Scientific Investigations Report 2005-5104

U.S. Department of the Interior

U.S. Geological Survey

Fate and Transport of Petroleum Hydrocarbons in Soil 

and Ground Water at Big South Fork National River and 

Recreation Area, Tennessee and Kentucky, 2002-2003
Cover photograph: View of the Big South Fork of the Cumberland River from the Honey Creek Overlook in the Big South Fork National River 

and Recreation Area. 
Fate and Transport of Petroleum 

Hydrocarbons in Soil and Ground Water 

at Big South Fork National River and 

Recreation Area, Tennessee and Kentucky, 

2002-2003

By Shannon D. Williams, David E. Ladd, and James J. Farmer

Scientific Investigations Report 2005-5104

U.S. Department of the Interior

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

Gale A. Norton, Secretary

U.S. Geological Survey

Charles G. Groat, Director

U.S. Geological Survey, Reston, Virginia: 2006

For sale by U.S. Geological Survey, Information Services

Box 25286, Denver Federal Center

Denver, CO 80225

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Although this report is in the public domain, permission must be secured from the individual copyright owners to 

reproduce any copyrighted materials contained within this report.

Suggested citation:

Williams, S.D., Ladd, D.E., and Farmer, J.J., 2006, Fate and transport of petroleum hydrocarbons in soil and ground 

water at Big South Fork National River and Recreation Area, Tennessee and Kentucky, 2002-2003: U.S. Geological 

Survey Scientific Investigations Report 2005-5104, 29 p.
iii

Contents

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

Introduction.....................................................................................................................................................1

Purpose and Scope ..............................................................................................................................2

Study Area..............................................................................................................................................2

Crude Oil Release Site 1 .............................................................................................................2

Crude Oil Release Site 2 .............................................................................................................7

Crude Oil Release Site 3 .............................................................................................................7

Petroleum Hydrocarbons..............................................................................................................................7

Types of Petroleum Hydrocarbons.....................................................................................................7

Transport of Petroleum Hydrocarbons............................................................................................10

Biodegradation of Petroleum Hydrocarbons .................................................................................11

Methods.........................................................................................................................................................12

Sample Collection and Preservation ...............................................................................................12

Physical Properties and Geochemical Analyses ..........................................................................12

Petroleum Hydrocarbon Analyses...................................................................................................13

Microbiological Analyses..................................................................................................................14

Crude Oil Dissolution Study...............................................................................................................14

Ground-Water Quality and Potential Natural Attenuation....................................................................14

Ground-Water-Quality Reconnaissance.........................................................................................15

Background Water-Quality Conditions............................................................................................15

Crude Oil Release Site 1 ....................................................................................................................15

Crude Oil Release Site 2 ....................................................................................................................23

Crude Oil Release Site 3 ....................................................................................................................24

Crude Oil Dissolution Study...............................................................................................................25

Summary........................................................................................................................................................26

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

Figures

1–2. Maps showing:

 1. Location of the study area at Big South Fork National River 

and Recreation Area near Oneida, Tennessee.................................................................3

 2. Locations of sites from which water samples were collected 

and locations of crude oil release study sites..................................................................4

3. Conceptual model of ground-water occurrence and flow in the 

Big South Fork National River and Recreation Area ..............................................................5

4–5. Maps showing:

 4. Sampling locations at crude oil release sites 1 and 2.....................................................6

 5. Sampling locations at crude oil release site 3 .................................................................8
iv

Tables

1. Physical, chemical, regulatory, and human health information for 

selected aromatic hydrocarbons...............................................................................................9

2. Physical properties and volatile organic compound data for 

water samples collected during the ground-water-quality 

reconnaissance, June 2002 ......................................................................................................16

3. Physical properties and volatile organic compound data for water samples 

collected after reconnaissance, July 2002 - February 2003 ................................................17

4. Geochemcial and diesel range organic compound data for water samples 

collected after reconnaissance, July 2002 - February 2003 ................................................18

5. Summary of results from biological activity reaction tests (BARTs), 

July 2002 - December 2002........................................................................................................19

6. Volatile organic compound data for soil gas samples, 

September and December 2002 ...............................................................................................21

7. Volatile and diesel range organic compound data for soil samples, 

September 2002 - February 2003 ..............................................................................................22

8. Results from the crude oil hydrocarbon dissolution study..................................................25

Conversion Factors, Vertical Datum, and Site-Numbering 

System

Multiply By To obtain

nanometer (nm) 3.937 x 10-8 inch (in.)

centimeter (cm) 0.3937 inch (in.)

meter (m) 3.281 feet (ft)

kilometer (km) 0.6214 mile (mi)

square kilometer (km2) 0.3861 square mile (mi2)

milliliter (mL) 0.0338 fluid ounce (fl oz)

liter (L) 0.2642 gallon (gal)

micrograms per kilogram (μg/kg) 1.000 x 10-9 pound per pound (lb/lb)

milligrams per kilogram (mg/kg) 1.000 x 10-6 pound per pound (lb/lb)

micrograms per liter (μg/L) 6.243 x 10-8 pound per cubic foot (lb/ft3)

milligrams per liter (mg/L) 6.243 x 10-5 pound per cubic foot (lb/ft3)

liters per second (L/s) 15.85 gallon per minute (gal/min)

Temperature in degrees Fahrenheit (°F) can be converted to degrees Celsius (°C), and 

temperature in °C to °F, as follows:

°F = 1.8 x °C + 32

°C = 5/9(°F – 32)

Vertical coordinate information is referenced to the National Geodetic Vertical Datum of 1929 

(NGVD 29); horizontal coordinate information is referenced to the North American Datum of 

1927 (NAD 27).
Site-numbering system for wells: In addition to the field site number, the U.S. Geological 

Survey assigns each site listed in this report a station identification number. The station 

identification number is used as an identifier for site data stored in the national computer data 

base of the U.S. Geological Survey.

The station identification number is a unique number for each site based on a latitude and 

longitude grid system. The number consists of 15 digits. The first 6 digits denote the degrees, 

minutes, and seconds of latitude; the next 7 digits denote degrees, minutes, and seconds of 

longitude; and the last 2 digits (assigned sequentially) identify the wells within a 1-second grid.

Site numbering system for surface-water sites: Each surface-water station in this report 

is assigned a unique identification number. The number is assigned when a station is 

first established and is retained for that station indefinitely. The station numbers indicate 

downstream-order position. A station on a tributary that enters between two mainstream 

stations is assigned a number between them. A similar order is followed in listing stations on 

first rank, second rank, and other ranks of tributaries.

Gaps are left in the series of numbers to allow for new stations that may be established; hence, 

the numbers are not consecutive. The complete number for each station such as 03540500, 

includes a 2-digit part number “03” plus the multi-digit downstream order number “540500.” 

This downstream ordering system is used in most cases; however, in some cases latitude and 

longitude numbers are assigned to hydrologic stations as a means of identification.

Acronyms

BART Biological activity reaction test

BISO Big South Fork National River and Recreation Area

BTEX Benzene, toluene, ethylbenzene, and xylene

DO Dissolved oxygen

DRO Diesel range organic

EPH Extractable petroleum hydrocarbon

GC Gas chromatography

GC/MS Gas chromatography/mass spectrometry

GRO Gasoline range organic

MCL Maximum contaminant level

NPS National Park Service

NWQL U.S. Geological Survey National Water Quality Laboratory

PAH Polycyclic aromatic hydrocarbon

PBS Phosphate buffered solution

STL Severn Trent Laboratories

TEAP Terminal electron acceptor processes

TPH Total petroleum hydrocarbon

USEPA U.S. Environmental Protection Agency

USGS U.S. Geological Survey

VBW Volatile grade blank water

VOC Volatile organic compound

VPH Volatile petroleum hydrocarbon

WQRL U.S. Geological Survey Water Quality Research Laboratory
Abstract

In 2002 and 2003, the U.S. Geological Survey (USGS), 

by agreement with the National Park Service (NPS), investigated the effects of oil and gas production operations on 

ground-water quality at Big South Fork National River and 

Recreation Area (BISO) with particular emphasis on the fate 

and transport of petroleum hydrocarbons in soils and ground 

water. During a reconnaissance of ground-water-quality conditions, samples were collected from 24 different locations (17 

springs, 5 water-supply wells, 1 small stream, and 1 spring-fed 

pond) in and near BISO. Benzene, toluene, ethylbenzene, and 

xylene (BTEX) compounds were not detected in any of the 

water samples, indicating that no widespread contamination of 

ground-water resources by dissolved petroleum hydrocarbons 

probably exists at BISO. Additional water-quality samples 

were collected from three springs and two wells for more 

detailed analyses to obtain additional information on ambient 

water-quality conditions at BISO.

Soil gas, soil, water, and crude oil samples were collected at three study sites in or near BISO where crude oil had 

been spilled or released (before 1993). Diesel range organics 

(DRO) were detected in soil samples from all three of the sites 

at concentrations greater than 2,000 milligrams per kilogram. 

Low concentrations (less than 10 micrograms per kilogram) of 

BTEX compounds were detected in lab-analyzed soil samples 

from two of the sites. Hydrocarbon-degrading bacteria counts 

in soil samples from the most contaminated areas of the sites 

were not greater than counts for soil samples from uncontaminated (background) sites. The elevated DRO concentrations, 

the presence of BTEX compounds, and the low number of 

hydrocarbon-degrading bacteria in contaminated soils indicate 

that biodegradation of petroleum hydrocarbons in soils at these 

sites is incomplete.

Water samples collected from the three study sites were 

analyzed for BTEX and DRO. Ground-water samples were 

collected from three small springs at the two sites located on 

ridge tops. BTEX and DRO were not detected in any of the 

water samples, and petroleum hydrocarbons do not appear to 

have leached into ground water at these sites. Ground-water 

samples were collected from a small spring and from three 

auger holes at the third site, which is located in a stream 

valley. BTEX and DRO were not detected in these groundwater samples, and currently, petroleum hydrocarbons do not 

appear to be leaching into ground water at this site. Weathered 

crude oil, however, was detected at the water surface in one 

of the auger holes, indicating that soluble petroleum hydrocarbons may have leached into the ground water and may 

have migrated downgradient from the site in the past. The 

concentration of soluble petroleum hydrocarbons present in 

the ground water would depend on the concentration of the 

hydrocarbons in the crude oil at the site. 

A laboratory study was conducted to examine the dissolution of petroleum hydrocarbons from a fresh crude oil 

sample collected from one of the study sites. The effective 

solubility of benzene, toluene, ethylbenzene, and total xylenes 

for the crude oil sample was determined to be 1,900, 1,800, 

220, and 580 micrograms per liter (μg/L), respectively. These 

results indicate that benzene and toluene could be present 

at concentrations greater than maximum contaminant levels 

(5 μg/L for benzene and 1,000 μg/L for toluene for drinking water) in ground water that comes into contact with fresh 

crude oil from the study area.

Introduction

The Big South Fork National River and Recreation Area 

(BISO) was established in 1974 to con­serve, interpret, and 

protect the unique resources of the Big South Fork of the 

Cumberland River. The National Park Service (NPS) manages BISO and has an ongoing program to protect the water 

resources of the area. Goals of this program include evaluating 

the condition of water resources and prioritizing activities to 

remediate any contamination of these water resources.

Approximately 300 active or abandoned oil and gas wells 

are located in BISO, and more than 3,000 oil and gas wells are 

in the Big South Fork watershed (Otton and Zielinski, 2000). 

Contaminants associated with oil and gas production have 

the potential to affect the water resources of the area. The 

potential contaminants associated with oil and gas production include petroleum hydrocarbons, brines and trace metals, 

Fate and Transport of Petroleum Hydrocarbons in Soil 

and Ground Water at Big South Fork National River and 

Recreation Area, Tennessee and Kentucky, 2002-2003

By Shannon D. Williams, David E. Ladd, and James J. Farmer
and in some cases naturally occurring radioactive material. 

Sources of these contaminants include overflowing, failing, or 

unlined pits; leaking tanks; leaking well heads; and interaction 

between ground water and petroleum or brine zones inside 

well bores. In 2002 and 2003, the USGS, by agreement with 

the NPS, investigated the effects of oil and gas production 

on ground-water quality at BISO with particular emphasis on 

the fate and transport of petroleum hydrocarbons in soils and 

ground water. This report is published by agreement with the 

NPS.

Purpose and Scope

This report presents data and results from an investigation of the effects of oil and gas production operations on 

ground-water quality at BISO. Objectives of this investigation 

included examining the extent of ground-water contamination 

by petroleum hydrocarbons from oil and gas production, documenting general ground-water-quality conditions in BISO, 

and evaluating potential natural attenuation processes such as 

biodegradation. 

Three stages of monitoring and research activities were 

used to meet these objectives. During the first stage (the 

reconnaissance), basic water-quality data and volatile organic 

compound (VOC) data were collected from several locations 

(mostly springs) in or near BISO. During the second stage, 

more detailed water-quality data (including microbiological, 

geochemical, and additional petroleum hydrocarbon data) 

were collected from several of the locations sampled during 

the reconnaissance stage. During the third stage of the investigation, soil gas, soil, water-quality, and microbiological data 

were collected at three crude oil release sites in or near BISO. 

Little construction and lithologic data were available for wells 

sampled during the first two stages of the investigation, and 

not enough water-level data could be collected from these 

wells to report ground-water gradients for BISO. Site-specific 

hydrogeologic data were not collected as part of the investigation, and little published information specific to the geology 

and hydrogeology of BISO exists. Although a general description of the hydrogeology of the Cumberland Plateau section of 

the Appalachian Plateaus Physiographic Province is presented 

in the report, site-specific hydrogeologic information is not 

included.

