Hydrogeology and Geochemistry of Acid Mine Drainage 

in Ground Water in the Vicini ty of Penn Mine and 

Can1anche Reservoir, Calaveras County, California: 

Second-Year Summary, 1992-93 

U.S . GEOLOGICAL SURVEY 


Water Res ou rces InveStigatiO ns 


Re port 1)6-·P57 


Prepared in co peration with the 

CALIFORNIA STATE WATER RESOURCES C NTROL BOARD 

.lnd lhl.: EA T BAY MUNICIPAL UTIUTY 01, TRICT 
Photograph on cover is the smelting works of the Penn Mining Company at 


Campo Seco, California. 


From: 


Aubrey, L.E., 1908, The Copper Resources of California: Bulletin 50, California 


State Mining Bureau; courtesy of California Department of Conservation, 


Division of Mines and Geology 

Hydrogeology and Geochemistry of Acid Mine Drainage in 

Ground Water in the Vicinity of Penn Mine and Camanche 

Reservoir, Calaveras County, California: Second-Year Summary, 

1992-93 

By Scott N. Hamlin and Charles N. Alpers 

U.S. GEOLOGICAL SURVEY 

Water-Resources Investigations Report 96-4257 

Prepared in cooperation with the 

CALIFORNIA STATE WATER RESOURCES CONTROL BOARD and the 

EAST BAY MUNICIPAL UTILITY DISTRICT 

-.0 

o I 

co 

o 

"" -.0 

Sacramento, California 

1996 
u.s. DEPARTMENT OF THE INTERIOR 

BRUCE BABBITT, Secretary 

u.s. GEOLOGICAL SURVEY 

Gordon P. Eaton, Director 

Any use of trade, product, or firm names in this publication 

is for descripti ve purposes only and does not imply 

endorsement by the U.S. Government. 

For sale by the 

U. S. Geological Survey 

Branch of Information Services 

Box 25286 

Denver Federal Center 

Denver, CO 80225 

For additional information write to: 

Distric t Chief 

U.S. Geological Survey 

Federal Building, Room W-2233 

2800 Cottage Way 

Sacramento, CA 95825 
CONTENTS 

Abstract ...... .. ....... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I 


Appendix 1. Lithologic logs and weU-construction data from USGS monitoring wells GS-1 through 


Appendix 2. Geophysical and selected acoustic-televiewer logs from USGS monitoring wells 


Appendix 3. Flowmeter data from USGS monitoring wells GS-lO, -11, and -16, at Penn Mine site, 


Appendix 4. Water-level altitudes from USGS monitoring wells at Penn Mine site, September 1992 to 


Introduction .. . . . . ... .... .. . ..... . ......... . ........... . ...... .. ... . ......... 2 


Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 


'Purpose and Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 


Acknowledgments .. . .. . . .. . . ..... . . .. ..... . .... . . ... . .... . ...... .. . ... . . 5 


Methods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 


Drilling and Well Construction ... ........... . .... . ..... . ..... ... ........ . . .. 6 


Geophysical Logging, Flowmeter Tests, and Water-Level Measurements .. . ..... . . ...... . 8 


Water-Qual ity Sampling . . . . . .. .. ... .... .. ... . . .. .. . .... .... .. . ... .. ... . .. 9 


Hydrogeology .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 10 


Identification of Fracture Zones .. . . ............ . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 10 


Hydraulic Characteristics of Fractured Bedrock ........ ..... . ..... .. .. . .... .... .. . 12 


Water Levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 


Water Quality . .... . .. .. . ..... .. .. . ..... . .. .. .. . . . .. . . ... . . . .. . .......... . . . .. 16 


Results of Sampling . .. .......... .. .............. . ... .. . .. .. . . ...... . .. . .. 16 


Distribution of Acid Mine Drainage .. . ... . .... .. . .... . ... .. .... .. . ............ 16 


Geochemical Correlations . ... ....... .. . . . . . .. ... .. ... . .. . ....... .. .... .. .. . 22 


Flow Rate and Metal Loading of Contaminated Ground Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 25 


SUlnmary . . ............. . .... . .. .... . ... .. ..... . . .. . .... .. .. .... . . .. . . ... . . . 26 


References .... . . ..... . .... .. ... . .. .. .. . . .. ... .. ... .. .. .. .. .. .. . . .. . .. .. . . ... 27 


GS-20 at Penn Mine site ........ .................. ..... ... ... .. . . . . . . . . . . . . .. 30 


GS-1O, -11 , -] 2, -13, -14, -15, -16, and -18 at Penn Mine site . . . . . . . . . . . . . . . . . . . . . . . . . .. 33 


December 1993 . ..... . ..... . .. . . .......... .. ........ . . .. ... .. . .. ........ .. 42 


November 1993 ... ... ... .. . .. .. .. ... . ... ...... ...... . . .. ... ....... . .... .. . 43 


ILLUSTRATIONS 

1-3. Maps showing: 

1. 	 Location of Penn Mine and Camanche Reservoir in the Foothill copper-zinc 


bell of California . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 


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


3. 	Location of monitoring wells and conceptual hydrogeologic section line ... . . . . . . .. . 6 


4. 	 Conceptual hydrogeologic section A-B-C-D-E constructed using data from Camanche 


Re ervoir; wells GS-3, -8, -16, -18, -19, and -20; and Mine Run Reservoir ... . ... . .. .... 11 


5. 	Map showing subsurface altitude of the metavolcanic-slate contact .................... 12 


6. 	 Graph showing flowmeter data and acoustic-telev iewer logs for well GS-16 . . . . . . . . . . . . . . 13 


7. 	Hydrographs showing water levels in Camanche and Mine Run Reservoirs, and in selected 


adjacent wells at Penn Mine, September 1992-November 1993, and in wells GS-18, -19, 


and -20 at Penn Mi ne, November 1992-November 1993 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 


8. 	 Graph showing relation between flow rate from seeps at well GS-20 (shaft no. 4) and 


water level in well OS-18 (300-foot level, near shaft no. 3) at Penn Mine . .. . ...... ..... 15 


9. 	Map showing areal distribution of pH in ground water ill metavolcanic rocks at Penn Mine, 


December 1992 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 


Contents III 
10-12. Graphs showing: 

10. Relation between sulfate concentration and pH in ground water and in Mine Run 

Reservoir at Penn Mine, April and December 1992, and January and July 1993 . . . . . . . 22 

11. Stable-isotopic composition of water samples from wells, seeps, and Mine Run 

Reservoir at Penn Mine, April and December 1992, and January and July 1993 . . . . . .. 22 

12. Relation between delta oxygen-18 and delta sulfur-34 in dissolved sulfate at 

Penn Mine .............................................. . ........ 24 

TABLES 

1. 	 Chemical data for water samples from Mine Run Reservoir, wells, and two seeps at Penn Mine . . . . 17 

2. 	Chemical data, expressed as percentages by volume, for gas exsolved from water pumped from 

well GS-18 (shaft 3 area) at Penn Mine, January 1993 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 20 

3. 	 Weight ratios of metals in ground-water and surface-water samples from Penn Mine. . . . . . . . . . .. 23 

CONVERSION FACTORS, WATER-QUALITY INFORMATION, VERTICAL DATUM, AN D 

WELL-NUMBERING SYSTEM 

Multiply By To obtain 

acre 0.4047 hectare 

acre 4,047 square meter 

cubic foot per day (ft3/d) 0.02832 cubic meter per day 

foot (ft) 0.3048 meter 

foot per day (ftld) 0.3048 meter per day 

foot squared per day (ft2/d) 0.0929 meter squared per day 

gallon per day (gal/d) 0.004546 cubic meter per day 

gallon per minute (gal/min) 0.06308 liter per second 

inch (in.) 2.54 centimeter 

mile (mi) l.609 kilometer 

square foot (ft2) 0.09290 square meter 

Temperature is given in degrees Celsius (OC), which can be converted to licgrees Fahrenheit (OF) by the 

following equation: 

WATER-QUALITY INFORMATION 

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

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

per liter is equivalent to 1 milligram per liter. For dissolved solids concentrations less than about 7,O()() 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 geodetlc 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. 

IV 	 Conversion Factors, Water-auality Information, Vertical Datum, and Well-Numbering System 
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 0), 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 mericlian. 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 15 characters and follow the format 004NOlOE04G002M. In this report, well numbers are abbreviated 

and written 4NIlOE-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 4NIlOE-4G2 is derived. 

RANGE 

R2W R1W R1E R10E 

D. T6N 

l: 

CJ) 

Z T5N 

0

== 

.... T4N 

0 C B A 

E F G H 

M l J 

N P 0 R 

6 5 

7 8 

18 17 

19 20 

30 29 

31 32 

I: 

.!!! 

:g 

:;: 

0

:c 

is 

~ 

SECTION 4 

4N110E-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: Second-Year Summary, 

1992-93 

By Scott N. Hamlin and Charles N. Alpers 

Abstract 

Acid drainage from the Penn Mine in 

Calaveras County, California, has produced a 

plume of contamination in ground water 

between Mine Run Dam and Camanche 

Reservoir. Historically, contaminated surface 

runoff from the mine flowed directly into the 

Mokelumne River; after the construction of 

Camanche Dam in 1963, the surface runoff 

flowed into Camanche Reservoir. Interaction 

of surface water with sulfide-bearing waste 

rock and mill tailings has produced acidic 

surface water with pH values between 2.3 and 

2.8 and high concentrations of sulfate and 

metals including aluminum, cadmium, copper, 

iron, and zinc. Diversions and unlined 

impoundments were constructed in 1978 to 

prevent or reduce surface runoff from the mine 

site. Some of the impounded mine drainage 

infiltrates to the ground water through fractures 

in bedrock and flows toward Camanche 

Reservoir. The 10weITIlost impoundment was 

treated with lime for several months during 

1993 to raise pH and to immobilize 

contaminants, but the impoundment has since 

been aI10wed to resume its untreated condition. 

This report summarizes the findings fTom 

the flfSt 2 years of study by the U.S. 

Geological Survey of contaminated ground 

water at the Penn Mine. The distribution and 

flow of ground water at the Penn Mine is 

controlled by geologic features and hydraulic 

properties. Geologic controls include fractures 

in bedrock, faults, and the contact between the 

principal rock types in the area. Most flow 

occurs through fractures in a metavolcanic unit 

along its contact with an underlying 

metasedimentary (slate) unit. The median 

hydraulic conductivity is about 10 times higher 

in the metavolcanic unit (0.1 foot per day) than 

in the slate unit (about 0.01 foot per day). 

Most flow occurs in the fractured metavolcanic 

rocks; hydraulic conductivity in this unit is as 

high as 50 feet per day. The general hydraulic 

gradient in ground water in the area between 

Mine Run Dam and Camanche Reservoir is 

westward toward Camanche Reservoir. 

Field data show a close relation between 

water quality in Mine Run Reservoir and water 

quality in downgradient wells in an area 

covered by slag. Specific conductance at all 

wells increased between April and December 

1992. During the same period, some wells 

showed a decrease in pH and an increase in 

dissolved metals concentration, reflecting a 

higher proportion of acid drainage in the 

ground water. Heavy stable isotopes of 

hydrogen and oxygen are enriched in the 

impounded surface water, as well as in the 

ground water downgradient from the impoundments. These stable isotope data indicate that 

the partially evaporated water in the impoundments is the most likely source of contamination to the fractured-rock aquifer in the slag 

area between Mine Run Dam and Camanche 

Reservoir. 

Water fTOm the underground mine 

workings is chemically distinct from ground 

water in the slag area. Exsolved-gas 

compositions in water from the flooded mine 

workings indicate somewhat reducing 

conditions. Ratios of dissolved concentrations 

Abstract 1 
of zinc to copper and of zinc to cadmium are 

anomalously hi gh in the underground mine 

water in comparison with such ratios for 

ground water in the slag area. These data 

suggest preferential scavenging of copper and 

cadmium, relative to zinc, by hydrogen sulfide 

produced by sulfate reduction in the mine 

workings. Variations in stable isotopes of 

sulfur and oxygen in dissolved sulfate are 

consistent with this interpretation. 

Discharge toward Camanche Reservoir 

within the acidic ground-water plume at the 

base of Mine Run Dam is estimated to be 

about 40 cubic feet (300 gallons) per day, using 

an average hydraulic gradient of 0.07 and a 

geometric mean value for hydraulic 

conductivity of 0.1 foot per day based on a 

total of five measurements from three wells in 

this immediate area. The actual rates of 

ground-water discharge in the contaminant 

plume vary with plume width, hydraulic 

gradient, and hydraulic properties of the 

fractured-rock aquifer. The hydraulic gradient 

varies with seasonal changes in recharge and in 

the water level of Camanche Reservoir. For 

the flow rate of 40 cubic feet per day, the 

corresponding loadings of dissolved metals 

flowing toward Camanche Reservoir were 

estimated to be 17 grams of copper per day, 

250 grams of zinc per day, and 2.7 grams of 

cadmium per day. 

INTRODUCTION 

Background 

The Penn Mine is an abandoned copper-zinc 

mine in the Foothill copp r-zinc belt in 

north we 'tern Calaveras County, California 

(Peterson, 1985) (fig. 1). The mine property 

encompasses about 140 acres (FinJayson and 

Rectenwald, 1978) in the drainage basin of Mine 

Run, an intennillent tributary to Camanche 

Reservoir. Mining activity at Penn Mine was active 

from th 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 smelt rs was 

dumped in a 1,500-ft-long area immediately 

adjacent to the former channel of the Mokelumne 

River (Finlayson and Rectenwald, 1978). The 

history of the Penn Mine was presented in more 

detail in a report by HamJin and Alpers (1995). 

Historically, contaminated surface runoff from 

the Penn Mine flowed directly into the Mokelumne 

River. Completion of Pardee Dam, about 3 mi 

upstrean1 from the mine, in 1929 decr ased the 

streamflow available for diluting the contaminated 

runoff. Completion of Camanche Dam, about 9 mi 

downstream from the mine, in 1963 flooded pllit of 

the Mokelumne River basin to approximately 0.5 mi 

upstream of Penn Mine. The altitude of the 

spillway of Camanche Dam is 236 ft above sea 

level, whereas the top surface of the slag pile is 

about 220 ft abo ve sea level. The slag pile along 

the former Mokelumne River channel is about 20 ft 

thick; consequently the slag is partially or totally 

flooded when the res rvoir pool is higher than 

about 200 ft above sea level (Finlayson and 

Re tenwald, 1978). 

In response to incidents of fi h mortality, 

several diversion chaJU1els were constructed in ] 978 

at the Penn Mine site to divert relatively unpolluted 

surface runoff around the Hinckley Run and Mine 

Run drainages (California Regional Water Quality 

Control Board- Central Valley Region, written 

commun., 1978, 1979). Hinckley Run drains from 

the northeast into Mine Run Re ervoir and contains 

impoundments HRI , HR2, and HR3 (fig. 2). Mine 

Run drains from the southeast into Mine Run 

Reservoir and contains impoundments .MR.l, MR2, 

and .MR.3 (fig. 2). These seven impoundments 

(Mine Run Reservoir, HRI -3, and .MR.1 -3) were 

constructed in 1978 to capture contaminated runoff 

from the Penn Mine site, replacing two or more 

previously existing impoundments. The Mine Run 

Dam was constructed from nonreactive earth 

materials with a clay core. The remaining dams or 

2 Hydrogeology, Geochemistry of Acid Mine Drainage In Ground Water, Penn Mine and Camanche Reservoir 
AREA OF 

FIGURE 1 

50 Miles 

I 

50 Kilometers 

EXPLANATION 

Foothill copper-zinc belt 

- -- Outline of Calaveras County 

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

Peterson, 1985). 

Introduction 3 
120°52'45· 120"52'30· 

38°14'10· 

38°14'00· 

38°13'50· 

EXPlANAnON 

D Mixed and affected soil and fill ­ Waste rock = ~ Wastewater Impoundment

~ Mill taUlngs --­

CJ Slag 

/ 

"­

I' 

I 

I 

\ 

\ 

, 

"­

I 

"­

I 

! 

Camanche Reservoir 

180-foot shoreline 

\ ,

\ 236-loot shorelme 

'(' (maximum stage) 

@ / 

I 

,r" 

stock -:3 "~ ' 

pond f Hinckley Run 

.. 

o ~ 30 

2~ 

61J 

300 

90 

400 

" 120 

500 Fefl , 

1S0Melers 

Berm In waste rock 

Clay-<:ore dam 

Spillway 

Tunnel under slag 

Figure 2. Penn Mine site and location of unlined wastewater impoundments, Calaveras County, California (modified 

from Davy Environmental, 1993). 

