-
                    trol by reducing the wave height impacting
                    the shoreline, and by trapping sediment on
                    the landward side.

                    Vegetation consists of planting an eroding
                    area with an appropriate species of erosion
                    resistant grass, perhaps in conjunction a
                    low stone sill and minor filling with an
                    appropriate material such as sand.

                    Other options which are often used in con-
                    junction with one or more of the above ero-
                    sion control techniques include infiltration
                    and drainage controls and slope flattening.
                    These   actions   stabilize  banks    against
                    erosion due to flowing water and may be
                    required even when all erosion due to waves
                    at the base of the bank is prevented by a
                    revetment or some other means.      Figure 6
                    shows an example of a well designed shore
                    protection system incorporating drainage
                    control, slope flattening, vegetation, and
                    a revetment.




















                                         13













                                        Adequate Setback of Structures to Avoid
                                        Overloading Bank and Provide Safety
                                        Factor in Case of Bank Collapse

                                        Construct Drain and Grade Surface to
                                        Control Su face Water
                                                        Weit-Rooted Vegetation to Reduce Surface Erosion

                                                        Regrade to Stable Slope
                                                                    Provide for Drainage of Water
                                                              .1-.  from Overtopping Waves

                                                                                   Af Stable Stone Armor


                                                         77

                                                                           .. . ....             Toe
                                                               Gravel Underlayer@@'@-.          ApProtection
                                                               and Filter Cloth

                                      Note;  Tie Structure Ends into Adjacent Bank to   ar
                                      Minimize Damage f rom Flanking Erosion





                                    Figure 6, Well Designed Shore Protection
                                    (University of Wisconsin Sea Grant, 1987)




                                    Impacts of the Various Erosion Control
                                    Options

                                    No Action consists of allowing nature to
                                    take its natural course, without attempts to
                                    slow erosion.             This option will often have
                                    the       least        objectionable               environmental
                                    consequences and will obviously have the
                                    least cost.


                                    Relocation consists of removing vulnerable
                                    structures from behind an eroding shoreline,


                                                                       14







                     either to another site or far enough from
                     the shoreline to give an acceptable service
                     life before again being threatened by
                     erosion.   This option will also generally
                     have minimal environmental impacts on the
                     marine environment, although relocation can
                     have detrimental impacts on upland areas in
                     some instances.


                     Bulkheads are often the least environ-
                     mentally acceptable alternative because they
                     provide no habitat or protected areas for
                     marine life, increase erosion of the shore-
                     line, and create access problems to the
                     shoreline. Bulkheads may be the best alter-
                     native when some water depth is required at
                     the shoreline for boating activities.

                     Revetments of placed stone cause less scour
                     of the sediment in front of the structure
                     than do bulkheads, and can provide a habitat
                     for marine life.      Revetments can hinder
                     access to the      shore for recreational
                     purposes,   but   they   often   provide    an
                     excellent    permanent   shoreline     erosion
                     protection  solution when complete erosion
                     control is  required.    Revetments can harm
                     downdrift beaches by removing the supply of
                     sand which has been nourishing the beaches.

                     Breakwaters provide an area sheltered from
                     waves, and beaches built up in the sheltered
                     area behind the breakwater can provide
                     enhanced      recreational        potential.
                     Breakwaters can hinder circulation and cause
                     water quality problems, and high structures
                     may also intrude on the view of the water.
                     Rubble breakwaters provide habitat for
                     biota, and they may also provide a sheltered
                     area where submerged aquatic vegetation will
                     thrive.




                                           15







                      Vegetation generally greatly improves the
                      natural habitat, but hinders other uses of
                      the shore because travel through the
                      plantings must be restricted.       Vegetation
                      must be protected from pedestrian use.


                      Specific Design Recommendations

                      Bulkheads

                      * Bulkheads should not, in general, be used
                      for shoreline erosion control in situations
                      where other alternatives will work. This is
                      because bulkheads do not provide habitat for
                      marine life, and will often cause scouring
                      of the shoreline, further damaging the
                      environment.

                      * Bulkheads may provide the best solution
                      when a maximum of upland area is required or
                      deep water is required at the bank.

                         When bulkheads are required their impacts
                      can be reduced by providing a substantial
                      stone toe.    This will protect against toe
                      scour and provide habitat.

