Literature Review of Methods for Deliniating Wellhead Protection Areas, December 1998

LITERATURE REVIEW OF METHODS FOR
DELINEATING WELLHEAD PROTECTION
AREAS
United States Office of Water EPA 816-R-98-021
Environmental Protection (4606) December 1998
Agency
Blandford, Neil T. 1990. Semi-analytical model for the delineation of wellhead protection areas: Version 2.0.

Caswell, B. 1992. Protecting fractured-bedrock wells.

Cleary, T.C. and R.W. Cleary. 1991. Delineation of wellhead protection areas: theory and practice.

Lennox, J.B., C.F. Adams, and T.V. Chaplik. 1990. Overview of a wellhead protection program. From the
determination of recharge areas to the development of aquifer protection regulations.

Livingstone, S., T. Franz, and N. Guiger. 1995. Managing ground water resources using wellhead protection.

McElwee, C.D. 1991. Capture zones for simple aquifers.

Miller, D.W. Principles of ground water protection.

Reilly, T.E. and D.W. Pollock. 1996. Sources of water to wells for transient cyclic systems.

Schleyer, R., G. Milde, and K. Milde. 1992. Wellhead protection zones in Germany: delineation, research and
management.

Swanson, R.D. 1992. Methods to determine wellhead protection areas for public supply wells in Clark County,
Washington. Intergovernmental Resource Center. 4

USEPA. 1993. Guidelines for delineation of wellhead protection areas.

USEPA. 1993. Wellhead protection workbook.

USEPA. 1991. Delineation of wellhead protection areas in fractured rocks.

USEPA. 1991. Protecting local ground water supplies through wellhead protection.

USEPA. 1991. Wellhead protection strategies for confined-aquifer settings.

USEPA. 1988. Developing a state wellhead protection program: A user's guide to assist state agencies under the
Safe Drinking Water Act.

USEPA. 1987. Guidelines for delineation of wellhead protection areas.

Wuolo, R.W. Flow modeling for wellhead protection delineation.

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Case Studies

Bailey, Z.C. 1993. Hydrology of the Jackson, Tennessee area and delineation of areas contributing ground water
to the Jackson Well Fields.

Barlow, P.M. 1989. Delineation of contributing areas to public supply wells in stratified glacial-drift aquifers.
Protecting Ground Water from the Bottom Up: Local Responses to Wellhead Protection. Proceedings of the
Conference, October 2-3, 1989, Danvers, Massachusetts.

Bogue, Kevin Scott. 1994. Evaluation of wellhead protection models; a case study, Xenia, Ohio.

Bowker, Joel A. 1993. A preliminary wellhead protection program for the village of Enon, Ohio.

Bradley, M.D. and S.M.K. Bobiak. 1997. WHPA delineation methodology development for large wells
completed in stratified drift in Rhode Island.

Edson, D.F. 1989. Aquifer protection through large scale computer modeling. Protecting Ground Water from
the Bottom Up: Local Responses to Wellhead Protection.

Freethey, G.W., L.E. Spangler, and W.J. Monheiser. 1994. Determination of hydrologic properties needed to
calculate average linear velocity and travel time of ground water in the principal aquifer underlying the
southeastern part of Salt Lake Valley.

Ginsberg, M. 1995. Applicability of wellhead protection area delineation to domestic wells: a case study.

Golder Associates Inc., Oregon, and W.E. Nork. Nevada. 1992. Draft wellhead delineation demonstration
project for Conger Wellfield.

Golder Associates Inc. 1992. Demonstration of wellhead protection area delineation methods applied to the
Weyerhaeuser Wellfield Springfield, Oregon.

Hansen, C.V. 1991. Description and evaluation of selected methods used to delineate wellhead-protection areas
around public-supply wells near Mt. Hope, Kansas; Water Resources Investigation.

Heath, Douglas L. 1995. Delineation of a refined wellhead protection area for bedrock public supply wells,
Charlestown, Rhode Island.

Heath, Douglas L. 1993. The Wilton, N.H. wellhead protection area pilot project.

Landmeyer, J.E. 1994. Description and application of capture zone delineation for a wellfield at Hilton Head
Island, South Carolina.

Moore, Beth A. 1993. Case studies in wellhead protection area delineation and monitoring.

Noake, K.D. 1989. Fox (Borough) guarding the aquifer coop: local control at work. Protecting Ground Water
from the Bottom Up: Local Responses to Wellhead Protection.

Osborne, T.J., J.L. Sorenson, M.R. Knaack, D. J. Mechenich, and M.J. Travis. Designs for wellhead protection
in central Wisconsin: Case studies of the town of Weston and City of Wisconsin Rapids.

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Rheineck, Bruce D. 1995. River-ground water interactions and implications for wellhead protection at Black
River Falls, Wisconsin.

Risser, D.W. and T.M. Madden. 1994. Evaluation of methods for delineating areas that contribute water to
wells completed in valley-fill aquifers in Pennsylvania.

Robinson, J.L. 1995. Hydrogeology and results of tracer tests at the Old Tampa Well Field in Hillsborough
County, with implications for wellhead protection strategies in West-Central Florida.

Schmidt, R.G., M.S. Beljin, R. Ritz, A. Field, and A. Zahradnik. 1991 Wellhead management modeling project,
final report project 661428, Montgomery County Phase III.

USEPA. 1995. Tribal wellhead protection demonstration projects.

USEPA. 1992. Development of a map and image processing system as decision support tool to local wellhead
protection.

Walden, R. Ground water protection efforts in four New England states; Technical Report.

Land Use/Mapping/Geographic Information Systems (GIS)

Baker, Carol P., M.D. Bradley, and S.M.K. Bobiak. 1993. Wellhead protection area delineation: Linking flow
model with GIS.

Barnett, Christopher, Y. Zhou, S. Vance, and C. Fulcher. Wellhead protection area delineation for identifying
potential contamination sources.

Freethey, G.W., L.E. Spangler, and WJ. Monheiser. 1994. Determination of hydrologic properties needed to
calculate average linear velocity and travel time of ground water in the principal aquifer underlying the
southeastern part of Salt Lake Valley.

Hendricks, Laurel Ann. 1992. Implementation of a wellhead protection program utilizing a Geographic
Information System.

Kilborn, K., H.S. Rifai, and P.B. Bedient. The integration of ground water models with GIS.

Muttiah, Ranjan Samuel. 1992. Neural networks in agriculture and natural resources: its application to the
wellhead protection area problem using GIS (Indiana, Vermont).

Olimpio, J. C., E.G. Flynn, S. Tso, and P. A. Steeves. 1990. Use of a Geographic Information System to assess
risk to ground water quality at public supply wells, Cape Cod, Massachusetts.

Rifai, H.S., L.A. Hendricks, K. Kilborn, and P.B. Bedient. 1993. GIS user interface for delineating wellhead
protection areas.

Analytical

Bair, E.S., C.M. Safreed, and E.A. Stasny. 1991. A Monte Carlo-based approach for determining traveltime-
related capture zones of wells using convex hulls as confidence regions.

Bolt, Walter Joseph. 1995. Delineation of a wellhead protection area for the village of Chelsea, Michigan, using
two dimensional steady-state MODFLOW.

Bradbury, K.R. and M.A. Muldoon. 1994. Effects of fracture density and anisotropy on delineation of wellhead

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protection areas in fractured-rock aquifers.

Cole, Bryce Evan. 1996. Impact of hydraulic conductivity uncertainty on capture zone delineation (wellhead
protection, contaminant transport)

Edson, D.F. 1989. Aquifer protection through large scale computer modeling. Protecting Ground Water from
the Bottom Up: Local Responses to Wellhead Protection.

Grubb, S. 1993. Analytical model for estimation of steady-state capture zones of pumping wells in confined and
unconfined aquifers.

Haitjema, H.M., J. Wittman, V. Kelson, and N. Bauch. 1994. Wellhead Analytic Element Model (WhAEM):
program documentation for the wellhead analytic element model.

Hall, J.C. 1989. Use of time of travel in zone of contribution delineation and aquifer contamination warning.
Protecting Ground Water from the Bottom Up: Local Responses to Wellhead Protection.

Harmsen, E.W., J.C. Converse, M.P. Anderson, and J.A. Hoopes. 1991. A model for evaluating the three-
dimensional ground water dividing pathline between a contaminant source and a partially penetrating water-
supply well.

Kraemer, S.R., H.M. Haitjema, and O.D.L. Strack. 1994. Capture zone modeling using the WhAEM.

Morrice, Joseph Nathan. 1997. Wellhead protection area delineation: evaluation of an analytic solution under
parameter uncertainty.

Noake, K.D. 1989. Fox (Borough) guarding the aquifer coop: local control at work. Protecting Ground Water
from the Bottom Up: Local Responses to Wellhead Protection.

Ramanarayanan, T.S., D.E. Storm, and M.D. Smolen. 1995. Seasonal pumping variation effects on wellhead
protection area delineation.

Sahl, Barbara L. 1994. A comparison of wellhead protection area delineation methods at Larimore, North
Dakota.

Shafer, J.M. and M.D. Varljen. 1992. Coupled simulation-optimization approach to wellhead protection area
delineation to minimize contamination of public ground water supplies.

USEPA. 1993. Wellhead protection in confined, semi-confined, fractured and karst aquifer settings.

van der Heijke, P. and M.S. Beljin. 1988. Model assessment for delineating wellhead protection areas.

Varljen, M.D. and J.M. Shafer. 1993. Coupled simulation-optimization modeling for municipal ground water
supply protection.

Varljen, M.D. and J.M. Shafer. 1991. Assessment of uncertainty in time-related capture zones using conditional
simulation of hydraulic conductivity.

Wilson, J. and G. Achmad. 1995. Delineation of wellhead protection areas using particle tracking analysis and
hydrogeologic mapping, northern Anne Arundel County, Maryland.

Wuolo, R.W., D.J. Dahlstrom, and M.D. Fairbrother. 1995. Wellhead protection area delineation using the
analytic element method of ground water modeling.

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Yeh, G.T., S. Sharp-Hansen, B. Lester, and Strobl. 1992. Three-Dimensional Finite Element Model of Water
Flow Through Saturated-Unsaturated Media (3DFEMWATER)/Three-Dimensional Lagrangian-Eulerian Finite
Element Model of Waste Transport Through Saturated-Unsaturated Media (3DLEWASTE): numerical codes
for delineating wellhead protection areas in agricultural regions based on the assimilative capacity criterion.

Numerical/Modeling

Banton, O., P. Lafrance, and J.P. Villeneuve. 1992. Delineation of wellhead protection area in an agricultural
zone by using solute transport modeling.

Guiger, N. and T. Franz. 1991. Development and application of a wellhead protection area delineation computer
program.

Harmsen, E.W., J.C. Converse, and M.P. Anderson. 1991. Application of the Monte Carlo simulation procedure
to estimate water-supply well/septic tank-drainfield separation distances in the Central Wisconsin Sand Plain.

Johanson, Mary Giglio. 1992. Delineation of time-related capture zones with estimates of uncertainty using
conditional simulation of hydraulic conductivity and numerical modeling.

Outlaw, James. 1995. A ground water flow analysis of the Memphis Sand Aquifer in the Memphis, Tennessee
Area.

USEPA. 1997. Numerical codes for delineating wellhead protection areas in agricultural regions based on the
assimilative capacity criterion.

Hydrogeologic/Geologic Analysis

Bhatt, K. 1993. Uncertainty in wellhead protection area delineation due to uncertainty in aquifer parameter
values

Caswell, B. 1990. River Recharge

Frederick, William T. 1991. Hydrogeology of the Onondaga Limestone and Marcellus Shale in Central New
York's Finger Lake region with emphasis in well-head protection and pollution potential

Gadt, Jeff W. 1994. Hydrogeology and hydrochemistry of the east-central portion of the Salt Lake Valley, Utah,
as applied to wellhead protection in a confined to semiconfined aquifer

Jost, Donald J. 1994. Hydrogeology and pollution potential of aquifers, Doylestown, Wayne County, Ohio

Paillet, F.L.and W.H. Pedler. 1996. Integrated borehole logging methods for wellhead protection

Pesti, Geza. 1993. Geoelectrics and geostatistics for characterizing ground water protection zones (Kriging,
Aquifer protection)

Quinlan, J.F., J.A. Ray, and G.M. Schindel. 1995. Intrinsic limitations of standard criteria and methods for
delineation of ground water-source protection areas (springhead and wellhead protection areas) in carbonate
terrains: critical review, technically-sound resolution of limitations, and case study in a Kentucky karst.