Study Area

BISO includes about 506 km2 in the rugged Cumberland 

Plateau section of the Appalachian Plateaus Physiographic 

Province in Tennessee and Kentucky (Fenneman, 1938) 

(fig. 1). BISO is located in parts of Fentress, Scott, Morgan, 

and Pickett Counties in Tennessee and McCreary County 

in Kentucky. Average annual precipitation near BISO (in 

Oneida, Tennessee) is about 140 cm (National Oceanic and 

Atmospheric Administration, 2002). Clear Fork and the New 

River meet in Tennessee to form the South Fork Cumberland 

River, also referred to as the Big South Fork River. The Big 

South Fork River flows north across the Cumberland Plateau, 

forming a steep-walled gorge that in places reaches a depth 

of 183 m (Manning, 2000), eventually flowing into the main 

stem of the Cumberland River in Kentucky. 

The Big South Fork River watershed covers about 

3,580 km2 from its headwaters to its confluence with the Cumberland River. Within the watershed, the Big South Fork River 

and its tributaries drain the Cumberland Plateau. Elevations 

in the watershed range from over 1,060 m in the southeastern part of the watershed to around 220 m near the northern 

boundary. The study area for this investigation is located 

in the southern part of the Big South Fork River watershed 

(fig. 1), which contains the highest density of oil and gas production wells in the vicinity of BISO. Although all of BISO 

lies within the Cumberland Plateau, the southeastern part of 

the study area lies within the Cumberland Mountain section of 

the Appalachian Plateaus Physiographic Province (Fenneman, 

1938) (fig. 1). The three crude oil release study sites and most 

of the sampling locations are located in or near the southern 

part of BISO (fig. 2).

The exposed geology of the study area consists predominantly of sandstones, conglomerates, shales, siltstones, and 

coals of Pennsylvanian age that overlie carbonates and shale 

of Mississippian age. The rocks of Pennsylvanian age compose the Cumberland Plateau aquifer system, which underlies 

BISO and the rest of the Cumberland Plateau. The sandstones 

have low intergranular permeability, and ground water in the 

aquifer occurs mostly within the fractures in the sandstones 

and conglomerates. The sandstone and conglomerate units 

are confined and separated by shale and siltstone beds of low 

permeability (Brahana and others, 1986). Seeps and springs, 

occurring where ground water intersects land surface, are 

common in BISO, particularly at the base of ledges and bluff 

shelters (Hamilton and Turrini-Smith, 1997). Commonly, 

springs in the Cumberland Plateau aquifer system are present at sandstone/shale contacts (Brahana and others, 1986). 

The only rocks of Mississippian age exposed within the study 

area are part of the Pennington Formation, a unit consisting 

of approximately 46 to 122 m of shale, siltstone, dolomite, 

limestone, and sandstone (Swingle and others, 1966). The 

Pennington Forma­tion, which crops out in the northern part of 

Tennessee in the bottom of the Big South Fork River gorge, 

separates underlying carbonates of Mississippian age from 

the exposed rocks of Pennsylvanian age. The top of the Pennington Formation is considered the base of the Cumberland 

Plateau aquifer system. A conceptual model of ground-water 

occurrence and flow in BISO is shown in figure 3. 

Crude Oil Release Site 1

Site 1, which is near Bear Branch in BISO (fig. 4), 

includes an active crude oil pumping unit and a tank battery. 

In 1993, a tank in an old battery was struck by lightning. Gas 

in the headspace of the tank exploded and about 31,800 L of 

crude oil were released, some of which flowed into a tributary 

   Fate and Transport of Petroleum Hydrocarbons...Big South Fork National River and Recreation Area
Figure 1. Location of the study area at Big South Fork National River and Recreation Area near Oneida, 

Tennessee.

Introduction   
Figure 2. Locations of sites from which water samples were collected and locations of crude oil release study sites.

 Fate and Transport of Petroleum Hydrocarbons...Big South Fork National River and Recreation Area
ABOUT 8 KILOMETERS

Drawing not to scale

ABOUT 180 METERS

BIG SOUTH FORK RIVER

Stream valley WEST

Springs

Spring

Springs Ground-water flow

FracconcoaPen

Modified from Brahanaand others, 1986

Figure 3. Conceptual model of ground-water occurrence and flow in the Big South Fork National River and Recreation Area.
Figure 4. Sampling locations at crude oil release sites 1 and 2.
to Bear Branch. After the spill, the old tank battery was 

removed. Remedial activity included tilling soil near the old 

tank battery to a depth of 10 to 13 cm, fertilization, and planting winter wheat and winter rye (Otton and Zielinski, 2000). 

This site was examined in 1999, during a study evaluating field-monitoring techniques for assessing impacts of oil 

and gas operations on Federal Lands (Otton and Zielinski, 

2000). During the 1999 study, holes were bored about 0.5 to 

1 m deep using a hand auger at the site (site BSF99-2 in Otton 

and Zielinski, 2000). Volatile organic compounds (VOCs) in 

soil gas from the auger holes or in headspace from heated bags 

containing soil were measured using a hand-held photoionization unit. Semisolid fragments of residual hydrocarbons and a 

strong hydrocarbon odor were detected in an auger hole near 

the southern edge of the remediated area. VOC concentrations 

as great as 50 mg/L were detected in the headspace from bags 

containing soil from that auger hole. Soil gas measured at a 

site located along a small dry streambed southwest of the spill 

site contained about 4 mg/L of VOCs. Soil gas measured at 

a site on the southwest side of the dry streambed contained 

about 1 mg/L of VOCs (Otton and Zielinski, 2000). Otton and 

Zielinski (2000) suggest that these data indicate that hydrocarbons are present in the subsurface along the tributary to Bear 

Branch. 

Crude Oil Release Site 2

The second crude oil release site is located about 360 m 

northeast of site 1 (fig. 4) and once included a spoil pit about 

30 m in diameter. Total petroleum hydrocarbon concentrations 

of 500 to 700 mg/kg have been detected in composite soil 

samples collected from the site (Otton and Zielinski, 2000). 

Remediation activities in 1993 and 1994 included mixing the 

sludge with soil, lime, and fertilizer; tilling the surface; and 

planting clover, winter wheat, and winter rye. The remediated 

area is along the crest of a ridge. A small erosional channel 

runs down the northwest side of the ridge to a small stream 

(fig. 4). 

During the 1999 study, soil gas samples were analyzed 

at several holes augered at this site (site BSF99-7 in Otton 

and Zielinski, 2000). Soil gas from auger holes in or near the 

remediated area contained 0.1 to 0.2 mg/L of VOCs. Soil gas 

samples collected from auger holes along the stream, just 

downgradient of the erosional channel, contained between 4.7 

and 13.9 mg/L of VOCs. Soil gas samples collected along the 

stream, just upstream from the erosional channel, contained 

between 0.2 and 0.9 mg/L of VOCs (Otton and Zielinski, 

2000). According to Otton and Zielinski (2000), hydrocarbons 

likely have been transported downslope from the former spoil 

pit to the stream by surface flow of oil, surface flow of water 

carrying dissolved hydrocarbons, or shallow ground water carrying dissolved hydrocarbons. 

Crude Oil Release Site 3

The third crude oil release site is located near a small 

unnamed tributary on the west side of New River about 8 km 

east of the BISO boundary (fig. 2), and includes an inactive 

pumping unit, two oil tanks, a pit filled with oil and water, 

and a brine pit (fig. 5). Of the three crude oil release sites, this 

was the only site at which the oil wells produced water (Otton 

and Zielinski, 2000). The oil- and water-filled pit is about 8 by 

12 m in size and about 3 m above the flood plain of the small 

stream (fig. 5). Soil gas concentrations were not measured 

during 1999 at this site (site BSF99-3 in Otton and Zielinski, 

2000). An oily sheen was noticed in a small pool of water 

between the pit and the stream, and visible evidence indicated that oil had spilled out of the pit and into the flood plain 

(Otton and Zielinski, 2000). 

Petroleum Hydrocarbons

Petroleum and petroleum products are highly complex 

and varied mixtures. Hydrocarbons (compounds containing 

only carbon and hydrogen atoms) compose the majority of 

the components in petroleum (Weisman, 1998). Crude oil can 

consist of thousands of individual compounds with hydrocarbons representing from 50 to 98 percent of the total weight of 

crude oil (Irwin and others, 1998). When petroleum compounds such as crude oil are released into the environment, 

the compounds undergo physical, chemical, and biological 

changes collectively referred to as weathering. The degree to 

which various types of petroleum hydrocarbons degrade under 

these changes depends on the physical and chemical properties 

of the hydrocarbons.

Types of Petroleum Hydrocarbons

Petroleum hydrocarbons are generally divided into two 

groups: aliphatics and aromatics. Aliphatics include alkanes 

that contain single bonds between carbon atoms and have 

formulas of CnH2n+2,, alkenes, which contain one or more 

double bonds between atoms and have formulas of CnH2n, and 

cycloalkanes, which contain carbon atoms in cyclic structures. 

Aromatics have one or more benzene rings as part of their 

structure. Monoaromatics are aromatics with one benzene ring 

as part of their structure; polycyclic aromatic hydrocarbons 

(PAHs) are aromatics with two or more fused benzene rings. 

Monoaromatics, such as benzene, toluene, ethylbenzene, and 

xylenes (BTEX), are some of the most common aromatic 

compounds in petroleum. Crude oil contains less BTEX than 

gasoline. Combining the average percentage weights for individual BTEX compounds (table 1) indicates that on average, 

BTEX compounds represent about 2 percent crude oil (by 

weight), which is consistent with data reported for crude oil 

samples collected from three different caverns that are used for 

storage in the Strategic Petroleum Reserve (U.S. Department 

Petroleum Hydrocarbons 
54

53

52

57

51

Oil tanks

Inactive pumping unit

Oil- and water-filled pit

Brine pit

Pit overflow

Unnamed tributary to New River

50 55

56

84 27'21" o 84 27'25" o

36 22'01" o

36 21'59" o

EXPLANATION

WATER SAMPLING LOCATION

AND MAP NUMBER

57

SOIL SAMPLING LOCATION

54 AND MAP NUMER

SOIL AND WATER SAMPLING

LOCATION AND MAP NUMBER

51

FEET

METERS

0 100

0 20 Base from U.S. Geological Survey

topographic quadrangles, 1:24,000

Lambert Conformal Conic projection

Standard parallels 35 15' N and

36 25' N, central meridian 86 W;

final map, Lambert Conformal Conic

projection Standard parallels 35 15'

N and 36 25' N, central meridian 86 W

0

0 0

0

0 0

Figure 5. Sampling locations at crude oil release site 3.

 Fate and Transport of Petroleum Hydrocarbons...Big South Fork National River and Recreation Area
Table 1. Physical, chemical, regulatory, and human health information for selected aromatic hydrocarbons.

[KOC, organic carbon-water partition coefficient; L/kg, liters per kilogram; mg/L, milligrams per liter; °C, degrees Celsius; MCL, drinking water maximum contaminant level; HB--, not available] 

Name

Typical amounts in crude oil1

(in weight percent) Physical and chemical properties Re

Average Minimum Maximum

Benzene 

(and total) 

rings

Number 

of carbon 

atoms

Molecular 

weight 

(grams)

K

oc

2

(L/kg)

Solubility in 

water2 (mg/L 

at 20 to 25 °C)

Henry’s law 

constant2

(dimensionless 

at 25 °C )

MCL

(mg/L

Benzene 0.16 0.040 0.41 1 6 78 59.0 1800 0.228 0.005 Toluene 0.67 0.080 2.5 1 7 92 182 530 0.272 1 Ethylebenze 0.17 0.056 0.31 1 8 106 363 170 0.323 0.7 Total xylenes -- -- -- -- -- -- -- -- -- 10  m-Xylene 0.66 0.080 2.0 1 8 106 407 160 0.301 --  o-Xylene 0.26 0.030 0.68 1 8 106 363 180 0.213 --  p-Xylene 0.26 0.090 0.68 1 8 106 389 190 0.314 -- Naphthalene 0.069 0.033 0.092 2 10 128 2,000 31 0.0198 -- Acenaphthene 0.0057 0.0057 0.0057 2 12 154 7,080 4.2 0.00636 -- Fluorene 0.020 0.0059 0.060 2 (3) 13 166 13,800 2.0 0.00261 -- Anthracene 0.0011 0.0011 0.0011 3 14 178 29,500 0.043 0.00267 -- Fluoranthene 0.00040 0.00020 0.00060 3 (4) 16 202 107,000 0.21 0.000660 -- Pyrene 0.00080 0.00040 0.0017 4 16 202 105,000 0.14 0.000450 -- Benz (a) anthracene 0.00030 0.00020 0.00070 4 18 228 398,000 0.0090 0.000140 -- Chrysene 0.0013 0.00070 0.0018 4 18 228 398,000 0.0016 0.00388 -- Benzo (a) pyrene 0.00020 0.00010 0.00040 5 20 252 1,020,000 0.0016 0.0000500 0.000Benzo (b) fluoranthene 0.00040 0.00040 0.00040 4 (5) 20 252 1,230,000 0.0015 0.00455 -- Benzo (k) fluoranthene 0.0016 0.0016 0.0016 4 (5) 20 252 1,230,000 0.00080 0.0000300 -- Ideno (1,2,3-c,d) pyrene 0.00070 0.00070 0.00070 5 (6) 22 276 3,470,000 0.000022 0.0000700 -- 

1 Potter and Simmons, 1998.2 U.S. Environmental Protection Agency, 1996a.3 U.S. Environmental Protection Agency, 2002.
of Energy, 2002). In samples from these caverns (each containing crude oil from multiple international sources), BTEX 

represented between 2.0 and 2.2 percent of the crude oil (by 

weight). Xylenes, toluene, benzene, and ethylbenzene represented 0.86 to 0.94, 0.74 to 0.81, 0.17 to 0.30, and 0.22 to 

0.24 percent by weight, respectively, of the crude oil (U.S. 

