PB94-964069
EPA/ROD/R04-94/203
January 1995
EPA Superfund
Record of Decision:
USAF Homestead AFB,
(0.U.3), (Site SS-13), FL
9/16/1994
-------
. I
Homestead .Air Force Base, Florida
Operable Unit 3 . .
SiteS$-t3,PCB S,piU Area
Declaration for the Record of Decision
/
":., . .1. ,
-------
DECLARATION
.-
FOR THE
RECORD O.FDECISION
SITE NAME AND LOCATION
Homestead Air Force 'Base
H~ Dade County,Florida
Operable Unit No. 3 ~ Site 55-13
PCB Spill Area (Former Site SP-3)
STATEMENT OF BASIS Al\TJ> PURPOSE
This decision document presentS the selected remedial action for the PCB Spill Area
(Site 55-13) Operable Unit No.3. at Homestead Air Force Base. in Homestead. Rorida.
The selected remedial action is chosen in a.ccordance with CERCLA.. as amended by
SARA. and.. to the extentpractica.ble. the National Oil and Hazardous Substances
Pollution Co~tingel!CY :~~ (NCP). This decision is based on the a~inistrative recor~
for this site.. . .
The State of Flo~ the U.S. Environmental Protection Agenq (USEPA), and me U.s.
Air Force (USAF) concur with the selected remedy presented in this Record of Decision
(ROD).
DESCRIPTION OF THE SELECTED REMEDY
No action.
DECLARATION STATEMENT
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
remedial aCtion. and is cost-effective. This remedy utilizes permanent soluuons to the
- 1-
o
-------
maximum extent prncticable for this site. Beamse the previous removalfremedw action
at this site did not result in the implementation of engineering or insumuonal controls to
prevent unacceptable exposures from h:lz.ard.ous substances and beca.use" Uris remedy will
not result in hazardous substances remaining on site above health-based levels. the
five-year review ",ill not apply to this aCtion.
STATE OF FLORIDA
DEPARTMEN10F ENv1RONMENiAL PROTECTION
A..f /") C) t/JLf
Dare: Ur..--t. ~c:/ 7(
.
UNITED STATES AIR FORCE
HOMESTEAD AIR FORCE BASE
Mr. Al2.D. Olsen
DirectOr, HQ AFBCA-DR
DateS~/&1 191'
By:
-2-
-------
- ,'(,£0 sr.,
.:>". 'so
... ~ ~
~ -- v
~w Gt :.
~.. ,""".i" C
'"' ..
~ ,>:
if....,' ~...;>
~, ""01~
UN ITED ST ATES ENVIRONM.ENT ALPROTECTION AGENCY
REG.lON IV
345 COURTLAND 'STREET. N.E.
ATLANTA. GEORGIA 30:365
SEP 1 6 1994
'"
4WD-FFB
Certified Mail
Return Receipt Requested
Mr, Alan Olsen
AFBCA/DR
1700 North Moore Street, Suite 2300
Arlington, Virginia 22209-2802
SUBJ:
Record of Decision for Operable Unit 3, PCB Spill Area
Homestead Air Force Base, Florida
Dear Mr, Olsen :
. ...--. ...
.-~.. - .~'-",~.. ;:".
The U.S, Environmental Protection Agency (EPA) Region IV has
reviewed the above referenced decision document and concurs with
the No Action Record,ofDecision for Operable Unit 3, PCB Spill
Area, as supported' b.Y .the previously approved Remedial
Investigation and Baseline Risk Assessment Reports.
The selected remedy is one of "No Further Action It . This
action is protective of human health and the enviromnent,
. complies with Federal and State requirements that are legally
applicable or relevant and appropriate to ~the"renieaial 'action and
is cost effective.
It is understood that the selected remedy for Operable
Unit 3 is the final remedial action to aqdress all media'
potentially affected by past disposal practices at this unit.
Sincerely,
cc:
~}YJ~1n
John H, Hankinson
Regional Administrator
Mary Bridgewater, Air Force Base Conversion Agency
Robert Johns, Dade County Environmental ResourceS
Management
Eric Nuzie, Florida Department of Environmental Protection
Humberto Rivero, Air Force Base Conversion Agency,
Operating'Location Y (Homestead Air Reserve Base)
7
"'0
-------
'-
Department of
Environmental Protection
i:
laWton ChiIes
Governor
Twin Towers Office Building
2600 Blair Stone Road
TaUahasse€. Florida 32399-2400
.. - .-----....-
Virginia B. Wetherell
Secretary
November 2( 1994
~x. Alan K. Olsen, Director
Air Force Conversion Agency
1700 N. Moore street, suite 2300
Arlington, Virginia 22209-2802
Dear Mr. Olsen:
The Florida Department of Environmental Protection agrees
with the Air Forcels selected alternative for Operable unit 6
(Site SS-13), PCB Spill Area at Homestead Air Force Base.
The Record of Decision specifies that the No Action
Alternative at site SS-13 is a cost effective remedy and provides
adequate protection of public health, welfare, and the
environment from PCB-related contamination. Note, a subsequent
investigative effort to address inorganic constituents found at
Site SS-13 will be performed under the scope of a Remedial
Investigation for Site SS-7 (Entomology Storage ~xea) located
southwest of Site SS-13. The determination of closing Site SS-13
so that further investigation proceeds under the scope of Site
SS-7 is consistent with the Comprehensive Environmental Response,
Compensation, and Liability Act (CERCLA) as amended by the
Superfund Amendments and Reauthorization Act and the National
Contingency Plan (40 CFR 300). .
In accordance with CERCLA as amended by SARA, the site will
undergo a five-year review with the costs of the review to be
absorbed by the Air Force.
We appreciate your continued cooperation and look forward to
an expeditious economic and environmental recovery of Homestead
Air Force Base.
Sincerely,
lli t~
~
Virginia B. Wetherell
Secretary
VBWjjrc
"p--c=~~<:=
C::;;:<;":>~''''....> ,::~c
.~.or,:c'c '$ E;~,/:.ro;-:':;c.--:= cr.c :\~~L;~<': >
~ ,.
.-~(';:: :;~.',--C'::';c
Pi:r.:.ec C:" t<;:C'/(;{.~<::" 'C::X..'~
-------
:.
Homestead Air Force Base, Florida
Operable Unit 3
Site ,55-13, PCB Spill A'rea
Decision Summary for the Record of Decision :,'
~7
, I.
/':".", / )) . -I-<"~.
-------
'LO
2.0
,.
J
.>
,
t,
r~f.EOFCONTE~:
~,
,..:,
. "
. .-.' .
SITE N~ LbCATION;.ANDI>ESCRIPTION~.....':"'..~..~.:......~._....~..__....~..: L
. .
SITE ,DESCRIPTION ...-.....:.---.........:........................--...........---......-.... 2
.LAND 'USE...~.._.........._..~.~......._~~...._....__...._......_._--_..-..-....-.........,......'3
SURFACE HYDROLOGY ...~._......;.~......_-~...~.....,..~--_...........................,.. 3
,L3.1. , . HyarQgeologic Setting...~.:._.~~~:__.....~....:....~._..................:..._.....;..... 4
SITEGEOLOOY AND HYDROGE()LOGY ...._...._-_...:...._.....~~.._....__6
SITE msTOR~ AND,ENFORCEMENt AGTIVITIES._...~~...........--...--.~..~.....- 7
1.1
1.2
1.3
104
2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
F.J:STOR Y~:"'''''~'''~~';;':''_''''_''''''''''__''__''''__''_-_''_''''_''_''..-..-................ 7
2.1.2 ' PaSt- SireJJsage -'~"--"-"-''''''''''.'''~'''''''''''''''''''''''''''''''''-''''''''''- 7
ENFORCEMENT HISTOR Y..........._~...~.........._....;..~........................:~....... '8
2.2.1 CERyLARegulatory'History ~[[[~ 8
INVESTJGA IIQN ...msTORY......._.._......_..........................................- 9
2.3.1 ,IRP..Ph3Se 1 -;-' 'Re:cora ':Search [[[9 '
2.3.2 IRP 'PhaSe,Il;;>CoDfmnati6n/Quantification .........................-.--...... 10
2.3.3 ,IRPPhaSeill-: Technology,Base;.j)evelopment .............--............~..-:l 0
2.304 mPPhaseIV~,- AdditionaUnvestigations .........................................10
2.3.5 1991-Remedial JnveStigatioii ..:~.;..........._......_.........._......~............~ n
2.3~6 1993;R.enledia.J.:Inv~tigaiion'Addendum ................-........................ 11
COMMUNITYRELATIONSHISTOR,Y ~............._...--......-........_~.....-..- '12
SCOPE AND:RQ~'OFQPERABlEHJNIT 3..........-........................_......13
sm' CHARActERIsTICS ..._--_..~....._._..~...._...._...._.._...--...._...... .'13
2.6:1 Nature and Extent'of Soil and UDsaturatedZone Contam1nation.....14
2. 6.1.1 Previous Investigation ...............................................-.... 14
2.:6.1.2 Current Investigation.__.......;.-..........--.....---........--.-- 14'
2.6.2'~~~=~~~:=..~~~:~:;~~:=:~~=:::::,}::::::I~ .