Teutsch, G. and B. Hofmann. 1990. The delineation of ground water protection zones using forced gradient
tracer tests: a model validation case study

Violette, P. 1987. Surface geophysical techniques for aquifer and wellhead protection area delineation

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Welhan, J. and C. Meehan. 1994. Hydrogeology of the Pocatello Aquifer: implications for wellhead protection
strategies

Miscellaneous

Jacobson, E., R. Andricevic, and T. Hultin. 1994. Wellhead protection area delineation under uncertainty

Pesti, G., I. Bogardi, and W.E. Kelly. 1994. Risk-based wellfield design combining different source of data

Ramanarayanan, Tharacad Subramanian. 1995. Evaluation of existing wellhead protection strategies for
controlling nonpoint source nitrate pollution
EXECUTIVE SUMMARY

This document supports both the Wellhead Protection Program and the Source Water Protection Program. This
document presents the results of a bibliographic search of the technical literature for publications, papers and
other documents addressing the technical aspects of wellhead protection area delineation. The document is a
companion to the review of technical literature addressing delineation of surface-water source water protection
areas found in Appendix 2 of State Methods for Delineating Source Water Protection Areas for Surface Water
Supplied Sources of Drinking Water.

INTRODUCTION
This document presents the results of a bibliographic search of the technical literature for publications, papers,
and other documents addressing the technical aspects of wellhead protection area delineation. The literature
summaries appear in the following sections: theory, case studies, land use/mapping/geographic information
systems (GIS), analytical, numerical/modeling, hydrogeologic/geologic analysis, and miscellaneous. Some
summaries appear in more than one section.

The literature search methodology for compiling information on Delineating Wellhead Protection Areas was as
follows:

1. Conducted an online literature search using the keywords "wellhead protection (and/or) delineation." The
following databases were searched:

a. AGRICOLA i. ERIC
b. AppSciTechAbs j. GEOBASE
c. BASICBIOSIS k. GEOREF (2 different versions)
d. BiolAgrlndex 1. PERABS
e. Article 1st m. PapersFirst
f WORLDCAT n. ReadGuideAbs
g. GenSciAbstract o. NewsAbs
h. DISS p. EBSCO
q. DIALOG
r. Journal of Water Resources Database

2. Queried Environmental Protection Agency (EPA) Regional specialists and specialists at EPA's Robert S.
Kerr Environmental Research Center/Office of Research and Development and EPA's National Exposure

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Research Laboratory/Office of Research and Development.
3. Searched the world-wide web using keyword searches of environmental abstracts, "wellhead protection,"
and "wellhead protection delineation." From this, the University of Toronto homepage was accessed and
the Environmental and Pollution abstracts database was searched.

LITERATURE SUMMARIES

Theory

Blandford, Neil T. 1990. Semi-analytical model for the delineation of wellhead protection areas: Version 2.0.
Report prepared for U.S. EPA Office of Ground Water Protection, 62 pp.

Wellhead Protection Area (WHPA) is a modular, semi-analytical ground water flow model designed to assist
State and local technical staff with the task of WHPA delineation. The WHPA model consists of four
independent computational modules that may be used to delineate capture zones. Three of the modules contain
semi-analytical capture zone solutions; they are applicable to homogeneous aquifers that exhibit two-
dimensional, steady ground water flow in an area! plane. Barrier or stream flow conditions which exist over the
entire aquifer depth may be simulated. Available aquifer types include confined, leaky-confined, and
unconfined with areal recharge. One of the modules contains a Monte Carlo module that provides for
uncertainty analysis capability. The fourth module is a particle tracking module that may be used as a
postprocessor for two-dimensional numerical models of ground water flow.

Caswell, B. 1992. Protecting fractured-bedrock wells. Water Well Journal, v. 46, no. 5, pp. 42-45.

Ground water protection in crystalline bedrock terrain is complex due to the unpredictability of water-bearing
fractures. Pump tests of wells drilled in fractured crystalline bedrock reveal a zone of depressed bedrock which
is elongated in the direction of major water-bearing fractures. Zones of protection are hard to assign because of
natural anisotropic and heterogeneous characteristics. Travel times of ground water are dependent on direction
of a fracture and on unconsolidated deposits for ground water storage. According to field investigations, an
arbitrary radius will not protect high-yielding wells in fractured crystalline bedrock. Certain levels of protection
may need to be established based on protective zones within the contributing area. Outer zones may limit
density and the type of development while the inner zones may exclude any development. Sub-zones are
recommended to be elliptical and oriented NNW-SSE along the major water-bearing fracture zones.

Cleary, T.C. and R.W. Cleary. 1991. Delineation of wellhead protection areas: theory and practice. Water,
Science, and Technology, v. 24, no. 11, pp. 239-250.

The Wellhead Protection Program, a preventative approach in ground water protection, has been established to
protect ground water within the WHPA of a well. Sources of potential pollution within the delineated WHPA
are defined as threats and need to be monitored for safe operation of a wellfield. A conceptual standard,
assigned a numeric value called the criterion threshold, serves as the basis for the WHPA delineation. The
simplest method used to define a WHPA is the fixed radius method. With increasing sophistication, a WHPA
may be defined by hydrogeological mapping and by analytical and numerical modeling. FLOWPATH and other
models which simulate the effects of different hydrogeological scenarios were used to demonstrate how subtle
changes in field conditions may have large impacts on shape, size, and orientation of the WHPAs.

Lennox, J.B., C.F. Adams, and T.V. Chaplik. 1990. Overview of a wellhead protection program. From the
determination of recharge areas to the development of aquifer protection regulations. Journal of English Water
Works Association, v. 104, no. 4, pp. 238-247.

The public water utility has requested that the town of Cheshire, Connecticut implement a multi-faceted
regulatory program which would increase protection of the aquifer. Of the 21,200 residents, 82 percent are
served by the public water supply within Cheshire. Numerical modeling, the most accurate way to determine
recharge area boundaries, was used to delineate the aquifer recharge area for the water-supply wells. According
to the public utility, a technically sound recharge area map and education of both municipal officials and

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residents are the key elements for convincing a town to adopt a wellhead protection strategy.

Livingstone, S., T. Franz, and N. Guiger. 1995. Managing ground water resources using wellhead protection.
Geoscience Canada, v. 22, no. 4, pp. 121-128.

The terminology and methodologies used in wellhead protection to delineate wellhead protection areas are
explained. A hypothetical case study is presented to show different methodologies for delineation and
evaluation. This hypothetical study proves that a numerical three-dimensional model provides a more accurate
WHPA than a two-dimensional numerical or an analytical model. Delineation errors and potential risks of
protecting the WHPA are also discussed.

McElwee, C.D. 1991. Capture zones for simple aquifers. Ground Water GRWAAP. v. 29, no. 4, pp. 587-590.

Analytical expressions to define well capture zones cannot be explicitly solved for the coordinates of the
capture zone boundary. An iterative scheme was developed which allows the solution in a timely manner. To
cover the entire region of interest, three forms of the analytic solution must be used. A smooth definition of the
capture zone requires 100-1,000 intervals along the x-axis. A FORTRAN program was written which works in
a variety of computing environments. No user interface is included. If the spacing of wells is not too close,
capture zone superposition is expected to be adequate. The program is a good first step in wellhead protection
or cleanup scenarios.

Miller, D.W. Principles of ground water protection. 1992. In: ASCE National Conference on Irrigation and
Drainage, Baltimore, Maryland, August 2-6, 1992. Publ. ASCE, New York, NY.

A thorough knowledge of ground water flow systems and an understanding of how contaminants migrate
through geologic formations leads to successful wellhead protection programs. Once there is a thorough
understanding of the mechanics involved, areas of contribution can be mapped and controls, such as limitations
on land use, can be imposed.

Reilly, T.E. and D.W. Pollock. 1996. Sources of water to wells for transient cyclic systems. Groundwater. v. 34,
no. 6, pp. 979-988.

State agencies are adopting wellhead protection programs. The focus of many of these programs is to protect
water supplies by determining the area contributing recharge to the water-supply wells. Another thrust is to
specify regulations to minimize contamination of the recharge water by activities at the land surface. Recharge
water protection is the focus of this document.

Schleyer, R., G. Milde, and K. Milde. 1992. Wellhead protection zones in Germany: delineation, research and
management. Journal of the Institution of Water and Environmental Management, v. 6, no. 3, pp. 303-311.

Germany has much legislation to provide adequate protection of ground water. Up to four wellhead protection
zones may be delineated within the recharge area of a well. New scientific data on ground water protection has
been obtained in a few areas: (1) interactions of bacteria and viruses in aquifers; (2) organic and inorganic
pollutants in soils and aquifer behavior; (3) effects on ground water quality of non-point and point source
pollution from hazardous substances; and (4) influences of atmospheric pollutants on ground water quality.
New wellhead protection areas should be assigned for both public and private well supplies. Strict requirements
should be placed on agriculture that takes place within the catchment areas of drinking water wells. A system
should be established for systematically inspecting and observing catchment areas.

Swanson, R.D. 1992. Methods to determine wellhead protection areas for public supply wells in Clark County,
Washington. Intergovernmental Resource Center.

Wellhead protection area boundaries can be based on the area of contribution to the well (zone of contribution)
or a more arbitrary consideration such as a manually drawn circle around a well. To determine the zone of
contribution, the hydrologic and hydrogeologic factors must be considered. A zone of influence is an area where

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the pumping well influences the water level. The Department of Health in Washington State is responsible for
designing and implementing a state wellhead protection program. The Wellhead Policy Advisory Committee
and the Wellhead Technical Advisory Committee were established by the Department of Health to assist in
assuring that the program is appropriate for conditions in Washington State.

USEPA. 1993. Guidelines for delineation of wellhead protection areas. EPA Report/440-5-93/001, Office of
Water, Office of Ground Water Protection, USEPA.

This document is a reprint of the document of the same name, published in 1987 (see below).

USEPA. 1993. Wellhead protection workbook. Report prepared for U.S. EPA Region III Water Management
Division, 46 pp.

This is a workbook to help resource managers and residents develop and understand water resource protection
programs for their local and regional aquifers. The following four steps of a successful program are discussed:
(1) organization of local committee; (2) mapping of ground- water protection areas; (3) identification of existing
and potential contamination sources; and (4) development and implementation of protection strategies. This
workbook is to be used in conjunction with the video "The Power to Protect," a 30- minute presentation of
successful case studies of ground water protection in three communities. Information, interpretations, and
graphics on ground water protection are presented with follow-up exercises, to reinforce the user's
understanding of terminology, issues, and applications.

USEPA. 1991. Delineation of wellhead protection areas in fractured rocks. EPA Report /570-9-91/009, Office
of Ground Water and Drinking Water, USEPA, 144 pp.

This document provides technical assistance to help address the hydrogeological aspects of the Wellhead
Protection Program. Six methods for delineating wellhead protection areas were studied at two sites in
Wisconsin to determine which are most appropriate for application to unconfmed, fractured-rock aquifers.

USEPA. 1991. Protecting local ground water supplies through wellhead protection. EPA Report 7570-09-
91/007, Office of Water, USEPA, 18 pp.

This is a user friendly, five-step approach to ground water protection and an excellent resource for community
discussion. Mayors, water supply managers, other agency officials, or interested citizens can use it to introduce
the wellhead protection program to their communities. It provides an overview of the steps taken in developing
a program for wellhead protection starting with forming a team and then delineating the wellhead protection
area.

USEPA. 1991. Wellhead protection strategies for confined-aquifer settings. EPA Report /570-9-91/008, Office
of Water, USEPA.

This document provides methods for delineating wellhead protection areas for wells or wellfields in confined-
aquifer settings. The document also presents approaches for distinguishing between confined and unconfmed
aquifers; a methodology is presented for determining the degree of aquifer confinement.

USEPA. 1988. Developing a state wellhead protection program: A user's guide to assist state agencies under the
Safe Drinking Water Act. EPA Report /440-6-88/003, Office of Ground Water Protection, USEPA, 44 pp.

This technical assistance document shows users how to tailor a wellhead protection program containing the
requisite elements. It supplements the June 1987 Guidance for Applicants for State Wellhead Protection
Program Assistance Funds under the Safe Drinking Water Act, illustrates a range of options from which states
can choose, and gives examples of different approaches for developing each specific element of the program.
Illustrations and case studies provide additional guidance on how a state can maintain its flexibility in meeting
these requirements. The document ends with a one-page road map showing how the submittal can be put
together from beginning to end.

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USEPA. 1987. Guidelines for delineation of wellhead protection areas. EPA Report /440-6-87/010, Office of
Ground Water Protection, USEPA.

This document provides state, local, and tribal water managers assistance in implementing the WHPA
provisions of the Safe Drinking Water Act. The basics of contaminant movement and ground water are
discussed, as are technical approaches to delineating WHPAs in different hydrogeologic settings.

Wuolo, R.W. Flow modeling for wellhead protection delineation. (Internet download, 1997)

The Minnesota Department of Health administers the management of WHPAs. Detailed information on ground
water velocity and direction, aquifer hydraulics, geology, well interference effects, and ground water-surface
water interaction is required for delineation of a WHPA. Most ground water models use existing information
which can easily be managed by geographic information systems. Model representation of the features is
designed to best simulate the various hydrologic conditions; in effect, modeling ground water flow. Calibration
improves the match between simulated and observed ground water flow characteristics. The model must also be
verified to further test its predictive capabilities, and a sensitivity analysis should be performed to evaluate
model uncertainty. Development and use of a ground water model for WHPA delineation is exemplified by the
North Dakota County Groundwater Model.

