Use of natural resource data in land and water planning

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

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The Connecticut Geology-Soil Task Force
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Report on
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USE OF NATURAL RESOURCE DATA

IN LAND AND WATER PLANNING

'@/%avid E. Hill and Hugo F. Thomas

LAND
AND
WATER
GEOLOG PLANNING

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SOIL
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HYDROLOGY

LAND USE

S43
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no.733
MY
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41 Bulletin of The Connecticut Agricultural Experiment Station
-733

U - S - DEPARTMENT OF COMMERCE NOAA
P-roPcrtY IF COASTAL SERVICES CENTER
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2234 SOUTH HOBSON AVENtiE
CHARLESTON , SC 29@,05-24 13

ACKNOWLEDGMENTS

The sheer increase in knowledge, together with its growing special-
ization, often bewilders the potential beneficiary of science and renders
the research that produced the knowledge less useful. Hence, the cry
heard more and more for "interdisciplinary" research*. In other words,
the consumer of knowledge or science wants to see the fragments put
together and made more useful. This bulletin reports interdisciplinary
resea,rch that was made possible by the generous contributions of people
from many specialties or disciplines and from many organizations.

The group that accomplished the reseaxch is known as The Connecticut
Geology-Soil Task Force. The Task Force was created in 1969 following a
conference sponsored by the U.S. Soil Conservation Service and the
Connecticut Geological and Natural History Survey. The Task Force is
informal, unofficial, and its membership is voluntary. Its activities
have been supported by the agencies that employ its members. Its goal
is encouraging greater collaboration and understanding among the
specialists who collect, interpret and use information on natural
resources. The Task Force has undertaken several projects.

The resource interpretation system reported in this bulletin is the
outcome of one project of the Task Force. The members of the steering
committee of the Task Force who initiated this project and assisted with
writing and reviews were:

John M. Allen U.S. Soil Conservation Service

Harold I. Ames Office of State Planning,
Department of Finance and Control

John A. Baker U.S. Geological Survey,
Water Resources Division

Harold M. Bannerman Consultant, Connecticut Geological
(Chairman) and Natural History Survey

William M. Brown U.S. Soil Conservation Service

David E. Hill The Connecticut Agricultural
Experiment Station

Harry L. Siebert Connecticut Department of Transportation
Bureau of Highways

Hugo F. Thomas University of Connecticut

other members of the Task Force who assisted by compiling data or
contributing narrative to the report were:

Roger B. Colton U.S. Geological Survey,
Geologic Division

Lincoln R. Page U.S. Geological Survey,
Geologic Division

Maurice H. Pease, Jr. U.S. Geological Survey,
Geologic Division

Joe Webb Peoples Connecticut Geological and
Natural History Survey

Fred Pessl, Jr. U.S. Geological Survey,
Geologic Division

Robert B. Ryder U.S. Geological Survey,
Water Resources Division

Richard N. Symonds, Jr. Office of State Planning,
Department of Finance and Control

Thanks are also due to other members of the Task Force -who contributed
and advised throughout the project. Special thanks are extended to
Clifford Keune, U.S. Geological Survey, for drafting illustrations.

The data used here have been taken largely from reports and maps
published by several agencies:

U.S. Geological Survey

U.S. Soil Conservation Service

Connecticut Department of Environmental Protection,
Geological and Natural History Survey

The Connecticut Agricultural Experiment Station

Connecticut Department of Transportation, Bureau of Highways

Office of State Planning, Department of Finance and Control

Our final thanks go to the workers in these departments who through
years of painstaking mapping and research built the foundation for this
system of resource interpretation.

David E. Hill

Hugo F. Thomas

CONTENTS

INTRODUCTION 5
BASIC RESOURCE DATA 5
Topographic Map 5
Bedrock-geology Map 6
Surficial-geology Map 6
Soil-survey Map 7
Water-resources Inventory 8
Land Use and Zoning Inventory 8
COMPILATION OF AVAILABLE DATA 9
Availability of Data 9
Need for Common Base, Scale and Boundaries 10
Establishment of Management Guidelines 12
Analysis of Data 14
Use of Transparent Maps 16
A RESOURCE INTERPRETATION SYSTEM 16
Single-factor Maps 16
1. Topography 17
2. General slope map 17
3. Slope greater than 151o 18
4. Slope less than 3% and soil seldom saturated 18
5. Bedrock type 19
6. Structural characteristics of bedrock 20
7. Outcrops 21
8. Depth to bedrock: 0-2 feet 21
9. Depth to bedrock: 0-10 feet 22
10. Depth to bedrock: 50-foot intervals 22
11. Unconsolidated-materials map 22
12. Sand and gravel deposits 23
13. Unified soil classification of substratum 24
14. Soil saturated with water within 3 feet of surface for 25
2-12 months
15. Soil saturated with water within 3 feet of surface for 26
less than 2 months
16. Peat and muck 26
17. Percolation rate classes 27
18. Agricultural land use capability 27
19. Drainage areas 28
20. Flood-prone axeas 28
21. Low flow of streams 28
22. Saturated thickness of stratified unconsolidated deposits 30
23. Availability of ground water 30
24. Location of existing sanitary and water related facilities 30
25. Land use: 1970 32
26. Zoning: 1970 32
A Pilot Study 32
Collating the Single-factor Maps 32
SUMMARY 44
REFERENCES 45
APPENDDC A 47

USE OF NATURAL RESOURCE DATA IN LAND AND WATER PLANNING

David E. Hill and Hugo F. Thomas

As Connecticut's population increases and the use of land shifts
from agriculture and woodland to commerce, industry and housing, great
interest has developed in land and water planning. Meanwhile, the
wealth of geologic, hydrologic and soil information has also been
growing, but those who want to use the information for land and water
planning have sometimes been thwarted because the data were not in a
form compatible with their needs. For some, the data were too general;
for others too detailed. Most information was collected for other
purposes, and earlier interpretations could not have anticipated
current problems of land and water use planning in a society newly
conscious of its environment.

Because of the interest in planning and the abundant storehouse of
natural resource information, the time seems ripe to tap the storehouse
for planning uses. Thus, the Connecticut Geology-Soil Task Force
studied ways to develop a flexible interpretation system for both
planners who seek general knowledge and planners who seek detail. For
those empowered to regulate land and water useP the new interpretation
system hopefully will help resolve conflicts between limitations
imposed by the natural environment and the requirements of our expanding
population.

In this study, we shall describe the development of the interpreta-
tion system and then demonstrate its use in selecting a fictitious
site to dump solid wastes. The area we chose for this study is a
portion of the Ellington quadrangle in north central Connecticut.

BASIC RESOURCE DATA

Basic to a resource interpretation system are the primary products
of the Federal and State agencies which collect and disseminate
information on topography, geology, hydrology, soils and land use.

Topographic Map. A topographic map, compiled by the U.S.
Geological Survey, is a graphic representation of a small portion of
the earth's surface. The configuration of the surface is c only
shown with contour lines that contain points of equal elevation.

-5-

6 Connecticut Experiment Station Bulletin 733

Topographic maps are produced at different scales and contour intervals
for different purposes. The earliest maps in Connecticut were 15-
minute quadrangles on the scale of 1:62,500 (1 inch equals about 1 mile)
with 20-foot contour intervals. Later maps were 7-fl-minute quadrangles
on the scale of 1:31,680 (1 inch equals I mile). These quadrangles
2
were more recently enlarged to a 1:24,000 scale (1 inch equals 2,000
feet). The 7-fl-minute quadrangle series has 10-foot contour intervals.
Revised editions are issued from time to time, but only the man-made
changes axe recorded (i.e., new houses, roads and modification of
topography along major roads). In 1967, a topographic map of Connecti-
cut was published by the U.S. Geological Survey in cooperation with the
State on the scale of 1:125,000 (1 inch equals about 2 miles). The
contour interval is 50 feet. Another edition of this State map shows
topography by shading.

The 7-fl-minute topographic map shows such natural features as
mountains, valleys, terraces (represented by contour lines) and water
and such cultural features as houses and roads.

Bedrock-geology Map. This map, compiled by the U.S. Geological
Survey, Geologic Division., in cooperation with the Connecticut
Geological and Natural History Survey, represents an interpretation
of the near-surface distribution of bedrock determined largely from
observations of outcrops.

The base map of the bedrock-geology map in the study area is the
7-21-minute topographic quadrangle at a scale of 1:31,680. In other
quadrangles the scale may be 1:24,000. Geologic units on the map
delineate rock types that can be grouped together as recognizable units
at this scale. Cross sections that interpret the geology in third
dimension usually accompany the geologic map. The interrelationship
of geologic units also is indicated, the geologic history postulated
and deposits of potential economic interest described in the text.