'2.622Current..Investigation......._..__.._--...........__............_- .15
2.63 Potential RoutesofMigration.-....._......-.---..........---...-..-:-.....--.- 15
2.6.4 ExpoSU're.'~rit_--_..~-_.._......_..__.._-_...._......__.:-_......- 16
SUMMARY .OF SITE-l~lSK ;~..._........_....__......__....-.............._...-..._...... ,16
2.7.1 I~ntificatidn: ofCofitaminants of Potential Concem........._............16
2. 7.2 Data Analysis.._.:..-.......-..-......--......-..................-........................17
2.721 Soil. .--.....-..--..-........--...........................-..........--- 17
2.7.2.2 Groundwater ..-........................-..................-................ 18
2.73 CompoundsofConcem Selection Process ...............................m..... ~8
2.7.4 Potential Routes of Migration ._...................m.....m....~................."" 18
2.7.5 Exposure .AsseSSIIlent___.._...........:.-..............................-............... 19
2.7.6 Toxicity Assessment .........-..................-.......................................... 20
2.7.7 Risk Chatacteriza.tion ..........-..................-........................................ 21
-------
Figure
No.
1-1
1-2
1-3
2-1
Table
No.
2-1
2-2
2-3
2-4
2-5
LIST OF FIGURES
Title
Follows
fue.
Location of Homestead Air Force Base [[[ 1
Site Location Map PCB Spill Area. Site SS-13 ............................................. 2
Base Location Map . ........ .... ............,..................... .................. ...... ............ ..... 4
PCB Spill Area. Site SS-13 Soil Boring and Monitoring Well
Location Map ............., .... "'''''' .... ...... .............. .......... ...... """""""" ...... ....... 11
LIST OF TABLES
Title
~
Soil Analytical Results - PCBs. 1991 [[[ 14
Soil Analytical Results - PCBs. 1993[[[ 14
Groundwater Analytical Results - PCBs. 1991......................................... 15
-------
. .
DECISION SUl\fMARY
;::.
FOR THE
RECORD OF DECISION
1.0
SITE NAME, LOCATION, AND DESCRIPTION
Homestead AFB is l~ approximately 25 miles southwest of Miami and 7 miles east
of Homestead in Dade County. Florida (Figure 1-1). The main Installation covers
approximately 2,916 acres with easements constituting an additional 429 acres. The land
surface at Homestead AFB is -relatively flat, with elevations ranging from approximately
5 to 10 feet above mean sea level (msl).
Homestead Army Air Field. a predecessor of Homestead AFB, was activated. in
September 1942. when the Caribbean Wing Headquarters took over the air field
previously used by Pan American Air Ferries. Inc. The airline had developed the site a
few years earlier and used it .primarily for pilot training. Prior.1O that time, the site was
undeveloped.
Ini~y. Hom~ArfnY AirF1eld~ed asastagingJaciJJ.tyf9I;$eArmy:r~rt
Command, which was responsible for maintaining and dispatching aircraft to overseas
locations. In 1943. the field mission was changed when the Second Operational Training
Unit was activated to train the transport pilots and crews. .
In September 1945. a severe hurricane caused extensive damage to the air field. Both the
high cost of rebuilding the field and the anticipated post-war reductions in military
activities led to the base being placed on an inactive status in October 1945. The base
property was turned over to Dade County. which retained possession of it for the next 8
years. During that time, the base was managed by the Dade County Port Authority. The
runways were used by crop dusters and the buildings housed a few small induStrial and
commercial operations.
In 1953, the federal government again acquired the Homestead Base. together with some
surrounding property, and over the next 2 years rebuilt it as a Strategic Air Command
(SAC) base. The fIrst operational squadron arrived at Homestead AFB in February 1955,
and the base was fonnally reactivated in November of the same year. Except for a short
-1-
! ;
-------
period during 1960. when modifications were made to accommodate B-52 aircraft. the
base remained an operational SAC base until 1968.
The command of Homestead AFB was changed from SAC to the Tactical Air Command
(TAC) in July 1968. and the 4531st Tactical Fighter Wing (TF\V) became the new host
unit. F-100 C's and D's were flown there during this time. When the 31st TFW returned
from Southeast Asia during October 1970, the designation 4531st TFW was deactivated
and the 31st TFW became the host unit for Homestead AFB. flying F-4 D's and E's. In
1981. the 31st TFW was redesignated the 31st Tactical Training Wing (TTW). In
October 1984. the base was converted to the 31st TFW and is currently home to F-16
aircraft. One tenant organization still flies F-4 aircraft. The Base was transferred to HQ
A,ir Combat Command (HQI ACC) on June 1. 1992.
In August 1992. Hurricane Andrew struck south Rorida causing extensive damage to the
Base. Military activities are currently minimized while the future of the base is
considered. No other activities or tenantS presently occur at the site. The majority of the
Base housing area is unoccupied with only essential base security and maintenance
personnel currently housed at the site. There are approximately 100 U.S. Air Force
employees living in temporary base housing. No families are presently housed at the
Base. The Base is presently on the Base Realignment and Closure (BRAC) list slated for
realignment with a reduced mission.
1.1
SITE DESCRIPTION
Operable Unit No.3, identified as Site SS-13 (Operable Unit No.3 or Site SS-13) is
located immediately behind Building 220. located within the Civil Engineering Storage
Compound. The Civil Engineering Storage Compound. Site SS-13 occupies
approximately 0.5 acres in the west-central pornon of Homestead AFB (Figure 1-2). This
storage compound is bordered by Westover A venue to the east which is paved and
oriented north/south; a drainage canal to the west; open land to the south; and storage for
large military trucks and equipment to the north. East of the site and west of Westover
A venue is an auto shop work yard.
The Civil Engineering Storage Compound was established as a storage area in the late
1960's and early 1970's. !vliscellaneous materials such as lumber. piping. air handlers.
cable. conduit. and transformers were stored there. The area was not fenced until the mid
1970's and early 1980's. Building 220 was used to store plumbing and electrical fittings
-2-
-------
. .~
N
r/:\
~ / \ ~
'~1 \ i ~ }-----------\
r" I i 0 ~ )
~ '\\ ( L : HENDRY COUNTY : )
\ \~~.J/ FT. MYERS: : PAlM BEACH COUNTY
~ ~~ i-----:: (
l ,-- I I
l I I I BOCA RATON.l
t--~ I r---------------
\ '-------i BROWARDCOUNTY J
I FORT-,-
COLLIER COUNTY: LAUDERDALE
1----1... .J'""--4
, ------ I
r-, I ~I
'- - 'DADE COUNTY ~MJAMI
~~O~:~~~~;: )i
0,- - - V .; PERRI~r 8IS~~:~~ .
: HO~ESI=:~ HOMESTEAD
EVERGLADES -I ~) AFB
-I . > p
A:frAL ~-~'J..
~~~
.
. . ..
" .
J
~.
~
,.....
" :lfl
.a -, ~.".""'V"
-------
CE STORAGE
COMPOUND
~
~
LEGEND
~
~..;
'"
[.//] BUILDING LOCA nON
.-
:: L-... ~.
-,-~-_.
""~=,,--=--_.
\
\
\
\
\
\
';!<.
y...-::::-- \
~ \
'f..." ENTOMOLOGY \
--- STORAGE AREA Ii
"'+~, @(
-r~~ X
~~
y...~
y...~
---
50
I
o
,
50
,
APPROXIMA TE SCALE
1
X--- N
-r\ I
X \ \
1\ \
en \
\\
~ \
!- \
u.! \
~\
i t5 \
X\ u \
\ ~ \
X ~ \
\
~
IX
\
\
\
HOMESTEAD AIR FORCE SASE
FLORIDA
S/TE LOCA TfOX ,.\1,4P
;':)::3 SPILL A. PEA. S,'7"'E ss~ ~::;.
F!GURE 1-2
------ --- - - - --
-- --
-------
that needed weather proteCtion. Prior to HUrri.carie Andrew in August 1992, the storage
compound was utilized .t()stOfe iJemssuch as old military jeeps,. solar warer heating
equipment, dumpsters. non-PCB containing transformers, razor wire, lumber, air
handlers. cable. conduit, and assorted steel pipe. Presently, only the steel frame and
concrete foundation remain at Building 220 and the compound is used to store
salvageable hurricane remnantS such as refrigerators, stoves, and miscellaneous
appliances. The site surface is primarily weathered limestOne.
1.2
LAND USE
The area adjacent to Homestead AFB including Site SS-13, to the west, east, and south
within a half"-mile radius, is primarily composed of farmland and plant nurse:ries.
Residential areas are located within a half-mile to the north and southwest of the Base.
Woodlands are located approximately one~half-mile east of the facility and mangroves
and marsh occur adjacent to "Siscayne Bay. The Biscayne National Park is located .2
miles east of Homestead AFB;the Everglades National park.is located 8 miles
west-southwest of the Base; and'the Atlantic OCean 'is approximarely 8 miles east of the
Base.