Department of Energy, 2002). On average, crude oil contains 

approximately 1 percent PAHs (Irwin and others, 1998). 

Typically, crude oil contains high concentrations of aliphatic 

hydrocarbons and lower concentrations of aromatic hydrocarbons (Potter and Simmons, 1998).

Natural gas condensates also are composed primarily of 

aliphatic hydrocarbons; however, the condensates may contain 

substantial amounts of BTEX. Samples of gas condensate liquids collected from sites in New Mexico, Colorado, Wyoming, 

and Alberta, Canada, contained BTEX concentrations representing from 3.4 to 15.0 percent of the total condensate weight 

(Hawthorne and Miller, 1998). Xylenes, toluene, benzene, and 

ethylbenzene represented 1.8 to 5.0, 1.1 to 5.4, 0.15 to 3.6, and 

0.31 to 0.63 percent, respectively, of the condensate weight. 

Rixey and others (1999) measured a maximum benzene 

concentration of 3.6 percent and mean benzene concentration 

of 1.0 percent (by weight) in 14 natural gas condensates, 12 

of which were collected from sites in the contiguous United 

States. 

Several aromatic hydrocarbons are known or suspected 

human carcinogens (table 1), and are classified as priority 

pollutants regulated by the U.S. Environmental Protection 

Agency (USEPA) (Office of the Federal Register, 2002). The 

BTEX compounds and 16 PAHs appear on The Clean Water 

Act Priority Pollutant list of 126 chemical substances (Office 

of the Federal Register, 2002). Benzene and PAHs are ranked 

sixth and ninth, respectively, on the 2001 Comprehensive 

Environmental Response, Compensation, and Liability Act 

Priority List of Hazardous Substances. This list is a prioritization of substances based on their frequency, toxicity, and 

potential for human exposure at sites on the National Priorities List (Agency for Toxic Substances and Disease Registry, 

2001). 

Cumulative concentrations of petroleum hydrocarbons 

commonly are referred to as total petroleum hydrocarbons 

(TPH). Many different analytical techniques including gravimetric, immunoassay, and gas chromatography (GC) have 

been used to measure TPH in soil and water. None of the 

techniques measure the entire range of petroleum hydrocarbons. The subsets of hydrocarbons detected by the techniques 

vary depending on the extraction and analytical methods used. 

For example, method 418.1 (U.S. Environmental Protection 

Agency, 1983) measures only hydrocarbons in the C6-C24 

range (6 to 24 carbon atoms). The terms gasoline range 

organic (GRO) and diesel range organic (DRO) have been 

used to refer to subsets of petroleum hydrocarbons detected by 

some of the techniques (mostly GC techniques). The subsets 

of hydrocarbons detected by these methods overlap; GRO 

typically includes hydrocarbons in the C5-C12 range, and 

DRO typically includes hydrocarbons in the C9-C36 range. 

Volatile petroleum hydrocarbons (VPH) and extractable petroleum hydrocarbons (EPH) are additional subsets of petroleum 

hydrocarbons detected by GC methods. VPH hydrocarbons 

include C5-C12 aliphatics, BTEX, methyl tertiary-butyl ether 

(MTBE), naphthalene, and C9-C10 aromatics. EPH hydrocarbons include C9-C36 aliphatics and C11-C22 aromatics.

Some states use site-specific target cleanup levels for 

petroleum contaminated soils; however, many states have 

established generic cleanup levels that typically include a 

cleanup level for either DRO or EPH. These levels vary 

greatly from state to state. Cleanup levels for DRO and EPH, 

for example, vary from 10 to 10,000 mg/kg (Nascarella and 

others, 2001). Cleanup levels established by the Tennessee 

Department of Environment and Conservation (1998) vary 

from 100 to 1,000 mg/kg for EPH and from 5.0 to 100 mg/kg 

for benzene, depending on ground-water and soil-permeability 

classifications.

Transport of Petroleum Hydrocarbons

Crude oil weathering processes include adsorption of 

hydrocarbons to soil particles, volatilization of hydrocarbons, 

and dissolution of hydrocarbons in water (Barakat and others, 2001). Alkanes and alkenes tend to be more volatile than 

aromatics. If volatilization is the most dominant weathering 

process, then the loss of lower molecular weight aliphatics will 

be the most substantial change in the crude oil, and aliphatics 

may be the principal air contaminants at spill sites (Potter and 

Simmons, 1998).

Less than 5 percent of crude oil will dissolve in water 

(Irwin and others, 1998). Aromatic hydrocarbons, especially 

BTEX, tend to be the most water-soluble fraction of crude 

oil and other petroleum compounds. Benzene (10 times 

more soluble than ethylbenzene or xylenes) is the most water 

soluble of the BTEX compounds (table 1). BTEX compounds 

also are the most volatile of the aromatic compounds and are 

considered to be VOCs. 

BTEX compounds have the lowest soil organic carbon 

sorption coefficients (Koc) of the most common aromatic 

hydrocarbons (table 1). Koc is the ratio of the amount of a 

compound sorbed to the organic matter component of soil or 

sediment to the amount of the compound in the aqueous phase 

at equilibrium, and has been used as one variable in predicting the mobility of a compound from soil to ground water. 

Benzene (Koc of 59) is considered to be highly mobile in soil, 

toluene (Koc of 182) is considered to be moderate to highly 

mobile in soil, and xylenes (Koc of 363 to 407) are considered 

to be moderately mobile in soil (U.S. Environmental Protection Agency, 1995).

Benzene often is the main ground-water contaminant of 

concern at petroleum release sites because of its high toxicity 

and mobility (as compared to other petroleum hydrocarbons). 

Plumes of benzene and other BTEX compounds have been 

detected in ground water near crude oil spills. At a site in 

Bemidji, Minn., benzene concentrations as great as 6.8 mg/L 

10 Fate and Transport of Petroleum Hydrocarbons...Big South Fork National River and Recreation Area
were detected in ground-water samples collected 16 years after 

1.7 million L of crude oil were spilled in 1979 (Cozzarelli and 

others, 2001).

Most PAHs, because of their low volatility, are classified as semivolatile organic compounds. In general, PAHs do 

not easily dissolve in water and are more likely to partition 

into sediments and soils rather than into ground water because 

of their low solubilities and high Kocs. As a result, transport 

of PAHs tends to be associated primarily with erosion of 

contaminated soils and sediments. PAHs sorbed to sediments 

may potentially affect aquatic communities downstream of 

contaminated sites (Irwin and others, 1998). The potential 

for colloid-facilitated transport of PAHs in ground water also 

has been documented. Geochemical changes caused by oil 

degradation mobilized a small amount of iron-rich colloids at 

the Bemidji, Minn., spill site and contributed to the transport 

of PAHs over great distances (Ryan and others, 1999). Some 

PAHs such as naphthalenes are more volatile and more water 

soluble than most PAHs (table 1), and can pose a threat to 

ground-water resources (Goerlitz and others, 1985). 

O’Reilly and others (2001) estimated potential dissolved 

concentrations of crude oil hydrocarbons (aromatics) in water 

and compared the estimated concentrations to maximum contaminant levels (MCLs) and water health based limits (HBLs) 

recommended by the USEPA. O’Reilly and others (2001) 

used published composition data for 69 crude oils, Raoult’s 

law, and published hydrocarbon solubility data to estimate 

the maximum dissolved concentrations (effective solubility) of benzene and 13 PAH compounds in water exposed to 

crude oil. MCLs were available for only benzo(a)pyrene and 

benzene. The estimated maximum dissolved concentration for 

benzo(a)pyrene [3.3 x10-4 μg/L] was well below the MCL of 

0.2 μg/L for benzo(a)pyrene; however, the estimated maximum dissolved concentration for benzene (27,000 μg/L) was 

well above the MCL of 5.0 μg/L for benzene. The estimated 

maximum dissolved concentrations did not exceed any of the 

recommended HBLs for the other PAHs examined (O’Reilly 

and others, 2001). Benzene concentrations may be greater 

than MCLs at gas condensate spill sites or sites where crude 

oil containing more than 300 mg of benzene per kg of oil 

(0.03 percent by weight) has been released (Rixey and others, 

1999). 

Biodegradation of Petroleum Hydrocarbons

Biodegradation is a major weathering process of crude 

oil and an important natural attenuation process. Rates of 

biodegradation vary with different microbial populations, 

hydrocarbons, and geochemical and hydrological conditions 

present in the subsurface. Nearly all soils and sediments have 

populations of bacteria and other organisms capable of degrading petroleum hydrocarbons (Kennedy and others, 2000; 

Potter and Simmons, 1998; U.S. Environmental Protection 

Agency, 1999; Wiedemeier and others, 1995). Hydrocarbondegrading bacteria can be present in low numbers in unpolluted environments; however, microbial populations can 

adapt and reach high densities after coming into contact with 

released petroleum compounds (Wisconsin Department of 

Natural Resources, 1994). Generally, petroleum hydrocarbons 

and other organic molecules with abundant carbon-hydrogen 

bonds are good food sources (electron donors) because they 

contain high-energy electrons.

Soil and ground-water bacteria use a variety of natural 

electron acceptors in the degradation process. The use of 

these final electron acceptors is not arbitrary but is based on 

energy transfer efficiency and availability (Montgomery and 

others, 1994). The most common inorganic electron acceptor in ground water is dissolved oxygen (DO). Once DO has 

been depleted, bacteria will preferentially use the next most 

efficient electron acceptor—usually this is nitrate (NO3

-

) or 

insoluble manganese (Mn4+). After NO3

-

 and Mn4+ have been 

depleted, the bacteria will use ferric iron (Fe3+), followed by 

sulfate (SO4

2-), and carbon dioxide (CO2

), respectively. During 

the reduction of these electron acceptors CO2, ammonia (NH3), 

soluble manganese (Mn2+) and iron (Fe2+), sulfide (S2-), and 

methane (CH4) are produced. 

Bacteria responsible for biodegradation commonly are 

categorized by their terminal electron acceptor processes 

(TEAP). Types of bacteria include aerobic bacteria, which 

use DO as their TEAP, nitrate-reducing bacteria, iron- and 

manganese-reducing bacteria, sulfur-reducing bacteria, 

and methanogenic bacteria. Pseudomonas bacteria are 

free-­swimming aerobic bacteria known to degrade BTEX 

(­Chapelle, 2000). 

Biodegradation rates for the various types of petroleum 

hydrocarbons depend on the TEAP occurring. The sequence 

of preferential electron acceptor processes has been shown to 

cause zones of different electron-accepting processes dominating in different redox zones in contaminant plumes (Godsy 

and others, 1999). Geochemical and microbiological data 

can be used to delineate the zones and to obtain information 

on possible degradation rates. Biodegradation rates of low to 

moderate weight aliphatic, alicyclic, and aromatic hydrocarbons can be high if ideal conditions are present. Resistance to 

biodegradation typically increases as the molecular weight of 

the hydrocarbon increases (Wiedemeier and others, 1995).

At the Bemidji, Minn. crude oil spill site, microorganisms have degraded BTEX compounds in the ground water, 

and biodegradation has slowed the movement of BTEX 

compounds (Cozzarelli and others, 2001). Many of the soluble 

hydrocarbons are degraded in an anoxic zone that has developed downgradient of the oil body, but benzene has been more 

recalcitrant under anoxic conditions and has migrated farther 

downgradient than other BTEX hydrocarbons (Eganhouse 

and others, 1996). Field studies at a crude oil spill site in India 

indicated that up to 75 percent of the hydrocarbons present 

could be biodegraded within a year if the proper geochemical 

and microbial consortia are present (Gogoi and others, 2003).

Multiple lines of evidence generally are needed to 

demonstrate biodegradation processes at contaminated sites 

(National Research Council, 1993; Wiedemeier and others, 

Petroleum Hydrocarbons 11
1995). The lines of evidence used to examine biodegradation 

of petroleum hydrocarbons include (1) chemical data that 

indicate decreasing concentrations of petroleum hydrocarbons, (2) geochemical data that indicate depletion of electron 

acceptors, and (3) laboratory or field microbiological data that 

indicate the bacteria present at a site can degrade petroleum 

hydrocarbons (U.S. Environmental Protection Agency, 1997).

Methods

Various methods were used to gather information for the 

investigation. To provide background information on oil and 

gas production operations in BISO and to aid in the selection 

of sampling locations for the investigation, oil and gas well 

records were obtained from State and Federal agencies, and 

an inventory of available water wells and springs in BISO was 

compiled from information provided by NPS. During the first 

stage of the investigation (the ground-water-quality reconnaissance), water samples were collected from springs, wells, and 

a few surface-water sites. Water samples collected during the 

reconnaissance were analyzed for physical properties (temperature, DO, pH, and specific conductance), VOCs, and selected 

types of bacteria. During the second stage of the investigation, 

additional water samples were collected from selected reconnaissance sites to obtain additional information on background 

water-quality conditions. Samples collected during the second 

stage of the investigation were analyzed for physical properties, geochemical indicators, VOCs, DRO, and selected 

types of bacteria. During the third stage of the investigation, 

soil gas, soil, water, and crude oil samples were collected to 

evaluate the fate and transport of petroleum hydrocarbons at 

the crude oil release sites. Soil gas samples were analyzed 

for VOCs. Soil samples were analyzed for VOCs, DRO, and 

selected types of bacteria. Water samples were analyzed for 

physical properties, geochemical indicators, VOCs, DRO, and 

selected types of bacteria. A fresh crude oil sample collected 

from an active production well at one of the release sites was 

used during a laboratory study examining the dissolution of 

petroleum hydrocarbons into water. 