4 Hydrogeology, Geochemistry of Acid Mine Drainage in Ground Water, Penn Mine and Camanche Reservoir 
dikes were constructed from available sulfidebearing waste rock, mill tailings, and soil; the 

impoundments were not lined, with the exception of 

an ineffec tive plastic liner in pond MR.l. 

Construction of the unlined impoundments 

did not eliminate releases of surface runoff to 

Camanche Reservoir. Releases of surface water 

from Mine Run Reservoir to Camanche Reservoir 

occurred during wet periods in 1979 through 1984 

and in 1986 (Bond, 1988). A relatively small 

amount of surface water discharged during February 

and March 1993 after Mine Run Reservoir was 

treated with hydrated lime [Ca(OH)2J to attain a pH 

value of greater than 7.0 (Richard Sykes, East Bay 

Municipal Utility District, oral commun., 1993). 

Recirculation of water from lower to upper ponds to 

reduce the volume of acid water enhanced the 

evaporation of contaminated waters and increased 

the contact time of acid drainage with the reactive 

waste rock and tailings (Bond, 1988). Because the 

impoundments are not lined, acid water can 

infiltrate to the ground water contained within the 

underlying fractured-rock aquifer. Characterization 

of the resultant acid ground-water plume 

downgradient from Mine Run Dam will facilitate 

management and remediation of the contamination. 

This study was done by the U.S. Geological Survey 

(USGS) in cooperation with the California Regional 

Water Quality Control Board-Central Valley 

Region (herein referred to as the Regional Board) 

and the East Bay Municipal Utility District (herein 

referred to as the Utility District). 

Purpose and Scope 

The ground-water investigation by the USGS 

in the Penn Mine area began in October 1991 and 

has the overall goal of characterizing the 

distribution of metals, sulfate, and acidity in ground 

water flowing through a fractured-rock aquifer. 

This report summarizes the findings from the first 2 

years of study. In a previous report, Hamlin and 

Alpers (1995) presented initial fi ndings from the 

first year of study. The specific objectives of the 

investigation are to evaluate (1 ) the quantity and 

quality of ground water flowing from the Penn 

Mine area toward Camanche Reservoir; 

I Available from East Bay Municipal Utility District 

(2) ground-water transport of metals, · sulfate, and 

acidity between Mine Run and Camanche 

Reservoirs; and (3) the hydrologic interactions 

between the flooded mine workings and other 

ground water and surface water in the Penn Mine 

area. Accomplishment of these objectives will 

facilitate the development of effective pol1utionabatement measures (such as thoSe described by 

Golder Associates, Inc., 1996) for the site. 

Hamlin and Alpers (J 995) described ground 

water in the Mine Run drainage basin between 

Mine Run Dam and Camanche Reservoir on the 

basis of data from eight boreholes drilled in 1991. 

This report includes data from 12 additional boreholes drilled in 1992 (eight boreholes in the vicinity 

of Mine Run Dam and four boreholes in the vicinity of shafts 3 and 4 in the area adjacent to pond 

HR2; fig. 2). Geologic, hydrologic, and waterquality data were collected during 1991-93 from the 

20 USGS boreholes and 2 boreholes constructed by 

the Utility District and its contractors (Brown and 

Caldwell Consultants, written commun., 1991) '. 

These data were used to describe geologic structure, 

ground-water movement, and the distribution of 

acid mine drainage in the ground-water system. 

Acknowledgments 

The authors acknowledge several USGS 

colleagues for assistance with this study. Paul A. 

Hsieh (Menlo Park, Calif.) assisted with the design, 

procurement, and installation of downhole inflatable 

packers. Frederick L. Paillet (Denver, Colo.) 

supervised field measurements and data analysis of 

borehole geophysics, including conventional logs 

(caliper, gamma, etc .), acoustic-televiewer logs, and 

heat-pulse flowmeter tests; assistance from Roger 

H. Morin and Richard E. Hodges on these tasks 

also is appreciated. Gas analyses were done by 

William C. Evans (Menlo Park, Calif.) Stable 

isotopes of oxygen and sulfur in dissolved sulfate 

were analyzed under the supervision of Robert O. 

Rye (Denver, Colo.). Interpretation of the 

hydrogeology benefitted from discussions with 

Clark Londquist (Sacramento Calif.) and Anthony 

Buono (San Diego, Calif.). Interpretation of 

geochemical correlations was improved by 

discussions with Terry Rees (San Diego, Calif.). 

Introduction 5 
/ 

Camanche Reservoir 

stock pond p ~\

/ . ' 

/ .. ··~Hinckley Run 

1 BO-foot shoreline Hinckley Run I 

Diversion 

I 

E 

l-_:1:'- -=fro,--:::;.\Xl,,----:;ro"'---"l5iJll Feel

30 00 90 120 150M,lers 

D Waste rock 

Wastewater Impoundment 

D Slag 

A--E 

4~ 

.W-SD 

EXPLANATION 

LIne of section 

USGS well and number - Letters denote 

depth Intervals separated by innatable packers 

MIne shaft and number 

EBMUD well and number 

Figure 3. Location of monitoring wells and conceptual hydrogeologie section line, Calaveras County, California. 

METHODS 

Drilling and Well Construction 

The USGS completed 20 boreholes for 

ground-water monitoring during 1991 and 1992 

(fig. 3). Boreholes GS-l through GS-8 were drilled 

in November 1991 (Hamlin and Alpers, 1995) and 

GS-9 through GS-20 were drilled in November 

1992. All of these boreholes were drilled using the 

rotary air-circulation method. During drilling, 

compress d air was sufficient to keep the holes 

open; the addition of water during drilling was not 

necessary. Drill cuttings were monitored 

continuously, and samples were collected every 5 to 

10 ft. Drill logs and details of well construction for 

wells GS-1 through GS-20 are summarized in 

appendix. 1. 

6 Hydrogeology, Geochemistry of Acid Mine Drainage in Ground Water, Penn Mine and Camanche Reservoir 
In the area between Mine Run Dam and 

Camanche Reservoir, two shallow (20-25 ft) boreholes (GS-9 and -10) intersected unconsolidated 

material consisting primarily of slag and weathered 

metavolcanic rock. These holes did not intersect 

the ground-water table at the time of drilling. Eight 

of the 12 boreholes drilled in 1992 were completed 

primarily in the metavolcanic unit. Boreholes GSII, -13, and -14 were drilled in the metavolcanic 

unit in the slag-pile area between Mine Run Dam 

and Camanche Reservoir. The remaining five 

boreholes in the metavolcanic unit were located as 

follows: one borehole (GS-16) was drilled on the 

north abutment of Mine Run Dam, three boreholes 

(GS-17, -18, and -19) intersect inclined shaft 3 and 

adj acent mine worldngs, and one borehole (GS-20) 

intersects i ncl ined shaft 4. Two boreholes (GS-12 

and -1 5) were completed in the slate unit beneath 

the slag pile. Total depths of the boreholes 

completed during 1992 ranged from 20 ft in well 

GS-9 to 260 ft in well GS-18. 

At drilling sites GS-9 through GS-20, a 

l3.75-inch-diameter rotary bit was used to drill 

through the overburden (alluvium, slag, and (or) 

waste rock) to a depth of about 6 ft, and lO-inchdiameter steel surface casing was set and sealed 

with a mix of bentonite and cement. For wells 

GS-9 and -10, which were constructed to monitor 

hydrologic conditions in the slag, perforated 6-inchdiameter casing was installed to the total depth of 

the well. 

For wells GS-II, -13, -14, and -] 6, 

constructed to monitor hydrologic conditions in the 

metavolcanic unit (see "Hydrogeology" section of 

this report), an 8.75-inch-diameter hole was drilled 

below the bottom of the lO-incb-djameter surface 

casing into tbe metavolcanic rocks to a deptb of to 

to 60 ft, generally above the contact between the 

metavolcanic and slate units. A 6-inch-diameter 

polyvinyl chloride (PVC) casing was set in the 

8.75-inch-diameter bole, from land surface to 10 to 

60 ft below land surface. The bottom 5 ft of 

annular space between tbe PVC casing and hole 

wall was filled with 0.375-inch bentonite pellets 

followed by bydrated mortar mix. In holes with 

more than 20 ft of PVC casin g, non-sulfide-bearing 

drill cuttings were used for part of the back fill of 

the annular space and the upper 3 to 5 ft were then 

'filled with hydrated mortar mix. A 5.65-inchdiameter air hammer bit was used to drill below the 

6-in. casing to the metavolcanic-slate contact. The 

IAvailable from East Bay Municipal Utility District 

borehole was left open from below the PVC casing 

to the bottom of the hole. 

For wells GS-12, and -15, constructed to 

monitor the hydrologic conditions in the slate unit 

underlying the metavolcanic rocks in the slag area, 

an 8.75-inch-diameter hole was drilled to the 

metavolcanic-slate contact and 6-inch-diameter PVC 

casing was set to this depth in the same manner as 

described above. Below the 6-inch-diameter casing, 

a 5.65-inch-diameter air-hammer bit was used to 

drill 50 ft into the underlying slate unit. This part 

of the well was left as open borehole. 

The wells constructed to monitor hydrologic 

conditions in the underground mine workings (GS17, -18, -19, and -20) were constructed in a manner 

similar to that of the other wells constructed in 

metavolcanic rocks (GS- Il, -13, -14, and -16), with 

the exception that that slate contact was not reached 

in the area of the mine workings. Instead, the 

drilling stopped when the mine workings were 

intersected. Of the four wells that penetrate the 

mine workings, GS-18 is the only one that 

intersects several feet of open mine workings; the 

other boreholes intersect shaft 3 (GS- 17 and -19) or 

shaft 4 (GS-20), which apparently were backfilled 

with waste rock in 1978. 

In addition to the wells constructed by the 

USGS for this study, several wells were drilled in 

1989 and 1990 by the Utility District and its 

consultants (Brown and Caldwell Consultants, 

written commun., 1991 )1. Of these wells, W-ID 

and W -50 were sampled by USGS as part of the 

present study. Lithologic logs and details of well 

construction for wells W -1 D and W -5 0 were 

provided by Brown and Caldwell Consultants, 

written commun" (1991 )1. 

Segments of three boreholes drilled in 1991 

were isolated for additional testing to distinguish 

flow and chemical characteristics of indi vidual 

fTactu re zones. Four inflatable packers were 

installed for the duration of the study in three of the 

fractured-rock monitoring wells. Once inflated, the 

packers virtually eliminate vertical ground-water 

flow and mixing. Additional details on the 

construction of the packers were reported by 

Hamlin and Alpers (1995). Single packers were 

installed at sites GS-I and GS-8. Upper intervals 

were designated as "A" and lower intervals as "B" . 

The packer at site GS-l, set at a depth of 80 ft 

Methods 7 
below land surface, separates the upper well (GS1A) from the lower well (GS-1B). The upper well 

monitors the metavolcanic unit and the 

metavolcanic-slate contact at a depth of 70 ft below 

land surface. The lower well monitors the slate unit 

exclusively. The packer at site GS-8 was set at a 

depth of 76 ft below land surface. Well GS-8A 

(upper interval) monitors the metavolcanic unit and 

the metavolcanic-slate contact; GS-8B (lower 

interval) monitors 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 

wells are designated (from shallow to deep) GS-4A, 

-4B, and -4C. GS-4A and -4B monitor ground 

water intervals in the metavolcanic unit. GS-4C 

monitors the metavolcanic-slate contact and the 

slate unit. 

Geophysical Logging, Flowmeter Tests, and 

Water-Level Measurements 

The open boreholes were logged by standard 

geophysical methods and by an acoustic televiewer 

and a heat-pulse flowmeter during December 1992. 

The downhole geophysical data were collected and 

processed by a USGS crew from Denver, Colorado, 

under the direction of Frederick L. Paillet. The 

standard geophysical logs included natural gamma, 

fl uid temperature, single-point resistivity, fl uid 

resistivity, short-normal resistivity (16-inch separation), long-normal resistivity (64-inch separation), 

and caliper. The gamma log was used to differentiate slate and metavolcanic rock units, the principal 

rock types encountered. The relatively high 

radioisotope (potassium and uranium) content of the 

slate gi ves it a distinctively high gamma response. 

Geophysical logs for wells GS-I 0, -1 1, -12, - 13, ­

14, -15, - 16, and -18 are provided in appendix 2. 

Caliper logs were the only standard geophysical 

data collected for wells GS-lO, -12, and -18. 

The acoustic televiewer uses high-frequency 

acoustic energy to produce a 360-degree 

representation of the borehole surface. It yields 

high-resolution information about the location, 

character, and orientation of fractures and other 

openings. 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 

video-camera logs (PaiUet and Kapucu, 1989). 

Acoustic televiewer images for wells GS-11 , -12, 

- 16, and -18 are included in appendix 2. 

Downhole heat-pulse flowmeter tests were 

used to determine the magnitude and direction of 

flow at different depth intervals in boreholes under 

both static and injection conditions. The flowmeter 

was composed of a thermistor above and below a 

filament that puts out a tiny heat pulse when 

triggered (Hess, 1986; Paillet and others, 1987). 

Detection of the heat pulse by the upper or lower 

thermistor determines whether flow is upward or 

downward. The velocity of flow in the borehole is 

proportional to the time it takes the pulse to reach 

one of the thermistors. Measurement of low flow 

rates in the borehole is facilitated by use of an 

inflatable bladder, which directs all vertical flow 

through the meter. Low flow rates are thus 

amplified in proportion to the reduced crosssectional area produced when the bladder is 

inflated. 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 were 

done in wells GS-lO, -11, and -16 (appendix 3). 

Water-level data were collected on a monthly 

basis at each of the 20 USGS monitoring well sites 

(GS-l through -20) when accessible. Inflatable 

packers were installed at sites GS-1, -4, and -8 to 

isolate fracture zones of interest. The remaining 

boreholes represent average water-level conditions 

over the entire length of open boreholes. Staticwater-level data were collected with an electric 

sounder. Automated water-level recorders were 

installed at sites GS-I, -4, -6, and -8. Shaft 

encoders, in conj unction with float-counterweight 

mechanisms, were used at wells GS-l A, - I B, -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 

stored on an hourly basis with datalogger units at 

each of the fOllr instrumented sites (Hamlin and 

Alpers, 1995). 

Water-level measurements could not be 

obtained in wells GS-l through -15 from early 

Summer 1993 until December 1993. During this 

period, the water level in Camanche Reservoir rose 

above the 220-fool 1 vel, inundating the slag area. 

The wells were sealed prior to submergence to 

prevent interchange between the reservoir and 

contaminated ground water. In most cases, threaded 

fittings with plastic screw caps were glued directly 

to the well casing. At sites where this was not 

possible, a rubber sleeve and plastic cap were 

attached to the top of the 10-inch steel pipe that 

provides the smface seal for these wells. This 

8 Hydrogeology, Geochemistry of Acid Mine Drainage in Ground Water, Penn Mine and Camanche Reservoir 
required removal of the water-level recorders and 

assoc iated equipment at sites GS-l , -4, -6, and -8. 

One of these recorders was installed at well GS-18 

to monitor water-level changes in the mine 

workings near shaft 3. 

Water-Quality Sampling 

Wells at sites GS-l through -8 were sampled 

during the periods January 26-February 1, 1992, 

and April 13-18, 1992 (Hamlin and Alpers, 1995); 

selected wells at sites GS-l to -20 were sampled 

during December 10-22, 1992. Specific 

conductance, pH, temperature, dissolved oxygen, 

and oxidation-reduction (redox) potential (Eh) were 

measured in the field during pumping using a 

flow-through chamber to prevent aeration of the 

ground water. A platinum electrode was used in 

the flow chamb r to measure the redox potential (in 

millivolts) of the ground water. Millivolt values 

were converted to Eh using the method described 

by Makita and Fujii (1992). After these properties 

had stabilized in the flow-through cell, samples 

were collected and processed using standard 

methods adopted by the USGS (Wood, 1976). At 

many wells, fewer than three "casing volumes" were 

purged because of slow recovery of water levels 

and low sustainable pumping rates. 

Samples for anion and cation analysis were 

fi ltered through a O. lO-flm cellulose nitrate 

membrane (142 mm in diameter) and a plate filter 

assembly. Filtered samples for cation analysis were 

acidified with nitric acid to a pH of about 1. All 

samples, except those collected for analysis of 

isotopes in dissolved sulfate, were submitted to the 

USGS National Water Quality Laboratory (NWQL) 

for analysis. Sulfur and oxygen isotopes in 

di solved sulfate were detennined by the USGS 

stable-isotope laboratory in Denver, Colorado, using 

methods descri bed by Wasserman and others 

(1992). 