1.3
SURFACE HYDROLOGY
, "
Smface hydrology at Homestead AFB. including Sire SS-13 is controlled by five main
factors: 1) relatively impermeable areas covered by runways, buildings and roads; 2)
generally high infIltration ,rateS through the relatively thin layer of soil cover; 3)fiat
topography; 4) generally high infiltration rates' through the . outcrop locations of the
Miami Oolite Formation; and 5) relatively high precipitation rate compared to
evapotranspiration rate. Infiltration is considered to be. rapid through surfaces of oolite
outcrop and areas with a thin soil layer. Infiltration rates are accelerared by fractureS
within the oolite, as well as naturally occurring solution channels. Precipitation
percolates through the relatively thin vadose zone to locally recharge the unconfined
aquifer.
Natural drainage is limited because the water table occurs at or near land surface. The
construction of numerous drainage canals on Homestead AFB has improved surface
water drainage and lowered the water table in some areas. Rainfall runoff from within
Homestead AFB boundaries is drained via diversion 'canals to the Boundary Canal. A
dike is present along the outSide of the bank of the Boundary Canal to prevent runoff
-3-
j:
-------
from outside the propeny from entering the canal. As can be observ~ in Figure 1-3, the
Boundary Canal surrounds all but a portion of the facility propeny at the nonhernmost
end.
A drainage divide occurs within the Homestead AFB facility propeny, running from the
nonhern end of the facility, toward the center. Water in the Boundary Canal flows
generally south and east along the western boundary of the property, and south along the
eastern boundary, converging at a stOrm-water reservoir located at the southeastern comer
of the Base. Flow out of the stermwater --eservoir flows intO Military Canal. which, in
turn. flows east into Biscayne Bay, approximately 2 miles east of the Base. Water
movement is typically not visible in the canals in dry weather due to the lowered water
table and the very low surface gradient (0.3 feet per mile) that exists at the Base. The
drainage canal. located approximately 300 [t west of the PCB Spill Area. is not a likely
receptor of groundwater or surface water from Site SS-13 given that the groundwater
flow is typically to the southeast and a concrete retaining wall paralleling the canal
restricts surface water from entering the canal.
1.3.1
Hydrogeologic Setting
The regional hydrogeology in the southeast Florida area consists of two distinct aquifers:
the surficial aquifer system, which consists or the Biscayne Aquifer and the Grey
Limestone Aquifer, and the Floridan Aquifer.
Biscayne Aquifer. The Biscayne Aquifer at Homestead Air Force Base consists of the
Miami Oolite. Fort Thompson Formation. and the uppermost part of the Tamiami
Formation. In general. the most permeable partS of the aquifer lie within the Miami
OOlite and the Fort Thompson Formation.
The Biscayne Aquifer underlies all of Dade. Broward, and southeastern Palm Beach
Counties. It is wedge-shaped, thinning to the west beneath the Everglades and thickening
to the east along the coasL The Biscayne Aquifer is the sole source of potable water in
Dade County and is a federally-designated sole-source aquifer pursuant to Section 1425
of the Safe Drinking Water Act (SDW A). The Biscayne Aquifer supplies drinking water
to approximately 2.5 million people within local communities. Within 3 miles of
Homestead AFB, an estimated 1.600 people obtain drinking water from the Biscayne
Aquifer and 18,000 acres of farmland are irrigated from wells (USEPA, 1990). All
,
--.-
-------
L~I.
. .... .,....' I I ~ ., .'
.:.
31
X:J
. DRIVE
-
LEVEE
7
HIGHWAY
~
--
4
--------
~
.
HOMESTEAD
6
~
I
r~
N
,
LEVEE
r q----
: j
I
l Source: USGS 7.5 minute
i Topographic Quadrangles
IE Arsenicker. Homestead
~ Goulds. and Perrine. '
1000
I
o
1
2000
I
HOMESTEAD AIR FORCE BASE
HOMESTEAD, FLORIDA
BASE LOCATION MAP
FIGURE 1-3
FEET
!
f...
;
t
-------
. .
recharge to the aquifer is derived from local rainf'all.partof which 'is30~t loe:vaporation.
transpiIation.~d runoff.
The high permeability of the formations that comprise the Biscayne Aquifer is attributed
to secondary solution features created by percolatinggroundwaters. The solution cavities
, '.'
occupy.a significant volume of the oOli~c llinestOne and a.re commonly filled with fine to
mediUm~grained sand.causing~e limestone to have high . horizont¥ and .vertical
permeabilities. It is the high vertical permeability that permitsrapidinfilttation of ra1Dfall
to the groundwater. DUringpreeipitation events. the dominant movement of groundwater
. .
is toward the open canals. limiting mixing to the shallow portion of the aquifer. The
lower massive limestone unit also. has well developed secondary permeability. through
caverns as large as several feet in diameter. Because of the' extremely high permeab,ility
of this limestOne. alllarge-capacity wells are completed in this part of the aquifer. The
. .'
cavernous section generally does not contain loose sand.
In general. the Biscayne Aquifer has hydraulically interconnected groundwater flow with
fluid potentials at all depths Closely related to the. water table (Sonntag. 1987). The
aquifer is characterized by interconnected zones of cavernous limestone and. in the
Homestead area. has reponed transri:Jissivities ranging from approximately 4 to 8 million
gallons per day per foot (mgdlft) (Allman et al.. 1979).
"'"."' "
'. .
Water-table contours indicate that under natural conditions. groundwater flows
southeasterly toward Biscayne Bay. The hydraulic gradient is approXimately 0.3 ftfnille.
.
The water table at Homestead AFBgenera1ly is encountered within 5 to 6 feet of ~d
surface. but may occur at or near land surface during the wet season (May to ()ctober)~
Fluctuations of groundwater levels and local variations in the direction of groundwater
flow are due to several factors: (1) differences in.infiltration potential. (2) runoff from
paved areas. (3) water-level drawdown near pumping wells. (4) significant but localized
differences in lithology (e.g.. silt-filled cavities) and (5) drainage effects of canals and
water-level control strUctures.
Average annual recharge to the Biscayne Aquifer ranges from 37 to 38 inches. The mean
annual precipitation range is 58 to 64 inches. Evapotranspiration accounts for 20 inlyr of
discharge from the aquifer. Runoff to the sea comprises 15.5 inIyear. and pumping
accounts for approximately 3.7 inlyr of groundwater discharge in Dade County.
-5-
,
-------
Floridan Aquifer. Underlying the low-permeability sedimentS of the Tamiami
Formation and Hawthorn Group are the forrnations which constitute the Floridan Aquifer.
The Floridan Aquifer is made up of limestOnes and dolomites. It is under artesian
pressure and water levels in deep wells may rise 30 to 40 ft above ground surface.
Groundwater within these Miocene and Eocene age forrnations tends to contain dissolved
constituentS at levels significantly above those recommended for drinking water. In view
of the poor water quality and the depth of water yielding zones (800 to 900 feet bgs), the
Roridan Aquifer is of limited usefulness as a source of potable water supply in the study
area.
1.4
SITE GEOLOGY AND HYDROGEOLOGY
The stratigraphy of the shallow aquifer system as deterrnined from soil borings perforrned
during site investigations by Geraghty & Miller (G&M) and Montgomery WatSon
consistS of a surficial weathered Miami OOlite ranging in depth from 2 to 6 feet bgs. The
weathered limestOne consistS of a white to brown semi-consolidated oolitic limestOne.
TIlls strata is underlain by consolidated to semi-consolidated oolitic and coral limestOne
interbedded with coarse to fme sand and clayey sand layers and lenses down to the total
depth of borings (approximately 40 feet bgs). The land surface at Site S$-13 appears to
be limestone gravel flll
The Biscayne Aquifer is one of the most transmissive aquifers in the world. It underlies
Homestead AFB. A thin vadose zone, nominally less than 5 feet deep, overlays the
groundwater table at the site. As previously stated. the aquifer structure is a calcium
carbonate matrix. This lithology is known to have natural concentrations of target
analyte list (TAL) metals. In'descending order by concentration, calcium. aluminum,
iron magnesium. sodium. and potassium can be considered the primary metals of
carbonate rock. The other TAL metals occur in trace concentrations. less than 50
milligrams per kilogram (mglkg). The range and the standard deviations are not provided
at this time. It should be expected that. as precipitation inf1ltrates and recharge takes
place. leaching of metal ions from the weathered vadose zone and shallow unsaturated
zone occurs. Regional data collected suggest that concentrations of trace metals can be
expected to be the greatest in the shallow portion of the aquifer because of the proximity
to the source (i.e. the weathering vadose structure) and the decreasing retention time with
decreasing depth of the saturated zone. These observations support a hydrogeologic
model in which the shallow portion of the aquifer has a greater horizontal transmissivity
-6-
-------
. .
than the vertical component 'during~e e"ents. However~ it,is nQt ,possible from the
av.ailable data at ,the site to quanti~vely,diffe~tiatehorizontaland !ertical components
of the aquifer's hydrologic conductivity. The possible presence of vertical solution zOnes
is well documented in literature. The site-specific effects have not been fully
investigated. Neverth.eless~ the available data does not lead to the immediate conclusion
that this is a necessary taSk. The conceptual model that the shallow groundwater is
discharging at the local swell and ditches is valid for the purpose of discussiIig Site
SS-13.
