CERCLA site inspection rptThe Gila River Indian Reservation (GRIR) site is located approximately 10 miles southwest of Phoenix, Arizona. The geographic coordinates of the site are

SDMSDocID 2009745

L

r : : - " ' ~Purpose: CERCLA Site Inspection

Site: Gila River Indian Reservation51st AvenuePhoenix, ArizonaMaricopa County

She EPA ID Number:

URS Investigators:

Date of Inspection:

Report Prepared By:

Report Reviewed By:

Review Concurrence:

*Report Date: * April 23,1997

Document Control No.: 41.62312.71.33.1878 05.a.1

AZD981621881»

John P. ZwierzyckiGary Floyd

March 22,1996

John P. Zwierzycki

• ChrisLNelSon'

Submitted To: Carolyn DouglasEPA Region, IXSite Assessment Manager

URS Greincr, Inc.Contract No 68-W9-00'S4

ARCS EPA Region IXWA No. 54-27-9JZZ

Table of ContentsSection Page

1.0 Introduction .. 11.1 Apparent Problem 1

2.0 Site Description 22.1 Site Location 22.2 Site Description 22.3 Operational History 22.4 Regulatory Involvement 6

2.4.1 United States Environmental Protection Agency (EPA) 62.4.2 Gila River Department of Environmental Quality 62.4.3 Arizona Department of Environmental Quality 62.4.4 Agency for Toxic Substance and Disease Registry 72.4.5 Arizona Department of Health Services 72.4.6 Bureau of Indian Affairs 7

3.0 Investigative Efforts — 83.1 Previous Sampling 8

3.1.1 Soil Sampling 83.1.2 Air Sampling 11

3.2 EPA Sampling 123.2.1 Purpose and Description of Sampling Event..... 123.2.2 Deviations from Sampling Plan 133.2.3 Discussion of Sample Results 133.2.4 Enzyme Immunoassay Screening 14

4.0 Hazard Ranking System Factors 374.1 Sources of Contamination 374.2 Groundwater Pathway 37

4.2.1 Hydrogeologic Setting 374.2.2 Groundwater Targets 384.2.3 Groundwater Pathway Conclusions 39

4.3 Surface Water Pathway 394.3.1 Hydrologic Setting 394.3.2 Surface Water Targets ., 394.3.3 Surface Water Pathway Conclusions 39

4.4 Soil Exposure and Air Pathways 404.4.1 Physical Conditions 404.4.2 Soil and Air Targets 404.4.3 Soil Exposure and Air Pathway Conclusions 41

5.0 Emergency Response Considerations „ 42

6.0 Summary ~ 43

7.0 EPA Recommendations - 44

8.0 References ~ 45

List of FiguresFigure Page

2-1 Site Location Map 3

2-2 Facility Map 4

3-1 Sampling Zone Map 10

3-2 Sample Location Map: Gila River Indian Reservation 15

3-3 Sample Location Map: Yazzie HomeSite Area 16

3-4 Field Screening Location Map 17

3-5 Sample Location Map: Field Screening Locations Along Airstrip 18

3-6 Sample Location Map: South of the Yazzie Homesite Area 19

3-7 Toxaphene Concentration Map 36

List of TablesTable Page

3-1 Summary of Soil Sample Analysis for Toxaphene: Thomas Homesite.... 11

3-2 Results of Surface Soil Sampling for Organochlorine Pesticides:May 30 and 31, 1996 20

3-2 Results of Surface Soil Sampling for Organochlorine Pesticides:August 15, 1996 31

3-4 Results of Enzyme Immunoassay Screening for Toxaphene:August 15 and 16, 1996 34

4-1 Population Within 4 Miles of GRIR Site : 40

List of Appendices

A Contact Log and Contact Reports

B Site Observation Report

C Photo Log

D Latitude/Longitude Worksheet

E Laboratory Analytical Reports

f \ }_ \ \

1.0 Introduction

Under authority of the Comprehensive Environmental Response, Compensation, and Liability

Act of 1980 (CERCLA) and the Superfund Amendments and Reauthorization Act of 1986 (SARA),

the U.S. Environmental Protection Agency (EPA) has tasked URS Greiner, Inc. (URSG) to

conduct a Site Inspection (SI) of Gila River Indian Reservation located in Maricopa County,

Arizona.

The Gila River Indian Reservation was identified as a potential hazardous waste site and entered

into the Comprehensive Environmental Response, Compensation, and Liability Information

System (CERCLIS) on July 13, 1984 (1). On June 14, 1984, the EPA's Emergency Response Section

was contacted by the Gila River Department of Environmental Quality (GRDEQ) after soil

samples collected from the site indicated the presence of significant concentrations of

pesticides. A Preliminary Assessment (PA) was performed for the EPA in October 1985 by Roy

F. Weston, Inc. The purpose of the PA was to review existing information on the site and its

environs to assess the threats, if any, posed to public health, welfare, or the environment, and to

determine if further investigation under CERCLA/SARA is warranted. After reviewing the PA,

the EPA decided that further investigation of Gila River Indian Reservation would be necessary to

more completely evaluate the site using the EPA's Hazard Ranking System (HRS) criteria. The

HRS assesses the relative threat associated with the actual or potential releases of hazardous

substances from the site. The HRS is the primary method of determining if a site is eligible for

placement on the EPA's National Priorities List (NPL). The NPL identifies sites at which the EPA

may conduct remedial response actions. This SI report is the result of URSG's recent

investigation.

1.1 Apparent Problem

Surface soils at the Gila River Indian Reservation Site are suspected to be contaminated with the

Organochlorine pesticides Toxaphene, DDT, p, p-dichlorodiphenyl-dichloroethylene (DDE), and

DDD and the organophosphate pesticides s,s,s-tributyltrithiophosphate (DEF), ethyl parathion,

and methyl parathion. The amount and extent of pesticide contamination at the former

pesticide container disposal area and the suspected airstrip are unknown. These areas of

potential surface soil contamination represent sources from which further contaminant

migration may occur. Pesticide contamination in the yards of residences near the site may pose a

threat to the health of the residents.

URS Gr*in*r, Inc. Page 1

2.0 Site Description

2.1 Site Location

The Gila River Indian Reservation (GRIR) site is located approximately 10 miles southwest of

Phoenix, Arizona. The geographic coordinates of the site are 33° 19' 31" North latitude, and 112°

10' 14" West longitude, Township 1 South, Range 2 East, Section 20, Gila and Salt River Baseline

and Meridian (2). The site location is shown on Figure 2-1.

2.2 Site Description

The site occupies approximately 20 acres in a rural area. The site is bordered on the north by the

Gila River Indian Reservation boundary and agricultural land, on the west by a drainage canal, on

the south by a dirt road and agricultural land, and on the east by 51st Avenue.

Buildings now on-site include a double-wide mobile home, and dilapidated buildings.

Historically, buildings on-site included several wooden buildings that had a variety of uses. A

2,357-foot-long dirt airstrip, no longer in use, is present at the site. The presence of a second,

shorter airstrip is suspected (see Figure 2-2). A former pesticide container dumping area is

located east of the 2,357-foot-long airstrip (3). Several concrete-lined drainage ditches are

present on and around the site. Much of the site has been used for the dumping of construction

debris, furniture and appliances, and municipal waste. The site layout is presented on Figure 2-2.

2.3 Operational History

Mr. Bill Taylor, former site operator, stated that the airstrip was first used in 1959 by the Bill

Lewis Crop Dusting Service. The Bill Lewis Crop Dusting Service operated at the site for about 1

year. Between 1970 and 1973, the facility was operated by Taylor Flying Service. In 1973, the

Samply Flying Service of Parker, Arizona, purchased the Taylor Flying Service, and continued to

operate at the site until about 1975. In 1975, the Samply Flying Service relinquished the business

to Mr. Bill Taylor, who then operated the site until 1977. The site was leased by Hudson Farms,

Inc. from 1977 to 1978. The site continued to be used as a crop dusting service until the early

1980s. Historical photographs from 1980 and 1986 indicate that areas outside the airstrip were

recently used as irrigated farmland. Part of the site was leased in 1976 from the Bureau of Indian

Affairs (BIA) by Hudson Farms, Inc. (4).


Soupo«:USGS Topographic Maps, LaveenQuadrangle, Photorevised, 1973

URS Gr«in*r, Ino.100 California StreetSan Francisco. CA 94 111December 10, 1996

Site Location MapGila River Indian Reservation

Phoenix, Arizona

FIGURE

2-1

Container Disposal»Area

undisturbedcontaining nat

URS Greiner, Inc.100 California StreetSan Francisco, CA 94111

'• December 10,1996

Facility MapGila River Indian Reservation

• Phoenix, Arizona

FIGURE

2-2

The ownership of the site is r_-.iplex. The site location crosses seven allotments (5). Each

allotment is owned by one or more individuals and managed in cooperation with the Gila River

Indian Community and the BIA re_l estate office. The BIA real estate office approves of and

manages leases of the allotments (5, It is not known if areas used as the airstrip at the site were

leased by the crop dusting services.

Figure 2-2 shows the location of Me former pesticide container disposal area. The Gila River

Indian Community investigated < ic site in 1984 and found 50 to 100 empty 5-gallon pesticide

containers. Labels on the containers identified the following pesticides as having been used at

the facility: Azodrin, Toxaphene. methyl-parathion, Lannate-L, DEF-6, Ambush, Bolstar-6, and

Furadan G). Pesticides were J>..»pa ently stored in containers at the site; there is no evidence to

suggest that above-ground or underground storage tanks existed at the site. Empty pesticide

containers were removed from the dumpsite by Mr. Dave Hudson, of Hudson Farms, Inc., who

leased the site from 1977 to 1978 (4).

An emergency response action at the Thomas Homesite portion of the site was conducted by

the EPA Region IX Technical Assistance Team (TAT) (n 1984 (7). The jemetgjKicy response

included the excavation and removal of pesticide-contaminated sou, the chemical and biological

treatment of remaining contaminated soils, and the placement of a soil cap over an area of the

site known as the Thomas Homesite. The majority of prior sampling at the site has been

conducted at the Thomas Homesite and is described in Section 3.1.1. The EPA emergency

response was completed on December 8, 1986 (8).

