U.S. Department of the Interior 

U.S. Geological Survey

U.S. ENVIRONMENTAL PROTECTION AGENCY REGION 1 

WASTE MANAGEMENT DIVISION

Construction and Calibration of Numerical 

Ground-Water-Flow Models of the 

Western Half of the Milford-Souhegan 

Glacial-Drift Aquifer, 

Milford, New Hampshire

By Philip T. Harte, Robert H. Flynn, am/Thomas J. Mack

Open-File Report 99-462

Pembroke, New Hampshire 

1999
U.S. DEPARTMENT OF THE INTERIOR 

BRUCE BABBITT, Secretary

U.S. GEOLOGICAL SURVEY 

Charles G. Groat, Director

The use of firm, trade, and brand names in this report is for identification purposes only and does 

not constitute endorsement by the U.S. Geological Survey.

For additional information write to:

District Chief

U.S. Geological Survey

New Hampshire/Vermont District

361 Commerce Way

Pembroke, NH 03275-3718

or through our website at 

http://nh.water.usgs.gov

Copies of this report can be purchased 

from:

U.S. Geological Survey 

Information Services 

Box 25286 

Federal Center 

Denver, CO 80225
CONTENTS

Abstract........................................................................................................_^ 1

Introduction..................................................................................................................................................................^ 1

Purpose and Scope ...................................................................................................................................................... 4

Hydrogeologic Setting ................................................................................................................................................ 4

Acknowledgments....................................................................................................................................................... 4

Construction of Numerical Models....................................................................................................................................... 5

Grid Design................................................................................................................................................................. 5

Time Discretization........................................................... 7

Hydraulic Conductivity .............................................................................................................................................. 7

Storage Properties....................................................................................................................................................... 13

Boundary Conditions................................................................................................................................................... 14

Recharge...................................................................................................................................................................... 14

River-aquifer Interactions............................................................................................................................................ 16

Ground-water Withdrawals......................................................................................................................................... 16

Calibration of and Performance Criteria for Numerical Models........................................................................................... 20

Steady State ................................................................................................................................................................ 21

Transient Seasonal....................................................................................................................................................... 21

Evaluation of Selected Model Parameters ............................................................................................................................ 23

Boundary Conditions................................................................................................................................................... 23

Recharge...................................................................................................................................................................... 24

Hydraulic Conductivity .............................................................................................................................................. 27

River-aquifer Interactions............................................................................................................................................ 30

Storage Properties....................................................................................................................................................... 32

Results of Simulations with Final Calibrated Model........................................................................................................... 35

Steady State................................................................................................................................................................. 35

Transient Seasonal....................................................................................................................................................... 38

Summary and Conclusions.................................................................................................................................................... 44

Selected References......................................................... 45

Appendix 1. List and description of model-input files for the ground-water-flow models of the

Milford-Souhegan glacial-drift aquifer, Milford, New Hampshire......................................................................... 47

Appendix 2. Information on well construction (sorted by well number) for selected wells................................................ 51

Appendix 3. Observed ground-water levels for selected wells in the Milford-Souhegan glacial-drift aquifer ................... 61

Appendix 4. Information on well construction (sorted by easting location) for selected wells .......................................... 65

Appendix 5. Ground-water-level hydrographs showing an example of the comparison between modelcomputed head and observed head from wells MW14B (well number 341) and MW10A (well number 316)..... 75

PLATES

1. Map showing locations of ground-water wells, test borings, river-gaging stations, and subbasins 

in the Milford-Souhegan glacial-drift aquifer, Milford, New Hampshire [In pocket]

2. Map showing numerical grid of the western part of the Milford-Souhegan glacial-drift aquifer, [In pocket]

Contents III
FIGURES

1-8. Maps showing:

1. Location of the Milford-Souhegan glacial-drift aquifer, Milford, New Hampshire.......................................... 2

2. Extent of contaminant plume (as defined by 10 parts per billion [ppb] line of equal concentration) 

of total volatile organic compounds in 1989 (A), and altitude of water-table surface, in feet above mean 

sea level in April 1994 (B)................................................................................................................................ 3

3. Areas of inactive and active grid cells, simulated river cells, and location of general-head

boundary (A), and grid cells (B), for model of the Milford-Souhegan glacial-drift aquifer............................. 6

4-8. Initial and final input of active areas and horizontal hydraulic conductivity zones for model layers:

4. Initial input for layer one (A), and final input for layer one (B)....................................................................... 8

5. Initial input for layer two (A), and final input for layer two (B)....................................................................... 9

6. Initial input for layer three (A), and final input for layer three (B)................................................................... 10

7. Initial input for layer four (A), and final input for layer four (B)...................................................................... 11

8. Initial input for layer five (A), and final input for layer five (B)....................................................................... 12

9. Graph showing river stage specified in model cell row 81 and column 13 for the transient-seasonal model .......... 17

10. Maps showing concentration of tetrachloroethylene (PCE) in 1989 (A), and 1994 (B)............................................ 22

11. Maps showing advective transport of ground water from areas corresponding to the leading edge

of the contaminant plume for the 1988 model of the entire Milford-Souhegan glacial-drift aquifer (A),

and 1994 model of the western half of the same aquifer (B)..................................................................................... 25

12. Graph showing model-computed heads for low, medium, and high monthly recharge rates from the

transient-seasonal simulation with the observed water levels at well MW-10B (well number 317, plate 1)............. 26

13. Graph showing computed river seepage from the transient-seasonal simulation for subbasin 4............................... 28

14. Map showing steady-state simulation of advective transport of ground-water particles showing pathlines

from high zones of contamination to final discharge locations.................................................................................. 29

15. Graphs showing model-computed river seepage for base riverbed conductance (A), ten-fold increase 

in riverbed conductance (B), difference in base value and ten-fold increase (C), and location map of 

simulated reach (D).................................................................................................................................................... 31

16. Map showing differences in simulated head for a two-fold increase in riverbed conductance.................................. 33

17. Graph showing transient model-computed heads at well MI-18 from simulated seasonal fluctuations in

river stage................................................................................................................................................................... 34

18. Graph showing transient-seasonal model-computed heads at well MI-18 from simulations of aquifer storage....... 34

19. Map showing head residuals (differences) between steady-state computed heads and observed heads calculated

from the arithmetic mean of the biweekly measured water levels............................................................................. 36

20. Diagram showing cross section of steady-state advective transport of ground-water particle showing

pathline projected along row 80................................................................................................................................. 37

21. Map showing steady-state advective transport of ground-water particles showing pathlines from

1,000 ppb line of equal concentration of PCE in 1989 (overlay A), and 1994 PCE concentrations (overlay B),

to discharge locations in 1994.................................................................................................................................... 39

22. Map showing triangular groupings of biweekly measured wells for determination of model-computed

and observed ground-water hydraulic gradients ........................................................................................................ 41

23. Graph showing ground-water gradients in relation to positioning of the water-table surface for triangle A............ 42

24. Graphs showing model-computed river seepage between river gaging stations PI and P2 for transient-seasonal

simulation (A), and measured river leakage for the same reach (B).......................................................................... 43

TABLES

1. Ground-water withdrawals from currently used commercial and industrial water-supply wells,

Milford, New Hampshire ........................................................................................................................................... 5

IV Contents
2. Estimates of ground-water recharge from a water-balance model of the Milford-Souhegan glacial-drift

aquifer and water-level-accretion technique for long-term observation well MI-18 (MOW-36, well number 29).... 15

3. Assigned values of riverbed leakance (hydraulic conductivity divided by riverbed thickness) to

models of flow............................................................................................................................................................ 17

4. Simulated ground-water withdrawals for stress periods in simulations..................................................................... 18

5. Differences between computed steady-state heads and observed mean heads from biweekly

measurements (June 1994 to June 1995).................................................................................................................... 27

6. Seasonal precipitation, amount of recharge from precipitation, and percent of precipitation recharged................... 27

7. Rates of river leakage for increases in riverbed conductance..................................................................................... 30

8. Volumetric budget for the steady-state simulation (1994-95).................................................................................... 35

9. Summary of river seepages from steady-state simulations and measured river leakages in subbasins...................... 37

10. Volumetric budget from June 1994-95 from the transient-seasonal simulation......................................................... 40

11. Differences between computed seasonal mean heads and observed seasonal mean heads from the

transient-seasonal-model simulation.......................................................................................................................... 40

12. Statistics from model-computed and observed direction and slope of maximum ground-water

hydraulic gradients from triangular grouping of wells, June 1994-June 1995........................................................... 40

CONVERSION FACTORS, VERTICAL DATUM, AND ABBREVIATIONS

Multiply By To obtain

inch (in.)

foot (ft)

mile (mi)

square mile (mi2)

cubic foot (ft3)

gallon (gal)

million gallons (Mgal)

inch per month (in/m)

inch per year (in/yr)

foot per mile (ft/mi)

cubic foot per second (ft3/s)

cubic foot per second per square mile [(ft3/s)/mi2)]

gallon per minute (gal/min)

million gallons per day (Mgal/d)

million gallons per day (Mgal/d)

foot per day (ft/d)

square foot per second (ft2/s)

square foot per day (ft2/day)

25.4

0.3048

1.609

2.590

0.02832

3.785

3.785

25.4

25.4

0.3048

0.02832

0.01093

0.06308

0.04381

1.547

0.3048

0.0929

0.09290

millimeter

meter

kilometer

square kilometer

cubic meter

liter

cubic meter

millimeter per month

millimeter per year

meter per mile

cubic meter per second

cubic meter per second per square kilometer

liter per second

cubic meter per second

cubic foot per second

meter per day

square meter per second

square meter per day

Vertical Datum: In this report "sea level" refers to the National Geodetic Vertical Datum of 1929 (NGVD of 1929) a geodetic datum 

derived from a general adjustment of the first-order level nets of both the United States and Canada, formerly called Sea Level Datum of 

1929.

ABBREVIATIONS USED IN THIS REPORT 

PCE tetrachloroethylene 

PVC polyvinyl chloride 

ppb parts per billion

ft/ft foot per foot

Contents V
Construction and Calibration of Numerical 

Ground-Water-Flow Models of the Western Half of 

the Milford-Souhegan Glacial-Drift Aquifer, 

Milford, New Hampshire

By Philip T. Harte, Robert H. Flynn, and Thomas J. Mack

Abstract

The Milford-Souhegan glacial-drift 

(MSGD) aquifer, in southcentral New Hampshire, 

is an important source of water for industrial, 

commercial, and domestic use that provides more 

than 2.7 million gallons of water per day in 1994. 

A large plume of volatile-organic compounds 

(approximately 0.5 square miles in area) covers a 

large part of the western half of the MSGD 

aquifer and threatens existing ground-water 

usage. The plume area has been designated a 

superfund site and named after a former 

municipal water-supply well (Savage Well) that 

was discontinued because of contamination.

A 3-year study by the U.S. Geological 

Survey and the U.S. Environmental Protection 

Agency began in January 1994 to examine the 

temporal variability of ground-water flow in the 

contaminant plume and adjacent areas of the 

western half of the MSGD aquifer. This report 

summarizes construction and evaluation of threedimensional, steady state and transient numerical 

ground-water-flow models that will be used to 

help design a remediation plan for containing 

volatile organic contaminants.

The results of the steady-state simulation of 

average-flow conditions from June 1994 to June 

1995 show a close comparison between modelcomputed heads and observed heads at more than 

70 wells. Most heads are within 1.5 feet of 

observed heads. The standard-mean-head error is 

-0.12 feet, indicating that computed heads are 

slightly lower than observed heads. The absolutemean-head error is 0.59 feet, and the root-meansquare error is 0.89 feet.

The results of the transient model of 

seasonal-flow conditions also show a close 

comparison between computed-head fluctuations 

and observed-head fluctuations for the same 

wells. The largest difference in computed and 

observed heads occurs for the fall of 1994 

(standard-mean-head error of 0.29 feet).

Computed variations in direction and slope 

of maximum hydraulic gradients compare well 

with observed variations for most areas of the 

model. The analysis, however, identified several 

areas of the model where further testing is 

suggested. These areas include those (1) near the 

source area of contaminants, (2) in the northcentral part of the plume, and (3) at the northern 

leading edge of contaminants near the confluence 

of two rivers.

INTRODUCTION

The Milford-Souhegan glacial-drift (MSGD) 

aquifer, in southcentral New Hampshire (fig. 1), is an 

important source of water for industrial, commercial, 

and domestic use, providing for more than 2.7 Mgal/d 

in 1994. Until it was found to contain high concentrations of volatile organic compounds (VOC's) in the 

early 1980's, the aquifer was also an important source 

of drinking water. Two former municipal supply wells 

(the Savage and Keyes wells) were shut down in 1983 

after withdrawn waters were found to contain elevated 

concentrations of VOC's. Subsequently, local, State, 

and Federal agencies initiated geohydrologic studies to 

characterize the glacial-drift river-valley aquifer and 

delineate the extent of contamination. In 1989, during 

an investigation of the Savage well, a large VOC 

plume composed primarily of tetrachloroethylene

Abstract 1
Area shown in detail in subsequent illustrations

45°

43° ' I

I o iTemple- 

' Keene

MASSACHUSETTS

01020 MILES 

0 10 20 KILOMETERS

EXPLANATION

AQUIFER BOUNDARY 

INACTIVE PUBLIC SUPPLY WELL 

STUDY AREA BOUNDARY

Figure 1. Location of the Milford-Souhegan glacial-drift aquifer, Milford, New Hampshire.

(PCE) was found to underlie the southwestern part of 

the MSGD aquifer (HMM Associates, 1989, 1991). 

The primary source of contamination is a former, 

discontinued, tool company (fig. 2) that discharged 

solvents into the subsurface for many years until the 

early 1980's. Although discharges have ceased, the 

underlying contaminant soaked sediments, and 

immiscible solvents continue to contaminate ground 

water flowing underneath the site. Currently (1999), 

this large plume continues to threaten existing groundwater usage at State and commercial fish hatcheries, 

and restricts the full beneficial use of this resource.

An initial study of ground-water flow in the 

MSGD aquifer was done in the late 1980's and early 

1990's by the U.S. Geological Survey (USGS) (Harte 

and Mack, 1992). The focus of that study was the 

delineation of well capture zones to the two former 

municipal wells (Savage and Keyes well) under 

average annual conditions.

Subsequent (unpublished) work by the primary 

author since the initial study found that the advective 

transport of contaminated ground water from the 

primary source area under the assumption of static or 

long-term steady-state conditions significantly 

underestimated the lateral extent of contaminated 

ground waters. Furthermore, the primary factor 

contributing to the inability of the model to simulate

the plume configuration was the transient variability of 

the aquifer, which was not addressed by Harte and 

Mack (1992).

A 3-year study by the USGS and the 

U.S. Environmental Protection Agency (USEPA) 

began in January 1994 to increase the understanding of 

transient hydrologic conditions in the aquifer. The 

primary objective of this study is to evaluate the 

effects of temporal changes in recharge, discharge, and 

ground-water withdrawals on contaminant flow. 

Specific objectives include:

1. Determine the temporal variability of ground-waterflow directions in the plume area.

2. Determine the temporal variability of surface and 

ground-water interactions between the Souhegan 

River and the glacial-drift aquifer.

3. Construct detailed numerical ground-water-flow 

models to use as predictive tools in remedial and 

monitoring well network design.

4. Identify flow paths to extraction wells by use of 

ground-water-flow models and supportive 

chemical data collected in the field. 

Previous studies include analysis of effects of 

ground-water withdrawals on advective transport of 

contaminated ground waters (Harte and Willey, 1997), 

transient hydrological data (Harte and others, 1997), 

and effects of model discretization on low-pumping 

rate wells (Harte and Mack, 1996).

Construction and Calibration of Numerical Ground-Water-Flow Models of the Western Half of the Milford-Souhegan Glacial-Drift 

Aquifer, Milford, New Hampshire
(A)

Source of Volatile Organic Compound data: HMM Associates, Inc., 1991 

Data collected between January 1989 and Januaiy 1990

EXPLANATION

 Boundary of aquifer

 10 Line of equal total 

volatile organic 

concentration in

r4\ Savage Well name and 

\iS Well (128) T

numberfor 

inactive wells

@ FH-5(208) Well name and 

partsperbilliontepb) 5KS2L*. ®

Direction of

contaminant flow

Outcrop of Bedrock

(B)

y ' \^ '

I \"""-/ ° 01 o-2 M °-4

/'» O, I X 1 I i ' i '' ' 'i L

L/ l^*M* I , 1 0 0.102030.4 0.5

EXPLANATION

 - Boundary of aquifer /K Savage Well name and number 245 Line ot equal water-table altitude, 

V Well (128) for unused wells .... . .

, r*.o._t T * '

® FH-5(208) Well name and number 

fnr ufithrlrauBil wollc

in feet above mean sea level; 

contour interval 5 feet

for withdrawal wells

Figure 2. Extent of contaminant plume (as defined by 10 parts per billion [ppb] line of equal 

concentration) of total volatile organic compounds in 1989 (A), and altitude of water-table 

surface, in feet above mean sea level in April 1994 (B), in the Milford-Souhegan glacial-drift 

aquifer, Milford, New Hampshire. (Modified from Harte and others, 1997)

INTRODUCTION 3
Purpose and Scope

This report summarizes the construction and 

calibration of both steady-state and transient finitedifference numerical ground-water-flow models of the 

western half of the Milford-Souhegan glacial-drift 

aquifer. Model simulations focused on simulating 

hydrologic stresses during 1994-95.

Model performance is evaluated by comparing 

ground-water levels (heads) and river seepages from 

data collected from April 1994 to September 1995 

(Harte and others, 1997). Other data also were used to 

evaluate model performance including data from 1988 

and 1990 (Harte and Mack, 1992; and Olimpio and 

Harte, 1994). A comparison also is made between 

advective transport of ground-water particles and the 

movement of contaminated ground water between 

1989 and 1994.

Hydrogeologic Setting

The MSGD aquifer (fig. 1) is defined as the 

entire sequence of unsaturated and saturated alluvium, 

glacial drift, and other unconsolidated deposits above 

the bedrock surface in the Souhegan River valley in 

Milford, N.H. The aquifer consists primarily of stratified sand and gravel with some basal till, and is 

overlain in places by recent alluvium. The maximum 

saturated thickness of the aquifer exceeds 100 ft in the 

eastern part of the aquifer, but generally ranges from 

0 to 60 ft. Laterally, the aquifer is bounded by tillcovered bedrock uplands.

Two bedrock types have been identified in rock 

cores and include a white to pink, medium to coarsegrained granite and a gray biotite rich diorite gneiss 

(HMM Associates Inc., 1989, 1991). Lyons and 

others (1997) identifies two bedrock formations in the 

Milford area, the Massabesic Gneiss Complex of Late 

Proterozoic Age and an intrusive gray biotite granite 

of Permian Age. A high-angle strike-slip fault called 

the Camp Hill Fault traverses the area.

Till forms the basal unit of glacial drift in the 

MSGD and discontinuously overlies bedrock from the 

Massabesic-Merrimack-Rye terrane (Harte and Mack, 

1992; Lyons and other, 1997). The till consists of a 

sandy to silty matrix.

Stratified-drift deposits represent the most 

transmissive units in the MSGD. Stratified drift was 

deposited as ice-contact materials, glacial-lake

deposits, fluvial deltas, and outwash materials (Koteff, 

1970). During the late stages of glaciation, a west to 

east drainage pattern, similar to present drainage 

patterns, caused coarser sediments to be deposited in 

the western part of the valley. Specifically, glacial 

drainage occurred through the channel occupied by 

Purgatory Brook and through the channel occupied by 

the Souhegan River west of the contaminant source 

area. These glacial drainage channels transported 

coarse-grained sediments into the present day 

Souhegan valley.

The river valley in the study area slopes gently 

at 12 ft/mi along the river. Land-surface elevations 

range from 230 to 280 ft in the study area. The land is 

drained by the Souhegan River and its tributaries 

(fig. 2), including Tucker, Purgatory, Great (not shown 

on map), and Hartshorn Brooks, and a number of 

small, unnamed streams. A discharge ditch drains 

processed waters from several manufacturing 

companies in the southwestern part of the study area.

Land use is predominantly industrial in the 

southwestern part of the study area, agricultural in the 

central and northwestern areas, and residential to 

commercial elsewhere. The contaminant plume 

(fig. 2) underlies a large agricultural area in the center 

of the study area (not shown on any figures) and abuts 

a commercial-industrial area to the south.

Current ground-water withdrawals are primarily 

used for commercial and industrial purposes. 

Withdrawal wells (table 1) include two wells for the 

State Fish Hatchery in the northwestern part of the 

study area (well numbers 87 and 208; fig. 2), a well at 

a private fish hatchery in the eastern part of the study 

area (well number 354; fig. 2), and a well for an 

industrial and manufacturing complex in the 

southwestern part of the study area (well number 395; 

fig. 2).

Acknowledgments

The study of the Milford-Souhegan glacial-drift 

aquifer is a collaborative effort between Federal, State, 

and local governments, and private companies and 

individuals. The authors wish to express thanks to 

Richard Goehlert and Richard Willey of the U.S. 

Environmental Protection Agency, Region 1, and 

Wayne Ives of the New Hampshire Department of 

Environmental Services (NHDES) for their interest. 

Test drilling, water-level data, well construction, and

Construction and Calibration of Numerical Ground-Water-Flow Models of the Western Half of the Milford-Souhegan Glacial-Drift 

Aquifer, Milford, New Hampshire
Table 1. Ground-water withdrawals from currently used commercial and industrial water-supply wells, Milford, 

New Hampshire

Well number _ .. . ...... Average daily withdrawals Average daily withdrawals _* Depth of well, in feet . .~_. . ' .... . . *,. . ' .... .

used in report i»,!L... i_iJ..>*_ in 1994, in millions of in 1995, in millions of

gallons per day

Well name

(figure 2) below land surface

1 This well is a backup to well MI-88.

gallons per day

State of New Hampshire 

Fish Hatchery well #5

State of New Hampshire 

Fish Hatchery well #4

Commercial Production

well MI-88

Commercial Production

well MI-33

Private Fish Hatchery well

208

87

395

47

354

65

42

42

60

40

1.05

1.26

0.25

0.0

0.22

1.10

1.19

0.25

0.0

0.14

water-budget information were collected with the help 

of NHDES, Environmental Science and Engineering, 

Inc., and Camp, Dresser, and McKee, Inc., for the 

superfund remedial investigations and design phases 

of investigations. Estimates of ground-water recharge 

and baseflow were done with the help of Forest Lyford 

and Albert Rutledge of the USGS.

CONSTRUCTION OF NUMERICAL 

MODELS

A block-centered, finite-difference groundwater-flow model (McDonald and Harbaugh, 1988), 

called MODFLOW, was used to simulate steady state 

and transient ground-water flow in the MilfordSouhegan glacial-drift aquifer. Construction of 

steady-state and transient ground-water-flow models 

for the aquifer included compiling certain geologic 

and hydrologic data (from wells, field observations, 

and available literature) for use in the model. Aquifer 

properties were assigned to each cell of the model and 

represent an integrated value over the cell area. In 

addition to aquifer properties, riverbed conductance, 

river stage, recharge from precipitation and lateral 

inflow, and discharge from ground-water withdrawals 

were also included at appropriate cells.

Steady-state and transient-seasonal models of 

flow were constructed to simulate 1994 and 1995 

hydrologic conditions on the basis of ground-water 

level and river-leakage field data available for this 

period. This period was considered acceptable for 

steady-state simulations of average annual conditions

because precipitation during 1994-95 approximated 

the long-term average precipitation (Harte and others, 

1997) and changes in net ground-water storage in the 

aquifer were negligible. Starting and ending water 

levels for the period were within 0.27 ft, or less than 

4 percent of historical fluctuations at long-term 

observation well MOW-36 (located in the southwest 

part of the aquifer), also called MI-18 (Coakley and 

others, 1997). This period is also considered acceptable for transient-seasonal simulations because fluctuations in ground-water levels exceeded 5 ft in parts of 

the aquifer because of seasonal changes in recharge, 

withdrawals, and river stage (Harte and others, 1997, 

table 7).

A list of computer-model files for the steadystate and transient-seasonal models are provided in 

appendix 1. Also listed are model files for the 

transient-historical model by Harte and Willey (1997). 

Model files are archived at the USGS office in 

Pembroke, N.H. and are available upon request. 

Model-input files require about 8 megabytes (MB) of 

storage. Model-output files require considerably more 

space if cell-by-cell flows are stored.

Grid Design

The model area is 1.65 mi2 and includes 

165,375 model cells. The number of active model 

cells is 70,517 cells and they are limited to the lateral 

extent and thickness of the MSGD aquifer (fig. 3).

Model orientation is aligned with the primary 

longitudinal axis of the contaminant plume (figs. 2 and 

3) in a slightly southwest to northeast trend. It is

CONSTRUCTION OF NUMERICAL MODELS 5
(A)

71°42' 71°40'

42°51'

42-50' 

/ -, Aquifer Boundary 

/V Rivers and Streams

(B)

EXPLANATION 

Simulated River Cell 

Inactive Cell

General Head Boundary 

Active Cell

Figure 3. Areas of inactive and active grid cells, simulated river cells, and location of generalhead boundary (A), and grid cells (B), for model of the Milford-Souhegan glacial-drift aquifer, 

Milford, New Hampshire.

6 Construction and Calibration of Numerical Ground-Water-Flow Models of the Western Half of the Milford-Souhegan Glacial-Drift 

Aquifer, Milford, New Hampshire
assumed that the longitudinal axis of the contaminant 

plume approximates the orientation of the average 

ground-water flow direction over the life of the plume. 

Orienting the model with the longitudinal axis of the 

plume will help reduce inaccuracies associated with 

the finite-difference solution of the ground-water-flow 

equation caused by not aligning the grid with the 

principal axis of the hydraulic conductivity tensor. 

Otherwise, the finite-difference-flow equation would 

need to include cross product terms if anisotropy is 

specified in the model (Trescott and others, 1976).

Horizontal cell sizes range from 50 by 25 ft to 

100 by 200 ft. Cell size in the x-direction across 

model columns (southwest to northeast) range from 

50 to 100 ft. Cell size in the y-direction across model 

rows (northwest to southeast) range from 25 to 200 ft. 

