PB95-964004
EPA/ROD/R04-95/200
December 1994
EPA Superfund
Record of Decision:
Anaconda Aluminum/Milgro
Electronics Site, Miami, FL
11/22/1994
-------
Record of Decision
Summary of Remedial Alternative Selection
Anaconda Aluminum/MlIgo Electronics Site
Miami, Florida
Prepared by:
U.S. Environmental Protection Agency
Region IV
Atlanta, Georgia
-------
DECLARATION FOR THE
RECORD OF DECISION
SITE NAME AND LOCATION
Anaconda Aluminum/Milgo Electronics Site
Miami, Florida
STATEMENT OF BASIS AND PURPOSE
This decision document presents the selected remedial action
for the Anaconda Aluminum/Milgo Electronics Site in Miami,
Florida. The remedy for the site was chosen in accordance with
the Comprehensive Response, Compensation, and Liability Act of
1980 (CERCLA), as amended by the Superfund Amendments and
Reauthorization Act of 1986 (SARA) 42 U.S.C. Section 9601
et.secr., and to the extent practicable, the National Contingency
Plan (NCP), 40 CFR Part 300. This decision is based on the
administrative record file for this site.
In accordance with 40 CFR 300.430, the State of Florida, as
represented by the Florida Department of Environmental Protection
(FDEP), has been the support agency during the Remedial
Investigation process for the Anaconda Aluminum/Milgo Electronics
site. Based upon comments received from FDEP, EPA anticipates
that concurrence on this Record of Decision will be forthcoming;
however, EPA has not yet received a formal letter of
nonconcurrence.
.DESCRIPTION OF THE SELECTED REMEDY
This remedy applies to site-related soil and groundwater
contamination. Due to past soil remediation and the presence of
low concentrations of groundwater contaminants that do not exceed
health-based levels, no further action is necessary to address
the Anaconda/Milgo Site. Four post-RI supplemental sampling
events will take place in order to verify that no site-related
release of contaminants is occurring. As of the writing of this
Record of Decision, one post-RI sampling event had already been
completed and indicated that the original contaminants found
during the RI were no longer present on the site. If the results
of the monitoring show that there is no unacceptable risk from
exposure to site-related contaminants in the groundwater, then
the site will be considered for deletion from the National
Priorities List (NPL). However, should groundwater monitoring
indicate that the site poses a threat to human health or the
environment, EPA, in consultation with the State of Florida, will
reconsider the protectiveness of the "No Action with Monitoring"
alternative and the feasibility of groundwater remediation will
-------
be re-evaluated.
DECLARATION STATEMENT
Based on the results of the Remedial Investigation and Risk
Assessment conducted for the Anaconda Aluminum/Milgo Electronics
Site, EPA has determined that no further action is necessary to
ensure the protection of human health and the environment, and
that the selected remedy is protective of human health and the
environment. The five-year review will not apply to this action
because this remedy will not result in hazardous substances
remaining on-site above health-based levels. EPA has determined
that with the exception of supplemental groundwater sampling, its
response at this site is complete. Therefore, the site now
qualifies for inclusion on the Construction Completion List.