There is little documentation available presenting the historical waste management practices at

the site. It is believed that most of the hazardous waste at the site was created by spills during the

mixing, loading, and handling of pesticides and herbicides before application to crops. During

the EPA emergency response at the site, buried pesticide containers were located within the

boundaries of the Thomas Homesite. Hazardous wastes excavated by the EPA during the

removal action at the Thomas Homesite were transported to and disposed of at the U.S. Ecology

facility located in Beatty, Nevada (9).

URS Gr*in*r, Ino. Page 5

2.4 Regulatory Involvement

2.4.1 U.S. Environmental Protection Agency

The GRIR site was entered into the CERCLIS databace on July 13, 1984 (1). The site is not listed inthe Resource Conservation and Recovery Informs ion System (RCRIS) database as of February 21,

1995.

The EPA began an emergency response at the Thomas Homesite on July 27, 1984 (10). The

emergency response included relocating Indian families living on-site, and excavating and

removing soils containing concentrations of 'oxaphene greater than 1,000 milligrams per

kilogram (mg/Kg). The remaining soil was chemically and biologically treated and a 6- to 15-inch

soil cap was placed over a portion of the site. The removal action was conducted in response to

an Immediate Removal Action Memorandum by on-scene coordinator Robert Millinaux and was

approved on July 31, 1984 (11).

2.4.2 Gila River Department of Environmental Quality

The Gila River Department of Environmental Quality (GRDEQ) has been involved with the site

since May 17, 1984. At that time, GRDEQ received a complaint from Mr. Joe Thomas regarding

pesticide soil contamination near his home. Mr. Charles Moses of the Gila River Indian

Community Pesticide Office conducted an inspection of the Thomas Homesite and discovered

empty pesticide containers. Mr. Moses collected soil samples to determine if pesticides were

present at the Thomas Homesite. Analysis of soil samples showed the soil was contaminated•

with Ethyl-Parathion, Methyl-Parathion, Toxaphene, and DEF (10). On June 14, 1984, the GRDEQ

contacted the EPA Region IX Emergency Response Section regarding the site to request Federal

assistance (12).

2.4.3 Arizona Department of Environmental Quality

The Arizona Department of Environmental Quality (ADEQ) has not been actively involved with

the investigations at the site. ADEQ does not maintain a file regarding the site.

URS Gr*in*r, (no. Page 6

2.4.4 Agency for Toxic Substance and Disease Registry (ATSDR)

The ATSDR reviewed the medical- and health-related aspects of the site, including results of

blood testing for cholinesterase from 14 of the residents of the site, at the time of the EPA

emergency response. Cholinesterase is a neurotransmitter found in the blood. Blood

cholinesterase levels can be lowered by organophosphate pes\: ;ides, which may result in health

problems (13). According to ATSDR, one adult and o-ie child had slightly depressed

cholinesterase levels, and two children had levels below 56 percent of the normal range. These

results could not be used to show a health effect after a presumed exposure to organophosphate

pesticides because there were no tests taken before the presumed exposure to compare with(14). ATSDR recommended periodic testing of serum cholincsterase levels of site residents.

2.4.5 Arizona Department of Health Services

The Arizona Department of Health Services (ADHS) has been involved with the site-since June

1984. At that time, representatives of ADHS conducted a survey of the site to supplement aerial

photographs taken by the EPA (15). The ADHS, along with the Indian Health Service, conducted

serum cholinesterase sampling and analysis from residents of the Thomas Site.

2.4.6 Bureau of Indian Affairs

The Bureau of Indian Affairs (BIA) has not been actively involved with the investigation of

pesticide contamination at the GRIR site. BIA, however, does keep a file regarding EPA activities

at the site, and has managed leases of the site property (6).

URS Gr*in*r, Ino. Page 7

\ j

)

> 3.0 Investigative Efforts

3.1 Previous Sampling

3.1.1 Soil Sampling

The emergency response action, begun on July 27, 1984, was limited t< a portion of the site

known as the Thomas Homesite. The emergency response action included relocating 19

persons who resided at the Thomas Homesite, and the excavation and removal of highly

contaminated soils. The remaining soils were chemically treated and the S;:e was capped with 6

to 15 inches of clean fill. Initial sampling of soils at the site indicated tibe pfestnce of Toxaphene *

at concentrations as high as 15,000 mg/Kg, as well as lesser concentration of 4,4'-DDE, methyl

parathion, ethyl parathion, and DEF (7). Toxaphene is considered the main contaminant of

concern at the site because it was found in higher concentrations in soil than other pesticides,

and it has a much longer half-life in soil than the organophosphate pesticides previously found at

the site, such as ethyl and methyl parathion, and DEF (16, 17, 18).

In September 1984, further sampling was conducted at the Thomas Homesite. During the

sampling event, 37 locations were sampled by the EPA TAT. Analysis indicated that soils at the

Thomas Homesite contained concentrations of Toxaphene at up to 14,100 mg/Kg, methyl

parathion at up to 8,280 mg/Kg, ethyl parathion at up to 5,830 mg/Kg, and DEF at up to 91.0

mg/Kg (7). Soil samples collected during this investigation were collected before the chemical

and biological treatment activities. Additional monitoring after chemical and biological

treatment, which occurred throughout 1984 and 1985, indicated significantly lower

concentrations of contaminants in soil at the Thomas Homesite (19).

On September 18, 1984, eight soil samples were collected near the airstrip outside of the Thomas

Homesite by OCM Incorporated for Hudson Farms, Inc. Soil samples were analyzed for the

presence of Toxaphene, ethyl parathion, and methyl parathion. Analytical results indicated the

presence of Toxaphene in all soil samples. The amounts of Toxaphene ranged from 3-19 mg/Kg

to 780 mg/Kg. Ethyl parathion was detected in one sample (designated 19776-5A) at 0.12 mg/Kg

(20).

The ereftftient of contaminated soil at the TTjomas HomeSite began to March 1985. The Thomas

Homesite was first tilled to a depth of 1.5 to 2.0 feet below ground surface (bgs) using a tractor

URS Gr«in«r, Ino. Page 8

and plow. The tilling was done to aerate the soil and create a uniform treatment zone. After the

soil tilling was completed, an underground sprinkler system was installed.

After tilling and installing the watering system, 35,000 pounds of sodium hydroxide were added

to the soil. Using a tractor with a fertilizer-spreading attachment, about 200 grams per square

foot were applied to the site. A plow and disc were used to mix the sodium hydroxide into the

soil.

'over 2"iSrjntfiSj During the treatment process, soil was

watered daily and turned weekly using a disc. Sampling results indicated a 45 percent reduction

inToxaphene concentrations after 69 days of treatment. This decrease was suspected to be due

primarily to dechlorination of the more complex components of Toxaphene.

Following the chemical treatment, the Thomas Homesite was then prepared for biological

treatment with anaerobic bacteria. Anaerobic bacteria cultures were applied to the Thomas

Homesite just prior to covering the site with between 6 and 18 inches of clean fill.

To monitor the effectiveness of the chemical and biological treatment of soil at the Thomas

Homesite, a series of soil samples was collected from nine separate sampling zones that were

established on the Thomas Homesite (see Figure 3-1). Sampling zone locations were established

based on geographic features (houses, trees, corrals, etc.) at the Thomas Homesite. Table 3-1

presents the results of analysis from soil samples collected between April 16, 1985 and March 21,

1986. Analytical results showed that chemical and biological treatment of soils significantly

reduced the amount of Toxaphene in each of the sampling zones.


«r

Not To Scale

URS Gr*in*r, Inc.100 California StreetSan Francisco. CA 94111November 1, 1996

Sampling Zone MapSamples Collected in 1985 and 1986

Gila River Indian ReservationPhoenix, Arizona

FIGURE

3-1

uTable 3-1

Summary of Soil Sample Analysis for ToxapheneThomas Homesite

Gila Indian Reservation(mg/Kg)

Zone

1

2

3

4

5

6

7

8

9

•4.

4/16/85

418

186

525

28.6

90.9

366

194

238

610

5/1/85

450

140

450

140

76.1

290

390

230

550

5/22/85

385

135

420

110

52.3

1,900

68

295

400

6/24/85

330

105

270

62

30.7

470

79.5

130

180

7/1/85

225

145

115

97.5

55.5

83

63

110

130

8/15/85

150

24

160

98

34

56

N/A

180

150

10/7/85

102

339

49-5

62.7

27.5

36.3

26.2

46.2

70.7

10/21/85

208

53

63

27

N/A

102

N/A

N/A

38

3/21/86

80.4

53.0

41.4

30.0

3.12

25.3

1.55

34.5

33X /^? S*^*Jf(i« Al*fJJ ' SltTO+S-AlOi* lAnt^Asjsf-st '/O —

On July 11, 1994, Mr. Adrian HendricKsVthe Pesticide Control Officer oT*the Department of Land

and Water Resources for the Gila River Indian Community, collected three soil samples from the

Yazzie Homesite. Soil samples analyzed by the Arizona State Agricultural Laboratory indicated

the presence of Toxaphene at up to 38 mg/Kg, and DDE at up to 1 mg/Kg. Soil samples were

collected from a depth of 3 feet bgs (21).

3.1.2 Air Sampling

In October 1985, three air samples were collected from the Thomas Homesite as part of an

ongoing monitoring program of contaminants at the site by the EPA. Of these three samples,

two were collected with charcoal tubes, and one sample was collected with an air filter. All

samples were analyzed for Toxaphene by a technique called gas chromatography.. Analysis of air

URS Grciner, Ino. Page 11

samples did not indicate the presence of Toxaphene in air at or above the analytical detection

limit of 0.002 milligrams per cubic meter (mg/m3) at the Thomas Homesite (22).

