science 

USGS

fora changing world

In cooperation with the Turtle Mountain Band of Chippewa Indians

Occurrence, Distribution, and Concentration of 

Hydrocarbons in and near the Shell Valley 

Aquifer, North Dakota

Open-File Report 99-194

SASKATCHEWAN I MANITOBA

SHELL

VALLEY 

AQUIFER

SOUTH DAKOTA

U.S. Department of the Interior 

U.S. Geological Survey
U.S. Department of the Interior 

U.S. Geological Survey

Occurrence, Distribution, and Concentration of 

Hydrocarbons in and near the Shell Valley 

Aquifer, North Dakota

By Wayne R. Berkas

Open-File Report 99-194

In cooperation with the Turtle Mountain Band of Chippewa Indians

Bismarck, North Dakota 

2000
U.S. DEPARTMENT OF THE INTERIOR 

BRUCE BABBITT, Secretary

U.S. GEOLOGICAL SURVEY 

CHARLES G. GROAT, Director

Any use of trade, product, or firm names is for descriptive purposes only 

and does not imply endorsement by the U.S. Government.

For additional information write to:

District Chief 

U.S. Geological Survey 

Water Resources Division 

821 East Interstate Avenue 

Bismarck, ND 58501

Copies of this report can be purchased from:

U.S. Geological Survey 

Branch of Information Services 

Box 25286 

Denver, CO 80225-0286
CONTENTS

Abstract..................................................................................................................................................................................................... 1

Introduction............................................................................................._^

Purpose and scope.............................................................................................................................................................................. 1

Location-numbering system...............................................................................................................................................................2

Study area...........................................................................................................................................................................................2

Previous studies............................................................................................^

Data collection and analysis......................................................................................................................................................................5

BTEX.................................................................................................................................................................................................5

PAH.................................................................................................................................

PCB............................................................................................................................................^

PCP..................................................»

Additional compounds.................................................................................................................................................................^

Summary.................................................................................................................................................................^

References........................................................................................................._^

FIGURES

1. Map showing location of the Shell Valley aquifer and locations of wells sampled for hydrocarbons, October and

November 1997..................................................................................................................................................................................2

2. Diagram showing township-range location-numbering system used to identify wells sampled for hydrocarbons...........................3

3. Map showing locations of sites sampled for hydrocarbons, 1995 .....................................................................................................4

4. Map showing areal distribution of PAH, detected using the immunoassay method, in the study area, October 1997.................... 10

5. Map showing areal distribution of PCB, detected using the immunoassay method, in the study area, October 1997.................... 13

6. Map showing areal distribution of PCP, detected using the immunoassay method, in the study area, October 1997..................... 15

TABLES

1. Hydrocarbon concentrations, determined using the immunoassay method, in water samples from the study area, 

October 1997.....................................................................................................^

2. Gas chromatography/mass spectrography analyses of selected water samples for BTEX compounds ............................................9

3. Gas chromatography/mass spectrography analyses of selected water samples for PAH compounds............................................. 12

4. Gas chromatography/electron capture detector analyses of selected water samples for PCB compounds ..................................... 14

5. Gas chromatography/mass spectrography analyses of selected water samples for PCP compounds.............................................. 14

6. Gas chromatography/mass spectrography analyses of selected water samples for additional organic compounds........................ 16

7. Estimated concentrations of selected organic compounds that were detected using the gas chromatography/mass 

spectrography method..........................................^

Hi
Occurrence, Distribution, and Concentration of Hydrocarbons 

in and near the Shell Valley Aquifer, North Dakota

EyWayne R. Berkas

Abstract

Water samples from 27 wells completed in and near the Shell Valley aquifer were analyzed for benzene, 

toluene, ethylbenzene, and xylene (BTEX), polynuclear aromatic hydrocarbons (PAH), polychlorinated 

biphenyls (PCB), and pentachlorophenol (PCP) using the enzyme-linked immunoassay method. The analyses 

indicated the presence of PAH, PCB, and PCP in the study area. However, an individual compound at a high 

concentration or many compounds at low concentrations could cause the detections. Therefore, selected samples 

were analyzed using the gas chromatography (GC) method, which can detect individual compounds and 

determine the concentrations of those compounds. Concentrations for all compounds detected using the GC 

method were less than the minimum reporting levels (MRLs) for each constituent, indicating numerous 

compounds at low concentrations probably caused the immunoassay detections. The GC method also can detect 

compounds other than BTEX, PAH, PCB, and PCP. Concentrations for 81 of the additional compounds were 

determined and were less than the MRLs.

Four compounds that could not be quantified accurately using the requested analytical methods also were 

detected. Acetone was detected in 4 of the 27 wells, 2-butanone was detected in 3 of the 27 wells, prometon was 

detected in 1 of the 27 wells, and tetrahydrofuran was detected in 9 of the 27 wells. Acetone, 2-butanone, and 

tetrahydrofuran probably leached from the polyvinyl chloride (PVC) pipe and joint glue and probably are not 

contaminants from the aquifer. Prometon is a herbicide that controls most annual and many perennial broadleaf 

weeds and primarily is used on roads and railroad tracks. The one occurrence of prometon could be caused by 

overspraying for weeds.

INTRODUCTION

The Shell Valley aquifer (fig. 1) is located in north-central North Dakota and is a source of water for the Turtle 

Mountain Indian Reservation and the surrounding area. The aquifer is the sole source of water for the city of Belcourt and 

the primary source of water for most of the rural areas within and adjacent to the Turtle Mountain Indian Reservation. A 

well field located in the northern part of the aquifer and another located in the west-central part are used for municipal, 

domestic, and industrial needs on the Reservation.