Richard D. Green, Associate Director
Office of Superfund and Emergency Response
Date
-------
TABLE OF CONTENTS
1.0 SITE NAME, LOCATION, AND DESCRIPTION 1
2.0 SITE HISTORY AND ENFORCEMENT 1,3
3 .0 HIGHLIGHTS OF COMMUNITY PARTICIPATION 3,4
4 . 0 SCOPE AND ROLE OF OPERABLE. UNIT 4
5.0 SUMMARY OF SITE .CHARACTERISTICS
5 .1 CLIMATE 4
5.2 SURFACE HYDROLOGY 4,6
5 . 3 GEOLOGY AND HYDROGEOLOGY 6
5.4 RESULTS OF THE REMEDIALINVESTIGATION .6,7,13
6 . 0 SUMMARY OF SITE RISKS 13
6 .1 CONTAMINANTS OF CONCERN 14
6.2 EXPOSURE ASSESSMENT 14,15
6.2.1 LAND USE 15
6.3 TOXICITY ASSESSMENT « 15,16
6 .4 RISK CHARACTERIZATION 16 , 19
6 .5 ENVIRONMENTAL ASSESSMENT 19
7 . 0 DESCRIPTION OF THE ALTERNATIVE 20
8 . 0 DOCUMENTATION OF SIGNIFICANT DIFFERENCES 20
LIST OF FIGURES AND TABLES
FIGURE 1, SITE MAP 2
FIGURE 5-1, SURFACE DRAINAGE 5
FIGURE 5-2, SOIL SAMPLING LOCATIONS/ANACONDA 8
FIGURE 5-3, SOIL SAMPLING LOCATIONS/MILGO 9
FIGURE 5-4 , MONITORING WELL LOCATIONS 10
FIGURE 5-5, SEDIMENT SAMPLING LOCATIONS 11
TABLE 5-1, CONTAMINANTS OF POTENTIAL CONCERN .12
TABLE 5-2, SUMMARY OF CANCER AND NONCANCER RISK (CURRENT). 16
TABLE 5-3, SUMMARY OF CANCER AND NONCANCER RISK (FUTURE).. 17
-------
DECISION SUMMARY FOR THE RECORD OF DECISION
ANACONDA ALUMINDM/MILGO ELECTRONICS SITE
MIAMI, FLORIDA
1.0 SITE NAME, LOCATION. AND DESCRIPTION
The Anaconda Aluminum/Milgo Electronics (Anaconda/Milgo)
Site is located in Dade County in the 3600 block of N.W. 76th
Street in Miami, Florida. The Anaconda/Milgo site is
approximately 3 acres of land along the north and south sides of
N.W. 76th Street, the portion on the north is the Milgo property
and the portion on the south is the Anaconda property (Figure 1).
There are two sites in the area that the Florida Department of
Environmental Protection (FDEP) has in the past or is currently
investigating for possible releases of hazardous substances. One
site is 700 feet due east of Anaconda/Milgo and is under
investigation for Volatile Organic Compounds (VOCs) in the soil
and groundwater. The second site is approximately 2500 feet
northwest of Anaconda/Milgo and has been investigated for
polychlorinated biphenyls and VOCs in soil and-groundwater. The
site area is zoned commercial/industrial; however, a trailer park
lies due east of the site between Anaconda/Milgo and one of the
sites that is under investigation by FDEP.
2.0 SITE HISTORY AND ENFORCEMENT ACTIVITIES
• i
Anaconda Aluminum Company operated an /aluminum anodizing
facility on the Anaconda property from approximately 1957 to
1977. The Atlantic Richfield Company acquired the Anaconda
Aluminum Company in 1977 and operated the facility until February
1982, when all processes ended and the Anaconda property was sold
to the current owner, Dade Metals Corporation in October 1983.
The property was used for storing lumber and rebar by a tenant,
JRD Forming Company. JRD is no longer a tenant and the property
is currently not in use. The aluminum anodizing operations
utilized an electrochemical processing acid and a caustic base to
produce a film of protective oxide on aluminum. Wastewater from
the process was discharged into an onsite percolation pit,
permitted by the Metropolitan Dade County Environmental Resources
Management (issued May 17, 1979). The percolation pit was filled
in when the facility ceased operations.
Milgo Electronics, producers of communications and data
processing equipment, conducted electroplating, manufacturing,
painting, and packaging operations at the Milgo property from
1961 until 1984. Wastewater from chemical rinses, metal plating,
and spray coating were treated onsite in a treatment system
designed to precipitate dissolved metals from the wastewater.
-------
LEGEND
I PROCESS WASTEWATER
I TREATMENT AREA
PROBABLE LOCATION OF
PERCOLATION .PIT
r
ELGIN WATCH CO.
