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OEL NORTE COUNTY PESTICIDE STORAGE AREA SITE

REMEDIAL INVESTIGATION

September 13, 1985

FINAL REPORT

1 E S C I

US. EPA CONTRACT NO 68-01-6939

/:-,v ••

ROY F. WESTON, INC. WOODWARD-CLYDE CONSULTANTS

CLEMENT ASSOCIATES, INC. ICFINCORPORATED

C. C. JOHNSON & ASSOCIATES, INC.

I O5Cj-()0HZ<Z \ I V . . . . ^

r

SFUND RECORDS CTR

88032757 i l V

AR0238 DEL NORTE COUNTY

PESTICIDE STORAGE AREA SITE REMEDIAL INVESTIGATION

September 13, 1985

FINAL REPORT

Prepared by

Woodward-Clyde Consultants One Walnut Creek Center

100 Pringle Avenue Walnut Creek, CA 94596

101-RI2-EP-BAXU-4

CDM environmental engineers, scientists, planners. & management consultants

October 4, 1985

CAMP DRESSER & McKEE INC.

7630 Little River Turnpike, Suite 500 Annandale, Virginia 22003 703 642-5500

Mr. Keith Takata Regional Project Off icer U.S. Environmental Protect ion Agency Region IX 215 Fremont Street San Francisco, Cal i fornia 94105

Ms. Michele Dermer Regional Site Project Off icer U.S. Environmental Protect ion Agency Region IX 215 Fremont Street San Francisco, Cal i fornia 94105

Work Assignment No.: 01-9L33 EPA Contract No.: 68-01-6939 Document No.: 101 —RI2-RT—8RNH—1

Dear Mr. Takata and Ms. Dermer:

Camp Dresser & McKee, Inc. (CDM) is pleased to submit to you the Del Norte County Pesticide Storage Area Site Final Remedial Investigation and Feasibi l i ty Study Reports. We bel ieve that the Remedial Investigation report ref lects the act ivi t ies of a complete si te characterizat ion, and that the Feasibi l i ty Study Report provides real ist ic and cost effect ive alternatives for remediat ion at the si te.

Should you have any questions regarding these f inal reports, please do not hesitate to cal l the REM I I Site Manager, Mr. David Gaboury at Woodward-Clyde Consultants (415-945-3000).

Very truly yours, INC.

Technical Operations Manager

DFD:rb/0066s*

cc: Ulr ike Joiner, Contract ing Off icer, US EPA Linda Boornazian, Project Off icer, US EPA Harry Seraydarian, Region IX Superfund Coordinator, US EPA Tom Bai ly, REM I I Region IX Manager, Woodward-Clyde Consultants

One Walnut Creek Center WOOdWard'ClyCle COnSUltailtS 100 Pringle Avenue Walnut Creek, CA 94596 415-945-3000

September 27, 1985

Mr. David Doyle, P.E. Technical Operations Manager Camp Dresser & McKee, Inc. 7630 Li t t le River Turnpike, Suite 500 Annandale, Virginia 22003

Work Assignment No.: 01-9L33 EPA Contract No.: 68-01-6939 Document No.: 101-RI2-RT-BRNH-1

Dear Mr. Doyle:

Woodward-Clyde Consultants is pleased to submit the Del Norte County Pesticide Storage Area Site Final Remedial Investigation and Feasibi l i ty Study Reports. Throughout the past three months, we have incorporated comments on draft versions of these reports from the EPA and state agencies.

Should you have any questions regarding the content of these reports, please do not hesitate to cal l our off ice.

Sincerely,

tteTrUU? i

David R. Gaboury I Thomas 0. Bai ly REM I I Site Manager REM I I Region 9 Manager

DRG/T0B:rb 0065s*

Enclosures

Consulting Engineers. Geologists and Environmental Scientists

Offices in Other Principal Cities

DEL NORTE COUNTY

PESTICIDE STORAGE AREA SITE

REMEDIAL INVESTIGATION

EPA CONTRACT NO. 68-01-6939

DOCUMENT CONTROL NO. 101-RI2-EP-BAXU-4

Prepared for

U.S. Environmental Protection Agency

215 Fremont Street

San Francisco, CA 94105

Prepared by

Woodward-Clyde Consultants

One Walnut Creek Center

100 Pringle Avenue

Walnut Creek, CA 94596

September 13, 1985

0308S-1

FOREWORD

The Del Norte County Pesticide Storage Area Site (the Del Norte Site) is

an area 100 by 200 ft in size, approximately 1 mile northwest of Crescent

City, California. Both the site and the adjacent land are owned by Del

Norte County. The site, established in 1970, was operated by the County

as a county-wide collection point for interim or emergency storage of

pesticide and herbicide containers.

In August 1981, inspection by the State of California North Coast

Regional Water Quality Control Board (NCRWQCB) revealed improper

operations at the site, and the County was ordered to close the facility

shortly thereafter. In 1983, based on preliminary field investigations

of soil and groundwater contamination by the NCRWQCB and the California

Department of Health Services, the U.S. Environmental Protection Agency

(EPA) evaluated the site and proposed to include it on the National

Priorities List (NPL) of hazardous waste sites. The site was placed on

the NPL in September 1984. This action by EPA made the site eligible for

funding under the Comprehensive Environmental Response, Compensation, and

Liability Act (CERCLA, or Superfund).

For remedial responses under CERCLA, such as at the Del Norte Site that

do not present immediate or imminent health or environmental hazards,

EPA's response activities begin with a Remedial Investigation (RI) and

Feasibility Study (FS). The RI is designed to collect and analyze the

data necessary to define the problem and evaluate possible cleanup

alternatives. Based on the findings of the RI, the FS identifies and

evaluates alternative methods for cleaning up the site.

This document presents and discusses the results of the RI conducted for

the Del Norte Site. The FS is provided in a separate volume.

iii

101-RI2-EP-BAXU-4

0306s—1

EXECUTIVE SUMMARY

PURPOSE

This document presents and discusses the results of the Remedial

Investigation (RI) conducted for the Del Norte County Pesticide Storage

Area Site (the Del Norte Site). The RI was conducted for two major

purposes—(1) to collect sufficient information to define the nature and

extent of contamination at the site and (2) to assess present and

potential impacts of the continued existence of the site on public health

and welfare, and the environment. The data collected during the RI is

also designed to provide a basis for an evaluation of the remedial

alternatives that may have to be implemented to reduce or eliminate

present and/or potential impacts. The remedial alternatives are

evaluated in the Feasibility Study.

The specific goals of the RI were achieved by establishing and executing

the following more specific tasks, for both the site itself and the

surrounding area:

• Compiled background information on the site (operating history,

prior land uses, etc.)

• Determined the nature and extent of surface soil contamination

• Determined the nature and extent of subsurface soil contamination

• Determined the nature and extent of groundwater contamination

• Determined the significance of surface water, air, and biota as

other pathways for transport and exposure

• Assessed the present and potential impacts of the site to the

public health and welfare and the environment.

iv 101-RI2-EP-BAXU-4

0306S-2

BACKGROUND

The Del Norte Site was established by Del Norte County in January 1970 as

a county-wide collection point for interim or emergency storage of

pesticide and herbicide containers. The designated site, 200 ft long and

100 ft wide, was located at the southern border of the McNamara Field

County Airport, 3/4 of a mile east of the Pacific Ocean. The County

requested operating advice and subsequently received approval of the site

from the North Coast Regional Water Quality Control Board (NCRWQCB),

provided that all containers were triple-rinsed and punctured prior to

arrival at the site. On August 13, 1981, an inspection of the site by

the NCRWQCB revealed that the incoming drums had not complied with the

triple-rinse procedures and that the County had failed to keep an

accurate log and record of incoming wastes. One week later, the site

ceased accepting deliveries. At final count, there were approximately

1,600 drums on the site, and only a few were properly rinsed and

punctured. The condition of the drums ranged from badly corroded to

nearly new.

Very little other documentation is available about actual day-to-day site

operations, despite requests by the NCRWQCB and the California State

Department of Health Services (DOHS) that the County maintain logs of

site operations. Site investigations have revealed that a sump

approximately 20 ft long, 15 ft wide, and several feet deep was

constructed on-site. Testing revealed that this sump contains the

highest chemical concentrations on-site. It is likely that wastes and/or

rinse water had been disposed of in the sump. Information as to when the

sump was excavated and how often it was used is not available.

As a result of the site inspections, the NCRWQCB issued Cleanup and

Abatement Order No. 81-213 in October of 1981, which required the removal

of all hazardous wastes (i.e., drums) to a site authorized to accept

California-designated Class I wastes. By April 1982, all containers had

been removed from the site. Under the NCRWQCB Cleanup and Abatement

101-RI2-EP-BAXU-4

0306S-3

Order 81-213, the County was charged with determining the extent of

potential contamination at the site. The County was unable to comply

with the order due to lack of funding, so the NCRWQCB and the DOHS

carried out post-closure monitoring, which revealed elevated levels of

herbicides and pesticides in the soil and groundwater.

On the basis of these results, the NCRWQCB determined that a problem

existed at the site, and amended its Cleanup and Abatement Order 81-213

in August 1983 to require that the extent of contamination be

determined. A plan for cleanup and/or abatement of the contamination was

also to be developed. The Del Norte County Board of Supervisors asserted

that the County was unable to fund such a study. The County's inability

to fund further site investigations triggered the process by which the

site became a CERCLA-regulated, or Superfund, site.

ACTIVITIES

The first step in the RI/FS process is the preparation of a work plan.

The work plan is a critical document since it identifies the specific

technical tasks necessary to determine the nature and extent of

contamination and potential cleanup alternatives. The first step in the

development of the work plan was a review of all existing data concerning

the site. Several other preliminary tasks were conducted during the work

plan development. These included site visits, preparation of a site

topographic map, a geophysical survey, and some preliminary soil

sampling. The results of these preliminary activities were included in

the work plan to help better define the necessary level of technical

studies for the remedial investigation. The resulting document, Del

Norte County Pesticide Storage Area Site; Remedial Investigation and

Feasibility Study Work Plan, was completed on January 16, 1985.

Two surface and subsurface soil sampling programs and a groundwater

monitoring program were completed. In the first program, composite

surface soil samples were collected from 50-ft-square quadrants on-site

101-RI2-EP-BAXU-4

vi

0306S-4

and immediately off-site. Subsurface soil samples were collected from

borings centered in eight on-site quadrants and in the sump area. The

borings were all 10 ft deep. In the second program, composite surface

samples were collected from 25-ft-square quadrants on-site only.

Subsurface soil samples were collected from five borings: one in the

sump, three immediately surrounding the sump, and one where a trench had

been located. Nine new groundwater monitoring wells were installed

around the site for the groundwater monitoring program. Also included in

the monitoring program were four local residential wells, one abandoned

well, and one existing on-site observation well.

The surface and subsurface soil samples and the groundwater samples were

all analyzed for herbicides, pesticides, volatile organics, and

semi-volatile organics. In addition, the samples were analyzed for

pentachlorophenol, a wood preservative, because it was detected during

pre-work plan sample analysis. The samples were also analyzed for the

metals arsenic, chromium, and copper because chromated copper arsenate is

used in the salt treating of wood.

In order to determine the permeability of the shallow aquifer,

hydrogeologic testing was performed in selected groundwater monitoring

wells by the means of slug testing and grain-size distribution analysis.

Water level measurements were taken several times at the wells over a

three-month period so that groundwater contour maps could be

constructed. Groundwater modeling was performed to project future

migration of the groundwater contamination plume.

Other potential pathways for contamination were examined. It was

determined that no contaminants from the Del Norte County Pesticide

Storage Site had migrated into surface water runoff paths. The air and

biota were eliminated as significant pathways. In addition, a public

health, welfare, and environmental assessment was made of the present

site conditions as well as the no-action alternative (letting the site

remain in its present state ad infinitum). This assessment was performed

vii 101-RI2-EP-BAXU-4

0306S-5

by comparing the results of the present and future extent of soil and

groundwater contamination with the known effects of the contaminants.

The major findings of the Remedial Investigation for the Del Norte Site

are summarized below.

FINDINGS

(1) Activities that occurred during the site operations from 1970 to

1981 have resulted in contamination of soil and groundwater.

The contaminants are herbicides, pesticides, volatile and

semi-volatile compounds.

(2) The on-site sump, measuring 15 by 20 ft, is the primary area of

soil contamination, with the organic compounds detected to a

depth of about 15 ft below grade. Contamination of soils on the

remainder of the site is restricted to very limited areas,

likely as a result of leaks or spills from drums. No

contamination below 1 ft was detected outside the sump.

(3) The spread of soil contamination off-site due to wind or runoff

was not detected.

(4) Many of the compounds found in the soil were also detected in

the groundwater beneath the site. Groundwater contamination has

spread a distance of about 150 to 300 ft in the southeasterly

direction from the on-site sump area. Use of the contaminated

on-site groundwater as a water supply would result in a

significant health risk.

(5) Projections of future migration of groundwater contaminants

indicate that under a "worst-case" situation, existing private

wells to the southeast of the site could become unsuitable for

viii 101-RI2-EP-BAXU-4

0306S-6

use in the next 50 to 100 years. However, more realistic or

expected exposure and risk estimates suggest that the threat to

private wells from the site is minimal.

(6) Investigations on-site and in the surrounding area have revealed

soil and groundwater contamination due to past land uses in the

vicinity (not associated with the pesticide site). Generally,

this contamination is quite limited and does not warrant further

investigation. For example, PAHs were detected in monitoring

well 14 (MW-14). When this well was resampled in July 1985,

PAHs were detected again. (Refer to the Chromium and PAH

Groundwater Sampling Technical Memorandum. September 1985, for

the results.) In addition, 2,4-D was detected in MW-5, and

volatile organics were detected in background surface soil

samples. Of much greater significance was the widespread

detection of the metals, copper, arsenic, and chromium in soils

and groundwater, both on- and off-site. These are due to past

land uses in the vicinity, not associated with the Del Norte

pesticide site. Chromium is the primary metal of concern. The

existing data is inadequate to assess the source, extent, and

migration potential of these metals. This problem is discussed

further in the section immediately below.

DATA PROBLEMS AND UNRESOLVED DATA NEEDS

In September 1984, pentachlorophenol was detected in a subsurface soil

sample. Since pentachlorophenol is used as a wood preservative, it was

decided to analyze future soil and water samples for metals (copper,

arsenic, and chromium) associated with a compound used to treat wood.

Copper and arsenic were detected at insignificant concentrations;

however, high levels of chromium were detected in January 1985 surface

soil samples, February 1985 subsurface soil samples, and February, March,

and April 1985 groundwater samples. Two facts indicate that the chromium

contamination is not associated with the pesticide storage area site.

ix 101-RI2-EP-BAXU-4

0306S-7

Background surface soil samples taken well off-site contained high

concentrations of chromium. In addition, there are no historical data

which indicate that chromium or chromium compounds were handled at the

site.

The chromium analyses described above were for total chromium, and it was

not known in what form (trivalent or hexavalent) the chromium occurred.

Hexavalent chromium is much more toxic than trivalent. Additional

groundwater samples were taken in July 1985 to determine which form was

present. The analyses of the July 1985 samples did indicate that the

chromium was in particulate form and very little dissolved chromium was

present. Because chromium in hexavalent form is highly soluble, the

chromium in particulate form is likely to be in trivalent form.

Additional testing will be done during the design phase to further

identify the form of chromium. The chemical treatment for the removal of

chromium in either form is similar (this is discussed in Section 3.0). A

formal discussion of the results and conclusions of the July 1985

sampling is presented in the Chromium and PAH Groundwater Sampling

Technical Memorandum (September 1985).

Chromium standards for both water and soil are applicable. The

California Assessment Manual (CAM) Total Threshold Limit Concentration

for chromium VI compounds is 500 ppm; it is 2500 ppm for chromium III

compounds. Concentrations above these limits are considered to be

hazardous wastes. Surface and subsurface soil sample results were all

well below these CAM limits. The primary drinking water standard for

total chromium is 50 ppb. Water samples from the private wells had total

chromium below 50 ppb, so no immediate problem exists. Samples from the

other monitoring wells had total chromium averaging 5 times the drinking

water standard, with maximum values over 10 times the standard.

Further groundwater sampling during the remedial design stage will verify

the form of chromium. Pending the results of this sampling, EPA will

evaluate the need for an additional investigation into the source and

extent of chromium contamination.

101-RI2-EP-BAXU-4 x

0210S-2

TABLE OF CONTENTS

Section Page

FOREWORD

EXECUTIVE SUMMARY

1.0 INTRODUCTION 1-1 1.1 Site Background 1-1 1.2 Postclosure Activities by State Agencies 1-5 1.3 Environmental Protection Agency Remedial Response 1-6 1.4 Overview of Report 1-8

2.0 SITE FEATURES INVESTIGATION 2-1 2.1 Demography 2-1 2.2 Land Use 2-1 2.3 Natural Resources 2-3 2.4 Climatology 2-4

3.0 HAZAROOUS SUBSTANCE INVESTIGATION 3-1 3.1 Waste Types 3-1 3.2 Waste Component Characteristics and Behavior 3-3

4.0 HYDROGEOLOGIC INVESTIGATION 4-1 4.1 Introduction 4-1 4.2 Surface Soils 4-3 4.3 Subsurface Geology and Soils ^ 4-26 4.4 Groundwater 4-44

5.0 SURFACE WATER INVESTIGATION 5-1 5.1 Introduction 5-1 5.2 Drainage 5-1 5.3 Sediments 5-3 5.4 Flood Potential 5-4

6.0 AIR INVESTIGATION 6-1 6.1 Activities 6-1 6.2 Findings 6-1

7.0 BIOTA INVESTIGATION 7-1 7.1 Activities 7-1 7.2 Findings 7-1

8.0 PUBLIC HEALTH AND ENVIRONMENTAL CONCERNS 8-1 8.1 Introduction 8-1 8.2 Activities 8-1 8.3 Findings 8-3

9.0 REFERENCES 9-1

xi

021Os—3

TABLE OF CONTENTS (concluded)

Appendices Page

APPENDIX A - Hydrogeologic Investigation: Surface and Subsurface Soils A-l

A.l Surface Soil Sample Collection Procedures A-l A.2 Subsurface Soil Sample Collection Procedures A-3 A.3 Sample Preparation Procedures A-5 A.4 Geophysical Study A-7 A.5 List of Constituents Analyzed in Soil Samples A-l3 A.6 September 1984 and February 1985 Boring Logs A-24

APPENDIX B - Hydrogeologic Investigation: Groundwater B-l B.l Well Logs B-l B.2 Grain Size Distribution Date B-20 B.3 Falling Head Test—Hydraulic Conductivity

Calculations B-33 B.4 Calculation of Hydraulic Conductivity from

Grain Size Distribution Data B-38

APPENDIX C - Toxicity Assessment of Principal Contaminants C-l

xii

0309S-1

LIST OF TABLES

Table Page

3-1 Known Chemicals Present at the Del Norte County Pesticide Storage Area Site 3-2

4-1 Compounds Tested for During DOHS Soil Sampling 4-5

4-2 Contaminant Concentrations in On-Site Soil Samples: Del Norte County Pesticide Storage Area, June 1982 4-8

4-3 Chlorophenoxy Herbicides in Surface and Subsurface Soils: September 1984 Samples 4-15

4-4 Volatile and Semi-Volatile Organics and Pesticides in Surface and Subsurface Soils: September 1984 Samples 4-16

4-5 Herbicides and Pentachlorophenol in Surface Soil: January 1985 Samples 4—19

4-6 Volatile and Semi-Volatile Compounds and Pesticides in Surface Soil: January 1985 Samples 4-20

4-7 Arsenic, Chromium, and Copper in Surface Soils: January 1985 Samples 4-21

4-8 Comparison of Past and Present Surface Sample Analysis Results 4-23

4-9 Herbicides, Pesticides, Phenols, and Chlorinated Organics* in Subsurface Soil: February 1985 Samples 4-34

4-10 Volatiles and Semi-Volatiles Found in Subsurface Soil: February 1985 Samples 4-35

4-11 Arsenic, Chromium, and Copper in Subsurface Soils: February 1985 4-38

4-12 Comparison of Past and Present Subsurface Sample Results 4-41

4-13 Monitoring Well Specifications 4-48

4-14 Water Table Elevations 4-50

xiii

0309S-2

LIST OF TABLES

(concluded)

Table Page

4-15 Volatile, Semi-Volatile, and Pesticide Compounds in Groundwater 4-55

4-16 Arsenic, Chromium, and Copper in Groundwater 4-57

4-17 Hydraulic Conductivity (k) Values Derived from Falling Head Test Data 4-60

4-18 Hydraulic Conductivity (k) Derived from Grain Size Analysis 4-62

4—19 Summary of Contaminant Transport Parameters 4-70

8-1 Contaminants of Primary Concern at the Del Norte County Pesticide Storage Area Site: Comparison of Concentrations in Groundwater with Applicable Standards and Criteria 8-4

8-2 Cancer Risk Associated with Ingestion of Contaminated Groundwater 8-8

8-3 Cancer Risk Associated with Ingestion of Contaminated Groundwater at Potential Human Exposure Points 8-10

xiv

0309S-3

LIST OF FIGURES

Figure Page

1-1 Location Hap 1-2

4-1 Approximate Locations of DHS Quadrants, Soil Sampling, June 1982 4-4

4-2 Surface Sampling and Boring Locations, September 1984 4-10

4-3 Surface Sample and Boring Locations, January and February 1985 4-11

4-4 Contaminants Detected in Surface Soils, September 1984 Samples 4-14

4-5 Contaminants Detected in Surface Soils, January 1985 Samples 4-18

4-6 Locations of Background Samples 4-25

4-7 Geologic Section Through the Del Norte Site 4-27

4-8 Contaminants Detected in Subsurface Soils, September 1984 and February 1985 4-31

4-9 Monitoring Well Locations and April Groundwater Contours 4-42

4-10 Groundwater Sampling Locations 4-51

4-11 1,2-Dichloropropane Plume at 0 Years 4-71

4-12 1,2-Dichloropropane Plume at 25 Years 4-72

4-13 1,2-Dichloropropane Plume at 50 Years 4-73

5-1 Topographic Map, Del Norte Site 5-2

5-2 Suggested Surface Water Drainage Paths in the Vicinity 5-4

XV

0301s-1

1.0 INTRODUCTION

The Del Norte County Pesticide Storage Area Site, located approximately

one mile northwest of Crescent City, California, consists of less than

one acre of land contaminated with a variety of herbicides, pesticides,

and other compounds. A Remedial Investigation/Feasibility Study (RI/FS)

has been conducted at the Del Norte Site by the Environmental Protection

Agency (EPA) as part of their remedial response under CERCLA. The

purpose of the Remedial Investigation was to collect and analyze the data

necessary to define the nature and extent of contamination at the site

and to provide sufficient data to evaluate alternatives to mitigate the

problem. The Feasibility Study, which is provided under separate cover,

contains an evaluation of appropriate and cost-effective alternatives for

remediation of the site.

This report presents the results of the Remedial Investigation (RI), and

describes the characteristics, distribution, and extent of contamination

at the site. The potential impact of the contamination on public health

and welfare and the environment is also discussed. The following

introductory sections are presented to document the site's known

operating history and closure, and the subsequent events which preceded

the remedial investigation.

1.1 SITE BACKGROUND

1.1.1 SITE OPERATING HISTORY

In December 1969, the Del Norte County Sanitarian notified the North

Coast Regional Water Quality Control Board (NCRWQCB) of the County's

intent to operate a pesticide container storage area. The designated

site, 200 ft long and 100 ft wide, was to be located at the southern

border of the McNamara Field County Airport, 3/4 of a mile east of the

Pacific Ocean (see Figure 1-1). The County requested operating advice

101-RI2-EP-BAXU-4

1-1

PROJECT SITE-

Pacific Ocean

0 L.

% _L_

1 mile

Proton Island miafo ^emoriaT"

Figure 1-1. LOCATION MAP

1-2

0301s-2

and approval from the NCRWQCB, and in January 1970, the NCRWQCB responded

with suggested operating procedures and requested additional information

about the site. Ouring 1970, the site was designated as a Class II—2

disposal site. It was to serve as a county-wide collection point for

interim or emergency storage of pesticide containers generated by local

agricultural and forestry-related industries. The NCRWQCB approved the

site for this use, provided that all the containers were triple-rinsed

and punctured prior to arrival at the site.

In 1974, the California Department of Health Services (DOHS) issued

a memorandum requiring hazardous waste handlers to comply with a monthly

reporting system and fee schedule. The Del Norte Site was exempted from

the rule due to the small quantities of waste which they handled. DOHS

requested that Del Norte County keep accurate records of their operations

in spite of the exemption.

In early November 1976, a NCRWQCB representative inspected the site. On

November 12, 1976, the NCRWQCB approved the site for interim and

emergency storage of small quantities of industrial and agricultural

wastes and pesticide containers. The NCRWQCB waived the Report of Waste

Discharge requirement for the site, but required the County to log all

incoming wastes and affirm that all empty containers brought to the site

had been triple-rinsed.

Very little documentation is available about actual day-to-day site

operations. Site investigations have revealed that a sump approximately

20 ft long, 15 ft wide, and several feet deep was constructed on-site.

Testing revealed that this sump contains the highest chemical

concentrations on-site. It is likely that wastes and/or rinse water had

been disposed of in the sump. When the sump was excavated and how often

it was used were not recorded.

On August 13, 1981, an inspection of the site by the NCRWQCB revealed

that the in-coming drums had not complied with the triple-rinse

101-RI2-EP-BAXU-4

1-3

0301s-3

procedures and that the County had failed to keep an accurate log and

record of incoming wastes. One week later, the County ceased accepting

deliveries at the site. Based on an inspection report, there were

approximately 1,600 drums on the site, and only a few were properly

rinsed and punctured. The condition of the drums ranged from badly

corroded to nearly new. Many of the several hundred newer drums on the

site were labeled so that some of the wastes could be documented. The

available log of the incoming wastes was inspected and found to date back

only to 1979. The EPA inspected the site on September 25, 1981, and

found numerous Resource Conservation and Recovery Act (RCRA) violations.

1.1.2 SITE CLOSURE

As a result of the site inspections, the NCRWQCB issued Cleanup and

Abatement Order No. 81-213 in October of 1981, which required the removal

of all hazardous wastes (e.g., drums) to a site authorized to accept

California-designated Class I wastes. The order also required the County

to determine the extent of potential contamination by sampling and

analyzing soils and by installing exploratory monitoring wells to sample

groundwater. The County in turn requested financial assistance from the

DOHS to comply with this order later that month. In November 1981, Del

Norte County submitted a proposed site closure plan to the NCRWQCB.

In January 1982, the County removed 1,150 of the containers from the

site. The rusted or corroded drums were removed and disposed of in a

special section of the Crescent City Landfill. The County Agricultural

Commissioner certified that the remainder of the 1,150 drums had been

adequately rinsed prior to storage at the Del Norte Storage Site. These

drums were also disposed of in a different section at the Crescent City

Landfill. In April 1982, the remaining 440 empty, sealed, and unrinsed

drums of "D-D" and "Telone" were shipped to a licensed recycler, the Rose

Cooperage Company, in Montebello, California.

101-RI2-EP-BAXU-4

0301s-4

During these activities, several drums on the site were found to contain

usable quantities of various pesticides, which were recycled by the

County Agricultural Commissioner for weed control. These drums were then

triple-rinsed and disposed of at the Crescent City Landfill. The

location where rinsing took place is unknown. Three remaining drums

containing pesticides that were not recyclable (i.e., 2,4-D sludge,

thimet, and miscellaneous materials) were put in storage in a vacant

building near the County Agricultural Commissioner's office for later

shipment to a Class I disposal site. The final disposition of these

drums has not been resolved.

1.2 P0STCL0SURE ACTIVITIES BY STATE AGENCIES

Under the NCRWQCB Cleanup and Abatement Order 81-213, the County was

charged with determining the extent of potential contamination at the

site. The County was unable to comply with the order due to lack of

funding, so the NCRWQCB and the DOHS carried out postclosure monitoring.

The DOHS collected on-site soil samples from three locations and sampled

four drums in December 1981. An additional 21 soil samples were

collected in June 1982. The results of their analyses showed high

concentrations of 2,4-D, 2,4-DB, 2,4,5-TP, 2,4,5-T, ethion, and malathion

in several areas, particularly the sump and areas of known drum storage.

The NCRWQCB collected groundwater samples from two on-site monitoring

wells which were installed for that purpose, as well as nine off-site

supply wells, in September 1982 and early 1983. The on-site water

samples showed elevated levels of the same contaminants found in the

soil, along with several other compounds. Five of the off-site wells

showed very low levels of contamination, well below applicable standards.

On the basis of these results, the NCRWQCB determined that a problem

existed at the site, and amended its Cleanup and Abatement Order 81-213

in August 1983 to require that the extent of contamination be

determined. A plan for cleanup and/or abatement of the contamination was

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also to be developed. The Del Norte County Board of Supervisors asserted

in a letter to DOHS that the County was unable to fund a study to

determine the extent of contamination. The County's inability to fund

further site investigations triggered the process by which the site

became a CERCLA-regulated, or Superfund, site.

1.3 ENVIRONMENTAL PROTECTION AGENCY REMEDIAL RESPONSE

1.3.1 INTRODUCTION

CERCLA, or Superfund, legislation authorizes the EPA to investigate and

respond to releases or threatened releases of hazardous substances which

may endanger public health and welfare or the environment. Superfund

refers to the trust fund of several billion dollars which is generated

primarily from taxes on specific chemicals and oil, and which pays for

CERCLA activities. Two basic forms of response can be undertaken:

emergency response is required to prevent immediate and significant harm

to human health or the environment and must be completed in less than six

months; remedial responses are taken when longer-term actions are

required to achieve permanent remedies. The Del Norte County Pesticide

Storage Site Area was determined to be a remedial response site.

Remedial response can be taken only at sites included on EPA's National

Priorities List (NPL), which currently consists of 786 priority sites.

The sites on this list are eligible for federal funding.

For remedial responses that do not present immediate or imminent health

or environmental hazards, response activities begin with a Remedial

Investigation (RI) and Feasibility Study (FS). The RI is designed to

collect and analyze the data necessary to define the problem and evaluate

possible solutions. The RI provides input to the Feasibility Study (FS),

to identify and evaluate alternative methods for cleaning up the site.

Under agreement with the federal government, state governments may take

either the lead role or provide assistance to EPA in planning and

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managing response activities. Regardless of what agency has the lead for

a site, CERCLA requires state governments to pay for 10 percent of the

costs of remedial actions at privately owned sites, and at least 50

percent of the costs at sites that were publicly owned at the time of

disposal. EPA is the lead agency on the Del Norte Site and coordinates

closely with state agencies, including the DOHS and the NCRWQCB. Since

the Del Norte Site is publicly owned, the state may be required to share

50 percent of the cost of a remedial action.

1.3.2 RI/FS WORK PLAN DEVELOPMENT

Prior to initiating the RI/FS investigation, a work plan was required.

The work plan is a critical step in the RI/FS process since it identifies

the specific technical tasks necessary to determine extent of site

contamination and potential cleanup alternatives. The first step in the

development of the work plan was a review of all existing data concerning

the site. Several other preliminary tasks were conducted during the work

plan development. These included site visits, preparation of a site

topographic map, a geophysical survey, and some preliminary soil

sampling. These preliminary activities were included in the work plan

development to help better define the necessary level of technical

studies for the remedial investigation. The resulting document, Del

Norte County Pesticide Storage Area; Site Remedial Investigation and

Feasibility Study Work Plan, was completed on January 16, 1985.

Included with the work plan are the Project Operations Plan (POP) and

Quality Assurance Plan (QAP), which identify the specific procedures

which must be followed for all field and laboratory activities, to ensure

that the precision, accuracy, completeness, and representativeness of the

data gathered at the Del Norte Site are known and documented. All site

investigations were carried out in accordance with the criteria presented

in the POP and QAP.

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1.3.3 SUMMARY OF REMEDIAL ACTION ACTIVITIES

A summary of the Remedial Investigation activities follows below:

• Composite surface soil samples were collected from on-site and

off-site quadrants.

• Subsurface soil samples were collected from borings drilled in

on-site quadrants.

• Nine groundwater monitoring wells were installed.

• Surface and subsurface soil samples and groundwater samples were

analyzed for herbicides, pesticides, volatile organics and

semi-volatile organics.

• The permeability of the shallow groundwater aquifer under the

site was determined.

• Groundwater contour maps were constructed.

• Computer modeling was used to project future migration of the

groundwater contamination plume.

• Surface water runoff, air, and biota were examined as potential

pathways for contamination.

1 .4 OVERVIEW OF REPORT

This subsection summarizes the contents of the remaining sections in this

report. Section 2.0 describes the site features, including demography,

site land uses, natural resources, and climatology. Section 3.0

describes the waste characteristics, including all known materials

present at the site. Section 4.0 is the description of the soil and

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groundwater investigations. Sections 5, 6, and 7 discuss the surface

water, air, and biota investigations, respectively. Section 8.0

summarizes the present and potential public health and environmental

concerns related to the site; the full risk assessment report itself is

attached as an appendix.

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2.0 SITE FEATURES INVESTIGATION

2.1 DEMOGRAPHY

The Del Norte County Pesticide Storage Area Site is located in a rural

area one mile northwest of Crescent City, California, and immediately

south of McNamara Field, the airport which serves Del Norte County (see

Figure 1-1). According to the California State Department of Finance,

approximately 18,300 people presently reside in Del Norte County.

Between the years 1970 and 1980, the average annual increase in the

county population was 2.1 percent. The population for Del Norte County

is projected to be 24,100 by the year 2000 (an increase of about 30

percent over the present value).

As of January 1, 1985, the population of Crescent City was estimated at

3,280. The population of the city from the 1980 census was 3,075. At

the time of the census, there were 1,214 occupied dwellings or households

in Cresent City with an average of 2.4 persons per household. In 1982,

the EPA estimated that 250 persons lived within one mile of the Del Norte

County Pesticide Storage Site, and no substantial change has occurred

since.

2.2 LAND USE

2.2.1 PAST LAND USES

The Del Norte Site and the land immediately surrounding it have been used

for a variety of activities throughout the years. Seven aerial

photographs, dating from 1948 to 1982, were examined to obtain a better

understanding of the historical use of the area, and to determine any

areas of concern. Existing information indicates that the site and

surrounding area have been used for waste disposal and related activities

for some time.

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Two possible dump sites were identified on the historical aerial photos.

In 1951, a dump was located about 25 ft from the eastern border of the

site. The second dump was noted in the southeast corner of the site in

1965. The type of material disposed of in these dumps is not recorded.

In addition, it appears that the site was used to park and possibly

service aircraft and tank trucks up until its current use began in 1970.

Over the years, various clearings, rough roadways, and trenches were

constructed in and around the site. Many small trenches existed and were

connected to existing drainage ditches around the site, presumably to

assist in drainage. Of concern was a trench that appeared in the 1970

photos, which was located in the southeast corner of the site. According

to the 1976 photo, this trench was filled in; however, a similar trench

reappeared in the 1982 photo, larger in size and adjacent to the old

trench.

In 1970 the pesticide storage site was established and a fence measuring

100 ft by 200 ft was erected. Although the 1970 photograph does not show

the presence of drums, the next photo taken in 1976 does show drums and

the on-site sump. The majority of the drums were located at the north

end of the site, adjacent to the sump, with a few groups of drums along

the eastern boundary. In addition, a small group of drums was located in

an open area approximately 150 ft to the northeast of the site. It is

possible that these drums were not designated for disposal and were

stored there temporarily away from the other drums.

During the drilling of several groundwater monitoring wells, objects were

found in the soil cuttings which prompted inquiry into the past uses of

specific areas. When drilling groundwater monitoring well MW-5, about

150 ft off the southeast corner of the site, old dog bones were found.

When drilling a well off the southwest corner of the site, dog hair and

portions of a carcass were found. Soil in the entire vicinity of this

well was disturbed, many small trenches were observed, and scars from old

trenches were visible. Subsequently, it was discovered that these areas

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had been used as burial sites for animals from the pound operated by the

Agricultural Commission facility. As the boring for a well to the

northeast of the site was drilled, pieces of pavement were observed.

This area was probably pavement associated with the airport; the edge of

a runway is only 400 ft away. Data from one of the original NCRWQCB

on-site borings indicated that old spark plugs and what appeared to be a

pocket of motor oil were found. Apparently, the area had also been used

as a World War II aircraft maintenance site.

2.2.2 PRESENT AND FUTURE LAND USES

The Del Norte Site and the land surrounding it are owned by Del Norte

County. The storage site itself, closed in 1981, is fenced, locked, and

posted with a public notice stating that hazardous substances may be

present. The entire County-owned parcel (including the site) covers an

area of approximately 480 acres. The County property is bounded on the

north by state-owned land, intended for use as a natural and recreational

area; on the south by Washington Boulevard and privately owned farmland;

on the east by Riverside Drive and approximately seven private

residences; and on the west by the Pacific Ocean. Future development in

this area is unknown but expected to be minimal, due to close proximity

to the airport.

2.3 NATURAL RESOURCES

Parklands, the ocean, and groundwater are three natural resources in the

immediate vicinity of the Del Norte Site. About two-thirds of Del Norte

County is occupied by preserved land: Del Norte Coast Redwoods and

Jedediah Smith Redwoods state parks, Redwood National Park, and Six

Rivers National Forest. These parks are all within six to ten miles of

the pesticide storage site. Three-quarters of a mile west of the site is

the Pacific Ocean, where Pebble Beach extends along the coastline.

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Groundwater in the immediate vicinity of the site is used for private

water supply. Four private water wells are located within 1500 to

2500 ft of the site. Recent sampling and analysis of these waters show

that the wells have not been affected by the wastes from the site. As a

part of the remedial investigation, an extensive study was performed on

the groundwater characteristics in and around the site, as described in

Section 4.4, Groundwater Investigation.

2.4 CLIMATOLOGY

The Del Norte Site is located in the northwest corner of California, near

Crescent City and within 3/4 mile of the Pacific Ocean. The climate of

Crescent City area is completely maritime, with high humidity prevailing

the entire year. There are definite rainy and dry seasons. The rainy

season begins in October and continues through April, accounting for

about 90 percent of the region's precipitation. Normal annual

precipitation, recorded at a weather station approximately 8 miles

northwest of the site, at an elevation of 125 ft, is 76 in. The dry

season from May through September is marked by considerable fog or low

cloudiness that usually clears in the late morning, followed by sunny

weather during the early afternoon hours.

Temperatures are moderate the entire year. Extreme temperatures range

from 20° to 85°F, and the normal range is from a low of about 35°F to a

high of about 75°F. In the summer months, the average daily temperature

may fluctuate 9°F. During the winter months, the daily temperatures may

fluctuate as much as 13°F; however, during winter, the daily temperatures

usually do not fluctuate more than 2° or 3°F.