A study conducted by the U.S. Geological Survey in cooperation with the Turtle Mountain Band of Chippewa Indians 

during 1995 indicated the presence of hydrocarbons, such as benzene, toluene, ethylbenzene, and xylene (BTEX), 

polynuclear aromatic hydrocarbons (PAH), polychlorinated biphenyls (PCB), and pentachlorophenol (PCP), in shallow 

ground water in the aquifer and in creeks and wetlands in the area of the aquifer. However, because the enzyme-linked 

immunoassay method used in that study detects compounds that are structurally similar, concentrations for the specific 

compounds could not be determined. Therefore, the U.S. Geological Survey conducted a study during 1997 in cooperation 

with the Turtle Mountain Band of Chippewa Indians to determine the occurrence, distribution, and concentration of 

hydrocarbons in and near the Shell Valley aquifer.

Purpose and Scope

The purpose of this study was to determine the occurrence, distribution, and concentration of hydrocarbons in and near 

the Shell Valley aquifer. Samples were collected during October 1997 from 27 wells screened across the water table and 

analyzed for hydrocarbons using the immunoassay method. Where hydrocarbons were detected, the gas chromatography 

(GC) method was used to identify the hydrocarbon compound and concentration. This report presents results of the study.
100° 99°40'

48°50' -

48°40' -

: Q T U R T £,£ M O

 «> T. 162 N.

T. 161 N.

T. 160N.

R.73W. R. 72 W. R. 71 W. 

Base from U.S. Geological Survey

1:100,000 quadrangles 01234 SMILES

I I I I I I

EXPLANATION 

I Shell Valley aquifer

R. 70 W.

UUATOBWAN MAWIOB*

> 26 Well and number IOUTH DAKOTA

Figure 1. Location of the Shell Valley aquifer and locations of wells sampled for hydrocarbons, October and 

November 1997.

Location-Numbering System

The location-numbering system used in this report to identify wells sampled for hydrocarbons is based on the Federal 

system of rectangular surveys of the public lands (fig. 2). The first number denotes the township north of a base line, the 

second number denotes the range west of the fifth principal meridian, and the third number denotes the section in which the 

well is located. The letters A, B, C, and D designate, respectively, the northeast, northwest, southwest, and southeast 

quarter section, quarter-quarter section, and quarter-quarter-quarter section (10-acre tract); thus, well 160-071-28AAA2 

would be located in the NE1/4NE1/4NE1/4 sec. 28, T. 160 N., R. 71 W. Consecutive terminal numbers are added if more 

than one well is located within a 10-acre tract.

Study Area

The Shell Valley aquifer lies south of the Turtle Mountain Indian Reservation in Rolette County (fig. 1). The aquifer is 

in a glacial outwash deposit that consists of some glacial tills and stratified silt, sand, and gravel deposits that were in
160-071-28AAA2

Figure 2. Township-range location-numbering system used to identify wells sampled for hydrocarbons.

contact with melting glacial ice (Randich, 1975). The sediments comprising the outwash deposit generally are less than 

40 feet thick except for a buried valley where sediments exceed 120 feet. Generally, the outwash deposit is at land surface, 

but parts are overlain by clay or till deposits.

Water depth in the aquifer ranges from 6 to 117 feet and has an average of about 35 feet (Randich and Kuzniar, 1984). 

Water-level measurements made in 1995 indicate the water table varied from less than 1 foot below land surface to more 

than 40 feet below land surface (Strobel, 1997). The ground-water flow is predominately from northeast to southwest. 

Recharge to the aquifer is mainly from precipitation. Numerous lakes and wetlands in the southern part of the aquifer may 

act as areas of focused recharge. Recharge to the aquifer also occurs along Wolf and Ox Creeks (fig. 1).

Previous Studies

In 1990, Ecology and Environment, Inc., completed a preliminary assessment report on Turtle Mountain 

Manufacturing for the Turtle Mountain Band of Chippewa Indians and the U.S. Environmental Protection Agency (Pat 

Smith, U.S. Environmental Protection Agency, written commun., 1990). Turtle Mountain Manufacturing, a small factory 

that fabricates single-axle trailers for the Department of Defense, is located about 2.5 miles west of Belcourt on 

Highways 5 and 281. The preliminary assessment identified unlined lagoons on the Turtle Mountain Manufacturing 

property. Tribal and U.S. Environmental Protection Agency samples from wells downgradient from the lagoons indicated 

the presence of 1,1-dichloroethane, trichloroethene, and tetrachloroethene.
In 1995, the U.S. Geological Survey collected water samples from 13 ground-water wells completed hi the Shell 

Valley aquifer and 9 surface-water sites hi the area of the Shell Valley aquifer (Strobel, 1997). The water samples were 

analyzed for the presence of hydrocarbons using the immunoassay method. BTEX was detected hi one ground-water 

sample and three surface-water samples (fig. 3). PAH was detected hi five ground-water samples and nine surface-water 

samples. PCB was not detected hi any ground-water samples but was detected in one surface-water sample. PCP was not 

detected hi any ground-water samples but was detected in five surface-water samples. Generally, hydrocarbons tend to 

float on water and would be detected on the water table of the aquifer. Most of the ground-water samples for the 1995 

study were collected near the bottom of the aquifer and did not contain any hydrocarbons. Also, the immunoassay method 

used in that study detects groups of structurally similar hydrocarbons but does not identify the specific compound or the 

concentration of that compound.