Smallest cell sizes occur in the area of the contaminant 

plume, to allow for simulation of low pumping rate 

withdrawal wells without problems associated with 

weak sinks (Harte and Mack, 1996).

The model is vertically discretized into 5 layers, 

each 5 to 25 ft thick, following procedures similar to 

Harte and Mack (1992), with one important exception. 

Unlike, vertical discretization in previous models of 

the MSGD aquifer that used the land surface as the 

uppermost surface for the starting point of vertical 

discretization (Harte and Mack, 1992, fig. 14), a prestressed simulation of the water-table surface, which 

was computed from a model of the MSGD described 

by Olimpio and Harte (1994), was used as the starting 

surface in this study. The use of the water-table 

surface as the uppermost surface produces a smoother 

delineation of model layers than that produced with 

the land surface as a starting surface. As in the 

original model described by Harte and Mack (1992), 

the lowermost boundary is the bedrock surface.

There are 33,075 cells (175 rows and 189 

columns) per model layer. The number of active cells 

decreases with depth from 24,641 cells in layer 1 to 

2,027 cells in layer 5 because the lateral extent of the 

MSGD aquifer with depth below the water-table 

surface decreases. The percent of active cells per total 

number of cells per model layer (33,075) is 75 percent 

for layer 1, 68 percent for layer 2,46 percent for layer 

3, 20 percent for layer 4, 6 percent for layer 5.

The distribution of the active model cells can be 

used as a guide to the saturated thickness of the 

MSGD aquifer. For example, layer 5 active cells 

denote areas where the saturated thickness of the 

MSGD exceeds 80 ft, layer 4 active cells denote areas 

where the saturated thickness exceeds 60 ft, and so on.

Time Discretization

The division of time (called time discretization) 

is an important consideration in simulating steadystate and transient models. Steady-state-model 

simulations represent a single view of hydrologic 

conditions that are representative of average 

conditions over some predetermined period in time. 

During this period, storage changes are considered 

negligible and aquifer stresses and boundaries can be 

averaged into constant values of recharge, groundwater withdrawals, and river stage, respectively. 

Transient simulations represent multiple views of 

hydrologic conditions that represent various 

hydrologic conditions over some period in time. The 

number of views correspond to the frequency of time 

discretization. Transient simulations allow for 

changes in storage and specification of varying aquifer 

stresses and river stage between each discretized time. 

In this report, the steady-state simulation represents a 

single view of average annual hydrologic conditions 

during June 1994 to June 1995. The transient simulation presented in this report, referred to as the 

transient-seasonal simulation, represents a series of 

26 views (or time steps) for the same period as the 

steady-state simulation and simulates changes of 

hydrologic conditions over that period in a discretized 

step-like process. In the transient-seasonal model, 

aquifer stresses and river stages were specified 

monthly. Therefore, stresses are constant for a month 

and are referred to as monthly stress periods. Two 

constant interval time steps (each 15-day in length) are 

used for each stress period, except during September 

1994, which had two stress periods to simulate abrupt 

river stage changes.

Hydraulic Conductivity

Hydraulic conductivity is specified for all five 

model layers because the model is constructed to allow 

for dewatering of model cells, which requires data on 

both hydraulic conductivity and model-layer 

thicknesses (figs. 4-8). Horizontal hydraulic conductivity is differentiated into three to seven zones per 

model layer. Within each zone, horizontal hydraulic 

conductivity is considered to be homogeneous and 

isotropic. Vertically, the model is isotropic and heterogeneous between layers 1 and 2, and anisotropic and 

heterogeneous between layers 2 through 5. Therefore, 

no vertical anisotropy is specified between layers 1

CONSTRUCTION OF NUMERICAL MODELS 7
71"42-

(A)

4251'

42501

(B)

EXPLANATION

LAYER 1 HYDRAULIC CONDUCTIVITY, IN FEET PER DAY 

O 45 450 Aquifer boundary 

 150 rj inactive

71"4?

4251'

42 501

Cobble zone

\ I

Figure 4. Initial input of active areas and horizontal hydraulic conductivity zones for model 

layer one (A), and final input for layer one (B), for Milford-Souhegan glacial-drift aquifer, 

Milford, New Hampshire.

8 Construction and Calibration of Numerical Ground-Water-Flow Models of the Western Half of the Milford-Souhegan Glacial-Drift 

Aquifer, Milford, New Hampshire
71'42 714V

(A)

42 SI42 501

(B)

4251

4250'

EXPLANATION

LAYER 2 HYDRAUUC CONDUCTIVITY, IN FEET PER DAY 

[^Inactive ^60 | 160 « Aquifer boundary

30 95 230

7141'

Figure 5. Initial input of active areas and horizontal hydraulic conductivity zones for model layer 

two (A), and final input for layer two (B), for Milford-Souhegan glacial-drift aquifer, Milford, New 

Hampshire.

CONSTRUCTION OF NUMERICAL MODELS 9
71 42' 71 4T

(A)

4251

42'SO1

.;

«

/

s-x >-

EXPLANATION 

LAYER 3 HYDRAULIC CONDUCTIVITY. IN FEET PER DAY

HI 55 | 140 | 320 Aquifer boundary

| 60 160 G Inactive

71"42' 71"4V

(B)

4251

4250'

Figure 6. Initial input of active areas and horizontal hydraulic conductivity zones for model layer 

three (A), and final input for layer three (B), for Milford-Souhegan glacial-drift aquifer, Milford, 

New Hampshire.

10 Construction and Calibration of Numerical Ground-Water-Flow Models of the Western Half of the Milford-Souhegan Glacial-Drift 

Aquifer, Milford, New Hampshire
(A)

7-T421

4251'

42 SO1

\\.

\

EXPLANATION 

LAYER 4 HYDRAULIC CONDUCTIVITY, IN FEET PER DAY

[05 B 4° | 150 " Aquifer boundary

B 30 60 Q inactive

71"42 71'4V

(B)

4251

42 SO1

Figure 7. Initial input of active areas and horizontal hydraulic conductivity zones for model layer 

four (A), and final input for layer four (B), for Milford-Souhegan glacial-drift aquifer, Milford, New 

Hampshire.

CONSTRUCTION OF NUMERICAL MODELS 11
7-T421 7141'

(A)

4251'

4250'

 ^

(B)

4251

4250'

\-\.

t .

I \ I

\ 

EXPLANATION

LAYER 5 HYDRAULIC CONDUCTIVITY, IN FEET PER DAY 

n 5 Q Inactive 

 60 Aquifer boundary

71'421

71 41'

\

Figure 8. Initial input of active areas and horizontal hydraulic conductivity zones for model layer 

five (A), and final input for layer five (B), for Milford-Souhegan glacial-drift aquifer, Milford, New 

Hampshire.

12 Construction and Calibration of Numerical Ground-Water-Flow Models of the Western Half of the Milford-Souhegan Glacial-Drift 

Aquifer, Milford, New Hampshire
and 2 and the ratio of horizontal to vertical hydraulic 

conductivity is 1:1. The upper two model layers 

consist of outwash plain deposits that probably vary 

equally in the horizontal and vertical directions. 

Vertical anisotropy is specified between layers 2 

through 5. The ratio of horizontal to vertical hydraulic 

conductivity is 2:1 between layers 2 and 3 and is 4:1 

between layers 3 through 5. Vertical heterogeneity is 

also incorporated into the model because a different 

pattern of horizontal spatial variability exists in each 

model layer.

The initial distribution of hydraulic conductivity 

assigned to each layer of the model (figs. 4A-8 A) was 

based on results of previous models of the MSGD 

aquifer (Olimpio and Harte, 1994; and Harte and 

Mack, 1992). The assigned distribution of hydraulic 

conductivity during model simulations was changed

(1) to incorporate information on geology and 

hydraulic characteristics from field data collected 

during the course of this study, including data 

collected to improve delineation of the plume (Camp, 

Dresser, and McKee, Federal Programs Corporation, 

1995; Environmental Science and Engineering, Inc., 

1995; and Camp, Dresser, and McKee, Inc., 1996);

(2) to improve calibration targets such as hydraulic 

heads and river seepages; and (3) to evaluate 

sensitivity of the constructed ground-water-flow 

model to changes in hydraulic conductivity.

Two high hydraulic conductivity zones were 

specified during model performance testing and are 

shown on figures 4b and 6b as plots of final distribution of hydraulic conductivity. The zones included a 

high hydraulic conductivity zone originating from 

glacial fluvial deposits transported in the upland 

channel now occupied by Purgatory Brook (figs. 2 and 

6b) and a shallow high hydraulic zone (fig. 4b) from a 

glacial outburst flood originating from the Stony 

Brook valley located several miles to the west of the 

study area (not shown on any map). Evidence of these 

glacial processes are reported by Koteff (1970) and 

Moore (1995), who describe the occurrence of highenergy meltwater channels in the valleys presently 

drained by Purgatory Brook and Stony Brook during 

the last glaciation.

Vertical hydraulic conductivity was calculated 

from horizontal hydraulic conductivity and model 

layer thickness data, using a method described by 

McDonald and Harbaugh (1988, p. 5-13). A vertical 

to horizontal hydraulic conductivity of 0.5 was applied 

between layers 2 and 3, and a ratio of 0.25 between 

layers 3 and 4, and 4 and 5.

Storage Properties

Storage properties of the aquifer are specified in 

transient simulations of ground-water flow and are not 

required in steady-state simulations. Implicit in 

steady-state simulations is the assumption that no 

change in aquifer storage occurs over the period of 

simulation.

Uniform values of storage properties were 

applied to each model layer based on position of the 

water-table surface. The uppermost model layer (one) 

(fig. 4), which largely contains the water table except 

near areas of ground-water withdrawals, was assigned 

a high storage value corresponding to values 

appropriate for specific yield1 of the aquifer. The 

lowermost model layers, below the uppermost active 

layer (model layers 2 through 5, figs. 5-8), were 

assigned dual storage properties; a low storage value

s\

to simulate the storage coefficient of the aquifer and a 

high value of storage to simulate specific yield for 

situations when the water table is lowered to those 

layers. This option of simulating dual storage properties is called a convertible model layer in the computer 

program MODFLOW (McDonald and Harbaugh, 

1988).

Specific yield for the aquifer was estimated 

from fluctuations of water levels at the long-term 

(36 years) observation well MI-18 (plate 1, 

appendix 2) on the basis of methods described by 

Rasmussen and Andreason (1959). A specific yield of 

0.23 was determined from this method and 

subsequently used in model simulations. The effects 

of using different values of specific yield, however, 

were evaluated in several transient-seasonal simulations. Specified specific yield input values ranged 

from 0.15 to 0.30.

Storage coefficients for the aquifer was assigned 

based on results of aquifer tests from Harte and Mack 

(1992, p. 12-13). A storage coefficient of 0.0003 was 

assigned to transient-seasonal simulations but ranges 

of 0.00003 to 0.003 were also tested.

'The specific yield term in the ground-water-flow equation 

represents the draining or wetting of pore spaces.

The storage coefficient term in the ground-water flow 

equation represents the process of aquifer expansion and compression of water.

CONSTRUCTION OF NUMERICAL MODELS 13
Boundary Conditions

Boundary conditions for the model are treated 

similarly to previous models of flow constructed by 

Harte and Mack (1992) and Olimpio and Harte (1994) 

with the exception of the eastern boundary of this 

model. The upper model boundary, the water table, is 

a specified-flux boundary and receives recharge from 

precipitation. The outermost active cells in the upper 

model boundary that correspond to adjacent till and 

bedrock areas also receive specified flow from these 

upland areas. The outermost active cells are visible in 

figure 3 as the contact between the active and inactive 

cells. The lower model boundary represents the 

bedrock surface, which is assumed to be a no-flow o

boundary . Perennial streams such as the Souhegan 

River, Tucker Brook, and Purgatory Brook are 

simulated as head-dependent flux boundaries.

The eastern boundary of the model differs from 

previous models because the boundary cuts across the 

valley and therefore it was necessary to simulate the 

exchange of flow across this area. The eastern 

boundary is simulated as a head-dependent flux 

boundary and utilizes the general-head boundary 

option of MODFLOW (McDonald and Harbaugh, 

1988, chap. 11). This boundary specification allows 

for the exchange of water between an external source, 

in this case the eastern part of the aquifer that is not 

explicitly simulated in the model, and the simulated 

model of the western part of the aquifer. Model-input 

parameters for the general-head boundary (GHB) 

include external hydraulic head and hydraulic conductance (hydraulic conductivity multiplied by crosssectional area of flow divided by length of flow).

The location of the GHB was positioned to 

provide adequate representation of ground-water flow 

in the western part of the aquifer, to simulate the 

exchange of flow between ground water in the western 

and eastern parts of the aquifer, and to maximize the 

level of discretization in the area of the contaminant 

plume. The boundary corresponds to a relatively thin 

and narrow section of the aquifer where the saturated

Undoubtedly, there is some amount of flow between the 

glacial-drift deposits and underlying bedrock. Most likely the 

MSGD aquifer is a sink from a net flow perspective and receives 

recharge from the bedrock. The assumption that the boundary can 

be treated as a no-flow boundary means that the magnitude of flow 

between the bedrock and the MSGD aquifer is relatively small 

compared to the total flow in the MSGD aquifer.

thickness is generally less than 30 ft and where 

ground-water flow is largely controlled by the 

Souhegan River. The boundary is located at model 

column 181 (fig. 3), eight columns west of the extreme 

edge of the model. Model cells in columns 182 to 189 

are not simulated. The placement of the GHB at 

column 181 allows for repositioning of the boundary 

further eastward if future model testing shows the 

GHB to have adverse effects on flow. The positioning 

of the boundary at column 181 just east of the 

Souhegan River is also useful because the Souhegan 

River in the middle part of the aquifer is a strong 

discharge reach and captures much of the flow from 

the western part of the aquifer (Harte and Mack, 

1992). One reason the Souhegan River acts as a strong 

sink in this part of the aquifer is that its depth of 

incisement relative to aquifer thickness is greater in 

this area of the aquifer than it is in other areas with the 

exception of the extreme eastern edge of the valley.

Hydraulic heads for the GHB were derived from 

computed heads of the same area from the 1988 

steady-state model of average annual conditions 

(Olimpio and Harte, 1994). Ground-water 

withdrawals in the valley in 1994-95 (table 1) have 

little effect on heads in this area of the model, and 

heads from the 1988 model of the MSGD aquifer are a 

good approximation of heads in this area regardless of 

current or past changes in ground-water withdrawals.

Conductances for the boundary were computed 

from the hydraulic conductivity of the corresponding 

model layer (both layers 1 and 2 were simulated), and 

from the cross-sectional area along column 181. The 

cross-sectional area of each GHB cell corresponds to 

the width of the cell in the row direction multiplied by 

the saturated thickness of the cell. Conductances of 

GHB cells vary from 0.36 to 1.12 ft2/s for layer 1 and 

0.41 to 4.26 ft2/s for layer 2.

Recharge

Recharge was applied to the uppermost active 

cells to simulate infiltration of direct precipitation onto 

the aquifer, lateral inflow of water from adjacent 

uplands, and infiltration of surface water from 

ephemeral streams (tributaries 1 and 2, fig. 2). 

Recharge from perennial streams was accounted for in 

simulations of river-aquifer interactions by use of the 

river package of MODFLOW (described in the section 

"River-Aquifer Interactions").

14 Construction and Calibration of Numerical Ground-Water-Flow Models of the Western Half of the Milford-Souhegan Glacial-Drift 

Aquifer, Milford, New Hampshire
Recharge from infiltration of precipitation was 

applied uniformly over the active model area. Lateral 

inflow of water from uplands was apportioned to the 

edge of the active model area based on upland areaweighted calculations discussed in Harte and Mack 

(1992). A lateral-inflow rate of 0.5 ft3/s was used for 

the simulated area.

Rates of direct precipitation were derived from 

two independent techniques and then specified in 

steady-state and transient-seasonal models of flow. 

The appropriateness of calculated recharge rates was 

evaluated by comparing computed heads and river 

leakages with observed heads and river leakages. The 

independent techniques used include a quasi twodimensional water-balance model, called HELP 

(U.S. Environmental Protection Agency, 1994a,b), 

and a water-level accretion method described by 

Rasmussen and Andreason (1959).

Recharge rates from the water-balance model 

were calculated by Environmental Science and 

Engineering, Inc. (1997b) for the period March 1994 

to June 1995 and tested in model simulations. The 

water-balance model computes monthly recharge from 

daily inputs of temperature and precipitation, and from 

characteristics of soil properties. Two sets of values 

were calculated that differed on the basis of the 

amount of simulated overland runoff (table 2). The set 

of recharge values with no overland runoff are proportionally greater than the set with overland runoff.

Recharge rates using the water-level-accretion 

technique were calculated for a similar period of time 

as the water-balance model. The technique involves 

computation of recharge based on the assumption that 

the water-level rise projected above a previous groundwater recession is equal to the rate of ground-water 

recharge divided by the specific yield of the aquifer

Table 2. Estimates of ground-water recharge from a water-balance model of the Milford-Souhegan glacial-drift aquifer and 

water-level-accretion technique for long-term observation well MI-18 (MOW-36, well number 29), Milford, New Hampshire

[Location of MI-18 is shown on plate 1. Abbreviations: in/m, inch/month; ft3/s, cubic foot per second; Bold numbers represent maximum estimate for that 

month.]

Date

March 1994

April 1994

May 1994

June 1994

July 1994

August 1994

September 1994

October 1994

November 1994

December 1994

January 1995

February 1995

March 1995

April 1995

May 1995

June 1995

Total

Monthly mean

Standard deviation

Percentage of

precipitation

Precipitation 

(in/m) (frVs)

5.99

2.50

5.07

1.77

4.33

4.89

5.83

0.63

3.88

6.12

3.82

2.99

1.97

2.03

3.23

1.78

56.83

3.55

1.65

100

8.57

3.70

7.26

2.62

6.20

7.00

8.62

0.90

5.74

8.76

5.47

4.74

2.82

3.00

4.62

2.63

82.65

5.17

2.37

100

Water-balance model 

with runoff1 

(low recharge) 

(in/m) (ftVs)

0.31

1.25

0.61

0.46

0.36

0.25

1.69

2.12

0.89

4.28

2.17

0.54

0.32

0.85

0.61

0.39

17.10

1.07

1.03

30

0.44

1.85

0.87

0.68

0.51

0.36

2.5

3.03

1.32

6.13

3.11

0.86

0.46

1.26

0.87

0.58

24.83

1.55

1.47

30

Water balance model 

with no runoff 2 

(medium recharge) 

(in/m) (frVs)

7.20

2.38

0.63

0.47

0.36

0.27

1.69

2.19

0.89

4.44

2.11

0.56

3.23

1.65

0.80

0.38

29.24

1.83

1.80

52

1030

3.52

0.90

0.70

0.52

0.39

2.51

3.13

1.32

6.35

3.02

0.89

4.62

2.44

1.15

0.59

42.35

2.65

2.56

51

Water-level accretion 

(high recharge) 

(in/m) (fAs)

3.57

1.80

1.89

1.00

0.98

2.55

3.72

1.21

3.60

5.95

3.47

1.85

2.83

1.82

235

1.12

39.80

2.49

1.29

70

5.11

2.66

2.71

1.48

1.40

3.65

5.50

1.73

532

8.52

4.97

2.93

4.05

2.70

336

1.66

57.75

3.61

1.85

70

'Environmental Science and Engineering, Inc. (1997b). 

Environmental Science and Engineering, Inc. (1997b).

CONSTRUCTION OF NUMERICAL MODELS 15
(assumed to be 0.23). Therefore, recharge over a 

given time period equals the summation of recharge 

from individual water-level rises. The water-levelaccretion technique produced higher rates of recharge 

than the water-balance method.

Based on these recharge analyses, a relation 

between precipitation and direct recharge was 

established and used to assign recharge rates for the 

simulated stress periods. Recharge values of 30,52, 

and 70 percent of direct precipitation were assigned to 

the model to test the appropriateness of these rates.

Total amounts of recharge that were applied to 

steady-state and transient-seasonal models varied 

based on the stress period. Steady-state recharge 

ranged from 2.06 ft /s (30 percent of precipitation) to 

3.89 ft3/s (70 percent of precipitation). A final value 

of 3.26 ft /s (60 percent of precipitation) was chosen 

as most representative of average annual conditions. 

Transient recharge varied from a monthly low of 

0.39 ft3/s in August 1994 to a monthly high of 

10.3 ft3/s in March 1994.

River-aquifer Interactions

River-aquifer interactions of perennial streams 

including the Souhegan River, Purgatory Brook, 

Tucker Brook, Hartshorn Brook, and the discharge 

ditch were simulated with the river package of 

MODFLOW, in which flow between the perennial 

streams and the aquifer is a function of head gradient 

and riverbed conductance. Therefore, river-aquifer 

interactions act as a head-dependent flow boundary. 

Perennial streams are represented by over 1,800 model 

cells.

Model-input specifications for each cell 

containing a perennial stream include altitude of the 

river stage and riverbed and riverbed conductance 

[which is a product of the riverbed hydraulic conductivity (K), width, and length of riverbed within the cell, 

divided by the thickness of the riverbed (M)]. All 

parameters except riverbed thickness and hydraulic 

conductivity are readily measurable.

River stages were based on measurements of 

altitude of river stage and riverbed from eight river 

gaging stations on the Souhegan River, four stations on 

the discharge ditch, and several miscellaneous stations 

on the remaining perennial streams (Harte and others, 

1997). Values of river stage were assigned to all river 

cells from linear interpolation of the measured river 

stage at each of the gaging stations.

River stage assigned to the steady-state models 

of flow were based on the arithmetic mean stage of the 

river-gaging stations during 1994 and 1995. River 

stage assigned to the transient-seasonal models of flow 

were based on the mean monthly stage of the stations. 

As an example, river stage assigned to model cell row 

81 and column 13 for the transient-seasonal model is 

shown in figure 9. Riverbed altitudes were constant 

for the steady-state and transient-seasonal models 

because this parameter is assumed to remain 

unchanged during this period. Riverbed altitudes were 

calculated from the height of the water column above 

the riverbed at gaging stations and were linearly 

interpolated between river-gaging stations.

Riverbed widths were computed from streamflow measurements made at over 40 sites on perennial 

streams and values for all cells linearly interpolated 

from these sites. These data also were used to assure 

that correct distances were used between the altitudes 

of river stage and riverbed.

The remaining parameters for the river-package 

input, riverbed thickness and hydraulic conductivity, 

were lumped into one parameter, called riverbed 

leakance, (K/M), and assigned rates comparable to 

those assigned in earlier steady-state models of flow in 

the aquifer (Harte and Mack, 1992). The distribution 

of riverbed leakance are provided in table 3.

Ground-water Withdrawals

Specifying appropriate rates of ground-water 

withdrawals is important because of the effect 

withdrawals have on ground-water flow. Rates of 

specified withdrawals in the models for the major 

public-water supply, commercial, and industrial water 

suppliers are provided in table 4 for various simulated 

stress periods.

Estimates of withdrawals are based on well 

records and written and oral communications with 

personnel from the State of New Hampshire Fish 

Hatchery and other facilities in Milford. Because of 

imprecision in the measurements of withdrawals at the 

State Fish Hatchery, probable ranges of withdrawals 

are listed in table 4. Managers evaluating remedial 

schemes should test the effect of these ranges of 

withdrawals on contaminant clean-up. For example, 

State Fish Hatchery well FH-4 (well number 87) 

(fig. 2) withdrawals may vary between 950 and 

1,350 gal/min and State Fish Hatchery well FH-5 

(well number 208) (fig. 2) may vary between 600 and 

800 gal/min.

16 Construction and Calibration of Numerical Ground-Water-Flow Models of the Western Half of the Milford-Souhegan Glacial-Drift 

Aquifer, Milford, New Hampshire
271

Hi 270

LJU

8

QJ

269

LJU

g 268 

O

QJ 

O 

£

CO

cc

HI

E

267

266

M M J A 

1994

M A 

1995

M

Figure 9. River stage specified in model cell row 81 and column 13 for the transient-seasonal model of the MilfordSouhegan glacial-drift aquifer, Milford, New Hampshire. (P1 gage is shown on plate 1.)

Table 3. Assigned values of riverbed leakance (hydraulic conductivity divided by riverbed thickness) 

to models of flow of the Milford-Souhegan glacial-drift aquifer, Milford, New Hampshire

[Units of riverbed leakance is measured in I/day. Locations of streams are shown in plate 2]

Stream Reach description Riverbed leakance

Souhegan River

Souhegan River

Purgatory Brook

Tucker Brook

Discharge ditch

Upstream of column 135

Downstream of column 135

All

All

All

2

0.75

2

1.33

0.66

CONSTRUCTION OF NUMERICAL MODELS 17
Table 4. Simulated ground-water withdrawals for stress periods in simulations of the Milford-Souhegan glacial-drift aquifer, 

Milford, New Hampshire

[Note: Not all results of simulations listed here are presented in this report. Results of transient historical simulations presented in Harte and Wilky (1997). 

ft /s, cubic foot per second (to convert withdrawals in ft /s to gallons per minute, multiply by 448.8)]

Well name

and number

shown on

plate 1

Model Simulated

Row Column 

(plate 2) (plate 2)

Model 

layer Ranges of rates of withdrawal tested, 

infrVs

Final rate of withdrawal,

FH-5(208) 

FH-4(87)

MI-88(395) 

PFH(354)

FH-5(208)

FH-4(87)

MI-88(395) 

PFH(354)

28

40

128

70

28

40

128

70

Savage (128) 118

MI-35(49) 130

59

55

39

159

59

55

39

159

99

59

3 

2,3

2

2

2,3

2,3

MI-33(47)

Savage (128)

FH-1(84)

MI-33(47)

Savage (128)

FH-1(84)

MI-33(47)

Savage (128)

128

118

28

128

118

28

128

118

40

99

60

40

99

60

40

99

3

2,3

3

3

2,3

3

3

2,3

FH-1(84)

FH-3(86)

MI-33(47)

Savage (128)

28

40

128

118

60

51

40

99

3

3

3

2,3

MI-35(49) 130 59

Steady-state simulation, 1994-95 

1.44-1.63

1.56-2.05; layer 2 

0.39-0.51; layer 3

0.38 

0.22 

Transient-seasonal simulation, 1994-95

1.59-1.78 from Jan. to May of 1994 and

Jan. to May 1995, and Oct. to Dec. 1994. 