3.2 EPA Sampling

•Two sampling events were conducted by URSG for the EPA at the GRIR site. Surface soils were

collected during both sampling events. Samples were analyzed for Organochlorine and

organophosphate pesticides according to the Field Sampling Plan, and the Addendum to the

Field Sampling Plan (23, 24).

3.2.1 Purpose and Description of Sampling Event

Under the direction of the EPA, the URSG team prepared a Field Sample Plan and Field Sample

Plan Addendum to collect surface soils at and around the GRIR site (23, 24). This plan was

reviewed by the EPA's Quality Assurance Management Section and Planning and Assessment

Branch. The Sample Plan was approved by the EPA in August 1996.

Sampling of the GRIR site by URSG was conducted to identify the presence of Organochlorine or*

organophosphate pesticides in surficial soil and to determine the extent of surficial soil

contamination. Samples were collected from the site in May and August 1996.

A total of 58 surficial soil samples, including four duplicates and three background samples, were

collected from on- and off-site locations. Sample materials were collected using a dedicated

metal trowel and homogenized in a paper paint bucket, then placed into 8-ounce or 16-ounce

glass jars.

Before shipment to the laboratories, samples were custody-sealed, entered on a Chain-of-

Custody, double-bagged, and placed in a cooler with ice for shipment to laboratories. Samples.

collected during the sampling event were analyzed for Organochlorine pesticides by Contract

Laboratory Program Analytical Services (CLPAS), and for organophosphate pesticides? by RAP

methods. Data validation was conducted by Lockheed Martin's Environmental Services

Assistance Team.

The first soil sampling event was conducted on May 30 and 31, 1996. This sampling event

included the collection of 50 surface soil samples, including three duplicates and two background

samples. Samples were collected using a triangular grid system, in order to generate a more

representative data set given a defined number of sampling points. Three soil samples were

submitted as matrix spike duplicates. Of these 50 surface soil samples, five were collected from ;

the former Thomas Homesite, 20 were collected in a triangular grid pattern from areas south of

URS Greiner, Ino. Page 12

othe Thomas Homesite, three were collected from an area believed to have been used as an

airstrip, located south of both the Thomas Homesite and Yazzie Homesite, three were collected

from the former pesticide container disposal area, and eight were collected from along the

airstrip based on field screening results. One sample (SS-29) was collected near a well located

approximately one-quarter mile west of the site, and four samples were collected from a

residential area located east of 5ls Avenue (see Figures 3-2, 3-3, 3-4, and 3-5). Soil samples

collected from along the airstrip were selected based on the results of field screening using

enzyme immunoassay (EIA) test kits. LaJiQraiory confirmation samples w€re"£Mteaec> ftdfr lac

of Toxaphene, and two screening locations that indicated tow Toxaphene concentrations. *

The second soil sampling event wa? conducted on August 15, 1996. This sampling event included

the collection of eight soil samples, including one duplicate and one background sample. Soil

samples collected from the site were selected based on the results of field screening of 60

locations using enzyme immunoassay test kits. Field screening and sampling locations are

presented in Figure 3-6.

3.2.2 Deviations from Sampling Plan

URSG collected an additional five surficial soil samples from the Thomas Homesite portion of the

site as part of the first round of soil sampling. The additional soil samples were collected at the

request of the EPA Site Assessment Manager. These samples were collected from the soil cap

that was placed on the Thomas Homesite as part of EPA's emergency response action and were

designated SS-42 through SS-46.*

3.2.3 Discussion of Sample Results

Analytical results of soil samples collected from areas south of the Thomas Homesite showed the

presence of Organochlorine pesticides at levels greater than three times background

concentration (see Tables 3-2, 3-3, and 3-4, and Figure 3-7). Organophosphate pesticides were

not found at soils. Sampling results, in combination with EIA field screening results, indicate that

soils contaminated with Organochlorine pesticides have not migrated significantly from the

northeastern end of the airstrip, where it is believed that crop-dusting planes were fueled and

loaded with pesticides, and possibly washed. rToxaphene concentrations at the sue ranges from

not detectable to 830 pprrO Sampling results cannot be compared to prior sampling results,

either because samples were not collected from the same area, or clean, imported fill material

had been brought to the sampling location.

URS Gr*iner, Ino. Page 13

Lj )Data quality objectives established in the sample plan were generally met, although some minorinconsistencies in precision and accuracy did exist (23). Analytical data packages, includingexplanations of data qualifiers, can be found in Appendix E, Laboratory Analytical Reports.Overall, there was acceptable correlation between standard and duplicate samples.

3.2.4 Enzyme Immunoassay Screening

The enzyme immunoassay test is a colorimetr c test. The amount of Toxaphene in a given

sample is inversely proportional to the reading from a photometer: the greater the photometerreading, the less Toxaphene in the sample.

During the May 1996 Sampling Event, fu "d .creening results indicated concentrations ofToxaphene in excess of 100 ppm along the for Tier airstrip at the site, and near a well locatedsouthwest of the site. A portion of the field screening samples was not diluted prior to

immersion into the enzyme tube; therefore, the standards for comparison of these samples

represented 0.5, 2, and 10 ppm; whereas with the other samples, the standards represent 5, 20,and 100 ppm Toxaphene. This resulted in EIA results that were biased high. Nine soil sampleswere collected for laboratory confirmation of the field screening results. Laboratory results(presented in Table 3-2) indicated inaccuracies in the field screening results. Some uncertaintyregarding the results is present because the enzyme immunoassay test was conducted attemperatures exceeding the recommended 60 to 80°F (degrees Fahrenheit). Additionally,photometer results from prepared standards indicate a level of accuracy outside manufacturer-

specified control limits. All three standards were found to give absorbencies substantially higher

than the manufacturer's stated limits. It is not clear to what extent the high ambient temperature

(100°F) may have contributed to this. The manufacturer states that the kits are designed for an

operating range of 60 to 80°F; however, due to the standards falling outside the prescribed limits,

URSG regards the screening results as very qualitative.

During the August, 1996 Sampling Event, field screening results indicated limited concentrationsof Toxaphene in areas south of the Yazzie Homesite. The results of the field screening and

laboratory analysis for those samples sent for laboratory confirmation are presented in Table 3-4. Laboratory confirmation sampling indicates a poor correlation with field screening results;

however, field screening results may be used qualitatively.

URS Greiner, Inc. Page 14

Irrigation Ditch

= Grid Sampling Area

= Area field screened withconfirmation samples collectedbased on field screening results

• = Discrete sample point

Two soil samples for field screeningwere also collected from an areaapproximately 0.25 mile west of thesite near an agricultural well that mayhave been used as a pesticide-mixing area

e background SS-40-located approximately 0.5mile west of the site

e background SS-41located approximately 0.5mile east of the site D *• eSS-3

Yazzie Homesite

Not To Scale

URS Greiner, Ine.100 California StreetSan Francisco, CA 94111January 27,1997

Sample Location MapGila River Indian Reservation

Phoenix, Arizona

FIGURE

3-2

Airstrip

<?-.« •8"SS"-13*

is-19

Mobile^Home

/ SS-17 ^sa-ia /"^S^ S£05 SS-0

1 \ I \ / \ I/ \ I \ I

t \ I \ I\ I \ /ss>11 \ / \ i

®- (j£- SS-07 0 SS-03

\ / \ / \\ / \ /

/ \ / \ /

*£s£-18_ KS5."1i X. §?'1° \L _°^

\ ^ x // x / \ / \ / N /

/ v / \ / \ / \ f

/ ^ Yazzie/Homesite \ / \ \ /

/' N N / \/ • \ ' \ /

Thomas Homesite

151st AvenuNot To Seal*

URS Greiner, Ine.100 California StreetSan Francisco, CA 94111January 27, 1997

Sample Location MapYazzie Homesite Area


FIGURE

3-3

FS-24

O = Field Screening location

I

URS Greiner, Ine.100 California StreetSan Francisco, CA 94111January 27, 1997

Field Screening Location MapSouthwestern End of AirstripGila River Indian Reservation

Phoenix, Arizona

FIGURE I

3-4

Field Screening locations FS-26 and FS-27were located near a well approximately 0.25mile west of the southern end of the airstrip.

FS-2

lAirstripl

YazzieHomesite Not To Scale

URS Greiner, Ino.100 California StreetSan Francisco, CA 941 1 1January 27, 1997

Sample Location MapField Screening Locations Along Airstrip


FIGURE

3-5

Continue grid patternup to the dirt road.

_ _ ?18 ^fSlf4 ^fSi° -qf8:36 -QfS:32 ^ ps-28

/ X / \ I \ / x / \ X X/ X ' X / \ / \ / X / X

> X X / \ / \ X X X X

\ ' X / X / \ / X/ X '

' fsl°_ _ -^. L8!6 - _ -C/FS^2 - - - 'F&38. -N

/x/ x / x / \\ \ \ /°~X !\ / N

\ 'FS-SO \6SS-19' (collected

X / 5/96)v /

XFS-49

x / s ' N ' sX X X X

'FS-41 \XFS-37 v/PS'33

^ -H\ / X / X

v I \ ' \

> \ / x / • x xX / v / . /

FS-51

x

\ x \ x

x

q FS-29

' \\

(collected^ 5/96)•OSS-20

151st Avenue*Not To Scale

URS Grein.r, Ino.100 California StreetSan Francisco, CA 94111June 19, 1996

Sample Location MapSouth of the Yazzie Homesite Area


FIGURE

3-6

Table 5-2Gila River Indian Reservation

Results of Surface Soil Sampling for Organochlorine PesticidesMay 30 & 31, 1996

Concentrations in Micrograms per Kilogram (parts per billion)

AnalyteAlpha-BHCBeta-BHCDelta-BHCgamma-BrlC(Lindane)HeptachlorAldrinHepiachlorEpoxideEndosulfan 1Dieldrin4,4'-DDEEndrineEndosulfan II4,4'-DDDEndosulfansulfate4,4'-DDTMethoxychlorEndrin ketoneEndrin aldehydealpha -Chlordanegamma -ChlordaneToxapheneAroclor-1016Aroclor-1221Aroclor-1232Aroclor-1242Aroclor-1248Aroclor-1254Aroclor-1260