Stable isotopes of hydrogen and oxygen were 

determined by the USGS NWQL using raw samples 

(not filtered or acidifi ed) collected in glass bottles 

that were predried in an oven at 110°C. The most 

abundant isotopes that compose [he water molecul 

are oxygen-16 C6

0), oxyg n-18 e80), hydrogen CH 

or H), and hydrogen-2 CZH; also known as 

deuterium, D). The heavy isotopes 18

0 and 2H exist 

naturally in water molecules in global 

average proportions of about 0.2 percent of total 

oxygen and 0.07 percent of total hydrogen. 

Ratios of the heavy to light isotopes, R, are 

expressed in delta units (8), which are parts per 

thousand (per mil, %0) differences relative to an 

arbitrary standard known as standard mean ocean 

water (V -SMOW) 

where Rand RS(d are the isotope ratios (DIH or 18

0/160) of the sample and standard, respectively. 

Relative concentrations of 2H and 18

0, expressed as 

8D and 8 180, generally correlate in a linear fashion. 

Graphic representation of this relation for global 

precipitation data produces a straight line known as 

the global meteoric water line (Craig and others, 

1963), defined by 

(2) 

Aqueous sulfate was precipitated as barium 

sulfate from fi ltered, unacidified samples by 

addition of a solution containing I M (molar) 

barium chloride. The bariu m sulfate precipitate was 

filtered, dried, and analyzed for sulfur and oxygen 

isotope ratios. Sulfur isotope variations are most 

commonly reported with regard Lo stable isotopes 

sulfur-34 (34S) and sulfur-32 e2

S), which compose 

approximately 4.21 and 95.02 percent, respectively, 

of the natural abundance. The ratio 34Sp2

S relative 

to the standard Canyon Diablo Troilite (CDT), an 

iron sulfide from a meteorite, is expressed as 834

S 

using the same notation as for 8D and 818

0 . 

Ex olved gas was collected from well GS- 18 

in an inverted 60-mL glas bottle subm rged in 

sample water at the discharge outlet of the flow 

chamber. When filled, the bottle was closed with a 

poly seal cap while submerged. Gas samples were 

analyzed by gas chromatography at the USGS 

laboratory in Menlo Park, California, using standard 

methods. 

Although every effort was made to isolate 

zones within well bores using inflatable packers, the 

foll owing concerns about water samples were re ognized. Zones of low penneability in wells in which 

packers are installed can produce samples not representative of ambient ground-water quality because 

of extremely low recharge rates. Deep intervals 

Methods 9 
in wells can reflect contamination from water that 

cascaded downward from fractures in the overlying 

metavolcanic rocks prior to installation of the 

packers. Conversely, samples collected from the 

upper intervals of open boreholes might have contained water derived from the underlying slate unit. 

HYDROGEOLOGY 

The study area is in the western metamorphic 

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

sedimentary and volcanic rocks (see fig. 4) were 

deposited during the Jurassic period and then buried 

and metamorphosed during the Cretaceous period 

(Schweickert, 1981). Rocks in the vicinity include 

the Gopher Ridge volcanics of Jurassic age, a 

metavolcanic complex composed of one intrusive 

and five extrusive units, and the metasedimentary 

Salt Spring Slate, also of Jurassic age (Peterson, 

1985). Metavolcanic rocks in the area have weak 

to intense bedding, schistosity, and cleavage that 

trend N. 30° W. to N. and dip steeply to the 

northeast or east (Peterson, 1985; Martin, 1988). 

Geology and mineralogy of the area were 

described in greater detail by Hamlin and Alpers 

(1995). 

Massive-sulfide ore bodies are associated with 

the intrusive metavolcanic unit and consist primarily 

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

sphalerite [(Zn,Fe,Cd)S] (Peterson, 1985; Martin, 

1988). The following minerals have been identified 

in samples from waste-rock and tailings piles by 

optical examination and x-ray diffraction methods: 

bornite (CuSFeS4), chalcopyrite, pyrite, sphalerite, 

galena (PbS), brochantite [Cu4(S04)(OH)6]' covellite 

(CuS), halotrichite-pickeringite [(FeU,Mg) 

Ali S04)4 -22H20], and copiapite 

[FellFeill4(S04MOHh -20H20]. 

Geologic features controlling the movement 

and distribution of ground water at the Penn Mine 

include fractures in the bedrock fault planes, and 

the contact between the 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, associated 

with the Campo Seco Fault in the western part of 

the study area (fig. 4), dips about 20° NE. and was 

encountered in boreboles at depths between 45 and 

183 ft below land surface (see appendix 1; Hamlin 

and Alpers, 1995). The underlying slate unit has 

been identified as the Salt Spring Slate by Peterson 

(1985) and is significantly less permeable than the 

overlying metavolcanic rocks. The relatively 

impermeable slate 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 N. 20° W. 

A conceptual hydrogeologic section (fig. 4) 

oriented roughly east-west (fig. 3) was constructed 

using lithologic and topographic data from Heyl and 

others (1948), Davy Environmental (1993), and this 

study. Information on the location of the 

underground mine workings was taken from Heyl 

and others (1948). Section A-B-C-D-E (fig. 4) 

shows geologic features between the mine workings 

and slag area, as well as potential ground-water 

flow paths, such as along the Campo Seco Fault. 

Contours of the altitude of the contact between 

metavolcanic rocks and slate in the slag area are 

shown in figure 5. The disrupted area in the 

vicinity of well GS-7 may be explained by folding 

and (or) fault displacement (dotted lines in fig . 5). 

During drilling of well GS-7 (fig . 3), cuttings 

alternated between slate and metavolcanic rock, and 

the hole continually caved in, indicating the 

possible presence of a highly fractured or folded 

zone. In general, faults impede ground-water flow 

perpendicular to the fault surface and enhance flow 

along the fault surface. Northeast-trending faults in 

outcrops adjacent to the slag pile were mapped by 

Hunerlach and Alpers (1994). Davy Environmental 

(1993) also reported northeast-trending faults in 

other areas of the Penn Mine. On the basis of the 

sparse altitude data, the contact zone is interpreted 

as an anticlinal fold. Additional data defining the 

contact from new boreholes and (or) from 

geophysical surveys would help characterize the 

nature of structural deformation in this area. 

Identification of Fracture Zones 

The downhole acoustic televiewer records 

correlate well with the caliper logs. Fracture zones 

shown on televiewer images tend to be associated 

with large-diameter segments of the caliper logs. 

Graphical reproductions of the televiewer images 

for selected wells show the location and orientation 

of primary fractures in the boreholes (appendix 2). 

Well GS-16 (total depth 183 ft), located at the north 

abutment of Mine Run Dam, showed many large 

fractures (fig. 6); the most exten ive fractures were 

between 73 and 85 ft below land surface. 

10 Hydrogeology, Geochemistry of Acid Mine Drainage in Ground Water, Penn Mine and Camanche Reservoir 
West -- East SSW-- NNE 

SW -- - -----NE WNW-- ----ESE 

A 	 BCD E FEET 

500 

Reservoir I : 

(range) I I - slagl 

? 

" ? 

G8-20 G8-18 


I i G8-19 (projection) 


400 

G8-3 G8-16 	 : I waste rock It~ I I ~ ~ G8-8 I 


300 
 Camanche I I Mine Run Reservoir HR1 : ~ \ :1 l ~ 

200 

100 

Sea level 

100 

200 

300 

400 

500 

600 

700 

800 

1

-.......Ii.-;::;--'\,<;~ ~ '1 shaft #3 


(projection) 

y 

~? II 

300 level \I 

400 level "",~ Metavolcanic rocks "" ? 	

\I 

\I Slate 	 l

",,~ ? -<J==? 500 level .c::£ilit~;::::~rl- " 

Mine working 

r- Surface-water flow 

-<F= Ground-water flow 

Ground-water flow, direction -<l=C>­

~ 

dependent on Camanche 

Reservoir elevation 

Infiltration 

USGS well (dashed J: where projected) 

c . 	 \I , Q>~ 

',~o \1 

? ' &(9. 	 600 level ~;;;;:::;C2Wi:

. ,00 ,,<:- II 

I ',Q>Vfi II 

I ....: ~ II 

t .........: ~ 700 level tk:z::iCI:Il:::j \ , II 

Slate \ 	 '~ II \ 	 , . II 

, 	 , 900 level 


/ '~ II 

/ ' 1,000 II 


I Metavolcanic rocks ' -...!..evel II 


: 	 " 'II 

\ 	 " II , 	

? 	 II 

II 

I 

o 100 200 300 400 500 Feet ,I I " " " ---i o 30 60 90 120 150 Meiers 

Figure 4. Conceptual hydrogeologic section A-B-G-D-E constructed using data from Camanche Reservoir; wells 

GS-3, -8, -16, -18, -19, and -20; and Mine Run Reservoir. 

The fl owmeter tests were run in static and 

injection modes for selected wells. Results of these 

tests are included in app ndix 3. The flowmeter 

was lowered into the well in static mode, and 

readings were taken at several depths. Static tests 

were completed in boreholes OS-l1 , -12, and -1 6. 

Only well OS-16 yielded conclu ive results in the 

static mode (fig. 6): The data showed downflow of 

approximately 0.05 gaVmin between 80 and 115 ft 

below land surface and upflow rates of 0.04 to 0.07 

gaVmin between 20 and 70 ft below land surface. 

These static flow data indicate that the zone of 

highest conductance in well OS-16 is near the 80­

foot depth. 

rn injection mode, well OS-16 showed 

changes in flow at four depth intervals (fig. 6), the 

most significant of which was at about 80 ft. An 

injection rate of 3.1 gal/min was used for flow 

measurements at depths of 60 ft and greater. For 

depths I ss than 60 ft, the inj ction rate was 

reduced to 2.0 gal/min to improve the accuracy of 

the measurements (appendix 3). Apparent 

downflow rates of 1.7 to 2.2 gaVmin were recorded 

between depths of 15 and 50 ft below land surface; 

normalized to an injection rate of 3.1 gal/min, the 

downflow rate was constant within the uncertainty 

of the measurements between depths of 15 ft and 

75 ft (fig. 6; appendix 3). It is interpreted that no 

Hydrogeology 11 
Mine Run 

Dam 

o 100 200 300Feet I I I

I I I I 

o 30 60 90 Meters 

EXPlANATION 

~ Slag 

150 - _ ••••? Contour showing equal altitude of metavolcanic-slate contact; 

dotted and queried where structure uncertain (folded or faulted). 

Contour interval 10 feet. Datum is sea level 

.146 USGS well. Number is altitude, in feet, of top of slate unit. 

Datum is sea level 

Figure 5. Subsurface altitude of the metavolcanic-slate contact, Camanche Reservoir, Calaveras County, California. 

hydraulically significant fractures were present in 

this interval. A dramatic decrease of the downflow 

rate, from 3.0 to 0.20 gaVmin, was recorded 

between 75 and 85 ft below land surface, (fig. 6). 

The static and injection test data for well GS-16 

indicate that the most hydraulically active fracture 

zone is at a depth of about 80 ft below land surface 

and that Jess active fracture zones occur at depths of 

about 112 ft, 120 ft, and 160 ft below land surface. 

Hydraulic Characteristics of Fractured 

Bedrock 

Hydraulic characteristics of fractured bedrock 

were estimated for wells GS-1 through -8 by 

Hamlin and Alpers (1995). Values of hydraulic 

conductivity (10 and transmissivity (T) were 

estimated through (1) analysis of recovery data 

using the Cooper-Jacob straight-line method 

12 Hydrogeology, Geochemistry of Acid Mine Drainage in Ground Water, Penn Mine and Camanche Reservoir 
TELEVIEWER 


PHOTOGRAPHS 


WELL GS-16 

BOREHOLE FLOW, 

IN GALLONS PER MINUTE 

-4.0 -3.0 -2.0 ~ ( -0.20 0 0.20 

0 

20 0 

0 w STATIC () 

« 40 DATA

LI.. 

C[ 

::> 60 INJECTION TEST 

(j) DATA 

0 

Z 0

:3 80 

~ 

0 INTERPRETATION

--l 100

W 

CO 

tu 120 

w 

LI.. 

Z 140 .. J: 

Ia. 

w 160

0 

180 

~"""'----r!"'~ 15 

20 

75 

80 

110 

. 120 

.. 155 

Figure 6. Flowmeter data and acoustic televiewer logs for well GS-16. 

Hydrogeology 13 

(Driscoll, 1986) and (2) analysis of specific capacity 

data (Huntley and others, 1992). Specific depth 

intervals were tested in boreholes GS-l, GS-4, and 

GS-8 using inflatable packers to isolate selected 

zones. 

Using the Cooper-Jacob method, the highest 

calculated value for K was 57 ftId at well GS-5, 

which penetrates both metavolcanic rocks and slate, 

as do other wells. Flowmeter tests indicate that the 

most hydraulically active fractures are in the 

metavolcanic unit primarily near the contact with 

the underlying slate unit. Therefore, higher K 

values are attributed to metavolcanic rocks, and the 

largest volume of ground-water flow is expected to 

be in a zone along or adjacent to the contact 

between the metavolcanic and slate units. The 

lowest K value was 0.008 ftld at well GS-l B, which 

is open only to the slate unit. 

Values for T and K calculated from specific 

capacity measured in April 1992 were generally 

within one order of magn itude of values estimated 

usi ng the Cooper-Jacob straight-line method 

(Hamlin and Alpers, 1995). The HuntleyNommensen-Steffey specific-capacity method 

consistently yielded lower values for T and K. The 

median value of K for the metavolcanic unit, for 

both methods, was about 10 to 50 times higher than 

that for the slate unit (Hamlin and Alpers, 1995). 

The median value of K for both methods was 0.1 

ft/d in the metavolcanic unit. The median value of 

K for the slate un it ranged from 0.002 ftId 

(Huntley-Nommensen-Steffey method) to 0.01 ftld 

(Cooper-Jacob method). 

Observations made during construction of 

boreholes in November 1992 indicated high values 

of K at some sites. Intervals in wells GS-13, -14, 

and -15 near the slate-metavolcan ic contact yielded 

large volumes of ground water during drilling, 

probably from fractures in the metavolcanic rocks. 

Buildup of hydraulic pressure dUTing airlift purging 

of well GS-14 caused water to flow from well 

GS-B , about 10ft away, indicating a good 

hydraulic connection. The same fracture system 

provides a conduit for contaminated ground water, 

as discussed in the 'Water Quality" section of t.his 

report. 

Water Levels 

Ground-water levels fo r USGS wells at the 

Penn Mine from September 1992 to November 

1993 are given in appendix 4. Ground-water levels 

for wells GS-l through -8 for December 1991 

through August 1992 were presented by Hamlin and 

Alpers (1995). 

Changes in water level for wells GS-l A, -1 B, 

-3, -8A, -16, -18, -19, and -20 for various periods 

during 1992-93 are shown in figure 7. Water levels 

in wells are highest in the eastern part of the study 

area and lowest near Camanche Reservoir. Water 

levels in wells GS-4A, -5, -8A, and -14 

(appendix 4) were nearly identical to the water level 

in Camanche Reservoir (180-185 ft above sea level) 

during the period September 1992 through January 

1993 (well GS-8A shown in fig. 7A). This 

indication of good hydraulic connection is 

corroborated by high hydraulic conductivity in 

fractures in wells GS-5 and -8A (fig. 3) (Hamlin 

and Alpers, 1995). Well GS-5 is closest to 

Camanche Reservoir at the northwest end of the 

slag pile, and well GS-8A is about midway between 

Mine Run Dam and Camanche Reservoir (180-foot 

shoreline; fig. 3). 

The water level in weJl GS-16 closely 

correlated with the water level in Mine Run 

Reservoir (fig. 7A). This well is on the north 

abutment of Mine Run Dam (fig. 3). Water levels 

in well GS-1 6 were within about 2 ft of those in 

Mine Run Reservoir during the period of October 

1992 to January 1993, when Mine Run Reservoir 

levels were at or below about 245 ft above sea 

level. When Mine Run Reservoir levels rose above 

255 ft after March 1993, water levels in GS-16 

tracked at about 3 to 4 ft below those of Mine Run 

Reservoir. Water-level data (appendix 4) and 

geochemical data (discussed in the "Water Quality" 

section) indicate a strong hydraulic connection 

between well GS-J6 and Mine Run Reservoir 

through fractures in the metavolcanic rocks. 