                      * A typical wooden sheet pile bulkheads is
                      shown in Figure 7. They will typically be
                      constructed with 12 to 16 foot long sheets
                      with 8 to 12 feet embedded into natural
                      ground, depending on the soil type and
                      density.   Each design should be checked for
                      stability  based on site conditions.

                          Other typical vertical face bulkheads
                      f ound in  coastal Mississippi are made of
                      concrete   and corrugated aluminum metal
                      alloys.    Heavy duty plastic bulkheads are
                      beginning  to come into use.



                                            16








                                  * Bulkheads must be built at or above the
                                  mean high tide mark.

                                  * In areas where there is substantial tidal
                                  marsh, vertical face bulkheads should not be
                                  constructed.               In these cases, revetment
                                  solutions should be explored.

                                        Marine grade treated lumber should be
                                  used for wooden bulkheads. Use of creosote
                                  treated timber           bulkheads is discouraged.







                                                                                    TREATED           CAP
                                                               GROUND               CAPBOARD


                                                          j           TIMBER LINER
                                                                      BOLTED TO WALER
                                                            1011

                                                                    GALVANIZED TIE ROD


                                     TIE BACK PILE
                                     AT EACH WALL PILE
                                                                        TIMBER WALES
                                                                        BOLTED TO PILES


                                                                        TONGUE AND GROOVE,"@'.
                                                                        SHEETING               4

                                                                                                TIMBER
                                                                                                PILE




                                  Figure 7, Wooden Sheet Pile Bulkhead (State
                                  of Maryland, 1982)





                                                                       17








                      Revetments

                          Revetments are generally suitable f or
                      protecting high or low banks f rom erosion
                      when a recreational beach in f ront of the
                      bank is not required. In some cases beaches
                      may f orm or remain in f ront of revetments,
                      but the revetment structure will often cover
                      narrow beaches, and scour from increased
                      wave reflection may. reduce the. amount of
                      sand deposited in front of the structure.

                           Revetments must have toe protection
                      designed into the structure when it is
                      constructed on easily eroded material such
                      as sand. Revetments also must be designed
                      so   that erosion     cannot   outflank    the
                      structure and cause erosion around the ends
                      of the structure.     This can be done by
                      either attaching the ends to existing
                      structures or extending return walls back
                      into the bank.

                      * Revetments are most commonly constructed
                      from stone.       If local stone is not
                      available, other designs such as concrete
                      armor units, wire gabions, etc. may be more
                      economical. In many cases manufacturers or
                      vendors   will provide     design    services.
                      Concrete rubble revetments should be f ree of
                      exposed steel, paint or petroleum based
                      products.   Asphalt should not be used as
                      revetment material.    Since revetments are
                      highly visible, only unifore materials
                      should be used.

                           Figure 8 shows some of the design
                      features of a typical armor stone revetment.






                                           18
















                       OVERTOPPING
                          APRON


                                               ARMOR LAYER

                                                               MHW


                                                          -MLW
                                                         TOE
                                                       PROTECTION
                         GRADED STONE
                             FILTER









                      Figure 8, Armor Stone Revetment
                      (U.S. Army Corps of Engineers, 1981)




                      Breakwaters


                           Offshore breakwaters are sometimes
                      suitable when a public recreational beach is
                      desired and offshore water depths are
                      shallow.     One   advantage   of    offshore
                      breakwaters is that they allow a portion of
                      the wave    energy to reach the beach,
                      maintaining some transport of sand along the
                      shoreline.   This helps prevent erosion of
                      beaches due to blocking sand movement.

                         Breakwaters which are long compared to
                      the   distance   offshore   Will    tend    to
                      accumulate sediments behind them, extending
                      the beach offshore.    In the extreme case,
                      the beach will eventually extend all the way


                                            19







                               to the breakwater.             This may interrupt the
                               movement of sediment to downdrift beaches
                               and may also reduce water circulation,
                               causing water quality problems.

                                     Due to the complexity of positioning
                               offshore breakwaters, it is recommended that
                               professional assistance be obtained for
                               design.

                                     Figure 9 shows an example of a small
                               armor stone breakwater cross section used in
                               conjunction with vegetation planting. Stone
                               sizes should be based on local site
                               conditions, using Table 1.