Most geologic map units are not suitable for direct use in
engineering or land planning, but data in the text can often be
interpreted for many uses. Rock properties may vary as significantly
within units as between units. Rock types with significantly different
properties are often too small to show at the scale of the map. A
bedrock lithology map based on the physical properties of bedrock is
used to describe the bedrock geology units in terms of physical
properties that are more useful for engineering and land management.
This kind of map is described later in the section on single-factor
maps.

Surficial-geology Map. The surficial-geology map, compiled by
the U.S. Geological Survey, Geologic Division, in cooperation with the
Connecticut Geological and Natural History Survey, show's the distribu-
tion of the different kinds of unconsolidated materials that cover the
bedrock as a discontinuous mantle of variable thickness. The base map

Resource Data in Land and Water Planning

1
for the surficial map in Connecticut is the 7-@-minute topographic
quadrangle at a scale of 1:24,ooo.

Materia,ls are shown as they occur beneath the soil layer (i.e.,
as if the soil layer, commonly a foot or two thick, had been stripped
from the land's surface). The unit shown is the uppermost material.
Other materials, different in composition, may underlie the mapped
unit or may occur -within it as thin lenses.

Outcrops of bedrock and areas where the surficial material is
thought to be less than 10 feet thick are usually shown on the map.
Areas that have been filled for such man-made features as highways,
flood-control structures or solid-waste storage are also shown and
designated axtificial fill. Other features of local interest, such
as striations gouged along bedrock surfaces, glacially transported
boulders, landforms, quarries and pits, may be indicated by separate
symbols.

The texture of the materials is shown by special overprint patterns
on recent maps. Cross sections and graphic logs of test holes are
included on some maps. The text accompanying most maps discusses the
characteristics of the deposits. It also interprets the conditions
under which the deposits were formed and briefly discusses the geologic
history of the map area.

Soil-survey Map. The basic soil information used in the study is
derived from a soil survey map compiled by the U.S. Soil Conservation
Service in cooperation with the Agricultural Experiment Stations of
Connecticut. The base map for Connecticut is an aerial photograph
with a scale of 1:15,840 (4 inches equals 1 mile). Areas on the land-
scape having different physical and chemical properties are delineated.
The properties a soil scientist uses to delineate each area (called a
mapping unit) are properties of the soil itself, such as color, texture,
structure, arrangement and depth of layers (called horizons), tempera-
ture, permeability, drainage, pH and organic matter content. Also
considered are characteristics of the landscape on which the soil rests,
such as slope, surface stoniness, amount of exposed bedrock, erosion,
and whether the area may become flooded.

Although the areas on a soils map of quadrangle size number in the
thousands, those areas with identical properties axe given the same
name. Thus, the mapping units identified and described number about
8o to 120.

Mapping at a scale of 4 inches per mile, however, limits the
number of areas that can be shown on a map; thus, areas less than one
acre with different properties cannot be shown and must be included in
larger units. The small areas of dissimilar soils are called inclusions
and at least 151o are permitted at this scale. At least 85% of each
area delineated on a soils map has its own set of properties. The soil

8 Connecticut Experiment Station Bulletin 733

scientist can interpret these properties relative to such uses as
agriculture, urban development, forestry and recreation.

Water-resources Inventory. The water-resources inventory of
Connecticut, a series of reports by the U.S. Geological Survey, Water
Resources Division, identifies and discusses the quantity and quality
of water available in vaxious regions. To simplify the calculation
and description of water quantity information, the State has been
divided into 10 study areas.

Water supplies may be obtained from surface sources such as streams
and lakes or from ground water. The inventory identifies lakes, ponds
and streams that have water in usable storage and indicates the amounts
in storage. More detailed information in tables and graphs shows flow
duration, low-flow frequency and duration, flood peaks, frequency of
floods and storage required to maintain various flows. Water quality
of surface supplies is also summarized.

The availability of ground water in the basins is summarized by
showing the areal distribution of the principal aquifers. Also shown
are the thickness and the water-transmitting characteristics of the
aquifers in sand and gravel deposits. These parameters can be used
to estimate yields and drawdowns in wells pumped at a constant rate.
Aquifers in stratified deposits that are especially favorable for
development are identified and quantities available are estimated.
The quality of ground water is also discussed. The basic data in the
inventory include well records, pumping-test data, ground-water level
measurements, stream-flow records and chemical analyses of water
samples.

Land Use and Zoning Inventory. A Connecticut land-use inventory
was compiled by the Office of State Planning in 1970-1971 in cooperation
with the Connecticut Regional Planning Agencies. Using aerial-
photograph interpretation and field checking, 57 different land-use
activities were recorded and transferred to 1:24,000 topographic
quadrangle maps. The maps show areas in the State used for residential,
manufacturing, transportation, communication and utilities, trades and
services, cultural entertainment and recreation and resource production
and extraction. The inventory also identifies wetlands, open and
forested areas. All information on the 57 land-use categories has been
prepared for computer analysis by the Connecticut Department of
Transportation to quantify and analyze land-use statistics and repro-
duce the data on a variety of scales. Other land-use inventories are
available that include land holdings of water utilities and state-
owned property.

A zoning inventory was made in 1970 for each of the towns in
Connecticut having zoning ordinances. The various local zoning
districts axe shown on a map havIng a scale of 1:72,000. Generalized
zoning categories have been plotted on a 1:125,000-scale map of

Resource Data in Land and Water Planning 9

Connecticut. Both land-use and zoning inventories are based on 1970
data and can be correlated with the 1970 Federal census.

COMPILATION OF AVAILABLE DATA

The basic resource data available for an area of investigation
must be gathered by the user from the agencies (see Acknowledgments)
who collect and disseminate it. In addition to topography, geology,
hydrology, soils and land use, other information may be available on
biology, engineering characteristics, geochemistry and geophysics.

Availability of Basic Resource Data
Not all basic data inventories have been completed in Connecticut,
so the user may find important kinds of data missing. Table 1 shows
the status of these inventories in 1972. Only the topographic and
land-use maps are available for the entire state. The other inventories
are in progress and are constantly reviewed to improve the quality of
data. Occasionally, information can be extrapolated from adjoining
areas if not available for the area being studied.

Table 1. Status of Basic Inventories in Connecticut.

Units in State Published Mapped but
Unpublished

Topography 115 quadrangles 115

Bedrock Geology 115 quadrangles 57 43

Surficial Geology 115 quadrangles 50 32

Soil Surveys 8 counties 3 34 towns

Water Resources Inventories

Basic Data Reports 10 basins 7 1

Interpretative Reports 10 basins 4 3

1970 Land Use Inventory 115 quadrangles 115

In developing a resource interpretation system, it was found that
some natural resource data were not available. Either their value was
unknown, techniques were not available for their aquisition or they
were not considered useful at the scale chosen. Some examples are:
depth to bedrock of 15-25 feet, the chemical chaxacteristics of surface
and ground water and description of engineering properties of surficia.1
material and bedrock.

10 Connecticut Experiment Station Bulletin 733

Need for Common Base, Scale and Boundaries
In the past, each agency has determined its own needs for scale,
base and survey boundaries. The soil survey field mapping is done at
a scale of 1:15,840 on an aerial photograph base. Mapping is done
town-wide and published county-wide at scales of 1:15,840 or 1:20,000.
Geological survey mapping (surficial materials and bedrock) is presently
done at a scale of 1:24,000 on a topographic base covering an area of
about 56 square miles. Soil mapping is more detailed than geological
mapping because it was originally planned to serve as a tool for farm
planning.

Scale and boundaries can be adjusted by careful mechanical methods.
Controlled aeria.1-photograph mosaic maps can be reduced in scale to
1:24,000 or the topographic map can be expanded to 1:15,840, whichever
is determined the most practical scale. The aerial photograph base map,
however, has inherent distortion and the identifiable features on the
topographic base and the aerial photograph base are often incongruent.
For example, using mechanical metho-ds of reducing soil maps, streams
may appear on the opposite side of a road when superimposed on the
topographic map. A perfect adjustment of maps requires hand transfer
of the information which is time consuming and expensive. The future
use of orthophoto base maps for both soils and geology mav eliminate
such problems. Orthophoto maps combine the traditional elements of the
topographic map and the aeria.1-photograph map and have been corrected
for distortion.

Alterations in map scale, however, may affect both the accuracy of
the data and its legibility. For example, reduction of scale from
1:15,840 to 1:24,000 alters the validity of the soils data and details
become difficult to read. An enlargement in scale from 1:24,000 to
1:15,840 might also affect the validity of the data and a larger map
is required to represent the same axea. The basic inventory data, then,
is most accurate within the scale chosen to represent it.

