PB98-964016
EPA 541-R98-072
October 1998
EPA Superfund
Record of Decision:
Pensacola Naval Air Station OU 1
Pensacola, FL
9/25/1998
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
REGION 4
ATLANTA FEDERAL CENTER
61 FORSYTH STREET
ATLANTA. GEORGIA 30303-8960
SEP 2 iq
CERTIFIED MAIL
RETURN RECEIPT REQUESTED
4WD-FFB
Commanding Officer
Naval Air Station Pensacola
190 Radford Boulevard
Pensacola, Florida 32508-5217
SUBJ: Record of Decision - Operable Unit 1
NAS Pensacola NPL Site
Pensacola, Florida
Dear Sir:
The U.S. Environmental Protection Agency (EPA) Region 4 has
reviewed the above subject decision document and concurs with the
selected remedy for the Remedial Action at Operable Unit 1. This
remedy is supported by the previously completed Remedial
Investigation, Feasibility Study and Baseline Risk Assessment
Reports.
The selected remedy consists of: institutional controls to
restrict groundwater use of the surficial zone of the sand and
gravel aquifer and prohibit intrusive activities within the
landfill boundary, an interception system to capture and treat
groundwater to reduce iron levels, and natural attenuation of the
organic compounds. EPA's concurrence assumes implementation of
land use restrictions, through a land use controls assurance and
implementation plan via a Memorandum of Agreement between the
Navy, State and EPA, will be executed within 90 days. This
remedial action is protective of human health and the
environment, complies with Federal and State requirements that
are legally applicable or relevant and appropriate to the
remedial action and is cost effective.
Internet Address (URL) • http://www.epa.gov
Recycled/Recyclable • Printed with Vegetable Oil Based Inks on Recycled Paper (Minimum 25% Poslconsumer)
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EPA appreciates the coordination efforts of NAS Pensacola
and the level of effort that was put forth in the documents
leading to this decision. EPA looks forward to continuing the
exemplary working relationship with NAS Pensacola and Southern
Division Naval Facilities Engineering Command as we move toward
final cleanup of the NPL site.
Sincerely,
Richard D. Green
Director
Waste Management Division
cc: Elsie Munsell, Deputy Assistant Secretary of the Navy
Ron Joyner, NAS Pensacola
Bill Hill, SOUTHDIV
David Grabka, FDEP
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FINAL RECORD OF DECISION
OPERABLE UNIT 1
NAS PENSACOLA
PENSACOLA, FLORIDA
SOUTHNAVFACENGCOM
Contract Number:
N62467-89-D-0318
CTO-083
Prepared for:
Comprehensive Long-Term Environmental Action Navy
(CLEAN)
Naval Air Station
Pensacola, Florida
Prepared by:
EnSafe Inc.
5724 Summer Trees Drive
Memphis, Tennessee 38134
(901) 372-7962
August 19, 1998
Release of this document requires prior notification of the Commanding Officer of the
Naval Air Station, Pensacola, Florida.
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Table of Contents
DECLARATION OF THE RECORD OF DECISION vii
1.0 SITE LOCATION AND DESCRIPTION 1
2.0 SITE HISTORY AND ENFORCEMENT ACTIVITIES 5
2.1 General Site History 5
2.2 Site-Specific History 5
2.3 Chronology of Events and Previous Investigations 6
2.4 Removal Action 11
3.0 HIGHLIGHTS OF COMMUNITY PARTICIPATION 12
4.0 SCOPE AND ROLE OF THE OPERABLE UNIT 13
5.0 SITE CHARACTERISTICS 16
5.1 Nature and Extent of Soil Contamination 16
5.2 Nature and Extent of Ground water Contamination 16
5.3 Nature and Extent of Sediment and Surface Water Contamination 17
5.4 Fate and Transport 21
5.4.1 Sources of Contamination 21
5.4.2 Contaminant Migration 22
6.0 SUMMARY OF SITE RISKS 29
6.1 Chemicals of Potential Concern 29
6.2 Exposure Assessment 31
6.2.1 Current Exposure 31
6.2.2 Future Exposure 32
6.3 Toxicity Assessment 33
6.4 Risk Characterization 41
6.5 Soil Performance Standards for Groundwater Protection 43
6.6 Risk Uncertainty 45
6.7 Human Health Risk Summary 48
6.8 Ecological Considerations 50
7.0 DESCRIPTION OF THE REMEDIAL ALTERNATIVES 52
7.1 Alternative 1: No Action 53
7.2 Alternative 2: Natural Attenuation 55
7.3 Alternative 3: Capping 60
7.4 Alternative 4: Groundwater Extraction with Treatment for the
Entire Landfill 61
7.5 Applicable or Relevant and Appropriate Requirements 66
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8.0 COMPARATIVE ANALYSIS OF ALTERNATIVES 71
8.1 Threshold Criteria 73
8.1.1 Overall Protection of Human Health and the Environment 73
8.1.2 Compliance with ARARs 74
8.2 Primary Balancing Criteria 75
8.2.1 Long-term Effectiveness and Permanence 75
8.2.2 Reduction of Toxicity, Mobility, or Volume Through Treatment ... 76
8.2.3 Short-term Effectiveness 77
8.2.4 Implementability 77
8.2.5 Cost 78
8.3 Modifying Criteria 78
9.0 THE SELECTED REMEDY 80
9.1 Source Control 80
9.2 Monitoring .81
9.3 Compliance Testing 81
10.0 STATUTORY DETERMINATIONS 83
10.1 Protection of Human Health and the Environment 83
10.2 Attainment of the ARARs 83
10.3 Cost-Effectiveness 84
10.4 Use of Permanent Solutions to the Maximum Extent Practicable 85
10.5 Preference for Treatment as a Principal Element 85
11.0 DOCUMENTATION OF NO SIGNIFICANT CHANGES 86
12.0 REFERENCES 87
List of Figures
Figure 1-1 Site Location Map 2
Figure 1-2 Site Map 3
Figure 5-1 Groundwater Area of Concern 18
Figure 5-2 Surface Water Area of Concern 20
Figure 7-1 Areas of Concern 54
List of Tables
Table 6-1 Chemicals of Potential Concern 30
Table 6-2 Exposure Point Concentrations 34
Table 6-3 Parameters Used to Estimate Potential Exposures for Current Land Use
Receptors 36
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Table 6-4 Parameters Used to Estimate Potential Exposures for Future Land Use
Receptors 38
Table 6-5 Toxicological Database Information for Chemicals of Potential Concern ... 40
Table 6-6 Risk and Hazard for Identified COCs and Pathways of Concerns 44
Table 6-7 Remedial Goal Options for Shallow/Intermediate Groundwater 49
Table 6-8 Remedial Goal Objectives for Deep Groundwater 51
Table 7-1 Site 1 — Remedial Objectives 53
Table 7-2 Potential Location-Specific ARARs for the Selected Remedy 68
Table 7-3 Potential Action-Specific ARARs for the Selected Remedy 69
Table 7-4 Potential Chemical-Specific ARARs for the Selected Remedy 70
Table 8-1 Cost Comparison for Alternatives 79
Table 9-1 Performance Standards for Groundwater 82
Appendix A
Appendix B
List of Appendices
Glossary
Responsiveness Summary
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List of Abbreviations
The following list contains many of the abbreviations, acronyms and symbols used in this
document. A glossary of technical terms is provided in Appendix A.
AOC Area of Concern
ARAR Applicable or Relevant and Appropriate Requirement
bis below land surface
BRA Baseline Risk Assessment
GDI Chronic Daily Intake
CEC Cation exchange capacity
CERCLA Comprehensive Environmental Response, Compensation, and Liability
Act
CG Cleanup Goal
COC Chemical of Concern
COPC Chemical of Potential Concern
CSF Cancer Slope Factor
CY Cubic Yard
E&E Ecology & Environment, Inc.
ED Exposure Duration
EPC Exposure Point Concentration
FDER Florida Department of Environmental Regulation (since renamed Florida
Department of Environmental Protection [FDEP])
FFA Federal Facilities Agreement
FGGC Florida Groundwater Guidance Concentration
FFS Focused Feasibility Study
FOTW Federally Owned Treatment Works
FPDWS Florida Primary Drinking Water Standard
FS Feasibility Study
FSDWS Florida Secondary Drinking Water Standard
G&M Geraghty & Miller, Inc.
gpm gallons per minute
HEAST Health Effects Assessment Summary Tables
HI Hazard Index
HQ Hazard Quotient
HRS Hazard Ranking System
IV
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List of Abbreviations (Continued)
IAS Initial Assessment Study
ILCR Incremental Lifetime Cancer Risk
IRIS Integrated Risk Information System
LURA Land Use Restriction Agreement
Iwa Lifetime Weighted Average
MCL Maximum Contaminant Level
MCLG Maximum Contaminant Level Goal
NACIP Navy Assessment and Control of Installation Pollutants
NAS Naval Air Station
NCP National Contingency Plan
NEESA Naval Energy and Environmental Support Activity
NPDES National Pollutant Discharge Elimination System
NPL National Priorities List
O&M Operation and Maintenance
OU Operable Unit
PAH Polyaromatic Hydrocarbon
PCB Polychorinated Biphenyl
ppb part per billion
ppm part per million
PVC polyvinyl chloride
PWC Public Works Center
RAB Restoration Advisory Board
RCRA Resource Conservation and Recovery Act
RfD Reference Dose
RGO Remedial Goal Option
RME Reasonable Maximum Exposure
RI Remedial Investigation
ROD Record of Decision
SARA Superfund Amendments and Reauthorization Act of 1986
SDWA Safe Drinking Water Act
SMCL Secondary Maximum Contaminant Level
SVOC Semivolatile Organic Compound
SWMU Solid Waste Management Unit
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List of Abbreviations (Continued)
TBC To-be-considered
TOC Total Organic Carbon
TRC Technical Review Committee
UCL Upper Confidence Limit
USEPA U.S. Environmental Protection Agency
VOC Volatile Organic Compound
WBZ Water-bearing Zone
VI
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DECLARATION OF THE RECORD OF DECISION x
Site Name and Location
Operable Unit 1, Site 1, Sanitary Landfill
Naval Air Station Pensacola
Pensacola, Florida
Statement of Purpose
This decision document (Record of Decision), presents the selected remedy for Operable Unit 1
at the Naval Air Station Pensacola, Pensacola, Florida. The remedy was developed in accordance
with the Comprehensive Environmental Response, Compensation and Liability Act of 1980
(CERCLA), as amended by the Super-fund Amendments and Reauthorization Act of 1986 (SARA).
42 U.S.C. § 9601 et seq., and to the extent practicable, the National Contingency Plan (NCP),
40 Code of Federal Regulations Part 300.
This decision is based on the administrative record for Operable Unit 1 at the Naval Air Station
Pensacola.
The United States Environmental Protection Agency and the Florida Department of Environmental
Protection concur with the selected remedy.
Assessment of the Operable Unit
Actual or threatened releases of hazardous substances from Operable Unit 1, if not addressed by
implementing the response action selected in this Record of Decision (ROD), may present an
imminent and substantial endangerment to public health or the environment.
Description of the Selected Remedy
This action is the first and final action planned for the operable unit. This alternative calls for the
design and implementation of response measures to protect human health and the environment.
The action addresses the sources of contamination as well as soil and groundwater contamination.
The major components of the remedy are:
• Institutional controls imposed in accordance with the Land Use Restriction Agreement
(LURA) among the Navy, EPA and FDEP to restrict groundwater use of the surficial zone
of the Sand-and-Gravel Aquifer within 300 feet of the site
VU
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• Institutional controls imposed in accordance with the LURA to restrict intrusive activities
within the landfill boundary without prior approval from the NAS Pensacola
Environmental office
• Annual review of the institutional controls and certification that the controls should remain
in place or be modified to reflect changing she conditions
• Groundwater monitoring program to ensure that natural attenuation processes would be
effective
• A review during which the Navy would determine whether groundwater performance
standards continue to be appropriate and if natural attenuation processes are effective
• Continued groundwater monitoring at regular sampling intervals after performance
standards are attained. The groundwater monitoring program would continue until
continued attainment of the performance standards has been achieved and the alternative
remains protective of human health and the environment.
• A groundwater interception system to capture the contaminated groundwater upgradient
of Wetland 3. The.intercepted groundwater will be treated to reduce iron levels to below
the applicable water quality standard. The treated groundwater will then be reintroduced
into Wetland 3.
• Concentrations of the organic compounds present in the groundwater and surface water
will be reduced through natural attenuation resulting from naturally occurring biotic and
abiotic processes which take place in the groundwater and surface water systems.
Statutory Determinations
The selected remedy is protective of human health and the environment, complies with federal and
state requirements that are legally applicable or relevant and appropriate to the remedial action,
and is cost-effective. This remedy utilizes permanent solutions and alternative treatment or
resource recovery technologies, to the maximum extent practicable, and satisfies the statutory
preference for remedies that employ treatment that reduces toxicity, mobility, or volume as a
principal element.
Because this remedy will result in hazardous substances remaining onsite, it will be reviewed
within five years after it commences to evaluate that it continues to adequately protect human
health and the environment.
Cappiffj.M. Denkler, NAS Pensacola Date
viii
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Final Record of Decision
NAS Pensacola Operable Unit 1
August 19. 1998
1.0 SITE LOCATION AND DESCRIPTION
Site 1 is an approximately 85-acre inactive sanitary landfill as shown on Figures 1-1 and 1-2. It
is from 8 to 20 feet above mean sea level and is densely vegetated with 15- to 25-foot tall planted
pines and natural scrub vegetation. Approximately one-half mile east of Forrest Sherman Airfield,
the site is within the north central portion of the Naval Air Station (NAS) Pensacola. The landfill
is bordered by an inland water body (Bayou Grande) to the north, by the A.C. Read Golf Course
to the east, and by areas of natural scrub vegetation to the west and south. Bayou Grande has been
classified by the Florida Department of Environmental Protection (FDEP) as a Class in water
body, indicating its use for recreation and maintaining a well-balanced fish and wildlife
population. Beyond the scrub vegetation, Taylor Road lies approximately 200 feet south of the
site.
Developed areas immediately north of the landfill include a Boy Scout camp, a nature trail, an
NAS Pensacola picnic area, and recreational Buildings 3553 and 3487. Also in this generally
developed area are two tidal-inlet ponds with associated wetlands. Other wetland areas are west
and east of the landfill; most are associated with marshy intermittent creeks. The nearest
residential area (base housing) is approximately 1,000 feet south of Site 1. Potable water for this
residential area and all of NAS Pensacola is supplied from Cony Station, approximately three
miles north of NAS Pensacola.
Because soil is highly permeable at the site, the potential for substantial contamination transfer via
surface water flow is limited. Two intermittent creeks lie within wetlands outside the landfill, as
shown on Figure 1-2. One creek, approximately 50 to 100 feet east of the landfill's central portion
(depending upon precipitation amounts), channels flow northeastward to the beaver pond
(Wetland 3). The other originates approximately 500 feet west of the landfill's central portion
and channels flow northwestward to Bayou Grande. Neither has been observed to receive direct
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cut/ or uooco
202
SCALE MILES
PENSACOLA
BAY
LEGEND
2500
SCALE
- PENCE
- RAILROAD
- SHORE LINE
2500
FEET
RECORD OF DECISION
SITE 1
NAS PENSACOLA
FIGURE 1-1
SITE LOCATION MAP
OWC DATE: 12/05/97 iDWC NAME: B3RODSLM
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BAYOU GRANDE POND
NORTH POND
BAYOU GRANDE
/
i
POWERUNE ROAD |
WETLAND 4
GOLF COURSE
POND
WETLAND 3
BEAVER
POND
^-INTERMITTENT CREEK
UNPAVED
ROAD
500
SCALE
500
FEET
SOURCE: U£ 1991/NAWAC ORAWNG NUMBER 5209053
RECORD OF DECISION
SITE 1
NAS PENSACOLA
RGURE 1-2
SITE MAP
DWG DATE: 12/05/97 I DWG NAME: 83ROOSTM
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Final Record of Decision
NAS Pensacola Operable Unit 1
August 19. 1998
surface water runoff from the landfill; it appears that they are fed by groundwater seepage when
the water table is high. A dry stream bed is in the site's northern portion, immediately south and
leading to Bayou Grande Pond. No surface water was observed in this stream bed during the
investigation.
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Final Record of Decision
NAS Pensacola Operable Unit 1
August 19, 1998
2.0 SITE HISTORY AND ENFORCEMENT ACTIVITIES
2.1 General Site History
In December 1989, the base was placed on the United States Environmental Protection Agency's
(USEPA) National Priorities List (NPL). The Federal Facilities Agreement (FFA), signed in
October 1990, outlined the regulatory path to be followed at NAS Pensacola. NAS Pensacola
must complete, not only the regulatory obligations associated with its NPL listing, but it also must
satisfy the ongoing requirements of an environmental permit issued in 1988. A permit is an
authorizing document issued by an approved Florida agency or USEPA to implement the
requirements of an environmental regulation. That permit addresses the treatment, storage, and
disposal of hazardous materials and waste and also the investigation and remediation of any
releases of hazardous waste and/or constituents from solid waste management units (SWMUs) at
NAS Pensacola. The Resource Conservation and Recovery Act (RCRA) governs ongoing use of
hazardous materials and the operating permit rules. RCRA and the Comprehensive Environmental
Response, Compensation, and Liability Act (CERCLA) investigations and actions are coordinated
through the FFA, streamlining the cleanup process.
2.2 Site-Specific History
From the early 1950s until 1976, domestic and industrial wastes from NAS Pensacola and other
outlying Navy facilities were disposed of at Site 1. The following partial list of wastes and
quantities disposed of at the site was taken from the 1983 Naval Energy and Environmental
Support Activity (NEESA) Initial Assessment Study (IAS):
• Ketone-soaked rags
• Polychlorinated biphenyl (PCB)- and transformer oil-soaked rags
• Paint chips
• Paint sludge from water wall paint booth
• Paint sludge
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Final Record of Decision
NAS Pensacola Operable Unit 1
August 19, 1998
• Dry air-filter pads from paint booths
• Compressed air cylinders
• Asbestos from building demolition
• Wood soaked with plating solutions
• Pesticide rinsate
• Garbage
• Wastes from outlying facilities: Corry, Ellison, Saufley, Baron, and Whiting
• Containers of paints, pesticides, oils, strippers, plating chemicals, solvents, thinners, etc.