Sample Collection and Preservation

Water samples were collected from 29 sites during the 

investigation. Water samples were collected from springs 

close to the surface discharge points. Samples typically were 

collected by dipping containers into springs. Some springs 

were enclosed and samples were collected from discharge 

pipes coming from the springs. Water samples were collected 

from wells after the wells had either been pumped for several 

hours or after measurements of temperature, DO, specific conductance, and pH had stabilized. Samples were collected from 

a spigot closest to the well head. Water samples were collected from auger holes by using bailers. Samples for selected 

geochemical indicators were filtered and acidified following 

methods described by Wilde and others (1999). 

Water samples for VOCs were collected in 40-mL glass 

vials and acidified following methods described by Wilde and 

others (1999). Quality-control procedures for VOC sampling 

included the collection of duplicate samples and trip blanks. 

Water samples analyzed for DRO organics using field screening methods were collected in 40-mL glass vials. Duplicate 

samples for laboratory analysis of DRO were collected in 

glass containers provided by the laboratory. Water samples 

for microbiological analysis were collected in sterilized glass 

containers. All water samples were stored at approximately 

2 °C (degrees Celsius) until analyzed. 

Soil gas surveys were performed using methods 

described by USEPA (1996b). A 0.95-cm-diameter hole was 

driven into the ground to a depth of about 1.2 m using a slam 

bar. A 0.64-cm-diameter stainless steel probe was inserted into 

the hole, and the hole was sealed by tightly packing soil into 

the top of the hole. An air sampling pump and Teflon tubing 

was used to purge the probes and to transfer soil gas samples 

to 1-L Tedlar bags (U.S. Environmental Protection Agency, 

1994c). 

Hand augers were used to obtain soil samples from 

selected depths below land surface. Soil samples for field 

screening of petroleum hydrocarbons were collected using 

methods described by Hewitt and Myers (1999) and were 

preserved using method 5035 (U.S. Environmental Protection Agency, 1996c). Modified 10-mL syringes were used to 

transfer approximately 5 g of soil to a preweighed sample vial 

(40-mL VOC vial) that contained 1 g of sodium biosulfate 

preservative and 20 mL of volatile grade blank water (VBW). 

The vial was then sealed and weighed. Duplicate soil samples 

for laboratory analysis of VOCs were collected in EnCore 

samplers (U.S. Environmental Protection Agency, 1996c). Soil 

samples analyzed for DRO using field screening methods were 

collected in 40-mL glass vials. Duplicate samples for laboratory analysis of DRO and for percent moisture were collected 

in glass containers provided by the laboratory. Soil samples 

for microbiological analysis were collected in sterilized glass 

containers. All soil samples were stored at approximately 2 °C 

until analyzed. 

A crude oil sample was collected from a production well 

at site 1. The crude oil sample was collected from a valve at 

the pumping unit. The sample was collected in a 40-mL VOC 

vial and was stored at approximately 2 °C. The sample was 

used during a laboratory study to examine the dissolution of 

BTEX from crude oil. 

Physical Properties and Geochemical Analyses

Physical water-quality properties such as temperature, 

specific conductance, and pH were measured in the field using 

water-quality meters and methods described by Wilde and 

Radtke (1998). The probes for the water-quality meters were 

placed directly in the water body, if possible. If the probes 

12 Fate and Transport of Petroleum Hydrocarbons...Big South Fork National River and Recreation Area
could not be placed in the water body, samples were collected 

in clean containers, the probes were placed in the containers, 

and measurements were made. 

Geochemical data were collected using titrametric or 

spectrophotometric methods described by the Hach Company 

(1992) and included alkalinity, DO, NO3

-

, NH3, Fe2+, SO4

2-, 

S2-, and chloride, and total iron concentrations. Water-­quality 

meters were calibrated following procedures described by the 

Hach Company (2001). Quality control procedures during 

spectrophotometric analyses included the analysis of blanks 

and quality control standards as described by the Hach Company (1992). 

Selected duplicate water samples were sent to the USGS 

Water Quality and Research Laboratory (WQRL) in Ocala, 

Fla. WQRL used methods I-2540-85, I-2545-85, and I-2522-

85 (Fishman, 1993) to analyze for nitrite (NO2

-

), NO2

-

 plus 

NO3

-

, and NH3, respectively. WQRL used method I-2057-

85 (Fishman and Friedman, 1989) to analyze for SO4

2- and 

chloride and method 200.7 (U.S. Environmental Protection 

Agency, 1994a) to analyze for Fe2+. 

Petroleum Hydrocarbon Analyses

Soil gas, soil, and water samples were screened for VOCs 

using a portable GC and methods described by Williams and 

Farmer (2003). The sample injection methods described in 

Williams and Farmer (2003) were modified for soil gas and 

soil samples. Soil gas samples were injected into the GC 

through the analysis port following methods described by 

USEPA (1994b). Soil samples were purged using a Sentex 

40-mL Vial Purge System. This system contained two needles 

that were inserted into septa-capped sample vials. The longer 

needle extended to the bottom of the vial and was used to 

purge samples; the shorter needle extended only into the top 

of the vial and was used to transfer purged VOCs from the 

headspace of the vial to the trap located in the GC. 

Analytical standards containing 50 mg/L each of benzene, ethylbenzene, toluene, o-xylene, m-xylene, and pxylene, naphthalene, and methyl tertiary butyl ether were 

used to prepare calibration standards. Analytical runs of about 

8 minutes were used to screen for BTEX and other VOCs 

in soil gas, soil, and water samples. VOCs were tentatively 

identified as being BTEX compounds if the retention time of 

the compound was within 5 percent of the retention time of the 

BTEX compound. VOCs tentatively identified may or may not 

have actually been a BTEX compound because many VOCs 

have similar retention times. Concentrations of unidentified 

VOCs were estimated by comparing the peak areas of these 

compounds to a calibration curve created using peak areas for 

BTEX compounds. The concentrations of tentatively identified BTEX compounds and unidentified VOCs were summed 

to obtain an estimated total concentration for the VOCs 

detected. The capacity of the portable GC to measure VOCs 

has been evaluated by the USEPA Superfund Innovative Technology Evaluation (SITE) Program (Einfeld, 1998).

Duplicates of selected soil samples and water samples 

were sent to the USGS National Water Quality Laboratory 

(NWQL) and to Severn Trent Laboratories (STL), both in 

Denver, Colorado. NWQL used gas chromatography/mass 

spectrometry (GC/MS) methods (Connor and others, 1998) 

to analyze for BTEX compounds in water. STL used methods 

5035 and 8260B (U.S. Environmental Protection Agency, 

1996c) to prepare and analyze soil samples for BTEX compounds. STL measured percent moisture in soil samples by 

using method 160.3 (U.S. Environmental Protection Agency, 

1983).

Soil and water samples were analyzed for DRO compounds using SiteLAB field screening methods, which incorporate fluorescence-based analytical techniques (SiteLAB 

Corporation, 2001). Aromatic hydrocarbons absorb light 

energy of specific wavelengths (excitation wavelengths) and 

emit light energy at longer wavelengths (emission wavelengths) (Tetra Tech EM Inc., 2001). Because fluorescence 

increases with hydrocarbon concentration, fluorometers 

equipped with specific excitation and emission filters can 

measure specific types of aromatic hydrocarbons. Monoaromatic compounds such as BTEX have emission wavelengths 

of about 280 nanometers (nm), two- to three-ring aromatics 

have an emission wavelength of approximately 330 nm, and 

aromatics with greater than three rings have an emission wavelength of approximately 380 nm (California Environmental 

Protection Agency, 1997). Emission filters with a bandwidth 

between 275 and 285 nm can be used to measure GRO petroleum hydrocarbons, and emission filters with a bandwidth 

between 300 and 400 nm can be used to measure DRO petroleum hydrocarbons (Tetra Tech EM Inc., 2001).

The SiteLAB method uses methanol to extract hydrocarbons from soil or water samples (SiteLAB Corporation, 2001). 

The soil extraction process is similar to that used for enzyme 

immunoassay techniques in USEPA SW-846 method 4030 

(Greason, 1997). Hydrocarbons were extracted from samples 

using methods described by the SiteLAB Corporation (2001). 

Methanol-extracted solutions were diluted if necessary and 

analyzed using a fluorometer (Turner Designs TD-700). The 

fluorometer was equipped with a clear quartz mercury vapor 

lamp with a predominant emission of 254 nm wavelength 

(Turner Designs 10-046), an excitation filter with a bandwidth 

of 254 (Turner Designs 10-038R), an emission filter with a 

bandwidth from 300 to 400 nm (Turner Designs 10-069R), 

and a red sensitive photomultiplier tube detector (185 to 

870 nm). With this configuration, the fluorometer was capable 

of detecting aromatic DRO compounds up to C40 molecular 

weight (Greason, 1997).

Quality-control procedures include the analysis of calibration standards and equipment blanks. Calibration standards 

containing known concentrations (0.1 to 5 mg/L) of DRO 

were purchased from SiteLAB (DRO C10-C40 aromatics 

standard kit). Equipment blanks were used to account for any 

interference from the methanol and disposable plastic containers and materials used during the extraction procedure (Greason, 1997). The Massachusetts Department of Environmental 

Methods 13
Protection (MDEP) evaluated SiteLAB methods and volatile 

and extractable petroleum hydrocarbon methods used by 

29 laboratories. The MDEP evaluation determined that the 

SiteLAB field method produced results of similar accuracy to 

that of the laboratory methods (Kinney, 1998). The USEPA 

Environmental Technology Verification Program also has 

evaluated SiteLAB methods for measuring TPH in soil. The 

USEPA evaluation determined that the SiteLAB method 

exhibited good accuracy and precision and is a reliable field 

measurement method for TPH in soil (Tetra Tech EM Inc., 

2001). Selected duplicate soil samples and water samples were 

analyzed by STL for DRO using method 8015B (U.S. Environmental Protection Agency, 1996c).

Microbiological Analyses

Semi-quantitative biological activity reaction tests 

(BARTs), described by Cullimore (1993), were used to 

examine water and soil samples for the presence of viable 

bacteria. BARTs consist of a capped sample vial containing a 

floating ball and crystallized selective medium attached to the 

floor of the vial. After water samples are added to the BART 

container, the floating ball restricts the entry of oxygen into 

the sample below creating selective growth conditions for 

any bacteria present. The selective culture medium varies 

for different types of bacteria. During this study, BARTs for 

total aerobic heterotrophic bacteria, denitrifying bacteria, 

iron-related bacteria, SO4

2--reducing bacteria, fluorescing 

Pseudomonas, and slime forming bacteria were used. Bacterial 

activity is detected by looking for specific growth activities 

and reactions associated with each type of BART. Growth 

activities include the formation of clouds, slimes, and gels. 

Reactions include color changes, development of gasses, and 

precipitation of dissolved constituents. The rates at which 

these activities and reactions occur can sometimes be used 

to quantify bacteria populations (Droycon Bioconcepts Inc., 

2003). 

Membrane filtration plate counts were used to quantify 

hydrocarbon- (crude oil and diesel) degrading bacteria in soil 

and water samples. Bacteria were extracted from soil samples 

by placing 50 g of soil in 200 mL of sterile homogenization 

buffer and agitating in a blender for 1 minute. The mixture 

was placed in an ice water bath for 1 minute. This procedure 

was repeated three times. The mixture was centrifuged at 640 

times the force of gravity for 15 minutes at 4 °C. The supernatant was transferred to a sterile 250-mL tube and centrifuged 

at 15,000 g for 20 minutes at 4 °C. The above steps were 

repeated two times using the original 50-g soil sample. The 

resulting bacterial pellet was suspended in 10 mL of sterile 

phosphate buffered solution (PBS). 

Water samples and bacteria solutions extracted from 

soil samples were serially diluted (into 100 mL of sterile 

PBS) eight times using a 0.1 dilution factor each time. Three 

replicates were prepared for each dilution. All three sets of 

replicates were filtered [47-mm (millimeter) diameter, 0.4-mm 

pore size filters] and a set of replicates was placed on one of 

three types of agar plates. The first type of plate was used 

to quantify crude oil degrading bacteria and consisted of 

Bushnell-Haas broth (Bushnell and Hass, 1941) containing 

1 percent agar and 100 microliters (μL) of p-iodonitroterazolium violet solution and 500 μL of crude oil spread on top 

of the solidified broth. The second type of plate was used to 

quantify diesel-degrading bacteria and consisted of BushnellHaas broth containing 1 percent agar and 100 μL of p-iodonitroterazolium violet solution and 500 μL of diesel fuel 

spread on top of the solidified broth. The third type of plate 

was used to quantify total heterotrophic bacteria and contained 

tryptic-soy agar. The p-iodonitroterazolium violet solution 

consisted of 3 milligrams (mg) of p-iodonitroterazolium violet 

dissolved into 3 mL of sterilized distilled water. 