Despite the problems encountered, the basic resource data from many
sources must be converted to a common base map and scale in order that
they may be used to integrate the information on the maps. Commonly
the basic resource data from each discipline are difficult to use
because they include a wide vaxiety of properties. For example,
drainage, depth to bedrock, texture and slope segregate different soils
in the classification scheme. When these properties are used to define
mapping units on a soil survey map, a detailed pattern results which
may be too complex for some users' needs. The user may wish to
examine some properties sepaxately because they have great impact on
the management of land and water resources. Single-factor maps can be
derived from the detailed maps to simplify the use of data. The kinds
of single-factor maps are limited only by the scope of the basic data
from -which they are derived. Some basic resource data maps can be used
directly as single-factor maps if they relate to only one kind of data;
topographic maps, land-use maps and zoning maps are examples. Table 2

Resource Data in Land and Water Planning

Table 2. Matrix of single-factor
maps derived from basic data
sources.

P
19

0
0
P, r.

P4
(D Id
M -,4 k
0 0 0
0 4NI "o
Id
A
0

Id
0 HrA
0
S3NGLE-FACTOR MAPS E-4 MO 14

1. Topography 0
2. General slope map 0 0 0
3. Slope greater than 155 0 9
-7. Slope less than 35 and soil seldom
saturated 9
5. Bedrock type 0 0
6. Structural characteristics of bedrock 0
7. Outcrops 0
Depth to bedrock: 0-2 feet 0
Depth to bedrock: 0-10 feet 0
10. Depth to bedrock: 50-foot intervals 0
1-1. Unconsolidated materials 0 0
12. Sand and gravel deposits 1 0
1@. Unified soil classification of substratum 0 0
14. Soil saturated with water within 3 feet 0 0
- of the surface for 2 to 12 months
175. Soil saturated with water within 3 feet 0 0
of the surface for less than 2 months
16. Peat and muck deposits 0
17. Percolation rate classes 0
18. Agricultural land use capability 0 0
.19. Drainage areas 0 0
20. Floodprone axeas 0 0 0
21. Law I'low of streams 0 0
22. Saturated thickness of stratified 0 0
unconsolidated deposits
73-. Availability of ground water 0 0
Location of existing sanitary and water
related facilities, services and uses 0
25. Land use: 1970 0
126. Zoning: 1970 1 1 0 I-A

12 Connecticut Experiment Station Bulletin 733

lists, on the left, examples'of single-factor maps that can be produced
and, on the right, the sources of basic data from which single-factor
maps axe derived.

For example, three different published sources may provide depth-
to-bedrock information. Some surficial geology maps show the distribu-
tion of rock outcrops and axeas where bedrock lies within 10 feet of
the surface. Soil survey maps delineate shallow-to-bedrock soils where
bedrock is within 2 feet of the surface. Some water-resources inventory
maps show estimates of depth to bedrock in 50-foot intervals. By
extracting this single factor from all three sources, a ma.'o can be
produced that shows both exposed bedrock and depths to bedrock beneath
the surface. Intervals of 0-2 feet, 2-10 feet, 10-50 feet, 50-100 feet,
etc., can be delineated. Such single-factor maps show only the
distribution of the resource and are not biased by prior knowledge of
land and water use.

Single-factor maps show map units of materials, slope, depth and
volume selected to maintain accuracy consistent with the limitations
of the original data and the scale of map presentation.

Establishment of Management Guidelines
Because land, water and mineral resources vary from place to place,
and the concepts of acceptable land and water use also vary, the
criteria of use must be established by the user. He must first define
criteria of acceptance for a particular use in a specific area. These
criteria can be expressed in management guidelines, which may include
statutory regulations, availability of specific resources, conditions
requiring site preparaticn@,or limitations of money.

The guidelines depend on the specific use that is planned. There
are two general types: corridor development and site development.
Corridor development requires study of all natural resources along a
corridor between two points and whose width is determined by the user.
Site development may involve location of a site that has an extractable
resource (e.g., sand and gravel) or a site that will serve as a host
for a specific use (e.g., sanitary landfill). Here the natural
resources of the site and its environs are evaluated. A closer
examination of each of these uses follows.

Corridor Development
In corridor development, the controlling factors are the points to
be connected by the corridor and the width of the corridor. Usually
the end points have already been established and the area between them
is the focus of investigation. The management guidelines for corridor
development attempt to create the least impact on the environmental
quality of the area. Each resource characteristic is evaluated for
its effect on the corridor during and after development. In many cases
the single-factor maps are used to determine a preliminary cost
evaluation before proceeding with site inspection. They can also be

Resource Data in Land and Water Planning 13

-used to assess impact along the corridor and costs for alternative
routes. The management guidelines in corridor development may include:
(1) the existing regulations controlling the use of the resources or
the use of the area, (2) attempts to minimize the detrimental effects
on the environment of the area and (3) attempts to minimize cost.

Site Development For The Extraction Of An Existing Resource
When a site is developed for the extraction of an existing resource
(e.g., sand and gravel) an important consideration is the presence of
adequate reserves. Management guidelines can be drafted listing the
preferred conditions for extraction and an evaluation of the impact
on the area as a result of the extraction. These management guidelines
may include: (1) considerations of volume and quality of material,
(2) rate and method of extraction, (3) the regulations controlling the
use of the resource in the area where it occurs and (4) conflicts w-Ith
existing land use. The order of selection of other single-factor maps,
beyond the initial map which establishes the distribution of sand and
gravel, depends largely on the philosophy of the user.

Site DeveloEEent To Serve As A Host
When a site is developed as a host for a specific use (e.g.,
sanitary landfill) many physical corlditions may exist that are acceptable
within the management guidelines but not ideal. Often acceptability of
a site will depend on the alternatives available for site preparation
to adjust the site to agree with the management guidelines. Since the
selection of a site for sanitary landfill will be used to illustrate
how the natural resource interpretation system works, a more detailed
list of guidelines is appropriate. This list is hypothetical and for
illustration only; other local factors also may be important and other
guidelines could be chosen.

(1) To comply with State regulations on disposal of refuse (Conn.
Dept. Health). These regulations, in part, read: "No refuse shall be
deposited in such manner that refuse or leachings from it shall cause
or contribute to pollution or contamination of any ground or surface
water on neighboring properties. No refuse shall be deposited within
fifty feet of the high water mark of a watercourse or on land where it
may be carried into an adjacent watercourse by surface or storm water
unless protective measures approved by the State Department of Health
are provided."

(2) To insure sufficient storage capacity per acre through develop-
ment of a trench-fill operation with a trenching depth of at least 12
feet.

(3) To provide for the development of an area greater than 25 acres.

(4) To avoid conflicts with land and water uses of the surrounding
areas (e.g., sight, odor, traffic).

14 Connecticut Experiment Station Bulletin 733

(5) To prepare the site at minimum cost with tree clearing, trench
preparation and establishment of access as the main items of expense.

(6) To provide adequate and suitable cover material at the site
and avoid transporting it from other axeas.

(7) To minimize the degradation of the existing natural resources
in the axea.

Once management guidelines have been developed, the single-factor
maps can then be used to eliminate from consideration the axeas that
are unacceptable because of natural limitations or because they exceed
the user's willingness to alter the site to make it compatible with
the management guidelines.

Analysis of Data
The selection of the single-factor maps to be used in evaluating
the intended land or water use is determined by management guidelines.
Table 3 illustrates the type of matrix that can be developed to indicate
the relationships between the single-factor maps and potential land use.
Either columns or rows can be expanded or contracted. The list of
single-factor maps is determined by the data available while the use
ordinate is chosen by the user. He may require only a single use or
he may want to evaluate alternative or multiple uses for a given site.

The single-factor maps can be compared with statements in the
management guidelines for each use and those characteristics that
directly relate to a statement in the guidelines can then be recorded.
A simple check system (verticle column 3, Table 3) can be used to
indicate the particular bits of information needed. Alternatively,
more specific relationships can be established by assigning a weighted
value to the single-factor map (verticle column 11, Table 3) to indicate
that some bits of information are more important than others in
eva.luating for a particular land use.

The map units used on single-factor maps are chosen by the agency
collecting the data and are based in part on estimates of field
precision. The units of measurement in the management guidelines are
often arbitrary but commonly have a scientific base.