Case Studies

Bailey, Z.C. 1993. Hydrology of the Jackson, Tennessee area and delineation of areas contributing ground water
to the Jackson Well Fields. USGS Water-Resources Investigations Report 92-414, 54 pp.

A hydrologic investigation of the Jackson area in Madison County, Tennessee was conducted to provide
information for the development of a wellhead protection program for two municipal wellfields. Estimates of
hydraulic conductivity for the Memphis Sand range from 80 to 202 ft/d, and for the Fort Pillow Sand, from 68
to 167. Estimates of transmissivity of the Memphis Sand range from 2,700 to 33,000 sq ft/d, and for the Fort
Pillow Sand, from 6,700 to 10,050. A finite-difference, ground water flow model was calibrated to hydrologic
conditions of April 1989, and was used to simulate hypothetical pumping plans for the North and South Well
Fields. More than half the inflow to the system is underflow from the boundaries. Slightly less than half of the
inflow is from areal recharge and recharge from streams. About 75% of the discharge from the system is into
the streams, lakes, and out of the model areas through a small quantity of ground water underflow. The
remaining 25% is lost to pumping. A particle-tracking program was used to delineate areas contributing water
to the North and South Well Fields for the calibrated model and the three pumping simulations, and to estimate
distances for different times-of-travel to the wells. The size of the area contributing water to the North Well
Field, defined by the 5-year time-of-travel capture zone, is about 0.8 by 1.8 miles for the calibrated model and
pumping plan 1; 1.1 by 2.0 miles for pumping plan 2; and 1.6 by 2.2 miles for pumping plan 3. The size of the
area contributing water to the South Well Field is about 0.8 by 1.4 miles for the calibrated model, 1.6 by 2.2
miles for pumping plans 1 and 3, and 1.1 by 1.7 miles for pumping plan 2.

There are several numerical and analytical methods available to delineate contributing areas to public supply
wells. Each of these methods uses different levels of computational complexity and requires differing degrees of
data specification. Coupling particle tracking algorithms to numerical ground water flow models is a recent
advance in analyzing contributing areas. This method was demonstrated on the stratified drift aquifer on Cape
Cod, Massachusetts. The results were that: (1) the location of the recharge and discharge areas for the aquifer
with respect to the well has a significant effect on the size of the well's contributing area, (2) the pumping rate
of the well and the recharge rate of the aquifer has a great effect on the size of the well's contributing area, (3)
the determination of a well's contributing area must take into consideration all the wells within an aquifer, and
(4) the lithology of the aquifer must be characterized. The modeling produced similar results to the numerical

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modeling with particle tracking for wells pumping from a thin, single layer, uniform aquifer; it may not be
needed to delineate contributing areas in such an aquifer. For conditions encountered in the field, numerical
models with particle tracking are still better tools than analytical models. These conditions include thick
heterogeneous aquifers in which wells are pumped simultaneously and have complicated boundary conditions.
In these conditions, sufficient detail leading to an accurate determination of the land area that contributes water
to a well can not be provided by analytical models.

Begey, M.D., M. Cargnelutti, and E. Perastru. 1996. Ground water model for management and remediation of a
highly polluted aquifer (organo-chlorine compounds) in an urban area, using radioactive tracers (super(131)I)
for hydrodynamic parameters and dispersivity measurements. In: Isotopes in Water Resources Management
Vol. 2. Vienna (Austria). International Atomic Energy Agency, pp. 229-248.

Monitoring of pollution caused by TCE leakage from a broken sewage pipeline in an Italian chemical plant
utilized a mathematical model developed to evaluate the extent of pollution and to determine which other public
wells would become contaminated. Radioactive tracers were used to define wellhead protection areas.

Bogue, Kevin Scott. 1994. Evaluation of wellhead protection models; a case study, Xenia, Ohio. Wright State
University. Dayton, Ohio, 121 pp.

Delineation of one year travel time related capture zones was performed using numerical, analytical, and semi-
analytical models of a buried valley aquifer, along with stream function programs and particle tracking. The
results of each of these methods were used to determine their abilities to delineate wellhead protection areas.
The numerical flow model incorporates a three-dimensional steady-state finite-difference solution with leakage
to and from streams between the three model layers. The analytical flow model defines two-dimensional
transient drawdown surrounding a well in a leaky confined aquifer along with superposition of the regional flow
field using the Hantush-Jacob equation. The semi-analytical flow model uses the Theis equation, which
describes two-dimensional, transient drawdown surrounding a well in a fully confined aquifer, and
superposition of a regional flow field. The appropriate method to use requires a procedure that takes into
account the complexity of the hydrogeology, the amount of hydrogeologic data, and the required accuracy of
the results. Minimal data are available for this study. Questions arise as to whether it is more practical to use a
time intensive, accurate numerical model, or a less precise method which would save time and money but may
not accurately represent the flow system. Abilities of the flow models are determined using the one year capture
zones for each method. The results prove that the numerical model more accurately represents the flow system;
yet, the semi analytical and analytical models perform adequately in delineating capture zones. The analytical
method requires less time and effort than the numerical method. The analytical methods on the other hand, can
not be upgraded and improved as additional data are gathered.

Bowker, Joel A. 1993. A preliminary wellhead protection program for the village of Enon, Ohio. Wright State
University. Masters Thesis, 189 pp.

To protect its water supply, the village of Enon, Ohio is developing a wellhead protection/ground water
management program. The small community of Enon is located in northeastern Clark County and has a
population of approximately 2,000 people. Within the productive Mad River buried-valley aquifer are three
production wells. The composition of the aquifer is mainly permeable sand and gravel outwash of glacial-fluvial
origin. The aquifer is very prone to contamination due to its high conductivity and location of the water table
near the surface. To determine wellfield protection boundaries, GPTRAC and MONTEC models were used to
predict ground water flow. Protection boundaries for the wellfield were estimated using a one year time-of-
travel of ground water. Using this information, strategies and management plans are suggested for the town of
Enon to use in its selection of potential management options.

Bradley, M.D. and S.M.K. Bobiak. 1997. WHPA delineation methodology development for large wells
completed in stratified drift in Rhode Island. Journal of Soil Water Conservation, v. 52, no. 1, pp. 55-58.

Mathematical equations and hydrogeologic mapping methods were used in delineating wellhead protection
areas in Rhode Island. The identified areas will be used in future wellhead protection programs.

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Edson, D.F. 1989. Aquifer protection through large scale computer modeling. Protecting Ground Water from
the Bottom Up: Local Responses to Wellhead Protection. Proceedings of the Conference, October 2-3, 1989,
Danvers, Massachusetts. Underground Injection Practices Council, Oklahoma City, Oklahoma, pp. 119-121.

One of the largest aquifers in central and western Massachusetts is the Barnes Aquifer which covers the eastern
area of the City of Westerfield. The City of Westerfield developed a wellhead protection program and a series
of bylaws aimed at protecting the aquifer based on topography and surficial geology in 1985. In 1989, a more
thorough approach to delineating wellhead protection areas was enacted using large scale hydrogeologic
computer modeling. MODFLOW, a three-dimensional, finite difference model developed by the U.S. Geologic
Survey, was used for detailing wellhead protection areas. The modeled area was 14,000 feet by 32,000 feet
represented by a 33 by 70 grid. The node spacing was between 400 and 900 feet. Characteristics of the aquifer
incorporated into the model included: saturated thickness, aquifer permeability, initial head distribution,
storativity, till barrier boundaries, induced infiltration from surface water bodies, and pumping well
withdrawals. A USGS resources investigation of the area and City well testing records served as sources for the
data. Development of wellhead protection districts were done using criteria for Zone II in Massachusetts. Zone
II state guidelines include 180 days of continuous pumping with no recharge from precipitation.

A 48-square-mile area in the southeastern part of the Salt Lake Valley, Utah, was studied to determine if
generalized information obtained from geologic maps, water-level maps, and drillers' logs could be used to
estimate hydraulic conductivity, porosity, and the slope of the potentiometric surface: the three properties
needed to calculate average linear velocity of ground water. Estimated values of these properties could be used
by water management and regulatory agencies to compute values of average linear velocity, which could be
further used to estimate travel time of ground water along selected flow lines, and thus to determine wellhead
protection areas around public-supply wells. The methods used to estimate the three properties are based on
assumptions about the drillers' descriptions, the deposit!onal history of the sediments, and the boundary
conditions of the hydrologic system. These assumptions were based on geologic and hydrologic information
determined from previous investigations. The reliability of the estimated values for hydrologic properties and
average linear velocity depends on the accuracy of these assumptions.

Hydraulic conductivity of the principal aquifer was estimated by calculating the thickness-weighted average of
values assigned to different drillers' descriptions of material penetrated during the construction of 98 wells.
Using these 98 control points, the study area was divided into zones representing approximate hydraulic-
conductivity values of 20, 60, 100, 140, 180, 220, and 250 feet per day. This range of values is about the same
range of values used in developing a ground water flow model of the principal aquifer in the early 1980s.
Porosity of the principal aquifer was estimated by compiling the range of porosity values determined or
estimated during previous investigations of basin-fill sediments, and then using five different values ranging
from 15 to 35 percent to delineate zones in the study area that were assumed to be underlain by similar deposits.
Delineation of the zones was based on deposit onal history of the area and the distribution of sediments shown
on a surficial geologic map. Water levels in wells were measured twice in 1990, during late winter when ground
water withdrawals were the least and water levels the highest, and again in late summer, when ground water
withdrawals were the greatest and water levels the lowest. These water levels were used to construct
potentiometric-contour maps and subsequently to determine the variability of the slope in the potentiometric
surface in the area.

Values for the three properties, derived from the described sources of information, were used to produce a map
showing the general distribution of average linear velocity of ground water moving through the principal
aquifer of the study area. Velocity derived ranged from 0.06 to 144 feet per day with a median of about 3 feet
per day. Values were slightly faster for late summer 1990 than for the later winter 1990, mainly because
increased withdrawal of water during the summer created slightly steeper hydraulic-head gradients between the
recharge area near the mountain front and the wellfields farther to the west. The fastest average linear-velocity
values were located at the mouth of Little Cottonwood Canyon and south of Dry Creek near the mountain front,

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where the hydraulic conductivity was estimated to be the largest because the drillers described the sediments to
be predominantly clean and coarse grained. Both of these areas also had steep slopes in the potentiometric
surface. Other areas where average linear velocity was fast included small areas near pumping wells where the
slope in the potentiometric surface was locally steepened. No apparent relation between average linear velocity
and porosity could be seen in the mapped distributions of these two properties. Calculation of travel time along
a flow line to a well in the southwestern part of the study area during the summer of 1990 indicated that it takes
about 11 years for ground water to move about 2 miles under these pumping conditions.

Ginsberg, M. 1995. Applicability of wellhead protection area delineation to domestic wells: a case study. EPA-
813-B-95-007, 13 pp.

Wellhead protection for a community supplied by numerous private wells requires a different approach than
that for wellhead protection of PWS wells. The higher density of private wells within a community may cause
wellhead protection areas to overlap where hydrogeology is not sufficiently known and long ground water
travel times are needed to meet protection goals.

Golder Associates Inc., Oregon, and W.E. Nork. Nevada. 1992. Draft wellhead delineation demonstration
project for Conger Wellfield. Klamath Falls, Oregon.

A wellhead protection demonstration project was conducted at the Conger Wellfield in Klamath Falls, Oregon.
It is a prototype for determining if the State of Oregon Draft Guidance Document for Wellhead Protection Area
Delineation is adequate for determining WHPAs where the ground water source is a deep, fractured-rock
aquifer.

Golder Associates Inc. 1992. Demonstration of wellhead protection area delineation methods applied to the
Weyerhaeuser Wellfield Springfield, Oregon.

Using the Draft Guidance Document for Wellhead Protection Area Delineation developed by the Oregon
Department of Environmental Quality, the Springfield Utility Board in Springfield, Oregon, defined a wellhead
protection area at the Weyerhauser Wellfield. This wellfield supplies one third of the ground water supply
providing drinking water to Springfield area residents.

Hansen, C.V. 1991. Description and evaluation of selected methods used to delineate wellhead-protection areas
around public-supply wells near Mt. Hope, Kansas; Water Resources Investigation. USGS Report USGS/WRI-
90-4102.

The purpose of the report is to present evaluations of several methods that can be used to delineate wellhead-
protection areas. Others interested in delineating wellhead protection areas for wells under hydrologic
conditions similar to those near Mt. Hope, Kansas, can use these evaluations to assess (1) the appropriateness of
each method for the hydrologic conditions and (2) the types of information needed to apply each method. These
evaluations also may be used to facilitate the choice of method most suitable for the available resources.

Heath, Douglas L. 1995. Delineation of a refined wellhead protection area for bedrock public supply wells,
Charlestown, Rhode Island. USEPA.