A positive control was prepared by filtering a solution 

containing Pseudomonas aeruginosa and placing these filters 

onto the various agar plates. A negative control was prepared 

by filtering an undiluted bacteria extraction from one of the 

sampling locations and a solution containing Pseudomonas 

aeruginosa and placing these filters onto plates of BushnellHaas broth containing 1 percent agar and 100 μL of p-iodonitroterazolium violet. The plates were incubated at 25 °C and 

then evaluated, and bacteria were counted at 48 and 72 hours.

Crude Oil Dissolution Study

Crude oil samples from site 1 were placed in volatile 

blank water (VBW) to monitor the dissolution of BTEX and 

other soluble petroleum hydrocarbons from the crude oil. 

Three replicates were created, each containing 3 mL of crude 

oil in 1-L glass bottles containing VBW and a stir bar. The 

bottles were sealed with solid Teflon-lined caps and were 

placed on stir plates. After 4 days of stirring, water samples 

were removed from two of the bottles and analyzed for BTEX 

and other VOCs. After 6 additional days of stirring, a water 

sample was removed from the third bottle and analyzed to 

determine if additional dissolution of BTEX and other VOCs 

had occurred. Water samples were analyzed using the methods 

previously described for environmental water samples. 

Ground-Water Quality and Potential 

Natural Attenuation

This investigation had three stages of monitoring and 

research activities. The ground-water-quality reconnaissance 

was completed during June 2002. During the reconnaissance, 

water samples were collected from 24 locations (17 springs, 5 

water-supply wells, 1 small stream, and 1 spring-fed pond) in 

and near BISO (fig. 2). More detailed water-quality sampling 

was completed during July 2002. During this second stage 

of the investigation, additional water samples were collected from three springs and two wells sampled during the 

14  Fate and Transport of Petroleum Hydrocarbons...Big South Fork National River and Recreation Area
reconnaissance. Sampling at the three crude oil release sites 

(the third stage of the investigation) occurred from September 

2002 through February 2003.

Ground-Water-Quality Reconnaissance

In June 2002, water samples were collected from 17 

springs, 5 water supply wells, 1 small stream, and 1 springfed pond in and near BISO. The reconnaissance and sampling 

was conducted during a relatively dry period. Total monthly 

precipitation in the vicinity of BISO for April through June 

2002 was below average (National Oceanic and Atmospheric 

Administration, 2002). Most of the springs located and 

sampled during the reconnaissance were small. Estimated 

discharges ranged from less than 0.02 to 0.13 L/s (table 2). 

The specific conductance of water samples from springs 

generally ranged from 8 to 45 μS/cm (microsiemens per centimeter) with one exception. The highest specific conductance 

in a water sample collected from a spring was 105 μS/cm at 

sampling location 17, which is a spring that emerges from 

the top of a shale layer. The specific conductance of water 

samples collected from wells generally ranged from 30 to 

42 μS/cm, but water from one well had a specific conductance 

of 460 μS/cm. DO concentrations in water samples ranged 

from 0.8 to 10.7 mg/L. Most samples were well oxygenated. 

Only two samples contained less than 5 mg/L of DO, and only 

two samples had a specific conductance greater than 50 μS/cm 

(table 2). The sample containing the least DO (0.8 mg/L) and 

the highest specific conductance (460 μS/cm) was from a 

water-supply well (sampling location 7) near a stream that is 

about 6 km northwest of and about 200 m lower in elevation 

than the location of the other wells sampled.

BTEX compounds were not detected in any of the 

water-quality samples collected during the reconnaissance 

of ground-water-quality conditions in BISO (table 2). BTEX 

detection limits for the portable GC used to screen the water 

samples ranged from 0.5 to 1 μg/L. The lack of BTEX detections in ground-water samples from various locations indicates 

that contamination of ground-water resources by dissolved 

petroleum hydrocarbons in BISO is probably not widespread.

Background Water-Quality Conditions

Sampling locations 2, 3, 7, 15, 16, and 18 from the reconnaissance were selected for additional water-quality sampling 

to obtain additional information on water quality away from 

areas of oil and gas production. Samples were collected in 

July 2002, when total monthly precipitation for the area was 

again below average (National Oceanic and Atmospheric 

Administration, 2002). Samples were again analyzed for 

physical properties and VOCs to determine if any temporal 

variations existed in ground-water-quality conditions (table 3). 

Water samples could not be collected from sampling location 

2 because this spring was dry during the sampling on July 30 

and 31, 2002. Most samples were well oxygenated, generally ranging from 6.4 to 7 mg/L of DO. Specific conductance 

generally ranged from 13 to 40 μS/cm. Once again, the sample 

containing the least DO (2.8 mg/L) and the highest specific 

conductance (384 μS/cm) was collected from sampling location 7. BTEX compounds were not detected in any of the additional water-quality samples collected in July 2002 (table 3). 

The water samples collected during July 2002 also were 

analyzed for geochemical indicators, DRO, and selected 

bacteria. Dissolved NH3, Fe2+, and S2- concentrations were not 

detected in any of the water samples collected from sites 3, 7, 

15, 16, and 18 (table 4). DRO compounds were not detected in 

any of the water samples from these sites (table 4). The detection limit for the field screening method used to analyze for 

DRO was 0.10 mg/L. Bacteria associated with the biodegradation of petroleum hydrocarbons were detected in several of the 

water samples collected at sampling locations 3, 7, 15, 16, and 

18 during July 2002 (table 5).

Crude Oil Release Site 1

Water, soil gas, and soil samples were collected at site 1 

during September and December 2002. The samples were 

analyzed to evaluate potential contamination and biodegradation at the site. Although total monthly precipitation in the 

area for September and December 2002 was above average, 

both months were preceded by below average precipitation 

(National Oceanic and Atmospheric Administration, 2002). 

Both springs at site 1 (sampling locations 21 and 22) were 

dry when soil gas and soil samples were collected during 

September 2002 (table 3). On December 3, 2002, the spring at 

sampling location 22 was still dry; however, a small amount 

of flow was discharging from the spring at sampling location 

21 (water samples had to be collected in a cup for measurement of physical properties). Water collected at location 21 

had a specific conductance of 34 μS/cm (table 3) with low 

concentrations for dissolved NO3

-

, NH3, Fe2+, SO4

2-, S2-, and 

DRO. The dissolved chloride concentrations were 5.4 to 

7.4 mg/L (table 4). Water samples from sampling location 21 

analyzed using field screening methods did not contain detectable concentrations of BTEX or DRO (tables 3 and 4). BTEX 

compounds also were not detected in a duplicate water sample 

from sampling location 21 analyzed by STL (table 3). 

Soil gas samples were collected at 13 sampling locations 

(numbers 25 through 37) at site 1 during September 2002 

(table 6). The greatest number of VOCs (16) and the highest estimated total VOC concentrations (about 40 μg/L) were 

detected in a soil gas sample from location 26 (table 6). This 

sample was collected near the old tank battery location and 

is within the area that was remediated after the spill in 1993 

(fig. 4). At least seven VOCs were detected in every soil gas 

sample collected at site 1 (table 6). Many of these detected 

VOCs had GC retention times near the retention times for 

BTEX compounds. Estimated total VOC concentrations for 

the other soil gas samples collected at this site ranged from 

about 1 to about 2.7 μg/L (table 6). These estimates represent 

Ground-Water Quality and Potential Natural Attenuation 15
Table 2. Physical properties and volatile organic compound data for water samples collected during the ground-water-quality reconnaissance, June 

[USGS, U.S. Geological Survey; o, degrees;  ́, minutes;  ̋, seconds; L/s, liters per second; oC, degrees Celsius; μS/cm, microsiemens per centimeter; mg/L, milligrams per liter; <, 

Sampling 

site 

number

Type of site USGS number Sampling date

Physical properties Volatile organic compound 

Estimated 

discharge 

(L/s)

Temperature 

(oC)

Specific 

conductance 

(μS/cm)

pH (standard units) Dissolved oxygen (mg/L) Benzene Toluene Eth

benz

1 Stream 3408510 06/11/2002 <0.02 18.0 32 6.6 8.3 <0.5 <0.5 <

2 Spring 362515084390501 06/11/2002 <0.02 15.5 9 5.9 9.5 <0.5 <0.5 <

3 Well 362916084415901 06/12/2002 -- 17.5 30 5.7 7.9 <0.5 <0.5 <

4 Well 362925084415301 06/12/2002 -- 15.0 34 6.0 8.8 <0.5 <0.5 <

5 Well 362920084415401 06/12/2002 -- 16.0 42 6.0 7.0 <0.5 <0.5 <

6 Well 362919084414701 06/12/2002 -- 15.5 38 6.1 7.8 <0.5 <0.5 <

7 Well 363215084433801 06/12/2002 -- 16.0 460 9.1 0.8 <0.5 <0.5 <

8 Spring 362839084404601 06/12/2002 <0.02 15.0 19 4.8 9.3 <0.5 <0.5 <

9 Spring 362849084410401 06/12/2002 <0.02 15.5 45 7.1 10.6 <0.5 <0.5 <

10 Spring 362939084430401 06/12/2002 <0.02 15.5 32 6.4 9.1 <0.5 <0.5 <

11 Spring 363007084404901 06/13/2002 <0.02 17.5 16 5.1 6.7 <0.5 <0.5 <

12 Spring 363238084375401 06/13/2002 <0.02 13.5 12 4.8 8.1 <0.5 <0.5 <

13 Spring 363237084375401 06/13/2002 <0.02 18.0 17 6.2 9.5 <0.5 <0.5 <

14 Pond 362249084422201 06/24/2002 0.00 24.0 45 5.7 1.7 <0.5 <0.5 <

15 Spring 362544084442201 06/24/2002 0.06 17.0 17 5.9 9.5 <0.5 <0.5 <

16 Spring 362833084333901 06/25/2002 0.02 15.5 45 5.5 9.7 <0.5 <0.5 <

17 Spring 362811084352901 06/25/2002 0.13 17.5 105 6.4 8.6 <0.5 <0.5 <

18 Spring 362728084371801 06/25/2002 0.03 16.0 34 7.1 9.8 <0.5 <0.5 <

19 Spring 362719084392301 06/25/2002 0.06 18.5 18 6.3 8.1 <0.5 <0.5 <

20 Spring 362413084344401 06/25/2002 0.09 15.5 15 4.7 7.7 <0.5 <0.5 <

21 Spring 362315084394201 06/12/2002 <0.02 17.5 8 5.8 8.7 <0.5 <0.5 <

22 Spring 362314084393801 06/12/2002 <0.02 14.5 14 5.9 7.5 <0.5 <0.5 <

23 Spring 362320084393301 06/12/2002 <0.02 16.5 12 7.0 10.7 <0.5 <0.5 <

24 Spring 362322084392501 06/12/2002 <0.02 15.0 18 5.6 5.4 <0.5 <0.5 <
Table 3. Physical properties and volatile organic compound data for water samples collected after reconnaissance, July 2002 - Februa

[L/s, liters per second; μS/cm; microsiemens per centimeter; mg/L, milligrams per liter; --, no data; <, less than]

Physical properties Volatile organic compoun

(micrograms per liter

Sampling

location

Type of

location

Sampling

date

Type of 

analysis

Estimated

discharge

(L/s)

Temperature

(°C)

Specific

conductance

(μS/cm)

pH

(standard

units)

Dissolved

oxygen

(mg/L)

Benzene Toluene Ethyl- benzene m-Xy

a

p-Xy

3 Well 07/31/2002 Field -- 19.5 31 5.9 6.6 <0.5 <0.5 <0.5 <

7 Well 07/31/2002 Field -- 14.0 384 8.4 2.8 <0.5 <0.5 <0.5 <

15 Spring 07/30/2002 Field 0.04 18.5 13 6.9 7.0 <0.5 <0.5 <0.5 <

16 Spring 07/30/2002 Field <0.02 17.5 40 5.9 6.9 <0.5 <0.5 <0.5 <

18 Spring 07/30/2002 Field <0.02 18.0 32 6.5 6.4 <0.5 <0.5 <0.5 <

Site 1

21 Spring 09/03/2002 -- Dry -- -- -- -- -- -- -- 

21 Spring 12/03/2002 Field <0.02 -- 34 5.7 -- <0.5 <0.5 <0.5 <

21 Spring 12/03/2002 Laboratory -- -- -- -- -- <0.2 <0.2 <0.2 <

22 Spring 09/03/2002 -- Dry -- -- -- -- -- -- -- 22 Spring 12/03/2002 -- Dry -- -- -- -- -- -- -- 

Site 2

23 Spring 09/03/2002 Field <0.02 -- 11 7.3 5.4 <0.5 <0.5 <0.5 <

23 Spring 09/03/2002 Laboratory -- -- -- -- -- <0.2 <0.2 <0.2 <

23 Spring 12/03/2002 Field <0.02 -- 9 6.4 -- <0.5 <0.5 <0.5 <

24 Spring 09/03/2002 -- Dry -- -- -- -- -- -- -- 24 Spring 12/03/2002 Field <0.02 -- 16 5.7 -- <0.5 <0.5 <0.5 <

24 Spring 02/19/2003 Field <0.02 -- -- -- -- <0.5 <0.5 <0.5 <

Site 3

50 Auger hole 12/10/2002 Field -- -- 3,440 6.8 -- <0.5 <0.5 <0.5 <

51 Auger hole 12/10/2002 Field -- -- 7,600 6.0 -- <0.5 <0.5 <0.5 <

51 Auger hole 12/10/2002 Laboratory -- -- -- -- -- -- -- -- 55 Auger hole 12/10/2002 Field -- -- 577 4.7 -- <0.5 <0.5 <0.5 <

55 Auger hole 12/10/2002 Laboratory -- -- -- -- -- <0.2 <0.2 <0.2 <

57 Spring 02/19/2003 Field <0.02 -- -- -- -- <0.5 <0.5 <0.5 <
Table 4. Geochemcial and diesel range organic compound data for water samples collected after reconnaissance, July 2002 - 

February 2003.