Water-level for wells GS-J8 though -20 in 

the vicinity of shafts 3 and 4 are shown in figure 

7B. These wells are in the Hinckley Run drainage, 

with land-surface altitudes of about 280 ft (GS-20) 

and 362 ft (GS-18 and -19) above sea level. Shafts 

3 and 4 are inclined mine workings that plunge 70° 

to 80° northeast (Heyl and others, 1948). These 

shafts intersect production stopes and haulage 

tunnels at different levels (fig. 4) and have been 

filled with mine waste and soil near the surface. 

W II GS-18 intersects the "300 level " of the mine 

work.ings adjacent to shaft 3 at a depth of about 250 

it; well GS- 19 intersects shaft 3 at a depth of about 

140 fl, an area of the shaft that had been filled with 

mine waste jn 1978. Well GS-20 penetrates shaft 4 

at a depth of about 11 ft. The water levels in wells 

14 Hydrogeology, Geochemistry of Acid Mine Drainage in Ground Water, Penn Mine and Camanche Reservoir 
• •• 

260 

250 

240 

230 

220 

210 

200 

190 

~ 

W 

> 

W 

~ 

W '" 

en 170

W 

> 

0 

III 160 

300 '" ~ 

W 

UI 

u. 

z 295 ..i 

UI 

> 

W 

~ 

a: 290 UI 

~ 

~ '" 285 

280 

275 

270 

265 

A 	 :--- {:; 

Mine Run Reservoir 

.. ... .. .. 0 0 0 crao 

• ~ 

.. .. 0 

• well GS-1A (mv) 

0 well GS - 1 B (sl) 

.a- well GS-3 (mv+sl) 

'V well GS-8A (mv) 

{:; well GS-1.6 (mv) 

- reservoirs 

Nole; Unils intersected by wells are indicated by mY, metavolcanic; alld sl. slate 

f,\
 B ,IV \ 

rI 

-+­ well GS-18 

-0­ well GS-19 

-0-­ well GS-20 

artesian flow 

260LS~ O~N~D~~J F~M ~A~ J~ J~A~~S~O~N~~D 

1992 	 1993 

..J 

W 

>

UI 

..J 

~ 1/1 

W 

> 

0 

CD 

C 

Iii 

~ 

i: 

irl 

> 

~ 

a: 

...

w 

< 

~ 

2850 

284 .8 

284.6 

284.4 

284.2 

284.0 

283.8 

283.6 

283A 

283.2 

283 .0 

282.8 

282.6 

282.4 

282.2 

282.0 

I ' 

• 

• 

• 	 J,

., • J 

~ 

~ l ~~:"-"-,-'::':-'-'-'-'::':-'-.>...J..J.~~,=,,-,-"-,=,=.J..J...L-,::,:, l " " I , " .l 0 10 	 20 30 40 80 90 100 

FLOW RATE, IN GALLONS PER MINUTE 

­

Figure 7r Water levels in Camanche and Mine Run 

Reservoirs, and in selected adjacent wells at Penn 

Mine, September 1992-November 1993 (A); and in 

wells GS-18, -19, and -20 at Penn Mine, November 

1992-November 1993 (B), Calaveras County, 

Califomia. 

GS-18 and -20 were nearJy identical, except during 

pump ing, indicating hydraulic connection between 

shafts 3 and 4 through the underground mine 

workings, as reported by Heyl and others (1948). 

The water level in well GS-1 8 rose above the 

altitude of well GS-20, causing artesian flow from 

well GS-20 during the period January to May 1993. 

The differences in the water levels in well GS-19 

relative to wells GS-18 and -20 probably reflect 

reduced hydraulic conductance caused by the 

presence of mine waste in shaft 3. During the 

period of artesian discharge from well GS-20 (fig. 

7B), numerous seeps were observed in the bedrock 

in the vicinity of shaft 4. The flow rates measured 

from these seeps and well GS-20 were positively 

correlated with water levels in well GS-18 (fig. 8) . 

Increasing flow from well GS-20 and adjacent seeps 

corres

18, which 

ponded 

reflected 

with risin

risin

g 

g 

w

gr

at

ou

er 

n

levels 

d-water 

in 

levels 

well GS

in 

­the 

mine workings. 

The overall hydraulic gradient from Mine 

Run Dam is westward toward Camanche Reservoir 

(see fig. 4). However, the hydraulic gradient can 

vary considerably with changes in the level of 

Camanche Reservoir and to a lesser extent with the 

level of Mine Run Reservoir. Furthermore, the 

direction of the hydraulic gradient between ground 

water in the slag area and Camanche Reservoir is 

controlled by the level in Camanche Reservoir. 

Figure 8. Relation between flow rate from seeps at 

well GS-20 (shaft no. 4) and water level in well GS-18 

(300-foot level, near shaft no. 3) at Penn Mine, 

Calaveras County, California . 

Hydrogeology 15 
When Camanche Reservoir levels are low, as in the 

period from September 1992 through January 1993, 

gradients clearly are toward Camanche Reservoir. 

When the level of Camanche Reservoir is above 

about 220 feet, as in the period from May to 

October 1993 when the slag area was inundated, the 

gradients likely are reversed. The correlation of 

ground-water levels in the slag area with the level 

of Camanche Reservoir indicates that there is good 

hydraulic connection between the two, probably 

through fractures in the metavolcanic rocks. 

WATER QUALITY 

Results of Sampling 

Water-quality data for April and Dcember 

1992 and January and July 1993 are summarized in 

table 1. The USGS wells were sampled in April 

and December 1992; Mine Run Reservoir and two 

Utility District weUs were sampled in December 

1992. A seep and one artesian well were sampled 

in January] 993, and another seep was sampled in 

July 1993. Summarized in table 2 are exsolved-gas 

data for well GS-18, which penetrates the mine 

workings near shaft 3 (fig. 3). 

As part of the quality-control program, field 

equipment blanks were run through the sampling 

process, including filtration and preservation, in 

April and December 1992. The concentrations of 

most constituents detennined in the field equipment 

blanks were less than detection limits. Calcium, 

magnesium, sulfate silica, aluminum, iron, and zinc 

were pres nt at concentrations near their detection 

limits in one of the two field blank samples and 

below their detection limits in the other; chloride 

was present at concentrations near its detection limit 

in both fi eld blanks (table 1). Properties measured 

in the fie ld included specific conductance, pH, 

temperature, dissol ved oxygen, and redox potential. 

A depth profile for dissol ved oxygen and 

temperature was compiled for Min Run Reservoir 

at 1- and 6-foot depths using a 3-L (liter) van Dom 

grab sampler. 

During April 1992. values for specific 

conductance ranged from 1,810 !-IS/cm 

(micfosiemen s per centimeter) at well GS-2 to 

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

water ranged from 3.7 at well OS-SA to 7.8 at well 

GS-2. Water t mperatures ranged from 17.5°C at 

well GS-S to 19.5o

C at well GS-3 (table 1). 

Samples for analysis of water quality were 

collected in December ] 992 from wells installed in 

1991 and 1992 in the slag area and the mine 

workings (areas of hafts 3 and 4) and from Mine 

Run Reservoir (fig. 3; table 1). Specific 

conductance ranged from 1,710 !-IS/cm at well GS19 to 9,300 /-lS/cm at Mine Run Reservoir at the 6­

foot depth. The pH of the water sampled in 

December 1992 ranged from 2.8 (GS-20 and Mine 

Run Reservoir at 1- and 6-foot depths) to 6.2 at 

GS -4B. A pH value of about 11 for well GS-12 in 

the slate unit was assumed to result from 

contamination from the cement plug above the 

bentonite seal at the bottom of the 6-inch PVC 

casing. Therefore, water-quality data from well GS12 were not included in table 1 and were not used 

to evaluate the ground-water chemistry. 

Temperatures ranged from ] 3.So

C in Mine Run 

Reservoir at the 6-foot depth to 19.5o

C in wells OS3 and -18 (table 1). 

Comparison of water-quality data for April 

and December 1992 (table 1) for five wells sampled 

on both occasions indicates transient behavior 

consistent with a contaminant plume in a dynamic 

hydraulic setting. AU wells howed increases in 

specific conductance with time; four of five weIJs 

showed increases in copper, zinc, cadmium, iron, 

and aluminum, and three of five showed increases 

in sulfate. During the same period, some wells 

showed decreases in pH. Rising specific 

conductance, metal, and sulfate concentration and 

falling pH reflect a higher proportion of acid 

drainage in ground water, consistent with the 

interpretation that acid drainage in ground water 

was migrating toward Camanche Reservoir (fig. 4) 

in a prograding plume during this period. 

Distribution of Acid Mine Drainage 

Dissolved constituents at the Penn Mine site 

are derived from oxidation of sulfi de minerals and 

from dissolution of associated a1um.inosi]jcate and 

oxid -hydroxide minerals in waste-rock piles exposed at several locations on the site. Percolation 

and infiltration of acid mine drainage to ground 

water will lower pH and raise concentrations of 

metals and sulfate in the ground water. Another 

possible source of these constituents could be the 

dissolution of soluble ulfate mineral in bedrock 

inter eeted by the underground mine workings. The 

generation of acid mine drainage was discussed in 

grealer detail by Hamlin and Alpers (1995). 

16 Hydrogeology, Geochemistry of Acid Mine Drainage in Ground Water, Penn Mine and Camanche Reservoir 
Table 1. Chemical data for water samples from Mine Run Reservoir, wells, and two seeps at the Penn Mine, 

Calaveras County, California 

[State well number: All wells are in 4NIlOE, township and range. MRR, Mine Run Reservoir; MRD, Mine Run Dam. DC, 

degrees Celsius; ft, foot; fJS/cm, microsiemen per centimeter; mg/L, milligram per liter; fJg/L, microgram per liter (divided 

by 1,000 = milligrams per liter); <, actual value is less than value shown; (5D, delta deuterium; (5 180, delta 18-oxygen; (534S, 

delta 34-sulfur; --, no data) 

SRe­ pH water DeRth Eh, M!lgne­ clfic whole Temper- Oxygen Calcium, Sodium, Well or State Date of Redox SlUm, con­ field ature, dis- dis- dis­ saf!1ple well well, poten­ dis­ duct­ (stand­ water solved solved solved site No. total tial solved ance ard (0C) (mg/L) (mg/L) (mg/L) (ft) (mV) (mg/L) (fJS/cm) units) 

GS-IA 4GIA 4-17-92 

12-15-92 

80 

80 

4,950 

4,980 

5.1 

4.6 

460 

499 

18.0 

18.5 0.2 

480 

470 

350 

400 

280 

270 

GS-IB 4GIB 4-18-92 200 5,980 7.2 263 18.5 480 260 810 

GS-2 4G2 4-14-92 200 1,810 7.8 319 18.5 .9 72 34 320 

GS-3 4G3 4-15-92 

12-19-92 

200 

200 

4,600 

5,660 

4.8 

5.1 

451 

446 

19.5 

19.5 

1.7 

.2 

440 

510 

550 

690 

57 

100 

GS-4A 4G4A 4-16-92 

4-16-92 

55 

55 

2,430 

2,430 

5.7 

5.7 

387 

387 

18.5 

18.5 

210 

200 

260 

240 

29 

31 

GS-4B 4G4B 4-16-92 

12-15-92 

80 

80 

3,120 

3,360 

6.6 

6.2 

400 

428 

19.0 

16.5 2.0 

360 

390 

250 

310 

83 

63 

GS-4C 4G4C 4-18-92 200 4,380 7.3 293 19.0 380 270 360 

GS-5 4G5 4-13-92 

12-18-92 

201.5 

201.5 

3,430 

4,300 

5.4 

4.6 

438 

467 

17.5 

18.0 

.5 

.5 

360 

430 

320 

380 

49 

62 

GS-6 4G6 4-15-92 

4-15-92 

401 

401 

18,000 

18,000 

4.2 

4.1 

484 

484 

18.5 

18.5 .5 560 600 

290 

270 

3,200 

3,100 

GS-7 4G7 4-14-92 202 2,390 4.9 565 18.5 1.0 300 170 28 

GS-8A 4G8A 4-14-92 

12-04-92 

76 

76 

5,660 

6,230 

3.7 

3.8 

500 

432 

18.5 

18.0 

.2 

.2 

480 

440 

580 

620 

60 

64 

GS-8B 4G8B 4-17-92 200 6,200 4.3 420 18.5 460 460 390 

GS-ll 4G 11 12-13-92 61 3,940 3.9 453 19.0 1.0 400 300 64 

GS-14 4G14 12-14-92 66 6,750 3.6 18.0 .3 490 710 67 

GS-15 4G15 12-19-92 120 6,380 3.5 536 18.0 .1 480 690 110 

GS-16 4G16 12-16-92 183 6,380 3.5 536 18.0 460 940 72 

GS-18 4GI8 12-16-92 260 4,480 3.8 422 19.5 .2 460 150 67 

GS- 19 4G1 9 12-16-92 162 1,710 3.1 664 18.5 6.1 30 120 11 

GS-20 

GS-201 

4G20 12-16-92 

1-28-93 

23 

23 

5,790 

3,850 

2.8 

4.2 

604 18.0 380 

540 

240 

130 

46 

54 

GS-20-Seep 1-28-93 23 3,880 4.2 500 130 54 

MRR-A2 

MRR-A3 12-22-92 

12-22-92 

8,000 

8,000 

2.8 

2.8 

686 14.0 

14.0 

4.7 

4.7 

430 

280 

810 

450 

73 

45 

MRR-B2 12-22-92 9,300 2.8 728 13.5 3.9 

MRD-Seep 7-07-93 4,000 3.7 30.0 510 270 43 

W-JD 12-19-92 48 6,450 3.5 594 20.5 2.1 490 720 57 

W-5D 12-22-92 49 8,080 3.6 508 17.0 0.5 450 920 71 

Field blanks 4-21-92 

12-22-92 

0.07 

<0.02 

0.03 

<0.01 

<0.20 

<0.20 

See footnotes at end of table. 

Water Quality 17 
Table 1. Chemical data for water samples from Mine Run ReseNoir, wells, and two seeps at the Penn Mine, 

Calaveras County California-Continued 

Solids, Potas­ Chlo­ Fluo Alum­ Cad­ ­ Well Sulfate, Bromide, Silica, residue or sium, ride, ride, inum, mium, Date dis­ dis­ dis­ at 180 °C, sample dis­ dis- dis- dis­ dis­ solved solved solved dis­ site solved solved solved solved solved (mg/L) (mg/L) (mg/L) solved (mgIL) (mg/L) (mg/L) (f.lg/L) (f.lgIL) (mgIL) 

GS-IA 4-17-92 11 3,500 97 1.5 .88 42 5,580 3,800 2, 100 

12-15-92 10 3,700 78 1.3 .39 47 5,540 10,000 2,300 

GS- IB 4-18-92 18 3,000 570 .90 4.5 13 6,090 30 440 

GS-2 4-14-92 5.5 450 240 .20 1.6 16 3,750 <10 <10 

GS-3 4-15-92 3.9 3,700 21 .30 .10 59 5,290 4,800 2,600 

12-19-92 5.8 4,400 36 .40 .15 72 6,590 3,800 3,700 

GS-4A 4-16-92 2.7 1,400 8.1 <.10 .26 42 2,320 40 1,100 

4-16-92 2.7 1,500 9.2 .10 .27 42 2,340 50 1,000 

GS-4B 4-16-92 2.8 2,100 54 .20 1.3 32 3,190 20 530 

12-15-92 2.7 2,300 26 .20 .24 37 3,510 60 900 

GS-4C 4-18-92 7.6 2,200 320 .30 1.3 22 3,870 30 520 

GS-5 4-13-92 6.4 2,900 16 .20 .22 41 3,840 240 3,000 

12-18-92 6.3 2,900 25 .30 .13 44 4,320 3,800 2,900 

GS-6 4-15-92 19 4,000 4,100 2.8 8.3 34 15,000 52,000 680 

4-15-92 20 2,900 5,000 3.2 6.5 35 14,500 51,000 690 

GS-7 4-14-92 3.1 1,700 20 .80 .39 38 2,610 3,600 630 

GS-8A 4-14-92 2.6 5,900 60 9.8 .32 11 0 9,020 220,000 L,400 

12-14-92 2.3 5,700 51 4.8 .48 120 8,670 250,000 1,500 

GS-8B 4-17-92 9.1 4,400 290 6.4 3.9 48 7,530 89,000 970 

GS-ll 12-13-92 2.3 2,900 25 2.9 .42 56 4,570 49,000 500 

GS-14 12-14-92 2.8 6,400 36 6.4 .51 140 10,000 370,000 1,500 

GS-15 12-19-92 5.1 6,300 67 4.5 .34 140 9,660 380,000 1,500 

GS-16 12-16-92 2.5 8,300 40 7.0 1.3 140 12,800 560,000 1,900 

GS-18 12-16-92 16 3,200 23 1.7 7.3 53 5,060 210,000 50 

GS- 19 12-16-92 13 810 24 .70 .47 77 1,230 38,000 80 

GS-20 12-16-92 8.5 4,200 18 .80 .49 120 6,230 280,000 410 

GS-201 1-28-93 13 2,900 22 1.3 60 1,280 6,000 20 

GS-20-Seep 1-28-93 12 2,900 21 1.3 60 3,690 5,900 20 

MRR-A2 

MRR-A3 12-22-92 

12-22-92 

<.10 

1.4 

8,500 

4,800 

38 

22 

.40 

.90 

1.9 

.94 

190 

130 

13,200 

3,820 

720,000 

280,000 

1,700 

940 

MRR-B2 12-22-92 

MFUD-Seep 7-07-93 2.3 2,900 22 2.3 .06 70 4,460 33,000 510 

W-lD 12-19-92 1.6 6,000 29 6.8 .24 150 8,990 290,000 1,300 

W-5D 12-22-92 2.0 8,100 38 .90 .080 150 12,200 500,000 1,800 

Field blanks 4-21-92 <0.10 <0.10 0.30 <0.10 <om <0.1 5 <10 <10 

12-22-92 <0.10 0.50 0.10 <0.10 <0.01 0.30 <1 30 <LO 

See footnoes at end of table. 