• Mercury
As shown on Figure 1-2, previous investigation documents and NAS Pensacola Public Works
Center (PWC) drawings indicate that disposal activities moved from one portion of the site to
another when the landfill was active (NEESA, 1983). The southernmost portion of the site, used
during the 1950s, is the landfill's oldest-known section. In the early 1960s, waste disposal was
moved approximately 3,000 feet north, to the site's northernmost portion. Additionally, an area
along the site's northwestern border is reported to have been filled with construction rubble during
the 1950s and 1960s. From the late 1960s until the closure of the landfill, waste was disposed of
in its central portion. During the earlier years of disposal, wastes commonly were burned before
burial; however, this practice ended in the late 1960s due to residents' concern regarding air
pollution in nearby areas. The landfill officially closed on October 1, 1976.
2.3 Chronology of Events and Previous Investigations
The following chronology of events and previous investigations at Site 1 provides a basis for
understanding the history and focus of the remedial investigation/feasibility study (RI/FS).
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Final Record of Decision
NAS Pensacola Operable Unit 1
August 19. 1998
1974 — Discovery of Landfill Leachate Discharge
In 1974, landfill leachate was discharging from an abandoned drainage field into a nearby golf
course pond. The leachate discharge resulted from a plugged drainage outlet, which caused the
water table to rise and leachate to seep from the surface. The leachate discharge was investigated
in 1974 and 1975 by installing and sampling seven galvanized-steel monitoring wells.
Ground water sample analysis detected phenol and several metals (G&M, 1984). This investigation
reportedly concluded that shallow groundwater flowed north toward Bayou Grande and was
contaminated in the upper portion of the Sand-and-Gravel Aquifer near the landfill
(NEESA, 1983).
1983 — Initial Assessment Study
An IAS was performed by NEESA (since renamed) under the Navy Assessment and Control of
Installation Pollutants (NACIP) program. As the first phase of the NACIP program, its purpose
was to identify and assess sites posing a threat to human health or the environment due to
contamination from hazardous materials operations. This study included reviewing facility records
and aerial photographs, interviewing facility personnel, and conducting field surveys. During the
survey, landfill leachate and sediment from site ponds were sampled. Sample analysis detected
cadmium, chromium, mercury, nickel, and lead in sediment, and cadmium and mercury in the
leachate (NEESA, 1983). The survey concluded that Site 1 presented a threat to human health and
the environment; therefore it was recommended for further investigation to include a confirmation
study (verification and characterization studies), Phase D of the NACIP program.
1984 — Verification Study
Part I of the NACIP confirmation study, the verification study, was performed by Geraghty &
Miller, Inc. (G&M) to confirm whether groundwater contaminants were present at sites
recommended for study in the IAS (G&M, 1984). During this study, eight shallow 2-inch
polyvinyl chloride (PVC) monitoring wells were installed and groundwater was sampled for
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Final Record of Decision
NAS Pensacola Operable Unit 1
August 19, 1998
analysis of volatile organic compounds (VOCs), semi volatile organic compounds (SVOCs),
pesticides, PCBs, metals, cyanide, and field parameters. Analytical results indicated that shallow
groundwater beneath the landfill had been affected by past disposal practices. VOCs were detected
in all groundwater samples collected. The highest concentrations of organic compounds, mostly
VOCs, were detected in samples from the central portion of the site. Only trace concentrations
of SVOCs were detected. No PCBs or pesticides were present at concentrations above method
detection limits. All detected metals concentrations were below FDEP 1984 drinking water
standards. Water levels measured in the study indicated shallow groundwater flowing north,
northwest, and northeast toward surface water bodies, where it discharges to the bayou, site
ponds, and tidal inlets.
1986 — Characterization Study
Part n of the NACIP confirmation study, the characterization study, was performed by G&M to
determine the nature and extent of contamination at verification study sites requiring additional
investigation (G&M, 1986). During this investigation, five additional shallow monitoring wells
(GM-38 through GM^*2) and three deep wells (GM-43 through GM-45) were installed.
Groundwater samples were collected from all new wells and the eight verification study wells.
Groundwater samples from the new wells were analyzed for the USEPA's list of organic priority
pollutants, including VOCs, SVOCs, pesticides, and PCBs. Samples collected from the previously
installed wells were analyzed for VOCs only. No metals analysis was performed for either well
group. Samples collected from 12 of the 16 wells contained one or more VOCs. Additionally,
two samples collected from deep wells were contaminated with VOCs. However, the presence
of certain VOCs during the characterization study was not consistent with the verification study
results (e.g., vinyl chloride only detected during characterization, methylene chloride detected
only during verification). SVOCs, pesticides, or PCBs were not detected during the
characterization study. Water level elevation data again confirmed the generally northward flow
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Final Record of Decision
NAS Pensacola Operable Unit 1
August 19. 1998
of shallow groundwater toward site surface water bodies. However, deep well water levels
indicated a slight gradient to the south (G&M, 1986).
1991 — Contamination Assessment/Remedial Activities Investigation
Phase I of a Contamination Assessment/Remedial Activities Investigation was performed by
Ecology and Environment, Inc. (E&E, 1991a), to identify principal areas and primary
contaminants of concern at Site 1 and to provide recommendations for subsequent phases of
investigation. The following preliminary surveys were performed: site reconnaissance survey,
aerial photography analysis, radiation survey, surface emissions survey, and a geophysical survey.
Additionally, site surface water, sediment, surface soil, and groundwater were sampled for
laboratory analysis. Groundwater samples were collected from 15 G&M monitoring wells, along
with 28 temporary shallow monitoring wells. Sediment, surface water, and surface soil samples
were analyzed for a suite of screening parameters, including VOCs, polynuclear aromatic
hydrocarbons (PAHs), phenols, pesticides, total PCBs, total recoverable petroleum hydrocarbons,
and metals (water samples analyzed unfiltered). Samples collected from existing G&M wells were
analyzed according to USEPA Contract Laboratory Program protocol for the full Target Analyte
List/Target Compound List, plus gross alpha radioactivity. Samples from temporary wells were
analyzed for the screening parameters suite. The investigations are detailed in the corresponding
1991 Interim Data Report (E&E, 1991b). The following passage summarizes E&E's investigation
result conclusions.
Site Reconnaissance Survey — Numerous disturbed areas indicating fill activities or leachate
migration were identified across the site. A collapsed/depression feature with remains of metal
containers, an oozing tar-like substance, and elevated organic vapor concentrations was identified
in the northwest corner of the 1950s fill area. Exposed medical and industrial waste was identified
in the southwestern corner of the 1970s fill area. A linear pit containing a black, tar-like material
was also identified in the northwestern corner of the 1970s fill area. This pit measured
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Final Record of Decision
NAS Pensacola Operable Unit 1
August 19. 1998
approximately 40 feet by 15 feet and contained approximately 1.5 feet of material. A construction
rubble field south of North Pond extended south across Powerline Road near well GM-33.
Various discolored water/leachate seeps and areas of soil and/or vegetation staining were identified
in site wetland areas (intermittent streams, ponds, and tidal inlets).
Aerial Photography Analysis — A review of historical aerial photographs generally confirmed
the progression of landfill activities, which began in the site's southern portion during the 1950s,
moved to the northern portion in the early 1960s, and ended in the central portion from the late
1960s through 1976. Additionally, numerous areas of disturbance associated with landfill
activities were noted from these photographs. Specifically, three dark areas, one corresponding
to the tar pit location, were identified on a 1970s photograph along the western extent of the
1970s fill area. An apparently low, linear marshy area also identified on a 1970s photograph
corresponds to the construction rubble field. Also, a sizeable dark irregular feature measuring
approximately 200 feet by 75 feet was observed in the center of the 1970s fill area on a
1973 photograph (E&E, 1991b).
Surface Emissions and Radiation Surreys — Elevated organic vapor concentrations ranging from
1.0 to 20.0 parts per million above background were detected at five locations. The highest
concentration was at the collapse/depression feature in the 1950s fill area. Surface radiation
concentrations above reference concentrations were not detected (E&E, 1991b).
Geophysical Survey — An electron magnetometer (EM-31) and metal detector (EM-34) were used
to perform the survey. Overall, the results indicated the presence of ferrometalic materials at
relatively shallow depths (20 feet below land surface [bis] or less) across most of the landfill,
primarily within the landfill boundary as determined by aerial photographs and site
reconnaissance. Deeper anomalous EM-34 readings collected north, west, and east of the landfill
may be attributable to landfill leachate migration toward the bayou in a lower portion of the
10
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Final Record of Decision
NAS Pensacola Operable Unit 1
August 19. 1998
surficial zone of the Sand-and-Gravel Aquifer. However, these deeper anomalies may also reflect
saline water intrusion and/or more conductive lithologies present below the surficial zone base
(E&E, 1991b).
2.4 Removal Action
The remedial investigation (RI) completed at Site 1 identified a tar pit which posed a physical
hazard to site trespassers. There is no PRG established for the material. TCLP samples collected
of the tar in 1993 indicated that it was not hazardous waste. A total of 73 tons of this material was
excavated in January 1998 and disposed of at a Subtitle D landfill to remove the physical hazard.
11
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Final Record of Decision
NAS Pensacola Operable Unit 1
August 19, 1998
3.0 HIGHLIGHTS OF COMMUNITY PARTICIPATION
Throughout the site's history, the community has been kept abreast of activities in accordance with
CERCLA Sections 113(k)(2)(B)(i-v) and 117. In January 1989, a Technical Review Committee
(TRC) was formed to review recommendations for investigation and remediation efforts at
NAS Pensacola and monitor its progress. The TRC was made up of representatives of the Navy,
USEPA, FDER (now FDEP), and the local community. In addition, a mailing list of interested
community members and organizations was established and maintained by the NAS Pensacola
Public Affairs Office. In July 1995, a Restoration Advisory Board (RAB) was established as a
forum for communication between the community and decision-makers. The RAB absorbed the
existing TRC and added more members from the community and local organizations. The
RAB members work together to monitor progress of the investigation and to review remediation
activities and recommendations at NAS Pensacola. RAB meetings are held regularly, advertised,
and are open to the public.
Site-related documents were made available to the public in the administrative record at
information repositories maintained at the NAS Pensacola Library and the John C. Pace Library
of the University of West Florida.
Before the removal action occurred at Site 1, a public notice was placed in the Pensacola News
Journal on January 8, 1998. After finalizing the RI, Focused Feasibility Study (FFS), and
FFS addendum reports, the preferred alternative for Site 1 was presented in the Proposed
Remedial Action Plan, also called the Proposed Plan. Everyone on the NAS Pensacola mailing
list was sent a copy of the Proposed Plan. The notice of availability of the Proposed Plan, RI, and
FFS documents was published in the Pensacola News Journal on December 4, 1997. A public
comment period was held from December 8, 1997, to January 22, 1997, to encourage public
participation in the remedy-selection process. In addition, the opportunity for a public meeting
was provided. Responses to comments received during the comment period are in Appendix B.
12
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Final Record of Decision
NAS Pensacola Operable Unit 1
.. August 19, 1998
4.0 SCOPE AND ROLE OF THE OPERABLE UNIT
This selected remedy is the first and final remedial action for the site. The function of this remedy
is to reduce the risks to human health and environment associated with exposure to contaminated
groundwater and soil.
The selected remedial alternative will address conditions which pose a threat to human health and
the environment including:
• Contaminated groundwater may potentially impact drinking water supplies or nearby
ecological receptors
Pathways of exposure include:
• ingestion and inhalation of contaminated groundwater and
• aquatic exposure to groundwater migrating to surface waters.
The major components of the remedy are:
• Institutional controls imposed in accordance with the LURA to restrict groundwater use
of the surficial zone of the Sand-and-Gravel Aquifer within 300 feet of the site.
• Institutional controls imposed in accordance with the LURA to limit intrusive activities
within the landfill boundary without prior approval from the NAS Pensacola
Environmental Office.
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NAS Pensacola Operable Unit 1
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• Annual review of the institutional controls and certification that the controls should remain
in place or be modified to reflect changing site conditions.
• Groundwater monitoring to ensure that natural attenuation processes are effective.
• A review during which the Navy would determine whether groundwater performance
standards continue to be appropriate and if natural attenuation processes are effective.
• Continued groundwater monitoring at regular sampling intervals after performance
standards are attained. The groundwater monitoring program would continue until a five-
year review concludes that the alternative has achieved continued attainment of the
performance standards and remains protective of human health and the environment.
• A groundwater interception system to capture the contaminated groundwater upgradient
of Wetland 3. The intercepted groundwater will be treated to reduce iron levels before
being reintroduced into Wetland 3.
• Concentrations of the organic compounds present in the groundwater and surface water
will be reduced through natural attenuation resulting from naturally occurring biotic and
abiotic processes which take place in the groundwater and surface water systems.
This remedy addresses the first and final cleanup action planned for Operable Unit (OU) 1. The
groundwater beneath OU 1 contains concentrations of contaminants similar to those present in
OU 1 subsurface soil. Although the water-bearing zone is affected, contamination is not affecting
the public drinking water supply. This proposed action is to prevent current or future
unacceptable exposure to contaminated soil and groundwater, and to reduce the migration of
contaminants to surface water.
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Final Record of Decision
NAS Pensacola Operable Unit I
August 19, 1998
This is the only Record of Decision (ROD) contemplated for Site 1. Operable Unit 1, which
consists of Site 1, is one of 13 OUs within NAS Pensacola. The purpose of each OU is defined
in the FY1997 Site Management Plan (SOUTHNAVFACENGCOM, 1996) for NAS Pensacola,
which is in the Administrative Record.
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NAS Pensacola Operable Unit 1
August 19, 1998
5.0 SITE CHARACTERISTICS
This section of the ROD presents an overview of the nature and extent of contamination at OU 1
with respect to known or suspected sources of contamination, types of contamination, and affected
media. Known or potential routes of contaminant migration are also discussed.
5.1 Nature and Extent of Soil Contamination
Based on the Site 1 RI (January 1996), soil inside the landfill boundary has been impacted by past
activities there. Buried waste in the landfill has been characterized in the RI as containing
detectable concentrations of all analyzed parameter groups (inorganics, volatiles, semivolatiles,
pesticides and PCBs). Because the landfill is approximately 20 to 40 years old, minimal
concentrations of waste constituents are expected to be leaching to underlying groundwater. Soil
quality outside the landfill boundary appears to generally compare to reference soil conditions.
However, soil within the boundary appears to have been impacted by landfill activities, resulting
in elevated concentrations of inorganic and organic constituents. However, none of the surface
soil samples contained any compounds at concentrations above their respective PRG.
5.2 Nature and Extent of Groundwater Contamination
Shallow and Intermediate Groundwater
The affected groundwater in the aquifer beneath OU 1 has been classified by USEPA and FDEP
as Class IIA and G-2, a potential source of drinking water. The nature and extent of landfill-
impacted groundwater have been evaluated onsite. Inorganic and organic constituents are present
in the surficial zone (shallow and intermediate well'depths) beneath the site. Groundwater
analytical results from 1993 and 1994 indicate that 1993 analytical results were affected (biased)
due to sample turbidity. The 1993 samples were collected with Teflon bailers, while 1994 samples
were collected with quiescent sampling techniques. Based on 1994 analytical results, the greatest
impact from inorganics to shallow and intermediate groundwater quality appears to be limited to
the site's center, along the landfill's eastern, western, and northwestern boundaries. Except for
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NAS Pensacola Operable Unit 1
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aluminum, iron, and manganese (indicated by reference data to naturally occur at elevated
concentrations), inorganic concentrations exceeding applicable or relevant and appropriate
requirements (ARARs) are generally limited to areas within and around the landfill perimeter.
Organic constituents have consistently been detected near Maximum Contaminant Levels/Florida
Groundwater Guidance Concentrations [MCL/FGGC] in Site 1 surficial groundwater. Consistent
with the distribution of elevated inorganics, the highest organic concentrations were detected in
the site's center and along the eastern and western boundaries. Organic concentrations extend
downgradient from the landfill to areas along Bayou Grande's coastline, adjacent wetlands, and
east-northeast beneath the golf course. However, no elevated inorganic or organic concentrations
(except for a single pesticide concentration) were detected in samples collected from the most
downgradient monitoring well across the golf course opposite the landfill. This indicates that the
extent of organic contaminant-impacted groundwater migrating east-northeast from the landfill is
limited to the area beneath the adjacent golf course. As with inorganics, organic concentrations
exceeding ARARs are generally limited to areas within and around the landfill's perimeter. The
groundwater area of concern is shown on Figure 5-1.
Deep Groundwater
Based on deep well sample results, groundwater quality within the main producing zone beneath
the site does not appear to have been affected by site activities.
5.3 Nature and Extent of Sediment and Surface Water Contamination
Wetland 3 is bordered by Site 1 to the north, south, and west, and by John Tower Road and the
golf course to the east. A narrow surface water channel in this wetland is approximately 4 inches
deep and 1 to 2 feet wide. The wetland's remaining portion is from 3 to 500 feet wide and is
saturated sediment overlain by a thin layer of surface water. Sediment in most of the wetland is
17
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01GI46
e
01GGM43\
RECORD OF DECISION
SITE 1
NAS PENSACOLA
- AREA OF GROUNDWATER
CONTAMINATION
ft - SHALLOW MONITORING WELL
- D£EB MONITORING WELL
•&• - INTERMEDIATE; MONITORING WELL
FIGURE 5-1
GROUNDWATER AREA OF CONCERN
OWC D*Tt:12/OV97
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Final Record of Decision
NAS Pensacola Operable Unit 1
August 19, 1998
highly organic, with total organic carbon (TOC) detected at up to 24%. The shallow, open water
portion contains several freshwater vegetative species such as lizard tail and cattails. The area
surrounding the wetland consists of pine trees, with some oaks and other species. These areas
could provide habitat and cover for many different species. The lower section of this wetland
recently was excavated to clear the drainage culvert that discharges into Wetland 4D. This culvert
runs east under John Tower Road and a golf course fairway before discharging into Wetland 4D.