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3.0 HAZARDOUS SUBSTANCES INVESTIGATION

3.1 WASTE TYPES

As previously described, pesticide containers were stored at the site

from 1970 to 1982. Between January and March 1982, all containers were

removed. Currently no hazardous wastes are stored on the site.

Accurate records of the numbers, types, and condition of the pesticide

and herbicide storage containers that were received at the site were not

maintained. At the time of site closure, many of the several hundred

newer drums on the site were labeled "D-D Soil Fumigant," which contains

1,3-dichloropropane and 1,2-dichloropropane; "Telone," which contains

1,3-dichloropropane; "Esteron 99 Cone.," which contains 2,4-dichloro-

phenoxyacetic acid (2,4-D); or "Tordon," which contains 4-amino-3,5,6-

trichloropicolinic acid. A summary of the chemicals known to have been

stored on the site, as well as their trade names and uses, are listed in

Table 3-1.

According to the permit conditions under which the facility was to be

operated, all containers received at the site were to be triple rinsed

and punctured. In addition, the site was not permitted to receive and

store other types of hazardous wastes. Although records are inadequate,

because a large number of containers were present at the time of site

closure in 1982, it was suspected that some quantity of the chemicals

listed in Table 3-1 or other unknown chemicals had leaked or spilled from

containers, been dumped into the on-site sump, or otherwise been

deposited on the site. The soil and groundwater monitoring initiated in

1982 confirmed this suspicion.

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Table 3-1. KNOWN CHEMICALS PRESENT AT THE DEL NORTE COUNTY PESTICIDE STORAGE AREA SITE

Active Chemical Trade Name Use

1.3-Dichloropropane

1,2-Dichloropropane

2.4-Dichlorophenoxyacetic acid

2,4,5-Trichlorophenoxyacetic acid

1,2,4,5,6,7,8,9-Octachloro-2,3,3a,4,7,7a-hexahydro-4,7-methanoindane

2-(2,4,5-Trichlorophenoxy)-propionic acid

0,O-Diethyl-S-((ethylthio) methyl)phosphorodithioate

4-Amino-3,5,6-trichloropicolinic acid

0,0,0',0'-Tetraethyl-S,s'-methy-lene bisphosphorodithioate

Heptach1orotetrahydro-4,7-methanoindene

0,0-Dimethyl-S-(l,2-dicarbo-ethoxyethyl) dithiophosphate

D-D Telone

D-D

2,4-D Esteron 99 Cone

2.4,5-T

Chlordane

Si 1 vex 2,4,5-TP

Thimet Phorate

Tordon Picloram

Ethion

Heptachlor

Malathion

Soil Fumigant, Nematocide

Soil Fumigant

Herbicide

Herbicide

Insecticide

Herbicide

Insecticide

Herbicide

Insecticide

Insecticide

Insecticide

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3.2 WASTE COMPONENT CHARACTERISTICS AND BEHAVIOR

Based on the materials known or suspected to have been present at the

site, eleven compounds were selected to assess the hazard the site

currently poses and may pose in the future to the public health and

welfare and to the environment. This selection was based on the

compounds present in the soil or groundwater, persistence and mobility in

the environment, and relative toxicity to humans and/or wildlife. A

summary of the characteristics and behavior of the eleven compounds that

were selected for hazard assessment is presented in this section, these

characteristics relate to environmental transport and fate. Section 8.0,

Public Health and Environmental Concerns, and Appendix C, Preliminary

Risk Assessment, describe the toxicology and potential impacts of these

compounds in greater detail. The following Section 4.0, Hydrogeologic

Investigation, discusses the site sampling program and the contaminants

for which the samples were analyzed, which include the known wastes.

3.2.1 ARSENIC

In the natural environment, arsenic has four different oxidation states,

and chemical speciation is important in determining arsenic's

distribution and mobility. Interconversions of the +3 and +5 states, as

well as organic complexation, are the most important. Arsenic is

generally quite mobile in the environment. In the aquatic environment,

volatilization is important when biological activity or highly reducing

conditions produce arsine or methylarsenics. Sorption by the sediment is

an important fate for the chemical. Arsenic is metabolized to organic

arsenicals by a number of organisms; this increases arsenic's mobility in

the environment. Because of its general mobility, arsenic tends to cycle

through the environment. Its ultimate fate is probably the deep ocean,

but it may pass through numerous stages before finally reaching the sea.

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3.2.2 BENZENE

Volatilization appears to be the major transport process of benzene from

surface waters to the ambient air, and atmospheric transport of benzene

readily occurs. Although direct oxidation of benzene in environmental

waters is unlikely, cloud chamber data indicate that it may be

photooxidized rapidly in the atmosphere. Inasmuch as volatilization is

likely to be the main transport process accounting for the removal of

benzene from water, the atmospheric destruction of benzene is probably

the most likely fate process. Values for benzene's log octanol/water

partition coefficient indicate that adsorption onto organic material may

be significant under conditions of constant exposure. Sorption processes

are likely removal mechanisms in both surface water and groundwater.

Although the bioaccumulation potential for benzene appears to be low,

gradual biodegradation by a variety of microorganisms probably occurs.

The rate of benzene biodegradation may be enhanced by the presence of

other hydrocarbons.

3.2.3 CHROMIUM

Hexavalent chromium (Cr VI) is quite soluble, existing in solution as a

component of a complex anion. It is not sorbed to any significant degree

by clays or hydrous metal oxides. The anionic form varies according to

pH and may be a chromate, hydrochromate, or dichromate. Because all

anionic forms are so soluble, they are quite mobile in the aquatic

environment. Cr VI is efficiently removed by activated carbon and thus

may have some affinity for organic materials in natural water. Cr VI is

a moderately strong oxidizing agent and reacts with reducing materials to

form trivalent chromium (Cr III). Most Cr III in the aquatic environment

is hydrolyzed and precipitates as chromium hydroxide. Sorption to

sediments and bioaccumulation will remove much of the remaining Cr III

from solution. Cr III is sorbed only weakly to inorganic materials. Cr

III and Cr VI are readily interconvertible in nature, depending on

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microenvironmental conditions such as pH, hardness, and the types of

other compounds present. Soluble forms of chromium accumulate if ambient

conditions favor Cr VI. Conditions favorable for conversion to Cr III

lead to precipitation and absorption of chromium in sediments.

In air, chromium is associated almost entirely with particulate matter.

Sources of chromium in air include windblown soil and particulate

emissions from industrial processes. Little information is available

concerning the relative amounts of Cr III and Cr VI in various aerosols.

Relatively small particles can form stable aerosols and can be

transported many miles before settling out.

Cr III tends to be absorbed strongly onto clay particles and organic

particulate matter, but can be mobilized if it is complexed with organic

molecules. Cr III present in minerals is mobilized to different extents

depending on the weatherability and solubility of the mineral in which it

is contained. Hexavalent compounds are not strongly absorbed by soil

components and Cr VI is mobile in groundwater. Cr VI is quickly reduced

to Cr III in poorly drained soils having a high content of organic

matter. Cr VI of natural origin is rarely found in soils.

3.2.4 DDT

DDT and its metabolites are very persistent in the environment.

Volatilization is probably the most important transport process from soil

and water for p.p'-DDT and o,p'-DDT, as evidenced by the ubiquitous

nature of DDT in the environment. Sorption and bioaccumulation are the

most important transport processes for the DDT isomers. Although it only

occurs slowly, the ultimate fate process for p.p'-DDT, o.p'-DDT, and ODD

is biotransformation to form bis (2-chlorophenyl) methanone (DDCO).

Indirect photolysis may also be important for p.p'-DDT and o.p'-DDT in

aquatic environments. For DDE, direct photolysis is the most important

ultimate fate process in the environment, although biotransformation may

also be important.

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3.2.5 1,2-DICHLOROETHANE

The primary method of dispersion from surface water for 1,2-dichloroethane

is volatilization. In the atmosphere, 1,2-dichloroethane is rapidly

broken down by hydroxylation, although some may be absorbed by

atmospheric water and return to the earth by precipitation. No studies

on the absorption of 1,2-dichloroethane onto soil were reported in the

literature examined. However, 1,2-dichloroethane has a low octanol/water

partition coefficient, is slightly soluble in water, and therefore

leaching through the soil into the groundwater is an expected route of

dispersal.

3.2.6 1,1-DICHL0R0ETHYLENE

Volatilization appears to be the primary transport process for

1,1-dichloroethylene (VOC), and the subsequent photooxidation in the

atmosphere by reaction with hydroxyl radicals is apparently the

predominant fate process. Information on other transport and fate

mechanisms was generally lacking for 1,1-dichloroethylene. However, by

inference from related compounds, hydrolysis, sorption, bioaccumulation,

biotransformation, and biodegradation probably all occur, but at rates

too slow to be of much significance.

3.2.7 2,4-DICHLOROPHENOXYACETIC ACID

Because of its low vapor pressure and relatively high solubility in

water, 2,4-dichlorophenoxyacetic acid (2,4-D) is probably not very

volatile. In surface water, 2,4-D undergoes either photolysis with

oxidation to chlorophenols or photoreduction to phenoxyacetic acid; the

process that occurs depends on the physical properties of the media.

2,4-D is only weakly absorbed to soil and may leach into groundwater,

although studies indicate that this is not an important transport

process. Biodegradation by soil bacteria may be an important fate

process for 2,4-D.

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3.2.8 1,2-DICHLOROPROPANE

Volatilization and subsequent photooxidation are probably important

environmental fate processes for 1,2-dichloropropane. In surface water

and soil, hydrolysis may also be a significant fate process, especially

if the compound is absorbed onto clay particles. Soil microbes can

biodegrade 1,2-dichloropropane, but this is likely to occur more slowly

than volatilization. 1,2-Dichloropropane is probably only moderately

persistent in the environment.

3.2.9 METHYLENE CHLORIDE

Volatilization to the atmosphere appears to be the major mechanism for

removal of methylene chloride from aquatic systems and its primary

environmental transport process. Photooxidation in the troposphere

appears to be the dominant environmental fate of methylene chloride.

Once in the troposphere, the compound is attacked by hydroxy! radicals,

resulting in the formation of carbon dioxide, and to a lesser extent,

carbon monoxide and phosgene. Phosgene is readily hydrolyzed to HC1 and

Ct^. About 1 percent of tropospheric methylene chloride would be

expected to reach the stratosphere where it would probably undergo

photodissociation resulting from interaction with high energy ultraviolet

radiation. Aerial transport of methylene chloride is partly responsible

for its relatively wide environmental distribution. Atmospheric

methylene chloride may be returned to the earth in precipitation.

Photolysis, oxidation, and hydrolysis do not appear to be significant

environmental fate processes for methylene chloride, and there is no

evidence to suggest that either absorption or bioaccumulation are

important fate processes for this chemical. Although methylene chloride

is potentially biodegradable, especially by acclimatized microorganisms,

biodegradation probably occurs only at a very slow rate.

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3.2.10 TETRACHLOROETHYLENE

Tetrachloroethylene (PCE) rapidly volatilizes into the atmosphere where

it reacts with hydroxyl radicals to produce HC1, CO, C02, and

carboxylic acid. This is probably the most important transport and fate

process for tetrachloroethylene in the environment. PCE will leach into

the groundwater, especially in soils of low organic content. In soils

with high levels of organics, PCE absorbs to these materials and can be

bioaccumulated to some degree. However, it is unclear if

tetrachloroethylene bound to organic material can be degraded by

microorganisms or must be desorbed to be destroyed. There is some

evidence that higher organisms can metabolize PCE.

3.2.11 2,4,5-TRICHL0R0PHEN0XYACETIC ACID

Photodecomposition of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) in

water can occur by a number of different mechanisms. These include

photooxidation of the phenoxy side chain and photonucleophilic

displacement of CI by OH to form chlorophenols, and photoreductive

dechlorination to form phenoxyacetic acids. Photolysis of 2,4,5-T under

dry conditions is also a significant environmental fate. Because of its

low vapor pressure, volatilization of this compound is not likely to be

an important process. At least one experimental study confirmed that

volatilization of 2,4,5,-T from an aqueous solution is negligible.

2,4,5-T is only weakly absorbed to soil. In addition, this compound is

moderately soluble in water, and experimental studies show that some

leaching of 2,4,5-T from soil does occur. This material has been found

at low concentrations in groundwater underlying areas to which it has

been applied. It has also been detected in the initial rainwater runoff

in treated areas. However, most 2,4,5-T remains in the upper levels of

soil, and leaching is not thought to be a major transport process. The

environmental persistence of 2,4,5-T is relatively low. For example,

2,4,5-T residues in a forest reportedly declined by 50 percent in 6 weeks

and by 90 percent in 6 months. Bioaccumulation of 2,4,5-T does not

appear to be a significant environmental process.

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4.0 HYDR0GE0L0GIC INVESTIGATION

4.1 INTRODUCTION

The Hydrogeologic Section explains in detail the activities which were

performed to characterize the nature and extent of contamination at the

Del Norte Site. Surface soil, subsurface soil, and groundwater

investigations, and their results, are presented and discussed. The

purpose of this extensive program was to provide facts pertaining to the

extent of contamination at the site.

The Surface Soil Section immediately following explains soil sampling

investigations conducted to date. This includes sampling conducted by

DOHS in December 1981 and June 1982. In addition, surface soil samples

were taken at the site during two sampling periods as part of EPA's

remedial response. In late September 1984, as part of the RI/FS Work

Plan development, composite surface samples were collected both on- and

off-site to identify the scope of the potential problem. On January 22,

1985, composite surface samples were collected from on-site locations

only, based on the results from the September 1984 work. In each case,

the samples were collected at a specific location and according to

standard procedures. The samples were analyzed at a local screening

laboratory (North Coast Labs) and then selected samples were analyzed

under the EPA Contract Laboratory Program (CLP). Results of the CLP

analyses are presented.

Section 4.3 on Subsurface Geology and Soils covers three subjects.

First, the subsurface geology in the site vicinity is discussed. Then,

the results of the geophysical study of the site are given. This study

was performed in August 1984 (using electromagnetic induction) as the

first task of the RI/FS Work Plan development. Geophysics is a

non-intrusive investigation technique to locate buried drums or other

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relevant subsurface features. Finally, the subsurface soil sampling

program is presented. Subsurface soil samples were taken at the site

during two sampling programs. During Work Plan development in September

1984, nine borings were drilled on-site: eight in the centers of 50-ft

grids and one in the center of the sump. On February 3, 1985, five

on-site borings were drilled, one in the sump, three immediately

surrounding the sump area, and one in a previously trenched area.

Samples from these borings were collected according to the procedures

described below. The subsurface samples were analyzed in the same manner

as the surface samples. Results of the CLP analyses are discussed.

Data and analyses from an investigation of groundwater conditions at the

Del Norte site are presented. Section 4.4 summarizes previous regional

and on-site studies of local hydrogeology along with results of the

remedial investigation. Field investigations included monitoring well

installation; sampling of monitoring wells, auger holes, and off-site

water wells; and in-situ permeability testing. Analyses of the data are

presented, including an evaluation of groundwater gradients and field

data. Computer simulation of current and projected contaminant migration

are also presented and discussed.

Detailed field methods and complete analytical results relevant to the

hydrogeologic investigations are provided in Appendices A and B for the

surface and subsurface soils, and groundwater, respectively.

Much of the contract lab analysis data for the soil and groundwater

samples are designated "J" (estimated value) or "P" (useful for limited

purposes). These letters appear as footnotes at the bottom of the data

summary tables. Data with letter designations are usable for planning,

designing, and most legal purposes.

4-2 101 —R12—EP-BAXU-4

0296S-3

4.2 SURFACE SOILS

4.2.1 PREVIOUS INVESTIGATIONS BY DOHS: ACTIVITIES AND FINDINGS

The first soils investigation at the site was performed in June 1982 by

DOHS. At that time, a grid system was set up on-site in areas of

suspected contamination. Composite surface soil samples and samples from

soil borings were collected. Approximate locations of all the soil

samples are shown on Figure 4-1. Table 4-1 lists all of the pesticides

and metals for which the soil samples were tested, the laboratory's

minimum detection limits, and which pesticides were detected during

analysis; no metals were found.

Table 4-2 shows the concentrations of the pesticides which were

detected. Several herbicides were detected in high concentrations in the

quadrant composite surface soil samples. The herbicides were 2,4-D (up

to 2,600 ppm), 2,4,5-T (up to 3,100 ppm), and 2,4,5-TP (up to 5,300

ppm). Surface samples collected from the sump area were found to contain

the herbicides 2-4-D, 2,4,5-T, 2,4,5-TP, and the pesticides malathion and

total DDD/DDE/DDT. Pesticides ethion (up to 409 ppm) and granular thimet

were detected in sample 055, which was collected from a cardboard box.

Neither ethion nor thimet were detected in any other samples.

Subsurface soil samples were also taken by DOHS from one boring in each

of three quadrants, shown on Figure 4-1. Samples from only one boring

were contaminated. That boring was located in the sump area. 2, 4-D (up

to 50 ppm), 2,4,5-T (up to 250 ppm), and 2,4,5-TD (up to 34 ppm) were

detected between 2'8" and 3'4" below grade.

Two conclusions can be drawn from these results. Surface contamination

is not widespread over the site, and may be confined to limited areas.

The potential for vertical migration of contaminants exists, primarily in ,

the sump.

101-RI2-EP-BAXU-4

4-3

055

056

052 and 075-087

• 089-091

EXPLANATION

Cardboard box (location unknown)

Surface between drums (location unknown)

Composite soil samples

Figure 4-1 Approximate Locations of DHS Quadrants Soil Sampling, June 1982

0218s—1

Table 4-1. COMPOUNDS TESTED FOR DURING DHS SOIL SAMPLINGS

Lowest Detection Limit Reported by Labs

Compound (ppm)

*DEF 0.3 Diazinon 0.3 Dioxathion 0.5 Disyston 0.5

"Ethion 0.3 Ethyl parathion 0.5 Folex 1.0

"Malathion 0.5 Methyl parathion 0.5

"Thimet 0.5 Trithion 0.5

Total Tordon 1.0 "Total 2,4-D 1.0 "Total 2,4,5-T 1.0 "Total 2,4-DB 1.0 "Total 2,4,5-TP (Silvex) 1.0 2,6-dinitrophenol 3.0 2,4-dinitrophenol 2.0 3,4-dinitrophenol 2.0 2,5-dinitrophenol 2.0 DNOC 2.0 Dinoseb acetate 3.0 Dinocap 2.0 Pendimethalin 2.0 Benefin 2.0 Dinocep 2.0 PCB (Arochlor - 1016) 3.0 2,4-DB but ester 1.0 2,4-DB isobutyl ester 1.0 2,4,5-T ethyl hexyl ester 1.0 2,4-D isopropyl 1.0 2,4-D butyl 1.0 2,4-D propylene glycol butyl ester 1.0 2,4-D butoxy ethanol ester 1.0 2,4,5-T butoxy butanol ester 1.0 *o,p-DDD 0.7 *o,p-DDD 0.2

"Compounds detected during on-site surface sampling.

4-5

0218s—2

Table 4-1. COMPOUNDS TESTED FOR DURING DHS SOIL SAMPLINGS (continued)

Lowest Detection Limit Reported by Labs

Compound (ppm)

*o,p-DDE 0.5 *o,p-DDE 0.2 *o,p-DDT 0.6 *p,p-DDT 0.3 Aldrin 0.1 a-BHC 0.1 %-BHC 0.1 Lindane 0.1

*o-Chlordane 0.2 Dieldrin 0.2 Endosulfan I 0.2 Endosulfan II 0.2 Endrin 0.2 Endrin aldehyde 15 •Heptachlor 0.1 Heptachlor epoxide 0.1 Methoxychlor 0.1 PCNB 0.3 Perthane 0.2 Trithion 0.5 Morestan 0.8 Kepone 0.7 Tedion 0.5 Mi rex 0.5

Metals

Titanium NA Vanadium NA Chromium NA Manganese NA Iron NA Cobalt NA Nickel NA Copper NA Zinc NA Arsenic NA Selenium NA

•Compounds detected during on-site surface sampling.

4-6

0218s—3

Table 4-1. COMPOUNDS TESTED FOR DURING DHS SOIL SAMPLINGS (concluded)

Lowest Detection Limit Reported by Labs

Compound (PP<n)

Rubidium NA Strontium NA Tantalum NA Mercury NA Lead NA Bismuth NA Molybdenum NA Silver NA Cadmium NA Tin NA Antimony NA Cesium NA Barium NA Thorium NA Beryllium NA

•Compounds detected during onsite soil sampling.

0201s-1

Table 4-2. CONTAMINANT CONCENTRATIONS IN ON-SITE SOIL SAMPLES: DLL NOR IE COUNTY PESTICIDE STORAGE AREA, JUNE 1982

Parameter

052 Pit Com­

posite Surface

055

Card-Board

Box

056

Surface Between

Drums

074

Comp-poslte Surface

075

Com­posite Surface

Contaminant Concentration (ppm)

076 077 078 079

Com- Com­posite poslte Surface Surface

Com- Com­posite poslte Surface Surface

0B0

Com­posite Surface

OBI

Com­posite Surface

082

Com­posite Surface

083

Com­posite Surface

2.4-D 2,4-DB 2.4,5-T 2,4,5-TP (Sllvex) Total Chlordane o-Chlordane Ethlon Heptachlor Malathlon Thlmet Tordon Total DOD/DDE/DOT

242

409

8,310 6.7

4.6

10.9 1.4

20.6

29

76

3,100 110

1.3

12

295 153

431

7.7

2,600

1,600

420

5,300

•> I oo

2,4-0 2,4-DB 2.4.5-T 2,4,5-TP (Sllvex) Total Chlordane a-Chlordane Ethlon Heptachlor Malathlon Thlmet Tordon Total ODD/DDE/DDT

084 Com­

posite Incin­erator

Ash and

Sand

085 086 087

Pit Oil Spot Com- Com- Com­

posite poslte poslte Surface Surface Surface

210

530

1.3

14.3

31 0.5

089A 0898 090A 090B 090C

Taken at Taken at Taken at Taken at Taken at Depth Depth Depth Depth Depth

1 * 1 " 1 1 2 " 1 ' 8 " 2 ' 0 " to 1'2" to 2'0" to 2*0" to 2'3"

2'3" to 2*5"

091A 091B

Taken at Taken at Depth Depth 2'8" 3'0"

to 3'0" to 3*4"

50 33

250 7.6

130 34

- - Not detected In measurable quantities. Source: Summary of data obtained during a review of DOHS files. Berkeley, California. October 1983.

0296S-4

4.2.2 ACTIVITIES AS PART OF THE RI/FS

Surface Soil Sample Locations and Sampling Techniques

In September 1984 the first set of surface samples was taken both on-site

and off-site to determine the areal extent of contamination. A sampling

grid was set up as shown on Figure 4-2. The grid consisted of 24

quadrants, each 50 ft by 50 ft, with two additional sampling stations.

The additional two were off-site locations for the purpose of

establishing background levels of contamination. Each quadrant was

numbered as shown in Figure 4-2. A composite surface soil sample was

taken at each quadrant and at the two off-site stations. Composite

samples consisted of grab samples from six stations located along the

general east-west center line of each quadrant. The first station was

situated 4 ft from the edge of the quadrant, with the other stations

being 8 ft apart (Figure 4-2). Analysis results indicated that soil

contamination was limited to specific areas largely in the areas of

previous drum storage. No off-site surface samples were contaminated.

Based on the above preliminary investigation, more detailed on-site and

off-site surface sampling was conducted to more fully delineate surface

soil contamination. In January 1985, 18 new quadrants were sampled, as

shown on Figure 4-3. These quadrants measured 25 ft square and were all

located within the site boundaries. Six sample stations for each

quadrant were selected by using a random number generator and a

5-ft-square sub-grid. Once the sample station locations were generated,

the same stations were used in taking grab samples from all the quadrants.

In addition to the on-site quadrants, three off-site stations were

sampled. Two were sampled to supply additional background information.

The third station was located approximately 150 ft to the northeast of

the site, where, based on aerial photos, drums had once been stored. No

contaminants were detected in any of these surface samples.

101-RI2-EP-BAXU-4

4-9

Background samples were taken from Quadrants 26 and 27, shown on Figure 4-6.

Figure 4-2 Surface Sampling and Boring Locations September 1984

4-10 [

lunvtY OATC • NOvCuiin.4,

oitcm location OHAtHm tOUTHCllLr

TRENCH 1

EXPLANATION

• Drainage ditch

Fence

Boring

1" - 21*

NOTE: Background samples were taken from Quadrants. 125 and 130, shown on Figure 4-6

j£.

4-3 Surface Sample and Boring Locations January and February 1985

4- i i CUftVC Y 'OA-TC'-NO

0296S-5

Complete details on sampling techniques and equipment use are presented

in Appendix A.l.

Surface Soils Analysis Procedures

A summary chart of the soil sampling program is given on Table A.5-1 of

Appendix A.5. This table lists the sample numbers, compounds for which

each sample was tested, the screening lab or CLP lab that performed the

analysis, and the total number of samples analyzed.

In September 1984, surface soil samples were collected from each of the

24 on- and off-site quadrants (Figure 4-2). Of these, ten on-site

samples, four duplicate samples, and two background samples (16 total)

were analyzed by the CLP for 2,4-D, 2,4,5-T, and malathion. Four of the

samples (one background included) and one duplicate were further analyzed

for volatiles, semi-volatiles, and pesticides. In addition, a total of

eight samples were analyzed for TCDD (dioxin). Detailed lists of the 35

volatiles, 68 semi-volatiles, and 27 pesticides for which the laboratory

tested are given in Appendix A.5, Tables A.5-1, A.5-2, and A.5-3.

In January 1985, samples were collected from eighteen on-site quadrants

and from three off-site locations as previously described. Ten samples,

two duplicate samples and two of the background samples (14 total) were

submitted to the CLP for analysis. Each of the total 14 samples was

analyzed for 2,4-D, 2,4-DB, 2,4,5-T, 2,4,5-TP, ethion, malathion and

volatile organics. In addition, half of the samples were analyzed for

pentachlorophenol, while the other half was analyzed for semi-volatiles,

pesticides, arsenic, chromium, and copper.

Surface soil samples were numbered according to the quadrants from which

they were collected. Two composite samples were taken from each

quadrant, samples A and B. For reference in the discussion below, a

typical sample number would be 4-SS-A (Quadrant 4, Surface Sample,

sample A).

101-RI2-EP-BAXU-4

4-12

0296S-6

4.2.3 SURFACE SOILS SAMPLING RESULTS

Analytical results are presented and discussed according to the dates

when the surface samples were taken.

September 1984 Sample Analysis Results

Surface samples were collected from on- and off-site quadrants in

September 1984. Of the ten on-site samples and four duplicates which

were tested for 2,4-D, 2,4,5-T, and malathion, the Quadrant 6 sample was

the only one that showed contamination. Results indicated an average of

700 ppb 2,4,5-T. Of the four samples analyzed for volatiles,

semi-volatiles, and pesticides, Quadrants 6, 11, and 14 showed traces of

contamination (refer to Figure 4-4). No semi-volatiles were detected.

The volatile organic compound tetrachloroethene was detected at 13 ppb in

Quadrant 6 and 3.45 ppb in Quadrant 11. Other volatiles in Quadrant 6

included ethylbenzene (5 ppb) and toluene (9 ppb). Pesticides were

detected in Quadrants 6 and 14. As shown on Figure 4-4, Endosulfan I (24

ppb) and 414 DDE (0.8 ppb) were found in Quadrant 14, while Endosulfan I

(44 ppb), 414 DDT (59 ppb), and heptachlor (23 ppb) were found in

Quadrant 6. These results indicate that contamination is limited to

specific areas within the site; Quadrants 6, 11, and 14 are such areas.

As shown, portions of land within these quadrants had been previous drum

storage areas. No TCDD (dioxin) was detected in any of the samples.

Tables 4-3 and 4-4 summarize all of the above data.

Methylene chloride, 2-butanone and acetone were found in all samples. It

should be noted that all three of these constituents were also found in

the sample blanks; methylene chloride and acetone are discounted as

contaminants because they are used as sample preparatory agents by the

laboratories. This finding applies to all other analyses in the RI which

follow.

101-RI2-EP-BAXU-4

4-13

1 2

CONCENTRATION ppb

3

SITE BOUNDARY

4

5 f I Tetrach loroethene 13 i |*Ethylbenzene 5_j

*2,4,5-T 700 •Heptachlor 23 •Endosulfan I 44 •4'4 DDT 59 •Toluene 9

7

r- -| I |

' !

J V!ump!

( } •

8

9 10 "rkJ\ i 1 1 Tetrachloroethene 3.45 i i i i i I i |

12

13 14

r n I 1

Endosulfan 1 24 [

4'4-DDE J 0.S| 1 1 i i i_ —i

' 1 IS 1 i i i i i i i i i i • i i i L 4

16

17 18 19

+ + + + + + + + + + + + + + + + + + + + + +

20

21 22 23 24

\ \ '

LEGEND

| | 50' x 50' On-site and off-site quadrants.

• Indicates an average of sample and duplicate sample(s) results are given.

r- 1 1 J Indicates previous drum storage area. + + + .

+ + ++ Indicates previous trench area.

Notes: a Soil borings drilled 10' deep in each on-site quadrant, and in the sump. Results on Figure 4-8.

• Composite surface soil samples taken from each quadrant.

Figure 4-4. CONTAMINANTS DETECTED IN SURFACE AND SUBSURFACE SOILS, SEPTEMBER 1984 SAMPLES

4-14

OT 05s —4

Table 4-3. CHLOROPHENOXY HERBICIDES IN SURFACE AND SUBSURFACE SOILS BY CLP: SEPTEMBER 1984 SAMPLES

Sample Identification Concentration (PPb)

Number 2,4-D 2,4,5--TP 2,4,5 -T Malathion

06-SS-A N.D. N.D. 600 J N.D.

06-SS-A N.D. N.D. 800 JJ N.D.

25-1-2 14,000 N.D. (<10) 16, 000 N.D.

25-2-4 N.D. N.D. 60 J N.D.

Notes

• N.D. = Not detected at a detection limit of 0.1 pg/g (ppm)

• 1. None of these constituents were detected in the following samples:

01-SS-A 20-SS-B(D) 15-1 -2

02-SS-A 23-SS-A 15-2-3

02—SS—B(D) 26-SS-A 18-1-2

04-SS-A 27-SS-A 19-2-2

11-SS-A 6-1 -2 25-4-2

12-SS-A 7-1-3 Method Blank

14-SS-A 10-1 -3

15-SS-A 11-1-2 (0 = Detection)

19-SS-A 14-1 -1

20-SS-A

J = Data usable for planning purposes

4-15

0293s—1

Table 4-4. VOLATILE AND SEMI-VOLATILE ORGANICS AND PESTICIDES IN SURFACE AND SUBSURFACE SOILS: SEPTEMBER 1984 SAMPLES

Sample Identification Number Constituent Concentration (ppb)

06-SS-A Toluene 13 Heptachlor 23 Endosulfan I 45 4,4'-DDT 52

06-SS-B Tetrachloroethene 13 Toluene 5J Ethylbenzene 5J Total Xylenes 13 Heptachlor 22 Endosulfan I 43 4-4'-DDT 66

11-SS-A Tetrachloroethene 3.45

14-SS-A Endosulfan I 24 4-4'-DDE 0.8 J

15-1-2 Tetrachloroethene 4.4 J Heptachlor 1.6 Endosulfan I 68

25-1-2 Toluene 13 1,2-Dichloropropane 130 Chrysene 1300J Pentachlorophenol 66003 Phrenanthene 7 50J Fluoranthene 6703 Pyrene 7503 Benzo(b) fluoranthene 1800J Benzo(k) fluoranthene 1800J Benzo(a) pyrene 13003 Endosulfan I 520 Endrin 47

27-SS-A Tetrachloroethene 12 (Background) Toluene 11

Ethylbenzene 6.0 Total Xylenes 19

Notes

• Methylene chloride was found at an estimated concentration of 5 ppb in blanks, acetone was found in blanks at concentrations of 10 and 44 ppb, and 2-butanone was found in blanks at an estimated concentration of 10 ppb. None of the concentrations of these compounds is given for the samples.

• J = value is estimated. 4-16

0296S-7

January 1985 Sample Analysis Results

In January 1985, fourteen surface soil samples were collected from

eighteen on-site quadrants. Eight quadrants were contaminated as shown

on Figure 4-5. Herbicides, pesticides, volatiles, semi-volatiles,

pentachlorophenol, arsenic, chromium, and copper were detected in limited

areas throughout the site, especially where drum storage areas had been.

Table 4-5 summarizes the results from herbicide, ethion, malathion, and

pentachlorophenol analyses. No ethion or malathion was detected. Table

4-6 summarizes the volatiles, semi-volatiles, and pesticides detected ih

the surface soils. Table 4-7 summarizes the arsenic, chromium, and

copper results.

Five of the surface samples, a duplicate sample, and a blank sample were

analyzed for arsenic, chromium, and copper. The results are reported on

Table 4-7. All three metals were detected. Arsenic and copper were

detected at low average concentrations of 13.3 ppm and 25.4 ppm,

respectively. Chromium concentrations were significant. Values of total

chromium ranged from 193 ppm to 254 ppm. Since such a limited number of

surface samples were analyzed for the three metals, no generalizations

can be made concerning the source and extent of contamination. However,

the presence of 232 ppm chromium in the background and subsurface samples

may be an indication that the contamination is more widespread, and

probably not associated with the pesticide storage activities.

Discussion

The discussion of surface samples which follows includes data from the

September 1984 and January 1985 sampling programs. Herbicide and

pesticide contamination is discussed, followed by volatile and

semi-volatile contamination. Surface soil background sample results are

discussed last.

101-RI2-EP-BAXU-4

4-17

r

I 00

CONCENTRATION ppb

101

12.4*0 1,360 l I 1,1,2,2 Tetreehloroethane 04 | Tatrachlotpeihene 27 I HaptachSor 20,000 I Chlordan* 46,000 ! Ar»r»lc 15,400

Chromkim 201,000 Copper 21,000

106

V \

SITE BOUNDARY

tot . "W ^ ?T

2,4-0 2.4A-T

~i «fj

106

2,4 A-t 2,000

Mi

119

iS>

2^00 2.4J-T 2AA-T0

7,100 2,100

30,000 1,600

107

2/1-0 1AA-T

240/80 110/120'

(8M Llet beta*)

106

in

114

117

2,4-00 2,4,6'T I

210 oob 240

1,1 OlehldrMthin* 37 1.1.1 TrteMoreethaite 7 1.1,2,2 Tetreehloroethane 81 TetriwMewthene 52 Anenk | 16,800 Chrqmlurh | 218,000

7 +

• • • 4 • 7 • • + -+ +

104

1,1,2,2 Tevechloroethana Tetiachkwue tliene Arsenic 1 Chromium !

90 1, 100

37 17

10. 600 237,000 20.000

112

116

2.4J6-T Pentschlorophenol

90/NO* 1500/1400*

118

¥ ' + + > - + > ' + " + • + • + +

CONTAMINANTS IN SURFACE SAMPLE QUADRANT 107, ppb

1,1,2,2 Tetreehloroethane Tttrachloroethene Fluorena Phenanthrene Fluoranthene Pyrene Be hio U) Anthracene Benio Ik) Fluoranthene Berwo la) Pyrene 4, 4*-ODD 4, 4' DDT Arsenic Chromium Copper

Samps*/Dyp#eose 31 (70) 16 (42)

610 (N/0) 16,000 (N/O) 11.000 (N/0) 12,000 (N/O) 1.400 (N/O)

840 (N/b) 320 (N/O)

37 N/p) 600 (N/O)

13,200 11,7# 214,000 204.000 22,000 33,000

CONTAMINANTS IN OPF-8ITE QUADRANT 124, ppb

1.1 ji Tatrashktoothow* 7 Tstfeohleroathene 7 Afeenk 9,200 Chromium 191,000 Cppp* 27/XX)

LEGEND

I I 25'x 26'On-site quadrants

• Sample/Duplicate Results r- i

Indicate* prevlout drum storage area + + +

7 + + 4 I n d i c a t e s p r e v l o u t t r e n c h a r e a

N»»»! • CbrftPb«ta surface templss were when |h *H quadrants.

• Amn^ CbromlMm, *rM Copper were anatyxed only In

FlflU»4^. CONTAMINANTS DETECTED IN SURFACE SOILS, JANUARY 1985 SAMPLES

0293S-5

Table 4-5. HERBICIDES, PESTICIDES AND SOIL: JANUARY 1985 SAMPLES

PENTACHLOROPHENOL IN SURFACE

Sample Identi­fication

Number Constituent Concentration

(ppb)

101-SS-A 2,4-D Heptachlor Chlordane

1.300P 25.000P 48.000P

102-SS-A 2,4-D 2,4,5-T

850P 140P

103-SS-A 2,4-D 2,4, DB 2,4,5-T 2,4,5-TP

7,1 OOP 2,1 OOP

39.000P 1.600P

106-SS-A 2,4,5-T 2,900P

107-SS-A 126-SS-A (Duplicate)

2,4-D 2,4,5-T 4,4' ODD 4,41 DDT

240P HOP

37P 500P

(Duplicate) 80P

120P N/D N/D

110-SS-A 2,4-D 2,4,5-T

90P 1.100P

115-SS-A 2,4,5-T Pentachlorophenol

90P 1.500P

(Duplicate) N/D

1,400P

117-SS-A 2,4-D 2,4-DB 2,4,5-T

21 OP 600P 240P

Notes

• Contaminants were not detected in these samples:

116-SS-A 125-SS-A (Background) 124-SS-A 130-SS-A (Background)

• P = This data usable for planning purposes.

4-19

0293S-2

Table 4-6. VOLATILE AND SEMI-VOLATILE COMPOUNDS IN SURFACE SOIL: JANUARY 1985 SAMPLES

Sample Identi­fication Concentration

Number Constituent (ppb)

101-SS-A 1,1,2,2 Tetrachloroethane 64 P Tetrachloroethene 27P

(Duplicate) 107-SS-A 1,1,2,2 Tetrachloroethane 31 P 70P 126-SS-A Tetrachloroethene 16P 42P (Duplicate) Fluorene 51 OP N/D

Phenanthrene 15,000P N/D Fluoranthene 11,000P N/D Pyrene 12,000P N/D Benzo(a) Anthracene 1,400P N/D Chrysene 1,600P N/D Benzo(k) Fluoranthene 640P N/D Benzo(a) Pyrene 370P N/D

110-SS-A 1,1,2,2 Tectachloroethane 37P Tetrachloroethene 17 P

117-SS-A 1,1 Dichloroethane 37P 1,1,1 Trichloroethane 7P 1,1,2,2 Tetrachloroethane 81 P Tetrachloroethene 52P

124-SS-A 1,1,1,2 Tetrachloroethane 7P Tetrachloroethene 7P

125-SS-A 1,1 Dichloroethane IIP (Background) 1,1,2,2 Tetrachloroethane 114 P

Trichloroethene 13P Tetrachloroethene 69P

Notes

• N/D = not detected.