                                                                 CREST I
                                 FLL AND MARSH GRASS                             ARMOR STONE

                                                                                           MH

                                                         .. ......                         ML
                                       CORE STONE              ....... .............................. .......
                                               FILTER CLOTH
                                                MIN. 3 STONES AT TOE OF SILL

                                      EXISTING GROUND






                               Figure 9, Armor Stone Breakwater Section,
                               with Marsh Creation




                                                              20











                                                       ESTIMATED WEIGHT                            CORRECTION                  CORRECTION FOR

                                                       OF ARMOR STONE                              FOR SLOPE                          UNIT WEIGHT


                                                       WAVE          ESTIMATED SLOPE                                            UNIT
                                                       HEIGHT           WEIGHT                                                WEIGHT
                                                         H                   W                                                   wr
                                                       (f                   Ob)           (f t/f 0                   K I       (lb/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        1:3      m on meow-0. 7              135                  2.4
                                                       2.0                        50        1: 3@                    0.6         14o                  2.0
                                                       2.5                   100            1: 4                     0.5         145                  1.7
                                                       3. 0           040bomm- 16           1: 44                    0.4         150
                                                       3.5                   260            1: 5                     0.4         155onnolillow-1-3
                                                       4.0                   390            1: 5%                    0.4         160                  1.1
                                                       4.5                   550            1-. 6                    0.3         165                  1.0
                                                       5.0                   760                                                 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 foot of rock weighs 165 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



                                                       TYPICAL UNIT WEIGHTS PER CUBIC FOOT:
                                                                                  CONCRETE         144
                                                                                  GRANITE          165
                                                                                  LIMESTONE        156
                                                                                  0
                                                                                  0
                                                                                  0
                                                                                  00@@











                                                       Table 1, Calculation of Armor Stone Weights
                                                       (U.S. Army Corps of Engineers, 1981)


                                                                                                      21







                      Vegetation

                         The success of vegetation as shoreline
                      erosion control depends on such factors as
                      climate, soil properties, wave exposure, and
                      salinity regimes.

                          Typically, Gulf Coast marshes include
                      saltgrass and gulf cordgrass, as well as
                      smooth cordgrass, saltmeadow cordgrass, and
                      black needle rush. See Table 2.

                      * The range of vegetation erosion control
                      can  be extended through the use of
                      structures such as low breakwater sills, as
                      shown in Figure 9, which remain permanently
                      in place, or temporary wooden or brush
                      fences.   These structures reduce the wave
                      height while the plants become established.

                          Vegetation should be protected from
                      pedestrian u'se by fences and signs. Access
                      paths through the vegetated areas should be
                      provided   to   public   beaches   or    other
                      recreational areas.
























                                            22













                                         PLANTING SPECIFICATIONS FOR GULF COASTS MARSH PLANTS


                                         Type           Planting Time           Plant Form        Spacing       Location

                                         Smooth               March-May         Sprigs            31 apart      MLW to
                                         Cordgrass                              15 Week           1.51          NNW
                                                                                6 Month           1.51
                                                                                or Plugs


                                         SaLtmeadow           March-May         Sprigs            31 apart      NNW to
                                         Cordgrass                              15 Week                         high tide


                                         Gulf                 March-May         Sprigs            1.51-31       NNW &
                                         Cordgrass                              15 Week           1.51          above
                                                                                6 Month           1.51



                                         Salt Grass           Spring            Seedlings         1.51-31       NNW &
                                                                                                                above



                                         Black                Spring            Seedlings         1-5% of       Above NNW
                                         Needle Rush                                              cordgrass
                                                                                                  plantings


                                         Common Reed          Spring            Sprigs            1.51-31       Above NNW



                                        Table 2, Planting Guide for Marsh Plants
                                        (U.S. Army Corps of Engineers, 1981)















                                                                                 23









                     SHOREFRONT ACCESS FACILITIES



                     Description of Access Facilities

                     This section describes shorefront structures
                     designed to provide access to coastal
                     waters.    Typical structures most commonly
                     built in coastal Mississippi include mooring
                     and fishing piers, boat ramps, dredged boat
                     slips, boat houses and berthing facilities.