100° 99°40'

48°50' -

48°40' -

T. 162 N.

T. 161 N.

T. 160 N.

R. 73 W. R. 72 W. 

Base from U.S. Geological Survey 

1:100.000 quadrangles 0

I

R. 71 W. R. 70 W.

SMILES 

J

EXPLANATION

Shell Valley aquifer (1) Site at which BTEX was detected

(2) Site at which PAH was detected

(3) Site at which PCB was detected

(4) Site at which PCP was detected

Ground-water sampling 

site (well)

Surface-water sampling 

site

Figure 3. Locations of sites sampled for hydrocarbons, 1995. (Modified from Strobel, 1997.)
DATA COLLECTION AND ANALYSIS

In 1997, the U.S. Geological Survey collected water samples from 27 wells completed in and near the Shell Valley 

aquifer (fig. 1). The wells were screened across the water table, and samples were collected from the top of the aquifer. 

The wells were constructed of polyvinyl chloride (PVC) pipe and screen, and the joints were glued. The wells were 

pumped with a peristaltic pump equipped with teflon tubing. Before the water samples were collected, three volumes of 

well water were removed or the well was completely evacuated and allowed to recharge. Water from the well was placed 

into baked glass bottles and analyzed at the U.S. Geological Survey District laboratory in Bismarck, N. Dak. Duplicate 

samples were collected from 7 of the 27 wells. The pump tubing was washed with methanol and rinsed with organic-free 

water before each sample was collected.

Samples from all of the wells were analyzed for BTEX, PAH, PCB, and PCP using the immunoassay method. All 

samples were analyzed within 3 days of collection. If a value obtained during the analysis exceeded the minimum 

reporting level (MRL), samples were usually sent to the U.S. Geological Survey National Water Quality Laboratory 

(NWQL) in Arvada, Colo., and analyzed using the GC method.

The preparation of the water sample in the laboratory determined the suitability of that sample to be quantified by the 

GC method. A total of three separate water samples were collected to send to the NWQL. The first sample was to be 

analyzed for seven Aroclor PCBs using the GC method and an electron capture detector (ECD). The second sample was to 

be extracted using methylene chloride under basic conditions (base/neutral acid extraction) and analyzed using the GC 

method and a mass spectrometric (MS) detector. The final sample was to be extracted using purge-and-trap techniques and 

analyzed using the GC/MS method, which is capable of determining concentrations of numerous organic compounds that 

may or may not be in the groupings of BTEX, PAH, PCB, and PCP. Combinations of the three samples were sent to the 

NWQL if compounds were detected using the immunoassay method.

Because of the two distinct analytical methods (immunoassay and GC) used in this study, the MRLs are different. In 

some instances, the MRL for the immunoassay method is less than the MRL for a specific compound determined using the 

GC method. For example, the MRL for the immunoassay method for BTEX is 0.02 microgram per liter, which is less than 

the MRL of 3 micrograms per liter for benzene determined using the GC/MS method. The MRL is defined as the smallest 

measured concentration of a constituent that may be reported reliably using a given analytical method. If the extraction 

and preparation phase of the water sample includes something that will alter the method results, the MRL will change. For 

example, if a dilution is used to eliminate interferences, a dilution factor will be reflected in the MRL.

The GC method is different from the immunoassay method in that the immunoassay method detects the sum of 

numerous related compounds. An individual compound at a high concentration or many compounds at low concentrations 

could result in an immunoassay concentration exceeding the MRL. The GC method determines the concentrations of 

individual compounds, and all concentrations could be less than the MRL but, when added together (as in the 

immunoassay method), could exceed the MRL.

BTEX

BTEX is a suite of aromatic hydrocarbons that typically are associated with fuels and additives to boost octane (Fetter, 

1993). Benzene is associated with detergents, solvents, and antiknock gasoline. Toluene is associated with adhesive 

solvents in plastics, solvents, aviation and high-octane fuels, diluents and thinners, explosives, and detergents. 

Ethylbenzene often is an intermediate state for the hydrocarbons and is associated with solvents and gasoline. Xylene is 

associated with aviation fuel, protective coatings, solvents, synthesis of organic chemicals, and gasoline. Samples to be 

analyzed for BTEX using the immunoassay method were placed in 40-milliliter septum bottles with teflon caps and no 

head space. After arrival at the U.S. Geological Survey District laboratory in Bismarck, N. Dak., the samples were 

prepared and analyzed using procedures outlined by the immunoassay manufacturer. The immunoassay method detects the 

sum of numerous BTEX-related hydrocarbons. The hydrocarbon compounds and products that the immunoassay method 

is sensitive to are as follow:
Compound Product

Acenapthene Creosote

Anthracene Diesel fuel

Benzene Jet-A-Fuel

Cyclohexane Kerosene

n-Decane Mineral spirits

Ethylbenzene 

n-Heptane 

Hexachlorobenzene 

n-Hexane 

Methylene chloride

Naphthalene

n-Nonane

n-Octane

Phenanthrene

n-Propylbenzene

Styrene

Toluene

Trichloroethylene

m-Xylene

o-Xylene

p-Xylene

1,2,4-Trimethylbenzene

1,35 5-Trimethylbenzene

BTEX concentrations in all samples (table 1) were less than 0.02 microgram per liter, which is the MRL for the 

immunoassay method.

Although the immunoassay method indicated no presence of BTEX compounds, the compounds were detected in 

water samples analyzed for other types of compounds at the NWQL using the GC/MS method. The BTEX compounds 

were detected in the analyses for PAH compounds. Concentrations for all BTEX compounds detected using the GC/MS 

method (table 2) were less than the MRLs, which range from 3 to 6 micrograms per liter.

