PB96964503
PB96-964503
EPA/ROD/R09-96/145
June 1996
EPA Superfund
Record of Decision:
Sharpe Army Depot,
(Basewide O.U.)> Lathrop, CA
3/5/1996
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Contract No. DAAA15-88-D0003
Delivery Order 0002
FINAL
RECORD OF DECISION
BASEWIDE REMEDY FOR
DDRW • SHARPE SITE
ENVIRONMENTAL SCIENCE & ENGINEERING, INC.
P.O. Box 1703
Gainesville, FL 32602-1703
February 1996
Distribution limited to U.S. Government Agencies only for
protection of privileged information evaluating another command:
February 1996. Requests for this document must be referred to:
Commander, U.S. Army Environmental Center,
Aberdeen Proving Ground, MD 21010-5401; or Commander,
SHARPE Site, Lathrop, CA 95331.
U.S. ARMY ENVIRONMENTAL CENTER
Installation Restoration Division
Aberdeen Proving Ground, MD 21010-5401
Primed on Recycled Paper
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TABLE OF CONTENTS
DECLARATION FOR THE RECORD OF DECISION xii
1.0 SITE NAME, LOCATION, AND DESCRIPTION 1
2.0 SITE HISTORY AND ENFORCEMENT ACTTVITIES 1
3.0 HIGHLIGHTS OF COMMUNITY PARTICIPATION 7
4.0 SCOPE AND ROLE OF RESPONSE ACTION 7
5.0 SUMMARY OF SITE CHARACTERISTICS 9
5.1 TCE CONTAMINATION 9
5.2 LEAD- AND CHROMIUM-CONTAMINATED SOILS 11
5.2.1 S#3-BLDG. S-l 19 (SPRAY PAINT BOOTH) 18
5.2.2 S#26-OPEN DUMPING FROM
BLDGS. 170 TO 184 18
5.2.3 S#28-SOUTH BALLOON AREA (METAL
STRIPPING SLUDGE WORKED
THROUGH SOIL) 24
5.2.4 S#29-SOUTH BALLOON (BURN PITS) 45
5.2.5 LEACHABLE LEAD AND CHROMIUM AT
S#26 AND S#28 45
6.0 SUMMARY OF SITE RISKS 49
6.1 IDENTIFICATION OF COCs 50
6.1.1 CURRENT AND FUTURE
LAND USE AT SHARPE 50
6.1.2 COCs AND MEDIA OF CONCERN 52
6.2 EXPOSURE ASSESSMENT 52
6.2.1 POTENTIALLY EXPOSED POPULATIONS 52
6.2.1.1 Human Populations 52
6.2.1.2 Wildlife Populations 55
6.2.2 EXPOSURE PATHWAYS 55
6.2.3 EXPOSURE CONCENTRATIONS 56
6.2.4 ASSUMPTIONS USED TO CALCULATE
CHEMICAL EXPOSURE 56
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TABLE OF CONTENTS
(Continued, Page 2 of 5)
Page
6.3 TOXICITY ASSESSMENT 58
6.3,1 HUMAN TOXICITY ASSOCIATED
WITH COCs 58
6.3.2 ECOLOGICAL TOXICITY ASSOCIATED
WITH COCs 59
6.4 RISK CHARACTERIZATION 59
6.4.1 METHODS FOR HUMAN
RISK CHARACTERIZATION 59
6.4.2 METHODS FOR ECOLOGICAL RISK
CHARACTERIZATION 64
6.4.3 SUMMARY OF RISKS 65
7.0 DESCRIPTION OF ALTERNATIVES 69
7.1 LEAD- AND CHROMIUM-CONTAMINATED SOIL 69
7.1.1 ALTERNATIVE 1C-CONTAINMENT:
ASPHALT CAP 71
7.1.2 ALTERNATIVE 2A-TREATMENT:
PHYSICAL/CHEMICAL--FIXATION/
SOLIDIFICATION 72
7.1.3 ALTERNATIVE 2B: CHEMICAL
EXTRACTION/SOIL WASHING 74
7.1.4 ALTERNATIVE 4B-REMOVAL AND
DISPOSAL: OFFSITE LANDFILL 76
7.1.5 ALTERNATIVE 5A-NO ACTION:
LIMIT ACCESS/USE RESTRICTIONS 78
7.2 TCE-CONTAMINATED SOIL 78
7.2.1 ALTERNATIVE 2B-THERMAL
TREATMENT: ONPOST INCINERATION 79
7.2.2 ALTERNATIVE 2C-PHYSICAL
TREATMENT: ISV 80
7.2.3 ALTERNATIVE 3A--INNOVATTVE
TECHNOLOGIES: LOW-TEMPERATURE
THERMAL STRIPPING 82
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TABLE OF CONTENTS
(Continued, Page 3 of 5)
7.2.4 ALTERNATIVE 4A-REMOVAL AND
DISPOSAL: OFFSITE LANDFILL 84
7.2.5 ALTERNATIVE 5A-NO ACTION:
UMTTACCESS/USE RESTRICTIONS 85
8.0 SUMMARY OF COMPARATIVE ANALYSIS OF
REMEDIAL ALTERNATIVES 86
8.1 LEAD-AND CHROMIUM-CONTAMINATED SOILS 87
8.1.1 PROTECTION OF HUMAN HEALTH AND
THE ENVIRONMENT 87
8.1.2 COMPLIANCE WITH ARARs 91
8.1.3 LONG-TERM EFFECTIVENESS 91
8.1.4 REDUCTION OF TMV THROUGH
TREATMENT 92
8.1.5 SHORT-TERM EFFECTIVENESS 93
8.1.6 IMPLEMENTABIUTY 94
8.1.7 COSTS 94
8.1.8 STATE ACCEPTANCE 94
8.1.9 COMMUNITY ACCEPTANCE 95
8.2 TCE-CONTAMINATED SOILS 95
8.2.1 PROTECTION OF HUMAN HEALTH AND
THE ENVIRONMENT 95
8.2.2 COMPLIANCE WITH ARARs 96
8.2.3 LONG-TERM EFFECTIVENESS 96
8.2.4 REDUCTION OF MTV THROUGH
TREATMENT 96
8.2.5 SHORT-TERM EFFECTIVENESS 97
8.2.6 IMPLEMENTABIUTY 97
8.2.7 COSTS 98
8.2.8 STATE ACCEPTANCE 98
8.2.9 COMMUNITY ACCEPTANCE 98
9.0 THE SELECTED REMEDIES 98
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TABLE OF CONTENTS
(Continued, Page 4 of 5)
Page
9.1 LEAD- AND CHROMIUM-CONTAMINATED SOILS 99
9.1.1 FURTHER CHARACTERIZATION 100
9.1.2 CLEANUP STANDARDS 100
9.1.3 EXCAVATION AND REMOVAL ACTIVITIES 101
9.1.4 EVALUATION OF RESIDUAL
CONCENTRATIONS AND EVALUATION
OF GROUNDWATER 102
9.2 VOC-CONTAMINATED SOILS 103
9.2.1 ISV OPERATION 104
9.2.2 VOC CONTAMINATED SOIL
CLEANUP STANDARD 105
9.2.3 TECHNICAL AND ECONOMIC FEASIBILITY 106
9.2.4 FURTHER CHARACTERIZATION 107
9.3 NO FURTHER ACTION SITES 108
10.0 STATUTORY DETERMINATIONS 108
10.1 LEAD- AND CHROMIUM-CONTAMINATION SOILS 116
10.1.1 PROTECTIVE OF HUMAN HEALTH
AND ENVIRONMENT 116
10.1.2 COMPLY WITH ARARs 117
10.1.3 COST EFFECTIVE 117
10.1.4 UTILIZATION OF PERMANENT SOLUTIONS
AND ALTERNATIVE TREATMENT
(OR RESOURCE RECOVERY)
TECHNOLOGIES TO THE MAXIMUM
EXTENT PRACTICABLE 119
10.1.5 PREFERENCE FOR TREATMENT AS A
PRINCIPAL ELEMENT 119
10.2 TCE-CONTAMINATION SOILS 120
10.2.1 PROTECTIVE OF HUMAN HEALTH
AND ENVIRONMENT 120
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TABLE OF CONTENTS
(Continued, Page 5 of 5)
ion Page
10.2.2 ARARs 120
10.2.3 COST EFFECTIVE 121
10.2.4 UTILIZATION OF PERMANENT SOLUTIONS
AND ALTERNATIVE TREATMENT
(OR RESOURCE RECOVERY)
TECHNOLOGIES TO THE MAXIMUM
EXTENT PRACTICABLE 121
10.2.5 PREFERENCE FOR TREATMENT AS A
PRINCIPAL ELEMENT 123
11.0 REFERENCES 123
RESPONSIVENESS SUMMARY 125
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LIST OF TABLES
Table Page
2-1 USTs Closed or in Process of Being Closed 5
5-1 Lead and Chromium in North Balloon Area Groundwater 25
5-2 Trench and Burn Pit Boring Soil Samples
Collected in the South Balloon Area 38
5-3 Surficial Soil Samples Collected in the South Balloon
Area at SHARPE 42
5-4 Water Quality Assessment for Lead 47
5-5 Water Quality Assessment for Chromium 48
6-1 Summary of COCs hi Soil and Air for the North Balloon Area,
South Balloon Area, and Central Area of SHARPE 53
6-2 Summary of Human Exposure Pathways to COCs hi Soil
and Air for the North Balloon Area South Balloon, Area,
and Central Area of SHARPE 57
6-3 Summary of Toxicity Dose-Response Information Used in the
Human Risk Characterization 60
6-4 Compound-Specific Ecotoxicity Benchmarks for
Terrestrial Organisms 62
6-5 Summary of Final COCs and Human and Ecological Exposure
Pathways Posing Risk Exceedances at SHARPE 66
6-6 Summary of Health Risks Associated with Soil Exposure
at SHARPE 67
6-7 Summary of Hazard Indices Associated with Soil
Exposure at SHARPE 68
6-8 COCs and PRGs to be Evaluated in the ROD for SHARPE
Soils (mg/kg) 70
8-1 Summary of Detailed Analysis of Remaining Alternatives
for Lead-, Chromium-, and TCE-Contaminated Soils 88
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LIST OF TABLES
(Continued, Page 2 of 2)
Table Page
9-1 No Further Action Sites 109
10-1 ARARs for Lead-and Chromium-Contaminated Soils 118
10-2 ARARs for TCE-Contaminated Soils 122
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LIST OF FIGURES
Figure
1-1
2-1
5-1
5-2
5-3
5-4
5-5
5-6
5-7
5-8
5-9
5-10
5-11
5-12
5-13
5-14
5-15
Site Map
Proposed Actions at SHARPE
VOC Contamination Groundwater Plumes
Soil Gas Sampling Locations, Plume 1 Area
Soil Gas Sampling Locations, Plumes 4 and 5 Area
Soil Gas Sampling Locations, Plume 6 Area
Soil Gas Sampling Locations, Plumes 7 and 8 Area
Soil Gas Sampling Locations, Plume 2 Area
Soil Gas Sampling Locations, Plume 3 Area
SWMUs in North Balloon Vicinity
Isoconcentration Map of Lead in Surface Soils at
Former Building S-l 19
Lead Concentrations in Soil Found using XRF in the
North Balloon Area, November 1992
Chromium Concentrations in Soil Found using XRF in
the North Balloon Area, November 1992
Soil Boring Locations, South Location
Soil Sample Locations, South Balloon Area,
Chromium 0-2 ft Surficial
Soil Sample Locations, South Balloon Area,
Chromium 0-5 ft Interval
Soil Sample Locations, South Balloon Area,
Chromium, 5-10 ft Interval
Page
2
6
10
12
13
14
15
16
17
19
20
22
23
27
29
30
31
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LIST OF FIGURES
(Continued, Page 2 of 2)
Figure Page
5-16 Soil Sample Locations, South Balloon Area,
Chromium, 10-15 ft Interval 32
5-17 Soil Sample Locations, South Balloon Area,
Lead, 0-2 ft Surficial 34
5-18 Soil Sample Locations, South Balloon Area,
Lead, 0-5 ft Interval 35
5-19 Soil Sample Locations, South Balloon Area,
Lead, 5-10 ft Interval 36
5-20 Soil Sample Locations, South Balloon Area,
Lead, 10-15 ft Interval 37
5-21 Potential Soil Remediation Locations,
South Balloon Area, 50-ft Radius 46
6-1 Exposure Assessment Study Areas and Zones 51
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LIST OF ACRONYMS AND ABBREVIATIONS
AHA Administration and Housing Area
BNA Base-neutral/acid-extractable
CERCLA Comprehensive Environmental Response, Compensation, and
Liability Act
COC chemicals of concern
CRL cancer risk level
yd3 cubic yard
CVRWQCB Central Valley Regional Water Quality Control Board
12DCE 1,2-dichloroethene
DDRW Defense Distribution Region West
DOD Department of Defense
DTSC Department of Toxic Substances Control
EPA U.S. Environmental Protection Agency
freon trichlorofluoromethane
FS feasibility study
ft foot
ft-bls feet below land surface
ft-msl feet above mean sea level
GPR Ground-penetrating radar
HI hazard index
ISV in-situ volatilization
IWTP industrial wastewater treatment plant
MCL maximum contaminant level
NCP National Oil and Hazardous Substances Pollution Contingency
Plan
NFA no further action
NPDES National Pollutant Discharge Elimination System
mg/kg milligrams per kilogram
mg/L milligrams per liter
OU1 operable unit 1
PAHs polynuclear aromatic hydrocarbons
PID photoionization detector
ppm parts per million
PVC polyvinyl chloride
QA quality assurance
RA Risk Assessment
RAGS Risk Assessment Guidance for Superfund
RI Remedial Investigation
ROD Record of Decision
SARA Superfund Amendments and Reauthorization Act of 1986
SHARPE Sharpe Site
SJCPD San Joaquin County Department of Planning and Building 2
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LIST OF ACRONYMS AND ABBREVIATIONS
(Continued, Page 2 of 2)
SSJIDC
SVE
SWMU
TBC
TCE
TCLP
TMV
TSDF
USATHAMA
USFWS
USTs
VES
VOAs
VOCs
WDC
XRF
yd3
South San Joaquin Irrigation District Canal
soil vapor extraction
solid waste management unit
to be considered
trichloroethylene
toxicity characteristic leaching procedure
toxicity, mobility, or volume
treatment, storage, or disposal facility
U.S. Army Toxic and Hazardous Materials Agency
U.S. Fish and Wildlife Service
underground storage tanks
vapor extraction system
volatile organic analytes
volatile organic compounds
Western Distribution Center
X-ray fluorescence
cubic yard
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DECLARATION FOR THE RECORD OF DECISION (ROD)
SITE NAME AND LOCATION
Defense Distribution Region West-Sharpe Site
Lathrop, California
STATEMENT OF BASIS AND PURPOSE
This decision document presents the selected remedial action for Defense Distribution
Region West (DDRW)-Shaipe Site (SHARPE), in Lathrop, California, developed in
accordance with Comprehensive Environmental Response, Compensation, and
Liability Act (CERCLA), as amended by Superfund Amendments and Reauthorization
Act (SARA) to the extent practicable, the National Oil and Hazardous Substances
Pollution Contingency Plan (NCP), and Chapter 6.8 of the California Health and
Safety Code. Further, these actions are also being taken in response to the California
Water Code. This decision is based on the administrative record for this site.
The U.S. Environmental Protection Agency (EPA) and the State of California concur
on the selected remedies.
ASSESSMENT OF THE SITE
Actual or threatened releases of hazardous substances from this site, if not addressed
by implementing the response actions selected hi this. Record of Decision (ROD), may
present an imminent and substantial endangerment to public health, welfare, or the
environment.
DESCRIPTION OF THE REMEDY
This Base-Wide ROD selects the remedy for the second operable unit (OU2) at
Sharpe. OU2 addresses the comprehensive cleanup of soil, including the removal and
offsite disposal of certain soils contaminated with lead and chromium; onsite treatment
via in-situ volatilization (ISV) using vacuum extraction of certain soils contaminated
with trichloroethylene (TCE); and no further action (NFA) for 111 Solid Waste
Management Units (SWMUs). OU2 is intended to be the final response action for
SHARPE. The first operable unit (OU1) addressed the contaminated groundwater; the
selected remedy is set forth in the OU1 ROD which was finalized in January 1993.
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The OU2 selected remedy for lead- and chromium-contaminated soil is excavation and
disposal offsite and includes:
1. Sampling to delineate soils contaminated with lead or chromium in excess
of cleanup standards;
2. Removal of existing pavement, concrete, and light brush at locations with
soils contaminated with lead and chromium at levels exceeding cleanup
standards;
3. Excavation of soils that exceed cleanup standards;
4. Analyze excavated soils to determine if any soils are hazardous by
characteristic;
5. If any portion of soils are determined to be hazardous by characteristic,
then transport soils to an appropriately permitted offsite treatment, storage,
or disposal facility (TSDF);
6. Transport non-hazardous soils to an appropriately permitted offsite landfill;
7. Complete confirmation sampling to ensure that soils with lead and
chromium concentrations greater than cleanup standards have been
removed;
8. Backfill excavations with clean fill so as to return the site to the existing
grade; and
9. Evaluation of residual concentrations in soils and potential impact to
groundwater.
The OU2 selected remedy for TCE-contaminated soil is ISV and includes:
1. Delineating areas suspected of being sources of groundwater contamination
using soil gas data;
2. Using ISV to induce airflow from the subsurface soils to a vapor extraction
point at locations determined to be impacting groundwater above the
current cleanup standards; and
3. Transmitting ISV offgases from the vapor extraction point to a system that
will treat air prior to discharging it into the atmosphere.
The OU2 selected remedy for the 111 SWMUs is NFA.
A dispute was invoked concerning the cleanup of VOCs in the vadose zone and
concerning the fate of residual metals. The Dispute Resolution Committee resolved
this dispute as reflected in Sections 9.2 et seq. and 9.1.4, respectively. The
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resolutions are negotiated solutions, based on site specific conditions and therefore not
generally applicable to other sites. Where language elsewhere in the ROD is not
consistent with these negotiated resolutions, the language in the above specified
Sections prevails.
STATUTORY DETERMINATIONS
The selected remedies are protective of human health and the environment, comply
with federal and state requirements that are legally applicable or relevant and
appropriate to the remedial action, and are cost effective. These remedies use
permanent solutions and satisfy the statutory preference for remedies that employ
treatment and reduce toxicity, mobility, or volume as a principal element.
A 5-year review, as required, will be conducted in accordance with CERCLA
Section 121(e).
M.W. Casey, Captain, S(5, USN Date
Commander, Defense Distribution Region West
Jfflie Anderson-Rubin, Director Date
/federal Facilities Cleanup Office
' United States Environmental Protection Agency
Region 9
Anthony J. Landis/P,^., fcbief, Northern California Operations Date
Office of Military "Facilities
Site Mitigation Program
Department of Toxic Substances Control
William Crooks, Executive Officer, Central Valley, RWQCB Date
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DECISION SUMMARY
1.0 SITE NAME, LOCATION, AND DESCRIPTION
SHARPE is located northeast of Lathrop, California, east of Interstate 5 and west of
California Highway 99, with Roth and Lathrop Roads paralleling and contiguous to
the north and south boundaries of the site, respectively. The South San Joaquin
Irrigation District Canal (SSJIDC) parallels the eastern boundary. Land around
SHARPE is used for a variety of purposes including residential, agricultural, and light
industry. A site map is presented as Fig. 1-1.
SHARPE lies on slightly sloping to flat land. Elevations generally vary between 16
and 23 feet above mean sea level (ft-msl). Most of the surface water runoff is routed
into drains leading to the stormwater sewer system and then into the SSJIDC at the
east side of the site. This canal discharges into French Camp Slough a few miles
north of SHARPE. French Camp Slough discharges into the San Joaquin River, which
flows into San Francisco Bay. No surface water runoff occurs on the west boundary
of SHARPE; surface water along this boundary drains into sumps 5- to 15-feet (ft)
deep located along the west fence line and is allowed to percolate.
No discernible evidence exists to indicate faulting or geologic structures influence
groundwater flow patterns. Groundwater flow along the western boundary of
SHARPE is generally northwestward.
2.0 SITE HISTORY AND ENFORCEMENT ACTIVITIES
SHARPE was established in 1941. Construction of the major facilities at SHARPE
began during World War II and continued into the post-war period. Additional
facilities were constructed during the Korean and Vietnam Conflicts. The Western
Distribution Center (WDC), constructed in 1988, represents the most recent
significant construction activity at SHARPE. For most of its existence, the installation
has had both supply and maintenance missions. The supply mission remains active
and includes storage, handling, preservation, packaging, and shipment of general
supplies and equipment. The maintenance mission at one time included repair and
reconditioning of both heavy equipment and aircraft. The heavy equipment mission
began in the late 1940s, and the aircraft mission was added in 1957. These missions
were discontinued in 1976. The major waste-generating activities from these
operations were paint stripping, metal finishing, and painting. Other activities
included engine overhauls, hydraulic and electric repairs, airframe and body work,
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THERN PACIFIC RR
RECORD OF DECISION
SHARPE SITE. LATHROP. CALIFORNIA
Figure 1-1
SITE MAP
U.S. Army
Environmental Center
Aberdeen Proving Ground, Maryland
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and component repair and reconditioning. Since 1976, the maintenance mission has
included only maintenance of installation facilities and vehicles used in performing the
supply mission.
Soil and groundwater contamination were first detected at SHARPE in 1982. In 1982,
the U.S. Army Environmental Center [USAEC, formerly the U.S. Army Toxic and
Hazardous Materials Agency (USATHAMA)] initiated a Remedial Investigation (RI).
Early RI work indicated groundwater, contamination with offpost migration of VOCs.
Base-neutral/acid-extractable (BNA) compounds and nitrates were also investigated
during the early phases of the RI and were found not to be chemicals of concern
(COCs). Additionally, arsenic, selenium, and bromacil have been detected
sporadically in groundwater samples. Available data indicate that the primary source
of VOC contamination is associated with past mission-related activities (e.g., vehicle
maintenance) at SHARPE.
As a result of early investigations conducted at SHARPE, an interim groundwater
extraction and treatment system (referred to as the South Balloon Area Groundwater
Treatment System) was put into operation in March 1987 to control migration of
contaminated groundwater in that portion of the site. A separate interim RI and
feasibility study (FS) was also prepared to identify and evaluate interim remedial
action alternatives in the North Balloon Area. As a result of this investigation, a
second interim groundwater pump-and-treat system was constructed in the North
Balloon Area. This system began operation in October 1990. The agencies reviewed
and informally approved the design and construction of the interim systems.
The RI was finalized in June 1991. Following this, USAEC prepared a Groundwater
FS to evaluate alternatives for remediating VOC-contaminated groundwater. This FS
was finalized in November 1991. The Proposed Plan for groundwater was released to
the public on Feb. 6, 1992, and the Public Meeting was held on Feb. 27, 1992.
The January 1993 ROD for groundwater was designated operable unit 1 (OU1) and
addressed VOCs, arsenic, selenium, bromacil, and nitrates in groundwater.
Construction of the third and last groundwater treatment plant, located in the Central
Area, was completed in May 1995, when it was put into operation. Groundwater
treatment in the South Balloon Area, North Balloon Area, and Central Area is being
conducted in accordance with the January 1993 ROD.
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Work on the Soils FS, which addressed TCE-contaminated soils, lead- and
chromium-contaminated soils, and NFA sites, was finalized in December 1994. The
Proposed Plan for OU2 was released to the public on February 22, 1995; the Public
Meeting was held on March 1, 1995.
Limited soil remediation has been conducted to date. ISV via vacuum extraction is
currently being conducted as part of a long-term pilot test in the South Balloon Area
and North Balloon Area. Additionally, pesticide-contaminated (DDT and chlordane)
soils from the North Balloon Area have been excavated and disposed of in an appro-
priately licensed offsite landfill. That action, documented in a Removal Action Memo-
randum finalized October 1994, was completed in March 1995. In December 1992,
approximately 3,000 yd3 of soils contamination with petroleum constituents were
excavated from the North Balloon Area and transported to an appropriately-licensed
offsite landfill, in accordance with Title 23 CCR, Div. 3, Chapter 15, Article 2
requirements.
Other actions have also been completed at SHARPE. A total of 26 non-fuel
underground storage tanks were identified during the initial phases of CERCLA work
conducted at SHARPE. SHARPE, U.S. Environmental Protection Agency (EPA), the
Department of Toxic Substances Control (DTSC), and the Central Valley Regional
Water Quality Control Board (CVRWQCB) agreed that it would be best to manage
these underground storage tanks (USTs) in accordance with the California UST
regulations. Consequently, closure of these tank sites was deferred to the state
program that manages closure of USTs. A total of 20 tanks have been closed to date.
The remaining six tanks have only petroleum contamination and are in the process of
being closed (see Table 2-1). These six tanks are identified in Table 2-1 with an "*"
and will comply with State requirements. All work associated with USTs is conducted
under the oversight of the CVRWQCB.
Additional work has been planned under SHARPE's Stormwater Pollution Prevention
Program. A sump with sludge containing high levels of metals and VOCs will be
closed. This sump is located in the eastern portion of the Central Area (see pink dot
on Fig. 2-1). Closure will involve removal of the sludge and transportation to an
appropriately permitted waste management facility, followed by capping stormwater
connections to the sump. It has not yet been determined if the state will require that
the sump be removed. Another project being conducted under SHARPE's Stormwater
Pollution Prevention Plan involves the oxidation/evaporation pond (see orange shaded
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Table 2-1 . USTs Closed or in Process of Being Closed
Tank
Number
60
70
79
9
11
26
20
27
35
36
37
10
71*
29
48
49.
50
51
52
53
54
55*
5«
59
•
16*
46
Description
Oil Water Separator
Sump; Engine Test
Facility
Oil Water Separator;
wash rack
Oil Water Separator;
maintenance shop
Railroad maintenance bldg
(valve vault)
Railroad maintenance bldg
(waste oil tank)
Oil Water Separator;
wash rack
Contaminated fuel tank
Diesel/ waste oil
Contaminated Fuel
Contaminated Fuel
Conuminated Fuel
Conuminated Fuel
Conuminated Fuel
Waste solvent
Waste oil
Waste oil
Waste oil
Waste oil
Solvent waste
Waste oil
(eroaene
Waste Oil
Diesel/ Watte oil
Unknown
Sump/ Create trap
Sump (north of 404)
Oil-Water Separator
Comments
Tank removed October 1993 by El A, Inc. Sampling results indicate no remediation necessary
Tank removed October 1993 by EIA, Inc. Sampling results indicate no remediation necessary
Tank removed October 1993 by EIA, Inc. Sampling results indicate no remediation necessary
Valve and piping vault; concrete construction; clean baaed on ten reaulu by PetroTek; no
remediation required; removed May 1990
Steel Unk; removed 1990; sampling result ND for TPH-D and TPH-G; adjacent unk area
remediated by Speiss Construction (COE contract); Confirmed Clean
Investigation performed 1990 by Mark Group; contamination removed January 1990 by DieDe
Construction
Tank removed May 1990; no contamination found during removal sampling
Location of test pit; tank removed by PetroTek in March 1990; remediated/sampled by ESE in
1992; 3000 cubic yards of conuminated soil removed; extraction well NA-10 and MW 477A
installed
Removed 1984 for construction of WDC; sampled 9 Nov 1992 by ESE; no contamination; see soils
FS for details
Removed March 1986; remediated July 1986; certified clean closure to SJC in August 1986 by
SHARPE Contractors (Kleinfelder Associates did closure)
Removed March 1986; remediated July 1986; certified clean closure to SJC in August 1986 by
SHARPE Contractors (Kleinfelder Associates did closure)
Tank removed May 1990; Unk remediation being performed 1993-94 under Corps of Engineers
contract (CVRWQCB has reviewed design and specifications for this job)
Tank removed October 1993 by EIA Inc.; results pending; EIA will remediate based on
conuminam levels; reference uble from Work Plan Addendum - July 1992
Tank removed March 1990; samples showed no significant contamination (sampling by PetroTek);
does not require remediation based on sample results; Board groundwater concern - this IS within
capture zone of NB and CA systems
Tank removed March 1990; test pit location during November 1992; conuminated toils remediated;
test pit backfilled after CVRWQCB approval on 7 January 1993; tee PS5; MW 476 A located
downgradient
Tank removed March 1990; insulled MW 474 downgradient (PCB detected); remediation required
based on sampling results; contract awarded Summer, 1994
Tank removed March 1990; sampling results indicate no remediation necessary
Tank removed March 1990; sampling results indicate no remediation necessary
Tank removed March 1990; sampling results indicate no remediation necessary
Tank removed March 1990; sampling results indicate no remediation necessary
Tank removed March 1990; sampling results indicate no remediation necessary
Tank removed March 1990; insulled MW 473 downgradient (PCB detected); remediation required
>ased on sampling results; contract awarded Summer, 1994
Tank removed March 1990; remediation required based on tampling results; remediation completed.
Closure pending board review.
Tank removed May 1990; tampling result* indicate no remediation neceaaary
Inactive tump; liquids removed; located inside building; concrete construction; tampling to be
performed underneath tump March 1994; sump will be properly closed
nactive tump; remediation to be performed IAW Soils FS; tee PS 4 for RA tiles.
Oil Separator removed; no conumination; MW 439A replaced MW469A which was destroyed
•indicates that site has not been closed, further work required.
