(RED)

CHROMATEX PLANT NO. 2

WEST HAZLETON, PA

EXTENT OF GROUNDWATER CONTAMINATION STUDY

PHASE 1

PREPARED FOR;CHROMATEX, INC.BY;

INTERNATIONAL EXPLORATION. INC577 S4CKETTSFORD ROAD

WAKMINSTER. PA 18974-1398• ( 2 1 5 1 398-7137

INTERNATIONAL EXPLORATION. INC.

577 SACKETTSFORD ROAD

WARMINSTER. PA 18974-1398

215 - 598-71 37

WU MAIL BOX 629O9666

TELEX 51O-6O1-O152

FAX 21 5-598-O847

June 28, 1988

Mr. Bill MarionCHROMATEX, INC.Valmont Industrial ParkWest Hazleton, Pa. 18201

Dear Bill:

Enclosed, please find 3 copies of the final draft of ourExtent of Groundwater Contamination Study of Chromatex Plant#2. Additional copies have been sent to those copied onthis letter.

One copy of this report has been sent to Mr. Richard Dulceyof the United States Environmental Protection Agency by Mr.Steve Engelmyer's Office on June 28, 1988 in order to meetthe time schedule.

Sincerely,

INTERNATIONAL EXPLORATION, INC.

John WalkerSenior Hydrologist

JW:cnh

Encl.

cc : Mr. RichMr. Steve EngelmyerMr. Bob Gadinski

t-e 1

(RED)

CHROMATEX PLANT NO. 2WEST HAZLETON, PA

EXTENT OF GROUNDWATER CONTAMINATION STUDYPHASE 1

Prepared for:

Chromatex, Inc.

INTERNATIONAL EXPLORATION, INC,577 SACKETTBFORD ROAD

WA«MIN«TER. PA 18974-1306(2)9) 388-7137 .

June, 1988

;ifi!AL(RED)

TABLE OF CONTENTS

PAGE NO.

INTRODUCTION . . . . . . . . . . . . . . . . . . . 1

SITE CHARACTERISTICS . . . . . . . . . . . . . . . 7

REGIONAL GEOLOGY AND HYDROGEOLOGY. . . . . . . . . 9

SITE GEOLOGY . . . . . . . . . . . . . . . . . . . 12

MONITORING WELL INSTALLATION . . . . . . . . . . . 15

GROUNDWATER QUALITY ANALYSIS . . . . . . . . . . . 20

WELL TESTING

PIEZOMETER TESTS . . . . . . . . . . . . . . . 26PUMPING TEST ON WELL #10A

Test Procedure and Results . . . . . . . . 32Aquifer Characteristics. . . . . . . . . . 36Effects of Pumping Test on Nearby Wells. . 39

GROUNDWATER FLOW AND VELOCITY

GROUNDWATER FLOW DIRECTION . . . . . . . . . . 42VELOCITY OF GROUNDWATER FLOW . . . . . . . . . 47

HYDROGEOLOGY OF THE PROJECT AREA

GENERAL. . . . . . . . . . . . . . . . . . . . 5 0UNIT 1: Perched Zone Water Table . . . . . . . 50UNIT 2: Shallow Unconfined Phreatic Zone ... 51UNIT 3: Deep Unconfined Phreatic Zone. . . . . 52UNIT 4: Confining Layer. . . . . . . . . . . . 53UNIT 5: Confined Zone. . . . . . . . . . . . . 53HYDRAULIC RELATIONSHIPS BETWEENINDIVIDUAL UNITS . . . . . . . . . . . . . . . 54APPLICATION OF PROJECT DATA TOCONTAMINATED RESIDENTIAL WELLS . . . . . . . . 55

SUMMARY AND CONCLUSIONS. . . . . . . . . . . . . . 57

REFERENCES . . . . . . . . . . . . . . . . . . . . 61

APPENDICES . . . . . . . . . . . . . Under Separate Cover

FIGURES, TABLES & EXHIBITS

PAGE NO

FIGURE 1: LOCATION MAP, CHROMATEX PLANT #2 . . . . 2

FIGURE 2: AREA FEATURES MAP. . . . . . . . . . . . 8

FIGURE 3: REGIONAL GEOLOGY IN THE VICINITYOF CHROMATEX PLANT #2 . . . . . . . . . . 10

FIGURE 4: DRAWDOWN IN CHROMATEX WELL #10ADURING 5.7 HOUR PUMPING TEST . . . . . . 33

TABLE 1: LITHOLOGIC LOG OF MONITOR WELL #10C ... 13

TABLE 2: MONITORING WELL CONSTRUCTION DETAILS. . . 16

TABLE 3: CHROMATEX MONITORING WELL PURGING DATA. . 21

TABLE 4: VOLATILE ORGANIC CHEMICALS DETECTEDIN CHROMATEX MONITORING WELLS . . . . . . 25

TABLE 5: PIEZOMETER TEST RESULTS:5A: SHALLOW WELLS. . . . . . . . . . . 295B: INTERMEDIATE WELLS . . . . . . . . 305C: DEEP WELLS . . . . . . . . . . . . 30

TABLE 6: WATER LEVELS WITH TIME IN NEARBYMONITORING WELLS DURING WELL #10APUMPING TEST (4/25/88). . . . . . . . . . 40

TABLE 7: WATER LEVEL MEASUREMENTS IN CHROMATEXMONITORING WELLS. . . . . . . . . . . . . 43

TABLE 8: WATER TABLE GRADIENTS ATCHROMATEX PLANT #2 . . . . . . . . . . . . 46

TABLE 9: CALCULATED SHALLOW GROUNDWATER FLOWVELOCITIES IN VICINITY OFCHROMATEX PLANT #2 . . . . . . . . . . . . 48

EXHIBIT I: MONITORING WELL LOCATIONS . . . . . Back Pocket

EXHIBIT II: GROUNDWATER FLOW DIRECTION. . . . . Back Pocket

f" ,V?I!\!*"<^-n\t(RED)

INTRODUCTION

In March, April and May of 1988, a hydrogeologic

investigation was conducted, by INTEX, in the vicinity of

Chromatex Plant #2 (Plant #2) in West Hazleton, Luzerne

County, Pennsylvania (Figure 1). This investigation was

conducted under an administrative consent order between

Chromatex, Inc. and the U.S. Environmental Protection

Agency. It was initiated after a preliminary investigation

by the U.S. EPA/TAT discovered high levels of contamination

by volatile organic chemicals (VOC's), primarily

trichloroethylene (TCE), in residential wells that were

nearby, and apparently hydraulically downgradient of, Plant

#2. Plant #2 uses TCE in its industrial processes, and

Chromatex, Inc. was named by the U.S. EPA as being a

possible responsible party with respect to the groundwater

contamination.

The investigation consisted of the drilling, testing and

sampling of 12 wells, of various depths, surrounding Plant

#2. It was conducted in compliance with a work plan

submitted to the U.S. EPA in February of 1988, which was

approved and became part of the consent order (INTEX, 1988).

Minor revisions in the work plan were made in the field

during the investigation, with prior approval of the U.S.

EPA and its on-site technical observer, Versar Corp.

- 1

FIGURE 1: LOCATION MAP, CHROMATEX PLANT #2, WEST HAZLETON, PA.

portion of the Conyngham, Pa., 7.5' quadrangle

2,000 Fr

The primary purpose of the Extent of Contamination Study was

to answer the questions set forth in the work plan,

submitted to the U.S. EPA by INTEX, in February of 1988:

What is the direction of groundwater flow in the

shallow phreatic zone beneath Chromatex Plant #2?

Does a groundwater divide exist in the shallow

phreatic zone beneath Chromatex Plant #2?

What is the degree and distribution of VOC conta-

mination?