0 in June 1994.

1.50-1.78 from July to Sept. 1994. 

1.50-1.78 in June 1995.

1.60-2.1 in layer 2 and 0.40-0.53 in layer 3 in

1994. 

1.42 in layer 2 and 0.36 in layer 3 from

Jan. 1995 to June 1995.

0.38

0.38 from Jan.-Oct. 1994.

0.22 from Nov. 1994-June 1995.

Transient historical simulation, 1965-96 

0.162 in layer 2 

0.162 in layer 3

Transient historical simulation, 1965-71

0.56

0.162 in layer 2 

0.162 in layer 3

Transient historical simulation, 1971-74

1.33

0.56

0.162 in layer 2 

0.162 in layer 3 

Transient historical simulation, 1974-Sept. 1976

1.33

0.56

0.162 in layer 2 

0.162 in layer 3

0.26 

Transient historical simulation, Sept. 1976-Feb. 1983

1.07

0.61

0.56

0.162 in layer 2 

0.162 in layer 3

0.26

1.63

1.56:layer 2 

0.39;layer 3

0.38

0.22

1.78 from Jan. 1994 to Mar. 1995 except

for June 1994 which was 0. 

April 1995 to June 1995 was 1.67.

1.60 in layer 2 and 0.40 in layer 3 in

1994. 

1.42 in layer 2 and 0.36 in layer 3 from

Jan. 1995 to June 1995.

0.38

0.38 from Jan.-Oct. 1994.

0.22 from Nov. 1994-June 1995.

0.162 in layer 2 

0.162 in layer 3

0.56

0.162 in layer 2 

0.162 in layer 3

1.33

0.56

0.162 in layer 2 

0.162 in layer 3

1.33

0.56

0.162 in layer 2 

0.162 in layer 3

0.26

1.07

0.61

0.56

0.162 in layer 2 

0.162 in layer 3

0.26

18 Construction and Calibration of Numerical Ground-Water-Flow Models of the Western Half of the Milford-Souhegan Glacial-Drift 

Aquifer, Milford, New Hampshire
Table 4. Simulated ground-water withdrawals for stress periods in simulations of the Milford-Souhegan glacial-drift aquifer, 

Milford, New Hampshire Continued

Well name 

and number - 

shown on 

plate 1

Model

Row 

(plate 2)

Column 

(plate 2)

Mo 

la)

del .... - -

Simulated

rer Ranges of rates of withdrawal tested, 

inftS/s

Final rate of withdrawal, 

inftS/s

Transient historical simulation, Feb. 1983-Oct. 1986

FH-1(84)

FH-3(86)

MI-33(47)

MI-35(49)

28

40

128

130

60

51

40

59

3

3

3

3

0.73

0.61

0.56

0.26

0.73

0.61

0.56

0.26

Transient historical simulation, Oct 1986- Jan. 1988

FH-1(84)

FH-4(87)

MI-33(47)

MI-35(49)

28

40

128

130

60

55

40

59

3

2,3

3

3

0.56

1.42-2.05 in layer 2 

0.36-0.51 in layer 3

0.56

0.26

0.56

1.42-2.05 in layer 2 

0.36-0.51 in layer 3

0.56

0.26

Transient historical simulation, Jan. 1988- Jan. 1989

FH-5(208)

FH-4(87)

MI-33(47)

MI-35(49)

28

40

128

130

59

55

40

59

3

2,3

3

3

1.78

1.42-2.05 in layer 2 

0.36-0.51 in layer 3

0.56

0.26

1.78

1.42-2.05 in layer 2 

0.36-0.51 in layer 3

0.56

0.26

Transient historical simulation, Jan. 1989- April 1990

FH-5(208)

FH-4(87)

MI-88(395)

MI-35(49)

28

40

128

130

59

55

39

59

3

2,3

3

3

1.78

1.42-2.05 in layer 2 

0.36-0.51 in layer 3

0.56

0.001

1.78

1.42-2.05 in layer 2 

0.36-0.51 in layer 3

0.56

0.001

Transient historical simulation, April 1990- Aug. 1992

FH-5(208)

FH-4(87)

MI-33(47)

MI-35(49)

PFH(354)

28

40

128

130

70

59

55

39

59

159

3

2,3

3

3

2

1.63

1.42-2.05 in layer 2 

0.36-0.51 in layer 3

0.40

0.001

0.334

1.63

1.42-2.05 in layer 2 

0.36-0.51 in layer 3

0.40

0.001

0.334

Transient historical simulation, Aug. 1992-Oct 1994

FH-5(208)

FH-4(87)

MI-33(47)

PFH(354)

28

40

128

70

59

55

39

159

3

2,3

3

2

1.44-1.63

1.42-2.05 in layer 2 

0.36-0.51 in layer 3

0.38

0.334

1.44-1.63

1.42-2.05 in layer 2 

0.36-0.51 in layer 3

0.38

0.334

Transient historical simulation, Nov. 1994-Dec. 1995

FH-5(208)

FH-4(87)

MI-33(47)

PFH(354)

28

40

128

70

59

55

39

159

3

2,3

3

2

1.44-1.63

1.42-2.05 in layer 2 

0.36-0.51 in layer 3

0.38

0.22

1.44-1.63

1.42-2.05 in layer 2 

0.36-0.51 in layer 3

0.38

0.22

CONSTRUCTION OF NUMERICAL MODELS 19
CALIBRATION OF AND PERFORMANCE 

CRITERIA FOR NUMERICAL MODELS

Computed heads and fluxes from steady-state 

and transient-seasonal models of flow were calibrated 

to observed heads and river leakages. Observed river 

stages are explicitly specified in the model and, 

therefore, are not used in calibration. A listing of 

observation wells, where heads were measured is 

given in appendix 3; well construction information is 

given in appendixes 2 and 4. River-gaging stations, 

where river leakage were calculated, are shown on 

plate 1.

The observed data used to calibrate the model 

differ for the steady-state and transient models of flow 

based on the time dependency of the simulation and 

relevancy of field observations to the simulated stress 

period. For example, in steady-state simulations, 

average values or values that approximate average 

conditions are used to judge model performance, 

whereas in transient simulations, actual discrete values 

that change with time are used.

Computed heads were compared to more than 

70 values of observed head (appendix 3). The steadystate model was calibrated to heads calculated from 

the arithmetic mean head of biweekly measured water 

levels from wells measured June 1994-95. The 

transient-seasonal model was calibrated to observed of 

heads from the same wells using discrete measurements of heads from the same period. Additional head 

data were also used to check model performance and 

include 3 synoptic rounds of head measurements made 

from more than 100 wells in 1988, 1990, and 1994.

Computed river seepages of simulated rivers 

were compared to observed river leakages5 from a 

comprehensive 1988 round of streamflow measurements (Harte and Mack, 1992) for selected drainage 

subbasins (plate 1), and to the calculated mean of river 

leakages from streamflow measurements made in 

1994-95 at two river reaches. The two river reaches 

include an upstream reach between stations WLR1 

and P2 (plate 1) and a downstream reach between 

WLR5 and bedrock outcrop (plate 1). Observed river 

leakages were calculated from streamflow measurements of coupled upstream and downstream river-

*TTie term seepage is used to describe ground-water recharge 

and discharge interactions with streams.

5The term leakage is used to describe all processes contributing to gains and losses in streams.

gaging stations based on techniques described by 

Harte and others (1997). The 1988 calculated 

leakages were measured during low to moderate flow 

conditions (77 percent flow duration at continuous 

gaging stations in the region). The 1994-95 leakages 

include 13 coupled measurements at the upstream 

reach and 10 at the downstream reach that were 

measured in low to high flow (30 to 90 percent flow 

duration at continuous gaging stations in the region).

An exact calibration between model-computed 

river seepage and observed river leakage is not 

possible because of a number of factors; first, there are 

inaccuracies in the observed river leakages that are 

intrinsic to techniques of measuring streamflow and, 

second, there is a difference between a seepage value 

and a leakage value. Seepage is entirely comprised of 

baseflow, whereas leakage may include other 

components of streamflow besides baseflow. In 

general, computed river seepages were considered 

acceptable if they were within 50 percent of observed 

river leakages during streamflows with less than a 

50 percent flow duration, and greater than 50 percent 

when observed river leakages were made during 

streamflows with greater than a 50 percent flow 

duration.

Summary statistical functions used for 

calibrating ground-water head include two statistical 

means, the standard mean and absolute mean, root 

mean square error, and standard deviation. The 

standard mean is calculated as

(1)

the absolute mean is calculated as

-M (2)

where

\.

h0 = observed head, and

n = number of observations.

m = model computed head,

20 Construction and Calibration of Numerical Ground-Water-Flow Models of the Western Half of the Milford-Souhegan Glacial-Drift 

Aquifer, Milford, New Hampshire
Summary statistics were used to measure model 

performance and adequacy in order to minimize mean 

differences between computed and observed heads 

without producing spatial bias.

Results of simulations were also checked by 

comparing advective transport of contaminated ground 

waters in the plume, by use of a semi-quantitative 

particle-tracking scheme called MODPATH (Pollock, 

1994), to the observed distribution of contaminants 

(fig. 2a). The observed distribution of contaminant 

was determined from water-quality data from previous 

studies (New Hampshire Department of Environmental Services, 1985; HMM Associates Inc., 1989, 

1991; Environmental Science and Engineering, Inc., 

1997; Camp, Dresser, and McKee-Federal, Inc. 1995; 

Camp, Dresser, and McKee Inc., 1996). Model performance based on particle tracking was done by 

comparing a steady-state simulation of particle distributions that was forward tracked for 5 years from a 

reported plume distribution in 1989, with the reported 

plume distribution in 1994 (fig. 10).

The comparison of plume distributions at 

different points in time using advective-transport 

simulations implicitly assumes that advective transport 

is the most important component of solute transport 

and that dispersion, diffusion, adsorption/desorption, 

decay, and additional sources and sinks of contaminants are relatively small factors in the solute transport 

of contaminants. Because for this study there was no 

attempt to independently differentiate the effects of 

advective transport from the other components of 

solute transport on the formation of the contaminant 

plume, direct comparisons of the observed plume and 

simulated advective transport are only qualitative.

Steady State

Results of steady-state simulations of flow of 

1994-95 were compared to mean-observed heads and 

mean-observed-river leakages for the period of simulation. The principal mechanisms of comparison were:

1. Mean differences between computed and observed 

heads from the arithmetic average of biweekly 

measurements of water levels from more than 

70 wells (Harte and others, 1997) (appendix 3),

2. Spatial analysis of residuals between computed and 

observed heads from wells,

3. Vertical-head gradients at clustered wells,

4. River leakage estimates made during baseflow 

conditions, and

5. Arithmetic mean of river leakage from two reaches 

on the Souhegan River where multiple coupled 

measurements of streamflow were made (Harte 

and others, 1997).

During calibration, head residuals were reduced 

to avoid spatial bias and to help assure a random error 

distribution. Maps of head residuals and gradients 

along transects of the aquifer were produced. Calibration was considered complete when head residuals 

were calibrated to less than the observed fluctuation of 

ground-water levels at the observed well location, 

which was generally 3 ft at locations remote from 

ground-water withdrawals, and 6 feet at pumping 

locations. Computed vertical gradients were 

compared observed gradients at well clusters.

Transient Seasonal

Results of transient-seasonal model of flow 

during 1994-95 were compared to biweekly observations of heads and monthly measurements of river 

leakage. The principal mechanisms of comparison 

were:

1. Seasonal mean differences between simulated and 

observed heads from wells,

2. Spatial analysis of water-level fluctuations,

3. Analysis of variations between the computed and 

observed principal directions and magnitude of 

maximum slope in heads at selected triangular 

grouped wells, and

4. River leakages from two reaches on the Souhegan 

River where multiple coupled measurements of 

streamflow were made (Harte and others, 1997). 

Variations in principal direction and magnitude 

of maximum slope of head were analyzed by use of 

procedures described by Johnston and Harte (1998), in 

which a three-point planar solution was applied to a 

triangular grouping of observations of ground-water 

levels. In the analysis presented in this report, 

triangular groupings of computed heads during June 

1994-1995 were compared to observed observations 

reported in Harte and others (1997, table 8).

Criteria used to judge the performance of the 

transient model include comparisons discussed in the 

steady-state model but also include analysis of 

temporal trends in computed and observed heads and 

computed river seepages and observed river leakages. 

Analysis of temporal trends include plotting of 

hydrographs, summary statistics grouped per season, 

time-series plots of river leakage, and analysis of 

standard deviation of biweekly head gradients.

CALIBRATION OF AND PERFORMANCE CRITERIA FOR NUMERICAL MODELS 21
(A) 976,000 1989 980,000

128,000 rZ3

124,000

(B)

128,000

<f QQ4

_____________________976,000_________iw»___________________980.000_______________

r&^ ,,X';^/ *>"* j&\ f \ ^-//v;~\v J^A^,^ | :jl \^ /V J V-^T"

^^^^(^ PxRU« *Na, V-^.^^|^;C %:'^/b%^ ^^TVb. ^Sl^~s i^rLT^RD'- ^ ^^i i ^^fe^i/feS^^1^^

V (^tfjgj "^ fS^3.<^H>RY ^ VA j- . ^";:3^( I'^^^P 

-\% ^<.r^./X V I"'/ ^^^^vi Or:^^x "-i'' \ > -->^

/-\ -" \ V*L i ^ * _ .U" y ' '.* *y*r." i*

%J^C^

124.000

Base from U.S. Geological Survey 

Milford, N.H., 1:24,000,1968, photorevision as of 1985 

4,000-foot grid based on New Hampshire State Plane 

coordinate system - NAD83

0 1,000 2,000 FEET

I_____ i ______I I I \

0 200 400 METERS

EXPLANATION

Contour of PCE concentration, 

in parts per billion (ppb)

Figure 10. Concentration of tetrachloroethylene (PCE) in 1989 (A), and 1994 (B), in the Milford-Souhegan glacial-drift 

aquifer, Milford, New Hampshire.

22 Construction and Calibration of Numerical Ground-Water-Flow Models of the Western Half of the Milford-Souhegan Glacial-Drift 

Aquifer, Milford, New Hampshire
Calibration reduced the temporal and spatial bias in 

head residuals. Calibration of computed river 

seepages based on ranges of observed river leakages, 

where multiple coupled streamflow measurements 

were made was not possible because the model 

simulates only ground-water flow, whereas observed 

river leakages incorporate other hydrologic processes. 

Thus the range in observed river leakages greatly 

exceed the range in computed river seepages.

EVALUATION OF SELECTED MODEL 

PARAMETERS

During testing of the flow models, important 

model parameters and conditions were evaluated to 

ascertain their effect on model results. Model parameters evaluated included boundary conditions, groundwater recharge, hydraulic conductivity, river-aquifer 

interactions, and storage parameters.

Previous model studies of the MSGD aquifer 

helped focus model testing during this study. 

Computed model results of sensitivity analysis of the 

post-calibrated model performed by Harte and Mack 

(1992) provided insight into what additional simulations should be performed. As a result, selected model 

parameters were tested concurrently with model 

calibration. This section outlines important simulated 

results from a trial-and-error calibration process. This 

trial-and-error calibration process also can be used as a 

pre-calibrated sensitivity analysis of the aquifer.

Boundary Conditions

The eastern boundary of the model, which 

contains the general-head boundary along column 

181 (fig. 3), underwent rigorous testing to insure that it 

adequately approximated ground-water-flow 

conditions in the western half of the MSGD. In particular, it was important to demonstrate that the generalhead boundary did not affect the final discharge 

locations and flow of ground water associated with the 

contaminant plume.

The effect of the general-head boundary on 

steady-state ground-water withdrawals in the westernhalf of the MSGD was tested by examining the extent 

of drawdowns from withdrawals at the private fish 

hatchery, which is the closest withdrawal well to the 

boundary. No-flow and constant-head boundary

conditions were tested along the same location of the 

aquifer and model-computed heads were compared at 

the withdrawal well near the private fish hatchery. 

These boundary conditions were initially compared 

with a 1988 model of the MSGD aquifer (Olimpio and 

Harte, 1994) because that model simulates the entire 

MSGD aquifer. No changes in drawdowns resulted at 

the private fish hatchery from incorporation of no-flow 

or constant-head boundaries along the area marked by 

column 181 of the 1994 model described in this report.

Steady-state flows from the general-head 

boundary of the 1994 model were checked against 

flows across this area of the aquifer with the 1988 

model of the MSGD aquifer (Olimpio and Harte, 

1994) to insure that rates of ground-water flow in both 

models were comparable. Both the 1988 model and 

the 1994 model simulated the same average annual 

steady-state flow conditions. The net flow across this 

area of the aquifer was computed with the 1988 model 

at a net rate of 0.23 ft3/s into the western part of the 

aquifer. Most of this flow occurred as inflow in the 

area occupying the northeastern part of the 1994 

model, approximately between rows 31 to 80 along 

column 181 of the 1994 model (plate 2). Simulations 

with the 1994 model using nearly identical model 

parameters as that of the 1988 model resulted in an 

initial net rate of 0.33 ft3/s into the 1994 modeled area 

from the GHB. Model adjustments during the calibration process resulted in increased rates of flow into the 

model from the general-head boundary. Specifically, 

increases in hydraulic conductivity and adjustments of 

river stage caused inflows of 0.57 ft3/s to occur from 

the general-head boundary. A rate of 0.57 ft3/s 

represents about 7 percent of total flow through the 

simulated western half of the aquifer. Because little 

data exist in the northeastern part of the study, rates of 

inflow ranging from 0.57 to 0.23 ft3/s are considered 

acceptable.

The use of general-head boundary also results in 

an adequate approximation of the patterns of advective 

transport of ground water near the leading edge of the 

contaminant plume. Steady-state advective transport 

of ground water near the leading edge of the contaminant plume were forward tracked to test the effect of 

the general-head boundary on discharge of contaminated ground water. Simulations using the 1994 

model of the western half of the MSGD aquifer were 

compared with the 1988 model of the MSGD 

(Olimpio and Harte, 1994) to assess differences 

caused by the contrast in the areal extent of the

EVALUATION OF SELECTED MODEL PARAMETERS 23
models. Again, identical flow conditions were 

simulated. Particles were tracked from the same 

starting locations, column 110 of the current model 

and column 58 of the previous model. All particles 

from the two models discharged to similar reaches of 

the Souhegan River (fig. 11) and showed a consistency 

in the locations of final discharge between the two 

models.

Specification of the GHB near the eastern 

boundary of the model does not affect the final 

discharge locations of contaminated ground waters for 

simulations testing alternative distributions (or realizations) of hydraulic conductivity in the aquifer. This is 

an important result because there is always uncertainty 

in model parameterization of aquifer properties and 

the testing of alternate possibilities of hydraulic 

conductivities near the GHB provides additional 

confidence in simulated results. Specifically, it is 

important to demonstrate that advective transport of 

ground water near the leading edge of the contaminant 

plume is unaffected (if alternate possibilities of 

hydraulic conductivity exist in the aquifer near the 

GHB) by the GHB. The distributions of alternate 

hydraulic conductivity included a simulation that 

tested for a highly conductive (hydraulic conductivity 

of approximately 600 ft/d deep) buried-esker deposit 

underlying the Souhegan River. Further information 

on buried-esker deposits in the aquifer is described in 

Mack and Harte (1996). A hydraulic conductivity 

value of 600 ft/d represents the likely uppermost range 

of hydraulic conductivity in the aquifer. A continuous 

deeply buried esker deposit underlying the area of the 

aquifer by the GHB potentially could facilitate the 

eastward flow of contaminants. Forward tracking of 

particles showed that discharge to the Souhegan River 

did not flow past the area marked by the GHB in the 

1988 model and, therefore, supports the placement of 

the boundary at this location.

Evaluation of the effect of the GHB on model 

simulations of seasonal variations in recharge and 

discharge for 1994-95 indicates that because stable 

heads are specified at the boundary, computed heads at 

model cells along columns 179 to 181 are dampened. 

For model columns less than 179 (west of column 

179), however, simulated-head fluctuations appear 

unaffected and fluctuate similarly to heads elsewhere 

in the model. The fluctuations of computed heads near 

column 181 are dampened because of the assignment 

of average heads, which are static over time, at the 

GHB. This dampening effect is restricted to several

hundred feet of the boundary, in an area of the aquifer 

in which little data are available, and removed from 

areas of the aquifer that affect advective transport of 

the contaminant plume.

Recharge

High (70 percent of precipitation), medium 

(52 percent of precipitation) and low (30 percent of 

precipitation) rates of ground-water recharge were 

simulated for the steady-state and transient-seasonal 

models. These recharge rates are based on calculations of flow based on computations of recharge 

previously described under "Construction of 

Numerical Models and Recharge."

Steady-state simulations showed small differences in computed heads between the high and low 

recharge rates. The average head difference (standard 

mean error) from observation wells (appendix 3) 

differed by only 0.4 ft between the high and low 

recharge simulations. The standard mean error 

represents the average head difference, from observation wells, between the model-computed heads 

produced from the steady-state simulation of 1994-95 

average annual conditions and the arithmetic mean of 

biweekly measurements of water levels. The standard 

mean error from the high recharge rate was the lowest 

(-0.16 ft) and provided the best overall match with 

observed data.

The simulated high-recharge rate also produced 

the best match between calculated river leakages and 

measured river leakages across the western aquifer. 

For the simulated low and medium recharge rates, 

computed river losses to the aquifer exceeds river 

gains from the aquifer by 1.31 ft3/s for the low 

recharge rate and 0.87 ft3/s for the medium recharge 

rate. For the simulated high recharge rate, river gains 

exceeds river losses by 0.4 ft /s. Nine coupled 

upstream and downstream measurements of streamflow across the study area showed a tendency of small 

gains between 1 to 2 ft3/s (in six out of nine measurements) between 1994-95.

Results of transient-seasonal simulations to 

assess the appropriateness of low, medium, and high 

monthly recharge rates (table 2) showed that computed 

heads using medium to high recharge rates best 

approximated observed water levels. A representative 

example of the variations in computed heads produced 

from specifying three different rates of recharge is

24 Construction and Calibration of Numerical Ground-Water-Flow Models of the Western Half of the Milford-Souhegan Glacial-Drift 

Aquifer, Milford, New Hampshire
0 1,000 3,000 FEET

I I I i

(B)

0 1,000 2,000 FEET

I , i , . I I

Easternmost 

extent of model

Easternmost 

extent of model

Figure 11 . Advective transport of ground water from areas corresponding to the leading edge of the contaminant plume for the 

1988 model of the entire Milford-Souhegan glacial-drift aquifer (A), and 1994 model of the western half of the same aquifer (B), 

Milford, New Hampshire.

EVALUATION OF SELECTED MODEL PARAMETERS 25
WELL MW1 OB (317) 

LAYERS

Observed water levels 

Simulated low recharge 

Simulated medium recharge 

Simulated high recharge

JFMAMJ J ASOND 

1994

J F M A M J 

1995

Figure 12. Model-computed heads for low, medium, and high monthly recharge rates 

from the transient-seasonal simulation with the observed water levels at well MW-10B 

(well number 317, plate 1), Milford, New Hampshire.

shown in figure 12. The hydrograph is from well 

MW-10B (well number 317m, plate 1), located in the 

middle of the aquifer. The computed heads are closest 

to observed heads for simulations specifying high to 

medium recharge. The observed head fluctuation is 

3.7 ft and is caused primarily by the variability in 

recharge rates throughout the year. Low rates of 

recharge occur during the summer and early fall and 

high rates of recharge occur in the late fall, winter and 

early spring. Specifically, the analysis showed 

1. For wet periods of the year, which experience the 

highest amounts of recharge, such as the early 

spring, the high monthly recharge rates produce 

computed heads that best match observed water 

levels. Simulated fluctuations with lower 

assigned rates of recharge poorly approximated 

observed water-level fluctuations. Simulated 

results support the general field observations that 

surface runoff is minimal in the valley because

the low assigned recharge rates assumes that 

recharge is reduced by the diversion of precipitation to surface runoff in the valley. 

2. For dry periods of the year, the low to medium 

monthly recharge rates produce computed heads 

that best match observed heads. 

To quantitatively assess differences in model fit 

per season, model-computed heads were grouped by 

season and compared to observed seasonal averages. 

The results of this analysis is provided in table 5. The 

reported mean difference (standard error) represents 

the average difference between all computed and 

observed heads.

Results shown in table 5 indicate that the lowrecharge simulation underestimates heads during the 

winter and fall and that the high-recharge simulation 

best matches heads during this period. For the 

summer and fall, the medium-recharge simulation best 

approximates heads although there is little difference

26 Construction and Calibration of Numerical Ground-Water-Flow Models of the Western Half of the Milford-Souhegan Glacial-Drift 

Aquifer, Milford, New Hampshire
between the medium and low recharge for this period. 

In summary, the best match is produced from a 

combination of the medium recharge during the 

summer and fall and the high recharge during the 

winter and spring.

Although there is a seasonal variability in 

recharge rates, seasonal variability in precipitation is 

small (table 6). The variability in seasonal rates of 

recharge results primarily from seasonal variation in 

the ability of precipitation to recharge the aquifer. 

Many factors contribute to this temporal "recharge 

efficiency," the primary factor is most likely 

evapotranspiration. Seasonal evapotranspiration 

contributes to seasonal depletion of soil moisture and 

that controls recharge efficiency. The term "recharge 

efficiency" is a measure of the ability of precipitation 

falling onto the land overlying the aquifer to recharge 

the aquifer. For the summer and fall, ground-water 

recharge is about 27 percent of precipitation (low 

efficiency) and for the winter and spring, ground-water 

recharge is about 91 percent of precipitation (high 

efficiency). The annual ground-water recharge 

estimate is 24.2 in/yr or 58 percent of precipitation 

(total recharge is, therefore, 26.2 in/yr when incorporating estimates of lateral recharge), 75 percent of 

recharge specifically occurs in the late fall through 

early spring.

The overall sensitivity of the model to variable 

rates of recharge is spatially dependent. Near 

perennial streams, variations in recharge have a small 

effect on computed heads and vary by as little as 0.2 ft 

due to specification of high or low recharge. Away 

from perennial streams, variations in recharge affect 

heads by as much as 2.0 ft.

