EPA 901/3-88-005
THE CAPE COD AQUIFER
MANAGEMENT PROJECT (CCAMP)
Demonstration of a Geographic
Information System for Ground Water
Protection
Eastham
CCAMP WAS
UNDERTAKEN BY:
U.S. ENVIRONMENTAL PROTECTION AGENCY, REGION I
U.S. GEOLOGICAL SURVEY, MASSACHUSETTS DISTRICT OFFICE
MASSACHUSETTS DEPT. OF ENVIRONMENTAL QUALITY ENGINEERING
CAPE COD PLANNING AND ECONOMIC DEVELOPMENT COMMISSION
IN COOPERATION WITH:
THE TOWN OF BARNSTABLE AND THE TOWN OF EASTHAM
SEPTEMBER 1988
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THE CAPE COD AQUIFER
MANAGEMENT PROJECT (CCAMP)
Demonstration of a Geographic
Information System for Ground Water
Protection
Edited by
Lee Steppacher
USEPA, Region 1
U.S. ENVIRONMENTAL PROTECTION AGENCY, REGION I
U.S. GEOLOGICAL SURVEY, MASSACHUSETTS DISTRICT OFFICE
MASSACHUSETTS DEPT. OF ENVIRONMENTAL QUALITY ENGINEERING
CAPE COD PLANNING AND ECONOMIC DEVELOPMENT COMMISSION
SEPTEMBER 1988
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The Cape Cod Aquifer Management Project (CCAMP) was a two year
cooperative effort undertaken by the U.S. Environmental Protection Agency,
Region I; the U.S. Geological Survey, Massachusetts District Office; the
Massachusetts Department of Environmental Quality Engineering; and the Cape
Cod Planning and Economic Development Commission in the towns of Barnstable
and Eastham, Massachusetts. Its purpose was to investigate methods and
approaches to be utilized in a comprehensive resource-based ground water
protection program. Additional copies of this report and others published by
CCAMP are available from the National Technical Information Service,
Springfield. Virginia.
This document was published with funding made available through the
Environmental Protection Agency's Office of Ground Water Protection and Office
of Drinking Water. The contents may not necessarily reflect the policies or
decisions of these two offices. The document solely reflects the views of
CCAMP participants.
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TABLE OF CONTENTS
Section • Title
I. PROJECT CONCEPTION.
II. PROJECT DESCRIPTION 4
A. CIS Technology 4
B. Project Objectives 4
C. Organization 5
III. DATA ACQUISITION 6
A. Choosing Base Maps 6
B. Data Sources and Automation 8
C. Data and Map Verification 10
IV. SCENARIOS 14
V. LESSONS LEARNED -- RECOMMENDATIONS FOR FUTURE PROJECTS 25
VI. ASSESSMENT AND CONCLUSIONS 31
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LIST OF FIGURES
Number Title
1 Map of Cape Cod 3
2 Maps Used in the CIS Project ' 7
3 Data Coverages 9
4 Class V Underground Injection Wells 11
5 CIS Staff Requirements 12
6 Sixteen Proposed Scenarios 15
7 Outline of Scenarios Process 16
8 Screening for Potential Public Water-Supply Sites,
Eastham, MA 34
9 Screening for a Potential Stump Dump Site, Eastham, MA .... 35
10 Inter-town Management: Zoning and Landuse Across
Barnstable and Yarmouth Town Boundaries (A) 36
11 Inter-town Management: Zoning and Landuse Across
Barnstable and Yarmouth Town Boundaries (B) 37
12 Increase of Potential Risk to Public-Supply Wells
from Landuse Build-Out, Barnstable, MA 38
13 Landuse-Based Calculation of the Average Nitrate Load
to Ground Water Within the Zone of Contribution
Barnstable, MA 39
14 Assessing Risk to Ground Water Quality at Public
Water-Supply Sites from Underground Storage Tanks 40
15 Assessing Risk to Ground Water Quality at Public
Water-Supply Sites from Landfills 41
16 Zones of Contribution and Half Mile Buffers Around
Public Supply Wells 42
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DEMONSTRATION OF A GEOGRAPHIC INFORMATION SYSTEM
FOR GROUND WATER PROTECTION
I. PROJECT CONCEPTION
A Geographic Information System (GIS) is a computerized graphic system
with automated database management functions. This report summarizes the
application of GIS technology to the Cape Cod Aquifer Management Project
(CCAMP). This CCAMP's experience is described as are problems and resolutions
in data acquisition, scenarios devised to demonstrate various aspects of the
technology, and final recommendations and conclusions.
The Cape Cod Aquifer Management Project (CCAMP), was initiated by the
U.S. Environmental Protection Agency, the U.S. Geological Survey (USGS), the
Massachusetts Department of Environmental Quality Engineering (DEQE) and the
Cape Cod Planning and Economic Development Commission (CCPEDC) to develop an
integrated, resource-based approach to ground water management involving all
levels of government. The project, conducted from 1986 to 1988, involved a
detailed examination of the many threats to the ground water on Cape Cod and
the development of improved scientific methods for protection of the resource
from these threats. The institutional framework regulating these potential
threats was evaluated and recommendations for stronger protection programs
were made.
Much of the focus of concern in CCAMP was on accurately defining the
resource to be managed, identifying the activities which threaten the
integrity of the resource and thus need to be controlled, and developing the
appropriate means to implement effectively any management scenario. One of
the realizations stemming from this work was that although resource-based
ground water management strategies have increased public awareness of the
potential conflict between development and water resources protection, the
threat to public water supplies from existing and future land use activities
is still significant. Generally, regulatory programs are not designed to
manage existing activities in proximity to public supply wells according to
their threat to such wells. Although the information on which future land use
decisions are made is voluminous, it is incomplete and the impacts of land use
decisions on ground water are not easily predicted or easily displayed. There
is an increasing need to evaluate available environmental data quickly and
accurately to determine potential risks to public water supplies.
CCAMP found that risk assessment has seldom been performed by regulatory
and planning agencies in a comprehensive way. Part of the problem in
performing more sophisticated analyses is that the available data are often
not organized or integrated in a useful way. Much of the available mapped
data have been drafted manually at different scales and dates. Comparing
different maps, or updating them, is a cumbersome process. Tabular data such
as information on well characteristics, often lack good geographic location
data. Data collection by various agencies on similar threatening activities
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usually lacks common identifying features, such as identification numbers that
would allow them to be cross referenced or aggregated.
Recent innovations in computerized data management offer improvements
that could help overcome these problems. In particular, geographic
information systems (CIS) technology provides efficient data handling,
manipulation, and display capabilities that facilitate the analysis of large
amounts of spatially referenced environmental data. It has the capability for
overlaying various mapped data layers, determining distances from fixed
points, automatic changing of map scales, and preparing maps from tabular
point data. Its presentation is graphically clear, resulting in a more
thorough understanding of the complex issues and consequently better decision
making.
The agencies involved in CCAMP decided that it would be desirable to
demonstrate the usefulness of CIS technology for these applications and to
evaluate the problems which might arise in using it. Accordingly, CIS was
used for a series of pilot analyses for Cape Cod. The work concentrated on
the development of a digital database and assessment at three different
geographic levels of analysis:. 1) the zone of contribution to nine public
water-supply wells in a highly urbanized area, 2) a rural, seasonally
populated, summer tourist town, and 3) the Cape Cod peninsula. Figure 1
provides a map of the Cape Cod area. The project was designed to raise issues
and answer the types of ground water management questions being asked on Cape
Cod, but also those faced by ground water managers in other areas of the
country as well.
CCAMP participants were especially interested in the ability of CIS to
incorporate a resource-based approach into a comprehensive ground water
analysis, that is; its capability to assess changes in risk associated with
the protection of the most vulnerable ground water resource areas. CCAMP
defined this area to be synonymous with zones of contribution (ZOC) to public
water supply wells, defined as that area of land surrounding a pumped well
under which water moves towards it and directly contributes to the water
withdrawn. Within these ZOCs, any contamination from the land surface which
travels through the soil to the water table and travels with the ground water
will reach the well. Only in areas dependent on private wells are individual
ZOCs not used to define the most vulnerable resource areas; instead the entire
area is considered at risk. This demonstration project was successful in
illustrating how CIS can improve the analyses required to implement a
resource-based approach to ground water management.
One of the many applications of this technology in which CCAMP was
particularly interested was the assessment of risk to water-supply wells from
potential contamination sources. It is possible to rank the priority for
clean up or to conduct a detailed assessment of various waste sources, such as
hazardous waste sites or landfills, basrd on multiple environmental features.
Site assessment studies to determine the most desirable locations for new
resource uses (such as public supply well sites) or for new facilities with
contamination potential are also greatly facilitated with this technology.
These applications were also demonstrated as part of the project.
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LOCATIONS OF AREAS OF STUDY
Barnstable
E a s t h am
Zone I
Figure 1
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II. PROJECT DESCRIPTION
This section first briefly reviews the basic methodology of CIS. It then
explains CCAMP's objectives with respect to the use of GlS technology.
Finally, the organization of the team responsible for the CIS demonstration
project is described.
A. CIS Technology
Geographic information system technology is unique in that it integrates
computer graphic capabilities with an automated database management system.
Historically, these computer functions and capabilities have existed
independently; CIS brings together both tools.
CIS is designed to permit users to display data comprised of points,
lines, and polygons which are fundamental to spatial relationships. It also
allows descriptive data values attributed to the graphic information to be
compiled and manipulated. It has the capability to apply a wide range of
analytic techniques including overlaying.graphically displayed data layers,
displaying the results of mathematical formulations used to describe physical
relationships, and compiling and translating graphically displayed information
into tabular form. Maps of different scales may be digitized and CIS can
enlarge or reduce them so that they may be overlaid. CIS may be used
interactively, a feature which is especially important for planning exercises.