Estuarine Wetland 4D is a pond fed by Wetland 3 from the west, Wetland 4C from the south, and
Bayou Grande from the north. Wetland 4D, which flows north into Bayou Grande through a
culvert beneath an unnamed dirt road, is surrounded by the golf course. The open water portion
of the wetland ranges from 1 foot to approximately 8 feet deep and has a maximum width of
approximately 700 feet. Sediment in the wetland is sandy, with TOC detected up to 7%. The
steep gradient surrounding the wetland makes the transition from upland to open water obvious.
The area surrounding Wetland 4D is mowed grass, with a small stand of pine trees and a small
area of spartina at its northwestern corner. The presence of mowed grass around this wetland
limits its potential to provide habitat for most species. However, great blue herons have been
observed feeding in this wetland.
Wetland 4D discharges into Bayou Grande, which has been classified by the Florida Department
of Environmental Protection (FDEP) as a Class in water body, indicating its use for recreation
and maintaining a well-balanced fish and wildlife population.
During the Site 41 RI, surface water samples were collected from Wetland 3 and Wetland 4D.
The only exceedances were for iron in Wetland 3 surface water and at the outfall of Wetland 3 into
Wetland 4D. Figure 5-2 shows where these exceedances occurred.
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WETLAND 3 AND WETLAND 4D SURFACE WATS*
IRON CONCENTRATIONS
041W0401
(1.580 ppb)
041W0301-
(17.900 ppb)'
041W0302
(59.600 ppb)
041W0404
(695 ppb)
J41W0303
176.000 ppb)
FE STANDARD
FLORIDA SALTWATER STANDARD 300 ppb
FLORIDA FRESHWATER STANDARD 1000 ppb
WETLAND 4O
041W0304
(21.500 ppb)
WETLANDS
RECORD OF DECISION
SITE 1
MAS PENSACOLA
FIGURE 5-2
SURFACE WATER
AREA OF CONCERN
3WG DATE: 12/11/97 |DWG NAME: 63RODAOC
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NAS Pensacola Operable Unit J
August 19. 1998
5.4 Fate and Transport
5.4.1 Sources of Contamination
During the RI, contamination was identified within the former landfill boundaries. A limited
amount of soil contamination was detected in the 0- to 1-foot surface soil depth interval inside the
landfill boundary. Higher concentrations of detected parameters were present within the
subsurface landfill waste interval (occurring at depths varying from 2 to 18 feet bis). Surface soil
inside the landfill boundary consists of highly permeable silty sand with varying amounts of
decaying organic cover (leaves and straw). Landfill wastes include heterogeneous deposits of
construction rubble; burned and unburned domestic refuse; industrial refuse including plastic,
glass, metal, and crushed drums; clayey-silty sludge; and tar/sludge. Native soil (fine- to medium-
grain quartz sand) immediately beneath the waste intervals appears to be only slightly impacted
compared to the overlying fill at most sampling locations; however, at one location (trench 6) soil
was contaminated down to the water table; at another location (trench 9) landfill waste extended
below the shallow water table in this area.
Surface soil samples collected from test trenches in the landfill boundary generally had detections
of all analytical parameter groups (inorganics, VOCs, semivolatiles, pesticides, and PCBs)
compared to surface soil outside the landfill and background soil samples. These samples should
be considered representative of surface conditions across the landfill interior because the surface
soil interval sampled at each trench location consisted of the overburden/cover material that was
reworked and graded into place during landfill activities. Surface samples from locations 01S8001
and 01S8201 represent discrete sources of surface soil contamination associated with surface
features — the mounds of soil and the collapse feature at each locality — in these respective areas.
Concentrations of all analytical parameter groups were identified in landfill waste samples
collected during test trenching. Highest concentrations from the trenching samples were detected
in waste samples from trench 3, inorganics, VOCs, semivolatiles, pesticides, and PCBs; trench 4,
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semivolatiles; trench 6, VOCs and semivolatiles; trench 7, VOCs, semivolatiles, and PCBs;
trench 8, PCBs; trench 11, PCBs; and trench 12, inorganics, VOCs, and semivolatiles. These
areas would appear to represent the greatest potential threat to groundwater. Notably, efforts were
made to sample landfill areas posing the greatest environmental risks based on contaminant source
survey findings. However, because of the landfill's size and the sampling location's distribution,
these areas are not considered isolated, but may represent parameter concentrations potentially
present throughout the heterogeneous waste interval. Therefore, no particular test trench should
be considered an isolated, separable source; moreover, broader source areas should be considered
when addressing contaminant migration (e.g., the landfill's central portion versus the northern or
southern portions).
5.4.2 Contaminant Migration
Leaching from Soil to Groundwater
Parameters detected in Site 1 soil and/or waste samples (solid media) may enter groundwater by
two mechanisms. They may leach by downward percolation of precipitation through the solid
media toward the water table or from continual groundwater contact with solid media at or near
a fluctuating water table. In general, native soil at Site 1 is very permeable, with rapid infiltration
and minimal contact time between percolating water and soil above the water table. However,
some trench wastes are fine-grained material (sludges, clayey-ash residue, or silty-clayey sand),
that have lower permeabilities, resulting in longer contact with percolating water. Most native soil
samples from immediately beneath the waste interval yielded very low to nondetect parameter
concentrations. This suggests either: (1) the waste material is retaining parameter constituents
where present, and minimal leaching is occurring, (2) downward migrating contaminants are not
retained by the native soil, but pass directly to groundwater, or (3) leachable fractions have
already been flushed to groundwater and current groundwater quality represents reasonable worst-
case conditions.
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Impacted soil and/or landfill waste material extended into the water table in trenches 6 and 9. At
trench 6, petroleum-hydrocarbon stained soil was encountered above and in direct contact with the
shallow water table (6 to 8 feet bis). This soil contained concentrations of aromatic and aliphatic
volatiles, chlorinated aromatic semivolatiles, and PAHs. At trench 9, waste material extended into
the water table. Solid media in these trenches continuously contact shallow groundwater, allowing
for maximum contact time for phase partitioning to the aqueous medium. An unfiltered shallow
groundwater grab sample collected from trench 9 contained several heavy metals (antimony,
cadmium, chromium, lead, mercury, and nickel) and benzene at concentrations exceeding MCLs.
However, the high turbidity of the sample likely contributed to the detected concentrations.
The potential for contaminant migration through soil depends on the chemical characteristics of
the contaminants and several physical and chemical parameters of the soil, including TOC, cation
exchange capacity (CEC), pH, and redox potential. Most semivolatiles, pesticides, and PCBs are
considered to have limited potential for migration due to their low solubility and high affinity for
soil particles and organic carbon. VOCs are considered more mobile, but also have a moderate
affinity for organic carbon. Physical analyses of waste interval material and underlying native soil
sampled generally indicate higher TOC content (up to 3,000 mg/kg) in the waste than in the native
soil (50 mg/kg to 250 mg/kg). Analyses of most trench waste/native soil pairs show correlations
between higher TOC values and high organic concentrations in the waste, and lower TOC values
and low to nondetect organic concentrations in the underlying native soil. The mobility and
potential for metals migration depends on pH, redox potential, TOC, and CEC of the soil. CEC
analyses consistently indicate higher values for the waste interval (up to 14.0 meq/lOOg) than the
underlying native soil (0.2 meq/lOOg to 5.2 meq/lOOg). Correspondingly, inorganic analytical
results show a higher metals concentration in the waste, and a low to nondetect metals
concentration in the underlying native soil. While the waste interval has been determined to be
contamination source, its elevated TOC and CEC values may also allow it to retain or bind an
appreciable amount of contaminants contained in it. The low to nondetect concentrations in the
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NAS Pensacola Operable Unit 1
August 19. 1998
underlying native soil may result from minimal downward contaminant migration due to the
retention properties of the waste interval, and/or a lower retention capability of the underlying
native soil as contaminants pass through it with minimal partitioning to the soil.
Based on the distribution of detected parameters in ground water, the landfill's most recently filled
central portion (early to mid-1970s) appears to be the primary source for organics (VOCs,
semivolatiles, and minor amounts of pesticides) currently detected in shallow and intermediate
samples. However, the southwestern portion (1950s) also appears to be a source of organics
(VOCs and semivolatiles) in both shallow and intermediate samples from the southwestern landfill
boundary. The relatively lower concentrations in the landfill's northern portion (1960s) are either
associated with relatively lower concentration sources in this area, or are the result of
downgradient advective contaminant migration from the site's central portion. This distribution
could be due to a higher overall volume of wastes within the central portion, the relative age of
that portion compared to the older and perhaps more leached sections, or the monitoring well array
spatial positioning.
The actual teachability of waste interval material was evaluated through TCLP analyses of test
trench samples. These waste samples consisted of the following materials: sandy soil with
domestic and burned waste from trench 2; sandy soil with clayey-ash from trench 3; tar waste and
stained sandy soil from trench 4; heavily fuel-stained sandy soil from trenches 6A, 6B, and 6C;
sandy soil with industrial and domestic waste from trenches 7, 8, and 9; sandy soil with industrial
and burned waste from trench 11; and sandy soil with tar-like sludge material from trench 12. No
samples, except those from trench 12 yielded leachable target constituents above TCLP reporting
limits. The sample from trench 12 yielded 376 ng/L tetrachloroethane. Based on the TCLP
results, it can be inferred that landfill wastes are presently not leaching gross concentrations of
contamination above TCLP reporting limits to site groundwater at 10 of the 11 tested locations.
However, TCLP reporting limits (parts per million [ppm]) are higher than CLP limits (parts per
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NAS Pensacola Operable Unit 1
August 19, 1998
billion [ppb]) and the reported list of TCLP analytical parameters is not as comprehensive as the
TAL/TCL list. Therefore, lower concentrations of target contaminants or non-TCLP parameters
may be leaching from the wastes to site ground water. Furthermore, landfill portions not
investigated by invasive methods may contain more teachable wastes than those encountered
during this investigation. However, groundwater quality data do not indicate that the last two
items are occurring to any appreciable degree.
Surface Water Transport
The generally high soil permeabilities around Site 1 limit substantial contamination transfer via
surface water flow. During the RI, overland flow was not observed within the landfill boundary.
Two intermittent creeks lie within wetlands outside the landfill, as shown previously on
Figure 1-2. One creek approximately 50 to 100 feet east of the landfill's central portion flows
intermittently to the northeast toward Beaver Pond (Wetland 3). The other creek originates
approximately 500 feet west of the landfill's central portion and channels flow northwestward to
Bayou Grande. Neither creek has been observed to receive direct surface water runoff from the
landfill. They appear to be fed by groundwater seepage during periods of high water table. A
third dry stream bed in the southern tip of the site's northern portion leads to Bayou Grande Pond.
No surface water was observed in this stream bed during the investigation.
Contaminants may be transferred from soil to intermittent stream waters via surface drainage or
by the same soil leaching processes discussed above. That is, contaminants would leach from soil
to groundwater, then via groundwater to surface water pathways, mediated by groundwater quality
characteristics. Because surface waters are fed primarily by groundwater, creek surface water
quality may be expected to approximate local shallow groundwater conditions. However, surface
water samples collected from site wetlands during 1994 sampling activities indicate that wetland
surface water has not been greatly impacted by site groundwater. Additionally, native
soil (sample 01S5602) from the dry stream bed south of Bayou Grande Pond yielded no
leachable target constituents above TCLP reporting limits. Based on these results, contaminant
concentrations are not currently being transported via the surface water pathway.
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NAS Pensacola Operable Unit 1
August 19, 1998
Groundwater Transport
Groundwater analytical results indicate that organic compounds are leaching or have leached
from the landfill and are migrating via the groundwater pathway. Additionally, inorganic
concentrations exceeding ARARs were detected in 1994 samples from the site's center, along the
landfill's eastern and western boundaries. The highest organic compound concentrations were
identified in both shallow and intermediate groundwater samples from the perimeter of the central,
1970s portion of the landfill. Based on piezometric measurements, groundwater contaminants
appear to migrate radially north, east, and west from the landfill's central portion toward
Bayou Grande. Downward vertical hydraulic gradients between shallow and intermediate
groundwater depths, generally equivalent in magnitude to lateral gradients, indicate a strong
tendency for downward contaminant migration with lateral movement. Parameter concentrations
detected at intermediate depth likely result from this downward flow component. The presence
of an 8- to 20-plus-foot thick, low-permeability clay layer between intermediate and deep
monitored zones likely inhibits downward contaminant migration into deep groundwater. This
likelihood is supported by the absence of organic compounds or elevated inorganics in deep
groundwater samples.
The groundwater contaminant migration rate may be conservatively estimated to equal
groundwater velocity disregarding retardation effects. Based on groundwater velocities calculated
and presented in the RI, the rate of contaminant movement from the landfill's central portion
toward the east, north, and west is expected to be approximately 0.17 to 5.01 ft/day in shallow
groundwater and approximately 0.08 to 3.38 ft/day in intermediate groundwater. Based on this
information, contaminants leaching to shallow groundwater from the landfill's central portion may
have migrated across the site's full northwestern, northern, and northeastern extents to
Bayou Grande during the approximately 20 years since the landfill was closed.
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NAS Pensacola Operable Unit 1
August 19, 1998
The high suspended solid and organic content in natural pore water beneath Site 1 may affect
contaminant transport due to possible partitioning of organic contaminants onto carbonaceous
material and metals onto organic material or clay. The variable pH of site ground water, ranging
from slightly acidic (as low as 4.15) to neutral (as high as 7.25) may also affect the partitioning
of organic and metal contaminants. Therefore, contaminant movement may, in part, be retarded
by the inability of paniculate matter to move with ground water, resulting in lower migration rates.
Potential Receptors and Impacted Media
The primary medium impacted by site activity has been the surficial zone of the Sand-and-Gravel
Aquifer. Samples from this zone's shallow and intermediate monitoring wells have consistently
indicated impacted groundwater. Concentrations of several organic compounds in RI samples
exceeded drinking water standards and generally compare to those reported in previous studies.
Limited elevated inorganic concentrations were also detected in 1994 samples. Impact on
groundwater emanating from the landfill's central 1970s portion appears to be the most significant.
Both impacted and unimpacted groundwater in the surficial zone is highly turbid (as noted during
1993 sampling) and contains natural iron, manganese, and sodium concentrations exceeding
FSDWS. A large portion of this zone yields dark brown, highly organic pore water with an acrid
odor. Moreover, background/reference concentrations of regulated metals also exceed drinking
water standards. Based on natural groundwater characteristics, the surficial zone does not appear
suitable as a drinking water supply either in impacted or unimpacted areas. Groundwater from
the surficial zone is not presently used or anticipated to be used for that purpose.
Bayou Grande receives discharge from groundwater flowing west, north, and northeast from the
site; therefore, the sediment and surface water are potentially impacted media of Site 1. This
bayou has been classified by the FDEP as a Class ID water body, indicating its use for maintaining
a well-balanced fish and wildlife population. Potential impacts of past landfill activities on
Bayou Grande will be addressed in an upcoming RI/FS (Site 40).
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Other potentially impacted media include the surface waters and wetlands associated with Beaver
Pond (Wetland 3) and Golf Course Pond and the intermittent creek east of the landfill, the
intermittent creek west of the landfill, and Bayou Grande Pond and North Pond to the north.
These water bodies are potentially threatened by impacted groundwater discharges via direct
seepage or intermittent creek flow during wet seasons. However, overland runoff from the landfill
into these bodies is unlikely due to the high surface soil permeability. Except for Wetland 3, this
investigation's results indicate that current impact to these areas is relatively low with regard to
sediment and surface water quality criteria. Surface water samples collected at Wetlands 16 and
18 during the Site 1 investigation had no exceedances of the Florida surface water quality
standards for fresh water. In Wetland 1, copper (7.5 ppb), iron (3,540 ppb), and lead (6 ppb)
exceeded the surface water quality standards for fresh water which are 6.54 ppb, 1,000 ppb, and
1.32 ppb respectively. Surface water samples collected from Wetland 3 had exceedances of the
iron surface water quality standard as shown on Figure 5-2. Potential impacts of past landfill
activities on these water bodies will be further addressed in an upcoming RI/FS for the
NAS Pensacola wetlands (Site 41).
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NAS Pensacola Operable Unit 1
August 19, 1998
6.0 SUMMARY OF SITE RISKS
A baseline risk assessment (BRA) has been conducted for OU 1, and the results are presented in
Section 10 of the RI report. The BRA, which was based on contaminated environmental site
media as identified in the RI, was conducted to assess the resulting impact to human health and
environment. Actual or threatened releases of hazardous substances from this site, if not
addressed by implementing the response action selected in this ROD, may present an imminent
and substantial endangerment to public health or environment.
6.1 Chemicals of Potential Concern
Contaminants detected at OU 1 were screened against available federal and State of Florida
cleanup criteria, soil and groundwater standards, and reference concentrations to develop a list or
group of chemicals referred to as chemicals of potential concern (COPCs). COPCs are selected
after comparison to screening concentrations (risk-based, teachability-based, and reference),
intrinsic toxicological properties, persistence, fate and transport characteristics, and cross-media
transfer potential. Any COPC is considered a chemical of concern (COC) if it is carried through
the risk assessment process and found to contribute to a pathway that exceeds a 106 risk or hazard
index (HI) greater than 1 for any of the exposure scenarios evaluated in this risk assessment and
has an incremental lifetime cancer risk (ILCR) greater than 10* or hazard quotient (HQ) greater
than 0.1. Table 6-1 summarizes COPCs for these pathways. Surface soil did not produce any risk
levels above 10"6 or 1. Bayou Grande and NAS Pensacola wetlands surface water and sediment
will be further evaluated during the Sites 40 and 41 RIs.
