PB95-964025
EPA/ROD/R04-95/238
January 1996
EPA Superfund
Record of Decision:
Pensacola Naval Air Station,
Site 39, Pensacola, FL
7/31/1995
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Table of Contents
DECLARATION OF THE RECORD OF DECISION vi
1.0 INTRODUCTION 1
2.0 SITE LOCATION AND DESCRIPTION 2
3.0 SITE HISTORY AND ENFORCEMENT ACTIVITIES 7
4.0 HIGHLIGHTS OF COMMUNITY PARTICIPATION 15
5.0 SCOPE AND ROLE OF THE OPERABLE UNIT 16
6.0 SITE CHARACTERISTICS 16
7.0 SUMMARY OF SITE RISKS 25
7.1 Chemicals of Concern 25
7.2 Exposure Assessment 26
7.3 Toxicity Assessment 30
7.4 Risk Characterization 31
7.5 Risk Uncertainty 33
7.6 Ecological Risk Assessment 39
8.0 DOCUMENTATION OF NO SIGNIFICANT CHANGES 39
List of Figures
Figure 2-1 Location Map 3
Figure 2-2 Site Map 5
Figure 2-3 Habitat Communities arid Surface Features 9
Figure 3-1 Area of Stained Soil and Excavation Extent 13
Figure 6-1 Geologic Cross Sections A-A', B-B', and Map Locations 19
Figure 6-2 Groundwater Flow of the Upper Surficial Zone 21
Figure 6-3 Groundwater Flow of the Lower Surficial Zone 23
List of Tables
Table 7-1 Exposure Pathways Summary 27
Table 7-2 Statistical Analysis of COPCs in Shallow and Intermediate Groundwater . 29
Table 7-3 Parameters Used to Estimate Potential Exposures for Future Land Use
Receptors 29
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Table 7-4 Chronic Daily Intakes for Potential Future Residents — Ingestion of
Shallow and Intermediate Groundwater 30
Table 7-5 Toxicological Database Information for NAS Pensacola, Site 39 32
Table 7-6 Hazard Quotients and Incremental Lifetime Cancer Risks-Potential
Future Residents Ingestion of Shallow and Intermediate Groundwater ... 33
List of Appendices
Appendix A Responsiveness Summary
Appendix B Glossary
Appendix C Florida Professional Geologist Seal
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List of Abbreviations
ARAR Applicable or Relevant and Appropriate Requirements
bis Below Land Surface
BRA Baseline Risk Assessment
CERCLA Comprehensive Environmental Response, Compensation and Liability Act
COPC Chemical of Potential Concern
E/A&H EnSafe/Allen & Hoshall
FDEP Florida Department of Environmental Protection
FFA Federal Facilities Agreement
FS Feasibility Study
mg/L Milligrams Per Liter
MSL Mean Sea Level
NAS Naval Air Station
NPL National Priorities List
PCB Polychorinated Biphenyl
PRAP Proposed Remedial Action Plan
PRG Preliminary Remediation Goal
PWC Public Works Center
RA Risk Assessment
RCRA Resource Conservation and Recovery Act
RI . Remedial Investigation
ROD Record of Decision
SARA Superfund Amendments and Reauthorization Act of 1986
SVOC Semivolatile Organic Compound
TAL/TCL Target Analyte List and Target Compound List
USEPA U.S. Environmental Protection Agency
VOC Volatile Organic Compounds
/tg/L Micrograms per Liter
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IV
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DECLARATION OF THE RECORD OF DECISION
She Name and Location
Site 39, Oak Grove Campground
Naval Air Station Pensacola
Pensacola, Florida
Statement of Purpose
This decision document presents the selected remedial action that the U.S. Navy, as the lead
agency in charge of the site, has selected for addressing potential groundwater and soil
contamination at Site 39 — Oak Grove Campground. The decision was chosen in accordance
with Comprehensive Environmental Response, Compensation, and Liability Act, as amended by
Superfund Amendments and Reauthorization Act of 1986 and, to the extent practicable, the
National Oil and Hazardous Substances Pollution Contingency Plan. This decision is based on
the Administrative Record for Site 39.
The United States Environmental Protection Agency and. the Florida Department of
Environmental Protection concur with the selected remedy.
Description of the Selected Remedy
The remedial investigation and the risk assessment conducted for Site 39 support a no action
remedial alternative. The RI and RAs addressed all media at the site, and therefore, no other
actions will be considered for She 39.
Declaration Statement
The selected remedy protects 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. Because treatment of the principal threats onsite was not found to be
practicable or within the scope of this action, this remedy does not satisfy the statutory
preference for treatment as a principal element. Because the remedial action selected will result
in hazardous substances, pollutants or contaminants remaining at the site above levels that allow
for unlimited use and unrestricted exposure, the five year review after initiation of the selected
remedial action will be necessary.
Signature (Commanding Officer, NAS Pensacola) Date
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VI
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Record of Decision
NAS Pensacola Site 39
July 1995
1.0 INTRODUCTION
In December 1989, Naval Air Station (NAS) Pensacola was placed on the U.S. Environmental
Protection Agency's (USEPA) National Priorities List (NPL) based on a numerical ranking of
42.4 (out of 100) of the potential hazards it poses to human health and the environment.
Although sites added to the NPL are generally called "Superfund sites," Department of Defense
sites like NAS Pensacola are cleaned up using Defense Environmental Restoration Account
funds.
The Navy is the lead agency responsible for cleanup at NAS Pensacola. The USEPA and the
Florida Department of Environmental Protection (FDEP) are the respective federal and state
regulatory agencies charged with overseeing the cleanup. Together they work with the Navy
through the Federal Facilities Agreement (FFA), an interagency agreement that defines the roles
and responsibilities for each agency. The FFA, signed in October 1990, outlines the regulatory
path that will be followed at the air station. NAS Pensacola must complete not only the
regulatory obligations associated with its NPL listing, but also it must satisfy the ongoing
requirements of an environmental permit issued in 1988. 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. The
Resource Conservation and Recovery Act (RCRA) governs ongoing use of hazardous materials,
and the rules of the operating permit; RCRA and Comprehensive Environmental Response,
Compensation, and Liability Act (CERCLA) investigations and actions are coordinated through
the FFA, streamlining the cleanup process.
Site 39 — Oak Grove Campground, at NAS Pensacola, has been the subject of a remedial
investigation (RI). The feasibility study (FS), which normally develops and examines remedial
action alternatives for a site, was not completed because a previous removal action reduced risks
to human health and the environment so that no further action is necessary. This Record of
Decision (ROD) has been prepared to present the Navy's selected remedial alternative for
Site 39. Section 121(d)(2)(A) of CERCLA incorporates into law the CERCLA Compliance
Policy which specifies that remedial actions meet any Federal or State standards, requirements,
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Record of Decision
NAS Pensacola Site 39
July 1995
criteria, or limitations that are determined to be legally applicable or relevant and appropriate
requirements (ARARs). Because the remedial action selected will result in hazardous
substances, pollutants or contaminants remaining at the site above levels that allow for unlimited
use and unrestricted exposure, the five year review after initiation of the selected remedial action
will be necessary.
2.0 SITE LOCATION AND DESCRIPTION
This ROD describes the alternative that the U.S. Navy has selected to address groundwater and
soil contamination at Site 39 — Oak Grove Campground, NAS Pensacola, Florida.