Map units and management guideline units often differ, of coarse,
thus introducing a limitation into the system. For example, a manage-
ment guideline for a trenched sanitary landfill may require a minimum
thickness of unconsolidated materia.1 of 12 feet. A state regulation
which provides another guideline requires that the base of the landfill
must be at least 4 feet above bed-rock. Therefore, to meet both guide-
lines the site must have at least 16 feet of unconsolidated materials
aver bedrock. The single - factor map for depth to bedrock has units
of 0-2 feet, 0-10 feet, 0-50 feet and deeper. None of these precisely
fits the management guideline. The 0-10 feet depth provides the

Resource Data in Land and Water Planning 15

Table 3. Matrix of relationship
of selected land uses to single-
factor maps. 0 A P,
4Z@
A

0
P4 -P
4J 10 P0, g
H ;9 0
rd P@
F4 H rd -;49
@1 H -1 @4 0 r-4
CH 0 rg 0 0
P, H EO
0 &
H P H or- 0
W &a to H H Id k 0 rq
;g W ka (0) rroik'd M
rq z 0 k 0 r-q 0
rd .0 Cd 0 W ;j rd $4 0 U2
-H 9 H 0 rq 0 H ;j
@D -ri ri 4p@ r_4 F4
r-i Q) -rq k
0 M rd 0 0
.0
Cd
k -H 0
0 _P _P -P PL
0 rn (1)
_P
rd
bf 0
H @4 P @4f E-4 P4
SINGLE-FACTOR MAPS r4 c@ C@ V; "D
P, P,
,D t@ C6 C@ C;
I .111 C"i r @ql
1. Topography 21 1 1
2. General slope 1 1 21 1
3. Slope greater Than 15% 1
4. Slope less than A and soil seldom 1
saturated
5 ! Bedrock type 1
6. Structural characteristics of bedrock -1
1. Outcraps 2
d. Depth to bedrock: 0-2 feet 12
9. Depth to bedrock: 0-10 feet 0 1
17. Depth to bedrock: 50-foot intervals 0 1.
11. Unconsolidated materials 1
12. Sand and gravel deposits 0 11
13. Unified soil classification of substratum 0 1
17. Soil saturated with water within 3 feet 0 1
of the surface for 2 to 12 months
15. Soil saturated with water within 3 feet 0 1
of the surface for less than 2 months
16. Peat and muck deposits 0 1
11. Percolation rate classes 1'@l
lb. Agricultural land use capability 3
19. Drainage areas 21 1 1 1
27. Floodprone areas 11 1 1
21. Law flow of streams 21 1 1
22. Saturated Thickness of stratified
unconsolidated deposits 21 11 1
2@. Availability of ground water 0 1
24. Location of existing sanitary and water
re ated facilities, services and uses
2@. Lan use: 1970
1 26. Zoning: 1970
1 = Primary importance; 2 = Secondary importance; 3 Indirectly related

16 Connecticut Experiment Station Bulletin 733

closest unit, but fails to identify the areas with depths between 10
and 16 feet. This limitation can be reconciled during site investiga-
tion. Similarly, reconciliation by site investigation must also be
made in the case -where single-factor maps are not available that meet
the criteria expressed in the management guidelines.

Use of Transparent Maps
The single factors extracted from basic resource data maps can be
drafted at a common scale on stable transpaxent material. The trans-
paxent single-factor maps judged critical to the evaluation axe stacked
congruently by the user to: (1) rule out axeas regarded as unacceptable
for the particular use or (2) locate areas where the characteristics
may be idea.1 for the particulax use. This preliminary evaluation in no
way replaces the need for on-site investigation, but it does reduce the
number of sites to be studied in detail.

A RESOURCE INTERPRETATION SYSTEM

With the basic information now at hand and the knowledge that
integration of data from maps drawn to different scales will not be
perfect, we shall develop a resource interpretation system. To
clarify and simplify the presentation of data, we shall produce a
series of single-factor maps which show specific bits of information.
Some of these single-factor maps will be ca-Iled limiting-factor maps
because either nature has placed a severe limitation on the land
(i.e., steep slopes, bedrock or water tables at sha-Ilow depths) or
man has limited its use by earlier decisions (i.e., current land use
and zoning). The costs of correcting these limitations may be prohibi-
tive. The resource interpretation system is flexible because the user
needs only to use the bits of information considered important in his
management guidelines.

To demonstrate the use of the system, an area of about 8 squaxe
miles in the Ellington quadrangle will be examined by collating.several
of the single-factor maps to determine potential areas for dumping
solid wastes, an important need in our time.

Single-factor Mas
The single-factor maps for the study axea were chosen for their
usefulness. Additiona.1 factors may be important in other study axeas;
these must be determined by local needs. For example, soil salinity,
which affects a.11 uses of soil, may be important in areas of limited
rainfall, but is considered less important in the humid Northeast.

Selecting a potential site for a sanitary landfill has been chosen
to illustrate how the sihgle-factor maps can be used. In this example,
the resource will serve as a host for the intended use. A variety of
conditions may be acceptable depending upon the willingness of the
user to spend money on site modification. Some conditions will not be
acceptable because the limiting factors outweigh the economic means
necessaxy to change them.

Resource Data in Land and Water Planning 17

It is assumed that there is no preconception of where the landfill
should be or what land is available for such use. The geographical
area is scanned to determine -where a landfill will conform to the
management guidelines. Alternatively, if several available sites
within a geographical area are known, they can be examined to evaluate
limitations imposed by the resource or management guidelines selected
by the user.

Each of the single-factor maps, shown in Table 3, will be briefly
described, their units of measure defined, and interpreted for a
specific example: the selection of a sanitary landfill site. Each
map has been numbered for reference, but not all of them will be
used in the example. The complete set of single-factor maps developed
for the Ellington quadrangle is on file at the Natural Resource Data
Services Center, Department of Environmental Protection, Hartford.

1. Topography. In determining the suitability of land for a
paxticular use, it is important to know -where the tract of land lies
in relation to its surroundings and if slopes are steep. A topographic
map indicates whether the land is on a ridgetop, hillside, or in a
valley. Steep slopes are shown as closely spaced contour lines. One
may also observe natural and cultural features such as swales, streams,
and whether the site is accessible by roads or near houses. Topographic
maps, however, will not show roads and houses built since the map was
published. Most older maps are being revised to show new cultural
features. If the land is used for sanitary landfill, the tcpographic
map will show nearby streams, swamps and houses, and whether the
present road network will provide access to the site. These factors
may not be critical but may enter into a comparative study of all
potential sites. Steep slopes, a critical factor, are shown on a
separate map.

2. General slope map. Slope may limit use of the land and is
important in land shaping, excavation and final grading for houses,
highways, parking lots and industrial development. It influences
construction of systems for disposal of septic tank effluent and
control of surface water.

General slope maps may be produced from both soils and topographic
maps. A soils map shows ranges of slopes measured on the land. The
last letter of the map symbol (e.g., ChA, ChB, etc.) indicates its
slope range as follows: A = 0-3%, B = 3-81o, C = 8-151o, D = 15-25%,
E = 25-35%, F = 35-451o. In very stony or very rocky axeas the ranges
are combined as BC = 3-15% and DEF = greater than 15% because stones,
boulders and bedrock outcrops axe more limiting than slope.

General slope maps are derived from topographic maps by scaling the
distance of the slope and determining differences in elevation between
two points on the scale. Slopes may be expressed in several ways:
as percentages, angles or in feet per mile.

18 Connecticut Experiment Station Bulletin 733

Slope, as it concerns sanitary landfill, falls into three categories.
The first is land having slopes greater than 15%. This land would be of
limited value in preparing a landfill because development costs could
be prohibitive and in direct conflict with the selected management
guidelines. Because of this relation between excessive slope and costs
of site preparation, a separate overlay showing steeply sloping axeas
was constructed (Map 3, Table 3) which can be utilized as a limiting-
factor map.

A second slope category delineates a suitable slope for a sanitary
landfill, 0-31o. Relatively flat land would require the least amount
of site preparation. Since this resource factor best complies with the
management guidelines, a sepaxate overlay map can be used. Map 4
(Table 3) not only shows the distribution of land having slopes less
than 3%, but also only those slopes underlain by well-drained soils.
Despite favorable slopes and surface drainage, however, these areas
may be underlain by coarse materials with low filtration capacity or
impeded drainage above a depth of 16 feet which may conflict with the
selected management guidelines.

The third category includes all remaining intermediate slopes,
3-15%. In general, costs of site preparation will rise with increases
in slope. The genera.1 slope map shows whether the land trends to-ward
favorable or prohibitive conditions.

3. Slope greater than 15%. This map delineates those axeas where
normal site development might be limited by the steepness of the slope.
An example of such a site is shown in Fig. 1. Steep slopes require
special design for sewage disposal systems and soil and water conserva-
tion. Increased construction costs may also be limiting. For sanitary
landfills the costs of developing trenches on steeply sloping land may
be prohibitive and in conflict with management guidelines. Steeply
sloping areas axe shown separately and the map can be used as a
limiting-factor map. Other slope units could have been used if they
had been set forth in the management guidelines for a different use.

4. Slopes less than 3% and soil seldom saturated. This map,
derived from the basic soil survey map, delineates axeas that are
suitable for a wide variety of uses including agriculture, urban
development, woodlands and recreation. In these areas, competition
for various uses could be great because there axe few, if any, natural
limiting factors. Design and construction costs should be low. The
favorable attributes of areas having slopes less than 3% and underlain
by well-drained soil prompts their separation from other data. For
sanitary landfills, this map may conform to many of the management
guidelines. This map does not show, however, the presence of a water
table below normal soil depths (5 feet). On-site investigations in
early spring would show if a water table is present within 16 feet of
the surface.