P/SHARPE/OU2ROD.V.5
06/27/95
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KEY
LOCATION OF SUMP AT PS4. TO BE REMOVED TO MITIGATE HIGH LEVELS OF METALS
AREAS TO BE FURTHER CHARACTERIZED VIA SOIL GAS
REMEDIATION FOR LEAD AND/OR CHROMIUM CONTAMINATED SOILS IN NORTH BALLOON AREA
REMEDIATION FOR LEAD AND/OR CHROMIUM CONTAMINATED SOILS IN SOUTH BALLOON AREA
AREA TO BE REMEDIATED AS PART OF STORMWATER PREVENTION POLLUTION PLAN
SA1 - SOIL AREA 1. TCE CONTAMINATED SOIL LOCATIONS TARGETED FOR REMEDIATION
ISV PILOT TEST LOCATION, TARGETED FOR REMEDIATION
0 400 BOO
SCALE FEET
Figure 2-1
PROPOSED ACTIONS AT SHARPE
SOURCE: ESE. IMS
RECORD OF DECISION
SHARPE SITE. LATHROP CALIFORNIA
U.S. Army
environmental C«nUr
Ab*rd*«n Proving Ground, Maryland
-------
area of Fig. 2-1). Elevated concentrations of metals will be removed from this site.
Closure of the sump and the oxidation/evaporation pond will comply will all federal,
state, and local laws. All Stormwater Pollution Prevention Program work will be
completed outside the scope of CERCLA. All work associated with storm water will
be conducted under the oversight of CVRWQCB National Pollutant Discharge
Elimination System (NPDES) Program.
All studies and remedial actions were conducted under a Federal Facilities Agreement
between the U.S. Department of Defense (DOD), EPA, and the State of California.
3.0 HIGHLIGHTS OF COMMUNITY PARTICIPATION
The RI/FS and Basewide Proposed Plan for SHARPE were released to the public on
February 22, 1995. These two documents were made available to the public in the
administrative record, located at SHARPE. The administrative file index (an index of
all reports and correspondence located in the administrative file) is located at the
Manteca Branch of the Stockton-San Joaquin County Public Library. The notice of
availability for these two documents was published in The Stockton Record. A public
comment period was held from February 22 to March 24, 1995. In addition, a public
meeting was held on March 1, 1995. At this meeting, representatives from SHARPE,
USAEC, DTSC, CVRWQCB, and EPA Region IX answered questions about the site
and the remedial alternatives under consideration. The Responsiveness Summary,
located at the end of this ROD, shows that no comments were received from the
public during the public comment period.
This document presents the selected remedial action for OU2 at SHARPE, Lathrop,
CA. This route of remedial action was chosen in accordance with CERCLA as
amended by SARA to the extent practicable, the NCP, and Chapter 6.8 of the
California Health and Safety Code. Further, these actions are being taken in response
to the California Water Code. The decision for this site is based on the administrative
record.
4.0 SCOPE AND ROLE OF RESPONSE ACTION
The scope of response actions for OU2 addresses contaminated soils at SHARPE. Al-
though it was initially intended that OU2 would address additional groundwater
contaminants at SHARPE, data collected since publication of the OU1 groundwater
ROD indicate that, at this point in time, no additional groundwater remedial action is
warranted. However, continued groundwater monitoring will be performed as part of
P/SHARPE/OU2ROD.R1
10/09/95
-------
the preferred alternatives described herein. It is expected that this Basewide ROD
represents the second and last ROD prepared for the SHARPE site.
The scope of the response action pertaining to soils addresses the following conditions
at the following locations (Fig. 2-1):
1. Soils containing lead and chromium that exceed cleanup standards in the
following areas:
• Eight areas in the North Balloon Area [see red-shaded areas, seven of
which are located within/near the balloon-shaped area; the eighth is
located below and to the left of the previously referenced area
(directly under the blue-shaded region of the North Balloon Area)].
• Six areas in the South Balloon Area (see gray-shaded regions with red
dots on the left side of Fig. 2-1).
2. Soils containing TCE that may potentially be source areas for contaminated
ground water are in the following areas:
• Five areas (see blue shaded areas of Fig. 2-1) that have been subject
to pilot testing using ISV.
• Two areas [see black shaded areas of Fig. 2-1 (one at upper-left of
figure and one at the northern end of the runway)] where elevated
concentrations of TCE have been reported.
• Seven areas (see green shaded areas of Fig. 2-1) have been identified
as requiring additional soil gas characterization, and contingent upon
the data provided, these areas may also be included within the
response action.
3. During the course of the CERCLA investigations, SHARPE recommended
that many sites be considered NFA sites. A no action determination is
appropriate in the following situations: when an area is already in a
protective state (i.e., an area poses no current or potential threats to human
health or the environment); or when CERCLA does not provide the
appropriate legal authority to undertake a remedial action. The 1994 Soils
FS documented all sites that SHARPE considers to require NFA along with
the rationale supporting why NFA would be required. EPA, DTSC, and
CVRWQCB have reviewed this information and agree that a total of
111 SWMUs fall into the category of NFA. Additional information
pertaining to the NFA sites is presented in Sec. 9.3.
P/SHARPE/OU2ROD.R1
10/09/95
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5.0 SUMMARY OF SITE CHARACTERISTICS
The data collected for the RI was comprehensive with respect to a variety of samples
analyzed for a variety of target analytes. The Risk Assessment (RA) evaluated all data
and defined COCs, as discussed in the Sec. 6.0 of this ROD. With the exception of
the pesticides chlordane and DDT, evaluation of COCs indicated that only lead and
chromium represent potential health threats to the onsite adult worker (the relevant
exposure population).
Elevated levels of chlordane and DDT were reported in the Pesticide Management
Area. A Removal Action Memorandum was finalized for this area in October 1994.
Soil removal was completed in March 1995. All soils determined to represent a
potential threat as defined in the Removal Action Memorandum were removed.
TCE, another site soil contaminant, was determined to not represent a potential threat
to human health or the environment based on the relevant exposure scenarios
evaluated in the RA. However, TCE-contaminated soils represent a continuing threat
to groundwater quality through leaching pathways. Therefore, the Soils FS evaluated
alternatives to remediate TCE-contaminated soils for the purpose of minimizing the
transport of TCE to groundwater.
Given the above information, the following discussion regarding site characteristics is
predominantly focused on lead, chromium, and TCE, as these contaminants represent
the chemicals that will need to be remediated as part of the response actions for OU2.
Additional information regarding site contaminants is presented in Sec. 6.0.
5.1 TCE CONTAMINATION
The disposal of VOCs occurred in designated disposal areas such as the South Balloon
Area and North Balloon Area. Disposal also occurred at undesignated, isolated spots
in the Central Area of the depot. Accidental releases of VOCs occurred at UST
locations and in areas where vehicles and equipment were defueled.
Seven VOC plumes exist in the groundwater within the three shallowest aquifers
beneath SHARPE and offsite, downgradient from the site (Fig. 5-1). The approach to
data presentation in the RI and the groundwater FS was to report suspected
contamination with respect to each of the contaminant groundwater plumes. To
maintain consistency, areas of suspected soil contamination are presented below by
P/SHARPE/OU2ROD.R1
10/09/95 9
-------
SHABPf BOO 2/95 HH
PLUME
A.B
Figure 5-1
VOC CONTAMINATION GROUNDWATER PLUMES
SOURCES LSL, 1988, 1998. SHAD. 1987
l^'l 5 UG/I U'l- CONTOUR - A TONh
F=q 5 ut/L ICE CONTOUR B "ONF
C2 i yC/l ICl CON10UK C ONt
A A.b.l INUIlAlCS Alr^fNIl IN UHl ',, A. B. AMU L CKLAUf) THAN 50 uG.'L
RECORD OF DECISION
SHARPE SITE, LATHROP. CALIFORNIA
U.S. Armg Envlronmintil C«nl«r
Atxrdun Proving Ground, nirgliinil
___ 10
-------
plume. The results of record searches, soil gas measurements, and soil analyses are
grouped by recognized VOC groundwater plumes (Fig. 5-1). Four different areas of
VOC-contaminated soil (predominantly TCE) exist at the site:
1. Plume 1 (South Balloon Area Plume)--An estimated total of 33,200 cubic
yards (yd3) of TCE-contaminated soil was found. Results of the 1987 soil
gas survey are summarized in Fig. 5-2.
2. Plumes 4 and 5~An estimated total of 11,400 yd3 of TCE-contaminated
soil was found. Results of the 1987 soil gas survey are summarized in
Fig. 5-3.
3. Plume 6-An estimated total of 14,700 yd3 of TCE-contaminated soil was
found. Results of the 1987 soil gas survey are summarized in Fig. 5-4.
4. Plumes 7 and 8 (North Balloon Area Plume)~An estimated total of
14,000 yd3 of TCE-contaminated soils was found. Results of the 1987 soil
gas survey are summarized in Fig. 5-5.
Additional areas were also investigated to determine if they are sources of VOCs:
5. Plume 2~Results of the 1987 soil gas survey are summarized in Fig. 5-6.
Confirmatory soil samples showed no soil contamination in this area.
6. Plume 3--Results of the 1987 are summarized in Fig. 5-7. Confirmatory
soil samples showed only one detection of TCE in soils, at a concentration
of 0.010 mg/kg.
Fig. 2-1 shows the areas onsite that are suspected of being source areas of TCE
contamination (designated as blue and black shaded areas). Additional areas (depicted
in green) show where further characterization via soil gas will be completed to
determine if additional source areas exist onsite.
5.2 LEAD- AND CHROMIUM-CONTAMINATED SOILS
Lead and chromium have been detected in concentrations greater than the cleanup
standards of 1,000 mg/kg and 300 mg/kg, respectively. A detailed discussion
regarding cleanup standards is presented in Sec. 7.1. The following SWMUs are
sources of this contamination:
1. S#3-Bldg. S-119;
2. S#26-Open dumping from Bldg. 170 to 184;
3. S#28-South Balloon Area (Metal Stripping Sludge Worked Through Soil);
and
4. S#29-South Balloon Area (burn pits).
P/SHARPE/OU2ROD.R1
10/09/95 11
-------
SHARPE ROD 2/95 MH
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AD 96 St»l Gas Or >d Coordinates
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Figure 5-3
SOIL GAS SAMPLING LOCATIONS,
PLUMES 4 AND 5 AREA
SOURCES: ESE, 198B, 1990, SHAD, 1987
RECORD OF DECISION
SHARPE SITE
LATHRQP, CALIFORNIA
U.S. Army
Environmental Center
Aberdeen Proving Ground, Maryland
13
-------
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SOIL GAS SAMPLING LOCATIONS.
PLUME 6 AREA
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RECORD OF DECISION
SHARPE SITE
LATHROP, CALIFORNIA
U.S. Army
Environmental Ctnttr
Abtrdein Proving Ground, Maryland
14
-------
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Figure 5-5
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RECORD OF DECISION
SHARPE SITE
LATHROP, CALIFORNIA
U.S. Armu
Environmental Ctntar
Aberdeen Proving Ground, Maryland
IF,
-------
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PLUME 2 AREA
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RECORD OF DECISION
SHARPESITE
LATHROP, CALIFORNIA
u.s.Armu
Environmental C«nUr
Abcrdtin Proving Ground. Maryland
16
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SOIL GAS SAMPLING LOCATIONS,
PLUME 3 AREA
SOURCES' ESE. 1988. 1990. SHAD. 1987.
RECORD OF DECISION
SHARPE SITE
LATHROP, CALIFORNIA
U.S. Army
Envlronmtntal Ctnttr
Aturdiin Proving Ground, Maryland
17
-------
Following presentation of total lead and chromium data for the aforementioned sites, a
discussion of leachable lead and chromium is presented.
5.2.1 S#3-BLDG. S-119 (SPRAY PAINT BOOTH)
The presence of lead and chromium was confirmed at this SWMU during the RI
phase of work. Additional field testing was performed in 1991 to delineate the extent
of lead contamination at Bldg. S-119 (Fig. 5-8). The results of the study indicated the
highest levels of lead contamination were found in the surface soil samples collected
south, southwest, and immediately west of Bldg. S-119. The highest lead
concentration reported was 5,115 milligrams per kilogram (mg/kg). None of the
split-spoon samples collected at depths between 0.5 and 4.0 feet below land surface
(ft-bls) in areas with high surface soil contamination contained any measurable
concentrations of lead. Also, two samples collected at one location indicated that the
contamination (4,493 mg/kg) lies in the several inches of soil covering the asphalt.
Lead contamination is restricted to the surface soils across the site, even where no
asphalt pavement is present. Chromium was not analyzed for in this study.
Fig. 5-9 is an isoconcentration map of lead in the surface soil at the study site. The
figure shows that the surface soil lead contamination has been found in all directions
radiating from Bldg. S-119, except possibly to the south. Sampling in this direction
was discontinued when Bldg. S-115 was reached.
The surface area of contaminated soil inside the 1,000-mg/kg contour line was
calculated by measurement with a planimeter. The resultant area is depicted in
Fig. 5-9. The area in which levels of lead are greater than 1,000-mg/kg covers
8,775 ft2, which represents 4,388 ft3 (163 yd3) of contaminated soil, assuming depth
of contamination is 6 inches.
No samples were collected for the evaluation of leachable metals.
5.2.2 S#26~OPEN DUMPING FROM BLDGS. 170 TO 184
Open dumping of waste received from Bldgs. 170 to 184 (Fig. 5-8) occurred in the
North Balloon Area. No coordinates have been specified for the dumping area. Work
conducted during the RI confirmed the frequency and elevated concentrations of lead
and chromium in soils.
P/SHARPE/OU2ROD.R1
10/09/95 18
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IAHP£ KOO 2/95 HH
INDUSTRIAL WASTE. HATER DUAL lit AND SEUAGE FACIUIIES
Figure 5-8
SWMUs IN NORTH BALLOON VACINITY
SOURCE- ESE 1988. 1990.
SOUTH SAN JOAOUIN IRRIGATION DRAINAGE CANAL
KEY
• 459A
ROADS
BUILDINGS
DRAINAGE CANAL
SOIL BORING LOCATION
WITH ANALYSIS
MONITOR WELL LOCATIONS
SUMP SAMPLING LOCATION
(WATER AND SEDIMENT)
SURFACE SAMPLE LOCATION
RECORD OF DECISION
SHARPE SITE. LATHROP. CALIFORNIA
U.S. Army
Envlrenmintil Cinur
Aturdiin Proving Ground. ntryi«n<
19
-------
SHARK ROD 2/9SMH
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PAVEMENT
KEY
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SOIL BORING
SOIL BORING 1.0.
RAILROAD
LEAD (ppm) CONTOUR
LEAD (ppm) CONCENTRATION
Figure 5-9
ISOCONCENTRATION MAP OF LEAD IN SURFACE
SOILS AT FORMER BUILDING S-119
RECORD OF DECISION
SHARPE SITE, LATHROP, CALIFORNIA
U.S. Army Envlronmtntal Ctnttr
Abtrdtin Proving Ground, Hergland
20
-------
In November 1992, an additional field effort was conducted to evaluate the extent of
lead and chromium contamination at SWMU No. 26 (S#26) in the North Balloon
Area. S#26 is the portion of the North Balloon Area characterized by past open
dumping of sandblasting waste received from Bldgs. 170 and 184 (Fig 5-10). The
predominant waste dumped in the North Balloon Area was probably sandblasting
sand, which is expected to contain paint chips and solvent residues.
The primary objectives of the investigation were to identify each of the dumping sites
where the sandblasting waste was disposed of, define the horizontal and vertical
extent of previously identified lead and chromium contamination at each dumping site,
and determine if the groundwater downgradient of the North Balloon Area was
contaminated with lead and chromium related to the sandblasting waste.
Lead in Soil
Soil contaminated with lead in excess of 1,000 mg/kg (measured by XRF), presented
in Fig. 5-10, was estimated to be approximately 27,650 ft2. Assuming a maximum
contamination depth of 6 inches, the total volume of lead-contaminated soil is
estimated at 13,825 ft3 (512 yd3).
Laboratory and XRF data for lead were plotted to evaluate correlation between the
two methods. Although the XRF data overestimated actual conditions, it was not
adjusted. Therefore, estimates of lead-contaminated soils are likely to be high.
Estimates derived are considered to be adequate for FS purposes. However, it would
be appropriate to confirm the extent of lead contamination during the remedial design
phase of work. Other parts of the North Balloon Area that should be evaluated
include nodes F1.5, M4, and O-13, where laboratory values of lead approached or
exceeded the cleanup standards of 1,000 mg/kg.
None of six soil samples from three collected borings (from 3 and 5 ft-bls) contained
lead in excess of 200 mg/kg. The observed values ranged from 2 to 196 mg/kg.
Chromium in Soil
Localized concentrations of 300 mg/kg chromium or higher as measured .by XRF
were observed at three locations (Fig. 5-11). The area inside the 300-mg/kg contour
line was estimated at approximately 12,375 ft2. Assuming a depth of contamination of
6 inches, the total volume of chromium-contaminated soil is approximately 6,188 ft2
(239 yd3).
P/SHARPE/OU2ROD.R1
10/09/95 21
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RECORD OF DECISION
SHARPE SITE, LATHROP CALIFORNIA
U.S. Army
Environmental C«nt«r
Ab«rd«»n Proving Ground, Mar/land
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»7
137
CONTOUR 1 5368 FT1
CONTOUR 2 9.543 FT<
CONTOUR 3 M3 PI*
0 100 200
SCALE FEET
Figure 5-11
CHROMIUM CONCENTRATIONS IN SOIL FOUND USING
XRF IN THE NORTH BALLOON AREA, NOVEMBER 1992
RECORD OF DECISION
SHARPE SITE, LATHROP CALIFORNIA
U.S. Army
Environmental C»nt«r
Ab«rd«»n Proving Ground. Maryland
23
-------
XRF and laboratory data for chromium were plotted to evaluate correlation between
the two methods. Although the XRF data overestimated actual conditions, it was not
adjusted. Therefore, estimates of chromium-contaminated soils are likely to be high.
Estimates derived are considered to be adequate for FS purposes. However, it would
be appropriate to confirm the extent of chromium contamination during the remedial
design phase of work. Grid node O-16 should also be evaluated during this phase, as
the laboratory value for chromium slightly exceeded the chromium cleanup standard
of 300 mg/kg.
Comparison of Figs. 5-10 and 5-11 indicates that soils with chromium concentrations
in excess of cleanup standards generally coincide with soils with lead concentrations
in excess of cleanup standards.
None of six soil samples from three collected borings (from 3 and 5 ft-bls) contained
chromium in excess of 300 mg/kg. The observed values ranged from 13 to 47 mg/kg.
Hexavalent chromium was found in all three samples analyzed for this compound.
The concentrations ranged from 0.11 to 0.57 mg/kg.
Lead and Chromium in Groundwater
Total and filtered groundwater samples were collected from wells near S#26 in
November 1992. Additional samples of filtered groundwater were analyzed in 1994
from four sampling episodes. The results of the 1992 and 1994 sampling efforts are
summarized in Table 5-1.
The limited data that is currently available shows that groundwater has not been
degraded by lead and chromium at levels greater than the drinking water standard of
15 /xg/L and 50 ftgfL, respectively.
5.2.3 S#28~SOUTH BALLOON AREA (METAL STRIPPING SLUDGE
WORKED THROUGH SOIL)
Waste from paint stripping operations at SHARPE historically has been disposed of in
the IWTP and the South Balloon Area. Waste (sludges) was routinely trucked to the
IWTP, where liquids were discharged into the oxidation ponds for treatment and
solids were spread on the ground in the South Balloon Area. The solids were then
turned into the ground during tests of refurbished heavy equipment in an early attempt
P/SHARPE/OU2ROD.R1
10/09/95 24
-------
TABLE 5-1. LEAD AND CHROMIUM IN NORTH BALLOON AREA GROUNDWATER
413A
420A
438A
LEAD CONCENTRATIONS
Nov 92 - Unfiltered
Nov 92 - Filtered
Feb94
Apr-May 94
Aug94
Oct94
< 0.002
< 0.002
< 0.005
< 0.005
0.016
< 0.005
0.012
< 0.002
< 0.005
< 0.005
< 0.005
< 0.005
0.003
< 0.002
<0.006
< 0.005
< 0.005
< 0.005
CHROMIUM CONCENTRATIONS
Nov 92 - Unfiltered
Nov 92 - Filtered
Feb94
Apr - May 94
Aug 94
Oct94
0.044(0.033)
0.042 (0.031)
0.013
—
0.011
0.011
0.030 (0.008)
0.018 (0.011)
0.040
0.038
0.011
0.032
< 0.006 (< 0.003)
< 0.006 (< 0.003)
< 0.006
< 0.005
< 0.005
< 0.005
All concentrations in milligrams per liter.
Values in ( ) represent concentration of Cr
Source: ESE.
P/SHARPE/OU2ROD.V.8
06/27/95
25
-------
at bioremediation. Tests called for 4 hours of continuous operation; therefore, it is
presumed that the sludge was thoroughly mixed with the soil.
Sampling conducted during the RI phase of work indicated the presence of elevated
lead and chromium concentrations in soil.
Additional soil sampling in the South Balloon Area was conducted during April 1994
to delineate and characterize potential lead and chromium contamination. In 1984,
Technos, Inc. used various geophysical methods to map the location of eight burial
trenches and pits in the South Balloon Area. This study indicated that the trenches and
pits may contain buried metals. The purpose of soil sampling was to determine
whether these burial trenches and pits are a source of metals contamination.
Two types of soil samples were collected; shallow soil samples (0-2 ft) and soil
borings (0-15 ft).
Sample Locations
To ensure that the samples were properly located in the field and collected at known
locations, a grid was set up across the South Balloon Area. The grid was surveyed in
by a licensed surveyor and was based on the state plane coordinate system. It was set
up with a 100-ft spacing and oriented north-south and east-west. The grid was labeled
alphabetically from west to east and numerically from north to south (Fig. 5-12).
Samples were located on the grid and named for the grid location (i.e., 50 ft east
of 1A).
Shallow Soil Samples
Initially, 41 shallow soil samples were collected at predetermined locations. Based on
the results from these initial samples, 9 additional shallow soil samples were collected
from locations determined by the CVRWQCB, and two 15-ft profile borings were
completed near two shallow sampling locations. Fig. 5-12 shows the location of the
50 shallow soil samples and the two profile borings.
Soil Borings ,
Twenty-nine initial borings in predetermined locations in the South Balloon Area were
sampled, and 10 borings were sampled in three burn pit areas just west of the South
Balloon Area. Based on the results of these samples, 10 additional borings and
2 vertical profile borings were completed at locations determined by the CVRWQCB
P/SHARJPE/OU2ROD.R1
10/09/95 26
-------
J* I • * i.i H
SHARPE SOUTH BALLOON
KEY
• SURFICIAL SAMPLES 0-2 FT
• SOIL BORING LOCATIONS. 0-13 II
EXTENT OF SUSPECTED TRENCH
swuu
S-M II BURN PIT SAMPLE STATION 10
-------
in the South Balloon and burn pit areas. Fig. 5-12 shows the location of these
49 borings and the two vertical profile borings.
Chromium
Samples were collected in accordance with the Work Plan Addendum (ESE, 1994c).
Laboratory and XRF data for chromium were plotted to evaluate correlation between
the two methods. This effort showed there was poor correlation between the field and
laboratory methods for determining chromium concentrations in soil. Consequently,
adjustments to the data were necessary to make the XRF data more representative of
the confirmation samples. The adjusted data are adequate to conclude that some soils
at depths of 0-2 ft do exceed the cleanup standard for chromium.
Adjusted data representing samples collected from 0-2 ft, 0-5 ft, 5-10 ft, and
10-15 ft are presented in Figs. 5-13, 5-14, 5-15, and 5-16, respectively.
Evaluation of data presented in the referenced figures indicates only three locations
where chromium exceeds the 300 mg/kg cleanup level:
1. 50E-1H (368 mg/kg, 3-4 ft);
2. 50E-1F (722 mg/kg, 14-14.5 ft); and
3. S29B4 (329 mg/kg, 12.5-13.5 ft).
The quality of the adjusted data is not considered adequate to determine the volume of
contaminated soils requiring remediation with a high level of certainty. It would be
appropriate to reevaluate the extent of chromium contamination in the South Balloon
Area during the remedial design phase of work at locations where chromium has been
reported or is suspected of exceeding the cleanup standard (based on the XRF data,
e.g., grid point 9G).
Considering the previous information and that shallow soil samples (0-2 ft, the
interval considered appropriate for remediation when considering protection of human
health and environment) were not collected in areas where chromium was reported
greater than 300 mg/kg, two assumptions were necessary to estimate the volume of
chromium-contaminated soils exceeding cleanup standards:
1. All points where chromium concentrations were reported to exceed the
cleanup standard will be assumed to require remediation in the 0- to
2-ft range; and
P/SHARPE/OU2ROD.R1
10/09/95 28
-------
KEY
• SAMPLE LOCATION
10 CONC. ppm
44.8 LAB W-WET. (ug/l)
EXTENT OF SUSPECTED TRENCH
swuu
0 75 150
SCALE FEET
Figure 5-13
SOIL SAMPLE LOCATIONS
SOUTH BALLOON AREA
CHROMIUM 0 - 2 FT SURFICIAL
RECORD OF DECISION
SHARPE SITE. LATHROP. CALIFORNIA
U.S. Army
Environmental C«nt«r
Abcrdawi Proving Ground, Maryland
-------
SHMP£ HOD 2/3S HH
Cl J
:'.f
GIB
-29 B6 44 (2-3)—'
-29 B8 17 (3.5-4.5
-29 Bll 41 (2.5-3)
-29 BIO <1 (2-3)-
-29 B5 8 (3-4>
-29 B9 110(2-2.5)12.8
r
*5T
-te
\/
37 a
f-Pf-3>
«-«» S3CL
SHARPE SOUTH BALLOON
<1
<2-3>
21 TL7
3 233
(0-1X3-4)
KEY
• SAMPLE LOCATION
10 CONC. ppm
SAMPLE DEPTH (0-1). ft
11.7 LAB W-WET. (ug/l)
RED VALUE > PRG
EXTENT OF SUSPECTED TRENCH
SWMU
l-J. • BURN PIT SAMPLE STATION 10
NOTE: SAMPLE LOCATIONS WITH TWO ASSOCIATED DATA
POINTS WERE TAKEN AT SEPARATE DEPTHS.
0 75 150
SCALE FEET
Fi(jure5-14 '
SOIL SAMPLE LOCATIONS
SOUTH BALLOON AREA
CHROMIUM 0 - 5 FT INTERVAL
SOUKCE tsc. iw4
RECORD OF DECISION
SHARPE SITE. LATHROP. CALIFORNIA
U.S. Army
Environmental C«nt«r
Abirdnn Proving Ground. Maryland
30
-------
SHAJtfC ROD Z/95 MH
S-29 B6 2 (5-6)
S-29 B8 6 <7-8>
S-29 BU none
S-29 BIO none
er.
-H
*»-«)
S30
i: i!
J-M M t-30 II
SHARPE SOUTH BALLOON
KEY
• SAMPLE LOCATION
10 CONG, ppm
SAMPLE DEPTH (5-6), ft
31.1 \M W-WET, (ug/l)
EXTENT OF SUSPECTED TRENCH
SWMU
«-» li SURN PIT SAMPLE STATION 10
0 7S ISO
SCALE FEET
Rgure 5-15
SOIL SAMPLE LOCATIONS
SOUTH BALLOON AREA
CHROMIUM S - 10 FT INTERVAL
RECORD Of DECISION
SHARPE SITE. LATHROP.
11
-------
SHARPE ROD 2/9S UH
722 16
(14-14,5)
6.69 BDL
(12-13)
S-29 B6 58«3.5-14.5)BDL
S-29 B8 7C13.5-13.S)
S-29 Bll none
S-29 BIO none
S-29 B5 8U1-13:
S-29 B9 none
• SAMPLE LOCATION
10 CONC. ppm
SAMPLE DEPTH (10-11). «
10 LAfl W-WET. (ug/l)
DEO VALUE > PRO
EXTENT OF SUSPECTED TRENCH
SWMU
»-* • IURN PIT SAMPLE STATION 10
SHARPE SOUTH BALLOON
RECORD OF DECISION
SHARPE SITE, LATHROP. CAUFORNIA
Figure 5-16
SOIL SAMPLE LOCATIONS
SOUTH BALLOON AREA
CHROMIUM 10 - 15 FT INTERVAL
U.S. Army
Environmental Center
AbMd«n Proving Ground. Maryland
-------
2. The extent of contamination will be based on the average area of
^ contamination reported for the North Balloon Area effort. This is a
reasonable assumption, since the method of waste disposal in the South
Balloon Area shallow soils (soil spreading) was similar to the North
Balloon Area.
As shown in Fig. 5-11, three locations exceed the cleanup standard for chromium in
the North Balloon Area. The total area represented by these locations is 12,375 ft2;
the average area represented per site is 4,125 ft2. Assuming that this area is
representative of areas in the South Balloon Area where chromium has exceeded
300 mg/kg, the total area requiring remediation in the South Balloon Area is
estimated as 12,375 ft2 (a total of three sites). Assuming excavation to a depth of 2 ft,
the total volume of soils to be remediated is approximately 916 yd3.
Table 5-2 also reports leachable chromium concentrations from specific samples. This
data indicates there is a potential threat to groundwater from leachable chromium.
More detailed information on this subject can be found in the FS.
Lead
Lead data were managed like the chromium data. Laboratory and XRF data for lead
were plotted to evaluate correlation between the two methods. This effort showed
there was poor correlation between the field and laboratory methods for determining
lead concentrations in soil. Consequently, adjustments to the data were necessary to
make the XRF data more representative of the confirmation samples. The adjusted
data are adequate to conclude that some soils at depths of 0-2 ft do exceed the cleanup
standard for lead. Adjusted data representing samples collected from 0-2 ft, 0-5 ft,
5-10 ft, and 10-15 ft are presented in Figs. 5-17, 5-18, 5-19, and 5-20, respectively.