What is the velocity of groundwater flow in the

shallow phreatic zone?

What head gradients and hydraulic connections exist

between the shallow phreatic zone and deeper zones

from which local residential wells withdrew water?

The answers to these questions should provide enough

information to allow for a determination as to whether or

not the property of Chromatex Plant #2 was a source of the

VOC contamination. Other questions that should be answered,

in part, by this investigation are:

What is the vertical distribution of VOC contami-

nation beneath Chromatex Plant #2.

What are the general hydrogeologic conditions of the

deeper phreatic zones beneath the site, with regard

to aquifers and confining layers?

3 —

Additional purposes of this investigation, as stated in

Section II of the U.S. EPA administrative consent order, are

to estimate the length of time that the VOC contamination

has been in the groundwater, and to develop information

which may be used in any possible future remediation of the

site.

This investigation was strictly hydrogeological in nature

and was not intended to explore or make conclusions on the

cause of the VOC contamination or how it came to be in the

groundwater, nor of its existence and distribution in

mediums other than the groundwater in the vicinity of Plant

#2.

Apparently,the only other hydrogeologic investigation

conducted in the area prior to the initiation of the extent

of contamination study was by EPA/TAT (Weston-SPER), in

October of 1987. This was an emergency response action

under the Superfund statute and consisted of sampling and

measuring water levels in the affected residential wells. A

soil gas survey was also conducted on, and adjacent to the

property of Plant #2. Trichloroethylene was found by

EPA/TAT in most of the residential wells in levels ranging

from 1.0 parts per billion (ppb) to 1,400 ppb.

Trichloroethylene was found in the soil gas in levels up to

10 parts per million (ppm). The findings of the report by

EPA/TAT stated that groundwater flows from the Chromatex

property toward the affected homes, and that relatively high

levels of volatile organic chemicals in the soil gas on the

Chromatex property suggest that the facility is a possible

source of the groundwater contamination.

Soil sampling was conducted, by INTEX, in November and

December of 1987, at various locations around the Plant #2

property. This investigation revealed a concentrated area

of soil contamination behind the building, near a retaining

wall, with TCE and 1,1,1 trichloroethane levels in the

hundreds of parts per million range. These concentrations

of VOC's in the soil indicate that this area is a probable

major source of groundwater and soil contamination. To

date, the cause of the contamination is not known.

A 10,000 gallon underground tank located in the front of

Plant #2, and used by Chromatex as an emergency overflow

receptacle, was also identified by EPA and the Pennsylvania

Dept. of Environmental Resources (D.E.R.), as a possible

source of the groundwater contamination. In November of

1987, this tank was found to be filled with water containing

TCE in the parts per million range, and several other VOC's

were also found in this water. Soil sampling conducted

immediately following the excavation of piping leading from

Plant #2 to the tank revealed TCE contamination in the parts

per million range. However, the soil was sampled

immediately after the piping broke during the excavation

process, causing liquid to leak out into the soil which was

subsequently sampled. Soil sampling conducted several

months later, at a depth of approximately 3.0 feet below the

piping and the soil that was initially found to

contaminated, revealed no contamination by VOC's.

Additionally, testing of the tank itself has proven it to be

airtight. At the present time, it is believed that the

initial soil contamination found in the excavated trenches

was caused by leakage from lines broken during excavation,

and that this area is not a source of groundwater

contamination. Investigations in the tank area are still

continuing.

- 6 -

SITE CHARACTERISTICS

Plant #2 Is located in a saddle on the crest of a low,

northwest-southeast trending ridge, which is truncated to

the northwest by Black Creek (Figure 2). Surface drainage

on the ridge, upgradient from Plant #2, is radial to the

north, west and south. In the vicinity of Plant #2, surface

drainage is to the northeast and southwest towards Black

Creek and its tributary (Figure 2). The residential

neighborhood in which wells were contaminated with VOC's is

located to the northeast of Plant #2 (Figure 2).

- 7

RESIDENTIAL AREAWITH CONTAMINATED WELLS

FIGURE 2: AREA FEATURES MAP

2,000 FT

REGIONAL GEOLOGY AND HYDROGEOLOGY

Plant #2 and its surrounding area are underlain by the

Pottsville Formation (Figure 3). This formation has been

described by Lohman (1957) , as being made up chiefly of gray

conglomerate, white, gray and brownish sandstone. In some

places there occurs red and green sandstone, with a few thin

seams of coal. The regional strike of the Pottsville

Formation in the area of West Hazleton is roughly east-west,

trending very slightly in a northeast-southwest direction

(Figure 3). The site is located in the glaciated area of

Pennsylvania, but there is no evidence of glacial deposits

in the immediate vicinity.

Groundwater in the Pottsville Formation occurs in the open

fractures and crevices in the hard conglomerate and

sandstone. Lohman (1957), reports that wells in the

Pottville Formation of Luzerne County range in depth from

150 to 800+ feet, with yields ranging from 50 to 150 gpm.

There is a large seasonal variation in water levels in

wells. Many wells flow during the wet season, but during

the dry season water levels drop many feet below the

surface. The flowing conditions are said to be caused by

occasional beds of shale which act as aquitards. As a

comparison to this regional information, it can be noted

that Plant #2 has a 400 foot deep well which yields 34 gpm.

CHROMATEX PLANT

FIGURE 4

REGIONAL GEOLOGY IN THEVICINITY OF CHROMATEX PLANT #2

C o m p i l e d by H. W. SCHASSE, 1 9 7 9 - 1 9 B CCONYNGHAM

10

The water level in this well in March of 1988 (the wet

season) was 35 feet below the ground surface.

1 -

SITE GEOLOGY

The lithologies underlying the Plant #2 site were

investigated during the drilling of the 12 monitoring wells

on the site. In general, the rock types encountered during

drilling are consistent with Lohman's description of the

Pottsville Formation, and consisted mostly of fine, medium

and coarse grained quartz rich and arkosic sandstone. The

sandstones were also found to be rich in dark minerals,

believed to be amphibole. Many of these beds of sandstone

are jointed, as evidenced by the many weathered fracture

faces that were observed in the drill cuttings. Well #10C

penetrated to a depth of 130 feet and is the deepest of the

12 monitoring wells. The rock types encountered in this

well are representative of those encountered in other wells.

Its lithologic log is reproduced in Table 1. Lithologic

logs of the other wells can be found in Appendix I.

A thin, coal bearing bed was encountered at three well

sites, #1, #10 and #11. It occurred at roughly the same

depth at all three well sites, between 40.0 and 44.5 feet

below the surface, and was therefore considered to be the

same bed. Using the depth of the coal bed in conjunction

with the elevation of the well casings, a standard

three-point problem was solved to determine the strike and

dip of the bedrock layers in the immediate vicinity of Plant

- 12 -

TABLE 1

LITHOLOGIC LOG OF MONITOR WELL #10C

DEPTH BELOW SURFACE (ft) ROCK TYPE

0-7 Yellow-brown clayey silt, littlecoarse sand.

7-9 Sandy silt with small chunks ofsandstone and arkosic sandstone.

9 - 1 5 Bedrock. Quartz-amphibole sand-stone, wet at 10'. Arlcosic inplaces. Weathered at 14 ft.

15 - 24 Medium to coarse quartz-amphibolesandstone, very weathered, wet at17' .

24 - 35 Black, medium sandstone, hard,fractured, trace of pyrite andfree quartz. Wet.

35 - 42 Gray, medium grained sandstone,trace of pyrite, very weathered,

42-55 Fine to coarse quartz-amphibolesandstone, mostly amphlbole,trace of pyrite, some shale,trace of anthracite coal andmica, dry.