PAH

PAH is associated with the combustion of fossil fuels, asphalt, bituminous coal, and naturally occurring petroleum and 

may be associated with forest fires, burning grasses, or, possibly, industrial chemicals. Samples to be analyzed for PAH 

using the immunoassay method were diluted 3:1 with methanol (30 milliliters sample and 10 milliliters methanol) and 

placed in 40-milliliter septum bottles with teflon caps and no head space. After arrival at the U.S. Geological Survey 

District laboratory in Bismarck, N. Dak., the samples were prepared and analyzed using procedures outlined by the 

manufacturer. The immunoassay method detects the sum of numerous PAH-related hydrocarbons. The hydrocarbon 

compounds and products that the immunoassay method is sensitive to are as follow:
Compound Product

Acenaphthalene Creosote

Acenaphthylene Diesel fuel

Anthracene Fuel oil #1

Benzo[a]anthracene Fuel oil #2

Benzo[a]pyrene Fuel oil #4

Benzo[b]fluoranthene Fuel oil #5

Benzo[g,h,i]perylene Fuel oil #6

Benzo[k]fluoranthene Gasoline

Chrysene Heating fuel

Dibenzo[a,h]anthracene JP-4

Fluoranthene JP-5

Fluorene Jet-A-Fuel

Indeno( 1,2,3 -c,d)pyrene Kerosene

Naphthalene Turbine fuel 

Phenanthrene 

Pyrene

PAH concentrations in wells 1,3,4,11,12,15,16,17,18,20, and 23 (table 1) were greater than 1.24 micrograms per liter, 

which is the MRL for the immunoassay method. The areal distribution of PAH in the study area is shown in figure 4. A 

pattern to the distribution of PAH in the study area is not apparent.

Water samples from most wells in which PAH was detected using the immunoassay method were sent to the NWQL 

along with samples from site 26 to determine the concentrations of selected PAH compounds using the GC/MS method. 

Concentrations for all compounds detected using the GC/MS method (table 3) were less than the MRLs, which range from 

3 to 10 micrograms per liter.

PCB

PCB is associated with industrial chemicals that do not break down easily, such as those in electrical transformers, 

heat-exchange and insulating fluids, lubrications and cutting oils, and some pesticides, paints, and inks. Samples to be 

analyzed for PCB using the immunoassay method were diluted 1:1 with methanol (20 milliliters sample and 20 milliliters 

methanol) and placed in 40-milliliter septum bottles with teflon caps and no head space. After arrival at the U.S. 

Geological Survey District laboratory in Bismarck, N. Dak., the samples were prepared and analyzed using procedures 

outlined by the manufacturer. The immunoassay method detects the sum of numerous PCB-related hydrocarbons. The 

hydrocarbon compounds that the immunoassay method is sensitive to are as follow:

Compound

Aroclor 1016 

Aroclor 1221 

Aroclor 1232 

Aroclor 1242 

Aroclor 1248

Aroclor 1254 

Aroclor 1260 

Aroclor 1262 

Aroclor 1268
Table 1. Hydrocarbon concentrations, determined using the immunoassay method, in water samples from the study area, October 1997

[BTEX, benzene, toluene, ethylbenzene, and xylene; PAH, polynuclear aromatic hydrocarbons; PCB, polychlorinated biphenyls; PCP, pentachlorophenol; ug/L, 

micrograms per liter; <, less than minimum reporting level; , not determined]

Well 

number

1

1

2

2

3

4

5

6

7

8

9

10

11

12

13

13

14

15

16

17

17

18

18

19

20

21

22

23

23

24

25

25

26

27

Station number

484728099535301

484728099535301

484712099534702

484712099534702

484542099523401

484452099511301

484359099511301

484217100021101

484231099553702

484216099593601

484216099581701

484125099581801

484124099554001

484124099542201

484215099541901

484215099541901

484034099541902

484124099565701

483847099530301

484217099502901

484217099502901

484307099514801

484307099514801

484123099490801

484119099502402

484032099512901

483914099475001

483935099491602

483935099491602

483939099502901

483939099530101

483939099530101

483755099514801

483846099514701

Township-range 

identification 

number

161-071-07AAA

161 -071-07 AA A

161-071-08BCB2

161-071-08BCB2

161 -071-20 AAA

161-071-22CCC2

161-071-27CCC

1 60-073-0 1CCC

160-072-02CBC2

160-072-07AAA

160-072-08AAA

160-072-08DDD

1 60-072- 10DDD

160-072- 11 ODD

1 60-072- 12BBB

1 60-072- 12BBB

1 60-072-1 3CCC2

1 60-072- 15BBB

160-072-36AAA

1 60-07 1-05DDD

1 60-07 1-05DDD

1 60-07 1-06AAA

1 60-07 1-06AAA

1 60-071-1 5BBB

160-071-16BBB2

160-071-1 7CCD

1 60-07 1-26CBB

1 60-07 1-28AAA2

160-071 -28 AAA2

160-071-29AAA

1 60-07 1-30BBB

1 60-07 1-30BBB

160-071 -3 1DDD

1 60-07 1-32BBB

Date

10-21-97

10-21-97

10-22-97

10-22-97

10-21-97

10-21-97

10-21-97

10-21-97

10-21-97

10-20-97

10-21-97

10-21-97

10-21-97

10-21-97

10-21-97

10-21-97

10-21-97

10-21-97

10-20-97

10-20-97

10-20-97

10-21-97

10-21-97

10-20-97

10-20-97

10-20-97

10-20-97

10-20-97

10-20-97

10-20-97

10-20-97

10-20-97

10-21-97

10-20-97

BTEX, 

total 

(ng/L)

<0.02

<0.02

<0.02

<0.02

<0.02

<0.02

<0.02

<0.02

<0.02

<0.02

<0.02

<0.02

<0.02

<0.02

<0.02

<0.02

<0.02

<0.02

<0.02

-

<0.02

<0.02

<0.02

<0.02

<0.02

<0.02

<0.02

<0.02

<0.02

<0.02

<0.02

<0.02

<0.02

<0.02

PAH, 

total 

(ng/L)