2.0
SITE msTORY AND ENFORCEMENT ACTIVITIES
2.1
msTORY
2.1.2
Past Site Usage
The site history of the Civil Engineering Storage Compoun
-------
2.2
E1\"FORCEMENT HISTORY
2..2.1
CERCLA Regulatory History
The Comprehensive Environmental Response. Compensation and Liability Act of 1980
(CERCLA) established a national program for responding to releases of hazardous
substances into the environment. In anticipation of CERCLA. the Department of Defense
(DOD) developed the Installation Restoration Program (IRP) for response actions for
potential releases of toxic or hazardous substances at DOD facilities. Like the
Environmental Protection Agency's (EP A's) Superfund Program. the IRP follows the
procedures of the National Oil and Hazardous Substances Pollution Contingency Plan
(NCP). Homestead AFB was already engaged in the IRP Program when it was placed on
the National Priorities List (NPL) in August 30. 1990. Cleanup of DOD facilities is paid
for by the Defense Environmental Restoration Account (DERA). which is DOD's version
of Superfund.
The Superfund Amendment and Reauthorization Act (SARA). enacted iIl 1986. requires
the federal facilities follow NCP guidelines. The NCP was amended in 1990 (see 40
CFR 300 et seq.) to implement CERCLA under SARA. In addition. SARA requires
greater EP A involvement and oversight of Federal Facility Cleanups. On March 1. 199 L
a Federal Facility Agreement (FF A) was signed by Homestead AFB. the EP A. and the
Florida Department of Environmental Protection (FDEP). The FF A guides the remedial
designJ remedial action (RDJR-\) process.
Also in response to SARA was a revision of EP A's Guidance on Remedial Investigations
Under CERCLA (EPA. 1985a) and Guidance on Feasibility Studies Under CERCLA
(EPA. 1985b). The revised document entitled Guidance for Conducting Remedial
Investigations and Feasibility Studies Under CERCLA (EPA. 1988). released in October
1988 in Interim Fmal form. reflects the provisions of SARA as well as EPA's experience
from previous Remedial InvesrigationlFeasibility Study (RIlFS) projects.
As part of the RIIFS process. Homestead AFB has. been actively involved in the
Installation Restoration Program (IRP) since 1983 and has identified 27 Potential Sou.rt:es
of Contamination (PSCs). Nine sites are currently being investigated under the RIIFS
stage of CERCLA; ten sites are being investigated in the Preliminary Assessment/Site
Investigation (P NSI) stage of CERCLA; one site is being investigated under the
-.... .... -
Resource Conservation and Recovery Act (RCRA) guidelines: and seven sites are being
-8-
-------
investigated under theFDEP petroleum contaminated sites,,-criterla (Rorida,'
Administrative Code 17-770). ' The following PSCS are '~un:-endy being inyestig~
according to the CERCLA RIlFS guidelines:
FT-5
OT-ll
SS-13
SS-8
wp.-{
SS-3'
SS-7
FT-4
SD-27
FIre Protection, Training Area. 2
Residual Pesticide Disposal Area
,PCB Spill CE. Storage Compound
Oil Leakage Bebind the MOt()r Pool
a~plating Waste Disposal Area.
Aircraft Washrack Area
Entomology Storage Area
FIre 'Protection Training Area. 3
Boundary~taryCanal
As previously mentioned. on March 1. 1991. Homestead Air Force Base entered into a
FFA with the USEPA and the Florida Depment of EnvirOnmental Regulation (FDER) ,
, (agency is now named Florida Deparnnent of Ehvironment3..l Protection [FDEP]). The
purpose of this agreement was to establish a procedural framework: and schedule for
developing, implementing. and monitoring appropriate response actions at -Homestead
AFB in accordance with existing regulations. The FF A requires the submittal of several
,p$n~ -and ,~Qn.daff~~tocuments"foreachofthe operableutri.ts'at Homestead :AFB., '
This ROD concludes all of the RIJFS requirements for Site SS-13 and selects a remedy
for Operable Unit No.3.
2.3
INVESTIGA TIONHISTORY
2.3.1
IRP Phase I - Record Search
An IRP Phase I - Records Search was performed by Engineering Science, and is
summarized in their repOrt, dated August 1983 (Engineering Science. 1983). During the
Phase I study, sites with the potential for environmental contamination resulting from
past waste disposal practices were identified. Thineen sites of potential concern were
identified by reviewing available installation records. interviewing past and present
Homestead AFB employees. inventorying wastes generated and handling practices,
conducting field inspections. and reviewing geologic and hydrogeologic data. In general.
Phase I studies are used to determine if a site requires further investigation.
-9-
c.7
-------
The thirteen sites identified were ranked usmg the Hazard ~ssessment Rating
Methodology (HARM) developed by JRB Associates of McLean. Virginia.. for the
USEP A R-\.R.\1 was larer modified for application to the .Air Force IRP. The following
factors are considered in HARM: (1) the possible receptOrs of the contaminants: (2) the
characteristics of the waste; (3) potential pathways for contaminant migration; and (4)
waste management practices. HARM scores for the sites ranked at Homestead AFB
ranged from a high of 72 to a low of 7 out of 100. Eight of the 13 sites were determined
to have a moderare to high contamination potential. one of which was the Sire SS-13 PCB
S pill Area.
The IRP Phase I Report evaluated the PCB Spill. Civil Engineering Compound (Site
SS-13) and assigned the lowest HARM score of 7 based on criteria listed above and the
reported removal of the contaminated soil from the area.
2.3.2
IRP Phase II . ConfirmationJQuantification
A.n IRP Phase II study was performed by Science Applications International Corporation.
and was reported on in March 1986 (SAlC. 1986). Based on the low R>\RM score and
the prior removal of the contaminated soil. Site SS-13 was excluded from this study
phase.
2.3.3
IRP Phase In. Technology Base Development
.
The IRP Phase ill is a research phase and involves technology development for an
assessment of environmental impacts. There have been no Phase ill tasks conducted at
the Base to date.
2.3.4
IRP Phase IV . Additional Investigations
The IRP Phase IV investigations consist of two areas of work activity. Phase IV-A
involves additional sire investigations necessary to meet the Phase II objectives. a review
of all management methods and technologies that could possibly remedy site problems.
and preparation of a baseline risk assessment (0 address the potential hazards to human
health and the environment associated with the constituents detected at the site. Detailed
alternatives are developed and evaluated and a preferred alternative is selected. The
preferred alternative then is described in sufficient detail to serve as a baseline document
for initiation of Phase IV - B.
-10-
-------
Although an IRPPhaseIV.~A~investigati()n,W~Iiot'conducted at Site SS-13, a Phase
IV:A investigation was c9Ilducted in 19.88 at
-------
in the center of the reported spill area. A total of two soil samples J one sample and a
duplicate) were collected from a depth of 0 to 1 ft bls and submitted for analysis of
volatile organic compounds (VOCs), base neutral/acid extractable compounds (BNAs),
organochlorine (OC) pesticides/PCBs. metals. and cyanide. The four monitOring wells
sampled in 1991 were resampledduring the 1993 investigation. A tOtal of five
groundwater samples (four samples and a duplicate) were analyzed for VOCs, BNAs. OC
pesticideJPCBs. metals. and cyanide.
No PCBs were detected above laboratOry reporting limits in the soil samples from boring
SP3-SL-0006. No PCBs were detected above laboratOry reporting limits in the
groundwater samples collected at Site SS-13. Because Operable Dnit No.3 is defmed as
the PCB Spill Area and associated potential PCB contamination only, all other analytical
results from soil and groundwater samples will be incorporated into the ongomg
Remedia11nvestigation at Operable Dnit No.7, Entomology Storage A.rea.
The purpose of the RI Addendum was to evaluate the current soil and groundwater
quality with respect to the USEP A target compound list/target analyte list (TCUT AL)
and to fill data gaps from the previous field investigations.
An additional objective was to achieve lower detection limits for the PCB analysis than
those reported for the 1991 Rl, and thus, confirm that PCBs in site soils were effectively
remediated by the excavation previously performed at the site.
2.4
COl\~ruI\1TY RELATIONS IDSTORY
The Remedial InvestigationlBaseline Risk Assessment report and the Proposed Plan for
Homestead AFB Site SS-13 were released to the public in late 1993 and early 1994,
respectively. These documents were made available to the public in both the
administrative record and an information repository maintained at the Miami-Dade
Community College Library.
A public comment period was held from March 8, 1994 to April 22, 1994 as part of the
community relations plan for Operable Unit No.3. Additionally, a public meeting was
held on Tuesday, March 29, 1994 at 7:00 pm at South Dade High School. A public
notice was published in the Miami Herald on March 21, 1994. At this meeting, the
USAF, in coordination with EPA Region IV, FDEP, and Dade County Environmental
Resource Management (DERJ.\1), were prepared to discuss the investigation, results of the
-12-
-------
l::.. sP3-SLoOOO4
CE STORAGE
COMPOUND
;J
't!
'0
c
...
~
..
~
~
:1;
..
~
g
o
.c
~
.~
'0
Q.
";)
E
LEGEND
.
@
l::..