Site 39 is a circular area approximately 300 feet in diameter littered with broken brick, concrete,
tile, glass, coal, and nails. Within this area, a zone of darkly stained soil and stressed vegetation
measured, approximately 60 feet x 80 feet. A 130-foot x 200-foot area of lighter staining and
less-distressed vegetation surrounded the darkly stained area.
The site is in the southwestern portion of NAS Pensacola, approximately 2,500 feet south of
Forrest Sherman Field and 520 feet northwest of the Pensacola Bay Shoreline, as shown on
Figure 2-1. The sandy soil is covered by some grass and brush growth, surrounded by trees.
As shown in Figure 2-2, Site 39 is approximately 200 feet south of the Oak Grove trailer
campground.
Little is known about Site 39's history. No records indicating the source of the debris and
stained soil have been identified. A boiler-powered sawmill was reported in the vicinity of
Site 39; however, this has not been confirmed. During the RI, little additional historical
information was obtained. Mr. Ron Joyner from Facilities Management Division at
NAS Pensacola stated there had not been a sawmill at Site 39. Rather, he said, the she was a
disposal area for hardflll debris that resulted from the demolition of Building 29. Mr. Joyner
hypothesized that the stained area may have been caused by campers dumping used motor oil
onto the ground.
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LEGEND
x - FENCE
i i i i i i i - RAILROAD
_, _ SHORE LINE
2,500
ess
SCALE
2.500
=
FEET
RECORD
OF DECISION
NAS PENSACOLA
SITE 39
FIGURE 2-1
LOCATION MAP
DWG DATE: 03/15/95 JDWG NAME:83RDLM
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Record-of Decision
NAS Peruacota Site 39
Juty 1995
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\ \
\\ TENT j
\ \ CAMPING
\ x AREA
/
SPARSE PINE
TREES
-TRAIL TO
BEACH
SITE AREA
SPARSE PINE
TREES
LEGEND
SOIL BORING
SOIL BORING AND SHALLOW MONITORING WELL .
INTERMEDIATE WELL
UNPAVED ROAD
BUILDING
AREA OF SCATTERED DEBRIS & LIGHT VEGETATION
AREA OF STAINED SOILS
SOURCE E4E 1991
0
SCALE
100
200
JS
FEET
RECORD OF
DECISION
NAS PENSACOLA
SITE 39
FIGURE 2-2
SITE MAP
DATE: 03/1 4/95
| DWG NAME: 83RDSM
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Record of Decision
NAS Pensacola Site 39
July 1995
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Record of Decision
NAS Pensacola Site 99
July 1995
Mr. James Tucker, caretaker for the Lighthouse Point Oak Grove Rental, said railroad ties were
once stockpiled at the site but could provide no information regarding dates or location.The site
center is about 6 feet above mean sea level (msl), approximately 520 feet inland (north) of the
Intercoastal Waterway (Pensacola Bay) shoreline. The terrain gently slopes downgradient in a
south/southeasterly direction. Surface runoff does not flow from the site to the shoreline but
infiltrates into the subsurface rapidly through the sandy surface soil. Interdunal depressions
immediately downgradient of the site retain water after heavy rains and conduct it vertically into
the soil. The terrain begins to flatten southeast of the site. Habitat communities and surface
features are shown in Figure 2-3.
To the north, a narrow band of woods separates the site from the campground. Sherman's Inlet
is approximately 500 feet southwest of the site center. The east end of Sherman's Inlet contains
wetlands 56A/B, as identified by Parsons and Pruitt (1991). A 200-foot-wide band of woods
west of the site separates it from Wetland 56A.
On the basis of the groundwater elevations measured onsite, the flow direction of the surficial
zone (both shallow and intermediate depths) generally mimics the topography, flowing
south-southeast toward Pensacola Bay. Piezometric maps indicate the water table lies between
3 and 7 feet below land surface (bis) and ranges in elevation from 3.9 to 2.9 feet above msl.
3.0 SITE HISTORY AND ENFORCEMENT ACTIVITIES
In the spring of 1990, campers reported stained soil with a hydrocarbon odor south of the
campground. NAS Facilities Management personnel collected two grab samples from a depth
of 0 to 7 inches bis from the stained soil area at Site 39. Analysis of these samples indicated
petroleum contamination
Site 39 was officially designated a "Remedial Investigation" site upon signature of the FFA in
October 1990. Between December 1992 and November 1994, EnSafe/Allen & Hoshall performed
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Record of Decision
NAS Pensacola Site 39
Juty 1995
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\\ TENT
\ \ CAMPING
AREA
/ CAMPING //
AREA //
Xx^boDS
SPARSE PINE
TREES
TO SHERMAN'S
INLET
SPARSE
TREES
WETLAND
56A
WOODS/
SHRUBS
INTERDURAL
SWALE
HIGH GROUND
ABOUT 4ft MSL
SCRUB/SHRUB
AREA
INTERDURAL
SWALE
^POTENTIALLY
UNCLASSIFIED
WETLAND AREA
SPARSE PINE
TREES
LOW-LYING
AREA
WETLAND
56B
POPULATIONS OF
CHRYSOPSIS
GODFREY!!
SHORg FRONT
TRAIL TO
BEACH
SPARSE
WOODS
SCRUB/SHRUB
AREA
• INTERCOASTAL WATERWAY
FEET
LEGEND
UNPAVED ROAD
STATE IMPERILED SPECIES FOR FLORIDA
AREA OF SCATTERED DEBRIS It LIGHT VEGETATION
AREA OF STAINED SOILS
SOURCE EftE 1991
RECORD OF
DECISION
SITE 39
MAS PENSACOLA
FIGURE 2-3
HABITAT COMMUNITIES
& SURFACE FEATURES
DATE: 03/14/95
I DWG NAME: 83RDHCSF
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Retard-of Decision
NAS Pensacola Site 39
July 1995
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Record of Decision
NAS Pensacola Site 39
July 1995
an RI at Site 39 on behalf of the U.S. Navy. The RI involved sampling soil and groundwater
to characterize the nature and extent of contamination onsite. The findings included:
SoU
• The stained soil was limited vertically to the uppermost foot over most of the site with
pockets approximately 3 feet deep. Low to moderate concentrations of semivolatile
compounds (SVOCs) were identified within the stained area, specifically pyrene at
1.9 milligrams per kilogram (mg/kg), which is commonly found in wood preservatives
and waste oil. Low concentrations of volatile organic compounds (VOCs) were found
within the stained area, specifically trichloroethane and toluene at total concentrations of
less than 2 micrograms per kilograms (/tg/kg). Specific metal compounds identified at
the site above the preliminary remediation goals (PRGs) and NAS Pensacola reference
concentrations include aluminum, arsenic, calcium, iron, magnesium, and sodium. All
metals detected were within the range typical of the reference concentrations at
NAS Pensacola.
Hydrogeology
• Groundwater flows south and southeast, respectively, in the upper and lower portions of
the uppermost zone ("surficial zone") of the aquifer. Underlying this uppermost zone
is the "low-permeability zone", consisting of clays and silt, which separates the upper
water-bearing zone from the "main producing zone" (regional potable water source).