18 Hydrogeology, Geochemistry of Acid Mine Drainage In Ground Water, Penn Mine and Camanche Reservoir 
Table 1. Chemical data for water samples from Mine Run Reservoir, wells, and two seeps at the Penn Mine, 

Calaveras County, California-Continued 

Manga­ oD 0180 0180 034S Copper, Iron, Lead, Silver, Zinc, Well or nese, (per water sulfate sulfate Date dis­ dis- dis- dis­ dis­ sample dis­ mil, (per mil, (per mil, (per solved solved solved solved solved site solved v­ v­ v­ mil, (flglL) (llglL) (flglL) (11 gIL) (llglL) (11 gIL) SMOW) SMOW) SMOW) CDT) 

GS-IA 4-17-92 

12-15-92 

9,800 

13,000 

160 

1,900 

<1 

<I 

27,000 

33,000 

<1.0 

<1.0 

140,000 

190,000 

-36.5 

-37.4 

-3.40 

-3 .31 -0.1 l.9 

GS-IB 4-18-92 <10 <10 <1 20,000 <1.0 18,000 -40.0 -3.85 

GS-2 4-14-92 <10 <10 <1 70 <1.0 20 -56.0 -7.65 

GS-3 4-15-92 

12-19-92 

12,000 

11,000 

60 

80 

<1 

<1 

25,000 

38,000 

<1.0 

<1.0 

150,000 

250,000 

-35.0 

-32.1 

-3.45 

-2.32 -0.8 1.5 

GS-4A 4-16-92 

4-16-92 

1,100 

1,100 

<10 

<10 

<1 

<1 

980 

850 

<1.0 

<1.0 

39,000 

34,000 

-51.5 

-50.0 

-6.60 

-6.65 

GS-4B 4-16-92 

12-15-92 

130 

400 

20 

10 

<1 

<1 

260 

120 

<1.0 

<1.0 

12,000 

26,000 

-48.5 

-46.5 -6.30 -6.01 -0.8 2.0 

GS-4C 4-18-92 30 <10 <I 790 <1.0 5,900 -48.5 -6.25 

GS-5 4-13-92 

12-18-92 

2,600 

6,100 

130 

3,200 

<1 

<1 

1,900 

4,600 

<1.0 

<1.0 

78,000 

94,000 

-46.5 

-42.9 

-5.40 

-5 .04 0.5 1.7 

GS-6 4-15-92 

4-15-92 

12,000 

13,000 

930 

950 

4 

4 

24,000 

25,000 

<1.0 

<1.0 

120,000 

170,000 

-35.0 

-33 .0 

-2.90 

-2.90 

GS-7 4-14-92 14,000 100 <I 23,000 <1.0 83,000 -58.0 -8.20 

GS-8A 4-14-92 

12-14-92 

86,000 

88,000 

110,000 

150,000 

<1 

<1 

58,000 

52,000 

<1.0 

<1.0 470,000 

-32.5 

-33 .9 

-2.65 

-2.6 1 1.0 1.6 

GS-8B 4-17-92 5,400 94,000 7 44,000 <1.0 300,000 -38.0 -3 .85 

GS-II 12-13-92 35,000 83,000 <1 37,000 <1.0 210,000 -48.8 -5.84 -0.2 2.0 

GS-14 12-14-92 84,000 92,000 <I 55,000 <1.0 460,000 -27.7 -1.38 -1.0 1.5 

GS-15 12-19-92 80,000 63,000 3 51,000 <1.0 450,000 -28.4 -1.47 1.0 

GS- l6 12-16-92 120,000 66,000 3 170,000 <1.0 630,000 -15.2 1.40 -0.7 1.4 

GS-18 12-16-92 130 82,000 170 2,600 <1.0 400,000 -49.8 -7.39 2.4/ 1.8 4.1 

GS-19 12-16-92 1,600 22,000 25 1,300 <1.0 1,800 -56.9 -7.99 1.8 2.3 

GS-20 

GS-201 

12-16-92 

1-28-93 

36,000 

60 

540,000 

660,000 

14 

13 

15,000 

9, 100 

<1.0 

<1.0 

62,000 

41 ,000 

-47.2 

-48.8 

-6.81 

-7.31 

1.6 

2.5 

2.6 

4.8 

GS-20-Seep 1-28-93 60 620,000 13 9, 100 <1.0 48,000 -48.8 -7.32 2.3/2.2 4.6 

MRR-A2 12-22-92 

MRR-A3 12-22-92 

MRR-B2 12-22-92 

MRD-Seep 7-07-93 

110,000 

62,000 

25,000 

160,000 

110,000 

90 

<1 

7 

5 

51,000 

28,000 

14,000 

< 1.0 

<1.0 

<1.0 

570,000 

200,000 

96,000 

-8.4 

-25.4 

-3.6 

-27.4 

2.55 

-2. ]2 

3.78 

-1.54 

1.1 

-0.7 

1.9 

1.5 

W-lD 12-19-92 30,000 54,000 190 62,000 <1.0 390,000 -21.7 -0.41 

W-SD 12-22-92 130,000 62,000 <1 150,000 <1 .0 620,000 -15.9 1.31 

Field blanks 4-21 -92 

12-22-92 

<10 

<10 

lArtesian flow. 

26 feet below water surface. 

31 foot below waler surface. 

4 

<3 

<1 

<I 

<1 

<1 

<1.0 

< 1.0 

<3 

5 

Water Quality 19 
Table 2. Chemical data, expressed as percentages 

by volume, for gas exsolved from water pumped from 

well G8-18 (shaft 3 area) at Penn Mine, Calaveras 

County, California, January 1993 

Sample 1 Sample 2 

Helium (He) 0.0033 0.0036 

Hydrogen (H2) .0006 .0005 

Argon (Ar) . 759 .750 

Oxygen (02) .147 .314 

Nitrogen (N2) 54.98 54.39 

Methane (CH4) .739 .745 

Carbon dioxide (CO2) 45.54 45.99 

Ethane (C2H6) .0020 .0017 

Hydrogen sulfide (H2S) <.0005 <.0005 

Totals 102.17 102.19 

The sl ag materials exposed near Camanche 

Reservoir contain greater than 6 percent zinc by 

weight (Wiebelt and Ricker, 1948). No published 

data are available for the cadmium content of the 

slag; however, seven grab samples of massive slag 

analyzed by inductively coupled plasma after 

HFIHNOi HCI04 digestion were found to have 

cadmium concentrations ranging from 14 to 1,700 

ppm (parts per million) (mean =280 ppm); the 

same seven samples showed a range in zinc 

concentration from 3.2 to 25 weight percent (mean 

= 7.8 weight percent) and a range in copper of 0.2 

to 2.2 weight percent (mean =0.8 weight percent) 

(M. Parsans, Stanford Univ., written commun., 

1996). Thus, the slag cauld be a source of zinc, 

capper, and cadmium to. ground water, especiaUy if 

leached under acidic canditians. 

Dissalved metals found at elevated 

concentratians in acidic water at the Penn Mine 

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

Water with pH values less than 4.5 can contain 

se eral hundred to several thousand milligrams of 

dissolved aluminum p r liter (Hem, 1985; 

Nordstrom and BaU, 1986; Alpers and Nordstrom, 

1991). Dissolved aluminum in ground water at the 

Penn Mine ranged from less than 10 to 720,000 

flg/L (micrograms per liter) (table 1). Copper may 

be present in concentrations as high as a few 

hundred milligrams per liler in acid mine drainage 

(Hem, 1985). Values for dissolved copper in 

ground water from tbe Penn Mille ranged from less 

than 10 to 130,000 flg/L (table 1). Concentrations 

of dissolved iron in ground water at the Penn Mine 

ranged from less than 10 to. 660,000 flg/L (table 1). 

Dissolved zinc in ground water from the Penn Mine 

ranged from 20 to 630,000 flg/L (table 1). 

Cadmium is found with zinc, including the sulfide 

mineral sphalerite and the sulfosalt mineral series 

tetrahedrite-tennantite, in most crustal environments; 

these minerals are present at Penn Mine. Dissolved 

concentrations of cadmium in ground-water samples 

from Penn Mine ranged from less than 10 to 

3,700 flg/L (table 1). 

The areal distribution of selected 

water-quality properties and constituents was 

plotted. The distribution map for pH in December 

1992 is shown in figure 9. The other major 

constituents of acid mine drainage (iron, aluminum, 

and sulfate) and associated trace elements (copper, 

zinc, cadmium) show distributions similar to that of 

pH. Acid mine drainage is characterized in ground 

water by values of pH less than 5. Low values of 

pH are associated with high concentrations of 

sulfate at Penn Mine (fig. 10). 

Concentrations of sodium and chloride at 

Penn Mine tend to increase whh depth and were 

highest in the slate unit (Hamwl and Alpers, 1995). 

In the 200-foot boreholes, where the rock units 

were separated by infl atable packers in the vicinity 

of the metavolcanic-slate contact (GS-l , -4, and -8), 

chloride concentration ranged from 290 to 570 

mg/L in the slate intervals and from 8.1 to 97 mg/L 

in the metavolcanic rock intervals; sodium 

concentration ranged from 360 to 810 mg/L in the 

slate intervals and from 29 to 280 mgIL in the 

metavolcanic rock intervals (table 1). The highest 

concentrations of chloride (5,000 mg/L) and sodium 

(3,200 mg/L) were found in the 4oo-foot borehole 

(GS-6), which penetrated mare than 350 feet of the 

slate unit. These data strongly suggest that the 

source of sodium and chloride is associated with the 

slate unit. 

Another way to delineate the plume of acid 

mine drainage in ground water downgraclient from 

Mine Run Dam is by plotting the di tribulion of the 

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

and ISO. During the evaporation process, water 

molecules containing heavy isotopes tend to become 

concentrated in the residual water, and 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 OD and 01S0 values that lie on 

a line with a slope between 3 and 6 to the right of 

20 Hydrogeology, Geochemistry of Acid Mine Drainage in Ground Water, Penn Mine and Camanche Reservoir 
~Camanche ~~-y 

~ Reservoir 

5.1 

4.6 

•

6. 3.6 __...;;;;.-.5 4 

3.9 . 3.5 

A 4 

(42). 46. 

~ •• 5 ........ &
 . ..
 .. ... 
 ';,. >\. 
 ~- ,. 

=--~.to· (70)

/~ (49) 


Mine Run 


Dam 


o 100 200 300 Feet 

f-------+-I

I -----r"L-----r 

o 30 60 90 Meters 

EXPLANATION 

Lines or equal pH based on • USGSweU 

December 1992 data 6, EBMUDweD 

Lines of equal pH based on April 1992 data 3.5 pH value, December 1992 

(49) pH value , April 1992 

Figure 9. Areal distribution of pH in ground water in metavolcanic rocks at Penn Mine, Calaveras County, Califomia, 

December 1992. 

the meteoric line (Craig and others, 1963). This The slope of this line suggests that the ground 

phenomenon is observed in a plot of isotope data water downgradient from Mine Run Darn represents 

from ground water and Mine Run Reservoir at the the mixing of evaporated water from Mine Run 

Penn Mine (fig. 11 ). The data can be fit by Reservoir with nonevaporated ground water. This 

least-squares linear regression (,-2=0.985), which interpretation would suggest that the chief source of 

gi ves a line described by the equation dissolved metals and sulfate in the ground water is 

leakage from the unlined Mine Run Reservoir. 

Wells GS -2, -7, and -19 show the least enrichment 

(3) in heavy isotopes and exhibit among the lowest 

Water Quality 21 
9,000 

8,000 tII: 

W

I­

::i 

II: 

W 

0.. 

en 

::;; 

<I:

II: 

(!I 

::::;

..J 

:i 

~ 

u.i I­

<I: 

L1­ ..J 

::J 

en 

7,000 t6,000 

5,000 

4,000 

3,000 

~ 

I:>. 

rP 

\l 

\l 

~ 

V 

B3 

/ 0 GS-20 (non-artesian) 

~ 

W CHl 

ell. 

• 

0 0 

Wells 

e GS-IA 

O GS-IB

• GS-2 

A GS-3 

'" GS-4A

• GS-4B 

0 GS-4C 

0 GS-5 

0 GS-6 

(} GS-7 

\l GS-BA 

V GS-BB 

0 GS-ll 

0 GS-14 

a GS-I S 

I:>. GS-16 

~ GS-IB 

® GS-19 

B3 GS-20 

~ GS-20SEEP 

<$I MRD SEEP 

~ Mine Run Reservoir 

0 

2,000 

\GS-20 (anesian) 

GS-20SEEP 

e:. , 

• • <i> 

1,000 

• 

pH 

0 ,----.----,----,-----,__--,----,----, 

& 

~ 0 

::;; 	 '<>' I:>. 

en 	 ~ 

~ ~ -20 	 0 

II: 	 0 

I-	

w ~ & ..J<I: ~~ ~== V if Wells II:Z "= w<l: e GS-tA 

o..w ,~ ..::; ~A 0 GS-IB ZU-0 	 ~ GS-2 •

~ GS-3 

::J<I: -40 ~ 0 GS-4A ~Z ?If v' -w '" ffi::;; ~ 0 . • GS-4B 

I-C 	 q,0 GS-20 (non artes,an) 0 GS-4C

::JII: Qf ~.o 0 GS-S

Cc 

W<l: ~ .0 0 GS-6

(::, GS-7 <l: Z ::9~ '"., 1-< ..JI- (50 GS-20 (ariesIan) \l GS-BA 

wen V GS-BB e- GS-20 SEEP Co ts 0 GS-tt I- 0 GS-14 -60 w II GS-tS > I:>. GS-16 i= 

< 	 <> GS-IB ..J W (j) GS-19

II: 	 83 GS-2O 


E3 GS-2O SEEP 


(i» MRD SEEP 


& Mine Run Reservoir 

-80 L--__--L____ __---l_____'_____.L_______'___~ 

-10 -8 -6 -4 -2 o 

DELTA OXYGEN-18, IN PER MIL 

RELATIVE TO STANDARD MEAN OCEAN WATER (V-SMOW) 

Figure 10. Relation between sulfate concentration and 

pH in ground water and in Mine Run Reservoir at 

Penn Mine, Calaveras County, California, April and 

December 1992, and January and July 1993. 

levels of contamination by acid mine drainage. 

Samples from Mine Run Reservoir and wells GS-14 

and -16 show the highest enrichment in heavy 

isotopes and highest levels of acid-mine-drainage 

contamination. The areal distribution of 318

0 in 

ground water is similar to the distributions of 

sulfate (table 1) and pH (fig. 9). This observation 

is consistent with Mine Run Reservoir providing the 

source of acidic, evaporated water found in the acid 

plume. 

Geochemical Correlations 

COITe]ations among dissolved constituents 

indicate the effects of acid mine drainage on 

ground-water quality at the Penn Mine. Dissolved 

iron correlates positively with sulfate in ground 

water, c osi tent with oxidation of pyrite as the 

probable source of these constituents (Hamlin and 

Alpers, 1995). Other constitueoLS, such as 

aluminum and other dissolved metals, show a 

similar correlation with pH. 