55 - 61 Black, very fine sandstone , somegrains of iron oxide. Wet at 58'

61 - 69 Medium to coarse , quartz-amphi-bole sandstone , trace of pyriteand free quartz. Fractured, wet.

69 - 76 Very fine to fine black sand-stone, little pyrite and quartz,wet .

76 - 87 Medium grained quartz-amphibolesandstone. Hard, unfractured,wet .

87 - 125 Black, medium sandstone, somequartz grains , dry . No evidenceof fractures, trace of mica.Weathered zones at 95'. Wetat 106 ' .

125 - 130 Black, very fine sandstone,soft, fractured, some freequartz, wet.

- 13 -

#2. Strike was calculated to be approximately due north,

with a dip of approximately 2 degrees to the east. These

attitudes should be considered approximate, since the

apparent depth of a rock bed can vary within a foot or two

at a depth of 40 feet, with the drilling method that was

used on this project. Strike and dip measured at nearby

outcrops was approximately N 45 degrees E with a dip of

15-25 degrees to the northwest (EPA/TAT, 10/87).

The bedrock attitudes obtained from the three point problem

are very different from those obtained from the measurement

of outcrops. It is possible that Plant #2 is on the axis of

an anticline or syncline, in which case the underlying rock

beds would appear to be flat-lying, as indicated by the

results of the three point problem.

14 -

(RLO)MONITORING WELL INSTALLATION

Twelve monitoring wells were drilled for this investigation;

one more than was originally proposed in the work plan.

Seven of these wells were drilled to depths ranging from 45

to 55 feet and were intended to monitor the upper 20 to 30

feet of the phreatic zone. The locations of these wells are

shown on Exhibit I, followed by the letter "A", or not

followed by any letter at all. These wells were given the

designation of "shallow" in the work plan.

Two wells were drilled to depths ranging from 80.5 to 82

feet and were cased through the units monitored by the

previously described shallower wells. They were intended to

monitor what was apparently the deeper portion of the

unconfined phreatic zone. Their locations are shown on

Exhibit I, as well #1B and well #10B. These wells were

given the designation of "mid-range" or "intermediate", in

the work plan.

Two wells were drilled to depths of 110 feet and 130 feet.

They were cased through the units monitored by all the other

shallower wells. They were intended to monitor the first

water bearing zone encountered beneath an apparently

unfractured and Impermeable layer occurring at a depth of

approximately 85 to 95 feet. The locations of these wells,

designated #1C and #10C, are shown on Exhibit I. These

- 15 -

TABLE 2MONITORING WELL CONSTRUCTION DETAILS

WELL #

1A

IB

1C

2

3

4

5

10A

10B

10C

10D

11

TOTALDEPTH(ft)

50.

80.

110.

55.

47.

55.

45.

50.

82.

130.

15.

55.

0

5

0

5

0

0

0

0

0

0

0

0

SMALLESTDIAMETER

(in)

6

6

4

6

6

6

6

6

6

6

4

6

DEPTHOP INNERCASING(ft)

22

55

86.5

15

18

15.5

15

17

57

87

15

20

DEPTHOF OUTERCASING

(ft)

NONE

NONE

NONE

NONE

NONE

NONE

NONE

NONE

20

27.5

NONE

NONE

DEPTH OFINTERVALMONITORED

(ft)

22-50

55-80.5

86.5-110

15-55.5

18-47

15.5-55

15-45

17-50

57-82

87-130

13-15

20-55

APPROX .YIELD OFMONITOREDINTERVAL

(gpm)

3.8

< 1.0

1.3

2.33

1.00

3.75

1 . 1

2.5

< 1.0

1.5

< 1.0

2 .0

Additional construction information can be found inAppendix I.

16 -

wells were given the designation of "deep", in the work

plan.

A twelfth monitoring well was added to provide information

on an apparent perched water table that was encountered

during the drilling of wells #10A, #10B and #10C. This

well, designated as #10D, is 15 feet deep. Its location is

shown on Exhibit I.

Construction details for all monitoring wells are presented

in Table 2.

All the wells were drilled using the air rotary method. An

in-line filter was used to prevent oil from the air

compressor from entering the drilling string and

contaminating the borehole. However, a non-petroleum based

vegetable oil was used to lubricate the drill bit.

Injection of water through the drill string was not used on

any well. The inner casings in wells #10B and #10C were

grouted by drilling an 8 inch diameter borehole to the depth

of the casing and pouring grout into the uncased borehole.

A 6 inch diameter steel casing, with its lower end sealed

with a teflon plug, was forced to the bottom of the

borehole. This method proved to be unsatisfactory, as the

pressure at the bottom of the hole forced the teflon plug

several feet up into the casing. Subsequently, the deeper

casings in wells #1B and #1C were grouted in place using a

- 17 -

standard tremie pipe method. The shallower casings in wells

#1A, #2, #3, #4, #5, #10A and #11 were grouted by inserting

the casing into an oversize borehole and pouring grout in

from the surface. The outer casings in wells #10B and #10C,

and well #10D were grouted in the same way. Grout was

allowed to harden for at least 24 hours before a well was

completed to its total depth. Grouting details for

individual wells can be found in Appendix I.

The monitored intervals in all wells, except #10D, were

completed as open, unscreened boreholes, owing to the

competency of the bedrock. The monitored interval in well

#10D was completed using a torch-slotted 4 inch diameter

steel casing, with its outer annulus packed with pea-size

quartz gravel.

The drilling rig, and all associated equipment, was

decontaminated before it was used at a new well site. All

decontamination took place at the designated decontamination

area {Exhibit I). Decontamination was accomplished using a

high pressure water rinse, followed by steam, followed by

another water rinse, in accordance with the work plan.

The ground around each well site was protected using a

doubled thickness of plastic tarp. All rock cuttings and

other material ejected from the wells was collected in a

large tub and transferred directly into plastic lined,

- 18 -

55-gallon steel drums. The drums were sealed and moved to

the designated storage area at the end of each work day, in

accordance with the work plan (Exhibit I).

GROUNDWATER QUALITY ANALYSIS

Groundwater samples were collected from each monitoring

well. Samples were collected from the 7 shallow wells over

a 3 day period in order to obtain a relatively instantaneous

picture of the state of contamination in the shallow

phreatic zone. Sampling of all 12 wells took place between

April 19 and April 26 of 1988.

All the wells, except for #1B, #10B and #10D were purged of

a minimum of 3 times the volume of water in the well, to

ensure that the sample collected was withdrawn from the

formation and was not stagnating in the well. Wells #1B,

#10B and #10D had such extremely low yields that they did

not recover quickly enough to allow the removal of 3 well

volumes. Actual volumes purged from each well are shown in

Table 3.

Well #1B was actually sampled twice to determine if any

cross-contamination had occurred between the shallow and

deeper unconfined zones at the well #1 cluster, where an

uncased, ungrouted borehole was left open to a depth of 85

feet for a period of several hours during the drilling of

well #1C.

All purging was accomplished using either a 1/2 hp

20 -

TABLE 3

CHROMATEX MONITORINGPURGING DATA

WELL#

1A

*1B

*1B

1C

2

3

4

5

10A

10B

10C

10D

11

VOLUMEOF WATER

IN WELL (gal)

37.21

(4/15) 76.43

(4/19) 75 .43

53.94

71 .08

42.34

61 . 14

51 .65

45.02

84 .7

145.53

11 .85

65 .0

WELL

NO. OF TOTALVOLUMES VOLUMEPURGED PURGED (gal)

3

1

1

3

3

3

3

3

4.89

1. 13

3

<1

3

111 .64

76.43

75 .43

161 . 82

213.24

126.9

183.43

154.96

220.0

96.03

438.0

4. 5

198.0

METHODOF

PURGING

Balling

Balling

Bailing

Bailing

Bailing

Bailing

Bailing

Bailing

Pumping

Pumping

Pumping

Bailing

Pumping

* NOTE: Well #1B was purged andsampled on two separatedates.