Evaluation of the data in Tables 5-2 and 5-3 and the referenced figures indicates that
lead exceeds the 1,000 mg/kg cleanup standard in eight locations:
1. 9E (2-3 ft; 6,691 mg/kg by XRF; 27,500 mg/kg by laboratory analysis);
2. 9E (5-6 ft; 1,027 mg/kg by XRF; 17,700 mg/kg by laboratory analysis);
3. 50E-1H (3-4 ft; 1,481 mg/kg by XRF; 3,990 mg/kg by laboratory
analysis);
4. 50E-1G (3-4 ft; 1,160 mg/kg by laboratory analysis);
5. 50E-1G (6-7 ft; 1,140 mg/kg by laboratory analysis);
6. S29-B4 (8-9 ft; 1,421 mg/kg by XRF analysis);
P/SHARPE/OU2ROD.RI
10/09/95 33
-------
O SAMPLE LOCATION
17 CONC. ppm
SO.S LAB OI-WET. (ilfl/l)
RED VALUE > PRO.
EXTENT OF SUSPECTED TRENCH
SWUU
0 75 150
E
SCALE FEET
SHARPE SOUTH BALLOON
RECORD OF DECISION
SHARPE SITE. LATHROP. CALIFORNIA
Figure 5-17
SOIL SAMPLE LOCATIONS
SOUTH BALLOON AREA
LEAD 0-2 FT SURFICIAL
U.S. »m>f
Environmental C*''
AbirdMft Pf«
-------
-29 B6 60(2-3>
-39 B8 177 <3.5-4.5>
-29 BU 412 25.3
4,9 11,1
252 474
(0-1X3-4)
KEY
SAMPLE LOCATION
CONC. ppm
SAMPLE DEPTH (0-1), ft
24.8 LAB OI-WET, (ug/l)
RED VALUE > PRO
EXTENT OF SUSPECTED TRENCH
SWMU
1-3. ii BURN PIT SAMPLE STATION ID
NOTE: SAMPLE LOCATIONS WITH TWO ASSOCIATED DATA
POINTS WERE TAKEN AT SEPERATE DEPTHS.
0 75 ISO
. SCALE FEET
-------
29 B6 -
29 B8 236(7-8)
29 B11 none
£9 BIO none
29 B5 <1 (6.5-7.5)
29 B9 none
•~^^_
39
(6-7)
<1
(8-9)
KEY
• SAMPLE LOCATION
10 CONC. ppm
SAMPLE DEPTH (5-6), ft
•.6 LAB M-WET. (ug/l)
RED VALUE > PRG
EXTENT OF SUSPECTED TRENCH
SWMU
1-3. » BURN PIT SAMPLE STATION ID
0 75 150
SCALE FEET
Figure 5-19
SOIL SAMPLE LOCATIONS
SOUTH BALLOON AREA
LEAD 5-10 FT INTERVAL
RECORD OF DECISION
SHARPE SITE. LATHROP, CALIFORNIA
U.S. Army
Environmental C«n!*r
Ab«r4*«n Proving Ground. Maryland
-------
HULJ il, ab Oi
3.
(14-14,5)
S-29 B6
-------
Table 5-2. Trench and Burn Pit Boring Soil Samples Collected in the South Balloon Area
Grid tempi*
Uettten Otpth
ff-bos)
Tf«ngh 1S ft Boringt-
SE 2-3'
5-6'
12-13
10N-8H 4 • 5
6-7
11-12
D7 2-3
6-7
13.5 • 14.5
*B 2-3
9-10
10-11
41S43CE-4 1 • 2
7.5-85
12-13
SCSSSOE-4 1 • 2
7-8
13-14
50S450E-2 2 - 3
7.5-15
14-15
3C 2-3
7-8
13.5-14.5
SOS8S3E-1 3 • 4
8x- 9
12-13
SI 2-3
6-7
12-13
3J 3-4
6-9
12.5 - 13.5
25N&25W-4 2 • 3
8 S - 9.5
13-14
•OS-2H 4 . S
9-10
14-15
IOStSOE-3 2-3
7-8
11.8- 12.5
•OE-ZF 2-3
«-9
125-13.5
CoiTtcle
Analytic*!
Cf
(ppm)
171
119
S
0
3
3
0
2
0
0
2
0
0
0
26
0
0
0
0
11
71
5
9
2
4
12
20
0
0
0
0
0
0
2
0
10
0
w
0
3
131
0
(
S
3
• ••> ••
.. _
38
-------
Table 5-2. Trench and Bum Pit Boring Soil Samples Collected in the South Balloon Area
(Continued, Page 2 of 4)
tompl*
Grid ftampl*
Location Depth
fll-bOJ)
80E-1H 3-4
C.S-7.S
12-13
90E-1G 3-4
6-7
13-14
50E-1F 2-3
6-7
14 - 14.5
SON&50E-1 2 • 3
e.5-7.5
13 • 13.5
7S-1F 3-4
7-8
13-14
SON-IE 3-4
55-65
12-13
SOE-2E 3-4
6-e
12.5 • 13.5
SOW-IE 3-4
6.5-7.5
12-13
SOE-30 3-4
J.B - 7.6
13-14
SCS-3D 4-5
7-8
12-13
SOS-40 4 • 5
7.4 - 84
14-14.5
SOS&SOE-4 3-4
7.3-8.3
14-15
SOStSOE-S 3-4
• -7
12.8-13.8
SOS45-E-5 9-4
•.4 • 7.4
12.5-13.5
total Sampl
•urn ntWtt merinpt-
S30-B1 4-5
7-6
13-14
K30-B2 3-4
«-7
11.6 - 12.6
$30-63 3-4
Conecud XRF
Analytical Values
Ct
(pern)
968
0
0
99
57
5
14
5
722
119
22
42
8
22
3
0
0
5
4
0
4
0
0
0
0
3
11
0
0
0
0
3
4
0
0
12
0
10
24
0
0
0
67
e
4
3
10
6
14
2
Pb
(ppm)
1481
35
se
860
714
126
130
39
0
452
242
126
209
31
187
45
65
16
275
66
5
0
0
100
0
0
0
0
0
0
21
0
75
5
0
1
43
42
142
52
36
219
67
0
3
14
6
44
4
5
LabomtoiY Arjyrtiai VaJuts Laboratory
OI-WET Total Sample ID
Cf Pb & Pb Cx»6" Numb*
(ueyi) (ue/L) (mo/kq) (mqAa) lms\a)
37 24.6 233 3990 -- 21
*• »• »« • • *• ••
•>• •• ** »• •• ••
27 15.7 65.3 1160 -- 23
14 3.5 658 1140 -• 24
10 2.1 12.3 2.33 •• 25
• • *• •• * • •• • -
18 36 15.2 41.9 •• 19
BDL BDL -- -- -- 31
..
• • •• •• » - •> -•
• • •*
*•
• • • • * . •• •• ••
• • •• •• •• •• « •
..
..
• • •• •• •» • » ••
BDL 5.6 -. -- -• 36
..
16 16 9 9 0
• • •» * • •>• •• «"
• » »• •• •• •• »"
*• .•• •• » • •• ••
• • •• * . • • •• ••
• • *• * . •• ' * " » *
BDL BOL -- •• •• 37
• • • • •• •• •• • •
39
-------
Table 5-2. Trench and Bum Pit Boring Soil Samples Collected in the South Balloon Area
(Continued, Page 3 of 4)
Simple
Grid tampk
leatien Depth
fll-bes)
6.5-7.5
12-13
S30-B4 2-3
e-r
13.5 • 14.5
S28-B4 1.5-2.5
8-8
12.5-13.5
S2S-B5 3-4
• 5-7.5
11-12
S29-B6 2 • 3
5-6
135-14.5
829-87 2-3
5-6
10-11
S18-B2 3-4
7.5 -8.5
12.5-13.5
S16-B3 3-4
6-9
10-11
Total Sampl
Optional frgneh and Burn Ph Borinpt
S1B-B4 3.5-^5
7.5-6.5
13-14
S29-BS 3.5 • 4.5
7-8
125-13$
S29-B9 2 • 2.5
S29-B10 2-3
S29-B11 2.5-3
SOS-9E 3.4
6-7
10-11
•OE-9E 3-4
t.a-92
12 • 12.5
KU7SN.1 9-4
9.5 • 6.5
105-115
fOS-11 2-3
l-t
12.5-13.5
2M 35-45
• -10
13-14
Total Samples:
Corrected XRF
Analytical Values
Ct
(ppm)
0
5
4
0
4
43
ise
329
6
0
8
44
2
se
6
0
0
10
3
16
21
13
W
30
0
4
20
17
6
7
110
0
41
6
25
23
0
14
0
3
0
2
25
4
S
0
0
33
24
Pb
(ppm)
3
S
0
0
0
192
1421
0
0
0
S
60
0
0
0
0
0
0
34
22
0
£2
27
30
339
197
151
177
236
331
1W2
357
412
279
268
347
68
197
276
242
K
CS
156
108
175
34
158
610
24
laboratory Antyftinl Values Laboratory
DI-WET Tail Sarnplt ID
Ct PP & Pt Ct»6" Notnbtf
(UBT.) (UB'I) (mo/ks) (TtBrtiQ)
-------
Table 5-2. Trench and Bum Pit Boring Soil Samples Collected in the South Balloon Area
(Continued, Page 4 of 4)
Sample
Grid Sample
Local ion Depth
ft-bos)
Vertical Profile 1! ft Boringi-
S29-BU 0-1
2-3
a.s • 6.s
12.5-13.5
48E-1F 0-1
3-4
e-s
12-13
Total Sanpl
Grand Total Samples:
Corrected XRF
Anarytical Values
Cr
(ppm)
35
132
ise
11
3
233
0
7
B
149
Pt
(ppm)
394
808
1364
206
252
474
0
0
t
149
Laboratory Analytical Values
DI-WET
Cr
(Ufl.1)
18
20
31.1
BOL
21
11.7
BDL
BDL
e
31
P6
-------
Table 5-3. Surficial Soil Samples Collected in the South Balloon Area
Sample
Grid Simpl*
Location Depth
fl-fcss)
frihial Surficlll Sail Simpl^y ;
8B 0-2
CE 0-2
CO 0-2'
35S-4I 0-2'
31E-1E 0-2'
42W-2C 0-2'
42S-2B 0-2
3CS&36E-1 0 • 2
28 0-2
4B 0-2
SB 0-2
ec 0-2
4C 0-2
3E 0-2
30 0-2
SO 0-2
60 0-2
46S&52W-5 0-2
S2N-6E 0 • 2
32N-SE 0 • 2
4F 0-2
2SS121W-4 0-2
50 0-2
Sf 0-2
30S-3G 0 - 2
if 0-2
2E 0-2
37S-2H 0 - 2
1H 0-2
S6N-1H 0-2
1C 0-2
42S.II 0 • 2
49KI-2! 0-2
2G 0-2
21E&24N-1 0-2
21E-1F 0-2
12W-1F 0>»
•9N-1E 0-2
SOE-7H 0 - 2
SON-61 0 - 2
SI 0-2
Total Simp!
fifrtum.1 Sutfici.1 Sail S,mpl.«.
7J 0-2
7N-9C 0-2
10E-9G 0-2
10W-9C 0-2
10S-9G 0-2
20S110E-3 0-2
30S-3G 0-2
10S-JG 0-2
20S*10W-3 0-2
Toul Sampl
V«rtiE«l Prnril* 18 B Bsringf
42S-2B 0-0.5
2-3
FMld XRF
Cf
(ppm)
4
1
C9
14
C
0
20
1
3
0
1
18
9
0
0
0
1
8
1
0
7
2
5
9
41
0
0
27
8
0
9
0
3
12
3
26
0
2
4
0
s
41
0
0
2
13
2
4
0
10
0
9
18
2
Valun
P6
(ppm)
177
35
•38
0
0
0
205
381
83
12
145
227
6
46
5
0
0
27
39
9
55
0
62
22
166
SB
0
0
64
0
66
0
79
3
0
0
0
8
0
17
0
41
252
0
177
268
CO
204
94
299
17
9
374
218
Ltboritory AnatyXici! Valutt Laboratory
OI-WET Total Samplt ID
Ci t>ti Cf Pt Number
(uo'L) (ua'L) (mg/ks) (ttflfVa)
25.4 64.3 6
..
448" 50.3- •• •• 1
..
..
..
1 .. .. .. ..
73.7 365 7
..
..
.. .. ..
147 241 •• •- 4
.. .. .. ..
..
•• •• -• •• »•
..
..
..
..
..
..
..
. .
•. •• •• •• ••
22 524 .- •• 3
..
..
189 558 8
..
..
..
..
30.5 102 9
..
14.6 27.2 -• •• 5
227 1230 •• •• 2
..
..
..
8.6S 12.4 10
.. .. .. •- ••
55 5 5
..
V* •• •• -• ••
•• •• •- •• ••
..
• • •• »• ~ » ••
..
.. .. -. •• .-
.. .. -- »
.. .. .. ..
00 0 0
.. ..
..
42
-------
Table 5-3. Surficial Soil Samples Collected in the South Balloon Area
(Continued, Page 2 of 2
Sample
Grid
loot ion
8G
FiettXRF Laboratory Anaryiticil Values Laboratory
Sample
Depth
ff-bfls)
8-8
11 -12
0-1*
2-3"
• •ID-
11-12'
An»M>eal Values DI-WET Total Sample ID
a
(ppm)
7
7
37
27
0
4
Pt Cr Pb Cr Pb Numbw
(ppm) (UB/L) (uo/L) (ms/kfl) (mo/kg)
22S
277
504
426
169
91
.
-
.
.
.
•
Total Simpl
Cnnd Total Samples:
•Samples apt* wHh CaWomia CexMral Valley Regional Witar Quality Convo! Board (total 8).
—DI-WET Toe 22 metals anarysJs wu done on aampla from 9G
Mote: •- « not applicable or umple rut anaryzed.
43
-------
7. S29-B9 (2-2.5 ft; 1,541 mg/kg by laboratory analysis); and
8. S29-B12 (8.5-9.5 ft; 1,364 mg/kg by XRF analysis).
The quality of the adjusted data is not adequate to determine the volume of
contaminated soils requiring remediation with a high level of certainty. It would be
appropriate to reevaluate the extent of lead contamination in the South Balloon Area
during the remedial design phase at locations where lead has been reported to exceed
the cleanup standard or is suspected of exceeding the cleanup standard (based on the
XRF data, e.g., grid locations 9G, 20S-3G, SOS and 50E-2B, 50S-2H, SON and
50E-1F, and location S29-B4).
Considering the previous information and that shallow soil samples (0-2 ft) were not
collected in areas where lead was reported greater than 1,000 mg/kg, two assumptions
were necessary to estimate the volume of lead contaminated soils exceeding cleanup
standards:
1. All points where lead concentration were reported to exceed the cleanup
standard will be assumed to require remediation in the 0 to 2 ft range; and
2. The extent of contamination will be based on the average area of
contamination reported for the North Balloon Area effort. This is
reasonable since the method of waste disposal in the South Balloon Area
shallow soils (soil spreading) was similar to the North Balloon Area.
As shown on Fig. 5-10, seven locations exceed the cleanup standard for lead. The
total area represented by these locations is 27,650 ft2; the average area represented
per site is 3,950 ft2. Assuming that this area is representative of areas where lead
exceeds 1,000 mg/kg, the total area requiring remediation in the South Balloon Area
is estimated at 19,750 ft2 (a total of five sites). Assuming excavation to a depth of
2 ft, the total volume of soils to be remediated is approximately 1,460 yd3.
Table 5-2 also reports leachable lead concentrations from specific samples. This data
indicate there is a potential threat to groundwater from leachable lead. More detailed
information on this subject can be found in the FS.
Lead and Chromium
Based on the previous information, and considering that the cleanup standards for lead
and chromium have been exceeded at this site, remediation is warranted at this
SWMU. The previous sections estimate the total volume of soil with lead above
cleanup standards as 1,460 yd3; the total volume of soil with chromium above cleanup
P/SHARPE/OU2ROD.R1
10/09/95 44
-------
standards is estimated as 916 yd3. The combined volume of soils requiring
remediation in the South Balloon Area is estimated as 2,090 yd3. Because there are
two locations where both lead and chromium are reported to exceed cleanup
standards, the total volume of soils requiring remediation is not the sum of lead- and
chromium-contaminated soil volumes. The areas to be remediated for lead- and
chromium-contaminated soils are presented in Fig. 5-21.
The previous sections use several assumptions to estimate the volume of contaminated
soils. The volume estimates were developed for FS purposes only. However, even if
the actual volume of soil requiring remediation varies greatly from the above
estimate, the analysis that was presented in the FS is adequate for remedy selection.
See App. G-2 of the Soils FS for further information pertaining to this SWMU.
5.2.4 S#29--SOUTH BALLOON (BURN PITS)
Much of the waste generated at the site including wood, paper, empty paint and
solvent cans, waste paint, waste solvents, waste oil, used hydraulic fluid, and
"anything else that would burn", was disposed of in burn pits in the South Balloon
Area. Contaminated fuel reportedly was not disposed of in the pits. Among other
constituents, lead and chromium were detected in the burn pit soils. Further
characterization of this site was completed in 1994. The data and figures presented
underlie discussion of S#28 can be referenced for data pertaining to the burn pits.
5.2.5 LEACHABLE LEAD AND CHROMIUM AT S#26 AND S#28
As part of the total lead and chromium delineation activities for S#26 and S#28,
samples were also collected to evaluate leachable lead and chromium from site soils.
Leachability was evaluated using the California De-Ionized (DI) Water Waste
Extraction Test (WET).
At the request of CVRWQCB, SHARPE completed a water quality assessment for
lead and chromium. The water quality assessment uses results from DI-WET testing.
Results of the water quality assessment for lead and chromium are presented in
Tables 5-4 and 5-5, respectively. Data noted by Area NBA represents samples
collected from SWMU S#26. Data noted by Area SBA represents samples collected
from S#28.
P/SHARPE/OU2ROD.R1
10/09/95 45
-------
SHARft KOD &9S MM
KEY
POTENTIAL SOIL REMEDIATION AREAS +
-EXTENT OF SUSPECTED TRENCH
R SO
0 75 150
SCALE FEET
ICH /
Figure 5-21
POTENTIAL SOIL REMEDIATION LOCATIONS
SOUTH BALLOON AREA
SOUSCC. CSE. 1W<
RECORD OF DECISION
SHARPE SITE. LATHROP. CALIFORNIA
U.S. Army
Env1ronm«ntal C«nt«r
Ab«rd««n Proving Ground. Maryland
46
-------
Table 5-4. Water Quality Assessment for Lead
Location
M4-SHPBS2
B1-SHPBS2*
SL-04-C
SL-04-B
SL-02-C
SL-01-A
SL-03-B
SS 1 to 6
SL-03-C
SL-01-B
SL-03-A
R3.5-SHPBS2
S21-SHPBS2
T17.5SHPBS2
SL-01-C
T16.5-SHPBS2
SL-02-B
SL-04-A
P5.5-SHPBS2
SL-02-A
R18.5-SHPBS2
O16-SHPBS2
Q4-SHPBS2
41S&30E~4 (12-13 ft)
50E-1G (13-14 ft)
48E-1F (8-9 ft)
50S&50E-U12-13 ft)
S29-B12 (12.5-13.5 ft)
50E-1G (6-7 ft)
50E-1F (14-14.5 ft)
50S&50E-3 (7-8 ft)
S29-B12 (2-3 ft)
24N&25W-4 (13-14 ft)
50S-9E (10-11 ft)
48E1F (0-1 ft)
S18-B2 (12.5-13.5 ft)
S29-B12 (0-1 ft)
50S&50E-5 (12.8-13.8 ft)
9E (12-13 ft)
S29-B6 (13.5-14.5 ft)
9E (5-6 ft)
50S11 (12.5-13.5 ft)
48E-1F (3-4 ft)
50E-1G (2-3 ft)
50S-2H (9-10 ft)
50E-1H (3-4 ft)
S29-B9 (2-2.5 ft)
21E&24N-1 (0-2 ft)
S29-B12 (8.5-9.5 ft)
9E (2-3 ft)
9G (0-2 ft)
20S-3G (0-2 ft)
6C (0-2 ft)
21E-1F (0-2 ft)
Area
NBA
NBA
NBA
NBA
NBA
NBA
NBA
NBA
NBA
NBA
NBA
NBA
NBA
NBA
NBA
NBA
NBA
NBA
NBA
NBA
NBA
NBA
NBA
SBA
Total
tiglg
1000
4710
NA
NA
NA
NA
NA
NA
NA
NA
NA
2130
5750
2250
NA
5330
NA
NA
1640
NA
2260
1430
605
84
SBA 126
SBA
SBA
SBA
SBA
SBA
SBA
SBA
SBA
SBA
SBA
SBA
SBA
SBA
SBA
SBA
SBA
SBA
SBA
SBA
SBA
SBA
SBA
SBA
SBA
SBA
SBA
SBA
SBA
SBA
0
375
206
714
0
0
808
105
347
252
22
394
142
369
0
1027
175
474
960
575
1481
1542
0
1364
6691
936
166
227
0
DI-WET
Mg/L
NA
139000
2
2
2
2
2.3
3.2
3.3
3.4
3.4
3.6
3.8
3.9
4.8
5.3
6.3
9.6
10.1
11.2
11.4
123
565
2
2.1
2.4
2.4
3.1
3.5
3.6
4.1
4.4
4.4
4.7
4.9
5.1
5.6
5.8
8.2
8.5
9.26
10.3
11.1
15.7
15.8
24.6
25.3
27.5
31
39.9
50.3
52.4
241
1230
Leachable
Concentration
NA
NA
20
20
20
20
23
32
33
34
34
36
38
39
48
53
63
96
101
112
114
1230
5650
20
21
24
24
31
35
36
41
44
44
47
49
51
56
58
82
85
92.6
103
111
157
158
246
253
275
310
399
503
524
2410
12300
Beneficial
Use
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15 '
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
Required
Protection
NA
NA
1
1
1
1
2
2
2
2
2
2
3
3
3
4
4
6
7
7
8
82
377
1
1
2
2
2
2
2
3
3
3
3
3
3
4
4
5
6
6
7
7
10
11
16
17
18
21
27
34
35
161
820
•All results obtained using California WET, except B1-SHPBS2, which was analyzed using TCLP.
NA = not analyzed.
Source: ESE.
P/SHARPE/OU2ROD.V .48
06/27/95
47
-------
Table 5-5. Water Quality Assessment for Chromium
Location
T17.5SHPBS2
B1-SHPBS2*
M4-SHPBS2
T16.5-SHPBS2
R18.5-SHPBS2
SL-03-A
SL-02-C
SL-01-A
SL-03-C
SL-Q4-A
SL-01-B
SL-02-A
SL-03-B
SL-04-C
SS 1 to 6
SL-04-B
P5.5-SHPBS2
SL-01-C
SL-02-B
O16-SHPBS2
S21-SHPBS2
R3.5-SHPBS2
Q4-SHPBS2
S18-B2 (12.5-13.5 ft)
50E-1G (13-14 ft)
41S&30E-4 (12-13 fa
9E (12-13 ft)
48E-1F H-4 ft)
S29-B9 f2-2.5 'ft)
9E C2-3 ft)
50E-1G (6-7 ft)
21E&24N-1 rt)-2 ft)
50E-1F H4-14.5 ft)
S29-B12 (0-1 ft)
S29-B12 (2-3 ft)
48E1F rO-1 ft)
20S-3G (0-2 ft)
50S&50E-3 (7-8 ft)
50E-1G (2-3 ft)
S2Q-B12 (8.5-9.5 ft)
50E-1H f3-4 ft)
9G (0-2 ft)
6C (0-2 ft)
2 IE- IF (0-2 ft)
Area
NBA
NBA
NBA
NBA
NBA
NBA
NBA
NBA
NBA
NBA
NBA
NBA
NBA
NBA
NBA
NBA
NBA
NBA
NBA
NBA
NBA
NBA
NBA
SBA
SBA
SBA
SBA
SBA
SBA
SBA
SBA
SBA
SBA
SBA
SBA
SBA
SBA
SBA
SBA
SBA
SBA
SBA
SBA
SBA
Total
Mg/g
434
NA
128
879
443
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
349
NA
NA
311
1010
511
4523
16
5
26
5
233
110
171
57
3
722
35
132
3
41
131
99
158
368
89
18
26
DI-WET
Mg/L
<6.02
NA
7
7.8
8.1
10
10
12
J4.6
15.2
16.3
16.9
17.8
20.7
22.4
24.9
28.4
28.6
34.6
38.2
45.6
68.8
no
10
10
10
10
11.7
12.8
13
14
14.6
16
18
20
21
22
23
27
31.1
37
44.8
147
227
Leachable
Concentration
NA
NA
70
78
81
100
100
120
146
152
163
169
178
207
224
249
284
286
346
382
456
688
1100
100
100
100
100
117
128
130
140
146
160
180
200
210
220
230
270
311
370
448
1470
2270
Beneficial
Reuse
50
50
50
50
50
50
50
50
50
50
50
50
50
50
50
50
50
50
50
50
50
50
50
50
50
50
50
50
50
50
50
50
50
50
50
50
50
50
50
50
50
50
50
50
Required
Protection
NA
NA
1
2
2
2
2
2
3
3
3
3
4
4
4
5
6
6
7
8
9
14
22
2
2
2
2
2
3
3
3
3
3
4
4
4
4
5
5
6
7
9
29
45
*A11 results obtained using California WET, except B1-SHPBS2, which was analyzed using TCLP.
NA = not analyzed.
Source: ESE.
P/SHARPE/OU2ROD.V.49
06/27/95
48
-------
Values posted below "Required Protection" represent the factor of attenuation
required to protect the beneficial use levels in groundwater. The CVRWQCB has
stated that factors appropriate for SHARPE are 100 for lead and 10 for chromium.
Based on this, a total of three lead and four chromium samples represent a threat to
the beneficial use of groundwater.
The CVRWQCB considers the above method to be a reasonable indicator to determine
if soils have the potential to degrade groundwater. SHARPE considers the test too
conservative, as the severe mixing conditions employed in the DI-WET test are not
representative of environmental conditions. The method by which SHARPE intends
to protect groundwater is specified in Sec. 9.1.4.
6.0 SUMMARY OF SITE RISKS
The purpose of conducting a baseline risk assessment for a contaminated site is to
determine if remedial action is required based on the magnitude of potential human
and ecological risks associated with exposure to a site. In other words, the baseline
risk assessment serves as the baseline indicating what risks could exist if no action
were taken at a site. For SHARPE, a baseline risk assessment was conducted on
residual contamination present in soils at the North Balloon Area, Central Area, and
South Balloon Area to determine if these soils require remedial action. Both human
health risks and ecological impacts are evaluated in the baseline risk assessment for
SHARPE (ESE, 1994b).
Because SHARPE is a Superfund Site, the baseline risk assessment is conducted based
on the methods presented in the EPA Risk Assessment Guidance for Superfund
(RAGS) (EPA, 1989a and b; EPA, 1991a and b) to address both potential human and
ecological exposures to site soils. In addition, applicable relevant supplements to EPA
RAGS were used, as were relevant Regional EPA (i.e., Region IX) and State risk
assessment guidance (DTSC, 1992). The baseline risk assessment consists of the
following five primary components, each of which are described in the following
sections:
1. Identification of chemicals of potential concern;
2. Exposure assessment;
3. Toxicity assessment;
4. Risk characterization; and
5. Development of cleanup criteria.
P/SHARPE/OU2ROD.R1
10/09/95 49
-------
The assessments for the human and ecological risk assessment are addressed
separately under each risk assessment component.
6.1 IDENTIFICATION OF COCs
The primary objectives of this component are to summarize data collected during the
RI and identify COCs. Site-specific risks for each COC are discussed in the risk
assessment. COCs are chemicals detected at the site at levels significantly higher than
naturally occurring levels. To identify COCs, the data are evaluated to ensure that
chemicals were excluded from the risk assessment if they are determined to be
unrelated to the site. Evaluation of current and future land use is also important in
evaluating COCs in the risk assessment, as land use will determine areas and media to
be included for risk evaluation (e.g., surface soils for residential exposure).
Chemicals that are not COCs must meet the following criteria:
1. Chemical is representative of background conditions (not related to the
site); and
2. Chemical is introduced into a sample as part of the sample preparation and
analysis procedures in the lab, and thus is not due to the site.
The principle product of COC selection is a list of COCs and concentrations in each
medium (e.g., soil) for each area studied (i.e., North Balloon Area, Central Area,
and South Balloon Area).
6.1.1 CURRENT AND FUTURE LAND USE AT SHARPE
Currently SHARPE is being used for storage and maintenance of military equipment;
this use is expected to remain in its current land use pattern (industrial) for the
foreseeable future. No known DLA plan exists to sell or change the current use of
SHARPE. Offpost areas are expected to continue in current land use patterns
including residential, agricultural, and light industrial, based on projected regional
growth patterns through 1995. Onpost residents consist only of military personnel and
their families residing in the northern and north-central areas of the North Balloon
Area (Zone 1, Fig. 6-1). The entire site is fenced, with security guards at both the
north and south gates. In addition, DLA security personnel regularly patrol the site
for unauthorized activity.
Military personnel are usually assigned to SHARPE for relatively brief tours of duty.