Figure 11. Stable-isotopic composition of water 

samples from wells, seeps, and Mine Run Reservoir 

at Penn Mine, Calaveras County, California, April and 

December 1992, and January and July 1993. 

Concentrations of dissolved metals in natural 

waters can be limited by solubility equilib- rium 

with solid phases. The concentrations of ferric iron 

and aluminum in ground water at the Penn Mine 

also are strongly dependent on pH (Hamlin and 

Alpers, 1995). Geochemical modeling wiLh the 

W ATEQ4F code (Ball and Nordstrom, ] 991) suggests that dissolved ferric iron is probably in equilibrium with a form of hydrous ferric oxide or 

ferrihydrite [nominally Fe(OH)3] (Hamlin and 

Alpers, 1995). Sulfate concentrations are highest in 

low-pH waters, whereas iron concentrations can be 

limited by solubility of a sulfate mineral such as 

hydronium-bearing jarosite [(K,Na,H30) Fe3 

(S0 4MOH)61 (Alpers and others, 1989) or 

schwertmannite [Fe80 8(0H)6S0 4J (Bigham, 1994). 

Similarly, aluminum concentrations appear to be in 

equilibrium with gibbsite [Al(OH)3]' except in 

ground water with pH values less than 5 (Hamlin 

and Alpers, 1995). Again, sulfate becomes dominant at low pH and aluminum can be in equilibrium 

with an aluminum-sulfate mineral such as jurbanite 

[AISOiOH) ·5HzO]. 

22 Hydrogeology, Geochemistry of Acid Mine Drainage in Ground Water, Penn Mine and Camanche Reservoir 
Metal ratios can be useful indicators of 

anomalous chemical analyses resulting from either 

analytical error or geochemical processes. The ratio 

of zinc to cadmium (ZnJCd) is commonly consistent 

within a single mineral deposit. The Zn/Cd ratio 

for all but three of the water samples (table 3) falls 

within the range of 11 to 420, which is consistent 

with ZnJCd ratios in ores and mine waters from 

other massive sulfide deposits (Nordstrom and Ball, 

1985). ZnJCd ratios are considerably higher for 

samples taken from wells GS-18 (8,000), GS-20 

(2,100 duri ng artesian flow on January 28, 1993), 

and the GS-20 seep (2,400). Values of the ratio of 

zinc to copper (ZnJCu) fall between 1 and 200 for 

all water samples (table 3), except again for GS-18 

(3,100), GS-20 (680 during artesian flow), and the 

GS-20 seep (800). Water samples collected from 

well GS-20 in December 1992 did not have similar 

characteristics because artesian flow at well GS-20 

had not yet begun. Subsequent artesian flow from 

weI! GS-20 and related seeps reflected discharge 

from the underground mine workings (characterized 

by water samples from GS-18) in response to rising 

hydraulic head. 

The most likely explanation for the 

anomalously high values of the Zn/Cd and Zn/Cu 

ratios is that cadmium and copper have been 

preferentially scavenged by aqueous hydrogen 

sulfide (H2S) in the underground mine workings. 

DiToro and others (1990) indicated the following 

sequence for metal sulfide solubility from most 

soluble to least soluble: 

MnS > PeS> NiS- ZnS > CdS-PbS > CuS >HgS. 

Therefor , cadmium and copper sulfides are less 

soluble then zinc sulfide and would be 

preferentially scavenged by any H2S produced by 

sulfate reduction. 

Heavy stable i otopes (bD and ( 18

0 ) were 

enriched in partially evaporated water from Mine 

Run Reservoir and in ground water affected by acid 

drainage from the reservoir (fig. 11). In contrast, 

ground water from the mine workings (GS-18 and 

OS-20 seep) falls on or near the global meteoric 

water line (fig. 11), showing no enrichment of these 

heavy isotopes. 

Another distinctive characteristic of the water 

from wells GS-] 8, GS-20, and the GS-20 seep is 

the presence of exsolving gas. Chemical analysis of 

the exso] ved gas from well GS-18 (table 2) 

indicates somewhat reducing conditions; the gas 

Table 3. Weight ratios of metals in ground-water and 

surface-water samples from Penn Mine, Calaveras 

County, California 

[All ratios reported with two significant figures. MRR, 

Mine Run Reservoir; MRD, Mine Run Dam; Zn, zinc; Cd, 

cadmium; Cu, copper. --, not determined because one or 

both of the concentrations was below the detection level] 

Well name or Date Zn/Cd ZnlCu sample site 

GS-IA 4-17-92 67 14 

12-15-92 83 15 

GS-IB 4-18-92 41 

GS-3 4-15-92 58 13 

12-19-92 68 23 

GS-4A 4-16-92 35 35 

4-16-92 34 31 

GS-4B 4-16-92 23 92 

12-15-92 29 65 

GS-4C 4-18-92 11 200 

GS-5 4-13-92 26 30 

12-18-92 32 15 

GS-6 4-15-92 180 10 

4-15-92 250 13 

GS-7 4-14-92 130 5.9 

GS-8A 12-04-92 310 5.3 

GS-8B 4-17-92 310 56 

GS-l1 12-13-92 420 6.0 

GS-I4 12-14-92 310 5.5 

GS-I5 12-19-92 300 5.6 

GS-16 12- 16-92 330 5.3 

GS-18 12- 16-92 8,000 3,100 

GS-19 12- 16-92 23 1.1 

GS-20 12-16-92 150 1.7 

GS-201 1-28-93 2,100 680 

GS-20-Seep 1-28-93 2,400 800 

MRR-A2 12-22-92 340 5.2 

MRR-A3 12-22-92 210 3.2 

MRD-Seep 7-07-93 190 3.8 

W-lD 12-19-92 300 13 

W-5D 12-22-92 340 4.8 

1Artesian flow. 


26 feet below waler surface. 


31 foot below water surface. 


Water Quality 23 
3 I I I I I 

i GS-20 (artesian) 0 IE 

== ~ 00, 0

-

> 

2­ -

0: W (!) - I­ :! c:z: I!l == :: £ GS-20 (non-artesian) a:: Z Wc:z: c.. w &

Zo 1 - l- V 

-:'0 

~Z Wells 

Z

'c:z: w 0 • GS-1A W== .& GS-3 

>-C • GS-4B " >< 0: D­ O GS-5 ­ O c:z: \l GS-8A c:z:C ·0 0 GS-11 I-Z ...Jc:z: 0 GS-14 WI4 

(!) ~ GS-1'6 C OO G5-18 0 EEl G5-19 lW • G5-20 -1 I- 0 I!l ­

> ~ G5-20 5EEP

i= (!) W-1D

c:z: £ W-5D ...I W & Mine'Run Reservoir a:: 

I I I I I -2 

0 2 3 4 5 6 

DELTA SULFUR-34, IN PER MIL, 


RELATIVE TO CANYON DIABLO TROILITE (COT) 


Figure 12. Relation between delta oxygen-18 and delta sulfur-34 in 

dissolved sulfate at Penn Mine, Calaveras County, California. 

is dominated by carbon dioxide and nitrogen, with from well GS-18 (table 1) indicate redox 

very little oxygen, and considerable methane and disequilibrium among dissolved gases and between 

traces of hydrogen. Exsolution of dissolved gas is the dissolved gases and the aqueous phase. The 

probably caused by the reduction in ambient redox disequilibrium could be caused by mixing of 

pressure as water is brought to the surface from the two or more waters with different dissolved gasses 

m.ine workings. This occurred during pumping at and dissolved metals in the underground mine 

well OS-IS (160 ft below the ground-water table) workings. Stable-isotope data for sulfur and oxygen 

and at well GS-20 during periods of artesian flow in dissolved sulfate are also consistent with the 

from shaft 4 of the mine workings. hypothesis of sulfate reduction and possible fluid 

mixing in tbe mine workings. 

The relatively reducing environment required 

for reduction of sulfate to H2S is consistent with the The stable isotopic composition of dissolved 

exsolved-gas chem.istry for well GS-18 (table 2), sulfate (table I) also can be used to distinguish 

which includes considerable methane (CH4) and water samples f.rom wells GS-18 and -20 and 

traces of hydrogen (H2). The presence of detectable associated seeps from water samples taken elseoxygen (02) in the exsolved gas, at concentrations where at the Penn Mine. The contrast in isotopic 

of 0.15 to 0.31 volume percent (rable 2), and the composition for the dissolved sulfate from the 

relatively oxidizing value of Eh in water underground mine workings is shown in figure 12; 

24 Hydrogeology, Geochemistry of Acid Mine Drainage in Ground Water, Penn Mine and Camanche Reservoir 
values of 834S in sulfate in three samples derived 

from the underground mine workings (GS-18, 

GS-20, while artesian, and GS-20-Seep) range from 

+4.1 to +4.8 per mil, about 3 per mil heavier than 

samples from Mine Run Reservoir and the wells 

down- gradient from Mine Run Dam, which have 

834S values ranging from + 1.0 to +2.0 per mil. 

Water samples from wells GS-19 and GS-20 (nonartesian) have 834S values intermediate between the 

samples from the underground mine workings and 

those from the Mine Run Dam area, indicating 

probable mixing. Values of 8 18

0 in sulfate range 

from -1.0 to +2.5 per mil, with the heaviest values 

in the sulfate from the mine workings. 

With the exception of stable isotopes (80 and 

8 180 in water, and 834S and 8 18

0 in dissolved 

sulfate) and dissolved copper and cadmium 

concentrations, the chemistry of acidic water in the 

underground mine workings (wells GS-18 and GS20, while artesian) is similar to water in Mine Run 

Reservoir and to the associated acidic ground-water 

plume. Alpers and others (1994) described these 

data and presented several possible explanations. 

The most likely explanation is that reducing 

conditions have led to bacterially mediated suLfate 

reduction in the mine workings, which has depleted 

the dissolved sulfate in the lighter isotope 32S, 

causing an increase in the 834S value of the residual 

sulfate. A similar effect would account for the 

Iligher values of 8 18

0 in dissolved sulfate. 

Alternative explanations involve lateral zoning of 

lhe relative abundance of sulfide minerals and the 

dissolution of primary sulfate minerals such as 

anhydrite, which occurs in some similar massive 

sulfide deposits. Neither of lhese alternative 

explanations is likely, however, given the lack of 

anhydrite and gypsum in the mine waste piles and 

no mention of these minerals in previous reports 

(for example, Heyl and others, 1948). Therefore, 

partial sulfate reduction is the favored hypothesis to 

explain the isotopic data and the relatively low 

aqueous copper and cadmium concentrations 

relative to zinc; copper and cadmium would be 

preferentially scavenged by hydrogen sulfide 

produced by sulfate reduction. 

FLOW RATE AND METAL LOADING OF 


CONTAMINATED GROUND WATER 


The flow rate of ground water in the fTactured 

metamorphic-rock aquifer between Mine Run Dam 

and Camanche Reservoir was estimated by 

'Available from East Bay Munkipal Utility District 

Hamlin and Alpers (1995) using mathematical 

relations developed for porous media. According to 

Darcy's law, the flow rate, q, through a given crosssectional area of aquifer is 

(4) q = KIA, 

where K is the hydraulic conductivity averaged over 

the thickness of the aquifer, A is the cross-sectional 

area, and I is the hydraulic gradient (Driscoll, 

1986). 

A rough estimate of the width of the plume, 

based on lines of pH equal to 5 (fig. 9) in a section 

of the plume defined by wells GS-IA, W-1D, and 

GS-3 (fig. 3), is about 100 ft. Water-level and 

pumping-rate data for these wells collected during 

water-quality sampling in April and December 1992 

were evaluated using the method described by 

Huntley and others (1992) to estimate values of 

hydraulic conductivity, K, for the metavolcanic 

rocks. Hamlin and Alpers (1 995) described this 

method and used it to estimate values of K for the 

metavolcanic and slate units. The analysis utilizes a 

relationship derived fo r transmissivity (T) and 

specific capacity (Qls) in fractured-rock systems: 

(5) T=0 .29(QIs)IlS 

where Q is the pumping rate and s is the draw down 

(Huntley and others, 1992). The values of T determined in this manner may be converted to hydraulic 

conductivity, K, by dividing by the saturated 

thickness of metavolcanic rocks. Estimated values 

of K are as follows: 0.2 ftld for GS-IA (December 

1992), OJ ftJd for W-ID (December 1992),0.8 ft/d 

for W-ID (Brown and Caldwell Consultants, written 

commun., 1991)', 0.01 ftld for GS-3 (April 1992; 

Hamlin and Alpers 1995), and 0.07 ftld for GS-3 

(December 1992). The median value of K from 

these data is 0.2 ftld for the metavolcanic rocks, 

which is similar to the value of 0.1 ftid previously 

determined by Hamlin and Alpers (1995) using data 

from all wells completed in the metavolcanic unit. 

The geometric mean of the five K values for wells 

GS-IA, GS-3, and W-ID also is 0.1 ftld. 

Saturated th.icknesses for wells GS-I A and -3 

and a width of 100 ft were used to estimate the 

cro s-sectional area of the plume in the metavolcanic rocks. The area of the polygon defined by 

Flow Rate and Metal Loading of Contaminated Ground Water 25 
the saturated parts of tbese wells is approximately 

5,750 fro The hydraulic gradient (a unitt ss 

quantity) in this part of the contaminant plume can 

be estimated by using water-level data from wells 

GS-l A and GS-SA (appendix 4), which lie 

approximately along the axis of the contaminant 

plume as shown by lines of equal pH (fig. 9). The 

hydraulic graclient between these two wells ranged 

from about 0.14 (such as during August througb 

December 1992) to zero (flat) or possibly a negative 

value (that is, west to east) during periods of 

submergence by Camanche Reservoir (such as 

during May through October 1993). Ther fore , a 

value of 0.07 is used to represent the average 

gradient. Using the geometric mean value of 0.1 

ftJd for the hydraulic conductivity of the 

metavolcanic rocks near wells GS-IA and -3, 

q = (0.1 ftJd) (5,750 tr) (0.07) =40 ft°/d. 

This is equivalent to a discharge of about 300 gal/d 

through this lOO-foot-wide section when the 

hydraulic gradient is 0.07. The actual value for q 

for the overall contaminant plume is dependent on 

the hydraulic gradient, which varies seasonally (see 

fig. 7A) and on tbe width of the contaminant plume 

which may vary over time and space. The 

hydraulic gradient for ground water was probably 

substantially flatter owing to increased pressure 

head wben the wells in the slag area were inundated 

by Camanche Reservoir during May througb 

October 1993. Depending on the degree of 

hydraulic connection, flow during such periods of 

submergence may have been from Camanche 

Reservoir to the ground-water system. 

Ranges for metal-transport rates can be 

estimated using the estimates of ground-water flow 

along a path leadjng toward Camanche Reservoir, 

and values for metal concentration determined for 

the contaminant plume (table 1). Wells GS-I A, 

W-ID, and GS-3 are along a line that is roughly 

perpenclicular to the axis of the plume and that 

approximates the width of the plume. Average 

metal concentrations determined in ground-water 

samples collected in April and December 1992 from 

these wells were: copper, 15 mglL; zinc, 220 

mglL; and cadmium, 2.4 mglL. 

Daily metal loadings within the part of the 

contaminant plume at the base of Mine Run Dam 

were calculated using the median value of hydraulic 

conductivity (0.1 ftld) applied to the portion of the 

plume that maintains a measurable hydraulic 

graclient. Using average metal concentrations and 

an estimated discharge rate of 40 fil/d (300 gal/d) 

for this part of the contaminant pl ume, the 

calcuJated metal loads within the plume were: 

copper, 17 g/d; zinc, 250 g/d; and cadmium, 

2.7 g/d. Previous metal loading estimates by 

Hamlin and Alpers (1995) lIsing a higher val ue of 

K (50 ftld) are considered not realistic because this 

higher value of hydraulic conductivity applies to a 

part of the flow sy tem [for example, wells GS-4A, 

-5, -SA, and -14 (fi gs. 3 and 7)] that has a much 

hall ower hydraulic gradient, the direction of which 

appears to be highly variable depending on 

fluctuations in Camanche Reservoir levels. 

Treatment of Mine Run Reservoir with lime 

during winter 1993 caused precipitation of dissolved 

solids and significantly reduced the concentration of 

dissolved metals. The effects of lime treatment and 

a shallower hydraulic gradient may have limlted 

metal loadings to the plume during that period. 