This report describes the refined delineation of the WHPA of a wellfield of five public supply wells installed in
granitic bedrock in Charlestown, Rhode Island, approximately 32 miles southwest of Providence, Rhode Island.
The supply wells range in depth from 125 to 500 feet and pump from 6.6 to 40 gallons per minute.

Refined delineation of the 1992 Rhode Island Department of Environmental Management (RIDEM) WHPA
was performed using the 10-Step Method, which describes well location, regional and local flow patterns, well
discharge, aquifer properties, and conceptual and computer models. Because the wellfield aquifer is shallow,
medium-grained granite, in which ground water flows in discrete fracture sets, various diagnostic tests from
available information were made to determine its behavior as an equivalent porous medium, so that standard
analytic-element modeling and particle tracking could be applied for approximate capture-zone simulation of

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lateral and downgradient flow boundaries.

The revised WHPA for the wellfield was delineated in four stages: (1) Analyses of well discharge,
drawdown/recovery, and ground water quality data suggested that the Narragansett Pier Granite aquifer behaves
as an equivalent porous medium at the wellfield's scale of investigation; (2) performing transient capture-zone
modeling on all five supply wells to determine distances from the wells to downgradient and lateral boundaries;
(3) comparing these boundaries to the 200-foot radius circles of existing sanitary protection areas mandated by
the Rhode Island Department of Health, all lateral and downgradient capture zone boundaries were less than
200 feet from the supply wells; and (4) extending streamline flow boundaries upgradient from these areas and
normal to water-table altitude contours to the regional ground water divide, as determined by the U.S.
Geological Survey. Therefore, the final WHPA is delineated by the arbitrary fixed radius and hydrogeological
mapping methods and supported by distance and flow boundary criteria.

Based on the best available information, the refined wellhead protection area is approximately one-tenth the size
of that delineated by the RIDEM. In addition, despite this modified size, a portion of the waste cell of the
Charlestown Municipal Landfill apparently still lies within the refined WHPA. Other potential sources of
contamination are several individual septic disposal systems at residences upgradient of the wellfield.

Heath, Douglas L. 1993. The Wilton, N.H. wellhead protection area pilot project. USEPA.

This report describes the delineation of the WHPA of two municipal supply wells in Wilton, New Hampshire.
The size of the WHPA is approximately 0.52 square miles. The wellfield is located within the watershed of the
Souhegan River, a tributary of the Merrimack River. It consists of two gravel-packed supply wells pumping
from an unconfined, stratified-drift aquifer at a combined rate of approximately 8 million gallons per month.
The aquifer, which is bounded on the east and west by till and bedrock uplands up to 1,000 feet in altitude,
consists predominantly of fine sand to coarse cobbles and boulders laid down by the retreat of the Wisconsinan
ice sheet. Finer-grained deposits of silt and clay deposited by glacial ice or as lake deposits also occur locally.
These valley-fill materials are recharged by ground water inflow from surrounding highlands and also from
infiltration originating as precipitation or as surface water, especially near pumping wells.

The delineation criteria, criteria thresholds, and methods applied in the wellhead protection area meet or exceed
the requirements of the New Hampshire Department of Environmental Services (NHDES) Phase I Delineation
Guidelines of the NHDES Wellhead Protection Program. These criteria are distance and flow boundaries, used
in conjunction with the following combined methods: arbitrary-fixed radius, analytical modeling, and
hydrogeological mapping. One of the supply wells was also investigated for its potential to induce infiltration
and water-borne pathogens (including enteric viruses) from the Souhegan River, located 91 feet away from the
wellhead.

The information and techniques used to delineate the wellhead protection area are outlined as a ten-step process
performed in sequential order. This approach was found to be effective given New Hampshire's well-developed
hydrogeological data base and the specific requirements of the selected delineation methods.

Landmeyer, I.E. 1994. Description and application of capture zone delineation for a wellfield at Hilton Head
Island, South Carolina. USGS Water-Resources Investigation Report. USGS Report 94-4012, 33 pp.

Numerical and analytical ground water models were used for delineating capture zone boundaries for individual
pumping wells in a confined aquifer. Two-dimensional capture zone boundaries representing the extent of the
contribution of ground water to a pumped well were delineated by all the models used. Capture zones were then
evaluated on the ability of each model to represent realistically the portion of the ground water flow system that
contributes water to the pumped well. The fixed radius method is the basis for the analytical models. Also
included in the analytical models is the arbitrary radius model, the calculated fixed radius model based on the
volumetric flow equation with a time-of-travel criterion, and a calculated fixed radius method with drawdown
criterion derived from the Theis model. Two-dimensional, finite difference models RESSQC and MWCAP
were used for the numerical models. The Theis analytical model and the arbitrary radius method both delineated
capture zone boundaries that compared least favorably with the capture zones delineated using both numerical

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models and the volumetric-flow analytical model. More reasonable capture zones, parallel to the regional flow
direction, were produced by the numerical models than the volumetric-flow equation. The numerical model
RESSQC computed more realistic capture zones than the numerical model MWCAP by considering the effects
of multiple-well interference. Capture zones predicted by both numerical and analytical models indicate that the
current 100-foot radius of protection around a wellhead in South Carolina is much smaller than the ground
water capture for pumping wells in this particular wellfield in the Upper Floridan. The arbitrary fixed radius of
100 feet underestimated the upgradient contribution of ground water flow to a pumped well.

Moore, Beth A. 1993. Case studies in wellhead protection area delineation and monitoring. USEPA Report
600/R-93/107.

A methodology for planning and implementing a wellhead protection monitoring program is formulated and
demonstrated at unique case study sites. This methodology emphasizes saturated zone monitoring and is
intended to serve as a guide for wellhead protection program implementors. Careful implementation of this
methodology will enable managers and scientists to establish technically defensible, reliable, and effective
ground water monitoring programs for wellhead protection.

Basic hydrogeology concepts and equations are discussed as they pertain to ground water systems and flow,
conceptual hydrogeologic models and flow nets, and accurate delineation and monitoring in different
hydrogeologic settings. The spectrum of unconfined to confined aquifers is discussed in relation to porous,
granular aquifers; fractured-bedrock aquifers; and karst aquifers.

Physical and chemical parameter monitoring apply to wellhead protection. Three types of ground water
monitoring are useful in managing wellhead protection areas-ambient trend, source assessment, and early-
warning detection monitoring. Ambient trend monitoring detects the temporal and spatial trends in physical and
chemical quality of the ground water system. Source assessment monitoring evaluates the existing or potential
impacts on the physical or chemical ground water system from a proposed, active, or abandoned contaminant
source. Early-warning detection monitoring is conducted upgradient from the wellhead, based on known travel
times, to trigger a contingency response to prevent public exposure to contaminants in aquifers; they should not
be mistaken as preventative or remedial measures.

Noake, K.D. 1989. Fox (Borough) guarding the aquifer coop: local control at work. Protecting Ground Water
from the Bottom Up: Local Responses to Wellhead Protection. Proceedings of the Conference, October 2-3,
1989. Danvers, Massachusetts. Underground Injection Practices Council, Oklahoma City, Oklahoma, pp. 71-
101. 8 fig, 2 tab, 13ref.

Responding to local needs, the Town of Foxborough, Massachusetts wellhead protection strategy evolved over
a five year period. To delineate a wellhead protection area, one must know the hydrogeologic characteristics of
the aquifer, pumping rates of wells, and the recharge the aquifer receives. When Foxborough delineated its
wellhead protection areas, it also adopted a Water Resource Protection District bylaw in 1984. To update the
1984 bylaw and redefine the wellhead protection areas to follow the guidelines for delineating primary (Zone II)
and secondary (Zone III) aquifer recharge areas, a consultant was retained. A defensible wellhead protection
strategy was the goal. The recharge areas for 11 existing wells and 6 proven well sites were performed using
different approaches. Pumping tests were performed at the town's pumping stations using an automated data
gathering and processing system. This database was used in a aquifer simulation model using MODFLOW
which delineated the 17 wells' recharge areas. Computer programs were used to check the existing data in the
database. To determine nitrate loading in Zone II areas under maximum build-out conditions, a mass balance
nitrate loading model was utilized.

Osborne, T.J., J.L. Sorenson, M.R. Knaack, D.J. Mechenich, and MJ. Travis. Designs for wellhead protection
in central Wisconsin: Case studies of the town of Weston and City of Wisconsin Rapids. (Internet download,
1997)

These were the first studies to monitor wellhead protection areas in Wisconsin. Wellhead protection areas of the
City of Wisconsin Rapids and Town of Weston were examined specifically for defining zones of contribution

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(ZOC), mapping and acknowledging potential contaminant sources, and beginning management strategy plans
for use in implementing wellhead protection programs. Application of the uniform flow equation, taking into
consideration boundaries and the relationship between pumping rate and natural recharge, defined the zones of
contribution of the wellfields. Time of travel zones, inside the ZOC, were determined to present time of travel
of ground water from an area to the well. The ground water supply of Weston is in an alluvial sand and gravel
aquifer contaminated by hazardous material spills and underground fuel storage tanks. Numerous sources of
contamination in the zones of contribution exist in the municipal wells for both Weston and Wisconsin Rapids.

Rheineck, Bruce D. 1995. River-ground water interactions and implications for wellhead protection at Black
River Falls, Wisconsin. University of Wisconsin-Madison. Madison, Wisconsin, 133 pp.

Two municipal wells for the city of Black River Falls are located along the Black River, which flooded in June
1993. Unsafe levels of coliform and fecal coliform were detected in the drinking water under the municipal
wells. This study investigates potential sources of contamination using ground water and surface water
interactions. The objectives of this study were to: (1) identify sources of ground water and their contributions to
the municipal wells, and (2) determine distances from municipal wells based on travel time. A numerical
ground water model was calibrated using field and existing data from the municipal wellfield. Hydraulic
conductivity of the Quaternary sand and gravel aquifer was determined using slug tests, aquifer tests, and grain-
size analysis. Cambrian sandstone hydraulic conductivity was determined using specific capacity test data. The
aquifer at the site was thought to be above an impermeable basal silt unit of Precambrian granite and Archean
gneiss. After calibrating a steady-state flow model, the resulting steady-state parameters were used to calibrate a
transient model by varying storage parameters. Using travel time analysis from PATH3D, the water takes
approximately six months to travel from the Black River to the supply wells. There are three explanations for
the bacteria contamination: the flood waters were contaminated, the flood waters pushed contamination from
the unsaturated zone to the aquifer, or the contamination from an unknown location happened to coincide with
the flood. This study points to the first explanation, which would explain the detection of bacteria after the flood
and detection over time. Under the assumption of purely advective transport, the contamination will continue
until the supply wells are receiving water from areas other than the flood area. Analysis of travel time indicates
that this will take about five years.

Risser, D.W. and T.M. Madden. 1994. Evaluation of methods for delineating areas that contribute water to
wells completed in valley-fill aquifers in Pennsylvania. USGS/92- 635, 82 pp.

Valley-fill aquifers in Pennsylvania are the source of drinking water for many wells in the glaciated parts of the
State and along major river valleys. These aquifers are subject to contamination because of their shallow water-
table depth and highly transmissive sediments. The possibility for contamination of water-supply wells in
valley-fill aquifers can be minimized by excluding activities that could contaminate areas that contribute water
to supply wells. An area that contributes water to a well is identified in this report as either an area of diversion,
time-of-travel area, or contributing area. The area of diversion is a projection to land surface of the valley-fill
aquifer volume through which water is diverted to a well. The time-of-travel area is that fraction of the area of
diversion through which water moves to the well in a specified time. The contributing area, the largest of the
three areas, includes the area of diversion but also incorporates bedrock uplands and other areas that contribute
water. Methods for delineating areas of diversion and contributing areas in valley-fill aquifers, described and
compared in order of increasing complexity, include fixed radius, uniform flow, analytical, semi-analytical, and
numerical modeling. Delineated areas are considered approximations because the hydraulic properties and
boundary conditions of the real ground water system are simplified even in the most complex numerical
methods. Successful application of any of these methods depends on the investigator's understanding of the
hydrologic system in and near the wellfield and the limitations of the method. The hydrologic system includes
not only the valley-fill aquifer but also the regional surface-water and ground water flow systems within which
the valley is situated. As shown by numerical flow simulations of a wellfield in a valley-fill aquifer along Marsh
Creek Valley near Asaph, PA, water from upland bedrock sources can provide nearly all the water contributed
to the wells.

Robinson, J.L. 1995. Hydrogeology and results of tracer tests at the Old Tampa Well Field in Hillsborough
County, with implications for wellhead protection strategies in West-Central Florida. Water Resources

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Investigation. USGS Report 93-4171, 63 pp.