As a result, demographic information on residents occupying onpost housing may
change significantly from year to year (ESE, 1990). Civilian workers live offpost, in
P/SHARPE/OU2ROD.R1
10/09/95 50
-------
n
s
E
D
KEY
SOUTH 8AU.OON AffiA
CtWRAlAREA
NORTH BAliOON AHA - ZONE 1
NORTH BAUOON-ASEA - ZONE 2
NORTH BAI100N AfltA - Zdt 2o
Figure 6-1
Exposure Assessment Study Areas and Zones
_jmiill-UL_!l»», IMii SHAD. »87. ,
RECORD OF DECISION
SHARPE SITE, LATHROP, CALIFORNIA |
U 5 Army Environmental CcnUr
Atierdsin Proving Ground, florylend
-------
either single-family homes in the small community of Lathrop, in a few apartment
complexes, or in the farm households scattered around the depot. The human
population located west of the site consists primarily of two housing subdivisions
located southwest of SHARPE across Lathrop Road, housing located on the farmland
on the west side of the depot, and a small group of people living in homes located
west of the northwest corner of the SHARPE across Roth Road. Additional houses are
located to the south and west along Harlan and Lathrop Roads. The 1990 U.S. Census
reports show the total residential population of Lathrop to be about 7,000. Census
information confirms that the land use in the region is primarily agricultural. The land
use pattern in the region is not expected to change significantly in the near future.
6.1.2 COCs AND MEDIA OF CONCERN
Generally, 0 to 2 ft is used for characterizing risks to surface soil, as this depth
typically represents soils that would be included in exposure pathways. However,
because the exposed surface areas at SHARPE have been routinely plowed, worked
with heavy equipment, and leveled, mixing of the upper regions of the soil has
occurred. Thus, based on the evaluation of the analytical data and land use conditions,
the primary media of concern is surface soils designated as 0 to 5 ft-bls and fugitive
dust. The COCs detected in this medium are summarized in Table 6-1 for the three
onpost areas of concern.
6.2 EXPOSURE ASSESSMENT
The exposure assessment is the most critical component of a baseline risk assessment,
because this is where populations or subpopulations (e.g., children), exposure
pathways, and the magnitude of exposure to these populations are identified.
6.2.1 POTENTIALLY EXPOSED POPULATIONS
6.2.1.1 Human Populations
The human receptor population under current land use conditions includes the workers
at the facility performing the maintenance and supply missions in the North Balloon
Area, Central Area, and South Balloon Area. Army personnel and families (i.e.,
adults and children) residing in the North Balloon Area, which includes the
Administration and Housing Area (AHA), are also potential receptors. Military
personnel are usually assigned to SHARPE for brief tours of duty [i.e., 2 to 3 years
in duration (SJCPD, 1987)].
P/SHARJPE/OU2ROD.R1
10/09/95 52
-------
Table 6-1. Summary of COCs in Soil and Air for the North Balloon Area, South Balloon Area, and
Central Area of SHARPE
coc
North
Balloon
Soil Air*
Central Balloon
Soil Air
South Balloon
Soil Air
Organic Chemicals
Anthracene (ANTRC)
Benzo(a)anthracene (BAANTR)
Benzo(k)fluoranthene (BKFANT)
Bis(2-ethylhexyl)phthalate
(B2EHP)
Benzene (C6H6)
Carbon tetrachloride (CCL4)
Chlorobenzene (CLC6H5)
Chloroform (CHCL3)
Chrysene (CHRY)
Ethylbenzene (ETC6H5)
Dichlorobenzene (DCLB)
Dichlorodifluoromethane (CCL2F2)
Di-N-octylphthalate (DNOP)
1,1,1-Trichloroethane (111TCE)
1,1-Dichloroethene (11DCE)
1,1-Dichloroethane (11DCLE)
1,2-Dimethylbenzene (12DMB)
1,3-Dichlorobenzene (13DCLB)
1,3-Dimethylbenzene (13DMB)
Fluoranthene (FANT)
Methylene chloride (CH2CL2)
Phenanthrene (PHANTR)
Pyrene (PYR)
1,1,2,2-Tetrachloroethane
(TCLEA)
Tetrachloroethene (TCLEE)
Toluene (MEC6H6)
trans-1,2-Dichloroethene
(T12DCE)
Trichloroethylene (TRCLE)
Xylene (XYLEN)
Vinyl chloride (C2H3CL)
NS
NS
cs
cs
cs
cs
cs
cs
cs
cs
cs
cs
cs
cs
cs
cs
cs
cs
cs
cs
cs
cs
CA
ss
ss
ss
ss
ss
ss
CA
SA
SA
SA
SA
SA
SA
CA
SS
SS
ss
SA
CA
SS
SS
SA
SA
SA
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53
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Table 6-1. Summary of COCs in Soil and Air for the North Balloon Area, South Balloon Area, and Central
Area of SHARPE (Continued, Page 2 of 2)
coc
Inorganic Chemicals
Aluminum (AL)
Antimony (SS)
Arsenic (AS)
Barium (BA)
Beryllium (BE)
Calcium (CA)
Cadmium (CD)
Chromium (CR)
Copper (CU)
Iron (FE)
Lead(PB)
Potassium (K)
Magnesium (MG)
Manganese (MN)
Molybdenum (MO)
Nickel (NI)
Silver (AG)
Sodium (NA)
Thallium (TL)
Vanadium (V)
Zinc (ZN)
Pesticides
Bromacil (BRMCIL)
Chlordane (CLDAN)
DDD(PPDDD)
DDE (PPDDE)
DDT (DDT)
Dieldrin (DLDRN)
beta-HexachlorocycIobexane
(BBHC)
Undone (UN)
Monuron (MONRN)
NS - North Balloon surface soil.
CA = Central Area air.
North
Balloon
Soil Air*
NS
NS !
NS
NS
NS
NS
NS
NS
NS
NS '
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
SS =
SA =
Central Balloon
Soil Air
CS
CS
CS
CS
CS
CS
CS
CS
CS
CS
CS
CS
CS
CS
CS
CS
CS
CS
CS
CS
South Balloon surface soil.
South Balloon air.
South Balloon
Soil Air
SS
SS
SS
SS
SS
SS
SS
SS
SS
SS
SS
SS
SS
SS
SS
SS
CS «> Central Area surface soil.
*None of the air samples had contamination after being corrected for blank concentrations.
P/SHARPE/OU2ROD.V.11
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Onsite workers are either onpost personnel living in the housing in the North Balloon
Area or civilians living offpost. Potential subpopulations of concern include the
children of onsite workers, who may visit the site with their parents. Based on the
nature of contamination, exposure of offpost populations to onsite soils is only a
potential pathway for residential children living near the North Balloon Zone 1 who
may trespass to use the track in one North Balloon area. The offpost populations of
potential concern are a function of future exposure to groundwater, which is
addressed as a separate OU.
6.2.1.2 Wildlife Populations
Because of the high degree of land development and management within and adjacent
to SHARPE, natural resources are limited; therefore, the area does not support a
great diversity of wildlife. Wildlife present at SHARPE are animals that can live on
extremely limited resources within SHARPE boundaries or adjacent agricultural
resources and marginal natural areas. Thus, the ecological risk assessment focuses on
a limited number of species which may come into contact while in transit to viable
habitats. These species include black-tailed jackrabbit, mice, burrowing owl, crop
plants, and cattle. No endangered plants or animals are currently found at SHARPE.
There are several species of animals listed by the U.S. Fish and Wildlife Service
(USFWS) as endangered and by the State of California as threatened in areas near the
SHARPE installation, but not on the installation. Candidate species for listing may
potentially occur in the vicinity of SHARPE. However, due to the lack of suitable or
critical habitats on the installation, endangered species or candidate species are
unlikely to occur at SHARPE.
6.2.2 EXPOSURE PATHWAYS
An exposure pathway is the path whereby a chemical from a contaminated area comes
into contact with a potential receptor (i.e., a worker, resident, or animal). An
exposure pathway is complete only when the potential exists for a receptor to come
into contact with contaminated areas of the site. Based on a review of the data,
several areas were identified as areas where receptors could come into contact with
contaminated soils and include:
1. North Balloon Area soils, north of Holly St. (Zone 1);
2. North Balloon Area soils, south of Holly St. (Zone 2);
3. North Balloon Area soils near Bldgs. T-40 and T-67 within Zone 2
(Zone 2a);
P/SHARPE/OU2ROD.R1
10/09/95 55
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4. Central Area soils; and
5. South Balloon Area soils.
These areas are identified in Fig. 6-1.
Once a receptor comes into contact with contaminated soils, exposure does not occur
unless there is a route by which the soil enters the body. Thus, based on the type of
land use at the site, the means by which the contaminated soils can enter a human or
ecological receptor's body are incidental ingestion, dermal contact, and inhalation of
dusts and vapors.
A summary of the of the human and wildlife exposure pathways included for further
risk analysis are listed in Table 6-2.
6.2.3 EXPOSURE CONCENTRATIONS
Exposure concentrations are concentrations of chemicals that a potential receptor may
come into contact with. For the soils risk assessment, the chemical concentrations of
concern are the levels detected in surface soil at the North Balloon Area, Central
Area, and South Balloon Area. To estimate how much of a chemical a human or
ecological receptor may be exposed to, the monitoring data for each area of concern
was used to determine the maximum concentration detected at the area, or the upper
95 percent confidence limit of the mean. Based on EPA RAGS, the lowest of the two
values was used to calculate exposure for both human and ecological risk
characterization.
6.2.4 ASSUMPTIONS USED TO CALCULATE CHEMICAL EXPOSURE
The degree of chemical exposure to a receptor is a function of exposure frequency
and duration. Therefore, in order to determine the frequency and duration of chemical
exposure, it is important to understand the type of activities that occur at the site (i.e.,
work or play activities) as well as the behaviors and duration associated with these
activities. For the SHARPE soil risk assessment, chemical exposure was determined
using exposure equations presented in EPA risk assessment guidance and using site .
monitoring data and site-specific exposure factors associated with worker, child
recreational, and residential activities.
To calculate worker exposure, it was assumed that a worker weighs 70 kilograms and
works 250 days per year for 25 years at the North Balloon Area, Central Area, and
P/SHARPE/OU2ROD.R1
10/09/95 56
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Table 6-2. Summary of Human Exposure Pathways to COCs in Soil and Air for the North
Balloon Area, South Balloon Area, and Central Area of SHARPE
Scenario
Applicable
Sites
Dust
Inh. Ing.
Soil
Derm.
Current Recreational
Current Residential
Current Worker
North Balloon '
Pesticide Area (2a)
North Balloon
North of Holly St (1)
North Balloon
North of Holly St. (1)
North Balloon
South of Holly St. (2)
Central Area
South Balloon
x
x
x
x
x
Wildlife Exposure*
North Balloon (1)
North Balloon (2)
North Balloon (2a)
Central Area
South Balloon
x
x
X
X
X
* Includes rodents, birds, livestock, and crop plants.
inn — inhalation.
ing = ingestion.
derm = dermal.
P/SH ARTC/OU2ROD .V. 12
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South Balloon Area. Workers are expected to incidentally ingest 50 mg of soil per
day; to come into contact with soil through skin on the forearms, hands, and face;
and to inhale contaminated dust during work activities.
For child recreational exposure, it was assumed that a worker's child will play outside
Bldgs. T-40 and T-67 in pesticide-contaminated soils. The child is assumed to weights
15 kilograms, and may visit the building with a parent on 50 days over 3 years.
Children are expected to incidentally ingest 200 mg of soil per visit and come into
contact with soil through skin on the arms, hands, face and legs.
For child and adult residents living in the onpost housing in the North Balloon Area
(Zone 1), it was assumed that residents will come into contact with soil on 350 days
over 3 years. Residents are expected to incidentally ingest soil during residential
activities and come into contact with soil through skin.
6.3 TOXICITY ASSESSMENT
6.3.1 HUMAN TOXICITY ASSOCIATED WITH COCs
The toxicity assessment describes the potential harmful effects associated with
exposures to COCs. Based on experimental evidence of exposure consequences, a
chemical is classified as either a carcinogen or a noncarcinogen. Carcinogens are
further classified into groups A through E by EPA based on the weight of evidence on
the chemical to cause human cancer. A summary of the lexicological properties
referred to as a toxicity profile is included in the risk assessment (ESE, 1994b). Each
COC profile summarizes the health effects associated with exposure. In addition, the
COC toxicity criteria values (reference doses for noncarcinogens and cancer slope
factors for carcinogens) are identified from the most current EPA sources such as the
Integrated Risk Information System, Health Effects Assessment Summary Tables, and
other relevant databases or documents.
Cancer slope factors have been developed by the EPA Carcinogenic Assessment
Group for estimating excess lifetime cancer risks associated with exposure to
potentially carcinogenic COCs. Cancer slope factors, which are expressed in units of
(mg/kg/day)-l, are multiplied by the estimated intake of a potential carcinogen to
provide an upper-bound estimate of the excess lifetime cancer risk associated with
exposure at that intake level. The term "upper-bound" reflects the conservative
estimate of the risks calculated from the cancer slope factor to ensure that actual
cancer risks are not underestimated. Cancer slope factors are derived from the results
P/SHARPE/OU2ROD.R1
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of human epidemiological studies or chronic animal studies to which extrapolations
are made to humans using uncertainty factors.
Reference doses have been developed by EPA for indicating the potential for adverse
affects from exposure to COCs exhibiting noncarcinogenic effects. They are expressed
in units of mg/kg/day, and are estimates of lifetime daily exposure levels for humans,
including sensitive individuals. Estimated chemical intakes are compared to reference
doses to determine if adverse effects may result from exposure to COCs at the site.
Reference doses are derived from human epidemiological studies or chronic animal
studies to which extrapolations are made to humans using uncertainty factors. These
uncertainty factors help ensure that the reference doses will not underestimate the
potential for adverse noncarcinogenic effects to occur.
The toxicity criteria used for calculating human health risks are summarized in
Table 6-3.
6.3.2 ECOLOGICAL TOXICITY ASSOCIATED WITH COCs
Reference concentrations similar to those identified for human risk characterization
are used to evaluate risks to wildlife. The reference concentrations, also referred to as
ecotoxicity benchmarks, are either concentrations derived from field studies to
measure adverse ecological effects (e.g., acute and chronic aquatic and/or
soil/sediment toxicity tests) or concentrations obtained in laboratory studies which
evaluate a variety of endpoints (e.g., lethal concentrations in which 50 percent of the
exposed population dies, maximum acceptable toxicant concentrations, lowest
observed effect level, no observable effect level, etc.). Ecotoxicity benchmarks that
are relevant to the wildlife observed at the site were identified. The ecotoxicity
criteria for calculating ecological risks are summarized in Table 6-4.
6.4 RISK CHARACTERIZATION
6.4.1 METHODS FOR HUMAN RISK CHARACTERIZATION
Risk characterization, the final step in the baseline risk assessment process, integrates
and summarizes the toxicity and exposure assessment information to produce
quantitative risks associated with exposure to site contaminants. To characterize the
potential carcinogenic effects, probabilities that an individual will develop cancer over
a lifetime of exposure are estimated. Excess lifetime cancer risks are determined by
multiplying the intake level with the cancer slope factor. These risks are probabilities
that are generally expressed in scientific notation (e.g., 1 x 10"6 or 10E-6). An excess
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Table 6.3. Summary of Toxicity Dose-Response Information Used in the Human Risk Characterization (Page 1 of 2)
Chemical
AN1ONS/CATIONS
Chloride
Nitrate + nitrite
INORGANICS
Aluminum
Antimony
Arsenic
Barium
Scry Ilium
Boron
Cadmium (iclid matrix)
Calcium
Chromium, hexavalent
Chromium, total
Cobalt
Copper
ron
Lead
Magnesium
Manganese (solid matrix)
Molybdenum
Nickel
tiosphorus
totassium
Silver
rhallium
Vanadium
Zinc
PESTICIDES
BHC, (beta)
Jromacil
Chlordane, tout
DDD.pp'
DDE,pp>
DDT.pp'
>ieldrin
jndane
Monuron
Oral RfD (mg/kg/day)
Chronic Subchronic
7.1e + 00
l.Oe-01 l.Oe-01
- -
4.0e-04 4.0e-04
3.0e-04 3.0e-04
7.0e-02 7.0e-02
5.0e-03 5.0e-03
9.0e-02 9.0e-02
l.Oe-03
..
5.0e-03 2.0e-02
l.Oe + 00 l.Oe + 00
-
3.7e-02 3.7e-02
--
-
-
1.4e-01 1.4e-01
5.0e-03 S.Oe-03
2.0e-02 2.0e-02
-
-
5.0e-03 5.0e-03
7.0e-05 7.0e-04
7.0e-03 7.0e-03
3.0e-0l 3.0e-01
3.0e-04 3.0e-03
1.2e-01
6.0e-05 6.0e-05
5.0e-04 5.0e-04
5.0e-04 5.0e-04
5.0e-04 5.0e-04
5.0e-05 5.0e-05
3.0e-04 3.0e-03
l.Oe-02
Inh. RfD (mg/kg/day)
Chronic Subchronic
_ _
-
- -
! _
- -
l.Oe-04 l.Oe-03
-
-
-
_
„
-
_
-
-
_
-
l.le-04 l.le-04
_
_
-
-
_ „
-
_
-
-
-
_
_
_
-
-
-
__ —
Oral CSF Oral Inh. CSF Inh.
(mg/kg/day)- 1 WoE* (mg/kg/day)- 1 WoE*
_
-
- -
-
1.8e + 00 A 5.0e + 01 A
-
4.3e+00 B2 8.4e+00 B2
-
6.U+00 Bl
_
ND 4.1e + 01 A
„
_
-
-
ND B2 ND B2
-
_
_
8.4e-01 A
-
_
-
-
-
_
_
1.8e + 00 C 1.8e + 00 C
-
1.3e+00 B2 1.3e + 00 B2
2.4e-01 B2 2.4e-01 B2
3.4e-01 B2 3.4e-01 B2
3.4e-01 B2 3.4e-01 B2
1.6e+01 B2 1.6e+01 B2
1.3e+00 B2/C ND B2/C
— —
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Table 6.3. Summary of Toxicity Dose-Response Informalion Used in the Human Risk Characterization (Page 2 of 2)
Chemical
POLYCYCLIC
AROMATIC
HYDROCARBONS
Anthracene
Benz(a)anirhacene
Benzo(k)ftionnthene
ChrvKne
Fluoraahene
Phemoduene
Pyrene
MISCELLANEOUS
SEMIVOLATILE
ORGAN1CS
Bis(2-cthylhexyl)phthalale
Dichlorobenzene, 1,3-
iichlorobenzenet, total
Di-D-ocryl pbthalate
MISCELLANEOUS
VOLATILE
ORGAN1CS
ienzene
Carbon letrachloride
CbJorobeazene
Zblonnonn
Dichtondifluoromethane
>ichlorocth»ne, 1,1-
DkhJoroethene, 1,1-
Dichloroethene, trans-1,2-
SthyBwnzene
lieshyiene chloride
TetncUcnoethane, 1,1,2,2-
"etzacfaioroethene
Toluene
rricUofoethane, 1,1,1-
"richioroethene
Vinyl chloride
Xyiene, m-
Cykne, o-
Xyieaet, total
Oral RfD (mg/kg/day)
Chronic Subchronic
3.0e-01 3.0e+00
3.0e-02 3.0e-01
3.0e-02 3.0e-01
3.0e-02 3.0e-01
4.0e-02 4.0e-01
3.0e-02 3.0e-01
3.0e-02 3.0e-01
2.0e-02 2.0e-02
_
9.0e-02 9.0e-01
2.0e-02 2.0e-02
2.0e-02
7.0e-04 7.0e-03
2.0e-02 2.0e-01
l.Oe-02 l.Oe-02
2.0e-01 9.0e-01
l.Oe-01 l.Oe + 00
9.0e-03 9.0e-03
2.0e-02 2.0e-01
l.Oe-01 l.Oe + 00
6.0e-02 6.0e-02
-
l.Oe-02 l.Oe-01
2.0e-01 2.0e+00
9.0e-02 9.0e-01
6.0e-03
-
2.0e+00 4.0e+00
2.0e+00 4.0e + 00
2.0e+00 4.0e + 00
Inh. RfD (mg/kg/day)
Chronic Subchronic
- -
-
-
-
- -
- -
-
_
_
4.0e-02 4.0e-01
- -
- -
-
5.0e-03 5.0e-02
_
5.0e-02 5.0e-01
l.Oe-01 l.Oe + 00
_
_
2.9e-01 2.9e-01
8.6e-01 8.6e-01
-
_
l.le-01 5.7e-01
3.0e-01 3.0e + 00
-
-
2.0e-01 l.Oe-t-00
2.0e-01 l.Oe+00
8.6e-02 8.6e-02
Oral CSF Oral Inh. CSF Inh.
(mg/kg/day)-l WoE» (mg/kg/day)-l WoE»
- -
7.3e-01 B2 6.1e-01 B2
7.3e-01 B2 6.1e-01 B2
7.3e-02 B2 6.1e-02 B2
„
- -
- -
1.4e-02 B2 ND B2
_
2.4e-02 C ND C
-
2.9e-02 A 2.9e-02 A
1.3e-01 B2 5.3e-02 B2
_
6.U-03 B2 8.1e-02 B2
-
ND C ND C
6.0e-01 C 1.2e + 00 C
„
-
7.5e-03 B2 1.6e-03 B2
2.0e-01 C 2.6e-02 C
S.le-02 B2 1.8e-03 B2
-
-
l.le-02 B2 1.7e-02 B2
1.9e+00 A 3.0e-01 A
-
_
-
* WoE " EPA weighl-of-evidence of oral carcinogenicity for classifying compounds as a human carcinogen via ingestion.
A * Human carcinogen (sufficient evidence from epidemiologic studies).
BI * Probable human carcinogen (limited evidence from epidemiologic studies).
K. = Probable human carcinogen (sufficient evidence in animals and inadequate evidence in humans).
C ' Possible human carcinogen Gimited evidence of carcinogenicity in animals in the absence of human data).
D = Not classifiable as to human carcinogenicity.
Source: ESE.
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06/27/95
61
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Table 6-4. Compound-Specific Ecotoxieity Benchmark! for Terrestrial Organisms
COMPOUND
1,1.1-TRICHLOROETHANE
1.1.2.2-TETRACHLOROETHANE
1,1-DICHLOROETHYLEKE
1,1-DICHLOROETHANE
1,3-DlCHLOROBENZENE
1,2-OIKETHYLBENZENE
XYLENE*
ALUHINUN
ANTHRACENE
ANTIMONY
ANTIMONY
ARSENIC
BARIUM
BARIUM
BARIUM
BARIUM
BENZENE
BEU20 (A) ANTHRACENE
BEH20 (K) FLUORANTHENE
BISC2-ETHYLHEXYLJPHTHALATE
BIS(2-ETHYLHEXYL)PHTHALATE
B1S(2-ETHYLHEXYL)PHTHALATE
B1S(2-ETHYLHEXYL)PHTHALATE
BROMACIL
BROHAC1L
BROMACIL
BROHACIL
CADMIUM
CADMIUM
CHLORDANE
CHLORDANE
CHLORDANE
CHLOROBENZENE
CHLOROBENZENE
CHLOROBENZENE
CHLOROBENZENE
CHLOROFORM
CHLOROFORM
CHROMIUM
CHROMIUM
CHROMIUM
CHROMIUM VI
CHRYSENE
COBALT
COBALT
COPPER
COPPER
COPPER
ODD
DDO
ODD
DOE
SCIENTIFIC NAME
Rattus rattus
Hus spp.
Rattus rattus
Rattus rettus
Rattus rattus
Rattus rattus/Hus sg.
Rattus rattus/Hus sg.
Callus eallus
MUS Sp..
Rattus rattus
Cam's fami'liaris
Hesocricetus auratus
Rattus rattus
Rsttus rattus
Coh'nus virginianus
Canis familiaris
Rattus rattus
Rattus rattus
Hus spp.
Rattus rattus
Bos bovis
Bos bovis
Sturnus vulgaris
Canis familiaris
Canis fami iiaris
Rattus rattus
Rattus rattus
Rattus rattus
Rattus rattus
Canis familiar™
Svlvilagus SPP.
Rattus rattus
Rattus rattus
Callus gall us
Rattus rattus
Ovit a ires
Sus scrofa
Colinus virainianus
Coturnix japonica
Phasianus celehieus
Annus platvrhvnehos
COMMON NAME
RAT
MOUSE
RAT
RAT
RAT
Rats/Mice
Rats/Mice
CHICKEN
RODENT
SMALL MAMMALS
SHALL MAHMALS
MOUSE
DOG
MOUSE
RABBIT
RAT
RAT
RODENT
RODENT
DOG
HAMPSTER
RAT
RAT
BDBUHITE QUAIL
DOG
RAT
RAT
MOUSE
RAT
CALF
CATTLE
STARLING
DOG
DOG
RAT
RAT
RAT
RAT
DOG
RABBIT
RAT
EARTHWORM
RODENT
CHICKEN
RAT
LAMB
PLANTS
SWINE
BOBWHITE QUAIL
JAPANESE QUAIL
RING NECKED PHEASANT
MALLARD
62
TEST
CHRONIC
CHRONIC
CHRONIC
ACUTE
ACUTE
ACUTE
ACUTE
ACUTE
ACUTE
ACUTE
CHRONIC
CHRONIC
ACUTE
CHRONIC
ACUTE
ACUTE
CHRONIC
CHRONIC
ACUTE
CHRONIC
CHRONIC
CHRONIC
CHRONIC
ACUTE
CHRONIC
CHRONIC
EFFECT
LOAEL
NOEL
NOAEL
NOAEL
LC50
LC50
LLD
LLD
LLD
LD50
NOEL
NOEL
NOEL
NOEL
LD50
LC50
NOAEL
LD50
LOAEL
NOEL
NOEL
DEATH
LOAEL
NOEL
LOAEL
LD50
NOEL
LC50
LC50
LC50
(XWC.
750
282
9
115
200
250
250
1400
3300
11
4000
40
90
70
170
118
1
2
72
60
250
400
26000
10000
31
5200
650
2
0
10
75
150
55
27
50
3400
30
60
100
2
1000
10
99
50
30
27
150
250
2178
3165
445
4
UNIT
MG/KG
MG/KG
MG/KG
HG/KG
MG/KG
MG/KG
PPM
MG/KG
MG/KG
MG/KG
HG/KG
MG/KG-B
MG/KG-B
MG/KG-B
MG/KG-B
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
PPM
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
HG/KG
MG/KG
MG/KG
MG/KG
HG/KG
HG/KG
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
MG
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
-------
Table 6-4. Compound-Specific Ecotoxicity BenchMrkf for Terrestrilt Organisms (Continued.
Page 2 of 2)
COMPOUND
DOT
DDT
•ttT
IT
JT
DIOU.OROBEN2ENE
01CHLOROBENZENE
01ELORIN
01ELDR1N
DIELORU
01ELORIH
nilYLBENZENE
flUDRAHTHENE
IRON (FERROUS SULFATE)
IRON (FERROUS SULFATE)
IRON (FERROUS SULFATE)
UAD
LEAD
LEAD
LEAB
LIB) AXE
MAGNESIUM
MANGANESE
MOLYBDENUM
MOLYBDENUM
MOLYBDENUM
MOLYBDENUM
MOLYBDENUM
NICKEL
SvtvUaaus see.
Callus eallus
Mus too.
Pieea too.
Bos bovis
Rattus rattus
OvU a ires
Sus terefa
Rattus rattus
Rattut rattus
Mus tee./Svlvttaaus tec.
Rattus rattus
Sus ierefa
COMMON NAME
PHEASANT
BOBUHITE QUAIL
CHICKEN
DOMESTIC FOUL
DOMESTIC FOUL
RAT
RATS/MOUSE
CATTLE
CHICKS
SHARP-TAILED GROUSE
SHEEP
RAT
ACUTE LDSO
GUINEA PIG
MOUSE
RAT
MOURNING DOVE
MOUSE
PLANTS
PLANTS
JAPANESE QUAIL
DOG
CATTLE
CATTLE
CATTLE
CATTLE
RABBIT
RABBIT
RAT
RAT
RAT
RODENT
MOUSE
RABBIT
RODENT
CHICKS
CROP PLANTS
MOUSE
NEHATODE
SPRUCE
CALF
HORSE
RAT/MOUSE/KAMSTER
RAT
MOUSE
RABBIT
CABBAGE
LAMB
PIG
RAT
RAT
MICE/RABBITS
MICE/RATS/RABBITS
RAT
PIG
PLANTS
PLANTS
TEST
NOAEL
NOAEL
ACUTE
2000 MG/KG
ACUTE
ACUTE
ACUTE
CHRONIC
CHRONIC
ACUTE
CHRONIC
CHRONIC
CHRONIC
CHRONIC
CHRONIC
CHRONIC
ACUTE
ACUTE
ACUTE
CHRONIC
CHRONIC
CHRONIC
CHRONIC
ACUTE
CHRONIC
ACUTE
ACUTE
ACUTE
ACUTE
ACUTE
CHRONIC
EFFECT
LC50
LC50
LC50
LDSO
LDSO
LDSO
LDSO
LDSO
LDSO
LDSO
LOEL
NOEL
LDSO
NOAEL
•
LCSO
LC50
CONC.
311
611
300
500
700
200
66
25
20
7
25
3SOO
1200
979
319
72
7
125
400
425
230
2
20
2
141
100
1000
50
5
20
700
383
3015
99
50
1000
1050
0
uoo
0
0
15
223
2400
7330
2500
200
200
1
10
113000
500
150000
1000
180
3000
UNIT
MG/KC
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
NG/KG
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
PPM
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
MG/KG
PPM
PPM
PPM
MG/KG
MG/KG
MG/KG
Source: ESE
•DTE: • • Uses sane benchmark as
12DMB
63
-------
lifetime cancer risk of 1 x 10"6 indicates that, as a plausible upper bound, an
individual has a one in one million chance of developing cancer as a result of
site-related exposure to a carcinogen over a 70-year lifetime under the specific
exposure conditions at a site.