Resource Data in Land and Water Planning 19

Figure 1. Steep slopes, coTmonly stony, prohibit most
kinds of development. Sewage and -waste disposal is
mostly limited by steepness of slope and shallowness to
bedrock. Historically, most steep slopes, as the one
above, have remained wooded. (Photo - Soil Conservation
Service)

5. Bedrock type. The kinds of rocks that underlie a geographical
axea are delineated on a bedrock-lithology map. The map units
correspond to the geologic map units (Collins, 1954), but have been
modified from recent detailed mapping in the Ellington quadrangle,
adjacent quadrangles and from interpretations of aeromagnetic data
(Pitkin, Philbin and Gilbert, 1969). This map, unlike the geologic
map, is not concerned with the relative stratigraphic position of each
rock type. The variety of rock types contained within these map units
are defined in terms of physical properties that are useful for engineer-
ing and land management.

The bedrock map may be used to determine a possible source of
conflict between use of the site and use of the underlying rock. If
the bedrock is covered by a sanitary landfill, the future use of the
rock as a resource could be eliminated. A second conflict could occur
if the bedrock is known to be an important aquifer. In this case, a
decision must be made either to avoid the use of the land because of
possible contamination or to protect the aquifer by special site
preparation.

20 Connecticut Experiment Station Bulletin 733

6. Structural chaxacteristics of bedrock. Contacts between the
rock types are shown on this map. They may be sharp or gradational,
but most contacts axe covered by glacial material and cannot be contin-
uously traced. Faults, where displacement of the rock has occurred,
are a1so shown. A fault 'may involve a single fracture or a zone of
fractures up to severa.1 hundred feet wide. The bedrock system in
fracture zones generally is structuraIly weak. Joints and fractures
a.re numerous and tend to decrease in abundance outward from the fault.
The fault may extend to depths of hundreds of feet and serve as channels
for ground water. An example of fractured bedrock is shown in Fig. 2.

Figure 2. Bedrock outcrops along highway cuts exhibit many
fractures. The gently sloping fractures are along bedding and
foliation planes. The steeply sloping fractures are along
joints. The prominant steeply sloping fracture in the center
of the picture is a fault. All of these fractures may extend
to considerable depth and serve as pathways of -water movement.
(Photo - U.S. Geological Survey)

Other symbols on the map define the attitude of surfaces formed by
alignment of certain minerals, called foliation. Foliation allows rocks
to split apart in preferred directions. Also shown is the attitude of
bedding which reflects the way the materials were originally laid down.
For the Ellington quadrangle, the bedding symbol is equivalent to the
foliation symbol. Trends of foliation and bedding and zones of potential
bedrock weakness are shown on a separate map.

Resource Data in Land and Water Planning 21

The physical properties of bedrock in the area studied are important
even though refuse in a sanitary landfill must be kept at least 4 feet
above the bedrock suxface. As leachate must inevitably move out of the
site axea, in many places it will probably reach the bedrock surface not
fax from the site, and may eventually seep to the bedrock. If the bed-
rock is relatively massive and lacks interconnecting fractures, leachate
will follow the bedrock surface. The direction and ease of transport of
leachate within bedrock depends upon permeability, water pressure,
attitude of layering and abundance of interconnecting fractures.

7. Outcrops. This map, derived from the basic suxficial-geology
map, shows the 1,ocation and distribution of outcroppings of bedrock.
Small, closely spaced outcrops are not shown on the map separately, but
are included in the areas of thin glacial material.

In accordance with management guidelines, the refuse in a sanitary
landfill must be kept at least 4 feet above the bedrock surface, thus
areas of exposed bedrock (outcrops) are unacceptable for a landfill.
This map can be used as a limiting-factor map.

8. Depth to bedrock: 0-2 feet. This map, derived from the basic
soil survey map, delineates areas, such as those shown in Fig. 3, where
the soil cover is very thin. Areas covered by shallow soils also may

Figure 3. Many acres of Connecticut's landscape axe
only thinly covered by soil. Shallow depths to bedrock
severely influence construction activities, productive
agriculture and forest growth. (Photo - Soil Conservation
Service)

22 Connecticut Experiment Station Bulletin 733

have numerous rock outcrops (not precisely located as in a surficial-
geology map). These areas severely influence construction such as
foundations, underground utilities, sewage disposal systems and sanitary
landfills. They also limit agricultural and forestry pursuits because
of low moisture reserves and difficult management. Most of these areas
have remained wooded.

Areas of 0-2 feet to bedrock are in conflict with the management
guidelines for sanitaxy landfills because at least four feet of clean
material must lie between the bottom of the landfill and the top of the
bedrock. This map can be used as a limiting-factor map when the map
showing 0-10 feet to bedrock is not available.

9. Depth to bed-rock: 0-10 feet. This map, derived from a surficial-
geology map, delineates areas where the thickness of unconsolidated
materials is estimated to be 10 feet or less. The glacially-scoured
surface of the crystalline bedrock of the Eastern Highlands is seldom
flat and smooth, but usually has a rough, jagged appeaxance. Small
deep pockets may occur within the 0-10 foot thick axeas shown on the
map. Filled with unconsolidated material, they create depths that
exceed 10 feet. Bedrock sometimes lies just below existing trenches
and seepage pits and might be overlooked if subsurface investigations
are inadequate.

Areas of 0-10 feet'to bedrock are in conflict with the management
guidelines since they require trenches at least 12 feet deep and an
additional 4 feet of soil material above the bedrock for a totaJ_ of
16 feet. Areas having thicknesses of unconsolidated material less than
10 feet would not be acceptable. A map showing depths of 0-15 feet to
bedrock would be more useful. Without these data, which more closely
conform to the management guidelines, this factor must be closely
examined during on-site investigations. This is a limiting-factor map.

10. Depth to b drock: 50-foot intervals. This map shows ranges
in depth to bedrock. Fifty-foot intervals were chosen after considera-
tion of accuracy and irregular distribution of the data. Ranges in
depth were derived from the water-resources inventory and records of
wells and test holes.

This map serves to identify areas where the depth of unconsolidated
materia.1s is not a limiting factor for sanitaxy landfills. This map
can be used in the same way that Map 4 was used to identify areas where
conditions may be well suited. It must be recognized, however, that
this map only estimates the total thickness of the unconsolidated
material lying above the bedrock. The characteristics of the material
may change with depth.

11. Unconsolidated-materials map. This map, derived from the
surficial-geology map, shows the distribution of the principal kinds
of unconsolidated materials. The natural deposits, glacial till, sand

Resource Data in Land and Water Planning 23

and gravel, and swamp deposits are assumed to be at least 3 feet thick
and are shown as they occur beneath the soil layer. The total thickness
of a map unit is not shown; different materials may occur at depths
beneath the map units.

Glacial till is a poorly-sorted mixture of boulders and stones with
sand, silt and clay sizes in varying proportions. Some till is loose,
sandy and very stony and is commonly less than 10 feet thick. Other
tills are less sandy, less stony and very compact (hardpan) and average
more than 10 feet thick. Where these tills occur together, the loose
sandy till lies on top of the compact till. The two vaxieties of till
have quite different physical properties. They were not differentiated
on this map because the data were unavailable for this quadrangle.
Therefore, detailed investigations of the physical characteristics and
thickness of till is necessary for planned site development.

Swamp deposits contain organic matter sometimes mixed with sand,
silt and clay. They form in very poorly drained areas, in valleys and
on broad, flat uplands underlain by hardpan.

Artificial fill is shown only where it is extensive and well defined.
They are found in areas filled for highways, flood-control structures,
solid-waste disposal and other major construction. In urbanized areas,
natural land conditions are often extensively altered but are not shown
on the map as such.

The unconsolidated materials map for the Ellington quadrangle
delineates the areas of glacial till and stratified sand and gravel.
The preferred host material should contain sufficient fine material
(silt and clay) to retaxd rapid percolation and promote chemical and
biological filtration of the leachate generated in the landfill, yet
the material should be coarse enough to provide a cover that will
support traffic when it is wet. These two characteristics of the
materials seem to conflict with each other. The materials map, however,
is especially useful in identifying areas where the fine-textured till,
a good host, is adjacent to deposits of stratified sand and gravel, a
good cover. Some tills, however, are quite sandy and also provide
suitable cover, but they were not differentiated on this map from the
siltier, compact till which commonly provides poor cover. The usefulness
of the materials map could be improved if the basic surficial-geology
map had differentiated between the two kinds of tills.