Essential elements may be screened out of a risk assessment if it is shown that concentrations
detected are not associated with adverse health effects. Therefore, the following nutrients were
eliminated: calcium, iron, magnesium, potassium, and sodium.
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Chemicals
1 , 1 ,2.2-Tetrachloroethane
1 . 1 .2-Trichlorocthane
1.2-Dichloroethene (toul)
1 ,4-Dichlorobenzene
4-Chloro-3-methylphenol
Aluminum
Aroclor-1248
Aroclor-1254
Aroclor-1260
Arsenic
Barium
Benzene
Beryllium
bis(2-Ethylhexyl)phthalate
Bromoform
Cadmium
Chlorobenzene
Chloroform
Chromium
Copper
Dieldrin
Lead
Manganese
2-Methylnaphthalene
Naphthalene
Nickel
Tetrachloroethene
Toluene
Trichloroethene
Vinyl chloride
Xylene
Zinc
Table 6-1
Chemicals of Potential Concern
Shallow and
Surface Soil Ail Depth Soil Intermediate Deep
(rag/kg) (mg/kg) (mg/L) (mg/L)
0.002-0.006
0.001-0.002
0.001-0.065
0.003-0.017
0.42-4.3 GWP
483-13600 141-13600 GWP 0.134-4.78
0.19
0.31
0.0047-0.13
0.0059-0.0426
0.69-1050 GWP 0.0024-0.335
0.001-0.08
0.61
0.011
0.002-0.004
5.2-99 1.5-214 GWP 0.0305
0.001-0.12
0.004-0.005
0.616
3.1-212 GWP 0.147
0.00019-0.072 GWP 0.0000076
0.9-441
2.3-191 1.9-191 GWP 0.0077-0.6 0.0241-
0.0901
0.22-6.8 GWP 0.003-0.011
0.32-16 GWP 0.00 i -0.038
11.1-55.7 GWP 0.253
0.006-26 Air
0.001-2300 Air
0.001-0.002
0.002-0.012
0.22-49 GWP 0.003-0.11
0.0027-3.02
Notes:
GWP — The chemical was retained as a COPC based on groundwater protection
AIR — The chemical was retained as a COPC based on potential volatilization and inhalation exposure.
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NAS Pensacola Operable Unit 1
August 19. 1998
6.2 Exposure Assessment
Whether a chemical is actually a concern to human health depends upon the likelihood of
exposure, i.e., whether the exposure pathway is currently complete or could be in the future. A
complete exposure pathway (a sequence of events leading to contact with a chemical) is defined
by four elements. If all four elements are present, the pathway is considered complete:
• Source and mechanism of release
• Transport medium (e.g., surface water, air) and migration mechanisms through the
medium
• Presence or potential presence of a receptor at the exposure point
• Exposure route (ingestion, inhalation, dermal absorption).
All potential exposure pathways that could connect chemical sources at OU 1 with potential
receptors were evaluated. All possible pathways were first hypothesized and evaluated for
completeness using the above criteria. Current pathways represent exposure pathways that could
exist under current conditions, while future pathways represent exposure pathways that could exist
in the future, if current exposure conditions change.
6.2.1 Current Exposure
Under current land use conditions at OU 1, access to areas of concern is restricted to authorized
personnel only, but the area is not fenced. Potential exposures under present land use are
summarized below:
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NAS Pensacola Operable Unit 1
August 19, 1998
Potential Exposure Scenarios — Current Conditions
Media Exposure Pathway Receptor
Soil Incidential Inhalation Onsite Worker
Dermal Contact Child Trespasser
Surface Water Incidential Ingestion Child Trespasser
Sediment Incidential Ingestion Child Trespasser
Dermal Contact Child Trespasser
6.2.2 Future Exposure
Complete exposure pathways could exist based on an estimate of the reasonable maximum
exposure (RME) expected under future conditions. Although unlikely, it is assumed that OU 1
may be developed as residential areas, which could also provide reasonable opportunities for
recreational activities. If so, future residents could be exposed to soil via incidental ingestion and
dermal contact routes of exposure associated with living in the area. Potential exposures for future
land use are summarized below:
Potential Exposure Scenarios — Future Conditions
Media Pathway Receptors
Soil Incidential Ingestion Site Resident
Dermal Contact Site Worker
Groundwater Ingestion Site Resident
Inhalation Site Worker
Exposure Point Concentration
Exposure point concentrations for each chemical of concern and exposure assumptions for each
pathway were used to estimate chronic daily intakes (GDIs) for potentially complete pathways.
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GDIs were then used with cancer potency factors and noncarcinogenic reference doses to evaluate
risk.
The 95th percentile for reported concentrations of chemicals of concern in each media evaluated
were calculated as exposure point concentrations for the RME in each exposure scenario.
Exposure point concentrations are summarized in Table 6-2.
Potential future exposure scenarios included all exposures examined under current conditions. The
same exposure assumptions used to evaluate future conditions were used for current conditions.
Assumptions are listed in Tables 6-3 and 6-4 for current and future land use.
6.3 Toxicity Assessment
A cancer slope factor (CSF) and a reference dose (RfD) are applied to estimate risk of cancer from
an exposure and the potential for noncarcinogenic effects from exposure.
CSFs have been developed by USEPA's Carcinogenic Assessment Group to estimate excess
lifetime cancer risks associated with exposure to potentially carcinogenic contaminants of concern.
CSFs, which are expressed in units of (mg/kg/day)"', are multiplied by a potential carcinogen's
estimated intake in mg/kg/day, 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 risks calculated from the CSF. Use of this approach makes
underestimation of actual cancer risk highly unlikely. CSFs are derived from the results of human
epidemiological studies or chronic animal bioassays to which animal-to-human extrapolation and
uncertainty factors have been applied.
This increased cancer risk is expressed by terms such as 1E-6. To state that a chemical exposure
causes a 1E-6 added upper limit risk of cancer means that if 1,000,000 people are exposed, one
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additional incident of cancer is expected to occur. The calculations and assumptions yield an
upper limit estimate, which assures that no more than one case is expected and, in fact, there may
be no additional cases of cancer. USEPA policy has established that an upper limit cancer risk
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Media and Chemical
Exposure
Table 6-2
Point Concentrations
Exposure Point Concentrations
Frequency of Detection RME
Background
Soil (mg/kg)
Aluminum
Beryllium
Cadmium
Lead
Manganese
Aroclor 1248
Aroclor 1254
Aroclor 1260
26/27
1/27
3/27
23/27
19/27
1/27
1/27
3/27
4006
0.239
2.738
102.222
40.5678
0.024
0.0269
0.00584
3833.8
0.41
1
7.32
21.36
NA
NA
NA
Shallow/Intermediate Groundwater (mg/L)
Vinyl chloride
1 , 1 ,2,2-Tetrachloroethane
1 ,2-Dichloroethene
Benzene
Toluene
Chlorobenzene
Ethylbenzene
Xylene
1 ,4-Dichlorobenzene
1 , 1 ,2-TrichJoroethane
2-Methylnaphthalene
Naphthalene
Aluminum
Arsenic
6/25
2/25
8/25
14/25
3/25
17/25
6/25
7/25
14/25
2/25
2/25
9/25
14/25
8/25
0.002462
0.001371
0.003035
0.026387
0.001129
0.12
0.003317
0.012807
0.007386
0.000637
0.00214
0.00536
0.449
0.12283
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
3.8189
ND
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NAS Pensacola Operable Unit 1
August 19, 1998
Table 6-2
Exposure Point Concentrations
Media and Chemical
Barium
Bromoform
Zinc
Manganese
Cadmium
Chloroform
Chromium (trivalent)
Copper
Dieldrin
Nickel
Trichloroethene
bis(2-ethylhexyl)phthalate
Chloroe thane
1 . 1 -Dichloroethane
1 ,2-Dichlorobenzene
Exposure
Frequency of Detection
18/25
2/25
12/25
22/25
1/25
2/25
1/25
1/25
1/25
1/25
2/25
1/25
2/25
6/25
8/25
Point Concentrations
RME
0.11293
0.001275
0.4614
0.042009
0.002865
0.002373
0.010594
0.0102
0.0000041
0.030824
0.000637
0.000889
0.000637
0.001559
0.001916
Background
ND
NA
0.0746
0.0215
ND
NA
0.0325
0.0122
NA
ND
NA
NA
NA
NA
NA
Deep Groundwater (mg/L)
Manganese
3/3
0.0901
0.0498
Notes:
RME — Reasonable Maximum Exposure
All results are in milligrams per kilogram or parts per million (ppm).
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Table 6-3
Parameters Used to Estimate Potential Exposures
for Current Land Use Receptors
Pathway Parameters
Trespassing Child
Age 7-16
Units
Incidental Ingestion of Soil
Ingestion Rate
Exposure Frequency
Exposure Duration
Body Weight
Averaging Time-Noncancer
Averaging Time-Cancer
2001
52C
Iff
45"
3,650*
25.550'
mg/day
days/year
years
kg
days
days
Dermal Contact with Soil
Skin Surface Area
Adherence Factor
Absorption Factor
Exposure Frequency
Exposure Duration
Body Weight
Averaging Time-Noncancer
Averaging Time-Cancer
Incidental Surface Water Ingestion
Ingestion Rate
Exposure Frequency
Exposure Duration
Body Weight
Averaging Time-Noncancer
Averaging Time-Cancer
3,959
1*
CSV
52'
Iff
45"
3.650*
25.550'
(while swimming)
0.13'
52"
10*
45'
3,650*
2SUO
cm3
mg/cm2
unitless
days/year
years
kg
days
days
liters/hour
days/year
years
kg
days
days
Inhalation of Volatilized Groundwater Constituents (ORD VOC Guidance)
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Notes:
Trespasser assumptions for soil exposure were used to estimate incidental ingestion and dermal contact with sediment while
swimming (i.e., 16 waking hours per day were adjusted to reflect 2.6 hours swimming exposure per day swimming).
a — USEPA (1989) Risk Assessment Guidance for Superfund Vol. I. Human Health Evaluation Manual (Pan A).
b — USEPA (1991) Risk Assessment Guidance for Superfund Vol. 1, Human Health Evaluation Manual Supplemental
Guidance, Standard Default Exposure Factors. Interim Final, OSWER Directive: 9285.6-03.
c — Assumes a trespass scenario of an adolescent aged 7-16 with an exposure duration (ED) of 10 years and an exposure
frequency of 52 days per year.
d — Adolescent body weight is the average value for the range of body weights for boys and girls ages 7-16 taken from
USEPA (1990) Exposure Factors Handbook, USEPA/600/8-89/043.
e — Calculated as the product of ED (years) x 365 days/year.
f — Calculated as the product of 70 years (assumed lifetime) x 365 days per year.
g — Skin surface area (i.e., worker — head, forearms and hands) provided by USEPA Region iv. For trespassing
children, skin surface area was computed as 25% of the age group mean total body surface per dermal guidance.
NA — Not applicable
CSV — Chemical-specific value
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Table 6-4
Parameters Used to Estimate Potential Exposures
for Future Land Use Receptors
Pathway Parameters
Onsite
Worker
Resident
Adult
Resident Child
Units
Incidental Ingestion of Soil
Ingestion Rate
Exposure Frequency
Exposure Duration
Exposure DurationLWA
Body Weight
Averaging Time-Noncancer
Averaging Time-Cancer
50"
250b
25"
NA
70"
9125C
25.550'
1001
350"
24'
24C
701
8,760"
25,550*
2001
350"
6'
61
15'
2,190"
25,550*
mg/day
days/year
years
years
kg
days
days
Dermal Contact with Soil
Skin Surface Area
Adherence Factor
Absorption Factor
Exposure Frequency
Exposure Duration
Exposure DurationLWA
Body Weight
Averaging Time-Noncancer
Averaging Time-Cancer
4100*
1"
CSV
250"
25"
NA
70"
9125'
25,550'
4,100'
1«
CSV
350"
24C
24C
701
8,760"
25.550*
2.000'
1«
CSV
350»
6'
6'
15'
2,190*
25.550*
cm2
mg/cm2
unitless
days/year
years
years
kg
days
days
Drinking Water Ingestion
Ingestion Rate
Exposure Frequency
Exposure Duration
Exposure DurationLWA
Body Weight
Averaging Time-Noncancer
Averaging Time-Cancer
NA
NA
NA
NA
NA
NA
NA
21
350"
24C
24C
70*
8,760"
25,550*
1*
350"
6'
6'
15'
2.190"
25.550*
liters/day
days/year
years
years
kg
days
days
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Final Record of Decision
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Table 6-4
Parameters Used to Estimate Potential Exposures
for Future Land Use Receptors
Onsite Resident Units
Pathway Parameters Worker Adult Resident Child
Inhalation of Volatilized Groundwater Constituents (ORD VOC Guidance)
Notts:
a — USEPA (1989) Risk Assessment Guidance for Superfund Vol. I, Human Health Evaluation Manual (Pan A).
b — Assumes a residential exposure frequency of 365 days per year with one two-week vacation.
c — USEPA (1991), Risk Assessment Guidance for Superfund Vol. 1, Human Health Evaluation Manual (Pan B,
Development of Risk-based Preliminary Remediation Goals), OSWER Directive 9285.7-O1B.
d — Calculated as the product of ED (years) x 365 days/year.
e — Calculated as the product of 70 years (assumed lifetime) x 365 days per year.
f — Skin surface area (i.e., adult resident — head, forearms and hands; child resident — head, arms, hands, and legs)
provided by USEPA Region IV.
g — Specific guidance from USEPA Region IV (February 11, 1992. New Interim Region IV Guidance).
NA — Not applicable
CSV — Chemical-specific value
falling below or within the range of 1E-6 to 1E-4 is acceptable. Florida considers below 1E-6
acceptable.
RfDs have been developed by USEPA to indicate the potential for adverse health effects from
exposure to COCs with noncarcinogenic effects. RfDs, which are expressed in units of
mg/kg/day, are estimates of lifetime daily exposure levels for humans, including sensitive
individuals, who are likely to be without risk of an adverse affect. Estimated intakes of COCs
from environmental media (e.g., amount of COCs ingested from contaminated groundwater) can
be compared to the RfD. RfDs are derived from results of human epidemiological studies or
chronic animal bioassays to which animal-to-human extrapolation and uncertainty factors have
been applied (e.g., to account for use of animal data to predict effects on humans). If the
estimated exposure to a chemical expressed as mg/kg/day is less than the RfD, exposure is not
expected to cause any noncarcinogenic effects, even if exposure is continued for a lifetime. In
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other words, if the estimated dose divided by the RfD is less than 1.0, there is no concern for
adverse noncarcinogenic effects.
Exposure point concentrations, and toxicity potency factors used to calculate human health risks
are summarized in Table 6-5.
Table 6-5
Toxicological Database Information for Chemicals of Potential Concern
Chemical
1 ,2-Dichloroethene (total)
1 ,4-Dichlorobenzene
Aluminum
Arsenic
Benzene
Barium
Bromoform
Chloroform
Zinc
Beryllium
bis(2-Chloroethyl)ether
bis(2-Ethylhexyl)phthalate
Cadmium (food)
Cadmium (water)
Chlorobenzene
Chromium
Copper
Dieldrin
Lead
Manganese (water)
Manganese (food)
PCB Aroclor-1248
PCB Aroclor-1254
PCB Aroclor-1260
Tetrachloroetbene
Trichloroethene
Oral
Reference Dose
(mg/kg/day)
0.009 b
ND
Ic
0.0003 a
ND
0.07 a
0.02 a
0.01 a
0.3 a
0.005 a
ND
0.02 a
0.001 a
0.0005 a
0.02 a
la
0.0371 b
0.00005 a
ND
0.005 a
0.14 a
ND
0.00002 a
ND
O.Ola
0.006 c
Inhalation
Reference Dose
(mg/kg/day)
ND
0.229
ND
ND
0.00171
0.000143
ND
ND
ND
ND
ND
ND
ND
ND
0.00571
ND
ND
ND
ND
0.0000143
ND
ND
ND
ND
ND
ND
Cancer
Classification
D
B2
ND
A
A
D
B2
B2
D
B2
ND
B2
Bl
Bl
D
D
D
B2
B2
D
D
B2
B2
B2
ND
B2
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Table 6-5
Toxicological Database Information for Chemicals of Potential Concern
Chemical
Oral
Reference Dose
(mg/kg/day)
Inhalation
Reference Dose
(mg/kg/day)
Cancer
Classification
Vinyl Chloride
1 , 1 ,2-TrichJoroethane
1 , 1 ,2,2-Tetrachloroethane
Napthalene
Nickel
4-Chloro-3-methyiphenol
Toluene
Xylene
ND
0.004 a
ND
ND
0.02 a
ND
0.2 a
2a
ND
ND
ND
ND
ND
ND
ND
ND
A
C
ND
D
D
D
D
D
Notes:
a — Integrated Risk Information System (IRIS)
b — Health Effects Assessment Summary Tables (HEAST)
c — USEPA Environmental Criteria and Assessment Office — Cincinnati
A — Human lexicological data have shown a proven correlation between exposure and the onset of cancer
Bl — Some human exposure studies have implicated the compound as a probable carcinogen.
B2 — Possible human carcinogen based on positive laboratory animal data
C — Possible human carcinogen
D — Compound not classifiable with respect to its carcinogenic potential.
ND — Not determined due to lack of information
NA — Not applicable or available
Toxicological data for naphthalene were used as surrogates for 2-methy(naphthalene.