                     Piers for mooring purposes are usually built
                     parallel to the shoreline. In cases where
                     water   depth   is a factor,      piers    are
                     constructed perpendicular to the shore with
                     boats being moored along side.        Commonly
                     when there is adequate navigation clearance
                     a 'IT" or "Ll' section is attached to a
                     perpendicular pier for mooring.        Mooring
                     piers are also used for fishing access and
                     many pier are used exclusively for fishing
                     or passive recreation.

                     Boat ramps for both residential and public
                     use are very popular in coastal Mississippi.
                     Most public boat ramps are constructed for
                     high volume use, while residential boat
                     ramps are not built to the same degree of
                     improvement.

                     Many property owners choose to moor their
                     boats by creating a boatslip from the upland
                     portions of their property.     In the past,
                     boatslips were dredged deep into the upland
                     property creating a square or rectangular
                     boatslip with upland on three sides.      This
                     type boatslip exhibits poor water quality
                     conditions because of the lack of water
                     movement in and out of   the boatslip.    This
                     type of boat slip is no   longer permitted in
                     coastal Mississippi. A   new type of boatslip


                                           24







                      is now being constructed along the coast,
                      with the slip parallel to the shoreline and
                      sides angled to allow better water flow
                      through the boatslip.

                      Often there is a need to protect moored
                      boats from the weather.        In these cases
                      boathouses are constructed over the mooring
                      area. In addition to a weather proof roof,
                      many boats are hoisted out of the water for
                      additional protection.

                      on occasion, individuals and local agencies
                      desire to provide facilities for the
                      berthing of many boats.       Marinas usually
                      require extensive planning and professional
                      assistance.     However, some guidance for
                      berthing facilities is included in this
                      publication as this guidance can be used for
                      other applications.


                      Specific Design Recommendations

                      Small Craft Launching Facilities

                      This section describes the design of boat
                      launching ramps generally used for public
                      use.    Private boat launching ramps will
                      typically be less elaborate.

                      * Public launching ramp lanes should be 15
                      feet wide on ramps of two or more lanes. If
                      the launching ramp consists of a single lane
                      it is recommended that the lane be 20 feet
                      wide, and never less than 16 feet wide. one
                      launching lane will handle approximately 50
                      launchings and 50 retrievals per day.

                          Launching ramps should have a minimum
                      slope of 1 (vertical) on 9 (horizontal) and
                      a maximum slope of 1 on 6. The slope should



                                             25







                     be kept constant if possible.

                     * A vertical curve should be incorporated
                     into the head of the ramp to provide a
                     smooth transition between the launching ramp
                     and the parking area, as shown in Figure 10.
                     The vertical curve keeps trailer hitches
                     from striking the launching ramp at a change
                     in grade, and enhances driver's vision while
                     backing. A 15 to 20 foot vertical curve is
                     recommended.





                                      HEM OF RAW

                                               r w
                                                    DOM HM WATER


                                       ........ .. .................
                                                   ,F DESM LOW WATER
                                N TO 2a           ... ......
                                VERMAL CURVE
                                            TOE OF RAMP\

                     H
                     Figure 10, Small Boat Launching Ramp
                     (State of California, 1991)


                     * Private individual boat launching ramps
                     will typically be narrower (approximately 15
                     feet or less) and will not extend as deeply
                     into the water (generally no deeper than -3
                     feet MLW) as described here.


                     Construction Details:
                                               r M",.'
                             7W@@ V @@E




                          Concrete should have a minimum of 3
                     inches of cover over rebar. Concrete should




                                           26








                     be a total of 6 inches thick in fresh water
                     and 8 inches thick in salt water. Minimum
                     steel reinforcement should be #4 bars at 12
                     inches both ways, or as required by the
                     design engineer.

                          Precast concrete planks should be
                     designed to bolt, cable, or key together
                     during installation.      Planks should be
                     placed over geotextile fabric to prevent the
                     foundation soil from   being washed through
                     the gaps.

                         In areas subject to undermining from
                     currents  or waves,    the ramps must be
                     protected by a 3 to    5 f oot perimeter of
                     riprap or other means  of protection.

                         It is recommended that boat ramps be
                     finished  with V-grooves aligned at 60
                     degrees to the longitudinal axis of the
                     ramp. The grooves should be 111 by 111. This
                     is especially important in salt water where
                     slick marine growth will frequently be
                     present.  spinning tires will quickly wear
                     away the growth on the peaks of the grooves
                     to provide traction.