— 21 —

submersible pump or 3 inch diameter teflon bailer (Table 3).

Purging was completed in such a way that several feet of

water remained at the bottom of the wells to minimize loss

of volatile organic chemicals. When possible, the water

level in the wells, during purging, was not allowed to drop

below the water bearing zones. All purged water was either

placed in drums and moved to the drum staging area, or

returned to the well from which it was removed, as part of

the hydraulic conductivity tests.

When purging was completed, groundwater samples were

immediately collected from each well using a 2 inch diameter

teflon bailer equipped with a titration valve. Samples were

collected in standard 40 ml, untreated volatile organic

chemical vials. Two samples vials were collected by INTEX

personnel, from each well and 2 samples were collected by

Versar Corp. personnel, the U.S. EPA on-site observer, from

several selected wells. INTEX samples were immediately

stored on ice. All samples were sealed in insulated

containers and shipped by overnight carrier to Quality

Control Laboratory, Inc. in Southampton, Pennsylvania.

All purging and sampling equipment was cleaned, after use in

each well, at the designated decontamination area.

Decontamination consisted of rinsing and scrubbing equipment

with potable water, rinsing with isopropyl alcohol, with

distilled water used as a final rinse.

- 22 -

Field blanks were collected of the final rinse water, after

several decontamination procedures, to determine if adequate

decontamination was taking place.

All samples were analyzed for the following compounds:

Chloromethane

Bromomethane

Vinyl Chloride

Chloroethane

Methylene Chloride

1,1-Dichloroethylene

1.1-Dichloroethane

1.2-Dichloroethylene {total)

Chloroform

1,2-Dichloroethane

1,1,1-Trichloroethane

Carbon Tetrachloride

Bromodichloromethane

1,2-Dichloropropane

cis-1,3-Dichloropropene

Trichloroethylene

Dibromochloromethane

1,1,2-Trichloroethane

Benzene

trans-1,3-Dichloropropene

Bromoform

- 23

Tetrachloroethylene

1,1,2,2-Tetrachloroethane

Toluene

Chlorobenzene

Ethylbenzene

The method of analysis used was EPA method 624 (Gas

Chromatagraph/Mass Spectrometer).

Volatile organic chemicals were detected in wells #2, #10A,

#10D and #11. Individual chemicals detected in each well

are presented in Table 4.

There were no volatile chemicals detected in any other well.

Low levels of contamination were found in two field blanks,

Well #2 and Well #10A. However, no contamination was found

in groundwater samples collected from wells after collection

of the contaminated field blanks. Apparently, the air

drying phase of the decontamination procedure caused

volatilization of the remaining residual VOC's.

Additionally, the Well #10A blank was contaminated with

compounds not found in the well water, suggesting the

possibility of a contaminated container, or contamination in

the laboratory. Chemical analysis data sheets may be found

in Appendix II.

- 24 -

TABLE 4

VOLATILE ORGANIC CHEMICALS DETECTEDIN CHROMATEX MONITORING WELLS

WELL # VOLATILE ORGANIC CHEMICAL IN ug/1 (ppb)

1,1,1-Trichloroethane 630Trichloroethylene 600

10A 1,1-Dichloroethylene 361.1-Dichloroethane 211.2-Dichloroethylene 1801,1,1-Trichloroethane 2,300Carbon tetrachloride 5.8Trichloroethylene 9,900

10D 1,1-Dichloroethane 9.81,2-Dichloroethylene 841,1,1-Trichloroethane 20Trichloroethylene 570

11 1,1-Dichloroethylene 2801.1-Dichloroethane 3701.2-Dichloroethylene 1,0301,1,1-Trichloroethane 13,000Trichloroethylene 17,000Tetrachloroethylene 35Toluene 140Ethylbenzene 29

- 25 -

WELL TESTING

PIEZOMETER TESTS

The hydraulic conductivity of the water bearing zones'in

each well was calculated using data gathered during

piezometer tests. These tests consisted of the rapid

injection or withdrawal of a volume of water into a well,

followed by the measurement of water level with time as it

recovers to static. The hydraulic conductivity of the water

bearing zone is a function of the duration of the recovery

period, the radius of the well, and the thickness of the

water bearing zone exposed in the well.

The piezometer test method chosen for this investigation was

that developed by Hvorslev in 1951 . This method is one of

the simplest of the piezometer test methods and was

developed for use with point piezometers, rather than for a

well open over a large thickness of an aquifer. It is

believed to be the most appropriate method for use with the

wells at the Chromatex site, since the water bearing zones

in these wells consist of isolated layers of fractured

bedrock which comprise a relatively small portion of the

entire open length of each well.

The Hvorslev equation is as follows:

r2 In (L/R)2L (To)

- 26 -

Where: k = hydraulic conductivity in ft/hr.

L = length of well screen (ft)

r = radius of well above screen (ft)

R = radius of well screen (ft)

To = time lag (hrs) (see Appendix III)

Since the wells at the Chromatex site are unscreened, (L)

would equal the saturated thickness of the water bearing

zones in the well, which is obtained from the drilling logs

Additionally, the wells are of the same diameter for their

entire length. For use with the Chromatex wells, the

Hvorslev equation can be simplified to the following:

k = r2 In (Le/r)2 (Le) To

Where: k = hydraulic conductivity in ft/hr.

r - well radius (ft)

Le = effective thickness of water bearing

zones in well (ft)

To = time lag (hrs)

All monitoring wells were tested using the above described

method (including well #10A, which was also subjected to a

pumping test). Repeat tests were conducted on wells #1A,

#10, #2, #4, #10B, #10C and #11 in order to determine the

reliability of the field procedure. As an additional check,

a piezometer test was conducted on well #10A, which was also

- 27

r 7̂,"'.!(RED)

test pumped, to observe the compatibility of the pumping

test and piezometer test results. The results of the

piezometer tests are presented in Table 5.

Worksheets and calculations for the results presented in

Table 5 can be found In Appendix III.

All injection tests were conducted after the wells had been

purged for sample collection purposes, and had recovered to

original static levels. All injected water was that which

had been previously removed from the same well, to ensure

that the existing water quality in the formation would not

be changed.

Attempts were made to test well #10D, which monitors a

perched water zone. However, the well did not recover when

water was removed from It, and too little water was removed

to make for an effective injection test. This well would

have to be tested using the injection of a relatively large

volume of fresh water to build up enough head to induce flow

into the formation. This was not done since the U.S. EPA

had requested that fresh water not be used for injection

tests.

The test results for the shallow wells indicate that

permeability in the shallow phreatic zone is relatively

uniform across the site, considering that the medium is a

- 28 -

TABLE 5A

PIEZOMETER TEST RESULTS: SHALLOW WELLS

INJECTION WITHDRAWAL HYDRAULICWELL # TEST # TEST TEST CONDUCTIVITY (ft/s)

1A 1 X 4 . 7 2 x 10~-51A 2 X 5 .55 x 1CT-52 1 X 1 . 10 x 10~-52 2 X 3.45 x 10"-53 1 X 1.80 x 10~-54 1 X 7 . 2 7 x 10~-54 2 X 1.01 x 10~-45 1 X 7 .70 X 10~-610A 1 X 1.53 x 10'-511 1 X 3 . 69 x 1CT-51 1 2 X 3 .46 x 10~-5

GEOMETRIC AVERAGE 3.04 x 10"-5

- 29 -

TABLE 5B

PIEZOMETER TEST RESULTS: INTERMEDIATE WELLS

INJECTION WITHDRAWAL HYDRAULICWELL # TEST # TEST TEST CONDUCTIVITY (ft/s)

IB 1 X 2.16 x 10"-610B 1 X 2.95 x 10"-610B 2 X 2.80 x 10~-610B 3 X 2.95 x 10"-6

GEOMETRIC AVERAGE 2.70 x 10"-6

TABLE 5C

PIEZOMETER TEST RESULTS: DEEP WELLS

INJECTION WITHDRAWAL HYDRAULICWELL # TEST # TEST TEST CONDUCTIVITY (ft/s)

1C 1 X 5.9 x 10"-51C 2 X 8.5 x 10"-510C 1 X 5.7 x 10"-610C 2 X 4.4 x 10"-6

GEOMETRIC AVERAGE 1.89 x 10~-5

30 -

heterogenous fractured bedrock, which typically exhibits

wide ranges in hydraulic conductivity over small areas.