Decision makers are able to sit at the terminal and ask 'what if...' questions
of the computer and observe the solutions to these questions almost
instantaneously. In the same way, projects may go through an iterative
process of refinement with minimal additional effort.
The CCAMP CIS effort utilized the ARC/INFO CIS software package developed
by Environmental Systems Research Institute (Redlands, CA). The ARC portion
of the package maintains the spatial location of map features such as lines,
points, and polygons, while the INFO portion stores and processes an unlimited
amount of attribute information which describes these features. The ARC/INFO
software was used on a Prime 9955 mini-mainframe computer at the Water
Resources Division of the USGS.
B. Project Objectives
The primary project objective was to demonstrate the usefulness of CIS
technology in assessing risk to public water-supply wells from different types
of contaminants. This included an assessment of the impact from existing
sources of contamination in proximity to the wells, as well as facility siting
to minimize future risks to wells. An integral component of this
demonstration was an evaluation of the data requirements necessary to utilize
CIS. Project participants also felt it important to undertake the project
with existing facilities and staff in order to demonstrate the ability of
other interested parties to employ CIS technology within their agencies.
Consequently, an existing computer system was utilized, agency staff were
trained and provided in-kind service to the project; no contract funds were
used.
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The focus of the project was on the analytic capabilities of CIS, not on
data collection efforts. For the most part, existing data bases were utilized
and there were minimal new data collection efforts. (Prior efforts in CCAMP
concentrated on data collection.) Data gaps were noted, but were not
generally filled unless the missing information was deemed essential.
Scenarios were developed to illustrate the various capabilities of CIS and
were specifically designed to:
1) Illustrate the ways in which data on a variety of factors,
such as hydrologic, geologic, land use, and environmental
conditions, could be integrated;
2) Illustrate spatial relationships between wells, land uses,
and contaminant sources;
3) Analyze the risk posed from these activities;
4) Develop management approaches based on risk assessments;
5) Compile a comprehensive database from a variety of
existing sources; and
6) Document problem areas in applying this technology
including assessing accuracy and completeness of data as
well as difficulties which arose in data manipulation.
The final purpose, in keeping with the 'demonstration' nature of the
project, was to design the project in such a way that the results could be
transferable to others interested in the application of CIS technology to
ground water management issues.
C. Organization
A cooperative team including members from each of the CCAMP participating
agencies was responsible for the CIS demonstration project. The team was
comprised of technical, scientific, and management personnel. Computer
technicians, hydrogeologists, and planners all played integral, but different,
roles in the project. U.S. Geological Survey computer facilities were used
and the Geological Survey staff contributed expertise in operation of the CIS
system. This included digitizing maps, inputting attribute data, generating
appropriate graphical displays of the analytic scenarios, and training others
to assist in these tasks. EPA and Massachusetts DEQE provided technical staff
with an understanding of data management issues who were responsible for
working with the CIS system as well as evaluating and verifying the data,
identifying gaps, and discrepancies. Management staff from these agencies
helped to identify important data coverages. They also supported
conceptualization, development and, interpretation of risk management
scenarios. There was a great deal of interaction between all of the
participants and also with other CCAMP work groups in undertaking each of
these tasks.
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Throughout the previous year, CCAMP had been involved in an extensive
land use study for one zone of contribution within the Town of Barnstable. A
great deal of data on potential contaminant sources were collected and
existing hydrogeologic maps were refined as part of this study. This became
the basis for the CIS effort and many of the same people were involved in both
projects, creating an important sense of continuity.
III. DATA ACQUISITION
Data acquisition was a major element of CCAMP's CIS project. This
section presents the project's approach to obtaining base maps and for
compiling and verifying the data associated with ground water management.
A. Choosing Base Maps
The first step in initiating the project was to obtain base maps of the
three areas of analysis: Cape Cod, the Town of Eastham, and Zone of
Contribution (ZOC #1) in Barnstable. Because ZOC #1 includes portions of both
the towns of Barnstable and Yarmouth, two different base maps of comparable
detail were needed to cover this area. Considerations in choosing base maps
included scale, accuracy, level of detail, currency, and consistency with
other town information.
As demonstrated by Figure 2, it was not always possible to find
consistent, good quality maps based on these criteria. The base maps and
feature maps came from a variety of sources, were of various scales, were
created at different times, and were both digital and nondigital. The reasons
for these variations are important. The towns of Barnstable and Eastham are
at different levels of sophistication in terms of mapping. Most maps produced
and maintained by the towns were created for informational or thematic
purposes for a specific project or study. In addition, each town has
developed its own type of base map and the detail reflects the level of
analysis needed to make a decision or undertake a project.
The map of the Barnstable ZOC, including portions of Barnstable and
Yarmouth, required the most detailed level of analysis. Because a substantial
amount of attribute data stored in the INFO portion of ARC/INFO was referenced
to individual parcels, it was important to choose a base map that could
support the same level of detail. Consequently, town tax assessor maps
outlining each land parcel were chosen as base maps. However, these maps were
not geographically referenced nor were the individual parcels drafted with any
degree of consistency or accuracy. The end result was the creation of a
picture of the area, not a map. It was a useful picture for most of the data
related to map and parcel, although it was not possible to locate specific
activities within a large parcel.
The second level of analysis was at the town level. Again, town base
maps were chosen according to their accuracy, scale, and ability to conform
with other data layers. Generally, USGS topographic maps were utilized as
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FIGURE 2
MAPS USED IN THE CIS PROJECT
MAP
CAPEWIDE
Coastline
Primary transport
Water Contours
Ground-water flow
Town boundaries
Cape ZOCs
Waste sources
Geographic names
BARNSTABLE/
EASTHAM
FINDS (Barnstable)
Wetlands (Eastham)
Zoning
Town owned land
Commercial land
Eastham water
quality
ZOC #1
Assessor maps
SOURCE
uses
USGS/MADPW
USGS/EPA
USGS/EPA
uses
CCPEDC
DEQE
uses
EPA
DEQE
town
town
town
town
Barnstable
Yarmouth
YEAR
1987
1985
1979
1979
1987
Unknown
1985
NA
1986
1984
1960
unknown
unknown
1984-86
1986
1980
(app
SCALE
1:25,000
1:190,000
1:48,000
1:48,000
1:25,000
1:48,000
1:25,000
NA
1:25,000
1:5,000
unknown
1:20,000
1:3,600
1:3,600
1:7,200
unknown
. 1:5,000)
FORMAT
Line/digital
Line/digital
Line/paper
Line/paper
Polygon/digital
Polygon/paper
Point/digital
NA
Point/digital
Polygon/orthophot
Polygon/paper
Polygon/paper
Polygon/paper
Polygon/paper
Polygon/mylar
Polygon/paper
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base maps. Other town maps, including zoning maps, were not geographically
referenced and did not represent a cartographically accurate view of the area.
The final level of analysis, the cape-wide maps, were the easiest to obtain
and digitize, and generally most accurate. The cape-wide base maps were
acquired from the Boston USGS office in digital form. Some of the other large
scale databases, especially the waste source data, contained locational
errors; while the obvious errors, such as landfills in the ocean were
corrected, these data were not field verified for accuracy.
The maps for this project came from a variety of sources and considerable
time was spent evaluating them. Other CIS users undertaking ground water
analyses should expect to spend considerable effort matching maps of different
scales and evaluating the accuracy and appropriateness of various maps.
Certain cartographic issues that consistently arose in this CCAMP project
should be considered by other CIS users. These include:
• Maps that are not geographically referenced (that is, not
referenced to a true location on the ground, such as a
latitude-longitude coordinate);
• Maps of various scales and resolutions;
• Maps from various sources;
• Maps in poor physical condition (for example, maps that
are folded, wrinkled, or torn); and
• Maps that are out of date.
CCAMP elected to utilize available maps in order to minimize data collection
time. Others who are investing in the long term use of CIS may choose not to
compromise data quality by utilizing maps which are of poor cartographic
quality and may instead wish to spend additional effort in obtaining or
creating high quality maps.
B. Data Sources and Automation
The attribute data compiled and utilized for the CIS project were
gathered through field investigations and from local and state program files.
Refer to Figure 3 for a full list of data sources utilized in this project. A
major portion of the attribute data for Barnstable was brought together as
part of a land use study in the Barnstable Zone of Contribution #1 undertaken
by CCAMP prior to the CIS effort. (See Gallagher, T., Steppacher, L. , The
Management of Toxic and Hazardous Materials in a Zone of Contribution on Cape
Cod, Proceedings of the National Water Well Association FOCUS Conference,
1987, Burlington, VT). As part of the land use study, field surveys of the
ZOC were made in order to identify the location, land use, and occupant name
of each parcel. Their data were then used as a basis to index other
information. Additional field surveys and interviews were undertaken to
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FIGDRE 3
DATA COVERAGES AND SOURCES*
DATA
SOURCE
COMMENT
POINT COVERAGES
underground storage tanks DPS/FDs
question 4/21E sites DEQE
public water-supply wells DEQE
large private water supplies EPA/DEQE
waste sources DEQE
FINDS EPA
local water quality data CCPEDC
municipal sewage disposal discharge USGS
right to know data DEQE
public water-supply test sites DEQE
small quantity generators DEQE
SPOT DEQE
geographic names USGS
toxic and haz. material storers BHD
class V underground injection wells EPA/DEQE
LINE COVERAGES
primary transportation routes USGS
water table contours USGS/EPA
ground water flow paths USGS
town boundaries USGS
wetlands USGS
'DRASTIC' contours EPA
bear ZOCs(ard. indiv. public wells) USGS
Cape Cod National Seashore USGS
POLYGON (AREA"> COVERAGES
Barnstable ZOC CCPEDC
Town of Eastham CCPEDC
parcel maps/land use CCPEDC
coastline USGS
public water-supply service area CCPEDC
Cape Cod ZOCs CCPEDC
sewered service areas Barn
landfills DEQE
USGS quadrangles USGS
zoning Barn/Eham
town owned land E'ham
FOR ANALYSIS
CCAMP nitrate model USGS
E'ham only,non-community wells
E'ham only, private wells
Barnstable WWTP
cape-wide,validity questioned
field survey, Barn ZOC only
cape-wide(1:48000),Barn ZOC
cape-wide(1:48000),Barn ZOC
cape-wide(1:25000)
Eastham only
Barn ZOC, results inconclusive
Eastham
cape-wide (1:190000)
Barnstable ZOC
cape-wide
* DPS-Dept. of Public Safety, FD-local fire dept., BHD-Barnstable Health Dept.
