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.



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.

Wuolo, R.W., D.J. 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
/600/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.

27



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. Journal of Contaminant Hydrology. v. 8, no. 1, pp.
71-90.

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 unconfined homogeneous aquifer of infinite areal extent with a regional
horizontal gradient. Results of the model are in good agreement with other numerical and 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 CLAEM. 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

23



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.

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.





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.

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
acommunity 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.



eri i
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 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

28



TABLE OF CONTENTS |

Blandford, Neil T. 1990. Semi-analytical model for the delineation of wellhead
protection areas: Version 2.0. .......... 06. .c cece eee Pete e eee ee eee 2

Caswell, B. 1992. Protecting fractured-bedrock wells. ......... 00.02. 0ec cece eee 2

Cleary, T.C. and R.W. Cleary. 1991. Delineation of wellhead protection areas:
theory and practice. 2.2.0... cece cece cece eeeeees 2

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. ..............00.0. ecu eeeee 3

Livingstone, S., T. Franz, and N. Guiger. 1995. Managing ground water

resources using wellhead protection. »..........0. 20.200. c cece cece e ee eee 3
McElwee, C.D. 1991. Capture zones for simple aquifers. ........0...0.00..00005 3
Miller, D.W. Principles of ground water protection. ........ 0.0 .eccecceeeeececee 3

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. ............0.00.00000- 4

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

Center. 2... cece cece een es nceteeeueennrene 4
USEPA. 1993. Guidelines for delineation of wellhead protection areas. .:.......... 4
USEPA. 1993. Wellhead protection workbook. ...2....00.00. cc cece ceecceeeeee 4
USEPA. 1991. Delineation of wellhead protection areas in fractured rocks. ......... 5



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 accom-
plished 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.

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, unconfined, or combined confined and unconfined 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

21



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.
Underground Injection Practices Council, Oklahoma City, Oklahoma, pp. 145-166. 11 fig, 1
tab, 12 ref.

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 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

7



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, 13 ref.

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 M.J. 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 (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.

13°



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
Il in Massachusetts. Zone II state guidelines include 180 days of continuous pumping with no
recharge from precipitation. :

Freethey, G.W., LE. 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. USGS Water Resources
Investigations Report: 92-4085. :

A 48-square-mile area in the southeastem 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 depositional 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 depositional 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

9



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 unconfined 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
4600/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.



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 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



TABLE OF CONTENTS (continued)

between a contaminant source and a partially penetrating water-supply
Bo 23

Kraemer, S.R., H.M. Haitjema, and O.D.L. Strack. 1994. Capture zone modeling
using the WhAEM. 1.0.0... 00 cee cece eee eee nee e eens 23

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. 2.0.0... 0... cece cece cee ete tenet e eee eee 24

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. ....... 2.0.0.0 eee ee eee eee eee 25

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. 2.6.6... eee cece cece tenet eee 25

Varljen, M.D. and J.M. Shafer. 1993. Coupled simulation-optimization modeling
for municipal ground water supply protection. ............-. sees eee ee eee 26

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.



Olimpio, J. C., E.C. 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 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. Bédient. 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 ina
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 fi/d while the average value from an aquifer test in log scale and the standard
deviation were both 1.0 fi/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

19



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.

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.

Bamett, 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.



TABLE OF CONTENTS (continued)

Page

time of ground water in the principal aquifer underlying the southeastern

part of Salt Lake Valley. 22... 2... 0 eee ccc cece ete e eee ee 9
Ginsberg, M. 1995. Applicability of wellhead protection area delineation to

domestic wells: acase study. ..... 20.0... eee c cece eee e cece eevee 10
Golder Associates Inc., Oregon, and W.E. Nork. Nevada. 1992. Draft wellhead

delineation demonstration project for Conger Wellfield. ...............0.4 10
Golder Associates Inc. 1992. Demonstration of wellhead protection area

delineation methods applied to the Weyerhaeuser Wellfield Springfield,

Oregon. .. 6... eee cnc c eee ene teen ene e eet eenee 10

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.