6.4 Risk Characterization
For carcinogens, risks are estimated as the incremental probability of an individual developing
cancer over a lifetime as a result of exposure to the carcinogen. Excess life time cancer risk is
calculated from the following equation:
RISK = CDIxCSF
where:
risk = a unitless probability (e.g., 2 x 10"5) of an individual developing cancer
GDI = chronic daily intake averaged over 70 years (mg/kg-day)
CSF = slope factor, expressed as (mg/kg-day)'1
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These risks are probabilities that are generally expressed in scientific notation (e.g., 1X10* or
IE -6). An excess lifetime cancer risk of 1x10* indicates that, as a reasonable maximum estimate,
an individual has a one in 1,000,000 chance of developing cancer as a result of site-related
exposure to a carcinogen over a 70-year lifetime under specific exposure conditions at OU 1.
The potential for noncarcinogenic effects is evaluated by comparing an exposure level over a
specified time (e.g., lifetime) with a reference dose derived for a similar exposure period. The
ratio of exposure to toxicity is called an HQ. By adding the HQs for all COCs that affect the same
target organ within a medium or across all media to which a given population may reasonably be
exposed, the HI can be generated.
The HQ is calculated as follows:
Noncancer HQ = CDI/RfD
where:
GDI = Chronic Daily Intake
RfD = Reference Dose
GDI and RfD are expressed in the same units and represent the same exposure period (i.e.,
chronic, subchronic, or short-term).
To evaluate estimated cancer risks, a risk level lower than 1x10* is considered a minimal or de
minimis risk. The risk range of 1x10* to IxlO4 is an acceptable risk range for USEPA and would
not be expected to require a response action. A risk level greater than IxlO4 would be evaluated
further, and a remedial action to decrease the estimated risk considered. The State of Florida
considers IxlO"6 and an HI of 1 acceptable.
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An HI of less than unity (1.0) indicates that the exposures are not expected to cause adverse health
effects. An HI greater than one (1.0) requires further evaluation. For example, although HQs of
several chemicals present are added and exceed 1.0, further evaluation may show that their
toxicities are not additive because each chemical affects different target organs. When total effects
are evaluated on an effect and target organ basis, the HI of the separate chemicals may be at
acceptable levels.
Carcinogenic risks and noncarcinogenic hazards were evaluated for potential exposures to
media-specific COCs in surface soil, surface water, surface sediment, and ground water. Receptor
populations were potentially exposed workers, trespassers, and future residents that could,
theoretically, use ground water for a household water source. Risks and hazards for the identified
COCs are summarized in Table 6-6.
Estimated potential exposure to COCs in surface water or sediment did not result in unacceptable
carcinogenic risk or noncarcinogenic hazard. Current site workers and potential child trespassers
did not have an individual pathway or combined single medium pathway with an HI in excess of
0.6 or an ILCR greater than 2E-6. The cross-pathway HI and cancer risk for these two receptor
types were also within the acceptable carcinogenic risk range. These projections indicate that
neither group is at significant risk of deleterious health effects resulting from RME to all media.
These receptor groups do not warrant further consideration.
6.5 Soil Performance Standards for Groundwater Protection
The potential for groundwater contamination due to site compounds was also assessed by
comparing contaminant concentrations in soil with guidance concentrations protective of
groundwater (as identified in FDEP's Soil Cleanup Goals). These concentrations are to-be-
considered (TBC) criteria for the site. Fourteen compounds were identified as exceeding guidance
concentrations when soil concentrations were compared to the leaching criterion.
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Table 6-6
Risk and Hazard for Identified COCs and Pathways of Concerns
Site Trespasser
Chemical HQ ILCR
Site Worker
HQ
ILCR
Potential Future Li
Resident
Adult
HQ
Resident
Child HQ
mdUse
Resident
Iwa
ILCR
Soil Incidential Ingestion Pathway
Beryllium" NA 4.600e-08
Soil Incidential Ingestion Pathway 0.003 7.00e-08
Total
NA
0.004
I 80e-07
3.00e-07
NA
0.01
NA
0.1
1.60e-06
3.00e-06
Shallow/Intennediate Groundwater Ingestion Pathway
1.1,2.2-Tetrachloroethane' NA NA
1.4-Dichlorobenzene* NA NA
Arsenic" NA NA
Barium' NA NA
Benzene" NA NA
Cadmium' NA NA
Chlorobenzene' NA NA
Manganese' NA NA
Vinyl Chloride' NA NA
Shallow/Intermediate NA NA
Groundwater Ingestion Pathway
Total
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
0.001
1.12
0.04
0.42
0.16
0.16
0.23
NA
2
NA
0.002
2.62
0.1
0.99
0.37
0.38
0.54
NA
5
4.10e-06
2.60e-06
2.70e-04
NA
l.lOe-05
NA
NA
NA
V.OOe-05
0.0004
Shallow/Intermediate Groundwater Inhalation Pathway
1,1,2.2-Tetrachloroethane' NA NA
1.4-Dichlorobenzene" NA NA
Benzene" NA NA
Chlorobenzene' NA NA
Chloroform* NA NA
Vinyl chloride' NA NA
Shallow/Intr rmfdiatt Inhalation NA NA
Pathway Total
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
0.001
0.42
0.58
0.01
NA
1
NA
0.002
0.99
1.34
0.02
NA
2
4.IOC-O6
2.60C-O6
l.lOe-05
NA
2.80e-06
l.lOe-05
3.00e-05
Deep Groundwater Ingestion Pathway
Manganese* NA NA
Deep Groundwater Ingestion NA NA
Pathway Total
NA
NA
NA
NA
Notes:
NA - Not applicable
HQ — Hazard Quotient
ILCR — Incremental Lifetime Excess Cancer Risk
a — Beryllium could be considered a COC at only one sample location; beryllium was
b — Chemical is a COC because of projected future resident lifetime weighted average
c — Chemical is a COC because of projected child resident noncarcinogenic hazard.
0.49
0.5
1.2
1
NA
NA
reported in only one of 27 samples.
carcinogenic risk.
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Type A Type B Type C
xylene (exceeded the ethylbenzene tetrachlorethene
secondary but not the toluene 2,4-dinitrotoluene
primary MCL) 1,4-dichJorobenzene 4-methylphenol
1,2-dichlorobenzene bis(2-chlorethyl)ether
pentachlorophenol
2,4-dimethy Iphenol
2-methylphenol
dieldrin
Type A compounds were defined as contaminants in soil exceeding FDEP cleanup goals (CGs)
for teachability in soil and promulgated MCLs, Florida secondary MCLs, or FGGCs in
groundwater beneath Site 1 (based on 1994 groundwater samples).
Type B compounds were present in both soil and groundwater. They exceeded FDEP's CGs for
teachability in soil, but were below MCLs, Florida secondary MCLs, or FGGCs in groundwater
(based on 1994 groundwater samples).
Type C compounds were present in soil, but not detected in groundwater (based on 1994
groundwater samples).
6.6 Risk Uncertainty
The following areas of uncertainty were associated with the estimation of chemical uptake from
exposure to groundwater.
The primary source of uncertainty in the groundwater exposure pathway is the potable use
assumption, which represents a highly conservative approach to assessing the significance of
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ground water impacts. The combined shallow/intermediate water-bearing zone (WBZ) is not
currently used onsite as an industrial or potable water source, nor is it anticipated to be in the
future. Assuming that homes were constructed on the landfill and the residents installed unfiltered
wells for potable use is an extremely conservative assessment of future aquifer use. The deep
WBZ was assessed separately under the same assumptions, but the shallow and intermediate WBZs
were combined. If the future-use scenario were to exist, and a future potable well was screened
exclusively in the shallow or intermediate WBZ, a change in the estimated risk/hazard could be
expected.
Supplemental guidance was presented in draft form in June 1994 by USEPA Region IV to
streamline the approach used to address contaminant inhalation via the ground water exposure
pathway. According to the draft supplemental guidance, the GDI for the inhalation pathway is
equivalent to that of the ingestion pathway, where 2 liters of groundwater are ingested daily.
According to the draft guidance, the risk/hazard posed by the pathways is cumulative; two times
the oral ingestion pathway GDI has been proposed as an equivalent calculation for the cumulative
ingestion and inhalation exposure pathways. Previously, these pathways were calculated
separately using chemical-specific factors and pathway-specific exposure assumptions. In addition
to these factors, this draft method does not consider fugacity (i.e., the propensity for a substance
to "break free" from the containing medium) as part of the suggested calculation. This proposed
method includes the inhalation reference dose or slope factor, but it is applied to the ingestion
formula.
An similar approach for limiting RME uncertainties was taken for groundwater. It would be
implausible to expect an individual to be chronically exposed to the maximum concentration of
each groundwater chemical. Substitution of the 95% upper confidence limit (UCL) mean
concentration (where possible) for each chemical provides a reasonably conservative estimate of
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the chronic concentrations to which an individual may be exposed via the groundwater pathway.
Spatial analysis shows that inorganic and organic COPCs did not consistently coexist, and
detections appeared to be random rather than suggestive of a defined plume.
Many essential nutrients were detected in the shallow, intermediate, and deep WBZs. These
essential nutrients would be expected due to possible saltwater intrusion. In addition to these
nutrients, arsenic would be expected to be present (as it is in seafood). Arsenic did not exceed its
federal MCL or FPDWS at the maximum concentration detected. At the exposure point
concentration (EPC), arsenic poses 3.2E-4 excess cancer risk, approximately 80% of the total risk.
Groundwater metals concentrations were obtained from unfiltered samples. As mentioned
previously, filtration would likely be a part of any system deriving water from the shallow WBZ
for potable use. The groundwater in this aquifer has been shown to be highly turbid and to contain
natural iron, manganese, and sodium concentrations exceeding FSDWS. A large portion of the
aquifer yields dark brown, highly organic pore water with an acrid H^S odor, which could be the
result of reduced manganese and iron. Based on natural qualities, the aquifer does not appear
suitable as a drinking water supply either in impacted or unimpacted areas.
As discussed for exposure to surface soil, uniform exposure was assumed for all monitoring well
data from Site 1. Percent area affected was not applied to the risk projections, and this is a highly
conservative approach, especially in the case of the low frequency of detected COPCs. As
discussed above, the likelihood that the aquifer would be used as a drinking water supply is
extremely low. Also previously discussed is the Navy's intention for continued operations, which
indicates the area will remain a limited access area. Since COCs were identified assuming potable
water use by site residents, the conservatism and resulting overestimation of risk projections are
substantial. All assumptions regarding the evaluation of shallow and intermediate groundwater
and deep groundwater as potential sources of potable water are the same for this risk assessment.
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Few COCs are identified for the residential exposure pathways (potential future use) only, and the
COPCs identified are based on conservative assumptions for all exposure pathways.
The following are uncertainties associated with estimation of risks:
In hazard and risk evaluations, risks or hazards presented by several chemicals reported for the
same exposure have been added to provide a sum of estimated total risk or hazard for that
particular exposure. This is a conservative assumption and is scientifically accurate only in those
instances where health effects of individual chemicals are directed at the same effect and same
target organ. Effects may be additive, synergistic, or antagonistic. Since many chemicals have
no similarity as to their noncarcinogenic action or target of their action, this approach may
overestimate risk.
Risks calculated from slope factors are derived using a linearized multistage procedure; therefore,
they are likely to be conservative upper-bound estimates. Actual risks may be much lower.
6.7 Human Health Risk Summary
Risk and/or hazard associated with exposure to all environmental media (and combinations) was
within USEPA's and FDEP's generally acceptable ranges for both current site workers and
potential current child trespassers.
For an unlikely hypothetical future site resident, exposure media were shown to exceed acceptable
residential goals. These media included shallow/intermediate and deep ground water.
Shallow/Intermediate Groundwater RGOs
Table 6-7 provides remedial goal options (RGOs) for the combined shallow/intermediate
groundwater pathways (ingestion/inhalation exposures). The EPCs for 1,4-dichlorobenzene,
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Table 6-7
Remedial Goal Options for Shallow/Intermediate Groundwater
Hazard-based RGOs Hazard
Carcinogenic Risk-based RGOs Goal
Reference
EPC Concentration
Chemical l.OOe-04 l.OOe-05 l.OOe-06 10 1 0.1 (mg/L) (mg/L)
U,2.2-T«trtchloroeth»ne 1.70e-02 l.70e-03 1.70e-04 NA
"1,4-Dichlorobenzene 1.40e-OI 1.40e-02 1.40e-03 17.9
"Arsenic"
"Barium*
Benzene
"Cadmium'
"Nickel*
"Chlorobenzene
"Manganese*
Vinyl Chloride
"Chloroform
Notti:
NA
ND
FPDWS
FDWS-C -
«
** _
EPC
mg/L -
4.50B-03 4.50e-04 4.50e-OS 0.047
NA NA NA 11.0
I.90C-OI l.90e-02 1 .90e-03 0.27
NA NA NA 0.078
NA NA NA 3.1
NA NA NA 3.1
NA NA NA 0.78
3.50e-03 3.506-04 3.50e-05 NA
7.20e-03 7.20C-04 7.20e-05 1.6
NA
1.79
0.0047
1.10
0.027
0.0078
0.31
0.31
0.078
NA
0.16
NA 0.0014 NA
0.179 0.0074 NA
0.00047 0.012 ND
0.110 0.113 ND
0.00267 0.026 NA
0.00078 0.0029 ND
0.031 0.0308 ND
0.031 0.12 NA
0.0078 0.042 0.0215
NA 0.0025 NA
0.016 0.0024 NA
ARAR
(mg/L) Source
0.0002 FDWS-C
0.075 FPDWS
0.05 FPDWS
2 FPDWS
0.001 FPDWS
0.005 FPDWS
O.I FPDWS
O.I MCL-
monochlorobenzene
0.05 FSDWS
0.001 FPDWS
0.006 FDWS-C
Indicates an RGO was not applicable for this chemical under risk and/or hazard-based conditions.
Indicates (he chemical was not detected in reference (background) wells.
Means Florida Primary Drinking Water Standard.
Indicates Florida guidance concentration based on carcinogeniciry.
Indicates the inhalation pathway was not considered in establishing RGOs.
Indicates the ARAR is greater than the EPC.
Exposure Point Concentration
milligrams per liter
Noncarcinogenic hazard-based RGOs were computed based on the future child site resident scenario with combined ingestion and inhalation exposure (where applicable).
Carcinogenic risk-based RGOs were computed based on the future site resident lifetime weighted average scenario with combined ingestion and inhalation exposure (where applicable).
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arsenic, barium, cadmium, nickel, chlorobenzene, manganese, and chloroform are below
corresponding ARARs, which may influence remediation levels deemed necessary.
Deep Groundwater RGOs
The RGOs for the deep groundwater pathway are provided in Table 6-8. The COC is potentially
related to saltwater intrusion and/or natural ambient groundwater concentrations.
6.8 Ecological Considerations
Ecological risks at Site 1 were determined to be inconsequential for flora and fauna from
contaminated soil. Based on a review of the factors that may affect availability of chemicals, and
a critical assessment of the concentrations observed during the 1994 sampling activity, no
appreciable ecological effects are expected from groundwater discharge to wetlands, other than
Wetland 3, near Site 1. The risk to ecological receptors at Wetland 3 has been evaluated by
comparing sediment and surface water concentrations to established screening values from FDEP
and USEPA Region 4. Contaminants of concern are primarily metals and pesticides. Benthic
community species and fish in downgradient sections of the wetland are potentially exposed
to excess risk. Methods proposed to assess risk to receptors for Phase IIB of the Site 41 RI are
bioassays for benthic and fish species. All contaminants will be studied further during the
Bayou Grande (Site 40) and NAS Pensacola wetlands remedial investigations (Site 41).
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Carcinogenic Risk-Based RGOs Risk Goal
Chemical l.OOe-04
1E-05
1E-06
Table 6-8
Remedial Goal Objectives for Deep Groundwater
Noncarcinogenic Hazard-Based RGOs (mg/L)
Hazard Index Goal
10
0.1
Exposure Point Reference
Concentration Concentration ARAR
(mg/L) (mg/L) (mg/L)
Source
Mannnese
NA
NA
NA
0.000
0.0000
0.090
JJJJ215
0.05
FSDWS
Notes:
NA — Indicates an RGO was not applicable for this chemical under risk and/or hazard-based conditions.
FSDWS — Means Florida Secondary Drinking Water Standard, SMCL means Secondary Maximum Contaminant Levels
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7.0 DESCRIPTION OF THE REMEDIAL ALTERNATIVES
The OU 1 FFS report and addendum presented the detailed analysis results on four potential
remedial action alternatives. These alternatives were developed to provide a range of remedial
actions for the site. This section of the ROD summarizes the four alternatives described in the
FFS report and addendum, which include:
• No Action
• Natural Attenuation
In addition, three natural attenuation options have been developed addressing Wetland 3
and the outfall for Wetland 3 into Wetland 4D.
a) Natural attenuation with monitoring only of the water entering and leaving Wetland 3
b) Natural attenuation for the landfill and enhancement of Wetland 3 to improve its
effectiveness
c) Natural attenuation for the landfill with interception and treatment of groundwater
before reaching Wetland 3
• Capping
• Groundwater Extraction and Treatment
These four remedial action alternatives were developed to address contaminated groundwater and
soil and various OU 1 areas of concern (AOCs). The AOCs were identified by comparing media-
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specific contaminant concentrations detected at OU 1 to media-specific remediation goals
developed in the FFS and the FFS addendum. The AOCs identified for OU 1 are:
• Contaminated soil above FDEP teachability guidance (TBCs)
• Contaminated groundwater above performance standards
• Contaminated surface water above performance standards
Figure 7-1 shows the general location of the AOCs for soil, groundwater, and surface water.
Table 7-1 summarizes the remedial objectives. Performance standards are defined in Section 9.
A concise description of how each alternative will address contamination at OU 1 as well as
estimated cost follows.
Media
Objective
Table 7-1
SUe 1 - Remedial Objectives
Location
Volume
Rationale
Waste Protect groundwater from
leachable compounds
Groundwater Restore site groundwater to
MCLs and prevent further
contamination of
shallow/intermediate
groundwater
Surface Water Prevent further contamination of
surface water in Wetland 3
Entire landfill
Central, northern,
western, and eastern
portions of Site 1
i700,000 yd1
210 million gallons
eastern portion of Site 1 1,156 million gallons
Entire waste component
may be leaching
contaminants to
groundwater (TBC).