The magnitude of acceptable cancer risk relative to Superfund site remediation goals
in the NCP generally ranges from 10"4 to 10"6 (one-in-one million) depending on the
site, proposed usage, and chemicals of concern. Within this range, the level of risk
that is considered to be acceptable at a specific site is a risk management decision and
is decided on a case-specific basis. The acceptability of a particular level of risk is the
province of risk management, where the quantitative estimates of risk are just one of
many factors considered in the decision-making process. A cancer risk of 10"4 is not a
de facto decision point, nor is it a "target" risk level. However, it is generally
accepted that risks above this range require attention. The one-in-one million level of
risk (expressed as 10"*) is often referred to as the de minimus level of risk. However,
DTSC has not endorsed 10"6 as a universally acceptable level of risk.
Potential concern for noncarcinogenic effects of a single contaminant in a single
medium is expressed as the hazard quotient (HQ) or the ratio of the estimated intake
derived from the contaminant concentration in a given medium to the contaminant's
reference doses. By adding the HQs for all contaminants within a medium or across
all media to which a given population may reasonably be exposed, the Hazard Index
(HI) can be generated. The HI provides a useful reference point for gauging the
potential significance of multiple contaminant exposures within a single medium or
cross media. An HI exceeding 1 indicates that the potential exists for adverse health
effects to an individual.
6.4.2 METHODS FOR ECOLOGICAL RISK CHARACTERIZATION
A Phase I screening risk analysis was conducted for addressing ecological risks. A
Phase I screening involves comparing ecotoxicological benchmarks and potential
exposure concentrations for each species of concern. The potential for adverse effects
to terrestrial organisms is estimated by evaluating the ecotoxicity quotient (EQ),
which is the ratio of the exposure concentration (concentration in soil), to the
ecotoxicity benchmark that has been adjusted for the weight of the species of concern.
Thus, much like an HI calculated for human exposure to noncarcinogens, an EQ is
calculated so that an exceedance of 1 indicates a potential exists for adverse health
effects to an individual.
P/SHARPE/OU2ROD.R1
10/09/95 64
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6.4.3 SUMMARY OF RISKS
A summary of the human and ecological exposure pathways that pose risks above
EPA's cumulative risk level of 1 x 10"4, an HI > 1, and/or an EQ > 1 are presented
in Table 6-5. In addition, a summary of the human risk and HI results are presented
in Tables 6-6 and 6-7, respectively.
Except for Zone 2a (the pesticide building area) of the North Balloon Area, the
human carcinogenic risk and His associated with the different exposure areas (North
Balloon Area, Central Area, and South Balloon Area) were below the cumulative risk
level of 1 x 10^. In Zone 2a, isolated areas of pesticide contamination resulted in
potential worker and child risks of 1.1 x 10~3 and 3.1 x 10"*, respectively, which
exceed the cumulative risk level of 1 x 10"4. In addition, the cumulative His for the
worker and child exposure scenario at this area are 36 and 43, respectively. Both the
cumulative risk and HI at Zone 2a is due to the presence of chlordane, dieldrin,
DDD, DDE, and DDT in soil (Tables 6-6 and 6-7).
For lead and chromium, which are chemicals without established human
dose-response values (e.g., reference doses or cancer slope factors), human health
risks were evaluated using EPA-accepted exposure models or health-based values that
are considered to be protective of human health under standard exposure conditions.
For lead, a potentially carcinogenic COC at SHARPE, risk was assessed using
DTSC's lead exposure model (Leadspread). Based on the lead model, it is determined
that levels of lead exceeding 1,000 mg/kg at the site may pose adverse human health
effects to an industrial worker. As with lead, a health-based value for chromium of
500 mg/kg was determined as a level that should not be exceeded at the site, based on
an evaluation of lexicological studies. In addition to the human health evaluation, lead
and chromium also indicated potential ecological risks based on a comparison of the
concentrations to acceptable ecological health-based values.
Based on the human and ecological risk characterization results, a subset of COCs
may pose unacceptable human health and ecological risks at the site to include
chromium, lead, chlordane, dieldrin, DDD, DDE, and DDT. This subset of
chemicals are referred to as the final COCs.
To provide goals for remedial actions to achieve, the risk assessment results are used
to develop preliminary health-based remediation goals (PRGs). These levels are
residual contaminant concentrations that are not expected to result in unacceptable
P/SHARPE/OU2ROD .Rl
10/09/95 65
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Table 6-5. Summary of Final COCs and Human and Ecological Exposure Pathways Posing Risk Exceedances at SHARPE
Exposure Area Exposure Scenario
Exposure
Pathway
Cum.
Risk
HI
COCs Exceeding
risks or His
COCs
Exceeding
Health-based
Levels
North Balloon Child Recreational
Pesticide Area (2a)
Worker
Zone I
Zone 2
Worker and Child
Residential
Worker
Ingestion & 3.1 x 10"
Dermal
Ingestion & 1.1 x 103
Dermal
Ingestion
Dermal, &
Inhalation
Ingestion
Dermal, &
Inhalation
43
36
Chlordane, dieldrin,
ODD, DDE, DDT
Chlordane, dieldrin,
ODD, DDE, DDT
Chromium, lead
Lead
Central Area
Worker
Ingestion
Dermal, &
Inhalation
Lead
South Balloon Worker
Ingestion
Dermal, &
Inhalation
Lead
P/SH ARPE/OU2ROD-H .R1.1
10/09/95
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Table 6-6. Summary of Health Risks Associated with Soil Exposure at SHARPE
Area
North Balloon
(Zone 1)
North Balloon
(Zone 2)
North Balloon
(Zone 2a)
North Balloon
(Zone 2a)
"Hotspot"
North Balloon
(Zone 2a)
"Hotspot"
Central Area
South Balloon
Scenario
Adult Worker
Lifetime Residential
Adult Worker
Lifetime Recreational
Lifetime Recreational
Adult Worker
Adult Worker
Adult Worker
Media
Dermal
Oral
TOTAL
Dermal
Oral
TOTAL
Dermal
Oral
TOTAL
Dermal
Oral
TOTAL
Dermal
Oral
TOTAL
Dermal
Oral
TOTAL
Dermal
Oral
Inhalation
TOTAL
Dermal
Oral
Inhalation
TOTAL
Risk |[ COCs
1.4E-06
1.5E-06
2.9E-06
1E-06
4.8E-06
5.8E-06
3.1E-05
5.8E-06
3.7E-05
7.4E-06
4.8E-06
1.2E-05
2.0E-04
1.1E-04
3.1E-04
9.4E-04
1.2E-04
1.1E-03
4E-06
1.8E-06
2.7E-06
8.5E-06
1.4E-06
1.4E-06
1.1E-05
1.4E-05
Arsenic, DDT
Arsenic
Arsenic, DDT
Arsenic, DDT
Arsenic, chlordane, DDE, DDT, Dieldrin
Arsenic, chlordane, DDE, DDT, Dieldrin
Arsenic, chlordane, DDE, DDT, Dieldrin
Arsenic, chlordane, DDE, DDT, Dieldrin
Chlordane, DDD, DDE, DDT, Dieldrin
Chlordane, DDD, DDE, DDT, Dieldrin
Chlordane, DDD, DDE, DDT, Dieldrin
Chlordane, DDD, DDE, DDT, Dieldrin
Arsenic, misc. volatile organics
Arsenic
Benzene, methylene chloride
Arsenic, PAHs
Arsenic
Benzene, carbon tetrachloride,
chloroform, tetrachloroethene
PAHs = polycyclic aromatic hydrocarbons.
Source: ESE.
P/SHARPE/OU2ROD.V .4
06/27/95
67
-------
Table 6-7. Summary of Hazard Indices Associated with Soil Exposure at SHARPE
Area
North Balloon
(Zone 1)
North Balloon
(Zone 2)
North Balloon
(Zone 2a)
North Balloon
(Zone 2a)
"Hotspot"
North Balloon
(Zone 2a)
"Hotspot"
Central Area
South Balloon
Scenario
Adult Worker
Adult Residential
Child Residential
Adult Worker
Child Recreational
Child Recreational
Adult Worker
Adult Worker
Adult Worker
Media
Dermal
Oral
TOTAL
Dermal
Oral
TOTAL
Dermal
Oral
TOTAL
Dermal
Oral
TOTAL
Dermal
Oral
TOTAL
Dermal
Oral
TOTAL
Dermal
Oral
TOTAL
Dermal
Oral
Inhalation
TOTAL
Dermal
Oral
Inhalation
TOTAL
HI
0.2
0.3
0.5
0.1
0.1
0.3
0.2
1.2
1.4
0.8
0.2
1.0
0.8
0.5
1.3
28.1
14.5
42.6
31.5
3.8
35.3
0.2
0.3
0.0
0.6
0.02
0.02
0.1
0.1
COCs Contributing to HI > 1
Lead*
Lead*
Thallium, Lead*, Chromium*
Lead*
Chlrodane
Chlordane
ChJordane, DDT
Chlordane, DDT
Chlordane, DDT
Chlordane, DDT
Lead*
Lead*
PAHs »= polycyclic aromatic hydrocarbons.
*lead and chromium exceeded health-based values.
Source: ESE.
P/SHARPE/OU2ROD.V.5
06/27/95
68
-------
health risks under specific land use and exposure assumptions. Using RAGS, a risk
assessment was conducted in reverse for the pesticides to develop PRGs that are based
on acceptable risk levels. The PRGs for pesticides, lead, and chromium were
developed based on an evaluation of toxicological information as well as consultation
with the Regulatory agencies (e.g., EPA and State DTSC) the PRGs established for
the areas of concern are presented in Table 6-8.
7.0 DESCRIPTION OF ALTERNATIVES
The presentation of alternatives has been subdivided into two sections: (1) alternatives
for lead- and chromium-contaminated soils, and (2) alternatives for TCE-contaminated
soils. The Soils FS for SHARPE, which presented the alternatives below, was
accepted by EPA and the State of California in December 1994. Table 6-8 presents
PRGs based on the RA. Final cleanup standards are presented in Sec. 9.0.
Alternatives for the remediation of pesticide-contaminated soils were not developed in
the FS. As previously stated, these soils were remediated as a non-time critical
response action, under the authority of a Removal Action Memorandum (ESE 1994).
This removal action was completed in March 1995.
Sites which were recommended for NFA are not included in the Description of
Alternatives or Evaluation of Alternatives sections (7.0 and 8.0, respectively). More
information regarding NFA sites is presented in Sec. 9.3.
7.1 LEAD- AND CHROMIUM-CONTAMINATED SOIL
SHARPE, USAEC, DTSC, CVRWQCB, and EPA have evaluated five remedial
alternatives for lead- and chromium-contaminated soils:
1. Alternative lC--Containment: Asphalt Cap;
2. Alternative 2A~Treatment: Physical/Chemical
Treatment-Fixation/Solidification;
3. Alternative SB-Treatment: Chemical Extraction/Soil Washing;
4. Alternative 4B--Removal and Disposal: Offsite Landfill; and
5. Alternative 5A-No Action: Limit Access/Use Restrictions.
Cleanup Standards
The RA presented PRGs (Table 6-8) for lead, chromium, and five pesticides (DDD,
DDT, DDE, dieldrin, and chlordane) (see Sec. 9.0 for final cleanup standards). As
previously stated, the pesticides were remediated with the removal action at the
P/SHARPE/OU2ROD.R1
10/09/95 69
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Table 6-8. COCs and PRGs to be Evaluated in the ROD for SHARPE Soils (mg/kg)
Area
North Balloon
Zone 1
North Balloon
Zone 2
-j
0 North Balloon
Zone 2a
Central Area
South Balloon
Hot Spot--
Trench 1
Hot Spot~5
coc
Lead
Chromium
Lead
Dieldrin
DDT
DDE
ODD
Chlordane
Chlordane
Dieldrin
DDT
DDE
ODD
Lead
Lead
Lead
UCL,5
4.72E+06
2.26E+05
3.07E+03
1.26E-01
1.64E+01
5.23E+00
9.06E-01
9.78E+00
9.78E+00
4.03E-02
2.62E+01
7.28E+00
8.20E-01
1.34E+04
—
-
Mean
2.04E + 05
1.26E + 04
1.64E + 03
6.23E-02
6.13E + 00
2.I6E+00
3.82E-01
3.34E+00
3.34E + 00
2.34E-02
8.32E+00
2.61E + 00
3.21E-01
2.15E + 02
2.58 E+03
2.26E+04
Maximum
5.75E+03
1.01E+03
4.1IE+03
2.75E-01
I.81E + 02
3.15E + 01
8.14E+00
4.70E+02
4.70E + 02
2.75E-01
1.81E+02
3.15E+01
8.14E+00
3.72E+03
3.99E + 03
2.75E+04
Frequency of
Detection
66/74
53/57
5/6
18/66
50/66
45/66
32/66
49/59
49/59
18/59
50/60
45/59
32/59
6/12
2/2
2/2
PRG
1,000
500
1,000
0.04
2
2
3
1
1
0.04
2
2
3
1,000
1,000
1,000
Basis of PRG
California To be Considered (TBC)
Health-Based Criteria
Hammond TBC Health-Based
California TBC Health-Based
Risk-based
Risk-based
Risk-based
Risk-based
Risk-based
Risk -based
Risk-based
Risk-based
Risk-based
Risk-based
California TBC Health-Based
California TBC Health-Based
California TBC Health-Based
Criteria
Criteria
Criteria
Criteria
Criteria
Source: ESE.
P/SHARPE/OU2ROD-H.RI .13
10/09/95
-------
pesticide management area completed in March 1995. Therefore, cleanup standards
for pesticides are not presented in this ROD.
During the FS, 1,000 mg/kg was selected as the cleanup standard for lead. The
CVRWQCB commented that the 500 mg/kg cleanup standard for chromium was
probably not protective of groundwater, and recommended a level of 300 mg/kg.
Consequently, the cleanup standard for chromium was established at 300 mg/kg. In
summary, the following apply to remedial response actions pertaining to lead- and
chromium-contaminated soils:
Lead Cleanup Standard 1,000 mg/kg
Chromium Cleanup Standard 300 mg/kg
Based on the above cleanup standards, the total volume of lead- and
chromium-contaminated soils above cleanup standards is estimated as 2,825 yd3
(2,085 yd3 in the South Balloon Area and 740 yd3 in the North Balloon Area). The
total area represented by this volume, which should be considered in estimating the
area and volume of soils to be remediated, is 68,050 ft2 (28,150 ft2 in the South
Balloon Area and 39,900 ft2 in the North Balloon Area).
7.1.1 ALTERNATIVE 1C-CONTAINMENT: ASPHALT CAP
Alternative 1C (Asphalt Cap) consists of containment of the contaminated soils.
Containment of soils would be accomplished with the construction of an asphalt cap.
The asphalt cap is the minimum cap design that would be considered. A more
protective cap may be required, depending on waste characteristics. The cap would
prevent worker and child exposure to lead- and chromium-contaminated soil and limit
infiltration of rainfall and stormwater into contaminated areas.
Two caps would be constructed with this alternative, one in the North Balloon Area
and one in the South Balloon Area. Soil from smaller contaminated areas would be
excavated and transported to the larger area, where it would be evenly applied and
covered by the cap. This approach would reduce the number of caps required to
implement this alternative. Soils from smaller contaminated areas would be tested
prior to excavation to ensure that only those soils that do not contain hazardous STLC
levels are excavated and transported to the larger area. If soils are determined to be
P/SHARPE/OU2ROD.R1
10/09/95 71
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hazardous by STLC, they would be transported offsite to an appropriately licensed
waste disposal facility.
This alternative would be compliant with all ARARs:
• 22 CCR Div. 4.5, Chapter 14, Article 14, §§66264.310 -- Closure of areas
with lead and chromium exceeding cleanup standards will involve installation
of a final cover designed and constructed to prevent downward entry of
water, function with minimum maintenance, promote drainage and minimize
erosion, accommodate settling and subsidence, and accommodate lateral and
vertical shear forces generated by the maximum credible earthquake.
• Water Quality Control Plan (Basin Plan) for CVRWQCB -- Defines
beneficial use levels for constituents in groundwater.
• State Water Resource Control Board Resolution No. 88-63, "Sources of
Drinking Water Policy" as contained in the CVRWQCB Water Quality
Control Plan ~ Specifies that with certain exceptions, all ground and
surface waters have the beneficial use of municipal or domestic water use.
• 22 CCR Div. 4.5, Chapter 14, Article 6, §§ 66264.90 et seq. - Detection
monitoring and evaluation monitoring programs for lead and chromium will
be instituted. If monitoring data indicates the beneficial uses of groundwater
are not being protected, corrective action may be required.
The total present-worth cost for this alternative is $388,600; time required to achieve
remedial response objectives is estimated at 2 months.
7.1.2 ALTERNATIVE 2A-TREATMENT:
PHYSICAL/CHEMICAL-FIXATION/SOLroiFICATION
Alternative 2A (Fixation/Solidification) consists of immobilizing contaminants in soils
through the process of fixation/solidification. The objective of this alternative would
be to prevent adult worker exposure to soils with lead and chromium concentrations
in excess of cleanup standards and to limit the mobility of the contaminants present in
soils. All contaminated soil would be excavated and solidified in a portable
solidification unit prior to being replaced in the excavation area.
P/SHARPE/OU2ROD.R1
10/11/95 72
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It is anticipated that a 20- to 25-percent increase in the volume of the soil would take
place as a result of this treatment process. After all contaminated soil is treated, the
solidified soils (consisting of approximately 3,530 yd3) would be replaced in the
excavated area. An asphalt cap would then be constructed to prevent human exposure
to the solidified matrix and to alleviate the infiltration of rainfall and stormwater into
the matrix.
Bench-scale treatability tests would be conducted to select the proper additives and
their relative ratios and to determine the curing time required to set the waste
adequately. Leaching tests and compressive strength tests would be conducted to
determine the integrity of the solidified soils.
The proposed fixation/solidification treatment area would require some site
preparation prior to mobilization of the process components. A temporary holding
area would also be required to store excavated soil awaiting treatment in the
solidification unit. This temporary holding area would be managed to prevent runoff,
wind dispersion, and dermal contact. Any boulders present in the excavated soil
would be removed prior to treatment and pressure-washed for decontamination.
This alternative would be compliant with all ARARs:
• 22 CCR Div. 4.5, Chapter 14, Article 16 - If excavated soils are
determined to be hazardous by characteristic, regulations addressing
environmental performance standards, monitoring, analysis, inspection,
response, reporting, corrective action, and post-closure care for treatment
systems categorized as Miscellaneous Units need to be complied with.
The following ARARs apply to areas where lead- and chromium-contaminated soils
are determined to be a potential threat to water quality:
• Water Quality Control Plan (Basin Plan) for CVRWQCB -- Defines
beneficial use levels for constituents in groundwater.
• State Water Resource Control Board Resolution No. 88-63, "Sources of
Drinking Water Policy" as contained in the CVRWQCB Water Quality
Control Plan ~ Specifies that with certain exceptions, all ground and
surface waters have the beneficial use of municipal or domestic water use.
P/SHARPE/OU2ROD.R1
10/11/95 73
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• 22 CCR Div. 4.5, Chapter 14, Article 6, §§ 66264.90 et seq. - Detection
monitoring and evaluation monitoring programs for lead and chromium will
be instituted with this program. If monitoring data indicates the beneficial
uses of ground water are not being protected, corrective action may be
required.
Through the process of solidification/fixation, this alternative is protective of human
health and environment via treatment.
The total present-worth cost for this alternative is $1,015,000; time to achieve
remedial response objectives is estimated at 8 months.
7.1.3 ALTERNATIVE 2B: CHEMICAL EXTRACTION/SOIL WASHING
Alternative 2B (Chemical Extraction/Soil Washing) for lead- and
chromium-contaminated soils involves excavating soil followed by transportation to a
mobile treatment unit. The objective of this process is to chemically treat lead- and
chromium-contaminated soils to levels below cleanup standards. To accomplish this
objective, contaminated soil would be excavated and chemically treated in a portable
soil washing unit which could be transported from one area of the installation to
another area as needed. After treatment, the soils would be transported to a temporary
soil staging area near the treatment unit. Soils at the staging area would be stored
until an analytical evaluation of the treated soils had been conducted. To minimize
human and environmental exposure, soil stored at the staging area would be covered
by plastic tarps. Covering the treated soils with a tarp would minimize storm water
infiltration and reduce the possibility of dermal contact.
The treated soils from the soil washing unit would retain a high water content;
therefore, the possibility exists for the generation of leachate. Any leachate would be
collected by constructing a series of perforated polyvinyl chloride (PVC) leachate
collection pipes. The leachate collection pipes would be covered with pea gravel and
overlain with a 1-ft layer of free draining sand. Leachate piping would be connected
to a sump which would be sampled and chemically screened for the target parameters.
If the results of soil sampling indicate adequate treatment has not been accomplished,
soil would be reprocessed through the soil treatment unit. After the soil contaminant
concentrations have been verified to be below the cleanup standards, treated soils
would be transported to the excavation site, and the excavation would be backfilled.
P/SHARPE/OU2ROD.R1
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One of three methods of soil washing may be utilized with this alternative. In the first
method, acid is used to solubilize metal ions, followed by settling of soils and a
hydroxide precipitation of the metal. All soil is washed and neutralized before being
returned to the excavation. High clay content soils are unsuitable for this process.
A second method would use a chelating agent, EDTA, to complex metal cations from
solution, and a calcium solution to regenerate the EDTA. The metal and EDTA floe
would float to the top of the slurry. No acid is used in this method.
A third method uses alkaline and surfactants to change interfacial tension of the metal
particles, causing them to floe and float to the surface. High clay content in soil
would hinder the effectiveness of this process.
The chemical extraction/soil washing treatment process is expected to generate a lead
and chromium sludge waste and leachate. The composition of the waste cannot be
predetermined without bench- or pilot-scale tests to determine the optimum treatment
process. However, after these wastes are generated, they would be collected, managed
as hazardous wastes, and transported to a hazardous waste management facility.
Soil excavations would be kept as small as possible. Backfilling would be completed
in 1-ft lifts (or less) and compacted to a pre-defined density. Density testing on every
other lift would be performed to verify the effectiveness of compaction efforts.
This alternative would be compliant with all ARARs:
• 22 CCR Div. 4.5, Chapter 14, Article 16 -- If excavated soils are
determined to be hazardous by characteristic, regulations addressing
environmental performance standards, monitoring, analysis, inspection,
response, reporting, corrective action, and post-closure care for treatment
systems categorized as Miscellaneous Units need to be complied with.
The following ARARs apply to areas where lead- and chromium-contaminated soils
are determined to be a potential threat to water quality:
• Water Quality Control Plan (Basin Plan) for CVRWQCB -- Defines
beneficial use levels for constituents in groundwater.
P/SHARPE/OU2ROD .R1
10/11/95 75
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• State Water Resource Control Board Resolution No. 88-63, "Sources of
Drinking Water Policy" as contained in the CVRWQCB Water Quality
Control Plan - Specifies that with certain exceptions, all ground and
surface waters have the beneficial use of municipal or domestic water use.
• 22 CCR Div. 4.5, Chapter 14, Article 6, §§ 66264.90 et seq, -- Detection
monitoring and evaluation monitoring programs for lead and chromium will
be instituted with this program. If monitoring data indicates the beneficial
uses of groundwater are not being protected, corrective action may be
required.
Through the process of chemical extraction/soil washing, this alternative is protective
of human health and environment via treatment.
A significant level of bench- and pilot-scale testing is required, as this technology is
still considered to be innovative. The total present-worth cost for this alternative is
$1,773,400; time required to achieve remedial response actions is estimated at 8
months.
7.1.4 ALTERNATIVE 4B--REMOVAL AND DISPOSAL: OFFSITE
LANDFILL
The objective of this alternative is to excavate lead- and chromium-contaminated soils
from the North Balloon Area and South Balloon Area such that the residual soil
concentrations do not exceed the respective cleanup standards. The contaminated soils
would be excavated from the site and transported offsite for final disposal.
Prior to excavation of the contaminated soils, any existing pavement, concrete, and
light brush would be removed using a front-end loader. Contaminated debris would be
staged for transportation to an appropriately permitted offsite disposal facility.
Contaminated soils would be excavated from each area using a hydraulic backhoe or
similar equipment. The surface area of the working face would be kept as small as
possible to minimize the release of fugitive dust emissions. Contaminated soils would
be loaded onto 20-yd3 dump trucks. Soils remaining in each excavation pit would be
analyzed for lead and chromium to ensure that contamination in excess of the cleanup
standards was removed and transported to an appropriately licensed offsite landfill.
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Testing would be conducted to determine if any soils were hazardous by
characteristic. If soils were determined to be hazardous by characteristic, the
excavated soils would be disposed of in a Class I facility. If soils were determined to
be non-hazardous, they would be disposed of at a Class II facility.
Approximately 2,825 yd3 of additional soil would be needed to complete backfilling
and to return the affected area to existing grade. This additional soil may be available
from sites at SHARPE and/or from offsite locations. Backfill material would be
placed in 1-ft lifts (or less) and compacted to achieve a predetermined density.
Density testing on every other lift would be performed to verify the effectiveness of
compaction efforts.
No ARARs were identified for the removal and disposal of soils containing lead and
chromium in excess of cleanup standards. The following ARARs apply to areas where
lead- and chromium-contaminated soils are determined to be a potential threat to
water quality:
• Water Quality Control Plan (Basin Plan) for CVRWQCB -- Defines
beneficial use levels for constituents in groundwater.
• State Water Resource Control Board Resolution No. 88-63, "Sources of
Drinking Water Policy" as contained in the CVRWQCB Water Quality
Control Plan — Specifies that with certain exceptions, all ground and
surface waters have the beneficial use of municipal or domestic water use.
• 22 CCR Div. 4.5, Chapter 14, Article 6, §§ 66264.90 et seq. -- Detection
monitoring and evaluation monitoring programs for lead and chromium will
be instituted with this program. If monitoring data indicates the beneficial
uses of groundwater are not being protected, corrective action may be
required.
Through the process of offsite disposal, this alternative is protective of human health
and the environment via engineering controls.
The total present-worth cost for this alternative is $683,000. Time to achieve remedial
response objectives is estimated at 4 months.
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7.1.5 ALTERNATIVE 5A-NO ACTION: LIMIT ACCESS/USE
RESTRICTIONS
Alternative 5A (No Action) for the lead- and chromium-contaminated soils is the
no-action alternative using land access restrictions. This alternative would provide
limited protection of human health and the environment and is included as a baseline
for comparison with other alternatives. A permanent fence (with appropriate warning
signs) would be constructed around the perimeter of each site with levels of lead and
chromium in excess of cleanup standards to prevent access to the sites and to prevent
exposure to contaminated soils.
This alternative involves no action, aside from periodic monitoring and institutional
controls. The following ARARs would not be complied with:
• Water Quality Control Plan (Basin Plan) for CVRWQCB - Defines
beneficial use levels for constituents in groundwater.
• State Water Resource Control Board Resolution No. 88-63, "Sources of
Drinking Water Policy" as contained in the CVRWQCB Water Quality
Control Plan -- Specifies that with certain exceptions, all ground and
surface waters have the beneficial use of municipal or domestic water use.
• 22 CCR Div. 4.5, Chapter 14, Article 6, §§ 66264.90 et seq. -- Detection
monitoring and evaluation monitoring programs for lead and chromium will
be instituted with this program. If monitoring data indicates the beneficial
uses of groundwater are not being protected, corrective action may be
required.
The total present-worth cost for this alternative is $52,000; time to achieve remedial
response objectives is estimated at 1 month.
7.2 TCE-CONTAMINATED SOIL
Five remedial alternatives were evaluated for TCE-contaminated soils:
1. Alternative 2B--Thermal Treatment: Onsite Incineration;
2. Alternative 2C~Physical Treatment: In-Situ Volatilization (ISV)
3. Alternative 3A~Innovative Treatment: Low-Temperature Thermal Stripping
(LTTS);
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4. Alternative 4A~Removal and Disposal: Offsite Landfill; and
5. Alternative 5A—No Action: Limit Access/Use Restrictions.
The RA showed that levels of TCE in soils do not represent a threat to human health
and the environment, given the currently operating groundwater remediation systems.
However, if TCE in soils is left untreated, it will be allowed to leach to groundwater
and likely increase the time required for the actions specified in OU1 to achieve
aquifer cleanup standards. For this reason, remediation of TCE-contaminated soils is
being undertaken.
For the purposes of comparison of alternatives, it was assumed the entire volume of
TCE-contaminated soils (see Sec. 5.1) would require remediation.
The total estimated volume of TCE-contaminated soils to be remediated is estimated
as 73,300 yd3.
7.2.1 ALTERNATIVE IB-THERMAL TREATMENT: ONPOST
INCINERATION
The objective of this alternative is to provide thermal treatment of TCE-contaminated
soils and to reduce TCE concentrations in the ash. The TCE-contaminated soils would
be incinerated onsite using a mobile incinerator. This unit would consist of a rotary
kiln unit with a secondary combustion chamber, packed tower, and jet scrubber. In
general, a 1.5- to 2-acre area would be needed for the incinerator operations, which
would include staging and ash storage areas. The temporary storage area for soils
awaiting incineration would be managed to prevent runoff, wind dispersion, and
dermal contact. Any boulders present in the soil would be removed from the waste
stream and jet washed for decontamination.
Incineration rates would be maintained to ensure appropriate destruction efficiencies
are achieved and to comply with paniculate standards and emission standards and
guidelines. Periodic monitoring of the stack gases would be conducted to ensure
compliance with the emissions standards and guidelines.
Ash would be stored at the incinerator complex until analyses had been completed
which verified that all contaminant concentrations were below pre-defined levels.
Offsite laboratories would be used to provide these analyses. If required contaminant
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removal is not obtained for any ash sample, the corresponding pile would be fed back
into the incinerator for additional treatment.