DOUBLE-WALLED
/BARRIER
MILGO ELECTRONICS
D
MW 76TH STREET
DESK
CONCEPTS
KING METAL
FABRICATION
o
IE
ANACONDA
ALUMINUM
•
SUSPECTED/
IMPOUNDMENT
GANG NAIL SYSTEM
ABANDONED
TREATMENT
STRUCTURES
SITE LAYOUT
ANACONDA/MILGO SITE
MIAMI, FLORIDA
FIGURE NO. i
-------
The precipitated sediment was removed by a tank truck and the
remaining liquid was discharged to a drainfield on the property.
Racal-Datacom, Inc. became the successor to Milgo Electronics
Corporation. The Milgo facility was closed in 1984 and 1985 in
accordance with a closure plan approved by the Florida Department
of Environmental Regulation. As part of the closure, the
drainfield, batch waste holding tank, and all process vessels
were drained and their contents disposed of at approved sites.
Preliminary and expanded site investigations determined that
there was potential impact to the environment by inorganic
contaminants, in particular chromium, lead, and aluminum. The
site was placed on the National Priorities List (NPL) in August
of 1990. General and Special Notice Letters were sent out
beginning in August of 1991 and ending in April of 1992. The
Administrative Order by Consent for the Remedial
Investigation/Feasibility Study (RI/FS) was signed on July 31,
1992 and later amended in November of 1992. Additional sampling
was conducted prior to the RI/FS and based upon these results, a
removal action was conducted in 1993 to remove a significant
portion of the contamination at the site. The removal activities
addressed soil and treatment structures known to contain elevated
levels of metals and organics and included; removal of liquids
and sludge from the settling tank, drainfield, batch tank, and
underground circular structure and sump with the liquid and
sludge being pumped into 55 gallon drums for disposal at an
approved offsite location, the testing of the sump (no leakage
was observed other than the exit pipe) , decqntamination and
removal/filling of structures with cement scurry, and finally
excavation of the drainfield to a 6-7 foot depth below land
surface in a 50 foot long by 7 foot wide trench. Post-removal
sampling results indicated that the removal was successful.
3.0 HIGHLIGHTS OF COMMUNITY PARTICIPATION
Community interviews were conducted by EPA in January 1993
to determine public interest in the Anaconda/Milgo site. The
conclusion drawn from these interviews is that there is minimal
interest in the Anaconda/Milgo Site, probably due to the heavy
industrial setting around the site. EPA held an Availability
Session at the North Central Library on January 21, 1993 to
provide information and answer questions on the interim removal
action and the RI/FS to be conducted at the site. Three
residents attended and indicated an interest in learning more
about the site, including the impact the site would have on
drinking water supplies, and questions about the Superfund
process. Minimal questions were raised regarding site-related
health and/or environmental concerns.
The RI, Risk Assessment, and Proposed Plan for
Anaconda/Milgo Site were released to the public in March of 1994.
-------
These documents were made available in both the administrative
record and at the information repository maintained at the EPA
Records Center in Region IV, Atlanta, Georgia and at the North
Central Library in Miami, Florida. The notice of availability
for these two documents was published in the Miami Herald. A
public comment period was held from September 19, to October 18,
1994. In addition, a public meeting was held on September 29,
1994 in Miami, Florida which no one attended. As mentioned
earlier, this is probably due to the fact that the site area is
heavily industrial. The decision for this site is based on the
administrative record. These community relations activities
fulfill the statutory requirements for public participation
contained in CERCLA section 113(k)(2)(B)(i-v) and section 117.