Barn - Barnstable, E'ham - Eastham
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identify potential underground injection wells may inject wastes into the
ground water.
Other data in potential contaminant source including underground storage
tanks, toxic and hazardous material storers and disposers, small quantity
generators and ground water discharge permittees were then gathered from local
and state files maintained in conjunction with the relevant regulatory program-
files . These data gathering efforts led to a fairly complete illustration of
the potential threats facing each parcel of land within the ZOC. Figure 4
presents an example of the results of data gathering efforts for one potential
source of contamination - Class V underground injection wells. Class V wells
are defined in the Safe Drinking Water Act and include, but are not limited to,
floordrains, large septic systems, agricultural drainage wells, stormwater
runoff wells). Similar maps for each source were developed.
The resulting databases contained a great deal of information. For
example, the databases identified location and name of each small quantity
generator and specified the type and quantity of waste hauled. For each
injection well, the database identified the type of well and what material was
being injected. This information helped to determine the appropriateness of
various management schemes, such as cooperative waste hauling of similar
commercial/industrial activities within a certain geographic area. Not all of
these data were applied within this demonstration CIS effort, although it
would be appropriate to utilize more of it in the future for additional
analyses.
None of the data obtained through the land use study were originally
automated. Most were found on paper files stored in offices and seldom used.
As part of the land use study, land parcels and related attributes as well as
potential contaminant source inventories, were put on DBASE III files. These
files were translated into a readable form for the CIS.
Additional data layers were employed for the town and cape-wide CIS
analyses. Most of these were taken from state compilations which included
hazardous waste sites, landfills, and public water supplies. These were also
paper files and were input directly into the CIS. The primary difficulties in
gathering these data were: 1) the data were stored in a variety of locations
and was inconsistently maintained; 2) retrieval was difficult because the data
were kept on paper files; and 3) many databases were incomplete and not up to
date. Figure 5 estimates the time required to undertake the data gathering
portion of the project.
C. Data and Map Verification
Computer operators and users of computer generated products recognize the
potential problems arising from use of imperfect data and the challenges to
the integrity of analyses resulting fr ,m incorrect data. CCAMP participants
were also aware of these issues prior to commencing the CIS project and
developed a data verification approach to address these issues. The
sophisticated presentation which the CIS technology is able to make creates a
sense of certainty in the information displayed. For this reason, it is
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POTENTIAL UIC CLASS V WELLS
AND PUBLIC WATER SUPPLY WELLS
IN THE BARNSTABLE ZONE OF CONTRIBUTION
EXPLANATION
AUTO SERVICE STATION
DISPOSAL WELLS
INDUSTRIAL PROCESS WATER
AND WASTE DISPOSAL WELLS
INDUSTRIAL DRAINAGE WELLS
DOMESTIC WASTEWATER
DISPOSAL WELLS
PARCELS
ZOC
Figure 4
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CIS Project Elements/
Staff Analysis
Staff Responsibilities
and Duties
FIGURE 5
CIS STAFF HEQDIEEtmS
Skills Required
and Training Heeds
Time Coomitment
(Han-days)
Comments
Data Gathering and Validating
Data Automation
Date Verification
Data Analysis and Scenario
Flaying
Windshield survey in field
CD site visits to local and
state program offices
Compilation of varied
databases
Inspection of UIC wells
Digitizing maps
Automating attribute files
(tables and spreadsheets)
Editing
Check maps against field
surveys, other maps
Proof automated data, check
against other data layers
Circulate data to program
persons
Storybook step by step
presentation
Iterative refinements
Review of plots
Presentations for comments
Understanding of whole 32 man-days
project, i.e., final data
requirements, available
data sources
Digitizing skills 60 man-days
Training in ARC/INFO
software and HUM! hardware
Data transfer between PC
and mainframe computer
Knowledge
Time
of the field area 75 man-days
Understanding of GIS
Understanding of ground
water concerns
Understanding of risk
ARCIHFO training
Strong scientific support
for scenarios
40 man-days (does not include
input from steering
committee)
Time may be under estimated
because CCAMP had
established cooperation
with local offices
providing data
Each participant should
have introductory training
on computer and the
software
Include wider diversity of
people early in process
Refine scenarios during
data gathering stages
to
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extremely important to support this conceptual security with truly accurate
data.
Data verification issues are two-fold: first, one must determine if the
data are accurate and truthful; second, one must determine whether the data
have been automated without mistakes. The latter requires the time consuming
and cumbersome task of checking each data entry with its original, plotting
maps to scale, and overlaying with originals and checking for typographical
errors. The most difficult aspect of this task in the CCAMP project was
ensuring that the more than 1,900 land parcels and related land use
identification numbers were correctly located. This accuracy was crucial
because it was the base on which many other data layers depended.
The importance of this task, however, was overshadowed by the critical
need to ensure that all the data within the CIS were accurate. Ideally, each
data file would be verified in the field. If this is not possible, the data
should be verified, at best, against a similar file maintained by another
entity. This was not always possible in the CCAMP study because of limited
time and resources. CCAMP depended on the specific knowledge of project
participants and draft plots of data coverages which were reviewed by project
managers from whom the data was obtained.
Whenever possible, critical information were cross-checked against other
easily accessible data. This approach worked well in Barnstable where local
agencies had been involved in collecting data on municipal wells, landfills,
and small quantity generators which could be compared to similar state data
bases. This was far more difficult in Eastham which does not have the
manpower to maintain a similar database at the local level and does not
believe their problems justify the commitment needed to develop such a
database. Consequently, the state data was assumed to be correct in this
case. Numerous discrepancies were identified and corrected through these
processes. However, without field checks and more extensive verification, it
was difficult to assure the total accuracy of the database. It seemed that a
verification process was never pursued in a systematic manner, and errors were
uncovered throughout the project.
There were numerous other difficulties encountered in verifying data and
maps. One such difficulty was that the accuracy and completeness of the maps
and data files varied greatly. For example, the local fire department
supplied well organized, up to date records on underground storage tank
information. They were also very knowledgeable of the local area and
cooperative to CCAMP participants, assuring a complete database. However,
other files provided to CCAMP were incomplete, out of date, and poorly
organized. Many were of such poor quality that it was difficult to read them.
Additionally, activity locations were "Xed" on large scale maps, sketches, or
plans providing only a general idea of the actual location.
The overriding reason for poor quality files appeared to be that program
files were seldom used by analysts or decision makers in other programs.
Similar data gathering efforts are often undertaken simultaneously by various
programs or agencies for specific purposes. Unfortunately, CCAMP found that
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inconsistent data were being maintained by different agencies. It was nearly
impossible to resolve these problems without field verification.
One response to the variability in data quality was to develop a data
dictionary. This is a compendium of each data source containing information,
for example, on where it is housed, the purpose for which it is gathered, who
gathered it, who maintains it, the medium (paper or automated), and the scale.
While this did not solve inconsistencies or correct data problems, it clearly
identified the important 'vital statistics' needed to evaluate data sources
against each other, assessed their applicability to the project and identified
a contact person if any questions arose regarding the database. It is
recommended that any CIS project should maintain a similar data dictionary,
especially long term projects with a multitude of databases.
IV. SCENARIOS
The emphasis of the demonstration project soon changed from a data
gathering/inputting/verifying process to analysis and' evaluation. This shift
reemphasized what had been learned; the data could use many further
improvements, and if it were to be used as the basis for policy decisions,
further verification would certainly be required. Because this project had
been initiated to identify the applicability of the technology, noting any
shortcomings it may have, the data were employed to demonstrate the usefulness
of the technology without additional verification beyond that already
described.
Knowing the data available and applying their own understanding of ground
water management issues, each team member developed one or more 'scenarios'.
A scenario for the purpose of CCAMP, was defined as a process of overlaying
and displaying various geographic data while interpreting and analyzing the
relevant attribute data in order to illustrate some aspect of the risk related
issues. These scenarios were reviewed and prioritized by the team.
Prioritization was based on both the perceived need for the analysis and an
assessment of how well CIS could display the issue. There was an initial bias
to work on scenarios which would best demonstrate the mapping and analytic
capabilities of CIS.
Sixteen scenarios were initially proposed as listed on page 15, Figure 6.
While these scenarios illustrate the wide range of possible analyses which
could be undertaken with the data available, eight of these scenarios were
chosen for in-depth work. The eight selected scenarios address issues such as
siting of contaminant threats to reduce risk, setting of priorities for
cleanup activities, and management of existing activities that may threaten
ground water. Additionally, the eight scenarios address important issues
currently being discussed within the towns and the state. The next section
presents each of" the scenarios. The purpose of each scenario is presented
first and is followed by a brief summary of the conclusion and the use of CIS.
Following Figure 6, Figure 7 explains the specific steps taken in each
selected scenario to arrive at the final map. A copy of each of the final
maps may be found at the conclusion of this report.
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FIGURE 6
SIXTEEN PROPOSED MANAGEMENT SCENARIOS
Identify future public supply well sites for Eastham and determine zones
of contribution for these wells.
Identify stump dump/demolition waste sites for Eastham which will
minimize threats to ground water.
Model future nitrate levels in supply wells resulting from saturation
development at current zoning and impacts of revised zoning.
Design an effective monitoring network to protect against existing
hazards.