12. Sand and gravel deposits. This single-factor map is derived
from Map 11. Sand and gravel deposits such as shown in Fig. 4 have
been isolated because they are important economic resources. These
deposits are composed of varying proportions of sand, pebbles and
cobbles which commonly occur in layers. Detailed on-site investigation
is necessary to determine composition, thickness and areal extent.
These deposits are not only important sources of construction materials,
but those covering large areas also may be important aquifers.

24 Connecticut Experiment Station Bulletin 733

WOOL,.,

t@' 7-
-01

_4@
@ i7w T @ -5r-

-47

Figure 4. Sand and gravel deposits have long been an important
economic resource in Connecticut. In some areas these deposits,
which axe also important aquifers, are rapidly disappearing.
(Photo - U.S. Geologica.1 Survey)

Sites containing sand and gravel may be easily prepared for a
sanitary landfill, but conflicts may arise with management guidelines.
For example, the use of the site for sanitary landfill must be
evaluated against its use as an extractable resource. Further 'both
uses must be evaluated against its use for water supply if the sand and
gravel aquifer contains a large supply of water.

13. Unified soil classes of substratum. This map, derived from
interpretative tables in the soil survey reports, shows the Unified Soil
Classes (Waterways Experiment Station, 1953) assigned to the substratum
(unweathered material generally below a depth of 30 inches) of each
soil series. The Unified System classifies mineral and organic-mineral
mixtures of soils for engineering purposes and is based on particle
size and moisture characteristics. For simplicity, the soils of the
Ellington quadrangle have been separated into classes of coarse-grained,
fine-grained and highly organic materials.

The map showing the Unified Soil Classification of the substratum
prov-ides information concerning the physica.1 characteristics of the
host and cover materials for a sanitary landfill. It enables the user

Resource Data in Land and Water Planning 25

to make preliminary estimates of such performance qualities as strength,
compressibility and permeability. The user may determine whether the
material at the site can be used as cover or if a different material
must be imported at additional cost.

14. Soil saturated with water within 3 feet of surface for 2-12
months. This map, derived from a soil survey map, delineates axeas
with a persistant high water table which seldom falls below-3 feet
from the siirface except during prolonged rainless periods. The
saturated zone is usually above an impermeable soil layer as in Fig. 5
or bedrock. These conditions are found in generally flat areas and the
water table fluctuates through a narrow range of depths below the surface.

Figure 5. Many soils have shallow water
tables that persist throughout the year.
Septic tank drain fields will not function
and solid wastes buried in these soils will
become flooded with water, producing
undesirable leachate. (Photo - Soil
Conservation Service)

26 Connecticut Experiment Station Bulletin 733

The maximum height generally can be determined by noting the depth in
the soil at which color mottling occurs. Poor drainage limits many
uses, but in places it can be corrected by drainage systems. Generally,
the soil drainage classes delineated here are:

a. Poorly-drained soils where the zone of saturation is within
0-6 inches from the surface during the wettest paxt of the year. The
saturated zone persists into early summer and may reappear after pro-
longed or unusually heavy summer rains. The water table is usually
observed within 4-5 feet of the surface even at its lowest point of
fluctuation.

b. Very poorly-drained soils where irater ponds on the surface for
significant periods in winter and early spring and persists within 3
feet of the surface throughout the year.

Management guidelines established the need to locate the high water
table relative to the base of the landfill (greater than 2 feet below).
A map showing the depth to saturated zones is not available. This
single-factor map, however, identifies the soils saturated with water
within three feet of the surface for known lengths of time. It serves
to identify areas in conflict with the management guidelines. This
map can be used as a limiting-factor map. The user must be awaxe that
a water table which rises seasonally within 14 feet of the surface will
still conflict with management guidelines. In the absence of water
table information within 14 feet of the surface, this factor must be
critically examined during detailed site investigation.

15. Soil saturated with water within 3 feet of surface less than
2 months. This map, derived from a soil survey map, delineates axeas
-which have a temporaxy high water table within 3 feet of the surface.
In these axeas, the water table may fluctuate over a wide range of
depths. During the highest point of fluctuation, generally occurring
in eaxly spring, the zone of saturation may lie within 15 to 20 inches
of the surface. The high water table seldom persists beyond late spring.
In wooded axeas the lowering of the water table is augmented by trans-
piration as new leaves begin to form on the trees. Areas delineated on
this map belong to the class of moderately well-drained soil. Imperfectly
drained axeas, like poorly drained ones, may be in conflict with
management guidelines, for greater quantities of leachate may be
produced in early spring and following prolonged rains which may affect
ground-water and surface-water quality in the region. An alternative
to the prohibition of use of areas of high water table would be to
drain the site or control the leachate produced in the landfill.

16. Peat and muck. This map, derived from a soil survey map,
delineates the axeas of organic soils where centuries of plant remains
have accumulated in former lakes and ponds. Most of the plants are
reeds and sedges, but in places remains of former forests are found
buried in the peat. Accumulations of peat camonly range in depth from

Resource Data in Land and Water Planning 27

1 to 25 feet. Many shallow deposits and the surfaces of most deep
deposits are highly decomposed and called muck. Virtually all peat and
muck areas are undrained and have a permanent high water table. They
are limited for most uses.

Areas of peat and muck are in conflict with the selected management
guidelines for they usually have a persistant high water table and the
materials may not serve as a suitable host. The use of these sites for
sanitary landfill would require extensive preparation. Although all
areas shown on this map are also shown on Map 14, this map segregates
wet unstable organic soils from wet mineral soils.

17. Percolation rate classes. This map, derived from interpretative
tables in soil survey reports, delineates areas of probable percolation
rates which can be used to assess the capability of a soil to transmit
effluent from on-site sewage systems. The rates are estimated from
percolation tests which measure the rate at which the water level falls
in a percolation test hole 30 to 36 inches deep. As water passes into
the surrounding soil, its rate is influenced by the condition of the
wall and by the porosity and moisture content of the unsaturated soil
through which it flows (Hill, 1966).

Percolation rates may be expressed in two ways: "inches per hour"
and inversely "minutes per inch". Class limits are arbitrary, but
correspond to those established by the Connecticut Department of Health
(1970). It is difficult to assign a precise percolation class to each
mapping unit, therefore, a probability factor is introduced to account
for site and seasonal variations. Percolation rates vary with site and
season in all soils, but the vaxiation may fall within a single percola-
tion rate class. These soils are easy to segregate. Those whose
seasonal variations straddle one or more classes are more difficult to
segregate. At best we can estimate the probability of soils with
intermediate rates being classed with the fast or slow rates. The rate
classes are fast, probably fast, probably slow and slow.

Although percolation rate data is derived from soil maps and
therefore limited to depths of 3 or 4 feet, broad estimates may be made
on deeper materials if they are similar to the materials from which the
soil has developed. The map can be used best to estimate the rate of
movement of leachate from landfill areas into the surrounding soil.
Soils in the "fast" percolation class indicate that leachate may move
rapidly from the landfill area. Soils in the "slow" category of
percolation may indicate areas where the movement of leachate is slow.
There is, unfortunately, little information on the rate of production
and control of landfill leachates at the present time.

18. Agricultural land use capability. This map delineates the
broad capability classes of soils. Groups of soils are classed to
show, in a general way, their suitability for most kinds of farming.
The grouping is based on limitations of the soils (i.e., drainage,
erosion, stoniness and wetness), the risk of damage when they are used,

28 Connecticut Experiment Station Bulletin 733

and how they respond to such treatments as drainage, irrigation and
fertilization. There are eight capability classes designated by Roman
numerals I through VIII. In Class I are soils with the fewest
limitations, the widest range of potential use, and the least risk of
damage. The soils in other classes have progressively greater limita-
tions.

Capability classes are primarily used to evaluate and plan methods
of farm management, yet they provide the planner with an evaluation of
the land for agriculture against use for sanitary landfill, home sites,
open space and recreation.

19. Drainage areas. This map, derived from a topographic map and
the water-resources inventory, segments the landscape into natural
surface drainage basins. The divides between basins and the total
drainage area in square miles that contributes streamflow to selected
sites on major streams are shown. These sites may be stream-gaging
sites, surface water sampling sites, or mouths of tributary streams.

The distribution and size of drainage areas may provide information
on the direction of leachate flow and show-where the landfill would lie
in relation to a stream discharging from the basin. The increased
potential of pollution loading from a landfill in relation to that
contributed to the basin by other sources may also be estimated.

20. Flood-prone areas. This map, derived from a topographic map
and the -water-resources inventory, delineates areas that may be flooded
on the average of once in fifty years (i.e., there is a 1 in 50 chance
that flooding could occur in any one year). Areas larger than those
shown could be flooded less frequently and smaller areas flooded more
frequently. This map identifies areas that are in conflict with
regulatory management guidelines for sanitary landfills. Regulations
require a minimum distance of 50 feet from the burial of refuse to the
high water mark of a surface water body. To resolve the conflict, the
area would have to be protected with a dike. This map can be used as
a limiting-factor map.