SS-117 U17 U17 U17 U

17 U17 U

1700 NJ

17 U1300 J4900

1700 U1700 U33 U

1700 U

1700 U1700 U33 U

1700 U17 U

1300 NJ

350000330 U680U330 U330 U330 U330 U330 U

SS-1D17 U17 U17 U17 U

17 U17 U

1400 NJ

17 U1000J

5300 NJ1700 U1700 U33 U

1700 U

1700 U1700 U33 U

1700 U17 U

1300 NJ

310000330 U680U330 U330 U330 U330 U330 U

SS-2170 U170 U170 U170 U

170 U170 U

310 NJ

170 U330 U67000860 NJ1400 NJ330 U1300

4400 U1700 U330 U330 U170 U

680 NJ

1200003300 U6800U3300 U3300 U3300 U3300 U3300 U

SS-3860U860U860U860U

860 U860 U860 U

860 U1700 U3700 NJ1700 U1700 U1700 U1700 U

1700 U8600 U1700 U1700 U1700 U

3900 NJ

310000 J17000 U34000 U17000 U17000 U17000 U17000 U17000 U

SS-42.0 U2.0 U2.0 U2.0 U

2.0 U2.0 U2.0 U

2.0 U3.9 U

250 NJ3.9 U91 NJ3.9 U36 NJ

260 NJ20 U3.9 U3.9 U2.0 U

36

660039 USOU39 U39 U39 U39 U39 U

RID

———

23,000

39,0002,3001,000

47,0003,900

—23,00047,000..._-..

39,000390,000

——...

___

...1,6001,6001,6001,6001,6001,6001,600

CSRC100360

—490

1403870

—401,900

——

2,700---

1,900

—— -

—...

— _ —

58083838383838383

Ta ,e 3-2Gila River Indian Reservation

Results of Surface Soil Sampling for Organochlorine PesticidesMay 30 & 31,1996


AnalyteAlpha-BHCBeta-BHCDelta-BHCgamma-BHC(Lindane)HeptachlorAldrinHeptachlorEpoxideEndosulfan IDieldrin4,4'-DDEEndirneEndosulfan II4,4'-DDDEndosulfansulfate4,4'-DDTMethoxychlorEndrin keioneEndrin aldehydealpha -Chiordanegamma -ChlordaneToxapheneAroclor-1016Aroclor-1221Aroclor-1232Arocior-1242Aroclor-1248Aroclor-1254ArocIor-1260

SS-0517 U17 U17 U17 U

17 U17 U

650 NJ

17 U930 NJ3600

1700 U1600 NJ240 NJ1700 U

33 U170 U33 U

1400 NJ17 U

1200

190000330 U670 U330 U330 U330 U330 U356 U

SS-062.1 U2.1 U2.1 U2.1 U

2.1 U2.1 U2.1 U

2.1 U4.1 U

2100 NJ1100NJ980 NJ520 NJ1100

4.1 LI640 NJ4.1 U

470 NJ2.1 U •

360 NJ

6900041 U83 U41 U41 U41 U41 U41 U

SS-0717 U17 U17 U17 U

17 U17 U

360 NJ

17 U900 NJ

2100 NJ440 NJ1000 NJ320 NJ

900

33 U170 U33 U33 U17 U

610

76000330 U680U330 U330 U330 U330 U330 U

SS-082.3 U2.3 U2.3 U2.3 U

2.3 U2.3 U2.3 U

2.3 U600 NJ2000 NJ1000 NJ960 NJ510 NJ

990

4.4 U23 U4.4 U660

2.3 U

420

6500044 U90U44 U44 U44 U44 U440

SS-0917 U17 U17 U17 U

17 U17 U

200 NJ

310 NJ96 NJ

1200 NJ1700 NJ1700 U33 U

1600 NJ

33 U2500 NJ

33 U130017 U

1100 NJ

250000330 U670 U330 U330 U330 U330 U330 U

RID

———

23,000

39,0002,3001,000

47,0003,900

—23,00047,000

—~~~

39,000390,000

—...

— — -

___

—1,6001,6001,6001,6001,6001,6001,600

CSRci100360

—490

1403870

—401,900

——

2,700

— — —

1,900—---

—"""

...

58083838383838383




AnalyteAlpha-BHCBeta-BHCDelta-BHCgamma-BHC(Lindane)HeptachlorAldrinHeptachlorEpoxideEndosulfan IDieldrin4,4'-DDEEndirneEndosulfan II4,4'-DDDEndosulfansulfate4,4'-DDTMethoxychlorEndrin ketoneEndrin aldehydealpha -Chlordanegamma -ChlordaneToxapheneAroclor-1016Aroclor-1221Aroclor-1232Aroclor-1242Aroclor-1248Aroclor-1254Aroclor-1260

SS-09D17 U17 U17 U17 U

17 U17 U

1700 U

17 U1200 NJ3000 NJ1700 U33 U33 U

1700 U

33 U170 U33 U

1700 U17 U

1400 NJ

470000330 U670 U330 U330 U330 U330 U330 U

SS-101.7 U1.7 U1.7 U1.7 U

1.7 U1.7 U1.7 U

1.7 U3.3 U930

3.3 U250 NJ

3.3250 NJ

3.3 U160

3.3 U17 U3.3 U '

160 J

1.7 U51 NJ1200033 U67 U33 U33 U33 U

SS-111.7 U1.7 U1.7 U1.7 U

1.7 U1.7 U

130 NJ

1.7 U3-3 U

1500 NJ520 NJ700 NJ3.3 U

350 NJ

1700 U760 NJ3-3 LJ180 NJ1.7 U

520

7800033 U67 U33 U33 U33 U33 U33 U

SS-121.7 U1.7 U1.7 U1.7 U

1.7 U1.7 U1.7 U

1.7 U3.3 U

903.3 U

8.9 NJ3.3 U3.3 U

3.3 U17 U3.3 U3.3 U1.7 U

1.7 U

79033 U67 U33 U33 U33 U33 U.33 U

SS-131.7 U1.7 U1.7 U1.7 U

1.7 U1.7 U1.7 U

1.7 U3.3 U790

3.3 U65 NJ3.3 U

22

3.3 U17 U3.3 U3.3 U1.7 LJ

21 NJ

480033 U67 U33 LJ33 U33 U33 LJ33 U

RID

——...

23,000

39,0002,3001,000

''7,0003.^3...

23,00047,000...

— - —

39,000390,000

...

...

— — —

— — —

—1,6001,6001,6001,6001,6001,6001,600

CSRC100360

—490

1403870

...40

l,9uO

—...2,700

-_-

1,900.........

— - —

*""**

58083838383838383

Tabic 3-2Gila River Indian Reservation



AnalyteAlpha-BHCBeta-BHCDelta-BHCgamma-BHC(Lindane)HeptachlorAldrinHeptachlorEpoxideEndosulfan 1Dieldrin4,4'-DDEEndirneEndosulfan II4,4'-DDDEndosulfansul fate4,4'-DDTMcthoxychlorEndrin ketoneEndrin aldehydealpha -Chlordanegamma -ChlordaneToxapheneAroclor-1016Aroclor-1221Aroclor-1232Aroclor-1242 .Aroclor-1248Aroclor-1254Aroclor-1260

SS-142.0 U2.0 U2.0 U2.0 U

2.0 U2.0 U2.0 U

2.0 U4.0 U1200

420 NJ430 NJ320 NJ220 NJ

4.0 U20 U4.0 U4.0 U2.0 U

200

3800040 U81 U40 U40 U40 U40 U40 U

SS-1517 U17 U17 U17 U

17 U17 U2900

17 U1600 NJ

33 U1700 LJ1700 U33 U

1700 U

1700 U1700 LJ33 U33 U17 U '

1700 U

830000330 U670 U330 U330 U330 U330 U330 U

SS-161.7 U1.7 U1.7 U1.7 U

1.7 U1.7 U1.7 U

1.7 U10 NJ160

3.3 LJ29 NJ21 NJ38 NJ

3-3 LJ17 U3.3 U22 NJ1.7 U

16

240033 LJ67 U33 U33 U33 U33 U33 U

SS-173-8

2.1 U2.6 NJ2.1 U

2.1 U2.1 U6.2 NJ

8.6 NJ35 NJ580

21 NJ48 NJ31 NJ160 NJ

4.1 U64 NJ15 NJ16 NJ

5.3 NJ

3-3 NJ

1100041 U83 LJ41 U41 U41 U41 U41 U

SS-17D3.4

2.4 NJ5.4 NJ

2.5

2.0 U2.0 U18 NJ

23 NJ130J

780 NJ530 NJ400 NJ250 NJ530 NJ

3.8 U270 NJ39 NJ50 NJ57 NJ

9.5 NJ

3900038U78 U38U38U38U38U38LJ

RtD

———

23,000

39,0002,3001,000

47,0003,900...

23,00047,000..."""

39,000390,000

...

...

...

...

—,600,600,600,600,600

1,6001,600

CSRC100360

490

1403870

...40

1,900......

2,700"•""• *'

1,900......

—...

""".