The deeper portion of the unconfined zone (monitored by the

intermediate wells) averages one order of magnitude less in

permeability than the overlying zone, and therefore, would

behave as a semi-confining layer, or aquitard. The zone

monitored by the deepest wells appears to be slightly higher

in permeability than the intermediate zone, and slightly

lower than the shallowest zone. Geometric, rather than

arithmetic, means were used to calculate average

permeability, as outlined in Fetter, 1988.

- 31

PUMPING TEST ON WELL #10A

Test Procedure and Results

In accordance with the work plan, a pumping test was

required to be conducted on one well in the #10 cluster.

Well #10A was chosen because it had the highest apparent

yield of any well in the cluster, and because preliminary

sampling indicated that it contained the highest levels of

volatile organic chemicals, namely trichloroethylene and

1,1,1 trichloroethane {Appendix II).

The pumping test had a total duration of 342 minutes (5.7

hours). It was pumped at a rate of 2.0 gpm for 235 minutes,

at which time the pumping rate was increased to 3.0 gpm and

adjusted to 2.5 gpm for the remaining 107 minutes of the

test. When the pump was shut off, recovery of the water

level was measured for 95 minutes.

During the 2.0 gpm portion of the test, a maximum drawdown

of 10.70 feet was observed {Appendix IV). As shown on

Figure 4, drawdown was consistent and continuous until 80

minutes into the test, except for a period at 20 minutes

where discharge slipped to 1.5 gpm. At 80 minutes into the

test, the water level stabilized and remained constant, with

minor fluctuations caused by constant adjustments to

maintain discharge (Figure 4). This leveling off of water

- 32 -

L.I Ml 1 • l .AHI t HMH •'•/ft i" 'I I rt f S'.l I' i '.) 1

drawdown affected bycasing storage

drawdown affected by delayed ]•yield or recharge

drawdown affected bydewatering of aquifer

FIGURE 4

DRAWDOWN IN CHROMATEX WELL'llOADURING 5,7 HOUR PUMPING TEST

pre-pumping water level: 19.40 ft. B.T.C.

30'

10 MINLTE^ 100 1,000

C"

levels may have been caused by delayed yield from aquifer

storage, diminishing casing storage, or the reaching of

equilibrium of the well's cone of depression.

After allowing the well to pump at 2.0 gpm for an additional

155 minutes, the discharge was increased to 3.0 gpm and

adjusted to 2.5 gpm to further stress the aquifer and

provide additional data. After 7 minutes of pumping at 3.0

gpm, the pumping level in the well dropped below 32.75 feet,

at which time cascading was heard in the well, indicating

that the pieziometric surface of the cone of depression had

dropped below a water bearing zone, and that dewatering was

taking place. The rapid drawdown that occurred afterward

suggests that the dewatered zone, at approximately 33 feet

provided a significant percentage of the well's total yield

(Figure 4). Within 95 minutes after the pumping level in

the well passed 32.75 feet, it had dropped to within a few

inches of the pump intake, which was set at 1.0 foot above

the bottom of the well, and the test was concluded.

The recovery of the water level was measured for 95 minutes

after the test ended. During that time, it recovered to

within 2.18 feet of the original pre-pumping water level,

for 90* recovery (Appendix IV).

The data obtained from the pumping test indicates that the

main water bearing zone of the shallow phreatic zone is

- 34 -

feu)

located at a depth of approximately 33 feet. According to

the well log, this is a fractured sandstone approximately

2.5 feet thick. The pumping test data also suggests that

the water bearing zone encountered at 45 feet is not capable

of yielding 3-4 gpm as was estimated during drilling.

Aquifer Characteristics

The drawdown data obtained during the test was used to

calculate the characteristics of the aquifer penetrated by

the well. Two aquifer characteristics were calculated,

transmissivity and storativity.

Transmissivity was calculated using the Jacob straight line

method. Due to the low discharge at which the test was

conducted, the relatively large well diameter, and the

relatively small specific capacity compared to well

diameter, it is believed that drawdown during the early part

of the test was influenced by casing storage.

Therefore, an approximation of the time after which casing

storage effects were insignificant was calculated using the

following equation (Schafer, 1978):

tc = 0-6 (dc2 - dp2)Q/s

Where: tc = time (min) after which casing storage

effect becomes negligable

dc = diameter (in) of well bore

dp - diameter (in) of pump riser pipe

Q/s - specific capacity of well at time tc

36

In this case:

dc = 6 inches

dp = 1.25 inches

Q/s = was estimated by using the average

specific capacity of-the well between

10 and 50 minutes into the test.

The calculation yields a tc of 77 minutes, which is very

close to the 80 minute time duration when water levels began

to stabilize. Therefore, drawdown data from the first 80

minutes of the test probably does not reflect the response

of the aquifer to pumping.

Transmissivity was calculated using the drawdown data for

the first 7 minutes of pumping at 3.0 gpm. This data

yielded a transmissivity value of 226 gpd/ft of aquifer

thickness (Appendix IV). If it is assumed that almost all

of the water supplied to the well is provided by the 2.5

foot thick layer of sandstone at 33 feet of depth, and the

6.5 foot layer at 40 feet, a hydraulic conductivity of 3.8 x

10"-5 ft/s is obtained. This compares to that of 1.53 x

10~-5 ft/s obtained from Well #10A using the Hvorslev

method, and compares very closely with the average of 3.04 x

10~-5 ft/s from all the shallow wells.

No other wells of the same depth were affected during the

test, so there was no observation well data with which to

confirm transmissivity data or calculate the storage

coefficient. The approximate storage coefficient was

calculated using the Jacobs variation of the Theis equation

s = _Q_ in 2'25 + T._, —— j_j.i —

Where : s = drawdown at time t (ft)

Q = discharge (cfs)

T - transmissivity (ft~2/s)

t = time (sec)

r = well bore radius (ft)

S = storage coefficient

In this case:

s = 12 feet (drawdown after 242 minutes}

Q = 0.0055 cfs

T = 0.00035 ft~2/s

t = 14,520 sec.

r = 0.25 feet

This calculation yielded a storage coefficient of 0.07.

This value suggests that the shallow phreatic zone is

unconfined, which was suspected during drilling due to the

lack of any obvious overlying confining layers. According

to Fetter, 1980, the storage coefficient of an unconfined

aquifer ranges from 0.01 to 0.30, while the storage

coefficient of a confined aquifer is usually 0.001 or less.

A storage coefficient , or specific yield, of 0.07 is

slightly low for a sandstone, and typical of a si It stone or

clay (Walton, 1985) .

- 1R -

Effects of Pumping Test on Nearby Wells

During the pumping test, the water levels in the other wells

in the #10C cluster were measured periodically, as were the

water levels in well #11 and the well #1 cluster. These

water levels are presented in Table 6.