SUMMARY 

The Penn Mine site encompasses an area of 

about 140 acres in the Foothill copper-zinc belt in 

northwestern Calaveras County, California. About 

10.5 mi of underground workings were excavated to 

yield several acres of mill tailings and waste rock 

now exposed on the surface. Slag from smelters 

was disposed of in a I,SOO-foot-Iong area adjacent 

to the fonner Mokelumne River channel in an area 

now frequently inundated by Camanche Reservoir. 

Historically, contaminated surface runoff from the 

mine flowed directly to the Mokelumne River; after 

the construction of Camanche Dam in 1963, the 

surface runoff flowed into the Camanche Reservoir. 

In an attempt to control cliscbarge of contaminated 

surface water from the mine, diversions and 

impoundments were constructed in 1978. Use of 

sulficlic waste rock and mine tailings La construct 

dams and dikes, coupled with recirculation of 

contaminated water between impoundments, could 

have unintentionally enhanced the formation of 

acidic, metal-rich water. Altbough the impoundment system has greatly reduced surface clischarges 

from the mine, the re ults of thjs study indicate that 

contamination of underlying ground water occur 

through fractures in bedrock under the unlined 

impoundments. This contaminated water continues 

to flow through a fractured-rock aquifer toward 

Camancbe Reservoir. To neutralize acidic drainage, 

lime treatment of water in the lowennost impoundment was initiated in 1993; pH was adjusted to a 

val ue greater than 7 for a short period of time, bUl 

the impoundment has since been allowed to resume 

its untreated condition. 

26 Hydrogeology, Geochemistry of Acid Mine Drainage in Ground Water, Penn Mine and Camanche Reservoir 
Geologic controls over the movement and 

distribution of ground water at the Penn Mine 

include fractures in bedrock, faults, and the contact 

between the principal rock types in the area. 

Fractures that transmit ground water are present 

chiefly near the base of the metavolcanic unit, 

which overlies a metasedimentary unit that is 

significantly less permeable. This contact zone acts 

as a conduit that transmits water along its strike, 

which is generally N. 200 W. In a similar manner, 

ground-water flow along a fault surface generally is 

enhanced; whereas flow perpendicular to a fault 

surface generally is impeded. 

The estimates of hydraulic conductivity were 

highest for fractured intervals of the metavolcanic 

unit. The lowest values of hydraulic conductivity 

were associated with the metasedimentary (slate) 

unit. The mean hydraulic conductivity for the 

metavolcanic unit was about 10 to 50 times higher 

than the hydraulic conductivity for the slate unit. 

These results support the concept that the contact 

zone between the metavolcanic and slate units is as 

a conduit for ground-water flow. 

The hydraulic gradient for ground water in 

the slag area is generally from Mine Run Reservoir 

toward Camanche Reservoir. The slope of this 

gradient is affected by seasonal changes in recharge 

and in the water level of Camanche Reservoir. The 

average hydraulic gradient in the vicinity of shafts 3 

and 4 generally f !lows the topography toward and 

along the Hinckley Run drainage. During January 

to May 1993, water levels rose in these shafts and 

numerous seeps developed near shaft 4 and well 

GS-20. Chemical data indicate that the source of 

the seepage from shaft 4 was water from the 

underground mine workings. 

Acid-drainage constituents form a plume in 

ground water in the metavolcanic unit between 

Mine RUD Dam and Camanche Reservoir. The 

plume is characterized by low pH values, by 

enriched heavy stable isotopes of hydrogen and 

oxygen in water (indicating evaporation), and by 

high concentrations of sulfate and dissolved metals. 

The highest concentrations of dissolved sodium and 

chloride were associated with the slate unit, 

indicating a source in this unit. The enrichment of 

heavy stable isotopes of hydrogen and oxygen in 

the water making up the contaminant plume 

indicates that Mine Run Reservoir is the likely 

source of contaminated water. 

The composition of water from wells GS-18 

and -20, which penetrate the underground mine 

workings, indicates a geochemical environment 

different from that of ground water down gradient 

from Mine Run Dam. Copper concentrations in 

water from the mine workings (GS-18 and -20) 

were 60 to 130 IlglL; whereas in ground water 

downgradient from Mine Run Dam, copper 

concentrations were as high as 130,000 IlglL. Zinc 

concentrations were similarly elevated in water from 

the mine workings (41,000 to 400,000 11 gIL ) and in 

ground water downgradient from Mine Run Dam 

(as high as 630,000 11 giL). The relatively lower 

copper concentrations in water from the underground mine workings may be the result of preferential scavenging (relative to zinc) by hydrogen 

sulfide, which is produced by sulfate reduction. 

Another distinctive characteristic of the water from 

the underground mine workings is the presence of 

exsolving gas containing hydrogen and methane, 

probably produced under somewhat reducing conditions. Isotopes of sulfur and oxygen in dissolved 

sulfate support the hypothesis that sulfate reduction 

is occurring in the underground mine workings. In 

contrast, water samples from wells downgradient 

from Mine Run Dam yielded dissolved sulfate that 

was similar isotopically to sulfate from the wastewater impoundments, showing no evidence of 

sulfate reduction. 

The plume of acidic ground water downgradient from Mine Run Reservoir is roughly 100ft 

wide at the base of Mine Run Dam. Discharge 

from the plume was estimated to be about 40 ft3

/d 

(300 gal/d). Actual values for disc barge vary with 

plume width, bydraulic gradient, and the level of 

Camanche Reservoir. Corresponding daily mass 

flows of dissolved metals in the contaminant plume 

toward Camanche Reservoir were estimated to be 

17 g for copper, 250 g for zinc, and 2.7 g for 

cadmium. These estimates could be refined by 

additional ground-water monitoring and by 

numerical modeling of ground-water flow. 

References 

Alpers, C.N., Hamlin, S.N., and Rye, R.O., 1994, Stable 

isotopes (O,H,S) dislingujsh sources of acid 

drainage at Penn Mine, California: Abstract of 

the Eighth International Conference on Geochronology, Cosmocbronology, and Isotope Geology, 

U.S. Geological Survey Circular 11m, p. 4. 

References 27 
Alpers, C N., and Nordstrom, O.K., 1991, Geochemical 

evolution of extremely acid mine drainage 

waters at Iron Mountai, 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, CN., Ball, lW., and Nordstrom, O.K., 1989, 

Solubility of jarosite solid solutions precipitated 

from acid mine waters, Iron Mountain, 

California, U.S.A.: Sciences Geologiques, 

Bulleti.n, v. 42, no. 4, p. 281-298. 

Ball, lW., and Nordstrom, O.K., 1991, User's manual for 

W ATEQ4F, with revised thermodynamic data 

base and test cases for calculating speciation of 

major, trace, and redox elements in natural 

waters: U.S . Geological Survey Open-File 

Report 91-183,193 p., one 5'A-inch diskette. 

Bigham, J.M. , 1994, Mineralogy of ochre deposits 

formed by sulfide oxidation, chap. 4 in Jambor, 

lL., and Blowes, D.W., eds., The environmental 

geochemistry of sulfide mine-wastes: 

Mineralogical Association of Canada, Short 

Course Handbook, v. 22, p. 103-132. 

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., 3 appendices. 

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

the western Sierra Nevada metamorphic belt, 

California: U.S. Geological Survey Professional 

Paper 410, 70 p., 11 pis., in pocket. 

Clark, W.B., and Lydon, P.A., 1962, M ines and mineral 

resources of Calaveras County, California: 

Californi a Division of Mines and Geology, 

County Report 2,214 p., 4 pis. in pocket 

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

exchange effects in the evaporation of water. 

1. Low-temperature experimental results: Journal 

of Geophysical Research, v. 68, no. 7, 

p. 5079-5087. 

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. 

DiToro, D.M., Mahoney, J.D ., Hansen, OJ., Scott, KJ., 

Hicks, M.B., Mayr, S.M ., and Redmond, M.S., 

1990, Toxicity of cadmium in sediments: The 

role of acid volatile sulfide: Environmental 

Toxicology and Chemistry, v. 9, no. 12, 

p. 1487-1502. 

Driscoll, FG., 1986, Groundwater and wells (2d ed): St. 

Paul, Minn., Johnson Division, 1089 p. 

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

copper and zinc from the Penn Mine area on 

king salmon (Oncorhynchus Tshawytscha) and 

steel head trout (Sa/rno Gairdneri) in the 

Mokelumne River Basin, California: California 

Department of Fish and Game, Environmental 

Services Branch, Administrative Report 78- 1, 

42 p. 

Golder Associates Inc., 1996, Draft Environmental 

Impact Report for the Penn Mine Site LongTerm Solution Project: unpub. report prepared 

for the East Bay Iv:.unicipal Utility District and 

the Central Valley Regional Water Quality Control Board, 632 p. 

Hamlin, S.N., and Alpers, CN., 1995, 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: U.S. 

Geological Survey Water-Resources 

Investigations Report 94-4040, 45 p. 

Hem, J.D., 1985, Study and interpretation of the chemical characteristics of natural water (3d ed.): 

U.S. Geological Survey Water-Supply Paper 

2254, 264 p., 3 pis. in pocket. 

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

fractures with a slow-velocity borehole 

flowmeter: Canadian Geotechnical Journal, 

v. 23, no. I, p. 69-78. 

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

zinc-copper mine, Calaveras County: California 

Division of Mines Bulletin 144, p. 61-84. 

Hunerlach, M.P .• and Alpers, C N., 	L994, Analysis of 

fracture orientations in surface outcrops and 

boreholes in the vicinity of an acidic groundwater plume at Penn Mine, Calaveras County, 

California: EOS, Transactions, American 

Geophysical Union, v. 75, no. 44, supplement, 

p.234. 

Huntley, David, Nommensen, Roger, and Steffey, Duane, 

1992, The use of specific capacity to assess 

transmissivity in fractured-rock aquifers: Ground 

Water, v. 30, no. 3, p. 396-402. 

Makita, S.N. and Fujii, Roger, 1992, Quality ass urance 

practices of the U.S. Geological Survey 

laboratory in Sacramento, California: U.S. 

Geological Survey Open-File Report 91-522, 

23 p. 

Martin, 	R.C, 1988, Volcanogenic massi ve sulfide belt of 

the western Sierra Nevada Mountains: Geology, 

v. 41 , p. 	195-204. 

28 Hydrogeology, Geochemistry of Acid Mine Drainage In Ground Water, Penn Mine and Camanche Reservoir 
Nordstrom, D.K. , and Ball, J.W., 1985, Toxic element 

composition of acid mine waters from sulfide 

ore deposits, in Fernandez-Rubio, R., ed., 

Second International Mine Water Symposium, 

September 1985, Granada, Spain: Madrid, Spain, 

School of Mines, Department of Hydrogeology, 

p.749-758. 

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

behavior of aluminum in acidified surface 

waters: Science, v. 232, no. 4746, p. 54-56. 

Paillet, FL, Crowder, R., and Hess A..E., 1996, Highresolution flowmeter logging applications with 

the heat-pulse flowmeter: Journal of 

Environmental and Engineering Geophysics, 

v. 1, p. 1-11. 

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

1987, Characterization of fracture permeabality 

with high-resolution vertical flow measurements 

during borehole pumping: Ground Water, v. 25, 

no. 1, p. 28-40. 

Paillet, F.L., and Kapucu, Kemal, 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. 

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

Calaveras County, California: U.S. Geological 

Survey Miscellaneous Field Studies Map 

MF-1797, scale 1:1 ,200, 2 sheets. 

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

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

geotectonic evolution of California: Englewood 

Cliffs, N.J., Prentice-Hall, p. 87-131. 

Wasserman, M.D., Rye, R.O., Bethke, P.M., and Arribas, 

Antonio, Jr., 1992, Methods for separation and 

total stable isotope analysis of alunite: U.S. 

Geological Survey Open-File Report 92-0009, 

20 p. 

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

slag dump and mine water, Calaveras 

County, California: 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. 02, 24 p. 

References 29 
Appendix 1. Lithologic logs and well-construction data from USGS monitoring wells GS-1 through GS-20 at 

Penn Mine site, Calaveras County, California 

[ft, foot; in. inch; dia., diameter; frags., fragments; --, no data] 

Depth of Depth of Depth of Depth of 

Well 

No. 

Depth 

(ft) 

Lithologic 

description 

10-in-dia. 

steel casing 

blank PVC 

casing l 

slotted 

PVC casingl 

inflatable 

packer(s) 

(ft) (ft) (ft) (ft) 

GS-I 0-15 

15-28 

28-70 

70-200 

Soil with pebbles 

Sandy, quartz, metavolcanic rock frags. 

Metavolcanic rock 

Slate 

0-6 0-40 80 

GS-2 0-30 

30-76 

76-202 

Unconsolidated 

material, slag 

Metavolcanic rock 

Slate 

0-6 0-40 

GS-3 0-10 

10-15 

15-26 

26-105 

105-202 

Unconsolidated 

material 

Slag 

Unconsolidated 

material 

Metavolcanic rock 

Slate 

0-6 0-30 

GS-4 0-1.5 

1.5-100 

100-202 

Unconsolidated 

material 

Metavolcanic rock 

Slate 

0-6 0-20 55,80 

GS-5 0-16 

16-76 

76-201 

Unconsolidated 

material 

Metavolcanic rock 

Slate 

0-6 0-30 

GS-6 0-24 

24-46 

46-401 

Slag 

Metavolcanic rock 

Slate 

0-6 0-30 

GS-7 0-18 

l8-38 

38-58 

58-202 

Slag 

Unconsolidated 

material 

Metavolcanic rock 

Mixed metavolcanic 

rock and slate 

0-6 0-40 0-58 

(3-in . 

dia.) 

See footnote at end of table. 

30 Hydrogeology, Geochemistry of Acid Mine Drainage in Ground Water, Penn Mine and Camanche Reservoir 
Appendix 1. Lithologic logs and well-construction data from USGS monitoring wells GS-1 through GS-20 at 

Penn Mine site, Calaveras County, California-Continued 

Depth of Depth of Depth of Depth of 

Well Depth Lithologic lO-in-dia. blank PVC slotted inflatable 

No. (ft) description steel casing casing' PVC casing' packer(s) 

(ft) (ft) (ft) (ft) 

GS-S 0-15 

15-63 

63-202 

Unconsolidated 

material, slag 

Metavolcanic rock 

Slate 

0-6 0-30 76 

GS-9 0-11 

11-20 

Unconsolidated 

material 

Metavolcanic rock 

0-3 0-10 10-20 

GS-I0 0-3.5 

3.5-25 

Unconsolidated 

material, slag 

Metavolcanic rock 

0-3 0-5 5-25 

GS-II 0-10 

10-61 

61 

Unconsolidated 

material, slag 

Metavolcanic rock 

Slate 

0-3 0-24 

GS-12 0-15 

15-63 

63-115 

Uncosolidated 

material 

Metavolcanic rock 

Slate 

0-7 0-71 

GS-13 0-10 

10-63 

Unconsolidated 

material, slag 

Metavolcanic rock 

0-3.5 0-20 

0-2S (4-in. 

dia.) 

2S-63 (4-in. 

dia.) 

GS-14 0-10 

10-63 

63 

Unconsolidated 

material, slag 

Metavolcanic rock 

Slate 

O-S 0-55 55-65 

GS-15 0-1 

1-59 

59-120 

Unconsolidated 

material 

Metavolcanic rock 

Slate 

0-7 0-74 

GS-16 0-IS1 

lSl-1S3 

Metavolcanic rock 

Slate 

0-3.5 O-S 

See footnote at end of table. 

Appendix 1 31 
Appendix 1. Lithologic logs and well-construction data from USGS monitoring wells GS-1 through GS-20 at 

Penn Mine site, Calaveras County, California-Continued 

Depth of Depth of Depth of Depth of 

Well 

No. 

Depth 

(ft) 

Lithologic 

description 

lO-in-dia. 

steel casing 

blank PVC 

casingl 

slotted 

PVC casingl 

inflatable 

packer(s) 

(ft) (ft) (ft) (ft) 

GS-17 0-80 Metavolcanic rock, 0-4.5 

altered 

GS-18 0-251 Metavolcanic rock, 0-3.5 0-4 

altered 

251 Top of mine workings, 

"300 level" near shaft 3 

260 Bottom of mine 

workings 

GS-19 0-140 Metavolcanic rock, 0-2.5 0-3.5 

altered 0-100 100-140 

140-150 Shaft 3 (2-in. (2-in. 

dia.) dia.) 

GS-20 0-11 Metavolcanic rock, 0-3.5 0-6 

altered 0-3 3-23 

11-23 Shaft 4 (2-in. (2-in. 

dia.) dia.) 

IDiameter of blank and slotted casing is 6 inches, unless otherwise indicated. 