11.9

10.4

<1.24

<1.24

2.69

14.9

<1.24

<1.24

<1.24 '

<1.24

<1.24

<1.24

4.22

1.36

<1.24

<1.24

<1.24

2.01

6.92

2.91

1.63

3.26

<1.24

<1.24

4.77

<1.24

<1.24

<1.24

12.1

<1.24

<1.24

<1.24

<1.24

<1.24

PCB, 

total 

(ng/U

<0.2

0.3

<0.2

<0.2

0.3

0.5

0.4

<0.2

<0.2

<0.2

<0.2

1.5

3.8

<0.2

<0.2

<0.2

<0.2

<0.2

1.4

1.2

<0.2

<0.2

<0.2

<0.2

<0.2

<0.2

<0.2

<0.2

<0.2

<0.2

<0.2

<0.2

5.3

<0.2

PCP, 

total 

(ng/U

<0.06

<0.06

<0.06

<0.06

<0.06

<0.06

<0.06

<0.06

<0.06

<0.06

<0.06

<0.06

<0.06

<0.06

<0.06

<0.06

<0.06

<0.06

<0.06

<0.06

<0.06

<0.06

1.34

<0.06

<0.06

<0.06

<0.06

<0.06

<0.06

<0.06

<0.06

<0.06

<0.06

PCB concentrations in wells 1, 3, 4, 5,10, 11, 16, 17, and 26 (table 1) were greater than 0.2 microgram per liter, which is 

the MRL for the immunoassay method. The areal distribution of PCB in the study area is shown in figure 5. A pattern to 

the distribution of PCB in the study area is not apparent.

Water samples from wells in which PCB was detected using the immunoassay method were sent to the NWQL along 

with samples from sites 15,18,20, and 23 to determine the concentrations of selected PCB compounds using the GC/ECD 

method. Sample bottles from sites 5 and 10 were broken in transit to the laboratory. Concentrations for all compounds 

detected using the GC/ECD method (table 4) were less than the MRLs, which were 0.1 microgram per liter.
Table 2. Gas chromatography/mass spectrography analyses of selected water samples for BTEX compounds

[Water samples were analyzed at the U.S. Geological Survey National Water Quality Laboratory in Arvada, Colo.; all compounds are in micrograms per liter; , no data; <, less than minimum reporting level]

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99°40'

48°50' -

48°40' -

T.162 N.

T. 161 N.

T. 160N.

R. 73 W. R. 72 W. 

Base from U.S. Geological Survey 

1:100,000 quadrangles °

R. 71 W. R.70W.

1234 SMILES 

I I I I I I

EXPLANATION 

Shell Valley aquifer 

 26 \veii an(j number-PAH was detected 

O 27 Well and number~PAH was not detected

Figure 4. Areal distribution of PAH, detected using the immunoassay method, in the study area, October 1997.

PCP

PCP is associated with agricultural uses, such as insecticides, fungicides, bactericides, algicides, herbicides, and wood 

preservatives. Samples to be analyzed using the immunoassay method were placed in 40-milliliter septum bottles with 

teflon caps and no head space. After arrival at the U.S. Geological Survey District laboratory in Bismarck, N. Dak., the 

samples were prepared and analyzed using procedures outlined by the manufacturer. The immunoassay method detects the 

sum of numerous PCP-related hydrocarbons. The hydrocarbon compounds that the immunoassay method is sensitive to 

are as follow:

10
Compound

2.3-Dichlorophenol

2.4-Dichlorophenol

2.5-Dichlorophenol

2.6-Dichlorophenol 

3,5-Dichlorophenol

Hexachlorobenzene

Hexachlorocyclohexane

Pentachlorophenol

Tetrachlorohydroquinone

2,3,4,6-Tetrachlorophenol

2,3,5,6-Tetrachlorophenol

2.3.4-Trichlorophenol

2.3.5-Trichlorophenol

2.3.6-Trichlorophenol

2.4.5-Trichlorophenol

2.4.6-Trichlorophenol

PCP was detected only in well 19, which is located in the southeast part of the study area (fig. 6). The PCP concentration 

in well 19 (table 1) was greater than 0.06 microgram per liter, which is the detection limit for the immunoassay method.

Although the water sample from well 19 was not sent to the NWQL, PCP compounds at some sites were detected in 

the analyses for PAH compounds. Concentrations for all compounds detected using the GC/MS method (table 5) were less 

than the minimum reporting levels, which range from 5 to 30 micrograms per liter.

Additional Compounds

The GC/MS method can detect numerous compounds in addition to those to which the immunoassay method is 

sensitive and can determine the concentrations of those compounds. Concentrations for 81 of the additional compounds 

that are not considered PAH or PCP compounds were determined using the GC/MS method (table 6). Concentrations for 

all compounds were less than the MRL, which range from 1 to 40 micrograms per liter.

Four compounds that could not be quantified accurately using the requested analytical methods also were detected. 

Estimated concentrations for these compounds acetone, 2-butanone, prometon, and tetrahydrofuran are listed in table 7.

Acetone is used as a solvent for fats, oils, waxes, resins, rubber, plastics, lacquers, varnishes, rubber cements, etc. 

(Budavari, 1989). Inhalation may produce headaches, fatigue, bronchial irritation, and, in large amounts, narcosis. Serious 

poisoning is rare. 2-butanone, also known as methyl ethyl ketone, is used as a solvent in the surface-coating industry, and 

tetrahydrofuran is used as a solvent for high polymers, especially polyvinyl chloride (Budavari, 1989). High 

concentrations of tetrahydrofuran can cause narcosis.