21. Low flow of streams. This map shows, for selected streams,
the lowest average daily streamflow that can be expected for 30
consecutive days on an average of once in 2 years. This low-flow
Parameter is one measure of the minimum quantity of surface water
available from run-of-the-river development. Typical high and low
streamflows are shown in Fig. 6.

The distribution of low-streamflow as mapped was determined by
correlating long-term and miscellaneous streamflow records available
within the quadrangle and adjoining areas. The standard error of
estimate for any mapped unit is � 35%.

Resource Data in Land and Water Planning 29

Figure 6. In May the stream above was flowing
at a rate of 11 mgd (million gallons per day);
it flows at least this much 40% of the time.
In August the same stream below was flowing
about 0.9 mgd; it flows at least this much 90%
of the time. (Photo U.S. Geological Survey)

30 Connecticut Experiment Station Bulletin 733

The units are: low flow,less than 1 mgd (million gallons per day),
1 to 10 mgd, and 10 to 100 mgd. This information can be used to
evaluate the potentia-I effects of known volumes of wastes, as from
sewage treatment plants, on the receiving streams. Regulatory
restrictions prohibit the deposition of refuse in a sanitary landfill
in a manner that -will allow leachate to contaminate or pollute surface
water on neighboring properties. The surface water low-flow map may
be used to estimate the diluting effects a stream -will have upon the
leachate if it should reach a stream.

22. Saturated thickness of stratified, unconsolidated deposits.
The map shows by contours the thickness of sand and gravel deposits
saturated with ground water. Where these deposits form a significant
aquifer (water-yielding earth material), saturated thickness provides
information on the amount of water-level lowering available if the
aquifer is developed for water supply. The map is based on contour
maps of land and bedrock surfaces and water-level data from streams,
wells and test holes. Contour intervals were chosen after consideration
of accuracy and density distribution of the data and of the map scale.
The map shows the limits of each stratified deposit and its saturated
thickness in 10, 30 and 40 foot intervals. Deposits having saturated
thicknesses exceeding 10 feet may be important aquifers. Areas under-
lain by such aquifers may have a potentia.1 conflict between use for
landfills and for ground-water supply.

23. Availability of ground water. This single-factor map was
derived from the preceeding map and simply delineates the areas where
the saturated thickness of sand and gravel deposits exceeds 10 feet and
ma,v be a potential water supply. Under usual circumstances well yields
in sand and gravel deposits should exceed 50 ga.Ilons per minute. Most
of these potential water supply areas in sand and gravel deposits may
also be acceptable as hosts for sanitary landfill. Porous, sandy
material allows rapid transmission of leachate without adequate
filtration, however, and contamination of the ground water may result.
This conflicts with management guidelines, and the map may be used
preliminarily as a limiting-factor map. On-site investigation,
however, may show that the aquifer as too poor a yield or quality for
development of water supplies. This may resolve the conflict.
Alternatively, the site could be prepared at the additiona.1 cost of
leachate control by sealing the bottom and controlling the leachate
generated in the landfill.

24. Location of existing sanitary and water-related facilities.
This map, derived from land-use maps, shows the locations and
boundaries in 1970 of water utility service areas, land owned by water
utilities, reservoirs, watersheds tributary to existing water-supply
reservoirs, water-supply wells, and water bodies supporting recreational
activities (boating, fishing and swimming). Also shown are sewer
service areas, sewage treatment plants, solid waste disposal sites and
incinerators. This map can be used to recognize conflicts between

Resource Data in Land and Water Planning 31

Fig. 7A

H2 Residential
(Urban Low-)

ST
ST General Trades and
Services

77
-0 XF Open Lands

XO Open Lands

Figure 7. Connecticut's land resources are
used in many ways. In 7A residential and
commercial uses abut open and forest land.
In 7B residential uses are scattered among
agricultural and forest land. Here a sani-
tary landfill would offend fewer neighbors,
but its location may be inconvenient to
many. (Photo - Northeastern Connecticut
Regional Planning Agency)

Fig. 7B

AG Active Agriculture

H4 Residential
(Suburban Low)

XC Cemeteries
.'Or

71
I@F

32 Connecticut Experiment Station Bulletin 733

location of landfills and watersheds protected for surface-water
supplies. Because of possible contamination of soil and water by
leachates from landfill, most watershed areas presently are not accep-
table as sanitary landfill sites. This map also identifies nearby
sewer lines through which collected leachates might be pumped to a
treatment plant.

25. Land use: 1970. This map shows the distribution of areas for
57 kinds of land use under such categories as residential, manufacturing,
transportation, communication, trades and services, and recreation.
Some of these uses are illustrated in Fig. 7. The map shows existing
uses of land which may conflict with development of a landfill.
Conflicts must be resolved by the user on the individual merits of
population needs and costs of alternative use. The uses in conflict
with management guidelines can be ruled unacceptable for the develop-
ment of a sanitary landfill and the map can then be used as a limiting-
factor map.

26. Zoning: .1970. This map delineates areas zoned for residential,
industrial, and commercial use in towns which have zoning ordinances.
Special zones may also include flood plains and open space. This map
indicates whether the intended use conforms to current zoning regulations.
If a conflict occurs between the existing zoning regulations and the
potential use of the area for a sanitaxy landfill, the earlier decision
could be reviewed. Conflict with the management guidelines can be
resolved by either changing the zoning in the area or prohibiting the
use of the land for sanitary land-fill.

A Pilot Study
The area chosen for the pilot study and development of the single-
factor maps was the Ellington quadrangle (U.S. Geological Topographic
Series) that covers about 56 square miles in north central Connecticut,
shown in Fig. 8, lies about 15 miles northeast of Hartford, and straddles
the boundary between the Eastern Highlands and the Connecticut River
Lowlands.

This particular quadrangle -was chosen for three reasons: (1) The
area provides sharp contrasts in topography, hydrologyand types of
bedrock, surficial materials and soils, (2) the existing land and water
uses include both fixed urban uses and potentially alterable rural uses,
and (3) the basic resource data were available from all participating
agencies and had been collected within the past 25 years. Most of the
data are published; some are in open file. A list of resource data
used in this study may be found in Appendix A.

Collating the Single-factor Maps
The single-factor maps which can be prepared on scale-stable
transparent material provide the user with pertinent available informa-
tion on soil, geology, hydrology and land use. The user can then select
information that will help identify axeas not in conflict with

Resource Data in Land and Water Planning 33

WINDHAM
LITCHFIELD TOLLAND
HARTFORD

NEW LONDON

MIDDLESEX

NEW HAVEN

FAIRFIELD

Figure 8. The Ellington quadrangle lies mostly in Tolland
County in north central Connecticut. The dark area within
the quadrangle is that portion used in the example, Figures
9-17.

management guidelines chosen for selection of a site for sanitary
landfill. The maps can be used to identify three kinds of areas:

1. Areas can be identified that are not acceptable for sanitary
landfill because they conflict with the original management guidelines.
The conflicts may be due to limitations created by regulations, those
created by the limiting characteristics of the resource, or those
created by incompatibility with existing use. In short, all areas that
are inappropriate to use for sanitary landfill can be identified and
ruled out of consideration.

2. Areas can be identified that provide the ideal physical
characteristics of land and water resources. These are the areas in
perfect agreement with the guidelines and will most likely require the
lowest costs of site preparation. In short, the best areas should be
the first to be considered for on-site study.

3. The remaining areas to be identified are those containing some
degree of compatibility with the guidelines, but requiring some
adjustments by site preparation to overcome conflicts -with the guide-
lines. Conflicts may be problems in access, drainage, transportation

34 Connecticut Experiment Station Bulletin 733

of cover material or control of leachate. These areas can also be
marked for on-site study.

A composite view can be obtained by stacking all of the transparent
maps that are limiting-factor maps for sanitary land-fill. For the
purposes of illustrating the composite, shown in Figs. 9-17, only the
small shaded portion of the Ellington quadrangle shown in Fig. 8 was
used. This area covers about 8 square miles.

The following transparent maps, each with areas of single limiting
factors shaded out, can be collated in the following manner:

To: Map 9, Depth to bedrock, 0-10 feet (Fig. 9)
Add: Map 14 and 15, Soil saturated with water -within 3 feet of the
surface (Fig. 10).

COMPOSITE LOOKS I= FIG. 11.

Add: Map 20, Flood-prone areas (Fig. 12) and
Map 3, Slope greater than 15% (Fig. 13).

COMPOSITE LOOKS LIKE FIG. 14.

Add: Map 23, Availability of ground water (Fig. 15).and
Map 25, Land use: 1970 (Residential areas) (Fig. 16).

COMPOSITE LOOKS I= FIG. 17.