32 Hydrogeology, Geochemistry of Acid Mine Drainage in Ground Water, Penn Mine and Camanche Reservoir 
Appendix 2. Geophysical and selected acoustic-televiewer logs from USGS monitoring wells GS-10, -11, -12, 

-13, -14, -15, -1 6, and -18 at Penn Mine site, Calaveras County, California 

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. 

Lowermost interval of borehole inaccessible 

to televiewer. 

Appendix 2 33 
Appendix 2. Geophysical and selected acoustic-televiewer logs from USGS monitoring wells GS-10, -11, -12, 

-13, -14, -15, -16, and -18 at Penn Mine site, Calaveras County, California-Continued 

WELL GS-10 


CALIPER LOG, 


IN INCHES 


5 6 7 

o .----...,----, 

20 

UJ 

0 

<l:: 

u.. 

a: 

:J 

(j) 

0 40 z 

<l:: 

-I 

~ 

0 

-I 

UJ 

a:J 

tUJ 

UJ 

u.. 60 

~ 

I 

ta. 

UJ 

0 

80 

100 L...-_---'-...I.-__....I 

34 Hydrogeology, Geochemistry of Acid Mine Drainage in Ground Water, Penn Mine and Camanche Reservoir 
UJ 

() 

« 

u. 

a:: 

:::> 

(f) 

a 

z 

:5 

~ 

0 

..J 

UJ 


OJ 


Iii 

UJ 

~ 

~ 

I 

le.. 

UJ 

0 

GAMMA LOG , 161NCH NORMAL TEMPERATURE, FLUID 

IN COUNTS RESISTIVI1Y, TELEVIEWER IN DEGREES RESISTIVITY, CALIPER LOG, 

PER SECOND IN OHM-METERS IMAGE FAHRENHEIT IN OHM-METERS IN INCHES 

o 20 40 o 1000 2000 62 64 66 68 4 6 8 10 1 2 5 6 7 0 ,..-----,---.. 

20 l

40 

~ 

60 

80 L...--......I.--..... 

Appendix 2. Geophysical and selected acoustic-televiewer logs from USGS monitoring wells GS-10, -11 , -12, 

-13, -14, -15, -16, and -18 at Penn Mine site, Calaveras County, California- Continued 

WELL GS-11 


Appendix 2 35 
WELL GS-12 

CALIPER LOG, TELEVIEWER 

IN INCHES IMAGE 

5 6 7 

o r----,.----, 

20 

w 

() 

<t: 

u.. 

a: 

::> 40 

en 

0 

z 

:) 

3: 

0 

....J 

w 60 

co 

IW 

W 

u.. 

Z 

I ­ .:: I­ 80 Cl. 

w 

0 

100 

Appendix 2. Geophysical and selected acoustic-televiewer logs from USGS monitoring wells GS-10, -11, -12, 

-13, -14, -1 5, -16, and -18 at Penn Mine site, Calaveras County, California-Continued 

36 Hydrogeology, Geochemistry of Acid Mine Drainage in Ground Water, Penn Mine and Camanche Reservoir 
GAMMA LOG, 16 INCH NORMAL TEMPERATURE, FLUID 

IN COUNTS RESISTIVITY, IN DEGREES RESISTIVITY, CALIPER LOG, 

PER SECOND IN OHM-METERS FAHRENHEIT IN OHM-METERS IN INCHES 

10 20 30 o 1750 3500 64 65 66 67 o 10 20 30 4 5 

w 

<..> 

« 

~ 

a: 20 ::::> 

(J) 

0 

Z 

~ 

3: 

0 

...J 

W 

co 

IW 

W 

~ 

Z 

I­ 60 lll. 

W 

0 

80 

Appendix 2. Geophysical and selected acoustic-televiewer logs from USGS monitoring wells GS-10, -11, -12, 

-13, -1 4, -15, -16, and -18 at Penn Mine site, Calaveras County, California-Continued 

WELL GS-13 

Appendix 2 37 
GAMMA LOG, 16 INCH NORMAL TEMPERATURE, FLUID 

IN COUNTS RESISTIVITY, IN DEGREES RESISTIVITY, CALIPER LOG, 

PER SECOND IN OHM-METERS FAHRENHEIT IN OHM-METERS IN INCHES 

o

o 

,...---,..--

5 10 15 

,..-----, 

o 2000 4000 62 64 66 o 30 60 567

w 

(.) 

« 

LL 

a: 20 :::> 

(/) 

Cl 

z 

« 

-I 

~ 

0 

-I 40 W 

CD 

ti 

w 

LL 

Z 

I 60 

ta.. 

w 

Cl 

80 

I 

I- ­

-

-

I 

Appendix 2. Geophysical and selected acoustic-televiewer logs from USGS monitoring wells GS-10, -11, -12, 

-13, -14, -15, -16, and -18 at Penn Mine site, Calaveras County, California- Continued 

WELL GS-14 

38 Hydrogeology, Geochemistry of Acid Mine Drainage in Ground Water, Penn Mine and Camanche Reservoir 
GAMMA lOG, 1 6 INCH NORMAL TEMPERATURE, FLUID 

IN COUNTS RESISTIVITY, IN DEGREES RESISTIVITY, CALIPER lOG, 

PER SECOND IN OHM-METERS FAHRENHEIT IN OHM-METERS IN INCHES 

o 750 1500 50 60 70 o 5 10 5 6 7 8 

I 

20 / -

I 

- -

-

-

-

- -

-

I 

50 100 

w 

() 

« -

cr:

u. 40 

::l 

(J) 

0 

z 

S 

;: 60 t­ 0 

.....I 

UJ 

co 

t 

UJ 

u. 

~ 80 

;IIel. 

W 

0 

100 

120 

I 

-

-

-

-

-

Appendix 2. Geophysical and selected acoustic-televiewer logs from USGS monitoring wells GS-10, -1 1, -12, 

-13, -14, -15, -16, and -18 at Penn Mine site, Calaveras County, California- Continued 

WELL GS-15 

Appendix 2 39 
GAMMA LOG, 


IN COUNTS 


PER SECOND 


w 60 

() 

« 

u.. 

a: 

:J 

(/) 

0 

z 80 « 

...J 

~ 

0 

...J 

W 

OJ 

I- 100 w 

w 

u.. 

z 

r

b: 120 w 

0 

16 INCH NORMAL TEMPERATURE, FLUID 

RESISTIVITY, TELEVIEWER IN DEGREES RESISTIVITY, CALIPER LOG, 

IN OHM-METERS IMAGE FAHRENHEIT IN OHM-METERS IN INCHES 

o 60r-_--.::,66r--_.:...;72 o 2 

I 

IIIIIII 

-

-

-

-

-

-

-

-

I I 

tt­

-

r 

tI I 

4 4 6 8 

I I 

-

-

-

-

-

-

-

-

-

I I 

180 

Appendix 2. Geophysical and selected acoustic-televiewer logs from USGS monitoring wells GS-10, -11, -12, 

-13, -14, -15, -16, and -18 at Penn Mine site, Calaveras County, California-Continued 

WELL GS-16 

40 Hydrogeology, Geochemistry of Acid Mine Drainage in Ground Water, Penn Mine and Camanche Reservoir 
Appendix 2. Geophysical and selected acoustic-televiewer logs from USGS monitoring wells GS-1 0, -11 , -12, 

-13, -14, -15, -16, and -18 at Penn Mine site, Calaveras County, California-Continued 

WELL GS-1 8 

CALIPER LOG, TELEVIEWER 

IN INCHES IMAGE 

5 6 7 

o ,..---,-----. 

20 

40 

60 

80 

w 

() 

~ 100 

ex: 

::> 

(/) 

a 

z 

::s 120 

3: 

0 

-I 

W 

[D

li:i 140 w 

u.. 

~ 

I ­ b: 160 w 

a J.'., 

I' : : 

180 , ;'j

;-­

200 

!,-' 

220 

240 

260 L..-_-L-_---I 

Appendix 2 41 
Appendix 3. Flowmeter data from USGS monitoring wells GS·1 0, -11, and -16 at Penn Mine site, Calaveras 

County, California, December 1993 

[Bladder: +. bladder in place and inflated; 0, bladder on tool but deflated. ~t, average of three or more repeated 

measurements of time elapsed between heat pulse and detection made over a span of two minutes or less. ft, foot; s, 

second; gal/min, gallons per minute; NF, no flow detected; --, no data] 

Well Depth Bladderl Flow ~t lI~t Flow Injection Normalized 

No. (ft) (+10 ) direction (s) ( lis ) (gal/min) rate (gal/min) f1ow2 (gal/min) 

Static tests 

GS-lO 

45 + NF3 NF <0.01 <0.01 

GS-ll 

85 + NF NF <.01 <.01 

GS- 16 

122 + NF <0.02 <.02 <.02 

55 + Up 12.5 .08 +.07 +.07 

30 + Up 19.0 .05 +.04 +.04 

20 + Up 22.0 .05 +.04 +.04 

40 + Up 16.0 .06 +.05 +.05 

60 + Up 17.0 .06 +.05 +.05 

85 + Down 14.5 .07 -.06 -.06 

110 + Down 14.5 .07 -.06 -.06 

115 + NF <.02 <.02 <.02 

70 + Up 13.5 .07 +.06 +.06 

Injection tests 

GS-16 

85 + Down 5.0 .20 -.20 3.1 -.20 

110 + Down 5.7 .18 -.17 3. 1 -.17 

122 + Down 28.0 .04 -.03 3.1 -.03 

145 + Down 22.0 .05 -.04 3.1 -.04 

173 + NF <.02 <.02 3.1 <.02 

163 + NF <.02 <.02 3.1 <.02 

154 + Down 18.0 .06 -.05 3.1 -.05 

122 + Down 18.5 .05 -.04 3.1 -.04 

115 + Down 7 .9 .12 -. il 3.1 -. 11 

110 + Down 4.5 .22 -.22 3.1 -.22 

85 + Down 4.6 .22 -.22 3.1 -.22 

75 0 Down 2.0 .50 -3.0 3.1 -3.0 

60 0 Down 1.9 .53 -3 .2 3.1 -3.2 

50 0 Down 3.0 .33 -2.0 2.0 -3.2 

40 0 Down 3.1 .32 -1.9 2.0 -3.1 

30 0 Down 3.0 .33 -2.0 2.0 -3.2 

20 0 Down 2 .8 .36 -2.2 2.0 -3.5 

15 0 Down 3.5 .29 -1.7 2.0 -2.7 

IAn inflatable bladder, when inflated, focuses the entire flow in the borehole through the flowmeter. Measurements with the 

bladder inflated (+) are accurate to within ±0.05 gal/min, and can resolve flow as small as 0.02 gal/min; measurements 

become very difficult to calibrate when flow exceeds 1.0 gal/min. Measurements made with packer defl ated (0) are 

accurate to within ±0.5 gal/min; these measurements are more nearly linear in the range of 1.0 to 5.0 gal/min. 

2Rate of injection during test ot GS-16 was reduced when measured downflow began to exceed 3.0 gal/min to keep flow 

within effective calibration range of the flowmeter; subsequent measurements are normalized to original injection rale using 

the method described by Paillet and others (1996) to account for the difference in magnitude of the flow regime. 

3NF denotes no flow response detected, at a level less than 0.02 gal/min. 

42 Hydrogeology, Geochemistry of Acid Mine Drainage In Ground Water, Penn Mine and Camanche Reservoir 
Appendix 4. Water level altitudes from USGS monitoring wells at Penn Mine site, Calaveras County, California, September 1992 to November 1993 

[Location of wells shown in figure 3. --, no data; ii, well inundated by Camanche Reservoir; aa, artesian flow] 

USGS well GS-IA GS-IB GS-2 GS-3 GS-4A GS-4B GS-4C GS-5 GS-6 GS-7 GS-8A GS-8B GS-9 

Date Altitude, in feet above sea level 

9-1 8-92 ]92.57 210.31 190.37 214.18 179.35 178.84 197.50 178.77 182.76 185.96 178.82 194.99 

10-28-92 192.37 21 0.57 190.13 213.21 180.48 179.98 197.48 179.89 183.05 185.73 179.95 194.65 

11-12-92 192.22 210.48 190.04 213.24 178.23 177.65 197.47 177.52 182.54 185.63 177.60 194.18 

12-10-92 192.64 210.67 177.36 175.00 197.50 182.25 174.43 194.13 

12-13-92 

12-1 4-92 197.47 194.05 

12-1 5-92 194.31 210.64 176.73 174.77 174.06 

12-16-92 

12-19-92 193.52 209.96 216.20 176.14 174.22 182.76 173.55 177.23 

12-31-92 183.19 

1-1 1-93 

1-12-93 197.16 210.18 197.79 176.39 192.37 174.55 184.87 190.03 174.64 193.31 

1- 15-93 

1-23-93 

1-28-93 

2- 10-93 

2-24-93 20 1.09 211.04 202.58 219.59 196.60 196.l6 197.50 196.14 193.24 196.44 196.19 194.36 

3-04-93 

3-10-93 

3-19-93 

3-29-93 

3-30-93 208.61 210.90 208.18 218.84 207.66 207.82 207.46 207.88 206.72 207.89 207.81 195.06 207.92 

4-15-93 

5-05-93 

5-28-93 ii ii ii ii ii ii 11 ii 11 ii 11 ii ii 

7-07-93 11 ii ii ii ii ii ii ii ii ii 11 11 11 

10-22-93 11 ii ii 11 ii ii 11 11 ii ii 11 11 ii 

11-23-93 

11-25-93 

> 

~ 

~ :J 

CL;;C. 

~ 

t; 
Appendix 4. Water level altitudes from USGS monitoring wells at Penn Mine site, Calaveras County, California, September 1992 to November t 

1993-Continued :J: 

'<

c.

.., Camanche 0 USGS well OS-1O OS-] 1 GS-]2 GS-]3 OS-14 GS-15 GS-] 6 OS-17 OS-1 8 GS- 19 OS-20 co 	 Reservoir] m 

0 

i5' Date 	 Allitude, in feet above sea level co 

~ 9-] 8-92 179.13 

Ii) 10-28-92 180.34 

~ 11 -12-92 177.84 177.31 177.81 242.48 265.82 267.63 178.00 n 

:::r ]2-10-92 174.85 	 267.37 268.67 267.44 174.82 CD 

12-I 3-92 196.02 174.79 174.34 174.33 173.48 268.52 270.09 268.64 174.47 

= 

~ 12-14-92 174.14 268.65 270.16 268.74 174.32

-< 12-1 5-92 196.05 174.48 172.52 [74.05 268.80 270.33 268.89 174.17 

0

- 12-16-92 	 268 .87 270.30 268 .98 174.00 

n 

~ 12-1 9-92 	 173.65 

a: 12-31 -92 271.61 272.20 271.65 172.60 

!: 1-11 -93 198.49 198.30 174.59 174.60 173.71 244.32 173.16 ::::Il 

CD 1-12-93 173.48 

c 1-15-93 175.25 280.81 175.04 ..,

!!. 	 1-23-93 2 10.52 283.29 aa 179.52 ::::Il 

I» 	 1-28-93 191.68 283 .66 288.90 aa 182.48 CD 

m 2- 10-93 282 .70 293.28 aa 188.92 

5' 2-24-93 214.75 196.46 213.21 196.13 195.98 194.99 253.62 283.30 294.94 aa 196.04 

Ii) 3-04-93 282.18 291.10 aa 198.82 ... 

0 	 3-10-93 281.94 291.31 aa 200.08 c:: 

::::Il 

c. 	 3-19-93 28 1.64 29 1.88 aa 202.22 

3-29-93 282.41 aa 207.48 :: 

I» 	 3-30-93 207.08 207.9 1 212.97 207.88 207.66 206.71 aa 207.88 CD 

.... 4-1 5-93 31 4.57 28 1.45 297.38 aa 213.52 

"tI 5-05 -93 252. 19 314.03 280.27 296.45 280.73 213.39 

CD 

::::Il 	 5-28-93 11 11 ii ji ii ii 25 1.35 313.04 278.74 290.43 278.11 221.40 ::::Il 

7-07-93 II 11 ii ii 11 11 252.76 31 2.97 276.77 287.30 276.59 231.12 i:S· 10-22-93 ii 11 ii ii ii 11 250.32 271.50 278.68 271.01 219.99 

CD 11-23-93 313.02 270.65 218.73 I» 

::::Il 11 -25-93 	 276.00 218.67 c. 

0 

III 

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Hamlin and Alpers-HYDROGEOLOGY, GEOCHEMISTRY, ACID MINE DRAINAGE, PENN MINE, CAMANCHE RESERVOIR