Determine comparative risk of contamination of public supply wells from
existing contamination sources (underground storage tanks, toxic and
hazardous materials, etc.)
Examine risk from underground storage tanks by looking at age, capacity,
location, etc.
Determine land use management/growth scenario in Eastham that protects
private well water quality.
Identify appropriate sites for high risk activities.
Perform a risk/threat analysis of hazardous waste sites and water
supplies.
Assess zoning/growth/land use issues in zones of contribution that cross
town boundaries.
Assess implementation of local, state, and federal toxic and hazardous
materials regulations.
Examine transportation of hazardous substances in relation to public
water-supplies. -
Determine priority areas for sewering.
Develop cape-wide map of zones of contribution and major waste sites.
Examine effects of 400 foot protection radius versus 2000 foot.
Examine contaminant transport/protection distances.
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F1UUKK 7
Scenario
OF SCHUBIO ROCESS
GIS Steps
Reason for Step
1. Identify a site for a
1 MGD water-supply in
Eastham
1. Base map of Eastham
2. Identify commercial properties and
place a 400 foot radius around
them.
3. Buffer Rt. 6 with 400 feet.
4. Buffer all ponds and wetlands with
ISO feet.
5. Identify all town owned parcels of
at least five acres.
6. Eliminate town parcels within the
Nation Seashore.
7. Identify all private wells.
(optional)
8. Delineate assumed zone of
contribution and the newly
required half mile radius.
(optional)
FINAL RESULT: Map of Eastham
identifying assumed zone of
contribution (Figure 8)
Identify known potential threats to
water quality
Eliminate such areas from
consideration
Buffer distance based on DEQE
regulations
Eliminate from consideration based
on sensitivity of ground water
pumping impacts on surface water
Provide town with as much control
over land use as possible
National Seashore rejected location
of water-supply well within
boundaries. But note that Seashore
can provide protection front
development to adjacent properties.
Extra information. To identify
feasible areas for delivery system
and make preliminary cost estimates.
Compare protection afforded by state
policy versus actual contributing
area.
2. Identify a site for a
stump dump for Eastham
1. Base map of Eastham
2. Identify ccomercial properties,
ponds, wetlands, roads, and buffer
as in Scenario 1.
3. Identify and eliminate from
consideration National Seashore
property, residential properties,
proposed new water-supply zone of
contribution.
4. Identify town owned parcels over 5
acres.
S. Overlay water table contours and
flow directions.
6. Display parcels which are
potential sites for stump dump.
FINAL RESULT: Map of Eastham
identifying possible stump dump site
(Figure 9)
Buffer distance based on DEQE
regulations
Eliminate from consideration all
incompatible land uses
- Provide town with control over land.
Minimize pollution potential to
sensitive areas by placing dump down
gradient.
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Scenario
-17-
FIGOEE 7
rmT.liiH OF SCQURJO PROCESS
GIS Steps
Reason for Step
Barnstable Zone of
Contribution
3. Inter-town management
in Barnstable zone of
contribution
MAP 1
1. Zone of contribution outline.
2. Overlay individual zones of
contribution (Bear ZCCs)
3. Overlay zoning map
MAP 2
1. Outline of zone of contribution.
2. Overlay individual zone of
contribution.
3. Overlay existing land use map.
MAP 3
1. Overlay zoning and land use maps.
2. Compile percent of different land
use and zoning types in each tovn.
FINAL RESULT: Map of ZOC identifying
those parcels where land use is
different than zoning. (Figures 10
and 11)
Identify portions of individual
zones of contribution which cross
town lines.
Identify how zoning differs across
town lines.
- Identify how land is actually used.
- Identify land uses which threaten
water quality.
- Note conflicts across town lines.
Identify those areas where land use
is not in accordance with zoning to
be used to target attention.
Optional. To illustrate character
of town.
A. Implication of Full
Development in Barnstable
Zone of Contribution
MAP 1
1. Base map of ZOC.
2. Categorize land use into one of 15
groupings based on relative risk
posed to ground water.
3. Overlay categorized land uses.
MAP 2
1. Base map of ZOC
2. Assume all land with growth
potential is developed according
to existing zoning ordinance.
3. Overlay full development map on
ZOC.
4. Categorize each potential land use
according to risk, as defined
above.
Based on best professional judgment.
Aggregate over 100 land uses into IS
categories based on potential risk
to public water-supply.
Using various shadings, can identify
location and extent of risky
activities.
In high growth area with no zoning
changes this represents full
development.
Identify location and degree of
potential risk.
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Scenario
-18-
FIGDBE 7
OF SCQURIO EBOCESS
GIS Steps
Reason for Step
Scenario 4, continued
5. Calculate percent change in land
use type before and after full
development.
- Compare graphically and
analytically, risk posed presently
and from full development.
- Identify increased risk.
- Identify incompatible land uses and
zoning designations over tom lines.
FINAL RESULT: Two maps, first
identifying existing land uses colored
by risk posed, second identifying
ultimate development land uses also
colored by risk category. (Figure 12)
S. Application of
nitrate loading formula
within Bamstable ZOC
1. Base map of ZOC.
2. Categorize land uses into 8
groupings based on relative
nitrate contribution.
3. Assign values of nitrate generated
to each land use category.
4. Calculate number of parcels in
each category.
S. Apply equation for calculating
• total nitrate load.
6. Shade categories and plot on ZOC
map.
FINAL RESULT: ZOC map identifying
those parcels contributing to the
nitrate load. Accompanying map is a
chart indicating individual nitrate
loads used in the analysis. (Figure
13)
Categories -and values are based on
literature and included in report by
Frimpter, et. al.
6. Ranking of risk posed
by underground storage
tanks in Bamstable ZOC
1. Outline of individual ZOC
surrounding Maher Diesel Hells
(also called Bear ZOC).
2. Delineate time of travel contours.
3. Rank each tank according to six
attributes and sum rankings.
Because distance is an important
criteria, need to make assessment
from localized area.
Display graphically the distance
corresponding to time of contaminant
travel to well.
Distance, tank age, size, content,
construction material, urbanization
of area.
4. Categorize rankings into high,
medium, and low with corresponding
color scheme.
S. Plot tanks according to risk.
FINAL RESULT: Map of individual ZOC
with time of travel contours
identified and individual UST plotted
by color. (Figure 14)
To display relative risk posed by
each tank.
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Scenario
-19-
FIGORE 7
QF SCDtARIO IBOCESS
GIS Steps . . .
.Reason for Step
CAPE COD
7. Ranking of risk posed
by landfills on Cape Cod
1. Base map of Cape Cod with town
boundaries .
2. Overlay public supply well
locations and corresponding ZOC
delineations .
3. Overlay landfill locations.
4. Calculate distance of landfills
from ZOC and well.
5. Assign a weight to each landfill
attribute to be used in ranking.
6. Rank each landfill according to
seven weighted attributes and sum
ranking.
7. Categorize risk into high, medium,
and low and assign color related
scheme .
8.
Assign Appropriate risk category
to each landfill.
FINAL RESULT: Map of Cape Cod, all
ZOCs delineated and each landfill
plotted and color coded according to
risk. (Figure 15)
Distance from landfill to ZOC and
well is important factor in ranking
scheme.
Distance, also depth to water table,
liner, leachate collection system,
water table gradient, thickness of
overburden, nature of material.
Heights are based on professional
judgment.
- See ranking in Figure 14.
8. Assessment of policy
to management programs
based on 1/2 mile radius
around those wells
without delineated ZOC
1. Base map of Cape Cod town
boundaries.
2. Overlay public water-supply wells
and corresponding delineate ZOCs
3. Overlay calculated 1/2 mile radius
around each public supply wells.
FIHAL RESULT: Map of Cape Cod, all
ZOCs delineated and 1/2 mile radius
overlaid. (Figure 16)
Observe difference in area and
determine whether 1/2 mile radius
over or under protects the water
resource.
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TOWN OF EASTHAM
Scenario 1. Identify a site for development of a 1 nillion gallon per
day public water supply system to serve the Town of Eastham.
Purpose: The town of Eastham, rural and residential in character,
presently is served solely by private wells. There have been localized
incidents of ground water contamination due to the landfill, commercial
activity, and high nitrogen levels in densely populated areas. Because the
town is growing at a significant rate, increased activity could lead to a
greater risk to the private wells. In order to ensure the possible future
delivery of high quality water, an appropriate site suitable for a municipal
well, i.e., one which is hydrogeologically capable of producing 1 MGD and
which has minimal existing threats, should be located.
Conclusions/Applicability of CIS: Siting decisions are probably one of
the most commonly illustrated and convincing applications of CIS technology.
This scenario was able to identify all potential sites defined in this
scenario as town parcels over 5 acres. Utilizing a series of overlay maps,
existing incompatible activities in proximity to the sites were located. Any
site with adjacent incompatible activities was eliminated from further
consideration. Two sites were identified to be protected for future use.
Data requirements for this scenario were moderate; most of the data were
available from local town files. Perhaps the least reliable was the
hydrogeologic data used to identify zones of contribution to potential wells.
More site specific information will be required in future work on the
development of the water supply source.
Scenario 2. Identify a site for a stump dump for the Town of Eastham.
Purpose; In conjunction with the Scenario 1 analysis to identify a
public water supply well, the Town of Eastham requested that CCAMP undertake a
related investigation to locate an appropriate site for a stump dump." The
timing of the analysis has enabled Eastham to identify a stump dump site
which will be compatible with, or minimize the threat to, a drinking water
well.
Conclusion/Applicability of CIS: This analysis was very similar to that
undertaken for Scenario 1; a series of overlays were utilized to identify the
most appropriate location for a stump dump. Both hydrogeologic and land use
consideration were included in the analysis. CIS was able to assimilate the
data and display the conclusions effectively.