                     * Private individual boat ramps not using
                     concrete should use 6 to 8 inches of clean
                     compact shell, limestone or gravel.



                     Shoreside Facilities:

                     * Where possible, parking areas should be
                     located   immediately    adjacent   to     the
                     launching ramp with all spaces within 600
                     feet of the ramp.

                         Garbage receptacles for marine trash



                                           27







                      should be provided as close to the launching
                      ramp as practical.

                      * A minimum of 20 to 30 car/trailer parking
                      spaces   per   launching   lane   should    be
                      provided.   Pull-through trailer spaces are
                      recommended to the maximum extent possible.

                      * Car/trailer spaces should be 101 wide by
                      401 long. Additional car-only spaces should
                      be provided for picnic, day-use and other
                      activities in the vicinity of the launching
                      area.


                          One handicap parking space should be
                      provided for every 50 car/trailer spaces and
                      every 40 single car spaces, with a minimum
                      of one handicap parking space.        Handicap
                      spaces should be located near the launching
                      ramp and restroom, and should conform to all
                      State and local regulations.

                           No overhead power lines should be
                      permitted over parking areas, launching ramp
                      areas, or any other areas where a vehicle
                      can drive while towing a boat trailer within
                      the project area, due to the possibility of
                      trailerable sailboats with metal masts using
                      the facilities.



                      Environmental Concerns:

                        Launching Ramps will not be permitted for
                      construction in,marsh areas.

                      * Care in the placement of launching ramps
                      should be taken to avoid interrupting the
                      natural movement of beach sand.     This may
                      lead to the buildup of sand on the updrift
                      side of the ramp and erosion of the beach on
                      the downdrift side of the ramp.


                                           28







                    * Boat Launching Ramps should be located in
                    areas   where   there   are   no   underwater
                    obstructions to interfere with launching or
                    navigation near the facility.

                       Stormwater runoff from launch approaches
                    and parking areas should be filtered through
                    sand or vegetated areas and should not be
                    directed down the boat ramp.


                    Piers

                        All public piers shall be handicapped
                    accessible with safety rails and wheelchair
                    guards, and shall be at least 61 wide.

                    * Piers used for mooring or docking shall
                    provide a combination of safety rails and
                    wheel chair guards to accommodate handi-
                    capped individuals.

                       Public piers should be lighted.

                         Piers shall not obstruct or create
                    hazards to navigation.

                        Piers, including the width of the boat
                    moored at the end, should not extend more
                    than 1/4 of the way across the water body in
                    which they are located. See Figure 11 for
                    typical pier layouts.

                        Piling design should be based on local
                    conditionst   including water     depth    and
                    geotechnical conditions.     Local knowledge
                    will often be the best guide for small
                    private facilities. Larger facilities will
                    require the services of an engineer and a
                    soils exploration program to determine
                    required pile sizes and embedment depths.
                    See Figure 12 for typical pier sections.


                                          29





























                                PERPENDICULAR      7- PER
                                TO SHORE


                                              MAXMUM OF V4 WAY
                                              ACROSS WATERWAY (TYPJ













                                PARALLEL TO SHORE   V PIER




                     Figure 11, Typical Pier Alignments


                     * Good foundation conditions and moderate
                     water depths will typically require piles
                     with embedment lengths of 15 to 30 feet with
                     butt diameters ranging from 10 to 12 inches
                     maximum to 6 to 8 inches minimum.         Soft
                     foundation soils will require embedment
                     lengths ranging from 25 to 40 feet.




                                           30









                    Construction Details:

                       All piers should have railing capable of
                    withstanding a horizontal force of twenty
                    pounds per linear foot, applied at the top
                    of the railing. Top rails should be 4211 in
                    height and be sloped on a 30 to 40 degree
                    angle to reduce sitting on the top rail.

                    * Typical wooden deck planks should be 6 or
                    8 inches wide and be placed with the heart
                    side down. Spacing should not be more the
                    1/411 between deck planks to facilitate
                    wheelchair use.

                    * Typical residential piers have pier bents
                    that range from 61 to 101 apart, with 8 to
                    12 inch wide cross beams, 6 to 10 inch cross
                    bracing, and 8 to 12 inch wide deck joists.

                        Public piers with handicapped access
                    should have handrails with the top rail 32
                    inches above the deck on all sloped pier
                    sections.