The estimated concentrations of acetone, 2-butanone, and tetrahydrofuran were large enough to cause concern. 

However, the wells used in this study were constructed of PVC pipe and screen, and the joints were glued. Other 

investigations indicate that glued PVC pipe leaches 2-butanone and tetrahydrofuran into the well water (Lapham and 

others, 1997). Acetone could be part of the glue formation used to join the PVC pipe. Thus, the occurrence of acetone, 

2-butanone, and tetrahydrofuran could be caused by the glued PVC pipe used in constructing the well.

Prometon is a herbicide that controls most annual and many perennial broadleaf weeds and primarily is used on roads 

and railroad tracks. Most of the wells used in this study are located in ditches, and the one occurrence of prometon could 

be caused by overspraying for weeds.

11
Table 3. Gas chromatography/mass spectrography analyses of selected water samples for PAH compounds

[Water samples were analyzed at the U.S. Geological Survey National Water Quality Laboratory in Arvada, Colo.; all compounds are in micrograms per liter; , no data; <, less than minimum reporting level]

ro

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484124099565701483847099530301

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s

10-21-9710-21-97

11-06-9710-21-97

10-21-97

10-21-97

10-21-97

11-06-97

10-20-9710-20-9710-21-9710-21-97

10-21-97

11-06-97

10-20-9711-06-97

10-20-97

10-21-97

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100° 99°40'

48°50' -

T. 162N.

T. 161 N.

T. 160N.

48°40' -

R. 73 W. R. 72 W. R. 71 W. R. 70 W.

Base from U.S. Geological Survey

1:100,000 quadrangles 01234 SMILES

I I I I I I

EXPLANATION 

Shell Valley aquifer 

 26 Well and number-PCB was detected 

O 27 Well and number-PCB was not detected

Figure 5. Areal distribution of PCB, detected using the immunoassay method, in the study area, October 1997.

SUMMARY

Water samples from 27 wells completed in and near the Shell Valley aquifer were analyzed for benzene, toluene, 

ethylbenzene, and xylene (BTEX), polynuclear aromatic hydrocarbons (PAH), polychlorinated biphenyls (PCB), and 

pentachlorophenol (PCP) using the enzyme-linked immunoassay method. The analyses indicated the presence of PAH, 

PCB, and PCP in the study area. However, an individual compound at a high concentration or many compounds at low 

concentrations could cause the detections. Therefore, selected samples were analyzed using the gas chromatography (GC) 

method, which can detect individual compounds and determine the concentrations of those compounds. Concentrations 

for all compounds detected using the GC method were less than the minimum reporting levels (MRLs) for each 

constituent, indicating numerous compounds at low concentrations probably caused the immunoassay detections. The GC 

method also can detect compounds other than BTEX, PAH, PCB, and PCP. Concentrations for 81 of the additional 

compounds were determined and were less than the MRLs.

13
Table 4. Gas chromatography/electron capture detector analyses of selected water samples for PCB compounds

[Water samples were analyzed at the U.S. Geological Survey National Water Quality Laboratory in Arvada, Colo.; all compounds are in micrograms per liter; <, less than 

minimum reporting level]

Well 

number

1

3

4

11

15

16

17

18

20

23

26

Station number

484728099535301

484542099523401

484452099511301

484124099554001

484124099565701

483847099530301

484217099502901

484307099514801

484119099502402

483935099491602

483755099514801

_ Aroclor 1016. Aroclor 1221, Aroclor 1232, Aroclor 1242, Aroclor 1248, Aroclor 1254, Aroclor 1260, 

3 total total total total total total total

10-21-97 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 

10-21-97 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 

11-06-97 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

10-21-97 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

11-06-97 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

11-06-97 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

10-21-97 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

11-06-97 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

10-20-97 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 

10-21-97 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

10-21-97 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 

11-06-97 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

11-06-97 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

10-20-97 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 

10-20-97 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

10-21-97 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

Table 5. Gas chromatography/mass spectrography analyses of selected water samples for PCP compounds

[Water samples were analyzed at the U.S. Geological Survey National Water Quality Laboratory in Arvada, Colo.; all compounds are in micrograms per liter; <, less than 

minimum reporting level]

Well number

1

3

4

11

15

16

17

18

20

23

26

Station number

484728099535301

484542099523401

484452099511301

484124099554001

484124099565701

483847099530301

484217099502901

484307099514801

484119099502402

483935099491602

483755099514801

Date

11-06-97

10-21-97

10-21-97

10-21-97

11-06-97

10-20-97

10-20-97 

10-21-97

11-06-97

11-06-97

10-20-97

10-21-97

2,4-Dichlorophenol, 

total

<5

<5

<5

<5

<5

<5

<5 

<5

<5

<5

<5

<5

Hexachlorobenzene, 

total

<20

<20

<20

<20

<20

<20

<20 

<20

<20

<20

<20

<20

Pentachlorophenol, 

total

<5

<5

<5

<5

<5

<5

<5

<5

<5

<5

<5

<5

2,4,6-Trichlorophenol, 

total

<30

<30

<30

<30

<30

<30

<30 

<30

<30

<30

<30

<30

14
99°40'

48°50' -

48°40' -

T. 162N.

T. 161 N.

T. 160N.

R. 73 W. R. 72 W. 

Base from U.S. Geological Survey 

1:100,000 quadrangles

R. 71 W. R. 70 W.

01234 SMILES 

I I I I I I

EXPLANATION 

Shell Valley aquifer 

 19 well and number-PCP was detected 

O 27 Well and number-PCP was not detected

Figure 6. Areal distribution of PCP, detected using the immunoassay method, in the study area, October 1997.