BARNSTABLE ZONE OF CONTRIBUTION
Scenario 3. Inter-town management issues within the Barnstable Zone of
Contribution.
Purpose: The Barnstable Zone of Contribution #1 illustrates that
hydrogeologic boundaries do not respect political jurisdictions; the ZOC
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straddles the town line between Barnstable and Yarmouth. Although water from
this ZOC serves the Town of Barnstable, land use activities in Yarmouth may
affect its quality and Yarmouth may not recognize this area of town as a high
priority for enforcement of town codes. This situation requires strong
channels of communication and cooperation (as was noted in other portions of
CCAMP project). The propose of this scenario is to graphically represent the
existing situation as well as the planned futures of the ZOC> based on current
zoning, and utilize this as a starting point for inter-town discussions.
Conclusion/Applicability of CIS: While the analysis itself was not
rigorous, the graphical representation generated clearly met the objectives of
the scenario. The maps were able to move a conceptual idea of the need for
inter-town management to a concrete starting point for discussion and
negotiation based on specifics. Because the land use data were available at
the parcel level, individual nonconforming uses could be identified and
targeted if required, for local enforcement efforts. In both towns, overall
development plans are not fully consistent with ground water protection. The
simple overlay of zoning on the ZOC map identified incompatible future land
uses and may be utilized to channel efforts at rezoning in both towns.
Although not utilized its full potential, CIS technology can be used
effectively in the capacity illustrated in this scenario. One limitation is
the amount of time required to accurately gather and digitize land use data by
parcel. If these two data layers were digitized solely to be used in this
scenario, it would have been more efficient to do the analysis manually, but
because these data layers were used frequently, CIS has the advantage over
manual mapping of generating additional maps easily and quickly.
Scenario 4. Identify potential risk to public water-supply veils from
complete planned future development.
Purpose: With the existing rate of growth on Cape Cod, some planners
believe that all allowable possible development will ultimately occur. A
zoning ordinance and map is not just a guide to the future in this situation,
but a map of what will occur. This 'build-out' analysis is not a projection
in that a time element is not included; it is an illustration of full growth,
at some unidentified future point in time. Portions of the Barnstable zone of
contribution are already developed and water purveyors are in the business of
managing existing risks. However, there are a number of large undeveloped and
partially developed parcels north of Route 6. These parcels (when developed)
could significantly increase the risk posed to the public supply wells.
In this scenario, a simple ranking of land uses and zoning categories
according to risk was developed. It was applied by assigning different shades
of color to different levels of risk, first to existing land uses and then to
potential development based on zoning. Differences between the map of risky
activities in the ZOC now and those which will be there in the future were
noted. The purpose was to present the consequences of taking no further
action to limit land uses in a zone of contribution.
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Conclusion/Applicabilitv of CIS: When full development is reached in
this ZOC, the water purveyors will be in the business of managing a high risk
potential public water-supply. Figure 11 clearly depicts the substantial
increase in risk resulting from development of many vacant parcels north of
Route 6 presently zoned industrial.
This kind of presentation, utilizing CIS map making abilities, can be a
strong tool in discussing with decision makers the need to consider rezoning.
Existing zoning can be altered slightly and the resulting decrease in
potential risk can be viewed. It is important to remember, however, that the
professional quality of the maps carries with it an appearance of certainty
that is not always there. When CCAMP presented this scenario, many
individuals believed that CCAMP was projecting that full development would
occur. It is important to title and qualify maps explicitly to reduce these
misunderstandings. The maps should be utilized as a catalyst for change.
Scenario 5. Application of predictive nitrate loading formula within
zone of contribution.
Purpose: A predictive nitrate loading formula was developed by a group
of hydrogeologists during an earlier phase of the CCAMP project. The formula
is based on a mass balance concept and assigns specific nitrate loads to a
multitude of land use activities. It is intended to be used in the planning
process to assess the incremental impact of a proposed development on the
nitrate concentration at the well. (See "Nitrate Loading in Municipal
Wellhead Areas" by M. Frimpter, J. Donahue, M. Rapacz, August, 1988 for a full
explanation and discussion).
Because CIS has analytic capabilities it was possible to program the
nitrate loading formula into the computer, assign loads to various activities,
and generate the load at the well. This then could be coupled with a
graphical display of the nitrate for different portions of the zone of
contribution. Decision makers could determine the load resulting from a
proposed development before approval of the development.
Conclusions/Applicability of CIS: The results of this scenario were
slightly compromised because the nitrate loading formula was designed to
predict the load within a ZOC surrounding one well. The Barnstable ZOC is a
composite including nine wells and it is not totally appropriate to apply the
formula in this case. It is difficult to ascertain the accuracy of the
application because of the complexities of pumping schemes and consequent
ground water flow between the individual wells.
Conceptually, however, the application was appropriate. Additionally, it
illustrated clearly the variable loads generated from specific parcels. With
more time, the formula could have been applied within each of the individual
ZOCs.
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Scenario 6. Ranking of risk from underground storage tanks (DST) to
public supply veils.
Purpose: An inventory of USTs within the Barnstable Zone of Contribution
identified 186 tanks on 82 sites. A number of facts and statistics had been
publicized pointing to the potential risk from UST. For example, it has been
noted that one gallon of gasoline could render 750,000 gallons of water
undrinkable (National Rural Water Association), and any tank over 20 years old
has a 57% chance of leaking (EPA). In this zone of contribution, all six of
the confirmed hazardous waste sites were due to petroleum contamination. The
purpose of this scenario was to illustrate a method using CIS to prioritize
management of USTs based on their relative risk to the public supply wells.
When the inventory was undertaken, additional information on each tank
was gathered, including age, size, contents, type of tank (e.g., steel or
fiberglass), and location. Utilizing CIS functions, the location of the UST
was translated into distance from a particular well. All these data were
employed as factors in a risk ranking scheme. Each tank was assigned points
for each factor which were summed arithmetically to assess overall risk posed
by each individual tank. This analysis was done for specific wells so the
distance factor could be accurately incorporated. The ranking schemes are
presented with the map at the back of this report.
Conclusion/Applicability of CIS: This was perhaps one of the more
rigorous scenarios in terms of the ability of the science to keep pace with
the technology. Even within CCAMP, there were disagreements on the ranking
scheme, and if it had been shown to a panel of experts, several differences of
opinion about the method of ranking risk to the well could be expected. Very
few studies support the specific categories which distinguish high, medium,
and low risk tanks. Additionally, it is difficult to scientifically ascertain
the relative contribution of one factor over another to overall risk.
However, the CIS technology was able to demonstrate an approach to risk
assessment which utilized both analytic and geographic factors in a
coordinated way.
In situations like this, where the science supporting the analysis is
uncertain, CIS is well suited. It is possible to run and rerun the scenario,
each time changing the assumptions on which the scenario is based.
Additionally, CIS makes it easy to undertake sensitivity analyses of each of
the variables contributing to the risk factor by weighting them in various
ways and observing the changes in results. The CCAMP project did not spend
sufficient time on this portion of the analysis.
Data quality issues were also extremely important to the integrity of
this scenario. This was the first scenario which employed contaminant source
data gathered from local and state sources of data (See Gallagher, T.,
Steppacher, L., 1987, for discussion of inventory, sources of data, and
quality issues). The data were available as the result of a new state law and
new reporting requirements. Most of the information was handwritten on forms
and submitted to the local fire department. It was copied by CCAMP
participants and transferred to a DBASE file. Although there was a large
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effort to verify data, there were many places for error beyond the control of
CCAMP. For example, the one tank which was perceived to pose the greatest
risk, in actuality was an above ground tank, but that fact was not indicated
in the files.
CAPE COD
Scenario 7. Prioritization of landfills for clean up based on threat to
public water-supplies.
Purpose: The State of Massachusetts is presently in the position of
enforcing regulations at active landfills and managing the closure of others,
with resources far too small to adequately do the job in a timely fashion.
Cleanup activities, therefore, must be prioritized. Because landfills are a
major threat to ground water quality, it is appropriate to examine individual
features of each landfill and prioritize their management based on the level
of threat they present.
This scenario, like Scenario 6, develops a ranking scheme based on seven
factors which may affect the likelihood that a landfill will threaten ground
water, specifically drinking water. Many of the ranking factors are also used
in the LaGrand Ranking methodology, including depth to water table, water
table gradient, and the nature and thickness of unconsolidated material.
Additional factors included size, presence or absence of a liner, and presence
or absence of a leachate collection system. Distance to public water
supplies, both in and outside zones of contribution, was also incorporated and
weighted heavily; distance was considered the major factor influencing
potential contamination. In fact, any landfill located within a zone of
contribution automatically was placed in the moderate-high or high risk
category. The sum of the weighted ranks was determined by multiplying each
attribute rank by that attribute's weighting factor to get a weighted rank.
Then the weighted ranks are summed for each landfill. The weighted rankings
are presented with the map at the back of the report.
Conclusion/Applicability of CIS: As the previous scenario provided
insight for UST within a single wellhead protection area, this scenario
utilizes a similar approach in a larger region in order to set priorities
within a state regulatory program. Together these scenarios illustrate the
suitability of CIS to environmental priority setting based on risk. CIS
proved to be very capable of compiling extensive data on a large number of
individual facilities and applying a standardized evaluation tool to each
facility in order to estimate comparative risk. Again, the ranking scheme may
not meet the expectations of all scientists and/or analysts; although the
LaGrand ranking scheme has undergone professional review and has been employed
in a variety of settings.
Data on each landfill were quite easily obtained from the DEQE. Much of
it was reported to the State as part of the landfill permitting process. The
geographic location of each landfill was the most difficult information to
gather and required extensive scrutiny. Because the distance factor was
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weighted heavily in the ranking scheme, the accuracy of these locations was
critical.
Scenario 8. Implications of a one-half mile radius around a well versus
a delineated zone of contribution.