• Semi-volatiles di-n-butyl phthalate and bis(2-ethylhexyl) phthalate were found in surface samples 101, 107, 110, 124, 125, and 126 at concentrations of 600 - 4000 ppm. Results were not recorded above because the laboratory indicated that this contamination might be due to the lab blank.

• Methylene chloride and acetone contamination are not reported since these compounds were used in sample preparation.

• P = Data usable for planning purposes.

4-20

0293S-3

Table 4-7. ARSENIC, CHROMIUM, AND COPPER IN SURFSACE SOILS: JANUARY 1985 SAMPLES

Arsenic (P) Chromium (V) Copper (P) Sample (ppm) (ppm) (ppm)

101 15.4 201 21 107 13.2 214 22 126 (Dup 107) 13.7* 254 33 110 10.6 237 (20) 117 15.8 218 24 124 9.2 193 27 125 (Background) 14.9 232 (5)

Notes

* Spike did not meet accuracy criteria

( ) Value in brackets indicates that the result is a value greater than or equal to the instrument detection limit but less than the contract required detection limit.

P = Results are usable for planning purposes.

V = Results are valid.

4-21

0296S-8 ^

Herbicide and pesticide results can be compared with results previously

obtained by DOHS. Herbicides and pesticides were detected only on

on-site surface soil samples. Of the 27 pesticides for which September

1984 and January 1985 surface samples were analyzed, only 4 were

detected: heptachlor, chlordane, DDT, and DDD. Most of the herbicides

and pesticides which were detected in June 1982 by DOHS were also

detected in the remedial investigation. Table 4-8 compares the highest

level of herbicide and pesticide contaminants found by DOHS with the

highest level of contaminants found in the remedial investigation. With

the exception of chlordane and heptachlor, the 1982 DOHS results are

several orders of magnitude greater than the recent results. One reason

for this is that the DOHS sampling program is designed to identify the

areas of highest concentration, while the sampling program in the

remedial investigation was designed to identify broader areas with

sufficient contamination to require cleanup. In addition, degradation or

transport of the herbicides and pesticides would have reduced the

concentrations over the years.

Analyzing for volatiles and semi-volatiles was not included in the 1982

DOHS program. Figures 4-4 and 4-5 and Table 4-6 show the volatiles and

semi-volatiles detected during the remedial investigation program. Of

the 103 total volatiles and semi-volatiles for which the surface samples

were analyzed, only 16 were detected. The highest concentration of a

volatile or semi-volatile was phenanthrene at 15,000 ppb (15 ppm). Of

the 13 surface samples which were analyzed in September 1984 and January

1985, six contained the volatile organic solvent, tetrachloroethene. The

concentrations ranged from 7 to 27 ppb. Five of the samples contained

1,1,2,2-tetrachloroethane in concentrations from 7 to 64 ppb. No other

volatiles or semi-volatiles appeared with such consistency. Other

compounds were detected in only one or two samples.

Two off-site background surface samples were collected during each of the

September and January sampling programs. Their locations are shown on

101-RI2-EP-BAXU-4

4-22

0293S-6

Table 4-8. COMPARISON OF PAST AND PRESENT SURFACE SAMPLE ANALYSIS RESULTS

Highest Level Detected Highest Level Detected Contaminant during DHS Program (ppb) during RI (ppb)

6/82 9/84 & 1/85

2,4-D 2,600,000 7,1 OOP 2,4-DB 4,600 2,1 OOP 2,4,5-T 3,100,000 39.000P 2,4,5-TP 5,300,000 1,600P Chlordane 10,900 48.000P Heptachlor 20,600 25.000P Total ODD/ 31,000 NT

DDE/DDT DDT NT 500P DDE NT 0 ODD NT 37P Endosulfan NT 45P Ethion 409,000 ND Malathion 242,000 ND

Notes

NT = Contaminant not tested for.

ND = Contaminant not detected.

P = Data usable for planning purposes.

4-23

0296S-9

Figure 4-6. None of the background sample analyses showed the presence

of herbicides, pesticides, or semi-volatiles. Two of the sample results

did show volatiles. The September background sample 27-SS-A, collected

150 ft west of the southwest corner of the site, contained low levels of

tetrachloroethene (12 ppb), toluene (11 ppb), ethylbenzene (6 ppb), and

total xylenes (19 ppb). All of these constituents (except xylenes) were

detected in on-site surface samples at very similar concentrations.

Xylenes were not detected in on-site samples. The January background

sample 125-SS-A, collected approximately 150 ft northwest of the

northwest corner of the site, contained 1,1-dichlorethane (11 ppb),

1,1,2,2-tetrachloroethane (114 ppb), trichloropropane (13 ppb), and

tetrachloroethene (69 ppm). The 1,1,2,2-tetrachloroethane concentration

was almost two times that of the highest concentration found in the

on-site samples. In addition, the tetrachloroethene concentration was

17 ppb higher than the highest concentration found in an on-site sample.

These results are summarized in Tables 4-4 and 4-6. It is unlikely that

these volatiles migrated to their locations from the Del Norte Pesticide

Storage Area. It is more likely that the volatiles are the results of

another past activity.

Conclusions

Several conclusions can be drawn from the surface soil sampling and

analytical results presented in the previous sections:

(1) Surface soil contamination at the Del Norte Site was detected in

specific areas on-site. These areas and the contamination are

located mainly in the northern half of the site where drum

storage areas existed.

(2) Organic compounds detected in surface soils are herbicides,

pesticides, volatiles, and semi-volatiles. Refer to Figures 4-4

and 4-5 for pictorial views of contaminant names, locations, and

concentrations.

101-RI2-EP-BAXU-4

4-24

125-SS-A (Open Area

300' 26-SS-A (Open Area)

27-SS-A * (Vegetated)

150'

•DEL NORTE COUNTY PESTICIDE STORAGE AREA

n r 130-SS-A (Open Area)

WASHINGTON BLVD.

100 I

200 I

feet

KEY • September 1984 Background

Surface Soil Sample • January 1985 Background

Surface Soil Sample

Figure 4-6. LOCATIONS OF BACKGROUND SAMPLES FOR SEPTEMBER 1984 AND JANUARY 1985 SURFACE SOIL SAMPLING PROGRAMS

4-25

0296S-10

(3) There are no areal patterns as to the level of contamination or

the specific compounds or groups of compounds found on the site.

(4) The spread of surface contaminants off-site by wind or runoff

was not detected. Limited contamination of off-site surface

soils has occurred, and is due to prior activities in the

vicinity of the site.

(5) Selected surface soil samples were analyzed for arsenic,

chromium, and copper. Results are summarized as follows:

(a) The three metals were detected in all on-site samples and

the background sample analyzed.

(b) The ranges of concentrations of the metals are:

4.3 SUBSURFACE GEOLOGY AND SOILS

4.3.1 SUBSURFACE GEOLOGY _

Three principal geologic units underlie the study area. They are, from

oldest to youngest (and bedrock to surface), undifferentiated

Jurrasic-Cretaceous age rocks, the St. George Formation, and the Battery

Formation (see Figure 4-7).

The Jurassic to Cretaceous age strata beneath the site vicinity consist

of undifferentiated, highly deformed sandstone, shale, chert,

arsenic

chromium

9.3 ppm - 15.8 ppm

193 ppm - 254 ppm

5 ppm - 30 ppm copper

(c) Data for the metals is inadequate to determine the full

areal extent of metals contamination.

101-RI2-EP-BAXU-4

4-26

Of •p-I to

r Qb A

kv v v \N

rj-rrn vJKuM « tr " 71

ALLUVIAL FAN DEPOSITS POORLY SORTED ANGULAR ROCKS IN A SILTY CLAY MATRIX. POORLY PERME­ABLE, BUT MAY YIELD SUFFICIENT WATER FOR DOMESTIC WELLS.

BATTERY FORMATION COMPACT MARINE TERRACE DEPOSITS OF FINE SAND AND CLAY. POORLY TO MOD­ERATELY PERMEABLE, GENERALLY YIELDS ONLY SMALL QUANTITIES TO WELLS.

6T. GEORGE FORMATION CONSOLIDATED MARINE SAND AND CLAY-STONE. UNDERLIES SOUTH ONE-HALF OF AREA BENEATH BATTERY FORMATION. DOCS NOT YIELD WATER TO WELLS.

BEDROCK SERIES UNDIFFERENTIATED SERIES OF CONSOL­IDATED AND HIGHLY DEFORMED SAND­STONE, SHALE, CHERT, CONGLOMERATE, SERPENTINE, AND VARIOUS METAMORPHIC ROCKS. UNDERLIES ENTIRE AREA AT DEPTH. ESSENTIALLY IMPERMEABLE AND YIELDS LITTLE OR NO WATER TO WELLS.

Source: State of California, 1966

Fjgure 4-7. Geologic Section Through the Del Norte Site

0296s—11

conglomerate, serpentine, and various metamorphic rocks. Depth to these

bedrock units is probably between 180 to 250 ft. They have little or no

interstitial porosity and are not a significant source of water supply.

Marine sediments of the St. George Formation overlie the Jurassic-

Cretaceous bedrock. The St. George Formation is composed of Tertiary age

consolidated marine sand and claystone. Back (USGS, 1957) described

these sediments as "highly unfavorable for the development of a deep

water supply near Crescent City." Depth to the St. George Formation

beneath the site is approximately 30 ft. The thickness of the St. George

Formation is probably between 150 and 200 ft.

The sedimentary units of the Battery Formation over lie the St. George

Formation and extend to the ground surface. The Battery Formation is

composed of poorly consolidated to unconsolidated Quaternary terraces

deposited by the Smith River, which discharges to the Pacific Ocean to

the north of Crescent City. The Battery Formation sediments are

typically comprised of fine to medium-grained clayey, silty sands with

occasional pebble layers. Organic material is common as evidenced by

dark brown to black color and actual fragments of organic matter, as

would be expected in a river-estuarine environment of deposition.

Locally, the Battery Formation yields water supplies adequate for

domestic and limited irrigation use. Permeability of the Battery

Formation is decreased by the typically high clay content.

4.3.2 PREVIOUS SUBSURFACE SOILS INVESTIGATIONS BY DOHS

As shown in Figure 4-1, shelby tube samples were collected at stations

089, 090, and 091 to maximum depths of 2 ft, 2 ft-5 in., and 3 ft-4 in.,

respectively. No subsurface contamination was detected at stations 089

and 090. Sampling station 091 was located in the on-site sump and was

found to be contaminated with 2,4-D, 2,4,5-T, and 2,4,5-TP to the maximum

depth of the sample (3 ft-4 in.). These data indicated that the sump is

a source for vertical migration of contaminants through the soil. The

101-RI2-EP-BAXU-4

4-28

0296s—12

Quadrant 075 (from which boring 089 was taken) had a composite surface

soil sample that contained 29 ppm 2,4,5-T. Quadrant 078 (from which

boring 090 was taken) had a composite surface soil sample that contained

295 ppm 2,4-D.

4.3.3 SUBSURFACE SOIL SAMPLING AS PART OF THE RI/FS

Geophysical Study

In August 1984, a geophysical study was performed at the Del Norte Site.

A terrain conductivity meter (which uses electromagnetic induction) was

used to measure subsurface electrical properties to locate any

underground objects, previously excavated areas, or potential paths of

migration for contaminants. Appendix A.4 contains all of the details of

this study, including information regarding equipment, field procedures,

and results. The site scan revealed no objects that were buried

underground. The conductivity gradient, made from conductivity

measurements, indicates material transport occurs towards the south and

southeast directions.

Selection of Subsurface Soil Sample Locations

Subsurface samples were taken from borings drilled during September

1984. Refer to Figure 4-2 for the sampling station locations.

Subsurface soil samples were taken from nine 10-ft borings located in the

center of each of the eight on-site quadrants (50-ft square) with the

additional boring located in the sump. The borings were numbered

according to their respective quadrant numbers with the exception of the

sump, which was designated as boring 25. The purpose of this sampling

and subsequent analysis was to identify the extent of subsurface

contamination.

Five additional soil borings were made on February 3, 1985, based on the

results from the September subsurface sample analysis. One boring, about

101-RI2-EP-BAXU-4

4-29

0296s—13

20 ft deep, was made in the middle of the sump area (Boring 119 on

Figure 4-3) while three 10-ft borings were made around the perimeter of

the sump, spaced 120° apart. The fifth boring (Boring 123) was drilled

to a depth of 15 ft in a previously trenched area in the southern part of

the site, identified from historic aerial photos subsequent to the

September 1984 investigation.

Subsurface Soil Sampling Procedures

Subsurface soil samples were extracted from borings drilled in September

1984 and February 1985. Borings were drilled with a hollow stem auger,

and samples were obtained with a split spoon sampler with thin inner

sleeves. Details on the sampling procedure are given in Appendix A.2.

Boring logs for these sampling programs can be found in Appendix A.6.

Subsurface sample numbers were assigned on the basis of the boring

number, the drive number, and the number of the samples extracted from

the drive. For example, sample 119-1-2 is the second sample taken from

the first drive of boring 119. Depths in feet below grade which

correspond to drive and sample number are shown on Figure 4-8.

Subsurface Soil Analysis Procedures

In September 1984, nine 10-ft borings were drilled. Eight of these were

centered in on-site quadrants. The ninth was positioned in the sump area

(Figure 4-2). The contract lab tested 12 samples for the herbicides

2,4-D, 2,4,5-T, 2,4,5-TP, and malathion. Two of the 12 were tested for

volatiles, semi-volatiles, and pesticides. One of the two was also

analyzed for TCDD (dioxin).

In February 1985, subsurface samples were taken from five borings as

previously discussed, and shown on Figure 4-3. Three sets of samples

were collected from the February borings. In general each set of samples

101-RI2-EP-BAXU-4

4-30

OD o K UJ

Ui -J >*a. I< I Q «5 2:

1 - 1

1-2 (i-)

1-3 <1.4*1

14 (16*)

2-1 (2-2'>

2-2 <2.5*)

2-3 (3*) 2-4 (33*)

3-1 (3.7*)

3-2(4')

3-3 (4.4*)

3-414.8*)

4-1 (8.7*) 4-2 (9*)

4-3 (9:4*)

4 (9.8*1

DATE

BORING NO.

1 -

9/84 9/84 2/85 2/85 2/85 2/85

Note: All retulti are in ppb.

15 25 119

4 -

[" Tetrachloroethene 4-4 •-j Heptechlar 1.6

|_ Endosulfan I 68

O N/D

7 - : ?

8 -

9 -

10 -

2,4D 14,000 2,45-T 16.000 Endosulfan 1 520 Endrln 47 Pentachlorophenol 6,600 1,2 Dichloropropene 130 Toluene 13 Crysene 1,300 Phrenanthene 750 Fluoranthene 670 Pyrtne 750 Benso(b) Ruorathene 1,800 Benso(k) Fluorathene 1600 Benzole) Pyrene 1,300

121 122 123

-0 2,4-D 2.4J5-T

N/D 60

Arsenic Chromium Copper

14J00 202,000 31500

Arsenic Chromium Copper

/ t

'm,

2.4D 14,100 2,45-T 12,400 Pentachlorophenol 26500

: 12 Dichloropropene 6,451 Toluene 67 Chlorobenzene 170 Ethyttaenzene 109

~2,4D 16500 Te trechioroe thene 19 2,45-T II5OO Toluene 206 Pentachlorophenol 20300 Chharobe nze ne 378 12 Dichloropropene 9.703 Ethylbenzene- 506

: Cis 1 -3 Dichloropropene 25

2.4D 9.000 12 Dichloropropane 16 2,45-T 7,400 Total Xylenes 14 2.45-TP 130 2,4 Dictator ophenol 1200 Pentachlorophenol 65500 Nepthalene 1.400

: 1-3Dichloropropane 13 2 Mailry-Nepthalene 580 : 163 Trichloroproparae 180 Phenemhiene 1,000 __2,3,45 TetracMorophenot 370500 Di-o-butylphthalate 4300

_2.4D 1500 2,45-T 850 12.3Trichloropropane 2T

: 23.45 Tehechlorophenof 17500 13 Dichkxoprapene -7

' 1,123 Tetracbloroethane 21

O N/D

(14.4*) (14.6*)

(15*)

O-l 19-5-2 -119-5-3

CM 19-64,-L N/D

12 Dicbloroprapene Arsenic Chromium Copper

15 10,400

180,000 16.000

O N/D

| Arsenic [Chromium [Copper

[l d-Trichiarapiopane-[ 12 Dichloropropane

14,400 173500 13,000

3 22

qI V2" Dichloropropene [_ToTuene

178 11

Arsenic Chromium Copper

. — j 1.122 Tetrachloroettu • [Di-n-butylphthaliu

14J500 276,000 30500

at 5 4.4O0

O N/D

O N/D

Arsenic 14300 Chromium 236500

^Copper 9,000 . . -

Di-n-butyiphthatste 3500 4,4' ODD 60-rArsenic 14300 -Chromium 236500 Copper 9.000

LOCATION OF BORING WITH R ESPECT TO SITE PLOT PLAN

"

January 1985 Quadrants \

•**13O/J? 322

123 15 • X-rtr— -Sump

• : (Trench Area)

' • No contaminants detectedin timbering.

BORINGS 15 AND 25 9 Analysed for 2.4D; 2,45-T; Melethion, Volatile*,

Semi-Voletlles end Pesticides O Analysed only for 2,4-D; 24 A-T; end Melethion

N/D Nothing detected:

BORINGS 119 123 • Analysed for 2,4D; 2.4DB; 2.4S-T; 2,4,5-TP; Ethion,

Melethion. Volatile*, Seml-Voletllet, 1,3 Dichloropropene. 123 Trichloropropene, end 2,3,4,6 Tetrtchiorophenol, Pentachlorophenol

O Analysed for 2,4D; 245-7: Pentachlorophenol, Voiethet

* Analysed for Arsenic, Chromium .Copper only. Background (sample 132-34) contained 11,300 A;sanlc,_277,000 Chromium, and Copper 5,000

N/D Nothingdeiacied Figure 4-8. CONTAMINANTS DETECTED IN SUBSURFACE SOILS

4-31

0296S-14

was taken at a different level below grade: 2.6 feet (i.e., 119—2—2),

4.6 feet (119-3-3). and 5 feet (119-3-4). One set of nine samples was

analyzed for 2,4-D, 2,4-T, pentachlorophenol, and volatiles. The second

set, consisting of seven different samples plus one background sample,

was analyzed for 2,4-D, 2,4-DB, 2,4,5-T, 2,4,5-TP, ethion, and

malathion. The same set of seven plus the background was sent to a

different contract lab to be analyzed for volatiles, semi-volatiles,

pesticides, pentachlorophenol, 1-3-dichloropropane, 1,2,3-trichloro-

propane, and 2,3,4,5-tetrachlorophenol.

In the September 1984 subsurface sampling, pentachlorophenol, a common

wood preservative, was detected in a subsurface sample from the sump. It

was decided at that time that a compound used in the salt-treating of

wood, called chromated copper arsenate (CCA), should also be tested for.

In the February subsurface sampling program, a third set of samples plus

a new background sample was analyzed for total arsenic, chromium, and

copper. Refer to Appendix A.5 for the chart which summarizes this

information.

4.3.4 DISCUSSION OF SUBSURFACE SAMPLE RESULTS

Analytical results are discussed according to the dates when the

subsurface samples were collected.

September 1984 Sample Analysis Results

In September 1984, eight 10-ft borings were drilled in the center of the

on-site quadrants, and one boring was drilled in the sump area (Figure

4-2). Analytical results from the screening laboratory showed that 2,4-D

and 2,4,5-T were not detected in subsurface soils in the quadrant

samples; however, both herbicides were found in the sump samples. These

results provided the basis for selecting samples to be analyzed by the

EPA CLP lab. One subsurface sample was taken from each quadrant boring

at depths ranging from 1 to 2.5 ft below grade. In addition, one sample

101-RI2-EP-BAXU-4

4-32

0296s—15

at 3 ft (from Quadrant 15) and 2 samples at 3.3 ft at 9.3 ft (from the

sump) were analyzed by CLP. All of these samples were analyzed for

2,4-0, 2,3,5-T, 2,4,9-TP, and malathion. The results are shown on Figure

4-8 and on Table 4-3. None of these constituents were detected in

quadrant samples; the herbicides 2,4-D and 2,4,5-T were detected in the

sump samples. As shown on Figure 4-3, the concentrations of the

herbicides decrease with depth. At 1 ft below grade, 2,4-D was

14,000 ppb, but it was not detected at 3.3 ft and 9.3 ft below grade.

The 2,4,5-T was 16,000 ppb at 1 ft, 60 ppb at 3.3 ft, and was not

detected at 9.3 ft below grade.

Samples from Quadrant 15 and from the sump at 1 ft below grade were also

analyzed for volatiles, semi-volatiles, and pesticides. The results from

these analyses are shown on Figure 4-3 and summarized on Table 4-4.

Pesticides were detected in these analyses; heptachlor (1.6 ppb) and

endosulfan I (68 ppb) were detected in the Quadrant 15 sample, while

endrin (47 ppb) and endosulfan I (520 ppb) were detected in the sump

sample. Pentachlorophenol, a wood preservative, was also detected in the

sump sample at 6600 ppb. 1,2-dichloropropane was detected at 130 ppb.

Other volatiles and semi-volatiles that were detected in the sump are

shown on Figure 4-3; concentrations range from 13 to 1800 ppb.

February 1985 Sample Analysis Results

Five subsurface borings were drilled in February 1985. Four of these

were located in and around the sump area, numbered 119-122. The fifth

boring, number 123, was located in an area in the south quarter of the

site where a trench had previously been dug and refilled. (Refer to

Figure 4-3.) The analytical results from boring 119 (in the sump) will

be discussed first, followed by the results from borings 120-122 (around

the sump) and boring 123 (south end of the site). All results are

summarized on Figure 4-8 and Tables 4-9 and 4-10.

101-RI2-EP-BAXU-4

4-33

0293S-7

Table 4-9. HERBICIDES, PESTICIDES, PHENOLS AND CHLORINATED ORGANICS* IN SUBSURFACE SOIL: FEBRUARY 1985 SAMPLES

Sample Identification Number Constituent

Concentration (PPb)

119-1-4 (A) 2,4-D 14,100 P (A) 2,4,5-T 12,400 P Pentachlorophenol 25,500 P

119-2-2 (A) 2,4-D 16,800 P (A) 2,4,5-T 11,800 P Pentachlorophenol 20,300 P

119-2-4 (B) 2,4-D 9,000 P 2,4,5-T 7,400 P 2,4,5-TP 130 P 1,3-Dichloropropane 13 P 1,2,3-Trichloropropane 180 P 2,4 Dichlorophenol 1200 P 2,3,4,5-Tetrachlorophenol 370,000 P Pentachlorophenol 65,000 P

119-3-4 (B) 2,4-D 1,000 P 2,4,5-T 850 P 1,2,3-Trichloropropane 21 P 2,3,4,5-Tetrachlorophenol 17,000 P

121-3-4 (B) 1,2,3-Trichloropropane 3 P

123-3-4 (B) 4,4' ODD 60 J'

Notes:

A = Sample analyzed for 2,4-D, 2,4,5-T and pentachlorophenol only.

B = Sample analyzed for 2,4-D, 2,4-DB, 2,4,5-T, 2,4,5-TP, ethion, malathion, pentachlorophenol, 1-3-dichloropropane, 1,2,3-trichloropropane, 2,3,4,5-tetrachlorophenol, and pesticides.

J'= Result is estimated. Data usable for planning purposes.

* = None of these contaminants were detected in the following samples:

119-5-2 (A) 119-5-4 (B) 120-1-2 (A) 120-2-2 (A)

120-3-4 (B) 121-2-2 (A) 122-2-2 (A) 122-3-4 (B)

123-2-2 (A) 123-2-4 (A)

131-3-4 (B, Bkg)

P = Data usable for planning purposes.

4-34

0293S-8

Table 4-10. VOLATILES AND SEMI-VOLATILES* FOUND IN SUBSURFACE SOIL: FEBRUARY 1985 SAMPLES

Sample Identification Concentration Number Constituent (ppb)

119-1-4 (A) 1,2-Dichloropropane 5,451 P Toluene 67 P Chlorobenzene 170 P Ethylbenzene 109 P

119-2-2 (A) 1,2-Dichloropropane 9,703 P Cis-1,3-Dichloropropene 25 P Tetrachloroethene 19 P Toluene 206 P Chlorobenzene 378 P Ethylbenzene 505 P

119-2-4 (B) 1,2-Dichloropropane 67 P Total Xylenes 14 P Napthalene 1400 P 2-Methy1-Naptha1ene 5,800 P Phenanthrene 1,000 P Di-n-butyl-propane 4,300 P

119-3-4 (B) 1,2-Dichloropropane 7 P 1,1,2,2-Tetrachloroethane 21 P

CM 1 in 1 (A) 1,2-Dichloropropane 15 P Toluene 7 P

co 1 CM

(B) 1,2-Dichloropropane 22 P

122-2-2 (A) 1,2-Dichloropropane 178 P Toluene 11 P

1 CO 1 CM CM

(B) 1,1,2,2-Tetrachloroethane 5 P Di-n-butylphthalate 4,400 P

123-3-4 (B) Di-n-butylphthalate 3,900 P

131-3-4 (B, Bkg.) Di-n-butylphthalate 1,100 P

A = Sample analyzed for volatiles only B = Sample analyzed for volatiles and semi-volatiles * None of these contaminants were detected in the following samples:

120-1-2 (A) 120-3-4 (B) 123-2-2 (A) 120-2-2 (A) 121-2-2 (A) 123-2-4 (A)

P = Data usable for planning purposes.

4-35

0296s—16

Herbicides, phenols, and 1,2,3-trichloropropane were detected in the sump

boring 119 as shown on Figure 4-8 and summarized on Table 4-9. No

pesticides were detected in boring 119. The types and concentrations of

contaminants varied with depth in boring 119, as summarized as follows:

Concentrations (in ppb)

Approx. Depth Below Grade (ft) 2,4-D 2,4,5-T 2.4.5-TP

Penta-chloro-Dhenol

1,2,3-trichloro-pronane

2,3,4,5-tetrachl Dhenol

1.8 14,100 12,400 NA 25,500 NA NA

2.5 16,800 11,800 NA 20,300 NA NA

3.3 9,000 7,400 130 65,000 180 370,000

4.8 1,000 850 N/D N/D 21 17,000

14.4 N/D N/D NA N/D NA NA

N/D = not detected NA = not analyzed

The maximum concentration of 2,4-D occurs at about 2.5 ft below grade

while the maximum concentration of 2,4,5-T occurs at 1.8 ft. From the

locations of maximum concentration, both 2,4-D and 2,4,5-T decrease with

depth to the point of no detection at 14.4 ft. 2,4,5-TP was detected at

3.3 ft below grade; although when the sample at 4.8 ft was analyzed for

2,4,5-TP, it was not detected. Both 1,2,3-trichloropropane and

2,3,4,5-tetrachlorophenol concentrations decrease with depth; samples

greater than 4.8 ft below grade were not analyzed for these

constituents. 1,3-dichloropropane was detected on a one-time basis in

boring 119 at 13 ppb, 3.3 ft below grade.

A variety of volatiles and semi-volatiles was detected in boring 119

February 1985 subsurface samples as shown on Figure 4-8 and on

Table 4-10. 1,2-dichloropropane, toluene, and di-n-butylphthalate were

101-RI2-EP-BAXU-4

4-36

0296S-17

the only constituents with common reoccurrences in all subsurface

borings. In boring 119, 1,2-dichloropropane concentrations decreased

with depth after peaking at 9,703 ppb, 2.5 ft below grade. 1,2-dichloro-

propane was detected at 14.4 ft below grade, but not detected at 15 ft.

In boring 119, toluene decreased with depth after peaking at 206 ppb,

2.5 ft below grade. Toluene was not detected in the sample at 15 ft

below grade.

Very few contaminants were detected in borings 120-122, located around

the sump borders. Nothing was detected in samples from boring 120 except

for the metals copper, chromium, and arsenic. 1,2,3-trichloropropane was

detected at 3 ppb from the 4.8 ft of boring 121; it had also been

detected at 21 ppb in sump boring 119 at the same depth. Toluene was

detected in boring 122 (11 ppb) at 2.5 ft below grade; it had been

detected at 206 ppb in sump boring 119 at the same depth.

Di-n-butylphthalate was detected in boring 122 at 4,400 ppb, 4.8 ft below

grade; in sump boring 119, it was detected at 4,300 ppb, 3.3 ft below

grade.

Only two constituents were detected in boring 123, on the south end of

the site. ODD was detected at 60 ppb from the 4.8 ft sample. This was

the only time a pesticide was found in February 1985 subsurface

sampling. Di-n-butylphthalate was detected at 3,900 ppb from the 4.8 ft

sample as well. Samples at depths greater than 4.8 ft were not taken

from this boring.

Eight subsurface samples were analyzed for arsenic, chromium, and copper,

and all metals were detected in all samples as shown on Figure 4-8 and

Table 4-11. Three samples were collected from boring 119 at depths below

grade of 3 ft, 4.4 ft, and 14.6 ft. Arsenic and chromium concentrations

decreased with depth, while the maximum copper concentration occurred at

4.4 ft below grade (refer to Table 4-11). Because concentrations of all

metals were detected at 14.6 ft, and samples from depths greater than

101-RI2-EP-BAXU-4

4-37

0293S-4

Table 4-11. ARSENIC, CHROMIUM, AND COPPER IN SUBSURFACE SOILS: FEBRUARY 1985 SAMPLES

Arsenic (P) Chromium (V) Copper (P) Sample (ppm) (ppm) (ppm)

119-2-3 14.7 202 31 119-3-3 14.3 188 45 119-5-3 10.4 180 16 120-3-3 23.5 308 (6) 121-3-3 14.4 173 13 122-3-3 14.5 276 30 123-3-3 14.3 236 9 132-3-4 (Background) 11.3 277 (5)

Notes

( ) Value in brackets indicates that the result is a value greater than or equal to the instrument detection limit but less than the contract required detection limit.

P = Results are usable for planning purposes.

V = Results are valid.

4-38

0296s—18

14.6 ft were not analyzed for arsenic, copper, and chromium, conclusions

cannot be made about maximum depth of contamination.

One sample was taken from each of the other four borings and analyzed for

the metals. The four samples were all taken at the same depth, 4.4 ft

below grade. Concentrations of all three metals remained fairly constant

throughout the borings 120-123. Arsenic concentrations ranged from

14.3 ppm to 23.5 ppm, chromium ranged from 173 ppm to 308 ppm, and copper

ranged from 9 ppm to 30 ppm. These values can be compared to the

concentrations of the Petals found in the sump boring 119 at the same

depth. Concentrations for arsenic (14.3 ppm) and chromium (188 ppm) fall

into the above ranges; however, copper at 4.4 ft below grade in boring

119 was 45 ppm. Because sampling was done at a single depth in the four

non-sump borings, no conclusions can be made about the relationship

between depth and concentration.

Discussion

The discussion of subsurface sample results which follows includes data

from the September 1984 and February 1985 sampling programs. Herbicide

and pesticide contamination is discussed, followed by volatile and

semi-volatile contamination. Subsurface soil background sample results

are discussed last.

As shown on Figure 4-8, samples from two of the six subsurface borings

contained herbicides. Both of these borings, numbers 25 and 119, were

located within the sump. Pesticides were also detected in borings 25 and

15. Results from the sample taken at 1 ft below grade from boring 25

showed 520 ppb endosulfan I and 47 ppb heptachlor. Results from the

sample taken at 1 ft below grade from boring 15 were 68 ppb endosulfan I

and 1.6 ppb heptachlor. Deeper samples from these borings were not

analyzed for pesticides, so concentration and depth relationships are not

known. Only herbicides were detected by D0HS in June 1982. The D0HS

took subsurface samples from three borings (Figure 4-1), and the

101-RI2-EP-BAXU-4

4-39

0296S-19

herbicides were found only in the boring by the sump. A comparison of

the DOHS results to the remedial investigation results is given in Table

4-12. The DOHS 1982 results are several orders of magnitude greater than

the recent results. One reason for this is that DOHS designed their

sampling program to identify the areas of highest concentration, while

the sampling program followed in the remedial investigation was designed

to identify broader areas with sufficient contamination to require

cleanup. Also, degradation or transport of the herbicides would have

reduced the concentrations over the years.

Analyzing for volatiles and semi-volatiles was not included in the DOHS

program. Figure 4-8 and Table 4-10 show the volatiles and semi-volatiles

detected during the remedial investigation program. Of the 103 total

volatiles and semi-volatiles for which the subsurface soil samples were

analyzed, only 17 were detected (Tables 4-10 and 4-11). The highest

concentration of a volatile or semi-volatile was 2,3,4,5-tetra-

chlorophenol at 370,000 ppb. Of the ten total subsurface samples which

were analyzed in September 1984 at February 1985, six of the samples

contained 1,2-dichloropropane in concentrations ranging from 7 to 9703

ppb. Four samples contained toluene (7 ppb - 67 ppb) and four other

samples contained di-n-butylphthalate (1100 ppb - 4400 ppb). Other

volatiles and semi-volatiles were detected in only one or two samples.

The samples collected at depths 2.5 ft and 3.3 ft below grade contained

the most number of different volatile, semi-volatile, and herbicide

constituents.

Two off-site background subsurface samples were collected during the

February 1985 program. One of the samples was taken at 1.4 ft below

grade from the Monitoring Well 6 (MW-6) boring. The other background

sample was taken 1.4 ft below grade from the MW-7 boring. (Refer to

Figure 4-9.) The subsurface sample taken from the boring of MW-7 was

analyzed for all volatiles, semi-volatiles, pesticides, and herbicides.

One semi-volatile was detected, di-n-butylphthalate. The presence of

101-RI2-EP-BAXU-4

4-40

0293S-9

Table 4-12. COMPARISON OF PAST AND PRESENT SUBSURFACE SAMPLE ANALYSIS RESULTS

Highest Level Detected Highest Level Detected Depth Below During DHS Program (ppb) During RI (ppb)

Herbicide Grade (ft) 6/82 9/84 and 2/85 (P)

2,4-D 1.1 ND 14,000 1.6 ND 14,100 2.2 ND NT 2.3 ND 16,800 2.8 50,000 NT 3.1 33,000 NT 3.3 NT 9,000 4.8 NT 1,000

below 14.4 NT ND

2,4,5-T 1.1 ND 16,000 1.6 ND 12,400 2.2 ND NT 2.3 ND 11,800 2.8 250,000 NT 3.1 130,000 NT 3.3 NT 7,400 3.8 NT 850

below 14.4 NT ND

2,4,5-TP 1.1 ND ND 1.6 ND ND 2.2 ND NT 2.3 ND ND 2.8 7,600 NT 3.1 34,000 NT 3.3 NT 130 3.8 NT ND

below 14.4 NT ND

Notes:

NT = contaminant not tested for ND = contaminant not detected

P = Data usable for planning purposes

4-41

EXPLANATION

• Private Well

• Monitoring Well

45 Groundwater Contours — April 28, 1985 (dashed where inferred)

Topographic Contour Interval — 10 feet

250 500 1000 feet —I

Figure 4-9. Monitoring Well Locations and April Groundwater Contours Del Norte County Pesticide Storage Area Site

4-42

0296S-20

this single chemical is not of concern since this is one chemical which

is very commonplace throughout the environment.

The subsurface sample taken from the boring of MW-6 was analyzed only for

arsenic, chromium, and copper. Although arsenic and copper were detected

in very low concentrations, chromium was detected at 277 ppb, which was

the second highest value detected (see Table 4-11). The presence of

chromium in the background sample is an indication that the metal

contamination is present beyond the boundaries of the site. Because of

the known history of the site and evidence from the groundwater

investigation, it is doubtful that the presence of metals in subsurface

samples is a result of activities performed at the Del Norte County

Pesticide Storage Area Site.

Conclusions

The conclusions drawn from the subsurface soil sampling and analysis

results are presented below:

(1) Subsurface soil contamination is found primarily in the on-site

sump and was also found in specific on-site areas. Sample

results from subsurface borings indicate that there is extensive

contamination in the sump to 15 ft below grade and slight

contamination in Quadrant 15 to 1 ft below grade.

(2) Organic compounds detected in subsurface soils are herbicides,

pesticides, volatile organics, and semi-volatile organics.

Refer to Figure 4-8 for a pictorial view of contaminant names,

locations, and concentrations.

(3) No off-site surface soil contamination was detected, with the

exception of arsenic, chromium, and copper.

101-RI2-EP-BAXU-4

4-43

0296s—21

(4) Select subsurface soil samples were analyzed for arsenic,

chromium, and copper. Results are summarized as follows:

(a) The three metals were detected in all on-site samples and

the one off-site background sample.

(b) The ranges of concentrations of the metals are:

arsenic 10.4 ppm - 23.5 ppm

chromium 173 ppm - 308 ppm

copper 9 ppm - 45 ppm

(c) Concentrations of the metals decreased with depth in the

one boring where several samples were taken.

(d) Data for the metals is inadequate to determine the full

vertical extent of contamination.

4.4 GROUNDWATER INVESTIGATION

Available information regarding hydrogeologic conditions in the vicinity

of the Del Norte Site includes previous regional groundwater

investigations conducted by the U.S. Geological Survey (USGS) and

California Department of Water Resources (DWR); site-specific

investigations conducted by the NCRWQCB; and hydrogeologic field

investigations, laboratory chemical analyses, and groundwater modeling

conducted as part of the EPA's remedial investigation. An evaluation of

site hydrogeologic conditions and groundwater contamination based on

these data is presented below.

4.4.1 REGIONAL HYDROGEOLOGIC SETTING

The principal water-bearing deposits in the study area are the permeable

sands and gravels in the Battery Formation. The Battery Formation is

4-44

101-RI2-EP-BAXU-4

0296S-22

composed of Quaternary terrace deposits of fine sand and clay. Locally,

the Battery Formation yields water supplies adequate for domestic and

limited irrigation use. Host wells are shallow, tapping only the upper

25 to 35 feet of sediments. Available well data shows the permeability

of the Battery Formation to average about 70 feet per day (US6S, 1957).

Specific capacities of wells completed in this formation average about 4

gallons per minute per foot of drawdown.

The water table in the area is relatively shallow. The depth to

groundwater may range from near the surface to about 20 feet below the

surface. Seasonal fluctuations in water table elevations are estimated

to be in the range of 10-15 feet.

Based on a previous USGS hydrogeologic study (USGS, 1957) on a regional

scale, the Del Norte Site is within the area of a groundwater mound. The

water table in the vicinity of the site may be locally influenced by

recharge from Dead Lake (elevation 50 ft), located about one-half mile

northeast of the site. Enhanced groundwater recharge (as a result of

grading operations that have increased soil permeability and reduced

evapotranspiration) in the vicinity of the County Airport may also

contribute to higher groundwater levels in this area.

The groundwater in the Battery Formation is classified as magnesium-

bicarbonate type, and is of generally excellent quality, with total

dissolved solids typically less than 200 parts per million (ppm).