58083838383838383

Tabtc 3-2Gila River Indian Reservation



Analyte

Alpha-BHCBeta-BHCDella-BI 1Cgamma-BHC(Lindane)1 IcptachlorAldrinHeptachlorEpoxideEndosulfan 1Dieldrin4,4'-DDEEndirneEndosulfan II4/r-DDDEndosulfansulfatc4,4'-DDTMethoxychlorEndrin ketoneEndrin aldehydealpha-Chlordanegamma -ChlordaneToxapheneAroclor-1016Aroclor-1221Aroclor-1232Aroclor-1242Aroclor-1248Aroclor-1254Aroclor-1260

SS-18

1.8 U1.8 U1.8 U1.8 U

18U18U18U

7 2 N J13 NJ110

13 NJ42

88NJ35LJ

17 NJ18 U

35NJ35LJ31NJ

60NJ

700J35 U72 U35 U35 U35 U35 UJ5u

SS-19

17U17U17LJ17U

17LJ17U

10

21 NJ37 NJ

885938

31 NJ67 NJ

92 NJ17 U33LJ46 NJ -11 NJ

24 NJ

2600 J33 U68U33 U33 LJ33 U33 U33 LJ

SS-20

1.7 U17U17LJ1 7 U

17LJ17U1.7 U

1 7 U99NJ

5018

38 NJ33U12 NJ

26 NJ17 U33U33LJ1 7 U

93

760J33 LJ68 LJ33 U33 U33 U33 U33 U

SS-21(FS-16)1.7 U1 7 U17U1 7 U

1 7 U17LJ17LJ

1 7 L J3 3 U

5033LJ

2833U3 3 U

3 3 U17 U33LJ33U17U

17LJ

60033 LJ68 LJ33 U33 LJ33 U33 U33 U

SS-22(FS-17)1 7 U1 7 U1 7 L J1 7 L J

1 7 U17U20 NJ

40 NJ52 NJ62065 J160J51

77 NJ

94 NJ17 LJ16 NJ33LJ18 NJ

28 NJ

3100J33 LJ68 LJ33 U33 U33 U33 LJ33 U

RID

—...

—23,000

39,0002,3001,000

47,0003,900

—23,00047,000

——•• —

39,000'XJ.OOO...

—...

...

—1,6001,6001,6001,6001,6001,6001,600

CSRC

100360...

490

1403870

...40

1,900......

2,700"""

1,900—

i-""""""

""""

58083838383838383

Tab,.. 3-2Gila River Indian Reservation



Analyle

Alpha-BHCBeta-BHCDelta-BHCgamma-BHC(Lindane)HeptachlorAldrinHeptachlorEpoxideEndosulfan IDieldrin4,4'-DDEEndirneEndosulfan II4,4'-DDDEndosulfansulfate4, 4 '-DDTMethoxychlorEndrin ketoneEndrin aldehydealpha -Chlordanegamma -ChlordaneToxapheneAroclor-1016Aroclor-1221Aroclor-1232Aroclor-1242Aroclor-1248Aroclor-1254Aroclor-1260

SS-23(FS-18)2.0 U2.0 U

11 LNJ2.0 U

2.0 U2.0 U2.0 U

11 NJ23 NJ190

56 NJ96'

27 NJ15 LNJ

79 NJ20 U3.9 U3.9 U

6.8 L NJ

9.8 NJ

2700 J39 U79 U39 U39 U39 LJ.39 LJ39 LJ

SJ>-24(FS-19)1.7 U1.7 U1.7 U1.7 LJ

1.7 U1.7 U1.7 LJ

19 NJ9.0 NJ110056 NJ

180 NJ37 NJ79 NJ

340 J17 U51 NJ96 NJ -5.5 NJ

15 NJ

6400 J33 LJ67 U33 U33 U33 U33 U33 LJ

SS-25(FS-21)1.7 U1.7 U1.7 LJ1.7 U

1.7 U1.7 U1.7 U

1.7 U3.3 U3.3 U3-3 U3.3 LJ3.3 U3.3 U

3.3 U17 U3.3 U3.3 U1.7 U

1.7 U

170 U33 U67 U33 U33 U33 U33 U33 U

SS-26(FS-22)2.1 U2.1 LJ2.1 U2.1 U

2.1 LJ2.1 U2.1 U

2.1 U4.1 LJ

284.1 U4.1 U4.1 LJ4.1 U

4.1 U21 LJ4.1 U4.1 U2.1 U

2.1 U

210 U41 LJ84 LJ41 U41 U41 U41 U41 U

SS-27(FS-23)1.7 LJ1.7 U1.7 U1.7 U

1.7 U1.7 U1.7 LJ

1.7 LJ3.3 LJ

393.3 U12 NJ3.3 LJ3.3 U

3.3 U17 U3.3 LJ3.3 U1.7 U

1.7 U

420 J33 U67 U33 U33 U33 U33 U33 U

RID

...

...

—23,000

39,0002,3001,000

47,0003,900...

23,00047,000

—— — —

39,000390,000

—...•**•"

— — —

—1,6001,6001,6001,6001,6001,6001,600

CSRC

100360...

490

1403870

—40

1,900—

—2,700— — •»

1,900—...

—~~—

...

-* It83838383838383

/"*

Tabie 3-2Gila River Indian Reservation



Anaiyte

Alpha-BHCBeta-BHCDelta-BHCganima-BHC(Lindane)HeptachlorAldrinHeptachlorEpoxideEndosulfan IDieldrin4,4'-DDEEndirneEndosulfan II4,4'-DDDEndosulfansulfate4,4'-DDTMethoxychlorEndrin ketoneEndrin aldehydealpha -Chlordanegamma -ChlordaneToxapheneAroclor-1016Aroclor-1221ArocIor-1232Aroclor-1242Aroclor-1248Aroclor-1254Aroclor-1260

SS-28(FS-24)1.7 U1.7 U1.7 U1.7 U

1.7 U1.7 U1.7 U

1.7 U1.7 U110

3-3 LJ19

3.3 LJ3.3 U

3.3 U17 LJ3.3 LJ3.3 LJ1.7 U

1.7 U

490J33 U68U33 LJ33 U33 U33 U33 U

SS-29(FS-27)2.0 LJ2.0 U2.0 U2.0 LJ

2.0 U2.0 U2.0 LJ

2.0 U4.0 U110

4.0 LJ17

4.0 U4.0 U

4.0 LJ20 U4.0 U4.0 LJ •2.0 U

2.0 LJ

460 J40 U81 U40 U40 U40 U40 U40 U

SS-30

1.7 U1.7 U1.7 U1.7 U

1.7 U1.7 U1.7 LJ

1.7 U3-3 LJ

5.23.3 U6.8

3.3 U3-3 U

3.3 LJ17 U3.3 U3.3 U1.7 U

1.9

200J33 LJ68U33 U33 U33 U33 U33 U

SS-31

1.7 U1.7 LJ

121.7 U

1.7 U1.7 U44 NJ

120 NJ70 NJ1100

120 NJ330

65 NJ230 NJ

170 NJ17 U41 NJ110NJ58 NJ

88 NJ

6200 J33 LJ67 U33 U33 U33 U33 U33 U

SS-32

1.7 U1.7 U1.7 U1.7 U

1.7 LJ1.7 LJ10 NJ

1.7 U3.3 LJ

363-3 U

403-3 LJ

20

3.3 LJ17 LJ3-3 U3.3 U1.7 U

9.8 NJ

980J33 U67 U33 U33 U j33 U33 U33 U

R\b

——...

23,000

39,0002,3001,000

47,0003,900...

23,00047,000...

- — —

39,000390,000

...

—""*"

...

—1,6001,6001,6001,6001,6001,6001,600

CSRC1

100360...

490

1403870

...40

1,900

——

2,700...

1,900......

—"""""

...

58083838383fc: I8383

~ 3-2Gila River Indian Reservation



AnalyteAlpha-BHCBeta-BHCDelta-BHCgamma-BHC(Lindane)HeptachlorAldrinHeptachlorEpoxideEndosulfan IDieldrin4, 4 '-DDEEndirneEndosulfan II4,4'-DDDEndosullansulfate4,4'-DDTMethoxychlorEndrin kctoneEndrin aldehydealpha -Chlordanegamma -ChlordaneToxapheneAroclor-1016Aroclor-1221Aroclor-1232Aroclor-1242Aroclor-1248Aroclor-1254Aroclor-1260

SS-32 D2.1 U2.1 U2.1 1)2.1 U

2.1 U2.1 U19 NJ

10 NJ25 NJ

6725 NJ

922852

49 NJ21 U4.1 U29 NJ10 NJ

22 NJ

2200 J41 U84 U41 U41 U41 U41 U41 U

SS-331.7 U1.7 U1.7 U1.7 LJ

1.7 U1.7 U

11

20 NJ50 NJ280

57 NJ140

34 NJ3.3 LJ

54 NJ17 U14 NJ3.3 LJ

9.7 NJ •

22 NJ

2300 J33 U67 LJ33 LJ33 U33 U33 LJ33 U

SS-342.4

1.7 U1.7 LJ1.7 U

1.7 U1.7 U1.7 U

4.6 NJ8.9 NJ

30016 NJ56

5.7 NJ3.3 U

42 NJ17 U3.3 U3.3 LJ1.7 U

4.2 NJ

990J33 U67 U33 U33 U33 U33 U33 U

SS-352.5 NJ

.7U

.7LJ

.7U

.7U

.71)

.7LJ

11 NJ19 NJ300

23 NJ64

12 NJ3.3 U

42 NJ17 U3-3 LJ3.3 LJ1.7 U

10 NJ

990J33 U68U33 LJ33 U33 U33 U33 U '

SS-361.7 U1.7 U1.7 U1.7 U

1.7 U1.7 U1.7 LJ

1.7 U3.3 LJ

124.8 NJ

163.3 LJ3.3 LJ

4.8 NJ17 LJ3.3 U3.3 U1.7 U

1.9 NJ

350 J33 U67 LJ33 U33 U33 U33 U33 U

RID

———

23,000

39,0002,3001,000

47,0003,900~.

23,00047,000..."*"*•

39,000390,000

...

...

— — «

_ _ _

1,6001,6001,6001,6001,6001,6001,600

CSRd100360

—490

1403870

—401,900

——2,700

— — —

1,900........."""""

