U.S. Department of the Interior

U.S. Geological Survey

ARSENIC IN SOILS AND SEDIMENTS ADJACENT TO

BIRCH SWAMP BROOK IN THE VICINITY OF TEXAS ROAD

(DOWNSTREAM FROM THE IMPERIAL OIL COMPANY

SUPERFUND SITE), MONMOUTH COUNTY, NEW JERSEY

Water-Resources Investigations Report 00-4185

Prepared in cooperation with the

U.S. ENVIRONMENTAL PROTECTION AGENCY and the

NEW JERSEY DEPARTMENT OF ENVIRONMENTAL PROTECTION
ARSENIC IN SOILS AND SEDIMENTS ADJACENT TO

BIRCH SWAMP BROOK IN THE VICINITY OF TEXAS ROAD

(DOWNSTREAM FROM THE IMPERIAL OIL COMPANY

SUPERFUND SITE), MONMOUTH COUNTY, NEW JERSEY

By Julia L. Barringer, Thomas H. Barringer, Pierre J. Lacombe, and

Charles W. Holmes

U.S. GEOLOGICAL SURVEY

Water-Resources Investigations Report 00-4185

Prepared in cooperation with the

U.S. ENVIRONMENTAL PROTECTION AGENCY and the

NEW JERSEY DEPARTMENT OF ENVIRONMENTAL PROTECTION

West Trenton, New Jersey

2001
U.S. DEPARTMENT OF THE INTERIOR

GAIL A. NORTON, Secretary

U.S. GEOLOGICAL SURVEY

Charles G. Groat, Director

For additional information Copies of this report can be

write to: purchased from:

District Chief

U.S. Geological Survey U.S. Geological Survey

Mountain View Office Park Branch of Information Servi

810 Bear Tavern Road, Suite 206 Box 25286

West Trenton, NJ 08628 Denver, CO 80225-0286
iii

CONTENTS

P

Abstract........................................................................................................................................

Introduction..................................................................................................................................

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

Description of the study area ...........................................................................................

Geology and soils.................................................................................................

Land-use history...................................................................................................

Acknowledgments............................................................................................................

Study approach and methods .......................................................................................................

Quality-assurance program ..............................................................................................

Soil sampling ..................................................................................................................

Sample collection.................................................................................................

Sample analysis....................................................................................................

Ground-penetrating-radar survey.....................................................................................

Data collection .....................................................................................................

Data analysis ........................................................................................................

Age dating of humaquepts ...............................................................................................

Sample collection and analysis ............................................................................

Data analysis ........................................................................................................

Statistical analysis of humaquept chemical constituents .................................................

Data conditioning.................................................................................................

Model testing and validation................................................................................

Arsenic in soils and sediments adjacent to Birch Swamp Brook.................................................

Spatial distribution of arsenic and other constituents in soils and sediments..................

Stream sediments .................................................................................................

Geologic substrate and humaquept soils .............................................................

Former orchard soils ............................................................................................

Fill materials ........................................................................................................

Mechanisms affecting the spatial distribution of arsenic.................................................

Fluvial transport and deposition of sediments .....................................................

Deposition of the humaquepts .................................................................

Deposition of stream sediment.................................................................

Effects of floods on sediment deposition.................................................

Physical changes to the stream channel.......................................

Height of flood stage....................................................................

Effect of bank storage ..................................................................

Land application of arsenic..................................................................................

Pesticide use.............................................................................................

Fertilizer use.............................................................................................

Mechanisms for the redistribution of arsenic...................................................................

Natural and human-induced movement of soils and sediments...........................

Overland runoff....................................................................................................

Geochemical processes ........................................................................................
iv

CONTENTS--Continued

P

Reduction of iron, arsenic, and vanadium ...............................................

Effects of changes in pH..........................................................................

Methylation and production of arsenical gases........................................

Sources of arsenic in soils and sediments adjacent to Birch Swamp Brook....................

Imperial Oil Company Superfund site .................................................................

Pesticide use.........................................................................................................

Geologic and organic materials ...........................................................................

Evaluation of evidence related to possible arsenic sources .................................

Summary and conclusions ...........................................................................................................

References cited...........................................................................................................................

Glossary of terms .........................................................................................................................

Appendix 1. Equipment cleaning, sample preparation, sample documentation, and quality

assurance...............................................................................................................................

Appendix 2. Geochemical data and soil-sampling field sheets, Texas Road site and adjacent

watersheds, Monmouth and Middlesex Counties, New Jersey.............................................

Appendix 3. Ground-penetrating-radar survey explanation and results .....................................

Appendix 4. Lead-210 activity data............................................................................................

ILLUSTRATIONS

Figure 1. Map showing location of the Texas Road site and the Imperial Oil Company

Superfund site, Monmouth County, New Jersey...............................................

2. Map showing the Texas Road site and immediate vicinity, and approximate areas

of former orchard and former and existing farm fields.....................................

3. Map showing detail of Birch Swamp Brook at Texas Road, and arsenic

concentrations measured in stream sediments during 1996 by New Jersey

Department of Environmental Protection .........................................................

4. Aerial photograph of the study area in 1932...........................................................

5. Map showing location of soil-sampling sites at the Texas Road site......................

6. Map showing location of humaquept sampling sites and surface-water gaging

stations in watersheds in Middlesex and Monmouth Counties, New Jersey ....

7. Topographic map from 1914 showing wetland cranberry-bog area, Texas Road

site.....................................................................................................................

8. Map showing approximate location of transects used in ground-penetratingradar survey, Texas Road site............................................................................

9. Schematic diagram showing conceptual model of the geochemical process that

produces “excess” 210Pb in sediments..............................................................

10. Graph showing ideal distribution of 210Pb in a sedimentary section showing the

difference between “supported” and “unsupported” 210Pb...............................

11. Vertical section showing stratigraphy of stream sediments in pit T5P1, Texas Roa

site.....................................................................................................................
v

ILLUSTRATIONS--Continued

P

Figure 12. Statistical Analysis System printout showing canonical scores for chemical variab

from humaquept samples, Texas Road site, and other watersheds in Middlese

and Monmouth Counties, New Jersey ..............................................................

13. Boxplots showing concentration distributions of selected chemical

constituents in humaquept samples from other watersheds in Middlesex and

Monmouth Counties and from the Texas Road site..........................................

14. Graph showing lead-210 activity as a function of depth in a soil core from the

area of the buried stream channel, Texas Road site ..........................................

15. Graph showing lead-210 activity as a function of depth in a soil core from the

farm-field area of the Texas Road site ..............................................................

16. Sketch showing three cross sections depicting water levels and sediments at

Birch Swamp Brook near Texas Road prior to damming, during the period of

damming, and in 1998 ......................................................................................

17. Map showing location of buried channel identified during ground-penetratingradar survey at the Texas Road site...................................................................

18. Map showing arsenic concentrations at three depths within soil profiles on east

and west banks of Birch Swamp Brook near Texas Road ................................

19. Six oblique sections intersecting west and east banks and channel of Birch

Swamp Brook at the Texas Road site................................................................

20. Graphs showing relation of lead and copper concentrations to depth in

humaquept soil cores from the Texas Road site................................................

21. Graphs showing relation of arsenic, iron, and vanadium concentrations to

depth in humaquept soil cores from the Texas Road site..................................

TABLES

Table 1. Summary statistics for arsenic concentrations in soils and sediments, Middlesex an

Monmouth Counties, New Jersey........................................................................

2. Summary statistics for copper and lead concentrations in soils and sediments,

Middlesex and Monmouth Counties, New Jersey ...............................................

3. Estimated flows for flood recurrence intervals of 2, 5, 10, 25, 50, 100 and 500

years for Birch Swamp Brook, calculated by using the Transfer Method...........

4. Evaluation of evidence for each of six hypotheses regarding possible sources of

arsenic at the Texas Road site, Monmouth County, New Jersey .........................
vi

CONVERSION FACTORS, VERTICAL DATUM, AND WATER-QUALITY

ABBREVIATIONS

Multiply By To obtain

Length

inch (in.) 25.4 millimeter

inch 2.54 centimeter (cm)

foot (ft) 0.3048 meter

mile (mi) 1.609 kilometer

Area

acre 4,047 square meter

square mile (mi2) 2.590 square kilometer

Volume

gallon (gal) 3.785 liter

Flow

cubic foot per second (ft3/s) 0.02832 cubic meter per second

Mass

ounce, avoirdupois (oz) 28,349 milligram (mg)

ounce, avoirdupois 28.35 gram (g)

pound, avoirdupois (lb) 0.4536 kilogram (kg)

Temperature

degree Fahrenheit (°F) °C = 5/9 x (°F-32) degree Celsius (°C)

Sea level: In this report “sea level” refers to the National Geodetic Vertical Datum of 1929-- a

geodetic datum derived from a general adjustment of the first-order level nets of the United

States and Canada, formerly called Sea Level Datum of 1929.