Limited data is available concerning the hydrogeologic conditions in

strata below the Battery Formation because most local wells do not

penetrate the St. George Formation. The permeability of the St. George

Formation is unknown but, based on general geologic characteristics, is

estimated to be substantially less permeable than the Battery Formation.

101-RI2-EP-BAXU-4

4-45

0296S-23

4.4.2 HYDROGEOLOGIC SITE INVESTIGATIONS BY NCRWQCB

The NCRWQCB installed two 20-foot deep on-site monitoring wells. The

NCRWQCB oversaw the drilling, and the wells were completed in September

1982.

Samples collected at the on-site wells were contaminated with a number of

compounds, primarily herbicides and pesticides and their pesticide

degradation by-products. Compounds that were detected included 2,4-D,

2,4,5-T, and dichloropropane. The cis- and trans 3-chloro-allyl alcohol

detected are degradation byproducts of 1,3-dichloropropene, a pesticide

not identified during this analysis. Tetrachloroethylene, an organic

solvent, was also found in samples from the on-site monitoring wells.

The source of this compound is not known.

The data from the on-site monitoring wells were suspected not be

representative of actual groundwater concentrations because of laboratory

problems. The on-site wells were removed from the Del Norte Site by the

NCRWQCB in January 1984. At the same time, one new well was installed

near the center of the site, approximately 20 feet from the sump.

The NCRWQCB performed two rounds of sampling from nine off-site wells

(within 1 mile of the site) in June and August 1983. Eight of these were

active domestic wells and one was an abandoned well near the airport. An

organic solvent, 1,1,1-trichloroethane, was detected in five of the nine

tested wells at a maximum concentration of 3.1 ppb. A 1.1 ppb

concentration of 2,4-D was found in the abandoned airport well.

4.4.3 FIELD INVESTIGATION PROCEDURES

Field investigations that were conducted as part of the remedial

investigation included monitoring well installation, hand-auger sampling

of groundwater, sampling of on-site and off-site monitoring wells, and

101-RI2-EP-BAXU-4

4-46

0296S-24

in-situ permeability testing. The scope of these investigations is

described below.

Monitoring Well Installation

Nine monitoring wells were installed at the site between January 28 and

April 29, 1985. These wells were designed to aid in the delineation of

the suspected groundwater contamination plume and to establish

groundwater elevations in areas where such data was lacking. Monitoring

wells installed as part of this investigation are shown on Figure 4-8.

MW-1 was installed by the NCRWQCB in January 1984. MW-2 through MW-8

were installed the week of January 28, 1985; MW-25 and MW-26 were

installed on April 28, 1985. In addition to the nine new wells, the

observation well constructed by the NRWQCB (MW-1) and five nearby

domestic wells (MW-10 to 14) were included in the monitoring program (see

Figure 4-9).

Monitoring wells were installed in 8-inch hollow stem auger borings.

Drive samples of subsurface soils were collected at selected intervals

using a split-spoon sampler. Some difficulty was encountered in

recovering soil samples below the water table due to the unconsolidated

nature of the fine-grained, sandy formational materials. Recovered

samples were retained for physical testing. Boring logs for the

monitoring wells are included in Appendix B.l.

Monitoring wells were constructed of 2-inch PVC and are generally

screened between 5 and 30 feet below the ground surface. A filter pack

of sand was placed in the casing annulus to a height one foot above the

slotted interval. Two feet of bentonite was placed above the filter

pack, and a cement surface seal was installed above the bentonite to the

ground surface. Monitoring well specifications are shown on Table 4-13.

Development of the monitoring wells was performed by removing four to six

casing volumes of groundwater with a Teflon bailer. At the completion of

101-RI2-EP-BAXU-4

4-47

// 0(k-.

Table 4-13. MONITORING WELL SPECIFICATIONS*

Monitoring Well

Top of Casing Elevation

(MSL)

Completion Depth Below Grade

Screen Elevation (MSL)

Geologic Material at or Near Completion Depth

MW-2 45.89 30.0 15.9 - 40.9 At 28 ft: Boulder or cobble zone

MW-3 46.70 29.5 17.2 - 42.2 At 25 ft: medium grained well-rounded, well-sorted brown sand; some silt

MW-4 45.17 29.5 15.7 - 40.7 Consolidated sandy clay with abundant shell fragments

MW-5 47.93 30.0 17.9 - 42.9 Dark grey to black fine to medium silty sand; some shells

MW-6 44.65 30.0 14.7 - 39.7 At 23% ft: Fine to medium blue to dark grey sand

MW-7 43.50 30.0 13.5 - 38.5 At 28 ft: Semi-consolidated material

MW-8 47.12 30.0 17.1 - 42.1 At 32 ft: Black semi-consolidated sandy silty clay, abundant shell fragments

MW-2 5 45.31 32.5 11.3 - 36.3 Well-sorted sub-angular to sub-rounded silty clayey sand

MW-2 6 44.77 33.0 10.3 - 35.3 Blue-grey silty clayey sand

*A11 values are in feet.

0296S-25

development, the groundwater remained clouded with suspended sediment,

and approximately the lower five feet of the well was filled with silt.

The inability to remove the fine sediment is probably due to sloughing of

formational material around the casing during well construction.

After completion of the wells, a point on top of the well casing was

marked with indelible ink and the elevation of this mark was surveyed.

All subsequent water-level measurements were made relative to this

point. Horizontal locations of the monitoring wells were surveyed on

April 29, 1985. Water levels in the on-site and off-site monitoring

wells were measured on February 5, March 5, March 25, and April 28, 1985,

as shown on Table 4-14.

Hand-Augered Groundwater Monitoring Holes

Because groundwater elevations indicated flow in a southeasterly

direction and because a plume of contamination might not have been

detected with the monitoring wells MW-2 through MW-8 described in the

work plan, 13 hand-augered monitoring holes were bored during the week of

March 25, 1985. The location of these auger holes are shown on Figure

4-10. The purpose of the auger holes was to allow screening analyses of

water samples and aid in locating additional wells. The auger holes were

generally located along the site perimeter between existing MW-1,-3,-4,

and-5, and downgradient of the sump.

Test holes were bored to a depth of three to five feet using a 4-inch

inner diameter hand auger. A length of 2-inch PVC casing was inserted

into the hole, and the hole was left open for a period of 10 to 15

minutes to allow suspended sediment to settle. Water samples were bailed

from within the PVC with a Teflon bailer. The bailer was rinsed with

borehole water three times prior to sampling.

Water samples were collected in sample containers provided by the CLP

from each of 13 auger holes and from MW-1 and MW-5. A total of 21 water

101-RI2-EP-BAXU-4

4-49

7702C-3

Table 4-14. WATER TABLE ELEVATIONS (ft., MSL)*

Monitoring Well 2/5/85 3/5/85 3/25/85 4/28/85

1 — 42.71 — 42.76

2 42.38 43.39 42.16 42.35

3 41.97 42.94 43.16 41.88

4 41.575 42.60 42.83 42.15

5 42.375 43.89 — 42.65

6 41.03 42.25 38.88 41.33

7 40.41 41.49 39.54 40.05

8 42.49 43.25 43.95 42.52

10 (Airport) 45.22 46.48 47.65 45.29

11 (McNamara) 36.02 37.06 37.49 35.95

12 (Groat) 39.98 40.59 39.93 39.97

13 (Wikoff) 40.46 — 41.68 40.35

14 (Sherman) 40.63 41.73 41.88 40.80

25 — — — 41.48

26 — — — 41.91

Pond — — — 41.69

*Average of three measurements (excluding pond).

—Not measured on this date.

4-50

EXPLANATION

MW-8 • 4252 -

Monitoring wells •Water level elevation measured 04/28/85

• 41.0 mm — Groundwater contours (dashed where inferred)

12. Temporary hand-augered holes

0 L

too '

200 300 I

feet

Figure 4-10. Groundwater Sampling Locations Del Norte County Pesticide Storage Area Site

4-51

0296S-26

samples, including three duplicates and three field blanks were delivered

to the EPA Contract Laboratory.

All of the equipment and materials involved with augering and sampling

were steam-cleaned, washed with alconox, rinsed with distilled water,

rinsed with pesticide-free acetone and again rinsed with distilled water

between sampling locations.

After the PVC casing was removed, the open boreholes were backfilled with

the boring cuttings. Cuttings from the auger holes on-site and near MW-5

were placed on plastic sheeting to avoid possibly contaminating clean

surface soils. These cuttings were then used to backfill the borehole

after groundwater sampling.

Groundwater Sampling Procedures

Groundwater samples for chemical analyses were collected from MW-1

through MW-14 on February 23-24, and March 5, 1985. Samples were

collected from MW-1 and auger holes on March 25, 1985. Samples were

collected from MW-5, MW-25, and MW-26 on April 29, 1985. Approximately

three to ten casing volumes of water were removed from each well prior to

sample collection. Samples were collected by lowering a clean teflon

bailer on a nylon rope into the well to the depth of the most permeable

portion of the aquifer as determined from the well boring logs. The

bailed water samples were then transferred to sample bottles. Four

one-liter amber glass bottles were used for each sample. A second set of

samples were collected in one-liter polyethelene bottles for inorganic

analyses. A third set of samples was collected in two 40 ml glass vials

for volatile analyses. Containers were supplied by the EPA Contract

Laboratory. One field blank was also included in the sample collection

and handling process during each field trip. Sample containers were

sealed and kept in cool storage until delivered to the laboratory.

Labeling, shipment, and chain-of-custody were conducted according to the

101-RI2-EP-BAXU-4

4-52

0296S-27

requirements stated in the Project Operations Plan and EPA Region IX

Sampling Plan.

Sample identification consisted of labels with three sets of numbers or

letters. The first set of numbers was the number of the well from which

the sample was taken. The second set consisted of the letters GW which

designated it as a groundwater sample, and the third set was the

sequential number of the sample taken from that well. For example, a

duplicate sample taken from MW-5 would be identified as 05-GW-02.

The teflon bailer was decontaminated between samples by first washing

with a phosphate-free detergent solution and rinsing in tap water. This

was followed by a pesticide-grade acetone rinse and a final rinse with

deionized water. A new nylon cord was attached to the bailer prior to

collecting each sample.

In-Situ Permeability Testing

Falling head permeability tests were conducted on February 8, 1985 at

MW-2,-3,-4,-6, and-8 in order to evaluate the hydraulic conductivity of

the Battery Formation in the vicinity of the site. Two separate falling

head tests were conducted at each well to assess the reproducibility of

the test results.

The tests were performed by adding between 1 and 1.5 gallons of water to

the well, and using a pressure transducer and strip chart recorder to

record the pressure-head decay rate. The transducer and strip chart

recorder were recalibrated after each test. Water levels were recorded

until no perceptible change in head was visually detected. Analysis of

permeability using grain size analysis was also performed to check the

results of field tests.

101-RI2-EP-BAXU-4

4-53

0296S-28

4.4.4 RESULTS OF LABORATORY CHEMICAL ANALYSES

One round of groundwater sampling was conducted on February 23, March 5,

March 25, and April 28, 1985. Laboratory chemical analyses were

performed by the CLP. Appendix A.5 identifies the category of analyses

and the EPA Contract Laboratory for each round of sampling. The specific

chemical compounds within each category of compounds, and the detection

limit for each chemical compound is listed in Appendix A.5. Tables 4-15

and 4-16 show the laboratory results for volatiles, semi-volatiles,

herbicides, pesticides, arsenic, chromium, and copper detected in

monitoring wells above the EPA contract required detection limit.

The highest concentrations of volatile, semi-volatile, herbicide and

pesticide compounds were detected on-site in MW-1. The soil fumigant

1,2-dichloropropane and the herbicides 2,4-0 and 2,4,5-T were

consistently detected in MW-1 during and sampling rounds in

concentrations up to 150 ppb; 1,2-dichloropropane was detected in

concentrations up to 2100 ppb.

A number of pesticides were detected in low concentrations in MW-5,-6,

and -12. Several semi-volatile compounds were detected in February

samples of groundwater from MW-14 although none of these compounds were

detected in subsequent sampling in March 1985. A concentration of 5 ppb

of 1,2-dichloropropane was detected down-gradient of the site in MW-25.

However, analysis of a duplicate sample from MW-25 was inconsistent in

that 2,4-D was not detected but other compounds were.

Contract Laboratory results of the auger hole sampling show that

1,2-dichloropropane was detected in auger holes 1, 5, and 10, and that

2,4-D was detected in auger hole 13. Measured concentrations of chemical

compounds detected in the auger holes are not reported here because these

results are not comparable with analyses of groundwater samples from

monitoring wells. Monitoring well samples reflect the actual

concentration of contaminants in the screened interval of the Battery

4-54 101-RI2-EP-BAXU-4

0304s—1

Table 4-15. VOLATILE, SEMI-VOLATILE AND PESTICIDE COMPOUNDS IN GROUNDWATER

Location Compound 2-23-85 Concentration (ppb)a 3-5-85 3-25-85 4-28-85

MW-1 1,2-Dichloropropane 1900 1400 1200v Benzene 6 * 68v 1,3-Dichloropropane 15 * *

1,2,3-Trichloropropane 47 * *

2,4-Dichlorophenol 18 11 *

Pentachlorophenol * 24 *

2,4,5-Trichlorophenol 34 20 *

2,3,4,5-Tetrachiorophenol 66 * *

Methylene chloride * 110 *

2-Butanone * 39V *

2,4-D 26 100V 150v 2,4,5-T 68 47 V llOv 2,4,5-TP 1.2 * *

Cis-3-Chloroallyl alcohol * 17b — —

MW-17 1,2-Dichloropropane 2100 1200 1200v (duplicate Benzene 6 * •k

of MW-1) 1,3-Dichloropropane 16 * *

1,2,3-Trichloropropane 50 * * '

2,4-Dichlorophenol 15 8 *

2,4,5-Trichlorophenol 32 14 *

2,3,4-5-Tetrachlorophenol 57 * *

Methylene chloride * 62v *

2,4-D 40 82v 50v 2,4,5-T 84 41 v 11 Ov Cis-3-Chloroallyl alcohols * 20b — —

MW-5 2,4-Dichlorophenol 15 * *

2,4,5-Trichlorophenol 32 * *

2,3,4,5-Tetrachlorophenol 57 * *

Total Xylenes 6 * *

2,4-D 21 12v *

MW-18 4,41-DDE * 0.2 — —

(duplicate 4',4'-DDT * 2 —

of MW-6)

MW-12 2,4-D 0.6 * —

MW-14 Benzo(a)anthracene 7 * — —

Chrysene 8 * —

Benzo(e)fluroanthene 3 * —

Benzo(a)pyrene 6 * —

Phenanthrene 8 * —

Anthracene 3 * —

Pyrene 13 * —

4-55

0304S-2

Table 4-15. VOLATILE, SEMI-VOLATILE AND PESTICIDE COMPOUNDS IN GROUNDWATER (concluded)

Location Compound 2-23-85 Concentration (ppb)a 3-5-85 3-25-85 4-28-85

MW-25 1,2-Dichloroprane — 5

MW-17 Toluene — 46 (duplicate Xylenes — 5 of MW-25) Pentachlorophenol — 50

Napthalene — 10 Benzoic Acid — 50

MW-15 Carbon tetrachloride * * 37v * (blank) Methylene chloride * * 78v *

Chloroform * * 18v *

aAll values reported by EPA Contract Laboratories as estimated and valid for planning purposes (unless otherwise noted).

^Lack of trans isomer makes this identification tentative. *Compound not detected. —Not sampled on this date. v-Results reported as valid for all purposes.

4-56

0304S-3

Table 4-16. ARSENIC, CHROMIUM, AND COPPER IN GROUNDWATER

Location Arsenic

Concentration

Chromium

(ppb) a

Copper Location 2-85 3-85 3-85 2-85 3-85 4-85 2-85 3-85 4-85

MW-1 * 7.5 * * * *

MW-17 (MW-1 dup) * — — 22 — * — —

MW-2 18.8 17 — 190 177 — 23 22 —

MW-3 23.2 38 — 291 547 — 54 92 —

MW-4 11.5 26 — 157 247 — * 29 —

MW-5 * 22 10b 83 187 38 * 23 13 MW-6 26.1 23 — 331 355 — 71 47 —

MW-18 (MW-6 dup) 30.5 — — 420 — — 70 — — MW-7 43.3 32 — 372 226 — 88 36 —

MW-8 8.6 10 — 144 84 — * * —

MW-10 * * — * 23 — * * —

MW-11 * * — * * — * * —

MW-12 * * — 9 12 , — * * —

MW-13 * * — * 9 — * * —

MW-14 * * — 9 19 — * * —

MW-2 5 — — *b — — 104 — — 14 MW-17 (MW-25 dup) — — *b — — 165 — — 28 MW-2 6 — — nb — — 305 — — 44 MW-1 5 (blank) * —

*a * * * —— 5.9

aAll results reported by EPA Contract Laboratories as valid for all purposes, unless otherwise noted.

^Estimated value, usable for planning purposes. •Compound not detected. — Not sampled on this date.

4-57

0296S-29

Formation (5 to 25 feet below grade), while auger hole groundwater

samples may not be representative of contaminant concentrations

throughout the aquifer. However, the auger hole sampling method served

as a useful screening tool in evaluating the presence or absence of

certain chemical compounds. Laboratory results from auger holes 10 and

13 are consistent with results from adjacent monitoring wells.

Contract Laboratory results for arsenic, chromium, and copper shown on

Table 4-16 were reported as valid, with minor exception. These data

reflect widespread presence of arsenic, chromium, and copper in all

monitoring wells installed as part of this investigation (MW-2 to -8 and

MW 25-26). The reason for the general absence of detected metals in MW-1

(installed by the NCRWQCB) is presently unknown. With the exception of

MW-11, chromium was detected in the remaining domestic wells (MW-12,

MW-13, and MW—14) and in the abandoned airport well (MW-10), at levels

substantially lower than the monitoring wells.

4.4.5 ANALYSIS AND INTERPRETATION OF HYDR0GE0L0GIC DATA

There are three issues of primary concern relative to the groundwater

contamination detected at the Del Norte Site—(1) the extent of

groundwater contamination; (2) the direction and rate of groundwater

movement; and (3) the contaminant migration potentialM Each of these

issues is discussed in more detail below and in the sections to follow.

The borings for the monitoring wells showed moderately well-sorted to

well-sorted silty, fine to medium sands. Fossils encountered at a depth

of 28-30 feet are interpreted to be an indication of the top of the

Tertiary marine St. George Formation. Based on the boring logs,

MW-4,-5,-7, and -8 are believed to penetrate the entire thickness of the

Battery Formation at those locations.

101-RI2-EP-BAXU-4

4-58

0296S-30

Sieve analyses of soil samples from the monitoring wells indicate that

the Battery Formation is composed of fine to medium well-sorted sands.

Laboratory grain-size distribution analyses are included in Appendix B.

Groundwater Contours

Water level elevations for wells in the vicinity of the Del Norte Site

are shown in Table 4-14. Water levels rose approximately one foot

between February 5 and March 5, 1985. However, there were no consistent,

observed changes in water level elevations in the periods between March 5

and March 25 or March 25 and April 28. Water levels measured on April 28

were approximately the same as those observed on February 5, 1985.

Previous investigations by the USGS (1957) suggest significant seasonal

fluctuations in regional groundwater elevations; however, the three month

monitoring period during the RI was too brief to confirm this behavior.

Based on measured water level elevations, a groundwater contour map

showing April 28, 1985 conditions was constructed as shown in Figures 4-8

and 4-9. The groundwater contours suggest a mild, generally

southeasterly gradient. On a regional scale, the steepest gradients are

more southerly, towards MW-11. In the immediate vicinity of the site,

the gradient tends to decrease in an easterly direction.

Hydraulic Conductivity

The rate of groundwater movement was evaluated on the basis of estimates

of hydraulic conductivity obtained from falling-head permeability tests

conducted in the field and from laboratory grain-size distribution data.

(Hydraulic conductivity is the measure of ease with which a fluid moves

through a porous medium.)

Analytical results of the falling head tests are shown in Table 4-17,

based on an analytical procedure developed by Hvorslev (1951).

Analytical results show excellent agreement between each test from the

101-RI2-EP-BAXU-4

4-59

0218s—10

Table 4-17. HYDRAULIC CONDUCTIVITY (K) VALUES DERIVED FROM FALLING HEAD TEST DATA

K Tft/secl Well Test 1 Test 2 Average

MW-2 6 . 7 X 10"5 5 . 8 X 10"5 6 . 2 X 10"5

MW-3 4 . 5 X

tn 1 o p— 5 . 2 X 10"5 4 . 8 X 10"5

MW-4 5 . 5 X 10"5 5 . 5 X 10"5 5 . 5 X 10"5

MW-6 4 . 0 X 10"5 3 . 6 X 10"5 3 . 8 X 10~5

MW-8 1 . 0 X o i

9 . 9 X 10"5 1 . 0 X o i

4-60

0296s—31

same well and from individual wells. Sample calculations using the

Hvorslev analytical method are shown in Appendix B.4. The values of

hydraulic conductivity determined from falling head tests represent

integrated values for the entire section of the Battery Formation through

which the monitoring wells are screened. Individual horizons within the

screened interval may have a higher or lower hydraulic conductivity.

The March and Denny (1966) analysis for the calculation of the hydraulic

conductivity from grain-size distribution curves was used to analyze six

soil samples. A sample of these calculations may be found in Appendix

B.5. The results of these calculations, listed in Table 4-18, indicate

that the Battery Formation is relatively homogeneous, with hydraulic -5 -4

conductivity values ranging from 4.6 x 10 to 7.0 x 10 ft/sec.

The hydraulic conductivity values obtained from the grain-size analysis

are, as expected, consistently larger than those obtained from the

falling head tests. The differences between the hydraulic conductivity

values may be attributable to a number of factors:

• The degree of cementation and compaction present in-situ is not

considered in the laboratory grain-size analysis.

• The samples analyzed may not be completely representative of the

grain size characteristics of the entire screened interval.

The hydraulic conductivity value from sample number MW4-1-4 is probably

not representative of the aquifer material since it was collected at a

location above the water table near the ground surface. The hydraulic

conductivity value from sample MW4-5-3 could not be accurately determined

because of the poorly sorted nature of the material. The March and Denny

analysis gives the best results for a more uniform grain size. If we

disregard these two values, the average hydraulic conductivity for the -4 soils samples is 3.2 x 10 ft/sec. The average hydraulic conductivity

-5 calculated from the falling head test is approximately 6.1 x 10 . For

101-RI2-EP-BAXU-4

4-61

0218s—11

Table 4-18. HYDRAULIC CONDUCTIVITY (K) DERIVED FROM GRAIN SIZE ANALYSIS

Sample Well Elevation of USCS K Number Number Sample (MSL) Classification (ft/sec)

MW2-3-1 MW-2 25.89-26.22 SP-SM 3.9 x 10"4

MW3-3-3 MW-3 32.37-32.03 SM-SC • X o

1

MW4-1-4 MW-4 41.84-41.50 SP-SM 7.0 x 10"4

MW4-2-4 MW-4 36.50-36.17 SP-SM 2.3 x 10"4

MW4-5-3 MW-4 16.50-16.17 SM-SC 4.6 x 10-5

MW6-4-4 MW-6 21.48-21.15 SP 5.4 x 10"4

4-62

0296S-32

practical applications, the differences in hydraulic conductivity between

the falling head test values and the grain size analysis values are not

significant. What is most important in the evaluation of hydraulic

conductivity is the high degree of consistency between the two methods

that was observed.

Based upon the results of the falling head tests, it was concluded that a

pump test was not necessary in order to define aquifer hydraulic

characteristics. The hydraulic conductivity values calculated from the

falling head tests show excellent agreement between each test from the

same well and between individual wells. It is believed that these values

are representative of the Battery Formation near the site.

Groundwater Velocity

The average linear pore fluid velocity (v) of the groundwater may be

calculated by using the following Darcy formula:

v - - Hi [ft/day] P

where

K = hydraulic conductivity [ft/day]

i = hydraulic gradient

p = effective porosity

The average linear pore fluid velocity is defined as the discharge per

unit area of pore space, or the average rate at which liquid moves

through the pores of soil. This velocity represents an average value,

and maximum groundwater velocity may be substantially greater.

Using the average value for hydraulic conductivity determined from the -5

falling head permeability tests (6.1 x 10 ft/sec), an average

hydraulic gradient value determined from recent groundwater contour maps

101-RI2-EP-BAXU-4

4-63

0296S-33

(2.25 x TO-3), and an estimated effective porosity for the Battery

Formation (0.30), the estimated average linear pore fluid velocity in the

Battery Formation is 9.5 ft/year.

4.4.6 DISCUSSION OF WATER SAMPLE RESULTS

Extent of Groundwater Contamination

Based on the results of Contract Laboratory chemical analyses for

volatile, semi-volatile, herbicides, and pesticide compounds, no

significant contamination associated with pesticide and herbicide

disposal at the Del Norte Site has been detected in nearby private

wells. These analyses have, however, shown detectable levels of

contamination in groundwater beneath the site (i.e. MW-1), in off-site

MW-6,-12,-14, and -25, and in auger holes 1, 5, 10, and 13.

The following discussion summarizes the extent of groundwater

contamination by pesticides, herbicides, volatile, and semi-volatile

compounds at the Del Norte Site.

(1) The highest concentrations of several herbicides and pesticides

analyzed by the laboratory were detected in MW- 1. This well is

the only on-site monitoring well and is located approximately 20

feet from the sump believed to be the primary source of

contamination.

(2) Groundwater samples from MW-5 and nearby auger hole 13 were

found to contain 2,4-D. However, because groundwater elevations

show that MW-5 is upgradient of the sump, the source of the

2,4-D detected in MW-5 is not believed to be the pesticide

storage site. This conclusion is supported by the lack of 2,4-D

in the auger holes located between the site and MW-5. The area

immediately surrounding MW-5 has been extensively disturbed by

trenching, the result of animal burial by the Del Norte County

101-RI2-EP-BAXU-4

4-64

0296S-34

SPCA in this area. It is possible that during these activities,

pesticide contaminated materials may have been placed in the trenches.

Other pesticides and herbicides were detected only in the February 23

samples from MW-5.

(3) Very low levels of pesticides were detected in one of the

March 5 duplicate samples from MW-6, and in a February 23 sample

from MW-12. The lack of consistency in laboratory results at

those locations does not indicate an ongoing, significant source

of contamination.

(4) Several polynuclear aromatics (PAHs), which are chemicals

associated with petroleum products, were detected at low levels

in February 23 samples from MW-14 but were not detected in

March 5 samples. The source of the chemical compounds detected

in MW-14 is presently unknown. When this well was resampled in

July 1985, these compounds were detected again. The source is

still unknown. The results of the July 1985 sampling are

presented in the Chromium and PAH Groundwater Sampling Technical

Memorandum (September 1985).

(5) The soil fumigant 1,2-dichloropropane was detected at a

concentration of 5 ppb off-site in MW-25 but not detected in a

duplicate sample. The proximity of MW-25 to the site and the

measured direction of flow suggest that contaminants have

migrated from the sump area. However, the cause of the

inconsistency in the results from the duplicate sample from

MW-25 is unknown.

Available laboratory data indicates that the contaminant plume is moving

off-site in a southeasterly direction. This conclusion is consistent

with the general direction of groundwater flow inferred from available

water level data. Based on the detection of 1,2-dichloropropane in auger

hole 5 and MW-25, the contaminant plume has moved a minimum of 150 ft

101-RI2-EP-BAXU-4 4-65

0296S-35

from the on-site sump area. T,2-dichloropropane is the primary

contaminant in the plume, other compounds are present in the plume

on-site but have not been consistently detected off-site.

Concentrations of arsenic, chromium, and copper were detected in most of

the monitoring wells in the vicinity of the Del Norte Site. Analyses of

these metals was undertaken after pentachlorophenol, a wood preservative,

was detected in a subsurface soil sample. It was decided to test for the

three metals, since a compound called chromated copper arsenate (CCA) is

often used in the salt-treating of wood. Metal concentrations were

detected in wells both up- and down-gradient of the site; concentrations

down-gradient were generally higher but the source is likely much larger

than the Del Norte Site. The highest concentrations of metals were

detected in MW-6 and MW-7. There is no clear explanation for the absence

of significant metal concentrations in on-site MW-1, but it may be due to

differing well design and installation procedures used by the NCRWQCB.

In monitoring wells installed as part of the remedial investigation,

arsenic and copper were detected at concentrations below federal drinking

water standards (50 ppb and 500 ppb, respectively) while chromium was

detected at levels that are above the drinking water standard of 50 ppb

for total chromium. The measurements made were for total chromium.

Because the levels in the monitoring wells were generally in the

200-250 ppb range, if only a portion of the total was in the hexavalent

form, the standard would be exceeded. With the exception of the four

residential wells, all of the other eleven monitoring wells were

resampled in July 1985 to determine what form the chromium is in

(trivalent or hexavalent). Results of the July 1985 sampling and

conclusions may be found in the Chromium and PAH Groundwater Sampling

Technical Memorandum (September 1985).

Arsenic and copper were not detected in any of the domestic wells.

Chromium was detected at levels below the drinking water standard in

off-site well MW-10, up-gradient of the site, and in all residential

101-RI2-EP-BAXU-4

4-66

0296S-36

wells. The residential wells (MW-11,-12,-13,-14) were not resampled in

July 1985.

Arsenic, copper, and chromium were found in the soils on- and off-site

and were detected in groundwater both up- and down-gradient of the site.

These facts indicate that activities associated with the pesticide

storage area are not the source of this contamination. In addition,

there is no historical data which shows that any of these metals were

ever handled at the site. On the basis of presently available monitoring

data, it is not possible to delineate the extent of groundwater

contamination by arsenic, chromium, and copper.

Contaminant Migration Potential

Assessment of the potential migration of contaminants from the Del Norte

Site requires an understanding of groundwater flow rate and direction,

and contaminant transport characteristics as determined by the processes

of dispersion, retardation, and degradation. Mass transport modeling of

the no-action alternative at the Del Norte Site was completed as an aid

in evaluating the potential of serious groundwater contamination in

nearby domestic wells. Given the present uncertainty in the source and

extent of groundwater contamination by metals, the modeling effort was

limited to an assessment of 1,2-dichloropropane migration. Modeling was

used to address the principal elements of plume migration resulting from

advection and dispersion processes from a conservative or "worst case"

perspective, as well as considering transport parameters such as

retardation (adsorption of contaminants) and degradation that will

inhibit plume migration. The objective during this phase of modeling was

to evaluate the contaminant plume originating at the Del Norte Site

beginning 15 years ago and to follow its development over a period of 50

years, using conservative approximations of the source term,

hydrogeologic transport, and chemical transformation.

The models chosen to simulate plume migration at the Oel Norte Site were

the PLASM and RANDOM WALK models based on the Prickett-Lonquist model for

101-RI2-EP-BAXU-4 4-67

0296S-37

contaminant transport. The PLASM model generates a groundwater velocity

field using hydraulic head values determined from field measurement of

groundwater levels. Model-simulated head values were generally within

five percent of measured values. The groundwater flow field then serves

as the basis for evaluating contaminant transport using the RANDOM WALK

model. The RANDOM WALK model computes the migration of contaminants

within the groundwater flow field and attenuating effects from

dispersion, retardation, and degradation.

Several of the principal assumptions regarding the model simulation of

contaminant transport at the Del Norte Site are as follows:

• The aquifer is homogeneous, isotropic, and infinite in areal

extent.

• In order to analyze contaminant transport under steady state

conditions, aquifer recharge and discharge are not accounted for.

• The groundwater flow is constant in magnitude, and flowrates

from the downgradient wells will not change substantially in the

next 50 years.

• The contaminant plume evolves in two-dimensions, longitudinally

and horizontally transverse to the groundwater flow.

• Contaminant dispersivity is constant temporally and spatially

and at a longitudinal to transverse dispersivity ratio of

two-to-one.

• The concentration of contaminants at the source is 1500 ppb.

• The contaminant source was introduced into the aquifer 7 years

before the present and continues at a constant rate. (This is

an approximation of a linear 15 year buildup from zero.)

101-RI2-EP-BAXU-4

4-68

0296S-38

Information on values for key model input parameters is shown on Table

4-19.

Two contaminant transport scenarios were evaluated with the model—(1) a

scenario considering only the effects of groundwater flow and dispersion;

and 2) a scenario that includes the attenuating mechanisms of retardation

and degradation. Each scenario was modeled under present conditions and

at 25 and 50 years in the future as shown on Figures 4-11 and 4-12.

The scenario considering only the effects of groundwater flow and

dispersion (Figure 4-11) indicates that southerly migration of the plume

would tend to intercept a supply well MW-11 at 50 years. However, the

simulated plume in this scenario is likely to be unrealistically

extensive given the importance of microbial degradation of

1,2-dichloropropane and retardation of contaminant migration resulting

from adsorption onto organic materials. Considering these factors, the

contaminant plumes shown on Figure 4—13 are more likely to represent

actual conditions at the site. Under these conditions, the plume would

not intercept off-site domestic wells within a 50-year period.

4.4,7 CONCLUSIONS

(1) Herbicides, pesticides, volatile, and semi-volatile compounds

were detected in the highest concentrations in groundwater

on-site (i.e., MW-1). The volatile organic compound

1,2-dichloropropane was detected in concentrations up to 2100

ppb.

(2) Detection of low levels of groundwater contamination by

herbicides, pesticides, volatile, and semi-volatile compounds in

several off-site monitoring wells (MW-5,-6,-12, and -14) does

not appear to be associated with past pesticide handling

practices at the site.

101-RI2-EP-BAXU-4

4-69

0307s—1

Table 4-19. SUMMARY OF CONTAMINANT TRANSPORT PARAMETERS

Transport Parameter Estimated

Value Confidence of Data Comment

Head Average of four measurements

Good Model generated values within five percent of field data

Hydraulic conductivity (cm/s) 10"3 Good Value based on five falling-head tests and six gra1n-s1ze analyses

Aquifer transmlsslvlty (gal/day-ft2) 841 Fair Based on hydraulic conductivity and estimated aquifer thickness

Aquifer t.hlckness (ft) 25 Good Based on all well logs and groundwater contour maps

Aquifer porosity and bulk density 0.35/1.7 Good Based on literature values for similar geologic materials

Aquifer total organic carbon content (T0C)(X)

0.04 Good Based on duplicate samples from five wells

1,2-D1chloropropane retardation 1.3 Low Based on TOC and 1,2-D1chloropropane octanol-water partition coefficient (Karlckhoff, et al.t 1979)

Aquifer dlsperslvlty (longitudinal: traverse) (ft)

5:2.5 Low Based on literature values for similar aquifer materials and similarly sized contaminant plumes (Freeze and Cherry, 1979; Sudlcky and Cherry 1970/1979)

Blodegradatlon half-life for 1,2-0lchloropropane (yr)

20 Low Based on laboratory values (0.5 to 2 yr) 1n the literature (Callahan et al., 1979)

0 2B0 600 1000 2000

L i_J I l Sc«l« in f*ei

Figure 4-11. 1,2-Dichloropropane Plume at 0 Years

4-71

)

280 I

800 I

1000 2000

Scate in fwt

Figure 4-12. 1,2-Dichloropropane Plume at 25 Years

4-72

0 250 BOO 1000 2000

1 »• i I I

Figure 4-13. 1,2-Dichloropropane Plume at 50 years

4-73

0296S-39

(3) The detection of 1,2-dichloropropane in MW-25 and two off-site

auger holes indicates that a plume of limited extent has moved a

distance of at least 150 ft in a southeasterly direction from

the on-site sump area.

(4) Model simulation of the future migration of 1,2-dichloropropane

indicates that the plume will not reach surrounding domestic

wells within a period of 50 years.

(5) Arsenic, chromium, and copper were detected in all monitoring

wells installed as part of the remedial investigation (MW-2

through MW-8, MW-25, and MW-26). Arsenic and copper were

detected at levels below federal drinking water standards while

total chromium was detected at levels well above drinking water

standards.

(6) Arsenic and copper were not detected in domestic wells.

Chromium was detected in domestic wells MW-10, -12, -13, and -14

at levels below the federal drinking water standard; no chromium

was detected in MW-T1.

(7) Metal concentrations were detected in monitoring wells both up-

and down-gradient of the site. It is not possible to estimate

the source, extent, and migration potential of arsenic,

chromium, and copper with presently available data.

4-74

101-RI2-EP-BAXU-4

0204S-1

5.0 SURFACE WATER

5.1 INTRODUCTION

Due to the nature of the contamination at the Del Norte Site, the

potential exists for spread of contamination due to surface water runoff

from the site. The site is located within a generally flat region which

drains to the southeast. Surface runoff from the site drains to Pebble

Beach located 3/4 of a mile away on the Pacific Ocean. There is no

drainage into streams or rivers that serve as habitat for aquatic life or

sources for public use. As part of the Del Norte Remedial Investigation,

current surface water paths were defined, and sediment samples were

analyzed to detect any contamination carried by runoff.

5.2 DRAINAGE

5.2.1 ON-SITE DRAINAGE

Over the last thirty years, depressions and trenches within the Del Norte

site have been constructed and subsequently filled in. These activities

have caused the drainage patterns within the site to change. The present

direction of surface water flow is shown on the site topographic map (see

Figure 5-1). In general, water drains to all four corners of the site and

is then picked up by local drainage ditches. The on-site sump is

surrounded by a 1- to 2-foot-high earth dike, which is adequate to

contain direct rainfall and prevent surface runoff from the sump.

5.2.2 OFF-SITE DRAINAGE

Natural and man-made surface drainage routes exist around the Del Norte

Site. It appears that trenches have been excavated specifically to

improve drainage and to route surface water from the site and adjacent

101-RI2-EP-BAXU-4

5-1

0204S-2

areas. Drainage paths within close proximity of the site are shown on

Figure 5-1. Trench 1 runs parallel to the entire length of the site's

west border and directs flow northeast to southwest. Trench 2 originates

at the southeast corner of the site. Assumed drainage paths for the

entire surrounding area are shown on Figure 5-2. As shown, waters from

Trenches 1 and 2 eventually intersect at a common point before continuing

in a southerly direction. Drainage to the far northeast of the site is

intercepted by Trench 3, which travels northwest to southeast. This same

trench joins the two others before heading south. All surface drainage

in the site vicinity moves in a south/southeasterly direction to the

Pacific Ocean.

Approximately 1/2 mile to the northeast of the site is Dead Lake. Since

Dead Lake is substantially upgradient of the site, surface water

contacting the site would not flow into the lake and present a

contamination problem. Five hundred feet due east of the site is a small

man-made pond. Trenches and natural contours direct surface water runoff

away from this pond.

5.3 SEDIMENT SAMPLING

In September 1984, a composite surface soil sample was collected in

surface water runoff Trench 2, which is shown on Figures 5-1 and 5-2.

The trench was included in Quadrant 20, which was one of the off-site

quadrants shown on Figure 4-2. The sample (20-SS-A) was sent to the

screening laboratory to be analyzed for 2,4-D and 2,4,5-T. Since neither

compound was detected above the laboratory's detection limit (0.1 ppm),

the sample was not sent to the EPA contract lab.