"*""

58083838383838383

3-2Gila River Indian Reservation



Analyte

Alpha-BHCBeta-BHCDelta-BHCgamma-BHC(Lindane)HeptachlorAldrinHeptachlorEpoxideEndosulfan 1Dieldrin4,4'-DDEEndirneEndosulfan 114,4'-DDDEndosulfansulfate4,4'-DDTMethoxychlorEndrin ketoneEndrin aldehydealpha -Chlordanegamma -ChlordaneToxapheneAroclor-1016Aroclor-1221Aroclor-1232Aroclor-1242Aroclor-1248Aroclor-1254Aroclor-1260

SS-37

1.8 U1.8 U1.8 U1.8 U

1.8 U1.881.8 U

1.8 U5.334

3.4 U19 NJ3.4 U3.4 U

4518 U3.4 U

131.8 U

3.6

91034U69 U34U34U34U34U34U

SS-38

1.7 U1.7 U1.7 U1.7 U

1.7 U1.7 U1.7 U

1.7 U3.3 U

613.3 U3.3 U3-3 U3.3 U

7.4 NJ17 U3.3 U3.3 U1.7 U

1.7 U

240 J33 U67 U33 U33 U33 U33 U33 U

SS-39

2.4 U2.4 U2.4 U2.4 U

2.4 U2.4 U2.4 U

2.4 U4.7 U

124.7 U8.9 NJ4.7 U4.7 U

2524 U4.7 U4.7 U2.4 U

2.4 U

53047 U96U47 U47 U47 U47 U47 U

SS-40background

1.7 U1.7 U1.7 U1.7 U

1.7 U1.7 U1.7 U

1.7 U3.3 U3.3 U3.3 U3.3 U3.3 U3.3 U

3-3 U17 U3-3 U3.3 U1.7 U

1.7 U

87 LJ33 U68U33 U33 U33 U33 U33 U

S&41background

2.3 U2.3 U2.3 U2.3 U

2.3 U2.3 U2.3 U

2.3 U4.5 U4.5 U4.5 U4.5 U4.5 U4.5 U

4.5 U23 U4.5 U4.5 U2.3 U

2.3 U

230 U45 U92 U45 U45 U45 U45 U45 U

RID

———23,000

39,0002,3001,000

47,0003,900

—23,00047,000

—— — «•

39,000390,000

...

—._.

-— •

—1,6001,6001,6001,6001,6001,6001,600

cMci

100360

—490

1403870

—401,900

——2,700->•*.

1,900

———~..

...

58083838383838383




AnalyteAlpha-BHCBeta-BHCDelta-BHCgamma-BHC(Lindane)HeptachlorAldrinHeptachlorEpoxideEndosulfan IDieldrin4,4'-DDEEndirneEndosulfan II4,4'-DDDEndosulfansulfate4,4'-DDTMethoxychlorEndrin ketoneEndrin aldehydealpha -Chlordanegamma -ChlordaneToxapheneAroclor-1016Aroclor-1221Aroclor-1232Aroclor-1242Aroclor-1248Aroclor-1254Aroclor-1260

SS-422.1 LJ2.1 U2.1 U2.1 U

2.1 U2.1 U2.1 U

2.1 U4.0 LJ

344.0 U5.0 NJ4.0 U4.0 U

2021 U4.0 U4.0 U2.1 U

2.1 LJ

49040 U82 U40 U40 U40 U40 U46 U

SS-431.7 LJ1.7 LJ1.7 U1.7 LJ

1.7 U1.7 LJ12 NJ

1.7 U3.3 U

280 NJ3.3 U62 NJ3.3 U3.3 U

120 NJ17 U3.3 U

485U '

23 NJ

380033 U68U33 LJ33 LJ33 U33 U33 U

SS-441.7 LJ1.7 U1.7 LJ1.7 U

1.7 LJ1.7 U1.7 U

1.7 U3.3 U

813.3 LJ10 NJ3.3 U3.3 U

15 NJ17 U3-3 LJ3.3 LJ1.7 U

1.7 LJ

74033 LJ68U33 LJ33 U33 U33 U33 U

SS-451.7 LJ1.7 U1.7 U1.7 LJ

1.7 LJ1.7 U69 NJ

30 NJ120

280 NJ340 NJ440 NJ210 NJ3-3 U

850 NJ510 NJ75 NJ150 NJ35 NJ

110NJ

1700033 U67 LJ33 LJ33 LJ33 U33 U33 U

SS-461.7 U1.7 U1.7 LJ1.7 U

1.7 LJ1.7 U1.7 LJ

1.7 LJ120

3.3 U17 NJ3.3 LJ3.3 LJ24 NJ

17 U3.3 U3.3 U1.7 LJ1.7 U

1100

33 U67 U33 LJ33 LJ33 U33 LJ33 U33 LJ

RID...

—...23,000

39,0002,3001,000

47,0003,900

—23,00047,000

—— — —

39,000390,000

—...***"""

•__

—1,6001,6001,6001,6001,6001,6001,600

CSRC100360...

490

1403870

—401,900...

—2,700

--•

1,900

—......

«•— —

-•-

58083838383838383

Notes:RfD Reference Dose Screening Concentration

CSRC Cancer Risk Screening Concentration

U The analyte was analyzed for, but was not detected above the reported sample quantitation limit.

L The results fall below the Contract Required Quantitation Limit. Results are estimated and are consideredqualitatively acceptable but quantitatively unreliable due to uncertainties in the analytical precision near the limitof detection.

R The sample results are rejected due to serious deficiencies in the ability to analyze the sample and meet qualitycontrol criteria. The presence or absence of the analyte cannot be verified.

LJJ The analyte was not detected above the reported sample quantitation limit; however, the reported quantitationlimit is approximate and may or may not represent the actual limit of quantitation necessary to accurately andprecisely measure the analyte in the sample.

J The analyte was positively identified; the associated numerical value is the approximate concentration of theanalyte in the sample.

NJ Hie analysis indicates the presence of an analyte that has been "tentatively identified" and the associatednumerical value represents its approximate concentration.

NO QUALIFIERS indicate that the data are acceptable both qualitatively and quantitatively.

3-3Gila River Indian Reservation

Results of Surface Soil Sampling for Organochlorine PesticidesAugust 15, 1996

Concentrations in Micrograms per Kilogram (parts pc. ^'"-r-j)

Analyte

Alpha-BHCBcta-BI 1CDelta-BHCgamma-UrlC(Lindane)HeptachlorAldrinHeplachlorEpoxideEndosulfan 1Dieldrin4,4'-DDEEndirneEndosulfan II4,4'-DDDEndosulfansullate4, 4 '-DDTMethoxychlorF.ndrin ketoneEndrin aldehydealpha -Chlordanegamma-ChlordaneToxapheneAroclor-1016Aroclor-1221Aroclor-1232Aroclor-1242Aroclor-1248Aroclor-1254ArocIor-1260

SS-1(FS-28)

3.91.8NJ

2.01.5 NJ

1.7 U1.7 U1.7 U

1.7 LJ3.3 LJ260

9.9 NJ3.3 U3.3 LJ

12

30 NJ17 U3.3 LJ3.3 LJ1.7U

1.7 LJ

370 J33 LJ68U33 LJ33 U33 U33 LJ

. i3U

SS-1D(FS-28)

3.61.6 NJ

1.81.4 J

1.7 U1.7 U1.7 U

1.7 U3.3 U230

5.0 NJ3.3 U13 NJ

2.9 NJ

20 NJ17 LJ

2.6 NJ3.3 U •1.7 U

1.7 LJ

100 J33 LJ66U33 U33 U33 U33 LJ33 U

SS-2(FS-30)

2.11.7 U1.6NJ1.7 U

1.7 U1.7 U1.7 LJ

2.4 NJ3.3 LJ180 NJ43 NJ3-3 U3.3 U

49

45 NJ17 U16 NJ3.3 LJ1.7 U

6.7 NJ

1400 J33 U66U33 LJ33 U33 U33 LJ33 U

SS-3(FS-33)

2.01.7 LJ1.4 NJ1.7 LJ

1.7 U1.7 LI1.7 LJ

1.7 U3.2 U180

14 NJ3.2 U3.2 U3.2 U

19 NJ17 U

4.9 NJ12 NJ1.7 U

3-6 NJ

390 J32 U66LJ32 U32 U32 U32 U32 U

SS-4(FS-37)8.4 U8.4 U8.4 LJ8.4 LJ

8.4 U8.4 U8.4 LJ

8.4 LJ16 LJ260

48 NJ16 LJ16 U16 U

84 U16 LJ16 U

8.4 LJ8.4 LJ

1500 J

160 U330 LJ160 LJ160 U160 U160 LJ160 LJ160 LJ

RtD

———

23,000

39,0002,3001,000

47,0003,900...

23,00047,000...-"""

39,000390,000

...

—— • —

--"*

—1,6001,6001,6001,6001,6001,6001,600

CSRC

100360...490

1403870

...40

1,900...

—2,700...

1,900......

—...

"""*

58083838383838383


Results of Surface Soil Sampling for Organochlorine PesticidesAugust 15, 1996


Analyte

Alpha-BHCBeta-BHCDelta-BHCgamma-BHC(Lindane)HeptachlorAldrinHeptachlorF.poxideEndosulfan IDieldrin4,4'-DDEEndirneEndosulfan 114,4'-DDDEndosulfansulfate4, 4 '-DDTMethoxychlorEndrin ketoneEndrin aldehydealpha -Chlordanegamma -ChlordaneToxapheneAroclor-1016Aroclor-1221Aroclor-1232Aroclor-1242Aroclor-1248ArocIor-1254Aroclor-1260

SS-5(FS-38)8.4 U8.4 U8.4 U8.4 U

8.4 LJ8.4 U8.4 U

8.4 U16 U110

16 U16 LJ16 U16 U

16 U84 U16 U16 U8.4 U

8.4 U

390J160 U330 U160 LJ160 U160 U160 LJ160 LJ

SS-6(FS-70)1.7 U1.7 U.7U.7U

.7LJ

.7LJ

.7U

1.7 U3.2 U

4.5 NJ2.3 NJ5.9 NJ4.3 NJ3.7 NJ

1.6NJ17 U3-2 U3.2 U •1.7 LJ

1.7 U

69 J32 U68U32 U32 U32 U32 LJ32 U

SS-7background

1.7 U1.7 U1.7 U1.7 U

1.7 U1.7 U1.7 U

1.7 U3.3 LJ3.3 LJ3.3 LJ3.3 U3.3 LJ3.3 LJ

3.3 LJ17 U3.3 LJ3-3 LJ1.7 LJ

1.7 LJ

170 U33 U66 U33 U33 LJ33 U33 LJ33 U

RID

———

23,000

39,0002,3001,000

47,0003,900...