Two wells, #10B and #10C display definite signs of being

affected by the pumping of well #10A, in the form of

continuously decreasing water levels during the test and an

increase in water levels when the pump was shut off. Well

#10B exhibits a total drawdown of 0.82 feet and well #10C

exhibits a total drawdown of 0.56 feet.

The drawdown in wells #10B and #10C is small compared to

that which occurred in the pumping well, especially

considering the short distance that separates the wells. It

is possible that upward vertical flow from the zones

monitored by wells #10B and #10C was induced when the head

in the shallow aquifer became less that that existing at

greater depths.

Well #10D displays an apparent drawdown of 0.18 feet during

the test. Observations made during drilling, and water

levels in wells #10A and #10D indicate that the zone

monitored by well #10D is perched above the true water

table. However, the possibility of some connection, even if

indirect, between the two zones at some distance from the

TABLE 6

WATER LEVELS WITH TIMEIN NEARBY MONITORING WELLS

DURING WELL #10A PUMPING TEST (4/25/88)

(All water levels in ft/BTC)

#1A #1B #1C #10C #10D

WATER LEVELTIME MEASURED

WATER LEVELTIME MEASURED

WATER LEVELTIME MEASURED

WATER LEVELTIME MEASURED

WATER LEVELTIME MEASURED

WATER LEVELTIME MEASURED

WATER LEVELTIME MEASURED

WATER LEVELTIME MEASURED

WATER LEVELTIME MEASURED

WATER LEVELTIME MEASURED

21.119:05

20.9810:40

20.8511:26

20.8812:28

20.8213:42

20.8514:47

20.8316:27

309

2910

2910

2911

3012

2913

2914

2916

.06:02

.94:44

.94:44

.94:31

.00:31

.92:44

.94:50

.94:30

308

3010

3011

3012

3013

3014

3016

.35:59

.11:47

.11:34

.18:34

.11:46

.14:53

.14:32

248

249

249

2410

2410

2412

2413

2513

2514

2416

.37:45

.55:35

.63:54

.74:20

.79:55

.96:00-

.95:16

.05:52

.19:36

.95:09

258

2510

2510

2511

2612

2613

2613

2614

2616

.66:52

.87:00

.90:26

.98:02

.00:05

.02:30

.08:58

.22:41

.11: 11

148

149

149

1510

1410

1412

1513

1513

1514

1516

.82:48

.93:38

.90:57

.00:23

.92:59

.98:02

.00:18

.00:54

.00:38

.10:10

10.119:06

10.119:42

10.0510:33

10.0511:05

10.1212:38

10.0513:38

10.1114:57

COMMENTS

Pump startedat 9:22.

Pump shut offat 15:04.

r- ;

wells, cannot be ruled out. Considering the very small

amount of apparent drawdown, the possibility of error in

measurement and influence of barometric pressure must also

be considered.

Solving the Jacobs variation of the Theis equation for the

distance from the well at which drawdown = 0, yields a

radius of 15 feet. Although 15 feet may not be the exact

radius of the cone of depression, it offers one explanation

as to why other shallow wells were not affected by the test.

The closest shallow well, #11, is 150 feet away.

In closing this section, it should be noted that this

pumping test was conducted in a bedrock terrain, in which

apparently all the permeability is secondary. Drilling data

and the general nature of fractured bedrock indicates that

this porous medium is quite heterogeneous. Aquifer analysis

equations were derived for use with ideal, homogeneous

aquifers (such as would occur on the coastal plain, etc.),

and have limitations when used in fractional bedrock

terrain, since bedrock aquifers are not usually homogeneous

over large areas. However, data obtained from this pumping

test agrees with piezometer test data, and quantitative

results using the equations are consistent with the

qualitative analysis. This indicates that the hydraulic

characteristics of the shallow phreatic zone do not vary

significantly over the project area.

- 41 -

GROUNDWATER FLOW AND VELOCITY

GROUNDWATER FLOW DIRECTION

The depth to the water table was determined by taking water

level measurements in each well on April 25, 1988 and May

12, 1988. These measurements are presented in Table 7.

Only the wells which monitor the shallow unconfined zone,

were used to define the actual water table.

Water levels in the wells increased by an average of 4.4

feet between the two periods of measurement, probably in

response to recharge due to rainfall. There is an unusually

large difference in head between wells #2 and #3, which are

only 300 feet apart, at essentially the same elevation, and

differ in depth by 8.5 feet. Well #2 intersects a 2 gpm

water bearing zone at 47 feet, and well #3 intersects two

low yielding zones at 27 and 35.5 feet. It is possible that

the head at depth in well #2 is greater than that in

shallower well #3.

The elevation of the water table across the site was

determined by surveying the elevations of the tops of the

well casings and subtracting the depth to water in shallow

wells from this elevation. An approximation of the

direction of groundwater flow beneath specific portions of

the site was calculated by solving a three point problem,

42

TABLE 7

WATER LEVEL MEASUREMENTS IN CHROMATEX MONITORING WELLS

(DEPTHS IN FEET BELOW TOP OF CASING)

WATER LEVELS

WELL # 4/25/88 5/12/88

1A

2

3

4

5

10A

11

IB

10B

1C

10C

21

9

20

15

12

19

10

30

24

30

25

. 11

.50

.35

.25

.00

.40

. 11

.06

.37

.35

.66

16.

7.

15.

11 .

8.

14.

6.

24.

18.

24.

20.

57

21

66

81

00

53

33

75

96

94

17

10D 14.82 11.54

- 43 -

similar to determing the dip of a bedrock layer, using water

level elevations from three wells as points.

Flow directions are similar for the two dates of

measurement, and indicate the presence of a groundwater

divide trending southeast - northwest beneath the plant #2

building, parallel to the strike of the ridge on which the

property is located. The flow direction of groundwater

appears to be to the north along one side of the divide, and

to the southwest along the other side of the divide. The

calculated flow directions follow the topography and surface

flow fairly closely. The concentration gradients of VOC

contamination in the monitoring wells also agree closely

with the calculated flow directions.

The distribution of contamination in the monitoring wells

indicates that shallow groundwater flow is in two directions

off of the divide, instead of radial, which was our initial

thought. If radial flow was occurring, contamination should

be found in well #1A in addition to wells #2 and #10A.

Water level elevations in wells in the #1 and #10 clusters

show a head gradient in the downward direction. This

indicates that the site is in a recharge area, where

groundwater tends to flow from shallow zones toward

progressively deeper zones. However, the piezometer test

results and water quality testing in the intermediate and

- 44 -

deep wells at the #10 cluster suggest that very little, if

any, vertical groundwater flow occurs in the immediate area.

Since only two intermediate depth wells and two deep wells

were drilled, it is not possible to calculate flow

directions at these depths with the available data.

The gradient of the water table, on either side of the

divide, was calculated using the same 3 point triangulation

technique as was used to calculate direction of flow. This

data is presented in Table 8.

Water table gradients north of the divide are very

consistent over the site and over each period of

measurement. However, due to the difference in head between

wells #2 and #3, gradients south of the divide are not

consistent and it is doubtful that it would vary over an

order of magnitude over the relatively short distance

between wells #2 and #3. It does appear that the gradients

calculated using wells #1A, #2 and #11 are too low.