Table 5. Differences between computed steady-state heads 

and observed mean heads from biweekly measurements 

(June 1994 to June 1995) in the Milford-Souhegan glacialdrift aquifer, Milford, New Hampshire

[All units are in feet. Negative numbers mean computed heads are less than 

observed heads.]

Standard-mean error

Table 6. Seasonal precipitation, amount of recharge from 

precipitation, and percent of precipitation recharged to the 

Milford-Souhegan glacial-drift aquifer, Milford, New 

Hampshire

[Precipitation is measured in inches; percent is in parentheses]

Season

Summer

Fall

Winter

Spring

Annual

Low recharge

-0.23

-0.08

-0.60

-0.56

-037

Medium 

recharge

-0.04

-0.02

-0.53

-0.27

-0.22

High recharge

0.24

0.48

-0.08

-0.03

0.16

Season Precipita- Low Medium High 

tion recharge recharge recharge

Summer 21.33(100) 5.77(27) 5.88(28) 13.06(61) 

and fall

Winter and 20.16(100) 8.77(44) 12.79(63) 20.16(100) 

spring

The high and low monthly recharge rates 

produce similar temporal patterns of river seepage, 

except that the magnitude of river seepage varies 

depending on the recharge rates used (fig. 13). For 

example, high and low recharge show the same 

months of ground-water discharge to the aquifer. 

River gains (ground-water discharge from the aquifer) 

for subbasin 4 (plate 1) are shown in figure 13 by 

positive values of river seepage (0 to 2.0 ft3/s), and 

conversely, river losses (ground-water recharge from 

rivers to the aquifer) are shown by negative values of 

river seepage(0 to -0.8 ft3/s). Subbasin 4 is a strong 

ground-water discharge area. The western most extent 

of subbasin 4 is marked by the confluence of the 

Souhegan River with Purgatory Brook and its easternmost extent by the intersection of the Souhegan River 

with the eastern boundary of the model (plate 1; see 

also Harte and Mack, 1992, fig. 25). Computed river 

seepage for subbasin 4 of the aquifer is about 

50 percent higher for the high monthly recharge than 

for the low monthly recharge simulations.

The simulated results show that monthly 

recharge affects river leakage, however, river stage 

also affects river seepage. A sharp rise in river stage of 

several feet from snowmelt in December of 1994 

(fig. 9) results in river seepage to the aquifer (shown 

by negative river seepage values on fig. 13). The sharp 

rise in river stage causes a gradient reversal between 

the river and ground water.

Hydraulic Conductivity

Evaluation of hydraulic conductivity of the 

aquifer and sensitivity of the model to this parameter 

focused on refining the distribution of hydraulic 

conductivity that was based on additional data from 

test borings and wells constructed between 1992 and

EVALUATION OF SELECTED MODEL PARAMETERS 27
2.0

Q 1-5

Z

o 

o mCO 

CC 

HI 

D.

t;

o

m

O

z

Uj 0.5

101 

UI 

CO

cc

UI

cc 

o

-0.5

-1.0

I Low monthly recharge 

D High monthly recharge

it i___i

MAMJJASOND 

1994

J F M A M J J 

1995

Figure 13. Computed river seepage from the transient-seasonal simulation for subbasin 4 of the MilfordSouhegan glacial-drift aquifer, Milford, New Hampshire. (Location of subbasin 4 is shown on plate 1.)

1997. These new data suggest that bulk hydraulic 

conductivity of the aquifer could be higher than 

original estimates from previous work (Harte and 

Mack, 1992). From this new information, several 

areas were identified where higher hydraulic conductivity than previously assigned were justified, 

including the lower layers of the aquifer near the 

contaminant source area, a high hydraulic conductivity 

zone in the upper layer of the aquifer by the contaminant-source area (cobble zone), and a high hydraulic 

conductivity zone by the State Fish Hatchery wells.

The observation that some increases in 

hydraulic conductivity was justified is also supported 

by earlier sensitivity analyses done by Harte and Mack 

(1992). Their work showed that a spatiallydependent, improved match between computed and 

observed heads occurred when hydraulic conductivity 

was universally increased from that used for the 

calibrated model. Specifically, 11 out of the 17 zones 

of uniform hydraulic conductivity in the aquifer

showed an improvement (Harte and Mack, 1992, 

table 14). In contrast, an almost globally poor approximation of computed heads with observed heads 

occurred when hydraulic conductivity was universally 

decreased from the calibrated model. Differences 

between simulated and observed heads increased in 14 

out of 17 hydraulic conductivity zones with a universal 

decrease in hydraulic conductivity.

Improved knowledge of hydraulic properties of 

the aquifer by the contaminant source area result from 

detailed geologic mapping of subsurface deposits by 

NHDES (Camp Dresser and McKee Inc., 1995). 

Information from more recent lithologic logs showed 

two features that differed from previous logs. First, 

lower layers of the aquifer were shown to consist of 

more permeable sands than were shown in previous 

logs of the area, which showed thick till deposits. 

Second, a permeable cobble zone was delineated in the 

upper layer of the aquifer (fig. 4B).

28 Construction and Calibration of Numerical Ground-Water-Flow Models of the Western Half of the Milford-Souhegan Glacial-Drift 

Aquifer, Milford, New Hampshire
Increases in hydraulic conductivity of lower 

layers of the aquifer near the contaminant source area 

from 5 to 50 ft/d had a negligible effect on computed 

heads. The increases, however, affect travel times of 

average interstitial waters (advective transport of 

ground water) from the contaminant source area to 

final discharge locations. Steady-state tracking of 

ground-water particles was done for three zones of 

highly contaminated ground water (fig. 14) to evaluate 

the effects of increases in hydraulic conductivity on 

advective transport of contaminated ground water. 

Maximum travel times decreased five-fold from 63 to 

12 years as a result of specifying high values of 

hydraulic conductivity in layers 4 and 5 of the aquifer 

for simulated 1994-95 average annual conditions. 

These differences in travel times are due to increases 

in computed ground-water velocity in the lower layers 

of the aquifer resulting from the use of high hydraulic 

conductivities for the lower layers.

A three-fold increase in hydraulic conductivity 

of the uppermost layer of the aquifer by the contaminant source area (cobble zone) from 150 to 450 ft/d 

has a small effect on computed heads and river 

seepage. Nevertheless, small improvements in the 

model result. The standard mean error of the steadystate model decreased from -1.68 to -1.47 ft at well 

MW-28 (well number 234, plate 1) when simulating 

the cobble zone. Well MW-28 has the largest difference between simulated and observed heads near the 

source area. Steady-state river seepages and recharge 

to the aquifer between gages PI and P2 (plate 1) 

increased by 10 percent (from approximately 0.62 to 

0.68 f^/s) when simulating the cobble zone. These 

results are more consistent with observed measurements of river leakage that show higher rates of 

observed river leakage (Harte and others, 1997) than 

computed river seepage.

972,000 976,000 980.000

128,000

124,000

Simulated river cells 

Model simulation area \

Ground water pathline . showing travel time ^ 

of one year showing 

direction of movement

 Starting location - 

Vertical profile and 

tetrachloroethylene 

(PCE) concentration, 

in parts per billion (ppb) 

(see inset map)

0 1,000 2,000 FEET

i i i

Figure 14. Steady-state simulation of advective transport of ground-water particles showing pathlines from high zones of 

contamination to final discharge locations, Milford-Souhegan glacial-drift aquifer, Milford, New Hampshire.

EVALUATION OF SELECTED MODEL PARAMETERS 29
River-aquifer Interactions

River-aquifer interactions exert a major 

influence on ground-water flow in the aquifer. 

Perennial and ephemeral streams are sources of 

ground-water recharge in some areas of the aquifer, 

and in other areas they are sinks that receive groundwater discharge. Perennial streams in the model have 

the capability of exchanging large amounts of water to 

the aquifer because they are head-dependent 

boundaries. For this reason, accurate estimates of 

riverbed hydraulic parameters are needed to ensure 

accurate calculations of river seepage.

A previous analysis of steady-state river seepage 

in the aquifer showed that net river seepage was 

generally insensitive to increases in riverbed conductance (leakance multiplied by river area) but was 

adversely affected by decreases in riverbed conductance (Harte and Mack, 1992, p. 58). Therefore, 

additional model testing with the current model 

focused on evaluating simulations where increases in 

riverbed conductance were specified. Testing with the 

1994 model showed that the net rate of river seepage 

generally was similar among model simulations with 

an increase in riverbed conductance greater than the 

final river conductance used for the model. Although 

the net rate of river seepage throughout the simulated 

aquifer and within subbasins in the aquifer showed 

little change with uniform increases in riverbed 

conductance, the amount of river seepage per 

individual model cell changed significantly.

Two steady-state simulations were made to 

evaluate the effect that increases in riverbed conductance had on model results. Riverbed conductances 

were increased by a factor of 2 and 10 from the base 

value. A comparison of head differences showed that 

the standard mean-head error and absolute mean-head 

error are similar between the base simulation and the 

simulation with conductance doubled. Head errors 

increased between the base conductance and the 

simulation with a 10-fold increase in conductance. 

Differences in net river leakage across the aquifer and 

within subbasins of the aquifer were negligible; 

however, the magnitude of river leakage into and out 

of the aquifer changed by 40 percent (table 7).

Computed aquifer recharge (streamflow loss) 

and discharge (streamflow gains) patterns along the 

Souhegan River are similar for the riverbed conductances evaluated. The distribution of computed river 

seepages of the Souhegan River shows that up to a

Table 7. Rates of river leakage for increases in riverbed 

conductance in the Milford-Souhegan glacial-drift aquifer, 

Milford, New Hampshire

[All units in ft3/s; negative values indicate streamflow loss]

River leakage

Steady-state . . ^ , Out of the Netchan9e 

, .. Into the aquifer .. in river simulation . .. aquifer . . (aquifer . ., leakage L. » (aquifer a recharge) . . . 

a ' discharge)

Base case 3.98

Ten times riverbed 5.72

conductance of

base case

Two times riverbed 4. 1 9

conductance of

base case

3.63 -0.35

6.07 -0.35

3.92 -0.27

State Plane coordinate easting location of 977,800 ft 

on the Souhegan River (fig. 15, reach number 360, 

plate 1), river seepage into the aquifer occurs and the 

river recharges the aquifer. East of easting location 

977,800 ft and reach number 360, aquifer discharge 

occurs for the base conductance (15A) and the simulation with a ten-fold increase in conductance. The 

largest rates of aquifer recharge from the river in both 

simulations occur by the State Fish Hatchery wells 

(FH-4, FH-5, plate 1) from withdrawals at these wells.

The general pattern of river seepage is similar 

for the riverbed conductances evaluated, but the 

magnitudes of river seepage differ for the two simulations. For the base simulation, withdrawals at the 

State Fish Hatchery (FH-4, FH-5, plate 1) cause 

smaller rates of aquifer recharge immediately adjacent 

to the well but induce greater rates of river leakage and 

aquifer recharge upstream of the State Fish Hatchery 

wells (between reach numbers 100 and 200, fig. 15A) 

than the simulation with increased riverbed conductance. Furthermore, downstream of the State Fish 

Hatcheries, aquifer discharges are much greater for the 

simulation with riverbed conductances at 10 times the 

base conductance than the simulation with the base 

conductance.

Although not shown in figure 15, differences in 

the rates of computed river seepage on the Souhegan 

River between the base simulation and the simulation 

with a two-fold increase in conductance are much 

smaller than those illustrated in figure 15. To help 

identify changes in model results caused by doubling 

the conductance, a spatial analysis of head differences

30 Construction and Calibration of Numerical Ground-Water-Flow Models of the Western Half of the Milford-Souhegan Glacial-Drift 

Aquifer, Milford, New Hampshire
(A) 0.10

D-UJ tH°- o

orai

UJll-

>o 

0:5

o

-0.10

-0.11

(B)

(C)

(D)

0.20

0

28 0.10

. Q-LU 

LUD. 

III. we

0:111 uju- >00:5 

o

-0.10 -

-0.11 

0

0.10

AQUIFER DISCHARGE

200 400 600 800

AQUIFER RECHARGE

AQUIFER DISCHARGE

200 400 600

RIVER REACH NUMBER

800

1.000 1.100

1,000 1,100

EXPLANATION 

0 Active withdrawal well

Figure 15. Model-computed river seepage for base riverbed conductance (A), ten-fold increase in riverbed conductance (B), difference in base value and ten-fold increase (C), and location map of simulated reach (D), Milford-Souhegan 

glacial-drift aquifer, Milford, New Hampshire.

EVALUATION OF SELECTED MODEL PARAMETERS 31
was done between the base riverbed conductance and 

the simulation with a two-fold increase in riverbed 

conductance. Head differences between the two 

simulations are small and generally less than 1 ft 

(fig. 16). In general over most of the aquifer, 

computed heads from the simulation with a uniform 

two-fold increase in riverbed conductance do not 

match observed heads better than computed heads 

match observed heads from the simulation with base 

conductance. There are selected areas in the aquifer 

where some improvements in match did occur, namely 

by State Fish Hatchery wells, by well number 309, 

307, and 209 (well cluster MW-1, appendices 2 and 4), 

and by some of the wells near the source area. Results 

imply spatial heterogeneity of riverbed conductance, 

such that an increase in riverbed conductance in 

upstream reaches of the Souhegan River and Tucker 

Brook, could improve model results.

Unlike the results from changing riverbed 

conductances, which generally had a small effect on 

computed heads, variations in river stage have a large 

effect on heads. Uniform increases in river stage 

caused an equivalent uniform increase in computed 

head. For example, a uniform river stage increase of 

2 ft also caused an average rise in head of 2 ft. 

Furthermore, patterns and rates of river seepage were 

relatively unchanged with uniform increases in river 

stage, unlike variations in riverbed conductance that 

had a large effect on rates of river seepage.

Seasonal fluctuations in river stage also affect 

computed heads in the seasonal-transient simulations. 

The effect of river-stage fluctuations on computed 

heads is greatest near perennial streams, but riverstage fluctuations also affect computed heads further 

away from perennial streams. Two transient simulations were run to evaluate the effect that river-stage 

fluctuations have on computed heads. All model 

parameters in the two simulations were kept the same 

except for river-stage fluctuations, which were varied 

monthly based on observed river stages in one simulation and kept constant at the observed mean stage in 

the other. The results of the simulations are shown in 

figure 17 for well MI-18 (well number 29, plate 1). 

Fluctuations in river stage enhance fluctuations in 

computed heads and cause increases in computed 

heads by approximately 25 percent over computed 

heads for the constant river stage simulation during the 

spring of 1994 and 1995.

Storage Properties

Specific yield and storage coefficient were 

varied in the transient-seasonal model in a series of 

simulations to evaluate the effect of storage properties 

on model results. Values of storage that were tested 

represent the most probable ranges of storage given 

the types of sediments in the aquifer and degree of 

uncertainty of variations in aquifer properties. 

Specific yield was varied from 0.15 to 0.30 with an 

aquifer-wide base value of 0.23. Storage coefficient 

was varied from 0.00005 to 0.003, with a base value of 

0.0003. The results of computed heads are shown in 

figure 18 for well MI-18 (well number 29, plate 1).

Fluctuations in computed heads using low to 

high values in storage are generally small and differ by 

less than 0.7 ft (fig. 18). From June 1994 to June 

1995, when observed data are available for comparison, computed-head fluctuations (the difference 

between the minimum and maximum heads) ranged 

from 1.73 ft for high storage values, 2.05 ft for base 

storage values, and 2.42 ft for low storage values. The 

aquifer at well MI-18 (fig. 18) is more sensitive to 

variations in storage properties than areas that are 

closer to perennial streams. Near perennial streams, 

head fluctuations from variations in storage properties 

are smaller than fluctuations at locations further away 

from streams.

The analysis of the effects of storage properties 

of the aquifer on model results indicates that the 

transient-seasonal model of flow is less sensitive to 

uncertainties in this parameter than in the recharge 

parameter, and, therefore, the model is a useful tool in 

providing estimates of seasonal recharge. At well 

MI-18, and in other areas of the aquifer distant from 

perennial streams, variations in estimates of recharge 

caused a larger difference in computed heads than did 

variations in storage properties. For example, at well 

MI-18, the maximum difference in head between 

simulations of low and high recharge was 1.2 ft, 

whereas the difference in head from storage variations 

in storage properties was 0.7 ft.

32 Construction and Calibration of Numerical Ground-Water-Flow Models of the Western Half of the Milford-Souhegan Glacial-Drift 

Aquifer, Milford, New Hampshire
>

I

o n

m 

m3 

oB

.3 Improvement In match with observed 

model run 94-44 and 94-47

Decrease In match with observed 

model run 94-44 and 94-47

Aquifer boundary

0-5 Contour line showing head differences,

In feet, for a two-fold increase in river bed conductance 

Well

? Unknown data

Planlmetrlc base by U.S. ERA Re^.w.. , * from aerial photographs token 1967___)

KILOMETER

Figure 16. Differences in simulated head for a two-fold increase in riverbed conductance, Milford-Souhegan glacial-drift aquifer, 

Milford, New Hampshire. (Locations of wells are shown on plate 1.)
259

I 258

I

m

b

- 257

o

co 256

255

i i r i i

Computed head with fluctations 

in river stage

Computed head with constant 

river stage

i___i___i___i___i

J FMAMJ J ASOND

1994

J FMAMJ 

1995

Figure 17. Transient model-computed heads at well MI-18 from simulated seasonal fluctuations in river stage, 

Milford-Souhegan glacial-drift aquifer, Milford, New Hampshire. (Location of well is shown on plate 1.)

260

259

CD

Si 258

3LU

X 257

O

LU

258

LU 

O

i r i i i i i

- Base Storage: Sy = 0.23 and Sc = 0.0003

- - High Storage: Sy = 0.3 and Sc = 0.003

- - - - Low Storage: Sy = 0.15 and Sc = 0.00005

i____i_____i_

J FMAMJ J ASOND

1994

J FMAMJ 

1995

Figure 18. Transient-seasonal model-computed heads at well MI-18 from simulations of aquifer storage, MilfordSouhegan glacial-drift aquifer, Milford, New Hampshire. (Sy = specific yield, Sc = storage coefficient, Location of well 

is shown on plate 1.)

34 Construction and Calibration of Numerical Ground-Water-Flow Models of the Western Half of the Milford-Souhegan Glacial-Drift 

Aquifer, Milford, New Hampshire
RESULTS OF SIMULATIONS WITH FINAL 

CALIBRATED MODEL

The final calibrated steady-state and transientseasonal models use the same data-input values for 

model parameters of hydraulic conductivity, riverbed 

conductance, and altitude of riverbed, but use different 

values for model parameters that change with time, 

such as river stage, rates of ground-water recharge, and 

ground-water withdrawals. It is important to consider 

these differences when judging the adequacy of 

steady-state and transient-seasonal model performance.

Steady State

The final volumetric budget for the steady-state 

model is given in table 8. Large amounts of groundwater withdrawals from wells in the aquifer 

(4.18 ft3/s) result in a net influx of 0.35 ft3/s 

(computed from the difference between the input river 

seepage (3.98 ft3/s) and the output river seepage 

(3.63 ft3/s)) of river seepage into the aquifer (river 

loss).

Computed heads from the steady-state model 

closely approximate the arithmetic mean of the 

biweekly measured heads from the observed wells 

measured between June 1994 and June 1995 

(appendix 3). The standard mean error is -0.12 ft, the 

absolute mean error is 0.59 ft and the root-meansquare residual (RMSE) is 0.89 ft. Head loss across 

the western aquifer is approximately 30 ft, therefore, 

an error of less than 1 ft represents a relative error of 

3 percent. The 1994 model's approximation of 

observed heads is a significant improvement over the 

1988 model's (Harte and Mack, 1992), which had a 

standard error of 0.78 ft and an absolute error of 

1.81 ft when compared to observations of heads made 

in October of 1988 at 44 wells.

A spatial plot of head residuals shows that most 

computed heads (approximately 90 percent) are within 

1.0 ft of observed heads (fig. 19). The largest difference in head is -4 ft (computed head less than observed 

head) and occurs at observation well FH5-obs (well 

number 240, plate 1), which is located within 5 ft of 

the State Fish Hatchery withdrawal well FH-5 (well 

number 208, plate 1). Large head differences are 

expected near withdrawal wells and the relatively poor 

match may be the result of several factors unrelated to

Table 8. Volumetric budget for the steady-state simulation 

(1994-95) of the Milford-Souhegan glacial-drift aquifer, 

Milford, New Hampshire

[Model area is 46.011, 180 ft2; ft3/s, cubic foot per second; in/yr, inch per 

year (For conversion from ft3/s to in/yr multiply by 8.2304)]

Inflow/ 

outflow

Inflow

Outflow

Mass balance

error

Source

Eastern general-head 

boundary

Wells

Recharge

River seepage

Eastern general-head 

boundary

Wells

River seepage

Budget 

inftVs

0.67

0

3.26

3.98

.10

4.18

3.63

0

Budget 

in in/yr

5.5

0

26.8

32.8

.8

34.4

29.9

0

model performance. These factors may include 

discrepancies between the location of the computed 

head, which in a finite-difference solution occurs at the 

cell's node, and the observed head, and the difference 

between a diffuse sink that is simulated in numerical 

models and a point sink that occurs in the field.

Computed vertical-head gradients are small and 

head differences are generally less than 0.01 ft 

between model layers. Observed vertical-head 

gradients from clustered wells in the aquifer generally 

show gradients between 0 to several tenths of a foot. 

The discrepancy between computed and observed 

vertical- head gradients is likely related to vertical 

heterogeneity in the aquifer that is not adequately 

represented by the model. Although model-computed 

head differences are small, the simulated model appear 

to approximate patterns of vertical flow in the aquifer 

(fig. 20) and show downward flow in recharge areas 

adjacent to areas of river seepage to the aquifer (such 

as near MW-11 cluster, well numbers 318 and 319, 

plate 1, appendix 2) and upward flow in discharge 

areas to the river (such as near MW-24 cluster, well 

numbers 255 and 333, plate 1, appendix 2).

Computed river seepages compare favorably 

with observed river leakages. Results of computed 

river seepage from two steady-state simulations using 

the 1994 model are given in table 9 and demonstrate 

the match between computed patterns and rates of 

river seepage and observed patterns and rates of river 

leakage. Observed river leakages are derived from

RESULTS OF SIMULATIONS WITH FINAL CALIBRATED MODEL 35
w

01

> o

J3 O

C 3

f!

3. | i SL

iii. p o

S SS

C <DI

O

5

I

Aquifer boundary

 1.0 Line of equal difference, in feet, between 

computed and observed heads

A Well

Planlmetrtc base by U.S. ERA Region 1 

from aerial photographs token 1987

KILOMETER

1____I

Figure 19. Head residuals (differences) between steady-state computed heads and observed heads calculated from the arithmetic mean 

of the biweekly measured water levels, Milford-Souhegan glacial-drift aquifer, Milford, New Hampshire. (Locations of wells are shown on 

plate 1.)
Column Released 

1 11

Column

111 

MW-24

Column 

189

Souhegon River 

Water-table surface

1,000 2,000 FEET

VERTICAL EXAGGERATION X 10.0

EXPLANATION

-B ^ Direction of ground-water pathline and

yearly travel times of advective transport

Figure 20. Cross section of steady-state advective transport of ground-water particle showing pathline projected along row 80, 

Milford-Souhegan glacial-drift aquifer, Milford, New Hampshire. (Row 80 location is shown on plate 2.)

Table 9. Summary of river seepages from steady-state 

simulations and measured river leakages in subbasins of the 

Milford-Souhegan glacial drift aquifer, Milford, New 

Hampshire

[All units are in cubic foot per second; negative value in column of 

measured net river leakage means streamflow loss; negative value in 

columns of computed river leakage mean aquifer recharge; computed river 

seepages from 1994 model]

Subbasin 

(plate 1)

2

3

4

5

6

8

9

Measured net 

river seepage 

1988

-0.18

0.05

1.58

-0.27

-0.73

-0.31

-0.47

Computed 

river seepage 

from simulation of 1988

0.24

0.29

1.56

-0.77

-1.41

0.10

-0.38

Computed 

river seepage 

from simulation of 1994-95

0.28

0.25

1.44

-0.67

-1.22

-0.05

-0.33

streamflow measurements made in October of 1988. 

The values of river leakage represent net river leakage 

within subbasins of the aquifer (the location of 

subbasins are shown in plate 1). The results presented 

in table 9 are from two steady-state simulations, 1994- 

95 conditions, discussed in this report, and October 

1988 conditions, discussed in Harte and Mack (1992). 

The two simulations differ in simulated ground-water 

withdrawals. The simulation results of October 1988 

allow for a direct comparison between computed river 

seepage and observed river leakage because aquifer

withdrawals changed between 1988 and 1994-95, and 

consequently, these changes affected patterns and rates 

of river seepage. Specifically, withdrawals decreased 

in industrial wells MI-88 and MI-33 (well numbers 

395 and 47, fig. 2 and plate 1), and increased in private 

fish hatchery well PFH and State Fish Hatchery well 

FH-4 (well number 354 and 87, fig. 2 and plate 1). 

The average rate of withdrawal in 1988 was 4.38 ft /s 

and in 1994 it was 4.18 ft3/s. Computed river seepages 

from the simulation of 1988 show greater recharge 

from rivers, river seepage from rivers into the aquifer 

(streamflow loss), than the amount of river recharge 

from 1994-95.

Computed-river seepages also were compared to 

the arithmetic mean of observed river leakages from 

multiple streamflow measurements made in 1994-95 

between river-gaging stations PI and P2. Computedriver seepage between gages PI and P2 is significantly 

smaller (-0.63 ft3/s; negative indicating streamflow 

loss and potential aquifer recharge) than the observed 

arithmetic mean of the difference between 13 coupled 

measurements of streamflow (-5.5 ft3/s). The 

procedure for computing river leakage from coupled 

streamflow measurements is discussed in detail in 

Harte and others (1997). The nine-fold difference 

between simulated and observed is not attributed to 

uniform increases in riverbed conductance or aquifer 

hydraulic conductivity because these parameters were 

varied by factors of 10 and 3, respectively, with only 

minor differences in computed river seepage (less than 

several tenths of ft3/s). Rather, the large difference is

RESULTS OF SIMULATIONS WITH FINAL CALIBRATED MODEL 37
attributed to (1) the inducement of large river leakage 

during short-term (less than 24 hours) hydrologic 

conditions that are not adequately simulated under 

average annual steady-state conditions, and (2) vertical 

heterogeneity of aquifer hydraulic conductivity. For 

example, with regard to the former, discrete 

hydrologic events such as sharp increases in river stage 

during high streamflow conditions, will induce large 

amounts of river leakage into the aquifer. Several of 

the coupled streamflow measurements were made 

during high streamflow (flow duration of 35 percent or 

less). These events are averaged and thus not 

represented in steady-state models nor in transient 

models with time discretizations greater than one day. 