[CaCO3, calcium carbonate; N, nitrogen; Fe, iron; SO4, sulfate; S2-, sulfide; Cl, chloride; mg/L, milligrams per liter; --, no data; <, less than]

Sampling

location

Type of

location

Sampling

date

Type

of

analysis

Geochemical data Diesel 

range 

organics 

(mg/L)

Alkalinity

 (as 

CaCO3)

Nitrate,

dissolved

(as N)

Ammonia,

dissolved

 (as N)

Iron,

 total

(mg/L

as Fe)

Iron,

dissolved

(mg/L

as Fe)

Sulfate,

dissolved

(mg/L

as SO4)

Sulfide,

dissolved

(mg/L

as S2-)

Chloride,

dissolved

(mg/L

as Cl)

3 Well 07/31/2002 Field 8.9 0.7 <0.01 0.02 <0.01 <1 <0.001 0.6 <0.10

7 Well 07/31/2002 Field 160 0.1 <0.01 0.09 <0.01 19 <0.001 5.0 <0.10

15 Spring 07/30/2002 Field 4.0 0.1 <0.01 <0.01 <0.01 <1 <0.001 0.7 <0.10

16 Spring 07/30/2002 Field 2.9 1.8 <0.01 0.03 <0.01 <1 <0.001 3.6 <0.10

18 Spring 07/30/2002 Field 12 0.2 <0.01 0.02 <0.01 <1 <0.001 0.5 <0.10

Site 1

21 Spring 09/03/2002 -- -- -- -- -- -- -- -- -- --

21 Spring 12/03/2002 Field 0.40 0.1 0.04 0.07 0.02 <1 0.002 5.4 <0.10

21 Spring 12/03/2002 Laboratory -- <0.02 <0.01 -- 0.03 1.2 -- 7.4

22 Spring 09/03/2002 -- -- -- -- -- -- -- -- -- --

22 Spring 12/03/2002 -- -- -- -- -- -- -- -- -- --

Site 2

23 Spring 09/03/2002 Field 1.1 <0.1 <0.01 0.01 <0.01 <1 <0.001 0.9 1.7

23 Spring 09/03/2002 Laboratory -- <0.02 <0.01 -- 0.01 0.4 -- -- <0.25

23 Spring 12/03/2002 Field 1.1 <0.1 <0.01 0.01 0.01 <1 0.001 0.5 <0.10

24 Spring 09/03/2002 -- -- -- -- -- -- -- -- -- --

24 Spring 12/03/2002 Field 1.5 0.1 0.01 0.05 0.01 <1 0.003 0.8 <0.10

24 Spring 02/19/2003 Field -- -- -- -- -- -- -- -- --

Site 3

50 Auger hole 12/10/2002 Field -- -- -- -- -- -- -- -- 40

51 Auger hole 12/10/2002 Field 63 0.2 2.00 31.2 25.2 58 0.013 4,000 <0.10

51 Auger hole 12/10/2002 Laboratory -- <0.02 0.68 -- 28.9 59 -- 2,590 --

55 Auger hole 12/10/2002 Field 0.28 0.0 0.23 0.26 0.02 190 0.011 22.3 <0.10

55 Auger hole 12/10/2002 Laboratory -- -- -- -- -- -- -- -- --

57 Spring 02/19/2003 Field -- -- -- -- -- -- -- -- --

18  Fate and Transport of Petroleum Hydrocarbons...Big South Fork National River and Recreation Area
Table 5. Summary of results from biological activity reaction tests (BARTs), July 2002 - December 2002.

[NA, not applicable; D, duplicate sample; SFB, slime-forming bacteria; IRB, iron-related bacteria; SRB, sulfate-reducing bacteria; DNF, denitrifying bacteria; HB, heterotrophic phate buffer solution; some BARTs are capable of detecting additonal types of bacteria, these detections are shown in parentheses]

Crude oil

release site

Sampling 

location

Type of 

sample

Sampling 

date

Slime-forming

bacteria

BART

Iron-related bacteria 

BART

Sulfate-reducing bacteria

BART

Denitrifying bac

BART

NA 3 Water 07/31/2002 Positive for SFB Negative for IRB Negative for SRB Positive for DNF 

(Heterotrophic bacteria) (Possibly anaerobic bacteria) (Anaerobic bacteria)

NA 7 Water 07/31/2002 Positive for SFB Positive for IRB Positive for SRB Positive for DNF 

(Heterotrophic bacteria) Dense slime bacterial and (Enteric bacteria) SRB consortium(Possibly anaerobic bacteria) (Possibly anaerobic bacteria)

NA 15 Water 07/30/2002 Positive for SFB Negative for IRB Negative for SRB Negative for DNF 

(Heterotrophic bacteria) (Possibly anaerobic bacteria) (Possibly anaerobic bacteria)

NA 16 Water 07/30/2002 Positive for SFB Negative for IRB Negative for SRB Negative for DNF 

(Heterotrophic bacteria) (Possibly anaerobic bacteria) (Possibly anaerobic bacteria)(Possibly Pseudomonadsand enteric bacteria)

NA 18 Water 07/30/2002 Positive for SFB Positive for IRB Negative for SRB Negative for DNF 

(Heterotrophic bacteria) (Possibly anaerobic bacteria) (Enteric bacteria)(Possibly anaerobic bacteria) 

1 21 Water 12/03/2002 Positive for SFB Negative for IRB Negative for SRB Positive for DNF 

(Pseudomonads and enteric bacteria)

2 23 Water 09/05/2002 Positive for SFB Negative for IRB Negative for SRB Negative for DNF 

(Anaerobic bacteria) 

2 24 Water 12/03/2002 Positive for SFB Negative for IRB Negative for SRB Negative for DNF 

(Fluorescing Pseudomonads) 
Crude oil

release site

Sampling 

location

Type of 

sample

Sampling 

date

Slime-forming

bacteria

BART

Iron-related bacteria 

BART

Sulfate-reducing Bacteria

BART

Denitrifying bac

BART

1 25 Soil 09/05/2002 Positive for SFB Slightly positive for IRB Negative for SRB Negative for DNF 1 28 Soil 09/05/2002 Positive for SFB Positive for IRB Positive for SRB Negative for DNF 

(Pseudomonads and (Anaerobic bacteria) Complex bacterial consortium enteric bacteria)

1 28 D Soil 09/05/2002 Positive for SFB Positive for IRB Positive for SRB Negative for DNF 

(Pseudomonads and (Anaerobic bacteria) Complex bacterial consortium enteric bacteria)

1 34 Soil 09/05/2002 Positive for SFB Positive for IRB Positive for SRB Positive for DNF 

(Pseudomonads and (Anaerobic bacteria) Dense slime bacterial and enteric bacteria) SRB consortium

(Anaerobic bacteria) 

2 38 Soil 12/03/2002 Positive for SFB Negative for IRB Positive for SRB Positive for DNF 

(Pseudomonads and Dense slime bacterial and enteric bacteria) SRB consortium

2 46 Soil 12/03/2002 Negative for SFB Negative for IRB Negative for SRB Negative for DNF 3 50 Water 12/10/2002 Positive for SFB Negative for IRB Positive for SRB Negative for DNF 

(Pseudomonads and (Anaerobic bacteria) Complex bacterial consortium enteric bacteria) (Enteric bacteria)

3 50 Soil 12/10/2002 Positive for SFB Negative for IRB Positive for SRB Positive for DNF 

(Pseudomonads and Dense slime bacterial and enteric bacteria) SRB consortium

NA Control PBS 09/05/2002 Negative for SFB Negative for IRB Negative for SRB Negative for DNF NA Control PBS 12/10/2002 Negative for SFB Negative for IRB Negative for SRB Negative for DNF 

Table 5. Summary of results from biological activity reaction tests (BARTs), July 2002 - December 2002.—Continued[NA, not applicable; D, duplicate sample; SFB, slime-forming bacteria; IRB, iron-related bacteria; SRB, sulfate-reducing bacteria; DNF, denitrifying bacteria; HB, heterotrophic phosphate buffer solution; some BARTs are capable of detecting additonal types of bacteria, these detections are shown in parentheses]
the total concentration of the VOCs detected, not the total 

concentrations of all VOCs that may have been present in the 

sample. Short, 8-minute GC scans were used to screen only 

those VOCs with retention times similar to those for BTEX 

compounds. This may be one reason that the soil gas concentrations detected during this investigation were much lower 

than concentrations detected during the 1999 study by Otton 

and Zielinski (2000), when a sample collected near sampling 

location 28 (fig. 4) had 50 mg/L of VOCs, and a sample collected near sampling location 29 (fig. 4) had 4 mg/L of VOCs. 

Soil samples were collected from various depths at 

sampling locations 25, 26, 28, 30, 34, and 36 at site 1 in 

September 2002 (fig. 4, table 7). Samples were collected from 

several depths (approximately 0.2, 0.5, 0.7, and 0.9 m below 

land surface) at sampling location 25, which is between the 

new tank battery and the pumping unit, and topographically 

upgradient from the remediated area (fig. 4). Using field 

screening methods, benzene (2.3 μg/kg) was tentatively identified in a soil sample collected from 0.9 m below land surface 

at sampling location 25 (table 7). Benzene also was tentatively 

detected in soil samples collected from sampling 

location 26 (7.7 μg/kg) and from sampling location 28 (1.2 and 3.4 μg/kg) both of which are in 

the remediated area. Benzene was not detected 

in duplicate samples analyzed by the laboratory 

(table 7). Laboratory detection limits for benzene 

ranged from 5.3 to 14 μg/kg (variations in detection limits for the same compound were caused 

by differences in amounts of soil analyzed). 

Based on the laboratory results, the compound 

tentatively identified as benzene was likely some 

other VOC with a retention time similar to that 

of benzene. Additional BTEX compounds were 

detected by the field screening methods in soil 

samples from sampling location 25; however, an 

estimated concentration (less than the reporting 

limit) of 1.0 μg/kg of toluene was detected by 

STL in a duplicate collected from 0.5 m below 

land surface (table 7). Toluene probably was not 

detected in soil samples analyzed using the field 

screening methods because the detection limit for 

toluene ranged from 1.69 to 2.87 μg/kg for soil 

samples from sampling location 25. 

Toluene and other BTEX compounds (at 

concentrations of about 45 to about 200 μg/kg) 

were tentatively identified in soil samples collected from sampling location 26 (table 7). 

Toluene and other BTEX compounds were 

not detected by STL in a duplicate soil sample 

from sampling location 26 (table 7); therefore, 

the compounds tentatively identified as BTEX 

compounds were probably other VOCs with GC 

retention times similar to the BTEX compounds. 

The highest estimated total concentration of 

VOCs detected at site 1 (760 μg/kg) was for a 

soil sample collected from sampling location 26 

(table 7). BTEX compounds were not detected 

by field screening or laboratory methods in soil samples collected from other sampling locations (30, 34, and 36) at site 1 

(table 7). 

Elevated DRO concentrations [greater than soil cleanup 

levels established by TDEC (1998) for EPH] were detected 

in soil samples from site 1. DRO concentrations of about 

2,400 mg/kg were detected in soil samples from sampling 

location 26 by using the field screening methods and by STL 

(table 7). Elevated DRO concentrations (930 to 1,500 mg/kg) 

also were detected at location 28 (table 7), the other sampling 

location in the formerly remediated area (fig. 4). All soil 

samples collected outside of the remediated area contained 

DRO concentrations less than 100 mg/kg (table 7). 

Microbiological tests indicated that petroleum-­degrading 

bacteria were present in soil samples at site 1. A wide variety of bacteria often associated with the biodegradation of 

petroleum hydrocarbons were detected in soil samples from 

sampling locations 25, 28, and 34 (table 5) by using BARTs. 

Slime-forming (Pseudomonads and enteric), denitrifying, and 

Table 6. Volatile organic compound data for soil gas samples, September and 

December 2002.

[VOCs, volatile organic compounds; μg/L; micrograms per liter]

Crude 

oil 

release 

site

Sampling 

location

Sampling 

date

Number 

of VOCs 

detected

Total peak 

area for all 

VOCs detected

Estimated total 

concentration of 

VOCs detected 

(μg/L)

1 25 09/04/2002 14 19,230,000 2.1

1 26 09/04/2002 16 932,700,000 40

1 26 (duplicate) 09/04/2002 14 874,100,000 36

1 27 09/04/2002 12 7,915,000 1.0

1 28 09/04/2002 12 18,230,000 1.6

1 29 09/04/2002 14 32,420,000 2.2

1 30 09/04/2002 9 25,950,000 2.2

1 30 (duplicate) 09/04/2002 11 39,620,000 2.7

1 31 09/04/2002 14 28,770,000 2.3

1 32 09/04/2002 11 37,840,000 2.3

1 33 09/04/2002 12 18,990,000 1.5

1 34 09/04/2002 10 34,700,000 2.6

1 35 09/04/2002 8 19,820,000 1.4

1 36 09/04/2002 9 21,730,000 1.8

1 37 09/04/2002 7 10,460,000 1.0

2 38 09/04/2002 16 58,470,000 4.9

2 38 12/03/2002 5 208,200 0.10

2 39 12/03/2002 15 4,117,000 0.84

2 40 12/03/2002 4 12,230 <0.10

2 41 12/03/2002 2 42,490 <0.10

2 42 12/03/2002 2 24,010 <0.10

2 43 12/03/2002 2 89,520 <0.10

2 44 12/03/2002 1 8,674 <0.10

2 45 12/03/2002 2 27,570 <0.10

2 46 12/03/2002 3 1,698,000 0.25

2 47 12/03/2002 3 36,880 <0.10

2 48 12/03/2002 2 11,390 <0.10

Ground-Water Quality and Potential Natural Attenuation 21
Table 7. Volatile and diesel range organic compound data for soil samples, September 2002 - February 2003.

