HYDROGEOLOGY AND GEOCHEMISTRY OF ACID MINE 

DRAINAGE IN GROUND WATER IN THE VICINITY OF 

PENN MINE AND CAMANCHE RESERVOIR, C A LAYER AS 

COUNTY, CALIFORNIA: FIRST-YEAR SUMMARY

By Scott N. Hamlin and Charles N. Alpers

U.S. GEOLOGICAL SURVEY

Water-Resources Investigations Report 94-4040

Prepared in cooperation with the

CALIFORNIA STATE WATER RESOURCES CONTROL BOARD and the

EAST BAY MUNICIPAL UTILITY DISTRICT

Sacramento, California 

1995
U.S. DEPARTMENT OF THE INTERIOR 

BRUCE BABBITT, Secretary

U.S. GEOLOGICAL SURVEY 

Gordon P. Eaton, Director

For sale by the U.S. Geological Survey 

Earth Science Information Center 

Open-File Reports Section 

Box 25286, MS 517 

Denver Federal Center 

Denver, CO 80225

For additional information write to: 

District Chief 

U.S. Geological Survey 

Federal Building, Room W-2233 

2800 Cottage Way 

Sacramento, CA 95825
CONTENTS

Abstract 1 

Introduction 2

Background 2

Purpose and scope 5 

Study methods 6

Drilling and well construction 6

Geophysical logging and flowmeter tests 6

Identification of fracture zones 7

Inflatable-packer methodology 8

Ground-water sampling and analysis 8

Water-level measurements 9 

Hydrogeology 9

Geology and mineralogy 9

Geologic structure 9

Hydraulic characteristics of fractured bedrock 11

Water levels 15 

Geochemistry 16

Results of sampling 16

Generation of acid mine drainage 20

Distribution of acid mine drainage 22

Geochemical correlations 26 

Flow rate of contaminated ground water 29 

Metal loading to Camanche Reservoir 29 

Summary 30 

References 31 

Appendix 1. Geophysical logs from U.S. Geological Survey monitoring wells GS-1 through GS-8 at Perm

Mine site 33 

Appendix 2. Flowmeter data from U.S. Geological Survey monitoring wells GS-1 through GS-8 at Perm Mine

site 41 

Appendix 3. Purging-log data for U.S. Geological Survey monitoring wells GS-1 through GS-8 at Perm Mine

site 43

Appendix 4. Hydraulic test data from U.S. Geological Survey monitoring wells GS-1 through GS-8 at Penn 

Mine site 44

FIGURES

1-3. Maps showing:

1. Location of Penn Mine and Camanche Reservoir in Foothills copper-zinc belt

of California 3 _ _

2. Penn Mine site and location of unlined wastewater impoundments 4

3. Location of monitoring wells, geologic section lines, and surficial geology 7

4. Geologic section A-A' and water levels constructed using data from Camanche Reservoir, wells GS-3 

and GS-8, and Mine Run Reservoir 10

5. Map showing subsurface altitude of the metavolcanic-slate contact 11

6. Hydrograph showing fluctuations in water levels in Camanche Reservoir, Mine Run Reservoir, and in 

wells at the Penn Mine 14

7. Map showing water-levels in the metavolcanic unit, August 1992 16

Contents
8,9. Geologic section B-ff showing:

8. Distribution of sulfate with depth at the Penn Mine, April 1992 23

9. Distribution of chloride with depth at the Penn Mine, April 1992 24

10. Map showing distribution of sulfate in ground water at the Penn Mine, April 1992 25

11. Graph showing variation of sulfate concentration with pH in ground water from the Penn Mine, 

April 1992 25

12. Maps showing distribution of pH in ground water at the Penn Mine, April and December 1992 26

13. Graph showing stable-isotopic composition of ground water and Mine Run Reservoir at the Penn 

Mine, April and December 1992 27

14. Map showing distribution of delta oxygen-18 in ground water at the Penn Mine, April 1992 27 

15-17. Graphs showing:

15. Variation of iron with sulfate concentrations in ground water from the Penn Mine, 

April 1992 28

16. Plot of log (Fe3+ activity) and pH with goethite and hydrous ferric oxide equilibrium values 

for ground water from the Penn Mine, April 1992 28

17. Plot of log (A13+ activity) and pH with gibbsite equilibrium values for ground water from 

the Penn Mine, April 1992 29

TABLES

1. Estimates of transmissivity and hydraulic conductivity at the Penn Mine, April 1992 12

2. Altitude of water levels for U.S. Geological Survey monitoring wells at the Penn Mine, December 1991 

to August 1992 13

3. Water-quality data for Mine Run Reservoir and wells at the Penn Mine 17

4. Estimates of ground-water flow and metal loading to Camanche Reservoir 30

CONVERSION FACTORS, WATER-QUALITY INFORMATION, VERTICAL DATUM, AND WELLNUMBERING SYSTEM

Conversion Factors

Multiply By To obtain

acre 

acre

cubic foot per day (frVd)

cubic foot per second (frVs)

foot (ft)

foot per day (ft/d)

foot per minute (ft/min)

foot squared per day (frVd)

gallon per minute (gal/min)

gallon per year (gal/yr)

mile (mi)

pound, avoirdupois (Ib) 

square foot (ft2)

0.4047

4,047

0.02832

0.02832

0.3048

0.3048

0.3048

0.0929

0.06308

0.003785

1.609

0.4536

0.09290

hectare 

square meter 

cubic meter per day 

cubic meter per second 

meter

meter per day 

meter per minute 

meter squared per day 

liter per second 

cubic meter per year 

kilometer 

kilogram 

square meter

Temperature is given in degrees Celsius (°C), which can be converted to degrees Fahrenheit (°F) by the 

following equation:

°F=1.8(°C)+32.

IV Conversion Factors, Water-Quality Information, Vertical Datum, and Well-Numbering System
Water-Quality Information

Chemical concentrations in water are given in milligrams per liter (mg/L) or micrograms per liter Qag/L). 

Milligrams per liter is a unit expressing the solute per unit volume (liter) of water. One thousand micrograms per liter is 

equivalent to 1 milligram per liter. For concentrations less than about 7,000 mg/L, milligrams per liter is equivalent to 

"parts per million," and micrograms per liter is equivalent to "parts per billion."

Vertical Datum

Sea level: In this report, "sea level" refers to the National Geodetic Vertical Datum of 1929 a geodetic datum 

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

Datum of 1929.

Well-Numbering System

Wells are identified and numbered according to their location in the rectangular system for the subdivision of 

public lands. Identification consists of the township number, north or south; the range number, east or west; and the 

section number. Each section is divided into sixteen 40-acre tracts lettered consecutively (except I and O), beginning 

with "A" in the northeast corner of the section and progressing in a sinusoidal manner to "R" in the southeast corner. 

Within the 40-acre tract, wells are sequentially numbered in the order they are inventoried. The final letter refers to the 

base line and meridian. In California, there are three base lines and meridians; Humboldt (H), Mount Diablo (M), and 

San Bernardino (S). All wells in the study area are referenced to the Mount Diablo base line and meridian (M). Well 

numbers consist of 11 characters and follow the format 004N10E4G02. In this report, well numbers are abbreviated and 

written 4N/10E-4G2. Wells in the same township and range are referred to only by their section designation, 4G2. The 

following diagram shows how the number for well 4N/10E-4G2 is derived.

RANGE

R2W R1W R1E R10E

0. 

(0

I

T6N

T5N

T4N

4N/10E-4G2

Conversion Factors, Water-Quality Information, Vertical Datum, and Well-Numbering System V
HYDROGEOLOGY AND GEOCHEMISTRY OF ACID MINE 

DRAINAGE IN GROUND WATER IN THE VICINITY OF 

PENN MINE AND CAMANCHE RESERVOIR, CALAVERAS 

COUNTY, CALIFORNIA: FIRST-YEAR SUMMARY

By Scott N. Hamlin and Charles N. Alpers

Abstract

Acid drainage from the Penn Mine in 

Calaveras County, California, has caused 

contamination of ground water between Mine 

Run Dam and Camanche Reservoir. The Penn 

Mine was first developed in the 1860's primarily 

for copper and later produced lesser amounts of 

zinc, lead, silver, and gold from steeply dipping 

massive sulfide lenses in metamorphic rocks. 

Surface disposal of sulfidic waste rock and 

tailings from mine operations has produced acidic 

drainage with pH values between 2.3 and 2.7 and 

elevated concentrations of sulfate and metals, 

including copper, zinc, cadmium, iron, and 

aluminum. During the mine's operation and after 

its subsequent abandonment in the late 1950's, 

acid mine drainage flowed down Mine Run into 

the Mokelumne River. Construction of 

Camanche Dam in 1963 flooded part of the 

Mokelumne River adjacent to Penn Mine. 

Surface-water diversions and unlined 

impoundments were constructed at Penn Mine in 

1979 to reduce runoff from the mine, collect 

contaminated surface water, and enhance 

evaporation. Some of the contaminated surface 

water infiltrates the ground water and flows 

toward Camanche Reservoir.

Ground-water flow in the study area is 

controlled by the local hydraulic gradient and the 

hydraulic characteristics of two principal rock 

types, a Jurassic metavolcanic unit and the 

underlying Salt Spring slate. The hydraulic 

gradient is west from Mine Run impoundment

toward Camanche Reservoir. The median 

hydraulic conductivity was about 10 to 50 times 

higher in the metavolcanic rock (0.1 foot per 

day) than in the slate (0.002 to 0.01 foot per 

day); most flow occurs in the metavolcanic rock 

where hydraulic conductivity is as high as 50 feet 

per day in two locations. The contact between 

the two rock units is a fault plane that strikes 

N20°W, dips 20°NE, and is a likely conduit for 

ground-water flow, based on down-hole 

measurements with a heat-pulse flowmeter.

Analyses of water samples collected during 

April 1992 provide a comprehensive characterization of ground water below Mine Run Dam 

at the Penn Mine. Specific conductance of the 

samples ranged from 1,810 to 18.000 microsiemens per centimeter. pH values of sampled 

ground water ranged from 3.7 to 7.8. Dissolved 

constituents in ground water ranged from less 

than 0.010 to 86 milligrams per liter for copper, 

from less than 0.010 to 240 milligrams per liter 

for iron, from less than 0.01 to 250 milligrams 

per liter for aluminum, and from 0.020 to 600 

milligrams per liter for zinc. A contaminated 

ground-water plume appears to originate in the 

metavolcanic unit along the north abutment of 

Mine Run Dam. The plume is characterized by 

low pH, high concentrations of sulfate and 

dissolved metals, and enrichment of the heavy 

stable isotopes of hydrogen and oxygen. 

Dissolved iron and sulfate correlate positively, 

suggesting pyrite as the probable source of these 

elements. The concentrations of some dissolved 

constituents apparently are controlled by equilibAbstract l
rium with solid mineral phases. Poorly crystalline hydrous ferric oxide and microcrystalline 

gibbsite are close to saturation in ground water 

with pH values between 4 and 7.8 and probably 

control the solubility of Fe3+ and A13+, 

respectively.

Using a range of bulk hydraulic conductivity 

values for the metavolcanic unit from the median 

value (0.1 foot per day) to the highest values (50 

feet per day), together with a representative 

cross-sectional area (3,000 square feet) for the 

contaminated ground-water plume and a 

hydraulic gradient of 0.14 from August 1992, the 

following range in ground-water flow rates is 

estimated by Darcy's law: 42 to 21,000 cubic 

feet per day, or 105 to 5xl07 gallons per year. 

Multiplying this estimated range in ground-water 

flow by representative metal concentrations from 

the contaminated plume gives the following 

estimates for annual metal transport to Camanche 

Reservoir by ground water: 86 to 42,000 pounds 

of copper; 310 to 150,000 pounds of zinc; and 

1.5 to 750 pounds of cadmium. These crude 

preliminary estimates may be refined using 

numerical modeling of flow and transport 

processes. The high values for metal transport 

rates are upper bounds and represent worst-case 

conditions.

INTRODUCTION 

BACKGROUND

The Penn Mine is an abandoned copper-zinc mine 

in the Foothills copper-zinc belt in northwestern 

Calaveras County, California (Peterson, 1985) (fig. 1). 

The mine property encompasses about 140 acres 

(Finlayson and Rectenwald, 1978) in the Mine Run 

drainage basin, an intermittent tributary to Camanche 

Reservoir. Mining activity at Penn Mine lasted from 

the early 1860's to the late 1950's (Clark and Lydon, 

1962). The area has 20 or more shafts, several adits, 

and numerous open pits and cuts; two smelters and 

several mills operated at the site (Clark and Lydon, 

1962). About 10.5 mi of underground workings were 

excavated to a depth of 3,300 ft (Heyl and others, 

1948). Several acres of mill tailings and unmilled 

waste rock are exposed on the surface (Bond, 1988); 

slag from the smelters was dumped in a 1,500- 

foot-long area immediately adjacent to the former

Mokelumne River channel (Finlayson and 

Rectenwald, 1978).

Historically, contaminated surface runoff from the 

Penn Mine flowed directly into the Mokelumne River 

(Shaw and Towers, 1937; Dunham, 1961). 

Completion of Pardee Dam in 1929 on the river about 

3 mi upstream from the mine decreased the 

streamflow available for diluting the contaminated 

runoff. Completion of Camanche Dam in 1963 

resulted in flooding part of the Mokelumne River 

basin from about 9 mi downstream of Penn Mine to 

approximately 0.5 mi upstream. The spillway 

elevation of Camanche Dam is 236 ft above sea level. 

Consequently, slag at the mine is partly flooded when 

the reservoir pool is higher than about 200 ft above 

sea level (Finlayson and Rectenwald, 1978).

Fish mortality in the Mokelumne River owing to 

contamination from the Penn Mine was recorded as 

early as 1937 (Shaw and Towers, 1937) and 

continued periodically until the beginning of the 

construction of Camanche Dam in 1960 (Dunham, 

1961; Finlayson and Rectenwald, 1978). Fish 

mortality at the salmon and steelhead hatchery, 

completed just downstream from Camanche Dam in 

1964, was documented in 1967, 1973, 1977, 1987, 

and 1989 (Bond, 1988; S.R. Bond, California 

Regional Water Quality Control Board Central 

Valley Region, written commun., 1989), although no 

surface-water discharges were emitted from Penn 

Mine from June 1986 to January 1993 (T. Pinkos, 

California Regional Water Quality Control BoardCentral Valley Region, written commun., 1993).

Several diversion channels were constructed in 

1978 at the Penn Mine site to divert unpolluted water 

from upstream areas on Hinckley and Mine Runs to 

Camanche Reservoir (T. Pinkos, California Regional 

Water Quality Control Board Central Valley Region, 

written commun., 1978, 1979). Seven unlined 

impoundments were built in place of two or more 

existing impoundments to capture contaminated runoff 

from the site (fig. 2). The Mine Run Dam, constructed from nonreactive earth materials with a clay 

core (California Regional Water Quality Control 

Board-Central Valley Region, written commun., 

1979), was built by the East Bay Municipal Utility 

District (herein referred to as the Utility District) on 

their property between the mine and Camanche 

Reservoir. The remaining dams or dikes were 

constructed from available sulfide-bearing waste rock 

and mill tailings; the impoundments were unlined. 

They were constructed on property belonging to New

2 Hydrogeology and Geochemistry of Acid Mine Drainage In Ground Water, Penn Mine and Camanche Reservoir
120°

AREA OF 

FIGURE

37°

50 MILES

I 

50 KILOMETERS

EXPLANATION

Copper-zinc belt 

 Outline of Calaveras County

Figure 1 . Location of Penn Mine and Camanche Reservoir in Foothills copper-zinc belt of California (after 

Petersoa 1985).

Introduction 3
120°52'47" 

38°14'0r

120°52'30"

38°14'00"

38°13'46"

rx Stock 

if pond

Camanche 

Reservoir

Hinckley Run |HR3 

Diversion 

Mine Run 

Reservoir

EXPLANATION

>>x:J Mixed and affected soil and fill 

Waste rock

Wastewater impoundment 

Mill tailing 

| | Clay-core dam 

^H Berm in waste rock 

1 Slag

30 60 120 METERS

Figure 2. Penn Mine site and location of unlined wastewater impoundments. (Distribution of mixed and 

affected soil, mixed fill, waste rock, and tailings modified from Davy Environmental. 1993).