Although the entire thickness of the low permeability zone was not investigated at this
site, previous investigations conducted at NAS Pensacola have shown the
low-permeability zone ranges from 12 to 17 feet thick, and is characterized by low
hydraulic conductivities. Hence, potential for flow between the aquifer zones is minimal.
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Record- of Decision
NAS Pensacola Site 39
July 1995
Groundwater
• On the basis of the groundwater analytical results, Site 39 soil is not impacting the
groundwater with appreciable amounts of organic compounds and no petroleum-based
parameters were detected. The VOCs tetrachloroethene and 1,1-dichloroethane (first
round of sampling) and tetrachloroethene (second round of sampling) were the only
organic compounds present in groundwater. These VOCs were detected only in the top
of the uppermost aquifer zone; all detected concentrations were below drinking water
standards.
Due to the high turbidity of the groundwater during the initial sampling, the metals data
were considered unreliable and a second round of groundwater sampling was undertaken
using a low-flow purging and sampling technique. This method reduced turbidity and
consequent metals concentrations significantly. Inorganic compounds exceeding
secondary drinking water standard concentrations were aluminum and iron. In addition,
arsenic, barium, calcium, lead, magnesium, and vanadium exceeded their respective
NAS Pensacola reference, or background concentrations. In the bottom of the uppermost
aquifer, only iron exceeded a secondary drinking water standard. Arsenic and aluminum
are potentially related to the marine environment or suspended sediment in samples and
are likely not site-related: Arsenic is within the natural range for Escambia County. In
addition calcium, iron, magnesium, and sodium are essential nutrients and are only toxic
at extremely high concentrations.
It was determined that the most cost-effective, environmentally and aesthetically beneficial
remedy was to remove and properly dispose of the contaminated upper 12 inches of soil and
replace it with clean fill material.
Between July 25 and July 29, 1994, NAS Pensacola's Public Works Center (PWC)
Environmental Department removed 864 tons of stained soil from Site 39. Figure 3-1 shows
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39CS01 $ - SHAUOT
39OOe-^- - MTEMEBIATE MOMIOKMC WQL
VV-y - TREES
~ EA OF SIAMED SCO.
\ /
- APmegOHOE ARE* MTM SCMIERED
OGBMS AND USMI VEBEVaiON
- MEA OF EXDMOION
OURWC REMO¥M. ACnON
30
SCALE
30
FEET
RECORD OF
DECISION
SITE 39
NAS PENSACOLA
FIGURE 3-1
AREA OF STAINED SOIL &
EXCAVATION EXTENT
DWG DATE: 03/14/95 I DWG NAME: 83RDSSEE
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NAS Pauacola Site 39
July 1995
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14
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Record of Decision
NAS Pensacola Site 39
Jufy 1995
the area of stained soil and the extent of the excavation during the removal action.
Approximately 1 foot of soil was removed on the south side of the site and the excavation
gradually deepened to 3 feet on the north side. The soil was tested by PWC's Laboratory and
determined to be a nonhazardous waste. The removed soil was disposed at the Escambia County
Solid Waste Department's Perdido Landfill, 13009 Beulah Road, Cantonment, Florida. Backfill
material was obtained from the backfill stockpile. It was analyzed for full Target Analyte
List/Target Compound List (TAL/TCL) parameters. The analysis of this soil did not identify
any contaminants above the PRGs.
Before backfilling Site 39 four post-removal confirmation samples were taken from the soil. No
VOCs were detected in any of these samples. Only one SVOC detected exceeded a PRG.
Benzo(a)pyrene slightly exceeded the PRGs in two post-removal samples. The site showed an
improvement from pre-removal conditions. After the removal action no pesticide detected
exceeded the PRGs. No PCBs were detected in the samples after the removal action. The only
inorganic constituent to exceed PRGs in the post-removal samples was arsenic. Arsenic
exceeded PRGs in one sampling location, however its concentration is within the range typical
of NAS Pensacola. As discussed in the previous section the entire site was backfilled with 1 to
3 feet of "clean" material after the post-removal confirmation sampling
4.0 HIGHLIGHTS OF COMMUNITY PARTICIPATION
Throughout the site's history, the community has been kept abreast of site activities in
accordance with CERCLA sections 113(k)(2)(B)(i-v) and 117. During the removal action the
local newspaper and television stations covered the removal by visiting the site and speaking
with a Navy spokesman. Site related documents were made available to the public in the
administrative record at information repositories maintained at the NAS Pensacola Library, the
West Florida Regional Library, and the John C. Pace Library of the University of West Florida.
Also, all addresses on the Site 39 mailing list were sent a public meeting notice and a summary
of the PRAP. The notice of availability of the PRAP and RI document was published hi the
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Record-of Decision
NAS Pensacola Site 39
Juty 1995
" Pensacola News Journal" on May 18, 1995. A public comment period was held from May 30
to June 30, 1995 to encourage public participation in the remedy selection process. In addition,
a public meeting was held on June 13, 1995, to respond to questions and to accept public
comments on the PRAP for Site 39. The public meeting minutes have been transcribed and a
copy of the transcript is available to the public at the aforementioned repositories. A
Responsiveness Summary, included as a part of this ROD in Appendix A, has been prepared to
respond to the comments, criticisms, and new information received during the comment period.
5.0 SCOPE AND ROLE OF THE OPERABLE UNIT
The proposed remedial action identified in this document is the "No Action Alternative." This
decision is the only remedial action identified for She 39. The previously cited removal action
has removed all heavily contaminated soil from the site. Therefore, no further action is
proposed for Site 39 because it has been determined not to be a threat to human health and the
environment.
Note that Site 39 is one of 37 sites at NAS Pensacola being investigated in accordance with
CERCLA. Separate investigations and assessments are being conducted for these other sites.
Therefore, this ROD applies only to She 39.
6.0 SITE CHARACTERISTICS
The site characteristics related to Site 39 are summarized below. Site characteristics include
land use, meteorology, surface features, hydrology, geology, hydrogeology, and ecology.
No construction of any kind is within the boundaries of Site 39. Oak Grove Campground, a
recreational facility, is approximately 200 feet north of Site 39. The campground is the
temporary residence for up to 336 people.
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Record of Decision
NAS Pensacola Site 39
Jufy 1995
NAS Pensacola has a mild, subtropical climate, with average annual temperature ranging from
55 °F in the winter to 81 °F in the summer. Rainfall averages approximately 60 inches per year,
with the highest amounts in July and August when thunderstorms occur almost daily. Rainfall
is lowest during spring and fall (4 inches average per month).
Winds, which prevail from the north during the winter and the south during the summer, are
generally moderate in velocity except during storms. A difference in the ocean-land temperature
produces the sea-breeze effect, a daily clockwise rotation in the direction of the surface wind
near the coast.
The topography of Site 39 is predominantly flat with the center at about 6 feet msl. From the
site's center, the terrain gently slopes downgradient to the south/southeast toward the shore of
Pensacola Bay. The terrain begins to flatten southeast of the site.
Sandy soil typifies the NAS Pensacola area. Consequently, most rainfall directly infiltrates the
subsurface, resulting in few natural streams. At Site 39, surface runoff does not flow from the
site to the shoreline. Interdunal depressions retain water after heavy rains and conduct it
vertically into the soil (see Figure 2-3).