Abbreviations:

ns - nanosecond (10-9 second)

MHz - megahertz

(unit of frequency equal to 106 hertz)

mg/kg - milligrams per kilogram

(equivalent to parts per million)

Al - aluminum

As - arsenic

Ba - barium

Ca - calcium

Cr - chromium

Cu - copper

Fe - iron

K - potassium

Mg - magnesium

Mn - manganese

Ni - nickel

Pb - lead

V - vanadium

Zn - zinc

TOC - total organic carbon
1

ARSENIC IN SOILS AND SEDIMENTS ADJACENT TO

BIRCH SWAMP BROOK IN THE VICINITY OF TEXAS ROAD

(DOWNSTREAM FROM THE IMPERIAL OIL COMPANY

SUPERFUND SITE), MONMOUTH COUNTY, NEW JERSEY

By Julia L. Barringer, Thomas H. Barringer, Pierre J. Lacombe, and Charles W. Holm

ABSTRACT

Concentrations of arsenic that exceed

the proposed New Jersey State Cleanup

Criterion for residential soils of 20 parts per

million (20 mg/kg (milligrams per kilogram))

have been measured in soil samples from two

residential and farm properties (referred to as

the “Texas Road site”) that abut Birch Swamp

Brook immediately south of Texas Road and

downstream from the Imperial Oil Company

Superfund site in Monmouth County, New

Jersey. Concentrations of arsenic that exceed

the proposed cleanup criterion also have been

measured in sediments along the banks and

point bars of Birch Swamp Brook and in the

organic soils through which the brook runs.

The brook drains areas of contamination about

0.5 miles upstream that are associated with the

Superfund site, where arsenical pesticide

production (1917-45) and waste-oil processing

(1950-69) took place. Prior to the current

study, the Imperial Oil Company Superfund

site was the only known major upstream

source of contaminants, which include arsenic,

petroleum, and polychlorinated biphenyls, but

past use of arsenical pesticides had been

shown to contribute substantial amounts of

arsenic to the soils in the area. The source of

the arsenic in the residential and farm soils was

unknown, however.

The soils adjacent to the stream are

organic-rich wetland soils, known as

humaquepts, with areas of recent sand and clay

fill, which overlie sands of the Englishtown

Formation. Samples of soils and sediments

were collected and analyzed for major catio

trace elements, and total organic carbon.

Results of the chemical analyses indicate th

arsenic concentrations are substantially larg

(4.7-139 mg/kg) in the humaquepts than in 

underlying sand of the Englishtown Format

(less than 0.64-7.6 mg/kg). Areas of sand a

silt along the stream bank and on point bars

contain elevated (greater than 20 mg/kg)

arsenic concentrations that range up to 2,57

mg/kg. Similar arsenic levels, typically acco

panied by petroleum and polychlorinated

biphenyl contamination, have been measure

in previous investigations.

Samples of humaquepts were collec

from other, nearby watersheds in the New

Jersey Coastal Plain and analyzed for arsen

metals, and total organic carbon. Arsenic

concentrations in these samples, which

represent local ambient conditions, ranged

from 4.9 to 43.1 mg/kg and include

background arsenic levels and various anthr

pogenic inputs. These concentrations are

similar to those measured in many of the

humaquept samples from the Texas Road si

but statistically significant differences in

calcium, barium, magnesium, and chromium

concentrations are indicative of different

chemical inputs to the other watersheds.

A ground-penetrating-radar survey o

the Texas Road site revealed the presence o

buried stream channel between the present-d

channel and the house nearest Texas Road.
2

Because the buried channel probably existed

before the beginning of the 20th century,

widespread arsenic contamination of the

humaquept soils did not result from floodwaters emanating from a channel located

elsewhere on the property. The rate of

deposition of the humaquepts, determined by

analysis of the samples for the isotope lead210, indicates that the humaquepts were

deposited over a period of at least 1,000 years;

therefore, arsenic measured at or near the

bottom of the humaquepts is unlikely to be

derived from the Superfund site wastes or from

pesticide applications unless it has leached

from the land surface. An increase in arsenic

and iron concentrations and a decrease in lead

and copper concentrations with depth in the

humaquepts at the Texas Road site indicate

probable redistribution of surficially deposited

arsenic by geochemical processes.

Anecdotal evidence for arsenical

pesticide use on the farm fields indicates that

some of the arsenic measured in soils at the

Texas Road site probably is attributable to

these pesticides. Given the small size of the

basin and little recent history of major flooding

along Birch Swamp Brook, arsenic from an

upstream source would have been deposited on

the fields only during major floods, such as

those during the hurricane of 1938. The

presence of elevated arsenic concentrations in

association with petroleum and polychlorinated biphenyl contamination along the stream

provides considerable evidence for streamsediment contamination that is derived from

the Superfund site, whereas the arsenic in the

humaquept soils is probably derived, in part,

from pesticide use, as well as from contaminated sediment originating at the Superfund

site that was deposited during an extreme

flood.

INTRODUCTION

Concentrations of arsenic that excee

the proposed New Jersey State Cleanup

Criterion of 20 parts per million (ppm), or 2

mg/kg, have been measured in soils and

sediments on residential and farm propertie

that abut Birch Swamp Brook immediately

south of Texas Road (fig. 1) in Monmouth

County, New Jersey. The properties are

downstream from the Imperial Oil Compan

Superfund site (fig. 1) and during the past 6

years have included areas of orchard and fa

fields (fig. 2). In samples of organic soils

(humaquepts) collected during 1994, arseni

concentrations ranged from 2.1 to 60.8 mg/

in the uppermost 6 in. of soil on two propert

east of the brook (hereafter referred to as th

“Texas Road site”). Arsenic concentrations 

sediments along the channel from 0 to 6 in.

deep generally were less than 60 mg/kg,

although 125 mg/kg was measured in point-

sediments near where the brook turns sharp

northwest to flow beneath Texas Road. At t

location, sediments from 12 to 18 in. deep

contained 9,460 mg/kg of arsenic (L. Rober

Kimball and Associates, Inc., 1995a); at oth

locations along the stream, sediments from 

12-to-18-in. interval tended to contain high

concentrations of arsenic than did the

shallower sediments at the same locations.

Recent sampling by the New Jersey

Department of Environmental Protection

(NJDEP) failed to confirm the arsenic conc

tration of more than 9,000 mg/kg, but conce

trations ranging from 11 to 488 mg/kg were

measured in sediment from the same genera

location, and 39 to 2,550 mg/kg and 25 to

1,040 mg/kg were measured in sediment at

two other locations along the stream channe

about 120 and 160 ft, respectively, to the w

(fig. 3) (Steven Byrnes, N.J. Department of

Environmental Protection, written commun

1997).
74 15' 74 14' 40

25'

Texas Road site

Imperial Oil Company

Superfund site

40

22'

30" Base from U.S. Geological Survey

South Amboy, 1:24,000, photorevised 1981

Keyport, 1:24,000, photorevised 1970

ookBr

Swamp

hcBir

0 .5 1 MILE

0 .5 1 KILOMETER

75 74

41

40

39

Area of detail

Study area

Newark

Middlesex Co.

Morganville

0 10 20 MILES

Monmouth Co. 0 10 20 KILOMETERS

Lakehurst

NEW

JERSEY

Marlboro Township

Figure 1. Location of the Texas Road site and the Imperial Oil Company Superfund site, 

Monmouth County, New Jersey.