Jl
SHALLOW MONITORING WELL
GERAGHTY & MILlER 1991INVESllGA1l0N
DEEP MONITORING WELL
GERAGHTY & MILLER 1991 INVESi1GA i10N
SOIL BORING LOCA 1l0N
GERAGHTY & MILLER 1991INVESi1GA i10N
NEW SOIL BORING LOCA i10N
MONTGOMERY WATSON 1993INVESi1GAi10N
x
\
X
\ \
X.. <
o
\t
X 8
\ 0
w
\,1...
. .~
x
J
'X
x
50
I
o
I
APPROXIMATE SCALE
50
t
HOMESTEAD AIR FORCE BASE
FLORIDA
PCB SPILL AREA SITE 55-13
SOIL BORING AND MONITORING WELL LOCATION MAP
AGURE 2-1
-------
Baseline Risk Assessment., and~e No Action Alternative described ipthe Proposed 'Plan.
. ..' . .. )
A response to the comme~ts rece,iyed during this,peri~ is inCluded in the Responsiveness
Summary, which is part of this ROD.
This decision document presents the selected remedial action for Operable Unit No.3,
chosen in accordance with CERCLA, as amended by SARA and, to the extent
practigible, the NCP. The decision on the selected remedy for this site is based- on the
adniinistrative record.
2.5
SCOPE AND ROLE OF OPERABLE UNIT 3
Homestead AFB, Florida with concurrence from the State of Florida and USEP A, has
'. .
elected to define Operable Unit No.3 as the PCB Spill Area and associated potential PCB
contamination only. The remedial actions planned at each of the Operable Units at
Homestead AFB are. to the extent practicable. independent of one another. However.
with respect to Operable Unit No.3 and Operable Unit No.7 (Entomology Storage Area).
the close proximity of these two operable units has resulted in some physical overlap of
site boundaries~
PCBs have not been detected at Operable Unit No.3; however. elevated levels of metals,
,primarily ~nic, haveb~p~tected within the site-.boU1ldarles. Consequ~ntly,
additional sampling will be conducted in conjunction with the Entomology StOJ:age Area
(Operable Unit No.7) investiganon to determine the extent of arsenic contamination
throughout the area. Arsenic remediation. if necessary. will be conducted as pan of
Operable Unit No.7.
2.6
SITE CHARACTERISTICS
Site history of the Civil Engineering Storage Compound has been incompletely
documented and historical records are sparse. In the past., the area stOred transfonners
containing polychlorinated biphenyl (PCB) fluids. In 1981. a spill of PCB cont3wi~ted
(>50 and <500 ppm PCB) transformer fluid occurred immediately southwest of
Building 220 in the Civil Engineering Storage Compound (Figure 1~2). Less than 100
gallons of fluid was involved. Following the incident., the impacted soil was analyzed
and found to contain less than 50 ppm of PCB. Subsequently, the soil was removed and
disposed of at an off-base site. Infonnation on the volume of soils removed and a map
-13-
'"
)
if
-------
depicting the exact location of the excavation is not available. Howe'ler. soil boring logs
indicate an approximately 1 ft thick surficial layer of silty sand fill in the area of the
spill/excavation.
This section describes the nature and extent of contamination identified in the soil and
groundwater at Site SS-13. The nature and extent of contamination at Site SS-13 was
first investigated in 1991 by G&M. Additional soil and groundwater sampling was
conducted bv Montgomerv Watson in 1993. The investigations were conducted in
.. "-' .- "-
accordance with the approved Facility Remedial Investi[1.tion Work Plan and Work Plan
Addendum (G&M, 1991; G&M. 1993). The results of both investigations are discussed
below.
2.6.1
Nature and Extent of Soil and Unsaturated Zone Contamination
2.6.1.1 Prevjous Investigation. The 1991 investigation conducted by G&M included
the collection of ten soil/weathered rock samples from five borings (SP3-SL-OOOl
through SP3-SL-OO(5). The borings surrounded the reported spill area located southeast
of Building 220 (Figure 2-1). The borings were located outside the estimated perimeter
of the excavation to identify possible contamination that was not removed during
excavation activities.
Soil samples were collected from depths of 0 to 1 ft bIs and 1 to 2 ft bIs in each boring
and submitted for PCB analysis. No PCBs were present above laboratory reporting
limits. Soil analytical results for the 1991 investigation are summarized in Table 2-1.
2.6.1.2 Current Investigation. In the current investigation. one additional soil
boring (SP3-SL-0006) was drilled at Site SS-13 (Figure 2-1). The boring was located
within the reported spill area to confirm that excavation activities had removed the
PCB-contaminated soils. A total of tWo soil samples (one sample and a duplicate) were
collected from a depth of 0 to 1 foot bls and submitted for analysis of VOCs. BNAs. OC
pesticideslPCBs, metals. and cyanide. No PCBs were detected above laboratOry
reporting limits in the soil samples from boring SP3-SL-0006. Results of the PCB soil
analysis are presented in Table 2-2.
Because Operable Unit No.3 has been defmed as the PCB Spill .-\rea and associated
potential PCB contamination only, all other analytical results from sample SP3-SL-0006
1.Jf
- 1 "T-
-------
TAULE 2-1
SOIL ANAL Y'nCAt HESUtTS . I'cns
sIn; 8S-13 PCB SPiLl. C.E. STORAGE COMPOUND
GERAGHty & MILLER, 1991
Homestead Air Force Buse, Florldll
Anulytc
G&M Sample J.D.
Suvannah I.[).
Sampling Unle
SP3.S(.-OOOI.1
34885-21
. 7/26/91
8P3-SI..~OOOI-2
34885.22
7/26/91
SP3.SL.0002.1
34885-23
7/26/91
Sl'3.StA002.2
341185.24
7/26/91
81)3-81..0003- 1
348115-25
7/26/91
81'3.81..0003-2
341185-26
7/26/91
1»OJ.YCHLOIHNATED 8l1'III~NYLS (uglkg dw):
Aroclor-l016
Aroclor. 1221
ArocJor - 1232.
Aroclor. 1242
Aroclor. 1248
Aroclor - 1254
Aroclor. 1260
< 360 < 370 < 370 < 370 < 370 <370
<360 <370 < 370 < 370 < 370 < 370
< 360 ~ 370 < 370 < 370 < 370 < 370
< 360 < 370 < 370 < 370 < 370 < 370
< 360 < 370 < 370 < 370 < 370 < 370
<360 < 370 < 370 < 370 < 370 < 370
< 360 < 370 < 370 < 370 < 370 < 370
G,~M Sample I.D. SP3-8L.0004.1 81'3.81.-0004-2 SP3.SL.0005.1 81'3.81..0005-2 81»3.81.-9005- I
Analyte Savannah 1.0. 34885.27 34885.22 34885~28 34885.29 34885-30
Sampling Date 7/26/91 7/26i91 7/26/91 7/26/91 7/26/91
Aroclor.1016 <920 <21)0 <920 <960 <190
Aroc\or - 1221 <920 <200 <920 <960 <190
Aroclor - 1232 <920 <200 <920 <960 <190
Aroclor. 1242 <920 <200 <920 <960 <190
Aroclor - 1248 <920 <200 <920 <960 <190
Aroclor. 1254 <920 <200 <920 <960 <190
Aroclor. 1260 <920 <200 <920 <960 <190
All samples analyzed by Savannah Laboratories, Tallahasscc, Florida..
uglkg dw micrograms per kilogram dry weight
< Analylc was nOI detected. 11lc values given arc equal to the practical qttaniiiltion limis nnd may vary among samples
due 10 differences in water conlent, mass analyzed, and dilution factors. .
Source: Geraghty & Millcr,lne (Dru(t 1992)
, "
;.-,>...}
-------
TABLE 2-2
SOIL ANALYTICAL IU~SlJLTS . PCBs
SITE SS-t3 PCB SPILL C.E. STORAGE COMPOUND
MONTGOMEUY WATSON, 1993
I (omcstcacl Air' Force Base, Florida
Analyte Units S PJS 1.0006 J SP3SL9006J
Interval n,o. J.O ft n.o. J.O ft
PCB TCL Compounds
I'CB-I016 (Aroclor 1(16) (llg/kg) < 36 < 37
PCB. t 221 (Aroclor 122 t) (ug/kg) <73 < 74
PCB-1232 (Aroc1or 1232) (ug/kg) <30 < 37
PCB. t 242 (Aroclor t 242) (llg/kg) < 30 < 37
1>CB-1248 (Aroclor t 248) (lIg/kg) < 36 < 37
PCB. t 254 (Aroc1or t 254) (llg/kg) < .HJ < 37
PCB. t 260 (Aroclor 12(0) (lIg/kg) <30 < 37
1\11 samples analyzed by Savannah Laboratories. Tallahassee, Florida
< . not detected at specified detection limit
IIg/kg . microgram per kilogram
-------
and duplicate sample SP37SL~9006will ,be incorporated into th~ ongoing remedial
investigation at Operable Unit No. ':7. EIrtomology S~rage Area.