Specifically, the site is underlain by poorly graded fine- to medium-grain quartz sand from the
surface to approximately 43 to 45 feet bis. Drill cuttings from the intermediate depth borings
indicated a dark brown, apparently organic-rich pore water within the sands at approximately
25 feet bis. The base of the surficial zone is underlain by a low-permeability zone consisting
of either a soft blue/gray clay or a green silty clay at 43 to 45 feet bis which was encountered
at all borings advanced to the appropriate depth. The extremely low hydraulic conductivity
characteristic of clay layer and its apparent laterally continuous nature beneath the site indicates
the potential for groundwater movement from the surficial zone, through the clay, and into the
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Retard, of Decision
NAS Pensacola Site 39
Juty 1995
underlying main producing zone to be extremely low. The geologic cross sections constructed
using data collected at Site 39 are shown in Figure 6-1.
The flow direction of groundwater (both upper and lower surficial zone depths) generally
appears to mimic the topography, flowing south-southeast toward Pensacola Bay. The water
table lies between 3 and 7 feet bis and ranges in elevation from 3.9 to 2.9 feet above msl. At
Site 39, there is an upward potential component of flow that exists between the lower and upper
surficial zones. The groundwater flow in the upper and lower surficial zones is illustrated in
Figures 6-2 and 6-3, respectively.
Generally, the area in and around Site 39 is classified as a long-leaf/slash pine community,
typical to coastal northwest Florida. Fauna! species associated with this back-dune habitat are
predominantly small mammals, amphibians, and reptiles. In addition, shorebirds are expected
to use this area intermittently.
Vegetation in the immediate site area is limited. It is impossible to ascertain whether this is a
result of natural effects, man-induced clearing, or contaminant-driven effects. The east end of
Sherman's Inlet contains wetlands 56A/B. Wetland 56A, a palustrine emergent wetland at the
northeast end of Sherman's Inlet, about 200 feet due west of the site, is dominated by a dense
thicket of sawgrass (Cladiumjamaicense). The shoreline surrounding this wetland contains slash
pines, yaupon, inkberry, wax myrtle, red maple (Acer rubrum), and sweet bay magnolia
(Magnolia virginiana). Wetland 56B, a large estuarine emergent wetland at the southeast end
of Sherman's Inlet, is approximately 500 feet southwest of the site center. It is dominated by
black needle rush (Juncus roemerianus), and the surrounding shoreline contains slash pines and
yaupon. Two populations of Godfrey's golden aster (Chrysopsis godfreyii) live southeast of the
site. Chrysopsis godfreyii is listed by the Florida Natural Areas inventory as a state imperiled
species. This is only threatened or endangered species identified near the site.
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A
NORTH
+ 10
(MSL)O -
E -10 '
o -20 -
I
"• -30 -
-40 -
B
WEST
+ 10 -
(MSL)O-
E -10 -
N^
§ -20 -
uj -30 -
-40 -
A-A' CROSS SECTION
39GI05
39GS01
PLAN VIEW
39S06
B-B CROSS SECTION
39S05
T.
39GS02 39GI06
B
EAST
39GS03 39GI07
39S05
FINE GRAINED POORLY GRADED Qtl SAND
GREYISH BLUE SANDY CLAY OR
GREEN SIL1Y CLAY
AREA CONTAINING STAINED SOIL
GROUNDWATER ELEVATION ON OS/14/93
39GSOtc SHALLOW MONITORING WELL
LOCATION/IDENTIFICATION
A INTERMEDIATE MONITORING WELL
390106 LOCATION/IDENTIFICATION
a SOIL BORING
39SOS LOCATION/IDENTIFICATION
TREES
30 0 30
GRAPHIC SCALE IN FEET
HORIZONTAL SCALE: 1"=30'
VERTICAL SCALE: 1" = 16'
RECORD OF
DECISION
SITE 39
NAS PENSACOLA
FIGURE 6-1
GEOLOGIC CROSS SECTIONS A-A1,
B-B1 AND MAP LOCATIONS
DWG DATE: 03/14/95
I DWG NAME: 83RDGCSM
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Record- of Decision
NAS Pensacola Site 39
Jufy 1995
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- 20 -
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39GS01
30
GRAPHIC SCALE IN FEET
-3.50
LEGEND
MONITORING WELL LOCATION/IDENTIFICATION
GW ELEVATION AT HIGH TIDE
GROUNDWATER FLOW DIRECTION
TREES
LINE OF EQUAL GROUNDWATER ELEVATION
RECORD OF
DECISION ..
SITE 39
NAS PENSACOLA
FIGURE 6-2
GROUNDWATER FLOW OF THE
UPPER SURF1CIAL ZONE
DWG DATE: 03/27/95 | DWG NAME: 83RDGFUZ
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NAS Paaacola Site 39
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30
30
GRAPHIC SCALE IN FEET
39GI05
4.98' 4-
.4.70'
LEGEND
39GI07^. INTERMEDIATE MONITORING WELL
3.98' LOCATION/IDENTIFICATION
GW ELEVATION AT LOW TIDE
-3.50
GROUNDWATER FLOW DIRECTION
TREES
LINE OF EQUAL GROUNDWATER ELEVATION
RECORD OF
DECISION
SITE 39
NAS PENSACOLA
FIGURE 6-3
GROUNDWATER FLOW OF THE
LOWER SURFICIAL ZONE
DWG DATE: 03/27/95 ] DWG NAME: 83RDGFLZ
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NAS Pauacola Site 39
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Record of Decision
NAS Pensacola Site 39
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7.0 SUMMARY OF SITE RISKS
During the RI, a baseline human health risk assessment (RA) and a baseline ecological RA
(collectively, the BRAs) were conducted to evaluate the actual or potential risks to human health
or the environment resulting from the no action scenario at Site 39. It is incorporated into
Chapter 10 of the RI report. The baseline RA represents an evaluation of the no further action
alternative, in that it identified the risk present if no remedial action is taken. The assessment
considers environmental media and exposure pathways that could result in unacceptable level of
exposure now or in the foreseeable future. Data collected and analyzed during the RI provided
the basis for the risk evaluation. The components of the baseline RA include: identification of
chemicals of concern; the exposure assessment; the toxicity assessment; risk characterization;
and risk uncertainty analysis.
7.1 Chemicals of Concern
The objective of chemical identification is to screen the information that is available on
hazardous substances present at the site and to identify potential chemicals of concern (COPCs)
in order to focus subsequent efforts in the risk assessment process. COPCs are those chemicals
selected in consideration of their comparison to screening concentrations (risk-based and
reference), intrinsic lexicological properties, persistence, fate and transport characteristics, and
cross-media transfer potential. Any COPC that is carried through the risk assessment process
and found to contribute to a pathway that exceeds a 10"6 risk or hazard index (HI) greater than 1
for any of the exposure scenarios evaluated in the risk assessment and has an incremental
lifetime cancer risk (ILCR) greater than 10* or hazard quotient (HQ) greater than 0.1 is referred
to as a chemical of concern (COC). Site 39 surface soil has been removed and replaced with
clean fill material. Therefore, soil exposure pathways were excluded from the BRA. During
the risk assessment for Site 39, the following chemicals were identified as COPCs in the
groundwater: aluminum, arsenic, and tetrachloroethene. The state of Florida does not consider
arsenic a COC at this site because arsenic concentrations did not exceed a Florida Primary
Drinking Water standard.