3
0 200 300 FEET

0

Area of former or existing

farm field

Area of former orchard

Topographic contour

Edge of woods

Tree

Base from L. Robert Kimball and Associates, Inc., 1995b

EXPLANATION

Area of detail 

shown in figure 3

House

Chicken barns

100

Texas Road

Birch

Swamp 

Brook

50 METERS

Figure 2. Texas Road site, Monmouth County, New Jersey, and immediate vicinity, and approximate 

areas of former orchard and former and existing farm fields. (Modified from L. Robert Kimball and 

Associates, Inc., 1995b) 

4
100 FEET

30 METERS

50

15

0

0

3.1

3.8

5.6

4.0

7.5

8.7

4.6

4.9

5.6

1.1

3.9

4.2

7.9

8.4

9.7

1

3.5

6.8

3.3

24.3

4.1

8.9

7.9

6.3

4.3

6.8

8.2

9.1

10.1

6.8

1.21

4.6

9.7

8.0

13.3

39.9

5.8

10.1

6.2

8.9

14.9

25.9

10.2

14.8

13.4

20.7

31.8

88.8

47.3

22

8.6

14.2

15.0

38.4

9.0

22.1

21.9

13.4

19.3

33.8

14.4

16.6

30.4

12.2

24.2

20.8

9.1

52.1

2.3

8.3

26.0

17.0

15.1

5.3

17.1

3.7

15.1

7.7

5.4

9.6

37.0

8.0

4.1

16.0

16.3

31.1

21.9

6.8

8.5

10.5

2.7

220

26.2

12.7

7.1

10.1

49.9

26.7

25.5

95.1

41.3

6.1

2.3

15.6

28.4

13.3

67.5

1.1

8.5

8.2

1

40.3

9.4

58.6

149

488

532

82.1

210

15.4

64.6

285

8.8

16.0

17.1

60.7

1.1

6.7

8.2

7.3

18.5

181

3.8

17.4

18.7

19.1

447

42.8

1

14.9

10.4

32.3

20.9

40.8

190

514

38.8

40.6

40.6

10.1

4.7

2.6

2,550

45.8

21.6

23.2

5.9

ND

153

125

130

6.0

2.5

2.6

3.6

4.8

5.3

4.8

10.0

7.0

52.6

241

56.4

13.9

17.4

36.9

20.1

36.2

13.8

8.4

50.0

56.6

505

262

109

3.4

7.7

1,040

25.0

16.8

67.0

67.3

45.4

17.1

13.7

93.3

102

31.0

40.1

122

513

84.2

10.3

25.5

186

42.8

710

91.6

12.4

18.0

4.8

ND

ND

ND

ND

ND

7.6

9.7

8.0

Texas Road

Brook

p mawS

Topographic contour

h

Edge of woods

reeT

Approximate location of soil core--Numbers are arsenic concentration at 0-6, 12-18, and 24-30 inches, respectivelyNot detected

cri B

Associates, Inc., 1995b Base from L. Robert Kimball and 

36.9

241

56.4

TION EXPLANA

ND

, and arsenic concentrations measured in stream 

ation shown in fig. 2)

, New Jersey exas Road, Monmouth County Detail of Birch Swamp Brook at T Figure 3.

sediments during 1996 by New Jersey Department of Environmental Protection. (Loc

5
6

On the basis of previous soil and

sediment sampling, one possible source of the

elevated arsenic concentrations in the floodplain and streambed sediments south of Texas

Road was hypothesized by investigating

agencies to be waste materials from the

Imperial Oil Company Superfund site (IOC).

Arsenic-bearing wastes were believed to have

been generated during 1917-45, when

arsenical pesticides were produced by Brocker

Chemical Company (later Champion Chemical

Company) at the IOC location off Tennent

Road in Marlboro Township (E.C. Jordan Co.,

1992). Waste materials from these activities

and from later waste-oil-processing activities

appeared to have accumulated in a wetland

area of Birch Swamp Brook at the northern

part of the Superfund site and upstream from

the Texas Road site (fig. 1). The stream

sediments south of Texas Road also contain

areas of petroleum contamination, which may

be related to one or more oil spills at IOC, that

began to appear in Birch Swamp Brook in

about 1952, according to the present owner of

the Texas Road site properties. Some of the oil

was transported down the length of Birch

Swamp Brook and reached Lake Lefferts,

about 1.5 mi north of IOC (Steven Byrnes, oral

commun., 1997). Petroleum and polychlorinated biphenyls (PCBs) have recently been

measured in stream-channel and bank

sediments along the length of the stream (L.

Robert Kimball and Associates, Inc., 1998a);

the PCBs, present in soils at IOC, are

presumed to be related to the waste-oilprocessing activities there. The source of the

elevated arsenic concentrations south of Texas

Road in the soils east of the brook and at

higher elevations than the stream banks was

unknown, however, prompting the U.S.

Environmental Protection Agency (USEPA)

and NJDEP to extend a previous U.S.

Geological Survey (USGS) cooperative study

of arsenic in soils in the vicinity of IOC

(Barringer and others, 1998). The objective of

the present study was to identify the sources of

arsenic in soils and sediments at the Texas

Road site through an evaluation of relevant

hydrologic processes and pathways and to

determine background arsenic levels for

wetlands soils in the area as well as rates of

sedimentation in wetlands. Background

arsenic concentrations determined during th

study are applicable on a regional scale to

similar wetlands in other parts of the Atlant

Coastal Plain.

Purpose and Scope

This report presents the results of a

study to (1) develop and test hypotheses

regarding the arsenic source(s); (2) determi

the distribution of arsenic and other constituents in soils and sediments; (3) determine 

mechanisms of arsenic distribution; and (4)

identify the sources of arsenic in soils and

sediments adjacent to Birch Swamp Brook 

the vicinity of Texas Road in Monmouth

County, New Jersey.

Description of the Study Area

Geology and Soils

The Texas Road site, organic wetlan

soils (humaquepts) in nearby watersheds, an

IOC, located about 0.6 mi south of the Texa

Road site, are underlain directly by the

Englishtown Formation, a sandy Coastal Pl

deltaic deposit of Cretaceous age (Owens a

Sohl, 1969). Clay lenses are interspersed

throughout the formation, and are more

common with depth. The contact between t

basal Englishtown Formation and the under

lying Woodbury Formation, primarily a clay

deposit of Cretaceous age, is gradational

(Owens and others, 1995).

The sands of the Englishtown

Formation at the Texas Road site range from

pale brown to dark grey in color; the darker

colors appear to depend on the degree to wh
7

a reducing environment is present. The sands

are composed mostly of quartz grains, some

with brown ferric (iron) hydroxide coatings.

Muscovite occurs as a minor mineral phase;

small fragments of “ironstone” (iron

hydroxide) channers and (or) small fragments

of lignite are observed in some samples.

The clay lenses in the Englishtown

Formation are composed of greyish to

brownish clay, which is mostly kaolinite, with

some illite and smectites present (see analyses

in Barringer and others, 1998). The clay

contains blebs of bright orange to dark reddish

brown silt that appears to derive its color from

iron hydroxides. The low hill in the southern

part of the Texas Road site, on which an

orchard once stood, is underlain by a clay lens.

Results of sampling during the present study

indicate that some of the sediment at the Texas

Road site is fill, both sand and clay, of local

origin; these clearly represent anthropogenic

deposits. Because the clay fill at the site is

from local materials, it is similar to clays in

naturally occurring lenses; however, the silt

blebs in the fill clays are disturbed and

deformed, and foreign materials such as

asphalt and concrete fragments commonly are

present.

The soils developed on the

Englishtown Formation sediments tend to be

sandy and acidic; where clay lenses are

present, the soils are loamy, containing a

higher percentage of clay and silt-size particles

than soils developed on sand. The soils present

at IOC belong to the Keyport soil series, which

are sandy loams. Soils mapped at the Texas

Road site include Keyport soils and the Elkton

loam, although the dominant soils are

humaquepts--highly organic, frequently

inundated soils with little development of

horizons (Jablonski and Baumley, 1989).

The humaquepts contain quartz sand

and silt grains that range from whitish through

brown to black in color. Partially decompos

leaves, twigs, and other organic matter

compose the predominant material of the

humaquepts. The humaquepts are dark

blackish brown in color, acidic (pH 4.1-5.5)

spongy in texture, and fairly easily

compressed.

The sediments in the stream channe

point bars, and stream banks have variable

characteristics. Thin layers of humaquept so

crop out sporadically along the stream bank

stream-deposited materials tend to be quart

rich gravels, sands, and silts, which typicall

range from light brown to dark reddish brow

in color.

Land-Use History

Settlement of the part of Monmouth

County in which the Texas Road site is loca

began in the 17th century. Farming was a

dominant activity in the 18th and 19th

centuries. In the early 20th century, vegetab

comprised the dominant crops (Jennings an

others, 1916); fruit-growing increased in th

area in the 1920’s (Lee and Tine, 1932). On

the Atlas Sheet 29 of the Geological Survey 

New Jersey (Kümmel and Vermeule, 1914)

first surveyed in 1884 and revised in 1914, 

Texas Road site and the area on the opposit

side of Birch Swamp Brook are shown as a

cranberry bog. An aerial photograph taken 

1932, however, indicates that both plowed

fields and orchards were present at the Texa

Road site and in the immediate vicinity (fig

Land use near the Texas Road site a

IOC has changed substantially during the p

4 decades. The aerial photograph taken in

1932 (fig. 4) and also one from 1940 (not

shown) indicate that much of this part of

Monmouth County had remained as farmla

(both row crops and orchards) and forest.

Extensive residential development began af

World War II, accelerated during the 1950’s
Texas Road site Birch Swamp Brook

Aerial photograph from New Jersey

Department of Environmental Protection

0 200 400 600 800 1,000 FEET

0 200 METERS

75 74

41

40

39

Area of detail

Study area

Newark

Middlesex Co.