Using the old Tampa wellfield in northeastern Hillsborough County, Florida as a test site, evaluation of
wellhead-protection strategies was done for the Upper Floridan aquifer of west-central Florida. The upper 400
feet of the Upper Floridan responded to pumping with discharge rates of 450 to 1,000 gallons per minute.
Storage coefficient and transmissivity values of the Upper Floridan aquifer are 0.0001 and 23,000 feet squared
per day, respectively. Effective porosity values, determined from rock cores, ranges from 21 to 46 percent. A
fluorescent dye was used for the tracer tests. The tracer test results determined an effective porosity of 25
percent and a longitudinal dispersivity of 1.3 feet for the aquifer. Using the fluorescent dye to measure ground
water travel time, a particle tracking program was used to simulate ground water flow. Simulation of areas of
contribution was done for different wellhead protection strategies using the particle tracking program. Due to
the heterogeneity of the Upper Floridan aquifer, the use of uniform porosity models to delineate time-related
areas of wellhead-protection in the Upper Floridan karst aquifer is not appropriate. Movement of ground water
in the aquifer can be determined using these same uniform porosity models.

Schmidt, R.G., M.S. Beljin, R. Ritz, A. Field, and A. Zahradnik. 1991 Wellhead management modeling project,
final report project 661428, Montgomery County Phase III. The Center for Ground Water Management, Wright
State University, Dayton, Ohio.

This report incorporates data from a three phase wellfield management study to develop a ground water flow
system model for use in Montgomery County. Hydrogeologic data were gathered from government agencies
and the private sector and entered into a dBase III program for use in developing the model. The ground water
flow model is considered useful in predicting travel times of contaminants and definition of one and three year
wellhead protection areas.

USEPA. 1995. Tribal wellhead protection demonstration projects. EPA Report 813/R-95/001, Office of Water,
141 pp.

These case studies illustrate Tribal wellhead protection activities and highlight several concerns Tribes may
have in implementing wellhead protection. These concerns include: ground water recharge or wellhead
protection areas that are located outside the boundaries of Tribal reservations, interrelationship between ground
and surface water within the reservation, and difficulties in implementing or enforcing a program in the absence
of a Tribal judicial body.

USEPA. 1992. Development of a map and image processing system as decision support tool to local wellhead
protection. EPA Report 813/R-92/001, Office of Water, 117 pp.

The report documents the development and use of enhanced Geographic Information System (GIS) technology
to assemble a wide range of data for the protection of municipal public supply wellheads in Carroll County,
Maryland.

Walden, R. Ground water protection efforts in four New England states; Technical Report. 1988. EPA Report
EPA/600/9-89/084. Office of Cooperative Environmental Management, 154 pp.

The study evaluates local ground water and wellhead protection strategies in representative, but progressive
communities, in New England: Springfield, Vermont; Topsham, Maine; Merrimack, New Hampshire; North
Kingstown, Rhode Island. The case study method is employed on the premise that the lessons drawn from the
four communities will be useful to EPA and State agencies in providing guidance to other communities in the
region.

Land Use/Mapping/Geographic Information Systems (GIS)

Baker, Carol P., M.D. Bradley, and S.M.K. Bobiak. 1993. Wellhead protection area delineation: Linking flow
model with GIS. Journal of Water Resources Planning Management, v. 119, no. 2, pp. 275-287.

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An important part of the RIDEM ground water protection plan is the protection of areas contributing water to
public wells, also known as wellhead protection areas or WHPAs. The first step in wellhead protection is
WHPA delineation. A Uniform Flow analytical model is used with hydrogeologic mapping by RIDEM for
WHPA delineation around large supply wells in stratified drift. Variables for input into the model are calculated
using a geographic information system, which transforms the data into geographically referenced layers and
provides mylar overlays for the final hydrogeologic mapping of the WHPAs. WHPA maps and other
hydrogeologic data will be available to the communities and water suppliers and will be used by the Rhode
Island Wellhead Protection Program as the basis for planning of local wellhead protection.

Barnett, Christopher, Y. Zhou, S. Vance, and C. Fulcher. Wellhead protection area delineation for identifying
potential contamination sources. (Internet download, 1997).

This paper investigates using GIS to delineate WHPAs and identify contaminant sources. For this pilot project,
twenty-five wellheads are used for WHPA delineation. A GIS layer is generated for each WHPA, using
orthophotos which have a very limited set of land use categories. Base maps are produced for persons in each
community to use for ground surveys. At the local level, very highly detailed information is gathered and placed
on the maps. The GIS layers will be updated using these maps. Then, potential threats to public drinking water
within the area are determined using the GIS layer.

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recharge area near the mountain front and the wellfields farther to the west. The fastest average linear-velocity
values were located at the mouth of Little Cottonwood Canyon and south of Dry Creek near the mountain front,
where the hydraulic conductivity was estimated to be the largest because the drillers described the sediments to
be predominantly clean and coarse grained. Both of these areas also had steep slopes in the potentiometric
surface. Other areas where average linear velocity was fast included small areas near pumping wells where the
slope in the potentiometric surface was locally steepened. No apparent relation between average linear velocity
and porosity could be seen in the mapped distributions of

these two properties. Calculation of travel time along a flow line to a well in the southwestern part of the study
area during the summer of 1990 indicated that it takes about 11 years for ground water to move about 2 miles
under these pumping conditions.

Hendricks, Laurel Ann. 1992. Implementation of a wellhead protection program utilizing a Geographic
Information System. Rice University. Masters Thesis. Environmental Science. Also available through UMI
Masters Abstracts International, v. 31-01, p. 0256, 274 pp.

This report describes a research project in Harris County, Texas to develop a database for the City of Houston's
proposed wellhead protection program. GIS data were inputted from local, state, and federal agency sources and
linked with existing ground water models in order to delineate a wellhead protection area.

Kilborn, K., H.S. Rifai, and P.B. Bedient. The integration of ground water models with GIS. 1991. In:
Technical papers ACSM-ASPRS annual convention, Baltimore, Maryland, 1991. Publ. ACSM/ASPRS, pp.
150-159.

Presented in this paper is the development of an interface between a GIS database of ground water
characteristics in Houston, Texas and a WHPA model. The WHPA model calculates potential pollution source
zones which must be managed and monitored. The user can delineate wellhead protection areas for any
geographic boundary in Houston. First, the user updates the model with all information needed in the model
input file. Next, the user puts additional parameters in the model if needed. Finally, the geographic results from
the model are put in the database. This process is more efficient and effective than using paper maps and
overlays.

Muttiah, Ranjan Samuel. 1992. Neural networks in agriculture and natural resources: its application to the
wellhead protection area problem using GIS (Indiana, Vermont). Purdue University. Dissertation Abstracts
International, v. 54-0IB, 224 pp.

The general objective of this research was finding the system characteristics of agriculture and natural resources
that allow them to be easily studied using neural networks. Delineation of WHPAs using neural networks was
the specific objective. A new method, introduced in this research, delineates WHPAs based on numerical
simulations of a non-point source model. This model accounts for surface factors, as well as subsurface
conditions through saturated-flow-and-transport finite-element models. The simulations were performed for an
area known as the Indian Pine in Tippecanoe County, Indiana. Nitrogen concentration in the runoff volume
leaving a cell was determined using the non-point source surface model. Predictions of drawdown and
contaminant concentrations in the area near the water well were done using the saturated zone models for
different pumping and contaminant discharge rates. Using the numerical solutions, the WHPAs were delineated.
Manually delineated WHPAs were determined using a cascade-correlation neural network with Gaussian
hidden units. The network accurately remembered the WHPAs used in training.

Olimpio, J. C., E.G. Flynn, S. Tso, and P. A. Steeves. 1990. Use of a Geographic Information System to assess
risk to ground water quality at public supply wells, Cape Cod, Massachusetts. Water Resources Investigation.
USGS Report, 52 pp.

Ground water in the sole-source, sand and gravel aquifer on Cape Cod, Massachusetts, is plentiful and of
chemical quality suitable for public supply. However, the water quality is vulnerable to changing land use,
particularly the rapid conversion of undeveloped land to residential and commercial uses. Considerable efforts

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have been made to delineate wellhead protection areas around the approximately 60 public water supply wells
on Cape Cod and to assess risk to ground water quality from current and potential sources of contamination.
This report presents the results of a project that demonstrates GIS methods for assessing the risk to water
quality of public supply wells on Cape Cod, Massachusetts. Other project goals included the development of a
large scale computer data base at the establishment of a step-by-step approach for assessing risk, the delivery of
a set of specified GIS map products, and the establishment of a regional GIS data base for future use.

Rifai, H.S., L.A. Hendricks, K. Kilborn, and P.B. Bedient. 1993. GIS user interface for delineating wellhead
protection areas. Groundwater. v. 31, no. 3, pp. 480-488.

This paper presents a GIS modeling users' interface for delineating WHPAs around public supply wells.
Necessary information can be extracted from the built-in GIS database. The delineated WHPAs can then be
stored in the GIS database for future use. This interface provides local agencies with a tool for managing
WHPAs more efficiently and effectively, as is shown in a wellhead protection study for the city of Houston.
This modeling interface was used to delineate WHPAs for 202 public water supply wells. Sensitivity analysis
was performed to determine the effect of model parameter uncertainty on delineated WHPAs. Sources of
contamination within the delineated WHPAs were identified using the GIS database. Although GIS is a useful
tool, GIS requires a large investment in financial and human resources.

Analytical

Bair, E.S., C.M. Safreed, and E.A. Stasny. 1991. A Monte Carlo-based approach for determining traveltime-
related capture zones of wells using convex hulls as confidence regions. Groundwater. v. 29, no.6, pp. 849-855.

Designation of wellhead protection areas may be too hasty in cases in which determination of traveltime-related
capture zones of wells is made with a lack of site-specific values or there is a heterogeneous nature to the area.
This uncertainty in hydraulic and geologic parameters is used by a Monte Carlo simulation of the traveltime-
related capture zones. Traditional deterministic flow models do not take these parameters into account. One-
year capture zones, using percentile confidence regions from reverse tracked flowpaths from a well in a leaky-
confined aquifer in North Canton, Ohio, were determined from 100 randomly generated hydraulic conductivity
and effective porosity values in a Monte Carlo simulation. The mean of the lognormal distribution of hydraulic
conductivity was 3.89 ft/d while the average value from an aquifer test in log scale and the standard deviation
were both 1.0 ft/d. The effective porosity, using a normal distribution, had a mean value of 25% and standard
deviation of 3.5%. An analytical flow model was used in conjunction with a particle-tracking program to obtain
100 sets of endpoints for 36 reverse particle-tracked flowpaths emanating from the well. Using a distribution of
3,600 endpoints, wellhead protection areas were determined based on the 90th-percentile and 75th-percentile
confidence regions by deleting the 10 and 25 outlier endpoints. Determination of the convex hull of the
remaining endpoints was determined for delineation of wellhead-protection areas. The placement of the
remaining endpoints around the well and determination of likely flowpaths were used to analyze the best
locations of wells used to detect contaminants flowing toward the well.

Bolt, Walter Joseph. 1995. Delineation of a wellhead protection area for the village of Chelsea, Michigan, using
two dimensional steady-state MODFLOW. Eastern Michigan University. Masters Abstracts International, v. 34-
02, 191 pp.

For the village of Chelsea's municipal wellfield, four separate wellhead protection areas were delineated for 1,
5, 10, and 20 year time-of-travel distances with MODFLOW-MODPATH. The municipal wells for Chelsea are
within a leaky confined glacial drift aquifer which contains considerable amounts of coarse sand and gravel.
From the ground surface to about 20 feet below grade, geologic materials consist of silty clay till. From 20 to 40
feet below grade, the composition of the geologic materials is sand and gravel. Silty clay is below the confined
aquifer. A two-dimensional steady-state MODFLOW model was developed using hydrogeologic data and water
levels from 21 residential wells. The particle tracking program MODPATH was then used to process the
calibrated MODFLOW model. Using 1, 5, 10, and 20 year time-of-travel distances for the wellhead protection
areas resulted in delineated areas of approximately 0.44, 1.71, 2.84, and 3.37 square miles, respectively.

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Bradbury, K.R. and M.A. Muldoon. 1994. Effects of fracture density and anisotropy on delineation of wellhead
protection areas in fractured-rock aquifers. Applied Hydrogeology. v. 2, no. 3, pp. 17-23.

Many wellhead protection investigations in fractured-rock aquifers assume that the aquifer approximates a
porous medium at the same scale as the wellhead protection area. Theoretical explanations and criteria have
been used for determining when to employ the porous media approximation. However, most of these criteria
require extensive field work for validation. To test when it is appropriate to delineate the capture zone of a well
drilled in fractured rock, using the assumption of porous media equivalence, experiments were conducted with
Rouleau's two-dimensional discrete fracture flow model coupled with a particle-tracking code focusing on the
effects of anisotropy and fracture density on capture zone delineation. Even in densely fractured aquifers, the
zone of contribution calculated by the fracture-flow model is much larger than the capture zone predicted by the
porous-media-based models.

Cole, Bryce Evan. 1996. Impact of hydraulic conductivity uncertainty on capture zone delineation (wellhead
protection, contaminant transport). University of Notre Dame. UMI, Doctoral Abstracts International, v. 56-
07B, 185 pp.