Purpose: To implement some of the institutional recommendations CCAMP
had proposed, DEQE wanted to incorporate a resource-based approach to a wide
range of regulatory programs. That would mean that program activities
designed to protect ground water resources would have a higher priority within
ZOCs, the most vulnerable resource area. Because a large number of public
water-supplies did not have ZOCs delineated, the state was considering
adopting a policy which assumed a one half mile radius around these public
water-supply wells.
On Cape Cod, all ZOCs have been delineated so that a graphic overlay of
these ZOCs and a one half mile radius could illustrate the different land
areas which could be affected and determine the suitability of the policy in
meeting the goal of protecting ground water.
Conclusion/Applicability of CIS: A graphical display of this type
illustrates the applicability of CIS to planning and policy decision making.
CIS enabled DEQE to examine the differences between a scientifically derived
ZOC and one created through a policy decision. It also could calculate the
affected land area in each situation. The graphic display illustrated that a
one half mile radius is conservative downgradient of the well and not as
conservative upgradient. However, on Cape Cod the one half mile radius was
consistently smaller than the delineated ZOC. This is due to the sandy soils
and high transmissivities on Cape Cod. Again, the CIS could have been well
utilized in performing sensitivity analyses of various sized radii.
V. LESSONS LEARNED -- RECOMMENDATIONS FOR FUTURE CIS PROJECTS
Because the project was designed to be a demonstration, very careful
notes were made of the process undertaken, problems encountered, and future
needs so that others could benefit from CCAMP's experiences. The following.
section highlights the major project findings and recommendations based on
these experiences. While supporting evidence is included so that this section
may be read independently, it is best understood in the context of the
complete report. This is especially true of the data related recommendations.
The range of issues related to data are fully explained in the data sections.
1: Identification of Project: Goals
Recommendation: Project goals and objectives must be clearly identified
and a project design detailed so that specific needs are identified before the
project begins. Included in this should be an evaluation of data quality and
base map quality. Data quality may dictate the feasibility of meeting certain
objectives.
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Supporting Evidence: The CCAMP project's objectives were not always
specific enough to direct data gathering efforts. Frequently, data layers
were gathered and digitized because they were available and in a usable form,
not because of the need for them in the analytic phase of the project.
Because the scenarios were not developed at the beginning of the project, they
did not guide data collection efforts. Instead, available data dictated the
level of analysis possible in certain scenarios.
Because specific needs were not clearly defined and data requirements not
thoroughly understood, CCAMP underestimated the time commitment needed for
developing the data into a usable form. An initial evaluation of data quality
would have kept project participants from investing a great deal of time in
automating a database which was not accurate and ultimately was not critical
in any scenario.
2: Data Quality
Recommendation: Since the quality of CIS products and analyses depends
on the quality of the data a CIS is built from, it is essential to choose high
quality data sources. All data to be used in a CIS should be adequately
referenced by a legitimate geographic coordinate system. For tabular
spreadsheet data sets, this means that each data point (well, UST, waste site)
should be referenced by a pair of x-y coordinates such as latitude-longitude.
For mapped data, this means that the map should be a legitimate cartographic
projection referenced by a coordinate system such as latitude-longitude.
Source maps should also be in good physical condition (not wrinkled or torn)
and on a scale-stable medium such as mylar.
In addition, any CIS project team should include a person who has
knowledge of basic cartographic and geographic principles such as projection,
scale, and coordinate systems.
Supporting Evidence: With the exception of U.S. Geological Survey 7.5
minute quadrangle maps and Massachusetts Department of Public Works highway
maps, most of the source maps used in this project were either lacking in
cartographic quality, in poor physical condition, or both. While these maps
were appropriate for their initial purposes, they did not contain the ideal
qualities of source maps for a CIS.
The base map for the Barnstable zone of contribution, the town tax
assessor's parcel map, was not in a legitimate cartographic projection or
coordinate system. Parcels were represented schematically; they were not tied
to ground-accurate positions and were not accurately represented in size or
dimension. Therefore, a number of contaminant source databases, such as the
Facility Index Data System (FINDS) which were correctly referenced by latitude
and longitude, and a number of data layers such as roads and town boundaries
which were taken from good cartographic bases, did not precisely overlay the
inaccurate parcel base map.
Likewise, not all tabular data sets contained proper location
coordinates. Some data point locations were addresses, others were parcel
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numbers, neither of which can be translated into a precise x-y
(latitude-longitude) coordinate position. For example, USTs were located by
parcel number only; for a tank to be located in a large parcel such as the
Barnstable Airport is highly inaccurate.
3: Use of Digitized Data
Recommendation: Any agency or person collecting data should make the
effort to collect and store its data in digital form. Agencies should be
encouraged to take the initiative to automate their data from the start so
that it is readily available for use in a CIS or other computer based
application. As far as possible, all databases should be automated before
being used as part of a CIS project.
Supporting Evidence: Data related aspects of CIS can be so time
consuming that it is not efficient to use staff time to automate paper files.
In the CCAMP project file automation distracted personnel from the focus of
the project. If certain databases are critical, they should be identified
during the planning phases and automated before the project begins.
Additionally, data that exist merely on sheets of paper are drastically
limited in their applicability, their ability to be shared or transferred to
other agencies, and in their ability to be maintained and kept current.
4: Master Version of Data Set
Recommendation: A master version of every data set should be maintained
by one person, or one person should be responsible for the status of the data.
Supporting Evidence: In the CCAMP project, a team of people were
responsible for the development and maintenance of data. Frequently, there
were numerous versions of the same database in existence at one time on
different computers. This led to some confusion, because various people made
revisions or updates that were not replicated in each version of the data set.
5: Data Dictionary
Recommendation: Vital statistics on the databases should be kept in a
'data dictionary'. It should include the data source, format, medium (paper,
mylar, automated), most recent update, level of accuracy, and contact person.
The data dictionary should also indicate how each data layer is intended to be
used and its limitations.
Supporting Evidence: A data dictionary was developed part way through
the project and helped to document where the data were obtained and by whom
and in what form. The data dictionary provided a good reference for the
scenario conclusions as they are presented to decision makers. Frequently,
the validity of the data may be questioned and the dictionary provides full
details on each data source. Additionally, for an ongoing CIS effort, the
data dictionary may be used as an index to the system and may be utilized to
guide analyses.
-------
-28-
6: Data Conventions
Recommendation: The State of Massachusetts should further encourage
development of data conventions and support the construction of highly
accurate statewide databases. Other states should develop data standards,
including field verification, to be used by state and local agencies involved
in data collection.
Of note is that the Massachusetts Executive Office of Environmental
Affairs has established a base scale of 1:25,000 for the Massachusetts
statewide database now under construction, and has committed to the National
Map Accuracy Standards adhered to on the U.S. Geological Survey 7.5 minute
quadrangles which are the base maps for the Massachusetts CIS database.
Supporting Evidence: Data quality standards help to assure a certain
level of accuracy in the data used in a CIS project. These standards should
help to determine how the data can be used and the degree of reliance to be
placed on the analyses utilizing these data. Data standards include guidance
on the acceptable sources and format of data guidelines regarding verification
of data.
7: Large Scale Maps
Recommendation: The state should encourage and support development of
larger scale (i.e., local level) databases, in particular parcel maps that are
of good cartographic quality.
Supporting Evidence: Parcel maps provide the most detailed land use
information on the level at which zoning, resource protection, and other local
policy making decisions are made. The CCAMP project was constantly
constrained by the quality of local level data such as parcel based land use,
or the total lack thereof. If resource management studies such as CCAMP are
to succeed, the development of these data sets must be supported.
8: Staff Expertise with Hardware and Software
Recommendation: Those persons working directly with the hardware and
software should be trained in their use prior to project start up.
Supporting Evidence: The CCAMP project was a learning experience for
each participant. Only one of the people responsible for data inputting had
knowledge of ARC/INFO software when the project began. Instead of placing the
responsibility for training on one individual and expecting participants to
learn 'on the job', it is important to provide training to all participants
during the initial stages of the project. At a minimum, all participants
should have been familiar with the PRIME operating system.
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-29-
9: Staff Availability
Recommendation: The CIS project should be the primary work day focus of
project participants.
Supporting Evidence: The CCAMP project depended on numerous participants
committing only a portion of their time to this CIS effort. This slowed down
the progress and diffused the momentum of the project. It also required that
a significant amount of time had to be committed to informing people of the
progress of the project.
10: Involvement of Decision Makers
Recommendation: A wide range of policy makers and decision makers should
be involved in project design to help identify needs and develop approaches
and scenarios.
Supporting Evidence: While the project team was made up of a diverse
interdisciplinary group of people, most were at the staff level. The true
policy and decision makers should have been more involved throughout the
project in brainstorming and critiquing final products. This would have
provided important insights to the scenarios early in the project.
Other CIS projects which are not inter-agency in nature may have even a
greater need for this involvement. While each participant in CCAMP brought to
the project the view point of their particular agency, in a project undertaken
by one agency, the CIS study may require a higher level policy maker who could
anticipate the perspective of various differing view points on a particular
analytic issue.
11: Assess Available Data
Recommendation: All available data sources, especially at the local
level, should be assessed at a early point in the analysis in order to develop
appropriate strategies for data verification.
Supporting Evidence: The two towns, Barnstable and Eastham, have very
different capabilities to gather and maintain data. While local data in
Barnstable could be used directly or used to verify state sources of data,
Eastham did not have a local data base. Consequently, it was more difficult
to find independent data sources with which to verify databases.
12: System for Data Verification
Recommendation: A systematic approach to data verification is essential.
This should include:
1. Information exchange between departments and local, state,
and federal agencies.
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-30-
2. Verification of digitized data against original source
map.
3. A person with knowledge of the study area to be in charge
of verification.
4. Allowance of adequate time in the project schedule.
Supporting Evidence: Data verification consumed significant time and
effort. A systematic approach to verification can ensure that the work
proceeds as efficiently as possible.