4 Hydrogeology and Geochemistry of Acid Mine Drainage In Ground Water, Penn Mine and Camanche Reservoir
Penn Mines, Inc., by the California Regional Water 

Quality Control Board Central Valley Region (herein 

referred to as the Control Board) (California Regional 

Water Quality Control Board-Central Valley Region, 

written commun., 1978, 1979). The system, designed 

to enhance evaporation of contaminated water by 

pumping the water from Mine Run Reservoir to 

upstream ponds on Mine Run, was operated jointly by 

the Utility District and the Control Board between 

1979 and 1992 (T. Pinkos, California Regional Water 

Quality Control Board Central Valley Region, written 

commun., 1993).

Recirculation of water in the ponds has increased 

the amount of evaporation and the contact time of 

acid drainage with the reactive waste rock and tailings 

(Bond, 1988). As much as 95 percent of the sulfide 

minerals in waste rock has been oxidized (Davy 

Environmental, 1993). Because the impoundments 

are unlined, some of the water in the lowermost 

impoundment can infiltrate the underlying aquifer in 

fractured metamorphic rock. In addition, controlled 

releases of surface water from Mine Run Reservoir to 

Camanche Reservoir were made during wet periods in 

1979 through 1984 and in 1986 at rates estimated 

between 0.1 and 0.7 ft3/s; uncontrolled releases 

estimated as high as 2.7 ft3/s occurred during 

extremely wet periods in 1983 and 1986 (Bond, 

1988). Surface-water releases did not take place 

between June 1986 and January 1993 during a time of 

prolonged drought. However, a relatively small 

amount of surface water discharged during 

February-March 1993 after Mine Run Reservoir had 

been treated with hydrated lime [Ca(OH)2] to attain a 

pH value of greater than 7.0 (Richard Sykes, East Bay 

Municipal Utility District, oral commun., 1993).

Concentrations of metals and sulfate in the 

wastewater ponds fluctuate seasonally, with maximum 

concentrations in the late summer/early autumn 

(August to October) possibly from evaporative 

concentration (Davy Environmental, 1993). Data 

collected since 1987 do not indicate any clear longterm trends in the concentrations from year to year 

(Davy Environmental, 1993). Oxidative dissolution 

of metal sulfides has continued unabated on the site, 

however, so metals released to solution since 1987 

have either accumulated in sediment on the bottoms 

of the ponds or have been transported out of the 

ponds into ground water.

To quantify the flux of metals leaving the unlined 

impoundments, information needed to define the 

extent of contamination and develop remediation 

alternatives, the U.S. Geological Survey (USGS), in 

cooperation with the Control Board and the Utility 

District, investigated the chemical composition and 

movement of ground water at Penn Mine from 

December 1991 to December 1992. The specific 

objectives of the investigation by the USGS are: (1) 

to determine the quantity and quality of ground water 

flowing into Camanche Reservoir from the Penn Mine 

area, (2) to quantify ground-water transport of metals, 

sulfate, and acidity between Mine Run and Camanche 

Reservoirs, (3) to collect hydrologic and chemical 

data that will contribute to an understanding of the 

water balance in the Mine Run drainage basin, and 

(4) to provide technical information to the cooperating 

State and regional agencies (the Utility District and 

the Control Board) that will assist in formulating 

remediation plans for Penn Mine. Accomplishment of 

these objectives will facilitate the development of 

effective pollution abatement measures for the site.

PURPOSE AND SCOPE

This report presents initial findings from the first 

year of the U.S. Geological Survey study to 

characterize the distribution of metals, sulfate, and 

acidity in ground water flowing through the fracturedrock aquifer between Mine Run Dam and Camanche 

Reservoir (fig. 2). The report describes the geologic 

structure, ground-water movement, and the distribution of acidic mine drainage in the ground-water 

system. Geologic, hydrologic, and water-quality data 

were collected during 1991-92 from eight wells 

drilled in this area. Lithologic data from drill cuttings 

and geologic logs show the location of the contact 

between the two major rock types in the area, 

greenschist-grade metavolcanic rock (Gopher Ridge 

volcanics) and slate (Salt Spring slate). Downhole 

acoustic-televiewer logs show the orientation and 

location of fractures and the lithologic contact. 

Downhole tests with a heat-pulse flowmeter have 

determined the location of fractures that conduct 

ground-water flow. Composite and depth-specific 

water samples were collected three times during the 

study period. Water-quality data were compiled and 

analyzed to determine chemical relations and mineral 

equilibria.

Introduction 5
STUDY METHODS

DRILLING AND WELL CONSTRUCTION

Eight boreholes were drilled during November 

4-15, 1991. Locations of the USGS monitoring wells 

GS-1 through GS-8 are shown in figure 3. A 

9.5-inch-diameter rotary bit was used to penetrate the 

overburden (alluvium and slag) and the upper 5 to 8 

ft of underlying bedrock (metavolcanic rock). In 

most cases, compressed air was sufficient to keep the 

hole open during rotary drilling, but a foam drilling 

additive was required at three boreholes to prevent 

caving. The water used during drilling was spiked 

with sodium bromide to yield a bromide concentration 

of about 100 mg/L (milligrams per liter) to facilitate 

detection of ground-water contamination during subsequent water-quality sampling. Drill cuttings were 

monitored continuously, and samples were collected 

every 5 to 10 ft.

Six-inch-diameter polyvinyl chloride (PVC) 

casing (schedule 40) was set to the depth of the 

9.5-inch-diameter holes, which ranged from 20 to 40 

ft below land surface. The bottom 5 ft of the annular 

space between casing and hole wall was filled with 

3/8-inch bentonite pellets followed by hydrated mortar 

mix. In holes with more than 20 ft of PVC casing, 

non-sulfide-bearing drill cuttings were used for some 

of the backfilling of the annular space surrounding the 

casing. The upper 3 to 4 ft of the annular space was 

filled with hydrated mortar mix and left to set 

overnight.

After the mortar mix had set, a 5.5-inch-diameter 

air-hammer bit was used to drill into the bedrock 

through the 6-inch casing until the desired depth was 

reached. All eight boreholes were drilled to a depth 

of 200 ft below land surface except GS-6, which was 

drilled to a depth of 400 ft below land surface. The 

thickness of slag, which covers most of the area west 

of Mine Run Dam, ranged from 0.5 to 38 ft. The 

contact between metavolcanic rocks and slate was 

encountered in seven of the holes between depths of 

45 and 105 ft below land surface. In hole GS-7, the 

lithology changed back and forth between slate and 

metavolcanic rock indicating a disrupted zone, 

possibly a fault zone or a tightly folded contact. 

Drilling through the Salt Spring slate unit was 

extremely fast with the air-hammer bit, averaging 

more than 2 ft/min. Five of the eight wells drilled 

"dry," not producing any flowing water. Heat 

generated from the compressed air during drilling 

tends to dry out drill cuttings on their path up the 

hole, so inflows of less than 0.5 gal/min can result in 

dry cuttings (J.A. Singer, U.S. Geological Survey,

oral commun., 1991). The three "wet" holes (more 

than 0.5 gal/min inflow) were GS-5, -7, and -8. After 

drilling, all the holes were left open below the 6-inch 

casing, except for hole GS-7, which partially caved 

and was filled with slotted, 3-in-diameter PVC casing 

to a depth of 50 ft below land surface.

GEOPHYSICAL LOGGING AND FLOWMETER TESTS

The open boreholes were logged by standard geophysical methods, acoustic televiewer, and heat-pulse 

flowmeter during November 1991. The standard 

geophysical logs included natural gamma, fluid 

temperature, lateral resistivity [single point, 16 and 32 

mm (millimeter)], fluid resistivity, short-normal resistivity, long-normal resistivity, and caliper. The 

gamma log differentiates the two principal rock types 

encountered: slate and metavolcanic rock units. The 

relatively high radioisotope (K, U) content of the slate 

gives it a distinctively high gamma response. The 

gamma logs are provided in appendix 1.

The acoustic televiewer uses high-frequency 

acoustic energy to produce a 360° visual record of the 

borehole surface (Zemanek and others, 1970). It can 

yield high-resolution information about the location 

and character of fractures and other openings, as well 

as provide the strike and dip of individual fractures 

and groups of fractures. The thickness or aperture of 

individual fractures also can be estimated from this 

log. The acoustic televiewer is not subject to the 

problems of optical clarity and distortion common to 

some video-camera logs (Paillet and others, 1987; 

Paillet and Kapucu, 1989).

Downhole flowmeter tests determined intervals of 

natural or induced flow. The flowmeter consisted of 

two thermistors, one located above and one below a 

filament that puts out a tiny heat pulse when triggered 

(Hess, 1986; Paillet and others, 1987). The velocity 

of flow in the borehole is inversely proportional to 

the time it takes the pulse to reach one of the 

thermistors. Detection of the pulse by the upper or 

lower thermistor determines whether flow is up or 

down. An inflatable bladder concentrates the flow 

through the meter to facilitate the determination of 

low-flow rates. The flowmeter response is calibrated 

directly to discharge, rather than using an interim 

determination of velocity. The lower limit of 

detection for this method is about 0.02 gal/min when 

measured in a 6-inch well (Hess, 1986). Flowmeter 

tests could not be done in boreholes GS-5 and -7 

owing to caving that occurred prior to arrival of the 

logging equipment.

6 Hydrogeology and Geochemistry of Acid Mine Drainage In Ground Water, Penn Mine and Camanche Reservoir
120°52'50" 

38°14'00"

120°52'45" 120°52'40"

Hinckley Run 

Diversion

Wastewater impoundment

A A' Line of section 

GS-2

.W-3S

USGS well and number

EBMUD well and number

Figure 3. Location of monitoring wells, geologic section lines, and surflcial geology.

IDENTIFICATION OF FRACTURE ZONES

In general, an excellent correlation was found 

between the downhole acoustic televiewer and the 

caliper logs. Fracture zones indicated by televiewer 

logs tend to be associated with large-diameter 

segments of the caliper logs. In several of the holes, 

the metavolcanic-slate contact is a large-diameter

zone, probably a conduit for ground-water flow. 

Graphical reproductions of the televiewer logs are 

included in appendix 1.

The flowmeter tests were run in static and 

injection modes. Results of these tests are included 

in appendix 2. The flowmeter was lowered into the 

well in the static mode, and readings were taken at

Study Methods 7
several depths. Static tests were completed in 

boreholes GS-1, -2, -3, -5, and -8. Only one site, 

well GS-8, yielded conclusive results in the static 

mode and exhibited downward flow of approximately 

1 gal/min in the depth interval 43 to 60 ft below land 

surface. Flow was not detected at depths greater than 

67 ft below land surface in well GS-8, indicating that 

flow was leaving the well in a fractured zone between 

60 and 67 ft below land surface along the fault 

contact between metavolcanic rock and slate. 

Borehole GS-5 yielded evidence of slight downward 

flow in static mode at a depth of 43 ft below land 

surface; however, large borehole diameters caused by 

extensive caving made it difficult to find depths at 

which flowmeter tests could be made in this well.

INFLATABLE-PACKER METHODOLOGY

Segments of the bore holes were isolated for 

additional testing to distinguish flow and chemical 

characteristics of individual fracture zones. Four 

inflatable packers were installed in three of the 

fractured-rock monitoring wells. Double (straddle) 

packers were installed at one site and single packers 

were installed at the two remaining sites. Once 

inflated, the packer virtually eliminates vertical 

ground-water flow and mixing.

Single packers were installed at sites GS-1 and 

GS-8. Upper intervals were designated as "A" and 

lower intervals as "B". The packer at GS-1, set at a 

depth of 80 ft below land surface, separated two 

intervals, GS-1A and -IB. The upper interval 

monitored the metavolcanic unit and metavolcanic-slate contact at a depth of 70 ft below land 

surface. The lower interval monitored the slate unit 

exclusively. The packer at GS-8 was set at a depth of 

76 ft below land surface. Interval GS-8A monitored 

the metavolcanic unit and the metavolcanic-slate 

contact; GS-8B monitored ground water in the slate 

unit. Two packers (a "straddle" assembly) were 

installed at site GS-4 at depths of 55 and 80 ft below 

land surface. The intervals are designated GS-4A, 

-4B, and -4C from shallow to deep levels. GS-4A 

monitored ground water in the upper part of the 

metavolcanic unit. GS-4B monitored the lower part 

of the metavolcanic unit and the metavolcanic-slate 

contact. GS-4C monitored the slate unit exclusively. 

Hole GS-6 was open from 30 to 400 ft below land 

surface and monitored both the slate and metavolcanic 

units. The remaining sites (GS-2, -3, -5, and -7) were 

drilled to a depth of 200 ft below land surface and 

also monitored ground water from both the slate and 

metavolcanic units.

The packer assemblies required customization to 

minimize exposure of metallic parts to ground water, 

which could compromise water-quality sampling by 

either dissolution or adsorption of base metals. 

Custom features in this application were (1) a PVC 

liner in the central, through-going steel tube, and (2) 

two through-going, stainless-steel tubes in the upper 

packer of the two-packer assembly for inflation and 

water transmission. One of the stainless-steel tubes 

installed in the upper packer transmitted water from 

the middle interval; the other tube connected the 

tubing that carries gas to inflate the lower packer 

assembly. Exposed parts of the packers were mainly 

stainless steel and rubber. Some reactive steel parts 

also were exposed; these were covered with 

0.25-millimeter-thick plastic tape. The epoxy paint 

initially used to protect the steel parts disintegrated in 

the acidic ground water at the site.

GROUND-WATER SAMPLING AND ANALYSIS

The wells installed by the USGS were sampled 

during three periods: January 26-February 1, 1992; 

April 13-18, 1992; and December 10-22, 1992. 

Specific conductance, hydrogen-ion activity (pH), 

temperature, dissolved oxygen, and oxidationreduction potential (Eh) were measured in the field. 

These properties were determined from samples 

collected during pumping or bailing. Purging-log data 

are compiled in appendix 3. Field properties were 

measured using a flow-through chamber to prevent 

aeration of the ground water. After field properties 

stabilized, water samples were collected and processed 

using standard methods adopted by the USGS (Wood, 

1976). Samples for anion analysis were filtered using 

0.10-um (micrometer) membranes. Samples for 

cation analysis were filtered in a similar manner and 

acidified with hydrochloric or nitric acid to a pH of 

about 1. Samples for nutrient analysis were filtered, 

preserved with mercuric chloride, and chilled. All 

samples were submitted to the USGS central 

laboratory for analysis. Replicate samples processed 

at four sites were submitted to the Utility District 

laboratory for comparison.

Laboratory analytical techniques for dissolved 

constituents are described by Fishman and Friedman 

(1985). Methods used to determine stable-isotope 

ratios for hydrogen are described by Coplen and 

others (1991) and for oxygen by Epstein and Mayeda 

(1953). Dissolved cadmium, calcium, copper, iron, 

magnesium, manganese, potassium, sodium, and zinc 

were determined using atomic absorption spectrometry 

(AAS) with air aspiration. Lead was determined by

8 Hydrogeology and Geochemistry of Acid Mine Drainage in Ground Water, Penn Mine and Camanche Reservoir
AAS using a graphite furnace. Aluminum was 

determined by AAS using a direct-current argon 

plasma. The anions chloride, fluoride, and sulfate 

were determined by ion chromatography. Silica and 

bromide were determined using colorimetric 

techniques.

WATER-LEVEL MEASUREMENTS

Water levels were measured and compiled after 

the installation of inflatable borehole packers. Initial 

measurements were made with a calibrated steel tape. 

Concern over contamination of well water and 

problems with condensation inside the well casing 

prompted a change to an electric sounder in January 

1992. Automated water-level recorders were installed at sites GS-1, -4, -6, and -8. Shaft encoders, 

in conjunction with float-counterweight mechanisms, 

were used at wells GS-1A, -IB, -4B, -4C, -6, -8A, 

and -8B. Because of space limitations, a pressure 

transducer was used to monitor water levels in well 

GS-4A. Water-level data were recorded on an hourly 

basis with datalogger units at each of the four 

instrumented sites.