Morganville

0 10 20 MILES

Monmouth Co. 0 10 20 KILOMETERS

Lakehurst

NEW

JERSEY

Marlboro Township

Figure 4. Aerial photograph of the study area, Marlboro Township, Monmouth County, 

New Jersey in 1932. (From New Jersey Department of Environmental Protection, 

Tidelands, Trenton, New Jersey).

8
9

and continues to the present (1998). Very little

of the former farmland still exists in that form;

where not developed for residential use,

former fields and orchards have reverted to

wooded areas.

Interpretation of aerial photographs

indicates that much of the Texas Road site was

open land, mostly under cultivation, during the

1930’s and 1940’s, and the area adjacent to the

sharp bend in the brook was wooded, probably

a wetland. Land immediately northeast of the

Texas Road site was orchard until at least the

mid-1950’s, and the southern part of the Texas

Road site also was orchard. The present owner

indicates that the property was farmed even

earlier than the 1930’s. Other than the

indication of a cranberry bog on the 1914 map,

however, no information about crops grown

before 1932 is available.

Some details of land-use history since

1940, based on recollections by local residents,

are known. Crops on the farm fields during the

late 1940’s and 1950’s included horse corn and

peas in the area dominated by organic soils;

tomatoes also were grown. Chicken barns were

built in the southern part of the study area in

the 1950’s; a house in the former orchard area

was built in 1948, and a second house nearer

Texas Road was built in 1984. Although some

of the land reverted to woods during the 1980’s

and early 1990’s, the trees are being cleared,

and row-crop cultivation is again underway.

Birch Swamp Brook was dammed at

Texas Road in about 1950 to create a

swimming hole, but this project was

abandoned in about 1952 when oil spills or

dumping, believed to originate at IOC, caused

petroleum to travel down the brook (Steven

Byrnes, oral commun., 1997). The present

owner has no recollection of the stream having

flooded the farm fields or orchard, even during

severe storms such as Hurricane Diane in

1955.

According to the present owner, the

area of sand fill next to the brook near the

sharp bend (west of the property owner’s

house) was in place when his family moved 

the site in the mid-1940’s (fig. 5, p. 10). Th

area of clay fill north of the house, which

extends to the stream bank, was placed ther

since about 1992; the clay is from a parking

area within 5 mi of the Texas Road site.

Acknowledgments

The authors thank Kim O’Connell a

Trevor Anderson of USEPA, and Anthony

Farro, Edward Putnam, Thomas Cozzi,

Kenneth Petrone, and Joseph Maher of NJD

for their technical support during this study

Field assistance and help in shipping sampl

from Steven Byrnes and John Evenson of

NJDEP is gratefully acknowledged. Soil

sampling was carried out by Nicholas Smith

Timothy Oden, and Robert Rosman of the

USGS; the authors are most grateful for the

careful work in this regard. The authors also

thank Marci Marot of the USGS for collecti

and analyzing samples for lead-210 ages.

Richard Sanders, also of the USGS, assisted 

sample collection.

STUDY APPROACH AND METHOD

Several hypotheses as to the possibl

source of arsenic at the Texas Road site wer

postulated and the study was designed to

investigate each hypothetical source. The

hypothetical sources are

1. Arsenic-bearing materials have

been transported down the stream

and have been deposited by fluv

processes both near and far from

the stream.

11

2. Stream-deposited sediments

contaminated by wastes from IOC

have been moved from the

streambed to higher elevations

during farming, landscaping, or

stream-channelizing activities.

3. Arsenic waste has been moved

from IOC to the Texas Road site by

means other than fluvial processes

(waste dumping, for example).

4. The arsenic is naturally occurring,

contributed by underlying geologic

materials.

5. The arsenic results from past use of

agricultural chemicals.

Given the observed distribution of

arsenic in the soils, an additional hypothesis

regarding arsenic distribution was postulated--

that arsenic, whatever its source, has been

mobile in the soils of the study area; thus the

present distribution of arsenic is not the

original distribution of arsenic.

Once the recently collected chemical

data for soils in undeveloped forested land, in

orchards, and at IOC (Barringer and others,

1998) and at the Texas Road site (L. Robert

Kimball and Associates, Inc., 1995a) had been

examined and the aerial photographs of the

study area from 1932 to the present had been

evaluated, the following tasks were conducted:

1. Sampling and analyzing soils and

floodplain sediments adjacent to

Birch Swamp Brook at the Texas

Road site to determine the concentrations and distribution of arsenic

and selected other chemical constituents in the various stratigraphic

units;

2. Performing a ground-penetrating

radar survey of the Texas Road s

to determine whether the

humaquepts had been disturbed;

3. Determining the time of depositi

and (or) exposure to the

atmosphere of the humaquepts a

the Texas Road site in order to

evaluate evidence of human dist

bance and fluvial deposition of

arsenic in the humaquepts far fro

the stream.

4. Sampling and analyzing

humaquepts in other watersheds 

Monmouth and Middlesex

Counties to determine backgrou

concentrations (from geologic a

atmospheric inputs) of arsenic a

other chemical constituents, and

comparing the chemical composition of the humaquepts from th

Texas Road site with that of the

humaquepts from other watershe

by means of statistical tests;

5. Sampling and analyzing soils in 

adjacent orchard to determine

whether chemical constituents

present (such as arsenic, lead, or

calcium) are indicative of arseni

pesticide use.

Quality-Assurance Program

Because the present study was an

extension of a previous study (Barringer an

others, 1998), procedures were outlined in a

addendum to the existing Quality Assuranc

Project Plan (QAPP) on file at, and approve

by, the USEPA, Region II, in New York, N.

This work plan includes a description of

standard operating procedures and the Sam

and Analysis Plan.
12

The quality-assurance program used in

the previous study is described in detail in

Barringer and others (1998); procedures used

in this study generally are the same and are

summarized in appendix 1. Soil-sampling

procedures followed the protocols for

sampling developed by NJDEP and approved

by USEPA. Although the NJDEP procedures

do not mandate rinsate equipment blanks for

soil samples, these blanks were collected

during both the previous study and the current

study. Barringer and others (1998) found that

contamination of soil samples introduced

during collection and handling was negligible. Therefore, only one rinsate equipment

blank was collected for 16 soil cores collected

during the present study. Two soil cores were

collected during the previous study. No

equipment blanks were collected during soil/

sediment sampling in the seven soil pits, as the

samples were collected directly into the

sample bottle with clean, disposable

equipment.

Standard reference materials (SRMs)

were submitted for analysis as blind samples

during the previous study, but this was deemed

unnecessary during the present study, as

laboratory results for the SRMs previously

submitted were considered satisfactory. All

analytical data were validated by NJDEP. A

synopsis of the NJDEP validation procedures

is found in Barringer and others (1998).

The ground-penetrating-radar survey

was intended as a reconnaissance effort;

therefore, quantification was not necessary.

The reproducibility of results was assured by

traversing the same path in a forward and

backward direction, and comparing the two

charts generated during the forward and

backward traverses.

Quality-assurance procedures for the

determination of lead-210 by polonium-210

analysis included adding to the samples a

polonium-209 spike, calibrated to a Nationa

Bureau of Standards isotope standard.

Soil Sampling

Results of reconnaissance sampling 

soils at the Texas Road site, conducted by

using a bucket auger, indicated that the

sediment on the point bars and along the

stream bank consisted of about four to six

separate soil horizons and (or) sediment lay

representing distinct depositional events in 

upper 18 to 24 in. of the soil/sediment profi

At higher elevations, the humaquepts overli

sands of the Englishtown Formation in most 

the study area, except where recent fill is

found, and Elkton soils are present in the

former orchard area.

Sample Collection

Samples were collected along five

transects (T1 through T5) that were roughly

orthogonal to the stream channel. The soils

and sediments along the stream bank and on

point bars were sampled by digging pits

(designated “P”) (fig. 5), exposing a clean fa

of soil/sediment by scraping with a clean

stainless-steel trowel, and sampling from ea

stratigraphic layer directly into the sample

bottle by using a clean, disposable plastic

spatula for each layer. Locations of the

sampling sites were determined by measuri

distances from landmarks with a tape.

At higher elevations (fig. 5), where

humaquepts overlie sand, where fill was

identified, or where soils other than

humaquepts are present, such as the former

orchard, samples were collected by using a 3

stainless-steel corer with butyl acetate liner

as described in Barringer and others (1998)

Core samples from the former orchard, whi

were not collected on a transect, were desig

nated “C,” and numbered. Core samples alo

the transects also were designated with a C,
13

and numbered beginning with the core

collected nearest the stream, but the core

number was preceded by the transect number.