25
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Record of Decision
NAS Pensacola Site 39
July 1995
7.2 Exposure Assessment
An exposure assessment was conducted to estimate the magnitude of exposure to the
contaminants of concern at the site and the pathways through which these exposures could occur.
Since clean backfill material comprises the 0- to 1-foot soil depth interval, the potential
risk/hazard posed by the soil pathways has not been assessed. Potential risk/hazard posed by
groundwater pathways has been assessed assuming a future residential exposure scenario. This
approach was selected to provide a conservative but reasonable evaluation of potential future risk
within Site 39. The potential pathways of exposure to COPCs identified in the shallow and
intermediate groundwater are listed in Table 7-1. Details regarding the rationale for exposure
pathway selection/rejection for both the soil and groundwater media are also provided in
Table 7-1. -
After exposure pathways were developed, the concentrations at the exposure points were
calculated. USEPA Region IV guidance calls for assuming lognormal distributions for
environmental data and the calculation of 95 percent of the UCL mean for use hi exposure
quantification. Exposure point concentrations for soil and groundwater at Site 39 are listed in
Table 7-2.
Once exposure point concentrations were developed, the chemical intake at each exposure point
was calculated. Assumptions made in quantifying chemical intake are listed hi Table 7-3.
Age-adjusted ingestion and contact factors were derived for the potential future residential
receptors (resident adult and resident child combined) for carcinogenic endpoints. These factors
consider the difference in daily ingestion rates for groundwater, body weights, and exposure
durations for children (ages 1 to 6 years) and adults (ages 7 to 31 years). The exposure
frequency is assumed to be identical for the two exposure groups. These assumptions, along
with the exposure point concentrations, are plugged into equations to give the Chronic Daily
Intake GDI) for each exposure pathway. The GDIs for groundwater ingestion for the potential
future site residents are provided in Table 7-4.
26
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Record of Decision
NAS Paisacola Site 39
July 1995
Table 7-1
**-^p*Mtir* Pathways Summary
NASPensacolaStte39
Rnsacola, Florida
Potentially Exposed
Medhnn find Exposure
Pathway
Pathway Selected
for Eraination?
Reason for Sffcftiiiii or
Current Land Uses
Residents (CuBd
andAduit}
Trespasser
Aiff JohsJflooJi of gaseous
^^^11^* —_-_|_ —.„—-J^Xtlx—,
fromsoil
Air, Inhalaoon of
fugitive dust
potable or general use
Sofi, Denial comer
Air, Inhalation of gaseous
fton soil
Air, Inhalation of
fugitive dust
No
Mo
No
No
No
No
No
No
fuftilive dust
Tic gaseous »ir pathway is not considered due
The sand grains, described asfine-naedium
gntBi uuaiUi are not respirable.
Gwnndwmier is not cunendy used as a source
of potable or indostnal water at Site 39.
Ground*
r js not cuneodjriised as « source
of potable or industrial water at Site 39.
PosMemovalsoa excluded from fte BRA,
Post-removal joal exctaded front die BRA.
The gaseous air pathway is not considered due
to the absence of signiffcanT volatile chemicals
in soil.
The sand grains, described as fine-medumi
grain quartz, are not respirable.
Soil, Inridemal ingesrion
Sofl. Dermal contact
No Post-removal soil excluded from die BRA.
Future Land Uses
Future Site
Residents (CbBd
andAduJty
Ait, Inhalation of gaseous
fromsoa
Air, Inhalation of
Ife ibc gtsemis sir pathway is sot considered duo
Yes
potante or general use
gnunonanzv are not resphabie.
The :CoaibiutU shallow and intermediate depth
water-bearing zones couM hypothencally be
used at aicsidrnriil water soatce.
27
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Record of Decision
NAS Pensacola Site 39
July 1995
Potentially Exposed
Exp
Table 7-1
! Pathways Sn
MAS Pcaaccoia Site 39
Florida
PuthwBy
Pathway Selected
for Evaluation?
Reason for Selection or F.Tdnaon
Future Site
Residents tov; the pmnary sofl contimigants
TH'fllf'|f1l1r!Hllf Ifffff TflltT" BTT gOOC SUBC ttK
execntion aaditmoval effort
The gaseous air pathway is not considered due
to the absence of volatile chfinfculs in sofl.
The sand grains, described as fine-medium
gnin quartz, are not respnable.
The combined shallow and uuermediate depth
water-bearing zones are not likely to be used
as an occupational water source.
Post-removal soil excluded from the BRA.
Post-removal sofl excluded from the BRA.
Note:
Dermal contact exposure pathways for aqueous media were not considered viable.
28
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Record of Decision
NAS Peraacola Site 39
Juty 1995
Tank 7-2
Statistical Analysis of COPCs in Shallow and Intermediate Groondwater
NAS Pensacota, Site 39
Natural Log Transformed
VCL
Chemical n Mean SD HStat (mg/L)
Aluminum 7 -1.20 • 1.94 6.53 348.15
Arsenic 7 -6.27 0.64 2.76 0.003
Tetnchfoioeme&e 7 0.099 0.26 2.07 0.001
Nate
NA - NotAppfabfc
Hsu - TtaeH-ntiaie«s excapud ban GiBKH. 1987.
ND - Not deucBd m idiuuEe wdb.
UCL - Upp, confidence limit
nij/L ™ Mnligfms per UET. *
Detection
(mg/L)
15
0.005
0.002
H.^^MVB.^__- X«M>M.^M<
&UM1UHUI QCSEKK
Reference
(mg/L)
3.88
2.80
NA
IferdeCOPCiwcRinal
EPC
(n^L)
15
0.005
0.002
as EPC.
Fan
Table 7-3
i Used to gc«™rt» Potential Exposures for Future Land Use Receptors
Pathway Parameters
Resident flifuii
Resident Child
Nattf
a - USEPA (1989) TUik Artrmrm GuJOncc fat Supertmd Vol. 1. Hnmm He«MiEviharianM«nal (PmA).'
b - USEPA (1991) TOfkAffonxttGiiklBixfeSaperfBd Vol. I: Hanm Habh Evtkaiiaa Manal
•taerin Fknl, OSWER Dnecove: 928S.64>3fPA/GOO/8-89AM3.
c - VSEP\(mn.tOiAaamtatOaamtefatSefalaa: \it.l—tlantaeaai&^aMaMa*a
>.• OSWER Direane 9Z85.741B.
Units
•
IngeaionlU*
Exposure Frequency
Exposure Dunrion
Exposure DunttonLWA
Body Weight
Averaging Time. Non-cancer
Avenging Tone. Cancer
*
350*
24e
24C
70"
8.760"
25450-
1*
350*
- 6°
6"
iy
2.190*
25450*
BtcB/day
days/year
yean
years
kg
days
days
efnlt Expone FMon.
d
c ** CucuuXBo tt oc poAtt of TV ycut (•tuuDioo UCUDB) x 3o5 datyi per ycv.
NA - Naapptiafate.