Upon completion of the incineration operations, the incinerator would be
decontaminated and removed from the site. Wastes generated during decontamination
would be collected and transported to a licensed facility for disposal.
The ash resulting from incineration would be used as backfill in the excavations. It is
anticipated that a 15- to 20-percent volume reduction of the soil would take place as a
result of incineration. Consequently, approximately 14,660 yd3 of additional soils
would be needed to complete backfilling of the excavated areas. These additional soils
may be available from sites at SHARPE and/or from offsite.
No ARARs were identified for the incineration of TCE-contaminated soils (TCE-
contaminated soils are not expected to be hazardous by characteristic). The following
ARARs apply to areas where TCE-contaminated soils are determined to be a potential
threat to water quality:
• Water Quality Control Plan (Basin Plan) for CVRWQCB - Defines
beneficial use levels for constituents in groundwater.
• State Water Resource Control Board Resolution No. 88-63, "Sources of
Drinking Water Policy" as contained in the CVRWQCB Water Quality
Control Plan -- Specifies that with certain exceptions, all ground and
surface waters have the beneficial use of municipal or domestic water use.
• 22 CCR Div. 4.5, Chapter 14, Article 6, §§ 66264.90 et seg. - Detection
monitoring and evaluation monitoring programs for TCE will be instituted
with this program. If monitoring data indicates the beneficial uses of
groundwater are not being protected, corrective action may be required.
The total present-worth cost for this alternative is $137,000,000; time required to
achieve remedial response actions is estimated as 30 months.
7.2.2 ALTERNATIVE 2C-PHYSICAL TREATMENT: ISV
ISV is accomplished by using a vacuum extraction system (VES) to induce airflow
from the subsurface soils to a vapor extraction point. The air from the subsurface is
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removed via the vapor extraction point by an air blower, thus creating a negative
pressure or vacuum in the subsurface soils. The airflow and vacuum condition in the
subsurface soils induces contaminants to volatilize from the adsorbed phase to the
vapor phase. The ISV offgases are then removed via the vapor extraction point and
treated prior to discharge to the atmosphere.
Implementation of ISV at SHARPE could consist of separate ISV systems operating
independently to remediate separate areas of contamination. Each ISV system could
consist of a positive displacement blower manifolded to a series of extraction network
piping which, in turn, is connected to the vapor extraction wells (VEWs). A
condensate separator would be used just prior to the blower to remove moisture from
the contaminated air stream. The condensate separator would contain control switches
and solenoid valves which would dump condensate to a collection tank once the
condensate separator is full. A bleed air inlet valve would be located in the vacuum
manifold piping between the blower and the condensate separator. The vapor
extraction manifold network would consist of PVC aboveground piping. VEWs would
consist of recovery wells screened from approximately 10 to 20 ft-bls. The selected
technology for ISV offgas treatment is vapor-phase-activated carbon.
This alternative would be compliant with all ARARs:
• Air Pollution Control District Rules and Regulations (Rule 2201) -- new
emission sources must comply with implementation of Best Available
Control Technology (BACT). Offgases from the treatment system will be
treated with gas-phase carbon adsorption prior to being discharged to the
atmosphere.
The following ARARs apply to areas where TCE-contaminated soils are determined to
be a potential threat to water quality:
• Water Quality Control Plan (Basin Plan) for CVRWQCB -- Defines
beneficial use levels for constituents in groundwater.
• State Water Resource Control Board Resolution No. 88-63, "Sources of
Drinking Water Policy" as contained in the CVRWQCB Water Quality
Control Plan ~ Specifies that with certain exceptions, all ground and
surface waters have the beneficial use of municipal or domestic water use.
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• 22 CCR Div. 4.5, Chapter 14, Article 6, §§ 66264.90 et seg. - Detection
monitoring and evaluation monitoring programs for TCE will be instituted
with this program. If monitoring data indicates the beneficial uses of
ground water are not being protected, corrective action may be required.
The total present-worth cost for this alternative is $528,000; time to achieve remedial
response actions is estimated at 24 months.
7.2.3 ALTERNATIVE 3A-INNOVATIVE TECHNOLOGIES:
LOW-TEMPERATURE THERMAL STRIPPING
The low-temperature thermal unit operates at temperatures up to 450°F to evaporate
the VOCs present in the soils through the application of these soils to an indirect heat
exchanger. Vaporized contaminants can either be destroyed through a secondary
high-temperature combuster, collected through condensate, or adsorbed onto activated
carbon.
In this alternative, contaminated soils would be excavated and stockpiled in an area
adjacent to the treatment unit for feeding into a scalping screen to remove oversized
(+2 inch) material and debris. Screened material would then be transported by a drag
conveyor to a hopper that directly feeds the thermal processor. The temporary storage
area for the soils awaiting treatment would be managed to prevent runon/runoff, wind
dispersion, and dermal contact. Any oversized material removed from the soil would
be decontaminated by pressure wash, if necessary.
The thermal processor is an indirectly heated, auger-type heat exchanger for solids
and slurries. The processor mixes, conveys, agitates, and heats the contaminated
soils, allowing the moisture, volatiles, and semivolatiles to vaporize and escape from
the soil. The operating temperature of the processor, approximately 450°F [204
degrees Celsius (°C)], minimizes the thermal load, but still allows vaporization. In
the portable system, two thermal processors, each with four 18-inch diameter,
20-ft long screws, are operated in sequence to induce adequate residence time and
agitation.
Treatment rates would be maintained to ensure destruction efficiencies would achieve
levels which do not threaten groundwater. Periodic monitoring of the stack gases
would be conducted to ensure compliance with emissions standards and guidelines.
Treated soil would be stored at the site until analyses verifies that the required level
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of destruction has been attained. Offsite laboratories would be used to provide these
analyses. If the required residual concentrations are not obtained for any treated soil
sample, the corresponding treated soil pile would be fed back into the thermal
processor for additional treatment. Once the soil concentrations are reduced to levels
that meet the cleanup criteria, they can be returned to the original excavations or used
as backfill in other areas.
Upon completion of thermal processing, the processor would be decontaminated and
removed from the site. Wastes generated during decontamination would be collected
and disposed of away from the original excavated area.
The treated soil resulting from the thermal processing would be used as backfill in the
excavated area. It is anticipated that a volume reduction of no greater than 5 percent
would take place in the soil as a result of the thermal process. Consequently, only a
small amount of soils would be needed to complete backfilling of the excavated areas
and to bring these areas back to the existing grade. Treated soil would be backfilled,
achieving a predetermined density. Density testing would be performed to verify the
effectiveness of these compaction efforts. A topsoil layer would then be applied to the
surface of the treated soil backfill.
This alternative would be compliant with all ARARs:
• Air Pollution Control District Rules and Regulations (Rule 2201) -- new
emission sources must comply with implementation of Best Available
Control Technology (BACT). Offgases from the treatment system will be
treated with gas-phase carbon adsorption prior to being discharged to the
atmosphere.
The following ARARs apply to areas where TCE-contaminated soils are determined to
be a potential threat to water quality:
• Water Quality Control Plan (Basin Plan) for CVRWQCB - Defines
beneficial use levels for constituents in groundwater. '
• State Water Resource Control Board Resolution No. 88-63, "Sources of
Drinking Water Policy" as contained in the CVRWQCB Water Quality
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Control Plan ~ Specifies that with certain exceptions, all ground and
surface waters have the beneficial use of municipal or domestic water use.
• 22 CCR Div. 4.5, Chapter 14, Article 6, §§ 66264.90 et seq. - Detection
monitoring and evaluation monitoring programs for TCE will be instituted
with this program. If monitoring data indicates the beneficial uses of
groundwater are not being protected, corrective action may be required.
The total present-worth cost for this alternative is $6,800,000; time to achieve
remedial response objectives is estimated at 16 months.
7.2.4 ALTERNATIVE 4A--REMOVAL AND DISPOSAL: OFFSITE
LANDFILL
The objective of this remedial technology is to physically remove the
TCE-contaminated soils from the South Balloon Area, North Balloon Area, and
Central Area. The contaminated soils would be excavated and transported off site for
final disposal in a landfill.
Prior to excavation of the contaminated soils, any existing pavement, concrete, and
light brush would be removed using a front-end loader. Contaminated debris and soils
would be staged for transportation to an offsite disposal facility.
Contaminated soils would be excavated from each area using a hydraulic backhoe or
similar equipment. The surface area of the working face would be kept as small as
possible to minimize the release of VOCs and fugitive dust emissions. Contaminated
soils would be loaded onto 20-yd3 dump trucks. Soils remaining in each excavation pit
would be analyzed to ensure that all soils which threaten groundwater are removed
and transported to the offsite disposal landfill.
Final disposal of TCE-contaminated soils is dependent on the results of TCLP
analyses. Land disposal is a viable alternative if a TCLP analysis yields TCE
concentrations in the leachate of less than 0.500 mg/L. If TCE concentrations in the
leachate exceed 0.500 mg/L, soils would be transported offsite to an appropriately
permitted treatment, storage, or disposal facility.
Additional soil would be needed to complete backfilling the excavated areas and to
return the affected areas to existing grade. This additional soil may be available from
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sites at SHARPE and/or from offsite locations. Backfill material would be placed in
1-ft lifts (or less) and compacted to achieve a predetermined density. Density testing
on every other lift would be performed to verify the effectiveness of compaction
efforts.
No ARARs were identified for the removal and disposal of soils containing TCE. The
following ARARs apply to areas where TCE-contaminated soils are determined to be
a potential threat to water quality:
• Water Quality Control Plan (Basin Plan) for CVRWQCB - Defines
beneficial use levels for constituents in groundwater.
• State Water Resource Control Board Resolution No. 88-63, "Sources of
Drinking Water Policy" as contained in the CVRWQCB Water Quality
Control Plan -- Specifies that with certain exceptions, all ground and
surface waters have the beneficial use of municipal or domestic water use.
• 22 CCR Div. 4.5, Chapter 14, Article 6, §§ 66264.90 et seq. - Detection
monitoring and evaluation monitoring programs for TCE will be instituted
with this program. If monitoring data indicates the beneficial uses of
groundwater are not being protected, corrective action may be required.
The total present-worth cost for this alternative is $23,000,000. Time to achieve
remedial response objectives is estimated at 8 months.
7.2.5 ALTERNATIVE 5A--NO ACTION: LIMIT ACCESS/USE
RESTRICTIONS
Alternative 5A (No Action) for the TCE-contaminated soils at the North Balloon
Area, South Balloon Area, and Central Area is a no-action alternative using
groundwater sampling and analysis to assess further groundwater contamination. This
alternative is included as a baseline for comparison with other alternatives. This
alternative does not minimize transport of TCE to groundwater caused by percolation
of runoff through overlying TCE-contaminated soils.
A complete round of sampling and analysis of surficial monitor wells in the vicinity
of the soils contamination would be conducted annually to monitor the effect of not
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remediating the contaminated soils. In addition, a report would be prepared every
5 years detailing the groundwater monitoring effort.
No ARARs were identified for this alternative.
8.0 SUMMARY OF COMPARATIVE ANALYSIS OF REMEDIAL
ALTERNATIVES
Evaluation of nine criteria is required under the NCP and Sec. 121 of CERCLA for
use in evaluation of remedial alternatives. The nine criteria are as follows:
THRESHOLD FACTORS
Overall Protection of Human Health and the Environment - Addresses whether or
not a remedy provides adequate protection and describes how risks posed through
each pathway are eliminated, reduced, or controlled through treatment, engineering
controls, or institutional controls.
Compliance with ARARs -- Site remediation should comply with federal and state
laws that apply to the project. This criteria evaluates whether or not a remedy will
meet all ARARs of federal and state environmental statutes. If the remedy does not
comply with ARARs of federal and state environmental statutes, this section should
specify grounds for invoking an ARAR waiver.
PRIMARY BALANCING FACTORS
Short Term Effectiveness - Addresses the period of time needed to complete the
remedy and any adverse impacts on human health and the environment that may be
posed during the construction and implementation period until the cleanup goals are
achieved.
Long-Term Effectiveness and Performance - Refers to the ability or remedy to
maintain reliable protection of human health and the environment over time, once
cleanup goals have been met.
Reduction of Mobility, Toxicity, and Volume (MTV) through Treatment - Refers
to the anticipated ability of a remedy to reduce the mobility, toxicity, and volume of
the hazardous components present at the site.
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Implementabilitj — Refers to the technical and administrative feasibility of a remedy,
including the availability of materials and services needed to carry out a particular
option.
Cost — Evaluates the estimated capital, operation, and maintenance costs of each
alternative.
MODIFYING FACTORS
State Acceptance — Indicates whether, based on its review of the information, the
state concurs with, opposes, or has no comment on the preferred alternative.
Community Acceptance - Indicates whether community concerns are addressed by
the remedy and whether the community has a preference for a remedy. Public
comment is an important part of the final decision.
A comparative analysis was conducted to evaluate the relative performance of each of
the five alternatives for lead- and chromium-contaminated soils and for
TCE-contaminated soils in relation to each of nine specific evaluation criteria. The
comparative summary is represented in tabular form in Table 8-1. The advantages and
disadvantages of the alternatives are compared in the following paragraphs. A
complete, detailed evaluation is presented in the Soils FS (ESE, 1994a).
8.1 LEAD- AND CHROMIUM-CONTAMINATED SOILS
The alternatives for lead- and chromium-contaminated soils include:
1. Alternative IC-Containment: Asphalt Cap;
2. Alternative 2A-Treatment: Physical/Chemical-Fixation/Solidification;
3. Alternative 2B~Chemical Extraction/Soil Washing;
4. Alternative 4B--Removal and Disposal: Off site Landfill; and
5. Alternative 5A~No Action: Limit Access/Use Restrictions.
8.1.1 PROTECTION OF HUMAN HEALTH AND THE ENVIRONMENT
Alternative 2A (Fixation/Solidification), Alternative 2B (Chemical Extraction/Soil
Washing), and Alternative 4B (Offsite Disposal) were all judged to be equivalent with
respect to protecting human health and the environment:
I. Alternative 2A (Fixation/Solidification) physically fixates lead and chromium
in a monolithic structure that will prevent leaching of the metals. After the
soil has been solidified, it is covered with an asphalt cap to remove the
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Table 8-1. Summary of Detailed Analysis of Remaining Alternatives for Lead-, Chromium-, and TCE-Contaminated Soils (Page 1 of 3)
ALTERNATIVE
SHORT-TERM EFFECTIVENESS (a)
Protection of
Community During
Remediation
Protection of
Workers During
Remediation
Environmental
Impacts
Time to achieve
Remedial Response
Objective
LONG-TERM EFFECTIVENESS .
Magnitude of
Remaining Risk
Adequacy of
Controls
Reliability of
Controls
LEAD- AND CHROMIUM-CONTAMINATED SOILS
1C— Containment
(Asphalt Cap)
2A— Treatment
(Fixation/Solidification)
2B— Innovative Technologies
(Chem Ext. /Soil Washing)
4B— Removal and Disposal
(OfTsite Landfill Disposal)
5 A— No Action
(Limit Access)
TCE-CONTAMINATED SOILS
26 — Onsite Incineration
2C— Treatment Technologies
(In-Situ Volatilization)
3A— Innovative Technologies
(Low Temp. Thermal Stripping)
4A— Removal and Disposal
(OfTsite Landfill Disposal)
5A — No Action
(Limit Access)
3
3
3
3
1
3
3
3
3
1
2
3
3
3
1
60 days
240 days
240 days
120 days
Odays
2
2
3
3
1
3
2
2
3
1
3
3
3
3
1
3
3
3
3
1
3
3
3
3
1
3
3
3
3
1
900 days
730 days
476 days
240 days
Odays
3
3
3
3
1
3
3
3
3
1
3
3
3
3
3
oo
00
3 = Alternative meets all requirements of this criterion.
2 = Alternative may not be capable of meeting all requirements of this criterion.
I = Alternative does not meet requirements of this criterion.
(a) = Only includes time following initiation of construction/installation. Does not include time for contractor procurement.
Source: ESE.
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Table 8-1. Summary of Detailed Analyali of Remaining Atternativei for Lead-, Chromium-, and TCE-Contaminaled Soili (Page 2 of 3)
ALTERNATIVE
REDUCTION OF TOXICfTY, MOBILITY, AND VOLUME
Treatment Process
and Remedy
Amount of Hazardous
Materials Destroyed or
Treated
Reduction in
MTV
Irreversibility of
Treatment
Type and Quantity of
Treatment Residual
IMPLEMENTABILITY
Technical
Feasibility
Administrative
Feasibility
Availability of
Services and
Materials
LEAD- AND CHROMIUM-CONTAMINATED SOILS
1 C— Containment
(Asphalt Cap)
2A— Treatment
(Fixation/Solidification)
2B — Innovative Technologies
(Chem Ext./Soil Washing)
4B— Removal and Disposal
(Offsile Landfill Disposal)
5A— No Action
(Limit Access)
3
3
3
3
1
1
3
3
1
'
2
2
2
3
1
1
3
3
3
1
1
3
3
3
1
3
2
3
3
3
3
3
3
3
3
3
3
3
3
3
TCE-CONTAMINATED SOILS
2B— Onsite Incineration
2C— Treatment Technologies
(In-Situ Volatilization)
3A— Innovative Technologies
(Low Temp. Thermal Stripping)
4A— Removal and Disposal
(Offsite Landfill Disposal)
5 A— No Action
(Limit Access)
3
3
3
3
'
3
3
3
1
1
3
3
3
3
1
3
3
3
3
1
3
3
3
3
1
3
3
3
3
3
1
3
3
3
I
2
3
2
3
1
oo
3 = Alternative meets all requirements of this criterion.
2 = Alternative may not be capable of meeting all requirements of this criterion.
I = Alternative does not meet requirements of this criterion.
Source: ESE.
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Table (I-1. Summary of Detailed Analysis of Remaining Alternatives for Lead-, Chmmium-, and TCE Contaminated Soils (Page 3 of 3)
ALTERNATIVE
COSTS (b)
Capital
Costs
($1,000)
Annual
O&M
Costs
($1,000)
Accuracy of
Cost
Estimates
Present
Worth
Cost
($1,000)
Overall
Costs
COMPLIANCE WfTH ARARs
Contaminant-
Specific
ARARs
Action-
Specific
ARARs
Location-
Specific
ARARs
Other Criteria,
Advisories, and
Guidance
Protection of
Human Health
and the
Environment
State
Acceptance
Community
Acceptance
LEAD- AND CHROMIUM-CONTAMINATED SOILS
1 C— Containment
(Asphalt Cap)
2A— Treatment
(Fi xation/Solidi Citation)
2B— Innovative Technologies
(Chem Ext./Soil Washing)
4B — Removal and Disposal
(Offsite Landfill Disposal)
5A— No Action
(Limit Access)
TCE-CONTAMINATED SOILS
2B— Onsite Incineration
2C— Treatment Technologies
(In-Situ Volatilization)
3 A— Innovative Technologies
(Low Temp. Thermal Stripping)
4A— Removal and Disposal
(Offsite Landfill Disposal)
5 A— No Action
(Limit Access)
280
808
1,425
221
52
4
4
N/A
N/A
N/A
3
1
1
3
3
388
1,015
1,773
683
52
3
2
1
3
3
N/A
N/A
N/A
N/A
N/A
3
3
3
3
3
N/A
N/A
N/A
N/A
N/A
137,000
286
6,800
23,000
N/A
N/A
130
N/A
N/A
260
2
3
3
3
3
137,000
528
6,800
23,000
260
1
3
1
1
3
N/A
N/A
N/A
N/A
N/A
3
3
3
3
3
N/A
N/A
N/A
N/A
N/A
3
3
3
3
3-
3
3
3
3
3
2
3
3
3
1
3
3
3
3
1
!
3
3
2
I
2
3
3
2
1
NCR
NCR
NCR
NCR
NCR
NCR
NCR
NCR
NCR
NCR
3 = Alternative meets all requirements of this criterion.
2 = Alternative may not be capable of meeting all requirements of this criterion.
1 = Alternative does not meet requirements of this criterion.
NCR = No Comments Received (to be updated after review of public comments).
(b) = Based on a discount rate of 5 percent and a 20-year period.
Source: ESE.
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exposure pathway to environmental receptors.
2. Alternative 2B (Chemical Extraction/Soil Washing) chemically removes lead
and chromium from the site soils. The treatment residuals are transported
off site to an appropriately permitted waste management facility.
3. Alternative 4B (Offsite Disposal) removes all soils with lead and chromium
in excess of cleanup standards from the site, thus preventing exposure to
soils that could cause adverse health effects.
Alternative 1C (Asphalt Cap) was judged to be less effective in the protection of
human health and the environment than alternatives 2A (Fixation/Solidification),
2B (Chemical Extraction/Soil Washing), and 4B (Offsite Disposal) in that soils with
lead and chromium exceeding cleanup standards would still remain at the site in an
unaltered matrix. Although this alternative does remove an exposure pathway, the fact
that soils are left onsite in concentrations exceeding cleanup standards makes this
alternative less desirable with respect to protection of human health and the
environment.
Alternative 5A (No Action) is not protective of human health and the environment in
that onsite workers would continue to be exposed to soils that exceed cleanup
standards.
8.1.2 COMPLIANCE WITH ARARS
Alternatives 1C (Asphalt Cap), 2A (Fixation/Solidification), 2B (Chemical
Extraction/Soil Washing), and 4B (Offsite Disposal) are all equally capable of
compliance with ARARs.
Alternative 5A (No Action) will not comply with ARARs.
8.1.3 LONG-TERM EFFECTIVENESS
Alternative 4B (Offsite Disposal) was determined to be the best alternative with
respect to long-term effectiveness. With the removal of all soils in excess of cleanup
standards, no health threats would remain onsite. The implementation of Alternative
4B (Offsite Disposal) could be completed with reliable and adequate controls.
Alternative 2B (Chemical Extraction/Soil Washing) was judged to be slightly less
effective that Alternative 4B (Offsite Disposal). Although the magnitude of remaining
risk would be equivalent to that described in Alternative 4B (Offsite Disposal) (i.e.,
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all soils in excess of cleanup standards would be removed from the site), the
reliability of the alternative is questionable. Soil Washing/Chemical Extraction is an
innovative technology for which substantial experience with implementation does not
exist. Therefore, there is insufficient information to judge how well the process will
perform.
Alternative 2A (Fixation/Solidification) was considered to be slightly less effective
than Alternatives 4B (Offsite Disposal) and 2B (Chemical Extraction/Soil Washing).
Although solidification/stabilization is a proven technology to remediate contaminated
soils, and success of treatment can be documented in the short-term, there are
unknown factors associated with the long-term stability of the monolith containing
lead- and chromium-contaminated soils.
Alternative 1C (Asphalt Cap) was considered to be less effective than the above
alternatives. A limited life is associated with the installation of an asphalt cap. The
reliability to which the cap will be maintained and replaced in the future makes this
alternative less effective than the other previously described.
Alternative 5A (No Action) is the no-action alternative and does not address the
appropriate long-term related issues related to protection of adult workers onsite.
8.1.4 REDUCTION OF TMV THROUGH TREATMENT
Alternative 2B (Chemical Extraction/Soil Washing) was rated the highest with respect
to reduction of TMV through treatment. It treats all soils with lead and chromium in
excess of cleanup standards, reduces the toxicity of the soils through chemical
extraction of lead and chromium, and eliminates the potential of lead and chromium
mobility from soils. The process is irreversible and yields a residual that can be easily
managed offsite. However, this technology has not been field tested at SHARPE. The
ability of the process to reduce TMV is not known.
Alternative 2A (Fixation/Solidification) was considered to be slightly less effective
than 2B (Chemical Extraction/Soil Washing) with respect to reduction of TMV
through treatment. Although the mobility of lead and chromium would be addressed
with this alternative, lead- and chromium-contaminated soils would remain onsite in
the form of a monolith; there is an estimated 25-percent volume increase associated
with treatment of soils. All other evaluation factors for this criteria were considered
equivalent with Alternative 2B (Chemical Extraction/Soil Washing).
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Alternative 4B (Offsite Disposal) was considered to be slightly less effective than
2A (Fixation/Solidification) with respect to reduction of TMV through treatment,
solely due to the fact that no soils will be treated or destroyed with this alternative.
Soils contaminated with lead and chromium in excess of cleanup standards would
simply be transported to an appropriately permitted offsite disposal facility. All other
evaluation factors for this criteria were considered equivalent with Alternative 2A
(Fixation/Solidification).
Alternative 1C (Asphalt Cap) was considered to be less effective than the above
alternatives because the lead- and chromium-contaminated soils in excess of cleanup
standards would remain in place. Although this alternative would reduce mobility
through capping, the toxicity and volume of the soils would remain unchanged. Also,
an asphalt cap is not considered a permanent structure, and there are concerns with
respect to irreversibility of treatment with this alternative. No treatment is employed
with this alternative.
Alternative 5A (No Action) does not reduce the toxicity, mobility, or volume of lead-
and chromium-contaminated soils through treatment at SHARPE.
8.1.5 SHORT-TERM EFFECTIVENESS
Alternatives 2A (Fixation/Solidification), 2B (Chemical Extraction/Soil Washing), and
4B (Offsite Disposal) were all judged to be equivalent with respect to short-term
effectiveness. All three alternatives protect the community and workers onsite. No
adverse environmental impacts are expected with the implementation of these three
alternatives. The time to implement Alternatives 2A (Fixation/Solidification),
2B (Chemical Extraction/Soil Washing), and 4B (Offsite Disposal) are considered
comparable at 240 days, 240 days, and 120 days, respectively.
Alternative 1C (Asphalt Cap) was considered to be less effective that the previously
described alternatives in that lead- and chromium-contaminated soils in excess of
cleanup standards would remain onsite.
Alternative 5A (No Action) was not considered to adequately address short term
effectiveness because onsite workers would continue to be exposed to lead- and
chromium-contaminated soils in excess of cleanup standards.
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8.1.6 IMPLEMENTABILITY
Alternatives 1C (Asphalt Cap) and 4B (Offsite Disposal) were considered to be the
most implementable alternatives evaluated with respect to technical feasibility,
administrative feasibility, and availability of services and materials. Alternatives 2A
(Fixation/Solidification) and 2B (Chemical Extraction/Soil Washing) were considered
less implementable due to the lack of pilot testing data which would confirm that the
technology is technically feasible.
As Alternative 5A (No Action) does not involve remediation; however,
implementability of this alternative is not a concern, as the only construction required
would be installation of a fence.
8.1.7 COSTS
Capital, O&M, and present-worth costs for Alternatives 1C (Asphalt Cap),
2A (Fixation/Solidification), 2B (Chemical Extraction/Soil Washing), 4B (Offsite
Disposal), and 5A (No Action) are presented in Table 8-1.
The present-worth cost is the least expensive for the no-action alternative. The least
expensive action alternative is Alternative 1C (Asphalt Cap); Alternative 2A
(Fixation/Solidification) has a much higher capital cost than 4B (Offsite Disposal).
The costs for Alternative 2B (Chemical Extraction/Soil Washing) are significantly
higher than the estimated costs for the other action alternatives.
8.1.8 STATE ACCEPTANCE
Alternative 2A (Fixation/Solidification) and 2B (Chemical Extraction/Soil Washing)
were considered the most acceptable to the state, as they employed treatment as a
principal element of reducing TMV. Alternative 4B (Offsite Disposal) involves
excavation followed by removal and disposal. This alternative is considered acceptable
to the state, but is not as favorable as treatment remedies.
Alternative 1C (Asphalt Cap) is not acceptable to the state as it does not provide a
permanent solution. Alternative 5A (No Action) is not acceptable to the state as it
does not protect human health and the environment.
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8.1.9 COMMUNITY ACCEPTANCE
Based on the public review and comment on the Proposed Plan, the community has
no significant concerns regarding selection and/or implementation of any of the
alternatives investigated by SHARPE to remediate contaminated soils.
8.2 TCE-CONTAMINATED SOILS
The alternatives for TCE-contaminated soils include:
1. Alternative 2B~Thermal Treatment: Onsite Incineration,
2. Alternative 2C-Treatment Technologies: In-Situ Volatilization (ISV),
3. Alternative 3A—Innovative Technologies: Low-Temperature Thermal
Stripping (LTTS),
4. Alternative 4A--Removal and Disposal: Offsite Landfill, and
5. Alternative 5A~No Action: Limit Access/Use Restrictions •
8.2.1 PROTECTION OF HUMAN HEALTH AND THE ENVIRONMENT
The levels of TCE in soils do not exceed the EPA-recommended 10"4 to 10"6 risk
range, so there is not a specific concern with worker exposure to these soils.
However, remediation of TCE-contaminated soils will expedite and enhance the cost-
effectiveness of the groundwater remediation effort being conducted in accordance
with the June 1993 OU1 ROD.
Alternative 2B (Onsite Incineration), 2C (ISV), 3A (LTTS), and 4A (Offsite Disposal)
were all judged to be equivalent with respect to protection of human health and the
environment:
1. Alternative 2B (Onsite Incineration) would incinerate soils contaminated with
TCE. Proper management of incinerator emissions would prevent adverse
affects on the population potentially affected by the implementation of this
alternative.
2. Alternative 2C (ISV) would remove TCE from contaminated soils using the
process of in-situ volatilization. Using carbon adsorption to treat offgases
from the process would protect the population potentially exposed to ISV
emission.
3. Alternative 3A (LTTS) would remove TCE from contaminated soils using
the process of low temperature thermal stripping. Using carbon adsorption to
treat offgases from the process would protect the population potentially
exposed to LTTS emissions.
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4. Alternative 4A (Offsite Disposal) would remove TCE-contaminated soils
from the site and transport them to an offsite disposal facility.
The above alternatives are all considered to be protective of human health and the
environment.
Alternative 5A (No Action) is judged to be less effective in the protection of human
health and the environment in that TCE-contaminated soils would be allowed to
!
remain onsite and function as a continuing source of groundwater contamination.