Therefore, a core collected on transect 1, for

example, would be designated T1C1, if the

core were nearest the stream. Subsamples of

each core were designated “S” for sand and

silt, “H” for humaquept, or “CL” for clay. For

those orchard cores collected from the Elkton

soil series, the individual horizons were given

the appropriate letter (A, E, or B). The same

naming system used for the cores on transects

was used for samples from the pits. Pit

samples were collected starting with the

transect farthest downstream and working

upstream in order to avoid disturbing channel

and bank sediments upstream that might

contaminate downstream sediments.

The same coring technique used to

sample humaquepts and other soils in the

former orchard in the southern part of the

Texas Road site was used to sample

humaquepts in other nearby watersheds,

including Matchaponix Brook, Weamaconk

Creek, Pine Creek, and an unnamed tributary

of Deep Run (fig. 6). Details of sampling

protocols and equipment-cleaning procedures

are found in Barringer and others (1998).

Core samples were chilled and returned

to the USGS District laboratory, West Trenton,

New Jersey, where they were subsampled by

soil horizon or by sediment type and placed in

precleaned sample bottles by using clean

stainless-steel spatulas or disposable spatulas,

depending on the stiffness of the sediment

sample. Details of the subsampling method are

given in Barringer and others (1998). The

filled sample bottles were kept chilled and

shipped in clean coolers to the analyzing

laboratories, accompanied by chain-of-custody

forms.

Sample Analysis

Inductively coupled plasma

spectroscopy was used to analyze for all tar

analyte list (TAL) metals and metalloids

except mercury, which was determined by t

cold-vapor atomic absorption method. Tota

organic-carbon analyses were performed us

the Lloyd-Kahn method. These methods are

described in Barringer and others (1998).

Analytical results are reported in appendix 

which also contains soil logs and sediment

descriptions from field sampling sheets.

Quality-assurance and quality-control infor

mation relating to soil sampling and analysi

contained in appendix 1.

Ground-Penetrating-Radar Survey

The GPR survey was conducted as a

area reconnaissance to produce a generalize

map of the geohydrologic framework at the

site. The generalized map was used to

determine the presence of any subsurface

structural features that might be associated

with movement and deposition of arsenicbearing materials at the site. Although the

aerial photograph from 1932 (fig. 4) shows 

stream channel occupying its present positi

a topographic map from 1914 (fig. 7) indica

an extensive wetland area, used as a cranbe

bog, with a stream-channel location that

appears to be farther east than the present

location. If the stream channel were modifie

during 1914-32 to create a larger area for

farming, it was anticipated that results of th

GPR survey would delineate general areas o

disturbance. The presence of such areas cou

indicate that arsenic wastes from early activ

ities at IOC had been deposited in a former

stream channel and, perhaps, redistributed.
erRiv

Tennent Pond

an

South

Mataw

Creek

Brook

Tennent

tsLeffer Lake Brook Birch Swamp

Deep

Run

Brook

Brook

Pine

Matchaponix

Mill Pond

Weamaconk

Brook

Middlesex County

Monmouth County

18

ROUTE 9

18

516

516

527

79

520

Ga

P

r

a

d

r

en k

Sta w

te ay

34

Englishtown

H3

H5 H7

H4

H4D

Clark Mills

MANALAPAN

H6

H2

Texas Road site

Imperial Oil Company

Superfund site

H1 Spring Valley

Robertsville

MARLBORO

MATAWAN

exas Road

Morganville

T

H6 Site location and number

Surface-water gaging station and number

Browntown

Mount Mills

Base from U.S. Geological Survey digital data, 

1:100,000, 1983, Universal Transverse

Mercator Projection, Zone 18 EXPLANATION

01406500

01406500

01406000

74 22'30" 74 15'

01407000

40 22'30"

40 17'30"

3 KILOMETERS

0 1 2 MILES

0 1 2

Figure 6. Location of humaquept sampling sites and surface-water gaging stations in watersheds in

Middlesex and Monmouth Counties, New Jersey.

14
0 1 2 MILES

0 1 2 3 KILOMETERS

TEXAS ROAD SITE

Base from Geological Survey of New Jersey,

Atlas Sheet No. 29, 1:63,360, 1914

Figure 7. Topographic map from 1914 showing wetland cranberry-bog area, Texas Road site, 

Monmouth County, New Jersey.

15
16

Data Collection

The RAMA/GPR system, manufactured by Mala GeoScience1, uses a 200-MHz

antenna, which was towed by the operator who

carried the electronics and recording

equipment in chest- and backpacks. GPR

profiles were collected continuously along six

transects from the dirt access road across

fallow farm fields to the bank of Birch Swamp

Brook or to the treeline just east of the brook

(fig. 8). (A seventh transect across a fill area is

not reported as no radar penetration was

measured.) The transects ranged from 295 to

440 ft in length; lengths were measured with a

300-ft tape measure. Data along the transects

were collected in both an east-west direction

and a west-east direction to determine reproducibility of data.

Data Analysis

The GPR data were downloaded and

printed on paper charts, shown in appendix 3.

The paper charts were analyzed by (1) delineating radar reflectors, such as the water table

and bedding features; (2) calculating the depth

to the water table and bedding features on the

basis of two-way travel time (in nanoseconds),

and (3) associating a bedding feature on the

charts with sediment either exposed at land

surface or known to be present in the soil/

sediment profile from previously collected

cores. The observed features were drawn on a

Mylar overlay sheet, copies of which are

shown in appendix 3.

The depth to observed features such as

the water table or bedding was calculated by

using the formula

D = T x Vc/2

where T is the two-way travel time of t

radar waves (in ns) and

Vc is the velocity of radar wave

through the sediment.

Details of the theory behind the GPR

technique are presented in appendix 3.

Land surface in the part of the Texa

Road site where the GPR survey was

conducted is relatively flat; altitudes range

from about 70 to 80 ft above sea level. The

contact between the humaquepts and sands 

the underlying Englishtown Formation was 

strongest first radar reflector encountered

(shown near the top of each GPR chart, app

3). This contact typically is found at a depth 

1 to 4 ft below land surface. The reflection

indicating the water table generally was dee

than the humaquept/sand interface; the dept

to the water table varies seasonally and was

greater during the summer, when the GPR

survey was conducted. Above the water tab

the velocity of radar waves was interpreted 

be 0.45 ft/ns. Below the water table, the

velocity of radar waves was calculated to be

0.2 ft/ns. As a result of this velocity change

10-ns interval above the water table was ab

4.5 ft, whereas a 10-ns interval below the wa

table was about 2 ft.

Age Dating of Humaquepts

Because arsenic concentrations in th

humaquepts typically were larger at depth th

at the surface, the hypothesis that large

amounts of arsenic were directly deposited

when the humaquept layer was thinner than 

is now was tested. Accordingly, the rate of

deposition and age of the deepest humaquep

needed to be determined. Ages of recent

1The use of trade names is for identification purposes only and does not constitute endorsement by the

U.S. Geological Survey.
Birch

Swamp 

Brook

0 200 300 FEET

0 50 METERS

Topographic contour

Edge of woods

Tree

Unpaved road/driveway

Fence

Ground-penetrating-radar

survey transect

Base from L. Robert Kimball and Associates, Inc., 1995b

EXPLANATION

House

Chicken barns

100

Texas Road

6

5

4

3

2

1

Figure 8. Approximate location of transects used in ground-penetrating-radar survey, Texas Road site, 

Monmouth County, New Jersey. (Map modified from L. Robert Kimball and Associates, Inc., 1995b)

17
18

sediments (more precisely, the dates associated

with recent exposure to the atmosphere) can be

determined by measurements of atmospherically deposited radioisotopes of several

elements (Faure, 1986); of these, lead-210

(

210Pb) is commonly used. To be a candidate

for age-dating sediments, the chemistry and

half-life (amount of time required for half a

given number of atoms to decay to another

element) of the radioisotope need to be known.

Additionally, the initial amount of the isotope

per unit of substrate needs to be known or

accurately estimated, and, once the isotope is

encapsulated in the substrate, any changes in

concentration must be the result of radioactive

decay. Further, the isotope’s decay rate must

be in a range appropriate to the scale of time

investigated, and easy to measure. A member

of the uranium-238 (238U) series, 210Pb, with a

half-life of 22.8 yr, is produced by decay of

radon-222 (222Rn), an intermediate gaseous

progenitor. 222Rn, formed by decay of radium,

escapes either by recoil during the ejection of

the alpha particle or by diffusion into the

atmosphere. 222Rn rapidly decays to form

210Pb, which has a residence time in the

atmosphere of about 10 days, and is removed

by rain or snow. 210Pb is sorbed to or incorporated into depositing sediments (fig. 9); this

210Pb is in excess of any 210Pb present as

“background” in the materials being deposited.