45 -

TABLE 8

WATER TABLE GRADIENTS AT CHROMATEX PLANT #2

WELLS FROM WHICH

WATER LEVELS WERE

USED TO CALCULATE

HYDRAULIC GRADIENT 4/25/88 5/12/88

North of Divide —•

1A, 10A, 11

4. 10A, 11

5. 10A, 11

1A, 2, 11

3, 4, 11

1A, 2, 4

1A, 2, 4

0.048

0.050

0.043

South of Divide

0.0065

0.054

0.013

0.051

0.042

0.045

0.040

0.009

0.025

0.018

0.046

46 -

VELOCITY OF GROUNDWATER FLOW

By utilizing the previously collected data on permeability,

specific yield and water table gradient, an approximation of

the velocity of shallow groundwater flow at the site can be

calculated. The calculation is as follows {from Walton,

1970) :

v —AhL kSy

Where: v =

k =

Ah_ =LSy =

groundwater velocity in f t/s

hydraulic conductivity in ft/s

hydraulic gradient

specific yield

A number of velocities were calculated to observe

differences in either side of the divide, and to obtain

maximum, minimum and average velocities. Since the velocity

of flow over a relatively long distance (several hundred

feet or more) is of prime interest, the hydraulic

conductivities obtained from several different wells in a

given area were averaged, as were hydraulic gradients. A

specific yield of 0.07 was used in all calculations, which

was calculated from the well #10A pumping test.

Calculated groundwater velocities are presented in Table 9.

- 47 -

TABLE 9

CALCULATED SHALLOW GROUNDWATER FLOW VELOCITIESIN VICINITY OF CHROMATEX PLANT #2

TABLE 9A

GROUNDWATER VELOCITY SOUTH OF DIVIDE

WELLS FROMWHICH K DATA MIN. MAX.

K ft/s WAS AVERAGED GRADIENT * v vAVERAGE

vV

ft/day

3.89 x 10~-51.01 x 10'-41.1 x 10"-5

1A, 2, 3,42

0.03450.0540.013

XX

X

1 .666.730. 18

Gradient calculated using combinationof wells 1A, 2 and 11, was not used inaverage because it was anomalously low.

TABLE 9B

GROUNDWATER VELOCITY NORTH OF DIVIDE

K ft/s

WELLS FROMWHICH K DATAWAS AVERAGED GRADIENT

MINv

MAXv

AVERAGEv

vft/day

2.72 x 10"-55.55 x 10~-57.7 x 10~-6

1A, 5, 10A,1A5

11 0.04460.050.04

XX

X

1 .503.420.38

48 -

An approximation of the velocity of flow across a large

distance of the shallow zone, to the north of the divide was

calculated. This was done using the average hydraulic

conductivities of all the shallow wells on the site. This

is the most logical approach, since it is desirable to use

data acquired over the largest possible area of an aquifer

when calculating flow over a long distance. This average

conductivity is 3.04 x 10~-5 ft/s. The gradient used was

the average calculated for the northern portion of the

divide (0.0446) and a specific yield of 0.07 was used.

These parameters yield a groundwater flow velocity of 1.67

feet/day.

49

HYDROGEOLOGY OF THE PROJECT AREA

GENERAL

The hydrogeologY of the Pottsville Formation underlying

Chromatex Plant #2, to a depth of approximately 100 to 130

feet, is characterized by relatively low permeability and a

fairly rapid groundwater velocity. Based on interpretation

of data from the drilling, testing and sampling of the

on-site monitoring wells, this section of the Pottsville

Formation can be divided up into 5 distinct hydrogeologic

units. They are described below, beginning with the

shallowest unit.

UNIT 1: Perched Zone Water Table

A perched water table has been found to exist In the

vicinity of the well #10 cluster and in the area of well

#11. It occurs at a depth of approximately 11 feet at well

#10, and has been observed to be within 2 feet of the

surface in backhoe pits excavated near well #11. This zone

is monitored by well #10D. Whether or not this perched zone

exists outside of these two areas is not known at this time,

nor is it known if it is seasonal or perennial. This unit

yielded enough water to require that it be cased off during

the drilling of well #10B and #10C. No perched water was

observed during the drilling of well #11, but backhoe pits

- 50

in this area have filled with water fairly quickly, during

previous investigations. This water table is believed to be

perched at the bedrock/soil interface, resting in the soil

on top of the bedrock. Information on the permeability or

hydraulic conductivity of this zone ds not available, since

tests on the one well that monitors this zone were not

successful, as previously discussed. The perched water is

contaminated with VOC's, as shown by the analyses of the

water collected from well #10D and previously collected

water samples from backhoe pits near well #11. The levels

of contamination in well #10D are less than those in deeper

well #10A, so it is possible that the contamination in the

perched zone is due to the collection of volatile gases

diffusing from the top of the true water table approximately

7 to 1O feet below.

UNIT 2: Shallow Unconfined Phreatic Zone

This unit is monitored by wells #1A, #2, #3, #4, #5, #10A

and #11. It is that thickness of the Pottsville Formation

between the top of the water table and a depth of

approximately 45 to 55 feet below ground surface. Since

there are no obvious confining layers overlying this zone,

it can be considered to be unconfined, a belief which is

supported by the specific yield obtained from the pumping

test on well #10A. Monitoring wells penetrating this zone,

in general, had the highest yield of all project wells.

Additionally, piezometer tests show that it has the highest

hydraulic conductivity of any zone investigated. However,

the yields obtained (in addition to the transmissivity

obtained from the well #10 pumping test), could classify

this zone as a semi-confining layer, or aquitard, rather

than an aquifer.

Drill cuttings indicate that unit 2 is rather highly

fractured. However, low well yields and hydraulic

characteristics suggest that the majority of these fractures

are completely filled with the limonitic material that was

observed to coat fracture faces and thus, limit groundwater

movement.

Thin layers of coal were observed in this unit. Coal often

has a high permeability, due to a high concentration of

cleats and other fractures. However, the coal does not

appear to play an important role in hydraulic conductivity

in this case, perhaps because it is too thin.

UNIT 3: Deep Unconfined Phreatic Zone

Unit 3 is monitored by wells #1B and #10B. It occurs at

depths from approximately 55 feet to approximately 85 feet.

Its average hydraulic conductivity is 2.71 x 10"-6 ft/s.

Yields from wells in this zone were extremely low, and it is

essentially dry. To call this unit unconfined is perhaps a

- 52 -

•At

misnomer, since its hydraulic conductivity and yield would

classify it as a confining or semi-confining layer.

However, since there apparently is nothing of lower

permeability directly overlying it, it could still be

considered as part of the unconfined phreatic zone.

Portions of this unit appear to be fractured. However,

these fractures do not appear to interconnect, or are filled

in with limonite.

UNIT 4: Confining Layer

This zone occurs from 87 to 95 feet in well #10C and 82 to

86.5 feet in well #1C. This unit could probably be

considered as a portion of unit 3. However, during the

drilling of well #10C, an 8 foot thick layer of unfractured

rock beneath low permeability unit 3 was encountered,

leading to the belief that any water bearing zones occurring

at greater depths would be confined. There are no project

wells that specifically monitor this zone.

UNIT 5: Confined Zone

This zone occurs immediately beneath the confining layer of

unit 4. Its thickness is at least 35 feet in well #10C and

24 feet in well #1C. Although the average yield of wells in

this zone are less than that of the shallow zone, the

hydraulic conductivities of the two units are similar and of

- 53 -

l

the same order of magnitude. This unit exhibits the same

characteristic fracturing as overlying units, and the same

fracture fillings.

Relative hydraulic characteristics indicate that units 3 and

4 act as at least a semi-confining layer overlying the

confined zone. However, the head in well #10C is lower than

that of wells #10A and #10B, and the head in well #1C is

lower than that of #1A and #1B. This indicates that, even

though unit 5 may be confined or semi-confined, it is not

under an artesian head.

HYDRAULIC RELATIONSHIPS BETWEEN INDIVIDUAL UNITS

Data from the pumping test of well #10A and water quality

data can be combined with vertical head gradients to

interpret the hydraulic inter-relationships between the

units. As stated in the previous section, when describing

the pumping test on well #10A, a small amount of drawdown

was observed in wells #10B and #10C during this pumping

test. This indicates some degree of hydraulic

interconnections with units 2 , 3 , 4 and 5. This is not

unexpected, since completely impermeable, laterally

extensive, confining layers are rare in bedrock terrain.