However, when considering the scope of the groundwater treatment action currently
underway at SHARPE, Alternative 5A (No Action) is considered protective of human
health and the environment.
8.2.2 COMPLIANCE WITH ARARS
Alternatives 2B (Onsite Incineration), 2C (ISV), 3A (LTTS), and 4A (Offsite
Disposal) are equally capable of achieving all ARARs. No ARARs were identified for
Alternative 5A (No Action).
8.2.3 LONG-TERM EFFECTIVENESS
Alternatives 2B (Onsite Incineration), 2C (ISV), 3A (LTTS), and 4A (Offsite
Disposal) were all judged to be equally effective with respect to long-term
effectiveness of remediation. All technologies used in these four alternatives, are
proven for soils contaminated with VOCs. As TCE-contaminated soils do not
represent a health threat, implementation of the four alternatives is expected to result
in acceptable residual risks onsite. Once the remedial action is completed,
effectiveness of the treatment at the completion of the action is not expected to
decrease over time. Alternative 2B (Onsite Incineration) does not yield any residuals
that require offsite management. Alternatives 2C (ISV), 3A (LTTS), and 4A (Offsite
Disposal) yield residuals, which must be managed offsite at appropriately permitted
waste management facilities.
As Alternative 5A (No Action) does not result in implementation of an alternative,
there are no long-term effectiveness parameters to address.
8.2.4 REDUCTION OF MTV THROUGH TREATMENT
Alternatives 2B (Onsite Incineration), 2C (ISV), and 3A (LTTS) were all considered
to be equally effective in reduction of MTV through treatment for TCE-contaminated
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soils. All three technologies employ treatment of TCE. However, Alternative 2B
(Onsite Incineration) does employ a technology that destroys TCE. With alternatives
2C (ISV) and 3A (LTTS), TCE is transferred from the soils to activated carbon (for
emission controls). TCE adsorbed on carbon will eventually be transferred offsite for
reactivation, which involves destruction of TCE.
Alternative 4A (Offsite Disposal) does not involve treatment. Therefore, no TCE is
treated or destroyed with this alternative. The TCE-contaminated soils are simply
transferred offsite to an appropriately permitted disposal facility.
Alternative 5A (No Action) does not involve remedial action; no reduction of MTV
through treatment is associated with this alternative.
8.2.5 SHORT-TERM EFFECTIVENESS
Alternatives 2B (Onsite Incineration), 2C (ISV), 3A (LTTS), 4A (Offsite Disposal),
and 5A (No-Action) were all considered to be equally effective with respect to
protection of the community and onsite workers through implementation prudent
safety precautions. However, the time to achieve remedial response objectives vary.
Alternative 5A can be implemented immediately. Estimated time to completion of
Alternative 4A (Offsite Disposal) is 240 days, followed by Alternatives 3A (LTTS),
2C (ISV), and 2B (Onsite Incineration) at 476, 730, and 900 days, respectively.
8.2.6 IMPLEMENTABILITY
Alternatives 2C (ISV) and 4A (Offsite Disposal) were considered to be the most
implementable alternatives evaluated with respect to technical feasibility,
administrative feasibility, and availability of services and materials. Alternatives 3A
(LTTS) was considered slightly less implementable due to the fact that the process is
patented and there are a limited number of LTTS systems available at any given time.
Alternative 2B (Onsite Incineration) was considered to be the least implementable
alternative due to complications associated with permitting incinerators, although
SHARPE need only comply with the substantive requirements of a permit.
Implementation of Alternative 5A (No Action), which includes groundwater
monitoring, is not expected to be difficult.
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8.2.7 COSTS
Capital, O&M, and present-worth costs for Alternatives 2B (Onsite Incineration),
2C (ISV), 3A (LTTS), 4A (Offsite Disposal), and 5A (No Action) are presented in
Table 8-1.
The present-worth cost is the least expensive for the no-action alternative. The least
expensive action alternative is Alternative 2C (ISV); Alternative 4A (Offsite Disposal)
has a much higher capital cost than Alternative 3A (LTTS). The capital costs for
Alternative 2B (Onsite Incineration) are significantly higher than the estimated costs
for the other treatment alternatives.
8.2.8 STATE ACCEPTANCE
Alternatives 2C (ISV) and 3A (LTTS) were considered equally acceptable to the state
as they utilize treatment as a principal element of remediation. Alternative 2B (Onsite
Incineration), although employing treatment, was considered less acceptable due to the
potential of the process yielding mobile metals in ash that could eventually leach to
groundwater. Alternative 4A (Offsite Disposal) involves excavation followed by
removal and disposal. This alternative is considered acceptable to the state, but is not
as favorable as treatment remedies.
Alternative 5A (No Action) is not acceptable to the state as it does not protect human
health and the environment.
8.2.9 COMMUNITY ACCEPTANCE
Based on the public review and comment on the Proposed Plan, the community has
no significant concerns regarding selection and/or implementation of any of the
alternatives investigated by SHARPE to remediate contaminated soils.
9.0 THE SELECTED REMEDIES
Based on the requirements of CERCLA, information obtained during the RI (ESE,
1990) and FS (ESE, 1994b), detailed analysis of alternatives, and public comments,
SHARPE, EPA, DTSC, and CVRWQCB have determined that:
1. Alternative 4B (Removal and Disposal to Offsite Landfill) is the most
appropriate remedy for lead- and chromium-contaminated soils to protect
human health and the environment from exposure to these soils;
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2. Alternative 2C (ISV) is the most appropriate source-control remedy for
TCE-contaminated soils given the groundwater remediation effort currently
being operated at SHARPE; and
3. NFA is appropriate for 111 SWMUs.
The following sections describe the major components of each of the selected
alternatives. Engineering variables presented in the following sections, however, are
subject to change during the remedial design phase of work, which is to be
implemented following signature of the ROD by SHARPE, EPA, DISC, and
CVRWQCB. Such changes, in general, reflect modifications resulting from the
engineering design process.
9.1 LEAD- AND CHROMIUM-CONTAMINATED SOILS
Removal and Disposal: Offsite Landfill
The objective of the remedy is to excavate lead- and chromium-contaminated soils
from those areas defined hi Fig. 2-1 such that the soil concentrations do not present a
threat to human health and the environment. Major components of this alternative
include:
1. Characterization of locations with levels of lead and chromium exceeding or
potentially exceeding cleanup standards;
2. Clearing of areas where excavation is required;
3. Excavation of soils which exceed cleanup standards for lead and chromium,
followed by disposal at an appropriately permitted offsite disposal facility;
4. Collection of verification samples from the floor and walls of the excavation
to ensure that all soils exceeding cleanup standards for lead and chromium
have been removed;
5. Backfill and compaction of fill in excavation to return excavation sites to
natural grade;
6. Characterization of dissolved lead and chromium in excavations;
7. Perform a statistical analysis of lead and chromium in groundwater, to
determine if groundwater has been impacted at levels hi excess of MCLs;
and
8. Institute a groundwater monitoring plan.
Based on conclusions presented hi the Soils RA report, several areas of concern exist
at SHARPE.
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9.1.1 FURTHER CHARACTERIZATION
The initial phases of remedial action involve characterization of sites determined to
exceed or potentially exceed cleanup standards. Prior characterization in the North
and South Balloon Area has been accomplished using XRF methods. These methods
were considered reliable for samples collected in the North Balloon Area. However,
data collected hi the South Balloon Area showed poor correlation between laboratory
and field methods. For this reason, it is appropriate to re-characterize the South
Balloon Area, at specific locations, for lead and chromium. Sites recommended for
further chromium characterization in the 0 to 2-ft interval are (see sample grid on
Fig. 5-12):
9G
20S-3G
50N+50E-1F
S29-B4
S29-B6
S29-B9
S29-B11
S29-B12
48E-1F
50E-1H
Sites recommended for further lead characterization hi the 0- to 2-ft interval are (see
sample grid on Fig. 5-12):
9E
50E-1H
50E-1G
S29-B9
9G
9.1.2 CLEANUP STANDARDS
The cleanup standard for lead-contaminated soils in the North and South Balloon
Areas has been established as 1,000 mg/kg. The soil cleanup level of 1,000 mg/kg
has been confirmed as protective of an industrial adult worker based on results from
the DTSC's Lead Spreadsheet Model default exposure scenarios. This cleanup level is
also inclusive of the range of 500 mg/kg to 1,000 mg/kg, which EPA recommends as
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an interim cleanup level based on EPA's biokinetic uptake model (EPA, 1991 a).
Although a cleanup value of 1,000 mg/kg may not be protective of a residential child,
such a receptor exposure is currently not applicable nor anticipated at the site. If the
land use and site activities at SHARPE are altered in the future to include residential
housing and child exposure scenarios, then a reevaluation of the risk assessment will
be warranted in accordance with DOD base closure policy (Title U.S.C. 2687 and
NOTE). Results from a revised risk assessment, based on changing receptors, may
necessitate implementation of additional remedial actions.
EPA has not established an interim cleanup level for chromium at Superfund sites.
The most sensitive health-based toxicity endpoint identified in the current literature
for chromium is contact dermatitis. The dermatitis toxicity value for trivalent
chromium is calculated to be 500 mg/kg. This value of 500 mg/kg accounts for both
sensitization and elicitation of the dermatitis reaction and is protective of greater than
90 percent of the population. It is not protective of the 10 percent of the population
considered hypersensitive. This may not be a conservative cleanup value, since all the
chromium is assumed to be in trivalent form. The cleanup standard for chromium was
established as 300 mg/kg, at the request of CVRWQCB. The Board considered this
level more protective of groundwater than the 500 mg/kg level previously referenced.
There are several areas where lead- and chromium-contaminated soils above cleanup
standards exist in the same location. When considering this, the total volume of soils
requiring remedial action is estimated at 2,825 yd3 (2,085 yd3 in the South Balloon
Area and 740 yd3 in the North Balloon Area). The total area represented by this
volume, which should be considered in estimating the area and volume of soils to be
remediated, is 68,050 ft2 (28,150 ft2 in the South Balloon Area and 39,900 ft2 in the
North Balloon Area).
9.1.3 EXCAVATION AND REMOVAL ACTIVITIES
After areas of contamination in excess of cleanup standards have been confirmed, site
preparation will be completed. This includes removal of light brush and any existing
pavement or concrete using a front-end loader. Uncontaminated debris would then be
loaded into covered trucks and transported to an appropriately permitted construction
landfill.
Contaminated soils would be excavated from each area using a hydraulic backhoe or
similar equipment. The maximum depth of excavation would be 2 ft, which represents
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a depth by which humans could be expected to come into contact with soils. The
surface area of the working face would be kept as small as possible to minimize the
release of fugitive dust emissions. Contaminated soils would be loaded onto 20-yd3
dump trucks. Transportation of all soils would be completed in a manner that
complies with all federal, state, and local laws.
Following removal of soils with lead and chromium concentrations in excess of
cleanup standards, confirmation sampling will be conducted in the excavation (wall
and floor samples) to ensure that all soils exceeding cleanup standards have been
removed. The specific details of the confirmation sampling plan will be provided as
part of the remedial design (RD).
Testing would be conducted to determine if any soils were hazardous by
characteristic. If soils were determined to be hazardous by characteristic, the
excavated soils would be disposed of in a Class I facility. One such facility exists in
Kettleman, CA. If soils were determined to be non-hazardous, they would be disposed
of at a Class n facility. One such facility exists in Stockton, CA. It was estimated that
completion of this remedial alternative would require approximately 120 working
days.
Approximately 2,825 yd3 of additional soil would be needed to complete backfilling
and to return the affected area to existing grade. This additional soil may be available
from sites at SHARPE and/or from offsite locations. Backfill material may be placed
in 1-ft lifts (or less) and compacted to achieve 95 percent of the Modified Procter
Test Method. Density testing on every other lift would be performed to verify the
effectiveness of compaction efforts. Locations of soils to be excavated in the North
and South Balloon Areas are presented in Fig. 2-1.
9.1.4 EVALUATION OF RESIDUAL CONCENTRATIONS AND
EVALUATION OF GROUNDWATER
SHARPE will evaluate the impact or threat of impact to ground water from the
residual lead and chromium in the vadose zone using an appropriate methodology.
SHARPE has agreed to undertake the following tasks for soils:
1) Perform sampling, using DI WET, to evaluate the levels of soluble metals
left in place.
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2) If the DI WET analysis reports samples with lead greater than 150 ug/1
and/or chromium greater than 50 ug/1, then SHARPE will perform an
attenuation study. SHARPE will develop an appropriate methodology to
characterize the degree of attenuation provided by the underlying soils to
retard the movement of remaining lead and chromium hi the vadose zone hi
the excavation areas. This methodology may include fate and transport
analysis of metals, collection of soil lithology to characterize the geology hi
the immediate vicinity, completion of soil testing analysis to characterize soil
ability to retard metals, and analysis of deeper soils for chromium and lead.
If the Soils Attenuation Study shows that the residual soils concentrations threaten to
impact water quality above MCLs, than SHARPE, USEPA, DTSC, and the RWQCB
will determine the need for any additional characterization or remedial actions and
modify this ROD, if necessary.
SHARPE has agreed to undertake the following task for ground water:
Complete a Ground Water Statistical Analysis to be included as part of the
Annual Ground Water Monitoring Report to determine if ground water has
been statistically impacted at levels above background or above MCLS. The
Ground Water Monitoring Plan will specify the frequency, location, and
duration of metals analysis.
If an Annual Ground Water Statistical Analysis identifies a statistically significant
impact to water quality above the conditions that exist at the time of signature of this
ROD, then SHARPE, USEPA, DTSC, and RWQCB will determine the need for any
additional action (may include continued monitoring, ground water data trend
analysis, soil sampling, or additional remedial actions) and modify this ROD, if
necessary.
Alternative 2C-Treatment Technologies In-Situ Volatilization
The ISV alternative involves using a ISV to induce air flow from the subsurface soils
to a vapor extraction point. The air from the subsurface is removed via the vapor
extraction point by an air blower, thus creating a negative pressure or vacuum in the
subsurface soils. The airflow and vacuum condition hi the subsurface soils induces
contaminants to volatize from the adsorbed phase to the vapor phase. The ISV
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offgases are then removed via the vapor extraction point, and activated vapor-phase
carbon will be used to remove the TCE from the ISV offgases prior to discharge to
the atmosphere. Soil gas monitoring wells, independent of ISV wells, will be installed
to monitor progress of remediation.
The two components of this alternative are:
1. Remediation of seven sites that have been sufficiently characterized and
found to be degrading groundwater (see five blue-shaded sites and two black-
shaded sites in Fig. 2-1);
2. Characterization of seven sites that are potentially degrading groundwater
(see green shaded areas hi Fig. 2-1). These sites are subject to remediation
based on the results of the characterization.
9.2.1 ISV OPERATION
Sharpe will remediate VOC contamination in the soil as a source control effort to
prevent further degradation of the ground water and minimize the aquifer cleanup
time. SHARPE will evaluate ISV remediation effectiveness by tracking the cumulative
mass of VOCs removed and modeling to assess the affects of remaining VOCs on
ground water. Additionally, soil gas monitoring will be conducted in order to obtain
the soil gas concentration data necessary to run the models referenced in
section 9.2.2. and 9.2.3. ISV remediation will continue until asymptotic conditions
have been reached.
Sharpe will plot the mass of VOCs removed as a function of time to help determine
how quickly the cumulative mass removed approaches asymptotic levels. It is
expected that the graph of cumulative mass removed versus time will follow the
general curve defined by the following exponential decay equation:
Mt = Sum(Mi) - KT [l-exp(-t/T)] Equation 1
Where: t = time
Mt = total cumulative mass removed at time t
Mi = total mass removed from each vapor extraction well
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KT = that maximum cumulative total mass which the ISV system
approaches asymptotically,
T = Tao, the time constant, or resident time = amount of time at
which the ISV system removes approximately 63% of KT
(theoretically, T is equivalent to V/Q, or the volume of soil gas
in the zone being remediated (V) divided by the volumetric flow
rate of the ISV system (Q))
Equation 1 above will be used as a guide for using field data to determine when
asymptotic conditions have been met. Where the "asymptote" to the mass removal
curve is that total/cumulative maximum mass (KT - defined above) which the ISV
system attempts to remove but approaches with ever decreasing speed asymptotic
conditions will have been reached when the upper limb or this curve is substantially
linear and the slope of the curve approaches zero. The specific procedures used to
evaluate if data are asymptotic will 'be defined during the remedial design phase of
work. However, it is not expected that field data will match the theoretical equation
exactly, thus, based on field data it will be necessary to use best professional
judgement to conclude that asymptotic conditions have been reached.
In order to assess if there are zones where the ISV system has not removed VOCs
"rebound periods" will be used to allow residual vadose zone contamination to re-
equilibrate. The treatment system will be shut down temporarily for a suitable period
of time after an asymptotic (mass removed) curve is produced. This will allow for
VOC concentrations to re-establish in the soil gas. After the temporary shutdown
period, soil gas monitoring points will be sampled to determine the remaining VOC
concentrations in the soil gas. If the resulting VOC levels are not characteristic of the
previous conditions, or indicate a "spike" increase in soil gas concentration, then
additional treatment may be warranted.
9.2.2 VOC CONTAMINATED SOIL CLEANUP STANDARD
VOC contaminated soils cleanup, for each remediation area, shall:
(a) be protective of human health and the environment; and
(b) not cause or threaten to cause concentrations in the ground water to exceed
the aquifer cleanup levels.
P/SHARPE/OU2ROD.R3
02/06/96 105
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VLEACH or another appropriate vadose zone model will be used to assess the effects
of VOC contaminated soils to a 10 foot deep zone of ground water underneath the
source area. For the SHARPE site, the Parties have agreed that a TCE soil gas
concentration at or below 350 ppbv will be considered to satisfy the above standard
without modeling.
For those VOC sources in the vadose zone overlying ground water that is not
currently in excess of the aquifer cleanup levels (e.g, the black shaded area in the
upper left corner of Figure 2.1) Sharpe has proposed VOC soil remediation so that
existing VOC concentrations in the underlying groundwater will not increase.
SHARPE will design, construct, operate, and, if necessary, modify the ISV systems
to comply with this cleanup standard. If at some later date it is determined that it is
infeasible to achieve the VOC contaminated soils cleanup standard specified above,
this issue will be reevaluated by SHARPE, USEPA, DISC, and the CVRWQCB.
9.2.3 TECHNICAL AND ECONOMIC FEASIBILITY
Even if the cleanup standard in Section 9.2.2 is met, SHARPE has agreed that VOCs
in the vadose zone will be remediated to the extent technically and economically
feasible. The feasibility analysis will include but not be limited to consideration of the
following factors:
1) Technical effectiveness of the system, including whether the asymptote as
described in 9.2.1 has been reached;
2) A ground water transport model may be used to predict the time the pump
and treat remedy would need to operate, with no additional vadose zone
remediation, to achieve aquifer cleanup levels;
3) The additional cost for continuing to operate the ISV system to/at asymptotic
mass levels;
4) The total cost for enhancing the ISV technology (e.g., additional vapor
extraction wells, air injection) beyond system optimization, which should
occur throughout operation of the remedial action, to remove additional
VOCs;
P/SHARPE/OU2ROD.R3
02/06/96 106
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5) The cost of vadose zone remediation compared to the cost of ground water
remediation when comparing cost on the basis of a common unit (i.e., cost
per pound of TCE removed) prior to the time that ground water reaches
aquifer cleanup levels.
SHARPE will provide the information specified in sections 9.2.1, 2, and 3 to the
regulatory agencies for review and approval prior to formal shutdown of the ISV
systems. Additionally, quarterly performance reports of operating ISV systems will be
provided to regulatory agencies for review and comment until ISV activities are
terminated.
9.2.4 FURTHER CHARACTERIZATION
As described in Section 9.2, characterization is required at seven areas green shaded
areas in Figure 2-1. Soil gas samples for VOC analysis will be collected for lateral
and vertical characterization of the extent of VOC contamination in the vadose zone.
This information will be used to determine if these areas of concern are hi compliance
with the ISV cleanup standard. If not, the ISV system will be installed and optimized
as described above. If the data collected as part of the characterization indicates that
TCE soil gas concentrations are less than 350 ppbv, then no action will be taken.
Even if the VOC contamination in these areas is below the ISV cleanup standard,
SHARPE may proceed with remedial action as described above when it is cost
effective and when site specific characteristics (e.g., lithology) indicate that the ISV
treatment would be practical.
The following factors will be used in the cost-effectiveness analysis:
1) The additional cost for extending the groundwater pump and treat remedy,
but with no additional soils remediation, in order to attain drinking water
standards in the aquifers;
2) The total cost for implementing the ISV system to asymptotic mass levels;
3) The cost of vadose zone remediation compared to the cost of ground water
remediation when comparing cost on the basis of a common unit (i.e., cost
P/SHARPE/OU2ROD.R3
02/06/96 107
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per pound of TCE removed) prior to the time that ground water reaches
aquifer cleanup levels.
This information will be presented to the regulatory agencies for review and approval
prior to close-out of these areas of concern.
9.3 NO FURTHER ACTION SITES
During the course of the CERCLA investigations, SHARPE recommended that many
sites be considered NFA sites. A no further action determination is appropriate in the
following situations: when an area is already in a protective state (i.e., an area poses
no current or potential threats to human health or the environment); or when
CERCLA does not provide the appropriate legal authority to undertake a remedial
action. The 1994 Soils FS documented all sites that SHARPE considers to require
NFA along with the rationale supporting why the NFA would be appropriate. EPA,
DTSC, and CVRWQCB have reviewed this information and agree that a total of 111
SWMUs fall into the category of NFA. These sites are presented in Table 9-1, along
with the reasoning as to why each site is considered an NFA site.
SWMUs were originally identified as part of the RI. Each SWMU was evaluated for
its past operation and potential for generating wastes. Those SWMUs for which no
documented releases were reported, or those for which during the normal operation
would not be suspected of causing releases of wastes to the environment, were not
evaluated further and were considered to require no further action. Those sites
suspected of being areas where wastes were released were evaluated as part of the
later stages of the RI. Data from these investigations was incorporated into the RA.
Sites with COCs less than health-based cleanup standards were recommended for
NFA. The maximum concentrations of chemical detected at the NFA sites do not pose
risks to human health and the environment. Therefore, no remedial actions are
necessary to ensure protection of human health and the environment (CERCLA §121).
Because no remedial actions are necessary, no statutory determinations or remedial
actions are necessary.
10.0 STATUTORY DETERMINATIONS
A total of 111 SWMUs were determined not to pose potential risks to human health
and the environment. Therefore, no remedial actions are necessary to ensure
protection of human health and the environment.
P/SHAWE/OU2ROD.R3
02/06/96 108
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Table 9-1. No Further Action Sites (Page 1 of 7)
Site/SWMU
Number
S2
PS1
A10
A14
S5
A16
A31
S38
A-54
A-l
A-2
A-3
A-6
PS-2
A7
A8&A9
Description
Pest control,
Equipment Storage
Pest control shop
Railroad Car
Maintenance
Vehicle Maintenance
Shop
Spray paint booths
Battery Shop;
Vehicle Maintenance
Vehicle Maintenance
Buried boxcar of
rations
Catch basins; water
feed lot/watering area
Photographic Shop -
Administration Bldg
Photographic Shops/
Printing Plate
Reproduction
Blacksmith Shop
Welding
Paint Shop Storage
Sign Shop
Reproduction
Comments
Building used only for equipment storage; no use of hazardous
materials at this site
No sampling planned; all pesticide mixing completed in building; no
outside storage of hazardous materials, no releases reported
Sampling performed per work plan; no contamination found; non-fuel
UST (9,11) being remediated by SHARPE
Sampling performed per work plan; no contamination found; fuel
UST (15) being remediated under SHARPE contract
Sampling performed with sewerline investigation; surrounding area
paved; wastes to IWTP
Sampling performed with sewerline investigation; surrounding area
paved; wastes to IWTP; non-fuel UST 20 removed (no remediation
required)
Samples taken per work plan - 2 borings; no contamination found
No soil gas > 10 ppb
Not SHARPE property; feedlot on adjacent land; SHARPE replaced
drinking water well for landowner
Fuel UST near T-4; no contamination found
Wastes to IWTP; covered during storm sewer survey
Iron and iron alloys used at this location; not expected to be
environmental problems
No large scale use of solvents; soil gas < 10 ppb; no further
assessment based on soil gas and nature of operation
SWMU is a building; area paved; paint stored but not used at this site
SWMU is a building; building demolished; area paved; entire area
around slab paved - no stains; covered during storm sewer
investigation
No materials stored outside bldg; liquid wastes to IWTP; covered
during storm sewer investigation; tank 8 (fuel UST) removed April
1988 • no contamination; solid waste not hazardous - likely disposed
in SB; soil gas < 10 ppb; Bldg 308 - fuel UST #33 removed March
1990 - no remediation required based on sampling; UST #34 removed
April 1990 - remediation required - currently under SHARPE contract
P/SHARPE/OU2ROD-V.R2.1
11/02/95
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Table 9-1. No Further Action Sites (Page 2 of 7)
Site/SWMU
Number
Description
Comments
All
Duplicating
No materials stored outside bldg; liquid wastes to IWTP; covered
during storm sewer investigation; fuel UST 12 removed April 1990 -
remediation required and under SHARPE contract (1993-94)
A15
Water Plant and
Water Quality
Laboratory
Soil gas < 10 ppb; liquid wastes to IWTP; covered during storm
sewer investigation; fuel USTs 13 & 14 removed May and March
1990; neither required remediation based on sampling results
A18
Fire Station
Neither solid nor liquid HTW-generated; HM not used in significant
quantities; extinguishers contained CC14; soil gas < 20 ppb; fuel
UST removed prior to 1986; old tank site under building addition;
SHARPE contract will install DC MW
S6
Former Taxi
Dispatch
Small office used to dispatch taxis; building demolished
in early 1970's; soil gas < 20 ppb; paved surfaces
around building; no reported releases or generation of
HW
A-22
Radiator Repair Shop
Radiators drained prior to delivery; liquid wastes to IWTP; covered
during sewer line investigation; solid wastes disposed through DPDO
or landfilling/ burning in SB area; area around bldg paved; UST 27
associated with this bldg; soil gas survey and downgradient
monitoring wells discussed with S6
A35
Printing Shop
All wastes to IWTP; soil gas < 40 ppb; covered during sewer line
investigation
A36-38
Brush Application of
Oils for Preservation/
Welding
All wastes to IWTP; soil gas < 24 ppb; covered during sewer line
investigation
A40
Gas Station
All tanks tight per tank test results; soil gas < 10 ppb;
no inventory loss, therefore no further investigation
required; USTs continuously monitored LAW Title 23
CCR
A48
Metals, plastic,
piping work, silk
screening
All wastes to IWTP; soil gas < 10 ppb; covered during sewer line
investigation
A23-26
Support Shops for
Electrical, Hydraulic,
Misc. Repair
No sampling planned; SWMU is a building surrounded by concrete
pavement; soil gas downgradient is < 100 ppb; within capture zone
of NB treatment system; borings 100 feet south of bldg all clean;
extraction well NA-10 within SO .feet; A23 drains to IWTP; covered
during sewer line investigation; A24 contains PCB sump - sump has
been drained and soil will be sampled beneath sump
S23
Defueling Facility
Large internally drained slab; rainwater drains to IWTP; covered
during sewer line investigation; fuel drained from aircraft routed to
two USTs (56,57); tanks removed April 1990; no remediation
required based on sampling results; soil gas < 60 ppb
P/SHAKPE/OU2ROD-V.R2.2
11/02/95
110
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Table 9-1. No Further Action Sites (Page 3 of 7)
Site/SWMU
Number
Description
Comments
A12
Steam Cleaning/Wash
Rack at Vehicle
Maintenance Shop
No solid wastes generated at building; washwater routed to IWTP.
Soil gas indicated that TCE is not present in detectable
concentrations.
AS
Plumbing, painting,
welding, pest control
No sampling per work plan; SWMU is a building; paved area; nearby
tanks removed under SHARPE contract - remediate if required; soil
boring and water results in PAR
A13
Metal shop;
washrack
Monitoring wells in area; site characterized during sewer line
investigation; SWMU is a building; soil gas (206 ppb); North Balloon
capture zone
S4
Paint Spray Booth
Bldg no longer exists; paved area; runoff to IWTP; no A zone aquifer
located adjacent to site; covered in sewer study; 2 borings for S31 -
188 ppm for lead at 15 ft; no VOCs in soil or soil gas; North Balloon
capture zone
A17
Ground stains ID
from aerial photo,
large area in SB
"A" Text pages from work plan addendum; 8 soil borings - all ND;
soil gas < 10 ppb in area - 2156 ppm (100 ft away); see non-fuel
UST discussion as separate issue. This site is targeted for soil gas
characterization, as described in Section 9.2.1.