                    Environmental Considerations:

                        For piers four feet wide or greater,
                    elevations of the pier deck should be a
                    minimum of 1 foot above vegetated bottoms
                    for every 1 foot of pier width, and provide
                    I inch spacing between decking boards to
                    prevent the shading of vegetation.     Public
                    piers accessible to the handicapped should
                    provide turn around areas with 1/4 inch
                    spacing at ends of piers or every 100 feet.
                    Minimum turnaround areas shall be 5 feet by
                    5 feet in dimension.

                         Pilings -supporting piers should be
                    concrete or chemically treated in accordance



                                         31














                                                    LIU4T FD(TLFE



                                                     UGHT POST


                               WHEELCHM GUAF0           RAIL CAP
                               AND MOORNG RAL
                                                      SAFETY RAL

                                                  DECKNO
                              BLOCKMNG                 DECK JC*T$


                              B"ER


                                                   CRO% BRACI,*       CROSS W-M





                                                                            NLW


                                    PLE                                    BOTTOM



                                                                              --JI
                             igure 12,    Typical Public Pier Cross-
                           Section   MIM, RAL     DEICK@
                                                        32









                    with American Wood Preserver's Association
                    recommendations f or the environment in which
                    the piling will be placed. Generally, wood
                    should be treated with 2.5 CCA for saltwater
                    and .6 CCA for freshwater.


                        The use of creosote treated lumber is
                    discouraged.


                    Berthing Facilitiles

                    Channels and Fairways:

                    * Entrance Channels should have a minimum
                    width of 75 feet at the design depth or
                    bottom' and a minimum depth of 3 feet below
                    the anticipated deepest draft vessel or 5
                    feet, which ever is greater.

                    * Interior Channels should have a minimum
                    width of 75 feet at the design depth, and a
                    minimum   depth   of   2   feet   below    the
                    anticipated deepest draft vessel, or 4 feet,
                    which ever is greater.

                       Fairways should have a minimum width of
                    1.75 times the length of the longest berth
                    where berths are perpendicular to the
                    fairway, or a minimum width of 1.5 times the
                    length of the longest boat where boats are
                    berthed parallel to the fairway.

                    * Fairways should have a minimum depth of
                    6 feet for boats up to 45 feet in length, 8
                    feet for boats up to 55 feet in length, and
                    10 feet for sailboats up to 65 feet in
                    length.







                                          33









                     Berths:


                     * Berths should have the same water depth
                     as fairways.

                        It is recommended that berth widths be
                     provided based on expected boat lengths:

                        Boat Length         Berth Width
                             201                 10,
                             241                 121
                             281                 131
                             321                 141
                             361                 151
                             4.01                161
                             501                 171


                         Main walkways should be 6 feet wide.
                     Finger piers should be a minimum of 2.5 feet
                     wide up to 20 feet long, 3.0 feet long up to
                     35 feet long, 4.0 feet wide up to 60 feet
                     long and 5.0 feet over 60 feet long.

                     Land Areas:

                         A minimum of 0.6 parking spaces per
                     recreational boat berth should be provided.
                     This is in addition to parking needs for
                     other areas such as restaurants, public
                     fishing piers, launching ramps, etc.

                     * Parking areas should be located such that
                     no parking space is more than 1,000 feet
                     from any berth.

                     * Approximately 2% of all parking spaces,
                     but not less than one space, shall be
                     reserved for handicap parking.

                     * Runoff should be controlled through the
                     use of grassed swales, detention ponds, or
                     other filtration methods to protect the



                                          34








                    quality of the receiving water.

                    Services:


                         All shoreside utilities should be
                    underground, and should conform to accepted
                    practice and all applicable codes.

                    * All utility lines shall be installed so
                    they are not exposed on the deck of the
                    structure.    For, floating piers, utility
                    lines should have not less than 6 inches of
                    clearance above the waterline under dead
                    load conditions, nor less than 2 inches
                    clearance under dead load plus live load
                    conditions.

                    * All water lines shall be equipped at the
                    shore end with appropriate anti-siphon
                    devices.

                        Fire protection shall be provided in
                    sufficient locations to afford protection to
                    all structures and boats in the marina at a
                    rate of not less than 40 gpm at 40 psi.
                    marina designers should check with local
                    fire officials for other requirements for
                    fire fighting at specific sites.