CSV - Cbomotl-specific vitoe
In araxcdrace vtt Sqiplenicn^ Guidince D RAGS film USEPA Regka
29
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Record of Decision
NAS Pensacola Site 39
July 1995
Table 7-4
Chronic Dafly Intakes for Potential Future Rrddfntu — lagection of Shallow and Intermediate Gronadwater
NAS Peuacah, Site 39
Chentol
An_
Arsenic
^*6flichloioctncBc-
iL&pusurc cuuu
(mg/L)
15
0.005
0.002
ruuuc luaweiu
C-CDI(a)
(mg/kg-day)
134&«1
7.45E-05
ZJS7&-5
rUUlfC MCollKW
AdnttH-CDI
(mg/kg-day)
4.12EO1
1J7&04
5.48E-3
ChfldH-CDI
(mg/kg-day)
939&QI ;
3JOE04
1.28&4
Notes:
In accordance with Supplemental Guidance to RAGS from USEPA Region IV regarding the mhalation of VOCsm groundwater, mhalation CDI
is equivalent to ingestion GDI for tetrachloroethene; the COI for tetncaloroethene was used to separately calculate inhalation and ingestion risk
and hazard.
a = Carcinogenic chronic dairy intake is based on the lifetime weighted avenge of an adult age 7-31 and a child age 1-6.
CDI = Chronic daily intake in units of mg/kg-day.
C-CDI = CDI for excess cancer risk.
H-CDI = CDI for hazard quotient.
mg/L = Mflligrams per liter.
mg/kg-day = Milligrams per kilogram per day.
7.3 Toxitity Assessment
The USEPA has established a classification system for rating the potential carcinogenicity of
environmental contaminants based on the weight of scientific evidence Slope factors (SF) have
been developed by the USEPA for carcinogenic compounds. The SF is defined as a "plausible
upper-bound estimate of the probability of a response (cancer) per unit intake of a chemical over
a lifetime."
In addition to potential carcinogenic effects, most substances also can produce other toxic
responses at doses greater than experimentally derived threshold concentrations. The USEPA
has derived Reference Dose (RfD) values for these substances. These lexicological values are
used in risk formulae to assess the upper-bound level of cancer risk and non-cancer hazard
associated with exposure to a given concentration of contamination
30
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Record of Decision
NAS Pensacola Site 39
Juty 1995
For carcinogens, the potential risk posed by a chemical is computed by multiplying the GDI (as
mg/kg-day) by the SF (in reciprocal mg/kg-day). The hazard quotient (for non-carcinogens) is
computed by dividing the GDI by the RfD. The USEPA has set standard limits (or points of
departure) for carcinogens and non-carcinogens to evaluate whether significant risk is posed by
a chemical (or combination of chemicals). For carcinogens, the point-of-departure range is 10"6.
For non-carcinogens, other toxic effects are generally considered possible if the HQ (or sum of
HQs for a pathway — hazard index) exceeds unity (a value of 1). Although both cancer risk
and non-cancer hazard are generally additive (within each group) only if the target organ is
common to multiple chemicals, a most conservative estimate of each may be obtained by
summing the individual risks or hazards regardless of target organ. This approach was used in
the BRA. Table 7-5 summarises lexicological data hi the form of RfDs and SFs obtained for
each COPC identified in Site 39 groundwater.
It was determined that risk or hazard via the ingestion and inhalation of groundwater for the
groundwater pathway hazard index was 2 for the future child resident and 0.9 for the adult.
7.4 Risk Characterization
Risk characterization combines the results of the exposure assessment and toxicity assessment
to yield qualitative and quantitative expressions of risk for the exposed receptors. The
quantitative component expresses the probability of developing cancer, or a non-probabalistic
comparison of estimated dose with a reference dose for non-cancer effects. These quantitative
estimates are developed for individual chemicals, exposure pathways, transfer media, and source
media, and for each receptor for all media to which one may be exposed. The qualitative
component usually involves comparing COC concentrations in media with established criteria
or standards for chemicals for which there are no suitable toxicity values.
Exposure to groundwater onsite was evaluated exclusively under a future site resident scenario.
Ingestion through potable use and inhalation of volatilized contaminant exposure pathways were
evaluated. For non-carcinogenic contaminants evaluated relative to future site residents, hazard
31
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Record -of Decision
NAS Pensacola Site 39
Juty 1995
Table 7-5
lexicological Database Information for NAS Pfmacob, Site 39
U^tut flinty
Factor
0«neal
Alnmmum
Arsenic
Tetnchioroemene
urai
Reference
DOM
(mg/kg/day)
U>»
0.0003*
OJ)1*
Reference
DOM
(mg/kg/day)
ND
ND
ND
Oral Cancer
Potency Factor
[(mg/kg/day)H
ND
1.75*
OJDS2'
Cancer
Potency Factor
[(mg/kg/day)H
ND
15.1-
0.00203'
Cancer
ND
A
0*2
Oral
ND
3
1000
Inhabit
ten
ND
ND
ND
Nous:
The ARAR for aluminum (0.05 to 0.2 mg/L) is a water baldness-dependent secondary ™ »«"""» contaminant level range, and the ARAR for
arsenic (0.05 mg/L) is a promulgated maTtmnm Bnmaminant level. The ARAR for tetrachloroemene (0.003 mg/L) is a Florida Primary Drinking
Water Standard (FPDWS).
a =
b
c =
ND
mg/kg/day =
Cancer Class A =
Cancer Class B2-C =
Integrated Risk Information System (IRIS)
Oral reference dose provided by USEPA Region IV Risk Aw-wr-ii' Reviewer
y», ' , , • f* *i..?ii MHUi A ii r • • • •! i • • f^ff i fCf* A f\\
environmental criteria ana nhnf Miiif in utnce \CCA\J)
Not ojeteimined due to ip^K of infonnanon.
milligmns per kilogram per day
ru»«ffi«H (5 a known, human carcinogen by USEPA
as a probable to possible human carcinogen by USEPA
was computed separately to address child and adult exposure. The shallow and intermediate
water-bearing zones monitored during the RI were combined for assessment. Table 7-6 presents
the computed carcinogenic risks and/or HQs associated with the potable use of shallow and
intermediate groundwater for drinking water.
The computed hazard indices for ingesting of shallow and intermediate groundwater used as a
potable source for the future child and adult resident were 2 and 0.9, respectively. Arsenic
aluminum, and tetrachloroethene were identified as groundwater COCs. Arsenic and aluminum
were the primary contributors to the hazard indices for the child and adult receptors, and arsenic
was the primary contributor to the total carcinogenic risk. The state of Florida does not consider
arsenic a COC because arsenic concentrations did not exceed the Florida Primary Drinking
Water standard. Inhalation and ingestion risk and hazard results calculated for tetrachloroethene,
32
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Record of Decision
NAS Pensacola Site 39
July 1995
a volatile organic compound, are shown separately in Table 7-6. Tetrachloroethene was a minor
contributor to risk and hazard, having a hazard quotient less than 0.1 and an ILGR less than
2E-6 for each receptor type and exposure pathway. As shown in Table 7-6, the incremental
excess carcinogenic risk for the future site resident via the shallow and intermediate groundwater
ingestion/inhalation pathway was calculated to be 1.3E-04.