The final composite will serve to block out all-areas of limiting
characteristics. The potentially acceptable areas appear as transparent
spaces or "windows" in the composite (Fig. 17). These windows focus
attention on specific areas. Some windows can be eliminated from
further examination because they are smaller than the minimum of 25
acres set forth in the management guidelines. The windows are primaxy
areas where on-site investigation is necessary. In order to find those
sites within the windows that may be well suited for landfill development,
Map 4, Slope less than 3% and seldom saturated, and Map 10, Depth to
bedrock: 50-foot intervals, could be inserted beneath the stack.

Many of the unshaded areas which appear as "windows" and seem well
suited for landfill may still conflict with other management guidelines.
Additional maps must be added to evaluate this possibility. For
example, Map 13, Unified soil classification of substratum, can be
inserted in the stack of other maps to determine the quality of the
site as host and supplier of suitable cover material. Map 26 could
a-Iso be inserted to determine conflicts with current zoning regulations.

If, after stacking the maps, the user finds that no sites within the
geographical area appear well suited for sanitary landfill, he may wish
to change his management guidelines. If he accepts additional site
modification (e-g-., by drainage) than the transparent map which locates

Resource Data in Land and Water Planning 35

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36 Connecticut Experiment Station Bulletin 733

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Resource Data in Land and Water Planning 37

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38 Connecticut Experiment Station Bulletin 733

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landfill trenches and erosion control without excessive site prepaxation.

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Figure 14. A composite formed by superimposing the transparent maps of Figures 10,
Shaded areas do not comply with management guidelines.

Resource Data in Land and Water Planning 41

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42 Connecticut Experiment Station Bulletin 733

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Resource Data in Land and Water Planning 43

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44 Connecticut Experiment Station Bulletin 733

areas of moderately well drained soils (Map 15) can be withdrawn from
the stack and the windows will expand and new areas can be explored.

Alternatively, if data are available, the user can develop a set of
transparent maps which delineate areas ideally suited for sanitary
landfill. If these areas, free of restrictions, are too few in number
and small in size, the user will most likely have to alter his guidelines
and accept correction of a limiting factor. Ultimately, the user must
turn to the limiting-factor maps to determine new areas where the kinds
of limitations occur that he is willing to accept.

In essence, the most important information the maps give the user is
identification of limitations that nature has imposed upon the land.
The seriousness of the limitations will depend upon the kind of use the
land is to accomodate.

SUDOMY

This report describes how geologic, hydrologic and soil data can be
integrated to provide a base for land and water use planning. The
interpretation system developed is in a simple form and flexible enough
to provide both general and detailed information. The data is intended
for preliminary planning and cannot replace the need for on-site
investigations.

First, the basic sources of natural resource data (topography,
bedrock and surficial geology, hydrology, soils, and land use) are
described and problems of integrating data to a common base and scale
are discussed.

Second, from basic resource maps and accompanying data, single-
factor maps are derived to delineate areas having common characteristics
such as steep slopes, bedrock at shallow depths, high water tables,
flooding, availability of ground-water supply, and land use. The
information can be put on scale-stable transpaxent sheets for simultaneous
observation of several characteristics. The 26 single-factor maps thus
derived in this study can be used to identify areas on the landscape
with favorable or unfavorable chaxacteristics for a variety of uses
such as sanitaxy landfills, on-site disposal of septic tank effluent,
or transportation and public utility corridors. Management guidelines
are established by the user for specific uses. The user determines
which of the 26 single-factor maps provides the most useful information.

Third, the Ellington quadrangle was chosen for detailed study.
Selection of a site for sanitaxy landfill was chosen to illustrate how
the single-factor maps can be used following development of management
guidelines that comply with statutory regulations, protect the
neighboring environment, and minimize costs of site preparation. The
transparent single-factor maps that show characteristics that limit
development of a sanitary landfill (bedrock at shallow depths, high
water table, slope, flooding) are collated to block out areas that

Resource Data in Land and Water Planning 45

conflict with the management guidelines. The areas that do not conflict
appear as "windows" and on-site investigation can then focus on these
"TAndan It.

REFERENCES

Published

1. Collins, G. E. 1954. The bedrock geology of the Ellington
quadrangle -with map. Quad. Report No. 4. Conn. Geol. and Nat.
History Survey.
2. Connecticut Department of Health. 1970. Private subsurface sewage
disposal. Hartford.
3. Connecticut Department of Health. Public Health Code Sec. 19-13-24a.
Disposal of refuse. Hartford.
4. Cushman, R. V. 1964. Ground-water resources of north-central
Connecticut. U.S. Geol. Survey Water-Supply Paper 1752.
5. Hill, D. E. 1966. Percolation testing for septic tank drainage.
Conn. Agr. Exp. Sta. Bul. 678.
6. Pitkin, J. A., Philbin, P. W., and Gilbert, F. P. 1969. Aeromagnetic
map of the Ellington quadrangle and paxt of the Rockville quadrangle,
Hartford and Tolland Counties. U.S. Geol. Survey Geophysical Invest.
map. GP-648.
7. Ryder, R. B. and Weiss, L. A. 1971. Hydrogeologic data for the
upper Connecticut River basin, Connecticut. Conn. Water Res. Bul. 25.
8. Waterways Experiment Station Corps of Engineers. 1953. The unified
soil classification system. Tech. Memo. No. 3-357. 2 vol.
Vicksburg, Miss.

Open File Maps

1. Colton, R. B. 1972. Bedrock outcrops and areas of thin drift,
Ellington quadrangle. U.S. Geol. Survey, Geologic Div., Middletown,
Conn.
2. Colton, R. B. 1972. Materials map, Ellington quadrangle. U.S.
Geol. Survey, Geologic Div., Middletown, Conn.
3. Handman, E. H. 1972. Depth to bedrock, Ellington quadrangle. U.S.
Geol. Survey@ Water Resources Div., Hartford@ Conn.
4. Handman, E. H. 1972. Saturated thickness of unconsolidated
stratified deposits, Ellington quadrangle. U.S. Geol. Survey,
Water Resources Div., Haxtford, Conn.
5. Olin, D. A. 1972. Low flow of streams, Ellington quadrangle. U.S.
Geol. Survey, Water Resources Div., Hartford, Conn.
6. Olin, D. A. 1972. Flood-prone areas, Ellington quadrangle. U.S.
Geol. Survey, Water Resources Div., Hartford, Conn.
7. Pease, M. H. Jr. 1972. Bedrock lithology, Ellington quadrangle.
U.S. Geol. Survey, Geologic Div., Middletown@ Conn.
8. Pease, M. H. Jr. 1972. Strike trends of foliation and zones of
potentia.1 weakness, Ellington quadrangle. U.S. Geol. Survey,
Geologic Div., Middletown, Conn.

46 Connecticut Experiment Station Bulletin 733

9. Pease, M. H. Jr. 1972. Summary of properties of bedrock types
(tabular material), Ellington quadrangle. U.S. Geol. Survey,
Geologic Div., Middletown, Conn.
10. Thomas, M. P. 1972. Drainage areas, Ellington quadrangle. U.S.
Geol. Survey, Geologic Div., Middletown, Conn.

APPENDIX A: RESOURCE DATA INVENTORY, ELLINGTON QUADRANGLE

Resource Description Scale Base Status

Topography Topographic Map 1:24,ooo Polyconic projection Published (1953)
Ellington Quad., Conn. Scale changed (1967)

Bedrock Bedrock Geology Map 1:31,680 Polyconic projection Published (1954)
Ellington Quad., Conn.

FJ
Surficial Surficia.1 Geology Map 1:24,ooo Polyconic projection Published (1972)
Geology Ellington Quad., Conn.

C+
Soil Hartford County Soil Survey 1:20@000 Air photo mosaic Published (1962)

Tolland County Soil Survey 1:15,840 Air photo mosaic Published (1966)

Hydrology Water Resources Inventory 1:24,000 Polyconic projection Portions in open file; P,
of Connecticut, Part 7, USGS, Water Resources
Upper Conn. River Basin Division

Land use C+
M
& Zoning 1970 Existing Land Use 1:24,ooo Polyconic projection Open file; Conn. Office FJ
Inventory of State Planning

Location of Existing 1:24,ooo Polyconic projection Published (1970)
Sanitary and Water- (Reduced to
Related Facilities, 1:48.,ooo)
Services and Uses

Zoning of the Municipalities 1:24,000 Polyconic Projection Open file; Conn. Office
of the State of Connecticut of State Planning

Materials Statewide Coarse Aggregate 1:24,ooo Polyconic projection Published (1972);
Map Inventory by Districts Conn. Dept. of
Transportation

DATE DUE

GAYLORDINa. 2333 KiNTED IN J 5 A

I ollill
36 141070195
r

BULLETIN 733, OCTOBER 1972 THE CONNECTICUT AGRICULTURAL EXPERIMENT STATION NEW HAVEN