Four compounds that could not be quantified accurately using the requested analytical methods also were detected. 

Acetone was detected in 4 of the 27 wells, 2-butanone was detected in 3 of the 27 wells, prometon was detected in 1 of the 

27 wells, and tetrahydrofuran was detected in 9 of the 27 wells. Acetone, 2-butanone, and tetrahydrofuran probably 

leached from the polyvinyl chloride (PVC) pipe and joint glue and probably are not contaminants from the aquifer. 

Prometon is a herbicide that controls most annual and many perennial broadleaf weeds and primarily is used on roads and 

railroad tracks. The one occurrence of prometon could be caused by overspraying for weeds.

15
Table 6. Gas chromatography/mass spectrography analyses of selected water samples for additional organic compounds

[Water samples were analyzed at the U.S. Geological Survey National Water Quality Laboratory in Arvada, Colo.; all compounds are in micrograms per liter, <, less than minimum reporting level; --, no data]

k.

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Q

10-21-97

10-21-97

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10-21-9710-21-97

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20 48411909950240223 483935099491602

26 483755099514801

10-20-97 <3 <3 <3 <3 <3

11-06-97 -- -- -- -- - <40 <5

10-20-97 <3 <3 <3 <3 <3 <40 <510-21-97 <6 <6 <6 <6 <6 <40 <5

<5

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<5<5 <5 

<5

<3 <3 <3 -- -- <3 <3 <3 <3 <3

<5 -- -- -- <5 <5

<5 <3 <3 <3 <5 <5 <3 <3 <3 <3 <3

<5 <6 <6 <6 <5 <5 <6 <6 <6 <6 <6
Table 6. Gas chromatography/mass spectrography analyses of selected water samples for additional organic compounds-Continued

[Water samples were analyzed at the U.S. Geological Survey National Water Quality Laboratory in Arvada, Colo.; all compounds are in micrograms per liter, <, less than minimum reporting level; , no data]

.S

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483935099491602483755099514801

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Table 6. Gas chromatography/mass spectrography analyses of selected water samples for additional organic compounds-Continued

[Water samples were analyzed at the U.S. Geological Survey National Water Quality Laboratory in Arvada, Colo.; all compounds are in micrograms per liter, <, less than minimum reporting level; --,

Well number

1

3

4

11 

15

09

16

17

18 

20

23

26

Station number

484728099535301484542099523401

484452099511301

484124099554001 484124099565701483847099530301

484217099502901

484307099514801 

484119099502402

483935099491602

483755099514801

a

10-21-97 

10-21-97 11-06-9710-21-9710-21-97

10-21-9710-21-97 

11-06-97

10-20-9710-20-97

10-21-97

10-21-97 10-21-97 

11-06-9710-20-97 

11-06-97

10-20-97

10-21-97

Dimethyl phthalate. total

<5<5<5

<5 <5

<5

<5<5<5

<5<5

<5

2,4-Dimethylphenol, total

<5

<5

<5

<5<5<5<5

<5

<5

<5

<5

<5

Di-N-butylphthalate. total

<5<5

<5<5

<5<5<5

<5<5

<5

<5<5

4,6-Dinitroorthocresol. total

<30

<30

<30<30<30<30<30<30<30

<30<30<30

oB 

0)n.

'£ 

5

4

<20

<20

<20<20<20

<20<20

<20

<20

<20<2()

<20

2,4-Dinitrotoluene, total

<5<5

<5<5

<5<5<5<5

<5

<5<5

<5

2,6-Dinitrotoluene, total

<5

<5<5<5<5

<5<5<5<5

<5

<5

<5

Di-N-octyl phthalate. total 1,2-Diphenylhydrazine, total

<10 <5

<10 <5<10 <5

<10 <5<10 <5<10 <5<10 <5<10 <5<10 <5

<10 <5

<l() <5<10 <5

Freon 113, total

<6<3

<3

<3<3 <6<3<6

<6<3 

<3

<3<3<6

Hexachlorobutadiene, total

<6

<3 <5

<3

<3<3

<6

<5<3<6

<6

<3 <3 <5

<3 <5<3<6

Hexachlorocyclopentadiene, 

total

<20

<20

<20

<20 

<20

<20<20

<20

<20 

<20

<20

<20

Hexachloroethane, total

<5

<5

<5<5

<5

<5<5

<5

<5 

<5<5

<5

n

2

0)1e

o.o

<5

<5<5

<5 

<5

<5<5<5<5 

<5<5<5

0)a

o. SB.

eM

a.

<6<3

<3<3<3 

<6

<3

<6<6

<3 <3

<3

<3

<6

Methyl tert-butyl ether 

(MTBE), total

<6

<3<3<3

<3 

<6

<3<6

<6

<3 <3<3

<3<6

0)

ja 

1

<6 <3

<3

<3<3 

<6<3<6

<6<3 

<3

<3<3<6

Methyl chloride, total

<6

<3

<3

<3<3 

<6<3<6

<6

<3 <3

<3

<3

<6

no data]

n-Nitroso di-n-propylamine, 

total

<5<5

<5<5 <5<5<5

<5

<5 

<5<5<5

n-Nitroso dimethylamine, 

total

<5

<5

<5<5 

<5<5<5

<5<5 

<5

<5<5
Table 6. Gas chromatography/mass spectrography analyses of selected water samples for additional organic compounds-Continued

[Water samples were analyzed at the U.S. Geological Survey National Water Quality Laboratory in Arvada, Colo.; all compounds are in micrograms per liter, <, less than minimum reporting level; --, no data]

Well number

1

3

4

11

1516

1718

20

2326

Station number

484728099535301484542099523401

484452099511301

484124099554001484124099565701483847099530301

484217099502901484307099514801

484119099502402483935099491602

483755099514801

S

10-21-97 

10-21-9711-06-9710-21-9710-21-97

10-21-97

10-21-9711-06-9710-20-9710-20-97

10-21-97

10-21-97

10-21-97

11-06-97

10-20-97

11-06-97

10-20-9710-21-97

n-Nitrosodiphenylamine, 

total -- <5

<5<5

<5__ <5

<5

<5

<5_<5_<5

<5

<5

Nitrobenzene, total -- <5

<5

<5

<5__ <5<5

<5<5

_.