[LS, land surface; mg/kg, milligrams per kilogram; --, no data; <, less than; J, estimated concentration less than the reporting limit; VOCs can only be tentatively 

identified by the field analytical techniques used during this study. Compounds identified by field analysis as BTEX compounds may actually be other VOCs 

with similar retention times]

Sampling

location

Sampling

date

Sampling 

depth 

(meters

below LS)

Type of 

analysis

Moisture

in sample

(percent)

Volatile organic compound results (micrograms per kilogram) Diesel

range

organics

(mg/kg)

Benzene Toluene

Ethylbenzene,

m-xylene, and

p-xylene, total

o-Xylene

Estimated total

for all VOCs

detected

Crude oil release site 1

25 09/05/2002 0.2 Field -- <0.88 <1.8 <7.0 <7.0 36 26

09/05/2002 0.5 Field -- <0.87 <1.8 <7.0 <7.0 130 2.6

09/05/2002 0.5 Laboratory 12.0 <5.7 1.0 J <5.7 <2.8 110 <4.5

09/05/2002 0.7 Field -- <0.85 <1.7 <6.9 <6.8 22 0.50

09/05/2002 0.9 Field -- 2.3 <1.8 <7.2 <7.2 -- --

09/05/2002 0.9 Field -- <1.4 <2.9 <11 <11 290 0.50

26 09/05/2002 0.6 Field -- 7.7 45 220 <7.6 530 2,500

09/05/2002 0.6 Laboratory 13.0 <5.7 <5.7 <2.9 <2.9 760 2,400

28 09/05/2002 0.5 Field -- 1.2 <1.4 <5.5 <5.5 35 930

09/05/2002 0.5 Field -- 3.4 <1.4 <6.4 <6.4 52 1,500

30 09/05/2002 0.5 Field -- <0.98 <2.0 <7.8 <7.8 94 8.7

09/05/2002 0.5 Laboratory 6.0 <5.3 <5.3 <2.7 <2.7 76 11

34 09/05/2002 0.2 Field -- <1.3 <2.7 <10.6 <10.6 140 4.8

09/05/2002 0.2 Laboratory 10.0 <14 <14 <6.8 <6.8 110 <4.5

36 09/05/2002 0.5 Field -- <0.85 <1.4 <6.8 <6.8 110 3.2

Crude oil release site 2

38 12/04/2002 0.6 Field -- 2,500 400 150 45 16,000 3,000

02/19/2003 0.6 Field -- 36 22 <26 <26 250 --

02/19/2003 0.6 Laboratory 15.0 <5.9 <5.9 <5.9 <3.0 840 --

39 12/04/2002 0.6 Field -- 130 <13 <2.7 <26 1,700 4,200

43 12/04/2002 0.6 Field -- 1.5 1.5 <2.7 <2.7 37 12

44 12/04/2002 0.2 Field -- 0.86 4.7 <2.4 <2.4 7.5 20

46 12/04/2002 0.5 Field -- <0.71 2.2 <2.5 <2.9 2.7 <0.20

48 12/04/2002 0.5 Field -- 1.4 <1.5 <2.6 <2.9 4.6 <0.20

49 02/19/2003 0.6 Field -- <0.64 <1.3 <2.8 <2.6 <2.8 --

Crude oil release site 3

50 02/19/2003 0.5 Field -- 2.1 3.0 <3.2 <3.2 5.1 --

02/19/2003 0.5 Laboratory 27.0 2.1J 2.6J <3.4 <3.4 830 --

12/09/2002 0.6 Field -- 4.9 4.5 4.3 <2.1 11 58

12/09/2002 1.2 Field -- 7.9 5.1 5.0 <2.0 32 130

22 Fate and Transport of Petroleum Hydrocarbons...Big South Fork National River and Recreation Area
heterotrophic bacteria also were detected in water samples 

collected from the spring at sampling location 21 in December 

2002 (table 5).

Viable bacteria colonies were detected in membrane 

filtration plates containing petroleum (diesel or crude 

oil), growth media, and environmental samples (water 

or soil extraction solutions). Counts of 3,600, 3,800, and 

1,800 col/100 mL (colonies per 100 milliliters of sample) for 

total heterotrophic, crude oil-degrading, and diesel-degrading 

bacteria, respectively, were detected in the water sample from 

the spring at location 21. These results indicate that bacteria 

detected in water and soil samples at the study sites were able 

to use petroleum hydrocarbons (from crude oil or diesel) as 

their primary growth substrate.

Bacteria were not present on control plates containing 

petroleum, growth media, and sterile water, verifying that the 

procedure used to sterilize the petroleum samples was successful. Bacteria also were not present on control plates containing 

only growth media and environmental samples, verifying that 

possible impurities in the growth media were not being used 

as a primary growth substrate. 

The elevated DRO concentrations detected in soil 

samples at sampling locations 26 and 28 and the presence of 

unidentified VOCs in soil gas (sampling location 26) and soil 

samples (sampling locations 25, 26, 34, and 36) indicate that 

biodegradation of petroleum hydrocarbons at study site 1 is 

incomplete. The detection of toluene in one of the soil samples 

indicates that BTEX compounds may be present at low 

concentrations at the site. Only a few ground-water samples 

(from one small spring) could be collected; however, BTEX 

and other soluble petroleum hydrocarbons do not appear to be 

leaching into shallow ground water at site 1. 

Crude Oil Release Site 2

Water, soil gas, and sediment samples were collected to 

evaluate potential contamination and biodegradation at site 2. 

Two small springs are located at site 2. The spring at sampling 

location 24 (fig. 4) was dry on September 3, 2002, but was 

sampled during December 2002 and February 2003 (table 3). 

The spring at sampling location 23 was sampled during September and December 2002. Concentrations of constituents 

used to characterize ground-water geochemistry were all low 

or below detection limits (table 4). BTEX compounds were 

not detected in any of the water samples collected from the 

two springs (table 3), and DRO concentrations were less than 

2 mg/L in all of the water samples (table 4).

Soil gas samples were collected from 11 sampling locations at site 2 (fig. 4, table 6). During December 2002, the 

greatest number of VOCs (15) and the highest estimated total 

VOC concentrations (0.84 μg/L) were detected in a soil gas 

sample from sampling location 39 (table 6). This location is 

near the south side of the former spoil pit that was remediated 

in 1993 and 1994 (fig. 4). Sampling location 46, near the confluence of the small stream south of the remediated area and 

Bear Branch (fig. 4), contained the second highest estimated 

total VOC concentration (0.25 μg/L). The remainder of the 

soil gas samples collected at the site contained estimated VOC 

concentrations of 0.10 μg/L or less. VOC concentrations in the 

soil gas sample collected from sampling location 38 in September 2002 were substantially higher than in December 2002. 

The estimated total VOC concentration was 4.9 μg/L with 16 

compounds detected in the September 2002 soil gas sample 

from location 38. Only five VOCs (estimated total of 0.10 

μg/L) were detected in the December 2002 soil gas sample 

Sampling

location

Sampling

date

Sampling 

depth 

(meters

below LS)

Type of 

analysis

Moisture

in sample

(percent)

Volatile organic compound results (micrograms per kilogram) Diesel

range

organics

(mg/kg)

Benzene Toluene

Ethylbenzene,

m-xylene, and

p-xylene, total

o-Xylene

Estimated total

for all VOCs

detected

Crude oil release site 3—Continued

51 12/09/2002 0.8 Field -- <0.58 <1.2 <2.3 <2.3 2.1 0.90

52 12/09/2002 0.9 Field -- 8.7 2.4 <2.7 <2.7 37 53

53 12/09/2002 0.8 Field -- <0.68 <1.4 <2.7 <2.7 1.3 1.4

54 12/09/2002 0.2 Field -- <0.41 <0.81 <1.6 <1.6 1.6 3,400

12/09/2002 0.6 Field -- <0.60 3.9 <2.4 <2.4 44 32

55 12/09/2002 0.6 Field -- <0.49 6.6 <2.0 <2.0 170 <0.20

56 02/19/2003 0.6 Field -- <0.64 <1.3 <2.6 <2.6 0.93 --

Table 7. Volatile and diesel range organic compound data for soil samples, September 2002 - February 2003.—Continued

[LS, land surface; mg/kg, milligrams per kilogram; --, no data; <, less than; J, estimated concentration less than the reporting limit; VOCs can only be tentatively identified by the field analytical techniques used during this study. Compounds identified by field analysis as BTEX compounds may actually be other 

VOCs with similar retention times]

Ground-Water Quality and Potential Natural Attenuation 23
(table 6). None of the soil gas samples collected in December 

2002 at site 2 contained VOC concentrations as high as those 

in the soil gas sample collected from sampling location 38 

in September 2002; VOC concentrations in the September 

2002 sample from sampling location 38 were similar to those 

detected at site 1. 

Soil samples were collected from sampling locations 38, 

39, 43, 44, 46, 48, and 49 during December 2002 and February 2003 (table 7). VOCs, tentatively identified as BTEX 

compounds based on GC retention times, were detected in soil 

samples collected from sampling locations 38, 39, 43, 44, 46, 

and 48 during December 2002 (table 7). The greatest VOC 

concentration (estimated total of 16,000 μg/kg) was detected 

in a soil sample from sampling location 38 (table 7). During 

February 2003, additional soil samples were collected from 

sampling location 38 and were analyzed using field screening 

methods and by STL. These subsequent concentrations were 

lower than in December 2002, and STL did not detect BTEX 

compounds in the soil sample from sampling location 38, indicating that the VOCs detected by the field screening methods 

were not BTEX compounds. 

An elevated DRO concentration of about 4,200 mg/kg 

was detected in a soil sample collected from 0.6 m below land 

surface at sampling location 39 using field screening methods 

(table 7). An elevated DRO concentration (3,000 mg/kg) also 

was detected in soil collected from 0.6 m below land surface 

at sampling location 38, near the center of the remediated area 

(table 7, fig. 4). DRO concentrations were less than 100 mg/kg 

(table 7) in all soil samples collected from locations downgradient of the former spoil pit/remediated area including 

locations 43 and 44 (fig. 4). Locations 43 and 44 are along the 

stream bank just downstream of the small erosional channel 

that Otton and Zielinski (2000) documented as being a possible path for the transport of hydrocarbons from the former 

spoil pit.

A wide variety of bacteria often associated with the 

biodegradation of petroleum hydrocarbons was detected in soil 

samples collected from sampling location 38. Slime-­forming 

bacteria were detected in both of the springs (sampling locations 23 and 24) at site 2 and fluorescing Pseudomonads also 

were detected in the spring at sampling location 24 (table 5). 

Crude oil-degrading and diesel-degrading bacteria were 

detected in water samples collected from the spring at sampling location 24 on December 3, 2002. Using the membrane 

filtration plate counts, 4,900, 450, and 4,300 colony forming 

units (cfu)/100 mL of total heterotrophic, crude oil-degrading, 

and diesel-degrading bacteria, respectively, were detected in 

a water sample from the spring. Soil samples from sampling 

location 49, a background location at site 1, contained 77 

diesel- and 110 crude oil-degrading bacteria per gram of wet 

soil. Soil samples from sampling location 38, one of the more 

contaminated locations at sites 1 and 2, contained 28 dieseland 67 crude oil-degrading bacteria per gram of wet soil. 

The elevated DRO concentrations detected in soil 

samples, the presence of unidentified VOCs in soil samples, 

and the low numbers of petroleum-degrading bacteria in 

contaminated soils indicate that biodegradation of petroleum 

hydrocarbons at study site 2 is incomplete. Only six groundwater samples (from two small springs) could be collected; 

however, BTEX and other soluble petroleum hydrocarbons do 

not appear to be leaching into shallow ground water at site 2. 

Crude Oil Release Site 3

Site 3 represents conditions that exist where a site has not 

been actively remediated for hydrocarbon contamination. This 

site is the only site where water is produced from the oil well. 

Water and soil samples were collected at site 3 during December 2002 and February 2003 (table 3). Total monthly precipitation for December 2002 and February 2003 was above normal 

(National Oceanic and Atmospheric Administration, 2002 and 

2003). Soil gas samples were not collected because of the high 

water table and wet conditions encountered at the site.

Water samples were collected from three auger holes and 

one spring at the site. Auger holes were drilled using hand 

augers to obtain soil samples; water was encountered and 

the auger holes were extended about 0.5 m below the water 

surface. Water was encountered at about 1.5 m below land surface at sampling location 50, about 1.2 m below land surface 

at sampling location 51, and about 0.6 m below land surface 

at sampling location 55. About three volumes of water were 

purged from the auger holes, and water samples were collected 

using bailers. Water samples collected from sampling locations 50, 51, and 55 had the highest specific conductance of 

any of the water samples collected at all three sites (table 3), 

and the highest concentrations of dissolved iron, sulfate, and 

chloride were detected in water samples from the auger holes 

at site 3 (table 4). The elevated specific conductance and 

chloride concentrations at site 3 are likely the result of releases 

of brine from the wells and tanks. BTEX compounds were not 

detected in any water samples collected from site 3. A spring 

(sampling location 57, fig. 5), about 5 m northeast of sampling 

location 50, was dry during the sampling in December 2002. 