Water-level drawdown and recovery data were 

collected from boreholes during the water-quality 

sampling in April 1992. Static water levels were 

measured with an electric sounder prior to pumping 

or bailing and immediately afterwards during 

recovery. Because water levels change most rapidly 

during the period immediately after pumping stops, 

initial water levels were measured frequently, about 

once per minute. After about the first 10 minutes of 

recovery, the frequency of measurements was reduced 

to once every 10 minutes, then to hourly, and 

eventually to daily readings. Because analysis of 

water-level data collected during aquifer tests uses a 

log scale for time, measurement frequency generally 

corresponds to powers of ten (10, 100, 1,000,...). 

These data are presented graphically in appendix 4.

of one intrusive and five volcanic units; and (3) the 

metasedimentary Salt Spring slate (Peterson, 1985) 

(fig. 3). Metavolcanic rocks in the area have weak to 

intense bedding, schistosity, and cleavage that trend 

N30°W to N and dip steeply to the northeast or east 

(Peterson, 1985; Martin, 1988).

Fine-grained white mica, quartz, and hematite are 

locally abundant near the mineralized zones, owing to 

hydrothermal alteration that accompanied the sulfide 

mineralization of Jurassic age. Minerals formed 

during the greenschist-grade metamorphism include 

chlorite, epidote, pumpellyite, quartz [in veins up to 

10 cm (centimeter) in width], and additional mica. 

Schistosity is pervasive in areas with abundant white 

mica (from hydrothermal alteration) that was 

recrystaUized in parallel orientation during 

metamorphism in a nonisostatic stress field.

Massive sulfide ore bodies are associated with the 

intrusive metavolcanic unit and consist primarily of 

pyrite (FeS2), chalcopyrite (CuFeS2), and sphalerite 

[(Zn,Fe,Cd)SJ (Peterson, 1985; Martin, 1988). Ore 

bodies occur as steeply pitching lenses along bedding 

or foliation planes and range in size from 150 to 

1,000 ft along pitch, 100 to 400 ft in breadth, and 4 

to 30 ft in width (Heyl and others, 1948). Stringer, 

disseminated, and vein ores are known to be present, 

and minor amounts of bornite (CUsFeSJ, 

tetrahedrite-tennantite [(Cu,Ag,Fe,Zn)12(Sb,As)4S13], 

and galena (PbS) have been reported (Peterson, 1985; 

Martin, 1988). High concentrations of cadmium, 

arsenic, molybdenum, and antimony also are 

associated with the ore (Peterson, 1988).

The following minerals have been identified in 

samples from waste-rock and tailings piles by optical 

examination and x-ray diffraction methods: bornite, 

chalcopyrite, pyrite, sphalerite, galena, brochantite 

[Cu4(SO4)(OH)6], covellite (CuS), halotrichite-pickeringite [(Fen,Mg) A12(SO4)4'22H!O], and copiapite

HYDROGEOLOGY 

GEOLOGY AND MINERALOGY

The study area lies in the western metamorphic 

belt of the Sierra Nevada (Clark, 1964). Marine 

sedimentary and volcanic rocks were deposited in the 

Jurassic period, then buried and metamorphosed 

during the Cretaceous period (Schweickert, 1981). 

Rocks in the vicinity of the mine include (1) a 

Tertiary conglomerate, which unconformably overlies 

all other units and caps the hills; (2) the Gopher 

Ridge Volcanics, a metavolcanic complex consisting

GEOLOGIC STRUCTURE

Geologic features that control the movement and 

distribution of ground water at the Penn Mine include 

fractures in the bedrock, fault planes, and the contact 

between the two major rock types in the area. 

Bedrock fractures that transmit ground water are 

chiefly near the base of the metavolcanic rock unit. 

The metavolcanic-slate contact dips about 20°NE and 

was encountered at depths between 45 and 105 ft 

below land surface in boreholes. The underlying slate 

unit has been identified as the Salt Spring slate by 

Peterson (1985) and is significantly less permeable

Hydrogeology 9
than the overlying metavolcanic rock. The 

metavolcanic-slate contact may be controlled by the 

Campo Seco Fault (Heyl and others, 1948). This 

fault produces an offset in the lithologic contact of 

about 1,000 ft and extends into the mine workings. 

However, the slate unit is not present in the mine 

workings, which were excavated exclusively in 

greenschist-grade metavolcanic rocks. The relatively 

impermeable slate below the contact is likely to form 

a barrier to downward movement of ground water 

from the metavolcanic unit, causing the contact zone 

to act as a conduit that transmits ground water along 

its strike, which is generally N20°W.

Geologic sections (locations indicated in fig. 3) 

were constructed using lithologic data to show the 

orientation of the metavolcanic-slate contact. Figure 

4 shows section A-A', oriented roughly east-west.

Water-levels from August 1992 also are shown. This 

section shows apparent discontinuities in the slope of 

the geologic contact. Some of the discontinuities are 

explained by the presence of a second fault (or tightly 

folded zone) oriented perpendicular to the contact and 

striking roughly N70°E. This fault may have been 

intersected by borehole GS-7; During drilling of 

GS-7, cuttings alternated between slate and 

metavolcanic rock and the hole continually caved in, 

suggesting the presence of fault gouge. This 

hypothesized fault is shown in the contour map of the 

elevation of the top of the slate unit (fig. 5). In 

general, fault surfaces form a barrier to perpendicular 

ground-water flow, whereas flow along the fault 

surface is normally enhanced. Davy Environmental 

(1993) also reported northeast-trending faults in other 

areas of the Penn Mine. Detailed mapping in 

progress by USGS of outcrops near boreholes GS-3,

West

A

FEET 

300-

GS-8

250 

200 

ISO100 

50

.Jl 

metavolcanic rock

.FRACTURE 

ZONE

slate

Water table

100 200 FEET

\^ 

30 60 METERS

Figure 4. Geologic section A-A' and water levels constructed using data from Camanche Reservoir, wells 

GS-3 and GS-8, and Mine Run Reservoir.

10 Hydrogeology and Geochemistry of Acid Mine Drainage In Ground Water, Penn Mine and Camanche Reservoir
120°52147- 120°52'42"

38013'S9" :

Camanche 

=s^=5^ Reservoir

60 METERS

 160 

.162

EXPLANATION 

Slag

Metavolcanlc rock

Fault - Approximately located. Arrow 

shows relative horizontal movement 

U, upthrown side; D, downthrown side

Subsurface contour Shows altitude of 

base of metavolcanic rock. Contour 

interval 10 feet. Datum is sea level

USGS well - Number is altitude of contact 

between slate and metavolcanic rock, in 

feet above sea level

Figure 5. Subsurface altitude of the 

metavolcanic-slate contact. Contours and fault 

represent possible interpretation of geologic 

structure. Altitude of land surface is between 220 

and 225 feet above sea level in slag area.

-4, and -5 has shown a large number of fractures with 

a northeast strike. Another possibility is that the 

metavolcanic-slate contact may have been warped by

anticlinal folding. However, the presence of a second 

fault is the preferred interpretation; the water-level 

and water-quality data presented in subsequent 

sections of this report are consistent with this 

interpretation.

HYDRAULIC CHARACTERISTICS OF FRACTURED 

BEDROCK

Tests for injection inflow were done in boreholes 

GS-1, -2, -3, -4, and -8 at constant head. The 

boreholes were filled with water and inflow rates 

were adjusted to a constant water level during the 

test. The injected water also was spiked with sodium 

bromide tracer to yield a bromide concentration of 

about 100 mg/L. Boreholes GS-1, -2, and -3 required 

less than 1.0 gal/min to maintain constant head 

Boreholes GS-4 and -8 required initially 0.9 and 1.60 

gal/min, respectively; the required injection rate 

gradually declined with time in each well during the 

test. Outflow was detected during these tests through 

fractures in the metavolcanic rock or along the 

metavolcanic-slate contact. The flowmeter data are in 

appendix 2.

Water-level recovery data were collected after 

pumping stopped at wells GS-1 A, -IB, -2, -3, -4A,

-4B, -4C, and -8B. In addition, drawdown data were 

collected during pumping at wells GS-5, -6, -7, and

-8A. Graphical presentations of these data are given 

in appendix 4. Well-bore storage can obscure 

aquifer-test data, particularly in large-diameter wells 

that tap low-permeability aquifers. This effect is 

minimized during late-time drawdown and recovery 

when the rate of water-level change is smallest 

Papadopoulos and Cooper (1967) gave equations that 

quantify this effect. In general, well-bore-storage 

effects are negligible for times greater than 25(r2)/T, 

where r is the casing radius and T is the aquifer 

transmissivity. Using this criterion, late-time data 

from wells GS -5, -7, and -8A should be free of 

well-bore-storage effects. Other sites may show 

well-bore-storage effects, particularly in early-time 

data that tend to overestimate transmissivity. 

Gringarten (1982) also described methods to determine the presence of well-bore-storage effects. He 

noted that well bore storage yields a straight line with 

unit slope on a log-log plot of recovery data. 

Recovery data from wells GS-1 A and -4A (appendix 

4) showed the effects of well-bore storage on the 

basis of these criteria and, therefore, were not used to 

estimate hydraulic conductivity.

Water levels recovered very slowly in well 

GS-1B, indicating low hydraulic conductivity, and 

rapidly in well GS-8A, indicating much higher conHydrogeology 11
ductivity. The data for well GS-1B showed much 

fluctuation during recovery (appendix 4). The water 

level rose and declined, and water made a gurgling 

sound as it entered the well. Fractures supplying this 

interval that may have been completely dried out in 

the upper levels during sampling could explain the 

fluctuating recovery rates.

The Cooper- Jacob straight-line method of analysis 

(Driscoll, 1987) was applied to hydraulic data 

collected at the Penn Mine (appendix 4). Drawdown 

data, in feet below the measuring point, were plotted 

relative to the logarithm of time, in minutes since 

initiation of pumping. Recovery data (residual 

drawdown in feet) were plotted against dimensionless 

time (t/t' = time since pumping started/time since 

pumping stopped). Transmissivity, T, can be 

estimated from the following expression:

T= 264 Q log(t/t' 

As

where

Q = pumping rate (gallons per minute), 

t and t ' = time (minutes), and 

s = drawdown (feet).

Residual drawdown, s', may be substituted for 

drawdown, s, in equation 1. In the absence of 

boundary and well-bore-storage effects, a plot of 

drawdown and log(t/t') should form a straight line.

When t/t' = 10, then log(J/O = 1. Therefore, T = 

264g/(As) for one log cycle (t/t' = 10). The 

drawdown (As), or recovery, was measured over one 

log cycle during late time. An estimate of T was 

determined using the value for (As) and the average 

value for Q during the test (appendix 4). Hydraulic 

conductivity (K) was calculated by dividing T by the 

thickness of the rock unit in the specified interval. 

Estimates of transmissivity and hydraulic conductivity 

are presented in table 1. This method of analysis 

tends to overestimate values for T and K, particularly 

in low-permeability rock (for example, slate). The 

highest calculated value for K is 57 ft/d at well GS-5, 

which penetrates metavolcanic rock and slate. 

Because fractures are primarily in the metavolcanic 

unit, K values are attributed to metavolcanic rock in 

wells that also penetrate the slate unit. The lowest 

value for K is 0.008 ft/d at well GS-1B (slate). In 

general, values of K are higher in the metavolcanic 

rock compared with those in the slate unit, 

particularly in borehole GS-8 (table 1). Most 

fractures are along or near the contact between the 

metavolcanic rock and slate units, chiefly in the 

metavolcanic unit. As a result, the largest volume of 

ground-water flow is expected to be in a zone along 

or adjacent to this contact

Transmissivity values also were estimated from 

specific capacity using a method described by Huntley 

and others (1992). The specific capacity of a well is 

calculated by dividing the pumping rate (0 by 

drawdown (s) after a specific period of time. Specific

Table 1. Estimates of transmissivity and hydraulic conductivity at the Penn Mine, April 1992 

[mv, metavolcanic rock; si, slate; ft, foot; ft/d, foot per day; frVd, square foot per day]

Well

GS-1B

GS-2

GS-3

GS-4B

GS-4C

GS-5

GS-6

GS-7

GS-8A

GS-8B

Depth 

interval

(ft below 

land 

surface)

80 - 200

40 - 200

30 - 200

55- 80

80 - 200

30 - 200

30-400

239- 50

30- 76

76 - 200

Thickness of 

Rock saturated

type

si

mv +

mv +

mv

si

mv +

mv +

mv +

mv

si

si

si

si

si

si

zone 

(ft)

120 '36

'75

25

100 '46

'16

58

33

124

Cooper-Jacob, 

straight-line method

Transmissivity

0.9

1.5

3.5

2.1

4.6

2,600

2.7

190

1,400

2.3

Hydraulic 

conductivity 

(ft/d)

0.008

.04

.05

.08

.05

57

.2

3.3

42

.02

Huntley and others, 1992, 

specific-capacity method

Transmissivity 

(frVd)

0.06

.8

.9

2.0

.2

2,300

1.6

150

350

.2

Hydraulic 

conductivity 

(ft/d)

0.0005

.02

.01

.08

.002

50

.1

2.6

11

.002

'Thickness of saturated zone refers to metavolcanic rock thickness in wells of mixed lithology. 

2Well GS-7 drilled to 200 feet below land surface, caved in below 50 feet below land surface; 3-inch diameter, 

perforated casing installed from land surface to 50 feet below land surface.

12 Hydrogeology and Geochemistry of Acid Mine Drainage In Ground Water, Penn Mine and Camanche Reservoir
Table 2. Altitude of water levels for U.S. Geological Survey monitoring wells at the Penn Mine, December 1991 to August 1992 

[Location of wells shown in figure 3. , no data]

USGS well

Date

12-24-91

1-06-921-22-92

2-12-922-19-922-27-92

3-04-923-09-923-10-923-15-923-16-92

3-18-923-24-92

4-02-92

4-14-924-15-924-16-924-23-924-28-92

5-07-925-15-926-02-926-30-92

7-16-92

8-20-92

GS-1A193.34

194.79

193.80195.30

197.21

195.71194.65195.70195.49

194.87

194.77

194.72194.63

194.52

194.20194.19

194.09193.95

193.80

193.63

193.46

193.18

193.12193.15192.83

OS-IB

200.86202.18

206.30

200.15

204.01206.19

207.34

207.88207.88

208.28208.33208.46208.73209.13

209.63209.64209.64

182.18194.26

203.21

205.07

207.70209.08209.60208.42

GS-2

191.62

194.37

194.06

196.54

200.06

196.90

195.48198.03196.69196.13

195.95

194.58

193.85

193.38

192.89192.45

192.28

191.95

191.74

191.35191.02190.89

190.60

GS-3

215.99217.47216.52217.63

218.74217.75

217.28

217.76217.70

216.67

217.42

216.32216.20216.27

..

216.21

214.15215.43

215.36

215.23

215.12

214.91

215.09215.00214.75

GS-4A

Altitude,

181.84

182.02181.74

182.78

183.30

183.42184.60

184.67

186.59

186.74187.11

187.94187.98186.85185.96185.50

184.21

182.98

180.34180.15180.02179.79

GS-4B

in feet above

......

184.02

186.12

186.30

.186.67

187.60187.65

186.56185.58185.08183.77

182.48179.67

179.59180.47179.23

GS-4C

sea level

..

..

187.87

193.23

193.71

194.40195.62197.17197.44

180.04186.31192.33194.79

195.42197.58197.55

197.51

GS-5

181.34

181.88180.23182.11183.23183.46182.65

185.08187.20187.36186.60

187.54

187.60

185.52

185.01183.70182.41179.58

179.55

179.43

179.13

GS-6

183.56

185.36

185.48185.29187.17

186.43186.18

186.76

186.88187.21188.39

187.29187.98188.02187.11

187.01

185.26

185.85

184.81

184.28

183.40183.23

183.44182.98

GS-7

186.05

186.46187.76

187.80190.44189.49188.94189.48

189.51189.33189.26189.21

189.18

189.18

188.69

188.26

188.06187.67

187.40186.95

186.56

186.47186.18

GS-8A

....