PS3
Motor pool; vehicle
maintenance &
storage
SWMU is a building; no sampling per work plan; paved area; no soil
gas hits in area; wastes from area routinely disposed at other sites;
North Balloon capture zone
A19
Heavy equipment
engine shop
No sampling planned; SWMU is a former building; outside area
paved; no soil gas hits downgradient; wastes drummed and disposed
in other locations; extraction wells NA 4, 9, 10
S7
Sandblasting booths -
performed in building
No sampling planned because SWMU is a building; outside area
paved; no soil gas hits downgradient; wastes disposed in North
Balloon area (S #26)
S8
Steam cleaning pad
Boring performed downgradient of slab (S8); no VOCs detected in
capture zone of NB (well NA 5); wastes to IWTP - covered during
sewer investigation
S9
Steam cleaning pad
3 borings in pad 669 (washrack); borings sampled for VOCs,
semi-VOCs, metals; results insignificant; SB capture zone;
contaminated rain water & runoff discharged to IWTP
A20
Heavy Equip
Component Repair
Bldg
No sampling planned; SWMU is a building surrounded by concrete
pavement; soil gas downgradient is < 100 ppb; see S27 for disposal
within capture zone of NB treatment system; borings 100 feet south
of bldg all clean; extraction well NA-10 within 50 feet
A21
Heavy Equip Repair,
Vehicle Maint Bldg
No sampling planned; SWMU is a building surrounded by concrete
pavement; soil gas downgradient is < 100 ppb; within capture zone
of NB treatment system; borings 100 feet south of bldg all clean;
extraction well NA-10 within 50 feet; see S27 for disposal of wastes
P/SHARPE/OU2ROD-V.R2J
11/02/95
111
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Table 9-1. No Further Action Sites (Page 4 of 7)
Site/SWMU
Number
A27
S10
A28
Sll
A30
A32-34
A39
A41
A42
A43
A4445
S14
S15-17
Description
Support shop for
electrical,hydraulic,w
elding
Dip Tank
Parts cleaning/
stripping
Dip Tank for
preservatives
Cocooning Shed -
preservatives
Storage of Lensatic
Compasses
Luminous dial
sketching sets storage
area
Cleaning, packaging,
preservation of parts
Paint stripping on
concrete slab and
washrack
Metal stripping,
degreasing,
refinishing/ paint
booth
Luminous fact wrist
compass storage
Stonnwater liftstation
sump: received
Stonnwater from
380,403,659
Hazardous materials
storage (for
distribution)
Comments
Surface soil sample taken south of site; lead levels less than
remediation levels (129 ppm, at 0 to 6 in); soil gas 2156 ppb TCE &
TCE ND in soil, South Balloon capture zone. This site is targeted
for soil gas characterization, as described in Section 9.2.1.
Dip Tank located outside near 174 washrack (S8); boring performed
at site (S8); lead at 75 ppm (0 to 5 ft); very low level VOC's
detected; North Balloon capture zone (NA5)
No sampling planned for site per work plan; building & OWS
demolished and removed in 1990 - including soil excavation to 25 feet
at site; work performed by DieDe Construction; NA 10 nearby;
within North Balloon capture zone
Soil gas reading near 205 was 100 ppb; soil boring Sll installed to
investigate soil gas - no contaminants site is indoor dip tank; 211 dip
tank considered as A#37
SWMU is a building; no sampling planned for site; soil gas in area
< 100 ppb or > 16 ppb; no waste disposal here; waste taken to S28
Indoor storage of lensatic compasses for issue to units; compasses not
manufactured, repaired or calibrated; warehouses demolished in 1976
No sampling planned for this site; indoor warehouse storage of
luminous sketching sets
No sampling planned for this site; indoor warehouse storage of
various commodities; considered in stormdrain investigation
2 soil borings performed at this site, low-levels of BTEX detected (5
ppm) at 5 to 10 ft, ND at 10 to 15 ft; soil gas <100 ppb
downgradient
SWMU is a building ; near PS4; 1 boring and 1 downgradient well
installed (452 A) sample taken from sump (PS 4); boring showed low
level chloroform, MW ND; waste disposal see PS 4 & S28
No sampling planned; SWMU is a building where these items were
stored (indoors)
No sampling planned; soil gas levels < 100 ppb; lift station for
Stonnwater drainage currently in use; addressed by storm sewer
survey
No sampling planned; SWMU is building (materials stored inside);
soil gas levels < 10 ppb; no waste generated at this site
P/SHARJPE/OU2ROD-V.R2.4
11/02/95
112
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Table 9-1. No Further Action Sites (Page 5 of 7)
Site/SWMU
Number
SIS
A46
S19
A47
A49
A50-52
S20-22
PS6
S24
PS7
S25
S27
Description
Burning Pits
Parts painting
Wash Apron
Packaging Building
Aircraft, minor
repair
Engine testing cells
in buildings 611-613
Storage of
flammable,
compressed gases
Care & preservation;
repair and storage
area
Floor drains, wash
rack, sumps
Battery shop; acid
neutralization pit
Chemical storage,
processing &
distribution
Waste Oil drained
from care &
preservation
Comments
GPR performed to locate pit; soil boring in center of pit - no
contamination detected; 1994 soil borings to 15 feet indicate Pb +Cr
< PRGs
No sampling planned; spray paint booth inside warehouse 486; soil
gas < 25 ppb; part of storm sewer survey (IWTPS)
No sampling planned; soil gas < 10 ppb; part of storm sewer survey;
within Central Area capture zone
SWMU is building where packaging of parts occurred; no soil
sampling planned; high soil gas reading of 420 ppb; no waste
disposed; near S35 & PS10. This site is targeted for soil gas
characterization, as described in Section 9.2.1.
SWMU is shed where aircraft minor repair took place; paved area; no
sampling planned; soil gas < 14 ppb or less; part of storm sewer
survey; see IWTP & S34 for waste disposal
SWMU is building where engine testing occurred; UST 47 removed
1990 - no contamination; OWS removed October 1993 - test results
pending; soil gas < 10 ppb
No sampling planned; soil gas < 10 ppb; flammable, compressed
gases stored in these sheds; storage at 647 - see A17
SWMU is a building; Soil borings (2) installed near soil gas hits of
2200 ppb and 3000 ppb; no contamination found in borings in South
Balloon capture zone
Paved, IWTP, elev. SG 1190 ppb, no contamination in 2 borings.
This site is targeted for soil gas characterization, as described in
Section 9.2.1.
1 boring at site - lead contamination at 10-15 ft (150 ppm); within
capture zone of South Balloon treatment system; extraction wells
(A8 & A6) sampled for metals (non-detect)
No sampling planned; soil gas < 10 ppb; SWMU is building where
chemical storage occurred; UST at site removed in 1990 - no
contamination found; no waste generated
Nine soil borings and 5 surface soil samples taken; no significant
contamination found (minor BTEX contamination); soils in North
Balloon frequently aerated due to heavy equipment tests in area within
North Balloon capture zone; extraction well NA-10 within 50 feet
P/SHARPE/OU2ROD-V.R2.5
U/02/95
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Table 9-1. No Further Action Sites (Page 6 of 7)
Site/SWMU
Number
PS8
S32
S35
PS10
S37
PS9
PS11
PS 12
PS 13
A57-63
ASS
AS6
Description
Sandblasting wastes
spread on ground
Solvent storage yard,
S of IWTP oxidation
pond
Drummed waste
storage yard
Open Storage Area
Buried wreck
helicopter
Storm sewers
PSllisa
combination of S12
&S32
Open storage in NB;
combination of S26
&S27
Includes
A57,A63,A72,A73;
Open Storage Area
Areas located around
Bldg 649
Canvas shed,
equipment overhaul,
cleaning, welding
Runway Extension
(same as S34)
Comments
Four shallow borings in area (same borings as done for S28); no
significant contamination found; 300 cubic yards of metals
contaminated soil removed in 1988 adjacent to Bldg 605 (volume 3,
appendix I, 1988 RI) per RCRA permit
Boring in area; no significant contamination found; SG < 10
High soil gas in area (> 1000 ppb); 4 borings at high soil gas
location - no significant contamination; SWMU is completely
contained within PS 10. This site is targeted for soil gas
characterization, as described in Section 9.2.1.
4 borings installed consistent with high soil gas; borings field
screened with PID: 2 negative, 2 analyzed - no contamination found
above detection limits
Soil gas < 10 ppb; buried with body parts; no sampling planned at
this site; ground water in 415a show 0.6 ppb TCE
Extensive storm sewer investigation performed conclude that the only
analyte detected in soil gas was toluene. Soil samples analyzed for
metals and VOCs were reported as non-detect.
See S12 and S32 above
See S26 and S27
Ground stains identified on aerial photographs; 2 borings correspond
to high soil gas locations (> 1000 ppb) - no significant contamination
found (results in 1988 RI); 404A clean; no evidence of contaminant
sources. A portion of this site is targeted for soil gas
characterization, as described in Section 9.2.1.
Soil gas sampling performed in entire ground stain area; borings
correspond to high soil gas readings (see PS 13); borings installed
around Bldg 649 (see PS5); extraction wells located within and
downgradient of these areas (A-7, 8, B-l, C-l, A-l, 3,5); MW
cluster 418 downgradient
Soil gas < 10 ppb in area; no sampling per work plan
Same as S34
P/SHARPE/OU2ROD-V.R2.6
11/02/95
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Table 9-1. No Further Action Sites (Page 7 of 7)
Site/SWMU
Number
A64-75
A4
S31
A29
Description
66,69,70,71 - PS 14;
67 - S26; 72,73 -
PS13
Sheet metal,
plumbing, painting
Ground stain adjacent
to building
Wash rack
Comments
A64 - Extraction well A3 & soil gas < 100 ppb; A65 - MW 449C &
soil gas < 100 ppb; A74 & A75 - soil gas < 10 ppb; A68 -
groundstain near 404, see S3S
No sampling planned per work plan; paved area; SWMU is a
building; no waste disposal; see IWTP; and S28
North Balloon system capture zone; 4,9 being two borings, complete
to 15 ft (at 5-ft intervals) were completed; maximum constituent
reported was lead, reported as 188 mg/lcg in one sample; quarterly
sampling of nearby extraction wells NA-4, NA-9, and NA-10 have
reported lead at concentrations below detection limits (0.005 /tg/L);
quarterly sampling was initiated in January 1994; this summary is
based on data through six quarters.
No sampling planned for site; soil gas in area > 16 ppb and < 100
ppb; non-fuel UST 70 removed Oct 1993 - Site approved for closure
by Board
P/SHARPE/OU2ROD-VJ12.7
11/02/95
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Because no remedial actions are necessary, no statutory determination of remedial
actions are necessary for the 111 SWMUs.
The selected remedies for lead- and chromium-contaminated soils and TCE-
contaminated soils satisfy the statutory requirement of Sec. 121 of CERCLA, as
amended by SARA, in that the following mandates are attained:
1. The selected remedies are protective of human health and the environment;
2. The selected remedies comply with federal and state ARARs;
3. The selected remedies are cost effective in the fulfillment of the nine
CERCLA evaluation criteria through remediation of the contaminated soil in
a reasonable period of time;
4. The selected remedies utilize permanent solutions and alternative treatment
technologies or resource recovery technologies to the maximum extent
practicable; and
5. The selected remedies satisfy the preference for treatments that reduce
toxicity, mobility, or volume as principal elements for TCE-contaminated
soils, and explain why this preference cannot be practicably satisfied for
lead- and chromium-contaminated soils.
The following sections describe how the selected remedies satisfy each of the statutory
requirements for each of the two selected alternatives.
10.1 LEAD- AND CHROMIUM-CONTAMINATED SOILS
10.1.1 PROTECTIVE OF HUMAN HEALTH AND ENVIRONMENT
The selected alternative is protective of human health and the environment hi that
soils hi excess of cleanup standards would be removed from the site, through
engineering controls. As described for Alternative 4B (Offsite Disposal), all soil with
lead and chromium above cleanup standards will be excavated and disposed of at an
offsite landfill. This action provides long-term effectiveness in that it will remove
pathways which could cause exposure of the onsite adult worker to soils with levels of
lead or chromium in excess of the cleanup standard. It is not possible to quantify the
reduced risks associated with implementation of the alternative, as:
1. Chromium was not considered a factor in the HI calculations; and
2. There is currently no cancer slope factor available to calculate risks
associated with lead.
P/SHARPE/OU2ROD.R3
02/06/96 116
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10.1.2 COMPLY WITH ARARs
The selected remedy will comply with all federal and state ARARs. No ARAR
waivers will be necessary.
With proper planning and implementation, the remedial action which implements this
alternative would comply with the following action-specific ARARs:
• Water Quality Control Plan (Basin Plan) for CVRWQC - Defines
beneficial use levels for constituents in groundwater. Beneficial use levels
for chromium and lead are equivalent to MCLs.
• State Water Resource Control Board Resolution No. 88-63, "Sources of
Drinking Water Policy" as contained in the CVRWQCB Water Quality
Control Plan - Specifies that with certain exceptions, all ground and
surface waters have the beneficial use of municipal or domestic water use.
• 22 CCR Div. 4.5, Chapter 14, Article 6, §§ 66264.90 et seq. - Detection
monitoring and evaluation monitoring programs for lead and chromium will
be instituted with this program. If monitoring data indicates the beneficial
uses of groundwater are not being protected, corrective action may be
required.
ARARs are listed in Table 10-1.
10.1.3 COST EFFECTIVE
The selected remedy, offsite disposal, is cost-effective because it has been determined
to provide overall effectiveness proportional to cost, the net present worth value being
$683,000. Although more costly then the capping alternative ($388,000), the
preferred alternative provides for permanent removal of waste from the site and more
assurance of protection of human health and environment. Fixation/Solidification was
the third most costly alternative, costing approximately $1,015,000 and involved
keeping treated waste onsite under a cap requiring perpetual maintenance. The most
costly alternative, Chemical Extraction/Soil Washing, was estimated to cost
$1,773,000. There were no assurances that the technology is capable of achieving the
cleanup standards established for cleanup.
P/SHARPE/OU2ROD.R3
02/06/96 117
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Table 10-1. ARARs for Lead- and Chromium-Contaminated Soils
ARAR
DESCRIPTION
COMPLIANCE
Water Quality Control
Plan (Basin Plan) for
the RWQCB, CVR
Applicable
Specific applicable portions of the Basin Plan
include beneficial uses of affected water bodies
and water quality objectives to protect those
uses. Levels of constituents in residual
contaminated soils that may affect water quality
must not result in water quality exceeding water
quality objectives.
The existing groundwater
treatment systems are
capturing and treating the
VOC plume. All soils with
designated levels of metals are
located within capture zones of
one of the three groundwater
treatment plants. Groundwater
will be monitored to assure the
beneficial use of groundwater
is protected.
22 CCR Div. 4.5,
Chapter 14, Article 6
§§ 66264.90 et seq.
Relevant and
Appropriate
Requires monitoring to ensure there are no
releases from waste management units. If
releases are detected, appropriate corrective
action must be taken to achieve compliance with
water quality protection standards.
Groundwater downgradient of
soils with designated levels of
metals will be monitored to
assure protection of the
beneficial uses of
groundwater.
State Water Resource
Control Board
Resolution No. 88-63,
"Sources of Drinking
Water Policy" (as
contained in the
RWQCB's Water
Quality Control Plan)
Applicable
Policies adopted by the State and Regional
Water Boards. Specifies that, with certain
exceptions, all groundwater and surface waters
have the beneficial use of municipal or domestic
water supply.
Remediation of lead- and
chromium-contaminated soils
must also protect the beneficial
uses of groundwater at
SHARPE.
The parties to this Record of Decision do not agree on whether State Water Resources Control Board (SWRCB)
Policies and Procedures for Investigation and Cleanup and Abatement of Discharges Under Water Code
Section 13304, June 1992, Resolution No. 92-49 is an ARAR for this site. The State's position is that SWRCB
Resolution No. 92-49 is an applicable requirements for remedial actions for groundwater and soil where there is
an impact, or threaten impact (including impacts from soils) to be beneficial uses of waters of the State.
SHARPE has not identified Resolution No. 92-49 as an ARAR. The State, however, has decided not to dispute
mis decision since the action proposed by SHARPE will substantially comply with Resolution No. 92-49.
Further, the Parties to this ROD do not agree fully on the citation of 22 CCR, Div 4.5, Chapter 14, Article 6,
Section 66264.90 et seq. as an ARAR. The State's position is that the entire article is needed to determine
specific monitoring and response actions. However, USEPA's position is that Article 6, in its entirety, is overly
broad and not sufficiently specific to be considered an ARAR. Inclusion of the entire Article 6 in the ARARs
table will not affect EPA's determination to be made under Section 9.1.4.
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10.1.4 UTILIZATION OF PERMANENT SOLUTIONS AND
ALTERNATIVE TREATMENT (OR RESOURCE RECOVERY)
TECHNOLOGIES TO THE MAXIMUM EXTENT PRACTICABLE
The selected remedy provides the best balance of tradeoffs among the alternatives
evaluated with respect to the evaluation criteria. A comparison of the alternatives
relative to one another is presented in Sec. 8.0. When compared to Alternatives 1C
(Asphalt Cap), 2A (Fixation/Solidification), 2B (Chemical Extraction/Soil Washing),
and 5A (No Action), on the basis of short-term effectiveness, long-term effectiveness,
reduction of TMV, implementability, compliance with cleanup guidelines, and
protection of human health and the environment, Alternative 4B (Offsite Disposal)
was evaluated to be an equivalent or better alternative for soil remediation.
Alternative 1C (Asphalt Cap) was not acceptable to the State. On the basis of cost,
Alternative 4B (Offsite Disposal) was estimated to be the most cost-efficient of the
state-accepted alternatives for achieving the remedial objectives for the site soil
contamination. With the exception of Alternative 5A, the remaining four action
alternatives comply with the threshold criteria of being protective of human health and
the environment and ARAR compliant.
While the selected alternative does not include the use of alternative treatment
technologies (or resource recovery technologies), it does provide for the most reliable
permanent solution for lead- and chromium-contaminated soils onsite.
This alternative provides protection of human health and the environment by lowering
the contaminant concentrations in the site soil. This alternative can achieve and
comply with all ARARs.
The state has accepted the FS and endorses implementation of Alternative 4B (Offsite
Disposal) to remediate lead- and chromium-contaminated soil.
The community did not comment on any of the remedial action alternatives.
10.1.5 PREFERENCE FOR TREATMENT AS A PRINCIPAL ELEMENT
Alternative 4B (Offsite Disposal) does not satisfy the statutory preference for
treatment as a principal element. Alternatives 2A (Fixation/Solidification) and 2B
(Chemical Extraction/Soil Washing), due to the technical complexity of the treatment
methods, are not as reliable as Alternative 4B (Offsite Disposal) hi the complete
removal and reduction in health and environmental risk factors. The present value
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cost for Alternative 4B (Offsite Disposal) was also estimated to be significantly less
than alternatives utilizing treatment.
10.2 TCE-CONTAMINATED SOILS
10.2.1 PROTECTIVE OF HUMAN HEALTH AND ENVIRONMENT
TCE-contaminated soils do not pose a risk to human health and the environment.
Risks to exposure were calculated to be between the EPA recommended risk range of
104 to 1Q*. His were estimated to be, less than one. Implementation of the selected
remedy, therefore, is not being recommended to decrease risks to human health and
the environment. Rather, the selected remedy will minimize the amount of TCE
allowed to migrate from contaminated soils to groundwater through treatment, and is
a source removal action. Implementation of this alternative will not pose unacceptable
risks or cross-media impacts. This alternative will reduce the amount of time and cost
to remediate groundwater currently being treated under the authority of the
groundwater ROD (GUI).
10.2.2 ARARs
The selected remedy will comply with all federal and state ARARs. No ARAR
waivers are necessary.
With proper planning and implementation, the remedial action which implements this
alternative would comply with the following action-specific ARARs:
• Air Pollution Control District Rules and Regulations (Rule 2201) - new
emission sources must comply with implementation of Best Available
Control Technology (BACT). Offgases from the treatment system will be
treated with gas-phase carbon adsorption prior to being discharged to the
atmosphere.
The following ARARs apply to areas where TCE-contaminated soils are determined to
be a potential threat to water quality:
• Water Quality Control Plan (Basin Plan) for CVRWQCB - Defines
beneficial use levels for constituents in groundwater. Beneficial use levels
for TCE are equivalent to MCLs.
• State Water Resource Control Board Resolution No. 88-63, "Sources of
Drinking Water Policy" as contained in the CVRWQCB Water Quality
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Control Plan -- Specifies that with certain exceptions, all ground and
surface waters have the beneficial use of municipal or domestic water use.
• 22 CCR Div. 4.5, Chapter 14, Article 6, §§ 66264.90 et seq. ~ Detection
monitoring and evaluation monitoring programs for TCE will be instituted
with this program. If monitoring data indicates the beneficial uses of
groundwater are not being protected, corrective action may be required.
ARARs are listed hi Table 10-2.
10.2.3 COST EFFECTIVE
The selected remedy, ISV, is cost effective because it has been determined to provide
overall effectiveness proportional to its cost, the net present worth value being
$528,000. The estimated cost of the selected remedy was the least expensive
alternative (with the exception of the no-action alternative), an order-of-magnitude
less than the next-least-expensive alternative, Alternative 3A (LTTS) ($6,800,000),
yet the selected alternative provides comparable treatment efficiencies without the
need for excavating soils. Alternative 4A (Offsite Disposal), the second most costly
alternative at $23,000,000, although more expensive, did not utilize treatment. The
most expensive alternative, 2B (Onsite Incineration), with estimated costs two
orders-of-magnitude greater than the selected remedy ($137,000,000), is more costly
without yielding a significantly greater treatment efficiency.
10.2.4 UTILIZATION OF PERMANENT SOLUTIONS AND
ALTERNATIVE TREATMENT (OR RESOURCE RECOVERY)
TECHNOLOGIES TO THE MAXIMUM EXTENT PRACTICABLE
The selected remedy provides the best balance of tradeoffs among the alternatives
evaluated with respect to the evaluation criteria. A comparison of alternatives relative
to one another is presented hi Sec. 8.0. When compared to Alternatives 2B (Onsite
Incineration), 3A (LTTS), 4A (Offsite Disposal), and 5A (No Action), on the basis of
short-term effectiveness, long-term effectiveness, reduction of TMV,
implementability, compliance with cleanup guidelines, and protection of human health
and the environment, Alternative 2C (ISV) was evaluated to be an equivalent or better
alternative for TCE-contaminated soil remediation. On the basis of cost,
Alternative 2C (ISV) was estimated to be the most cost-efficient means of achieving
remedial objectives for the site soil contamination. Alternative 2C (ISV) has been
evaluated on a pilot-scale at SHARPE and has been proven effective. Alternatives 2B
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Table 10-2. ARARs for TCE-Contaminated Soils
ARAR
DESCRnTION
COMPLIANCE
Air Pollution Control
District Rules and
Regulations (Rule
2201}
Applicable
Specifies that new emission sources comply with
implementation of Best Available Control
Technology (BACT).
Offgases from the ISV VES
systems will be treated with
gas-phase carbon adsorption
prior to being discharged to
the atmosphere.
Water Quality Control
Plan (Basin Plan) for
the RWQCB, CVR
Applicable
Specific applicable portions of the Basin Plan
include beneficial uses of affected water bodies
and water quality objectives to protect those
uses. Levels of constituents in residual
contaminated soils that may affect water quality
must not result in water quality exceeding water
quality objectives.
The existing groundwater
treatment systems are
capturing and treating the
VOC plumes. Remediation
will be conducted at locations
where it is determined to be
cost effective for treatment.
22 CCR Div. 4.5,
Chapter 14, Article
6§§ 66264.90 el seq.
Relevant and
Appropriate
Requires monitoring to ensure there are no
releases from waste management units. If
releases are detected, appropriate corrective
action must be taken to achieve compliance with
water quality protection standards.
Groundwater downgradient of
TCE source areas will be
monitored to assess
compliance with MCLs.
State Water Resource
Control Board
Resolution No. 88-63,
"Sources of Drinking
Water Policy" (as
contained in the
RWQCB's Water
Quality Control Plan)
Applicable
Policies adopted by the State and Regional
Water Boards. Specifies that, with certain
exceptions, all groundwater and surface waters
have the beneficial use of municipal or domestic
water supply.
Remediation of TCE-
contaminated soils must
protect the beneficial uses of
groundwater at SHARPE.
Remediation will be conducted
at locations where it is
determined to be cost effective
for treatment.
The parties to this Record of Decision do not agree on whether State Water Resources Control Board (SWRCB)
Policies and Procedures for Investigation and Cleanup and Abatement of Discharges Under Water Code
Section 13304, June 1992, Resolution No. 92-49 is an ARAR for this site. The State's position is that SWRCB
Resolution No. 92-49 is an applicable requirements for remedial actions for groundwater and soil where there is
an impact, or threaten impact (including impacts from soils) to be beneficial uses of waters of the State.
SHARPE has not identified Resolution No. 92-49 as an ARAR. The State, however, has decided not to dispute
this decision since the action proposed by SHARPE will substantially comply with Resolution No. 92-49.
Further, the Parties to this ROD do not agree fully on the citation of 22 CCR, Div 4.5, Chapter 14, Article 6,
Section 66264.90 et seq. as an ARAR. The State's position is that the entire article is needed to determine
specific monitoring and response actions. However, USEPA's position is that Article 6, in its entirety, is overly
broad and not sufficiently specific to be considered an ARAR. Inclusion of the entire Article 6 in the ARARs
table will not affect EPA's determination to be made under Section 9.1.4.
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(Onsite Incineration) and 3A (LTTS) would require treatability testing prior to
implementation.
The state has accepted the FS and endorses implementation of Alternative 2C (ISV) to
remediate TCE-contaminated soil.
The community did not comment on any of the remedial action alternatives.
10.2.5 PREFERENCE FOR TREATMENT AS A PRINCIPAL ELEMENT
Alternative 2C (ISV) satisfies the statutory preference for treatment as a principal
element. This alternative involves the installation of extraction wells to recover TCE
vapors from soils. The TCE-laden vapor is transferred to gas-phase carbon, where the
TCE is removed prior to the air being discharged to the atmosphere. Gas-phase
carbon, when exhausted, is transported off site to a commercial reactivation facility,
where the carbon is regenerated and the TCE is destroyed.
11.0 REFERENCES
Department of Toxic Substances Control (DTSC). 1992. Supplemental Guidance for
Human Health Multimedia Risk Assessments of Hazardous Waste Sites and
Permitted Facilities. California EPA, Office of Science Advisor. Sacramento, CA.
Environmental Science and Engineering, Inc. (ESE). 1990. Remedial
Investigation/Feasibility Study, Sharpe Army Depot. Prepared for U.S. Army
Toxic and Hazardous Materials Agency, Aberdeen Proving Ground, MD.
Environmental Science and Engineering, Inc. (ESE). 1993. Remedial
Investigation/Feasibility Study at DDRW-SHARPE Site: Record of Decision,
Operable Unit 1. Prepared for U.S. Army Toxic and Hazardous Materials
Agency, Aberdeen Proving Ground, MD.
Environmental Science and Engineering, Inc. (ESE). 1994a. Remedial
Investigation/Feasibility Study at SHARP Site: Soils Feasibility Study'Report.
Prepared for U.S. Army Environmental Center, Aberdeen Proving Ground, MD.
P/SHARPE/OU2ROD.R3
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Environmental Science and Engineering, Inc. (ESE). 1994b. Remedial
Investigation/Feasibility Study at SHARPE Site: Soils Risk Assessment Report.
Prepared for U.S. Army Environmental Center, Aberdeen Proving Ground, MD.
Environmental Science and Engineering, Inc. (ESE). 1994c. Work Plan Addendum to
Evaluate Lead and Chromium at SHARPE Site. Prepared for U.S. Army
Environmental Center, Aberdeen Proving Ground, MD.
San Joaquin County Planning Department (SJCPD). 1987. General Land Use Plan to
1995. Department of Planning and Building Inspection, Stocton, CA.
U.S. Environmental Protection Agency (EPA). 1989a. Risk Assessment Guidance for
Superfund (RAGS), Vol. I, Human Health Evaluation Manual (Part A).
EPA/540/1-89/002.
U.S. Environmental Protection Agency (EPA). 1989b. Risk Assessment Guidance for
Superfund (RAGS), Vol. II, Ecological Health Evaluation Manual. Office of
Emergency and Remedial Response, Washington, DC. EPA/540/1-89/001.
U.S. Environmental Protection Agency (EPA). 1991a. Risk Assessment Guidance for
Superfund (RAGS). Volume 1: Human Health Evaluation Manual, Supplemental
Guidance: Standard Default Exposure Factors. OSWER Directive 9285.6-03.
U.S. Environmental Protection Agency (EPA). 1991b. Memorandum from Don R.
Clay, re: Update on OSWER Soil Lead Cleanup Guidance. Office of Solid Waste
and Emergency Response, Washington, DC. 29 Aug 1991.
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Defense Distribution Region West - SHARPE Site
Lathrop, California
RESPONSIVENESS SUMMARY
1.0 OVERVIEW
At the time of the public comment period, Defense Distribution Region West
(DDRW) recommended a preferred alternative in the Proposed Plan for remediation
of contaminated soils at SHARPE in Lathrop, CA.
The preferred alternative:
• for lead and chromium contaminated soils involves excavation arid off-site
disposal of soils that represent a threat to human health;
• for trichloroethene (TCE) contaminated soils involves using in-situ
volatilization to remove TCE from soils; treatment of these soils will be to a
level practicable, and will consider the costs of soil treatment and costs of
treating groundwater with the already operating groundwater treatment systems
at SHARPE;
• for 111 SWMU's is No Further Action.
Because no comments were received during the public comment period, DDRW
concluded that residents near SHARPE have no significant concerns regarding the
selection and/or implementation of any of the alternatives investigated by DDRW to
remediate contaminated soils.
2.0 BACKGROUND ON COMMUNITY INVOLVEMENT
Community interest in the SHARPE site dates to 1990 when SHARPE conducted the
first technical review committee (TRC) meeting, at which representatives of the
community were present. The TRC meeting was part of the Public Involvement
Response Plan (PIRP), which was completed in June 1989. The TRC Charter was
finalized in June 1990, the same month as the first TRC meeting. The last TRC
meeting was held on February 4, 1993. A public meeting, detailing the preferred
actions for this operable unit, was held on March 1, 1995.
3.0 SUMMARY OF PUBLIC COMMENTS
The public comment period was from February 22, 1995 to March 24, 1995. No
comments were submitted by the public.
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