See ee cee eee een e een ede e eee ee reeset eeeee -1l
Landmeyer, J.E. 1994. Description and application of capture zone delineation :
for a wellfield at Hilton Head Island, South Carolina. ............0.0.0005 12
Moore, Beth A. 1993. Case studies in wellhead protection area delineation and
monitoring . ©... . 2... cece eee e nce e ne eeee 12

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. ........2 00. e cee 13

Rheineck, Bruce D. 1995. River-ground water interactions and implications for
wellhead protection at Black River Falls, Wisconsin. ..............0..004 14

vii



TABLE OF CONTENTS (continued)

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. ............ 6

Wuolo, R.W. Flow modeling for wellhead protection delineation. ..............655 6

Bailey, Z.C. 1993. Hydrology of the Jackson, Tennessee area and delineation of
areas contributing ground water to the Jackson Well Fields. ................ 6

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. ...........2022005 7

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. ........:-.-..+.5 7

Bogue, Kevin Scott. 1994. Evaluation of wellhead protection models; a case
study, Xenia, Ohio. ............ 0.00 eee eee

Bowker, Joel A. 1993. A preliminary wellhead protection program for the village
of Enon, Ohio. ..... 22.0... c eee eee eee eee eee e tees 8

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

vi



(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
unconfined, fractured-rock aquifers.

USEPA. 1991. Protecting local ground water supplies through wellhead protection. EPA Report
/570-09-91/007, 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 unconfined 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 Sor 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.



TABLE OF CONTENTS (continued)
Page

Olimpio, J. C., E.C. Flynn, S. Tso, and PA. Steeves. 1990. Use of a Geographic
Information System to assess risk to ground water quality at public supply
wells, Cape Cod, Massachusetts. ........00. 0000 cece eceeeeeeeeeceees 19

Rifai, H.S., L.A. Hendricks, K. Kilborn, and P.B. Bedient. 1993. GIS user
interface for delineating wellhead protection areas. ...........0.00.0.0008 19

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. ©... . 20... 2.2 cece eee eee ee ceeeeaes 19

Bolt, Walter Joseph. 1995. Delineation of a wellhead protection area for the
village of Chelsea, Michigan, using two dimensional steady-state
MODFLOW. ........ 06.0.0 b cece cece cece cece ete e ee eceeeeene 20

Bradbury, K.R. and M.A. Muldoon. 1994. Effects of fracture density and
anisotropy on delineation of wellhead protection areas in fractured-rock
aquifers. 22.0... e teen ecneeeee 20

Cole, Bryce Evan. 1996. Impact of hydraulic conductivity uncertainty on capture
zone delineation (wellhead protection, contaminant transport) .............. 20

Edson, D.F. 1989. Aquifer protection through large scale computer modeling.
Protecting Ground Water from the Bottom Up: Local Responses to
Wellhead Protection. .... 0.2.0.2. e eee cece eee c eee e eee 21

Grubb, S. 1993. Analytical model for estimation of steady-state capture zones of
pumping wells in confined and unconfined aquifers. ..............000.00- 21

Haitjema, H.M., J. Wittman, V. Kelson, and N. Bauch. 1994. Wellhead Analytic
Element Model (WhAEM): program documentation for the wellhead
analytic element model. 2... 00... eee ccc cece eeneeeees 22

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. .:..........0.....0. 22

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



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 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 US.
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 approxi-
mately 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

11



& EPA

United States .
Environmental Protection Office of Water EPA 816-R-98-021

“Agency (4606) December 1998

LITERATURE REVIEW
OF METHODS FOR
DELINEATING
WELLHEAD
PROTECTION AREAS



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.