183.94185.99186.19186.57

187.51

187.58

186.41

~

185.56185.03183.72182.43

179.63

179.58180.46179.20

GS-8B

194.92

194.99193.21194.67195.04195.41

195.52

190.80195.17195.38195.57

195.37195.45

195.75195.50

185.72

191.63

194.46

195.08195.50

195.38

195.30

195.17
LU 

LU

LU

cr LU

I

260

250

240

LU 

CO

> 230 

O

220

210 

CO

LU

> 200

190

180 -

170 I I I

DEC 

1991

JAN 

1992

FEE MAR APR MAY JUNE JULY AUG

EXPLANATION

D GS-1A,0-80ft

A GS-18,80-200 ft

+ GS-2, 0-200 ft

X GS-3, 0-200 ft

O GS-4A, 0-55 ft

T GS-4B, 55-80 ft

H GS-4C, 80-200 ft

GS-5, 0-200 ft

GS-6, 0-400 ft 

GS-7, 0-200 ft 

GS-8B, 76-200 ft 

CAMANCHE RESERVOIR 

MINE RUN RESERVOIR

Figure 6. Fluctuations in water levels in Camanche Reservoir, Mine Run Reservoir, and in wells at the Penn 

Mine. A. Water levels for Camanche Resevoir, Mine Run Reservoir, and wells GS-1 through GS-8. B. 

Water levels for Camanche Reservoir and wells GS-4A, GS-5, GS-6, and GS-7 shown at an expanded scale. 

Water levels for GS-8A are the same as the levels in GS-4A. Data for Camanche Reservoir from East Bay 

Municipal Utility District (written commun., 1993).

capacity (Q/s) commonly has been used to estimate 

aquifer transmissivity in alluvial systems assuming a 

linear relation. Huntley and others (1992) found that 

Q/s in fractured rock systems was related to T as a 

log function, with a potential error of about 1.1 log 

cycles:

T = 0-2902/s) 1 -18. (2)

Values for transmissivity and hydraulic conductivity 

calculated by this method also are given in table 1 

and generally are within one order of magnitude of

14 Hydrogeology and Geochemistry of Acid Mine Drainage In Ground Water, Penn Mine and Camanche Reservoir
Ul 

HI

192

190

188

186

CO 

UJ

o

OQ 

<

ti 

UJ 

LL

Z 184

HI 

UJ 

DC 

P

182

180 

178

DEC 

1991

JAN 

1992

FEB MAR

B

Figured. Continued.

APR MAY JUNE JULY AUG

values estimated using the Cooper-Jacob straight-line 

method. The Huntley specific-capacity method 

consistently yields lower values for T and K, which 

may better represent actual conditions in lowpermeability systems.

The mean hydraulic conductivity (K) for the 

metavolcanic unit from both methods was about 10 to 

50 times higher than in the slate unit. The median 

value of K from both methods was 0.1 ft/d in the 

metavolcanic unit. The median value of K 

determined for the slate unit ranged from 0.002 

(Huntley method) to 0.01 ft/d (Cooper-Jacob method).

WATER LEVELS

Ground-water levels for USGS wells at the Penn 

Mine during December 1991 to August 1992 are 

given in table 2. Water-level data were collected at 

each of the eight borehole sites (GS-1 through -8). 

Inflatable packers were installed at three sites (GS -1, 

-4, and -8) to isolate fracture zones of interest. The

remaining boreholes represent average water-level and 

water-quality conditions over the entire length of open 

boreholes. Water-level altitudes were consistently 

higher in the slate than in the overlying metavolccnic 

rock at individual well sites where packers separate 

the rock types. This observation can be explained by 

a recharge source for the slate at a higher altitude 

than the metavolcanic rock. Figure 6 shows fluctuations in water-level altitudes for the wells during 

December 1991 to August 1992. Altitudes are 

highest in wells near Mine Run Dam during periods 

of recharge in the winter months. Water levels are 

lowest in wells near Camanche Reservoir during 

periods of dry weather (figs. 3 and 6). The 

significant declines in water-level altitudes in wells 

such as GS-1B during February and April 1992 were 

caused by the very slow recovery after pumping water 

from low-permeability intervals during water-quality 

sampling. Water-level altitudes in wells GS-4A, -5, 

and -8A are nearly identical to levels in Camanche 

Reservoir, indicating hydraulic connection. Water 

levels in these wells are apparently above the level of 

Camanche Reservoir in winter months and below resHydrogeology 15
120052'47' 120°52'«'

38°13'55"

1BO 

.191

EXPLANATION

Slag

Metavolcanic rock

Water-level contour Shows altitude of 

water level. Dashed where approximately 

located. Contour interval 10 feet. Datum 

is sea level

USGS well - Number is altitude of water 

level, in feet above sea level

Figure 7. Water levels in the metavolcanic unit 

August 1992.

ervoir level in summer months. This observation may 

be clarified by resurveying well altitudes and the 

benchmark on Mine Run Dam to confirm groundwater altitudes. Wells GS-5 and -8A yielded the 

highest hydraulic conductivities among the tested sites 

(table 1); the wells may intersect a major conduit for 

ground-water flow. Well GS-4 is near the north end

of the slag pile, and GS-5 is closest to Camanche 

Reservoir to the northwest. Well GS-8A is about 100 

ft south of GS-4 (fig. 3).

Water-surface altitude in Camanche Reservoir was 

about 180 ft above sea level during low stage in JuneAugust 1992. Water-surface altitude in Mine Run 

Reservoir fluctuated between about 245 and 250 ft 

above sea level during the same period. Groundwater levels in wells GS-1 through -8 lie between 

180 and 220 ft above sea level; the general hydraulic 

gradient during the study period was from Mine Run 

Reservoir through the ground-water system to 

Camanche Reservoir.

Water-level altitudes in the metavolcanic unit are 

contoured in figure 7. Formation-specific data were 

used for sites GS-1, -4, and -8. Water elevations for 

the other sites were measured in wells that penetrate 

metavolcanic rock and slate over the length of the 

borehole (figs. 3 and 7). Water levels in boreholes 

that penetrate units of contrasting permeability 

normally reflect the unit of highest permeability. 

Consequently, water levels in boreholes penetrating 

metavolcanic rock and slate were assumed to 

represent hydraulic conditions in the metavolcanic 

rock, which generally has a much higher permeability.

The average hydraulic gradient is toward the west 

over most of the study area. The primary flow path 

seems to be to the northwest in the northern half of 

the study area. The general direction of ground-water 

flow is shown in cross section in figure 4. The 

orientation of the acid-mine-drainage plume, described 

in the following section, is toward the northwest and 

originates near the northern section of Mine Run 

Dam. When the level in Camanche Reservoir rose 

above an altitude of about 182 ft above sea level in 

March 1992, the hydraulic gradient apparently 

reversed direction, indicating flow from Camanche 

Reservoir to the ground-water system.

GEOCHEMISTRY 

RESULTS OF SAMPLING

Water-quality data for January, February, April, 

and December 1992 are summarized in table 3. 

Zones of low permeability in wells with packers may 

produce samples that do not represent ambient 

ground-water quality prior to drilling because of 

contamination that cascaded downward from fractures 

in the overlying metavolcanic rock prior to installation of the packers. Conversely, samples collected

16 Hydrogeology and Geochemistry of Acid Mine Drainage In Ground Water, Penn Mine and Camanche Reservoir
Table 3. Water-quality data for Mine Run Reservoir and wells at the Penn Mine

[State well number: All wells are in 4N/10E, township and range. MRR, Mine Run Reservoir. °C, degrees Celsius; ft, foot; 

US/cm, microsiemens per centimeter; mg/L, milligram per liter; mV, millivolts; ug/L, microgram per liter: <, actual value is 

less than value shown; , no data]

Well 

name

GS-1A

OS-IB

GS-2

GS-3

GS-4A

GS-4B

GS-4C

GS-5

GS-6

GS-7

GS-8A

GS-8B

MRR-A5

MRR-A6

MRR-BS

State 

well 

No.

4G1A

4G1B

4G2

4G3

4G4A

4G4B

4G4C

4G5

4G6

4G7

4G8A

4G8B

Date

1-29-92

4-17-92

12-15-92

2-03-92

4-18-92

1-28-92

4-14-92

1-30-92

4-15-92

12-19-92

4-16-92

4-16-92

1-31-92

4-16-92

12-15-92

2-03-92

4-18-92

1-27-92

4-13-92

12-18-92

1-29-922

1-29-923

4-15-924

4-15-924

1-28-92

4-14-92

1-31-92

4-14-92

12-04-92

2-03-92

4-17-92

12-22-92

12-22-92

12-22-92

Depth 

of 

well, 

total 

(ft)

80

80

80

200

200

200

200

200

200

200

55

55

80

80

80

200

200

201.5

201.5

201.5

401

401

401

401

202

202

76

76

76

200

200

-

-

Specific 

conductance 

(US/cm)

5,060

4,950

4,980

5,200

5,980

1,430

1,810

5,190

4,600

5,660

2,430

2,430

«K

3,120

3,360

3,440

4,380

3,730

3,430

4,300

11,430

14,000

18,000

18,000

3,150

2,390

6,900

5,660

6,230

5,540

6,200

8,000

8,000

9,300

pH water 

whole 

field 

(standard 

units)

5.8

5.1

4.6

6.7

7.2

7.6

7.8

4.7

4.8

5.1

5.7

5.7

5.6

6.6

6.2

6.7

7.3

5.6

5.4

4.6

4.1

4.5

4.2

4.1

4.7

4.9

3.7

3.7

3.8

4.1

4.3

2.8

2.8

2.8

Redox 

potential 

(mV)1

-.

460

499

__

263

__

319

__

451

446

387

387

400

428

293

438

467

_

484

484

__

565

__

500

432

_

420

686

-

728

Temperature, 

water (°Q

18.5

18.0

18.5

18.5

18.5

18.5

18.5

19.5

19.5

19.5

18.5

18.5

16.0

19.0

16.5

19.0

19.0

17.5

17.5

18.0

16.5

17.5

18.5

18.5

18.5

18.5

18.0

18.5

18.0

16.5

18.5

14.0

14.0

13.5

Oxygen 

dissolved 

(mg/L)

0.8

0.2

0.9

0.9

0.8

1.7

0.2

__

2.0

_

0.3

0.5

0.5

0.5

0.1

0.5

0.3

1.0

1.9

0.2

0.2

..

4.7

4.7

3.9

Calcium, 

dissolved 

(mg/L)

540

480

470

540

480

72

72

480

440

510

210

200

380

360

390

360

380

440

360

430

520

570

560

600

390

300

510

480

440

550

460

430

280

..

Magnesium, 

dissolved 

(mg/L)

350

350

400

320

260

38

34

600

550

690

260

240

290

250

310

280

270

390

320

380

430

380

290

270

250

170

540

580

620

350

460

810

450

Sodium, 

dissolved 

(mg/L)

370

280

270

410

810

180

320

57

57

100

29

31

110

83

63

150

360

48

49

62

1,200

1,700

3,200

3,100

38

28

54

60

64

190

390

73

45

..

Footnotes at end of table.

Geochemistry 17
Table 3. Water-quality data for Mine Run Reservoir and wells at the Penn Mine-Conflnued

Well 

name

GS-1A

OS-IB

GS-2

GS-3

GS-4A

GS-4B

GS-4C

GS-5

GS-6

GS-7

GS-8A

GS-8B

MRR-A5

MRR-A6

MRR-B5

State 

well

No.

4G1A

4G1B

4G2

4G3

4G4A

4G4B

4G4C

4G5

4G6

4G7

4G8A

4G8B

Footnotes at end

Date

1-29-92

4-17-92

12-15-92

2-03-92

4-18-92

1-28-92

4-14-92

1-30-92

4-15-92

12-19-92

4-16-92

4-16-92

1-31-92

4-16-92

12-15-92

2-03-92

4-18-92

1-27-92

4-13-92

12-18-92

1-29-922

1-29-923

4-15-924

4-15-924

1-28-92

4-14-92

1-31-92

4-14-92

12-04-92

2-03-92

4-17-92

12-22-92

12-22-92

12-22-92

of table.

Potassium, 

dissolved 

(mg/L)

13

11

10

14

18

4.9

5.5

4.9

3.9

5.8

2.7

2.7

3.5

2.8

2.7

4.9

7.6

7.0

6.4

6.3

13

17

19

20

3.7

3.1

2.7

2.6

2.3

6.5

9.1

<.10

1.4

Sulfate, 

dissolved 

(mg/L)

3,500

3,500

3,700

3,300

3,000

370

450

3,700

3,700

4,400

1,400

1,500

2,100

2,100

2,300

2,000

2,200

1,400

2,900

2,900

4,400

4,800

4,000

2,900

2,300

1,700

5,400

5,900

5,700

4,500

4,400

8,500

4,800

-

Chloride, 

dissolved 

(mg/L)

120

97

78

200

570

130

240

22

21

36

8.1

9.2

100

54

26

93

320

15

16

25

1,800

2,800

4,100

5,000

27

20

20

60

51

320

290

38

22

Fluoride, 

dissolved 

(mg/L)

1.2

1.5

1.3

1.5

.90

.20

.20

2.1

.30

.40

<.10

.10

.30

.20

.20

.80

.30

.80

.20

.30

3.5

6.5

2.8

3.2

1.5

.80

2.0

9.8

4.8

3.5

6.4

.40

.90

Bromide, 

dissolved 

(mg/L)

1.9

.88

.39

2.9

4.5

1.8

1.6

.15

.10

.15

.26

.27

4.6

1.3

.24

5.7

1.3

.28

.22

.13

13

5.1

8.3

6.5

.50

.39

.31

.32

.48

3.4

3.9

1.9

.94

Silica, 

dissolved 

(mg/L)

35

42

47

29

13

18

16

71

59

72

42

42

33

32

37

30

22

22

41

44

43

38

34

35

51

38

100

110

120

60

48

190

130

Solids, 

residue 

at 180 °C, 

dissolved 

(mg/L)

5,750

5,580

5,540

5,760

6,090

992

3,750

5,930

5,290

6,590

2,320

2,340

3,390

3,190

3,510

3,410

3,870

1,970

3,840

4,320

11,000

12,400

15,000

14,500

3,620

2,610

8,470

9,020

8,670

7,700

7,530

13,200

3,820

Aluminum, 

dissolved 

(ug/L)

570

3,800

10,000

30

30

<10

<10,

6,900

4,800

3,800

40

50

<10

20

60

<10

30

270

240

3,800

37,000

63,000

52,000

51,000

9,100

3,600

240,000

220,000

250,000

81,000

89,000

720,000

280,000

Cadium, 

dissolved 

(ug/L)

1,600

2,100

2,300

1,400

440

<10

<10

3,600

2,600

3,700

1,100

1,000

630

530

900

670

520

2,900

3,000

2,900

1,200

1,000

680

690

970

630

1,600

1,400

1,500

1,200

970

1,700

940

18 Hydrogeology and Geochemistry of Acid Mine Drainage In Ground Water, Penn Mine and Camanche Reservoir
Table 3. Water-quality data for Mine Run Reservoir and wells at the Penn Mine-Conf/nued

Well 

name

GS-1A

GS-1B

GS-2

GS-3

GS-4A

GS-4B

GS-4C

GS-5

GS-6

GS-7

GS-8A

GS-8B

MRR-A5

MRR-A6

MRR-B5

State 

well

No.