Sample Collection and Analysis

A 2-ft core was collected at the Texas

Road site, in an area underlain by a buried

stream channel, by using a 4-in.-diameter

polyvinyl chloride (PVC) corer that contained

a polycarbonate liner. Additionally, two 3-ft

core samples of humaquepts were collected in

a fallow farm field at the site (see fig. 5 for

locations) by using a 2-in.-diameter stainlesssteel corer with a butyl acetate liner. The cores

were X-rayed at the Monmouth County Health

Department facilities in Freehold, N.J., to

determine the nature and depths of small-sc

disturbances of the soils.

The soil cores were prepared for

isotope analysis by sectioning at 2-cm (0.8-i

intervals. The activity of 210Pb was determined by measuring the activity of its “gran

daughter” element, polonium-210 (210Po).

210Po decays solely by alpha-radiation and 

easy to measure. The 210Po is isolated from

the samples by dissolving the material in nit

acid and plating the isotope on a silver

planchet (Flynn, 1968). During dissolution 

the sample, a known amount of the isotope

209Po is added. The activity of 210Po is dete

mined by comparing the activity of the trac

to that of the Po in the sample. Because 210

and 210Pb have been shown to be in

equilibrium (their activities are about the

same), the activity of 210Pb can be calculate

once 210Po activity is determined. The resul

of isotope analysis are presented in appendi

4.

Data Analysis

The process by which 210Pb is form

in, and deposited from, the atmosphere leads 

the presence of excess or “unsupported” 210

in sediments. “Unsupported” 210Pb is that

210Pb whose activity is greater than that of i

radium progenitor in the sediments, wherea

“supported” (or background) 210Pb has the

same activity as its radium progenitor (fig. 1

Dates of the sediment deposition are calcula

by determining the decrease in 210Pb activity 

successive depths in the sediment core. If th

initial 210Pb activity is known, or is estimate

the age of sediment deposited at a particula

depth is calculated by:

( ) 210 ⁄ 210 Tage = ln A Pb0 A Pbh × 1 ⁄ λ 

where A 210Pb0 is the unsupported 210Pb

activity in disintegrations per minute at tim

zero (the present);
19

210Pb

222Rn 222Rn

226 210 226 210 Ra + Pb Ra + Pb

Stream sediments

Fluvial deposition

Radioactive decay

Radioactive decay

Atmospheric

deposition

deposition

Atmospheric

fusion toDif

atmosphere

atmosphere

Diffusion to

Figure 9. Conceptual model of the geochemical 

process that produces "excess" Pb in sediments. 210

Unsupported Pb-210

DEPTH (TIME)

Supported Pb-210

ACTIVITY

Figure 10. Ideal distribution of Pb in a 210

sedimentary section showing the difference 

between "supported" and "unsupported" Pb. 210
20

A 210Pbh is the 210Pb activity in disintegrations per minute at depth h; and

λ is the decay constant for 210Pb,

which equals 0.03114.

A plot of 210Pb activity (on a logarithmic

scale) as a function of depth ideally is a

straight line, the slope of which indicates the

relative sedimentation rate. A rapid decrease

in 210Pb activity with depth indicates a slow

rate of sediment deposition; conversely, little

or no decrease in 210Pb activity with depth

indicates a rapid rate of deposition.

Because no data on radium-226 (226Ra)

activity in the humaquepts were available,

226Ra activity was estimated; the activity of

226Ra is assumed to be at equilibrium with the

activity of supported 210Pb. The method of

Binford (1990) was used to determine the

activities of supported and unsupported 210Pb.

The limit of unsupported 210Pb with depth is

determined by using a Students t-test, which

identifies the data point that is significantly

different (at the 95-percent confidence level)

from the mean of the activity data points near

the asymptote on the plot of 210Pb activity as a

function of depth. The number of data points

near the asymptote that are included depends

on visual inspection of the curve. Activities at

depths below the significantly different data

point represent supported 210Pb activities.

The calculation of dates of deposition

depends on a model that best describes the

geochemistry of 210Pb. Two models that are

widely applied to dating sedimentary deposits

are the Constant Initial Concentration (CIC)

model and the Constant Rate of Supply (CRS)

model. In the CIC model, 210Pb activity in the

depositional system is assumed to have been

constant through time, whereas in the CRS

model, the flux of 210Pb to the sediment is

assumed to have been constant and a change in

rate of sediment accumulation is assumed to

result in dilution or concentration of 210Pb.

Lead is assumed to be immobile in both

models; Binford (1990) indicates that lead c

migrate only in extremely acidic environments.

These models do not account for

mixing or post-depositional disturbances. I

order to circumvent this problem, a variatio

of the CRS model, the Best-Fit model, was

used in this study. The cores are examined

prior to performing calculations; data from

sections where mixing is indicated are

excluded from the calculations. If several

background (supported) 210Pb activities are

measured, the activity values are averaged, a

excess (unsupported) 210Pb for each data po

(greater than background) is determined by

subtracting the averaged background value

from the measured activities greater than

background. The natural logarithms (ln) of

excess 210Pb values from the unmixed portio

of the cores are plotted (ln 210Pb activity as 

function of depth), and a best-fit line is calc

lated. If the correlation coefficient (r2) for t

best-fit line is greater than 0.9, the fit is

considered to be acceptable. The apparent

210Pb age for each depth sampled can be cal

lated by using the equation of the best-fit lin

The rate of sedimentation can be determine

from the slope of the line.

Statistical Analysis of Humaquept

Chemical Constituents

Data Conditioning

The raw data consisted of concentra

tions of 15 chemical constituents in 52

humaquept samples. The variables used in

statistical analyses were concentrations of t

constituents Al, As, Ba, Ca, Cr, Cu, Fe, Mg

Mn, Ni, K, Pb, V, Zn, and TOC. Twenty-ni

samples (observations) were humaquept

samples from the Texas Road site. The

remainder were humaquept samples collect
21

from four other watersheds. There were no

missing values. Censored concentration

values (below detection limits) were converted

to the censoring threshold value. Ca and Mg

each had three censored values. Al, Cu, and Fe

concentrations were scaled by dividing by

1,000, and K concentrations were scaled by

dividing by 100. Pb and Cu concentrations

were normalized to TOC by dividing each

value by the related TOC value divided by

1,000, and As concentrations were normalized

similarly to Fe. Data were converted to

logarithms (base 10) to reduce distributional

skewing effects.

Model Testing and Validation

The conditioned data were subjected to

canonical discriminant analysis, which is a

statistical classification procedure conducted

by using the “normal” option of the SAS statistical software procedure DISCRIM (SAS

Institute Inc., 1990). This procedure was done

to determine whether the observations could

be classified into two groups (Texas Road and

“other”) on the basis of their geochemical

composition as represented by the variables

listed above. Because TOC was used in

normalizing two of the other variables, it was

not used as a separate variable in the analysis.

Canonical variates (variables) are

linear combinations of the original variates

used in the analysis, and contain all of the

variance present in the original variate set.

Canonical variates are used to simplify the

geometry of the classification by reducing the

dimensionality of the data set. In this case,

only the first canonical variate was significant

(F = 21.06, α = 0.0001). That is, the two

groups (Texas Road humaquepts and other

humaquepts) were separable on the basis of

their scores on a single linear combination of

the original variables. On the basis of crossvalidated posterior probabilities, which are

asymptotically unbiased and robust measurements of model performance, the overall

classification accuracy of the model was 96

percent. Accuracy for observations from th

Texas Road category and the “other” catego

was 100 percent and 93.1 percent, respective

The posterior-probability error-rate estimate

for the model was 0.0012.

To confirm the classification perform

by using the normal option of DISCRIM, th

“npar” option was used. This is a nonparametric, nearest-neighbor classification meth

that is robust to violations of assumptions

required under the normal option. Classification accuracy of the second procedure, on

the basis of cross-validated posterior probab

ities, was more than 98 percent, thus tending 

confirm the classification determined under 

normal option.

Because some of the 15 original

variables correlated weakly with the canoni

variate, data reduction was done by subjecti

the original variables to a stepwise discriminant analysis. This produced a model with

just five variables--the logarithms (base 10) 

concentrations of normalized As, Ba, Ca, C

and Mg. That model was then re-estimated 

using the DISCRIM procedure with the norm

option. Classification accuracy with crossvalidated posterior probabilities for the mod

was greater than 98 percent--compared to

about 96 percent in the first model. Finally, 

model was re-estimated by using nonparametric discriminant analysis. The nonparametric discriminant does not require

assumptions made for the preceding model

Classification accuracy for this model was 1

percent.
22

ARSENIC IN SOILS AND

SEDIMENTS ADJACENT TO

BIRCH SWAMP BROOK

The current distribution of arsenic in

soils at the Texas Road site varies areally as

well as vertically through the soil profile. This

nonuniform distribution probably results from

a variety of transport and deposition mechanisms that have operated at different times

during the past 7 decades. Natural mechanisms

include fluvial transport and deposition of

arsenic-bearing materials, weathering and

illuviation of arsenic-bearing materials, and a

series of geochemical processes. Mechanisms

related to human activities include movement

of soils and sediments during landscaping and

agricultural activities.

