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POOR LEGIBILITY
ONE OR MORE PAGES IN THIS DOCUMENT ARE DIFFICULT TO READ DUE TO THE QUALITY OF THE ORIGINAL
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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%"
J30%=
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cu*
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cu>e
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cltm 90uarc owmw! SIEVE ANALYSIS
i U a STtMMKt MKS HYOROMETER ANALYSIS
time rerfhnm
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SIEVE ANALYSIS
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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PROJECT NAME
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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 =
WELL GRADED GRAVEL SAND Cu>4
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description X/*J 2 *9 -
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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"
3/8"
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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