Groundwater exceeding
MCLs (ARARs).
Surface water exceeding
SWQS (ARARs).
Nole:
yd* — Cubic yards
7.1 Alternative 1: No Action
Capital Cost:
Annual Operation and Maintenance (O&M) Costs:
Net Present Worth
$0.00
$0.00
$0.00
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GRANDE
01GGM04
01GGM35 „'
01GI28 «\01GGM
01S76-10
LEGEND
« - SHALLOW MONITORING WELL
« - DEEP MONITORING WELL
4> - INTERMEDIATE MONITORING WELL
• - SHALLOW SOIL BORING
AREAS ABOVE FLORIDA'S
PROTECTION OF GROUNDWATER
LEACHABILITY PRGs
AREA OF GROUNDWATER
CONTAMINATION
RECORD OF DECISION
SITE V
NAS PENSACOLA
nGURE 7-1
AREAS OF CONCERN
)WG DATT: 12/O5/97 IDWC
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The NCP requires consideration of a no-action alternative as a baseline against which other
alternatives are compared. In the no-action alternative, no further action will be taken to contain,
remove, or treat soil and ground water contaminated above performance standards.
Health risks for the future resident will remain and no chemical-specific ARARs will be met. This
alternative does not meet the effectiveness criterion because it does not reduce future exposures
for the unlikely future child resident through exposure to groundwater. Contaminated waste/soil
may threaten site groundwater.
7.2 Alternative 2: Natural Attenuation
This alternative would include:
• Institutional controls imposed in accordance with the LURA to restrict groundwater use
of the surficial zone of the Sand-and-Gravel Aquifer within 300 feet of the site.
• Institutional controls imposed in accordance with the LURA to limit intrusive activities
within the landfill boundary without prior approval from the NAS Pensacola
Environmental Office.
• Annual review of the institutional controls and certification that the controls should remain
in place or be modified to reflect changing site conditions
• Groundwater monitoring to ensure that natural attenuation processes would be effective and
that contaminants would not migrate.
• A review during which the Navy would determine whether groundwater performance
standards continue to be appropriate and if natural attenuation processes are effective.
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• Continued groundwater monitoring at sampling intervals to be established by the Navy
with FDEP and USEPA concurrence. The groundwater monitoring program would
continue until the alternative has achieved continued attainment of the performance
standards and remains protective of human health and the environment.
Groundwater samples would be collected in accordance with the monitoring plan to be completed
during remedial design. Proper well construction and development techniques, along with a low
flow sampling method, would be used during the monitoring. The Navy may revise the
groundwater monitoring program sampling intervals with USEPA and FDEP concurrence.
In addition, three natural attenuation options have been developed to address Wetland 3 and the
outfall for Wetland 3 into Wetland 4D. Natural attenuation costs for the landfill are included in
each subaltemative.
7.2.1 Alternative 2a: Contaminated Groundwater Discharge into Wetland 3 with
Monitoring Only
Capital Cost: $211,500.00
Annual Operation and Maintenance (O&M) Costs: $358,700.00
Net Present Worth $3,258,600.00
Under this alternative, no active remedial steps are taken and the wetland is included in the
monitoring plan presented for the landfill in the original FFS. Natural processes that decrease
contamination of the water discharging into the wetland are monitored to ensure that they are
proceeding as expected. It is expected that surface water standards would continue to be exceeded
for some time.
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7.2.2 Alternative 2b: Enhancement of Wetland 3
Capital Costs: $816,400.00
Annual Operation and Maintenance (O&M) Costs: $179,900.00
Net Present Worth $4,278,500.00
Wetlands improve water quality through independent and interactive physical, chemical, and
biological processes. Wetlands physically remove suspended solids from water in two ways.
First, suspended solids settle to the bottom; increased retention times and contact with plant
materials enhance this process. Secondly, absorption of suspended solids to sediment and plant
material results in removal of suspended material. Chemical removal occurs when chemical
constituents attach or sorb onto solids. Increased water surface area for gas exchange improves
dissolved oxygen content for decomposition of organic compounds and oxidation of many metal
ions. However, the most important attenuation processes are biological and similar to those
occurring in conventional treatment plants. Like conventional treatment plants, wetlands provide
a suitable environment for abundant microbial populations. Wetlands require larger treatment
areas than conventional treatment plants to establish stable, low maintenance environments for
similar microbes, but may support additional types of microorganisms because of the diverse
mixture of microenvironments. Having a more diverse microenvironment and a larger treatment
area than conventional treatment plants produces lower discharge concentrations of water-borne
pollutants.
The principal function of vegetation in wetlands systems is to create additional environments for
microbial populations. Not only do the stems and leaves in the water column obstruct flow and
facilitate sedimentation, they provide substantial amounts of surface area for attachment of
microbes (reactive surfaces). Plants also increase the amount of aerobic microbial environment
incidental to the unique adaption that allows wetland plants to thrive in saturated sediments. Most
plants are unable to survive in water-logged soil because their roots cannot obtain oxygen in the
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anaerobic conditions created after inundation. However, hydrophilic plants have specialized
structures in their leaves, stems, and roots similar to a mass of breathing tubes that conduct
atmospheric gases, including oxygen, down into the roots. Because the root hair outer covering
is not a perfect seal, oxygen leaks out, creating a thin aerobic region around each root hair. In
addition, the ability of vascular plants to absorb and concentrate heavy metals is well-documented.
Plants would limit the growth of algae in the system by restricting the penetration of sunlight and
competing for available nutrients.
7.2.3 Alternative 2c: Groundwater Interception, Treatment and Reintroduction to
Wetland 3
Capital Cost: $559,000.00
Annual Operation and Maintenance (O&M) Costs: $209,800.00
Net Present Worth $4,542,600.00
In this alternative, a groundwater interception system would be installed to capture the
contaminated groundwater upgradient of Wetland 3. This extracted groundwater would be treated
to reduce iron levels and then reintroduced into Wetland 3. This alternative addresses Wetland 3
surface water exceedances by preventing water with high iron content from entering the wetland,
while at the same time having a minimal effect on the wetland's water level.
Based on areal extent of apparent contamination in the surficial aquifer, and specific characteristics
of the aquifer (hydraulic conductivity, aquifer thickness) and subject to the detailed
Remedial Design, an eight-well recovery system was conceptualized for the purpose of developing
costs for the Feasibility Study. The actual method of groundwater interception will be determined
during Remedial Design and may involve alternatives to wellpoint extraction (e.g., trenching,
walls, etc.). The hydrogeological basis for the current conceptual design is the groundwater model
prepared for and presented in the Final Focused Feasibility Study which may be consulted for
details.
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Due to the high concentration of iron in the groundwater stream, iron removal will be required
before the intercepted groundwater is reintroduced to Wetland 3. The various physical and
chemical processes (e.g., pH adjustment, flocculation, coagulation, oxidation, etc.) by which iron
may effectively be removed to concentrations below the RGOs will be evaluated during
Remedial Design. For the purpose of developing costs for use in the Feasibility Study, the
conceptual treatment scheme was based on an oxidation process. An aeration/pH adjustment tank
would enhance removal of the dissolved iron prior to filtration, while air would promote the
oxidation of iron from the soluble ferrous state to the insoluble ferric state. The iron removal filter
removes suspended particulates and iron bacterial residue from the groundwater. Particulates are
removed by a combination of gravity settling and filtration on a series of nonwoven fabric filter
plates.
The system design was based on the following assumptions:
• The groundwater flow is 110 gpm.
• The facility would be manually controlled.
• The system's design life is 20 years.
• The iron concentration in groundwater is 73 ppm.
• The desired effluent concentration is 1,000 ppb maximum.
A more complete description of the conceptual design used to develop the cost of this alternative
may be found in the Focused Feasibility Study Addendum. Again, this conceptual design was
intended to be used for FFS purposes only. Details on the groundwater interception system and
iron removal system will be developed during Remedial Design.
Under this alternative, the iron removal system may also provide some incidental treatment of the
other contaminants (primarily organics) present in the extracted groundwater. However, the
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primary reduction of remaining contaminant concentrations would be through natural attenuation
after the water is reintroduced to Wetland 3. These naturally occurring biotic and abiotic
processes are described fully under Alternative 2b, above.
7.3 Alternative 3: Capping
Capital Cost: $10,813,200.00
Annual Operation and Maintenance (O&M) Costs
(for 30 years): $140,400.00
Net Present Worth $13,450,400.00
This alternative includes:
• Institutional controls imposed in accordance with the LURA to restrict groundwater use
of the surficial zone of the Sand-and-Gravel Aquifer within 300 feet of the site.
• Institutional controls imposed in accordance with the LURA to limit intrusive activities
within the landfill boundary.
• Construction and maintenance of a clay cap for 30 years.
• A review during which the Navy would determine whether groundwater performance
standards continue to be appropriate and if natural attenuation processes are effective.
• Continued groundwater monitoring at sampling intervals to be established by the Navy
with Florida and USEPA concurrence. The groundwater monitoring program would
continue until the alternative has achieved continued attainment of the performance
standards and remains protective of human health and the environment.
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Capping reduces the risk of contact with contaminated soil and reduces the quantity of leachate
generated when rainwater filters through contaminated waste/soil. With the capping alternative,
approximately 85 acres will be capped with clay. The entire site is cleared, grubbed, and graded
before cap installation. Storm water runoff is controlled by perimeter ditches that collect and
direct it away from the site. Under this alternative, groundwater is monitored and with little
additional contamination, is expected to meet remedial goals through natural attenuation over time.
Regular maintenance is required, such as inspecting, mowing, and repairing the cap. The present
cost of this alternative is estimated at $13,450,400, assuming 30 years of maintenance.
7.4 Alternative 4: Groundwater Extraction with Treatment for the Entire Landfill
Groundwater Extraction
Capital Cost: $753,300.00
Annual Operation and Maintenance (O&M) Costs: $132,200.00
Net Present Worth $3,198,500.00
Air Stripping
Capital Cost: $149,500.00
Annual Operation and Maintenance (O&M) Costs: $82,300.00
Net Present Worth $2,000,000.00
Constructed Wetlands
Capital Cost: $866,800.00
Annual Operation and Maintenance (O&M) Costs: $54,000.00
Net Present Worth $2,431,100.00
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This alternative would include:
• Institutional controls imposed in accordance with the LURA to restrict groundwater use
of the surficial zone of the Sand-and-Gravel Aquifer within 300 feet of the site.
• Institutional controls imposed in accordance with the LURA to limit intrusive activities
within the landfill boundary without prior approval from the NAS Pensacola
Environmental Office.
• A groundwater monitoring program to ensure that the groundwater treatment system would
be effective and that contaminants would not migrate.
• Active remediation of groundwater. Groundwater extraction and treatment would continue
until all performance standards are met for two consecutive sampling events.
• Continued groundwater monitoring upon attainment of the performance standards at
sampling intervals established during remedial design. The groundwater monitoring
program would continue until a five-year review concludes that the alternative has achieved
continued attainment of the performance standards and remains protective of human health
and the environment.
If implemented, the groundwater extraction system shall consist of a group of wells within the
estimated plume area. The pumping system shall be designed to provide a capture zone sufficient
to intercept the delineated plume targeted for extraction. The effectiveness of the groundwater
extraction system depends on the aquifer characteristics, transmissivity, and storativity. Typically,
these design criteria are developed by aquifer testing based on constant discharge pumping and/or
recovery tests. Pumping tests and modeling shall be required before extraction. The number of
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wells, estimated at 20, and system extraction rate, estimated at a combined 80 gallons per minute,
will be determined during remedial design. The two treatment processes considered under this
alternative are constructed wetlands and air stripping, which are described below.
Air Stripping
Air stripping is an established technology by which volatile organics are partitioned from
groundwater by greatly increasing the surface area of the contagttftjHxi water exposed to air.
Types of aeration methods include packed towers, diffused aeration, tray aeration, and spray
aeration. In this FFS, tray aeration was chosen for implementation at Site 1. The following
variables may limit the applicability and effectiveness of the process:
• Equipment may be fouled by inorganic or biological constituents. Ferrous iron precipitates
as insoluble ferrous hydroxide species upon aeration. Air strippers must be taken out of
service and packing materials acid-washed.
• Consideration should be given to the Henry's Law constant of the VOCs in the water
stream.
• Compounds with low volatility at ambient temperature may require pre-heating the
groundwater.
A pretreatment process using sodium hydroxide to raise the pH and precipitate metals from the
water will be included in the treatment train for air stripping. The water will then be treated with
air stripping and the waste residuals will be disposed of offsite at a licensed treatment, storage,
and disposal facility.
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This established technology can be implemented with a minimum of testing. Treated water must
be discharged to surface water, reinjected into the underlying aquifer, or discharged to a federally
owned treatment works (FOTW). The process of extracting groundwater eliminates contaminant
migration.
Contaminated groundwater would be extracted, treated, and discharged in accordance with
National Pollution Discharge Elimination System (NPDES) permit requirements. If an NPDES
is not viable, other discharge alternatives such as discharge to the Navy-owned wastewater
treatment plant would be considered. Onsite treatment would likely be required so that the treated
water would meet permit requirements for discharge to a nearby surface water body. The number
of extraction wells and pumping rates will be determined during remedial design.
Constructed Wetlands
Constructed wetlands are man-made systems that are designed, built, and operated to perform the
functions of natural wetlands for treatment of contaminated water. Wetlands improve water
quality through physical, chemical, and biological processes operating independently and also
interactively. The removal mechanisms for suspended solids in the wetlands treatment system
essentially fall under two processes. The first is sedimentation in which the suspended solids
ultimately settle to the bottom. Retention times and contact with plant materials enhance this
process. Absorption of suspended solids also aids in this reduction process. Many chemical
constituents tend to attach or sorb onto solids. Absorption, combined with solids settling, removes
constituents from the water column that otherwise could remain. Increased water surface area for
gas exchange improves dissolved oxygen content for decomposition of organic compounds and
oxidation of many metalic ions. But the most important processes are similar to transformations
occurring in conventional treatment plants. Wetlands, like conventional treatment systems, simply
provide suitable environments for abundant microbial populations. Wetland systems use larger
treatment areas to establish stable, low maintenance systems providing environments for similar
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microbes, but may support additional types of microorganisms because of the diverse mixture of
microenvironments. The latter, along with a larger treatment area, frequently provides more
complete reduction and lower discharge concentrations of water-borne pollutants.
The principal function of vegetation in wetlands systems is to create additional environments for
microbial populations. Not only do the stems and leaves in the water column obstruct flow and
facilitate sedimentation, they also provide substantial amounts of surface area for attachment of
microbes — reactive surfaces. Plants also increase the amount of aerobic microbial environment
in the substrate incidental to the unique adaptation that allows wetlands plants to thrive in saturated
soil. Most plants are unable to survive in water-logged soil because their roots cannot obtain
oxygen in the anaerobic conditions rapidly created after inundation. However, hydrophytic or
wet-growing plants have specialized structures in their leaves, stems, and roots somewhat
analogous to a mass of breathing tubes that conduct atmospheric gases, including oxygen, down
into the roots. Because the root hair outer covering is not a perfect seal, oxygen leaks out,
creating a thin aerobic region around each root hair. In addition, the ability of vascular plants to
absorb and concentrate heavy metals is well-documented.
Constructed wetlands provide an onsite treatment that requires little maintenance or power after
a landfill is closed. They provide several characteristics that are beneficial for leachate treatment
including large vegetative bio-mass, large adsorptive surfaces on sediments and plant material,
aerobic/anaerobic interfaces, and diverse, active microbial populations. Plants also provide a
more rapid decrease in leachate volume through transpiration than lagoons without plants.
Although constructed wetlands is an emerging technology, it is based on well-established processes
and can be implemented, but requires substantial testing and planning. Also, treated water must
be discharged to surface water or reinjected into the underlying aquifer. The process of collecting
leachate from the groundwater eliminates contaminant migration.
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The present worth cost of this alternative ranges from $5,216,500 (air stripping) to $5,629,500
(constructed wetlands) for 30 years O&M for an 80-gallon per minute (gpm) treatment system.
7.5 Applicable or Relevant and Appropriate Requirements
The remedial action for OU 1, under CERCLA Section 121(d), must comply with federal and state
environmental laws that are either applicable or relevant and appropriate. Applicable requirements
are standards, criteria, or limitations promulgated under federal or state law that specifically
address a hazardous substance, pollutant, contaminant, remedial action, location, or other
circumstance at a CERCLA site. Relevant and appropriate requirements are those that, while not
applicable, still address problems or situations sufficiently similar to those encountered onsite that
their use is well-suited to the particular site. TBC criteria are nonpromulgated advisories and
guidance that are not legally binding, but should be considered in determining the necessary level
of cleanup for protection of health or the environment.
The affected groundwater in the aquifer beneath OU 1 has been classified by USEPA and FDEP
as Class HA and G-l, a potential source of drinking water. It is Florida and USEPA's policy that
groundwater resources be protected and restored to their beneficial uses. A complete definition
for USEPA's groundwater classification is provided in the Guidelines for Groundwater
Classification under the EPA Groundwater Protection Strategy, Final Draft, December 1986.
Florida groundwater classification is defined in Chapter 62-520, Groundwater Classes, Standards,
and Exemptions.
While TBCs do not have the status of ARARS, the approach to determining if a remedial action
is protective of human health and the environment involves consideration of TBCs, along with
ARARs. Potential ARARs for all of the alternatives are presented in the feasibility study
completed for OU 1.
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Location-specific ARARs are restrictions placed on the concentration of hazardous substances or
the conduct of activities solely on the basis of location. Examples of location-specific ARARs
include state and federal requirements to protect floodplains, critical habitats, and wetlands, and
solid and hazardous waste facility siting criteria. Table 7-2 summarizes the location-specific
ARARs for OU 1 for the selected remedy.
Action-specific ARARs are technology- or activity-based requirements or limitations on actions
taken with respect to hazardous wastes. These requirements are triggered by the particular
remedial activities that are selected to accomplish a remedy. Table 7-3 lists action-specific ARARs
and TBCs for the OU 1 selected remedy.