Spatial Distribution of Arsenic and

Other Constituents in Soils and

Sediments

Stream Sediments

Arsenic concentrations in sediments

collected from pits along the stream bank and

on point bars were highly variable, both among

locations and among stratigraphic layers at

each location. With the exception of the sand

layers from T5P1, the pit farthest upstream,

arsenic concentrations in samples from sand

layers typically were less than 20 mg/kg,

whereas those in samples from silty and clayey

layers were greater than 20 mg/kg. Organicrich layers were present in some of the pits;

arsenic concentrations varied from 4.7 to 59.5

mg/kg in samples from these sediments. In

general, arsenic concentrations in sediments

from pits other than T5P1 tended to be within

the range of concentrations measured in

sediment from other watersheds (table 1).

The layers exposed in pit T5P1 (fig.

11) were reddish sands, samples of which

contained arsenic concentrations ranging from

179 to 2,570 mg/kg. The composite sample 

contained an arsenic concentration of

179 mg/kg, whereas individual subsamples

within the stratum contained arsenic concen

trations ranging from 702 to 735 mg/kg. Th

concentration of arsenic in the composite

sample S3 probably resulted from dilution o

the highly contaminated sediment by less

contaminated sediment.

The largest iron concentration

measured during the study (49,900 mg/kg) w

associated with the largest arsenic concentration (2,570 mg/kg) in this sand sample

(T5P1S2), indicating that arsenic is strongly

associated with iron hydroxide in this samp

0"

Root mat

3" Dark greyish-brown fine 

sand, small amount me

white sand, fine roots 6"

Dark reddish-brown

medium sand, slightly

silty

Dark grey med

sand

16"

Black fine muc

Sample S3A: 

As = 702 mg/kg

Cu = 230 mg/k

Fe = 39,200 mg

Pb = 113 mg/kg

Dark reddish-b

medium sand 26" Sample S3B: 

As = 735 mg/kg NOT TO SCALE Cu = 4.9 mg/kg 

Fe = 29,500 mg

Pb = 20.2 mg/k

Dark grey fine 

sand, mica flak

Sample S3C: 

As = 717 mg/kg

Cu = 214 mg/k

Fe = 16,800 mg

Pb = 80.8 mg/k

Sample S1:

As = 281 mg/kg

Cu = 68.4 mg/kg 

Fe = 12,500 mg/kg

Pb = 695 mg/kg

Sample S2: 

As = 2,570 mg/kg

Cu = 18.7 mg/kg

Fe = 49,900 mg/kg

Pb = 80.7 mg/kg

Sample S3: 

As = 179 mg/kg

Cu = 14.8 mg/kg

Fe = 4,850 mg/kg

Pb = 24.5 mg/kg

Figure 11. Stratigraphy of stream sediments in 

T5P1, Texas Road site, Monmouth County, New 

Jersey. (Pit location shown in fig. 5; ", inches; 

mg/kg, milligrams per kilogram)
23

Table 1. Summary statistics for arsenic concentrations in soils and sediments, Middlesex and Monmou

Counties, New Jersey

[mg/kg, milligrams per kilogram; Fm., Formation; >, greater than; >, greater than or equal to; <, less tha

”, inches; ND, not detected; --, not calculated]

Concentration (mg/kg) Number of

samples Num

Number of >20 mg/kg, sam

Material/land use samples Minimum Median Maximum <40 mg/kg >40 

Geologic substrate Englishtown Fm. sand1,2 11 1.1 5.4 11.1 0 

Englishtown Fm. sand3 4 1.2 5.4 8.6 0 

Englishtown Fm. sand2,4,5 23 ND6 1.8 18.8 0 

Englishtown/Woodbury Fm. clays3 21 8.1 18.3 41.2 7 

Orchard soils Texas Road site1

 A horizon 3 5.2 5.7 6.1 0 

 B horizon 8 2.3 7.7 15.6 0 

 Clay 2 3.4 -- 44.1 0 

Monmouth, Middlesex Counties3

 A horizon 14 4.2 11.0 41.5 1 

 E horizon 4 2.4 2.9 38.3 1 

 B horizon 23 3.3 8.1 16.9 0 

 Clay 6 17.8 25.4 39.1 5 

Texas Road site4

 0 - 6” 12 3.4 5.3 11.5 0 

 12 - 18” 12 ND6 2.9 18.5 0 

 24 - 30” 9 ND6 2.9 40.1 0 

Residential soils (former orchard)3

 A horizon 23 10.4 25.1 70.5 14 

 B horizon 40 3.3 21.4 149 17 

 Clay 25 11.4 18.7 42.3 9 

Humaquept soils Texas Road site1 27 6.3 21.1 139 7 

Other watersheds (Monmouth, 24 4.9 22.0 43.1 14 

 Middlesex Counties)1

Texas Road site4,5 90 1.6 18.0 208 18 

Fill materials1 Sand 5 0.68 3.4 15.9 0 

Clay 12 2.3 19.3 28.4 5 

Birch Swamp Brook streambed and bank sediments1

Sand 17 <0.86 15.9 2,570 3 

Clay (fill) 2 36.7 - 40.7 1 

Humaquept 5 4.7 11.5 59.5 1 

Streambed and bank deposits, other watersheds

(Monmouth, Middlesex Counties)1

Sand 4 6.4 13.0 81.8 0 

Clay 1 6.8 -- 6.8 0 

1This study.

2Only sands underlying humaquepts and not part of a soil series or sand fill are included.

3Barringer and others, 1998.

4L. Robert Kimball and Associates, Inc., 1995a.

5Includes 8 sample sites on west side of stream and 32 sample sites on east side of stream.

6Reporting limit is about 0.3 mg/kg.
24

Another sample (T5P1S1) from the uppermost

sand layer in this pit contained 281 mg/kg of

arsenic, 695 mg/kg of lead, and 68.4 mg/kg of

copper; these were the largest values for these

latter two metals measured in soils from the

Texas Road site during this study. The copper

concentration in this sample was larger than

concentrations previously measured in soils

from nearby forested areas and orchards, and

was similar to copper concentrations measured

in some soil samples from IOC and the adjacent residential area (Barringer and others,

1998). The lead concentration also was larger

than the largest measured in orchard soils, and

similar to concentrations measured previously

in soils at IOC, although still larger concentrations also are reported for IOC soils (Barringer

and others, 1998). In addition to the highly

elevated concentrations of arsenic, lead, and

copper measured in samples from pit T5P1,

water that collected at the bottom of the pit

was observed to have an oily sheen and petroleum odor.

The stratigraphy revealed in the soil

pits dug at the edge of the stream (T1P1, T2P1,

T3P1) indicates that humaquepts underlie the

sands along the banks; therefore, the original

surface of the stream banks and channel

probably was composed of highly organic

materials derived from the surrounding

vegetation. The sands and silts that overlie the

humaquepts along the stream channel may

have arisen from disturbances upstream, as

they clearly postdate the original wetlands

humaquept soils. At one location (T2P1), the

upper humaquept layer contained small pieces

of brick, which presumably had been transported by stream waters. The arsenic concentrations in the humaquepts along the stream

channel (parallel to Texas Road in the northern

part of the study area), measured at three

locations (T1P1, T2P1, T3P1), ranged from

24.5 to 59.5 mg/kg, which are similar to, or

slightly larger than, concentrations measured

in humaquept samples from other watersheds.

The locations of stream sediment

samples collected during this study are wid

distributed along the stream channel; the

sampling conducted by NJDEP along the

stream reach parallel to Texas Road include

large number of cores (77) in stream-bank a

point-bar sediments along a short (less than

300 ft) stream segment. Thus, the density o

samples in this part of the stream is high, an

the distribution of arsenic in the sediments (

fig. 3) can be examined in more detail than

elsewhere along the stream. In general,

arsenic concentrations on the banks are larg

near the stream than farther from it, and larg

concentrations tend to be associated with po

bars or incipient point bars, which are areas 

sediment deposition. Near the stream, whe

arsenic concentrations are highly elevated, t

concentrations generally increase with dept

Whether this vertical distribution indicates t

more arsenic was deposited decades ago tha

was deposited recently, or whether it indica

arsenic mobility, cannot be assessed at this

time. No other constituent concentrations

were measured in the samples, so spatial

trends for other constituent concentrations t

might support a hypothesis of arsenic mobil

cannot be determined from these data. It

appears likely that sediments deposited at th

Texas Road site during and shortly after

arsenical pesticides were produced at IOC

would contain larger concentrations of arse

than sediments transported from the site

several decades after pesticide production h

ceased. Thus, deeper sediments could be

expected to contain more arsenic than surfic

sediments, if arsenic mobility is not a factor 

the observed distribution.