4G1A

4G1B

4G2

4G3

4G4A

4G04B

4G4C

4G5

4G6

4G7

4G8A

4G8B

Date

1-29-92

4-17-92

12-15-92

2-03-92

4-18-92

1-28-92

4-14-92

1-30-92

4-15-92

12-19-92

4-16-92

4-16-92

1-31-92

4-16-92

12-15-92

2-03-92

4-18-92

1-27-92

4-13-92

12-18-92

1-29-922

1-29-923

4-15-924

4-15-924

1-28-92

4-14-92

1-31-92

4-14-92

12-04-92

2-03-92

4-17-92

12-22-92

12-22-92

12-22-92

Copper, 

dissolved 

(Hg/L)

3,000

9,800

13,000

2,400

<10

<10

<10

15,000

12,000

11,000

1,100

1,100

160

130

400

230

30

2,500

2,600

6,100

4,000

70

12,000

13,000

21,000

14,000

84,000

86,000

88,000

10,000

5,400

110,000

62,000

Iron, 

dissolved 

(Mg/L)

150

160

1,900

30

<10

5

<10

60

60

80

<10

<10

30

20

10

10

<10

190

130

3,200

240,000

220,000

930

950

1,200

100

120,000

110,000

150,000

88,000

94,000

160,000

110,000

-

Lead, ManSadis- nf.se' 

solved &s- «*« ss

<1 24,000

<1 27,000

<1 33,000

2 24,000

<1 20,000

<1 75

<1 70

<1 29,000

<1 25,000

<1 38,000

<1 980

<1 850

4 480

<1 260

<1 120

<1 690

<1 790

<1 1,900

<1 1,900

<1 4,600

24 33,000

18 27,000

4 24,000

4 25,000

<1 29,000

<1 23,000

<1 52,000

<1 58,000

<1 52,000

18 44,000

7 44,000

<1 51,000

7 28,000

-

Silver, Zinc, 

dis- dissolved solved 

(Hg/L) (ng/L)

<1.0 110,000

<1.0 140,000

<1.0 190,000

<1.0 83,000

<1.0 18,000

<1.0 47

<1.0 20

<1.0 170,000

<1.0

<1.0 250,000

<1.0 39,000

<1.0 34,000

<1.0 16,000

<1.0 12,000

<1.0 26,000

<1.0 17,000

<1.0

<1.0 72,000

<1.0 78,000

<1.0 94,000

<1.0 310,000

<1.0 290,000

<1.0 120,000

<1.0 170,000

<1.0 150,000

<1.0 83,000

<1.0 430,000

<1.0

<1.0 470,000

<1.0 300,000

<1.0 300,000

<1.0 570,000

<1.0 200,000

8D 

(per 

mil)

..

-36.5

-37.4

__

-40.0

__

-56.0

__

-35.0

-32.1

-51.5

-50.0

-48.5

-46.5

__

-48.5

._

-46.5

-42.9

 _

-35.0

-33.0

-58.0

-32.5

-33.9

__

-38.0

-8.4

-25.4

-3.6

8180 

(per 

mil)

-3.40

-3.31

-3.85

__

-7.65

__

-3.45

-2.32

-6.60

-6.65

__

-6.30

-6.01

__

-6.25

__

-5.40

-5.04

__

_

-2.90

-2.90

 _

-8.20

-2.65

-2.61

_.

-3.85

2.55

-2.12

3.78

'Redox potential relative to the standard hydrogen electrode potential (Eh), measured using a platinum electrode with 

quinhydrone standard redox buffers, as described by Makita and Fujii (1992). 

2Sample collected at depth of 50 feet. 

3Sample collected at depth of 160 feet. 

4Replicate samples collected at depth of 90 feet. 

5Six feet below water surface. 

'One foot below water surface.

Geochemistry 19
for upper intervals of open boreholes may contain 

water derived from the underlying slate unit. The 

purge logs (appendix 3) indicate that more than three 

well volumes were purged from two of the more 

permeable intervals (GS-4B and -8A) and that more 

than one well volume was purged for several others. 

Deep intervals and open boreholes generally yielded 

less than one well volume during purging in response 

to slow recovery of water levels and low pumping 

rates (appendix 3). In all cases, the field properties 

(pH, specific conductance, temperature, and redox 

potential) had stabilized in the flow-through cell prior 

to sampling.

Preliminary sampling done in December 1991 

showed the effects of materials introduced to the 

wells during vandalism in November 1991 and the 

subsequent airlifting to clean and purge the wells. 

Aeration of well water can change water quality, 

particularly elements (for example, iron) involved in 

redox reactions. Data from sampling in December 

1991 are not shown in table 3 because they are less 

representative of water-quality properties prior to 

drilling when compared with subsequent samples. 

Specific conductance in December 1991 ranged from 

1,860 uS/cm (microsiemens per centimeter at 25°C) 

at well GS-2 (60-foot depth below land surface) to 

12,400 uS/cm at well GS-6 (280-foot depth below 

land surface). The pH of purged water ranged from 

4.6 at well GS-8 (160-foot depth below land surface) 

to 8.9 at GS-3 (145 ft below land surface). The high 

pH value at GS-3 resulted from the presence of cement (dry mortar mix) poured into the well during 

vandalism. Temperatures ranged from 12.5°C at well 

GS-2 to 23.5°C at well GS-7. Relatively high concentrations of dissolved bromide in several wells indicated the presence of water used during drilling and 

injection tests. The introduced waters were spiked 

with sodium bromide to yield a bromide concentration 

of about 100 mg/L. Bromide concentration was 

highest (15 mg/L) in water from well GS-2.

The samples collected during January-February 

1992 represent conditions closer to natural ground 

water than the December 1991 samples. The JanuaryFebruary 1992 samples were collected using a 

submersible pump. Multiple intervals were sampled 

at sites equipped with inflatable packers (GS-1, -4, 

and -8). Specific conductance ranged from 1,430 

uS/cm at well GS-2 to 14,000 uS/cm at well GS-6. 

The pH of ground water ranged from 3.7 at well 

GS-8A to 7.6 at well GS-2. Water temperature 

ranged between 16.0°C at well GS-4B to 19.5°C at 

well GS-3 (table 3).

Analytical results from sampling during April 1992 

provide the most comprehensive available representation of ground-water quality. Values for specific 

conductance ranged from 1,810 uS/cm at well GS-2 

to 18,000 uS/cm at well GS-6. The pH of sampled 

water ranged from 3.7 at well GS-8A to 7.8 at well 

GS-2. Water temperatures ranged from 17.5°C at 

well GS-5 to 19.5°C at well GS-3. The results of 

stable-isotope analysis indicate that ground water has 

been evaporated to a variable degree (table 3). These 

results are discussed later in this section. As part of 

the quality-control program, a field equipment blank 

was run through the sampling process, including 

filtration and preservation. Nearly all properties 

determined in the field blank were less than detection 

limits. Calcium, magnesium, chloride, and'iron were 

present at concentrations near their detection limits.

Comparison of water-quality data for April and 

December 1992 (table 3) indicates transient behavior 

consistent with a mobile contaminant plume. Water 

from all wells measured during these months (GS-1 A, 

-3, -4A, -5, and -8A) showed an increase in specific 

conductance. During the same period, water from 

three of five wells showed a decrease in pH and an 

increase in dissolved copper concentration. Rising 

specific conductance and copper and falling pH reflect 

a higher proportion of acid drainage in ground water. 

These data and the data on water levels (table 2; fig. 

6) are consistent with the interpretation that a plume 

of acid drainage in ground water in the vicinity of 

wells GS-1 and GS-3 was migrating toward 

Camanche Reservoir during this period. Water-level 

data for wells GS-4A, -5, and -8A indicate that 

hydraulic heads in these three wells are very close to 

the altitude of the surface of Camanche Reservoir, 

making interpretation of water-quality trends for these 

wells more difficult. More data are needed for water 

levels and water quality for these wells to interpret 

the transient behavior of the contaminated plume in 

that area.

GENERATION OF ACID MINE DRAINAGE

Oxidation of sulfide minerals produces low values 

of pH in water draining or pumped from many coal 

and metal mines (Hem, 1985). The volume of acid 

mine drainage can be large and may continue long 

after mining operations have ceased. Typical characteristics of acid mine drainage include low pH and 

high concentrations of iron, aluminum, and sulfate 

(Todd, 1980). Pyrite generally is slow to oxidize 

below the water table in circum-neutral waters with 

low concentrations of dissolved oxygen and ferric 

iron. However, exposure of pyrite to air and water

20 Hydrogeology and Geochemistry of Acid Mine Drainage In Ground Water, Penn Mine and Camanche Reservoir
produces sulfuric acid solutions that readily dissolve 

base-metal sulfides and other minerals. The complete 

oxidation of pyrite at near-neutral to weakly acid (pH 

4 to 7) conditions can be summarized by the 

following reaction (Alpers and Nordstrom, 1991):

m(OH)'3(s>

2- (3)

At pH values less than 4, ferric iron can act as the 

direct oxidant of pyrite:

FeS2+14Fe ^

2+ 2~

+2SO4 ~+16H *.

The latter reaction (equation 4) is fast (McKibben and 

Barnes, 1986), but its rate is limited in an abiotic 

system because the reoxidation of iron from ferrous 

to ferric by oxygen is extremely slow at pH values 

less than 4. However, the catalytic effect of the ironoxidizing bacterium Thiobacillus ferrooxidans speeds 

up the rate of the reaction

Fe 2++l/4O2+H ' (5)

by five to six orders of magnitude over the abiotic 

rate (Nordstrom, 1985). The rate of regeneration of 

ferric iron (equation 5) is about three orders of 

magnitude greater than the rate of pyrite oxidation by 

ferric iron (equation 4). In the presence of abundant 

bacteria, equation 4 is the rate-determining step in the 

production of acid mine drainage (Singer and Stumm, 

1970). Combining equations 4 and 5, an acidic 

ferrous-sulfate solution is produced by the oxidation 

of pyrite according to the reaction

FeS 2~ + +2SO4 ~+2H +.

The resulting acidic solution will attack other metalsulfide minerals, such as chalcopyrite and sphalerite. 

Percolation of acid mine drainage to ground water 

will lower pH and raise concentrations of metals and 

sulfate. Metals with elevated concentrations in 

ground water and surface water at the Perm Mine 

include aluminum, cadmium, copper, iron, and zinc. 

These dissolved constituents most probably are 

derived from oxidation of sulfide minerals and 

dissolution of associated aluminosilicate minerals in 

waste-rock piles exposed at several locations on the 

properties of New Penn Mines, Inc., and the Utility 

District (fig. 2). Another possible source of these 

constituents can be from dissolution of soluble sulfate

minerals in the bedrock adjacent to the underground 

mine workings. In addition, the slag materials 

exposed near Camanche Reservoir contain high 

concentrations of zinc, which averaged 6.5 percent by 

weight in 8 bulk samples (Wiebelt and Ricker, 

1948). Slag, when exposed to acid ground water, can 

be a source of metals, particularly zinc and cadmium.

Determinations of dissolved aluminum are 

complicated by its tendency to form particulate 

material (colloids) that pass through the standard filter 

membrane with 0.45-um pore diameter. Gibbsite 

[A1(OH)3], for example, forms crystals that pass 

through standard filter media. The use of 0.10-um 

filters during sampling at the Penn Mine reduced the 

amount of colloidal aluminum in filtered samples. 

Water with pH values less than 4.5 can contain 

several hundred to several thousand milligrams of 

dissolved aluminum per liter (Hem, 1985; Nordstrom 

and Ball, 1986). At the Penn Mine, dissolved 

aluminum in ground water ranged from less than 

0.010 to 250 mg/L (table 3).

Copper may be found in either the cuprous (Cu*) 

or cupric (Cu ) oxidation state, but the cupric form 

is more common in near-surface waters. In solutions 

with alkaline pH, copper hydroxycarbonates (for 

example, malachite) are slightly soluble and yield 

copper concentrations less than 10 |jg/L (micrograms 

per liter) (Hem, 1977). Adsorption or coprecipitation 

of copper with hydrous ferric oxides can result in 

lower aqueous concentrations (Hem, 1977); however, 

this process is unlikely to occur to a significant 

degree in water with pH values less than 5 (Webster 

and others, 1994). Copper may be present in 

concentrations up to a few hundred milligrams per 

liter in acid mine drainage (Hem, 1985). Values for 

dissolved copper in ground water from the Penn Mine 

ranged from less than 0.010 to 88 mg/L (table 3).

In aerated water, ferric iron (Fe3*) concentrations 

are not expected to exceed a few micrograms per liter 

in the pH range 6.5 to 8.5 (Hem, 1985). Like 

aluminum, the solubility of ferric iron is low at 

circum-neutral pH; higher reported concentrations of 

iron at circum-neutral pH probably result from 

colloidal iron passing through the filter membrane. 

High concentrations of dissolved ferrous iron (Fe2*) 

can occur in circum-neutral ground water having a 

low redox state. Dissolved ferrous iron is the primary 

product of pyrite oxidation (equations 4 and 6). 

Subsequent oxidation of Fe2* to Fe3* will lead to 

precipitation of Fe(ni)-bearing minerals, generally 

with lower solubility than Fe(II)-bearing minerals. 

The saturation state of ground-water samples from

Geochemistry 21
Penn Mine with respect to various iron minerals that 

can potentially control iron solubility is discussed in 

a later section. Concentrations of dissolved iron in 

ground water at the Penn Mine ranged from less than 

0.010 to 240 mg/L (table 3). Davy Environmental 

(1993) found high concentrations of iron in 

ground-water samples from the bedrock adjacent to 

the impoundments above Mine Run Dam. These high 

concentrations can be attributed to acid mine drainage 

generated by the oxidation of pyrite and other sulfide 

minerals in the surrounding waste rock.

Zinc is found in the same general abundance in 

crustal rocks as copper (Hem, 1985). However, 

aqueous zinc has only one significant oxidation state, 

Zn2+, and tends to be somewhat more soluble than 

copper in water. Under neutral-to-alkaline conditions, 

the equilibrium concentration of zinc is expected to be 

less than 0.1 mg/L in most cases. Water affected by 

acid mine drainage generally contains substantially 

higher concentrations of zinc. Dissolved zinc in 

ground water from the Penn Mine ranged from 0.020 

to 470 mg/L (table 3).

Cadmium is found with zinc in most crustal 

environments, including the sulfide minerals sphalerite 

and tetrahedrite-tennantite. The ratio of zinc to 

cadmium is commonly on the order of 50 to 500 in 

massive sulfide deposits and associated mine drainage 

(D.K. Nordstrom, oral commun., 1992). Dissolved 

concentrations of cadmium in ground-water samples 

from Penn Mine ranged from less than 0.010 to 3.7 

mg/L (table 3). Ratios of zinc to cadmium for the 

data in table 3 range from 11 to 335 with a median 

value of 69.

DISTRIBUTION OF ACID MINE DRAINAGE

Several water-quality properties were contoured in 

cross-section and map views to delineate the extent of 

acid mine drainage in ground water at the Penn Mine. 

Distributions of aluminum, iron, sulfate, oxygen 

isotopes, and pH for the April 1992 sampling were 

evaluated in this manner. The vertical distribution of 

chloride also was evaluated. Along cross section 

B-B', the major constituents of acid mine drainage 

show similar distributions, indicating that the 

acid-mine-drainage plume in April 1992 was 

concentrated in the metavolcanic unit. The distribution of sulfate in borehole GS-4, however, shows 

slightly elevated sulfate concentration with depth, 

apparently the result of lateral migration of high sulfate water along the metavolcanic-slate contact (fig. 

8). Sulfate concentration generally decreases with

depth and decreases toward the northern and southern 

ends of section B-B' (fig. 8). The distribution of 

chloride shows the reverse trend and increases with 

depth (fig. 9). Within individual wells with multiple 

intervals separated by inflatable packers, chloride 

concentration was always highest in the underlying 

slate unit (fig. 9; table 3). In the 200-foot boreholes, 

chloride ranged from 93 to 570 mg/L in the slate 

intervals and from 8 to 100 mg/L in the metavolcanic 

rock intervals. The highest concentration of chloride, 

5,000 mg/L, was found in the 400-foot borehole 

(GS-6), which penetrated more than 300 ft of the slate 

unit. This indicates that the source of chloride is 

associated with the slate unit.

The distributions of major acid-mine-drainage 

constituents in map view are similar to the 

distribution of sulfate shown in figure 10. The acid 

mine drainage is derived from a source in or near the 

metavolcanic unit along the north abutment of Mine 

Run Dam. Most subsurface flow is in a northwesterly 

direction along the strike of the geologic contact (fig. 

5) from the dam toward Camanche Reservoir. A 

component of flow to the southwest correlates with 

the interpreted fault (fig. 5) and the water-level 

contour map (fig. 7). Some of the acid mine drainage 

may preferentially follow the strike of this fault, 

which, apparently tends to have a high permeability 

along its strike in contrast to surrounding materials. 