TABLE OF CONTENTS (continued)

Gadt, Jeff W. 1994. Hydrogeology and hydrochemistry of the east-central
portion of the Salt Lake Valley, Utah, as applied to wellhead protection in
aconfined 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. ................-.0005 Loc c cece eeeees 32

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

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

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



TABLE OF CONTENTS (continued)
: : Page

Yeh, G.T., S. Sharp-Hansen, B. Lester, and Strobl. 1992. Three-Dimensional
Finite Element Model of Water Flow Through Saturated-Unsaturated
Media (3 DFEMWATER)/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. ..... 27

Banton, O., P. Lafrance, and J.P. Villeneuve. 1992. Delineation of wellhead
protection area in an agricultural zone by using solute transport modeling... . 28

Guiger, N. and T. Franz. 1991. Development and application of a wellhead
protection area delineation computer program. ..............0.0.000.0% 28

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. ....28

Johanson, Mary Giglio. 1992. Delineation of time-related capture zones with
estimates of uncertainty using conditional simulation of hydraulic
conductivity and numerical modeling. .............. 000: e cece cece eeee 28

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 ............ 29

eologic/Geologic Analysis ......... 2... cece ccc e cece cece cece eeeeneeeees 29

Bhatt, K. 1993. Uncertainty in wellhead protection area delineation due to
uncertainty in aquifer parameter values... 2.2.00. 00.0000 ccc e cece cence 29

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 ..............0.0-0.cce eee 30



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 WHPAs 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 (ZOJ), 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 incorporat-
ing (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.



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.

Kilbom, 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. 54-01B, 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.



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. USGS Water Resources
Investigations Report: 92-4085.

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 depositional 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 depositional 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, 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

17.



TABLE OF CONTENTS (continued)

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. ............++- 15

USEPA. 1992. Development of a map and image processing system as decision
support tool to local wellhead protection. .......-. 60+ e sees cence eee eee 16

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

Ta]

Baker, Carol P., M.D. Bradley, and S.M.K. Bobiak. 1993. Wellhead protection
area delineation: Linking flow model with GIS. ...........-..2--20e eee 16

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 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. 2.2.2.0... eee eect e eee 17

Hendricks, Laurel Ann. 1992. Implementation of'a wellhead protection program
utilizing a Geographic Information System. ..........0. 60 cc cece cece eens 18

Kilborn, K., H.S. Rifai, and P.B. Bedient. The integration of ground water models
with GIS. 2... eee e eee e eens 18

Muttiah, Ranjan Samuel. 1992. Neural networks in agriculture and natural
resources: its application to the wellhead protection area problem using
GIS (indiana, Vermont). ..... 0.0... 18



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 semianalytical 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.

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

8



were tested for sensitivity to recharge, hydraulic conductivity, specific yield, and porosity. Circular
WHPAs are produced using arbitrary (AFR) and calculated fixed radius (CFR) methods. The CFR
varies only with porosity and the AFR 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. i

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, 10 pp.

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 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.

25



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

26



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

14





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 /440/12-87/106, 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 fi/day and the transmissivities range from 0.1-10
fi/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.

i meous

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.

33



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, 151 pp.

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 of fence 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; (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.

Jost, 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,
(7Aq) 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.

31



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 ji) | GEOBASE
c) BASICBIOSIS kK GEOREF (2 different versions)
d) _ BiolAgrindex 1)‘ PERABS
e) Articlelst m) PapersFirst
f) WORLDCAT n) ReadGuideAbs
g) GenSciAbstract 0) NewsAbs
h) _—*DISS p) EBSCO
@ DIALOG
1) 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 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.



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 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 méchanics involved, areas of contribution can be
mapped and controls, such as limitations on land use, can be imposed.



LITERATURE REVIEW OF
METHODS FOR DELINEATING
WELLHEAD PROTECTION AREAS



sets, whereas the capture zones determined without using uncertainty in the analytical solution did
not detect large parts of the field capture zone.

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, 13 ref.

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. 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

24



(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-bome 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, J.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 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

12





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 90"-percentile and 75"-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.

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

20



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.

Hydroge: i logic Analysis

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

29



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 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, deter-
mined 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 watet 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.

15



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.

xiii



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 areal 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
awellfield. 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.