Therefore, the impact of discrete hydrologic events on 

the ground-water system can not be assessed with this 

model. The effect of vertical heterogeneity on river 

leakage is discussed in the section on the transientseasonal model.

Steady-state advective transport of ground-water 

particles were tracked forward from the 1,000 ppb line 

of equal concentration distribution of tetrachloroethylene (PCE) from 1989 (fig. 10) for 5 years and 

compared to the 1994 distribution of PCE. During this 

period, increases in withdrawals at the State Fish 

Hatchery wells and decreases in withdrawals at wells 

along the southern part of the plume have caused a 

northward shifting of ground-water pathlines (Harte 

and Willey, 1997). Comparing advective transport of 

particles to the plume during this period helps 

constrain average interstitial velocities of the flow 

model and also helps to identify the role advective 

transport plays in contaminant transport. For example, 

if advective-transport velocities in the flow model 

were too slow, pathlines would be significantly slower 

than the observed plume. Tracked ground-water 

particles started in 1989 shifted about 2 times the 

distance after 5 years than the observed 1,000 ppb 

line-of-equal concentration did in 1994 (fig. 21). It 

appears that the computed advective transport 

pathlines respond quicker than the observed plume 

suggesting some retardation of contaminants.

Transient Seasonal

Seasonal ranges in the volumetric budget for the 

final-calibrated transient model of seasonal conditions 

are significant and show a lag effect between aquifer 

recharge and discharge of ground water to the river 

(table 10). Largest amounts of recharge occur in the 

fall and winter seasons for the simulated period 

(June 1994-95). In contrast, the largest amounts of

ground-water discharge to the rivers occurred in winter 

and spring. Therefore, the increases in fall recharge 

appear to affect aquifer discharge the most in the 

following season. The lag effect reflects the ability of 

the aquifer to store recharge and is most evident in the 

fall because recharge in the fall replenishes the low 

storage of ground water in the aquifer caused by the 

preceding low rates of recharge in the summer. As a 

result, maximum increases in storage occur in the fall.

Summation of components of the seasonal 

volumetric budget shows there is a small change in 

aquifer storage during the simulated period of June 

1994-95. The total for storage is 0.93 ft3/s, which 

equals an average annual rate of 0.23 ft3/s; therefore, 

water from storage is being released over the annual 

cycle at a rate of 0.23 ft /s. Compared to the 

summation products of the other budget components, 

water in storage represents a small part (only 5.5 

percent) of available sources of water. Recharge, river 

leakage, and water from the eastern boundary are the 

primary sources of water and contribute 74, 9.5, and 

11 percent of water respectively.

Results of the analysis of seasonal volumetric 

budgets suggests that a true average annual steadystate condition probably does not exist because a net 

storage change occurs over the annual cycle. The 

amount of storage change is relatively small and the 

system is in dynamic equilibrium. This is probably a 

typical storage response of this type of aquifer because 

the aquifer is permeable and recharge boundaries like 

the river supplement storage and force quick equilibration of the system.

Use of the seasonal-transient model adequately 

approximates6 observed-head fluctuations from 

biweekly measurements of heads at observed wells 

(table 11). Seasonal comparisons of simulated and 

observed heads show that the largest average head 

difference between computed and observed occurs in 

the fall of 1994.

A statistical summary of variations in the 

direction and slope of simulated maximum groundwater hydraulic gradients from seasonal conditions 

(June 1994-95) is given in table 12. Model-computed 

and observed heads were analyzed by triangular 

grouping of wells (fig. 22) to allow for computation of 

direction and slope of maximum ground-water 

hydraulic gradients by three-point planar solution 

(Johnston and Harte, 1998).

6An example of head comparisons between computed and 

observed can be seen in appendix 5.

38 Construction and Calibration of Numerical Ground-Water-Flow Models of the Western Half of the Milford-Souhegan Glacial-Drift 

Aquifer, Milford, New Hampshire
RESULTS OF SIMULATIONS WITH FINAL CALIBRATED MODEL 39
Table 10. Volumetric budget from June 1994-95 from the transient-seasonal-model simulation of the Milford-Souhegan 

glacial-drift aquifer, Milford, New Hampshire

[Model area is 46,011, 180 ft2: ft3/s, cubic foot per second; in/yr, inch per year; For conversion from ft3/s to in/yr multiply by 8.2304; positive value means 

recharge to the aquifer; negative value means discharge of water from the aquifer; a positive value for storage means water coming out of storage while a 

negative value means water going into storage]

Budget components

Net volumetric budget, 

in ft3/s Cumulative budget,

Storage

Wells

Recharge

River seepage

Eastern general-head boundary

Summer 1994

1.15

-4.39

1.21

1.09

0.93

Fall 1994

-2.93

-4.39

4.71

2.29

0.32

Winter 1994-95

0.84

-4.16

4.25

-0.95

0.03

Spring 1995

1.87

-4.05

2.38

-0.82

0.57

0.93

-16.99

12.55

1.61

1.85

Table 11. Differences between computed seasonal mean heads and observed seasonal mean heads from the transientseasonal-model simulation of the Milford-Souhegan glacial-drift aquifer, Milford, New Hampshire

[All units are in feet. Negative numbers mean simulated heads are below observed heads in biweekly measurements of heads in observed wells, appendix 3]

Season Standard head difference Absolute head difference

Summer, 1994 

Fall, 1994 

Winter, 1994-95 

Spring, 1995 

Annual

0.03

0.29

-0.01

-0.10 

0.05

0.55

0.62

0.71

0.62

0.63

Table 12. Statistics from model-computed and observed direction and slope of maximum ground-water hydraulic gradients 

from triangular grouping of wells, June 1994-June 1995, Milford, New Hampshire

[Triangle locations are shown in figure 22; to convert slope, in degrees, to slope in foot per foot, take the tangent of the value of slope in degrees; triangles 

listed in descending order of standard deviation]

Direction of maximum ground-water gradient

Observed

Triangle

M

J

B

D

H

E

C

A

N

G

I

K

F

L

Mean direction, standard

in f9reeSI°m Nation 

true north

86.3

77.2

131.5

11.0

52.3

86.8

75.5

125.4

82.0

67.9

31.2

52.8

48.9

53.8

50.9

33.9

4.3

9.4

5.6

5.1

4.3

4.1

3.2

2.9

2.5

2.2

2.1

1.6

Model computed

Mean direction, 

in degrees from 

true north

52.5

127.5

81.0

3.9

63.0

87.8

70.1

110.8

55.4

68.6

52.6

55.1

41.6

57.5

Standard 

deviation

7.1

8.3

4.6

7.5

4.8

4.2

3.1

3.5

6.8

4.3

2.7

5.2

2.6

4.1

- Triangle

D

B

M

A

J

E

N

H

K

G

I

F

L

C

Slope of maximum ground-water gradient

Observed

Mean slope, 

in degrees

0.537

.429

.206

.401

.131

.207

.223

.258

.184

.142

.177

.196

.191

.273

Standard 

deviation

0.113

.084

.078

.056

.032

.026

.020

.018

.011

.008

.007

.007

.006

.003

Model computed

Mean slope, Standard 

in degrees deviation

0.682

.360

.137

.287

.181

.188

.184

.173

.183

.235

.244

.223

.202

.252

0.125

.013

.030

.026

.031

.006

.005

.003

.007

.008

.011

.013

.009

.006

40 Construction and Calibration of Numerical Ground-Water-Flow Models of the Western Half of the Milford-Souhegan Glacial-Drift 

Aquifer, Milford, New Hampshire
71-42'

' \ *

\ I

* I

_ I 1

*~ \ I » 

0 0.1 02 0.3 0.4 0.5 KILOMETER

EXPLANATION 

 Boundary of Aquifer

Triangle of 

Adjoining Weds

SavageWM(128> Wen Name and

Number for Unused 

Wen

Wen and Number 

Used for TriangulaBon of Water Level

Wells

43.203,234

43.234.335

228,318.335

240,310.318

23.293.296

220.296.349

255.308.349

233,308.315

220,308.349

89.281.306

220,228.255

220.255.296

281.288.292

233,255.308

Figure 22. Triangular groupings of biweekly measured wells for determination of model-computed and observed ground-water 

hydraulic gradients, Milford-Souhegan glacial-drift aquifer, Milford, New Hampshire. (From Harte and others, 1992)

The transient-seasonal model adequately 

approximates the observed direction of maximum 

slope in most areas of the model except three: the area 

west and upgradient of the source area (triangle B), by 

the confluence of Purgatory Brook and the Souhegan 

River (triangles J and M), and the northcentral part of 

the contaminant plume (triangle N). The maximum 

difference between the model-computed and observed 

directions of maximum gradient occurs at triangle B 

(table 12). A possible explanation for the difference in 

direction is inadequate specification of river stage in 

the model, which linearly slopes between gaging 

stations PI and P2 (plate 1). The presence of riffles 

and pools between PI and P2 on the Souhegan River 

supports the fact that the river slope is not linear and 

that a non-linear slope of the river probably would 

produce a better match. At triangles J and M, two 

possible factors that could be attributed to the discrepancy are (1) inadequate specification of river stage 

along Purgatory Brook and (2) oversimplification or

lack of aquifer heterogeneity. These factors cause the 

advective transport of ground water to completely 

discharge to the Souhegan River rather than be 

partially transported underneath the Souhegan River as 

indicated by the observed chemical data.

Simulated slopes of maximum gradients from 

triangular groupings of wells are fairly evenly split 

between being greater than or less than the observed 

maximum gradients and, therefore, show no strong 

deficiency of the model to approximate observed 

conditions. The maximum difference between modelcomputed and observed slope is located downgradient 

from the source area (triangle A). The computed 

gradient is -0.114 degrees (-0.002 ft/ft) less than the 

observed gradient (0.007 ft/ft), a difference of 

29 percent.

The observed slope of maximum gradient at 

triangle A is negatively correlated (-0.88) with the 

height of the water table (fig. 23). Lowest gradients 

occur with the highest positioning of the water table

RESULTS OF SIMULATIONS WITH FINAL CALIBRATED MODEL 41
01

DC 

O

0.50

0.48

0.46

0.44

0.42

Q 0.40

Z

g 0.38

I

O 0.36 

0.34 

0.32 

0.30 

0.28

261.5 262.0 262.5 263.0 263.5 264.0

MEAN HEAD, IN FEET ABOVE MEAN SEA LEVEL

264.5 265.0

Figure 23. Ground-water gradients in relation to positioning of the water-table surface for triangle A, MilfordSouhegan glacial-drift aquifer, Milford, New Hampshire. (For location of triangle A, refer to figure 22.)

(the positioning of the water table was computed from 

the mean water level from the three wells comprising 

triangle A and is specified as the mean head in the 

abscissa of figure 23. Because the upper aquifer at the 

source area contains cobble deposits and these 

deposits are only partially saturated during conditions 

of average to below-average water levels, the degree of 

saturation of the cobble zone could control gradients. 

The lithologic evidence suggests the aquifer is 

vertically heterogeneous, with the greatest hydraulic 

conductivity near the top of the aquifer. With this type 

of hydraulic-conductivity distribution, the bulk 

transmissivity of the aquifer is highly sensitive to the 

position of the water table. As the water table rises, 

large increases may occur in the bulk transmissivity of 

the aquifer producing a decrease in hydraulic gradient.

Computed river seepage into the aquifer 

between gaging stations PI and P2 ranges from 0.34 to

o

1.19 ft /s (fig. 24A). Maximum river seepage

occurred in December of 1994 and minimum river 

seepage in January 1995. The computed range in river 

seepage is much lower than the observed-river leakage 

(measured) range. Whereas seepage is comprised only 

of ground-water recharge and discharge to the river, 

leakage can include other processes such as runoff and 

back storage. Field data indicate a minimum leakage 

of -6.6 ft3/s (discharge to the river) and a maximum 

leakage of 23 ft /s (recharge to the aquifer) (fig. 24B). 

Time discretization, as well as vertical heterogeneity, 

also causes an underestimation of simulated variability 

in river leakage. A coarse time discretization with 

relatively large time steps, as used in the transientseasonal model, reduces computed variability.

The transient-seasonal model simulates 15-day 

periods of time with constant monthly parameters and 

stresses (except in September 1994). This time step 

tends to average the effects of short-term responses in 

the aquifer to hydrological events. One of the most

42 Construction and Calibration of Numerical Ground-Water-Flow Models of the Western Half of the Milford-Souhegan Glacial-Drift 

Aquifer, Milford, New Hampshire
(A)

0.2

M A 

1995

M J

DATE, ON DAY 15 AND 30 OF EACH MONTH, 1994 AND 1995

(B)

20

O 

Z

O 15 

.O 

UJ W

HI LL.

= 0

o

-5

-10

P1 tO P2

Loss in leakage

A M J J ASONDIJFMAMJ 

1994 1995

Figure 24. Model-computed river seepage between river gaging stations P1 and P2 for transient-seasonal 

simulation (A), and measured river leakage for the same reach (B), Milford, New Hampshire.

RESULTS OF SIMULATIONS WITH FINAL CALIBRATED MODEL 43
important factors in river seepage to the aquifer is the 

rate at which river stage increases relative to the rise of 

ground-water levels. High rates of river leakage into 

the aquifer will occur in losing river reaches when 

river stages increase quickly relative to ground-water 

levels. Because river stage is averaged over a monthly 

period and the minimum time step is 15 days, 

variations in river leakage are underestimated by the 

model. To test this hypothesis, time-discretization was 

increased in December of 1994 to simulate the 

observed rise in river stage over a single day, instead of 

a month. The increased time discretization alone 

resulted in a computed river seepage 3-times the 

15-day rate of 1.19 ft3/s. It is expected that further 

refinement of time steps would increase seepage.

SUMMARY AND CONCLUSIONS

The Milford-Souhegan glacial-drift aquifer 

(MSGD) aquifer is highly permeable with relatively 

rapid advective transport. The western half of the 

aquifer is contaminated by a plume of volatile-organic 

compounds (VOC's), primarily tetrachloroethylene 

(PCE), that covers a 0.5 mi2 area. The primary source 

of contamination was from a discontinued tool 

company that discharged contaminants into the 

subsurface for many years until the early 1980's. 

Although these discharges have ceased, contaminants 

continue to desorb from the underlying sediments, and 

immiscible fluids continue to contaminant ground 

water flowing under the site.

This report summarizes construction and 

calibration of three-dimensional, steady-state and 

transient numerical ground-water flow models that 

will be used to help in the design of a remediation 

plan, and to monitor the VOC plume. The model area 

covers 1.65 mi2, has more than 70,000 active cells 

with smallest cell sizes of 25 by 50 ft, and consists of 

5 model layers of approximately 20-feet thick. The 

steady-state model closely approximates observed 

heads and river leakages throughout much of the 

aquifer. Most computed heads are within 1.0 ft of 

observed heads computed from the arithmetic mean of 

biweekly measured heads for one year. Steady-state 

river leakages also match observed river leakages 

fluxes from one round of measurements of river 

leakages. The calibrated transient model, which 

simulates seasonal conditions, showed that annual 

recharge to the aquifer is approximately 60 percent of 

precipitation. Recharge is nonuniformly distributed

throughout the year and most recharge occurs when 

evapotranspiration is negligible. This causes large 

seasonal variations in recharge and discharge of 

ground waters. Seasonal variations in ground-water 

flow are also highly affected by variations in river 

stage, which cause large changes in the direction of 

ground-water flow and changes in the slope of 

maximum hydraulic gradients. Simulated flow 

(seepages and gradients) varied the most near the river.

The transient-seasonal model closely approximates the observed-head fluctuations in the aquifer. 

The largest differences between model-computed and 

observed heads were those for the fall of 1994 

(standard-mean-head error of 0.29 ft). The transient 

model underestimates the observed variation in river 

leakages, partly because leakages incorporate other 

processes besides ground-water flow, but also because 

of the 15-day time step used in the transient model. 

Computed river seepages varied by a factor of 10 

while the observed leakages varied by a factor of 

several hundred at one losing river reach where more 

than 13 coupled measurements of streamflow were 

made throughout the year. The unfavorable comparison suggests that the time discretization of the 

transient model can be used to estimate fluctuations in 

head, but cannot estimate the short-term dynamics of 

river-aquifer systems.

Ground-water flow and advective transport 

throughout most of the aquifer and contaminant plume 

area can be estimated using the transient-seasonal 

model. Several modeling deficiencies were detected 

that warrant further analysis; these are (1) a tendency 

for computed discharges to the Souhegan River in the 

area by the confluence between the Souhegan River 

and Purgatory Brook (see the area by triangle J in 

figure 22) to be greater than observed, (2) low 

computed heads in the State Fish Hatchery area could 

cause a more northerly trajectory of ground-water flow 

than observed in the northcentral part of the plume 

(see the area by triangle D in figure 22), and (3) the 

river stage and the vertical heterogeneity of the aquifer 

near the source area of the plume (see the area by 

triangle B in figure 22) is oversimplified. Possible 

solutions to reduce these discrepancies include 

(1) collecting additional river stage information in the 

areas near the source area and the confluence of the 

Souhegan River and Purgatory Brook to validate 

model input, and (2) incorporating spatially variable 

vertical heterogeneity into the model in the above 

mentioned areas.

44 Construction and Calibration of Numerical Ground-Water-Flow Models of the Western Half of the Milford-Souhegan Glacial-Drift 

Aquifer, Milford, New Hampshire
SELECTED REFERENCES

Camp, Dresser, and McKee, Federal Programs Corporation, 

1995, Final report of vertical contaminant profiling, 

Savage Municipal Supply Well, Superfund site-OUl, 

Milford, New Hampshire: Boston, Mass., Camp, 

Dresser, and McKee, Inc., Federal Programs Corporation, November 1995, 5 chaps., 5 apps.

Camp, Dresser, and McKee, Inc., 1996, Conceptual

remedial design report for OK tool source area, Savage 

Municipal Supply Well, Superfund site-OUl, Milford, 

New Hampshire: Cambridge, Mass., Camp, Dresser, 

and McKee, Inc., March 1996, vol. 1, 5 chaps.

Chapelle, F.H., 1993, Ground-water microbiology and 

geochemistry: John Wiley and Sons, Inc., New York, 

424 p.

Coakley, M.F., Keirstead, Chandlee, Brown, R.O., and 

Hilgendorf, G.S., 1997, Water resources data 

New Hampshire and Vermont water year 1996: 

U.S. Geological Survey Water-Data Report 

NH-VT-96-1, 189 p.

Environmental Science and Engineering, Inc., 1995, Results 

of vertical profiling program Savage Municipal Water 

Supply Superfund Site: Amherst, N.H., Environmental 

Science and Engineering, Inc., 3 chaps.

 1997a, Final results of vertical profiling program 

Savage Municipal Water Supply Superfund Site: 

Amherst, N.H., Environmental Science and 

Engineering, Inc., Feb. 1997, 25 p. 

-1997b, Draft ground-water modeling report Savage

municipal water supply well superfund site, Milford, 

New Hampshire: Nashua, N.H., QST Environmental, 

appendix E.

Harte, P.T., and Willey, R.E., 1997, Effects of historical 

withdrawals on advective transport of contaminated 

ground waters in a glacial-drift aquifer, Milford, New 

Hampshire: U.S. Geological Survey Fact Sheet 162- 

97, 6 p.

Harte, P.T., Flynn, R.H., Kiah, R.G., Severance, Timothy, 

and Coakley, M.F., 1997, Information on hydrologic 

and physical properties of water to assess transient 

hydrology of the Milford-Souhegan glacial-drift 

aquifer, Milford, New Hampshire: U.S. Geological 

Survey Open-File Report 97-414, 96 p.

Harte, P.T., and Mack, T.J., 1992, Geohydrology of, and 

simulation of ground-water flow in the MilfordSouhegan glacial-drift aquifer, Milford, New 

Hampshire: U.S. Geological Survey Water-Resources 

Investigations Report 91-4177, 90 p.

 1996, Effects of model discretization on zones of 

contribution to low pumping-rate wells in a hypothetical river-valley aquifer in hydrology and hydrogeology of urban and urbanizing areas: St. Paul, Minn.,

American Institute of Hydrology, p. GWQB42- 

GWQE56.

HMM Associates, Inc., 1989, Draft remedial investigation, 

Savage well site, Milford, New Hampshire: Concord, 

Mass., no. 2176 HAZ/2880, 218 p.

 1991, Remedial investigation, Savage well site, 

Milford, New Hampshire: Concord, Mass., no. 2176 

HAZ/4814, 800 p.

Johnson, A.I., 1967, Specific yield-computation? of specific 

yields for various materials: U.S. Geological Survey 

Water-Supply Paper 1662-D, 74 p.

Johnston, C.M., and Harte, P.T., 1998, Documentation and 

application example of a simple method to compute the 

maximum slope and direction of hydraulic head: U.S. 

Geological Survey Water-Resources Invest'gations 

Report 98-4021,25 p.

Koteff, Carl, 1970, Surficial geologic map of the Milford 

quadrangle, Hillsborough County, New Hampshire: 

U.S. Geological Survey Geologic Quadrangle Map 

GQ-881, scale 1:62,500.

Lyons, J.B., Bothner, W.A., Moench, R.H., and

Thompson, J.B., 1997, Bedrock geologic map of New 

Hampshire: U.S. Geological Survey State Geologic 

Map, 2 sheets, scale 1:250,000 and 1:500,COO.

Mack, T.J., and Harte, P.T., 1996, Analysis of acuifer tests 

to determine hydrologic and water-quality conditions 

in stratified-drift and riverbed sediments near a former 

municipal well, Milford, New Hampshire: U.S. 

Geological Survey Water-Resources Invest'gations 

Report 96-4019, 77 p.

McDonald, M.G., and Harbaugh, A.W, 1988, A modular 

three-dimensional finite-difference ground-water flow 

model: U.S. Geological Survey Technique" of WaterResources Investigations, chap. Al.

Moore, R.B., 1995, Geohydrologic setting, in Harte, P.T., 

and Johnson, W.P, Geohydrology and water quality of 

stratified-drift aquifers in the Contoocook Piver basin, 

south-central New Hampshire: U.S. Geological 

Survey Water-Resources Investigations Report 

92-4154, p. 10-15.

New Hampshire Department of Environmental Services, 

1985, Hydrogeological investigation of the Savage 

well site, Milford, New Hampshire: New Hampshire 

Water Supply and Pollution Control Division, Report 

145, 91 p.

Olimpio, J.R., and Harte, P.T., 1994, Reassessment of 

geohydrologic data and refinement of a regional 

ground-water flow model of the Milford-Souhegan 

glacial-drift aquifer, Milford, New Hampshire: U.S. 

Geological Survey Water-Resources Investigations 

Report 95-281,40 p.

SELECTED REFERENCES 45
Pollock, D.W., 1994, User's guide for

MODPATH/MODPATH-PLOT, Version 3: A particle 

tracking post-processing package for MODFLOW the 

U.S. Geological Survey finite-difference ground-water 

flow model: U.S. Geological Survey Open-File Report 

94-464, 220 p.

Rasmussen, W.C., and Andreason, G.E., 1959, Hydrologic 

budget of the Beaver Dam Creek basin, Maryland: 

U.S. Geological Survey Water-Supply Paper 1472, 

106 p.

Trescott, PC., and Pinder, G.F., and Larson, S.P., 1976, 

Finite-difference model for aquifer simulation in two

dimensions with results of numerical expe-iments: 

U.S. Geological Survey Techniques of Wa*erResources Investigations, book 7, chap. Cl, 116 p.

U.S. Environmental Protection Agency, 1994a, The

hydrologic evaluation of landfill performance (HELP) 

model; Users Guide for Version 3: Office of Research 

Development, Washington, D.C., Sept. 1994, 81 p.

 1994b, The hydrologic evaluation of landfill performance (HELP) model; Engineering Documentation for 

Version 3: Office of Research Development, 

Washington, D.C., Sept. 1994, 81 p.

46 Construction and Calibration of Numerical Ground-Water-Flow Models of the Western Half of the Milford-Souhegan Glacial-Drift 

Aquifer, Milford, New Hampshire
APPENDIX 1: List and description of model-input files

for the ground-water-flpw models of the MilfordSouhegan glacial-drift aquifer, Milford, New Hampshire
Appendix 1. List and description of model-input files for the ground-water-flow models of the western half of the MilfordSouhegan glacial-drift aquifer, Milford, New Hampshire

[Model input files are for computer-modeling software MODFLOW-88 or MODFLOW-96]

Model run File type File name Description of model input

All steady-state models Input,ascii bas4.10796

Transient, seasonal analysis for Input, ascii bas-48t.oc96 

1994-95

Transient, historical analysis for Input, ascii bas-hist5 

1960-88

All steady-state and transient Input,ascii Iblnoch. 10796 

models

All steady-state and transient 

models

All steady-state and transient 

models

All steady-state and transient 

models

All steady-state and transient 

models

Input,ascii

Input,ascii

Input, ascii

Input,ascii

IbZnoch. 10796

Ib3.797

Ib4.797

Ib5.797

BASIC FILES

Input file for basic package for steady-state model. Contains information on number of model cells and layers, and cond; tions to be simulated.The Milford model simulates 175 rows, 189 columns, and 

5 layers.All model layers can simulate unconfined conditions.

Basic file for transient input to basic package of MOE ^LOW. Total 

simulation is 2.5 years long. Contains 20 stress periods and simulates seasonal variations from April 1994 to June 1995. The period 

of January 1993 to April 1994 is used to insure starting heads are 

appropriate for seasonal analysis.

Basic file for transient input to basic package of MOC^LOW. Total 

simulation is 29 years from 1960 - December 1988. Contains 8 

stress periods and simulates historical changes in pampage.