Although some copper and lead

concentrations measured previously in soil

samples from IOC were in the range of

background concentrations in area soils,

concentrations of both metals in other soil a

sediment samples from IOC were highly

elevated (table 2). Therefore, copper and le
25

Table 2. Summary statistics for copper and lead concentrations in soils and sediments,

Middlesex and Monmouth Counties, New Jersey

[mg/kg, milligrams per kilogram; Fm., Formation; >, greater than; <, less than; “, inches;

ND, not detected; -, not calculated]

Copper

Material/location

Number of

samples

Concentration (mg/kg)

Minimum Median Maxim

Imperial Oil Company Superfund site soils/sediments1

Imperial Oil Company Superfund site soils/sediments2

Soils, undeveloped areas2 A horizon

B horizon

Geologic substrate2 Englishtown Fm. sand

Englishtown/Woodbury Fm. clay

Birch Swamp Brook streambed and bank sediments3

Sand

Clay (fill)

Humaquept

Humaquept soils3 Texas Road site

Other watersheds (Middlesex and

 Monmouth Counties)

23

30

12

23

4

20

20

2

5

26

24

7.0

.48

5.5

.55

<.51

5.7

<.23

17.3

2.2

6.9

4.2

26.5

8.5

7.7

3.4

1.5

13.3

7.9

--

11.3

14.9

13.2

3,34

16

3

1

1

6

1

1

3

14

Lead

Material/location

Number of

samples

Concentration (mg/kg)

Minimum Median Maxim

Imperial Oil Company Superfund site soils/sediments1

Imperial Oil Company Superfund site soils/sediments2

Soils, undeveloped areas2 A horizon

B horizon

Geologic substrate2 Englishtown Fm. sand

Englishtown/Woodbury Fm. clay

Birch Swamp Brook streambed and bank sediments3

Sand

Clay (fill)

Humaquept

Humaquept soils3 Texas Road site

Other watersheds (Middlesex and

 Monmouth Counties)

33

30

12

23

4

20

20

2

5

26

24

1.4

2.2

18.5

1.3

1.7

5.5

1.2

19.3

4.9

4.1

8.2

14.9

22.5

36.4

5.1

3.9

16.6

21.9

-

21.0

27.4

21.1

3,01

4,55

13

4

2

69

2

2

8

99

1E.C. Jordan Co., 1990

2Barringer and others, 1998

3This study
26

might be expected to be present in elevated

concentrations at the Texas Road site if sediments bearing wastes from IOC had been

transported downstream. With the exception

of a core of humaquepts (T4C2) west of the

present owner’s house, copper and lead concentrations tended to be largest in sediments,

mostly sands, collected from the pits along the

stream bank and channel. Although lead also

has been deposited from the atmosphere as a

result of lead-bearing emissions from automobiles and trucks, the stream sediments are less

likely than soils to accumulate metals from the

atmosphere, as stream sediments are moved

about by water and can be shielded from additional atmospheric input by subsequent sediment deposition. Some of the lead measured

in the stream sediments near the road could be

derived from runoff rather than directly from

atmospheric deposition. Additionally, runoff

from the farm fields, where lead arsenate may

have been used in the past, could have added

lead to the stream sediments.

Nevertheless, the concentrations of

lead and copper in samples of stream

sediments from the Texas Road site were

within the range of concentrations measured in

samples of sands and clays from other watersheds. Sample S2 from pit T5P1, with

evidence of petroleum contamination, highly

elevated arsenic concentrations, and copper

and lead concentrations in the range of those

measured in IOC soils, does appear to indicate

contaminant transport from IOC to the stream.

Similar instances of highly elevated arsenic

concentrations along the stream (see fig. 3)

were observed in areas where lead and copper

were not measured. Consequently, the distribution and concentrations of lead and copper

in the sediments are less well known than the

distribution and concentrations of arsenic. On

the basis of available data, concentrations of

lead and copper in stream sediments at the

Texas Road site do not appear to be reliable

markers of contaminant transport from IOC,

although it is possible that some of the lead

and copper measured in the sediments could

have originated at IOC.

During sampling for the present stud

petroleum was noted in streambed sedimen

upstream from the eastward bend, between

T5P1 and T3P1. Disturbance of the sedime

released petroleum to the stream. These

sediments appear to be a reservoir of adsorb

petroleum that has travelled downstream.

Because there is no known major land-surfa

source of petroleum at the Texas Road site, i

unlikely that petroleum is floating on the wa

table there, to be released into the sediments 

ground water discharges to the stream.

Sediments upstream and downstream from 

Texas Road site also contain adsorbed

petroleum (Steven Byrnes, oral commun.,

1997). In a recent investigation, L. Robert

Kimball and Associates, Inc. (1998a), also

found petroleum along the stream channel, a

PCBs in the sediments; concentrations of th

latter contaminants generally were largest

south of (upstream from) the Texas Road si

These results indicate that arsenic

concentrations in stream sediments are high

elevated, particularly on point bars, and are

within the range of concentrations measured 

soils at IOC. Relatively few copper and lea

concentrations are available; concentrations 

both metals were highly elevated in one

sample but generally were within the ranges 

concentrations measured in other watershed

Petroleum was found in association with

arsenic contamination.

Geologic Substrate and Humaquept

Soils

Arsenic concentrations in soils and

underlying Englishtown Formation sedimen

10 ft or more from the stream, which were

collected by coring, typically were larger in 

humaquepts than in the sands that underlie









1930's

Texas

Road

Humaquepts

1950

Texas

Road

Humaquepts

Sand and silt

Clay fill

1990's Texas

Road

Humaquepts

Sand and silt

NOT TO SCALE

Figure 16. Three cross sections depicting water levels and sediments at Birch Swamp Brook near

Texas Road, Monmouth County, New Jersey, prior to damming, during the period of damming, 

and in 1998.

36



9.1

8.4

ND

8.1

9.5

183

19.3

10.6

8.5

33.2

165

16.4

82.4

47.2

28.4

73.6

21.6

27.7

75.3

38.2

9.4 7.8

6.0 18.8

9.0

62.6 3.4

4.8

1.4

7.1

18.5

40.1

6.0

2.9

3.1

8.6

7.5

9.4

41.8

5.4

15.2

17.2

62.3

13.5

2.8

30.6

4.5

2.5

4.5

13.2

21.1

ND

8.0

15.5

65.5

13.8

87.6

60.6

10.6

8.2

1.8 13.2

30.1

15.8

13.8

17.8

3.7

9.6

13.4

52.2

25.6

30.7

26.3

13.6

13.2

18.9 5.7

1.6

2.9

B'

3.1

1.8

ND

A'

9.5

11.4

13.1

17.0

17.0

44.9

51.2

13.1

56.2

14.9

74.2

62.7

5.7

8.7

ND

8.3

10.0

33.1

28.5

1.5

0.88

27.5

51.9

1.1

24.7

88.4

8.5

58.6

86.4

4.4

34.1

1.6

1.5

2.7

12.3

1.7

8.3

2.3

ND

8.9

1.3

ND

19.5

74.4

1.8

12.7

208

1.7

24.2

29.7

15.7

15.5

41.1

36.8

7.9

2.1

7.3

2.7

0.86

ND

45.1

4.9

11.7

4.0

3.7

119

40.3

8.4

87.1

60.8

33.9

30.2

21.7

10.8

9.0

15.7

18.8

2.6

3.4

32.2

8.7

8.0

4.1

11.3

5.0

7.2

8.7

19.9

18.8

12.9

9.4

26.7

14.0 60.6

59.9

91.5

9.7

18.5

79.4

125

9,460

23.5 524

198

12.8 18.8

19.3

8.9

53.2

30.7

33.5

19.3

12.2

10.1

28.2

17.3

2.2

12.7

31.1

14.0

12.0

8.5

6.9

13.9

9.7

21.1

15.2

104

44.3

C'

D'

E'

F'

F

E

D

C

B

A

0 200 300 FEET

0 50 METERS

Base from L. Robert Kimball and Associates, Inc., 1995b

100

Approximate area within which 

arsenic concentrations exceed 

20 milligrams per kilogram

Line of section in figure 19

Topographic contour

Edge of woods

Tree

Approximate sample location--

Numbers are arsenic

concentrations, in milligrams per

kilogram, in soil from 0-6, 12-18, 

and 24-30 inches, repectively

EXPLANATION

A A'

8.0

4.1

11.3

Texas Road

Figure 18. Arsenic concentrations at three depths within soil profiles on east and west 

banks of Birch Swamp Brook near Texas Road, Monmouth County, New Jersey. 

(Modified from L. Robert Kimball and Associates, Inc., 1995b; arsenic concentrations 

from L. Robert Kimball and Associates, Inc., 1995a)

40