In a study done by the Department of Energy in 

Tennessee, ground-water flow was found to follow 

the geologic strike in a fractured bedrock aquifer (Lee 

and others, 1992). A tracer used in that study helped 

to determine that flow was controlled primarily by 

geologic strike and not by maximum hydraulic 

gradient. The highest concentrations of sulfate are 

associated with low values of pH (fig. 11). The 

plume also is delineated by lines of equal pH values 

in the ground water (fig. 12). Values for pH in most 

wells along the axis of the plume measured in 

December 1992 were lower than values in April 1992. 

This is consistent with the plume migrating 

downgradient toward Camanche Reservoir. The most 

acidic value recovered for pH in ground water in the 

study area is 3.7 (table 3). Values of pH in MineRun Reservoir, the inferred source region, range from 

2.3 to 2.8 (Bond, 1988; Davy Environmental, 1993; 

this report, table 3).

Another way to delineate the extent of acid mine 

drainage in ground water is by the distribution of the 

stable isotopes deuterium [D or hydrogen-2 ^H)] and 

oxygen-18 (18O). The most abundant isotopes that 

constitute the water molecule are 18O, oxygen-16 

(16O), 2H, and hydrogen-1 (1H). The heavy isotopes

22 Hydrogeology and Geochemistry of Acid Mine Drainage In Ground Water, Penn Mine and Camanche Reservoir
B'

Sea level

so

VERTICAL EXAGGERATION X1.5 

100 FEET

I 

15

I 

30 METERS

EXPLANATION

 Contact - Dashed where inferred

 i£ Inferred fault Arrows indicate relative movement

 3,000 Line of equal sulfate concentration-Dashed where 

approximate. Interval 1,000 milligrams per liter

GS-8

A

- Borehole number

- Borehole packer

5,900 Sulfate concentration, in milligrams per liter, 

at indicated depth

 Interval of open fractures from flow-meter testing

-Bottom of hole

Figure 8. Distribution of sulfate with depth along geologic section B-fi' at the Penn Mine, April 1992.

18O and 2H exist naturally in average proportions of 

0.2 percent of the oxygen and 0.07 percent of the 

hydrogen in water molecules. Ratios of the heavy to 

light isotopes, R, are expressed in delta units (8), 

which are parts per thousand (per mille) differences 

relative to an arbitrary standard known as standard 

mean ocean water (V-SMOW) (O'Neill, 1986).

M(/?-/?std)//?Jx 1,000, (7)

where R and RM are the isotope ratios (D/H or 

18O/16O) of the sample and standard, respectively. 

Relative concentrations of 2H and 18O, expressed as 

8D and 818O, generally correlate linearly. Graphic

Geochemistry 23
B

B'

Sea level

50

VERTICAL EXAGGERATION X1.5 

100 FEET

15 30 METERS

GS-8

EXPLANATION

Contact Dashed where inferred

Inferred fault - Arrows indicate relative movement

-Borehole number

- Borehole packer

- Chloride concentration, in milligrams per liter, 

at indicated depth (mean value of available data)

- Interval of open fractures from flow-meter testing

 Bottom of hole

Figure 9. Distribution of chloride with depth aiong geologic section fi-fi' at the Penn Mine, Aprii 1992.

representation of this relation for global precipitation 

data produces a straight line known as the meteoric 

water line, defined by

8D=88180 + 10, 

(Craig and others, 1963).

(8)

24 Hydrogeology and Geochemistry of Acid Mine Drainage In Ground Water, Penn Mine and Camanche Reservoir
120°52'47' 

38013'59"

120°52'42-

38°13'55-

60 METERS

1,000 

1,700

EXPLANATION 

Slag 

Metavolcanic rock

Line of equal sulfate concentration -

Queried where uncertain. Interval 

1,000 milligrams per liter

USGS well Number is sulfate concentration, 

in milligrams per liter

Figure 10. Distribution of sulfate in ground water 

at the Penn Mine, April 1992.

During the evaporation process, water molecules 

containing heavy isotopes tend to become concentrated in the residual water, whereas molecules 

containing lighter isotopes become enriched in the 

water vapor. Hence, isotopic values for bodies of 

surface water exposed to evaporation tend to be enriched in heavy isotopes relative to most ground 

water. The process of isotopic evaporative enrichment produces data that lie on a line with a slope 

between 3 and 6 on a plot of 8D and 818O, to the 

right of the meteoric line (Craig and others, 1963).

10.00O

oc

ffi

a.

<3 

d 1.000

2

I

100 

3

1 1 1 1 1 1 1 1

: ° - & '-

A V

* x n n

^ K A -

 v VH H

* *

' -

+ ' 

+ '

i i i i i i i i

.5 4 4.5 5 5.5 6 6.5 7 7.5 6

PH

EXPLANATION

D GS-1A

A OS-IB

+ GS-2

X GS-3

O GS-4A

V GS-4B

H GS-4C

K GS-5

$ GS-6

 GS-7

O GS-8A

 GS-8B

Figure 11 . Variation of sulfate concentration with 

pH in ground water from the Penn Mine, April 

1992.

This phenomenon is observed in a plot of isotope data 

from ground water and Mine Run Reservoir at the 

Penn Mine (fig. 13). The data can be fit by leastsquares linear regression (r*=Q.9&5), which gives a 

line described by the equation

8D = 4.4 818O - 21. (9)

The slope of this line indicates that the ground-water 

downgradient from Mine Run Dam represents the 

mixing of evaporated water from Mine Run Reservoir 

with nonevaporated ground water. This interpretation 

suggests that the source of dissolved metals and 

sulfate in the ground water is leakage from the 

unlined Mine Run Reservoir. Wells GS-2 and -7 

show the least enrichment in heavy isotopes and 

exhibit the lowest levels of contamination by acid 

mine drainage. Samples from Mine Run Reservoir 

and wells GS-3, -6 and -8A show the highest enrichment in heavy isotopes and highest levels of acidmine-drainage contamination. The aerial distribution 

of the evaporated ground-water plume is delineated by 

818O in figure 14. The stable-isotope composition of 

ground water probably results from mixing nonGeochemistry 25
120°52'46" 

38°14'00"

120°52'40"

38°13'54"

Camanche 

Reservoir

Camanche 

Reservoir

/Mine Run 

/Reservoir

/MineRun 

y Reservoir

'

30 60 METERS

V/7A

 6 

EXPLANATION

Waste rock

Wastewater impoundment

Line of equal pH Dashed where approximately located; queried where uncertain. 

Interval 1 unit

USGS well - Number is pH value April 1992

USGS well - Number is pH value December 

1992. Parentheses indicate pH value prior 

to December 1992

Figure 12. Distribution of pH in ground water at the Penn Mine. A, April 1992. B, December 1992.

evaporated ground water with evaporated acid mine 

drainage from the retention pond.

GEOCHEMiCAL CORRELATIONS

Correlations among dissolved constituents indicate 

the effects of acid mine drainage on ground-water 

quality at the Penn Mine. Dissolved iron and sulfate 

show a weak positive correlation in ground water,

consistent with oxidation of pyrite as the probable 

source of these constituents (fig. 15). Other 

constituents show similar correlations, particularly 

with pH. Lower pH values in ground water are 

associated with higher concentrations of dissolved 

constituents such as sulfate (fig. 11), aluminum, iron, 

and other dissolved metals.

The distribution of dissolved iron species is controlled by the pH and Eh of the ground water. The

26 Hydrogeology and Geochemistry of Acid Mine Drainage In Ground Water, Penn Mine and Camanche Reservoir
-14 -12 -10 

DELTA OXYGEN-16, IN PARTS PER THOUSAND

EXPLANATION

Ground Water

O GS-1A X GS-5 

+ GS-2 $ GS-6 

X GS-3 GS-7 

O GS-4A O GS-8A 

V GS-4B GS-8B 

H GS-4C

Mine Run Reservoir 

$ MRR-1 foot below water surface 

Q MRR-6 feet below water surface

120°52'47'

_ Camanche 

==S=^L Reservoir

120°52'42-

38°13'55-

I

c 

r£

I

S

100 200 FEET r^

30 60 METERS

Figure 13. Stable-lsotopic composition of ground 

water and Mine Run Reservoir at the Penn Mine, 

April and December 1992.

Eh of an aqueous solution is a measure of the 

intensity of oxidizing or reducing (redox) conditions 

within a system with the hydrogen-electrode potential 

serving as a reference point of zero volts. A platinum 

electrode was used in the flow chamber during water 

sampling to measure the field potential of the ground 

water in volts. This determination was later converted to Eh. The pH-Eh relations of aqueous solutions can predict and define the equilibrium behavior 

of multivalent elements. Positive potentials indicate 

that the system is relatively oxidizing, and negative 

potentials indicate that the system is relatively 

reducing. Redox potentials calculated from Eh values 

determined for ground water at the Penn Mine were 

all positive, ranging from 263 mV (millivolts) at well 

GS-1B to 565 mV at well GS-7. Values for redox 

potential are included in table 3.

Analytical determinations of dissolved ions presented in this report are for total concentrations and 

do not describe the aqueous species present. For 

example, a determination of total dissolved iron 

would not define the amounts of ferrous and ferric

-7.6

EXPLANATION

Slag

Metavolcanic rock

Line of equal delta oxygen-18 value ~ Dashed 

where approximately located; queried where 

uncertain. Interval 1 permil

USGS well- Number is delta oxygen-18 value in 

permil(V-SMOW)

Figure 14. Distribution of delta oxygen-18 in 

ground water at the Penn Mine, April 1992.

iron in solution. Total and ferrous iron in solution 

can be determined analytically; the difference between 

the two is dissolved ferric iron. Iron species also may 

be determined theoretically from total iron 

concentrations using the Eh and pH of the solution. 

In this study, the chemical model WATEQ4F (Ball 

and Nordstrom, 1991) was used to determine 

dissolved species and their activities based on known 

thermodynamic data. The activity of a chemical

Geochemistry 27
10,000

1,000

z

VV

CORRELATION COEFFICIENT= 0.644

100 

0.001 0.01 0.1 1 10 100 1.000

IRON. IN MILLIGRAMS PER LITER

EXPLANATION

n GS-1A H GS-4C

A GS-1B X GS-5

+ GS-2 $ GS-6

X GS-3 GS-7

O GS-4A O GS-8A

V GS-4B GS-8B

Figure 15. Variation of iron with sulfate 

concentations in ground water from the Penn 

Mine, April 1992.

species is related to its analytical concentration by an 

aqueous activity coefficient, gamma (y)

a = ym, (10)

where a is the chemical activity and m is the 

analytical concentration in molality (moles/kg H2O). 

Aqueous activity coefficients are primarily dependent 

on the effective ionic strength of the aqueous 

solution; as total concentrations of species decreases, 

activity coefficients tend to approach unity. Because 

aqueous activities commonly are small numbers and 

range over several orders of magnitude, they generally 

are expressed as log values.

The concentrations of certain metals in natural 

waters may be controlled by solubility equilibrium 

with solid phases. If the controlling reaction contains 

the hydrogen ion, then a plot of pH against aqueous 

activity of the metal should yield a straight line with 

a slope corresponding to the stoichiometry of the 

controlling solubility reaction. The log of Fe3+ 

activity is plotted in figure 16 against pH in relation 

to solubility curves calculated for hydrous ferric oxide

3

a

s

-10

-15

-20

-25

5 

PH

EXPLANATION

GS-1A $ GS-6

X GS-3

V GS-4B

X GS-5

GS-7

GS-8A

GS-8B

Figure 16. Plot of log (Fe3+ activity) and pH with 

goethite and hydrous ferric oxide equilibrium 

values for ground water from the Penn Mine, April 

1992.

Fe(OH)3] and goethite [FeO(OH)] using thermodynamic data in WATEQ4F. With the exception of 

the lowest pH ground water from wells GS-8A and 

-8B, the water appears to be close to equilibrium with 

hydrous ferric oxide. Sulfate concentrations become 

higher at low pH (fig. 11). The deviation of data 

points in figure 16 from the hydrous ferric oxide 

curve at low pH can reflect control by an iron-sulfate 

mineral such as jarosite [(K,Na,H3O)Fe3(SO4)2(OH)6] 

(Alpers and others, 1989) or a ferric-hydroxy-sulfate 

mineral such as the newly discovered, poorly 

crystalline schwertmannite [Fe8O8(OH)6SO4] (Bigham 

and others, 1990; Murad and others, 1994), for which 

no thermodynamic data are yet available.

A similar graphical analysis was applied to 

analytical data for dissolved aluminum in ground 

water at the Penn Mine. The log of A13+ activity is 

plotted in figure 17 against pH in relation to solubility 

curves for amorphous and microcrystalline gibbsite. 

Ground water is in apparent equilibrium with crystalline gibbsite, with the exception of low pH water 

from wells GS-6, -8A, and -8B. Equilibrium with an 

aluminum-sulfate mineral can control the concentration of A13+ species in the low pH range, or there

28 Hydrogeology and Geochemistry of Acid Mine Drainage In Ground Water, Penn Mine and Camanche Reservoir
-2

-4

-6

£ "6

ra "10

-12 

-14 

-16 

-16

1

, X \ ,

o \\

*^\%

%\\

^\\

\\\ \\ \\ \\ - \\

1 1 1 1 1 1 \ \

3456769 1C 

PH

EXPLANATION

D GS-1A X GS-5

A GS-1B $ GS-6

X GS-3 GS-7

O GS-4A O GS-8A

V GS-4B GS-8B

E GS-4C

Figure 17. Plot of log (A1 3+ activity) and pH with 

gibbsite equilibrium values for ground water from 

Penn Mine, April 1992.

may be no solubility control. Nordstrom and Ball 

(1986) observed that basic aluminum-sulfate minerals 

can control aluminum concentrations in waters having 

low pH and high sulfate concentrations. They noted 

that two possible controls on the aluminum chemistry 

of acid mine drainage were (1) the leaching rate of 

aluminum from common aluminosilicate minerals in 

sulfuric acid solutions and (2) the solubility of basic 

aluminum sulfate minerals known to exist under these 

conditions. Compared to surface water, ground water 

is in contact with mineral phases for much longer 

periods; consequently, ground water is exposed to 

much larger surface areas of minerals per unit time. 

Hence, ground water is expected to exhibit an 

increasing tendency toward mineral saturation and 

equilibrium with basic aluminum sulfate phases such 

as jurbanite [A1(SO4) (OH)-5H2O] basaluminite 

[A1 4 (S04 )(OH) 10 -5H2 0], and alunite 

[KA13(SO4)2(OH)6] at low pH (Nordstrom, 1982). 

Kinetic barriers to alunite formation may lead to 

supersaturation of aqueous solutions with respect to 

this mineral under certain conditions.

FLOW RATE OF CONTAMINATED GROUND 

WATER

The flow rate of ground water in the fractured 

metamorphic-rock aquifer between Mine Run Dam 

and Camanche Reservoir can be estimated by using 

mathematical relations developed for porous media. 

According to Darcy's law, the flow rate, q, through a 

given cross-sectional area of aquifer is

q = KIA, (11)

where K is the hydraulic conductivity averaged over 

the thickness of the aquifer, / is the hydraulic 

gradient, and A is the cross-sectional area (Driscoll, 

1987). Wells GS-1 and -8 lie roughly along the axis 

of the contaminated plume (fig. 3) and parallel to the 

direction of maximum hydraulic gradient, which was 

about 0.14 in August 1992. A rough estimate of the 

width of the plume is about 300 ft based on contours 

of sulfate concentration (fig. 10). The primary fractures that transport ground water are in a 10-foot-thick 

zone associated with the metavolcanic-slate contact. 

This yields a cross-sectional area for the flow path of 

approximately 3,000 ft2. The median value of hydraulic conductivity for the metavolcanic rock is 

about 0.1 ft/d (table 1). Therefore, $=(0.1 ft/d) 

(3,000 ft2) (0.14) = 42 ftVd. This is equivalent to 

about 115,000 gal/yr. Using a high value for K, 50 

ft/d, yields a discharge of about 21,000 frVd, or about 

57 million gal/yr. The actual value for q is 

proportional to the width of the plume and to the 

effective hydraulic conductivity along the flow path. 

Seasonal changes in the hydraulic gradient also will 

affect the ground-water discharge rate.