IBOUND FILES

Contains model cell ibound designation for layer one. Active cells 

where head is calculated are designated with a posi*ive integer, 

specified-head cells are designated with a negative integer and inactive cells that are not simulated are designated with a zero.

Contains model cell ibound designation for layer two.

Contains model cell ibound designation for layer three.

Contains model cell ibound designation for layer four.

Contains model cell ibound designation for layer five.

All steady-state and transient Input,ascii wet 1.10796 

models

All steady-state and transient Input,ascii wet2.10796 

models

All steady-state and transient Input,ascii wet3.797 

models

All steady-state and transient Input,ascii wet4.797 

models

All steady-state and transient Input,ascii wet5.797 

models

REWETTING FILES

Contains model cell designation for layer one rewettin? capabilities. A 

positive integer indicates cell can be rewetting if during iterative 

solution becomes dry. Rewetting option is invoked when calculated 

head is above the thickness criteria set in this array (positive integer) and wetness factor in bcf2 file. The Milford model activates 

rewetting when calculated head is 5 feet above base of cell.

Contains model cell designation for layer two rewettirg capabilities. 

Contains model cell designation for layer three rewetting capabilities. 

Contains model cell designation for layer four rewettng capabilities. 

Contains model cell designation for layer five rewetting capabilities.

48 Construction and Calibration of Numerical Ground-Water-Flow Models of the Western Half of the Milford-Souhegan Glacial-Drift 

Aquifer, Milford, New Hampshire
Appendix 1. List and description of model-input files for the ground-water-flow models of the western half of the MilfordSouhegan glacial-drift aquifer, Milford, New Hampshire-Continued

Model run File type File name Description of model input

All steady-state models Input,ascii bcf. 82696

Transient seasonal models for the Input,ascii bcf-48t.oc96 

period 1994-95

Transient historical model for the Inputascii bcf-hist2 

period 1960-88

All steady-state and transient 

models

All steady-state and transient 

models

All steady-state and transient 

models

All steady-state and transient 

models

All steady-state and transient 

models

All steady-state and transient 

models

All steady-state and transient 

models

All steady-state and transient 

models

All steady-state and transient 

models

All steady-state and transient 

models

All steady-state and transient 

models

All steady-state and transient 

models

All steady-state and transient 

models

All steady-state and transient 

models

Steady-state model for 

1994-95

Transient seasonal for 1994-95

Transient historical model for

Input, ascii

Input,ascii

Input,ascii

Input,ascii

Input,ascii

Input,ascii

Input,ascii

Input,ascii

Input,ascii

Input, ascii

Input,ascii

Input,ascii

Input,ascii

Input,ascii

Input, ascii

Input, ascii

Input ascii

Klokhigh.897

K2.5597

K3.797

K4.797

K5.797

vconlokhigh.897

vcon2.5597

vcon3.797

vcon4.797

botl.ap98

bot2.ap98

bot3.sp98

bot4.sp98

bot5.sp98

recharge.31897

rech-caltt.897

rech-hist5

1960-88

BLOCK-CENTERED FILES

Input file for bcf2 rewetting package for steady-state models. Contains 

information on model grid cell sizes, rewetting options, aquifer 

anisotropy (not invoked), and fortran unit numbers a~?d formatting 

for aquifer hydraulic conductivity, vertical conductance, and model 

layer elevations.

Input file for bcf2 rewetting package for transient seasonal models for 

the period 1994-95. Contains information on model grid cell sizes, 

rewetting options, aquifer anisotropy (not invoked), ?nd fortran unit 

numbers and formatting for aquifer hydraulic conductivity, vertical 

conductance, and model-layer elevations.

Input file for bcf2 rewetting package for transient histo-ical model.

HYDRAULIC CONDUCTIVITY FILES

Hydraulic conductivity array for layer one.

Hydraulic conductivity array for layer two. 

Hydraulic conductivity array for layer three. 

Hydraulic conductivity array for layer four. 

Horizontal hydraulic conductivity array for layer five. 

Vertical hydraulic conductance between layers one and two. 

Vertical hydraulic conductance between layers two and three. 

Vertical hydraulic conductance between layers three and four. 

Vertical hydraulic conductance between layers four and five.

MODEL LAYER SURFACES

Altitude of bottom of model cells in layer one, in feet above sea level. 

Also is used for top of model layer two.

Altitude of bottom of model cells in layer two, in feet above sea level. 

Also is used for top of model layer three.

Altitude of bottom of model cells in layer three, in feet above sea 

level. Also is used for top of model layer four.

Altitude of bottom of model cells in layer four, in feet above sea level. 

Also is used for top of model layer five.

Altitude of bottom of model cells in layer five, in feet above sea level.

STRESS FILES

Contains recharge rates to model cells for steady-state models. Valley 

edge cells receive higher rates than interior cells. Tot?l recharge is 

3.25 ft^s, which is about 26.2 in/yr.

Seasonal transient recharge for 1994-95. 

Historical transient recharge for 1960-88.

APPENDIX 1 49
Appendix 1 . List and description of model-input files for the ground-water-flow models of the western half of the MilfordSouhegan glacial-drift aquifer, Milford, New Hampshire-Continued

Model run File type File name Description of model input

Steady-state 1983 conditions Input,ascii 

Steady-state 1988 conditions Input,ascii

Steady-state 1990 conditions 

Steady-state 1994 conditions 

Steady-state 1996 conditions 

Transient seasonal for 1994-95

Transient historical for 

1960-88

All steady-state files

Input,ascii 

Input,ascii 

Input,ascii

Input, ascii

Input, ascii rivbas. 112097

Transient seasonal model for Input, ascii river-61t.nv97 

1994-95

Transient historical model for Input, ascii rivbas. 112097 

1960-88

All steady-state models

All steady-state and transient 

models

All steady-state models

Transient seasonal model for 

1994-95

Transient historical model for 

1960-88

Steady-state models and seasonal 

transient model

Steady-state models and seasonal 

transient model

Steady-state models and seasonal 

transient model

Steady-state models and seasonal 

transient model

Steady-state models and seasonal 

transient model

Input, ascii ghb.71697

Input,ascii pcg-n!4 

Input,ascii oc

Input, ascii 

Input, ascii 

Input,ascii 

Input,ascii 

Input,ascii 

Input,ascii 

Input,ascii

STRESS FILES-Continued

wel!83.897 Location of ground-water withdrawals and rates for 19^3 conditions 

with Savage well pumping.

wel!88.897 Location of ground-water withdrawals and rates for October 1988, 

ground-water withdrawals.

wel!90.897 Location of ground-water withdrawals and rates for 1990 conditions.

wel!94.5597 Location of ground-water withdrawals and rates for 1994 conditions.

wel!96.55967 Location of ground-water withdrawals and rates for 1996 conditions.

we!194-t.897 Transient seasonal well file.

well-hist5 Transient historical well file.

BOUNDARY CONDITION FILES

Steady-state model of altititude of river stage and rivert ixi, and riverbed conductances for the Souhegan River, Purgatory Brook, 

discharge ditch, Tucker Brook, and Hartshorn Brook.

Transient seasonal river package. 

Transient historical river package.

Contains general-head boundary information including eltitude of 

external head and conductances along column 181 of model.

SOLUTION FILES

Information on iterative solution options for the precon-iitionedconjugate gradient solution. The Milford model uses non-linear 

solution techniques.

Output control options for printing and saving heads and fluxes. The 

Milford model saves heads in ascii and binary form and fluxes in 

binary.

oc-47t Output control for seasonal transient model.

oc-hist5 Output control for historical simulation.

hdl 1 -r94-44.in Input array for starting steady-state heads for model layer 1.

hd!2-r94-44.in Input array for starting steady-state heads for model layer 2.

hdl3-r94-44.in Input array for starting steady-state heads for model layer 3.

hd!4-r94-44.in Input array for starting steady-state heads for model layer 4.

hdl5-r94-44.in Input array for starting steady-state heads for model layer 5.

50 Construction and Calibration of Numerical Ground-Water-Flow Models of the Western Half of the Milford-Souhegan Glacial-Drift 

Aquifer, Milford, New Hampshire
APPENDIX 2: Information on well construction

(sorted by well number) for selected wells in

Milford, New Hampshire
Appendix 2. Information on well construction for selected wells in Milford, New Hampshire

[All units in feet; horizontal datum based on 2,000-foot grid New Hampshire State Plane coordinate system North American Datum 1983; vertical datum based 

on feet above National Geodetic Vertical Datum of 1929; depth in feet below land surface; some wells not shown on plate 1: -, no data: TPVC, top of 

poly vinyl casing (pvc); TSC, top of steel casing; CONC, concrete; TINRSC, top of inner steel casing; TCONC, top of concrete; WELLCVR, well cover, 

BOLT, top of bolt; PWMC, from metal cover; AHPUMP, air line reading at pump; SHELTER, labeled point inside wooden shelter; TOP RRBAR, top of rebar]

Well 

number 

on 

plate 1

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

29

30

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

46

Well name

LW-01D

LW-02D

LW-03D

LW-04D

MOW-33

GW-02D

GW-03D

GW-04D

GW-05D

RFW-1

RFW-2

RFW-3

RFW-4

PA-1

PA-2

PA-3

MI-7

MI-8

MI- 10

MI- 11

MI-12

MI-15

MI- 16

MI- 18

MI- 19

MI-20

MI-20A

MI-21

MI-21 A

MI-22

MI-22A

MI-23

MI-24

MI-24A

MI-25

MI-26

MI-27

MI-28

MI-30

MI-31

MI-32

Easting

984848.90

984490.30

984873.40

985001.00

976961.90

983382.40

984183.60

983753.10

984174.30

980111.60

980419.40

980457.30

980142.70

980332.10

980334.70

980388.40

978642.40

976549.90

979677.40

979580.10

979476.40

976242.80

976813.60

977625.40

974416.40

974416.40

974565.10

974566.70

974696.40

975053.70

974976.60

975053.70

975050.20

975092.10

975089.20

975089.20

975064.80

974962.80

975877.30

975786.40

975247.20

Northing

125391.90

124835.40

124642.50

124601.20

125149.30

127459.90

126015.00

127211.90

127024.90

123484.10

123831.60

124035.20

124069.50

123667.20

123737.30

123703.10

125263.60

125251.50

124853.90

125310.70

125858.70

123624.90

123543.90

123963.10

124870.30

124870.30

124758.40

125043.30

124790.30

125123.50

125182.60

125123.50

124966.30

124891.90

124821.70

124821.70

124731.30

124603.60

124347.00

124591.90

124933.70

Description of 

measurement point

~

-

~

-

~

-

-

~

~

~

~

~

-

-

-

TSC

TINRSC

TPVC

TSC

TSC

TSC

--

TCONC

TSC

TSC

TPVC

TPVC

TPVC

TSC

-

TSC

TPVC

~

TSC

TSC

TPVC

TPVC

TPVC

TPVC

TPVC

Altitude of

Measurement point

245.66

251.14

246.43

-

-

~

~

--

-

253.87

253.51

252.15

-

-

~

256.68

264.93

255.12

254.52

253.26

265.17

-

264.34

277.99

277.99

~

274.95

272.61

272.08

-

272.08

272.63

~

271.41

271.41

272.23

271.85

269.35

267.23

273.57

Land 

surface

264.80

243.10

247.30

243.40

260.00

255.40

252.40

255.60

261.00

255.70

253.80

253.50

251.60

255.10

254.90

255.30

253.20

262.60

252.20

252.10

251.50

264.70

269.10

262.70

275.60

275.60

274.70

272.10

272.50

269.10

270.10

269.10

269.80

272.00

269.30

269.30

269.90

270.30

265.70

266.10

270.20

Top of 

screen or 

opening

100.00

45.00

44.50

40.00

60.00

19.00

28.00

21.50

23.00

8.00

10.00

13.00

6.00

-

-

-

-

~

44.00

40.00

43.00

~

~

-

65.00

10.00

-

15.00

-

99.00

-

10.00

10.00

-

101.80

8.00

13.00

35.00

27.00

36.00

30.00

Depth to

Bottom of 

screen or 

opening

110.00

55.00

54.50

50.00

70.00

29.00

38.00

31.50

33.00

28.00

35.00

43.00

16.00

8.70

8.70

7.80

31.00

-

47.00

56.00

49.00

-

-

-

80.00

40.00

14.80

40.00

-

114.00

11.70

75.00

85.00

14.00

111.00

88.00

78.00

55.00

72.00

54.00

75.00

Refusal Bedrock

1 14.3

62.5

80.2

80

56

34

23.5

19

33

28

35

43

16

._

--

-

-

--

58.5

63

50

..

-

-

63.5

63.5

-

53

-

94

-

94

96

105

105

88

56

75

~

95

52 Construction and Calibration of Numerical Ground-Water-Flow Models of the Western Half of the Milford-Souhega^ Glacial-Drift 

Aquifer, Milford, New Hampshire
Appendix 2. Information on well construction for selected wells in Milford, New Hampshire-Continued

Well 

number 

on 

plate 1

47

48

49

50

51

52

54

55

56

57

58

59

60

61

62

63

64

65

66

67

68

69

70

71

72

73

74

78

79

80

82

83

84

85

86

87

88

89

90

91

92

93

94

Well name

MI-33

MI-34

MI-35

MI-36

MI-37

MI-38

MI-41

MI-42

MI-43

MOW-63

MI-44

MI-45

MI-46

MI-47

MI-48

~

-

P-03

-

-

~

-

-

-

MI-62

MI-64

MOW-35

MOA-4

-

-

-

~

#226inSurvey

FH-15

FH-13OBS

FH-14

FH-16

FH-27

FH-22

FH-24

FH-25

FH-23

FH-21

Easting

975651.30

975833.60

976578.50

974900.80

975299.50

975116.90

977561.60

977567.30

977583.80

975248.20

977514.10

975909.30

975970.80

975825.50

976556.30

973226.90

976086.60

976979.60

975354.00

979957.10

976054.90

976146.70

976282.60

976275.60

977408.80

979161.50

979010.10

978318.20

975782.30

975917.30

982214.80

982062.20

975999.60

976951.60

975717.70

975867.00

977174.80

978957.50

978953.00

979035.90

979102.50

979002.60

978928.60

Northing

124011.30

122797.60

124150.80

123429.20

123330.90

123948.10

124774.20

124958.10

125123.00

125062.10

125199.40

125772.40

125598.00

125094.20

124678.90

124779.40

124426.60

124880.40

124548.90

124233.70

124695.20

124676.00

124669.80

124553.60

125554.80

123887.20

124641.80

124603.50

119504.90

119166.00

125347.60

125393.90

127234.70

126886.40

126524.20

126592.80

126706.30

126176.80

126400.00

126403.90

126406.50

126401.50

126400.60

Description of 

measurement point

WELLCVR

TPVC

PWMC

TPVC

TPVC

-

TPVC

TPVC

TPVC

-

TPVC

-

~

~

CONC

~

-

TSC

-

-

~

-

-

-

~

~

-

-

-

~

~

~

TSC

AHPUMP

TPVC

BOLT

-

TSC

TPVC

TPVC

TPVC

TPVC

TPVC

Altitude of

Measurement point

265.90

278.84

263.20

270.51

272.60

-

260.12

258.51

258.82

-

260.60

-

»

-

-

-

-

263.27

-

-

-

--

-

-

-

-

-

--

~

-

-

-

262.51

265.72

269.03

263.53

262.99

253.41

255.10

253.27

251.63

253.70

251.63

Land 

surface

268.00

278.80

262.20

269.90

270.40

270.00

258.70

257.20

257.30

270.00

259.20

264.90

267.30

270.00

264.10

282.40

265.30

261.30

270.00

250.00

267.90

266.30

264.10

264.00

260.00

259.90

260.00

249.50

350.00

~

240.00

240.90

261.70

265.10

260.00

262.20

261.00

251.30

253.10

251.60

252.10

252.00

252.10

Top of 

screen or 

opening

50.00

--

~

-

-

~

-

~

-

53.00

-

~

~

-

-

-

-

-

~

~

-

-

17.00

~

-

33.00

-

-

-

-

51.00

18.00

33.00

32.00

~

36.00

24.00

24.00

23.00

22.00

21.00

Depth to

Bottom of 

screen or 

opening

60.00

17.70

55.00

12.50

12.50

-

20.00

20.00

20.00

62.00

20.00

-

-

-

-

-

-

-

-

-

-

-

-

-

58.00

-

-

38.00

-

-

~

-

66.00

38.00

43.00

42.00

-

41.00

29.00

29.00

28.00

25.00

26.00

Ref -sal Bedrock

60

..

..

-

-

-

65

-

..

..

..

..

..

-

-

-

60.7

-

59

54

-

23

-

60

 

--

--

-

-

APPENDIX 2 53
Appendix 2. Information on well construction for selected wells in Milford, New Hampshire-Continued

Well 

number 

on 

plate 1

95

96

97

98

99

100

101

102

103

104

105

106

107

108

109

111

117

118

119

120

121

122

123

124

125

127

128

148

149

150

151

152

153

154

155

156

157

158

163

164

165

166

167

_ . Attitude of DescnpWell name

FH85-8A

FH1974

Bl

B3

B4

B6

B8

B9

Bll

B12

--

-

-

--

--

--

-

-

-

--

--

WW-125

GW-01S

GW-01D

GW-01M

HAYWOOD

SavageWell

LW-01M

LW-01S

LW-02S

LW-03S

LW-04S

MOW-38

MOW-32

GW-02S

GW-03S

GW-04S

GW-05S

MI-2

MI-3

MI-4

MI-5

MI-6

Easting

975813.90

978905.30

974473.70

974360.10

974211.60

974327.40

974392.90

974212.30

974370.30

974471.90

972221.40

969943.60

982412.50

969797.70

982510.90

976843.40

977035.00

974663.40

975143.40

974826.10

976507.90

975152.70

982781.10

982862.30

982953.40

981163.80

978473.20

984856.90

984856.90

984495.90

984876.20

985003.80

975574.20

976679.80

983400.80

984191.20

983770.60

984189.90

978827.60

978692.70

978596.40

978717.70

978717.10

. , .. . tion of Northing 

y measure- Measurement point ment point

126532.90

126519.50

125037.50

124970.20

124942.20

125036.10

125051.00

125172.50

125169.70

125190.80

119573.10

115997.70

131350.50

115772.40

130710.20

1 15878.60

115723.00

117151.10

117530.10

117243.00

117660.40

129134.80

127851.50

127876.40

127904.30

124370.30

124848.00

125418.50

125419.50

124860.80 -- 245.91

124673.40 - 250.44

124625.30 ~ 246.46

128320.70

124466.70

127487.90

126042.60

127239.50

127055.10

124764.70 TSC 253.94

124915.00 TSC 257.28

124892.50 TSC 257.49

124920.50 TSC 255.89

124918.60 TSC 255.66

Land 

surface

260.00

254.50

269.90

269.30

270.00

269.00

269.70

275.30

275.00

275.40

-

«

349.20

-

349.30

-

-

~

-

-

-

269.00

256.10

256.50

256.70

256.30

261.00

265.10

265.20

243.40

250.00

244.80

262.70

261.80

255.10

252.40

255.60

264.20

252.90

254.50

255.00

255.20

255.10

Top of 

screen or 

opening

20.00

~

-

~

-

~

-

-

-

~

-

--

-

~

-

--

-

~

~

-

--

--

6.00

60.00

30.00

~

35.00

42.60

25.60

4.00

9.00

5.00

30.00

6.00

6.00

8.40

5.40

7.00

42.00

44.00

39.00

39.00

Depth to

Bottom of 

screen or 

opening

26.00

~

43.00

33.80

54.50

-

26.00

~

-

-

--

-

--

~

--

-

--

-

-

-

-

-

16.00

70.00

40.00

-

45.00

52.60

35.60

14.00

19.00

15.00

40.00

16.00

16.00

18.40

15.40

17.00

47.00

49.00

49.00

49.00

Refusal Bedrock

..

43

33.8

54.5

2':.2

~

--

..

~

-

._

..

-

--

-

--

-

56

-

-

--

-

--

--

41

20

-

-

..

~

..

-

-.

54 Construction and Calibration of Numerical Ground-Water-Flow Models of the Western Half of the Milford-Souhegan Glacial-Drift 

Aquifer, Milford, New Hampshire
Appendix 2. Information on well construction for selected wells in Milford, New Hampshire-Continued

Well 

number 

on 

plate 1

168

169

170

171

172

173

174

175

176

177

178

179

180

188

189

190

191

192

193

194

195

196

197

198

199

200

201

202

203

204

208 

209

210

212

213

214

215

216

217

218

219

220

221

Well name

MI-6A

MI-9

MI- 14

MI-29

MI-40

H12-71

Hll-71

H9-71

H8-71

H6-71

H7-71

H10-71

H5-71

MOA-25

MOA-35

MOA-37

MOA-38

-

MOW- 15

MOW-58

MOW-64

MOW-65

MOW-66

MOW-67

MOW-68

MOW-25

MOW-26

MOW- 19

MI-63

MI-13

FH-5 (pump) 

MW-1C

MW-2B

MW-4B

MW-5B

MW-6B

MW-7B

MW-8B

MW-9C

MW-10C

MW-11R

MW-12A

MW-13B

Easting

978830.10

976255.70

977619.80

975306.90

977391.30

981352.50

981478.20

981665.10

981881.90

981885.60

981841.00

981819.40

981751.40

975839.70

975554.90

975737.60

975295.40

984005.20

977255.80

975647.00

976832.40

976555.40

982904.60

983164.50

983417.40

977668.80

977661.40

976722.50

975636.80

984325.50

975988.30 

974922.80

975151.80

975303.50

975408.30

975521.20

976263.30

976524.90

976503.30

976215.00

976435.00

978133.30

977300.60

Northing

124812.80

125936.00

123760.40

123808.10

124739.20

124815.30

125561.40

126217.40

126202.30

126032.00

125953.90

126331.60

126415.00

125937.00

125804.90

126314.60

125590.60

123305.50

127892.70

125574.50

126380.50

126488.70

124297.20

124318.20

124322.20

122997.30

122551.60

125725.60

125076.60

123765.20

127199.90 

122726.70

125599.90

123583.80

123982.60

124486.80

123908.40

124151.40

124473.60

124930.60

125881.60

124280.70

125081.10

Description of 

measurement point

TCONC

-

TPVC

TPVC

-

-

~

~

-

-

-

~

-

-

-

~

-

-

-

-

--

-

--

-

-

-

-

TSC

-

TINRSC 

TPVC

TSC

TPVC

TPVC

TPVC

TPVC

TPVC

TPVC

TPVC

TSC

TPVC

TPVC

Altitude of

Measurement point

265.05

-

269.93

257.40

-

-

-

-

~

~

-

~

~

-

~

-

-

-

-

-

-

~

~

-

-

-

267.75

251.42

267.89 

281.28

269.19

268.59

269.61

268.95

264.29

263.80

268.09

264.74

263.30

265.96

259.35

Land 

surface

259.50

263.80

260.00

268.50

256.10

250.00

241.60

250.80

250.00

249.50

246.90

250.90

250.50

262.00

265.20

260.00

270.00

266.70

260.00

268.70

260.00

260.00

252.80

249.80

245.00

259.70

260.00

260.80

265.10

249.60

268.00 

279.50

266.40

266.70

267.60

267.10

262.50

261.80

266.30

262.80

261.00

264.00

257.90

Top of 

screen or 

opening

-

-

31.50

-

36.00

25.00

20.00

20.00

16.00

15.00

18.00

23.00

50.00

-

~

~

-

-

54.00

41.00

54.00

27.00

37.00

36.00

-

-

~

24.00

12.00

50.00 

51.10

70.70

45.80

50.40

56.80

45.60

57.00

79.00

81.50

52.00

25.00

48.00

Depth to

Bottom of 

screen or 

opening

-

~

51.50

-

36.00

35.00

25.00

25.00

16.00

15.00

28.00

28.00

60.00

-

-

-

-

-

63.00

49.00

62.00

33.00

43.00

42.00

-

~

-

64.00

18.00

65.00 

61.10

80.70

55.80

60.40

66.80

55.60

67.00

90.00

91.50

64.00

35.00

58.00

Refusal

-

~

51.5

-

~

-

-

~

~

-

-

~

72

12

13

14

-

-

76

76

73

37

45

53

4

14

-

~

33

~

~

~

-

-

--

~

-

-

-

-

Bedrock

-

~

-

-

36

39

28.5

32

16

15

34

31

~

-

-

~

12

-

-

-

-

-

~

~

~

~

-

-

~

62

~

43.2

61.35

69.4

58.6

90

94

91.6

65

-

64

APPENDIX 2 55
Appendix 2. Information on well construction for selected wells in Milford, New Hampshire-Continued

Well 

number 

on 

plate 1

222

223

225

226

228

231

233

234

235

237

240

242

244

245

247

248

249

250

251

252

255

258

262

264

267

268

269

270

271

273

274

275

276

111

278

279

280

281

282

283

284

285

287

Well name

MW-14R

MW-15A

MW-26

MW-25

MW-3

MW-18A

MW-16A

MW-28

MW-27

MW-23A

FH-10(OBS)

FH-9

RW6

RW3

RW1

RW2

Cassarino

SP-1

SP-7

SP-6

MW-24A

MW-17A

MW-29

MW-20A

SP-4

SP-3

P-9A

P-9B

P-15

HP-1

HP-2

HP-3

P-10

P-ll

MW-21A

SPZ-2

P-16

MW-34

P-17A

P-17B

RW4

SPZ-1

RW9

Easting

978696.00

982006.40

975206.20

975168.90

975915.60

975824.80

975671.20

974374.90

974728.20

975835.10

975991.40

975997.30

974672.70

974864.40

975397.40

975425.10

975491.40

976415.40

977551.40

976792.40

977644.90

976216.50

977125.30

977472.90

977995.70

978256.80

978624.20

978624.00

978953.70

978832.70

979099.70

979343.90

979466.80

979689.20

979001.30

979817.20

979986.60

979987.00

980125.10

980124.10

980479.80

980666.60

981114.80

Northing

125647.00

125915.30

123141.40

123046.50

123237.10

124273.40

124863.10

124929.30

125049.90

125944.30

127198.40

127233.10

126362.00

126779.80

127471.00

127514.80

127480.10

128176.90

127255.90

126621.20

126373.30

124754.00

124080.30

124629.10

127200.00

126568.90

126009.90

126015.80

126170.90

125303.40

125374.20

125403.50

125859.00

126100.90

124463.60

126368.50

126500.00

126490.70

126109.10

126110.10

126905.00

126449.90

127599.20

Description of 

measurement point

TSC

TPVC

TPVC

TPVC

TPVC

TPVC

SHELTER

TPVC

TPVC

TPVC

TSC

TSC

--

--

--

--

-

TPVC

TPVC

TPVC

TPVC

TPVC

TPVC

TPVC

~

-

-

-

TPVC

~

-

~

~

-

TPVC

TPVC

TPVC

TPVC

-

~

-

TPVC

Altitude of

Measurement point

255.75

258.53

271.11

273.12

270.54

269.78

270.39

275.42

275.36

267.51

268.01

269.83

-

-

-

-

-

259.17

258.66

261.05

259.67

263.29

260.90

263.23

258.63

256.30

254.73

255.01

252.08

254.51

253.24

253.53

252.70

254.54

261.27

251.94

260.43

260.91

252.54

253.66

280.08

259.17

271.45

Land 

surface

253.80

256.80

268.70

270.50

268.70

267.90

267.50

275.60

273.80

265.40

267.30

268.30

-

-2.00

-2.00

~

267.90

257.40

258.20

260.00

257.10

264.40

261.00

260.80

257.10

255.30

253.10

252.60

251.40

252.30

251.00

251.10

250.40

252.50

259.20

249.90

258.30

258.50

250.60

252.60

278.30

257.40

270.40

Top of 

screen or 

opening

50.00

12.50

3.00

4.00

11.50

44.50

16.90

5.00

5.00

20.00

58.00

-

-

111.00

59.00

-

-

2.00

4.50

3.00

19.50

19.80

2.50

15.20

2.50

4.50

7.00

9.20

7.00

1.00

1.50

1.50

7.50

7.50

3.80

1.00

12.00

9.50

8.00

12.00

-

3.50

__

Depth to

Bottom of 

screen or Refusal Bedrock 

opening

60.00 - 60

27.50

13.00

12.00

21.50 - - 21.5

54.50

26.90

15.00

15.00

30.00

63.00

52.00

..