Delineating capture zones, assuming a homogeneous hydraulic conductivity field, does not take into account the
accurate definition of the area supplying water to a well in a set time period needed for pump-and-treat systems
and wellhead protection plans. A Monte Carlo simulation of the hydraulic conductivity distribution is used, in
this study, to determine time-related capture zones and the variability of regional gradient estimates.
Identification of capture zone boundaries is accomplished using the steady-state flow model MODFLOW and a
fourth order Runge-Kutta integration along with reverse particle tracking. The pumping scenarios include both
regional flow domination and flow conditions dominated by pumping. Observations included: (1) estimation of
the regional hydraulic gradient using a 3-point scheme showed high uncertainty in the heterogeneous
conductivity field; (2) the flow lines did not generally follow the mean regional gradient to passive wells or
even straight line flow paths to the well under pure pumping conditions; (3) those correlation directions not
aligned with the mean of the regional gradient resulted in deviations in the orientation of average flow paths
using a mean regional gradient; (4) travel time variation from a few areas exceeded two orders of magnitude;
and (5) with greater distances to the well, a decrease in the probability that points upgradient of the well would
be included in the capture zone was determined. The Monte Carlo analysis results indicate that heterogeneous
hydraulic conductivity fields complicate wellhead protection programs or plans for sampling networks. Future
characterization to reduce uncertainty would, in most cases, be prohibitive in cost. It is suggested that safety
factors be considered for estimating travel time to a wellhead or delineation of a capture zone area. Using the
results of this study, safety factors greater than ten may be good enough for most cases.

Edson, D.F. 1989. Aquifer protection through large scale computer modeling. Protecting Ground Water from
the Bottom Up: Local Responses to Wellhead Protection. Proceedings of the Conference, October 2-3, 1989,
Danvers, Massachusetts. Underground Injection Practices Council, Oklahoma City, Oklahoma, pp. 119-121.

One of the largest aquifers in central and western Massachusetts is the Barnes Aquifer which covers the eastern
area of the City of Westerfield. The City developed a wellhead protection program and a series of bylaws aimed
at protecting the aquifer based on topography and surficial geology in 1985. In 1989, a more thorough approach
to delineating wellhead protection areas was enacted using large scale hydrogeologic computer modeling.
MODFLOW, a three-dimensional finite difference model developed by the U.S. Geologic Survey, was used for
detailing wellhead protection areas. The modeled area was 14,000 feet by 32,000 feet represented by a 33 by 70
grid. The node spacing was between 400 and 900 feet. Characteristics of the aquifer incorporated into the model
included: saturated thickness, aquifer permeability, initial head distribution, storativity, till barrier boundaries,
induced infiltration from surface water bodies, and pumping well withdrawals. A USGS resources investigation
of the area and City well testing records served as sources for the data. Development of wellhead protection
districts were done using criteria for Zone II in Massachusetts. Zone II state guidelines include 180 days of
continuous pumping with no recharge from precipitation.

Grubb, S. 1993. Analytical model for estimation of steady-state capture zones of pumping wells in confined and
unconfined aquifers. Groundwater. v. 31, no. 1, pp. 27-32.

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Capture zone analysis is a useful tool when designing pumping systems and wellhead protection programs. By
using discharge potentials, equations were derived for application to confined, unconfmed, or combined
confined and unconfmed aquifers. These transient equations can not be solved explicitly. Steady-state
equations, on the other hand, have been formulated and can be solved. The equations define an area in which, in
theory, all the water in the aquifer eventually reaches the pumping well. However, these equations fail to
account for effects of hydrodynamic dispersion. Also, equations were formulated for finding the stagnation
point, upgradient divide, and dividing stream line. These equations were applied to an example problem. The
capture zones were similar when the calculations of both a confined and an unconfmed aquifer were compared.
The formulated equations are useful for a fast analysis of a pumping system and the properties in the aquifer
even though they do not take into account hydrodynamic dispersion. Although many of the assumptions restrict
its application to many sites, solving of small geohydrologic problems could be a benefit of the analysis
presented here.

Haitjema, H.M., J. Wittman, V. Kelson, and N. Bauch. 1994. Wellhead Analytic Element Model (WhAEM):
program documentation for the wellhead analytic element model. EPA Report /600/R-94/210, 131 pp.

The WhAEM demonstrates a new technique for the definition of time-of-travel capture zones in relatively
simple geohydrologic settings. The WhAEM package includes an analytic element model that uses
superposition of (many) analytic solutions to generate a ground water flow solution. WhAEM consists of two
executables: the preprocessor Geographical Analytic Element Preprocessor (GAEP), and the flow model
Capture Zone Analytic Element Model (CZAEM). WhAEM differs from existing analytical models in that it
can handle fairly realistic boundary conditions such as streams, lakes, and aquifer recharge due to precipitation.
The preprocessor GAEP is designed to simplify input data preparation; specifically, it facilitates the interactive
process of ground water flow modeling that precedes capture zone delineation. The flow model CZAEM is
equipped with a novel algorithm to accurately define capture zone boundaries by first determining all stagnation
points and dividing streamlines in the flow domain. No models currently in use for wellhead protection contain
such an algorithm.

Hall, J.C. 1989. Use of time of travel in zone of contribution delineation and aquifer contamination warning.
Protecting Ground Water from the Bottom Up: Local Responses to Wellhead Protection. Proceedings of the
Conference, October 2-3, 1989. Danvers, Massachusetts. Underground Injection Practices Council, Oklahoma
City, Oklahoma, pp. 137-143.

Determining the zone of contribution for water supply wells has typically depended on using specified
drawdown data. Advances in computer modeling allow for the determination of both drawdown and travel time
also. It is more advantageous to use travel time determination instead of drawdown due to the freedom from
sloping piezometric surfaces, accounting for high permeability strata in the aquifer, proper inclusion of recharge
from nearby low-permeability areas, and delineation of where monitoring should take place. The model must
account, at each node, for all significant strata and permeabilities. This is of particular importance for glacial
sediments. There are two-dimensional models available regarding head field output that can accept differences
in stratigraphy at every node. This is preferable to the strictly two-dimensional models, such as PLASM, or
three-dimensional models requiring too many layers. If possible, the grid should cover the entire watershed of
the aquifer. In calibrating time of travel models, permeability should be adjusted only to levels consistent with
geologic data. Errors in geologic interpretation often signal problems with calibration. For most cases in time of
travel modeling, more input is required than in simple flow modeling.

Degradation of ground water quality results when effluent from septic tank drainfields encroaches on ground
water and contaminates water supplies. Development of a model was undertaken to assist planners in the
unsewered area of central Wisconsin to reduce the risks of contamination of water supplies from septic systems.
The model can handle three-dimensional transient flow in an unconfmed homogeneous aquifer of infinite areal
extent with a regional horizontal gradient. Results of the model are in good agreement with other numerical and

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analytical models. Due to the applicability to larger scale problems, this model could be a welcome addition to
the U.S. Environmental Protection Agency's Wellhead Protection Program.

Kraemer, S.R., H.M. Haitjema, and O.D.L. Strack. 1994. Capture zone modeling using the WhAEM. EPA
Report /600/A-94/109, 9 pp.

A new computer modeling package has been developed through a cooperative agreement between Indiana
University, the University of Minnesota, and the U.S. Environmental Protection Agency for the determination
of time-of-travel capture zones in relatively simple geohydrological settings. The WHAEM package includes an
analytic element model that uses superposition of (many) closed form analytical solutions to generate a ground
water flow solution. WhAEM consists of two executables: the preprocessor GAEP and the flow model
CZAEM. WHAEM distinguishes itself from existing analytical models in that it can handle fairly realistic
boundary conditions such as streams, lakes, and aquifer recharge due to precipitation. GAEP is designed to
simplify input data preparation, specifically to facilitate the interactive process of ground water flow modeling
that supports capture zone delineation. CZAEM is equipped with a novel algorithm to accurately define capture
zone boundaries by determining all stagnation points and dividing streamlines in the flow domain.

Morrice, Joseph Nathan. 1997. Wellhead protection area delineation: evaluation of an analytic solution under
parameter uncertainty. University of Nevada. Masters Thesis. UMI Masters Abstracts International, v. 35-04, 86
pp.

Time dependent capture zone analysis is commonly used in determining wellhead protection areas. One method
used for delineating capture zones is a two-dimensional analytic solution for a pumping well in a homogeneous
aquifer with a regional gradient. This method requires true estimates of the representative mean values for
hydraulic parameters. A probabilistic approach to capture zone delineation has been developed by incorporating
uncertainties in the hydraulic parameter estimates into the analytic solution. To evaluate the effectiveness of this
method, three comparisons were undertaken: the first involved analyzing capture zones resulting from different
input statistics, the second used Monte Carlo simulations, and the third involved a capture zone delineated in
practice using three data sets based on published data. It was determined that there was a reliance on the
uncertainty in transmissivity and the direction of regional flow. By including uncertainty, the calculated capture
zone overlayed most or all of the field capture zone using two data sets, whereas the capture zones determined
without using uncertainty in the analytical solution did not detect large parts of the field capture zone.

Responding to local needs, the Town of Foxborough, Massachusetts wellhead protection strategy evolved over
a five year period. To delineate a wellhead protection area, one must know the hydrogeologic characteristics of
the aquifer, pumping rates of wells, and the recharge the aquifer receives. When Foxborough delineated its
wellhead protection areas, it also adopted a Water Resource Protection District bylaw in 1984. To update the
1984 bylaw and redefine the wellhead protection areas to follow the guidelines for delineating primary (Zone II)
and secondary (Zone III) aquifer recharge areas, a consultant was retained. A defensible wellhead protection
strategy was the goal. The recharge areas for 11 existing wells and 6 proven well sites were performed using
different approaches. Pumping tests were performed at the town's pumping stations, using an automated data
gathering and processing system. This database was used in an aquifer simulation model using MODFLOW
which delineated the 17 wells' recharge areas. Computer programs were used to check the existing data in the
database. To determine nitrate loading in Zone II areas under maximum build-out conditions, a mass balance
nitrate loading model was utilized.

Ramanarayanan, T.S., D.E. Storm, and M.D. Smolen. 1995. Seasonal pumping variation effects on wellhead
protection area delineation. Water Resources Bulletin, v. 31, no. 3, pp. 421-430.

The main feature of the wellhead protection programs for drinking water supplies is the delineation of WHPAs.

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Very often, WHPAs are delineated using idealized steady-state assumptions, leading to an incorrect estimation
of area and geometry. Results presented in this paper compare a commonly used steady-state method with a
more complex transient assumption allowing seasonal variations in pumping rates. A transient procedure is also
introduced for time-related capture zone delineation using a numerical flow and transport model. A ten year
time-of-travel assumption is employed for examining wellhead delineation for two municipal wells in Tipton,
Oklahoma. GPTRAQ, a semi-analytical model, was used assuming constant pumping rates, for the steady-state
procedure along with MOC, a numerical model. The capture zone estimated by GPTRAQ has the same shape as
the capture zone estimated by MOC but they are of different sizes due to the different solution schemes. MOC
was used for the transient method incorporating seasonal variations in pumping rates. The capture zones
delineated by the steady-state procedure were much smaller than those predicted by the transient procedure
using the same model. Also, the transient procedure predicted higher drawdown than the steady-state procedure
which explains the larger capture zones.

Sahl, Barbara L. 1994. A comparison of wellhead protection area delineation methods at Larimore, North
Dakota. Masters Thesis. University of North Dakota. Grand Forks, ND, 177 pp.

Shallow aquifers provide many communities in North Dakota with water which is susceptible to contamination.
Delineation of WHPAs is one of the strategies to protect the ground water supplies. Five delineation methods
were evaluated in Larimore, North Dakota. All five methods were tested for sensitivity to recharge, hydraulic
conductivity, specific yield, and porosity. Circular WHPAs are produced using arbitrary (APR) and calculated
fixed radius (CFR) methods. The CFR varies only with porosity and the APR uses no site-specific data.
RESSQC and GPTRAC, semi-analytical models, generate WHPAs using well and aquifer data and particle
tracking. MODFLOW/SURFER/GWPATH (MSG) connects a numerical flow model (M), with a contouring
program (S), and a particle-tracking program (G). The head distribution from a cone of depression generated
from MODFLOW is combined with a digital map for input into GWPATH. MSG produced the closest
representation of the aquifer/well system and was assumed to produce the most accurate WHPAs. Neither of the
fixed radius methods was accurate for the Larimore site. RESSQC

and GPTRAC, without recharge, generated WHPAs that were too large. With recharge, GPTRAC generated
WHPAs most similar to those produced by MSG and is probably accurate for the simple aquifer system at
Larimore.

Shafer, J.M. and M.D. Varljen. 1992. Coupled simulation-optimization approach to wellhead protection area
delineation to minimize contamination of public ground water supplies. In: The 20 Anniversary Conference
on Water Management in the '90s, Seattle, Washington, May 5, 1992 . Reprinted in Water Resources Planning
and Management and Urban Water Resources, 1993. Publ. ASCE, New York, NY, pp. 567-570.