From the above results, it was concluded that contamination by surface

water runoff is not a problem at the Del Norte Site and does not need to

be addressed in the remedial plan.

5-3

101-RI2-EP-BAXU-4

Figure 5-2. Suggested Surface Water Drainage Paths in the Vicinity of the Del Norte Site

5-4

0204S-3

5.4 FLOOD POTENTIAL

The site does not lie within any designated flood-prone areas or in any

100-year floodplains of streams or rivers. Though the site is relatively

flat, drainage is adequate to prevent the occurrence of standing water in

all but very extreme storms.

101-RI2-EP-BAXU-4

0203s—l

6.0 AIR INVESTIGATION

6.1 ACTIVITIES

Three types of investigations were performed with regard to potential air

quality problems at the site. An AID model 580 organic vapor monitor was

used to survey the site during preliminary site visits for airborne

organic constituents. Second, an HNU photoionization analyzer was used

to monitor soil gas emissions during the drilling of on-site borings for

subsurface soil samples and off-site borings for groundwater monitoring

well installation. During the drilling of the on-site borings, an HNU

meter was set up near the drilling rig; during the drilling of the

monitoring wells the HNU sensor was placed inside the borings after the

drilling of each 5-foot depth increment. Headspace monitoring using the

HNU was performed on samples taken from the sump.

The third type of investigation that was performed was the calculation of

potential on-site airborne concentrations due to mobilization of on-site

contaminated soils. These calculations indicated that it is highly

unlikely that enough dust could be generated on-site for the OSHA

permissible exposure levels to be exceeded due to the extremely small

size of the site and the relatively low contaminant concentrations in the

soil.

6.2 FINDINGS

No organic vapors or trace gases were detected on-site, during headspace

sampling of soils from the sump or in soil borings, using either the

organic vapor analyzer or the HNU photoionization analyzer. In addition,

the highest surficial soil contaminant concentrations are so low that

exceedance of OSHA standards for airborne contaminants would be extremely

101-RI2-EP-BAXU-4

6-1

0203S-2

unlikely. The inability to detect any off-site 2,4-D or 2,4,5-T

contamination appears to indicate that eolian transport of contaminated

soils is not occurring to any significant degree. Based on the above

findings, the potential for off-site transport of contaminants through

the airborne pathway is minimal, and therefore does not need to be

addressed as part of the remedial plan.

6-2 101-RI2-EP-BAXU-4

"5

0205s—l

7.0 BIOTA INVESTIGATION

7.1 ACTIVITIES

The investigation into the biotic resources at the site was limited to

qualitatively characterizing the biota in and around the site. This

characterization indicated that the biota in the vicinity of the storage

area are typical of the North Coast Vegetation Zone, which consists of

mixed forested areas of sitka spruce, pine, alder, and maple. The patchy

nature of the overstory allows the development of a thick understory of

vine maple, salal, and other common shrubs.

Nearby ecological zones include an extensive interior sand dune area,

Dead Lake, grasslands and pasture lands, marsh, and the Pacific Ocean.

The sand dunes and Dead Lake are upgradient, north and east of the site.

The grasslands are maintained as part of the airport; the area south of

Washington Blvd. is a fenced pasture. Some marsh habitat occurs south

and east of the site in the localized surface drainage pathway to the

Pacific Ocean.

A review of the available aerial photographs of the site and its

surroundings indicates that the vegetation in and around the storage area

has been stressed on occasion, specifically in 1982. From the black-and-

white aerial photographs, the stressed vegetation appears to be

discolored and thin, where it was once thick. Aerial photographs taken

in 1970 and 1976 do not show the level of stressed vegetation that was

found in the 1982 photograph.

7.2 FINDINGS

Based on the limited extent of groundwater contamination at the site (see

Section 4.4), herbicides, pesticides, and related organic compounds in

the groundwater could not cause the stressed vegetation that appears to

7-1 101-RI2-EP-BAXU-4

0205S-2

surround the site in the 1982 aerial photograph. Similarly, off-site

migration of contaminated sediments does not appear to be a cause for the

stressed vegetation, as neither of the chlorophenoxy pesticides, (i.e.,

2,4-0 or 2,4,5—T) were found in any of the surface soil samples that were

taken off-site. As discussed in the previous section, the airborne

pathway is also not a likely cause for the stressed vegetation, because

airborne contaminants have not been detected during any of the air

monitoring activities that have been performed on the site to date. It

would appear, then, that the stressed vegetation observed in the 1982

aerial photograph is not related to the Del Norte Site.

7-2 101-RI2-EP-BAXU-4

0214s—1

8.0 PUBLIC HEALTH ANO ENVIRONMENTAL CONCERNS

8.1 INTRODUCTION

As one phase of the remedial Investigation, a risk assessment was

performed to assess the Impacts of the Del Norte Site on public health

and welfare and the environment. Although information from previous

investigations were used to assess health and environmental risks, the RI

was tailored to generate additional data necessary for the risk

assessment. The risk assessment is divided into the following general

parts: selection of contaminants of concern and the potential release

pathways from the site; assessment of the toxicity of the contaminants of

concern, both to humans and animals; and assessment of the risks to

public health, welfare and the environment from these contaminants.

8.2 ACTIVITIES

8.2.1 DETERMINATION OF POTENTIAL EXPOSURE PATHWAYS

Data collected from previous site studies as well as the RI were reviewed

to determine the pathways which could potentially transmit contaminants

from the source (site) to receptors (nearby residences, wildlife, etc.).

As described in Section 4, groundwater and to a lesser extent soils, are

the primary pathways of exposure for the site. Surface water and air are

briefly addresed below, but have been essentially eliminated as

significant concerns.

The Del Norte Site area is very flat, located on a low terrace directly

adjacent to the Pacific Ocean, and thus supports no natural surface water

drainage system. Soils at the site are predominantly sandy, which makes

infiltration of precipitation more likely, and runoff less likely.

Several manmade drainage ditches are present around the periphery of the

site; however, migration of contaminants due to surface runoff was not

101-RI2-EP-BAXU-4

8-1

0214S-2

detected. Surface water is therefore not considered a potential pathway

for contaminant migration. See Section 5 for more details on the surface

water investigation.

Although contaminants can become entrained in dust, the area of

contaminated soils on-site is extremely small. The area immediately

surrounding the site is densely vegetated, and no off-site soil

contamination has been detected. Thus contamination of ambient air in

the vicinity of the site is not a significant pathway. See Section 6 for

more detail on the air investigations.

Direct contact with contaminated soils on-site could potentially occur,

although the possibility of such contact is minimal. The site is fenced,

posted with warning signs, and generally isolated from the public.

Actual areas of high concentrations within the site are limited to the

on-site sump and other very limited areas. Further details of the soils

pathway are provided below.

A small plume of contaminants was detected in the shallow aquifer during

the RI. Local residents in the vicinity obtain their domestic water

supplies from this aquifer. No contaminants from the site have been

detected above applicable standards in domestic wells; however, a slight

potential exists, for contact with contaminants by the public via the

groundwater pathway.

8.2.2 SELECTION OF CHEMICALS FOR HAZARD ASSESSMENT

Section 3.0 of this report describes the various chemicals known to have

been handled on the site (see Table 3-1). From the array of wastes known

to be present at the site, eight chemical compounds were selected as the

most likely to cause significant risks to potential receptors. The

selection was made based on the chemicals' concentrations at the site,

mobility and persistence in the environment, and relative toxicity to

humans and/or wildlife.

101-RI2-EP-BAXU-4

8-2

0214S-3

Table 8-1 lists the eight selected indicator chemicals, the maximum

concentrations in groundwater observed during the remedial investigation,

and applicable criteria regarding human health. Complete toxicity data

is contained in Appendix C. As discussed elsewhere in this report,

chromium in both soils and groundwater are of concern, both on-site and

in the surrounding area. Chromium was included in Table 8-1 and

preliminary assessment of this problem is provided in this section;

however, data is currently inadequate to fully address this problem.

8.3 FINDINGS

This section describes the potential for human and animal exposure to

contaminants; assesses the risks to human and animal populations; and

estimates the impacts to the environment caused by the Del Norte Site.

8.3.1 RISK ASSOCIATED WITH HUMAN EXPOSURE TO CONTAMINATED SOIL

The Del Norte Site is owned by Del Norte County and is not currently in

use. It is in a relatively remote area and access to the site is

restricted. Contamination of soil is confined within the site

boundaries. Therefore, under normal conditions, contact with

contaminated soil is unlikely. Even if someone entered the site,

exposure would probably be for only short durations and to low

concentrations of contaminants. The risks to human populations are

considered to be very low.

Excavation, construction, or new land use activities, especially in the

sump area, could lead to exposure to higher contaminant concentrations

for longer time periods. Although such exposures would also probably

involve relatively few individuals, the associated risks could be greater

than those expected for the casual, incidental type of contact described

in the previous paragraph. However, since soil contamination is limited,

it would probably be relatively easy for the County to institute an

8-3

101-RI2-EP-BAXU-4

-1

Table 0-1. CONTAMINANTS OF PRIMARY CONCERN AT THE DEL NORTE COUNTY PESTICIDE STORAGE AREA SITE: COMPARISON OF CONCENTRATIONS IN GROUNDWATER WITH APPLICABLE STANDARDS AND CRITERIA (all concentrations in ppb)

Maximum Concentration in Groundwaters

September 1982 -February 1983 February-March 1985

Ambient Water Quality

Criteria (AWQC) for

Human Healthc

Interim Primary

Drinking Water

Regulations11

USEPA Longer-Term Health Advisories

Arsenic

Chromium

2,4-D

2.4.5-T

DDT

oo ^Methylene chloride

1,2-dichloropropane

Benzene

410 1.1 (airport, MW-10)

610

ND (MW-1) 38 (MW-3)

261 (MW-7)

ND (MW-1) 547 (MW-3) 355 (MW-6)

150 12 (MW-5)

110 1.1 (MW-8)

ND 2.2b(MW-6)

ND (detection limit, 1000) 110

1200 1200

68

0.0022c

170,000 (CrIII) 50 (CrVI)

0.00004C

0.19c

0.66c

50

50

100

700d

150 e

10

70

aVa1ues are for the on-site well MW-1 and as indicated. MW = monitoring well.

''This concentration includes the sum of DDT (2 ppb) and DDE (0.2 ppb).

cValues associated with an estimated Incremental lifetime cancer risk of 10

Suggested No Adverse Effect Level. National Academy of Sciences. 1977. Drinking Water ahd Health.

Suggested No Adverse Response Level. California Department of Health and USEPA.

fProposed Maximum Contaminant Levels (MCLs). Action Memorandum (4-17-85): VOCs-Promulgation of Recommended MCLS and Proposal of MCLs.

ND = not detected.

0214S-4

effective safety plan. Risks associated with exposure as a result of use

or reuse of the site would also be relatively low.

8.3.2 RISK ASSOCIATED WITH HUMAN EXPOSURE TO CONTAMINATED GROUNDWATER

Risk Based on On-site Contaminant Concentrations

Groundwater at the Del Norte site is not currently used for drinking or

other purposes, and future use of this water is not anticipated. Unless

a drinking water well was installed at the site, exposure to contaminants

at concentrations currently found on site would not occur. Therefore,

the results of this analysis probably represent conservative modeling

assumptions.

Arsenic and chromium have been found in groundwater at several sampling

points in the vicinity of the Del Norte site. These contaminants were

not detected in on-site groundwater. Consequently, the risks associated

with on-site exposure to these compounds are not discussed in the

following section. Furthermore, currently available data are not

sufficient to model movement of these contaminants in groundwater, and

predicted future risks are therefore not discussed. However, it should

be noted that detected concentrations in off-site groundwater greatly

exceed Interim Primary Drinking Water Maximum Contaminant Levels in some

cases, and that significant health risks to exposed individuals would

exist if water containing these levels was consumed.

DDT and DDE have been found in one off-site monitoring well (MW-6) but

not in on-site groundwater. Consequently, the risks associated with

on-site exposure to these compounds are not discussed in the following

section. Although these compounds may have originated at the Del Norte

Site, available data are not adequate to model their movement in

groundwater, and predicted future risks are therefore not discussed.

Ingestion of water contaminated at the observed levels could result in an

increased cancer risk to exposed individuals. However, DDT and DDE are

8-5

101-RI2-EP-BAXU-4

0214S-5

strongly adsorbed to soils and other surfaces and are unlikely to be

transported significantly in groundwater.

Similarly, a number of potentially carcinogenic PAHs have been detected

in an off-site drinking water well (MW-14) but not in on-site groundwater

or in other off-site monitoring wells. The source of these compounds is

not known and available data are not adequate to permit modeling of their

movement in groundwater. Consequently, risks associated with present or

future exposure will not be discussed in the following sections.

Ingestion of water contaminated at the observed levels (3-13 ppb) could

result in an increased cancer risk to exposed individuals. However, PAHs

are strongly adsorbed to surfaces and are not readily mobile in

groundwater.

Noncarcinogenic Chemicals Comparison of observed concentrations of

noncarcinogenic indicator chemicals (February-March 1985 data) with

applicable drinking water regulations or suggested guidelines based on

allowable daily intakes (ADI) provides an indication of the risks

associated with exposure to these compounds. This information is

presented in Table 8-1.

Concentrations of 2,4-D in groundwater at the Del Norte Site

(February-March 1985) exceed the Primary Drinking Water Regulation

Maximum Contaminant Level (MCL) by a factor of 1.5. Thus, systematic

toxicity, as described in the toxicity profile for this compound, could

potentially occur in individuals using groundwater contaminated at the

observed levels as a drinking water source.

Concentrations of 1,2-dichloropropane exceed the Suggested No Adverse

Response Level, a suggested guideline for prevention of adverse effects

due to ingestion of this chemical compound in water, by a factor of 120.

Thus, significant health risk to exposed individuals probably exists.

101-RI2-EP-BAXU-4

8-6

0214S-6

The concentration of 2,4,5-T in groundwater at the site is lower than the

Suggested No Adverse Response Level for this compound by more than a

factor of 6. Thus, it appears that chronic ingestion of groundwater

contaminated at this level would not result in systemic toxicity in

exposed individuals. However, results of previous groundwater monitoring

efforts (September 1982-February 1983) have indicated higher 2,4,5-T

concentrations.

Carcinogenic Chemicals The remaining indicator chemicals listed in

Table 8-1 are potential human carcinogens. The potential risks

associated with ingestion of groundwater in the vicinity of the site are

estimated by comparing exposure rates with unit risks for these

compounds. A unit risk is the possible incremental lifetime cancer risk

occurring in a hypothetical population in which all individuals are

exposed continuously for lifetime to a concentration of 1 ppb of a

compound in drinking water.

In developing lifetime incremental cancer risks, USEPA's Carcinogen

Assessment Group uses a multi-stage model, among others to extrapolate

potential excess cancer risks expected at environmental concentrations

from results in high dose animal studes. This model estimates risk to a

70 kg adult ingesting 2 liters of water per day for a 70-year lifetime.

The cancer risk associated with ingestion of water containing

contaminants at levels currently existing at the Del Norte Site is shown

in Table 8-2. Federal regulations for environmental contaminants have -4 -6

generally fallen in the 10 to 10 lifetime risk range.

Risk Based on Off-Site Contaminant Concentrations

Results of groundwater modeling suggest that a contaminant plume

originating at the Del Norte site could potentially reach existing

domestic wells in 50 to 100 years. Because of the conservative

assumptions made in estimating the extent and severity of groundwater

101-RI2-EP-BAXU-4

8-7

0311s-1

Table 8-2. CANCER RISK ASSOCIATED WITH INGESTION OF ON-SITE CONTAMINATED GROUNDWATER

Concentration Risk Associated Unit Risk3 in Groundwater with Ingestion

(ppb)-l (ppb) of Groundwater

Methylene Chloride 5.26 x 10"6 110 5.79 x 10"4

Benzene 1.49 x 10"6 68 1.01 x 10"4

3 Upper 95% confidence limit unit risks are derived from Ambient Water Quality Criteria for Protection of Human Health; more recent Carcinogen Assessment Group calculations (49 Federal Register 114:24340) are used where available.

8-8

Draft 101-RI2-BAXU-4

0214S-7

contamination beyond the Del Norte Site, the results of this analysis

also probably represent conservative modeling assumptions. However, this

risk assessment is more realistic than one based on existing on-site

contaminant concentrations (see discussion above) in that it estimates

risks at probably points of exposure.

Noncarcinogenic Chemicals The estimated concentration of 2,4-D at

potential human exposure points in 50 to 100 years is lower than the

Primary Drinking Water Regulation MCL by a factor of 80. The estimated

concentration of 2,4,5-T is more than 700 times less than the suggested

non-adverse-response-level for this compound shown in Table 8-1.

Consequently, it appears that the human health risks associated with

chronic ingestion of groundwater contaminated at these levels would be

negligible.

In 50 to 100 years, 1,2-dichloropropane is estimated to be present at

potential human exposure points at a concentration of 10 ppb. This

concentration is equivalent to the suggested no-adverse-response- level

for this compound. Although a safety factor is built into this

guideline, chronic exposure at this level could potentially result in

adverse health effects. As mentioned previously, a number of

conservative assumptions were made in developing the initial Del Norte

contaminant plume simulations. For example, 1,2-dichloropropane is

reported to undergo significant biodegradation. If this factor is

considered in modeling efforts, then 1,2-dichloropropane would not pose

significant health risks under these circumstances.

Carcinogenic Chemicals The remaining indicator chemicals are potential

human carcinogens. The cancer risks associated with ingestion of water

containing these compounds at levels estimated to occur at human exposure

points is 50 to 100 years are shown in Table 8-3. The incremental

increase of lifetime cancer risk associated with lifetime exposure at the -5

estimated concentrations is less than 10 for all the potentially

carcinogenic indicator chemicals.

101-RI2-EP-BAXU-4

8-9

0311s-2

Table 8-3. CANCER RISK ASSOCIATED WITH INGESTION OF OFF-SITE CONTAMINATED GROUNDWATER AT POTENTIAL HUMAN EXPOSURE POINTS

Unit Risk3

(PPb)"1

Concentration in Groundwater

(ppb)

Risk Associated with Ingestion of Groundwater

Methylene Chloride 5.26 x 10"6 0.92 4.84 x 10"6

Benzene 1.49 x 10"6 0.57 8.49 x 10"7

a Upper 95% confidence limit unit risks are derived from Ambient Water Quality Criteria for Protection of Human Health; more recent Carcinogen Assessment Group calculations (49 Federal Register 114:24340) are used where available.

8-10

Draft 101-RI2-BAXU-4

0214S-8

8.3.3 ASSESSMENT OF ENVIRONMENTAL IMPACTS

Potential environmental impacts at the Del Norte site are associated

primarily with exposure to contaminated soil. Terrestrial animals and

birds using the site may be exposed to contaminants present in surface

materials. However, because concentrations of surface soils are

relatively low except in a few localized areas of the site, potential

risks associated with direct contact are probably low. Some

bioaccumulation of organochlorine compounds, especially by soil

invertebrates such as insects and earthworms, may occur. Birds and other

animals ingesting these organisms may also be exposed, thus leading to

some bioconcentration in the food chain. However, the site is relatively

small and is close to an airport and other human activities to reduce use

of the area by higher predators. Migration of significant amounts of

chemical contaminants beyond the site boundaries, except in groundwater,

is not likely to occur.

Groundwater investigations suggest that contaminated groundwater could

discharge into the small pond southeast at some time in the future.

Comparison of estimated concentrations of contaminants entering the pond

at this time with available information concerning aquatic toxicity of

these compounds suggests that adverse environmental effects associated

with contamination at the predicted level are unlikely. Dilution

afforded by the receiving water would make the occurrence of adverse

environmental effects even less likely. Information concerning the

aquatic toxicity of the compounds of primary concern at the Del Norte

site is summarized in the toxicity profiles in Appendix C.

8.3.4 ASSESSMENT OF IMPACTS ON PUBLIC WELFARE

The site is surrounded by land owned by Del Norte County and is thus

buffered from adjacent land uses. As long as the site remains

undeveloped and migration of materials from the site does not occur,

adverse effects on public welfare are not likely to occur. Furthermore,

8-11

101-RI2-EP-BAXU-4

0214s—9

future uses will be compatible with the remedial actions taken, to ensure

that future land use is consistent with safe and environmentally sound

policies under conditions existing at the site.

Migration of contaminants in groundwater is a distinct possibility (see

Section 4). Contamination of local groundwater could adversely affect

future development in the vicinity of the site. Depending on the degree

and extent of contamination, property values could decrease and residents

may have to obtain alternative domestic water supplies.

8.4 SUMMARY

Risk associated with exposure to contaminated soil at the Del Norte site

appear to be relatively low. Although human exposure could potentially

result in some adverse health effects, these effects are unlikely to be

life threatening. The potential for adverse environmental effects also

is low. Soil contamination is probably most important in that it is a

potential source for further contamination of groundwater at the site.

The most important risk associated with contamination of groundwater at

the site is the potential for exposure in humans using the groundwater as

a domestic water supply. Contamination of groundwater could also result

in reduction of public welfare in the vicinity of the site. Results of

conservative modeling assumptions based on existing data suggest that

significant risks could be experienced by local residents using water

contaminated at concentrations currently found in groundwater at the

site. Existing off-site supply wells do not contain contaminants from

the site at levels above applicable standards and criteria. Also, the

results of future plume projections under very conservative assumptions

suggest that contaminants from the site probably would not reach

potential human exposure points for 50-100 years. More realistic

exposure and risk estimates based on these projections suggest that

groundwater contamination originating at the site is not likely to cause

significant risks to potential human receptors for at least 50-100 years.

8-12

101-RI2-EP-BAXU-4

0300S-1

9.0 REFERENCES

California Department of Water Resources. 1966. Water Well Standards,

Del Norte County, Bulletin 74-3.

Callahan, Michael A., et al. Water Related Environmental Fate of

129 Priority Pollutants. Vol. II. EPA-440/479-029b.

Freeze, R.A., and Cherry, J.A. 1979. Groundwater. Englewood Cliffs:

Prentice-Hall, Inc.

Heim, M., and Austin, N. (California State Department of Finance).

1985. Telephone conversation with R. Trowbridge (Woodward-Clyde

Consultants) regarding Crescent City and Del Norte County population

statistics.

Karickhoff, S.W., Brown, D.S., and Scott, T.A. 1979. Sorption of

hydophobic pollutants on natural sediments. Water Resources

13:241-248.

Lockheed Engineering and Management Services Company, Inc. 1982. Aerial

Photography Analysis of Hazardous Waste Study Sites. Vol. 2,

Northern California.

Phone conversation between Rebecca Trowbridge of Woodward-Clyde

Consultants and Marilyn Heim and Nancy Austin of the CA State

Department of Finance regarding Crescent City and Del Norte County

population statistics.

Prickett, Thomas A., Naymik, Thomas G., and Lonnquist, Carl G. 1981.

A "Random Walk" Solute Transport Model for Selected Groundwater

Quality Evaluations. Illinois State Water Survey, Bulletin 65.

9-1

101-RI2-EP-BAXU-4

0300S-2

U.S. Environmental Protection Agency. 1983. Draft Remedial Action Master

Plan, Del Norte County Pesticide Storage Area. 01-9V33.0.

U.S. Geological Survey. 1957. Geology and Ground-water Features of the

Smith River Plain. Del Norte County, California. Water Supply Paper

No. 1254.

Woodward-Clyde Consultants. 1985. Del Norte County Pesticide Storage

Area Site Remedial Investigation/Feasibility Study Interim Site

Investigation Memorandum, Surface and Subsurface Soils Results.

Woodward-Clyde Consultants. 1985. Del Norte County Pesticide Storage

Area Site Investigation and Feasibility Study, Work Plan. Vol I.

9-2

101-RI2-EP-BAXU-4

0202S-16

APPENDICES

Appendix A

Hydrogeologic Investigation:

Surface and subsurface soils

0202S-1

APPENDIX A.I

SURFACE SOIL SAMPLE COLLECTION PROCEDURES

The vegetation, debris, and detritus, if present, was scraped away from

an approximately one foot diameter area at each sampling station. A

1/8 cup stainless steel measuring utensil was used to scoop up the soil

with slightly less than three 1/8 cupfulls taken from each station and

placed in each of the two 16 oz. jars. This resulted in a total of

approximately 5 oz. of soil taken from each station and 30 oz. from each

quadrant. Care was taken to try and exclude as much gravel and organic

matter (e.g., roots, grass, pine needles, etc.) as possible. A few

samples such as those taken in the dense brush areas did, however,

contain some organic matter. It was initially felt that the organic

matter may influence the lab analyses to some extent. Consequently, two

background samples were taken well offsite during the September sampling

with one being in a vegetated area with significant organic matter in

the soil and the other in an open area with almost no organic matter

present. Each background sample consisted of 16 oz. of soil taken from

one station only. The background station in the vegetated area was taken

approximately 50 yards west of the southwest corner of the site while the

other background station was located approximately 100 yards west of the

northwest corner of the site.

The sample containers were 16 oz. clear glass, wide mouth jars with

teflon lined black phenolic caps. Prior to use in the field the jars and

caps were rinsed with pesticide grade acetone and the jars were oven

dried for 30 minutes at 200°F. The caps were air dried. Following

placement of the sample in the jars, they were labeled, put in ziplock

A-l

0202s-2

plastic bags and placed 1n a cooler with 1ce. The jars were labeled with

the quadrant number, SS for surface sample and A or B for the two jars

at each station (e.g., for quadrant 1 1t would be 1-SS-A or 1-SS-B).

The background samples for the vegetated and non-vegetated areas were

numbered 26-SS-A and 27-SS-A respectively. The date and time of day

were also noted on the jars. In September, no surface sample was taken

for quadrant 24 as access to all but the northern edge was blocked by

very dense brush and fallen debris. Also, access to quadrant 20 was

restricted to the southern edge which would have put both samples In close proximity.

A-2

0202S-3

APPENDIX A.2

SUBSURFACE SAMPLE COLLECTION PROCEDURES

The September 1984 samples were taken using a truck-mounted drill rig

equipped with an eight inch hollow stem auger and a California modified

sampler. During the drilling and sampling operations the stratigraphic

and hydrogeologic characteristics (e.g. depth to water) of the substrate

were examined and recorded for each boring. The boring logs are provided

in Appendix B.3. Samples collected during the February 1985 drilling

were done in the same manner. Boring logs for this program can be found

in Appendix B.3.

The samples were labeled for identification using three separate

numbers. The first number identifies the boring and quadrant within

which the sample was taken, the second designates the drive it was taken

from and the third number identifies the sample tube from that drive.

For example, a sample taken from the second tube of the third drive from

the sump would be labeled; 25-3-2. The depths at which each sample was

taken were also noted on the sample while the date and time of sampling

were recorded on the boring logs and chain of custody forms. The

subsurface soil samples collected in February were labeled in the same

manner.

Upon completion of the sampling operations the cuttings from the nine

borings were placed in 55 gal. drums and bolted shut. The borings were

then backfilled with concrete to the surface. The drummed cuttings along

with a few drums containing other contaminated materials (e.g. used Tyvek

coveralls, gloves, boxes, empty acetone and dionized water containers.

A-3

0202S-11

etc.) were left onsite. As a cost saving measure these drums were

disposed of along with drums of cuttings and other wastes that were

generated when the additional groundwater monitoring wells were installed.

A-4

0202S-5

APPENDIX A.3

SAMPLE PREPARATION PROCEDURES

1. Weigh 5 grams of soil (wet weight), sift it through a number

10 sieve, and collect the soil in a 40 ml VOA vial. Add 2 ml

of deionized water to the vial and shake the vial for several

minutes. Add 1 drop of 1:1 H^SO^ to the vial followed by

10 ml of diethyl ether. Attach the vial to a shaker and shake

vigorously for 2 hours.

2. Remove the ether layer and transfer it to another vial containing

0.5N NaOH. Agitate the vial gently by hand for 2 minutes.

(Freeze water out of ether if an emulsion forms.) Pipette and

discard the ether layer. Add 3 drops of 1:1 H2S04 (pH<3) to

the water remaining in the vial and extract with 10 ml of ether

by agitating for 1 minute. Discard the aqueous phase and dry the

ether over anhydrous Na^O^.

3. Pipette exactly 1 ml of ether to a reaction vial and dry water

under N^ at 38°C. Add 0.75 ml of BF3 in methanol. Heat vial

for 15 minutes and then cool to room temperature.

4. Transfer to a 40 ml VOA vial containing 10 ml of 7% Na2S04

solution and 5 ml of hexane. Vortex (mix) for 1 minute and then

pipette hexane to a storage vial.

A-5

0202s-4

5. The sample 1s now Injected on to a Varian gas chromatograph (GC)

equipped with an electron capture detector and Varian Vista 401

automated data handling system. The gas chromatographic column

used for this analysis 1s a glass colume packed with SP-2100 and run at 190bC isothermally.

A-6

0202S-7

APPENDIX A.4

GEOPHYSICAL STUDY

Introduction

Geophysical measurements were obtained at the Del Norte County Pesticide

Storage Area Site on August 21, 1984. The purpose of these measurements

was to evaluate the subsurface conditions with respect to evidence of

previous excavation activity (waste burial), probable direction of

contaminant migration and the potential presence of buried drums.

Electro-magnetic (EM) induction methods using a Geonics EM-31 were

employed to measure lateral variations in the electrical conductivity of

the upper approximately 16 feet of soil. This instrument operates by

inducing electrical currents in the ground and measuring their magnitude

to obtain a continuous direct reading of soil conductivity. More

specifically, the EM-31 measures apparent ground conductivity by sensing

the amount of magnetic field coupling between two loop antennas located

near the ground. The coupling is the relationship between the amplitudes

and phases of the magnetic fields being measured at the receiving

antenna. One loop, the transmitter antenna, generates a primary magnetic

field at audio frequencies. This time-varying magnetic field also

induces electrical eddy currents within the ground, which in turn

generate a secondary magnetic field. The primary and secondary fields

are both sensed by the receiving antenna. The ratio between the two

fields depends on loop orientation and separation, was well as the ground

conductivity. Electronic circuits within the instruments convert this

ratio to a direct readout of apparent ground conductivity in millimhos

per meter (mmho/m).

A-7

0202S-6

Apparent Ground Conductivity

At any given point the value measured by the instrument is referred to as

"apparent ground conductivity" because it represents an integrated value

of the true conductivities within the sensing range of the instruments.

The sensing range is determined by coil separation, coil orientation,

and operating frequencies and extends both horizontally and vertically

from the coil locations. Thus, the EM-31 system used in a vertical coil

mode with the fixed coil separation of 3.7 m is sensing the integrated

conductivity of the upper 5 m (16 ft.) of the soil section but the

majority of the signal represents the conductivity of the upper 2.5 m

(8 ft.)

The EM-31 may also be used for metal detection work by employing special

operational methods. The presence of metal within the instrument's EM

field results in a phase shift which causes the magnetic coupling to

rapidly change. This effect may be further amplified by placing the EM31

in the "QUAD" mode and adjusting the meter to one-quarter full scale.

The QUAD mode effectively increases the instruments sensitivity to metal

by approximately 20 percent.

Factors Affecting Soils Conductivity

Soil/rock conductivity is predominately controlled by electrolytic

conduction which is determined by porosity (degree and type), moisture

content, concentration of electrolytes, temperature, phase state, and

colloids (clay). The impact that contaminants have on electrolyte

conduction is usually the primary source of anomalous conductivity values

associated with the presence of a contaminant. Inorganic contaminants

usually increase the conductivity when present in significant quantities.

Conversely, organic contaminants such as gasoline will generally act

as insulators and reduce conductivity. It can be demonstrated that

the presence of an organic, low-conductivity fluid in a dry (low

conductivity) soil will not in itself cause an anomaly but that its

A-8

0202s-7

effect on the soil moisture balance may be dramatic. Field experience

with organic chemicals suggests that an effect occurs which is

approximately one order of magnitude greater than that associated purely

with soil moisture displacement by a non-conductive liquid. While the

nature of the interaction is poorly understood, the cause is apparently

related to disruption of the soil moisture balance, e.g. effects on the

capillary zone and pore to pore conductivity.

Data Interpretation

The lateral variations in electrical conductivity at the Del Norte site

may be interpreted in terms of variations in moisture and clay content,

as well as metallic objects. Lateral variations may also be interpreted

as changes in concentration of organic compounds in the soil although the

levels of organic contaminants at the site are anticipated to be too low

to significantly influence the soil conductivity. An increase in the

depth to the water table will result in a decrease in the conductivity

values. A decrease in overall soil clay content will also cause a

decrease in the conductivity values. In each case, an area of lower

conductivity, compared to regional values, is indicative of a likely

pathway for migration of contaminants. An area of anomalous values is

generally associated with unusual soils conditions, such as those caused

by excavation. The presence of metallic conductors, such as drums or

cans, will also cause distinctive anomalous values. i

Survey Procedures

A survey grid was established, and conductivity values measured, on 10

foot intervals throughout the fence site area and accessible perimeter

areas. This provided 200% coverage as the instrument measures soil

conductivity for approximately 10 ft. in all directions. A two man

survey team consisting of a geophysicist and a technician performed the

survey with the geophysicist operating the instrument and the technician

recording the measurements at each interval or station. The survey was

A-9

0202S-8

run longitudinally along the grid lines with respect to the layout of the

site (e.g. in a southwest - northeast direction). The instrument was

oriented such that the transmitter and receiver were inline with the grid

lines except occasionally where a perpendicular orientation was used to

confirm anomalous readings.

Conductivity values were obtained where interference from metallic

objects, such as the fence and well casings, was minimal or predictable.

The values were plotted and contoured at a two mmho/m. interval (see

Figure 3). Subsequently, the instrument was adjusted for optimal

sensitivity to metallic objects (QUAD mode) and the site was scanned for

anomalous values not associated with known surface metallic objects.

Under these conditions the instrument is capable of detecting the

presence of a relatively intact drum at depths of 10 to 15 feet. The

scanning was conducted by walking the grid lines while observing the

continuous readout of the instrument and noting locations and values of

anomalous readings, if any. The presence of surface metallic objects at

the site such as, rusted metal flakes from the drums, old well casings,

wire, etc., prevented the detection of any other metal objects that

may have been buried underneath. Similarly, these objects prevented

obtaining any meaningful conductivity values for these areas during the

survey. This did not, however, significantly impact the results of the

survey as the areas containing surface metal comprised only a small

portion of the site.

Results

The contoured conductivity values are shown in Figure 3, along with a

sketch of surface features which are the cause of anomalous values.

Conductivity values are high along the site perimeter due to the presence

of the fence. Unusually high values occur throughout the northern half

of the site. The values in the northeast quadrant are associated with

metal debris from rusted scrap metal (drum remains?) and effectively

prevent accurate evaluation of the true soils conductivity. The values

A-10

Contour Map of Conductivity Values in mmho/m

Surface Metal Features: 6/B4

M s s K s n • • • • B D II 12

IS* IS*

Fence •

(>

Old Well Casings-

4 .Wire

-IncineratorJ ] ©

Gate

Scrapmetat

NOTE: No evidence of significant quantities of metal found, other than in the areas of Surface Scrap.

\ \

0 L

20 40 ft. J I

Fioure 2. GEOPHYSICAL MEASUREMENTS OF DEL NORTE COUNTY PESTICIDE STORAGE AREA SITE

A-ll

0202S-9

in the northwest quadrant rise progressively upon approach to a surface

tank presently on the site and appear to be primarily related to surface

metal objects.

The overall conductivity gradient, based on the values measured on and

around the site, appears to be towards the south and southeast. This

condition implies a greater likelihood of material transport in these

directions. No major conductivity anomalies are evident outside those

related to the metal surface debris. A small high of 1 mmho/m. occurs on

the south side of the site but appears to be related primarily to the

small trees growing in that area.

The site scan for unknown buried metal objects revealed no anomalous

targets which could be attributed to buried drums in the measurable areas

of the site. The possible presence of drums underneath metallic surface

objects or debris cannot, however, be discounted on the basis of these

measurements since these surface objects are a source of interference.