420.00

340.00

..

12.50

7.00

9.50

8.00

29.50

29.80

12.50

25.20

7.50

9.50

8.00

10.20

8.00

6.00

6.50

6.50

8.50

8.50

13.80

6.00

13.00

19.50 - 20.5

9.00

13.00

23.00

8.50

22.00

56 Construction and Calibration of Numerical Ground-Water-Flow Models of the Western Half of the Milford-Souhegar Glacial-Drift 

Aquifer, Milford, New Hampshire
Appendix 2. Information on well construction for selected wells in Milford, New Hampshire-Continued

Well

number . Well name 

on

plate 1

288 

289 

290

291

292

293

294

295

296

297

299

301

302

304

305

306

307

308

309

310

311

312

313

314

315

316

317

318

319

320

321

322

323

324

326

327

328

329

330

331

332

333

334

FH-28 

FH-29 

SP-18 

SP-11

FH-30

MW-22A

MW-22B

P-13

MW-32A

MW-32B

HM-1

FH-11

FH-19

SP-5

FH-18

MW-33

MW-1A

MW-13A

MW-1B

MW-2A

MW-2R

MW-4A

MW-5A

MW-7A

MW-8A

MW-10A

MW-10B

MW-11A

MW-11B

MW-12B

MW-16B

MW-17B

MW-17C

MW-18B

MW-19A

MW-19B

MW-20B

MW-21B

MW-21C

MW-23B

MW-23C

MW-24B

MW-31

Easting

981031.70 

981063.30 

981032.50 

981256.90

981104.80

981102.30

981098.70

981806.60

981366.60

981369.80

975363.00

975989.90

978898.80

977271.90

978724.80

979070.90

974929.80

977298.80

974926.70

975148.90

975145.00

975307.90

975414.60

976267.60

976511.80

976221.50

976218.50

976433.30

976435.20

978134.30

975671.00

976212.00

976212.80

975824.10

977289.20

977294.80

977476.10

979001.20

979001.50

975802.80

975840.80

977649.70

978979.10

Northing

126543.60 

126519.20 

126481.60 

126375.40

126341.00

126204.00

126201.30

126346.10

125490.00

125487.10

125252.30

127199.80

126408.40

126837.80

126549.20

126468.10

122712.20

125084.80

122718.30

125591.30

125587.70

123586.40

123981.80

123912.60

124151.80

124928.60

124928.40

125888.70

125885.30

124287.40

124868.60

124755.50

124757.90

124279.10

124123.20

124124.80

124622.30

124469.80

124474.00

125947.10

125954.00

126372.30

126191.90

Description of 

measurement point

TSC 

TSC

TSC

TPVC

TPVC

--

TPVC

TPVC

TPVC

TSC

TSC

-

-

TPVC

TPVC

TSC

TPVC

SHELTER

TSC

TPVC

TPVC

TPVC

TPVC

TPVC

TPVC

TPVC

TPVC

TPVC

TPVC

TPVC

TPVC

TPVC

TSC

TSC

TPVC

TPVC

TPVC

TPVC

TPVC

TPVC

TSC

Altitude of

Measurement point

248.85 

250.07 

250.17 

249.67

250.69

252.52

252.77

250.84

250.46

251.23

268.14

268.08

256.17

257.07

255.01

253.89

281.26

259.85

281.38

270.08

267.67

268.34

269.71

264.40

263.91

263.77

263.55

262.78

262.83

265.61

269.85

263.34

263.36

270.30

264.30

263.88

263.03

261.77

261.34

267.40

267.34

259.39

251.87

Land 

surface

248.10 

247.80 

248.20 

247.70

248.30

250.20

250.10

248.30

247.90

248.30

269.20

267.40

~

255.30

~

251.80

279.70

257.90

279.50

266.60

266.20

266.50

267.60

262.30

262.00

262.20

262.20

260.90

261.00

264.00

267.60

264.60

264.70

268.00

261.60

260.90

260.70

259.30

259.40

265.30

265.30

256.80

250.10

Top of 

screen or 

opening

4.50 

8.50

--

13.80

33.50

7.50

7.00

31.80

3.00

-

--

2.50

--

41.50

5.00

23.90

35.40

29.00

134.00

19.70

28.00

3.20

4.50

19.00

44.00

20.50

52.30

56.00

39.60

52.40

85.00

72.00

23.50

39.00

35.00

20.00

44.10

48.00

84.30

31.00

Depth to

Bottom of 

screen or 

opening

23.00 

33.90 

7.50 

9.50

23.00

23.80

43.50

8.50

17.00

41.80

83.00

62.00

--

7.50

-

51.50

17.00

33.90

45.40

39.00

164.00

29.70

38.00

13.20

16.50

29.00

54.00

30.50

64.30

66.00

49.60

62.40

95.00

82.00

33.50

49.00

45.00

30.00

54.10

58.00

94.30

41.00

Refusal Bedrock

--

47

_.

..

43.5

..

52.5

--

..

..

115.5

_.

..

_.

65

66

..

99.3

82

--

30 35

47.5

63.75

106

40.5

50.5

APPENDIX 2 57
Appendix 2. Information on well construction for selected wells in Milford, New Hampshire-Continued

Well 

number 

on 

plate 1

335

336

337

338

339

340

341

342

344

345

347

348

349

351

352

353

354

356

357

358

359

360

361

362

364

366

367

369

374

375

376

377

380

396

397

398

399

400

401

402

403

404

405

Well name

P-l

P-2

WLR4

P-14

SP-9

SP-10

MW-14B

MW-15B

MW-16C

MW-16R

MW-4R

MW-6A

MW-14A

MW-9A

MW-9B

FH-17

PFHprodWell

-

--

--

FH-?

~

P-12

USGS-DISK

--

MW-30

M261942

FHwoods

FH-26

nearFH19

2ftHitchPWl

3ftHitchPWl

HitchWIHs

B95-01

B95-02

B95-03

B95-04

B95-05

B95-06

B95-07

B95-08

B95-09

B95-10

Easting

974088.30

975100.90

978297.60

981843.10

976276.60

975407.80

978696.60

982001.40

975678.10

975670.80

975299.90

975521.40

978695.90

976502.90

976503.60

978711.30

981195.60

981217.30

981218.60

981191.10

981138.80

981136.40

980380.20

978965.10

976295.60

975228.80

973138.90

976854.10

979100.80

978900.70

975620.10

975608.90

975651.60

975177.38

975120.69

974985.31

974848.69

974688.19

974669.00

974914.31

975035.38

975039.81

974816.69

Northing

124847.50

125281.90

125583.70

124952.70

126593.00

126569.50

125651.10

125914.50

124877.10

124875.20

123581.50

124481.80

125654.90

124485.80

124479.10

127671.80

126601.60

126573.60

126572.10

126524.60

126516.30

126667.90

125709.40

126138.80

125521.00

125893.30

124764.60

127069.30

126405.40

126413.00

124005.90

124010.10

124010.80

124917.10

125077.40

125214.80

125108.90

125027.70

124826.00

124802.50

124825.80

124825.60

124997.50

Description of 

measurement point

TPVC

TPVC

SHELTER

--

-

--

TPVC

TPVC

TSC

TSC

TINRSC

TPVC

TPVC

TPVC

TPVC

BOLT

--

-

-

TSC

TSC

TSC

--

--

--

TSC

-

TSC

TPVC

--

--

--

-

--

--

TPVC

~

TPVC

TPVC

TPVC

TPVC

TPVC

TPVC

Altitude of

Measurement point

278.95

271.32

257.38

248.69

261.16

263.92

255.13

258.61

269.70

268.92

267.94

269.11

254.65

267.76

267.87

272.44

251.68

250.05

249.97

250.03

249.86

251.03

252.03

250.02

264.93

267.96

--

266.46

254.35

~

--

--

-

-

272.41

~

275.10

272.12

273.64

276.12

273.34

274.68

Land 

surface

276.60

268.60

251.30

246.70

259.40

262.40

253.30

257.00

267.40

266.50

266.40

267.00

253.40

266.10

266.10

~

249.20

247.40

247.40

247.20

248.50

247.10

252.00

--

262.50

-

--

266.10

--

-

-

-

269.83

269.67

269.65

270.35

273.05

272.75

271.71

270.08

270.31

272.14

Top of 

screen or 

opening

13.90

17.00

4.00

7.00

1.50

1.00

50.00

29.40

73.20

88.00

64.00

8.00

19.00

30.70

58.20

~

30.00

-

-

-

-

-

9.00

--

-

--

-

-

--

-

--

-

--

--

61.50

-

37.00

41.50

46.00

72.00

10.00

61.00

Depth to

Bottom of 

screen or 

opening

14.90

18.00

5.00

8.00

6.50

6.00

60.00

36.40

83.20

138.00

98.00

20.00

29.00

40.70

68.20

--

40.00

--

--

20.50

24.80

34.50

10.00

--

--

--

--

--

-

--

-

--

--

--

--

71.50

-

47.00

51.50

56.00

82.00

20.00

66.00

Refusal Bedrock

--

--

--

..

..

60

27,

87.

87.

45

..

..

--

--

--

..

-

._

_.

_.

--

--

--

-

..

--

..

..

..

107

99.

86

69

.5

.5

.5

.8

73.5

-

58

88

..

58 Construction and Calibration of Numerical Ground-Water-Flow Models of the Western Half of the Milford-Souhegar Glacial-Drift 

Aquifer, Milford, New Hampshire
Appendix 2. Information on well construction for selected wells in Milford, New Hampshire-Continued

Well 

number 

on 

plate 1

406

407

408

409

410

411

Well name

B95-11

B95-12

B95-13

B95-15

B95-16

B95-17

Easting

974969.13

975343.81

975490.63

975254.00

974827.31

974980.38

Northing

124987.00

124724.70

125002.00

125149.40

124995.70

124985.10

Description of 

measurement point

TPVC

TPVC

TPVC

TPVC

TPVC

TPVC

Altitude of

Measurement point

274.58

272.01

266.26

267.90

274.48

274.50

Land 

surface

272.38

269.45

267.01

269.61

272.04

272.07

Top of 

screen or 

opening

73.00

55.00

60.00

85.00

10.00

40.00

Depth to

Bottom of 

screen or 

opening

78.00

60.00

65.00

95.00

20.00

50.00

Refusal Bedrock

80

76

90.5

96.5

...

-

JPPENDIX2 59

APPENDIX 3: Observed ground-water levels for

selected wells in the Milford-Souhegan glacial-drift

aquifer, Milford, New Hampshire
Appendix 3. Observed ground-water levels from selected wells in the Milford-Souhegan Glacial-Drift Aquifer, Milford, 

New Hampshire

[All units in feet; aquifer code: S&G= sand and gravel, over=overburden; water level datum is NGVD 1929; horizontal datum 2000 foot grH New Hampshire 

State Planar coordinates; --, no data available]

Well 

number 

on 

plate 1

21

29

223

280

281

285

288

292

296

31

233

234

235

250

314

315

335

336

348

228

307

220

326

255

297

318

333

349

258

264

351

33

308

310

316

293

309

312

294

341

Well name

MI-7

MI- 18

MW-15A

P-16

MW-34

SPZ-1

FH-28(OBS6)

FH-30

MW-32A

MI-20 (M-lb)

MW-16A

MW-28

MW-27

SP-1 (SP-8)

MW-7A

MW-8A

P-l

P-2

MW-6A

MW-3

MW-1A

MW-12A

MW-19A

MW-24A

MW-32B

MW-11A

MW-24B

MW-14A

MW-17A

MW-20A

MW-9A

MI-21 (M-2)

MW-13A

MW-2A

MW-10A

MW-22A

MW-1B

MW-4A

MW-22B

MW-14B

Easting

978642.4

977625.4

982006.4

979986.6

979987

980666.6

981031.7

981104.8

981366.6

974416.4

975671.2

974374.9

974728.2

976415.4

976267.6

976511.8

974088.3

975100.9

975521.4

975915.6

974929.8

978133.3

977289.2

977644.9

981369.8

976433.3

977649.7

978695.9

976216.5

977472.9

976502.9

974566.7

977298.8

975148.9

976221.5

981102.3

974926.7

975307.9

981098.7

978696.6

Northing

125263.6

123963.1

125915.3

126500

126490.7

126449.9

126543.6

126341

125490

124870.3

124863.1

124929.3

125049.9

128176.9

123912.6

124151.8

124847.5

125281.9

124481.8

123237.1

122712.2

124280.7

124123.2

126373.3

125487.1

125888.7

126372.3

125654.9

124754

124629.1

124485.8

125043.3

125084.8

125591.3

124928.6

126204

122718.3

123586.4

126201.3

125651.1

Model 

row

103

146

103

65

65

72

71

80

115

85

95

82

80

13

137

130

83

74

109

161

169

137

137

52

115

61

52

88

104

118

116

81

99

62

97

85

169

142

85

88

Model 

column

104

79

172

135

135

148

156

156

158

19

44

19

26

72

52

58

13

35

40

43

21

90

73

89

158

63

89

107

54

79

59

21

77

37

55

156

21

32

156

107

Model 

layer

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2,3

3

Aquifer 

code

S&G

S&G

S&G

--

S&G

S&G

S&G

S&G

Sand

S&G

S&G

S&G

S&G

S&G

S&G

S&G

S&G

S&G

S&G

S&G

S&G

Sand

S&G

S&G

Sand

S&G

Till

S&G

S&G

Sand

S&G

S&G

S&G

S&G

S&G

S&G

S&G

S&G

S&G

S&G

Synoptic Synoptic 

water level, water-teve1 

October October 

1988 1990

250.16 251.19

254.32 255.27

249.32

245.53

245.81

243.43

243.6

265.14

258.48

267.14

264.5

252.55

258.38

257.56

268.06

261.42

-

261.14

272.51

253.51

255.9

250.56

243.67

255.99

250.62

..

257.72

254.98

264.53

254.65

260.3

257.57

243.82

272.39

260.77

243.82

248.78

Mean 

biweekly 

water level, 

June 

1994-95

250.77

255.88

242.08

246.31

245.67

244.81

243.39

243.39

242.71

265.84

259.34

266.89

265.25

253.35

259.18

258.29

267.6

261.61

260

261.43

273.62

253.7

256.56

250.93

242.79

255.98

250.95

249.18

258.53

255.13

257.91

265.35

254.74

260.06

258.43

243.53

271.62

261.63

243.5

249.42

62 Construction and Calibration of Numerical Ground-Water-Flow Models of the Western Half of the Milford-Souhegar Glacial-Drift 

Aquifer, Milford, New Hampshire
Appendix 3. Observed ground-water levels from selected wells in the Milford-Souhegan Glacial-Drift Aquifer, Milford, 

New Hampshire-Continued

Well 

number 

on 

plate 1

43

209

23

89

306

320

25

165

203

215

221

240

317

319

321

322

328

38

42

46

86

299

210

216

352

214

344

217

218

323

Well name

MI-28 (H-l)

MW-1C

MI- 10

FH-27

MW-33

MW-12B

MI- 12

MI-4

MI-63

MW-7B

MW-13B

FH-IO(OBS)

MW-10B

MW-11B

MW-16B

MW-17B

MW-20B

MI-24 (M-4)

MI-27 (M-6)

MI-32

FH-13OBS

HM-1

MW-2B

MW-8B

MW-9B

MW-6B

MW-16C

MW-9C

MW-10C

MW-17C

Easting

974962.8

974922.8

979677.4

978957.5

979070.9

978134.3

979476.4

978596.4

975636.8

976263.3

977300.6

975991.4

976218.5

976435.2

975671

976212

977476.1

975050.2

975064.8

975247.2

975717.7

975363

975151.8

976524.9

976503.6

975521.2

975678.1

976503.3

976215

976212.8

Northing

124603.6

122726.7

124853.9

126176.8

126468.1

124287.4

125858.7

124892.5

125076.6

123908.4

125081.1

127198.4

124928.4

125885.3

124868.6

124755.5

124622.3

124966.3

124731.3

124933.7

126524.2

125252.3

125599.9

124151.4

124479.1

124486.8

124877.1

124473.6

124930.6

124757.9

Model 

row

100

169

127

69

59

137

86

117

86

137

99

28

97

61

95

104

119

86

96

88

40

76

62

130

117

109

95

117

97

103

Model 

column

29

21

123

114

117

90

123

102

44

52

77

59

55

63

44

54

79

32

32

38

51

39

37

58

59

40

44

59

55

54

Model 

layer

3

3

3

3

3

3

3

3

3

3

3

3

3

3

3

3

3

3

3

3

3

3

4

4

4

4

4

5

5

5

Aquifer 

code

S&G

S&G

S&G

S&G

S&G

Sand

S&G

Sand

Over

S&G

Sand

S&G

S&G

S&G

S&G

S&G

S&G

Over

Over

S&G

S&G

Over

S&G

S&G

S&G

S&G

S&G

S&G

S&G

S&G

Synoptic 

water level, 

October 

1988

260.56

--

-

-

-

-

-

-

-

257.16

-

-

-

-

--

-

--

259.86

259.98

259.16

-

~

-

255.25

-

257.24

--

255.9

-

Synoptic 

water-level, 

October 

1990

260.91

267.95

248.66

245.9

246.54

253.61

247.46

251.99

-

258.34

254.67

240.76

257.55

255.83

258.57

257.82

255.01

--

-

259.94

249.88

-

260.06

257.53

-

259.01

258.67

257.4

257.69

Mean 

biweekly 

water level, 

June 

1994-95

262.24

268.46

248.9

247.64

247.37

253.7

247.5

251.98

260.38

259.27

254.79

244.64

258.4

255.87

259.46

258.53

255.11

261.33

261.57

260.%

252.65

260

260.54

258.13

257.92

259.82

259.5

257.78

258.01

258.46

APPENDIX 3 63

APPENDIX 4: Information on well construction

(sorted by easting location) for selected wells in

Milford, New Hampshire
Appendix 4. Information on well construction (sorted by easting location) for selected wells in Milford, New Hampshire

[Some wells are not shown on plate; all units in feet; horizontal datum based on 2,000-foot grid New Hampshire State Plane coordinate system North American 

Datum 1983; vertical datum based on feet above National Geodetic Vertical Datum of 1929; depth in feet below land surface; -, no data; T'VC, top of poly vinyl casing (pvc); TSC, top of steel casing; CONC, concrete; TINRSC, top of inner steel casing; TCONC, top of concrete; WELLCVR, well cover; BOLT, top of 

bolt; PWMC, from metal cover; AHPUMP, air line reading at pump; SHELTER, labeled point inside wooden shelter; TOP REBAR, top of rebar]

Well 

number 

on 

plate 1

108

106

105

367

63

391

335

99

102

100

98

103

234

101

31

30

104

97

32

33

118

401

244

400

34

235

405

120

410

399

245

50

402

209

309

307

43

406

36

411

Well name

-

~

M261942

-

WLR-1

P-l

B4

B9

B6

B3

Bll

MW-28

B8

MI-20

MI-19

B12

Bl

MI-20A

MI-21

-

B95-06

RW6

B95-05

MI-21 A

MW-27

B95-10

~

B95-16

B95-04

RW3

MI- 36

B95-07

MW-1C

MW-1B

MW-1A

MI-28

B95-11

MI-22A

B95-17

Easting

969797.70

969943.60

972221.40

973138.90

973226.90

973834.40

974088.30

974211.60

974212.30

974327.40

974360.10

974370.30

974374.90

974392.90

974416.40

974416.40

974471.90

974473.70

974565.10

974566.70

974663.40

974669.00

974672.70

974688.19

974696.40

974728.20

974816.69

974826.10

974827.31

974848.69

974864.40

974900.80

974914.31

974922.80

974926.70

974929.80

974962.80

974969.13

974976.60

974980.38

Northing

115772.40

115997.70

119573.10

124764.60

124779.40

124843.10

124847.50

124942.20

125172.50

125036.10

124970.20

125169.70

124929.30

125051.00

124870.30

124870.30

125190.80

125037.50

124758.40

125043.30

117151.10

124826.00

126362.00

125027.70

124790.30

125049.90

124997.50

117243.00

124995.70

125108.90

126779.80

123429.20

124802.50

122726.70

122718.30

122712.20

124603.60

124987.00

125182.60

124985.10

Description 

of measurement point

-

-

~

~

SHELTER

TPVC

--

-

~

-

~

TPVC

~

TSC

TSC

--

--

TPVC

TPVC

--

TPVC

--

TPVC

TPVC

TPVC

TPVC

-

TPVC

-

-

TPVC

TPVC

TPVC

TPVC

TPVC

TPVC

TPVC

~

TPVC

Altitude of

Measurement point

-

-

-

~

282.80

278.95

-

-

-

-

-

275.42

-

277.99

277.99

-

~

-

274.95

-

272.12

-

275.10

272.61

275.36

274.68

-

274.48

-

-

-

-

281.28

281.38

281.26

271.85

274.58

~

274.50

Land 

surface

-

-

-

-

282.40

-

276.60

270.00

275.30

269.00

269.30

275.00

275.60

269.70

275.60

275.60

275.40

269.90

274.70

272.10

-

272.75

-

273.05

272.50

273.80

272.14

-

272.04

270.35

-2.00

269.90

271.71

279.50

279.50

279.70

270.30

272.38

270.10

272.07

Top of 

screen or 

opening

-

-

-

~

~

13.90

-

-

~

~

--

5.00

-

10.00

65.00

-

~

-

15.00

~

41.50

~

37.00

-

5.00

61.00

-

10.00

-

111.00

-

46.00

51.10

35.40

5.00

35.00

73.00

-

40.00

Depth to

Bottom of 

screen or Refusal Bedrock 

opening

_.

..

..

~

14.90

54.50 54.5

26.2

33.80 33.8

~

15.00

26.00

40.00 -- 63.5

80.00 - 63.5

._

43.00 43

14.80

40.00 - 53

51.50

47.00 - 73.5

15.00

66.00

20.00

69

420.00

12.50

56.00 - 58

61.10 -- 62

45.40

17.00

55.00 56

78.00 - 80

11.70

50.00

66 Construction and Calibration of Numerical Ground-Water-Flow Models of the Western Half of the Milford-Souhegar Glacial-Drift 

Aquifer, Milford, New Hampshire
Appendix 4. Information on well construction (sorted by easting location) for selected wells in Milford, New Harmshire 

--Continued

Well 

number 

on 

plate 1

398

403

404

38

35

37

42

41

40

39

336

52

397

119

311

310

210

122

226

396

225

366

46

57

409

191

51

347

212

171

312

407

66

299

247

340

213

313

248

408

249

214

348

Well name

B95-03

B95-08

B95-09

MI-24

MI-22

MI-23

MI-27

MI-26

MI-25

MI-24A

P-2

MI-38

B95-02

-

MW-2R

MW-2A

MW-2B

WW-125

MW-25

B95-01

MW-26

MW-30

MI-32

MOW-63

B95-15

MOA-38

MI-37

MW-4R

MW-4B

MI-29

MW-4A

B95-12

~

HM-1

RW1

SP-10

MW-5B

MW-5A

RW2

B95-13

Cassarino

MW-6B

MW-6A

Easting

974985.31

975035.38

975039.81

975050.20

975053.70

975053.70

975064.80

975089.20

975089.20

975092.10

975100.90

975116.90

975120.69

975143.40

975145.00

975148.90

975151.80

975152.70

975168.90

975177.38

975206.20

975228.80

975247.20

975248.20

975254.00

975295.40

975299.50

975299.90

975303.50

975306.90

975307.90

975343.81

975354.00

975363.00

975397.40

975407.80

975408.30

975414.60

975425.10

975490.63

975491.40

975521.20

975521.40

Northing

125214.80

124825.80

124825.60

124966.30

125123.50

125123.50

124731.30

124821.70

124821.70

124891.90

125281.90

123948.10

125077.40

117530.10

125587.70

125591.30

125599.90

129134.80

123046.50

124917.10

123141.40

125893.30

124933.70

125062.10

125149.40

125590.60

123330.90

123581.50

123583.80

123808.10

123586.40

124724.70

124548.90

125252.30

127471.00

126569.50

123982.60

123981.80

127514.80

125002.00

127480.10

124486.80

124481.80

Description 

of measurement point

TPVC

TPVC

TPVC

TPVC

TSC

TSC

TPVC

TSC

TSC

-

TPVC

~

-

-

TSC

SHELTER

TSC

~

-

-

-

TSC

TPVC

-

TPVC

-

TPVC

TINRSC

TPVC

TPVC

TPVC

TPVC

-

TPVC

~

-

TPVC

TPVC

-

TPVC

-

TPVC

TPVC

Altitude of

Measurement point

272.41

276.12

273.34

272.63

272.08

272.08

272.23

271.41

271.41

-

271.32

~

~

-

267.67

270.08

269.19

-

273.12

-

271.11

267.96

273.57

-

267.90

~

272.60

267.94

268.59

269.93

268.34

272.01

-

268.14

~

263.92

269.61

269.71

-

266.26

~

268.95

269.11

Land 

surface

269.65

270.08

270.31

269.80

269.10

269.10

269.90

269.30

269.30

272.00

268.60

270.00

269.67

266.20

266.60

266.40

269.00

270.50

269.83

268.70

-

270.20

270.00

269.61

270.00

270.40

266.40

266.70

268.50

266.50

269.45

270.00

269.20

-2.00

262.40

267.60

267.60

--

267.01

267.90

267.10

267.00

Top of 

screen or 

opening

61.50

72.00

10.00

10.00

99.00

10.00

13.00

8.00

101.80

-

17.00

-

134.00

29.00

70.70

-

4.00

~

3.00

-

30.00

53.00

85.00

~

~

64.00

45.80

31.50

19.70

55.00

-

3.00

59.00

1.00

50.40

28.00

~

60.00

-

56.80

8.00

Depth to

Bottom of 

screen or 

opening

71.50

82.00

20.00

85.00

114.00

75.00

78.00

88.00

111.00

14.00

18.00

-

-

164.00

39.00

80.70

-

12.00

-

13.00

-

75.00

62.00

95.00

-

12.50

98.00

55.80

51.50

29.70

60.00

~

83.00

340.00

6.00

60.40

38.00

-

65.00

12.50

66.80

20.00

Refusal Bedrock

86

88

._

96

94

94

88

105

105

..