A determination of the steady-state pumping rates for individual wells (in a wellfield containing multiple wells)
that results in the fewest number of potential contaminant sources in the wells' time-period capture zones was
done using a loosely coupled simulation-optimization procedure. In order for the total wellfield pumping rate to
meet the wellfield demand, the nonlinear, unconstrained optimization problem is solved with a conjugate
direction search algorithm.

USEPA. 1993. Wellhead protection in confined, semi-confined, fractured and karst aquifer settings. EPA
Report/810/K-93/0012, 10pp.

Protection areas around wells producing from confined, fractured, and karst aquifers are, because of their
complex hydrogeology, more difficult to define than protection areas for wells in porous media settings. The
document provides background information explaining the need to define protection areas for wells that draw
public drinking water from several complex hydrogeologic settings: confined, semi-confined, fractured, and
karst aquifers. These settings include aquifers in which the ground water is not open to the atmosphere, or the
aquifer does not consist of unconsolidated porous media. Several figures illustrate these settings in a general
way.

van der Heijke, P. and M.S. Beljin. 1988. Model assessment for delineating wellhead protection areas. Final

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Report. EPA Report /440/6-88/002, 271 pp.

The document offers a compilation of ground water computer flow models potentially applicable to wellhead
protection area delineation. It contributes information on existing ground water flow and contaminant transport
and fate models that may be considered for use in these delineations. Each of the 64 personal computer models
described was rated with respect to applied quality assurance, user-friendliness, accessibility, portability, and
modificability.

Varljen, M.D. and J.M. Shafer. 1993. Coupled simulation-optimization modeling for municipal ground water
supply protection. Groundwater. v. 31, no. 3, pp. 401-409.

A technique has been developed to protect municipal water supplies from potential contamination through
capture zone management using a numerical ground water flow model and unconstrained nonlinear
optimization. This technique combines nonlinear programming with finite difference ground water flow
modeling and travel time calculations. The reason for using this method is to determine pumping rates for wells
in a wellfield that will minimize the potential risks of contamination while maintaining the total output of water
from the wellfield. Features of this technique include the incorporation of realistic boundary conditions, the
treatment of complicated aquifer configurations, and the use of spatially varying aquifer properties depending
on the availability of site-specific data. This method improves upon the conventional wellhead protection and
delineation approaches by achieving a greater level of protection. Protection improvement is achieved through
essentially nullifying the effects of potential contaminant sources in capture zone analysis, instead of reducing
the threat of these sources. This technique was tested at a site in Pekin, Illinois and in a hypothetical ground
water system.

Varljen, M.D. and J.M. Shafer. 1991. Assessment of uncertainty in time-related capture zones using conditional
simulation of hydraulic conductivity. Groundwater. v. 29, no. 5, pp. 737-748.

Presented is a time-related, steady-state, stochastic capture zone analysis based on conditional simulation of
hydraulic conductivity. A conditional simulation of hydraulic conductivity preserves the measured and spatial
correlation of the hydraulic conductivity field while presenting the most representative results by optimization
of the use of available data. A test problem, with a water supply well, was formulated to find, using stochastic
analysis, the uncertainty in the one year and ten year capture zones of the well. The influence of hydraulic
conductivity values on the 'zone of uncertainty' of the capture zone as a function of time of travel and direction
of regional flow is demonstrated in the results. Monte Carlo techniques are used to determine uncertainty in the
delineation of time-related capture zones based on uncertainty in hydraulic conductivity. This method makes
optimum use of the available data by using not only the data values but also their corresponding spatial
attributes. The problems associated with implementing the conditional analysis have been answered by testing
this technique on a hypothetical ground water flow domain with a simulated pumping well. Using this
demonstration, estimates of ranges in uncertainty in the sizes and layouts of time-related capture zones that arise
from incomplete knowledge of hydraulic conductivity can be estimated adequately using this technique.

Wilson, J. and G. Achmad. 1995. Delineation of wellhead protection areas using particle tracking analysis and
hydrogeologic mapping, northern Anne Arundel County, Maryland. Report of Investigations - Maryland
Geological Survey, v. 61, 121 pp.

The report compares two computer modeling techniques used to delineate WHPAs for the public supply wells
of northern Anne Arundel County. The first technique involves using the U.S. Geological Survey MODFLOW
program along with the 1989 version of the U.S. Geological Survey MODPATH program, a particle tracking
code. The alternative technique is performing particle tracking using the semi-analytical module called
GPTRAC in the WHPA code (version 2.1) from the U.S. Environmental Protection Agency. Using
hydrogeologic mapping, an 'aquifer vulnerability map' is developed. Although the overall water quality of the
Lower Patapsco aquifer is good, contaminants are present in the more vulnerable regions of the aquifer. Without
remediation, upgradient sources of contamination pose a threat to the presently unused Glendale and Sawmill
wellfields.

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Wuolo, R.W., DJ. Dahlstrom, and M.D. Fairbrother. 1995. Wellhead protection area delineation using the
analytic element method of ground water modeling. Groundwater. v. 33, no. 1, pp. 71-83.

Delineation of wellhead protection areas was done using the Analytic Element Method of ground water
modeling for proposed and existing wells in Brooklyn Park, Minnesota. This was accomplished by simulating
steady-state flow in the Franconia-Ironton-Galesville aquifer and the water table aquifer. Delineation was
performed using ground water time-of-travel as the delineation criterion. The solution produced by the Analytic
Element Method includes local scale and regional scale features in the same solution. This allowed for
simulation of the city wells in relation to the regional flow field. The Single Layer Analytic Element Model
(SLAEM) was used for developing and calibrating separate models. Each of these separate models was linked
together using the Multi-Layer Analytic Element Model (MLAEM). Wellhead protection areas and ground
water travel time zones were delineated using reverse particle tracking for the existing wells.

Yeh, G.T., S. Sharp-Hansen, B. Lester, and Strobl. 1992. Three-Dimensional Finite Element Model of Water
Flow Through Saturated-Unsaturated Media (3DFEMWATER)/Three-Dimensional Lagrangian-Eulerian Finite
Element Model of Waste Transport Through Saturated-Unsaturated Media (3DLEWASTE): numerical codes
for delineating wellhead protection areas in agricultural regions based on the assimilative capacity criterion.
EPA Report A500/R-92/223, 254 pp.

Two related numerical codes, 3DFEMWATER/3DLEWASTE, are presented that can be used to delineate
wellhead protection areas in agricultural regions using the assimilative capacity criterion. 3DFEMWATER
(Three-dimensional Finite Element Model of Water Flow Through Saturated-Unsaturated Media) simulates
subsurface flows, whereas 3DLEWASTE (Hybrid Three-dimensional Lagrangian-Eulerian Finite Element
Model of Waste Transport Through Saturated-Unsaturated Media) models contaminant transport. Both codes
treat heterogeneous and anisotropic media consisting of as many geologic formations as desired, consider both
distributed and point sources/sinks that are spatially and temporally dependent, and accept four types of
boundary conditions-i.e., Dirichlet (fixed-head or concentration), specified-flux, Neumann (specified-pressure-
head gradient or specified-dispersive flux), and variable. The variable boundary condition in 3DFEMWATER
simulates evaporation/infiltration/seepage at the soil-air interface, and, in 3DLEWASTE, simulates mass
infiltration into or advection out of the system. 3DLEWASTE contains options to model adsorption using a
linear, Fruendlich, or Langmuir isotherm, plus dispersion, and first-order decay.

Numerical/Modeling

Banton, O., P. Lafrance, and J.P. Villeneuve. 1992. Delineation of wellhead protection area in an agricultural
zone by using solute transport modeling. Rev. Sci. EAU. v. 5, no. 2, pp. 211- 227.

When delineating wellhead protection areas, certain ideas need to be considered: zones of influence encircling
the well, recharge areas, flow paths, transport velocities, sources of contamination, types of contamination, and
travel times. For site-specific examples of wellhead protection areas, a defined analytic method must be
employed. When using quantitative criteria, mathematical simulation models are often used as the only method
capable of defining wellhead protection areas.

Guiger, N. and T. Franz. 1991. Development and application of a wellhead protection area delineation computer
program. Water Science and Technology, v. 24, no. 11, pp. 51-62.

A ground water flow code with pathline analysis is FLOWPATH, which can calculate hydraulic head
distributions, pathlines, travel times, and velocities using a steady-state flow simulation. Time-related capture
zones and pumping well drawdown distributions also are calculated. Case studies were performed on the Vega
Alta Superfund Site in Puerto Rico, and for a town in Massachusetts. FLOWPATH was used to determine that
proposed capture zones of remediation wells would not be sufficient to contain the future migration of
significant amounts of trichloroethylene in Puerto Rico. At the Massachusetts site, it was determined that
contaminants released within the watershed of a nearby pond would eventually contaminate the wellhead.

Harmsen, E.W., J.C. Converse, and M.P. Anderson. 1991. Application of the Monte Carlo simulation procedure

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to estimate water-supply well/septic tank-drainfield separation distances in the Central Wisconsin Sand Plain.
Journal of Contaminant Hydrology JCOHE6. v. 8, no. 1, pp. 91-109.

A three-dimensional groundwater contaminant tracking model was used to estimate the mean and standard
deviations of both the necessary separation distances and the minimum well depth between a water supply well
and a septic tank drainfield, based on conditions found in the Central Wisconsin sand plain. Sensitivity analysis
of Monte Carlo simulations identified horizontal hydraulic conductivity, anistrophy ratio, and horizontal
regional gradient as the most important factors.

Johanson, Mary Giglio. 1992. Delineation of time-related capture zones with estimates of uncertainty using
conditional simulation of hydraulic conductivity and numerical modeling. University of New Orleans. Masters
Thesis. New Orleans, LA, 163 pp.

The most reliable method for defining wellhead protection areas is using particle tracking analysis to determine
numerical time-related capture zones. Aquifer parameter estimates, required by this method, can be sources of
error in capture zone delineation. This study uses a stochastic approach to calculate the one-year, five-year, and
ten-year capture zones around a municipal wellfield with estimates of capture zone configuration and extent.
Variogram analysis was used to assess the spatial distribution of the hydraulic conductivity field. Uncertainty of
capture zone delineation was determined using statistical analysis of model results. This study concluded that
the technique outlined can be used to estimate time-related capture zones around a municipal wellfield.

Outlaw, James. 1995. A ground water flow analysis of the Memphis Sand Aquifer in the Memphis, Tennessee
Area. Ground Water Institute: The University of Memphis. (Internet download, 1997).

The towns of Arlington and Collierville in Shelby County along with the cities of Memphis, Germantown,
Millington, and Bartlett in Tennessee depend completely on ground water for their drinking water. An
important part of the protection process of the ground water supply is understanding the aquifer system in West
Tennessee. A flow model of the primary aquifer in the Memphis area known as the Memphis Sand aquifer, was
developed using the USGS model, MODFLOW. An earlier regional-scale flow model developed by the Ground
Water Institute at the University of Memphis served as the basis for this model. The final model was calibrated
using December, 1991 conditions and verified using information from 1992 and 1993. Leakage from the
surficial aquifer was estimated using the model. The flow model, already calibrated, was run to a steady-state
solution, and capture zones within the municipal wellfields in Shelby County were delineated using the USGS
model MODPATH. EPA WHPA model results were compared to the capture zones predicted by MODFLOW
and MODPATH. Approximately 31% of the total pumping from the Memphis Sand aquifer, predicted by the
model, could possibly be attributed to leakage originating in the surficial aquifer. About 19% is taken from
storage, especially in the eastern and southeastern portion of the county where the Memphis Sand aquifer
should be treated as an unconfined unit. The Memphis Sand aquifer recharge area to the east (and lesser
amounts from other directions) provides the source of the remaining water that enters the Memphis area. Also,
the model indicates more information is needed about the flow system in the Memphis area to fully
understand it.

USEPA. 1997. Numerical codes for delineating wellhead protection areas in agricultural regions based on the
assimilative capacity criterion. EPA Report /600/R-92-223.

The 3DFEMWATER/3DLEWASTE are related numerical codes that can be used together to model flow and
transport in three-dimensional, variably-saturated porous media under transient conditions with multiple
distributed and point sources/sinks. Thus, these models can be used to apply the assimilative capacity criterion
to the development of wellhead protection areas, as each state in the U.S. is required to do under the 1986
Amendments to the Safe Drinking Water Act. The complexity of the 3DFEMWATER/3DLEWASTE numerical
models requires that they be used by experienced numerical modelers with a strong background in
hydrogeology.

Hydrogeologic/Geologic Analysis

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Bhatt, K. 1993. Uncertainty in wellhead protection area delineation due to uncertainty in aquifer parameter
values. Journal of Hydrology, v. 149, no. 4, pp. 1-8.

Studies have been done on the importance of modeling in hydrogeologic investigations. A parameter analysis is
essential to determining whether a model is applicable to the hydrogeologic setting. A parametric analysis was
performed to determine the effect of data uncertainty on delineation of WHPAs. The most important factor in
WHPA delineation is the precision of aquifer parameter values and their relationship to the model itself. To test
effects of different values in a wellfield model, a modified version of the time-related analytical ground water
flow model RESSQC was used to determine capture zone boundaries and delineate contaminant fronts for
injection wells. Aquifer parameters, measured in a shallow aquifer, were used in this analysis.