Table 7-6
Hoard Quotients and Incremental Lifetime Cancer Risks-Potential
rmure nemans ingesoan 01 anauow ana inwnnamue i
NAS Pensacola, Site 39
Chemical
• Aluminum
Arsenic
Tetracflloioeinenc
(ingcstioo)
Tetrachloroethene
(inhalfttion)
Slope Factor
Used
[(mg/kg-dayH
ND
1.75
0.052
0.00203
Reference
Dose Used
(mg/kg-day)
1.0
0.0003
0.01
0.01
Hazud Indices/Total Cumulitive Risks
Notes:
a • = Incremental
Ftatnre
Resident Adi*
Quotient
(mg/kg-day)
0.4
0.5
0.005
0.005
0.9
trounowmer
Future
Resident Child
ffaf aid
Quotient
(mg/kg-day)
1.0
1.1
0.01
0.01
2
lifetime cancer risk (ILCR) is based on me lifetime weighted average (Iwa) of an adult a
Future Rffptfntf
ILCR bra (a)
[Ong/kg-dayH-l
ND
1E44
Uv*
SB*
1E-04
ge 7-31 and a child age
1-6.
ND = Not determined due to lack of available information.
ing/kg/day = Milligrams per kilogram per day.
7.5 Risk Uncertainty
Exposure Pathways and Contaminants
Chemicals present in site samples (CPSSs) were initially eliminated from the BRA based on the
criteria agreed on by USEPA, FDEP, and the Navy. The risk/hazard thresholds of 1E-6 and
0.1 were selected to account for potential cumulative effects of various chemicals, and the
maximum concentration detected was compared to the corresponding screening value. As
discussed previously in the BRA, the comparison was made using the most conservative
33
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Record of Decision
NAS Pauacola Site 39
July 1995
screening value provided by USEPA Region HI, USEPA Region IV, and FDEP for each
exposure medium. Although some uncertainty exists regarding potential cumulative effects, the
fact that mavtmum concentrations detected were used in the screening comparison in concert
with low range risk/hazard thresholds alleviates much uncertainty. A large number (i.e., greater
than 10) of constituents would have to be present at near-RBC concentrations to elicit a concern
for cumulative effects. However, the target organ for each COC is different and the hazard
'quotient should be considered individually. The potential carcinogenic risk was computed to be
1.3E-04 due to arsenic concentrations. Customarily a hazard index of 1 and carcinogenic risk
range of 1E-04 to 1E-06 is considered acceptable by the USEPA while FDEP point of departure
is 1E-06 excess cancer risk. Arsenic and aluminum are potentially related to saltwater intrusion
or suspended sediment in samples and are likely not site-related. In addition, the arsenic and
tetrachloroethene exposure point concentrations (i.e., die maximum concentration detected) of
0.005 mg/L and 0.002 mg/L respectively, were below the corresponding state and federal
drinking water standards of 0.05 mg/L and 0.003 mg/L, respectively. The state of Florida does
not consider arsenic a COC at this site because the arsenic concentrations did not exceed a
Florida primary Drinking Water standard. While the aluminum exposure point concentration
of 15 mg/L exceeds the EPA secondary drinking water standard of .05 to .2 mg/L, this standard
is not health based but applies to the taste, odor, color and certain other non-aesthetic effects of
drinking water. EPA recommends these guidelines as reasonable goals, but federal law does not
require strict compliance with them. Moreover as previously outlined, aluminum is potentially
related to saltwater intrusion or suspended sediment in samples.
Comparison to Reference Concentrations (Background)
Because the intent of the BRA is to estimate the excess cancer risk or health hazard posed by
COPCs, a comparison to reference concentrations was performed subsequent to comparison to
screening values. The maximum concentration detected for each chemical that exceeded its
corresponding screening value was compared to two-times the mean reference concentration, if
a reference concentration was available. Because low frequency of detection could indicate a
34
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Record of Decision
NAS Pensacola Site 39
July 1995
contaminant should not be addressed in the BRA, all detected chemicals that failed the screening
comparisons were evaluated with respect to frequency of detection and consistency of detection
in two or more sampled environmental media. This approach was selected as a conservative
screening approach.
Additional uncertainty is introduced by a comparison of site data to non-specific screening
reference data. Although the reference concentrations are specific to NAS Pensacola, they are
not site-specific.
Comparison to USRDA
Due to the proximity of Pensacola Bay, it is possible that occasional -saltwater intrusion in the
groundwater sampled at Site 39 is the primary source for. the essential nutrients detected. As
listed in The Chemistry of Natural Waters, essential nutrients arsenic, potassium, sodium, and
iron are components of seawater. These essential nutrients are also naturally occurring in soil.
In an effort to focus this risk assessment on any dominant risk/hazards present at Site 39,
essential nutrient information was used as part of the screening process to further reduce the
number of CPSSs evaluated.
In order to assess the potential for toxic effects due to excessive doses of essential nutrients, the
maximum detected concentrations of essential nutrients were compared to USRDAs. In addition,
as RAGS Part A suggests, arsenic was retained as a COPC in groundwater since acceptable
dietary concentrations associated with arsenic are not well established.
In groundwater, arsenic, iron, and magnesium were the only essential nutrients with maximum
detections exceeding screening and reference criteria. Iron and magnesium were eliminated from
the quantitative risk assessment because at the 2 L/day groundwater ingestion rate, 17.2 mg of
iron, 96 percent of the USRDA, and 6.8 mg of magnesium, 0.017 percent of the USRDA,
would be ingested.
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Record of Decision
NAS Paaacola Site 39
Jufy 1995
Characterization of Exposure Setting and Identification of Exposure Pathways
Uncertainty in the exposure setting and pathways exists due to the highly conservative
assumptions (i.e., future residential use) recommended by USEPA Region IV when assessing
potential future and current exposure. As previously discussed, no potable (or industrial water)
wells exist at Site 39, and none are projected for installation.
Determination of Exposure Point Concentrations
Based on the guidance provided by USEPA, EPCs are those concentrations used to estimate
CDI. The uncertainty associated with EPC primarily stems from their statistical determination
or imposition of maximum concentrations, described below.
Statistical Estimation of Exposure Point Concentrations
USEPA provided supplemental guidance which outlines a statistical estimation of EPC. These
calculated concentrations are 95 percent UCL which are based on certain assumptions. USEPA
assumes that most (if not all) environmental data are lognormally distributed. Uncertainty exists
in this assumption because many environmental data are neither normally nor lognormally
distributed.
The UCL calculation is provided hi the Supplemental Guidance to RAGS: Calculating the
Concentration Term, May 1992. This calculation includes a statistical value, the H-statistic, is
based on the number of samples analyzed for each COPC and the standard deviation of the
results. To obtain this number, a table must be referenced, and the value must be interpolated
(an estimation) from the table. The equation for the H-statistic has not been provided in the
supplemental guidance, nor does the document referred to in the guidance provide the equation.
Although the statistic appears to be non-linear, a linearity assumption was made to facilitate
interpolation of the statistic for each COPC addressed in the BRA.