..

99.8

_.

115.5

..

107

95

65

96.5

14

45

43.2

51.5

..

76

..

61.35

_.

..

90.5

_.

69.4

APPENDIX 4 67
Appendix 4. Information on well construction (sorted by easting location) for selected wells in Milford, New Hampshire 

--Continued

Well 

number 

on 

plate 1

189

153

377

376

203

194

47

380

345

321

233

344

86

190

79

45

331

381

382

95

324

231

61

48

237

188

332

87

44

59

228

80

60

208 

301

240

242

84

68

64

69

322

323

Well name

MOA-35

MOW-38

3ftHitchPWl

2ftHitchPWl

MI-63

MOW-58

MI-33

HitchWIHs

MW-16R

MW-16B

MW-16A

MW-16C

FH-13OBS

MOA-37

-

MI-31

MW-23B

MW23-SG1

MW23-SG2

FH85-8A

MW-18B

MW-18A

MI-47

MI-34

MW-23A

MOA-25

MW-23C

FH-14

MI-30

MI-45

MW-3

-

MI-46

FH-5 (pump) 

FH-11

FH-10(OBS)

FH-9

#226inSurv

-

-

~

MW-17B

MW-17C

Easting

975554.90

975574.20

975608.90

975620.10

975636.80

975647.00

975651.30

975651.60

975670.80

975671.00

975671.20

975678.10

91 '5711. 70

975737.60

975782.30

975786.40

975802.80

975803.80

975805.70

975813.90

975824.10

975824.80

975825.50

975833.60

975835.10

975839.70

975840.80

975867.00

975877.30

975909.30

975915.60

975917.30

975970.80

975988.30 

975989.90

975991.40

975997.30

975999.60

976054.90

976086.60

976146.70

976212.00

976212.80

Northing

125804.90

128320.70

124010.10

124005.90

125076.60

125574.50

124011.30

124010.80

124875.20

124868.60

124863.10

124877.10

126524.20

126314.60

119504.90

124591.90

125947.10

125915.30

125912.70

126532.90

124279.10

124273.40

125094.20

122797.60

125944.30

125937.00

125954.00

126592.80

124347.00

125772.40

123237.10

119166.00

125598.00

127199.90 

127199.80

127198.40

127233.10

127234.70

124695.20

124426.60

124676.00

124755.50

124757.90

Description - 

of measurement point

~

~

-

TSC

-

WELLCVR

-

TSC

TPVC

SHELTER

TSC

TPVC

-

-

TPVC

TPVC

SG1

SG2

~

TPVC

TPVC

~

TPVC

TPVC

-

TPVC

BOLT

TPVC

-

TPVC

-

~

TINRSC 

TSC

TSC

TSC

TSC

-

~

~

TPVC

TPVC

Altitude of

Measurement point

-

-

-

267.75

-

265.90

-

268.92

269.85

270.39

269.70

269.03

~

-

267.23

267.40

257.74

257.74

--

270.30

269.78

~

278.84

267.51

~

267.34

263.53

269.35

~

270.54

-

-

267.89 

268.08

268.01

269.83

262.51

--

-

-

263.34

263.36

Land 

surface

265.20

262.70

-

-

265.10

268.70

268.00

-

266.50

267.60

267.50

267.40

260.00

260.00

350.00

266.10

265.30

-

~

260.00

268.00

267.90

270.00

278.80

265.40

262.00

265.30

262.20

265.70

264.90

268.70

-

267.30

268.00 

267.40

267.30

268.30

261.70

267.90

265.30

266.30

264.60

264.70

Top of 

screen or 

opening

-

30.00

-

--

24.00

54.00

50.00

-

88.00

39.60

16.90

73.20

33.00

-

~

36.00

48.00

-

-

20.00

72.00

44.50

~

~

20.00

50.00

84.30

32.00

27.00

~

11.50

~

-

50.00

58.00

~

51.00

~

-

~

52.40

85.00

Depth to

Bottom of 

screen or 

opening

~

40.00

-

--

64.00

63.00

60.00

-

138.00

49.60

26.90

83.20

43.00

-

-

54.00

58.00

-

~

26.00

82.00

54.50

~

17.70

30.00

60.00

94.30

42.00

72.00

~

21.50

-

-

65.00 

62.00

63.00

52.00

66.00

-

~

-

62.40

95.00

Refusal Bedrock

12

41

-

..

76

60

~

87.

-

..

.5

87.5

-

13

-

..

-

..

82

-

-

-

72

106

75

..

21.

..

--

~

--

--

60

-

..

99.

.5

.3

68 Construction and Calibration of Numerical Ground-Water-Flow Models of the Western Half of the Milford-Souhegai Glacial-Drift 

Aquifer, Milford, New Hampshire
Appendix 4. Information on well construction (sorted by easting location) for selected wells in Milford, New Hampshire 

-Continued

Well 

number 

on 

plate 1

218

258

317

316

26

169

215

314

71

339

70

364

250

318

219

319

351

217

352

121

315

216

22

196

62

49

154

202

252

27

195

111

369

85

9

65

117

262

88

193

304

326

327

Well name

MW-10C

MW-17A

MW-10B

MW-10A

MI- 15

MI-9

MW-7B

MW-7A

-

SP-9

-

-

SP-1

MW-11A

MW-11R

MW-11B

MW-9A

MW-9C

MW-9B

-

MW-8A

MW-8B

MI-8

MOW-65

MI-48

MI-35

MOW-32

MOW- 19

SP-6

MI- 16

MOW-64

~

FHwoods

FH-15

MOW-33

P-03

-

MW-29

FH-16

MOW- 15

SP-5

MW-19A

MW-19B

Easting

976215.00

976216.50

976218.50

976221.50

976242.80

976255.70

976263.30

976267.60

976275.60

976276.60

976282.60

976295.60

976415.40

976433.30

976435.00

976435.20

976502.90

976503.30

976503.60

976507.90

976511.80

976524.90

976549.90

976555.40

976556.30

976578.50

976679.80

976722.50

976792.40

976813.60

976832.40

976843.40

976854.10

976951.60

976961.90

976979.60

977035.00

977125.30

977174.80

977255.80

977271.90

977289.20

977294.80

Northing

124930.60

124754.00

124928.40

124928.60

123624.90

125936.00

123908.40

123912.60

124553.60

126593.00

124669.80

125521.00

128176.90

125888.70

125881.60

125885.30

124485.80

124473.60

124479.10

117660.40

124151.80

124151.40

125251.50

126488.70

124678.90

124150.80

124466.70

125725.60

126621.20

123543.90

126380.50

115878.60

127069.30

126886.40

125149.30

124880.40

115723.00

124080.30

126706.30

127892.70

126837.80

124123.20

124124.80

Description 

of measurement point

TPVC

TPVC

TPVC

TPVC

TSC

TCONC

TPVC

TPVC

-

-

--

~

TPVC

TPVC

TSC

TPVC

TPVC

TPVC

TPVC

-

TPVC

TPVC

TINRSC

~

CONC

PWMC

-

-

TPVC

~

~

-

TSC

AHPUMP

-

TSC

-

TPVC

-

-

--

TSC

TSC

Altitude of

Measurement point

264.74

263.29

263.55

263.77

265.17

265.05

264.29

264.40

-

261.16

264.93

259.17

262.78

263.30

262.83

267.76

268.09

267.87

263.91

263.80

264.93

-

~

263.20

-

-

261.05

-

~

266.46

265.72

-

263.27

~

260.90

262.99

~

257.07

264.30

263.88

Land 

surface

262.80

264.40

262.20

262.20

264.70

263.80

262.50

262.30

264.00

259.40

264.10

262.50

257.40

260.90

261.00

261.00

266.10

266.30

266.10

-

262.00

261.80

262.60

260.00

264.10

262.20

261.80

260.80

260.00

269.10

260.00

-

266.10

265.10

260.00

261.30

-

261.00

261.00

260.00

255.30

261.60

260.90

Top of 

screen or 

opening

81.50

19.80

44.00

19.00

-

~

45.60

3.20

~

1.50

-

~

2.00

20.50

52.00

52.30

30.70

79.00

58.20

-

4.50

57.00

-

54.00

-

~

6.00

-

3.00

41.00

~

~

18.00

60.00

-

-

2.50

-

-

2.50

23.50

39.00

Depth to

Bottom of 

screen or 

opening

91.50

29.80

54.00

29.00

-

-

55.60

13.20

-

6.50

~

-

7.00

30.50

64.00

64.30

40.70

90.00

68.20

-

16.50

67.00

-

62.00

~

55.00

16.00

-

8.00

-

49.00

~

~

38.00

70.00

~

--

12.50

-

--

7.50

33.50

49.00

Refusal Bedrock

91.6

__

..

..

..

58.6

..

--

65

65

94

..

90

-

73

20

-

..

76

..

56

..

-

-

-

..

..

30 35

APPENDIX 4 69
Appendix 4. Information on well construction (sorted by easting location) for selected wells in Milford, New Hampshire 

-Continued

Well 

number 

on 

plate 1

308

221

172

72

264

328

58

251

54

55

56

370

29

255

333

201

200

267

220

320

268

337

78

368

128

165

270

269

21

164

349

222

341

353

167

166

305

163

168

273

302

375

96

Well name

MW-13A

MW-13B

MI-40

MI-62

MW-20A

MW-20B

MI-44

SP-7

MI-41

MI-42

MI-43

MI-14

MI-18

MW-24A

MW-24B

MOW-26

MOW-25

SP-4

MW-12A

MW-12B

SP-3

WLR4

MOA-4

BMc821934

SavageWell

MI-4

P-9B

P-9A

MI-7

MI-3

MW-14A

MW-14R

MW-14B

FH-17

MI-6

MI-5

FH-18

MI-2

MI-6A

HP-1

FH-19

nearFH19

FH1974

Easting

977298.80

977300.60

977391.30

977408.80

977472.90

977476.10

977514.10

977551.40

977561.60

977567.30

977583.80

977619.80

977625.40

977644.90

977649.70

977661.40

977668.80

977995.70

978133.30

978134.30

978256.80

978297.60

978318.20

978403.90

978473.20

978596.40

978624.00

978624.20

978642.40

978692.70

978695.90

978696.00

978696.60

978711.30

978717.10

978717.70

978724.80

978827.60

978830.10

978832.70

978898.80

978900.70

978905.30

Northing

125084.80

125081.10

124739.20

125554.80

124629.10

124622.30

125199.40

127255.90

124774.20

124958.10

125123.00

123760.40

123963.10

126373.30

126372.30

122551.60

122997.30

127200.00

124280.70

124287.40

126568.90

125583.70

124603.50

123964.90

124848.00

124892.50

126015.80

126009.90

125263.60

124915.00

125654.90

125647.00

125651.10

127671.80

124918.60

124920.50

126549.20

124764.70

124812.80

125303.40

126408.40

126413.00

126519.50

Description - 

of measurement point

TSC

TPVC

TPVC

~

TPVC

TPVC

TPVC

TPVC

TPVC

TPVC

TPVC

~

TCONC

TPVC

TPVC

-

~

-

TPVC

TPVC

~

SHELTER

-

-

-

TSC

-

~

TSC

TSC

TPVC

TSC

TPVC

BOLT

TSC

TSC

-

TSC

-

--

TSC

-

Altitude of

Measurement point

259.85

259.35

257.40

-

263.23

263.03

260.60

258.66

260.12

258.51

258.82

~

264.34

259.67

259.39

-

~

258.63

265.96

265.61

256.30

257.38

-

-

-

257.49

255.01

254.73

256.68

257.28

254.65

255.75

255.13

272.44

255.66

255.89

255.01

253.94

--

254.51

256.17

-

Land 

surface

257.90

257.90

256.30

260.00

260.80

260.70

259.20

258.20

258.70

257.20

257.30

260.00

262.70

257.10

256.80

260.00

259.70

257.10

264.00

264.00

255.30

251.30

249.50

-

261.00

255.00

252.60

253.10

253.20

254.50

253.40

253.80

253.30

-

255.10

255.20

-

252.90

259.50

252.30

-

254.50

Top of 

screen or 

opening

23.90

48.00

~

17.00

15.20

35.00

-

4.50

-

-

-

-

-

19.50

31.00

-

~

2.50

25.00

56.00

4.50

4.00

33.00

~

35.00

39.00

9.20

7.00

-

44.00

19.00

50.00

50.00

-

-

39.00

~

42.00

~

1.00

~

~

Depth to

Bottom of 

screen or 

opening

33.90

58.00

~

58.00

25.20

45.00

20.00

9.50

20.00

20.00

20.00

-

--

29.50

41.00

~

-

7.50

35.00

66.00

9.50

5.00

38.00

~

45.00

49.00

10.20

8.00

31.00

49.00

29.00

60.00

60.00

~

-

49.00

-

47.00

-

6.00

-

-

Refusal Bedrock

._

64

_

60.7

-

47.5

..

..

..

-

-

._

40.5

14

4

--

66

..

54

--

..

-

--

-

60

60

-

..

..

--

-

70 Construction and Calibration of Numerical Ground-Water-Flow Models of the Western Half of the Milford-Souhegan Glacial-Drift 

Aquifer, Milford, New Hampshire
Appendix 4. Information on well construction (sorted by easting location) for selected wells in Milford, New Hampshire 

-Continued

Well 

number 

on 

plate 1

94

90

271

89

379

362

378

334

329

278

330

93

74

91

306

274

374

92

73

275

276

25

24

23

277

279

67

280

281

14

283

282

17

18

19

361

20

15

16

284

393

285

288

Well name

FH-21

FH-22

P-15

FH-27

FH27-SG2

USGS-DISK

FH27-SG1

MW-31

MW-21B

MW-21A

MW-21C

FH-23

MOW-35

FH-24

MW-33

HP-2

FH-26

FH-25

MI-64

HP-3

P-10

MI- 12

MI- 11

MI- 10

P-ll

SPZ-2

~

P-16

MW-34

RFW-1

P-17B

P-17A

RFW-4

PA-1

PA-2

P-12

PA-3

RFW-2

RFW-3

RW4

WLR-5

SPZ-1

FH-28

Easting

978928.60

978953.00

978953.70

978957.50

978965.00

978965.10

978965.10

978979.10

979001.20

979001.30

979001.50

979002.60

979010.10

979035.90

979070.90

979099.70

979100.80

979102.50

979161.50

979343.90

979466.80

979476.40

979580.10

979677.40

979689.20

979817.20

979957.10

979986.60

979987.00

980111.60

980124.10

980125.10

980142.70

980332.10

980334.70

980380.20

980388.40

980419.40

980457.30

980479.80

980644.90

980666.60

981031.70

Northing

126400.60

126400.00

126170.90

126176.80

126143.60

126138.80

126137.30

126191.90

124469.80

124463.60

124474.00

126401.50

124641.80

126403.90

126468.10

125374.20

126405.40

126406.50

123887.20

125403.50

125859.00

125858.70

125310.70

124853.90

126100.90

126368.50

124233.70

126500.00

126490.70

123484.10

126110.10

126109.10

124069.50

123667.20

123737.30

125709.40

123703.10

123831.60

124035.20

126905.00

126283.60

126449.90

126543.60

Description - 

of measurement point

TPVC

TPVC

TPVC

TSC

SG2

-

SG1

TSC

TPVC

TPVC

TPVC

TPVC

-

TPVC

TPVC

-

TPVC

TPVC

-

-

-

TSC

TSC

TPVC

-

TPVC

-

TPVC

TPVC

~

~

-

-

-

~

-

-

-

-

-

SHELTER

TPVC

TSC

Altitude of

Measurement point

251.63

255.10

252.08

253.41

245.48

250.02

245.48

251.87

261.77

261.27

261.34

253.70

-

253.27

253.89

253.24

254.35

251.63

-

253.53

252.70

253.26

254.52

255.12

254.54

251.94

~

260.43

260.91

-

253.66

252.54

252.15

-

-

252.03

-

253.87

253.51

280.08

254.27

259.17

248.85

Land 

surface

252.10

253.10

251.40

251.30

-

~

~

250.10

259.30

259.20

259.40

252.00

260.00

251.60

251.80

251.00

~

252.10

259.90

251.10

250.40

251.50

252.10

252.20

252.50

249.90

250.00

258.30

258.50

255.70

252.60

250.60

251.60

255.10

254.90

252.00

255.30

253.80

253.50

278.30

-

257.40

248.10

Top of 

screen or 

opening

21.00

24.00

7.00

36.00

-

-

-

-

20.00

3.80

44.10

22.00

-

24.00

41.50

1.50

-

23.00

-

1.50

7.50

43.00

40.00

44.00

7.50

1.00

-

12.00

9.50

8.00

12.00

8.00

6.00

-

-

9.00

~

10.00

13.00

-

-

3.50

Depth to

Bottom of 

screen or 

opening

26.00

29.00

8.00

41.00

--

-

--

-

30.00

13.80

54.10

25.00

-

29.00

51.50

6.50

-

28.00

--

6.50

8.50

49.00

56.00

47.00

8.50

6.00

-

13.00

19.50

28.00

13.00

9.00

16.00

8.70

8.70

10.00

7.80

35.00

43.00

23.00

-

8.50

23.00

Refusal Bedrock

-

-

..

-

50.5

~

..

63.75

..

59

..

52.5

..

_.

-

_.

..

-

50

63

58.5

..

..

-

20.5

28

-

16

-

-

--

-

35

43

..

--

APPENDIX 4 71
Appendix 4. Information on well construction (sorted by easting location) for selected wells in Milford, New Hampshire 

--Continued

Well 

number 

on 

plate 1

290

289

294

293

292

287

360

359

127

358

354

356

357

291

173

296

297

174

175

180

295

179

178

338

176

177

342

223

83

82

107

109

123

124

197

125

198

10

155

199

12

157

192

Altitude of

rtaetrintinn

Well name

SP-18

FH-29

MW-22B

MW-22A

FH-30

RW9

-

FH-?

HAYWOOD

--

PFHprodWell

-

--

SP-11

H12-71

MW-32A

MW-32B

HI 1-71

H9-71

H5-71

P-13

H10-71

H7-71

P-14

H8-71

H6-71

MW-15B

MW-15A

--

--

-

-

GW-01S

GW-01D

MOW-66

GW-01M

MOW-67

GW-02D

GW-02S

MOW-68

GW-04D

GW-04S

Easting

981032.50

981063.30

981098.70

981102.30

981104.80

981114.80

981136.40

981138.80

981163.80

981191.10

981195.60

981217.30

981218.60

981256.90

981352.50

981366.60

981369.80

981478.20

981665.10

981751.40

981806.60

981819.40

981841.00

981843.10

981881.90

981885.60

982001.40

982006.40

982062.20

982214.80

982412.50

982510.90

982781.10

982862.30

982904.60

982953.40

983164.50

983382.40

983400.80

983417.40

983753.10

983770.60

984005.20

Northing

126481.60

126519.20

126201.30

126204.00

126341.00

127599.20

126667.90

126516.30

124370.30

126524.60

126601.60

126573.60

126572.10

126375.40

124815.30

125490.00

125487.10

125561.40

126217.40

126415.00

126346.10

126331.60

125953.90

124952.70

126202.30

126032.00

125914.50

125915.30

125393.90

125347.60

131350.50

130710.20

127851.50

127876.40

124297.20

127904.30

124318.20

127459.90

127487.90

124322.20

127211.90

127239.50

123305.50

of measure- ..

. . Measure- ment point . . . ^ ment point

250.17

TSC 250.07

TPVC 252.77

TPVC 252.52

TSC 250.69

271.45

TSC 251.03

TSC 249.86

-.

TSC 250.03

251.68

250.05

249.97

249.67

_.

TPVC 250.46

TPVC 251.23

-

..

-

250.84

._

-

248.69

..

-

TPVC 258.61

TPVC 258.53

-

-

-

-

-

-

-

-

..

-

-

-

-

-

Land 

surface

248.20

247.80

250.10

250.20

248.30

270.40

247.10

248.50

256.30

247.20

249.20

247.40

247.40

247.70

250.00

247.90

248.30

241.60

250.80

250.50

248.30

250.90

246.90

246.70

250.00

249.50

257.00

256.80

240.90

240.00

349.20

349.30

256.10

256.50

252.80

256.70

249.80

255.40

255.10

245.00

255.60

255.60

266.70

Top of 

screen or 

opening

4.50

-

33.50

13.80

~

~

-

~

--

--

30.00

~

~

8.50

36.00

7.00

31.80

25.00

20.00

23.00

7.50

18.00

15.00

7.00

20.00

16.00

29.40

12.50

~

-

~

-

6.00

60.00

27.00

30.00

37.00

19.00

6.00

36.00

21.50

5.40

Depth to

Bottom of 

screen or 

opening

7.50

33.90

43.50

23.80

23.00

22.00

34.50

24.80

-

20.50

40.00

-

-

9.50

36.00

17.00

41.80

35.00

25.00

28.00

8.50

28.00

15.00

8.00

25.00

16.00

36.40

27.50

-

-

-

-

16.00

70.00

33.00

40.00

43.00

29.00

16.00

42.00

31.50

15.40

Re*Msal Bedrock

..

..

47

..

..

..

--

-

..

~

-

-

-

36

..

43.5

39

28.5

31

--

34

15

-

32

16

27.5

-

..

23

~

..

56

37

--

45

34

53

19

_.

12

72 Construction and Calibration of Numerical Ground-Water-Flow Models of the Western Half of the Milford-Souhegar Glacial-Drift 

Aquifer, Milford, New Hampshire
Appendix 4. Information on well construction (sorted by easting location) for selected wells in Milford, New Hampshire 

-Continued

Well 

number 

on 

plate 1

13

11

158

156

204

6

150

5

148

149

7

151

8

152

Altitude of

n<ac»f»rirvttnn

Well name

GW-05D

GW-03D

GW-05S

GW-03S

MI- 13

LW-02D

LW-02S

LW-01D

LW-01M

LW-01S

LW-03D

LW-03S

LW-04D

LW-04S

Easting

984174.30

984183.60

984189.90

984191.20

984325.50

984490.30

984495.90

984848.90

984856.90

984856.90

984873.40

984876.20

985001.00

985003.80

Northing

127024.90

126015.00

127055.10

126042.60

123765.20

124835.40

124860.80

125391.90

125418.50

125419.50

124642.50

124673.40

124601.20

124625.30

of measure- .. 

. . Measure- ment point . . . ^ ment point

-

..

251.42

245.66

245.91

-

251.14

250.44

246.43

246.46

Land 

surface

261.00

252.40

264.20

252.40

249.60

243.10

243.40

264.80

265.10

265.20

247.30

250.00

243.40

244.80

Top of 

screen or 

opening

23.00

28.00

7.00

8.40

12.00

45.00

4.00

100.00

42.60

25.60

44.50

9.00

40.00

5.00

Depth to

Bottom of 

screen or 

opening

33.00

38.00

17.00

18.40

18.00

55.00

14.00

110.00

52.60

35.60

54.50

19.00

50.00

15.00

Refusal Bedrock

33

23.5

--

..

33

62.5

..

114.3

_.

-

80.2

..

80

--

APPENDIX 4 73

APPENDIX 5: Ground-water-level hydrographs showing

an example of the comparison between modelcomputed head and observed head from wells MW4B 

(well number 341) and MW10A (well number 316). 

(Location of wells is shown on plate 1)
ILl

£ i 252 £^*J£~

$ 

w

|

uJ

S251

3" 250 

S

DC 

uJ

I

§249 

o

DC 

O

IL.

O

(U

O

t 246

5 500 <

uJ

§ 262

2

10

WELLMW14B (well number 341)

\ 

\

\ 

&2U94

-x computed head 

+ Observed head

+ / 

/+ .

+ - 

&Q5&5

\;

+

600 700

TIME, IN JULIAN DAYS

600 900

WELLMWlOa (well number 316)

260

53

uJ

5

DC 

uJ

| 256

uJ

O

b 256

~x Computed head 

+ Observed head

+ ^^

X

6(21/94

+

500 600 700 

TIME IN JULIAN DAYS

600 900

76 Construction and Calibration of Numerical Ground-Water-Flow Models of the Western Half of the Milford-Souhega- Glacial-Drift 

Aquifer, Milford, New Hampshire