2.6.2
Nature and Extent of Groundwater Contamination
2.6.2.1 Previous Investigation. In the 1991 G&M investigation. a total of four
monitOring wells were installed at Site SS.;.13. Three of the wells were'constIU~inthe
. .
uppermost water-bearing zone beneath the site; a fourth was constructed in a deeper
water,.be.aring zone. Groundwater samples from the four wells were a.naIyzed for PCBs.
,. .
No PCBs were detected above laboratory reporting limits. Analytical resUlts for the 1991
groundwater samples ,are summarized in Table 2-3.
2.6.2.2 Current Investigation. " The four monitOring wells were re-sampled during
, .
the current investigation. A '~t9talof five groundwater samples (four samples and a
duplicate) were analyzed for VOCs.BNAs. OC' pesticideslPCBs. metals. and cyaqide.
No PCBs were detected above laboratory reporting limits. Results of the 1993 PCB
groundwa~ analyses are presented in Table 2-4.
Because Operable Unit No.3 has been defmed as the PCB Spill Area and associated
potential PCB contamination only, all other analytical results from groundwater samples
will,~ iJ1cOI.'PO~~iJ1~o,theongoing remedial investigCition~.,Opera.ble{J~t:NQ,,),
EntOmology Storage Area.
2.6.3
Potential Routes ofMi~on
CODt:iminants may migrate from a source area through a variety of processes. Volatile
contaminants may ~ released intO air and migrate in the vapor phase. Liquid or aqueous-
phase contaJninants may migrate to bOth soils and groundwater through direct infiltration.
Erosion related to surface runoff or wind may transport contaminants sorbed to surface
soils. Infiltrating precipitation may dissolve contaminants and carry them intO deeper
soils where they can be adsorbed. or into groundwater in the dissolved phase. Dissolved
phase contaminants may be carried in the down gradient direction by groundwater flow in
an aquifer.
. A tOtal of ten weathered rock/soil samples were collected during the 1991 investigation
from locations around the perimeter of the reported excavation area. One additional
-15-
~ ""
r\ "
j-
-------
TABLE 2.,)
(iIWIJNI>WATER ANALYTICALIU:..<;tJLTS. I'cn,
SITE SS.13I'CR SI'II.I. C.\<:, STORAGE COMI'O\IND
m;ltAGIIT\' & ~IILI.EH, 1991
IIrnnesh,," Air Filter \lnsf', HOli!!a
,\11"') ".
(i&1\1 Sample I,D.
SavAnnah J.D.
SlIlIIpllng Date
l-:'I',ll'menl IIInnk
3S 1-13 (\
&/12/91
SI'3.\)I\IW.0001
35143-1
&/12/91
81'3.I\IW.000I
JSIH-2
&/12/91
SI'J.I\IW.0002
.\5 J.tJ.J
&'12191
SI'.3.1\1 W.0005
J51-1:3.4
8/12J91
SI'.3.I\IW.ljH05
.15143.5
&'1219\
---_.
_*"'-h'v_~..~~--'
---~------~.w--
I'CJLYCIILoHINATED IIIPIlENYLS (IIWI.):
Arodl\r. 1251
<.0.50 <.0.50 d)5!) '/",I hy Savallnah I.ahoratories, S,wallllah. (Jel"!:la.
ur,n. mi('(()gl am~ pCI lite I
< Allaly1e wa.' lIot dekcled. 'Ihc valllcs given are c'IlIal to Ihe 1"'\l1kal 'IlIalllitalioll lirnits alld n~IY vary anlOllg 'ilfllpk\
dll~ to .lIffer,'lIcts ill (j\lantily anaIY/.c.<.\ and .liIlllion factr>!s.
SOllrr'(': (;\'Iaghly ,'I.i MlllfI', Inl" (Dnlf11991)
-------
TABLE 2.4
GROUN1>WATER ANALYTICAL RI;:SULTS. PC Us
SrrE SS.13 PCR SPILL C.R. STORAGE COMI)OUNI>
MONTG01\1rmy WATSON, J993
Homestead '~Ir Force IJase, Florldo
t\ nlllytc
Units SP3.DMW.OOOJ. SP3.MW.OOOJ
SP3~MW.0002 SN.I\1W.II005
SP3'.I\JW-900.
FlmEItAI.
MCt
SP3.EB-OOOI
FI.OltmA
MCL
pen TCL Compounds
PCB.IOI6 (Amdor 1016)
PCn.1221 (Aroelor 1221)
PCB-1232 (Aroelor 1232)
PCn.1242 (Aroelor 1242)
PCO.1248 (Aroelor 1248)
I'Cn-1254 (Aroelor 1254)
pcn.1260 (Aroelor 1260)
(U8/1.) <1.2 <1.1 <1.1 <1.1 <1.1 <1.2 0.5'" 0.5**
(ug/L) <2.3 <2.3 <2.2 < 2.2 < 2.2 < 2.5' 0.5" 0.5"
(ug/L) < 1.2 <1.1 <1.1 <1.1 <1.1 < 1.2 0.5" :0.5++ .
(lIg/l.) <1.2 <1.1 < 1.1 <1.1 < 1.1 < 1.2 0.5++ . 0.5**
(ug/t) < 1.2 <:1.1 <1.1 <1.1 <1.1 <1.2 0.5++ 0.5"
(lIg/L) < 1.2 <1.1 <1.1 <1.1 < 1.1 < 1.2 0.5" 0.5**
(lIg/L) <1.2 <1.1 <1.1 <1.1 <1.1 < 1.2 0.5'" 0.5++
all samples analyzed by Savannah Laboralories, Tallahassee. Florida
< . not detected :It specified detection limit
MCL. maximum conlaminantlcvc!
NE. nol established
* - value listed is for chlordane
... . vallie lisled is for lotal PeD
i "<..:
I'
-------
sample was collecred from within the reponed excavated area in the J 993 investigation.
lill samples were analyzed for PCBs; none were detecred.
A total of four groundwater monitoring wells were sampled during the 1991 investigation
at Sire SS-13. The four monitoring wells were resampled during the 1993 investigation at
Site SS-13. All samples were analyzed for PCBs. none were deteCted.
Based on PCB analytical results collected to date. the PCB spill at Operable Unit No.3
has been effectively remediated by the excavation activities and thus. migration via the
routes described above is not occurring.
2.6.4
Exposure Assessment
A critical step in assessing the potential risk to public health is to identify the pathways
through which exposure could occur. A typical transport pathway consists of four
necessary elements: 1) a source and mechanism of chemical release. 2) an environmental
transport medium. 3) a point of potential contact with the contaminated medium, and
4) an exposure route (inhalation of vapors, ingestion of groundwater, etc.). All four of
these elements must be present for a pathway to be complete.
As previously discussed, the analytical data collected by both Montgomery Watson in
1993 and by G&M in 1991 indicate no evidence of significant PCB-related
contamination at Operable Unit No.3.
Based on PCB analytical results collected to date, the PCB spill at Operable Unit No.3
has been effectively remediated by the excavation activities and thus, exposure via the
pathways described above is not occurring.
2.7
SUMMARY OF SITE RISK
2.7.1
Identification of Contaminants of Potential Concern
This section presents the analytical data collected during L~e RI and other previous
investigations that are used in the risk assessment, and on the basis of these data.
determines which compounds are responsible for the greatest risks at the site. Four wells
sampled by G&M (SP3-MW-0001, SP3-DMW-OOOl, SP3-MW-0002. and SP4-M\\T-5)
for analysis of PCBs were resarnpled by Montgomery \VatSon for analysis of PCBs, TCL
-16-
-------
pestici~ TCL volatile and TCL semivo1atile organic compoun~ and TAL metals. Ten
soil samples were collected by6~ inJ99l for analysis of PCB~. :Qne'surface soil
sample was collected by Montgomery Watson in 1993 for analysis of PCBs~ pesticides~
volatile and semivolatile organic compounds~ and metals. It should be noted that the
following evaluation of significance of chemical data is limited by the single sample for
soil. The risk analysis eliminates from consideration any data that indicate that a
compound is present within the range of 'natural background concentrations~ because a
compound present at these concentrations is probably not a contaminant released from
Site SS-13. In addition to the four wells sampled by G&M in 1991 andresampled by
Montgomery Watson in 1993~ one background groundwater sampl~ SP4-MW-5, was
collected in the Montgomery Watson sampling event. Five site-wide background soil
borings, SPll-SL-0028-2, P3-SL-0023~ P2-SL-0023-2~ SP3-SL-0004-1~ SP3-SL-0004-2
were collected during the G&M sampling event. In,addition, compounds were further
screened to determine frequency of detection, tOxicity, Le., whether the compound is an
essential nutrien~ a carcinoge~or a non-carcinoge~ and if the concentrations detected,at
the site are greater than levels reported in the sCientific literature. Reviewing all
compounds detected at the site and'selecting compounds of concemallows the risk
assessment to focus ona manageable list of the most important chemicals~ which in turn
permits concise analysis 'and' presentation.
2.7.2
Data Analysis
The analytical data for the 1993 risk assessment were collected by G&Mduring 1991 and
by Montgomery Watson during 1993. G&M performed laboratory analyses and data
validation for their field samples; Montgomery Watson performed, its own data
va1idatio~ which is to be reported in an Internal Draft Quality Control Summary Report.
while Savannah Laboratories performed the laboratory analyses. All data collected by
G&M and Montgomery Watson was used in this risk evaluation. This includes a review
of detec~ detection limits for non-detects~ and estimated (J-qualified) data. Detection
limits reported for Montgomery Watson samples were in compliance with contract
laboratory protoCol statement of work (CLP SOW) required deteCtion limits.