The spring was flowing, and a water sample was collected in 

February 2003. BTEX compounds were not detected in the 

water sample from the spring.

Soil samples were collected from sampling locations 50 

through 55 in December 2002 (table 7). BTEX compounds 

(benzene and toluene) tentatively were identified at concentrations ranging up to 8.7 μg/kg in soil samples analyzed using 

field screening methods (table 7). During February 2003, 

additional soil samples were collected from sampling location 50, and one sample was sent to STL to determine if the 

detected VOCs actually were BTEX compounds. Benzene 

and toluene were detected in the soil sample analyzed by STL 

(table 7), indicating that the VOCs detected in the soil sample 

from sampling location 50, and most likely the VOCs detected 

in other soil samples, were BTEX compounds. 

DRO concentrations detected in soil samples from site 3 

ranged from <0.2 to about 3,400 mg/kg (table 7). Weathered 

crude oil was observed at the water surface in the auger hole 

24  Fate and Transport of Petroleum Hydrocarbons...Big South Fork National River and Recreation Area
at sampling location 50. DRO concentrations in water samples 

from locations downgradient of sampling location 50 (sampling locations 51 and 55) were less than 0.10 mg/L (table 4). 

Bacteria often associated with the biodegradation of 

petroleum hydrocarbons were detected in soil and water 

samples collected from sampling location 50 (table 5). Crude 

oil-degrading and diesel-degrading bacteria were detected in 

soil samples collected from sampling location 50 (one of the 

more contaminated locations at site 3) on December 10, 2002. 

Using the membrane filtration plate counts, 18,000, 160, and 

78 cfu per gram of wet soil of total heterotrophic, crude oildegrading, and diesel-degrading bacteria, respectively, were 

detected in soil samples collected from sampling location 50. 

These bacteria counts were lower than counts for soil samples 

from a background location at site 3 (sampling location 56). 

Total heterotrophic, crude oil-degrading, and diesel-degrading 

bacteria counts of 140,000, 220, and 970 cfu per gram of wet 

soil, respectively, were detected in soil samples from sampling 

location 56. 

The elevated DRO concentrations detected in soil samples, the presence of BTEX compounds in soil samples, and 

the low numbers of petroleum-degrading bacteria in contaminated soils indicate that biodegradation of petroleum hydrocarbons at study site 3 is incomplete. The detection of weathered 

crude oil at sampling location 50 indicates that crude oil has 

percolated down through the soil to shallow ground water 

(only a few meters below land surface) at the site. The crude 

oil does not appear to have migrated horizontally in ground 

water based on the low DRO concentrations in water samples 

collected downgradient of sampling location 50. 

BTEX compounds were not detected in ground-water 

samples; however, benzene may have leached into ground 

water and may have migrated downgradient from the site in 

the past. The concentration of benzene and other soluble petroleum hydrocarbons present in the ground water would depend 

on the concentration of these hydrocarbons in the crude oil 

at the site. High chloride concentrations (table 4) detected in 

water samples from sampling location 51 indicate that brine 

likely has migrated downgradient from the well, tanks, and pit.

DRO data for soil samples collected from sampling location 54 may indicate surface transport of petroleum hydrocarbons away from this site. The highest DRO concentration 

(3,400 mg/kg) was detected in a shallow (0.2-m-deep) 

soil sample collected from sampling location 54. Location 54 is near the stream where visible evidence indicates that crude oil and water have overflowed the large 

pit at site 3. The DRO concentration in a sample from 

0.6 m below land surface at sampling location 54 was 

less than the concentration in the shallow sample (table 

7). Based on these data, petroleum hydrocarbons sorbed 

to sediment may be reaching the stream by overland 

transport. The elevated DRO concentrations at the other 

two sites and the erosional channel at site 2 indicate that 

the potential exists for overland transport of petroleum 

hydrocarbons from other crude oil-contaminated sites in 

the study area. Petroleum hydrocarbons such as PAHs, 

if present in suspended or bed sediments, could possibly affect 

aquatic communities downstream of contaminated sites. 

Crude Oil Dissolution Study

Dissolution of BTEX compounds from crude oil was 

detected during the crude oil dissolution study. BTEX compounds were detected in water samples removed from all three 

of the 1-L glass bottles containing VBW and crude oil from 

site 1. Water from replicates 1 and 2, which were stirred for 

4 days, contained slightly greater concentrations of BTEX 

than water from replicate 3, which was stirred for 10 days 

(table 8). The lack of increase in dissolved BTEX concentrations from day 4 to day 10 indicates that the BTEX dissolved 

in water was in equilibrium with BTEX in the crude oil. Using 

the average of the three replicates, the maximum dissolved 

concentrations (effective solubility) of BTEX compounds in 

water exposed to crude oil from site 1 ranged from 220 μg/L 

for ethylbenzene to 1,900 μg/L for benzene (table 8). 

The effective solubility values for BTEX compounds 

from the crude oil sample were used to determine if contact 

with crude oil in the study area might cause BTEX concentrations in ground water to exceed drinking water MCLs. The 

effective solubility for benzene (1,900 μg/L) was substantially less than maximum effective solubility for benzene 

(27,000 μg/L) reported by O’Reilly and others (2001); however, the effective solubility was substantially above the MCL 

of 5 μg/L for benzene in drinking water (table 8). The effective 

solubility of toluene (1,800 μg/L) also was above the MCL of 

1,000 μg/L for toluene in drinking water (table 8). The effective solubility of ethylbenzene (220 μg/L) and total xylenes 

(580 μg/L) were less than MCLs for drinking water (table 8). 

Results from the crude oil hydrocarbon dissolution study 

indicate that benzene and toluene concentrations greater than 

drinking water MCLs may be present in ground water that 

comes into contact with fresh (unweathered) crude oil from 

the study area. Releases of crude oil or natural gas condensate 

at sites in stream valleys may have the greatest potential for 

benzene and toluene contamination of ground water because 

of the shallow depths to ground water commonly found at 

these sites. 

Table 8. Results from the crude oil hydrocarbon dissolution study.

[μg/L, micrograms per liter; MCL, drinking water maximum contaminant level; effective 

solubility was calculated using averages from the three replicates; water/crude oil solutions were stirred for 4 days in replicates 1 and 2 and for 10 days in replicate 3] 

Name

Dissolved concentration in water 

samples (μg/L) 

Effective 

solubility 

(μg/L)

MCL 

(μg/L) Replicate 1 Replicate 2 Replicate 3

Benzene 1,900 2,000 1,700 1,900 5

Toluene 1,900 1,900 1,600 1,800 1,000

Ethylbenzene 250 250 170 220 700

m- and p-Xylene 300 300 180 260 --

o-Xylene 370 370 230 320 --

Total xylenes -- -- -- 580 10,000

Ground-Water Quality and Potential Natural Attenuation 25
Summary

Approximately 300 active or abandoned oil and gas wells 

are located in BISO, and more than 3,000 oil and gas wells are 

present in the Big South Fork watershed. In 2002 and 2003, 

the USGS investigated the effects of oil and gas production 

operations on ground-water quality at BISO with particular 

emphasis on the fate and transport of petroleum hydrocarbons 

in soils and ground water. Three stages of monitoring and 

research activities were performed during the investigation. 

The first stage consisted of a reconnaissance of the general 

ground-water-quality conditions in BISO. The second stage 

included more detailed characterization of ground-waterquality conditions at a few of the reconnaissance sampling 

locations. The third stage of the investigation included 

additional sampling at three crude oil release sites in and near 

BISO to evaluate the fate and transport of petroleum hydrocarbons. 

When petroleum compounds such as crude oil are 

released into the environment, the compounds undergo physical, chemical, and biological changes. The degree to which 

the various types of petroleum hydrocarbons degrade depends 

on the physical and chemical properties of the hydrocarbons. 

Monoaromatics, such as BTEX, are some of the most common 

aromatic compounds in petroleum. BTEX compounds are the 

most soluble aromatic compounds and have the lowest Koc of 

the most common aromatic hydrocarbons. Because of the high 

degree of toxicity and mobility of benzene (compared to other 

petroleum hydrocarbons), it is commonly the main groundwater contaminant of concern at petroleum release sites. Benzene concentrations may be of concern (greater than MCL) at 

gas condensate spill sites or sites where crude oil containing 

more than 0.03 percent benzene (by weight) has been released. 

During the ground-water-quality reconnaissance, samples 

were collected from springs, wells, and a few surface-water 

locations in various parts of BISO. Water samples collected 

during the reconnaissance were analyzed for physical properties (temperature, DO, pH, and specific conductance), VOCs, 

and selected types of bacteria. During the second stage of the 

investigation, additional water samples were collected and 

analyzed for physical properties, geochemical conditions, 

VOCs, DRO, and selected types of bacteria. During the third 

stage of the investigation, soil gas, soil, water, and crude oil 

samples were collected to evaluate the fate and transport of 

petroleum hydrocarbons at three crude oil release sites. Soil 

gas samples were analyzed for VOCs. Soil samples were analyzed for VOCs, DRO, and selected types of bacteria. Water 

samples were analyzed for physical properties, geochemical 

indicators, VOCs, DRO, and selected types of bacteria. A 

crude oil sample collected from an active oil production well 

at one of the release sites was used during a laboratory study 

examining the dissolution of petroleum hydrocarbons from the 

oil into water.

BTEX compounds were not detected in water samples 

in either the reconnaissance stage or the second stage of the 

investigation. During the reconnaissance, water samples were 

collected from 24 sampling locations (17 springs, 5 watersupply wells, 1 small stream, and 1 spring-fed pond) in or 

near BISO. BTEX compounds were not detected in any of 

the samples collected during the reconnaissance, indicating 

that contamination of ground water by dissolved petroleum 

hydrocarbons is not widespread in BISO. During the second 

stage of the investigation, additional water samples were collected from three springs and two wells sampled during the 

reconnaissance. BTEX and DRO were not detected in any of 

the water samples collected during the second stage of the 

investigation. 

Elevated DRO concentrations (as great as 2,400 mg/kg) 

detected in soil samples and the presence of unidentified 

VOCs in soil gas and soil samples indicate that biodegradation 

of petroleum hydrocarbons at site 1 is incomplete. The detection of toluene (1.0 μg/kg) in a lab-analyzed soil sample indicates that BTEX compounds may be present at low concentrations at the site. Only a few ground-water samples (from one 

small spring) could be collected; however, BTEX and other 

soluble petroleum hydrocarbons do not appear to be leaching 

into ground water at site 1.

DRO concentrations (as great as 4,200 mg/kg) detected 

in soil samples, the presence of unidentified VOCs in soil 

samples, and the low petroleum-degrading bacteria counts 

found in contaminated soils indicate that biodegradation of 

petroleum hydrocarbons at site 2 is incomplete. Only a few 

ground-water samples (from two small springs) could be collected; however, BTEX and other soluble petroleum hydrocarbons do not appear to be leaching into ground water at site 2. 

Elevated DRO concentrations (as great as 3,400 mg/kg) 

detected in soil samples, the presence of BTEX compounds in 

soil samples, and the low petroleum-degrading bacteria counts 

found in contaminated soils indicate that biodegradation of 

petroleum hydrocarbons at site 3 is incomplete. Collection 

of soil and ground-water samples indicate that crude oil has 

percolated down through the soil to shallow ground water only 

a few meters below land surface at site 3. 

The crude oil does not appear to have migrated horizontally in ground water based on the low DRO concentrations 

detected in water samples from downgradient locations at 

site 3. BTEX compounds were not detected in ground-water 

samples; however, benzene may have leached into ground 

water and may have migrated downgradient from site 3 in the 

past. The concentration of benzene and other soluble petroleum hydrocarbons present in the ground water would depend 

on the concentration of these hydrocarbons in the crude oil at 

the site. Elevated chloride concentrations detected in water 

samples collected from auger holes at site 3 indicate that brine 

likely has migrated downgradient from the well, tanks, and 

pits. 

The elevated DRO concentrations in shallow soil samples 

at all three sites, the erosional channel at site 2, and visible 

evidence of overflow of oil and water from the pit at site 3 

indicate the potential for overland transport of petroleum 

hydrocarbons from crude oil-contaminated sites in the study 

26  Fate and Transport of Petroleum Hydrocarbons...Big South Fork National River and Recreation Area
area. Petroleum hydrocarbons such as PAHs, if present in 

suspended or bed sediments, could possibly affect aquatic 

communities downstream of contaminated sites.

During the crude oil hydrocarbon dissolution study, the 

effective solubility of benzene in water exposed to crude oil 

from site 1 was substantially above the MCL of 5 μg/L for 

benzene in drinking water. The effective solubility of toluene 

(1,800 μg/L) also was above the MCL of 1,000 μg/L for toluene in drinking water. The effective solubility of ethylbenzene 

(220 μg/L) and total xylenes (580 μg/L) were less than MCLs 

for drinking water. Results from the crude oil hydrocarbon dissolution study indicate that BTEX concentrations greater than 

drinking water MCLs may be present in ground water that 

comes into contact with fresh (unweathered) crude oil from 

the study area. Releases of crude oil or natural gas condensate 

at sites in stream valleys may have the greatest potential for 

benzene and toluene contamination of ground water because 

of the shallow depths to ground water commonly found at 

these sites.

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