                    * It is recommended that circuit breakers
                    equipped with ground fault interrupters be
                    provided at all berth power outlets. GFI's
                    should be tested and maintained at regular
                    intervals to insure that the devices remain
                    in working order, especially in a salt water
                    environment.

                         A minimum of one shoreside pumpout
                    installation must be provided at every
                    marina. This facility should be approved by
                    the local authority having jurisdiction over
                    sewage disposal.



                                          35







                      Dredged Boat Slips

                      * Residential boatslips cut into the shore
                      shall have each side cut at 45 degrees or
                      less to the shoreline, as shown in Figure
                      13. The slip width should be based on the
                      berth widths indicated in the previous
                      section.  Boats should generally be moored
                      in the boatslip parallel to the shore.

                         The back side of the boatslip shall be
                      equal to or slightly longer than the boat
                      proposed to be moored.

                          Boatslips shall not be dredged in or
                      through marsh areas.







                                       BAYOU

                            4-@
                                                MOOFM Pu a-usTm





                                  45'







                      Figure 13, Indented Boatslip





                                           36










                   Boat Houses


                       Boat houses should be designed to be
                   visually unobtrusive.   Completely enclosed
                   structures are discouraged.

                      Boat houses constructed seaward of the
                   shoreline should be as near the shoreline as
                   water depths allow.

                      Boat houses with motorized boat hoists
                   should have sufficient structural capacity
                   to accommodate the boat to be lifted.


                   * Electrical service to boat houses should
                   incorporate ground fault interrupters.





                                              ROOF




                                      L
                              PLE,,,             OPr=N SDr=S


                                                   MW
                                                   HLW


                                                   BOTTOM







                   Figure 14, Boat House Section
                                   L




                                        37










                      CONCLUSION


                      There are a wide range of options available
                      for  controlling    shoreline  erosion    and
                      providing access to the shoreline without
                      degrading the natural environment.       This
                      pamphlet presents suggestions, and in some
                      cases   requirements   of   the   State    of
                      Mississippi, which will help provide cost
                      effective measures which have been proven to
                      have the least impact on our shorelines.

                      Individuals    planning   on     constructing
                      shoreline erosion control or shorefront
                      access facilities are urged to contact the
                      State of Mississippi Department of Wildlife,
                      Fisheries and Parks for guidance before
                      beginning construction.       Engineers and
                      contractors with local experience can also
                      be of help in planning a project, obtaining
                      required permits, and insuring that the
                      project is properly built.

                      By taking proper care in planning and
                      constructing shoreline structures, we can
                      enjoy our natural resources while preserving
                      the environment for future generations.

















                                            38









                     REFERENCES


                     American Wood Preservers Institute, 11AWPI
                     Technical Guidelines for Pressure-Treated
                     Wood", 1970.

                     CERC (Coastal Engineering Research Center),
                     "Shore Protection Manual",, Volumes 1 and 2,
                     U.S. Army Corps of Engineers, 1984.

                     Quinn, Alonzo, Design and Construction of
                     Ports and Marine Structures, McGraw-Hill,
                     N.Y., 1972.

                     State of California, Department of Boating
                     and   Waterways,     "Layout,    Design     and
                     Construction Handbook for Small Craft Boat
                     Launching Facilities", March 1991.

                     State of California, Department of Boating
                     and Waterways, "Layout and Design Guidelines
                     for  Small    Craft   Berthing    Facilities",
                     January 1984.

                     State of Maryland, Department of Natural
                     Resources, "An Assessment of Shore Erosion
                     in Northern Chesapeake Bay", 1982.

                     State of Mississippi Department of Wildlife,
                     Fisheries and Parks, "Mississippi Coastal
                     Programs," 1988, Fourth Printing.

                     State of Washington, Department of Ecology,
                     "Shoreline Management Guidebook", 1990.

                     U.S. Army Corps of Engineers, "Low Cost
                     Shore Protection - A Guide for Engineers and
                     Contractors", 1981.

                     University of Wisconsin Sea Grant Institute,
                     "Coastal Processes Workbook, 1987.




                                            39







                                                                                                      NOAA COASTAL SERVICES CTR LIBRARY



                                                                                                      3 6668 14111885 3