METAL LOADING TO CAMANCHE 

RESERVOIR

Using the estimates of ground-water flow along a 

path leading to Camanche Reservoir described in the 

previous section, ranges for metal transport rates can 

be estimated using values for metal concentration 

determined for the containment plume. Metal 

concentrations chosen for these estimates are 85 mg/L 

for copper, based on an average of the JanuaryFebruary and April 1992 samples from well GS-8A; 

300 mg/L for zinc, based on values from wells GS8A and -8B; and 1.5 mg/L for cadmium, based on an 

average of values for January-February and April 

1992 samples from well GS-8A (table 3).

Metal Loading to Camanche Reservoir 29
Table 4. Estimates of ground-water flow and 

metal loading to Camanche Reservoir

[Assumed concentrations in plume are 1.5 milligrams per 

liter for cadmium, 85 milligrams per liter for copper, and 

300 milligrams per liter for zinc, ft/d, foot per day; ft3/d, 

cubic foot per day; gal/yr, gallon per year; Ib/yr, pound per 

year]

Hydraulic Row Flow

conductivity rate rate

(ft/d) (gal/yr) (ftVd)

_ , .

C

'0.1 l.lSxlO5 42 1.5 

250 5.7xl07 21,000 750

86 310

42,000 150,000

'Median value of hydraulic conductivity, metavolcanic 

rock.

2High value of hydraulic conductivity, metavolcanic 

rock.

The calculated metal loadings are shown in table 4 

for median (0.1 ft/d) and high (50 ft/d) values of 

hydraulic conductivity. Because maximum values for 

metal concentrations in the contaminant plume were 

used, the metal loading estimates for the high value of 

hydraulic conductivity [copper, 42,000 Ib/yr (pounds 

per year); zinc, 150,000 Ib/yr; cadmium, 750 Ib/yr] 

can be considered "worst-case" scenarios. More 

realistic metal loading estimates can be obtained by 

consideration of the transient nature of the hydrologic 

system. In particular, the fluctuations of altitude of 

the surface of Camanche Reservoir appear to have an 

important effect on the direction of the hydraulic 

gradient, in the area of wells -4A, -4B, -5, -8A, and 

-8B. More detailed data are needed on water levels 

in these wells during and following fluctuations in 

Camanche Reservoir surface altitude to evaluate metal 

fluxes to Camanche Reservoir under transient 

ground-water conditions.

SUMMARY

The Penn Mine was active from the early 1860's to 

the late 1950's. Metals produced from the mine in 

decreasing order of abundance were copper, zinc, 

silver, lead, and gold. Surface disposal of sulfidebearing waste rock and tailings has led to formation 

of acid mine drainage with high concentrations of 

dissolved aluminum, cadmium, copper, iron, zinc, and 

sulfate. Historically, contaminated surface runoff 

from the mine flowed directly into the Mokelumne 

River. Since the construction of Camanche Dam in 

1963, contaminated runoff has flowed into Camanche 

Reservoir. In an attempt to reduce the interaction of 

mine waste with surface water, diversion channels and 

unlined impoundments were constructed and existing

impoundments were altered in 1979 to capture the 

runoff. The dams and dikes were constructed from 

available sulfide-bearing waste rock and tailings, 

except for Mine Run Dam, which has a clay core. 

Recirculation of water in the impoundments has led 

to evaporative concentration; leaching from containment materials is likely to release additional metal to 

the ponds. However, there has been no clear increase 

in metal concentrations in the ponds from 1987 to 

1991 (Davy Environmental, 1993). This lack of 

increase suggests that significant quantities of metals 

are being removed either by precipitation as solids on 

the pond bottoms or by leakage to ground water. The 

results of this study suggest that contaminated ground 

water flows from the unlined impoundment behind 

Mine Run Dam, through an aquifer composed of 

fractured metamorphic rock along a flow path in the 

direction of Camanche Reservoir.

The principal bedrock units affecting the distribution of ground water are the metavolcanic Gopher 

Ridge Volcanics sequence and the metasedimentary 

Salt Spring slate. Massive sulfide ore bodies are 

associated with the metavolcanic complex. Ground 

water flows through fractures in the two rock types 

(metavolcanic rock and slate) and along the fault 

contact between these units. Flow appears to follow 

the strike of this contact, generally N20°W. The 

contact also may act as a barrier to downward flow 

from the metavolcanic rock to the underlying slate. 

A second fault hypothesized in the study area, striking 

approximately N70°E, also may affect ground-water 

flow in a manner similar to the lithologic contact. 

Median values of hydraulic conductivity estimated for 

the rock units range from 0.002 foot per day in the 

slate to 0.10 foot per day in the metavolcanic rock. 

Consequently, ground-water flow is primarily in the 

fractured metavolcanic unit. Static water levels 

generally are higher in the slate unit than in the 

metavolcanic unit, reflecting recharge at a higher 

elevation and providing another reason why the slate 

may act as a barrier to ground-water flow. Within the 

metavolcanic unit, water levels are highest near Mine 

Run Dam and lowest near Camanche Reservoir. 

Therefore, ground-water flows from the unlined 

impoundment behind Mine Run Dam toward 

Camanche Reservoir.

Results of analyses of samples collected from eight 

wells on three occasions in 1992 were used to 

evaluate the chemical character of ground water 

between Mine Run Dam and Camanche Reservoir. 

Specific conductance of the water ranged from 1,430 

microsiemens per centimeter at well GS-2 to 18,000 

microsiemens per centimeter at well GS-6. The pH

30 Hydrogeology and Geochemistry of Acid Mine Drainage In Ground Water, Penn Mine and Camanche Reservoir
of sampled water ranged from 3.7 at well GS-8A to 

7.8 at well GS-2. Comparison of field water-quality 

data for April and December 1992 indicates a drop in 

pH at several of the sampling points, most notably at 

well GS-5, in which pH decreased from 5.4 to 4.6 in 

this period. This trend suggests that the contaminant 

plume containing the products of sulfide oxidation 

and pond evaporation was moving toward Camanche 

Reservoir at an observable rate.

The oxidative dissolution of pyrite is a major 

source of the acid mine drainage, characterized by 

low pH and high concentrations of sulfate and metals. 

At the Penn Mine, dissolved copper in ground water 

samples ranged from less than 0.010 to 88 milligrams 

per liter. Dissolved iron and aluminum ranged from 

less than 0.010 to 240 and 250 milligrams per liter, 

respectively. Dissolved zinc and cadmium ranged 

from 0.020 to 470 milligrams per liter and <0.010 to 

3.7 milligrams per liter, respectively. The distribution 

of these and other constituents define the extent of a 

plume of acid mine drainage in the fractured groundwater aquifer downgradient from Mine Run Dam. 

Other dissolved constituents (calcium, magnesium, 

and potassium) show a similar distribution to the trace 

metals in ground water, with the exception of sodium 

and chloride, which are associated with a source in 

the slate unit.

A plume of contaminated water in the metavolcanic 

unit is delineated by pH, stable isotopes of oxygen 

and hydrogen, dissolved sulfate, and dissolved metals. 

The source of the plume seems to be in or near the 

metavolcanic unit along the north abutment of Mine 

Run Dam. The lowest values for pH are associated 

with the highest concentrations of sulfate and 

dissolved metals in ground water. The areas of 

lowest pH correspond to the axis of the plume and are 

associated with isotopic compositions enriched in 

heavy isotopes (8D and 818O). The isotopic 

enrichment most likely results from evaporation of the 

pond water and subsequent filtration into the 

ground-water system. Most ground-water flow is in 

a west-to-northwesterly direction from Mine Run 

impoundment toward Camanche Reservoir. Groundwater discharge at lowflow conditions is estimated to 

be (for example, using hydraulic gradients from 

August 1992) from 42 to 21,000 cubic feet per day 

(105 to 5xl07 gallons per year), based on an 

equivalent-porous-medium approximation.

Corresponding fluxes of dissolved metals to 

Camanche Reservoir from the contaminated groundwater plume below Mine Run Dam are estimated to 

fall within the following ranges: for copper, 86 to

42,000 pounds per year; for zinc, 310 to 150,000 

pounds per year; and for cadmium, 1.5 to 750 

pounds per year. Additional ground-water monitoring 

and numerical modeling of ground-water flow and 

transport would help to refine these crude estimates 

and to quantify uncertainties.

References

Alpers, C.N., and Nordstrom, O.K., 1991, Geochemical 

evolution of extremely acid mine waters at Iron 

Mountain, California: Are there any lower limits to pH? 

in Proceedings, Second International Conference on the 

Abatement, of acidic drainage, MEND (Mine 

Environment Neutral Drainage), Montreal, Quebec, 

Canada, September 16-18, 1992, v. 2, p. 321-342.

Alpers, C.N., Nordstrom, D.K., and Ball, J.W., 1989, 

Solubility of jarosite solid solutions precipitated from 

acid mine waters, Iron Mountain, California, U.S.A.: 

Sciences Ge"ologiques, Bulletin, v. 42, p. 281-298.

Ball, J.W., and Nordstrom, D.K., 1991, User's manual for 

WATEQ4F, with revised thermodynamic data and test 

cases for calculating speciation of major, trace, and 

redox elements in natural waters: U.S. Geological 

Survey Open-File Report 91-183, 189 p.

Bigham, J.M., Schwertmann, U., Carlson, L., and Murad, 

E., 1990, A poorly crystalline oxyhydroxy sulfate of 

iron formed by bacterial oxidation of Fe(II) in acid mine 

waters: Geochimica et Cosmochimica Acta, v. 54, 

p. 2743-2758.

Bond, S.R., 1988, Penn Mine Toxic Pits Cleanup Act 

technical investigation report: California Regional 

Water Quality Control Board, Central Valley Region, 

Sacramento, 36 p. (plus 3 appendixes).

Clark, L.D., 1964, Stratigraphy and structure of part of the 

western Sierra Nevada metamorphic belt, CaliforniaU.S. Geological Survey Professional Paper 410, 70 p.

Clark, W.B., and Lydon, P.A., 1962, Mines and mineral 

resources of Calaveras County, California: California 

Division of Mines and Geology, County Report 2.

Craig, H., Gordon, L.I., and Horibe, T., 1963, Isotope 

exchange effects in the evaporation of water: Journal of 

Geophysical Research, v. 68, p. 5079-5087.

Coplen, T.B., Wildman, J.D., and Chen, J., 1991, 

Improvements in the gaseous hydrogen-water 

equilibration technique for hydrogen isotope ratio 

analysis: Analytical Chemistry, v. 63, p. 910-912.

Davy Environmental, 1993, Site Characterization Report, 

Penn Mine, Calaveras County, California: Prepared for 

California Regional Water Quality Control Board, 

Central Valley Region, 174 p., plus 8 drawings and 2 

appendices.

Driscoll, F.G., 1987, Groundwater and wells (2d ed): St. 

Paul, Minnesota, Johnson Division, 1089 p.

Dunham, R., 1961, Report on pollution at the Mokelumne 

River by the Penn Mine, Calaveras County, California: 

California Department of Fish and Game, Report to 

Central Valley Regional Water Pollution Control Board, 

28 p.

References 31
Epstein, S., and Mayeda, T., 1953, Variation of 18O content 

of waters from natural sources: Geochimiceat 

Cosmochimica Acta, v. 4, p. 213-224.

Finlayson, B.J., and Rectenwald, H.J., 1978, Toxicity of 

copper and zinc from the Penn Mine area on king 

salmon (Oncorhynchus Tshawytscha) and steelhead trout 

(Salmo Gairdneri) in the Mokelumne River Basin, 

California: California Department of Fish and Game, 

Environmental Services Branch, Administrative Report 

78-1, 42 p.

Fishman, M.J., and Friedman, L.C., 1985, Methods for 

determination of inorganic substances in water and 

fluvial sediments: U.S. Geological Survey Techniques 

of Water-Resources Investigations, Book 5, chap. Al, 

709 p.

Gringarten, A.C., 1982, Flow-test evaluation of fractured 

reservoirs: Geological Society of America Special Paper 

189, p. 237-262.

Hem, J.D., 1977, Reactions of metal ions at surfaces of 

hydrous iron oxide: Geochimica et Cosmochimica Acta, 

v. 41, p. 527-538.

Hem, J.D., 1985, Study and interpretation of the chemical 

characteristics of natural water: U.S. Geological Survey 

Water-Supply Paper 2254, 263 p.

Hess, A.E., 1986, Identifying hydraulically conductive 

fractures with a slow-velocity heat-pulse flowmeten 

Canadian Geotechnical Journal v. 23, no. 1, p. 69-78.

Heyl, G.R., Cox, M.W., and Eric, J.H., 1948, Penn 

zinc-copper mine, Calaveras County: California Division 

of Mines Bulletin 144, p. 61-84.

Huntiey, D., Nommensen, R., and Steffey, D., 1992, The 

use of specific capacity data to assess transmissivity in 

fractured-rock aquifers: Ground Water, v. 30, no. 3, 

p. 396-402.

Lee, R.R., Kettelle, R.H., Bownds, J.M., and Rizk, T.A., 

1992, Aquifer analysis and modeling in a fractured, 

heterogeneous medium: Ground Water, v. 30, no. 4, p. 

589-597.

Makita, S.N., and Fujii, Roger, 1992, Quality assurance 

practices of the U.S. Geological Survey laboratory in 

Sacramento, California: U.S. Geological Survey OpenFile Report 91-522, 23 p.

Martin, R.C., 1988, Volcanogenic massive sulfide belt of 

the western Sierra Nevada Mountains: Geology 41, 

p. 195-204.

McKibben, M.A., and Barnes, H.L., 1986, Oxidation of 

pyrite in low temperature acidic solutions: Rate laws and 

surface textures: Geochimica et Cosmochimica Acta, v. 

50, p. 1509-1520.

Murad, E., Schwertmann, U., Bigham, J.M., and Carlson, 

L., 1994, Mineralogical characteristics of poorly 

crystalline precipitates formed by oxidation of Fe2+ in 

acid sulfate waters, in Alpers, C.N., and Blowes, D.W., 

eds., Environmental Geochemistry of Sulfide Oxidation, 

ACS Symposium Series, v. 550: American Chemical 

Society, Washington, D.C., p. 190-200.

Nordstrom, O.K., 1982, The effect of sulfate on aluminum 

concentrations in natural waters: Some stability relations 

in the system A12O3-SO3-H2O at 298K: Geochimica et 

Cosmochimica Acta, v. 46, p. 681-692.

Nordstrom, D.K., 1985, The rate of ferrous iron oxidation 

in a stream receiving acid mine effluent, in Selected 

Papers in the Hydrological Sciences: U.S. Geological 

Survey Water-Supply Paper 2270, p. 113-119.

Nordstrom, D.K., and Ball, J.W., 1986, The geochemical 

behavior of aluminum in acidified surface waters: 

Science, v. 232, p. 54-56.

O'Neill, J.R., 1986, Terminology and standards, in Valley, 

J.W., Taylor, J.P., Jr., and O'Neill, J.R., eds., Stable 

Isotopes in High Temperature Geologic Processes, 

Reviews in Mineralogy, v. 16, p. 561-570.

Paillet, F.L., Hess, A.E., Cheng, C.H., and Hardin, E.L., 

1987, Characterization of fracture permeability with 

high-resolution vertical flow measurements during 

pumping: Ground Water, v. 25, no. 1, p. 28-40.

Paillet, F.L., and Kapucu, K., 1989, Fracture 

characterization and fracture-permeability estimates from 

geophysical logs in the Mirror Lake watershed, New 

Hampshire: U.S. Geological Survey Water-Resources 

Investigations Report 89-4058, 49 p.

Papadopoulos, I.S., and Cooper, H.H., 1967, Drawdown in 

a well of large diameter: Water Resources Research, 

v. 3, no. 1, p. 241-244.

Peterson, J.A., 1985, Geologic map of the Penn Mine, 

Calaveras County, California: U.S. Geological Survey 

Miscellaneous Field Studies Map MF-1797.

___1988, Distribution of selected trace and major 

elements around the massive sulfide deposit at the Penn 

Mine, California: Economic Geology, v. 83, p. 419-427.

Schweickert, R.A., 1981, Tectonic evolution of the Sierra 

Nevada range, in Ernst, W.G., ed., The Geotectonic 

Evolution of California: Englewood Cliffs, New Jersey, 

Prentice-Hall, p. 87-131.

Shaw, P., and Towers, C.L., 1937, Water pollution 

problems in California: Fish and Game, California, 

v. 23, no. 4, p. 262-285.