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Record of Decision
NAS Pensacola Site 39
Jufy 1995
Linear interpolation is a good estimate of H; however, it is important to note that the formula
and H are natural log values, and H is applied as a multiplier. The effect of multiplying natural
log numbers is not equivalent to multiplying untransformed values. While data are log
transformed, adding two numbers is the equivalent of multiplying the two numbers if they were
not transformed. The effect of multiplying a number while in log form is exponential, and H
is applied as a multiplier. In summary, using this method to calculate the UCL includes much
uncertainty (an overestimation of risk/hazard), and often provides concentrations greater than
the maximum detected onsite. The calculated UCL for aluminum, arsenic, and tetrachloroethene
are greater than or approximately equal to the maximuip concentrations detected, and the number
of samples was less than 10. Therefore, the maximum concentrations detected were used as
Although RAGS advocates using neither worst-case scenarios nor maximum concentrations as
EPCs, the use of the H-statistic often necessitates using the reported maximum concentration as
EPC. The lesser of the maximum concentration and the UCL is used as the EPC. Summation
of risk based on maximum concentrations leads to overestimating risk/hazard, especially in the
case of low detection frequency or spatially segregated COPCs. This concept is further
discussed below.
Frequency of Detection and Spatial Distribution
Because of the influence of standard deviation on EPC, low frequency of detection can cause
COPCs to be inappropriately addressed in the risk assessment. More specifically, COPCs
detected only once or twice in all samples analyzed (having concentrations exceeding the RBCs
and reference concentrations) would be expected to have relatively higher standard deviation as
concentration variability or range widens. Higher standard deviation results in a high H-statistic,
and this typically leads to a UCL greater than the maximum concentration detected onsite. If
that is the case, then using the UCL or maximum concentration detected as EPC (or possibly
37
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Record >cf Decision
NAS Pensacola Site 39
Jufy 1995
the inclusion of the COPC in question) may not be appropriate when EPC is assumed to be
ubiquitous.
The spatial distribution of chemicals detected in groundwater does not indicate the presence of
an identifiable source at the 39GS04 shallow zone monitoring well at Site 39 (i.e., within the
former stained soil area). The concentrations detected at the location in question would be
expected to be elevated when compared to data corresponding with surrounding monitoring
wells. However, groundwater data are not elevated at this location (39GS04) relative to other
Site 39 monitoring wells. The spatial distribution of COPCs is described below for second phase
groundwater data. Tetrachloroethene was detected in well 39GS01 (the upgradient well).
Aluminum was detected in two shallow wells and one intermediate well, 39GS03, 39GS04, and
39GI05, respectively. The highest concentration was detected in 39GS03. Arsenic, an element
associated with seawater, was detected in the two downgradient shallow wells, 39GS02 and
39GS03 (i.e., closest to the bay). The highest concentration of arsenic was detected in 39GS02.
The gradient and groundwater flow onsite is generally toward the bay. The groundwater flow
gradient at Site 39 is low. As a result of the limited gradient and potential tidal influences, the
pattern of transport from the former suspected source area would have been controlled by
diffusivity. The random distributions observed in the RI groundwater data are not indicative of
diffusion from a concentrated source area.
Due to the abundant supply of good quality water hi the deeper main producing zone
groundwater from the surficial zone of the Sand-and-Gravel Aquifer is not used as potable water
in Southern Escambia County nor is it anticipated to be used for that purpose in the future.
Furthermore, groundwater at the site and at NAS Pensacola is highly turbid and contains ambient
iron and manganese concentrations exceeding Florida's secondary drinking water standard
concentration. The data from this investigation suggest that the site has not degraded the quality
of the aquifer; instead, the metal concentrations found are typical of the Sand-and-Gravel
Aquifer as a whole.
38
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Record of Decision.
NAS Pensacola Site 39
Juty 1995
Currently there are no full time residents nor potable water wells at Site 39 therefore, there are
no human receptors for the Site 39 groundwater, and consequently no current exposure. The
hazard index is based on a summation of the hazard quotients for all of the COCs for a future
child resident. However, the target organ for each COC is different. Therefore, individual
hazard quotients should be considered instead of summing the hazard quotient for all COCs.
If a hazard index of 1 was selected for a cleanup threshold, only arsenic (1.1) slightly exceeds
that threshold for a future child resident. The aluminum and arsenic found in Site 39
groundwater is typical of the concentrations found throughout NAS Pensacola and should be
considered background levels of these inorganic compounds.
7.6 Ecological Risk Assessment
An ecological risk assessment was performed to determine the actual or potential effects of
Site 39 on the surrounding ecosystem. Based on the relatively limited area of contamination and
the lack of suitable habitat onsite, effects from the site contaminants are not expected to be a
concern. However, specific effects to overall biota within the affected area are unknown. This
is compounded by the lack of available data on acute and chronic toxicity in soil for the
chemicals of concern discussed. Instead of attempting to quantify these effects, it was
determined that the most cost-effective and environmentally and aesthetically beneficial remedy
was to simply remove and properly dispose of the contaminated soil and replace it with clean
fill material.
8.0 DOCUMENTATION OF NO SIGNIFICANT CHANGES
The Navy presented a PRAP for Site 39 on June 13, 1995. The no action remedy consisted of
the same components described in this ROD. No significant changes have been made to the no
action remedy described in the proposed plan and presented to the public.
N:\WF51\ALD\FCOLA\CraOS3\ROD
39
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Record of Decision
NAS Pensacola Site 39
July 1995
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40
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Appendix A
Responsiveness Summary
-------
RESPONSIVENESS SUMMARY
Overview i
At the time of the public comment period, the U.S. Navy had selected a preferred remedy to
address soil and groundwater contamination at Site 39 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 and no fundamental objections to its selection have been raised.
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 which 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, the West Florida Regional
Library, and the John C. Pace Library of the University of West Florida.
In May of 1995, newspaper announcements were placed to announce the date and location of
the public meeting to present the proposed remedial action plan (PRAP), the public comment
period (May 30 through June 30, 1995) and included a short synapses of the proposed plan.
These adds ran in the Pensacola News Journal on May 18, 1995 and in the Pensacola Voice and
the New American Press during the week of May 18, 1995 through May 24, 1995. In
conjunction with these newspaper announcements, addresses on the Site 39 mailing list were sent
a technical summary of the PRAP and notice of the public meeting. A public meeting was held
at the Pensacola Junior College Warington Campus on June 13, 1995. Approximately
25 people attended the public meeting.
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Summary of Comments Received During the Public Comment Period
During the public meeting on June 13, 1995 the proposed plan was presented to the public and
the floor was opened for comments. No oral or written comments were received at this time.
Comment cards were provided at the public meeting and with the mailed announcements.
During the public comment period of May 30 through June 30,1995 no comments were received
on the Site 39 Proposed Remedial Action Plan.
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Appendix B
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 which 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 Superfnnd 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 DOD 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.
FEASIBILITY STUDY: See Remedial Investigation/Feasibility Study.
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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 (HRS): A scoring system used to evaluate potential 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 located at the West Florida Regional Library, 200 W. Gregory Street,
Pensacola, Florida; The John C. Pace Library, University of West Florida; and the
NAS Pensacola Library, Building 633, 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 (NFL): 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
prior to 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 clean up 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
altemative(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 gmj 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.
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
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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 dose 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, 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.
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SUPERFUND: The trust fimd 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 non-petroleum 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 above ground, 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 C
Florida Professional Geologist Seal
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Record of Decision
NAS Pensacola Site 39
July 1995
FLORIDA PROFESSIONAL GEOLOGIST SEAL
I have read and approve of this Record of Decision for Site 39 and seal it in accordance with
Chapter 492 of the Florida Statutes.
Name: Brian E. Caldwell
License Number: #1330
State: Florida
Expiration Date: July 31, 1996
Brian E. CaldweJl
Date
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