13: Labeling of Maps
Supporting Evidence: Data verification consumed significant time and
effort. A systematic approach to verification can ensure that the work
proceeds as efficiently as possible.
Recommendation: Place descriptive labels on all map products so there is
less chance of misinterpretation. Disclaimers should also be included on all
maps with which one cannot be fully assured of the accuracy of the data.
Supporting Evidence: Initial presentations of the CIS products revealed
the clarity of the maps to those whom had not been working with them.
Generally it was found that map titles were not descriptive enough to fully
explain what the map represented. Instead of always having a project
participant nearby to explain the scenario, a descriptive text label could
have explained the purpose of the map and what it represented.
Additionally, a lot of attention was at these presentations being paid to
accuracy of data, especially by persons with a first hand knowledge of it,
i.e., landowners. This detracted from the analysis. If verification efforts
cannot assure the validity of the data, note should be made of that on the
map.
14: Use of Maps for Communication
Recommendation: The maps generated by CIS should be evaluated according
to their ability to communicate to an audience what is displayed.
Supporting Evidence: The purpose of the CIS maps is to communicate to
others the results of a policy analysis question. Those people generating the
maps must consider ths best method to convey their results in an
understandable way. Frequently the CIS technology enables the analysis to
incorporate more detail than can be easily understood. .For example, the
analyses which categorized land uses into fifteen different categories based
on risk assigned a different color to each category. This created a very
detailed map which may have been difficult to understand. The conclusions of
the analysis may have been more effectively communicated if only six risk
categories were presented on the maps.
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-31-
VI. ASSESSMENT AND CONCLUSIONS
The depth and breadth of the scenario process clearly illustrate the
advantages of using CIS technology in ground water protection efforts. The
capabilities of the technology provide opportunities and challenges that
ground water managers have never faced before in terms of analytic capability
and presentation. While the processes are not new to environmental analysts,
CIS has provided the capability of quickly undertaking environmental analyses
in an organized manner utilizing large amounts of data, and displaying these
findings in a clear, professional presentation. Because of the power of the
technology and the relative ease of utilizing it, analyses may be driven to a
new level of sophistication.
CIS requires a commitment of money, time, and knowledgeable people in
order to be effectively applied. The software and hardware costs are
significant, but pale next to the commitment of manpower required. The CCAMP
demonstration project illustrates the dedication needed to undertake even a
moderate level of analysis within a project with limited scope. Figure 5
presented previously, shows each of the critical elements within an
application of CIS and the skills and time required to undertake each task.
Although a few individuals must understand the software, for the most part,
specialized skills are not required. CCAMP's experience clearly demonstrates
that a great deal of time and energy is dedicated to data related elements.
While this point should be emphasized to anyone considering utilizing CIS, the
relative requirements are a bit misleading within the context of this project.
More data were gathered and digitized than were actually employed within the
scenarios. Initially, sixteen scenarios were proposed which could have been
supported with the data available. Additionally, further analysis could have
been performed on the chosen scenarios if time had permitted. Consequently,
the energy dedicated to data acquisition and input could support a great deal
of analysis.
One should also recognize the special circumstances surrounding the CCAMP
project which also may have influenced data collection efforts. CCAMP had
already established a structure based on the commitment and cooperation of
agencies at each level of government. Lines of communication were well
established, not only between participating agencies but among all the other
agencies. This was especially important in the collection of local data. The
CCAMP project was a demonstration of effort and data collection which took
place over a limited period of time. A long term commitment to use of CIS in
everyday analyses would involve ongoing data collection efforts. In such
cases, sufficient time and money could be committed to maintaining an
up-to-date database.
Of greater significance, however, is the realization that wellhead
protection itself is very data intensive, independent of utilizing CIS as an
analytic tool. Analysis is at a small scale and thus requires refined and
detailed data. Finding this level of data is difficult at best and ensuring
its accuracy can be troublesome. Local governments have gathered data based
on their individual needs. Consequently each community maintains data at a
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-32-
different level of detail. Simultaneously, the state databases do not always
include enough detail to effectively undertake wellhead protection. The
conclusion is that wellhead protection efforts may require field
investigations, such as those undertaken by CCAMP to identify underground
injection wells, in order to gather the specific data required to protect the
ground water resources. This situation additionally illustrates how the
activities required in one regulatory program, underground injection control,
complement, and enhance the potential effectiveness of another, namely
wellhead protection.
Another key conclusion related to the use of CIS for wellhead protection
is the need for accurate data. Because of the professional presentation of
the CIS generated maps and the level of detail which can be attained, the
margin of error which can be sustained is minimal. The precision of the CIS
generated maps presently exceeds that of the quality of the data routinely
gathered as part of local and state regulatory programs. Because traditional
analytic tools generally have less rigorous data requirements, the use CIS may
drive data gathering efforts in the future.
The demonstration indicated that data issues became less critical when
the analyses were at a larger scale, i.e., when they covered a larger area.
Two scenarios done in the Town of Eastham were quite successful in utilizing
the capabilities of CIS to site facilities. Because data required for these
scenarios was of a more general nature. The regional analysis of a one half
mile radius interim ZOC policy is another example of CIS which produced
significant results and was not hindered by data verification difficulties.
Although a substantial portion of ground water management occurs at the
local level and CIS has the potential for aiding local decision makers in
designing the most, effective management tools, the quality of existing data
puts a burden on CIS users and challenges the integrity of analyses. Until
the time that site specific data meets certain quality standards, CIS is most
effectively employed at a regional and state level.
In order to overcome data reliability problems while using available
databases, extensive systematic verification efforts are required. It was for
all these reasons that CCAMP developed a data dictionary in order to track all
sources of data. A data dictionary should be an integral part of all CIS
projects, especially those which are ongoing and involve the compilation of a
series of databases over time. If data cannot be fully verified then
notations should be placed on all maps indicating the potential inaccuracies
of the data.
The CCAMP project has illustrated that there are numerous ground water
management decisions to be made within regional, state, and federal
governments for which CIS provides useful insight. Its utility in setting
regulatory program priorities based on protecting the most vulnerable resource
areas first has been shown. This kind of analysis could be applied to many
program areas. It is the type of analysis which CCAMP advocates in a
resource-based approach to ground water protection.
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-33-
While the scenarios undertaken in this project attempted to prioritize
management of contaminating activities within a particular regulatory program,
the next step would be to develop a method of comparing the risk posed by
different activities, as for example in the comparative risk of landfills,
junkyards, and versus historical spill sites. This type of analysis would
enable policy makers to set priorities between regulatory programs. CIS would
be useful in attempting such an analysis because it is able to manipulate,
analyze, and display large quantities of data; although developing an
appropriate ranking scheme is still a challenge.
The power of the computer presents many advantages to using CIS over more
traditional methods of analysis. It enables the user to generate multiple
versions of a mapped product. Consequently, it is easy to correct errors and
to refine and update maps as new data and new risk assessment methods becomes
available. In the day of paper maps this would have been a cumbersome, time
consuming task and possibly would not have been attempted. The interactive
capabilities of CIS allow individuals to work at the terminal and ask numerous
'what if...' questions. Answers on the screen, or on a map, are nearly
instantaneous. In this way, analysts and policy makers may clearly examine
the implications of incremental changes in policy.
The science which may be incorporated into risk based analyses for ground
water protection is also in need of advancement. This is not a flaw with the
CIS technology but simply reflects limitations on the understanding of
physical phenomena related to ground water. In the underground storage tank
scenario and the landfill scenario, there was not enough supporting science to
document the real threats to the ground water resources and develop a true
ranking system. CIS could have incorporated any relationship between the
threatening activity and water quality if it had been available.
Time and again CCAMP participants have observed the power of the CIS
generated maps as a means of communication. While all maps are generally able
to present issues of a geographic nature better than words, the CIS generated
maps are of such high quality and are so clear and concise, that the message
is easy to grasp. Additionally, the maps generated a great deal of useful, in
depth, discussion. Because the CIS utilized data from a variety of offices
and programs, representatives from all these programs gathered to examine the
products. It was useful in this forum to show individual programs how their
concerns overlapped and how ground water protection required cooperation of
each of these programs. In this context, CIS appeared to provide results much
greater than the sum of its parts.
-------
Screening For Potential Pu
•j*
Water-Supply Sites
F a s t h a m, MA
Wr I I jr. i. jn I f:nJ
= j I i i- • i- J 150 II
a
EXPLANATION
Potential 1 MGO Pub I i .
Water Suppl/ Sites
Locations f Private Wells
Calculated Zone of Contribution
1 MGD We II (Radius . 850 ft)
DEQE Interim 1/2 -mi Ie Buffer
Cape Cod National Seashore
j Bound ?r/ of A 12 i I ? b I e Area
— Passing Screening Criteria
for Potential We II Sites
To*no • ! , • C : -n i
0 i i «• I i . n '. [ 11 : und-Wu In r I .»