Chemical-specific ARARs are specific numerical quantity restrictions on individually listed
chemicals in specific media. An example of a chemical-specific ARAR is the MCLs specified
under the Safe Drinking Water Act. Since there are usually numerous chemicals of concern for
any remedial site, various numerical quantity requirements can be ARARs. Table 7-4 lists
chemical-specific ARARs for OU 1 for the selected remedy.
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Table 7-2
Potential Location-Specific ARARs for the Selected Remedy
Requirements Status Requirement Synopsis Application to the RI/FS
Federal Requirements
Executive Order 11990 Applicable Sets forth policy for the protection of wetlands Several wetlinds on Site 1 fit the definition under the
Wetlands Protection Policy Executive Order.
State Requirements
None
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Requirements
Table 7-3
Potential Action-Speclfk ARARs for the Selected Remedy
Status Requirement Synopsis
Application to the RI/FS
Federal Requirements
RCRA Groundwiter Monitoring Requirements Relevant and
40 CFR 264 Subpirt F Appropriate
Clean Water Act Discharge Limitations NPDES Applicable
Permit
40 CFR 122, 125, 129, 136
Pretreatment Standards
40 CFR 403.5
Safe Drinking Water Act Underground Injection Applicable
Control Program
40 CFR 144
Establishes minimum requirements for groundwater
monitoring and protection standards for RCRA facilities.
Prohibits unpermitted discharge of any pollutant or
combination of pollutants to waters of the U.S. from any
point source. Standards and limitations are established
for these discharges
Regulates the use of five classes of underground
injection wells for (he purpose of disposal of hazardous
substances.
Onsite treatment, storage, and/or disposal of RCRA
wastes may be included in die remediation of Site I.
Remedial actions may include the discharge of treated
groundwater, runoff, or other flows to a surface water.
Would be applicable if injection well technology is used
as a pan of site remediation.
State Requirements
Florida Rules on Permits Applicable
Tide 62 Chapter 62-4
Florida Underground Injection Control Applicable
Regulations
Title 62 Chapter 62-28
RCRA Solid Waste Groundwiter Monitoring Applicable
Requirements
Establishes antidegradation requirements.
Establishes construction standards, permitting
procedures, and operating requirements for underground
injection wells.
Establishes monitoring requirements
Requirements may be applicable to site depending upon
remedial actions and discharge options selected.
Remedial actions may include underground injection as a
disposal option for treated effluent.
Remedial action will require monitoring
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Requirements
Status
Table 7-4
Potential Chemical-Specific ARARs for the Selected Remedy
Requirement Synopsis
Application to the RI/FS
Federal Requirements
RCRA Maximum Concentration Limits Applicable
40 CFR 264 Subpart F
Safe Drinking Water Act MCLs 40 CFR Applicable
141.11 - 141.16
Safe Drinking Water Act MCLGs Relevant and
40 CFR 141.50-141.51 Appropriate
Maximum Concentration Levels have been established for 14
toxic compounds under RCRA groundwater protection standards.
A compliance monitoring program is included for RCRA
facilities.
MCLs have been set for toxic compounds as enforceable
standards for public drinking water systems. SMCLs are
unenforceable goals regulating the aesthetic quality of drinking
water.
MCLGs are unenforceable goals under the SDWA.
Applicable to Site 1 with current groundwater monitoring
program; also applicable where identified hazardous wastes
are treated, stored, or disposed onsite.
The Sand- and-Gravel Aquifer is a potential source of drinking
water. Some contaminants in the plume below Site I are
above MCLs and SMCLs.
The Sand-and-Gravel Aquifer is a potential source of drinking
water. Some contaminants is plume below Site 1 are above
non-zero MCLGs.
SUte Requirements
Florida Water Quality Standards
Title 62 Chapter 62-3
Florida Surface Water Standards
Tide 62 Chapter 62-301 and
62-302
Florida Drinking Water Standards
Title 62 Chanter 62-550
Applicable Establishes minimum water quality criteria for groundwater.
Applicable Establishes water quality standards for all waters of (he state.
Applicable Establishes MCLs for drinking water. Establishes secondary
requirements for drinking water.
Remedial objectives require remediation of Sand-and-Gravel
Aquifer.
Remedial objectives require protection of surficial waier.
Remedial actions may impact surficial water bodies.
Remedial objectives require restoration of Sand- and-Gravel
Aquifer to drinking water standards.
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8.0 COMPARATIVE ANALYSIS OF ALTERNATIVES
This section of the ROD provides the basis for determining which alternative provides the best
balance with respect to the statutory balancing criteria in Section 121 of CERCLA, 42 U.S.C.
Section 9621, and in the NCP, 40 CFR, Section 300.430. The major objective of the FFS and
addendum was to develop, screen, and evaluate alternatives for remediating OU 1. Alternatives
and technologies were identified as potential candidates to remediate the contamination at OU 1.
These were screened based on their feasibility with respect to the contaminants present and site
characteristics. After the initial screening, the remaining alternatives/technologies were combined
into potential remedial alternatives and evaluated in detail. The remedial alternative was selected
from the screening process using the following nine evaluation criteria:
• Overall protection of human health and the environment.
• Compliance with applicable and/or relevant federal or state public health or environmental
standards.
•
• Long-term effectiveness and permanence.
• Reduction of toxicity, mobility, or volume of hazardous substances or contaminants.
• Short-term effectiveness or the impacts a remedy might have on the community, workers,
or the environment during implementation.
• Implementability, that is, the administrative or technical capacity to carry out the
alternative.
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• Cost-effectiveness, considering costs for construction, operation, and maintenance of the
alternative over the life of the project, including additional costs should it fail.
• Acceptance by the state.
• Acceptance by the community.
The NCP categorizes the nine criteria into three groups:
• Threshold Criteria — Overall protection of human health and the environment and
compliance with ARARs (or invoking a waiver) are threshold criteria that must be satisfied
for an alternative to be eligible for selection.
• Primary Balancing Criteria — Long-term effectiveness and permanence; reduction of
toxicity, mobility or volume; short-term effectiveness; implementability and cost are
primary balancing factors used to weigh major trade-offs among alternative hazardous
waste management strategies.
• Modifying Criteria — State and community acceptance are modifying criteria that are
formally taken into account after public comments are received on the proposed plan and
incorporated into ROD.
The selected alternative must meet the threshold criteria and comply with all ARARs or be granted
a waiver for compliance with ARARs. Any alternative that does not satisfy both of these
requirements is not eligible for selection. The Primary Balancing Criteria are the technical criteria
upon which the detailed analysis of alternatives is primarily based. The final two criteria, known
as Modifying Criteria, assess the acceptance of the alternative.
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The following analysis summarizes the evaluation of alternatives for remediating OU 1 under each
of the criteria. Each alternative is compared for achievement of a specific criterion.
8.1 Threshold Criteria
All alternatives considered for selection must comply with the threshold criteria, overall protection
of human health and the environment, and compliance with ARARs.
8.1.1 Overall Protection of Human Health and the Environment
This criterion evaluates the degree of overall protectiveness afforded to human health and the
environment. It assesses the overall adequacy of each alternative.
The no-action alternative will not mitigate the risks associated with contamination at or originating
from OU 1. Therefore, this alternative is not protective of human health and the environment and
will no longer be considered in this discussion.
Alternatives 2 and 3 would use groundwater monitoring and apply natural attenuation processes
to meet groundwater performance standards. Since there is no current direct exposure route to
groundwater, natural attenuation of groundwater contamination is protective. In addition, risk
and/or hazard associated with exposure to surface water and sediment within Wetland 3 did not
exceed USEPA or FDEP risk and hazard thresholds for recreational use by swimmers or waders.
No excess threat to human health is caused by discharging groundwater to the surface water of
Wetland 3; therefore, all alternatives are protective of human health.
Institutional controls restricting unapproved intrusive activities within the landfill boundary and
restricting use of the surficial zone of the Sand-and-Gravel Aquifer within 300 feet of the site
afford additional protection of potential human receptors under Alternatives 2, 3, and 4.
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The iron detected in Wetland 3 surface water does exceed Florida Surface Water Quality Standards
(1,000 ppb). High iron concentrations are a physical threat to fish and other biota because the
oxidation products of iron can affect inhalation and ingestion processes. Wetland 3 is currently
not a suitable fish habitat because the water is too shallow, and during dry periods of the year, it
recedes below ground level. Because no adverse effects have yet been conclusively linked to the
iron at the site, it is difficult to differentiate between the three alternatives. Assuming iron is
causing environmental impacts to the wetland, Alternative 2c would be more protective than
Alternatives 2a or 2b.
Alternative 4 would treat the groundwater contamination, thereby allowing the groundwater to
attain the COC's MCL through extraction and treatment. Alternative 4 would actively restore
groundwater and would protect human health and the environment best and most quickly.
These alternatives protect human health and the environment by restoring the aquifer and
preventing potential migration of contaminated groundwater to available receptors.
8.1.2 Compliance with ARARs
The iron detected in Wetland 3 surface water does exceed Florida Surface Water Quality Standards
(1,000 ppb). Alternative 2c would be more protective than Alternatives 2a or 2b as it provides for
the interception and treatment of the groundwater before it enters Wetland 3.
Groundwater ARARs include MCLs that establish chemical-specific limits on certain contaminants
in community water systems. Long-term monitoring is included in Alternatives 2, 3 and 4.
Additional statistical analysis of data will further substantiate the presence or absence of a
groundwater plume. This long-term monitoring will provide the data necessary for a statistical
determination of constituent concentrations in groundwater.
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For Alternatives 2 and 3, remedial action would include further sampling and analysis of
groundwater to assure that groundwater beneath the site will meet ARARs through attenuation in
a reasonable time-frame. Alternative 4 also has further sampling and analysis to assure that
groundwater will meet ARARs through treatment. Bayou Grande and NAS Pensacola wetlands
will be further evaluated during the Sites 40 and 41 RIs.
Alternatives 2, 3, and 4 would meet all federal and state standards for contaminants and proposed
actions.
8.2 Primary Balancing Criteria
8.2.1 Long-term Effectiveness and Permanence
Alternatives 2, 3, and 4 would provide long-term effectiveness and permanence.
All of the Alternative 2 subalternatives and Alternatives 3 and 4 would use institutional controls,
which would be re-evaluated after implementation of the monitoring program and again at the five-
year review. Although this alternative would require additional time to meet the performance
standards, it would likely be as effective long-term.
As stated earlier, no excess risk to human health is posed under current use scenarios by any
alternative, including the no action alternative. Alternative 2a depends on Wetland 3's capacity
to retain iron and how much of this capacity has already been used. Therefore, Alternative 2a's
permanence is difficult to predict. With harvesting of plants and removal of decayed matter,
Alternative 2b should be effective for the 30-year life of the project. Alternative 2c's long-term
effectiveness depends upon maintenance of the system for the project's 30-year life. With proper
operation, Alternative 2c should effectively remove iron from the groundwater. None of the
alternatives eliminates the iron's source, and under alternatives 2a, 2b, and 2c, conditions would
return to their present state when the systems are shut down or maintenance terminated.
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Alternative 2c provides more reliable controls than Alternatives 2a or 2b. The technology
involved in groundwater interception and removal of iron is well developed and has been used for
many years in other applications. Wetlands have been used to aid in the removal of inorganics
from water, as proposed in Alternatives 2a and 2b, but this practice is an innovative technology.
Its successful implementation often depends upon trial and error because of the many variables
involved.
Alternative 3 would use a clay cap, which would limit leachate generation, and long-term
monitoring to meet the performance standards. Although this alternative would require additional
time to meet the performance standards, it would likely be as effective long-term. Alternative 4
would use treatment technologies to reduce hazards posed by the contaminants in the OU 1
groundwater.
Alternative 3 would require long-term cover maintenance. Alternatives 2, 3 and 4 would require
monitoring after performance standards were met to ensure continued effectiveness. Five-year
reviews would be needed to verify that the cleanup remained protective for all three alternatives.
8.2.2 Reduction of Toxicity, Mobility, or Volume Through Treatment
Alternative 4 would actively remediate and treat groundwater. Alternative 3 would not treat
groundwater, but would reduce contaminants over time. Toxicity, volume, and mobility of
groundwater would be reduced through active restoration in Alternative 4. Alternatives 2a and
2b address reduction of the iron's mobility at Wetland 3 and do not significantly reduce the volume
or toxicity. With physical removal of the iron by filtration, Alternative 2c addresses toxicity,
mobility, and volume.
Therefore, Alternatives 2c and 4 would best satisfy CERCLA's statutory preference for treatment
and use of treatment to reduce toxicity, mobility, and volume of contaminants.
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8.2.3 Short-term Effectiveness
No short-term effectiveness issues are associated with Alternative 2a. The only short-term
effectiveness issues for Alternative 2b are obtaining permits, and testing and planning required
during the remedial design phase. Short-term issues associated with Alternative 2c include worker
and community safety during interception and treatment system installation. However, these are
easily controlled with proper personal protective equipment and engineering controls. The
duration of the construction activities under Alternative 2c is short, estimated to be less than
6 months.
Alternative 3 would also be effective short-term. The installation of the cap may impose risks by
disturbing the soil contamination; however, it is not expected to pose unacceptable short-term
environmental or health hazards that could not be controlled. Adverse impacts to the surrounding
environment are not anticipated during cap construction; engineering controls can be applied to
manage storm water runoff and siltation, if necessary.
Alternative 4 would also be effective short-term. Alternative 4 (groundwater treatment) would
require additional studies to determine groundwater treatment design specifications. However,
Alternative 4 would more quickly remediate groundwater contamination through extraction and
treatment. The installation of groundwater wells may impose risks by disturbing the
contamination in the soil or groundwater; however, it is not expected to pose unacceptable short-
term environmental or health hazards that could not be controlled.
8.2.4 Implementability
Alternative 2a would be the most easily implemented alternative. Alternative 2b would require
more planning, and testing during remedial design. Alternatives 2b and 2c would either require
permits for discharges or that the permit's intent be met. In addition, Alternative 2b would require
a permit for wetlands alterations.
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Alternative 3 would also be simple to implement. Materials, services, capabilities, and specialists
would be readily available for cover maintenance. Periodic maintenance of the cover would
provide reliability in the future. The groundwater monitoring program would determine the
effectiveness of contaminated groundwater attenuation.
Alternative 4 would be the most technically difficult to implement and would require treatability
studies and testing to define the design parameters for these processes.
8.2.5 Cost
Cost details are provided in the FFS and the addendum and are summarized below in Table 8-1.
Alternative 2, institutional controls/monitoring, has the lowest present worth cost and
Alternative 3, capping and monitoring, has the highest. Alternative 3 is significantly more
expensive to construct and operate because of the 85 acres requiring capping. Alternative 4 is
more expensive than Alternative 2 because of the groundwater extraction and treatment component
for the entire landfill. Alternative 2 provides for the best ratio of costs to benefit received through
the permanent reduction of risks to human health and the environment.
8.3 Modifying Criteria
8.3.1 State Acceptance
The State of Florida has concurred with the selection of Alternative 2c to remediate OU 1.
8.3.2 Community Acceptance
Based on comments expressed during the comment period, it appears that the Pensacola
community generally agreed with the selected remedy. No comments were received during the
public comment period.
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Alternative
Table 8-1
Cost Comparison for Alternatives
Direct and Indirect
Costs
Annual O&M Costs Total Net Present Worth
Alternative 1
None
None
None
Alternative 2
2a. Monitoring at
Wetland 3
2b. Enhancement of
Wetland 3
2c. Groundwater
Interception with
Treatment at Wetland 3
Alternative 3
$211,500
$816.400
$559,100
$10,728,100
$358,700
$180,000
$209,800
$140,400
$3.258.600
$4,278.500
$4,542,600
$13,450,400
Alternative 4
4a. Extraction with
Air Stripping
4b. Extraction with
Constructed
Wetlands
1,230,400
1.343,900
214,700
186,300
5,216,500
5,629.500
Notes:
Net present worth costs, where appropriate, were calculated using a 6% discount rate over 30 years.
Alt of the alternatives include cost estimates of engineering services/report preparation supplied by
Bechtel Environmental Inc.
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9.0 THE SELECTED REMEDY
Based upon consideration of the requirements of CERCLA, the NCP, the detailed analysis of
alternatives and public and state comments, the Navy has selected Alternative 2c, institutional
controls, natural attenuation, groundwater monitoring, and interception and treatment of
ground water in the Wetland 3 area as the remedial action for OU 1. At the completion of this
remedy, the risk associated with this site will be protective of human health and the environment.
The selected alternative for OU 1 is consistent with the requirements of Section 121 of CERCLA
and the NCP. The selected alternative will reduce the mobility, toxicity, and volume of
contaminated groundwater onsite. In addition, the selected alternative is protective of human
health and the environment, will attain all federal and state ARARs, is cost-effective, and uses
permanent solutions to the maximum extent practicable.
Based on the information available at this time, the selected alternative represents the best balance
among the criteria used to evaluate remedies. Alternative 2c is thought to be protective of human
health and the environment, will attain ARARs, will be cost-effective, and will use permanent
solutions and alternative treatment technologies or resource recovery technologies to the maximum
extent practicable.
9.1 Source Control
Since the Baseline Risk Assessment indicates no unacceptable risk to exposure to soil, source
control remediation will address restricting exposure to contaminated wastes and subsurface soil
at the site and intercepting groundwater before discharge to Wetland 3. Source control shall
include institutional controls to be placed in accordance with the LURA as agreed by the USEPA,
FDEP, and the Navy.
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The major components of source control to be implemented include:
• Institutional controls imposed in accordance with the LURA to restrict groundwater use
of the surficial zone of the Sand-and-Gravel Aquifer within 300 feet of the site.
• Institutional controls imposed in accordance with the LURA to limit intrusive activities
within the landfill boundary without prior approval from the NAS Pensacola
Environmental Office.