Under natural, non-pumping conditions, a vertical head

gradient exists across units 2, 3, 4 and 5, with the head in

- 54 -

unit 2 being the highest and the head in unit 5 being the

lowest. This situation indicates the tendency, and

probability, for groundwater flow in the downward direction.

However, the distribution of VOC's in wells #10A, #10B and

#10C suggest that very little, if any, groundwater flows

from the shallow unconfined zone into deeper zones. This is

probably because the hydraulic conductivity of the shallow

unconfined zone is an order of magnitude greater than that

of the deeper unconfined zone. Since groundwater flow

follows the path of least resistance, it would be expected

that the majority of flow would be in the horizontal

direction. It is probable that the vertical conductivity of

the deeper unconfined zone is even less than its horizontal

conductivity, which is what was measured by the piezometer

tests.

APPLICATION OF PROJECT DATA TO CONTAMINATED

RESIDENTIAL WELLS

Available data on residential wells indicates that they

range from 85 feet to 495 feet in depth, with casing lengths

of 20 to 40 feet. The great majority of these wells are

deeper than the deepest wells drilled for this

investigation. This is not surprising in light of the data

obtained from the upper 100 to 130 feet of the Pottsville

Formation, which indicates it to be a rather poor aquifer.

The Chromatex facility well is 400 feet deep, with 20 feet

of casing, and yields 34 gallons per minute. According to

- 55 -

the driller, all but a few gpra of this yield was obtained at

depths greater than 350 feet. This well is contaminated

with TCE in the 1.0 to 3.0 ppm range.

This data raises the following question: If the aquifer

from which most of the residential wells, and the Chromatex

production well withdraw their water are below units 3, 4

and 5, which have been shown to be uncontaminated, then how

did the deeper aquifers become contaminated? The simplest

and most logical explanation to this question concerns the

casing lengths of these wells. These casings, which are

apparently no deeper than 40 feet, would not completely seal

off the highly contaminated shallow unconfined zone.

Therefore, contaminated water flowing through the shallow

zone would be able to leak under the shallow casings into

the wells, thereby contaminating them. Since TCE and

related VOC's are heavier than water, it would be possible

for them to sink to the bottom of the wells, contaminating

the entire water column and probably the deeper aquifers as

well. Since the typical household well pumps for only a

small fraction of each day, it would be possible for VOC

contaminated water entering the wells from the shallow zones

to flow in to deeper zones penetrated by the well, since the

pumping period would probably be too brief to prevent this.

Head gradients in this direction would facilitate this.

- 56 -

SUMMARY AND CONCLUSIONS

1) Volatile organic chemical contamination, including high

concentrations of TCE, has been identified in the

groundwater in monitoring wells #2, #10A, #10D and #11.

The concentration gradients of this contamination, com-

bined with calculated groundwater flow directions,

indicates that a major source of the contamination is

in the vicinity of monitoring well #11.

The distribution of groundwater contamination and calcu

lated flow directions also offer strong evidence that

the VOC contamination that affected the residential

wells did not originate in the vicinity of the under-

ground tank.

2) The vertical distribution of VOC contamination in the

well #10 cluster indicates that it is limited to the

shallow unconfined phreatic zone, and does not extend

in significant concentration below a depth of 55 feet.

The reason for this is believed to be the low perme-

ability of the deeper unconfined zone , which inhibits

vertical groundwater flow and forces most groundwater

flow to occur in the horizontal direction. However,

vertical head gradients in the well #1 cluster and

well #10 cluster indicate the potential for ground-

water flow from shallow zones to deeper zones .

- 57 -

3) Hydraulic conductivity tests conducted on the moni-

toring weils indicate fairly uniform permeability in

the shallow phreatic zone across the site. The aver-

age conductivity of the shallow phreatic zone is

3.04 x 10~-5 ft/s, which is significantly greater

than the average of 2.71 x 10~-6 ft/s of the deeper

unconfined zone, and is similar to the average of

1.89 x 10~-5 ft/s of the confined zone.

4) Calculated groundwater flow directions indicate the

presence of a groundwater divide in the water table

beneath Chromatex Plant #2. The divide trends in a

northwest-southeast direction. Groundwater flows off

the northern side of the divide in a northeast direc-

tion, and off of the southern side of the divide in a

southwest direction. Keeping in mind the large dif-

ference in head between wells #2 and #3, flow direc-

tions calculated using them are probably not as ac-

curate as those ont he northern side of the divide.

5) Velocities of flow have been calculated for ground-

water flow off of each side of the divide. The aver-

age flow velocity off of the southern side of the

divide has been calculated to be 1.66 ft/day. Velo-

cities of flow on the southern side of the divide

must be considered only approximate, since the head

- 58 -

feu)

differences in wells #2 and #3 may have some effect

on the calculated water table gradient. The average

velocity of flow off of the northern side of the

divide was calculated to be 1.50 ft/day. An average

velocity of flow across 'a large area of the shallow

zone, north of the divide, was calculated to be

1.67 ft/day.

To date, the most distant downgradient well in which

VOC contamination has been detected is the Arby's

Restaurant well on Route 93. This well is approxi-

mately 1,560 to 1,660 feet from the most highly con-

taminated well, monitor well #11. The Arby's well is

not in the exact direction of calculated groundwater

flow, but is in the general direction. Assuming a

groundwater flow in a straight line between the two

wells, which is unlikely, at a velocity of 1.67 ft/day,

it would take approximately 2.57 to 2.72 years, for

VOC' s reaching the water table at well #11 to reach

the Arby's well.

The above calculation assumes natural, unimpeded

groundwater flow through the residential neighbor-

hood. It must be kept in mind that, up until Octo-

ber, 1987, at least 22 residential wells, in addi-

tion to the Chromatex Facility well, were in opera-

tion. These wells, which obviously drew in contami-

- 59 -

nated groundwater while pumping, may have impeded

the flow of groundwater through the shallow phreatic

zone. Personnel at Chromatex Plant #2 estimate that

the facility operated at a withdrawal rate of

5,5OO gpd. This well, which evidently drew in con-

taminated groundwater while pumping, may have slowed

down the migration of the contaminant plume toward

the residential wells by pulling it in another di-

rection while it was pumping.

The nature of flow of VOC's in groundwater must be

considered when calculating their travel time

through an aquifer. TCE and related compounds are

denser than water and can display differing flow

characteristics, and it is possible that it could

take longer for TCE to flow through the aquifer

than uncontaminated water.

6) An apparent perched water table is located in the

vicinity of the well #10 cluster and well #11.

This water table has been investigated in a pre-

liminary fashion, and found to be contaminated

with VOC's.

- 60 -

Vil

REFERENCES

Fetter, C. W., 1988, Applied Hydrogeology; MerrillPublishing : Columbus, Ohio.

Hvorslev, 1951, Time Lag and Soil Permeability in Ground-water Observations; U.S. Army Corps of EngineersWaterways Exp. Sto., Bull. 36, Vicksburg, Miss.

INTEX, 1988, Work Plan for Phase 1 of Extent of Contami-nation Study at Chromatex Plant #2, West Hazleton,Pa.

Lohman, 1957, Groundwater in Northeastern Pennsylvania;Pa. Geologic And Topographic Survey Bulletin W4.

Schafer, 1978, Casing Storage Can Affect Pumping TestData; Johnsons Drillers Journal, Jan/Feb., JohnsonSivision, UOP, Inc.

Walton, 1970, Groundwater Resources Evaluation; McGraw-Hill, N.Y., 644 p.

Walton, 1985, Practical Aspects of Groundwater ModellingNWWA.

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