A-12

APPENDIX A.5

SUMMARY OF SOIL AND WATER SAMPLING PROGRAMS

A-13

99

Appendix A. 5 SUMMARY OF SOIL SAMPLING PROGRAM

Sample Location or Number Analysis3 Lab'' No. of Samples

SEPTEMBER 1984 (Refer to Figure 4-2)

A. Screening Lab 1. Surface Samples Quadrants 1-23, 26(Bkg),

2. Subsurface Borings

B. Contract Lab 1. Surface Samples

> I-*

2. Subsurface Samples

27(Bkg)

Quadrants 6,7,10, 11,14,15,18,19,25

1A,2A,2B,4A,6A,6A(DUP), 11A,12A,14A,15A,19A, 20A(DUP2A),20B(DUP2B), 23A,26A(Bkg),27A(Bkg)

6A(2),11A,14A,27A

6B,11B,14B,15A,15B, 27A(Bkg),28A

6-1-2,7-1-4,10-1-3, 11-1-2,14-1-3,15-1-2, 15-2-3,18-1-2,19-2-2, 25-1-2,25-2-4,25-4-2

15-1-2, 25-1-2

2,4-D, 2,4,5-T

2,4-D, 2,4,5-T

2,4-D, 2,4,5-T, Malathion

Volatiles, Semi-volatiles and Pesticides

TCDD (dioxin)

2,4-D, 2,4,5-T, 2,4,5-TP, Malathion

Volatiles, Semi-Volatiles and Pesticides

NCL

NCL

CAL

CAL

GEO

CAL

25 Samples 2 Duplicates

44 Samples 8 Duplicates

16

1 2

CAL

25-1-2 TCDD (dioxin) GEO

99<

Appendix A. 5 SUMMARY OF SOIL SAMPLING PROGRAM (continued)

Sample Location or Number Analysis3 Lab*3 No. of Samples

JANUARY 1985 (Refer to Figure 4-3)

A. Screening Lab • All Surface

Samples

B. Contract Lab • All Surface

Samples

> i

101-118, 124-130

101-118, 124-128

A Series: 102,103,106, 115,116,127(0up 115), 130(Bkg)

C Series: 102,103,106, 115,116,127(Dup 115), 130(Bkg)

A Series: 101,107,110 117,124,125(Bkg), 126(Dup 107)

B Series: 101,107,110, 117,124,125(Bkg), 126(Dup 107)

2,4-D, 2,4,5-T

23 Volatiles

2,4-D, 2,4-DB, 2,4,5-T, 2,4,5-TP, Ethion, Malathion, Pentachlorophenol

Volatile Organics

Volatiles, Semi-volatiles and Pesticides

2,4-D, 2,4-DB, 2,4,5-T 2,4j5-TP, Ethion, Malathion

NCL

CH2M Hill

B&C

U.S. Testing

ERG

B&C

25 Samples 9 Duplicates

23 Samples

7 Samples

7 Samples

7 Samples

7 Samples

Arsenic Chromium, Copper JTC 7 Samples

59s

Appendix A. 5 SUMMARY OF SOIL SAMPLING PROGRAM (concluded)

Sample Location or Number Analysis3 Labb No. of Samples

FEBRUARY 1985 (Refer to Figure 4-3)

A. Screening Lab • All Subsurface

Samples Quadrants 119,120,121, 122,123 and samples from Borings of MW6 and MW7 at 5' below grade (Bkg)

2,4-D, 2,4,5-T 22 Volatiles

NCL CH2M Hill

72 Samples 2 Background

B. Contract Lab • All Subsurface

Samples 119-1-4,119-2-2,119-5-2, 120-1-2,120-2-2,121-2-2, 122-2-2,123-2-2,123-2-4

2,4-D, 2,4,5-T Penta-chlorophenol, Volatiles

PEI 9 Samples

> i H*

119-2-3,119-3-3,119-5-3, 120-3-3,121-3-3,122-3-3, 123-3-3,132-3-4(MW6-l-3 Bkg)

Arsenic, Chromium, Copper JTC 8 Samples

119-2-4,119-3-4,119-5-4, 120-3-4,121-3-4,122-3-4, 123-3-4,131-3-4(MW7-l-3 Bkg)

2,4-D, 2,4-DB, 2,4,5-T 2,4,5-TP, Ethion, Mala-thion

B&C 8 Samples

119-2-4,119-3-4,119-5-4, 120-3-4,121-3-4,122-3-4, 123-3-4,131-3-4(MW7-l -3 Bkg)

Volatiles, Semi-volatiles, Pesticides, Pentachlorophenol, 1-3 Dichloropropane 1,2,3 Trichloropropane 2,3,4,5 Tetrachlorophenol

ERG 8 Samples

3 Complete list of Volatiles is shown on Table A.5-1, this appendix. Complete list of Semi-Volatiles is shown on Table A.5-2, this appendix. Complete list of Pesticides is shown on Table A.5-3, this appendix.

b LAB KEY NCL = North Coast Lab B&C = Brown & Caldwell CAL = California Analytical Laboratories ERG = Environmental Research Group GEO = Geochem Research, Inc. JTC = JTC Environmental Consultants PEI = PEI Associates

9s

Appendix A.5. SUMMARY OF WATER SAMPLING PROGRAM (continued)

Sample Location or Number Analysis3 Labb

No. of Samples

MARCH 1985

A. Contract Lab • Samples Taken

3/5/85 MW1-MW8 (site monitoring) MW10-MW14 (residents) Dup (MW1), Dup (MW6) Blank

Volatiles, Semi-volatiles, ERG Pesticides, 1-3 Dichloropro-pane, 1,2,3 Trichloropropane, 2,3,4,5 Tetrachlorophenol

17

> I

2,4-D, 2,4-DB, 2,4,5-T, B&C 2,4,5-TP, Ethion, Malathion

Arsenic, Chromium, Copper JTC

Cis and Trans 3-chloroallyl CAL alcohols

17

17

17

B. Contract Lab • Samples Taken

3/25-3/26/85 Augerholes AH1-AH17, MW1, MW4, MW15, MW16

Volatiles, 2,4-D, 2,4,5-T CAL 21

APRIL 1985

Contract Lab • Samples Taken MW5, MW15, MW17, MW25,

4/28/85 MW26 Arsenic, Chromium, Copper Versar 5

Volatiles, 2.4-D, 2,4-DB, CAL 5 2,4,5-T, 2,4,5-TP, Malathion, Tordon, cis and trans -3-chloroallyl alcohol, Semi-Volatiles, Isopropanol

9s

Appendix A.5. SUMMARY OF WATER SAMPLING PROGRAM

Sample Location or Number Analysis3 Lab*5

No. of Samples

FEBRUARY 1985

A. Screening Lab • Samples Taken

2/7/85 ALL SAMPLES

MW1-MW8 (site monitoring) MW10-MW14 (residents) Oup (MW1), Oup (MW6) Blank

2,4-D, 2,4,5-T Volatile Organics

NCL CH2M Hill

17 17

Contract Lab • Samples Taken

2/23/85-2/24/85 Volatiles, Semi-volatiles, ERG Pesticides, 1-3 Dichloropro-pane* 1,2,3 Trichloropropane, 2,3,4,5 Tetrachlorophenol

2,4-D, 2,4-DB, 2,4,5-T, B&C 2,4,5-TP, Ethion, Malathion

Arsenic, Chromium, Copper JTC

Cis and Trans 3-chloroallyl CAL alcohols

17

17

17

17

)9s

Appendix A.5. SUMMARY OF WATER SAMPLING PROGRAM (concluded)

Sample Location No. of or Number Analysis3 Labb Samples

Complete list of Volatiles is shown on Table A.5-1. Complete list of Pesticides is shown on Table A.5-3.

Complete list of Semi-Volatiles is shown on Table A.5-2.

b LAB KEY NCL = North Coast Lab CAL = California Analytical Laboratories PEI = PEI Associates

B&C = Brown & Caldwell ERG = Environmental Research Group JTC = JTC Environmental Consultants

0253s—1

Table A.5-1. VOLATILE COMPOUNDS

Detection Limit (ppb) Compound Soil Water

Chloromethane 10 10 Bromomethane 10 10 Vinyl Chloride 10 10 Chloroethane 10 10 Methylene Chloride 5 5 Acetone 10 10 Carbon Disulfide 5 5 1.1-Dichloroethene 5 5 1.1-Dichloroethane 5 5 Trans-1,2-Dichloroethene 5 5 Chloroform 5 5 1.2-Dichloroethane 5 5 2-Butanone 10 5 1,1.1-Trichloroethane 5 5 Carbon Tetrachloride 5 5 Vinyl Acetate 10 5 Bromodichloromethane 5 5 1,1,2,2-Tetrachloroethane 5 5 1,2-Dichloropropane 5 5 Trans-1,3-Dichloropropane 5 5 Trichloroethene 5 5 Dibromochloromethane 5 5 1.1,2-Trichloroethane 5 5 Benzene 5 5 cis-1.3-Dichloropropene 5 5 2-Chloroethylvinyl ether 10 5 Bromoform 5 5 2-Hexanone 10 5 4-Methyl-2-Pentanone 10 5 Tetrachloroethene 5 5 Toluene 5 5 Chlorobenzene 5 5 Ethylbenzene 5 5 Styrene 5 5 Total Xylenes 5 5

Total Number = 35

A-20

02 53s—2

Table A.5-2. SEMI-VOLATILE COMPOUNDS

Detection Limit (ppb) Compound Soil Water

N-Nitrosodimethyl amine 330 10 Phenol 330 10 Ani1ine 330 10 bis(-2-Chloroethyl)Ether 330 10 2-Chlorophenol 330 10 1,3-Dichlorobenzene 330 10 1,4-Dichlorobenzene 330 10 Benzyl Alcohol 330 10 1.2-Dichlorobenzene 330 10 2-Methylphenol 330 10 bis(2-Chloroisopropyl)Ether 330 10 4-Methylphenol 330 10 N-Nitroso-Di-n-Propylamine 330 10 Hexachloroethane 330 10 Nitrobenzene 330 10 Isophorone 330 10 2-Nitrophenol 330 10 2.4-Dimethyl phenol 330 10 Benzoic Acid 1600 50 bi s(—2—Ch1oroethoxy)Methane 330 10 2.4-Dichlorophenol 330 10 1,2,4-Trichlorobenzene 330 10 Napthalene 330 10 4-Chloroani1ine 330 10 Hexachlorobutadiene 330 10 4-Chloro-3-Methylphenol 330 10 2-Methylnaphthalene 330 10 Hexachlorocyclopentadiene 330 10 2,4,6-Trichlorophenol 330 10 2,4.5-Trichlorophenol 1600 50 2-Chloronaphthalene 330 10 2-Nitroaniline 1600 50 Dimethyl Phthalate 330 10 Acenaphthylene 330 10 3-Nitroani1ine 1600 50 Acenaphthene 330 10 2.4-Dinitrophenol 1600 50 4-Nitrophenol 1600 50 Dibenzofuran 330 10 2.4-Dinitrotoluene 330 10 2.6-Dinitrotoluene 330 10 Diethylphthalate 330 10 4-Chlorophenyl-phenyl ether 330 10 Fluorene 330 10

A-21

0253S-3

Table A.5-2. SEMI-VOLATILE COMPOUNDS (concluded)

Detection Limit (ppb) Compound Soil Water

4-Nitroaniline 1600 50 4,6-Dinitro-2-Methylphenol 1600 50 N-Nitrosodiphenylamine(l) 330 10 4-Bromophenyl-phenylether 330 10 Hexachlorobenzene 330 10 Pentachlorophenol 1600 50 Phenanthrene 330 10 Anthracene 330 10 Di-n-Butylphthalate 330 10 Fluoranthene 330 10 Benzidine 1600 100 Pyrene 330 10 Butylbenzylphthalate 330 10 3.3'-Dichlorobenzidine 660 20 Benzo(a)Anthracene 330 10 bis(2-Ethylhexyl)Phthalate 330 10 Chrysene 330 10 Di-n-Octyl Phthalate 330 10 Benzo(b)Fluoranthene 330 10 Benzo(k)Fluoranthene 330 10 Benzo(a)Pyrene 330 10 Indeno(l ,2,3-cd)Pyrene 330 10 Dibenz(a.h)Anthracene 330 10 Benzo(g,h,i)Perylene 330 10

Total Number = 68

A-22

0253S-4

Table A.5-3. PESTICIDES

Detection Limit (ppb) Compound Soil Water

Alpha-BHC 2.0 0.05 Beta-BHC 2.0 0.05 Delta-BHC 2.0 0.05 Gamma-BHC(Lindane) 2.0 0.05 Heptachlor 2.0 0.05 Aldrin 2.0 0.05 Heptachlor Expoxide 2.0 0.05 Endosulfan I 2.0 0.05 Dieldrin 4.0 0.10 4.4'-DDE 4.0 0.10 Endrin 4.0 0.10 Endosulfan 11 4.0 0.10 4.4'-DDD 4.0 0.10 Endrin Aldehyde 4.0 0.10 Endosulfan Sulfate 4.0 0.10 4.41-DDT 4.0 0.10 Methoxychlor 20.0 0.50 Endrin Ketone 4.0 0.10 Chlordane 20.0 N/A Toxaphene 40.0 N/A Aroclor-1016 20.0 N/A Aroclor-1221 20.0 N/A Aroclor-1232 20.0 N/A Aroclor-1242 20.0 N/A Aroclor-1248 20.0 N/A Aroclor-1254 40.0 N/A Aroclor-1260 40.0 N/A

Total Number = 27

A-23

0305s—1

APPENDIX A.6

SEPTEMBER 1984 AND FEBRUARY 1985 SOIL BORING LOGS

A-24

.Mfootfward-Ctyde Consultants PROJECT namf n>>1 Norte RI/FS N0 • OAINS LOCATION

daillinc acencv Quadrant i

DA ILL »NC CQUlAMtNT g—53

Diamond Core |Q" •*•*»*» Chesbro"

DAILLINC METHOD

>tzc and tvae of casino none

Hollow Stem Jpa ill sit g jnCh

TV At OF AtAFOAATlON

IZE AND TVAt OF HACK ypnc Concrete

F ROW *6 #T faom Q to10 ft

TYAt of UAl None IF MOM TO IT

ELEVATION AND DATUM

ETd.I^tS 9/27/84 1300-I77Q-COMAtETlON death

NO OF IOIST. SAMAlct ; •All

2SiL

WAT EH ILCV. I AST

JL LOOOtO »r

R. Ciegel

SAMPLE A WNDIST.

Cal. Mod, 16

COMA^..

CHECKED »v;

,J« MAS J

QAl»~iC lOC l«HH II II I*

M«MI

Ills MmAu SA'.mj

0- • ; Gravelly soil-very dark, hard-• pan-almost like asphalt-then dajrk

1J. cohesive sandy silty clay with ; much charcoal and organic debriis

2

3

4

5-

6: 7--

Fine sand, brown, moderate sorting lncreaslhg sanfl coaisenesb, yie -r-r^lnr, hpsvy i rnn staining Fine sand, grey, well sorted

Fine to medium grey sand, mois poorly sorted-iron oxides and organic debris

8 - -;; V Water level

9-- Medium, moderatley sorted, grej sand-saturated

i«i:

V n •— < + e

n ¥*• < ft

Sample Numbers

FIELD LOG OF BORING NO.

A-25

SHEET_of

Wootfward-Cfyde Consuttarrts MniPrrutuF np] Norte RI/FS N0

(ODlNC LOCATION Quadrant 1

Cut v AT ION AND DATUM

dwillinc aqincv Diamond Core Chesbro" gi?£ ££,£,15 9/27/84 1030-1200 DOILLINS EQUIPMENT £—53 COMPLETION OEPTM

Hit and type op paca Concrete r "OM o TO10 " TYPE OP SEAL

None r MOM

|i 8 »

o - • ; Gravelly soil

xr

2 - -

3--

4 —

5--

6 - -

7--

8

9

10--

Medium grained sand vith some silt and clay-rones of orange and dark brown sand which diffa only in color-iron oxide stain! twios and other orcanis debris Increasing coarseness and angu lerity of grains with depth-hea ier iron oxide stains

Interbeds of fine to medium sands with iron oxide stains-grey, moist

Water level

Medium, moderately sorted, grey sand, saturated

Cal. Mod.

MtUIIU

Sample Numbers

P

i

•NR-NO Recove

FIELD LOG OF BORING NO. A-26

SHEET_OF

vroocwBro-i*yoe bonsurxarns ewQJECTname Del Norte Kl/FS SORING location NO

CHILLING AOENCV

CLCVATION AND DATUM

DRILLING EQUIPMENT g-53 Diamond Core I0*'"-'* Chesbro 9/27/84 A-XX ICOMH^JTlON OtHTti luyi.it' ' J IT J LI

CHILLING MCTMOO Hollow Stem 3 IDA ILL »IT 6 inch NO O* IDIGT. ISil

(AMMC

UNDHT. Cal. Mod.

-12. HZC ANO Trnc or CAGING Done

None SlZC ANO TVPC or HACK Concrete

MATCH 1'IRST ti-tv i COMRj..

CMECK.CD «v"

»»« HHS

TVHf or UAL None

*hom 5 TSJq rr eh cm Vo

o--; Gravelly soil

1--

2 - -

Sandy, silty clay, dark brown or black with much iron oxide staining

3

4

5

6

72

Fine to medium sand, grey, mod erately sorted, angular

Increasing coarseness, inter-beds of fine, medium and coars sand-poorly sorted, grey

8

9

10+

11

12

Driller says higher moisture content here than at comparabl depths in holes 6,7 and 11

Kater level

Lost samples in heaving sands-vent deeper for samples

Medium, saturated sand with moderate to veel sorting

FIELD LOG OF SORING NO

A-27 SHEET_o<

101-SI1-WP-AYPR-3

Woodward-Clyde Consultants fQAlNC LOCATION PA. .NC WINCY Diamond Core

PROJECT AiAuc n*»l Norte Ki/*s>

Chesbro OAIUI.INC EQUlAMtNT J3-53

SlZC AND TVAC O* CASING NOIlC

0 - -

2 - -

3"" Medium sands, grey, moderately «• sorted w/ some iron oxide stair

7--

8 - -

10"

Concrete hardpan with gravel

Dark cohesive silty, sandy, clay

Increasing silt, sand content

I' Interbeds of fine, medium and "• coarse sands-abrupt transitions

5-. much iron oxide stains and org-•• anic debris

6 - -

Kater level

j. Saturated, medium sands, poorl] > sorted, grey color

1 NR-No Recovery

FIELD LOG OF BORING NO. A-28

SHEET_OF

[•OAiNC LOCATION DA ILL INS AGENCY .Quadrant L4_

DA14.UNG CQUIAMCN? B-53 Diamond Core IDA i LLC A Chesbro

OAILLINS METHOD

HZC AND T*« Of CAJINC

TVAt OA ACA'OAATlON

Hollow Stem EH (IT 6 inch None

-Bene net AND TW or #AC* Concrete jr*OM 0 TO10 rT

IAOM TO rr

T*K or SEAL None r ADM

l i

To FT C«»»-IC lOC

CLCVATION AND datum DATC CTAATCD D*Tl |TC«TID Q/TC/B4 D A T E * I N I E « E D f / A C / O A COMALCTION PC*Tw^Q % |

1030-1130 CAMAlCA

NO or IDIST. JLAMAfcEi! WATCA Jri —Ikiv^

Cel. Mod UNDIET.

LOOSED CHECKED »V:

R. Siegel

Mmuu

0 - -

•Pebbly soil

1-- Dark brown to black sandy, silty i clay w/ numerous pebbles-cohesi ve

« <

Dark brown to black silty, sandy 3j_clay w/ large patches of orange "'materials differing from black ; material only in color-iron oxijd stains-organic debris-very cohe

e sive

« '

5'Brown, poorly sorted sand

6 - -

7--

8 - -Brown, medium sand-moderate sorting

9--

10--

Quartz sand, moderately well sorted in grey clay-unlike any other borings, sharp transitioi at 8ft. 6in.

Sample Numbers

14-4-3 14-4-4

•KR-No Recovery

FIELD LOG OF BORING NO.

A-29

SHEET__ of

(OALNS LOCATION . ,. 15 _ CLCVATION AND DATUM

OA.LL.NG MSINCY Diamond Core Chesbro DATE ATNI$MCD 9/28/84 0930-1030 DA.LL.NC COU.AMCNT B-53 COMMIT,ON OCMT.10 , |VAMAUTACJ.U ^

OM.UL.NC «THOO HOLLOV STM1 8 INCH NO. or IOIST. JuNOltT. _ , GAM»i.Et ; ! 11

Slit AND TVAC CASING NOnC MATCH ;riH»T I CLCV 1

COMAL. ,2* MAS

r 1 TVMI or »c«roAATtON ... ir«OM TO rr. None LOCCCO »T

r. siegel

CHECKED

HJIANO T*H orrACA Concrete jr*OM 8 TO^O "• LOCCCO »T

r. siegel

CHECKED

T*K or tut „ ICAOM TO rr. None !

LOCCCO »T

r. siegel

CHECKED

-tB f i s;

lOC

H MWMI

Jill Mmmq

Cfc- M«a. aa | tl •

0-

1

2

: son

4 Increasing gravel content v/ de ?th

iy Gravel, silt,sand-angular, poor sorted

3

4

5- -

6-

7- -

Interbeds of fine to medium and coarse sand-poorly sorted v/ iron oxide stains and abundant organic debris

8

9

' . V Water level

Medium, moderately sorted, sat urated, grey sand

10--

o n H* < ft K> H r-< ft

. .

To >1

ft

FIELD LOG OF BORING NO.

A-30

Sample Number;

15-4-4

>NR-No Recovery^'"

SHEET_OF

VAjodw*r6-Cty6e Consonants Cr PROJECT M A H ? T)«Q Norte RI/FS_

t3»ihC LOCATION OA.LLINO ABINC* piamonfl Core 15C0-154 5

liAMA4.tR M i l Moa,

JUNDIBT.

T V » i 6 ' A t « » O A A T I O N

utt AND TVAt or RACK Concrete 1VH OA »(Al

atacAiRT«N

• Gravel

Sandy, silty clay-poorly sorted • v/ iron oxide staining

;• Erovn medium sand-moderately 3" sorted v/ iron oxide staining

Water level

g-- Medium sand-moderate to poor sorting, saturated and grey in color

lCh-

r 1 * •

, U>

FIELD LOG OF BORING NO A-31

Sample Numbers]

18-1-1

18-1-2 18-1-3 18-1-4

18-4-1

'NR-No Recovery

SHEET__e»f —

, VPhodward-Ctyde ConsufUnrts^F^ PROJECT Mint n^l Norte RI/FS m0

«OMlNC LOCATION Qnnrtrant L9_ ELEVATION AND DATUM

oa.luno accncy piajnond core 1 DAILLCP Chesbro DAILLINO EQUIPMENT g_53

QAT| ATnumcd 9/28/84 1130—1230 L COM Auction DEPTH IIAM»H«_ .

121 sample*

Cal. Mod.; DAILLINO MCTHQO HO11OV S<,gnt P"'CL».T g

Size AND TYPE or CASING

TYPE O* PCA'OAATlON

NO. or foist. UNDlST.

None

SlZC ANO TYPE or PACK None Concrete

TrioM To rt jrpOM o TO10 FT

pAtee CLtv.

•PlMST

LOOGCO »Y

TYPE or SEAL None JPPOM TO "FT St. Siegel

COMPU. 11

CHECKED »V:

i» HPS f I-

11 i.s

QP>A»->C lOC PmMi ii

t*M*l.tt

m MHMa Opp.wtl [»

0 - -

l-f Rock, cobbles end large pebble! down to 2ft.-no sample

3--

Silty, sandy clay-brown w/ some pebbles

Above grades into medium, poor. 4- - sorted sand w/ iron oxide stair

5--

6 - -

7--

8 - - VJater level

9"

10--

Saturated, medium to coarse, brown-grey sand-poorly sorted Increasing coarseness with depth over this drive

o »i

Sample Numbers

NR* NR 19-1-grab NR (from cutt R for 0-2ft

B l : .«

v

C

i

•NR-No Recover

FIELD LOG OF BORING NO.

A--}?

SHEET_ of

iflVUWIIVM/VC WIIMI1MIIU ...... 4. tOCAT»ON _ . . ti-l (ON

f..uMeMi.e« t>iano«* core Chesbro OATC |TAB71Dfc /TP/64 1330-1430

D«'tL"«C IQWI.MINT B-53 C0M**.C7lON 10 ' Cel. Mod.

Hr l l r - F^«r - r ^ 8 inch 94 c o Olfti ! 1 wt AND Tv.t or CAS.NC jjone El_tV

FIH8T 1 COM... ;j« •> *s

fvAE 6> RA.OAATION TO " tODGCD «v CHECKED »v

iiit and or .Aca Concrete r"""" c TBI0 F 1 J F .. Siegel

none I'"*" TO FT,

| i Ef t

•tftCn*TiO» : ID;

tsiSFra' Msv'iai** •I

f a \ l I I

* I | iili

AtH.HU »*• *•». '•* MI e»' *>• i

« Sarple Kur.bers • t 4

0 -4 Tar or grease stains on surface

« Silty, sandy, clay sliney at "tines-tar and/or grease dis-coloretions and iron oxide stai

a 25-1-1 4

1-Silty, sandy, clay sliney at

"tines-tar and/or grease dis-coloretions and iron oxide stai

H- 25-1-2 4 4

Silty, sandy, clay sliney at "tines-tar and/or grease dis-coloretions and iron oxide stai ns 0

N* 25-1-3

""25-1-4 -2 -

Increasing slitrey nufl content to approxinately 4 ft.

o 25-2-1 Increasing slitrey nufl content to approxinately 4 ft.

1 f- 25-2-2

«

3-

Increasing slitrey nufl content to approxinately 4 ft. <

ft "25-2-3

to ""25-2-4

«

j J n _NR* —25-3-2 (Used SJ •c.

_NR* —25-3-2 (Used SJ

• tiscolored mediun sand v/ blacV a 2 5 - 3 - 3 s p o o n i organic or tar stains

•

u> _JJR pier) 5-* •

organic or tar stains •

€:

7^

8-4

Mediun sand,grey v/ iron oxide stains but no signs of tar or other dark discolorations

o 2 5 - 4 - 1 9-

Mediun sand,grey v/ iron oxide stains but no signs of tar or other dark discolorations

• ¥*• < 2 5 - 4 - 2 4

Mediun sand,grey v/ iron oxide stains but no signs of tar or other dark discolorations ft 2 5 - 4 - 3

l(h 4

4 4

Mediun sand,grey v/ iron oxide stains but no signs of tar or other dark discolorations

* 2 5 - 4 - 4 l(h

4

4 4

>

• •

'NP.-KC Recovery

FIELD LOG OF BORING NO

A-33

SHEET— c' —

101-P.11-WP-A"RR- 3

Woodward-Clyde Consultant* ft

"BOWING LOCATION ON-SITE SOIL BORING 119

PROJECT NAME DEL NORTE mo BIM01

[DRILLING AGENCYDIAMOND CORE |DR!LLINC EQOIPMLNI

|DRILLER k|T QHEESBRO DATE START tu ntTF FINISHED

MOBILE DRILL S3

nflTt riniarn.w COMPLETION DE"M IG- JSAMPLER CAL

- JUNDIST. [DRILLING METHOD H-S AUGER KLZE AND TYPE OF CASING N /A

[TYPE OF PERFORATION N/A

[SIZE AND TYPE OF PACK N/A

IF ROM

J

TO

TO

FT.

TT

JTYPE OP SEAL, NEAT CEMENT • BENTONITE {FROM I 19

ELEVATION AND DATUM N / A

2-3-85

MOD.

NO. OF SAMPLES WATER ELEV.

lDIST.

JFIRST |COMPL. TZ4HRS

LOGGED BY

T. DAUS

CHECKED BY:

PEXTON

i . if 8?

oescwimo*

GRAPHIC LOG

Utfietcfv I I I LM«AITST«OR

(AMPuES

I *» !• I. -J _ REMARKS

I i ill lOnii Raw. Fa«e MM . Odoi.eu.l •I A 1E I

lo­

ll-

12-

Silty clayey medium land Brown oily iheen on bubbles

Clay and lilt content decreasing with depth

35

38

19

119-1-1

119-1-2

119-1-3

119-1-4

21 | 119-2-1

"m-2-2 119-2-3 119-2-4

"119-3-1

18 I 119-3-2

119-3-3 119-3-4

No samples retained. Samples washing out o< tubes.

13

eiELD LOG OF BORING NO.. 119 SHEET_lof J-

A-35

Woodward-Clyde Consultants PROJECT NAME. DEL NORTE NO RI1-101 BORING LOCATION ON-SITE SOIL BORING 120 ELEVATION AND DATUM N / A DRILLING AGENCY DIAMOND CORE DRILLING EQUIPMENT

| PR I LLER KIT CHEESBRO DATE STARTED

DATE FINISHED 2-3-85

MOBILE DRILL 53 COMPLETION DEPTH 10' SAMPLER CAL. MOD.

DRILLING METHOD H.S. AUGER • DRILL BIT 8" NO. OF IDIST.

SAMPLES I UNDIST. 10

SIZE AND TVPE OF CASING N / A WATER ELEV.

FIRST |COMPL. J24 HRS

TVPE OF PERFORATION N / A SIZE AND TVPE OF PACK N / A

ITYPE OF SEAL NEAT CEMENT • BENTONITE

FROM TO FT

FROM TO FT

LOGGED BY

T. DAUS FROM

10 TO 0 FT

CHECKED BY:

PEXTON

SI 1 8 ?

DCSCFTTMO*

G«APHJC LOG

^aiawiir limeiicton V

SAMPLES

III. REMARKS

tO*ill Raw, Fiwd iom. Ooo«. ate.)

I

I 1-;-

2 - -

3 - -

4 —

5 - -

6 - -

7 - -

8 - -

9 - -

10-

Red-brown clayey silt Blocky texture, dry

Red-brown medium silty und Fe oxide

Medium und Fe oxide rich

120-1-2

120-1-3

120-1-4

120-2-1

120-2-2

120-2-3 120-2-4

11

14

120-3-2 120-3-3

120-3-4

13

26

31

1 1 - - -

1 2 - -

13—

FIELD LOG OF BORING NO.

A-36

120 SHEET_Lof 1 1

Woodward-Oyde Consultant* ' - IBORING LOCATION

(DRILLING AGENCV

(DRILLING EQUIPMENT

(DRILLING METHOD

(SIZE AND TV RE OF CASING

[TYPE OF

ON-SITE BORING 121 DIAMOND CORE

MOBILE DRILL S3 H.S. AUGER

N/A

PROJECT NAME DEL NORTE ELEVATION AND DATUM

1 KIT CHEESBRQ

8"

| N/A • FROM TO FT. 1 N/A IFROM To "" PT.

( NEAT CEMENT - BENTONITE JFROM 1£) A o

o FT.

f s w IV s a

DATE STARTED DATE FINISHED

NO,

N/A

RM-101

2-3-85 COMPLETION DEPTH ISAMPLER - 10 CAL. MOD.

OIST- JuNOIST. NO. OF SAMPLES WATER ELEV. 'F,RST jcOMPL. *2* HRS~

LOGGED Bv

T. DAUS

_L jCHECKED BV:

pexton

GRAPHIC lOG

OCSCMirrio Lftfiototv l wemeter P«emn»j | | { f | I £ | ~ | S = >"|

*5 i mliJj ID.-I I • a- •

1 - -

2 —

3 - -

4 —

5 - -

REMARKS

11 R«i». fhim lou. O0o>. «c.l

Red-brown clayey tilt Blocky texture, dry

Red-brown medium tilty tand Fe oxide

6 - -

9 - -

10

1 2 - -

I

Medium tand Fe oxide rich

1 1 - - _

FIELD LOG OF BORING NO.. A 0 1

121

121-1-2 121-1-3 121-1-4

121-2-2

J21-2-3 121-2-4

121-3-1 121-3-2 121-3-3

9 '""121-3-4

121-4-1 8 I 121-4-2

121-4-3 23

SHEET J_ or _L

Woodwartf-Ctyde Consultants project name del norte Mn Rn-101 BORING LOCATION ON-SITE SOIL BORING 122

| PR I

ELEVATION AND DATUM N / A DRILLING AGENCV DIAMOND CORE LLER KIT CHEESBRO DATE STARTED

DATE FINISHED 2-3-85 DRILLING EQUIPMENT MOBILE DRILL S3 COMPLETION DEPTH

10' SAMPLER CAL. MOD.

DRILLING METHOD H.S. AUGER • DRILL BIT 8"

NO. OF IDIST. SAMPLES 1

UNDIST. 15 SIZE AND TVPE OF CASING N/A WATER 'FIRST

ELEV. ! COMPL. J24 HRS

TVPE OF PERFORATION N/A SIZE AND TYPE OF PACK N/A TVPE OF SEAL NEAT CEMENT - BENTONITE

FROM TO FT

FROM TO FT LOGGED BV

T. DAUS

CHECKED BV:

PEXTON FROM 10 TO „ FT

DESCRIPTION

GRAPHIC LOG

LPwierr Imnm InnxllMM* *1

SAMPLES

I Hi REMARKS

(DrU An*. IM Mi. Oooi. rc I

0 - -

1 - -

2 —

3 - -

4 —-

5 - -

6 —

7 - -

8 - -

9 - -

10-

1 1 - -

1 2 - -

13--

Silty fine brown sand

Coarsening downward

Silty medium brown sand Fe oxide holding grains together

Silty medium brown sand

Medium sand, minor silt Fe oxide rich

12

51

_1_22-1-2 122-1-3

"l22-1-4

21

30

37

122-2-1

722-2-2 _122-2-3 JI22-2-4

J22-3-1 _122-3-2 J22-3-3 122-3-4

122-4-1

30

J22-4-2 122-4-3 122-4-4

FIELD LOG OF BORING NO.

A-38

122 SHEET J. of _L

Woodwartf-Ctyde Consultants pro icpt *ua»c pel norte mo Rimoi BORING LOCATION ON.S|TE S0IL BORING 123 ELEVATION AND DATUM N/A

DRILLING ACENCV DIAMOND CORE |DRILLER K|T CHEESBRO DATE STARTED DATE FINISHED 2-3-85

DRILLING EQUIPMENT MOBILE DRILL 53 COMPLETION DEPTH 15. SAMPLER CALMOD

DRILLING METHOD H s AUGER lORILL BIT 8" NO. OF SAMPLES

|DIST. I

18' UNDIST. 1fi

SIZE AND TYPE OF CASING N/A WATER ELEV.

J FIRST •

COMPL. ;za HRS 1

TYPE OF PERFORATION N IFROM TO FT. LOGGED BY CHECKED BY: SI2E AND TYPE Of PACK N/A jPROM TO FT. T. DAUS PEXTON TYPE OF SEAL neaj cement . BENTONITE F °M ^ TO 0 FT.

GRAPHIC LOG * SAMPLES

I t OESCMIFTIOM LrtAoioey Fwoflwix •amMimwi

a t

*5 |I £ l >

t t e

LLL^ £ * S m

REMARKS

(Oral Am*. Fki«i mm. Oooi. nc.l

0-

1-Gravelly clayey und 45

1-43 123-1-2

123-1-3

5-32

123-1-2 123-1-3

6 123-2-1 123-2-2

3- Medium-grained und Fe oxide coated grains

8 123-2-3 3- Medium-grained und

Fe oxide coated grains 16 123-2-4 123-3-1 123-3-2 -4 —

20

123-2-4 123-3-1 123-3-2

37 123-3-3 123-3-4

A — 29

123-3-3 123-3-4

6-

7-

8-

9 -21 "123-4-1 9 -

Medium sand Fe oxide rich

31 123-4-2

10-

Medium sand Fe oxide rich

22 123 4-3 123-4-4

10-

11-- -

12-

13-

FIELD LOG OF BORING NO 1£3 SHEETJ_of_L

Woodward*Clyde Consultants €r project namf del norte N0 rimqi

I : * »

S I D£KC*iPTlOK

*-<C IOC 5 • • I I * a

SAMFUS I : * »

S I D£KC*iPTlOK l<tno<a«v

*1

5 • • I I * a

i i \ i!)«

» t - s *

MIMAS KS IDoii *«t. fiyi« ieti Oos'. «tc I

13

14-

15-

: •

10 "123-5-1

13

14-

15-

: •

10

40

123-5-2 123-5-3 123-5-4

16-

17-

18-

19-

20-

21-p 4

22-

-

23-

24-

25-

26--•

- • ,

27--• , 4

*

28-- * '

- •

29-- « •

• • ,

30--•

« . «• -

• •

FIELD LOG OF BORING NO 1J3 SHEET_Lof_l

A- 40

Appendix B

Hydrogeological Investigation:

Groundwater

APPENDIX B.l

WELL LOGS

Woodward-Ctyde Consultants project name del norte no rimoi SORING LOCATION MONITORING WELL NO. 2 ELEVATION AND DAT UM 45.89 DRILLING AGENCV DIAMOND CORE dr i l le r < i t cheesbr0 DATE STARTED

DATE F INISHED 1-30-85

DRILLING EQUIPMENT MOBILE DRILL 53 COMPLETION DEPTH 30, SAMPLER SPLIT SPOON

DRILLING METHOD H g AUGER DRILL BIT 8" NO. OF SAMPLES

DIST. .

N/A I UNDIST. 5

SIZE AND TVPE OF CASING j" PVC SCH. 40 WATER ELE V.

FIRST 3' I COMPL. 124 HRS 1

TYPE OF PERFORATION FROM 30 TO 5 FT. LOGGED BY CHECKED BY:

SIZE AND TYPE OF PACK SLUFF AND 12 x 20 SAND

FROM 30

•

TO 4 FT. S.L. WINTERS PEXTON

TYPE OF SEAL BENTONITE PELLETS FROM 4 TO 2 FT.

G«APF : lOG - SAMPLES

E R A z o it

DESCRIPTION LITFTOIOEV P»«IOMETE' INTUILAIION

£ | £ o u

1: * £

© 2 | > 0 U *> * £ - 1 »I£1O

REMARKS

(DULL RATE. Fimo LOTT. OOO1 ATC.L

Surface sediments; brown clayey fine to medium sand; "soft clay" (by strength test)

0-

1-

Start -830 AM

2-

3-— First sign of water (s> 3'

Sample at 354' washed out and not retained (i.e. can't hold sand in sampler)

4-

Sample at 354' washed out and not retained (i.e. can't hold sand in sampler) 18 Seems to be some

resistance to hammer blows from rig cable

4-22

Seems to be some resistance to hammer blows from rig cable

5- Sample at 5' washed out 20

5- Sample at 5' washed out 2

4 2nd attempt to obtain sample

6 -8

7-

8-

9 -6

18

10- In shoe at 10' — silty/clayey fine sand sub-angular 39

MW-2-1-2

MW-2-1-1 (Note tube numbers are reversed due to error) Both samples sealed with teflon for organic analysis

11-

and well-rounded quartz grains; color laminations [ <%" thick, brown and gray.

Soft clay; sample in tube at 10' - 9' 8" seems to - have coarser sand and more silt; some mica flecks

MW-2-1-2

MW-2-1-1 (Note tube numbers are reversed due to error) Both samples sealed with teflon for organic analysis

12-

13-

FIELD LOG OF BORING NO Mw~2 SHEET_LofJL B-l

Woodward* Ctyde Consultants PROJECT NAMF DEL NORTE M O R I 1 - 1 0 1

DESCRIPTION QCIT-

L'ihO'09> P**/e*T»etf lnit*nai lO*

SAV wfcS

r' ? K REMARMS i0* <1 • R*it f it, c iovv Ooi.

13-r

14 —

15 —

16-r

17-

4 18—r

1

T T 19 1 4

20 — 4

21 —

22 —

23 —

24 —

25 —

26 —

-r 27 —

2 8 - -

29

30-

In shoe at 15' — fine to medium quartz (50-70%) sand; silty, but less silt than above; little clay in sample some mica flecks; sands well-rounded and sorted; tubes have similar lithologies; at 14' 2" mottling (similar to that observed in last sample) seems to end

In shoe at 20' — well-rounded, moderately sorted fine to medium sand; silty with some clay; clay very soft, some mica long cylindrical objects (< 0.6 mm) observed

Problems with sampling; can't sample past 20'; 10' of slough of liquified sand pushing up auger. Will auger to ~35' without taking samples

Boulder encountered — evidently, boulder pushed f fpa to side since formation very loose /r w

19

I !

17

i 45

MW-2-2-3

MW-2-2-4 (Sealed with teflon for organic analysis)

MW-2-3-1 (Teflon sealed for organic analysis)

Note: Tube number and depth do not correspond - I believe tube number wrong.