• Groundwater interception and treatment before reintroduction into Wetland 3.
9.2 Monitoring
Groundwater monitoring will be implemented at OU 1 to record contaminant movement to nearby
surface water bodies. The major components of groundwater monitoring to be implemented are:
• Placement of institutional controls to preclude usage of groundwater in the surficial zone
of the Sand-and-Gravel Aquifer within 300 feet of the site
• Implementation of a groundwater monitoring program to monitor compliance with the
performance standards listed in Table 9-1.
9.3 Compliance Testing
Groundwater and surface water will be monitored at this site in accordance with the monitoring
plan to be completed during the remedial design. After demonstration of compliance with
performance standards for two consecutive sampling events and continued attainment through the
five-year review at the designated compliance points, sampling and monitoring may be
discontinued. If sampling or monitoring indicates that the performance standards set forth in
Section 9.2 are being exceeded at any time after monitoring has been discontinued, groundwater
sampling may recommence until the performance standards are once again achieved.
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Table 9-1
Performance Standards for Groundwater
Contaminant Performance Standards
Nickel 100
Benzene 1
ChJorobenzene 100
Vinyl Chloride 1
Note:
Florida Primary Drinking Water Standard or USEPA MCL, whichever is lower.
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10.0 STATUTORY DETERMINATIONS
Under CERCLA Section 121,42 U.S.C. § 9621, the Navy must select remedies that are protective
of human health and the environment, comply with ARARs (unless a statutory waiver is justified),
are cost-effective, and use permanent solutions and alternative treatment technologies or resource
recovery technologies to the maximum extent practicable. In addition, CERCLA includes a
preference for remedies that employ treatment that permanently and significantly reduces the
volume, toxicity, or mobility of hazardous wastes as their principal element. The following
sections discuss how the selected remedy at OU 1 meets these statutory requirements.
10.1 Protection of Human Health and the Environment
The selected remedy protects human health and the environment by eliminating, reducing, and
controlling risk through institutional controls and monitoring through performance standards
described in Section 9. Contaminated groundwater will be monitored to meet the performance
standards described in Section 9. Institutional controls will prevent exposure to contaminants in
groundwater. The review will ensure that the performance standards are being met. Groundwater
interception and treatment will prohibit further contamination of the surface water in Wetland 3.
10.2 Attainment of the ARARs
Remedial actions performed under CERCLA, Section 121, 42 U.S.C. § 9621 must comply with
all ARARs. All alternatives considered for OU 1 were evaluated based on the degree to which
they complied with these requirements. The selected remedial action was found to meet or exceed
identified ARARs.
The selected remedy was found to meet or exceed ARARs identified in Tables 7-2, 7-3, and 7-4.
The following is a short narrative in support of attainment of the pertinent ARARs.
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Chemical-Specific ARARs
Groundwater restoration performance standards identified as MCLs are the groundwater protection
standards set out in this ROD as performance standards for remedial action.
Action-Specific ARARs
Performance standards are consistent with ARARs identified in Tables 7-2 and 7-3; these
regulations will be incorporated into the design and implementation of this remedy.
Location-Specific ARARs
Performance standards are consistent with ARARs identified in Table 7-1.
Waivers
Section 121 (d)(4)(C) of CERCLA, 42 U.S.C. § 9621(d)(4)(c) provides that an ARAR may be
waived when compliance with an ARAR is technically impracticable from an engineering
perspective.
Other Guidance To Be Considered
Other guidance TBCs include health-based advisories and guidance. TBCs have been used in
estimating incremental cancer risk numbers for remedial activities at the sites and in determining
RCRA applications to contaminated media. TBCs for OU 1 include Guidelines for Groundwater
Classification under the EPA Groundwater Protection Strategy, Draft Final, December 1986.
10.3 Cost-Effectiveness
The Navy believes the selected remedy, Alternative 2c, will eliminate risks to human health at an
estimated cost of $4,542,000. Alternative 2c is expected to achieve a comparable effectiveness
at a substantially lower cost than the other alternatives (although over a longer time).
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Alternative 2c provides an overall effectiveness proportionate to its costs, such that it represents
a reasonable value achieved for the investment.
10.4 Use of Permanent Solutions to the Maximum Extent Practicable
The Navy, with USEPA and FDEP concurrence, has determined that the selected remedy
represents the maximum extent to which permanent solutions and treatment technologies can be
used cost-effectively for final remediation at OU 1 at NAS Pensacola. Of those alternatives that
protect human health and the environment and comply with ARARs, the Navy, with USEPA and
FDEP concurrence, has determined that this selected remedy provides the best balance of trade-
offs in long-term effectiveness and permanence; reduction in toxicity, mobility, or volume
achieved through treatment, short-term effectiveness; implementability; and cost, while also
considering the statutory preference for treatment as a principal element and consideration of state
and community acceptance. The selected remedy provides for long-term effectiveness and
permanence; is easily implemented; reduces toxicity, mobility, or volume, and is cost-effective.
10.5 Preference for Treatment as a Principal Element
Because groundwater treatment is practicable, the statutory preference for remedies that employ
treatment as a principal element is satisfied.
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11.0 DOCUMENTATION OF NO SIGNIFICANT CHANGES
There have been no significant changes in the selected remedy. Alternative 2c, from the preferred
remedy described in the proposed plan. No comments were received during the public comment
period.
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12.0 REFERENCES
Ecology & Environment, Inc. (1991a). Data Evaluation Summaries and Proposed Samples
Location Changes, Phase I Site Groups A through E, Contamination Assessment/Remedial
Activities Investigations, Naval Air Station (NAS) Pensacola, Florida, Ecology &
Environment, Inc.: Pensacola, Florida.
Ecology & Environment, Inc. (1991b). Contamination Assessment/Remedial Activities
Investigation, Sanitary Landfill (Site 1), Naval Air Station Pensacola, Pensacola, Florida,
Interim Data Report, Ecology & Environment, Inc.: Pensacola, Florida.
Ecology & Environment, Inc. (1992). Contamination Assessment/Remedial Activities
Investigation, Naval Air Station, Pensacola, Pensacola, Florida, Data Summary and
Preliminary Scoping Report for Ecological Risk Assessment Work Plans, Ecology &
Environment, Inc.: Pensacola, Florida.
Geraghty & Miller, Inc. (1984). Verification Study, Assessment of Potential Ground-water
Pollution at Naval Air Station, Pensacola, Florida. Geraghty & Miller, Inc.:
Tampa, Florida.
Geraghty & Miller, Inc. (1986). Characterization Study, Assessment of Potential Ground-water
Pollution at Naval Air Station, Pensacola, Florida. Geraghty & Miller, Inc.:
Tampa, Florida.
Naval Energy and Environmental Support Activity. (1983). Initial Assessment Study of Naval Air
Station, Pensacola, Pensacola, Florida, NEESA 13-015, Naval Energy and Environmental
Support Activity: Port Hueneme, California.
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Southern Division Naval Facilities Engineering Command. (1996). 1977 Site Management Plan
for the Naval Air Station Pensacola, Pensacola, Florida. Southern Division Naval
Facilities Engineering Command: Charleston, South Carolina
U.S. Environmental Protection Agency. (1989). Risk Assessment Guidance for Superfund,
Volume 1, Human Health Evaluation Manual Part A, Interim Final. EPA/540/1-89/002.
December 1989.
U.S. Environmental Protection Agency. (1990). National Oil and Hazardous Substances
Pollution Contingency Plan, Final Rule. EPA/540/1-89/002. December 1989. Federal
Register V55:46 pg 8666-8865, March 8, 1990.
U.S. Environmental Protection Agency. (1990). Exposure Factors Handbook.
U.S. Environmental Protection Agency. (199 la). Risk Assessment Guidance for Superfund,
Volume /-Human Health Evaluation Manual, (Pan B, Development of Risk-based
Preliminary Remediation Goals). USEPA/OERR, USEPA/540/R92/003, December 1991
(Interim). (RAGS Part B).
U.S. Environmental Protection Agency. (1991b). Risk Assessment Guidance for Superfund,
Volume I-Human Health Evaluation Manual, Supplemental Guidance-Standard Default
Exposure Factors-Interim Final. USEPA/OERR, OSWER Directive: 9285.6-03,
March 25, 1991. (RAGS Supplement).
Q (T 0»3\PCOLA\RODlSiK I.rod.wpd
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Appendix A
Glossary
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This glossary defines terms used in this record of decision describing CERCLA activities. The
definitions apply specifically to this record of decision and may have other meanings when used
in different circumstances.
ADMINISTRATIVE RECORD: A file that contains all information used by the lead agency to
make its decision in selecting a response action under CERCLA. This file is to be available for
public review and a copy is to be established at or near the site, usually at one of the information
repositories. Also a duplicate is filed in a central location, such as a regional or state office.
AQUIFER: An underground formation of materials such as sand, soil, or gravel that can store
and supply groundwater to wells and springs. Most aquifers used in the United States are within
a thousand feet of the earth's surface.
BASELINE RISK ASSESSMENT: A study conducted as a supplement to a remedial
investigation to determine the nature and extent of contamination at a Superfund site and the risks
posed to public health and/or the environment.
CARCINOGEN: A substance that can cause cancer.
CLEANUP: Actions taken to deal with a release or threatened release of hazardous substances
that could affect public health and/or the environment. The noun "cleanup" is often used
broadly to describe various response actions or phases of remedial responses such as
Remedial Investigation/Feasibility Study.
COMMENT PERIOD: A time during which the public can review and comment on various
documents and actions taken, either by the Department of Defense installation or the USEPA. For
example, a comment period is provided when USEPA proposes to add sites to the
National Priorities List.
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COMMUNITY RELATIONS: USEPA's, and subsequently Naval Air Station Pensacola's,
program to inform and involve the public in the Superfund process and respond to community
concerns.
COMPREHENSIVE ENVIRONMENTAL RESPONSE, COMPENSATION, AND
LIABILITY ACT (CERCLA): A federal law passed in 1980 and modified in 1986 by the
Superfund Amendments and Reauthorization Act (SARA). The act created a special tax that goes
into a trust fund, commonly known as "Superfund," to investigate and clean up abandoned or
uncontrolled hazardous waste sites.
Under the program the USEPA can either:
• Pay for site cleanup when parties responsible for the contamination cannot be located or
are unwilling or unable to perform the work.
• Take legal action to force parties responsible for site contamination to clean up the site or
pay back the federal government for the cost of the cleanup.
DEFENSE ENVIRONMENTAL RESTORATION ACCOUNT (DERA): An account
established by Congress to fund Department of Defense hazardous waste site cleanups, building
demolition, and hazardous waste minimization. The account was established under the Superfund
Amendments and Reauthorization Act.
DRINKING WATER STANDARDS: Standards for quality of drinking water that are set by both
the USEPA and the FDEP.
EXPLANATION OF DIFFERENCES: After adoption of final remedial action plan, if any
remedial or enforcement action is taken, or if any settlement or consent decree is entered into, and
if the settlement or decree differs significantly from the final plan, the lead agency is required to
publish an explanation of any significant differences and why they were made.
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FEASIBILITY STUDY: See Remedial Investigation/Feasibility Study.
GROUND WATER: Water beneath the earth's surface that fills pores between materials such as
sand, soil or gravel. In aquifers, groundwater occurs in sufficient quantities that it can be used
for drinking water, irrigation, and other purposes.
HAZARD RANKING SYSTEM (MRS): A scoring system used to evaluate relative risks to
public health and the environment from releases or threatened releases of hazardous substances.
USEPA and states use the HRS to calculate a site score, from 0 to 100, based on the actual or
potential release of hazardous substances from a site through air, surface water, or groundwater
to affect people. This score is the primary factor used to decide if a hazardous site should be
placed on the NPL.
HAZARDOUS SUBSTANCES: Any material that poses a threat to public health and/or the
environment. Typical hazardous substances are materials that are toxic, corrosive, ignitable,
explosive, or chemically reactive.
INFORMATION REPOSITORY: A file containing information, technical reports, and
reference documents regarding a Superfund site. Information repositories for Naval Air Station
Pensacola are at The John C. Pace Library at the University of West Florida and the
NAS Pensacola Library in Building 633 on the Naval Air Station, Pensacola, Florida.
MAXIMUM CONTAMINANT LEVEL: National standards for acceptable concentrations of
contaminants in drinking water. These standards are legally enforceable standards set by the
USEPA under the Safe Drinking Water Act.
MONITORING WELLS: Wells drilled at specific locations on or off a hazardous waste site
where groundwater can be sampled at selected depths and studied to assess the groundwater flow
direction and the types and amounts of contaminants present, etc.
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NATIONAL PRIORITIES LIST (NPL): The USEPA's list of the most serious uncontrolled or
abandoned hazardous waste sites identified for possible long-term remedial response using money
from the trust fund. The list is based primarily on the score a site receives on the Hazard Ranking
System. USEPA is required to update the NPL at least once a year.
PARTS PER BILLION (ppb)TPARTS PER MILLION (ppm): Units commonly used to express
low concentrations of contaminants. For example, 1 ounce of trichloroethylene in a million
ounces of water is 1 ppm; 1 ounce of trichloroethylene in a billion ounces of water is 1 ppb. If
one drop of trichloroethylene is mixed in a competition-size swimming pool, the water will contain
about 1 ppb of trichloroethylene.
PRELIMINARY REMEDIATION GOALS: Screening concentrations that are provided by the
USEPA and the FDEP and are used in the assessment of the site for comparative purposes before
remedial goals being set during the baseline risk assessment.
PROPOSED PLAN: A public participation requirement of SARA in which the lead agency
summarizes for the public the preferred cleanup strategy, and the rationale for the preference,
reviews the alternatives presented in the detailed analysis of the remedial investigation/feasibility
study, and presents any waivers to cleanup standards of Section 121(d)(4) that may be proposed.
This may be prepared either as a fact sheet or as a separate document. In either case, it must
actively solicit public review and comment on all alternatives under agency consideration.
RECORD OF DECISION (ROD): A public document that explains which cleanup alternative(s)
will be used at NPL sites. The Record of Decision is based on information and technical analysis
generated during the remedial investigation/feasibility study and consideration of public comments
and community concerns.
REMEDIAL ACTION (RA): The actual construction or implementation phase that follows the
remedial design and the selected cleanup alternative at a site on the NPL.
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REMEDIAL INVESTIGATION/FEASIBILITY STUDY (RI/FS): Investigation and analytical
studies usually performed at the same time in an interactive process, and together referred to as
the "RI/FS." They are intended to: (1) gather the data necessary to determine the type and extent
of contamination at a Superfund site; (2) establish criteria for cleaning up the site; (3) identify and
screen cleanup alternatives for remedial action; and (4) analyze in detail the technology, and costs
of the alternatives.
REMEDIAL RESPONSE: A long-term action that stops or substantially reduces a release or
threatened release of hazardous substances that is serious, but does not pose an immediate threat
to public health and/or the environment.
REMOVAL ACTION: An immediate action performed quickly to address a release or threatened
release of hazardous substances.
RESOURCE CONSERVATION AND RECOVERY ACT (RCRA): A federal law that
established a regulatory system to track hazardous substances from the time of generation to
disposal. The law requires safe and secure procedures to be used in treating, transporting, storing,
and disposing of hazardous substances. RCRA is designed to prevent new, uncontrolled hazardous
waste sites.
RESPONSE ACTION: As defined by Section 101(25) of CERCLA, means remove, removal,
remedy, or remedial action, including enforcement activities related thereto.
RESPONSIVENESS SUMMARY: A summary of oral and written public comments received
by the lead agency during a comment period on key documents, and the response to these
comments prepared by the lead agency. The responsiveness summary is a key part of the ROD,
highlighting community concerns for USEPA decision-makers.
SECONDARY DRINKING WATER STANDARDS: Secondary drinking water regulations are
set by the USEPA and the FDEP. These guidelines are not designed to protect public health,
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instead they are intended to protect "public welfare" by providing guidelines regarding the taste,
odor, color, and other aesthetic aspects of drinking water which do no present a health risk.
SUPERFUND: The trust fund established by CERCLA which can be drawn upon to plan and
conduct clean ups of past hazardous waste disposal sites, and current releases or threats of releases
of nonpetroleum products. Superfund is often divided into removal, remedial, and enforcement
components.
SUPERFUND AMENDMENTS AND REAUTHORIZATION ACT (SARA): The public law
enacted on October 17, 1986, to reauthorize the funding provisions, and to amend the authorities
and requirements of CERCLA and associated laws. Section 120 of SARA requires that all federal
facilities "be subject to and comply with, this act in the same manner and to the same extent as any
non-governmental entity."
SURFACE WATER: Bodies of water that are aboveground, such as rivers, lakes, and streams.
VOLATILE ORGANIC COMPOUND: An organic (carbon-containing) compound that
evaporates (volatizes) readily at room temperature.
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Appendix B
Responsiveness Summary
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RESPONSIVENESS SUMMARY
Overview
During the public comment period, the U.S. Navy proposed a preferred remedy to address
ground water contamination at OU 1 on NAS Pensacola. This preferred remedy was selected in
coordination with the USEPA and the FDEP. The NAS Pensacola Restoration Advisory Board,
a group of community volunteers, reviewed the technical details of the selected remedy. The
sections below describe the background of community involvement on the project and comments
received during the public comment period.
Background of Community Involvement
Throughout the site's history, the community has been kept abreast of site activities through press
releases to the local newspaper and television stations that reported on site activities. Site related
documents were made available to the public in the administrative record at information
repositories maintained at the NAS Pensacola Library and The John C. Pace Library of the
University of West Florida.
On December 4, 1997, newspaper announcements were placed to announce the public comment
period (December 8, 1997, through January 22, 1998) and included a short description of the
proposed plan. The announcement appeared in the Pensacola News Journal. In conjunction with
the newspaper announcement, copies of the proposed plan were mailed to addresses on the
Installation Restoration Program mailing list. The opportunity for a public meeting was provided.
Summary of Comments Received During the Public Comment Period
No comments were received during the public comment period.
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