23,00047,000

—— -

39,000390,000

—

—

---

—1,6001,6001,6001,6001,600.1,6001,600

CSRC

100360

—490

1403870

—401,900......

2,700

1,900...

——~"

•"""

58083838383838383

Notes:RfD Reference Dose Screening Concentration

CSRC Cancer Risk Screening Concentration

U The analyte was analyzed for, but was not detected above the reported sample quantitation limit.

L The results fall below the Contract Required Quantitation Limit. Results are estimated and are consideredqualitatively acceptable but quantitatively unreliable due to uncertainties in the analytical precision near the limitof detection.

R The sample results are rejected due to serious deficiencies in the ability to analyze the sample and meet qualitycontrol criteria. The presence or absence of the analyte cannot be verified. >.*

UJ The analyte was not delected above the reported sample quantitation !;.«„; ! -•> ever, the reported quantitationlimit is approximate and may or may not represent the actual limit of quantitation necessary to accurately andprecisely measure the analyte in the sample.

J The analyte was positively identified; the associated numerical value is the approximate concentration of theanalyte in the sample.

NJ The analysis indicates the presence of an analyte that has been "tentatively identified" and the associatednumerical value represents its approximate concentration.

NO QUALIFIERS indicate that the data are acceptable both qualitatively and quantitatively.

Table 3-4Results of Enzyme Immunoassay Screening for Toxaphene

Gila River Indian Reservation SiteMaricopa County, Arizona

August 15 & 16, 1996

Sample Location

FS-281

FS-29FS-301

FS-31FS-32FS-331

FS-34FS-35FS-36FS-371

FS-381

FS-39FS-40FS-41FS-42FS-43FS-44FS-45FS-46FS-47FS-48FS-49FS-50FS-51FS-52FS-53FS-54FS-55FS-36FS-57FS-58FS-59FS-60FS-61FS-62FS-63FS-64FS-65

Tentative ToxapheneConcen ration (ppm)

-.0 to 1005 to 20

20 to 100Oto53 to 203 to 20 '5 to 205 to 205 to 205 to 205 to 205 to 205 to 205 to 205 to 20Oto 5O t o 5O t o 5O t o 5O t o 5O t o 5Oto5Oto5Oto5O t o 5O t o 5Oto50 to 5Oto5Oto5Oto5Oto5Oto5Oto 50 to 5Oto 5Oto 5Oto 5

Laboratory ToxapheneResult (ppm)0.370 J /0. 100 J

1.400J

0.390 J

0.160 U0.390 J

(. \

Table 3-4 (Continued)Results of Enzyme Immunoassay Screening for Toxaphene

Gila River Indian Reservation SiteMaricopa County, Arizona

August 15 & 16, 1996

Sample Location

FS-66FS-67FS-68FS-69

FS-701

FS-71FS-72

FS-73FS-74

FS-75FS-76FS-77FS-78FS-79FS-80FS-81FS-82

FS-83FS-84FS-85FS-86FS-87

Tentative ToxapheneConcentration (pp n)

Oto 5Oto 5Oto 5Oto 5Oto 5Oto 5Oto 5Oto 5Oto 5Oto 5Oto 5Oto 5Oto 5Oto 5Oto 5Oto 5Oto 5Oto 5Oto 5Oto 5Oto 5Oto 5

Laboratory ToxapheneResult (ppm)

0.069 J

•

1 - Sample sent for laboratory conformation.

U - Not detected, method detection limit shown.

J » The results are estimated and the data are valid for limited purposes; results arequalitatively acceptable.

Legend

• Soil sampling locationSS-44 Sample location

designation

31' /Toxaphene 'concentration andjduplicateconcentration Iin mg/Kg

SS-09 ^SS-05 SS-01\(250/470) / (190) (350/31 )) J

\ . x ,\ / \ / I

\ ' X 'SS;1§_ lm^B±n ^ /cc ™ X *

Vx Yazzie, Homesite x

URS Gr«in*r, Ine.100 California StreetSan Francisco, CA 94111January 27, 1997

Toxaphene Concentration MapConcentrations in mg/Kg or ppm

Yazzie Homesite AreaGila River Indian Reservation

Phoenix. Arizona

FIGURE

3-7

4.0 Hazard Ranking System Factors

The Hazard Ranking System (HRS) is a scoring system used to assess the relative threat associated

with actual or possible releases of hazardous substances from sites. It is the principal

mechanism the EPA uses to place sites on the National Priorities List (NPL). URSG has evaluated

the HRS factors discussed belo^,, which are relative to this site.

4.1 Sources of Contamination

Sources of contamination at tl ? Gila River Indian Reservation site are limited to contaminated

soil. Analysis of surface oil samples for organophosphate pesticides did not show their

presence. Analysis of surficial soil samples for Organochlorine pesticides showed the presence

of delta hexachlorocyclohexane at up to 12 micrograms per kilogram (|ig/Kg), heptachlor

epoxide at up to 2,900 ug/Kg, endrine at up to 1,700 ug/Kg, endosulfan I at up to 310 ug/Kg,

endosulfan II at up to 1,600 Mg/Kg, endosulfan sulfate at up to 1,600 ug/Kg, gamma chlordane at up

to 3,900 Jig/Kg, methoxychlor at up to 2,500 ug/Kg, endrine at up to 1,700 Mg/Kg, endrin aldehyde

at up to 1,400 ug/Kg, Dieldrin at up to 1,600 ug/Kg, 4.4'-DDE at up to 67,000 Ug/Kg, 4,4'-DDD at

up to 520 ug/Kg, 4,4'-DDT at up to 850 ug/Kg, and Toxaphene at up to 830,000 ug/Kg.

Concentrations of the above-mentioned Organochlorine pesticides are greater than three times

background concentrations. Concentrations of heptachlor epoxide, Dieldrin, 4,4'-DDE, and

Toxaphene were found in excess of their -respectsre :GlgC|f ,Rlak Screening Concentrations

(CRSC). An exposure to a contaminant present at or above the CRSC provides a Y In one million

chance that an individual will develop cancer due to this exposure! Concentrations of heptachlor

epoxide were detected in excess of the Reference Dose Screening Concentration (RfD). The RfD

is an estimate of a daily exposure level of a substance to a human population below which

adverse noncancer health effects are not anticipated. If contaminant concentrations are greater

than the CRSC or RfD benchmark concentrations, and are present at concentrations greater than

three times background concentrations, the HRS assigns "level 1" contamination of resident

individuals. Assigning level 1 contamination of resident individuals increases the HRS score for a

given site. Surface soil sampling indicates that Toxaphene is the most widely distributed

contaminant at the site, with average concentrations of 196,000 ug/Kg within the Yazzie Homesite

area. With the exception of the sample collected at location SS-10, all soil samples collected

from the Yazzie Homesite area were greater than the CRSC for Toxaphene of 580 ug/Kg.

URS Greiner, Ino. Page 57

4.2 Groundwater Pathway

4.2.1 Hydrogeologic Setting

The Gila River Indian Reservation site is located within the Basin and Range geomorphic

province. This province is characterized by fault-block uplifting, graben downthrowing, and

erosional deposition. The site is located in a depositional environment, receiving materials from

South Mountain, a small but typical mer morphic core complex, centered with light-colored

granite and surfaced with a sheared, arched carapace of metamorphic rock. The net annual

precipitation for the Phoenix area is approximately 0.5 inch (25). Surficial soils at the site are

thinly developed and composed of alluvial deposits of sandy clays or clayey sands with some

gravel. The approximate depth to groundw- ter in the site vicinity is 90 feet bgs (26).

The GRIR site is located in the West Salt River Valley subbasin of the Phoenix Active Management

Area, created by the Arizona Groundwater Management Act of 1980 (27). According to the well

log from the Gila Crossing Day School Well, located between 3 and 4 miles from the site, the

subsurface consists of approximately 360 feet of sand and gravel underlain by approximately 560

feet of clay and sandy clay layers with some shale, and a granite bedrock, located approximately

920 feet bgs (28).

4.2.2 Croundwater Targets

There are four drinking water wells located within 4 miles of the site. These drinking water wells

are designated as the District 6 North Well, District 6 South Well, the New Gila Crossing Well, and

the Gila Crossing Day School Well. Wellhead Protection Areas have been established at each of

these wells; however, the site is not located within any Wellhead Protection Area (26).

The District 6 North Well, located approximately 0.75 mile from the site, is the drinking water

well nearest the site. The District 6 South Well is located approximately 1.25 miles from the site.

The District 6 North and District 6 South wells provide drinking water to approximately 2,500

people through a blended water system (26). Both the District 6 North and District 6 South wells

are located hydrologically upgradient of the site (29). The District 6 South Well extends to 620

feet bgs, and is screened from 540 to 615 feet bgs (26). The exact screened interval of the

District 6 North well is not known; however, based on its total depth of 634 feet, it is believed to

have a screened interval similar to thru of the District 6 South Well.

The New Gila Crossing Well and the Gila Crossing Day School Well are located between 3 and 4

miles from the site. The New Gila Crossing Well is screened between 350 to 390 feet bgs and 820


\to 980 feet bgs (26). The New Gila Crossing Well suppli : drinking water to approximately 2,500

people. The Gila Crossing Day School Well is screened between 905 and 925 feet bgs and

supplies drinking water to approximately 2,500 people (2"). Both the New Gila Crossing Well

and the Gila Crossing Day School Well are located upgradient of the site, based on information

received from the Gila River Indian Community.

Several inactive irrigation wells are also located within 4 miles of the site. One groundwater

sample was collected from an agricultural well located n^ar the airstrip on June 21, 1984 by Mr.

Charles Moses of the Gila River Indian Community Pesticide Program. Analysis of this

groundwater sample did not indicate the presence of pesticides. According to Mr. Pete Overton

of the Bureau of Indian Affairs, samples of groundwater collected from these irrigation wells by

Mr. Lee Ballard have indicated the presence of DDT G'O. Laboratory data sheets were not

available to confirm the presence of DDT.