Singer, P.C., and Stumm, W., 1970, Acid mine drainage: 

the rate-determining step: Science, v. 167, p. 1121-1123.

Todd, D.K., 1980, Groundwater Hydrology: New York, 

John Wiley, 535 p.

Webster, J.G., Nordstrom D.V., and Smith K.S., 1994, 

Transport and natural attenuation of Cu, Zn, As, and Fe 

in the acid mine drainage of Leviathan and Bryant 

Creeks, in Alpers C.N. and Blowes, D.W., eds., 

Environmental Geochemistry of Sulfide Oxidation, ACS 

Symposium Series, v. 550: American Chemical Society, 

Washington D.C., p. 244-260.

Wiebelt, F.J., and Ricker, S., 1948, Penn Mine slag dump 

and mine water, Calaveras County, Calif.: U.S. Bureau_ 

of Mines, Report of Investigations 4224, 6 p.

Wood, W.W., 1976, Guidelines for the collection and field 

analysis of ground-water samples for selected unstable 

constituents: U.S. Geological Survey Techniques of 

Water-Resources Investigations, Book 1, chap. D2,24 p.

Zemanek, J., Glenn, E.E., Morton, L.J., and Caldwell, R.L., 

1970, Formation evaluation by inspection with the 

borehole televiewer: Geophysics, v. 35, p. 254-269.

32 Hydrogeology and Geochemistry of Acid Mine Drainage In Ground Water, Penn Mine and Camanche Reservoir
APPENDIX 1. Geophysical logs from U.S. Geological Survey monitoring wells GS-1 through GS-8 at Penn 

Mine site.

EXPLANATION OF TELEVIEWER LOGS

Isolated planes intersecting borehole; 

probably open fractures.

Fracture zone composed of several parallel 

and intersecting fractures.

Faint discontinuous planes intersecting 

borehole; probably foliation in greenschist.

Large opening intersecting borehole; shape 

of top of opening may indicate orientation.

Intensely fractured and altered rock; 

orientation of individual fractures difficult 

to determine.

Bottom of casing above open borehole.

Top of fluid column in open borehole.

I I

Lowermost interval of borehole inaccessible 

to televiewer.

Appendix 1 33
APPENDIX 1. Geophysical logs from U.S. Geological Survey monitoring wells GS-1 through GS-8 at Penn 

Mine site Continued

WELL GS-1

GAMMA LOG, SINGLE-POINT

IN COUNTS CALIPER LOG, RESISTANCE LOG,

PER SECOND IN INCHES IN OHMS TELEVIEWER LOG

0 100 200 300 5 6 7 0 100

LU 

O

oc

I

LU 

CD

LU 

LU

0- 

LU

a

20

40

60

80

100

120

140

160

180

200

1

LU

I____I

 " -.= 

y

34 Hydrogeology and Geochemistry of Acid Mine Drainage in Ground Water, Penn Mine and Camanche Reservoir
APPENDIX 1. Geophysical logs from U.S. Geological Survey monitoring wells GS-1 through GS-8 at Penn 

Mine site Continued

GAMMA LOG,

IN COUNTS

PER SECOND

0 100 200 300 5

0

WELL GS-2

SINGLE-POINT

CALIPER LOG, RESISTANCE LOG, 

IN INCHES IN OHMS TELEVIEWER LOG

6 70 50 100

40

120

140 -

160 -

180 -

200

111

=31

\

Appendix 1 35
APPENDIX 1 . Geophysical logs from U.S. Geological Survey monitoring wells GS-1 through GS-8 at Penn 

Mine site Continued

WELL GS-3

GAMMA LOG, SINGLE-POINT

IN COUNTS CALIPERLOG, RESISTANCE LOG,

PER SECOND IN INCHES IN OHMS TELEVIEWER LOG

0 100 200 300 5 6 70 50 100

HI

oc

ID 

CO

a

ILII 

m

tu LII 

u.

I 120

HI 

a

200

100

140 -

160 "

180 -

36 Hydrogeology and Geochemistry of Acid Mine Drainage In Ground Water, Penn Mine and Camanche Reservoir
APPENDIX 1. Geophysical logs from U.S. Geological Survey monitoring wells GS-1 through GS-8 at Penn 

Mine site Continued

WELL GS-4

GAMMA LOG, SINGLE-POINT

IN COUNTS CALIPER LOG, RESISTANCE LOG,

PER SECOND IN INCHES IN OHMS TELEVIEWER LOG

0 100 2005 6 70 250 500

20

40

60

Ul

to 

a

i

Ul 

COt]

HI

LU

a

80

100

120

140

160 -

180 '

200

O

i

Appendix 1 37
APPENDIX 1. Geophysical logs from U.S. Geological Survey monitoring wells GS-1 through GS-8 at Penn 

Mine site Continued

WELL GS-5

CALIPER LOG, 

IN INCHES

6 8 10

LU

oc

CO

20

I

111 

CD 40

LLJ 

111 

LL

Z 

I

60

111

a

so

38 Hydrogeology and Geochemistry of Acid Mine Drainage in Ground Water, Penn Mine and Camanche Reservoir
APPENDIX 1. Geophysical logs from U.S. Geological Survey monitoring wells GS-1 through GS-8 at Penn 

Mine site Continued

WELL GS-6

GAMMA LOG, SINGLE-POINT

IN COUNTS . CALIPERLOG, RESISTANCE LOG,

PER SECOND IN INCHES IN OHMS TELEVIEWER LOG

0 100 200 300 5 6 70 50 100

20

40

60

LLJ

DC 

CO

a

LLJ

0. 

LLJ 

Q

80

100

120

140

160

180 -

200

Appendix 1 39
APPENDIX 1. Geophysical logs from U.S. Geological Survey monitoring wells GS-1 through GS-8 at Penn 

Mine site Continued

WELL GS-8

GAMMA LOG, SINGLE-POINT

IN COUNTS CALIPER LOG, RESISTANCE LOG,

PER SECOND IN INCHES IN OHMS TELEVIEWER LOG

0 100 200 300 5 6 7 80 50 100

20

40

60

LLJ O

Q

!

5

LLJ

a. 

m 

a

80

100

120

140

160

180

200

I____I I____I

..o.

m

40 Hydrogeology and Geochemistry of Acid Mine Drainage in Ground Water, Penn Mine and Camanche Reservoir
APPENDIX 2. Flowmeter data from U.S. Geological Survey monitoring wells GS-1 through GS-8 at Penn 

Mine site

[ft, foot, gal/min, gallon per minute; NF, no flow; >, value greater than value shown; <, value less than value shown; 

At (s), time in seconds for next pulse to reach thermister; I/At, inverse of At (s' 1 ); +, packer inflated; 0, packer not inflated; 

 , no data]

Well

No.

GS-1

GS-1

GS-2

GS-2

GS-3

GS-3

GS-4

GS-4

GS-5

GS-5

GS-6

GS-6

GS-7

GS-7

Depth 

(ft)

55

90

55

35

45

94

36

45

80

145

25

55

15

30

47

55

70

70

60

43

43

Packer1

Static

+

+

Injection

+

+

+

Static

+

Injection

+

+

Static

+

+

Injection

+

+

Static

Injection O1

0

0

0

0

+

Static

+

O1

+

Injection

Static

Injection

Static

Injection

Date/ 

Direction

11-14-91

11-14-91

Down

11-15-91

-

11-15-91

Down

11-14-91

..

11-14-91

Down

Noisy-probably no flow

~

11-16-91

Down

Down

Down

Down

Up

11-16-91

Up

Down

-

- (too much debris in well)

- (too much debris in well)

 (no well)

 (no well)

At(s)

>60

>60

>60

9.8

>60

>60

3.2

>60

>60

>60

15.0

-

6.5

6.0

9.0

11.0

15.5 1

>60

40

>60

18

~

-

I/At (s'1 )

<0.02

<.02

<.02

.10

<.02

<.02

.31

<.02

<.02

<.02

.07

-

.15

.17

.11

.09

.06

<.02

.02

<.02

.06

~

~

~

Row 

(gal/min)

NF2

NF

NF

0.08

NF

NF

.28

NF

NF

NF

.05

--

.9

1.0

.8

.7 NF1

NF

NF3

NF

.05

~

~

~

-

-

Appendix 2 41
APPENDIX 2. Flowmeter data from U.S. Geological Survey monitoring wells GS-1 through GS-8 at Penn 

Mine site Continued

Well 

No.

GS-8

GS-8

Depth 

(ft)

55

50

45

43

60

55

50

45

' 55

60

65

67 '

62

67

Packer1

Static O1

0

0

0

0

0

0

0

Injection O1

0

0

0

0

+

Date/ 

Direction

11-16-91

Down

Down

Down

Down

Down

Down

Down

Down

Down

Down

Unsteady - no results

Unsteady - no results

At(s)

5.0

6.9

5.0

4.3

7.6

3.9

6.8

4.0

3.0

3.0

-

>60

-

>60

I/At (s'1 )

0.20

.14

.20

.24

.13

.26

.15

.25

.33

.33

~

<.02

<.02

Flow 

(gal/min)

1.0

.85

1.0

1.1

.75

1.15

.9

1.15

,

1.60

1.60

-

NF

-

NF

'Packer is an inflatable bladder that focuses the entire flow in the borehole through the flowmeter. Measurements 

without packer inflated can yield erroneous upflow by driving a convective cell.

2NF = "No flow" to within 0.02 gal/min resolution (with packer) or 0.25 gal/min resolution (without packer). 

'Slight upflow is probably driven by buoyancy of heat pulse - probably no flow.

42 Hydrogeology and Geochemistry of Acid Mine Drainage In Ground Water, Penn Mine and Camanche Reservoir
APPENDIX 3. Purging-log data for U.S. Geological Survey monitoring wells GS-1 through GS-8 at Penn Mine 

site

[Column 7 divided by column 8 equals column 9. gal, gallon; , no data]

Well 

No.

(1)

GS-1 A

OS-IB

GS-2

GS-3

GS-4A

GS-4B

GS-4C

GS-5

GS-6

GS-7

GS-8A

GS-8B

Purge 

date

(2)

1-29-92

4-16,17-92

1-29-92

1-30-92

1-31-92

2-3-92

4-17,18-92

1-28-92

4-14-92

1-29-92

4-15-92

4-16-92

1-29-92

1-31-92

4-16-92

1-30-92

4-17-92

1-27-92

4-13-92

1-29-92

4-15-92

1-28-92

4-14-92

1-29-92

4-14-92

1-29-92

4-17-92

Sample 

date

(3)

1-29-92

4-17-92

2-3-92

2-3-92

2-3-92

2-3-92

4-18-92

1-28-92

4-14-92

1-30-92

4-15-92

4-16-92

1-31-92

1-31-92

4-16-92

2-3-92

4-18-92

1-27-92

4-13-92

1-29-92

4-15-92

1-28-92

4-14-92

1-31-92

__

4-17-92

Volume 

well bore 

(gal)

(4)

258

254

187

187

185

185

187

251

250

276

276

240

203

203

183

185

185

237

248

533

536

247

248

190

243

189

234

Volume 

above 

packer 

(gal)

(5)

22.5

77.7

10.7

10.7

8.6

9.0

11.0

_ 

 _

~

26.9

3.7

3.7

2.9

8.8

8.7

__

 .

7.9

-

7.2

-

Volume 

below 

packer 

(gal)

(6)

235

176

176

176

176

176

176

__

..

213

176

176

176

176

176

__

_

_

182

182

-

Volume 

purged 

(gal)

(7)

21.2

58.2

9.0

8.5

2.6

4.0

75.0

132

86

108

118

27.0

3.2

5.0

11.0

5.7

5.0

54.6

168

41.5

75.2

250

170

118

199

4.0

35.6

Total 

volume 

(gal)

(8)

22.5

77.7

10.7

10.7

8.6

9.0

11.0

251

250

276

276

26.9

3.7

3.7

2.9

8.8

8.7

237

248

533

536

247

238

7.9

243

7.2

243

Percentage

(9)

94

75

84

79

30

44

682

53

34

39

43

100

86

135

379

65

57

23

68

7.8

14

101

71

1,494

82

56

15

Ratio of volume 

purged to 

total volume

(10)

0.9:1.0

.7:1.0

.8:1.0

.8:1.0

.3:1.0

.4:1.0

6.8:1.0

.5:1.0

.3:1.0

.4:1.0

.4:1.0

1.0:1.0

.9:1.0

1.4:1.0

3.8:1.0

.6:1.0

.6:1.0

.2:1.0

.7:1.0

.1:1.0

.1:1.0

1.0:1.0

.7:1.0

15.0:1.0

.8:1.0

.6:1.0

.2:1.0

Appendix 3 43
APPENDIX 4. Hydraulic test data from U.S. Geological Survey monitoring wells GS-1 through GS-8 at Penn 

Mine site

Water-level drawdown and recovery data collected from boreholes during the water-quality sampling in April 1992 are 

presented graphically on the following pages. Where available, recovery data are presented, in plots of residual drawdown 

versus the logarithm of the time ratio [(time versus pump start)/(time since shutdown)]. Where recovery data were not 

collected (wells GS-5, -6, -7, and -8A), drawdown data are shown, in plots of drawdown versus the logarithm of time. Q 

signifies the pumping rate and gal/min is the abbreviated form for gallon per minute.

3.0

H 3.2

z

i 3A

i 3.6

i

S

3.8

4.0

60

62

i.

z

1 66

I 6B

3 70

IT 72

74

76

30

t

UJ I 35

1 40

i

IT

45

50

i i i i i i i i | i i i i i i i i

* Well GS-1 A

Q = 0.3 gal/min

""" 

-

i i i i t i i t I i i i i i i i i

i i i i i i i i | i i i i i i i i

Well GS-1 B

Q = 0.3 gal/min

i 

* 

 .

' ,B

* *

-

-

i i t i i i i i 1 i i i i i i i i

i i i i i i i i | i . i i i i i i

Well GS-2

Q= 1.75 gal/min

-

\

<*-..

_i i i i i i i i I , i i i i i i i

|jj 60

U.

J

8 65

5 70

§

CC

75

60

0«

u_

Z

i 2

§

I 3

1 

*

5

6

14

16

._

1 18

s

1 1 122

i 24

26

28

an

1 1 1 1 1 1 M| 1 1 1 1 1 Ml| 1 1 1 1 1 II 1

Well GS-3

Q = 0.3 gal/min

.

^"" » 

-

i i i i i 1 1 1 1 i i i t i 1 1 1 1 i i i t i 1 1 1

' ' i i i i i n| > i i i i i M| i i i i i i > i

Well GS-4A

Q = 0.3 gal/min

*

_

\

'

, ,,,,,,;! , iii mil , 11,1111

1 1 1 1 1 1 M| , , I , 1 Ml| , I I , , | ||

WellGS-4C .

Q = 0.3 gal/min

-

-

" ,

"* ' . .

1 1 1 1 1 1 1 1 1 1 1 1 1 1 M 1 I 1 1 1 1 1 1 1 1

10 100 

TIME RATIO (SINCE PUMP START)/(SINCE SHUTDOWN)

10 100 1,000 

TIME RATIO (SINCE PUMP START) / (SINCE SHUTDOWN)

44 Hydrogeology and Geochemistry of Acid Mine Drainage In Ground Water, Penn Mine and Camanche Reservoir
APPENDIX 4. Hydraulic test data from U.S. Geological Survey monitoring wells GS-1 through GS-8 at Penn 

Mine site Continued

0.2

I 0.4

J0.6

0.8

_ 

0.1

10

15

20

25

fc

I 4

10

10

Well GS-5

Q= 16.0gal/m!n

0.1

0.2

0.3

0.4

Well GS-8A

Q = 2.0 gal/min

1 10

TIME, IN MINUTES

100 1 10 

TIME. IN MINUTES

100

Well GS-6

Q = 1.75 gal/min

22

23

24

25, r

26

27

26

29

Well GS-8B

Q = 0.3 gal/mln

10

TIME, IN MINUTES

100 », 10 100 

TIME RATIO (SINCE PUMP START) / (SINCE SHUTDOWN)

Well GS-7

Q = 2.1 gal/min

so 100

TIME, IN MINUTES

Appendix 4 45