FIELD LOG OF BORING NO B-2

MW-2 SHEET J. of _L

Woodward-Clyde Consultants W projfptnamf DEL NORTE KN RM-IQI

DESCRIPTION L'tno>og> IflUI'iltO'

» i 5 • 5 f ? REMARks ID"1- Rait *-w c *Oii Ooc f 1;

30-|-

31

32

4 i

33 -F

-T 4 T

34

a 35-R

: •t

36T 37 1

38 —

39 —

40-

41-4

4-42-f-

-f 4

43 + 4 4 4

44-

45-

46-

47-

— 1040 AM — over-drilled hole to 40'; dark gray silt observed with 10-20% clay; makes mudballs

— 1130 AM — can't get casing into hole; attempting to pound sand bridge or plug out; —1145 AM — can't get bridge out; pulling up augers and re-drilling hole this time plugging hole; as augers pulled up, observed fine to medium sand with —5% >2 mm particles, including one shell fragment on auger blade at 15 to 20'

Casing in at 1236 PM — 12' of PVC casing pulled up, -9' sawed off

Completion depth —30' below surface

Monterey sand used to fill hole below casing, which is estimated at —13' (3 bags of sand was used)

i i j i

I I

FIELD LOG OF BORING NO MW-2 B-3

SHEETJLOI JL

Woodward-Ctyde Consultants project name del norte no Rimoi 0ORING LOCATION MONITORING WELL NO. 3 (See work plan) ELEVAT ION AND DATUM 46.70

DRILLING AGENCV DIAMOND CORE DRILLER <|T CHEESBR0 DATE STARTED DATE FINISHED 1-30-85

DRILLING EQUIPMENT MOBILE DRILL 53 COMPLET ION DEPTH 29 5, SAMPLER SPUTSPOON

DRILLING METHOD H S AUGER DRILL BIT 8" NO. OF SAMPLES

|DIST. I

N/A UNDLST. 7

SIZE AND TYPE or CASING 2" PVC SCH 40 WATER E L E v .

|FIRST 1 7' COMPL. |2« HRS

1 TYPE OF PERFORATION #2Q [FROM ^

< TO 4.5 FT. LOGGED B Y CHECKED B Y :

SIZE AND TYPE OF PACK SLUFF AND 12 x 20 SAND

FROM 29.5 TO 4.0 FT. S.L. WINTERS PEXTON

TYPE OF SEAL BENTONITE PELLETS FROM . 4

TO 2 FT.

G R A F - >C LOG SAMPL ES z -

a u. UJ 0

DESCRIPTION L'lhOIOQv Piezometer installation

. e • *> • £ i 0 V

i ; £ • z 0 £

0 z 1 >

» c w L c . 2 > z. 0 ®

REMARKS

(Oft" Rate. PiufO loss. Ooo>. etc »

fo

-»

O

1 1 1 1 I 1 1

1 1

1 i • 1 • 1 1 1 1 *

Start ~14:40 — surface sediments: Well-graded gravel, seems to be former parking lot surface; abandoned first attempt and moved to ~10' closer to fence

fo

-»

O

1 1 1 1 I 1 1

1 1

1 i • 1 • 1 1 1 1 *

Soil at ~2' 1" beneath gravel surface; soil very black with pebbles

3-

4-

sample; soil attached to side of sampler is a - clay with 1b-20% fine to medium sand

soft

5 for

- • 18"

5-

•

6-

In shoe at 5': Contact of brown clay with gray fine to medium quartz-rich sand, grams well-rounded. In tube 4, brown medium sandy clay coarsens downwards

MW-3-1 -2 5-

•

6-

In shoe at 5': Contact of brown clay with gray fine to medium quartz-rich sand, grams well-rounded. In tube 4, brown medium sandy clay coarsens downwards

MW-3-1-4

7-

8-

• -2. Water

q -7

8

10- In shoe at 10' — fine to medium gray sand, well-rounded & sorted; 10' to 9' 8" tube looks sillier than above, brown organic material in sand (~1 mm long)

7 MW-3-2-3

MW-3-2-4 10- In shoe at 10' — fine to medium gray sand, well-rounded & sorted; 10' to 9' 8" tube looks sillier than above, brown organic material in sand (~1 mm long)

MW-3-2-3

MW-3-2-4

11- ~ 9' 4" to 9' tube shows silty sand grading to fine to medium sand

12-

13-

FIELD LOG OF BORING NO MW'3 SHEET_Lof_L

B-4

Woodward-Ctyde Consultants P R Q J F f l T M A M F DEL NORTE NN RI1-1Q1

13 t

14-r

15-

16-4-} t

17-^-

18—i-

i 19-

4 -f *r •+

2 0 -

21 —

22 —

23 —

24 — T

27-

28-

29-

30-

DESCSIPTION

In shoe at 1 5' — mottled gray and brown fine to medium sand; red-brown (oxidized) streaks in brown and clayey sand

In shoe at 20' — medium, well-rounded and sorted brown sand; little silt, relative to above (15')

G-fir- : iGG

LMftO'OQt

25 Shoe at 25' — same as 20'

26 —

~ 16:41 — attempted to install PVC but fine ~8' slough; casing removed; well must be redrilled

mtU"«1<0

15

25

35

i 2

I 1 8

iDiii Rait c ,on Go:

MW-3-3-3

MW-3-4-3

MW-3-4-4

FIELD LOG OF BORING NO

B-5

MW-3 SHEETJ. of JL

Woodward-Ctyde Consultants PROJECT NAME DEL NORTE N0 RIMOI BORING LOCATION MONITORING WELL NO. 4 (Under spruce trees)

2

1 O

>

UJ J

UJ

AND DAT UM 45.17

DRILLING AGENCY DIAMOND CORE DRILLER K|T CHEESBR0 DATE STARTED DATE F INI SHE D 1-31-85

DRILLING EQUIPMENT MOBILE DRILL 53 COMPLET ION DEPTH __ ZY.D 1 SAMPLER SPL|T SPOON

DRILLING METHOD H S A|JGER DRILL BIT 8" NO. OF SAMPLES

|DIST. 1

N/A [UNDIST 10 I

SIZE AND TYPE OF CASING PVC SCH 4Q WATER ELE V.

(FIRST I 4' |COMPL |24 1- i R S

TYPE OF PERFORATION ..„ IFROM „ _ w20 i 4.5 TO 29.5 FT' LOGGED BY CHECKED BY

SIZE AND TYPE OF PACK SLUFF AND 12 x 20 SAND

FROM . n 4.0 TO 29.5 FT T. DAUS PEXTON

TYPE OF SEAL BENTONITE PELLETS FROM 2.0 T° 4.0 FT.

PEXTON

GPAPHI: LOG SAMPJ.ES 5 *-

© t. DESCRIPTION LITOOIOEV P»«LOM«TE'

TNST»IL*IION

. e « ti 5 c £ © u ii

&

0 Z 1 »

> 0 U * l-L~ I r i s % 2 e 10

REMARKS

(DNLI RAIT, FTUIFL LOTI, ODO«. TIC I

0-

1 -

2-

Silty, sandy loam 0-

1 -

2-

3-3

16 MW-4-1-3

OL

^

I.I _l I I I I 1

A I

— W a t e r 18 MW-4-1-4

OL

^

I.I _l I I I I 1

A I

Fine to medium brown sand with some minor coarse sand and silt. Grains are medium sorted and sub-angular. Fe oxide coating on some grains. > 50% quartz, assorted dark minerals

6-

7-

8-6

8-

Subangular to well-rounded, well sorted gray sand. 9 MW-4-2-3

9 -

> 50'c quartz 9 MW-4-2-4

10-

11-

12-

Well rounded fine-grained gray to black sand, minor

13-

medium-grained sand and shell fragments, some [_ roots interbedded well rounded fine-grained brown 20

sand with minor medium-grained sand stringers, both sands >50% quartz

FIELD LOG OF BORING NO MW'4 SHEET_LOF_L B-6

Woodward-Clyde Consultants (r project name del nor te no r l1-101

DESCRIPTION

13-r

14->-

15 —

16-1

17'

18—t-:

4-

20 —

21 —

-t--t-22 —

23 — t

24 — 1

25— 4

26 — j.

-27 —

284-

29-I

30 4-

Well rounded fine-grained brown sand, minor silt. > 50% quartz

Black silty fine sand

g«ap-.: ici L'TNO'OQT

Subangular, moderately sorted fine to medium-grained sand with minor silt

Brown moderately sorted fine to medium-grained quartz sand

Consolidated sandy clay with lots of shell fragments

P-ejomffie- 5 = i4a> RtMAO»,c

• i t P r - c m O OL — •

— jr-*

45

20

31

i :

MW-4-4-3

MW-4-4-4

Sluff material 3-4 ft in hollow stem, unable to retrieve sample

MW-4-5-3

MW-4-5-4

f ie ld log of bor ing no

B-7

MW-4 SHEET_Lo<_L

Woocfward-Ctyde Consultants PROJECT NAME DEL NORTE Mfi RH-101 BORING location MONITORING WELL NO. 5 e le vat ion AND DAT UM 47.93

DRILLING AGENCV DIAMOND CORE driller k|t cheesbr0 DATE STARTED DATE F INISHED 1-29-85

DRILLING EQUIPMENT MOBILE DRILL 53 completion dept* * 30' SAMPLER SpL|T SP00N

drilling method h s auger DRILL BIT 8" NO. OF SAMPLES

|DIST. N/A UNDlST. g

SIZE AND TYPE OF CASING PVC SCH 40 WATER ELEV.

[FIRST I 3' compl. \7* HRS

1 TYPE OF PERFORATION

*20 F ROM 30 TO 5 FT. LOGGED BY CHECKED Bv

SIZE AND TYPE OF PACK SLUFF AND 12 x 20 SAND

from 3q TO 4 FT. S.L. WINTERS PEXTON

TYPE OF SEAL BENTONITE PELLETS FROM TO 2 FT.

g«ap* IC LOG . sampLes z -0. w UD UJ o &

DESCRIPTION Lithoiopy Pittometer installation

- Z £ " 5 c 5 © u

u £

0 z

>

> 0 w «< 1:1s

SIO

REMARKS

(DM" R*te, FiuiO ion. Ooo'. etc i

Weather: Clear, sunny, ~45"F Start 930 AIV Surface sediment dark brown dirty well-rounded medium sand — some cobbles and wood fragments

0-

1-

2-

3-

• -2- Water

2 4 — - Sand saturated 3V4 to 4'; no sample can be

obtained — runs out of tube -

- Sand saturated 3V4 to 4'; no sample can be obtained — runs out of tube 1

1

6"jj

Sample taken at 7' 7" gray quartz-rich well rounded fine to medium sand with some ( £ 10%) MW-5-1-4

8-_ silt. Wide variety of minerals, many park; MW-5-1-4

animal hair

10 Q -

11 MW-5-2-3

10-12 MW-5-2-4 10-

gravel 1/8" to 1/4" with Fe-staining at root (Analyze for organics)

holes and around gravel;

11- "" Fine to medium sandy brown clay (all grains s0.5mm) sediments retain shape on squeezing low water content, some mica flecks

12-

13-

FIELD LOG OF BORING NO Mw'5 SHEET_LofJL

B-8

Woodward-Ctyde Consultants €r prqjftt name del norte Nn rimoi

GRAP LOG SAN«tlS

& **• DESCRIPTION L'lioiog* P'tJOmW IfHWHil.O*

£ | * •

£0 JJ a

c 2 1 > » c £

f i n Z £ s J

REMARKS

iD"1- R»te E»wO 'on Goo-

13-, Knot in cdblc

14- • 5 @ 1030 AM

14' 4" to 14' 8" well-rounded fine sand with 35

15-some medium grains ( ~VS mm) 15' Silty fine sand with minor pebbles 34

(Sand finer than at 10') MW-5-3-4

16-

•

17T i

i ! 1 | i j

00

_4 4

-4

.<

- • ! i i

19-2- ! 1 |

20-i 4 «+

Same as above with grains up to 1" (Track of animal hair)

MW-5-4-4

21-

4 22-

N

Sands "heaving" at ~ 21 % ft. (1100 AM) adding water to auger head

23 — i

24-4 6

12

25— In shoe — brown fine sand with minor silt ( ~25%) well-sorted, well-rounded, some mica flecks; coarses up between 25' & 24' 8" tubes

31 MW-5-5-4

J 26-2

In shoe — brown fine sand with minor silt ( ~25%) well-sorted, well-rounded, some mica flecks; coarses up between 25' & 24' 8" tubes

1134 AM — waiting to fill auger with water

i •t

27 —

28--

29— •

30 4 •

FIELD LOG OF BORING NO MW"5 SHEET_2_0f JL

B-9

Woodward-Ctyde Consultants €r PROJECT NAME. DEL NORTE NO RI1-101

c. -

30 —

31-!-

32-

33-4

34-r

0. 35-^ : t

36 —

i -r 4

37 4

-38—<-

4 -i

40 —

i 41-t-1

42 —

2

43

44 ^

45-

46-

47-

descrlptlom

In shoe at 30' — dark gray to black fine to medium sand with some grains up to —1% mm; some shell fragments ( J£ 10%) up to 4 mm; silty, well-rounded sand, fine-grained particles more sub-angular

Problems with heaving sands coming into auger when plug removed to install casing. Well was re-drilled with rods holding plug in place to ~33' (i.e. over-drilled hole)

Drillers worried PVC casing will come up hole, but has not moved

Screen at 6' below grade ( ~ 247 PM)

Sand-pack consists of mainly formation sand; only -1-1/3 100-lb Monterey sand bags used as sand pack; two more bags added when augers removed

1/2 bucket bentonite added (6:1 cement to bentonite mixture) from 3%' to surface

: LC.;,

litno'oqt P-eio*p*»te

as - _ -j _ 1 "'marks 11 ff «"v' -= "" ooi'-

- "5 oughing •cise depth in — comple-? 30'

FIELD LOG OF BORING NO.

B-10

MW-5 SHEETJ. of _JL

Woodward-Ctyde Consultants ClF project name del norte no rimoi

BORING LOCATION MONITORING WELL NO. 6 ELE VAT ION AND DATUM 44.65 MSL

DRILLING AGENCY DIAMOND CORE DRILLER K|T CHEESBRO DATE STARTED DATE F INI SHE D 2-1-85

DRILLING EQUIPMENT MOBILE DRILL 53 COMPLETION DEPTI- 30' SAMPLER SPLIT SPOON

DRILLING METHOD HS AUGER DRILL BIT 8" NO. OF SAMPLES

DI5T. N/A UNDIST. G

SIZE AND TYPE OF CASING 2" PVC SCH. 40 WATER ELEV.

FIRST N/A ! COMPL. |24 HRS

TVPE OF PERFORATION #20 J F ROM 3Q 1

TO 5 FT. LOGGED BY CHECKED BY

SIZE AND TYPE OF PACK SLUFF AND 12 x 20 SAND

FROM 30 TO 4 FT. S.L. WINTERS PEXTON

TVPE OF SEAL BEMTONITE PELLETS FROM 4 TO 2 FT.

GRAPfiiC LOG SAMPLES I —

L F yy III O It

DESCRIPTION Lit*O>O0V P«<iometer

tnntiliiiofh

- c •> 5 e u

H z o £

e 2 t >

> e z

1;!-

£ z. £ ip L —

REMARKS

IDnli Rats. Fluid lotv OdO'. flc 1

Start <s> 13:46 — Red-brown clay soil with

0-

1-

2-

3-

medium to coarse sand ( ~5%) at surface

4-

-

3 4-

-• 4

Hit 14 times more to

8 ensure sample took

5-

6-

7-_

8-

Brown coarse feldspatic sand, silty ( — 20%) 8

MW-6-1-3 MW-6-1-4 (ANAL)

5-

6-

7-_

8-

Brown coarse feldspatic sand, silty ( — 20%) MW-6-1-3 MW-6-1-4 (ANAL)

9~ 13

9~ 21

38 Hit 13 more, as above 10- Inn first samDle- lost 2nd sartlDle took auaer down 10-

one foot to attempt one more sample

11- _ln shoe — fine brown sand at shoe tip, but 2" up medium sand like above; brown staining and streaking in fine sand; sample not retained

12-

13-

FIELD LOG OF BORING NO MW"6 SHEET_Lof_L

B-ll

Woodward-Ctyde Consultants (r PROJECT NAME. DEL NORTE N0 R11 -101

description geae- : lgc

?? n REMARKS

R*ie iovs Go; n:

13-

14

15 —

16 —j— ;

17-

18-

19 t T

T 20 — -f

2 1 —

-r -t 22 —

-t -*

23 — -r T

24 — -j-

25 —

26 — I

27-r

28--

29 —

In shoe at 15' — gray to black or bluish fine silty sand; light quartz grains like "salt" in abundance of pepper; some brown organic material at top of tube 3

In tube 4 — dark gray or bluish medium sand; some pebbles at base of tube 4 (~ 3 to 4 mm) piece of corral?

Shoe at 23Vi — fine to medium bluish or dark gray sand. Material in base of tube 4 is silty but sand coarser than in shoe; organic brown material, 2 to 5 mm; tube 4 only Vi full; other tubes discarded

30 ~ 7' of slough in hole — no sample taken

12

18 43

37

i ! 43

50

26

50

MW-6-2-3 MW-6-2-4 (ANAL)

MW-6-3-3 MW-6-3-4 (ANAL)

FIELD LOG OF BORING NO

B-12

MW-6 SHEET.! of -L

Woodward- Clyde Consultants project name del norte no rimoi

B O R I N G L O C A T I O N MONITORING WELL NO. 7 (Near road) E L E V A T I O N A N D D A T U M 43.50

D R I L L I N G A G E N C Y DIAMOND CORE |D R I L L E R K , T C H E E S B B O D A T E S T A R T E D D A T E F I N I S H E D 2-1 85

D R I L L I N G E Q U I P M E N T MOBI LE DRI LL 53 C O M P L E T I O N D E P T H 30' S A M P L E R S P L | T S P O O N

D R I L L I N G M E T H O D ^ g AUGER ID R I L L B I T 8" N O . O F S A M P L E S

D I S T N/A I U N D I S T . G

S I Z E A N D T Y P E O P C A S I N G 2" PVC SCH. 40 W A T E R E L E V.

F I R S T 3' ' C O M P L | 2 A HRS l

T Y P E D F PERFORATION ^ 2 0 jFROM g l

TO 30 F T . L O G G E D B Y C H E C K E D B Y :

S I Z E A N D T Y P E O F P A C K . F R O M + SLUFF AND 12 x 20 SAND! *

TO 30 F T . T. DAUS PEXTON

T Y P E O F SEAL BENTONITE PELLETS jF R O M 2 TO 4 F T .

GRAPH C L O G - S A M P LES

5 C $ z o £

D E S C R I P T I O N Lithoiogy Fitzomtter (munition

. c • * t © u 11 *

a

e Z I >

> O w I I N

R E M A R K S

(Or>11 Rate. Fiwid lent Odo-. etc )

0- Black silty clay topsoil

•

1-

2-

- -2. Water

Brown medium-grained sand 3-- -2. Water

Brown medium-grained sand 5

(Fe-oxide staining on sands) 4 MW-7-1-3

4 MW-7-1-4

5-Sand grains are well rounded moderately well sorted, lots of roots

6-"

7-

8-8-~ Same as above 10

10 MW-7-2-3

9 -35 MW-7-2-4

10-

11--

12-

13-

FIELD LOG OF BORING NO Mw"7 SHEET J_of_L B-13

Woodward Clyde Consultants PRQJFOT MAMF DEL NORTE NO FT"-101

description oBAt-.: toc

LitnoiOQy * = I; REMARKS ID" ' - Rut f iw c -ow Goi t : :

13 —

14-^

15-1-

16 -r

17-

4 18—h

t 4

, 9 T

»i

21

t -t

22 —

23 —

24 — 4"

25 — t ~

26 —

27-

28h

Gray-black silty tine sand Sand >50% quartz

Brown silty fine sand > 50% quartz with minor mica, some minor coarse material

Semi-consolidated material possibly St. George

29-H

30-

17

23

32

MW-7-3-3

MW-7-3-4

I !

17

32

: 50 for ' 51'

MW-7-4-3

MW-7-4-4

i !

Sluff material 4 to 5 ft into the auger stem; sluff material is silty fine sand

FIELD LOG OF BORING NO MVV-7

B-14

SHEET_£_0f

Woodward-Clyde Consultants project name del norte Mn rimoi BORING LOCATION MONITORING WELL NO. 8 ELEVATION AND DATUM 47.12 DRILLING AGENCY DIAMOND CORE |DRILLER K(T CHEESBRQ OATE STARTED

DATE FINISHED 2-2-85 DRILLING EQUIPMENT MOBILE DRILL 53 COMPLETION DEPTH SAMPLER SPLIT SPOON DRILLING METHOD H S AUGER |DRlLL BIT 8" NO. OF

SAMPLES |DIST. N/A 'UNDIST. N/A

SIZE AND TYPE OF CASING j" PVC SCH. 40 WATER ELEV.

(FIRST N/A COMPL. |24 HRS

TYPE OF PERFORATION 1FROM c #20 i 5 TO 30 FT. LOGGED BV CHECKED BY

SIZE AND TYPE OF PACK .FROM -SLUFF AND 12 x 20 SAND! 4

TO 30 FT. T. DAUS PEXTON

TYPE °FSEAL BENTONITE PELLETS iFROM 2 TO 4 FT.

GRAPHIC LOG SAMPi.ES S £ t u O -

DESCRIPTION L«thorn® v P»*ZOMCT«R INTUII«IIOR

5| £ o u

Is s° £

0 z & >

> 0 w * X fili

REMARKS

ID'T" RATE. PIWIO »©u. OOOF. ttc i

0- 6" black humus

1- Brown fine to medium-grained sand, subangular grains, Fe oxide staining, moderately sorting

2-

3- Slightly fining trend with depth

4-*

r -5-

6-

7-

8-m

9~

10- Fine silty clayey sand, brown color

12-

Black medium-grained sand with finer sand fraction

13-

'

FIELD LOG OF BORING NO Mw"8 SHEET_LofJL

B-15

Woodward-Ctyde Consultants €r PROJECT NAMF DEL NORTE Nn RI1-101

description GCAC- : iGC

L>t*o»Oflv P«eiD»«»ir 11 hi!

RE VABX.S

ID-.-. R#ie f c oi> Ooi- ft;

13-r

14 —

15 —

16 + 4

17-r 4

184 t

19 +

J 21 —

t-•*

22 — -r —

23 — -t

. :

24-4 T n-

25— : 26-

4. 4

27-

28-

29-

30-

Brown fine grained sand, well rounded > 75% quartz, minor mica and heavy minerals. Fe oxide streaking in the sand minor silt fraction

i i

FIELD LOG OF BORING MO MW-8

B-16

SHEET_2_O<_L

Woodward-Clyde Consultants PROJECT NAME DEL NORTE NO RI1-101

DESCRIPTION

30-r

31-1-

32 —R

33-J-4

34 —

35^ i

36 t

37 ~ -t

38 —

«* 39 —

4

40 —

I -T

41 —

42 —

43-

44-r

45-

46-

47-

— —— Sharp contact

Black semi-consolidated sandy silty clay, lots of shell fragments

G-it- Z ,GG

L-tno>og, P.«/o>n#ir o t :

SAN'C.iS

i !

R£MAB».C

i0*-' fi, c cii Oai" 9':

* *** +,

U'l 1

FIELD LOG OF BORING NO.

B-17

MW-8 SHEET_lof_L

BORING LOCATION ^75, FRQM STORAGE AREG FENCE ELEVATION AND DATUM

DRILLING AGENCY D;AMOND CORE DRILLER MJKE Colbert DATE STARTED 4/07/OC DATE FINISHED ^UHOO

DRILLING EQUIPMENT MOBJ| DRJ| | COMPLETION DEPTH 32% feet

SAMPLER ... None DRILLING METHOD 8„ Hollow-Stem Auger DRILL BIT NO.OF IDIST.

SAMPLES UNDIST.

SIZE AND TYPE OF CASING 2" ID Schedule 40 PVC WATER FIRST ELEV.

COMPL. |24 HRS 1

TYPE OF PERFORATION 0.020" Machine Slot iFROM 32% TO 7% FT' LOGGED BV

Rob Pexton

CHECKED BY:

Steve Winters SIZE AND TYPE OF PACK IFROM TO o FT

4% 100lb baas No. 3 Monterey Sand! 32/s 6

LOGGED BV

Rob Pexton

CHECKED BY:

Steve Winters TYPE OF SEAL Cemem ^ Bentonite jFROM g TOl FT.

LOGGED BV

Rob Pexton

CHECKED BY:

Steve Winters

I p 0- w UJ U1 o i

GHAPHiC LOG

DESCRIPTION £ s eo ?si: REMARKS

(DMH Rate. Fluid loss. Odoi. etc.)

- Black organic-rich topsoil • Brown topsoil

Light brown well-sorted subangular to - subrounded silty fine sand with variable

amounts of clay (0-10%) 5--

1 0 - -

15--

20--

25--

30--

35-

Blue fossiliferous silty mudstone at 32 feet

"H-NU" at 32.5' 2 ppm versus background of < 0.2 ppm

FIELD LOG OF BORING NO.. MW-25 SHEET J_ of _L

Figure 2. FIELD LOG OF MONITORING WELL 25

Woodward-Clyde Consultants PROJECT NAME. Del Norte NO.. MW-26 B O R I N G L O C A T I O N _ 2 0 C ) , ^ Q F Q E N T E R F E N C E

D R I L L I N G A G E N C Y Diamond COre D R I L L E R Mike Colbert

E L E V A T I O N A N D D A T U M

D A T E S T A R T E D 4 / 0 7 / D C D A T E F I N I S H E D ^ U U O O

D R I L L I N G E Q U I P M E N T Mobil Drill C O M P L E T I O N D E P T H 33feet„

S A M P L E R None

D R I L L I N G M E T H O D 8" Hollow Stem Auger D R I L L B I T

S I Z E A N D T Y P E O F C A S I N G | Q PVC SCH 40

N O . O F S A M P L E S

W A T E R E L E V .

D I S T . UNDIST.

F I R S T ! C O M P L . 24 HRS i

T Y P E O F P E R F O R A T I O N Machine Slotted 0.02" I F R O M 33 TO

S I Z E A N D T Y P E O F P A C K 4% 1001b baas No. 3 Monterey Sand

] F R O M 33 T O

T Y P E O F S E A L Cement over Bentonite | F R O M T O

L O G G E D B Y

Rob Pexton and Steve Winters

C H E C K E D B Y :

Steve Winters

x p C. UJ

GRAPHIC LOG

DESCRIPTION Lnhoiogy Ptejomeitrr Installation 5 e

REMARKS

(Dull Rate. Fiuid loss. Odor, etc.)

4. Dark brown organic-rich soil over reddish brown soil. At 2', blue-grey clayey sandy silt (clay "very soft")

5--

1 0 - -

15-

20--

25-- Cutting at 25' coarser than above i.e., medium L silty, clayey sand

30 +

33

35

At 30' at 9:15a.m.; pulling plug~@ 9:21 Some sand coming in auger. Pulling augers at 9:33. At 9:29 must redrill back to 30' and go to ~ 35' (sands "heaving" badly) At 33' hit dense material i.e. "clay". Rod bounces or jolts. Plug pulled (2nd time) and insert casing at 9:53a.m.

Drilling at 8:30a.m.

"H-NU" reading at 25': ~0.2ppm or at background

FIELD LOG OF BORING NO. MW-26 SHEETj_of J_

Figure 3. FIELD LOG OF MONITORING WELL 26

0112s—10

APPENDIX B.2 GRAIN SIZE DISTRIBUTION DATA

B-20

SIEVE ANALYSIS

BROCBCT HA/)/(,* Tf PROJECT NO. /<5/-7?I / .Aam.H

SAMTLE VD.W l<) A*'?'-*? DATE ~jTI^gP

^ ' description tested by

tlZfCi f.7 ~to

reduced by >*[ (3so!^ checked by /" >sl ~.

COARSE SIEVE ANALYSIS

WT. AIR DRY SOIL RETD. #10 cms. w. air DRy S0JL pASSING #10

WT. OVEN- DRY SOIL RETD. #10 QMS. HYGROSCOPIC WATER CONTENT gms. %

gms. WT. OVEN DRY SOIL RETD. ON ^ 0V£N DRy S0JL pASSING §lQ

#10 AFTER WASHING _GMS. TOTAL WT. DRY SOIL PASSING #10 QMS

TOTAL WEIGHT OF DRY SOIL USED IN TEST GMS (W )

SIEVE SIZE CUMULATIVE WT. RETAINED ON SIEVE % PASSING

2"

IV

1"

3/4" f o o . o

1/2"

3/8" 3«. 2H.it>

FINE SIEVE ANALYSIS

WT. OF AIR DRY SAMPLE USED IN TEST GMS. WT. OF OVEN DRY SAMPLE GMS. (W )

s

NO. 4 HYDROMETER MATERIAL-MULTIPLY BY % PASSING #10 SIEVE NO. 10

HYDROMETER MATERIAL-MULTIPLY BY % PASSING #10 SIEVE

NO. 16 72 9S 5 * 7 - 6 9

NO. 30 ?8.?9 £5-6*4

NO. 50 £ /<SL

NO. 100 133 AS 3 5 . 0 ^

NO. 200 Z H . 1 Z

PAN K6'3* BREAKDOWN

MOIST WEIGHT + TARE GMS. WASHED DRY WEIGHT + TARE GMS.

OVEN DRY WEIGHT + TARE W/.Q Q CMS. TARE CMS.

TARE cPP/. AS GMS. WASHED DP*Y WEIGHT GMS.

MOISTURE CONTENT o2fLJLC_% OVEN DRY WEIGHT (W^) £ ) °t , IS GMS.

COMMENTS:

B-22

WOODWARD — CLYDE CONSULTANTS

project name /)^ a/oat

tested bys.clftp*

sample no.

liquid limit

plasticity index

PROJECT NO.

JUA2lfS PLOTTED BY &JM9S REVIEWED BY A

DEPTH U.S.C.S.__=5>^5^L

D 10%'

30% d 60%'

v

v

WELL GRADED GRAVEL SAND

Cu>4

Cc>l<3 cu>6

Cc>l<3 SIEVE ANALYSIS

ClCAN I0VMK OWMWI | 9" l-l/l" 9/4" \/f « m

u a. stanoano acmra >0 90

HYOROMETER ANALYSIS TWC NC ADMAA

AKIN. I* Ml A AOMIN 29 HN THNMINN. 49

w i k) OJ

o 70 >

in

m m o in h TO

W a

o z

o c JO < m in

too

A.92 4 f A

COBBLES COAN9C GRAVEL

»54 I.IA .990 .29? 149 PIAMCTCN Of 9AWTICLC IN MIH.IMCTtW9

0?4 .09? ,i'« 8 8 8 s ?

00§ OOt

sand F f M C coaftsc medium FIMC clay (ftastici to silt («o*-ft«sticl

SIEVE ANALYSIS

PROJECT NAMETVc ^r/ PROJECT NO fOl-hj-X i-Aft*,d

SMffLE /VVL/yV DATE

DESCRIPTION- <5A AS**, ft*- S'rxi-SC. fitTD* PT TSClasj.T*, TESTED BY REDUCED BY CHECKED BY C, ^

COARSE SIEVE ANALYSIS

WT. AIR DRY SOIL RETT). #10 GMS. WT. AIR DRY SOIL PASSING #10

WT. OVEN DRY SOIL RETD. #10 GMS. HYGROSCOPIC WATER CONTENT GMS.

WT. OVEN DRY SOIL RETD. ON ^ WT. OVEN DRY SOIL PASSING #10_

#10 AFTER WASHING ^ . TOTAL WT. DRY SOIL PASSING #10

TOTAL WEIGHT OF DRY SOIL USED IN TEST GMS. (W )

%

GMS.

GMS.

SIEVE SIZE CUMULATIVE WT. RETAINED ON SIEVE % PASSING 2"

IV

1"

3/4"

1/2"

3/8"

FINE SIEVE ANALYSIS

SAMPLE USED IN TEST GMS. WT. OF OVEN DRY SAMPLE GMS.(W ) s

NO. 4 m.t? HYDROMETER MATERIAL-MULTIPLY BY * PASSING #10 SIEVE

NO. 10 <9,w elci,0/ HYDROMETER MATERIAL-MULTIPLY BY * PASSING #10 SIEVE

NO. 16 2 - 0 2 99.20 NO. 30 9 * 3 * NO. 50

NO. 100 / 5/, 7c NO. 200 / vs.tfv PAN ? BREAKDOWN

MOIST WEIGHT + TARE

OVEN DRY WEIGHT + TARE S//, / TARE J* v MOISTURE CONTENT %

GMS. WASHED DRY WEIGHT + TARE

GMS. TARE

GMS. WASHED DP'Y WEIGHT

GMS.

_GMS.

GMS.

OVEN DRY WEIGHT(W ) S

COMMENTS: B-24

PROJECT NAME A/MT

TESTED j2JA2lf£ PLOTTED BY s5l£3p0i5L___j*L£2Z£JREVIEWED BY — DEPTH _ u.S.C.S

PROJECT NO.

SAMPLE NO. WW VW- */

LIQUID LIMIT

PLASTICITY INDEX

D 10%"

530%=

D 60%"

V V

WELL GRADED GRAVEL SAND C >4 u Cc>l<3

Cu>6 C > 1 < 3 c

r r«r SIEVE ANALYSIS

at»» sou*** owmn | • j* i-i/j" j/«" */r 4 • io II. t. 9TANMN0 9CRC9

It 30 90

HYDROMETER ANALYSIS TN« KIOMM

t«IN. It MM. #0 MM. THWItlNN.

4 f t o*" *• «1 « - o *> o f »*»o o| o

* 3t l it 9to rtr ut o?4 ° osr QIAIHTtW or MNTICLC IN MILUMCTCNS

SS g o o 3 o o n f l f l f l B o q o

oot oot oo>

clay ipt-mtici to silt (wo*-tt»jticl

SIEVE ANALYSIS

PROJECT NAME A/a* re SAMPLE VO.QllJ V- /

DESCRIPTION T/9" £*/?*) TESTED BY

/, '/• PROJECT NO>e>l~bCX 1

DATE

P*iff* REDUCED BY >51 #OJ?/XS CHECKED BY C. I / 7^ |

WT. AIR DRY SOIL RETD. #10

MT. OVEN DRY SOIL RETD. #10

WT. OVEN DRY SOIL RETD. ON

#10 AFTER WASHING

COARSE SIEVE ANALYSIS

GMS. WT. AIR DRY SOIL PASSING #10

.GMS. HYGROSCOPIC WATER CONTENT

WT. OVEN DRY SOIL PASSING #10

GMS. TOTAL WT. DRY SOIL PASSING #10_

TOTAL WEIGHT OF DRY SOIL USED IN TEST GMS. (W )

GMS.

GMS.

GMS.

SIEVE SIZE CUMULATIVE WT. RETAINED ON SIEVE % PASSING

2"

iy

i"

3/4"

1/2"

3/8"

FINE SIEVE ANALYSIS

WT. OF AIR DRY SAMPLE USED IN TEST GMS. WT. OF OVEN DRY SAMPLE GMS.(W ) s

NO. 4 HYDROMETER MATERIAL-MULTIPLY BY % PASSING #10 SIEVE

NO. 10 loo. 0 HYDROMETER MATERIAL-MULTIPLY BY % PASSING #10 SIEVE

NO. 16 £.31 96,43 NO. 30 0 %~3?> NO. 50 2 2 . H I NO. 100 3o/> ?o U. 94 NO. 200 3/7 1.S2 PAN BREAKDOWN

MOIST WEIGHT + TARE /£{. > GMS.

OVEN DRY WEIGHT + TARE GMS.

TARE 232 *3- GMS.

MOISTURE CONTENT /<& . % 1 %

WASHED DRY WEIGHT + TARE _GMS.

TARE JSMS.

WASHED DRY WEIGHT GMS.

OVEN DRY WEIGHT(W) 3V*. t3 GMS. 5

COMMENTS: B-2b

WOODWARD - CLYDE CONSULTANTS

PROJECT NAME

TESTED BY."

SAMPLE NO. WW 1p- Li .Lf

LIQUID LIMIT

PROJECT NO.

PLOTTED BY £J&}£fS REVIEWED BY DEPTH U.S.C.S., - >5/?-

D

PLASTICITY INDEX 10%

}30%=

60%

V WELL GRADED GRAVEL SAND C >4 u Cc> 1<3

C„>6 C » 1 <3 c

w ro ^4

r r r SIEVE ANALYSIS

etc a* SOUANC owmn | j" !-•/»" j/«" iff a

u a. STANOARO acmca so

HYDROMETER ANALYSIS twe at a dm m

tSHA.

0> TO >

w M rn

o > A

tn -i TO

00

o z o cr < m tn

too SSSj? JTS 2

•w irr t*c s« i C M •• .sso f»» 14# OIAMCTCN or PARTIClt IN MILLIMCTCNS

oos oos oot

ronm rt gravel sand clay (ptasnci to silt (non-rtajticl

• • SIEVE ANALYSIS

PROJECT NAME /)W PROJECT NO. ,/0/- / - fit)/&//v SAMPLE KO.rf/U) ~t> - V- </ A " DATE 9 - S> <"

DESCRIPTION J>f i —C Z7— •

TESTED BY ^5 REDUCED BY .S ; CHECKED BY ^, iJt,

COARSE SIEVE ANALYSIS

WT. AIR DRY SOIL RETD. #10__ GMS. WT. AIR DRY SOIL PASSING #10

WT. OVEN DRY SOIL RETD. #10_ GMS. HYGROSCOPIC WATER CONTENT

WT. OVEN DRY SOIL RETD. ON WT. OVEN DRY SOIL PASSING #10_

#10 AFTER WASHING QMS. TOTAL WT. DRY SOIL PASSING #10

TOTAL WEIGHT OF DRY SOIL USED IN TEST GMS. (W )

GMS.

_%

GMS.

GMS.

SIEVE SIZE CUMULATIVE WT. RETAINED ON SIEVE % PASSING

2"

iy

i"

3/4"

1/2"

3/8"

FINE SIEVE ANALYSIS

WT. OF AIR DRY SAMPLE USED IN TEST GMS. WT. OF OVEN DRY SAMPLE GMS. (W ) s

NO. 4 /bCK D HYDROMETER MATERIAL-MULTIPLY BY * PASSING #10 SIEVE

NO. 10 4. fit 9911 HYDROMETER MATERIAL-MULTIPLY BY * PASSING #10 SIEVE

NO. 16 49.9,-7 NO. 30 /. & 3 -

NO. 50 <22.93

NO. 100

NO. 200 3. oZ~ PAN 3 9 BREAKDOWN

MOIST WEIGHT + TARE ?S> GMS.

OVEN DRY WEIGHT + TARE i/ - </£ GMS.

TARE GMS.

MOISTURE CONTENT Q./,

COMMENTS:

WASHED DRY WEIGHT + TARE GMS.

TARE GMS.

WASHED DP'Y WEIGHT GMS.

OVEN DRY WEIGHT (W ) fl? GMS.

B-28

WOODWARD - CLYDE CONSULTANTS

f

PROJECT NAME PROJECT NO.

TESTED BYSXfyfiS tL£2lfS PLOTTED BY &J3t71fS REVIEWED BY SAMPLE NO. DEPTH II s r s

LIQUID LIMIT

PLASTICITY INDEX '10%"

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PROJECT NAME /y^r/ SAMPLE NO. mrt^ZL- 3- /

DESCRIPTION g/v r/>-•$/>*

• # PROJECT NO._ /Ot-Tt-X >

DATE c? & *? ' % S~

TESTED BY C. REDUCED BY £jC/)JS CHECKED BY TTTJ,

WT. AIR. DRY SOIL RETD. #10

WT. OVEN DRY SOIL RETD. #10

WT. OVEN DRY SOIL RETD. ON

#10 AFTER WASHING

COARSE SIEVE ANALYSIS

GMS. WT. AIR DRY SOIL PASSING #10_

GMS. HYGROSCOPIC WATER CONTENT

GMS. WT. OVEN DRY SOIL PASSING #10_

TOTAL WT. DRY SOIL PASSING #10

TOTAL WEIGHT OF DRY SOIL USED IN TEST GMS. (W ) ~ 6

GMS.