4.2.3 Groundwater Pathway Conclusions

The groundwater pathway is not the primary pathway of concern at the GRIR site.

Organochlorine pesticides detected at the site sorb readily to soil particles and are not highly

soluble or mobile. Groundwater wells within 4 miles of the site supply drinking water to

approximately 7,500 people.

4.3 Surface Water Pathway

4.3.1 Hydrologic Setting

The GRIR site is located within the Basin and Range geomorphic province. This province is

characterized by fault-block uplifting, graben downthrowing, and erosional deposition. The site

is located in a depositional environment, receiving materials from South Mountain, a small but

typical metamorphic core complex, centered with light-colored granite and surfaced with a

sheared, arched carapace of metamorphic rock. The annual net precipitation for the Phoenix

area is approximately 0.5 inch (25). Surficial soils at the site are thinly developed and composed

of alluvial deposits of sandy clays or clayey sands with some gravel. The approximate depth to

groundwater in the site vicinity is 90 feet bgs (26).

Stormwater flowing from the site travels in a southerly direction through lined and unlined

irrigation ditches. These irrigation ditches terminate approximately 0.75 mile south of the site.

From the end of the irrigation ditches, surface water is assumed to flow as sheet-flow to the

southwest, toward the Gila River, located approximately 2.5 miles from the site. The Gila River is

URS Grciner, Inc. Page

highly managed and flows only after rainfall events. The 2-year, M-hour rainfall for the site

vicinity is approximately 1.5 inches (3D- The site is located in an area above the 500-year

floodplain (32). Groundwater flow at the site is believed to be toward the northwest, based on

State of Arizona Department of Water Resources information (27).

4.3.2 Surface Water Targets

Surface water downstream of the site is not used as a source of drinkir g water, as a fishery, or as

habitat for sensitive environments (33). Surface water downstrean. of the site is not used to

irrigate farmland, water livestock, or as a recreational water body.

4.3.3 Surface Water Pathway Conclusions

The surface water pathway is not a pathway of concern at the GRIR s te. There are no uses of

surface water flowing from the site.

4.4 Soil Exposure and Air Pathways

4.4.1 Physical Conditions

The GRIR site is located in an agricultural/residential area approximately 10 miles southwest of

Phoenix, Arizona. A residential area is located directly east of 51st Avenue, approximately 100

feet from the site. Access to the site is not restricted in any way. There are a few barbed-wire

fences surrounding the site; however, these fences are in a state of disrepair and do not restrict

access to the site. The entire site is approximately 20 acres and is relatively flat. The surface soil

at the site consists of sandy clays with some gravel. The site is sparsely vegetated (34).

As stated in Section 4.1, and detailed in Table 3-2 and Figure 3-7, soil at the GRIR site has been

found to contain concentrations of Toxaphene and other Organochlorine pesticides at amounts

greater then three times background concentrations, and above health-based benchmark

concentrations, including the CRSC and RfD. Of the four samples collected near residences

located east of 51st Avenue, one sample, SS-37, contained Toxaphene concentrations in excess of

the CRSC and greater than three times background concentrations.

4.4.2 Soil and Air Targets

Prior to July 1994, there were three residents located on-site. These residents moved from the

site when they began to have health problems and became concerned about the potential

presence of pesticides at the site. There are currently no residents at the site (34).

URS Grcincr, Inc. Page 40

There are no workers at the site, and the site is not currently used for commercial silviculture,

commercial agriculture, or commercial livestock production. The site does not ptovide habitat

for Federally or State-protected species. The site is used by the local community 35 evidenced

by recent graffiti and trash at the site (34). Areas adjacent to the site consist of native desert flora,

protected by the State of Arizona Desert Protection Act.

There are an estimated 127 people living within 1 mile of the Gila River Indian Reservation site.

Approximately 20 people live within 0.25 mile of the site, and of those 20, approximately five

people live within 200 feet of areas with Toxaphene contamination. Population within 4 miles of

the site is presented in Table 4-1 (2, 35, 36).

Table 4-1Population Within 4 Miles of The GRIR Site

Distance (miles)0 to 0.25

0.25 to 0.50.5 to 11 to 22 to 33 to 4

Total Population

Population201295280475

1,1001,982

4.4.3 Soil Exposure and Air Pathway Conclusions

*

The Soil Exposure Pathway is the primary pathway of concern at the GRIR site. Soil sampling

conducted as part of this Site Inspection indicates the presence of Organochlorine pesticides in

surficial soils at concentrations exceeding background and benchmark concentrations. Air

sampling, conducted in October 1985, did not show the presence of contaminants in ambient air

(22). Prior to July 1994, there were three residents located on-site. Currently, there are

approximately 127 people living within 1 mile of the site, approximately five of which live within

200 feet of areas with Toxaphene contamination.

URS Grcincr, Ino. Page 41

5.0 Emergency Response Considerations

The National Contingency Plan [40 CFR 300.415 (b) (2)1 authorizes the Environmental Protection

Agency to consider emergency response actions at those sites which pose an imminent threat to

human health or the environment. For the following reasons, a referral to the EPA's Region IX

Emergency Response Section does not appear to be necessary:

• The site does not present the risk of fire or explosion.

• The EPA removal action of July 1984 included the excavation and removal of highlycontaminated soil, and the treatment and capping of less-contaminated soils.

• Concentrations of contaminants in soils at the site do not present a significant risk tothe drinking water aquifer because of the depth to the drinking water aquifer, and thecharacteristic of site contaminants to bond strongly to soil particles.

• Hazardous substances are no longer in use, and therefore are no longer being releasedto the environment at the site.

URS Gr«in«r, Ino. Page 42

6.0 Summary

The Gila River Indian Reservation (GRIR) site is located approximately 10 miles southwest of

Phoenix, Arizona. The site occupies approximately 20 acres in a rural area. The site is bordered

on the north by the Gila River Indian Reservation boundary and agricultural land, on the west by a

drainage canal, on the south by a dirt road and agricultural land, and on the east by 51st Avenue.

The site was used by agricultural aviation services (crop dusters) between 1959 and the early

1980s. In 1984, the EPA conducted an emergency response action at the site which included the

relocation of site residents, the removal of wastes from a portion of the site, the chemical and

biological treatment of contaminated soils at a portion of the site, and capping a portion of the

site.

Surficial soil sampling conducted in May and August 1996 has indicated the presence of delta

hexachlorocyclohexane at up to 12 micrograms per kilogram (ug/Kg), heptachlor epoxide at up

to 2,900 ug/Kg, endrine at up to 1,700 Mg/Kg, endosulfan I at up to 310 Mg/Kg, endosulfan II at up

to 1,600 Mg/Kg, endosulfan sulfate at up to 1,600 Mg/Kg, gamma chlordane at up to 3,900 ug/Kg,

methoxychlor at up to 2,500 Mg/Kg, endrine at up to 1,700 Mg/Kg, endrin aldehyde at up to 1,400

Mg/Kg, Dieldrin at up to 1,600 Mg/Kg, 4,4'-DDE at up to 67,000 Mg/Kg, 4,4'-DDD at up to 520

Mg/Kg, 4,4'-DDT at up to 850 Mg/Kg, 'ir>d Toxaphene at up to 830,000 Mg/Kg- Concentrations of

heptachlor epoxide, Dieldrin, 4,4'-DDE, and Toxaphene were detected in amounts greater than

their respective Cancer Risk Screening Concentrations (CRSC). Concentrations of heptachlor

epoxide were detected in excess of the Reference Dose Screening Concentration (RfD). Surface

soil sampling indicates that Toxaphene is the most widely distributed contaminant at the site,

with average concentrations of 196,000 Mg/Kg within the Yazzie Homesite area. With the

exception of the sample collected at location SS-10, all soil samples collected from the Yazzie

•Homesite area were greater than the CRSC for Toxaphene.

The following are pertinent HRS factors associated with the site:

• There are four drinking water wells located within 4 miles of the site, which serveapproximately 7,500 people.

• Shallow groundwater is located approximately 90 feet below ground surface.

• There are an estimated 127 people living within 1 mile of the site.


n \R ^DIAL SITE ASSESSMENT DECISION - EP iCION IX

sShe Name: Cila River Indian Reservation EPA ID #: AZD981621881

Alias Site Names: None

City: Phoenix County or Parish: Maricopa County State: AZ

Refer to Report Dated: April 23. 1997 Report Type: CERCLA Site Inspection

Report Developed By: URS Greiner. Inc.

DECISION:

GET" 1. Further Remedial Site Assessment under CERCLA (Superfund) is not required because:

ET 1 a. Site does not qualify for further remedial site assessment under CERCLA (No Further Action- NFA) and:

D EPA is retaining this site in CERCLIS because the Federal Superfund program still has aninterest in the site.

D EPA is archiving this site in CERCLIS because it does not warrant Federal Superfund action,or an appropriate Federal Superfund response action has been completed. This meansthat EPA believes no further Federal Superfund response is appropriate. Archived sitesmay be returned to the CERCLIS site inventory if new information necessitating furtherFederal Superfund consideration is discovered.

D 1 b. Site may qualify for further action, but is deferred to: D RCRA D NRC

D 2. Further Assessment Needed Under CERCLA D 2a. (optional) Priority: D Higher D Lower

D 2b. Activity Type: D PA D SI D ESI D HRS EvaluationD Other

DIJUSSION/RATIONALE:

Report Reviewed and Approvand Site Decision Made by:

Project M«nj emen«.A\EPA Form f 9100-3 Rev. O6

Boundary Site Site Investigation Report, GRIG, Arizona. Prepared by the GRIGDepartment of Environmental Quality. April 3, 2002. - this report is currently beingphotocopied in the comm center - 2/23/04.

Documents

CERCLA site inspection rptThe Gila River Indian Reservation (GRIR) site is located approximately 10 miles southwest of Phoenix, Arizona. The geographic coordinates of the site are