Caswell, B. 1990. River Recharge. Water Well Journal, v. 44, no. 11, pp. 34-37.

Delineation of WOT As and determination of the connection between ground water and surface water were the
major issues for a Vermont community that decided to replace an existing municipal well. A geohydrologic
investigation of the aquifer was required by state regulations as a part of constructing a new well. Using test
boring and test pumping information, the results showed that the nearby Connecticut River provides significant
recharge to the ground water source, but a brook adjacent to the well site does not. This determination requires
small amounts of land purchase or land use zoning by the community due to the high transmissivity of the
glacial stream aquifer and the coupling of the aquifer with the Connecticut River. However, river water quality
should be addressed at the state level.

Frederick, William T. 1991. Hydrogeology of the Onondaga Limestone and Marcellus Shale in Central New
York's Finger Lake region with emphasis in well-head protection and pollution potential. State University of
New York. Buffalo, NY. Masters Thesis, p. 212.

To implement wellhead protection , the New York State Health Department will mandate the delineation of
three zones around municipal wellfields: ZOC, zone of influence (ZOI), and the watershed tributary to the ZOC.
The unconfined, fractured Onondaga Limestone and the Marcellus Shale aquifer system serve as the main water
supply for the Village of Shortsville, New York. These ground water sources are contaminated by the
community they supply. A MODFLOW simulation is performed to help develop protection plans. Fractures,
horizontal bedding plains, joints, vertical fractures and joints, slumpfold induced fractures, pop-up induced
fractures, and Paleo-ground water surface fluctuations serve as the sources of the secondary permeability within
the Onondaga Limestone and Marcellus Shale. In some areas, the Pleistocene deposits overlie the bedrock and
in other areas lie within the saturated thickness of the aquifer. It is these deposits, made up of outwash,
alluvium, kame deposits, variably textured tills, and moraines, that define the rates at which pollutants migrate
to the bedrock aquifer. Wellhead protection zones around the Village wellfield are delineated. A regional
ground water protection plan can be implemented by incorporating (1) point source locations of contamination,
(2) hydrogeologic properties of these sites, and (3) locations of point sources of contamination in relation to
wellhead protection zones. Such a plan includes ground water pollution potential maps showing areas with low
pollution potential and high hydrologic efficiency.

Gadt, Jeff W. 1994. Hydrogeology and hydrochemistry of the east-central portion of the Salt Lake Valley, Utah,
as applied to wellhead protection in a confined to semiconfined aquifer. Utah State University. Logan, Utah,
151pp.

Numerical and analytical methods are used to delineate drinking water source protection zones Two and Three,
which are based on hydrogeologic time-of-travel data and recharge data acquired through the use of
hydrogeochemical and hydrogeologic techniques. The findings of this research are: (1) the hydrogeology is
much more complex than previously thought. This was determined through the use offence diagrams and
hydrostratigraphic diagrams; (2) horizontal ground water flow velocities are low at the site, which is indicated
by the recovery rate of water in the monitoring wells due to pumping of the target well; (3) the deepest of the
three water-bearing zones is not well connected to the upper two zones as indicated by interpretation of major
ions relative to the depth of the highest open interval on various sample wells; (4) the chemical makeup of the
westernmost of three flowpaths indicates there is a change from calcium bicarbonate to sodium-sulfate water;

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(5) total-dissolved-solids contents from samples of water recharged from the southern Wasatch mountains are
lower than in those samples of water recharged from the northern Wasatch mountains; (6) sources of recharged
water must be evaluated on an individual basis with regards to the sample wells; (7) wells located farthest into
the valley have the lowest tritium values; (8) determined through Carbon 14 dating, the ground water is between
1,300 and 1,500 years old; and (9) the risk of contamination of the target well site is low in terms of the 15-year
travel time.

lost, Donald J. 1994. Hydrogeology and pollution potential of aquifers, Doylestown, Wayne County, Ohio.
University of Akron. Masters Thesis, 177 pp.

A primary wellhead protection program was designed for the municipal wellfield in Doylestown using the
geologic and hydrogeologic data of northeastern Wayne County. The wellfield, on top of Pennsylvanian Sharon
Sandstone, is just west of the village. This formation provides drinking water for some homes in the area but the
aquifer providing the bulk of the water is the Rittman Sandstone/Armstrong Siltstone of the Mississippian
Cuyahoga Formation. Approximately 2.5 miles south of Doylestown is Chippewa Creek, underlain by a buried
valley. This buried valley contains permeable sand and gravel that may be a future ground water source for the
village. Four hydrogeologic settings are within the Glaciated Central Region (DRASTIC designation) where
Doylestown is located: (7Aa) glacial till over bedded sedimentary rocks, (7Ad) glacial till over sandstone, (7Ac)
glacial till over shale, and (7D) buried valley. Using pumping tests, the average transmissivity of bedrock
aquifers is determined to be about 3500 gpd/ft. Pennsylvanian sandstones have moderate conductivities (2.1-21
gpd/ft), and conductivities of the Cuyahoga Formation are low to moderate (0.021-2.1 gpd/ft). The Bradbury-
Rothschild computer program compared well with these hydraulic parameters. Also, wellhead protection areas
were delineated for 1 yr, 2 yr, 5 yr, 10 yr, and 20 yr times-of-travel using the fixed-radius method. DRASTIC
indexes from 74 to 163 and pesticide indexes between 88 and 184 were determined using the DRASTIC
system.

Paillet, F.L.and W.H. Pedler. 1996. Integrated borehole logging methods for wellhead protection. The 1993 36
Annual Meeting of the Association of Engineering Geologists, San Antonio, TX. Engineering Geologists, v. 42,
no. 2-3, pp. 155-165.

Models depend on accurate descriptions of the aquifer so reliable contaminant travel times can be determined in
order to define a protection area. Applications of multiple geophysical measurements to ground water flow in
the wellhead protection area are adapted to alluvial, fractured sedimentary, and fractured crystalline rock
aquifers. Obtaining data from a single test well cannot indicate large-scale flow paths. A number of observation
boreholes, with geophysical and hydraulic measurements, can indicate large-scale flow paths, and are also very
useful in defining aquifer properties for wellhead protection studies.

Pesti, Geza. 1993. Geoelectrics and geostatistics for characterizing ground water protection zones (Kriging,
Aquifer protection). University of Nebraska. Doctoral Abstracts International, v. 54-04B, 160 pp.

A series of tools are presented in this dissertation for characterization of the protection and yield of ground
water reservoirs. Traditional measuring techniques, such as well logs, specific capacity, and pump tests, are
supplemented with geophysical observations. There are four main sections to the dissertation. In the first
section, a method is presented for defining aquifer properties of low conductivity subsurface layers. Mapping of
the thickness of a protective clay layer is achieved using cokriging of data estimated from electrical resistivity
data and well data. In the second section, a procedure is presented for mapping travel times to existing wellhead
protection areas. A fixed protection zone is assumed around each well for travel time calculations. The third
section describes a method for delineation of areas for new wells using the yield of the wells and protection
zone effectiveness as criteria. This method is developed for leaky aquifer settings. The protection zone
effectiveness is best characterized by corresponding travel times. Composite programming, a multi-criteria
decision making technique, is used to determine the most sensible well locations. Section four discusses
selecting the most optimal water supply well locations in an area using observation network design. This
method uses measurement network alternatives which combine wells and geoelectric measurements. All the
methods are presented using actual data.

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Quinlan, J.F., J.A. Ray, and G.M. Schindel. 1995. Intrinsic limitations of standard criteria and methods for
delineation of ground water-source protection areas (springhead and wellhead protection areas) in carbonate
terrains: critical review, technically-sound resolution of limitations, and case study in a Kentucky karst. In:
Karst geohazards: engineering and environmental problems in karst terrain. Proceedings 5 conference,
Gatlinburg, pp. 525-537. Beck, B.F. Editor.

A Ground Water Source Protection Area in Mississippian limestones is delineated with the use of tracer-test
results in this case study. The study illustrates the necessity of tracer-test results for delineating a Ground Water
Source Protection Area in the karst over and above the use of computer modeling.

Teutsch, G. and B. Hofmann. 1990. The delineation of ground water protection zones using forced gradient
tracer tests: a model validation case study. In: Calibration and reliability in ground water modeling, The Hague,
pp. 351-360.

The study compared direct measurements observed from a gradient test covering the ZONE II area and
delineation of the ZONE II area as calculated from a large scale hydraulic test. The case study examines a new
waterworks which is planned for the Rhine Valley near Karlsruhe in the city of Southwest Germany. A two
dimensional regional model was linked with a local scale three dimensional model to determine ground water
flow and transport. Depending on the type of data used, examples include tracer or hydraulic test data, the
ZONE II area estimates can differ by more than 100%.

Violette, P. 1987. Surface geophysical techniques for aquifer and wellhead protection area delineation.
Technical Report. Final. EPA Report 7440/12-87/106, 63 pp.

Surface geophysical techniques developed by the petroleum and minerals industries are applicable to ground
water investigations. The document examines some of these techniques to aid in the delineation of aquifers as
part of the delineation of wellhead protection areas. Techniques reviewed include seismic, electrical,
electromagnetic induction, very low frequency (VLF) resistivity, ground penetrating radar, gravity, and
magnetic geophysical techniques, and their applicability to aquifer delineation. The theory and methodology of
these are discussed, along with costs as of early 1987. Also briefly discussed is the delineation of wellhead
protection areas.

Welhan, J. and C. Meehan. 1994. Hydrogeology of the Pocatello Aquifer: implications for wellhead protection
strategies. In: Hydrogeology, waste disposal, science and politics. Proceedings of 30 symposium on
engineering geology and geotechnical engineering, Idaho, pp. 1-18.

The southern wellfield is located on a shallow strip aquifer (1:6 width:length aspect ratio) comprised of sorted
fluvial gravels. The wellfield is also bounded by low permeability regions laterally. The linear velocities range
from 6 to 60 ft/day and the transmissivities range from 0.1-10 ft/day. Longer pumping well capture zones are a
result of high ground water flow velocities with ground water time of travel over a one year period on the order
of kilometers. Design of wells to intercept the ground water flow is assisted by the rapid linear migration of
ground water.

Miscellaneous

Jacobson, E., R. Andricevic, and T. Hultin. 1994. Wellhead protection area delineation under uncertainty. U.S.
Department of Energy. Nevada Field Office, 81 pp.

The Nevada Test Site (NTS) is currently using 14 water supply wells. Of the 14 wells, 11 are being used as
potable water supplies and the three additional wells are used strictly for construction purposes. This study
estimates WHPAs for each water-supply well at the NTS. Since there was limited information about the
hydraulic properties used for estimating WHPAs, a plan for considering the uncertainty in estimating the
hydraulic properties was created and used.

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Pesti, G., I. Bogardi, and W.E. Kelly. 1994. Risk-based wellfield design combining different source of data.
Future Ground Water Resources at Risk, pp. 255-270.

Hydraulic conductivities and layer thicknesses, measured from well-logs and well-performance tests, are
predicted and mapped for determination of well yield and travel times. Layer thicknesses, hydraulic
conductivities, and total travel times, in conjunction with estimated yields, are treated as spatially random
variables. Simulated hydraulic conductivities and thicknesses are used to determine expected value maps of
specified reliability for yield and total travel-time. Combinations of yield and travel time maps, developed using
composite programming, are determined using trade-off maps. The trade-off relationship incorporates the
methodology of well yield versus wellhead protection. The incorporation of this method is enacted at an area
close to Ashland, Nebraska.

Ramanarayanan, Tharacad Subramanian. 1995. Evaluation of existing wellhead protection strategies for
controlling nonpoint source nitrate pollution. Oklahoma State University. Doctoral Abstracts International, v.
56-09B, 232 pp.

The purpose of this research is to study nonpoint source pollution to ground water due to leaching of nitrate
from agricultural fields. To control agricultural nonpoint source nitrate pollution, existing time-of-travel and
assimilative capacity criteria are used for WHPA delineation. The study area was Tipton, Oklahoma.
Delineation of a ten year capture zone was performed using a transient ground water flow and transport model.
A volume mass balance was used to study the effectiveness of the WHPA. Water flux in the saturated zone was
determined using a numerical flow model. In the root zone, nitrate and water fluxes were approximated using a
root zone hydrologic-water quality model. The WHPA for the Tipton municipal wells was updated using a
different method of delineating WHPAs which encompasses nonpoint source pollution. The conclusions are
that the existing wellhead protection criteria do not effectively account for the nitrate pollution. Even after
implimentation of best management practices and elimination of agriculture within the WHPA, the Tipton
WHPA did not meet the drinking water standards. In the Tipton WHPA, the resultant nitrate concentration
using the alternative procedure meets the drinking water quality standards.

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