B t c 6 and C«fHlt»rl«l Pof -I-
t j I I - i •• J 400 II
Figure 8
-------
Screening For a Potential
S t ump Dump Site
E a s t h am, MA
Wetlands and Ponds Commercial Parcels
Buffered 150 and 500 ft Buffered 500 ft
EXPLANATION
Available Parcels Passing
S creen ing Criteria for a
Stump Dump
Cape Cod National Seashore
Kou t e 6
Figure 9
Town-o»ne d Parcels
Greater than 5 Acres
Roads Buffered 150 ft
-------
Intertown Management: Zoning and Landuse
Across Barnstable and Yarmouth
Town Boundaries
ZONING
Re s i den t i a
Business
Industrial
LANDUSE
Residential
Business
Industrial
Publicly Owned
Land
Undtve I oped
Land
Figure 10
-------
Intertown Management: Zoning and Landuse
Across Barnstable and Yarmouth
Town Boundaries
BARNSTABLE
DIESE
zoc
AREAS WHERE LANDUSE AND
ZONING DO NOT AGREE
EXPLANATION
LANDUSE/ZONING
Res i dent i a I / Bus Ines s
Residential/Industrial
Business/Industrial v
*
Business/Residential
Industrial/Business
I ndus t rI a I/Res iden t i a I
Areas Where Landuse And
Zoning Are In Agreement, Or
Where Landuse Is Publicly
Owned Or Undeveloped
A/ Barnstable Zone of
Con t r i bu t i on
Town -line
Ay Yarmouth and Maher Diesel
'Zones of Contribution
Public Water-Supply Wells
Figure 1 1
-------
Increase Of Potential Risk To Public-Supply Wells
From landuse Build-Out, Barnstable, MA
EXPLANATION
II »k Citegor I es
|p Open lind
[g| Undevelopable Laid
Q Developable leildetllal
(^Developable Commercial
jl| Deve I opab I e Induilrlal
^ Enter li I nine • I
m tttldtut III . Single ind
Mil I HiBl I y
g Hctelt, Moleli, Inn,
and leitanranti
IJTj Offices aid »«blIc
StrvIcti
IJfl letill
|| Storage, Warehouie and
DlilrI but Ion
H] 'ndui I r 111 Storage
Q Auto lelated
[2] Indmlrlil
' Publicly Owned land
(Variable Illk)
[g] Zone of Contr Ibit Ion
Boundjry
fv] Town-1 I ne
o P«bl Ic Water-SvppIy
We I 11
BEFORE BUILD-OUT
AFTER BUILD-OUT
EXPLANATION
Ilik Ca tegorlet
t § Open Land
° f^ Undevelopable Land
Enter!aInment
leildenl III
Hotel!, Hoteli, lint,
and lei tairint I
oiiicti aid r»bi u
Sorvlcei
IJ leta I I
3 Storage, Wartnotie ind
DlttrlbitIon
Indm t rill Slerige
JJJ Alto Itl a ted
3 Indnt rlil
f~l fibllcly Owned
(Variable lltk)
QQ Zone of Cont r Ibit Ion
Bound i r y
£«] Town- 1 I ni
o Fibl Ic Witer-Svpply
Mill
Figure 12
-------
Land-Use -Based Calculation of the Average Nitrate
Load to Ground Water within the Zone of Contribution
Barnstable,MA
Re
Sp
EXPLANATION
lative Loads F rom
ecific Land Uses
X - Non -Contributing
or S ewe red
G - Dry Goods Stores
P - Gas Stations
F - Off i ces
E - SmaII Businesses
S - Restaurants
A - Residential
U - Motels, and
Condomi n i urns
H WWTP, and Special
Cases
Zone of Contribution
Boundary
Town-Line
Pub lie Wa ter-SuppIy
Wei I s
i
u>
vo
Figure 13
-------
Assessing Risk to Ground-Water Quality
At Public Water-Supply Sites From
Underground Storage Tanks
EXPLANATION
RELATI VE RISK
Q LOW RISK (020)
* LOW-MED RISK (21-40)
• MEDIUM RISK (41-60)
• MED HIGH RISK (61-80)
• HIGH RISK (81-100)
j^Maher Diesel »2 Zone
of Contribution
Groundwater Time-
-of-Travel Limits
^j Major Roads
Maher Diesel *2 Well',
fATER
Figure 14
o
-------
-40a-
Risk
Choree
Da t
ID
Ranking for Each Tank
(eristic and Total Risk
F.or Each Tank
i
o as of January. 1987
* a
X •"
2 i - i
f. ^ u z
•— ^. LfcJ *— ^
UJ z »*vl Z CO
— o< — Oce „ . -..
O «C r— (/} <-> 3 KljK
LOW-MEO RISK
41
144
145
134
44
45
78
79
43
76
0
0
0
3
0
0
0
0
0
0
0
0
0
0
0
0
0
1
4
0
0
0
0
0
0
0
0
0
2
0
5
3
3
1
4
4
3
2
1
4
0
1
1
0
2
2
2
2
0
2
4
5
5
5
4
4
5
5
4
5
31
31
31
31
34
34
34
34
37
37
MEDIUM RISK
165
77
128
36
42
179
186
163
37
39
40
80
121
81
122
i 82
180
184
38
129
183
50
160
2
0
3
0
0
3
3
3
0
0
0
1
3
1
3
1
3
3
0
3
3
3
3
WED-HIGH
123
124
125
126
182
152
153
156
157
158
159
185
162
49
127
154
155
161
164
181
118
1 19
H 1 GH
187
3
3
3
3
3
2
2
3
3
3
3
3
3
3
3
3
3
3
3
3
2
2
2
0
1
2
4
3
3
2
4
4
4
3
l
3
i
3
3
1
4
0
3
3
3
2
2
2
2
2
2
2
2
2
2
2
0
2
0
2
0
2
2
2
2
0
2
2
t
4
2
5
2
1
1
1
4
3
3
3
4
3
4
3
;
2
4
1
3
4
2
0
2
0
1
2
0
0
0
1
2
2
2
1
2
1
•2
1
2
2
5
2
0
2
5
5
5
4
4
5
5
6
4
4
4
6
4
6
4
6
5
5
4
5
5
5
5
41
44
44
48
48
48
48
48
51
51
51
51
51
51
51
51
5!
51
55
55
55
58
58
RISK
3
3
3
3
3
4
4
1
1
1
1
5
2
3
3
4
4
2
3
3
3
3
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
5
5
3
3
3
2
2
4
4
4
4
1
3
4
4
2
2
4
3
2
5
5
0
0
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
5
2
2
5
5
5
5
5
6
6
6
6
6
6
5
6
5
5
6
6
6
6
5
6
6
62
62
62
62
62
62
62
62
62
62
62
62
62
65
65
65
65
65
65
68
68
68
RISK
5
3
2
4
5
5
82
DISTANCE RANK
(Distance in feel Iron
neoresl public-supply
• ell)
>4400
3251-4400
1976-3250
639-1975
426-638
ACE(Yeors)
0-4
5-9
10-14
15-20
21-25
26-30
dealer than
or equal 30
RANK
0
1
2
i
4
5
6
CONTENT
Fuel Oil.
Oil. Heal
Ne» Oil.
Aviation
Kerosene
Diesel Oi
Gaso 1 i ne
taste Oi 1
Oil. Gear
ing Oil.
Empty
Gas.
1 .
. Used
Oi 1
RANK
0
1
2
5
IAN* y»H»l»L
f i be r q t os s
Doub I e-wo I I
Sleel
Slee 1
Concrete
RANK
0
1
2
3
SI Z[(<)0l Ions)
nt i oI
Limited Industrial.
Urban Bus i ness 3
Industrial 4
Business 5
Highway Business 6
MAP NOTES: This illustration presents the results of one type ol
a muIticriteria evaluation method to estimate the risk
to ground-later quality at a public «ro t e r - supp I y well
from underground storage tanks. In an automated proc-
eedure, the range of values for six characteristics of
each tank located within the zone of contribution to a
•ell are ranked and then added to determine the relative
risk of the tank. The data for this demonstration i i\
the Barnstable ZOC were compiled in January 1987 by the
Cape Cod Aquifer Management Project (CCAMP). This anal
ysis is one of si> demonstration scenarios prepared by th.
CCAMP-GIS project .
-------
POTENTIAL RISK TO PUBLIC-SUPPLY
WELLS FROM LANDFILLS, CAPE COD
Location and Potential Risk of
Landfills to Public-Supply Wells
* Low Risk (0-20)
* Low to Moderate Risk (21-40)
* Moderate Risk (41-60)
* Moderate to High Risk (61-80)
* High Risk ( >80)
N Zones of Contribution
• Public Water-Supply Wells
^^
Q
Figure 15
-------
CRITERIA FOR RANK I NG
LANDFIUS
DISTANCE (ft) RANK
L»i than or
equoI to 400 5
401-1000 4
1001-2640 3
2641-5280 2
Greatfr than or
• quo I to 5281 1
Distance 1 - H2I in anticip-
ated direction
of flow
<2S in anticip-
ated direction
of flow
Flat or owojr
from anticip-
ated direction
of flew
Away from
publ ie water
•apply
WEIGHTING FACTOR
RANK
3
2
1
0
- 4
DEPTH TO WATER-
TABLE (FT)
Leet than or
equal to 2
3-8
9-15
18-25
26-35
Greater than
or equal to 36
WEIGHTING FACTOR
RANK
S
4
3
2
1
0
- 6
THICKNESS/NATURE
OF UiCONSOUOATED
NATEIIU
LECRAND SCORE
8-t
7
«
4-5
2-1
9-}
WEIGHTING f ACTOR -
RANK
5
4
1
2
1
0
1
SIZE
(ae r e i)
>50
21-50
11-20
1-10
Leei than
or equal
to 5
WEIGHTING
RANK
i
4
3
2
1
FACTOR - 1
I I HER RANK
prilint 0
not prtttitt 5
WEIGHT INC FACTOR - 4
UACHATC COLLECTION
SYSTEM
preient
not prttmt
WEIGHTING FACTOR - 4
RANK
0
S
Ranking of Landfill Characteristics
and Calculated Totd Risk
ID
UJ
O
z
•<
IS*
NAME a
10* RISK:
1 Of TO MOOCIATC IISK:
CM
UJ t—
<-> z
Z UJ
•< X —
»— »- 0
i/i a. <
— uj ec
o , o o
No land*
N* Land!
THICKNESS
1 1 1
1 1 1
i
-------
ZONES OF CONTRBUTION AND
HALF MLE BUFFERS AROUND
PUBLIC SUPPLY WELLS
ZONE OF CONTRIBUTION
TO PUBLIC SUPPLY WELL
HALF MILE BUFFER AROUND
PUBLIC SUPPLY WEL
Figure 16
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