<5

..

<5

<5

<5

2-Nitrophenol. total -- <5

<5<5

<5

._

<5

<5<5<5

_.

«

<5

..

<5

<5<5

4-Nitrophenol, total -- <30

<30<30<30

..

<30

<30<30<30

..

~

<30

..

<30

<30<30

Parachlorometa cresol, tota -<30

<30<30<30

._

<30

<30<30<30

._-<30

._

<30

<30<30

Parachlorotoluene, total

<6

<3

~

<3<3<3<6

~

<3<6<6<3

<3

~

<3

~

<3

<6

Phenol (C6H-50), total -<5

<5<5<5__ <5

<5

<5<5

_.-<5__ <5

<5<5

Propane, 1,3-dichloro-, total

<6<3<3

<3

<3

<6

~

<3

<6<6<3<3-- <3

<3<6

Ol

B 

O>

<6

<3<3<3

<3

<6

~

<3<6<6

<3<3

~

<3<3<6

1,1.1.2-Tetrachloroethane. 

total

<6

<3-<3

<3

<3<6

~

<3<6<6<3

<3-<3

~

<3

<6

1,1Z2-Tetrachloroethane, 

total

<6

<3-<3

<3

<3<6-<3

<6

<6

<3<3

~

<3

- -- <3

<6

Ol

1

o 

u

i

<6<3

~

<3

<3

<3

<6

~

<3

<6

<6

<3<3

~

<3

~

<3

<6

Trans-1,3-dichloropropene, 

total

<6<3-<3

<3

<3<6-<3<6<6

<3<3-- <3-- <3

<6

1,2-Transdichloroethene. 

total

<6<3-<3<3<3<6

~

<3<6<6<3<3

~

<3

~

<3<6

1,2,4-Trichlorobenzene, total

<6

<3

<5<3

<3

<3<6<5<3

<6

<6

<3<3<5

<3

<5<3

<6

0)

ra

i

0

<6

<3-- <3<3

<3

<6-<3<6

<6

<3<3-<3-<3

<6

1,1.2-Trichloroethane, total

<6

<3-<3<3<3

<6-- <3

<6

<6

<3<3-<3-<3

<6

Trichlorofluoromethane, total

<6<3-- <3<3<3<6

~

<3<6<6<3<3-- <3

~

<3<6

o» ra § Q. 

O

<6

<3-<3<3

<3

<6-- <3<6<6

<3

<3-<3-<3

<6

0)us.

1

<2

~

<1<1<1<2-- <1<2<2

<,<1

~

<,-- <1

<2
Table 7. Estimated concentrations of selected organic compounds that were detected using the gas chromatography/mass spectrography method

[Water samples were analyzed at the U.S. Geological Survey National Water Quality Laboratory in Arvada, Colo.; ng/L, micrograms per liter; >, greater than; -, not 

determined]

Well 

number

1

1

3

4

11

15

15

16

17

17

18

18

26

Station number

484728099535301

484728099535301

484542099523401

484452099511301

484124099554001

484124099565701

484124099565701

483847099530301

484217099502901

484217099502901

484307099514801

484307099514801

483755099514801

Date

10-21-1997

10-21-1997

10-21-1997

11-03-1997

10-21-1997

10-21-1997

11-06-1997

11-03-1997

10-20-1997

10-21-1997

10-21-1997

10-21-1997

10-21-1997

Acetone

> 1,200

>600

-

> 7,800

~

> 1,600

>6,900

__

>8,900

2-Butanone Prometon Tetrahydrofuran 

(pg/L) (ug/L) (ug/L)

> 10,000

> 14,000

>600

>800

>600

74.5 - > 20,000

1.0

> 6,300

>20,000

61 - >21,000

>200

>200

110 - >20,000

REFERENCES

Budavari, Susan, ed., 1989, The Merck index an encyclopedia of chemicals, drugs, and biologicals (llth ed.): Merck and Co., Inc., 

Rahway, N.J., USA, 2303 p.

Fetter, C.W., 1993, Contaminant hydrology: New York, Macmillan Publishing Co., 458 p.

Lapham, W.W., Wilde, F.D., and Koterba, M.T., 1997, Guidelines and standard procedures for studies of ground-water quality;

selection and installation of wells and supporting documentation: U.S. Geological Survey Water Resources Investigations Report 

96-4233, 110 p.

Randich, P.G., 1975, Ground-water availability in the Belcourt area, Rolette County, North Dakota: U.S. Geological Survey Open-File 

Report 75-104, 36 p.

Randich, P.G., and Kuzniar, R.L., 1984, Ground-water resources of Bottineau and Rolette Counties, North Dakota: North Dakota State 

Water Commission County Ground-Water Studies 35, pt. Ill, and North Dakota Geological Survey Bulletin 78, pt. El, 41 p.

Strobel, M.L., 1997, Hydrogeology and water quality of the Shell Valley aquifer, Rolette County, North Dakota: U.S. Geological 

Survey Water-Resources Investigations Report 97-4291,25 p.

20