2.7.2.1 Soil. As stated above. both the G&M and Montgomery WatSOn data sets were
used in the risk assessment. Ten soil samples were collected by G&M in 1991 for
analysis of PCBs. One surface soil sample was collected by Montgomery WatSOn in
1993 for analysis of PCBs. TCL pesticides. TCL volatile and TCL semivolatile organic
compounds and TAL metals. The Montgomery Watson results confirm the earlier
-17-
',1
",
-------
findings of no PCBs in soil at detection limits of 36 to 73 micrograms per kilograms
(Jlgfkg) (ppb), depending on the PCB isomer, which improved upon the detection limits
for PCBs in soil previously reported by G&.\1.
2.7.2.2 Groundwater. Four wells sampled by G&M for analysis of PCBs were
resampled by Montgomery Watson for analysis of PCBs, pesticides. volatile and
semivolatile organic compounds, and metals. The Montgomery Watson results confIrm
the earlier fmdings of no PCBs in groundwater at detection limits of 0.5 to 2.0 microgram
per liter (J1g1L) (ppb). No pesticides were detected in groundwater samples at detection
limits of 0.056 Jlg/1 to 5.8 Jlg/1 (ppb), depending upon the compound.
2.7.3
Compounds of Concern Selection Process
The compounds of concern selection process determines those chemicals that are most
toxic and that are anticipated to create the greatest potential risk. However. analytical
results indicate no evidence of significant PCB related comarnination at Operable
Unit No.3.
It should be noted that several metals (aluminum, a..~enic. copper, iron, lead. manganese.
mercury, potassium. and zinc) were detected at levels above site background in the single
soil sample and its duplicate collected by Montgomery Watson in 1993. Of these metals,
only arsenic was detected at levels outside of any of the reference values presented in
Table 2-5.
The potential public health significance of the elevated metals in the soil warrants further
risk assessment. This metals data as well as all other soil and groundwater data (other
than PCB data) 'Will be incorporated into the ongoing investigation of Operable Unit No.
7, Entomology Storage Area.
2.7.4
Potential Routes of Migration
Contaminants may migrate from a source area through a variety of processes. Volatile
contaminants may be released into air and migrate in the vapor phase. Liquid or aqueous-
phase contaminants may migrate to both soils and groundwater through direct infiltration.
Erosion related to surface runoff or wind may transport contaminants sorbed to surface
soiis. Infiltrating precipitation may dissolve contaminants and caITY them into deeper
soils where they can be adsorbed. or into groundwater in Lhe dissolved phase. Dissolved
-18-
-------
:.
TABLE2-S
BACKGROUND SOIL CONCENTRATIONS
Compound
Homestead AFB Typical Values
Background. for Uncontaminated Common
SoiI(a) Soils (b) Range(c) A verage(c)
0-2 ft bls (mglkg) (mglkg) (mglkg)
738.55 0.01 - 13 forest (d)
0.01 - 1.01 rural
0.06 - 5.8 urban
8 - 336 road dust
126
2400 700 ->10.000 57000
<28 - 30 0-30 2 - 10(e) -(e.f)
1.6 0-30 <0.1 - 73 7.4
42.9 0-500 10 - 1.500 420
<2.8 - 2.9 0-5 <1-7 0.85
<2.8 - 3.0 0-1 0.01 - O.I(e) . O.06(e)
345,000 10 - 28,000 630
11.5 0 - 100 1-'1000 52
. ~ ...
<1.1 - 1.2 7 <0.3 - 70 9:2
<2.7 - 3.0 30 <1 - 700 22
1650 10 - 10.000 2.500
4.05 0-500 <10 - 300 . 17
1050 0-500 5 - 5.000 460
23 0 - 500 <2 -7.000 640
0.014 0-1 «).01 - 3.4 0.12
<4.5 - 4.7 15 <5 - 700 18
<110 - 120 5 - 3,700 -(f) :
<5.6 - 5.7 0-1 <0.01 - 3.9 0.45
<1.1 - 1.2 0.15 0.01 - 5.O(e) O.05(e)
555 <500 - 50.000 7,800
<1.1 - 5.6 22 - 23 8.6
<5.7 - 5.9 0 - 100 <7 - 300 66
20 60 <5 - 2.900 5.2
Total P AHs (Jlg/kg)
Total Phthalates (Jlglkg)
Metals (mg/kg)
Aluminum
Antimony
Arsenic
Barium
Beryllium
Cadmium
Calcium
Chromium
CObalt
Copper
Iron
Lead
Magnesium
Manganese
Mercury
Nickel
Potassium
Selenium
Silver
Sodium
Thallium
Vanadium
Zinc
(a) Source: Based on 5 background samples as reponed in Geraghty & Miller. 1992.
(b) Soutce: Gas Resea.-d:llnstitUte. 1987.
(c) U.S. Geological Survey Professional Paper 1270. Element Concentt3lions in Soils and Other Surficial M31eriai of !be Conterminous
United St:I1eS ?age 4. Table 1 (unless indicated othe:w1se).
(d) Source: Menzie. et al.. 1992.
(e) Data for t.b= metals Wclc not included in !be USGS P:lper. Concentrations Wclc obtained from me USEPA
Office of Solid Waste a.nd Emergency Response. Hazardous Waste Land Trea.:menl. SW -874. April 1983. Page In. Table 6.45,
(f) Average not eStablished
."
(/:;1.; ,,:.r.:'
-------
phase conniminants may be ~edin.the.downgradient direction by groundwater flow in
an aquifer. Migration via any ot$esepotential pathw~ys is affectecll;>y the fate and
transport mechanisms previously discussed.
Based on PCB soil analytical results collected to date, the PCB spill at Operable Unit No.
3 has been effectively remediated by the excavation activities and thus. migration via the
routes described above is not occUrring. .
2.7.5
Exposure Assessment
An exposure assessment is conducted to identify potential sources and mechanisms of
release, transport pathways (e.g. ground water, surface water, soil. and air), routes of
exposures (ingestion, inhalation, dermal contact), and potential on-site and off~site
receptor populations (current users of the site, as well as adjacent populations which may
be exposed to chemicals that have been transported off-site). This infonnation provides
the basis for constructing site-specific exposure scenarios.
Other information considered in the development of present and future exposure
scenarios includes: physical characteristics of the site and surrounding area such as
cliniatology, groundwater hydrology, location and description of surface water and .
surrounding land use and available state-specific guidelines relevant to exposure and risk
assessments.
A critical step in assessing the potential risk to public health is to identify the pathways
through which exposure could occur. A typical transport pathway consists. of four
necessary elements: 1) a source and mechanism of chemical release, 2) an
environmental transport medium, 3) a point of potential contaCt with .the conniminated
medium, and 4) an exposure route (inhalation of vapors, ingestion of groundwater, etc.).
All four of these elements must be present for a pathway to be complete.
As previously discussed the analytical data collected by both Montgomery Watson in
1993 and by Geraghty & Miller in 1991 indicate no evidence of significant PCB-related
contamination at Operable Unit No.3. Several metals, in particular arsenic, were
detected in concentrations above site background. The limited soil data (one surface
sample and duplicate) available at this time limits the usefulness of perfonning full risk
assessment calculations until further verification and extent can be detennined. Operable
Unit No.3 is defined as the PCB Spill Area and associated potential PCB contamination
only; therefore, the arsenic detection will be evaluated in the RIlBRA for Operable Unit
No.7. Entomology Storage Area.
-19~
,
t
1-:1
f
-------
Based on PCB analytical results collected to date, the PCB spill at Operable Unit No.3
has been effectively remediated by the excavation activities and thus exposure ....ia the
pathways described above is not occurring.
2.7.6
Toxicity Assessment
This section of the baseline risk assessment provides infonnation on the human health
effects of site-~pecific contaminants of potential concern. Additional infonnation
considered in this section includes physical and chemical characteristics that influence
fate. mobility, and bioaccumulative potential. The infonnation presented in this section
provides a basis for the dose-response assessment carried out in the quantitative risk
assessment.
Evaluation of the tOxic potential of a chemical involves the examination of available data
that relate observed toxic effects to doses. Generally, there are two categories of
information that are considered in this part of a quantitative risk assessment:
.
Infonnation on the potential for chemicals to initiate or promote cancers;
Infonnation on the potential acute or chronic non-<;ancer effectS of chemicals;
.
Much of this infonnation would be included in detail in toxicological profiles created for
the risk assessment.
A wide variety of factOrs must be considered in using health effectS data in qualitative or
quantitative assessments. As discussed in the following subsections. there may be a
variety of relationships between dose and effects. Also. the fact that some chemicals
display thresholds (i.e., there are doses below which the chemical does not cause an
effect) must be considered. In general. non-<;arcinogenic (acute or chronic systemic)
effects are considered to have threshold values, while carcinogenic effects are considered
not to have thresholds. Toxicity studies for the fonner focus on identifying where this
threshold occurs. The threshold can be related to a reference dose (RID). A chronic RID
is an estimate of a daily exposure level for which people, including sensitive individuals.
do not have a11 appreciable risk of suffering significant adverse health effects. Exposure
doses above an RID could possibly cause health effects. Studies of carcinogenicity tend
to focus on identifying the slope of the linear portion of a curve of dose versus response.