GMS.

GMS.

SIEVE SIZE CUMULATIVE WT. RETAINED ON SIEVE % PASSING

2"

1*"

1"

3/4"

1/2"

3/8"

FINE SIEVE ANALYSIS

WT. OF AIR DRY SAMPLE USED IN TEST GMS. WT. OF OVEN DRY SAMPLE QMS. (W ) s

NO. 4 HYDROMETER MATERIAL-MULTIPLY BY % PASSING #10 SIEVE

NO. 10 / £>&. o

HYDROMETER MATERIAL-MULTIPLY BY % PASSING #10 SIEVE

NO. 16

NO. 30 9 9 . Z 1

NO. 50 tO-tiSL' 1 S - 9 3

NO. 100 2 - 0 3 . 0 &

NO. 200 £•

PAN £ 5'/. C */- BREAKDOWN

MOIST WEIGHT • TARE

OVEN DRY WEIGHT + TARE 1/77*9%

TARE 2//, gfl

MOISTURE CONTENT 3 O . I3_s

GMS. WASHED DRY WEIGHT + TARE

GMS'. TARE

GMS. WASHED DP'Y WEIGHT

GMS,

OVEN DRY WEIGHT(W ) S

GMS,

GMS.

GMS

COMMENTS: B-30

WOODWARD — CLYDE CONSULTANTS

I

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LIQUID LIMIT D,

PROJECT NO. /O/~7?j:I -v >W IJ&UJtS. REVIEWED BY CAJ SO . AAC.IMS

u.s.c.s

'10%

PLASTICITY INDEX D 30%" d 60%"

V

C c =

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COARSE SIEVE ANALYSIS

HT. AIR DRY SOIL RETO. .10 GHS. HT. AIR DRY SOIL PASSING .10

HT. OVEN DRY SOIL RETD. .10 CMS. HYGROSCOPIC HATER CONTENT 7

HT. OVEN DRY SOIL RETD. ON OVEN DRY SOIL PASSING TTc CMS

.10 AFTER HASHING __GHS. TOTAL HT. DRY SOIL PASSING .10

TOTAL HEIGHT OF DRY SOIL USED IN TEST CMS. (B )

SIEVE SIZE CUMULATIVE WT. RETAINED ON SIEVE % PASSING 2"

IV

1"

3/4"

1/2"

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FINE SIEVE ANALYSIS

HT. OP AIR DRY SAMPLE USED IN TEST CMS. HT. OF OVEN DRY SAMPLE GMS. (H ) s

NO. 4 HYDROMETER MATERIAL-MULTIPLY BY * PASSING #10 SIEVE NO. 10

HYDROMETER MATERIAL-MULTIPLY BY * PASSING #10 SIEVE

NO. 16 /Pi. o NO. 30 l.lo 91.4k NO. 50 C7.S&- >Ip6> NO. 100 Z5(,. 4a / £. NO. 200 £99-e 6 S.ilu PAN P-99./3 BREAKDOWN

MOIST WEIGHT + TARE S?£,</A CMS. WASHED DRY WEIGHT + TARE GMS.

OVEN DRY WEIGHT + TARE . GMS. TARE cms.

TARE 3-fiq.Htf GMS. WASHED DRY WEIGHT GMS.

MOISTURE CONTENT /£?%•'£ % OVEN DRY WEIGHT (W^) GMS.

COMMENTS: b—-32

WOODWARD - CLYDE CONSULTANTS

0112s—12

APPENDIX B.3

FALLING HEAD TEST - SAMPLE HYDRAULIC CONDUCTIVITY CALCULATIONS

\

B-33

0112s—6

From Hvorslev (1951) we can write

K = . In 21 (E-l)

8.0LT d

where:

K = hydraulic conductivity (cm/sec)

d = monitoring well I.D. (cm)

L = screened length (cm)

T = basic time lag (sec).

Relationship E-l is valid as long as:

d

For the wells at the Del Norte site

L = 25 ft

d = 0.17 ft

therefore:

L = 150 » 4 d

Restriction E-2 is thus met for the Del Norte wells. See Figure E-l

for a sample calculation.

l > 4. (E-2)

B-34

0112s—6

In order to use the Hvorslev analysis, the strip chart data must be

reduced to the appropriate values. Reducing the strip chart data from

MW-3 run number 1, we obtain the following tabulated data:

Table E-l. FALLING HEAD TEST DATA AT WELL MW-3 FOR RUN NUMBER 1

Time AH* (sec) (ft) AH/H0**

6 1.85 0.76 12 1.30 0.53 18 0.875 0.36 24 0.60 0.25 30 0.45 0.18 36 0.35 0.14 42 0.25 0.10 48 0.20 0.08 54 0.20 0.08 60 0.15 0.06 78 0.10 0.04

* AH represents the change in the groundwater elevation in the piezometer.

** H0 is the maximum deflection in the groundwater elevation at time = 0.

Graphing this data on semi-log paper, we obtain Figure E-l.

The basic time lag 1n equation E-l is derived by determining the time in seconds that corresponds to a AH/H0 of 0.37 (Hvorslev, 1951).

Substituting the numerical values Into equation E-l yields the following relationship:

K - (0-TQ2 In 2(25)

8(25)(18.05) 0.17

K = 4.5 x 10"5 ft/sec

B-35

Project No. PLOT OF FALLING HEAD TEST DATA FOR WELL MW-6, RUN NUMBER TWO

FIG. E-l

Woodward-Ctyde Consultants PLOT OF FALLING HEAD TEST DATA FOR WELL MW-6, RUN NUMBER TWO

FIG. E-l

B-36

0112s—13

appendix b.4

calculation of hydraulic conductivity from grain size distribution data

B-37

0112s—8

Sample number: MW2-3-1 Depth below grade of sample: 20'-19'8u

United Soil Classification System (USCS): SP-SM

Table F-l. GRAIN SIZE DISTRIBUTION FOR SAMPLE MW2-3-1

y Particle Percent Diameter 0 Retained (mm) Value

5 0.297 1.75 16 0.250 2.00 50 0.190 2.40 84 0.120 3.06 95 0.074 3.75

In order to obtain the hydraulic conductivity (K), the standard deviation (sd) of the grain size distribution needs to be calculated. From Masch and Denny (1966), we obtain the following relationship:

. 084 - 010 ^ 095 - 05 sd = + 4.0 6.6

Substituting the values from Table F-l, we obtain:

3.06 - 2.00 3.75 - 1.75 „

4 6.6

This value corresponds with a well-sorted material where the range in the 0 is from 0 for a well-sorted material to 4 for a poorly sorted material.

Using the value for the standard deviation and the 50 percent retained grain size, we can estimate the hydraulics conductivity from Figure F-l as approximately 150 gallons per day per square foot (gpd/ft2). Making the necessary unit conversions, K can be expressed as 2.3 x 10-4 feet per second (ft/sec).

B-38

MDjo DIAMETER ($)

>

Proiect No.

101RI1 Del Norte County

Site Investigation Technical Memo CURVES FOR PREDICTIVE TECHNIQUES Figure F-1

Woodward-Clyde Consultants CURVES FOR PREDICTIVE TECHNIQUES Figure F-1

B-39

Appendix C

Toxicity Assessment of principal Contaminents at Del Norte Site

APPENDIX C

TOXICITY ASSESSMENT OF PRINCIPAL CONTAMINANTS AT DEL NORTE SITE

This toxicity assessment focuses on the nine principal

contaminants detected in groundwater in the vicinity of the

Del Norte site. The toxic effects of these compounds and appli­

cable environmental criteria are discussed in the following

sections. This is followed by a summary of the physical and

chemical properties of these contaminants.

The environmental criteria presented in this section include

recently proposed Maximum Contaminant Levels (MCLs), Health

Advisories, Interim Primary Drinking Water Regulation MCLs,

and Carcinogen Assessment Group (CAG) lifetime incremental

cancer risks. MCLs are intended to protect public health from

contaminants in drinking water that may present an imminent

and substantial hazard to exposed individuals. These criteria

are designed to protect a 70 kg adult ingesting 2 liters of

water per day for a 70-year lifetime. Final MCLs become part

of the Revised Primary Drinking Water Regulations under the

Safe Drinking Water Act. Health Effects Advisories (HEAs)

are developed by the USEPA Office of Drinking Water for unreg­

ulated contaminants found in drinking water supplies. HEAs

suggest levels of contaminants at which adverse health effects

would not be anticipated. These criteria are calculated to

protect a 10 kg child ingesting 1 liter of water per day, and

are provided for one-day, ten-day, and longer-term exposure

periods when adequate background data are available. In devel­

c-i

oping lifetime incremental cancer risks, USEPA's CAG uses a

multi-stage model among others to extrapolate potential excess

cancer risks expected at environmental concentrations from

results in high dose animal studies. The model estimates risk

to a 70 kg adult ingesting 2 liters of water per day for a

70-year lifetime. Federal regulations for environmental con-

—4 -6 taminants have generally fallen in the 10 to 10 lifetime

risk range.

A. Arsenic

Health Effects

Arsenic has been implicated in the production of skin

cancer in humans. There is also extensive evidence that inha­

lation of arsenic compounds causes lung cancer in workers.

Arsenic compounds cause chromosome damage in animals, and humans

exposed to arsenic compounds have been reported to have an

elevated incidence of chromosome aberrations. Arsenic compounds

have been reported to be teratogenic, fetotoxic, and embryotoxic

in several animal species, and an increased incidence of multiple

malformations among children born to women occupationally exposed

to arsenic has been reported. Arsenic compounds also cause

noncancerous, possibly precancerous, skin changes in exposed

individuals. Several cases of progressive polyneuropathy invol­

ving motor and sensory nerves and particularly affecting the

extremities and myelinated long-axon neurons have been reported

in individuals occupationally exposed to inorganic arsenic.

Polyneuropathies have also been reported after the ingestion

of arsenic-contaminated foods.

Toxicity to Wildlife and Domestic Animals

Various inorganic forms of arsenic appear to have similar

levels of toxicity; they all seem to be much more toxic than

organic forms. Acute toxicity to adult freshwater animals

occurs at levels of arsenic trioxide as low as 812 g/liter

and at levels as low as 40 ng/liter in early life stages of

aquatic organisms. Acute toxicity to saltwater fish occurs

at levels around 15 rog/liter, while some invertebrates are

affected at much lower levels (508 ng/liter). Arsenic toxicity

does not appear to increase greatly with chronic exposure,

and it does not seem that arsenic is bioconcentrated to a great

degree.

Arsenic poisoning is a rare but not uncommon toxic syndrome

among domestic animals. Arsenic causes hyperemia and edema

of the gastrointestinal tract, hemorrhage of the cardiac serosal

surfaces and peritoneum, and pulmonary congestion and edema;

and it may cause liver necrosis. Information on arsenic toxicity

to terrestrial wildlife was not reported in the literature

reviewed.

Current Criteria

The USEPA Ambient Water Quality Criterion for protection

of human health is 2.2 ng/liter. This is an upper limit estimate

of the arsenic concentration associated with an incremental

lifetime cancer risk of 10~^, and is based on ingestion of

C-3

contaminated water and contaminated aquatic organisms. Excluding

consumption of aquatic organisms as a potential exposure pathway,

approximately 2.5 ng/liter of arsenic in drinking water would

be associated with a lifetime cancer risk of 10~6. The Interim'

Primary Drinking Water Regulations specify a Maximum Contaminant

Level (MCL) of 50 jig/liter for arsenic.

B. Chromium

Bealth Effects

The hexavalent form of chromium is of major toxicological

importance in higher organisms. A variety of chromate (Cr VI)

salts are carcinogenic in rats and an excess of lung cancer has

been observed among workers in the chromate-producing industry.

Cr VI compounds can cause DNA and chrorasome damage in animals

and humans and Cr (VI) trioxide is teratogenic in the hamster.

Inhalation of hexavalent chromium salts causes irritation and

inflammation of the nasal mucosa, and ulceration and perforation

of the nasal septum. Cr VI also produces kidney damage in

animals and humans. The liver is also sensitive to the toxic

effects of hexavalent Cr, but apparently less so than the kidneys

or respiratory system. Cr III is less toxic than Cr VI; its

main effect in humans is a form of contact dermatitis in sensi­

tive individuals.

Toxicity to Wildlife and Domestic Animals

Chromium is an essential nutrient and is accumulated in

a variety of aquatic and marine biota, especially benthic organ­

isms, to levels much higher than in ambient water. Levels

C-4

in biota, however, usually are lower than levels in the sedi­

ments. Passage of chromium through the food chain can be demon­

strated. The food chain appears to be a more efficient pathway

for chromium uptake than direct uptake from seawater.

Water hardness, temperature, dissolved oxygen, species,

and age of the test organism all modify the toxic effects of

chromium on aquatic life. Cr III appears to be more acutely

toxic to fish than Cr VI; the reverse is true in long term

chronic exposure studies.

None of the plants normally used as food or animal feed

are chromium accumulators. Chromium absorbed by plants tends

to remain primarily in the roots and is poorly translocated to

the leaves. There is little tendency for chromium to accumu­

late along food chains in the trivalent inorganic form. Organic

chromium compounds, about which little is known, can have signi­

ficantly different bi©accumulation tendencies. Little infor­

mation concerning the toxic effects of chromium on mammalian

wildlife and domestic animal species is available.

Current Criteria

The USEPA Ambient Water Quality Criteria for protection of

human health are 170 mg/liter for chromium III and 50 ng/liter

for chromium VI. These criteria are based on ingestion of

contaminated water and contaminated aquatic organisms. Excluding

consumption of aquatic organisms as a potential exposure pathway

would not change these values appreciably. The Interim Primary

C-5

Drinking Water Regulations specify a Maximum Contaminant Level

(MCL) of 50 jig/liter for total chromium.

C. 1,2-Dichloroethane

Health Effects

1,2-Dichloroethane (ethylene dichloride) is carcinogenic in

rats and mice, producing a variety of tumors. When administered

by gavage, it produced carcinomas of the forestomach and hemangio-

sarcomas of the circulatory system in male rats; adenocarcinomas

of the mammary gland in female rats; lung adenomas in male mice;

and lung adenomas, mammary adenocarcinomas, and endometrial

tumors in female mice. It is mutagenic in bacterial test systems.

Human exposure by inhalation to 1,2-dichloroethane has been

shown to cause headache, dizziness, nausea, vomiting, abdominal

pain, irritation of the mucous membranes, and liver and kidney

dysfunction. Dermatitis may be produced by skin contact.

In severe cases, leukocytosis (an excess of white blood cells)

may be diagnosed and internal hemorrhaging and pulmonary edema

leading to death may occur. Similar effects are produced in

experimental animals.

Toxicity to Wildlife and Domestic Animals

1,2-Dichloroethane is one of the least toxic of the chlo­

rinated ethanes to aquatic life. For both fresh- and saltwater

species, it is acutely toxic at concentrations greater than

118 rag/liter, while chronic toxicity has been observed at 20 mg/

liter. 1,2-Dichloroethane is not likely to bioconcentrate,

C-6

as its steady state bioconcentration factor was 2 and its elim­

ination half-life was less than 2 days in bluegill.

No information on the toxicity of 1,2-dichloroethane to

domestic animals or terrestrial wildlife was found in the liter­

ature reviewed.

Current Criteria

The USEPA Ambient Water Quality Criterion for protection of

human health is 0.94 jig/liter. This is an upper limit estimate

of the lr2-dichloroethane concentration associated with an

incremental lifetime cancer risk of 10~^r and is based on inges­

tion of contaminated water and contaminated aquatic organisms.

Excluding consumption of aquatic organisms as a potential expo­

sure pathway does not change this value appreciably. Based

on more recent calculations, USEPA estimated that approximately

0.5 ng/liter in drinking water would be associated with a 10~^

incremental lifetime cancer risk (49 Federal Register 114:24340).

USEPA recently proposed a Maximum Concentration Limit (MCL)

for chronic exposure to 1,2-dichloroethane in drinking water

of 5 jig/liter.

D. 1,1-Dichloroethylene

Health Effects

1,1-Dichloroethylene caused kidney tumors in males and

leukemia in one study on mice exposed by inhalation, gave equi­

vocal results in other inhalation studies, but gave negative

results in rats and mice following oral exposure and in hamsters

following inhalation exposure. VDC was mutagenic in several

C-7

bacterial assays, for genetic toxicity. 1,1-Dichloroethylene

did not appear to be teratogenic but did cause embryotoxicity

and fetotoxicity when administered to rats and rabbits by inha­

lation. Chronic exposure to oral doses of VDC as low as 5 mg/kg/day

caused liver changes in rats. Acute exposure to high doses

causes central nervous system depression, but neurotoxicity

has not been associated with low-level chronic exposure. The

oral LD5O value for the rat is 1r500 mg/kg and for the mouse

it is 200 mg/ kg .

Toxicity to Wildlife and Domestic Animals

1,1-Dichloroethylene was not very toxic to freshwater or

saltwater species, with acute LCJQ values generally being in

the range of 80 to 200 mg/liter. A chronic study in which no

adverse effects were observed indicated that the acute-chronic

ratio was less than 40; a 13 day study which produced an LC^Q

of 29 mg/liter indicated that the acute-chronic ratio is greater

than 4.

No reports of the toxicity of 1,1-dichloroethylene to

terrestrial wildlife or domestic animals were found in the

literature reviewed.

Current Criteria

The USEPA Ambient Water Quality Criterion for protection

of human health is 0.033 jig/liter. This is an upper limit

estimate of the 1,1-dichloroethylene concentration associated

with an incremental lifetime cancer risk of 10 **, and is based

on ingestion of contaminated water and contaminated aquatic

C-8

organisms. Excluding consumption of aquatic organisms as a

potential exposure pathway does not change this value appreciably.

Based on more recent calculations, USEPA estimated that approxi­

mately 0.24 |ig/liter in drinking water would be associated

with a 10~® incremental lifetime cancer risk (49 Federal Register

114:24340).

USEPA has also developed a Health Advisory of 70 jig/liter

for longer term exposure to 1,1-dichloroethylene. USEPA recently

proposed a Maximum Concentration Limit (MCL) for chronic exposure

to 1,1-dichloroethylene in drinking water of 7 ng/liter.

E. 2>4-Dichlorophenoxyacetic Acid

Health Effects

2,4-Dichlorophenoxyacetic acid has been assayed for car­

cinogenicity in rats, mice, and dogs. Statistically significant

increases in tumor initiation have not been observed in any study.

Increases in the number of lymphosarcomas, total sarcomas,

and carcinomas in rats, however, suggest that it may be carci­

nogenic. A tumor-promoting effect was observed in a skin-paint­

ing study in mice.

2,4-0 has damaged DNA and inhibited DNA repair in several

strains of bacteria and yeast. It caused chromosomal damage

and induced increased rates of sister chromatid exchange (SCE)

in cultured human lymphocytes. 2,4-D also induced SCE in Chinese

hamster ovary cells. The results of the Drosophila sex-linked

recessive lethal assay were weakly positive. 2,4-D failed

C-9

to induce mutation in the Ames assay. Considering all available

test data, 2,4-D is a weak mutagen.

When administered to pregnant rats, mice, and hamsters,

2,4-D produces a pattern of developmental abnormalities, includ­

ing skeletal anomalies and cleft palate. Fetotoxicity and

fetal death have also been reported. The minimum level causing

major developmental abnormalities in rats is approximately

100 mg/kg. No effect on reproduction was observed in a 3-gene-

ration rat study.

2,4-D apparently is not very acutely toxic to humans,

with the oral LD50 estimated to be approximately 400 mg/kg.

However, considerable uncertainty exists regarding what is

a minimal toxic dose; it may be as low as 80 mg/kg. Symptoms

of vomiting, fever, and profound muscle weakness are usually

reported after ingestion of 2,4-D. 2,4-D is irritating to

the eyes. Absorption through the skin reportedly produces

severe peripheral neuropathy, with stiffness of extremities,

possible motor paralysis, and parathesia.

The oral LD50 for 2,4-D in mice and rats is 375 mg/kg,

but the oral for dogs is 100 mg/kg. Esters of 2,4-D have

comparable toxicity. Cardiac arrhythmia has been cited as a

cause of death in several acute studies. Pathological changes

have also occurred in the gastrointestinal tract, liver, lungs,

and kidneys. The rabbit dermal LD50 is 1,400 mg/kg.

Contrary to suggestions that 2,3,7,8-tetrachlorodibenzo-p-

dioxin contamination has contributed to the toxicity of 2,4-D,

C-10

no actual TCDD contamination of 2,4-D has been reported, although

hexachlorodibenzo-p-dioxin and 2,7-dichlorodibenzo-p-dioxin

have been found. There is no experimental evidence that dioxins

are formed by photolysis of 2,4-D.

Toxicity to Wildlife and Domestic Animals

Studies on the effects of exposure to 2,4-D and other

phenoxy herbicides on algae indicate that many single-celled

plants are not very sensitive to these compounds. Concentrations

of 25 mg/liter 2f4-D administered for 10-12 days reduced the

growth rate of Scenedesmus, one of the more sensitive species,

by 42%. The growth of Nostol muscorum, a blue-green algae,

is inhibited at concentrations of 0.1 rog/liter. Various forms

of filamentous algae, i.e., Chara, Hydrodictyon, and Pitophora,

are controlled at concentrations above 10 mg/liter.

The 96-hour for Daphnia magna is 2 mg/liter. Concen­

trations of 2 mg/liter had no detectable effect on shell growth

in oysters.

2,4-D's toxicity to fish has been thoroughly studied.

The 24- and 48-hour LC5Q values for the bluegill were reported

to be 8 mg/liter for 2,4-D. Esters of 2,4-D are slightly more

toxic. Concentrations of 50 mg/liter had no observable effect

on tadpoles of the frog, Rana temporaria.

Animal poisonings have been reported and attributed to

herbicide formulations containing 2,4-D, but in most instances

a definite causal relationship has not been established. 2,4-D

does not bioaccumulate in the adipose tissue.

c-ii

Current Criteria

The Interim Primary Drinking Water Regulations specify

a Maximum Contaminant Level (MCL) of 100 \ig/liter for 2,4-dichlo-

rophenoxyacetic acid.

F. 1,2-Dichloropropane

Health Effects

1,2-Dichloropropane caused an increased incidence of liver-

combined adenomas and carcinomas in male and female mice and

caused a slight increase in mammary adenocarcinoma in female

rats. In an earlier study, 80 C3H mice were exposed to 1,850 mg/m

of 1,2-dichloropropane for 4 to 7 hours per day 37 times and

were then observed for the next 7 months; the 3 mice survived,

but all of these developed multiple hepatomas. 1,2-Dichloropro­

pane was found to be mutagenic using the Ames assay both with

and without metabolic activation. It also increased the fre­

quency of 8 azaguanine-resistant mutants in the Aspergillus

nidulans spot test. No information was available on the repro­

ductive or teratogenic effects of this compound.

High concentrations of 1,2-dichloropropane cause central

nervous system depression and narcosis in humans. Other human

symptoms include headache, vertigo, lacrimation, and irritation

of the mucous membranes. Studies indicate that exposure to v

high concentrations may affect the rate of growth in rats and

guinea pigs, and cause fatty degeneration and multilobular

or centrilobular necrosis of the liver. Histopathologic changes

were also observed in the kidneys, adrenals, and heart. 1,2-Di-

C-12

chloropropane is a mild skin irritant. It is moderately irri­

tating to the eye but does not cause permanent injury.

The oral LD50 for rats is 1,900 mg/kg; the oral LD^Q for

mice is 860 mg/kg. The dermal LD50 for rabbits is 8,750 mg/kg.

Toxicity to Wildlife and Domestic Animals

Only limited data are available on the effects of 1,2-

dichloropropane on wildlife and domestic animals. The 48-hour

EC5Q is 52 mg/liter in Daphnia magna. The 96-hour EC50 for

the bluegill is 300 mg/liter; for the fathead minnow, it is

139.3 mg/liter; and for the tidewater silverside it is 240 mg/liter.

In an embryo-larval test using the fathead minnow, chronic

effects developed at 8,100 (xg/liter.

Current Criteria

Based on a tentative recommendation by USEPA, the California

Department of Health Services has adopted a 10 jig/liter action

level for 1,2-dichloropropane in water consumed for 10 or more

days.

G. Methylene Chloride

Health Effects

Methylene chloride is currently being tested for carcinogen­

icity by the National Cancer Institute. Available information

regarding potential carcinogenic effects are inconclusive.

In a chronic inhalation study, male rats exhibited an increased

incidence of sarcomas in the ventral neck region. However,

the authors suggested that the relevance and toxicological

significance of this finding were uncertain in light of available

C-13

toxicity data. Methylene chloride is reported to be mutagenic

in bacterial test systems. It also has produced positive results

in the Fischer rat embryo cell transformation test. Bowever,

it has been suggested that the observed cell-transforming cap­

ability may have been due to impurities in the test material.

There is no conclusive evidence that methylene chloride can

produce teratogenic effects.

In humans, direct contact with methylene chloride produces

eye, respiratory passage^ and skin irritation. Mild poisonings

due to inhalation exposure produce somnolence, lassitude, numb­

ness and tingling of the limbs, anorexia, and lightheadedness,

followed by rapid and complete recovery. More severe poisonings

generally involve correspondingly greater disturbances of the

central and peripheral nervous systems. Methylene chloride

also has acute toxic effects on the heart, including the induc­

tion of arrhythmia. Fatalities reportedly due to methylene

chloride exposure have been attributed to cardiac injury and

heart failure. Methylene chloride is metabolized to carbon

monoxide in vivo, and levels of carboxyhemoglobin in the blood

are elevated after acute exposures. In experimental animals,

methylene chloride is reported to cause kidney and liver damage,

convulsions, and distal paresis. An oral value of 2,136 mg/kg,

and an inhalation LC5Q value of 88,000 mg/m3/30 min are reported

for the rat.

Toxicity to Wildlife and Domestic Animals

Very little information concerning the toxicity of methylene

C-14

chloride to domestic animals and wildlife exists. Acute values

for the freshwater species Daphnia magna, the fathead minnow,

and the bluegill are 224,000, 193,000, and 224,000 |ig/liter,

respectively. Acute values for the saltwater species, mysid

shrimp and sheepshead minnow, are 256,000 and 331,000 fig/liter,

respectively. No data concerning chronic toxicity are available.

The 96-hour EC^Q values for both freshwater and saltwater algae

are greater than the highest test concentration, 662,000 fig/liter.

Current Criteria

The USEPA Ambient Water Quality Criterion for protection

of human health is 0.19 fig/liter. This is an upper limit esti­

mate of the methylene chloride concentration associated with

an incremental lifetime cancer risk of 10~®, and is based on

ingestion of contaminated water and contaminated aquatic organisms.

Excluding consumption of aquatic organisms as a potential expo­

sure pathway does not change this value appreciably. A USEPA

longer term health effects advisory of 150 fig/liter has been

developed for methylene chloride.

H. Tetrachloroethylene

Tetrachloroethylene was found to produce liver cancer

in male and female mice when administered orally by gavage

(NCI 1977). Unpublished gavage studies in rats and mice per­

formed by the National Toxicology Program (NTP) showed hepato­

cellular carcinomas in mice and a slight, statistically insig­

nificant increase in a rare type of kidney tumor. NTP is also

conducting an inhalation carcinogenicity study. Elevated mutagenic

C-15

activity was found in Salmonella strains treated with tetrachloro-

ethylene. Delayed ossification of skull bones and sternebrae

were reported in offspring of pregnant mice exposed to 2,000 mg/m

of tetrachloroethylene for 7 hours/day on days 6-15 of gestation.

Increased fetal resorptions were observed after exposure of

pregnant rats to tetrachloroethylene. Renal toxicity and hepato-

toxicity have been noted following chronic inhalation exposure

of rats to tetrachloroethylene levels of 1,356 mg/m^. During

the first 2 weeks of a subchronic inhalation study, exposure

to concentrations of 1,622 ppm (10,867 mg/m"*) of tetrachloro­

ethylene produced signs of central nervous system depression,

and cholinergic stimulation was observed among rabbits, monkeys,

rats, and guinea pigs.

Toxicity to Wildlife and Domestic Animals

Tetrachloroethylene is the most toxic of the chloroethylenes

to aquatic organisms but is only moderately toxic relative

to other types of compounds. The limited acute toxicity data

indicated that the LC5Q value for saltwater and freshwater

species were similar, around 10,000 jig/liter; the trout was

the roost sensitive (LC5Q = 4,800 ng/liter) . Chronic values

were 840 and 450 |ig/ liter for freshwater and saltwater species

respectively, and an acute-chronic ratio of 19 was calculated.

No information on the toxicity of tetrachloroethylene

to terrestrial wildlife or domestic animals was found in the

literature reviewed.

C-16

Current Criteria

The USEPA Ambient Water Quality Criterion for human health

is 0.8 jig/liter, a concentration corresponding to an upper

limit excess cancer risk of 10~®. This criterion is based

on ingestion of contaminated water and contaminated aquatic

organisms. Excluding consumption of aquatic organisms as a

potential exposure pathway, USEPA estimated that lifetime inges­

tion of approximately 1.0 (xg/liter of. tetrachloroethylene in

drinking water would be associated with an incremental lifetime

cancer risk of 10~6 (49 Federal Register 114:24340). USEPA

has also developed a health advisory of 20 ng/liter for longer

term exposure to tetrachloroethylene, and recently proposed

a maximum contaminant level (MCL) for chronic exposure in drinking

water of 10 jig/liter.

I. 2,4,5-Trichlorophenoxyacetic Acid

Health Effects

Currently, there is no conclusive evidence that 2,4,5-T

is carcinogenic in humans or experimental animals. Data from

studies on experimental animals and in vitro suggest that 2,4,5-T

is not mutagenic but may damage chromosomes. Administration

of 2,4,5-T to pregnant experimental animals disrupts fetal

development, causing fetal loss, developmental retardation,

and malformations or anomalies. Other acute or chronic effects

of 2,4,5-T have not been adequately demonstrated. An oral

LD^Q level of 300 mg/kg is reported for the rat.

C-17

The toxic effects of purified 2,4,5-T in experimental

animals and humans have not been adequately studied, and other

toxic effects observed as a result of exposure to 2,4,5-T for­

mulations, including induction of microsomal mixed function

oxidase activity and chloracne, may actually be caused by 2,3,7,8-

tetrachlorodibenzo-p-dioxin (TCDD), a common contaminant of

these formulations.

Toxicity to Wildlife and Domestic Animals

Limited evidence suggests that 2,4,5-T may affect wildlife

or domestic animals indirectly by disrupting vegetation density

and composition in an area. Herbivores may be affected by

changes in the types and amounts of their potential food sources.

These changes may favor some species and be detrimental to

others. Other animals may lose sources of cover from predators

or sites for nest and den building.

There is virtually no specific information on the toxicity

of 2,4,5-T to wildlife or domestic animals available. While

2,4,5-T is thought to have relatively low toxicity for vertebrate

species, it has been reported that populations of invertebrates,

including beneficial insect species, have been adversely affected

at field concentrations. Invertebrates may be adversely affected

both directly because of the compound's toxicity and indirectly

because of the changes 2,4,5-T produces in vegetation growth

patterns. Although 2,4,5-T is not reported to have large,

direct toxic effects on livestock, there are reports of animal

C-18

deaths due to alterations in plant chemistry and palatability

after 2,4,5-T treatment.

Information on the effects of 2,4,5-T on aquatic species

is also limited. Among fish, the LD50 value perch is

55 mg/liter; for guppies, 8 mg/liter; and for rainbow trout,

1.3 mg/liter.

Current Criteria

The National Academy of Sciences has calculated a suggested

no adverse effect level for 2,4,5-trichlorophenoxyacetic acid

in drinking water of 700 ^g/liter. In deriving this value,

it was assumed that a 70 kg person would drink 2 liters of

water per day. It was further assumed that 20% of the total

allowable daily intake of 2,4,5-trichlorophenoxyacetic acid

would be ingested in drinking water, and the remaining 80%

would be obtained from other sources.

C-19

ARSENIC

Arsenic can be found in the environment in any of four valence states (-3, 0, +3, and +5) depending on the pH, Eh, and other factors. It can exist as either inorganic or organic compounds and often will change forms as it moves through en­vironmental media. The chemical and physical properties depend on the state of the metalloid. Only the properties of metallic arsenic have been listed; properties of other arsenic compounds are often quite different.

CAS Number: 7440-38-2

Chemical Formula: As

IUPAC Name: Arsenic

Chemical and Physical Properties

Atomic Weight: 74.91

Boiling Point: 613°C

Melting Point: 817°C

Specific Gravity: 5.72 at 20°C

Solubility in Water: Insoluble; some salts are soluble

C-20

CHROMIUM

Chromium exists in the stable trivalent (Cr III) and hexa-valent (Cr VI) oxidation states in most of its compounds. Cr III is the most common naturally occurring form; most Cr VI in the environment comes from industrial and domestic emissions.

CAS Number: 7440-47-3

Chemical Formula: Cr

IUPAC Name: Chromium

Chemical and Physical Properties (Metal)

Atomic Weight: 51.996

Boiling Point: 2672°C

Melting Point: 1857 + 20°C

Specific Gravity: 7.20 at 28°C

Solubility in Water: Insoluble; some compounds are soluble

Solubility in Organics: Soluble in dilute and

insoluble in HN03 and iqua regia (a mixture of concentrated HNO^ and HC1)

C-21

1,2-DICHLOFOETHANE

1,2-Dichloroethaine is sometimes referred to as ethylene dichloride or EDC. It is a volatile organic solvent, and vola­tilization and percolation into groundwater may be significant routes of transport. It has low solubility in water and may be a component in non-aqueous-phase-liquids in places where they occur. 1,2-Dichloroethane is carcinogenic and mutagenic and is a suspect human carcinogen. Its carcinogenic potency is relatively low (+1 on a scale of 0-7). The ambient water quality criterion (concentration corresponding to a risk level of 10 ) is 0.94 jig/liter. It has low toxicity to aquatic life.

CAS Number: 107-06-2

Chemical Formula: CI^CICI^CI

IUPAC Name: 1,2-Dichloroethane

Important Synonyms and Trade Names:

Chemical and Physical Properties

Molecular Weight:' 98.96

Boiling Point: 83-84°C

Melting Point: -35.4°C

Specific Gravity: 1.253 at 20°C

Solubility in Water: 8 g/liter

Solubility inorganics: Miscible with alcohol, chloroform, and ether

Log Octanol/Water Partition Coefficient: 1.48

Vapor Pressure: 61 mm Hg at 20°C

Flash Point: 15°C (closed cup)

Ethylene dichloride, glycol dichloride

C-2 2

1,1-DICHLORDETHYLENE

CAS Number: 75-35-4

Chemical Formula: CB2CC12

IUPAC Name: 1,1-Dichloroethene

Important Synonyms and Trade Names: Vinylidene chloride, VDC, 1,1-dichloroethene, 1,1-DCE

Chemical and Physical Properties

Atomic Weight: 96.94

Boiling Point: 37°C

Melting Point: -122.1°C

Specific Gravity: 1.218 at 20°C

Solubility in Water: 400 mg/liter at 20°C

Solubility inorganics: Sparingly soluble in alcohol, ether, acetone, benzene, and chloroform

Log Octanol/Water Partition Coefficient: 1.48

Vapor Pressure: 500 mm Bg at 20°C

Vapor Density: 3.25

C-23

2,4-DICHLORQPHENOXYACETIC ACID

CAS Number: 94-75-7

Chemical Formula: Cl2CgH3OCH2CX)OH

IUPAC Name: 2,4-Dichlorophenoxyacetic acid

Important Synonyms and Trade Names: Agrotectf Dicotox, Phenox, 2,4-D

Chemical and Physical Properties

Molecular Weight: 221.04

Boiling Point: 160°C at 0.4 mm Hg

Melting Point: 138°C

Solubility in Water: 620 mg/liter

Solubility in Organics: Soluble in organic solvents

Log Octanol/Water Partition Coefficient: 2.5 (calculated)

Vapor Pressure: <10~5 mm Bg at 25°C

Vapor Density: 7.63

pKa: 2.8

C-24

1,2-DICHLOROPROPANE

CAS Number: 78-87-5

Chemical Formula: CH2CICHCICH3

IUPAC Name: 1,2-Dichloropropane

Important Synonyms and Trade Names: Propylenechloride, propylene-dichloride

Chemical and Physical Properties

Molecular Weight: 112.99

Boiling Point: 96.8°C

Melting Point: -100°C

Specific Gravity: 1.16 at 20°C

Solubility in Water: 2,700 mg/liter at 20°C

Solubility in Organics: Miscible with organic solvents

Log Octanol/Water Partition Coefficient: 2.28

Vapor Pressure: 42 mm Hg at 20°C

Vapor Density: 3.9

Flash Point: 21°C (open cup)

C-25

METHYLENE CHLORIDE

CAS Number: 75-09-2

Chemical Formula: CH2CI2

IUPAC Name: Dichloromethane

Important Synonyms and Trade Names: Methylene dichloride, methane dichloride

Chemical and Physical Properties

Molecular Weight: 84.93

Boiling Point: 40°C

Melting Point: -95.1°C

Specific Gravity: 1.3266 at 20°C

Solubility in Water: 13,200-20,000 mg/liter at 25°C

Solubility in Organics: Miscible with alcohol and ether

Log Octanol/Water Partition Coefficient: 1.25

Vapor Pressure: 362.4 mm Hg at 20°C

Vapor Density: 2.93

C-26

TETRA CHLO RO E TH YL ENE

CAS Number: 127-18-4

Chemical Formula: C^Cl. 2 4

IUPAC Name: Tetrachloroethene

Important Synonyms and Trade Names: Perchloroethylene, PCE

Chemical and Physical Properties

Molecular Weight: 165.83

Boiling Point: 121°C

Melting Point: -22.7°C

Specific Gravity: 1.63

Solubility in Water: 150 to 200 mg/liter at 20°C

Solubility inorganics: Soluble in alcohol, ether, and benzene

Log Octanol/Water Partition Coefficient: 2.88

Vapor Pressure: 14 mm Hg at 20°C

C-27

2,4,5-TRICHLOROPHENOXYACETIC ACID

CAS Number: 93-76-5

Chemical Formula: Cl3CgH2OCH2CX>OH

IUPAC Name: 2,4,5-Trichlorophenoxyacetic acid

Important Synonyms and Trade Names: Brushtox, Ded-weed Brush Killer, 2,4,5-T, Weedar

Chemical and Physical Properties

Molecular Weight: 255.48

Melting Point: 153°C

Solubility in Water: 250 mg/liter

Solubility inorganics: Soluble in alcohol

Vapor Pressure: Less than 8.4 x 10~6 mm Hg at 25°C

Vapor Density: 8.83

pKa: 2.84

C-2 8

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