A plausible upper-bound value of the slope is called the slope factOr (SF) or cancer
potency factOr (CPF). The product of the SF and Lhe exposure dose is an estimate of the
-20-
-------
risk of developing cancer. In accordance with 'current scientific,policy concerning
carcinogens. it is assumed that any" dose. :n.o matter how small. has .some associa~
response. This is called a non-threshold effect. In this assessment, the no-threshold
effect was applied to all probable carcinogens. EP A has classified carcinogens with
regard to the epidemiologic and toxicologic data available.
As previously discussed the analytical data collected by both Montgomery Watson in
1993 and by G&M in 1991 indicate no evidence of significant PCB-related
contamination at Operable Unit No.3. Several metals. in particular arsenic. were
. .
detected in concentrat:ions above site background. The limited soil data (one surface
sample and duplicate) available at this.time limits the usefulness of performing fuJ,I: risk
assessment calculations until further verification and extent can be determined. Operable
Unit No.3 is defmed as the potential:PCB Spill Area and associated potential'PCB
contamination only; therefore. the arsenic detection will be evaluated in the RIlBRA for
Operable Unit No.7, EntOmology Storage Area
Based on PCB analytical results collected to date. the PCB spill at Operable Unit No.3
has been effectively remediated by the excavation .activities and thus the need for a .
quantitative risk a.ssessDient is eliminated. .
2.7.7
RiskCharacteriza~on
This section of the baseline risk assessment describes how calculated exposure doses are
.
converted into health risks. This section characterizes risks as part of a quantitative. risk
assessment for the site. Risk characterization involves the mregration of health effects
information developed as pan of the dose-response assessment with exposure estimates
developed as pan of exposure assessment. The result is a quantitative estimate of chronic
and non-carcinogenic risks based on the presumption that a threshold dose is required to
elicit a response. as well as a quantitative estimate of carcinogenic risks presumed to exist
regardless of the dose. These estimates are usually presented in either probabilistic terms
(e.g.. 1 in one million), or with reference to specific benchmark or threshold levels.
Because risk estimates are based on a combination of measurements and assumptions, it
is important to provide info~ation on sources of uncenainty in risk characterization.
The key elements of risk characterization as described below are: an estimation of human
dose, an estimation of risk, a presentation of risk. and an uncertainty analysis.
-21-
,
U~
-------
As previously discussed the analytical data collected by both Montgomery Watson in
1993 and bv G&M in 1991 indicate no evidence of sienificant PCB-related
- ~.
contamination at Operable Unit No.3. Several metals. in particular arsenic. were
detected in concentrations above site background. The limited soil data (one surface
sample and duplicate) available at this time limits the usefulness of performing full risk
assessment calculations until further verification and extent can be determined. Operable
Unit No.3 is defined as the potential PCB Area and associated potential PCB
contamination only; therefore. the arsenic detection will be evaluated in the RI/BRA for
Operable Unit No.7. Entomology Storage Area.
Based on PCB analytical results collected to date. the PCB spill at Operable Unit No.3
has been effectively remediated by the excavation activities and thus the need for a
quantitative risk assessment is eliminated.
2.7.8
Ecological Risk
This section addresses the ecological risks to plants and animals potentially affected by
contaminants at Homestead AFB: The area surrounding Homestead AFB is characterized
by diverse and rich biological habitats that support a wide variety of plants and animals.
Site SS-13 is located directly north of Operable Unit No.7 and west of Biggs Street. and
is a small area adjacent to a storage building where PCBs containing transformers were
previously stored.
An environmental assessment addresses the potential impacts and risks associated with
existing conditions at Homestead AFB. It provides a qualitative and quantitative
evaluation of the current and future risks represented by the present site conditions. A
variety of methods are employed to examine the impacts and risks to the terrestrial and
aquatic components of the system.
The specific objectives of an assessment include the following: identify species that may
be exposed to site-related compounds: select endpoints of concern; identify the ecological
exposure pathways; measure or estimate exposure point concentrations: develop
information on the chemical's toxicity; characterize the emironmental risks associated
with the exposure under curreIft and future conditions: assess the uncertainties associated
with u'1e estimates: and. discuss the ecological significance of the findings. The
qualitative assessment is a broad. cursory evaluation of risks to all ecological life in
conjunction with a focused assessment of significa..."1t ecological concerns.
-22-
-------
~e Environmental Assessment uses a "weight.of evidence" appr.o~h which includes
direct field observations, selected field and.laboratOry studies., and evaluation of chemical
. ""'.- " ;. . , .' . .~.
analytical data relative to environmental benchmarks. When integrated into the overall
assessmen~ these methods provide a peISpeCtive on the nature of ecological risks at a site.
In the early spring of 1993. G&M prepared an Ecological InventOry for Homestead Air
Force Base (G&M, 1993). TlUs inventory provided identification and characterization of
biotic communities and the associated flora and fauna at or near the base sites. Site SS-
13 is characterized as a composite of deteriorating asphalt and concrete pavementS.
compacted din and gravel, bare limerock' and a scattered, discontinuous covering. of
weeds. such as white beggar ticks. button weed, tridax (Tridax procumhens). and ,blue
porterweed (Stachytarpheta jamaicensis). ,Hunicane Andrew struck Homestead AFJ.:3 in
August 1992, before the ecological invelltory was conducted. This site has been
developed for use in base operations. thus buildings and asphalt paving have replaced
natural habitat. The hunicane destroyed Building 220. a former civil engineering storage
area. Subsequent to the hurricane. this area was used as a staging/storage area for
salvageable materials and equipment for the entire base~ The materials are stored in the
unpaved area of the site. This operable unit is defined as the PCB spill only. therefore,
elevated levels of other contaminants in soil are evaluated in the Remedial
InvestigationlBaseline Risk Assessment for Entomology Storage Area, Site SS-7. The
biologist ~onduc,ted.no,shovel,dig within this ,unit because ,pavementand,gravel,(tO,
bedrock) characterized this area. Thus. site impacts to ecological receptOrs are expected
to be minimal.
As previously discussed the analytical data collected by both Montgomery Watson in
1993 and by G&M in 1991 indicate no evidence of significant PCB-related
contamination at Operable Unit No.3. Several metals. in particular arsenic, were
detected in concentrations above site background. Operable Unit No.3 is defined as the.
potential PCB Spill Area and associated potential PCB contamination only; therefore the
arsenic detection will be evaluated in the RIlBRA for Operable Unit No.7, Entomology
StOrage Area.
Based on PCB analytical results collected to date, the PCB spill at Operable Unit No.3
has been effectively remediated by the excavation activities and thus the site poses no
significant ecological risk.
-23-
! t
~.
-------
2.8
DESCRIPTION OF THE "NO ACTION" ALTERN A TIVE
Based on PCB analytical results collected to date, the PCB Spill Area is free of PCB
contamination and therefore warrants a No Action ROD to close out Sire SS-13.
-24-
-------
-.
..' .~ ,- -~ .
'I
Homestead Air Force Base, Florida
Operable Unit 3 .
S'ite SS-13,PCB S'pill Area
Responsiveness Summary for the
Record of Decision
!t;jl
Li/~:; ..'
, .>:' /'ilJ" /
,(; .,-'.>
..........._...._-.~~M.,__.._._.~~
-------
j;,.
. REsPONS!VENEsSSUMMARY
FOR THE
RECORD OF DECISION
The responsiveness summary"SerVes tbreepurposes. First, it provides regulators with
information about -the co~Unity 'preferences regarding both the remedial alternatives
and general concerns about Operable Unit No.3. Homestead AFB. Second. .the
responsiveness summary documents how public comments have been considered and
integrated into the decision'lI':akingprocess. Third. it,providesEPA with the opp0J:!mrity
to respond to eacp comment'Submitted by the public on the record.
The Remedial InvestigatiorilBaseline Risk Assessment' report and the Proposed' Plan for
Homestead AFB Site SS;.13 were released to the public in late 1993 and .early 1994.
respectively. These documents were made available to the public in::both the.
administrative record and an information repository maintained at the Miami-Dade
Community College Library.
. .'
"
~ ~>,...
. ~.": ," of ..
A public comment period was held from March 8. 1994 to April 22. 1994 as part of the
community relations plan for Operable Unit No.3. Additionally. a public meeting was
held on Tuesday, March 29, 1994 at 7:00 pm at South Dade High SchooL A public
notice was published in the Miami Herald on March 21. 1994. At this meeting. the
USAF. in coordination with EPA Region IV. FDEP. and DERM were prepared to discuss
. .
the investigation. results of the Baseline Risk Assessment, and the No Action Alternative
described in the Proposed Plan.
No comments were received during the public comment period and no comments were
made at the public meeting regarding the proposed No Action Alternative at Operable
. . Unit No.3.
-1-
~L
------- |