4.0 SCOPE AND ROLE OF OPERABLE UNIT
During the initial stages of negotiations, the
Anaconda/Milgo site was divided into three operable units (an
operable unit for soil at each property location and one operable
unit to address groundwater at both properties). However,
subsequent to these negotiations, all three operable units were
combined into one for the purpose of the RI/FS and Baseline Risk
Assessment activities. The response action in this ROD is for
all three operable units at the Site. Extensive cleanup efforts
during the removal action and results of the Risk Assessment,
suggest that if no further action were taken at this site,
present site conditions would be protective ,of human health and
the environment. The response actions are Consistent with the
NCP (40 CFR Part 300). /
5.6 SUMMARY OF SITE CHARACTERISTICS
5.1 CLIMATE
Miami is located in South Florida in an area dominated by
tropical air masses. The average annual temperature is 76°F; the
average low annual temperature is 68°F. The average annual
precipitation for the area is 56 inches. Surface meteorological
data obtained from the Miami International Airport indicate a
general east to southeasterly flow of air in this region.
5.2 SURFACE HYDROLOGY
Figure 5-1 displays potential surface drainage patterns on
and near the site. Surface drainage consists of sheetflow from
building and the asphalt/concrete paved areas that make up the
majority of the site. This flow discharges to box drains on site
-------
- ABANDONED
TREATMENT
STRUCTURES
SD-OJ
SO-04
S0-t5
0 50 100
I I I I I
SCALE
LEGEND
AREA OF STORMWATtR
ACCUMULATION
Figure 5-1
Site Drainage
Anaconda/Milgo Site
Miami, Florida
-------
and catch basins along the roadway. It is uncertain whether or
not the catch basins are components of a municipal stormwater
drainage system or merely parts of a local infiltration device.
Stormwater accumulation was observed in two areas along the
eastern portion of the site. Accumulated water in these areas
would typically evaporate and/or infiltrate within 24 hours of a
storm event. The nearest surface water bodies are the Little
River Canal which lies approximately 1.5 miles north of the site
area and the Miami Canal which lies approximately 2 miles south
of the site area.
5.3 GEOLOGY AND HYDROGEOLOGY
The following surficial and lithologic units occur in
southeast Florida in the vicinity of the Anaconda/Milgo site and
are given in order of youngest to oldest: the Recentage Lake
Flirt Marl, the Pamlico Sand, the Miami Oolite , the Anastasia
Formation, Key Largo Limestone, the Pleistocene units, the
Pliocene Caloosahatchee Marl, the Miocene age Tamiami Formation,
and the Hawthorn Group. The sands, sandstone, and limestone
beneath the site form part of the Biscayne Aquifer, the primary
drinking water source in Broward and Dade Counties. The aquifer
is thickest near the coast and it thins and pinches out in the
western reaches of Dade and Broward Counties. The aquifer is
comprised primarily of unconsolidated quartz sands in
approximately the upper 50 feet and it becomes more calcareous
and consolidated with depth. Below a depth of 75 feet the
aquifer is comprised of semiconsolidated sandstone and limestone
that are inter layered. The limestone is moire trarismissive than
either the unconsolidated sand or sandstone'; it is from the more
transmissive zones of the limestone that water supplies are
drawn. Transmissivity of the Biscayne Aquifer ranges from 5.4 X
10* ftVday where the aquifer is mostly sand to greater than 1.6
X 106 ftVday in the limestone-rich areas. Regional flow of
ground water is to the southeast; however, the direction of flow
may be influenced by the Preston-Hialeah wellfield which may
impart a southwestern flow direction.
5.4 RESULTS OF THE REMEDIAL INVESTIGATION
The purpose of the Remedial Investigation (RI) is to gather
and analyze sufficient data to characterize the site in order to
perform the Baseline Risk Assessment, which determines the site's
impact on human health and the environment. Both the RI and Risk
Assessment are used to determine whether further remedial action
is necessary at the site.
The RI was designed to focus on the remaining areas of
potential contamination not addressed during the removal action.
All field investigation activities at the Anaconda/Milgo site
were conducted and completed during April and May of 1993.
-------
During this period, samples of soil, groundwater, and sediment
were collected to determine the nature and extent of
contamination at the Site. During this investigation, 107 soil
screening samples were collected to determine extent of
contamination by evaluating chromium concentration in soil. An
additional 39 soil samples were collected from locations
targeting suspected source areas to characterize the nature of
contamination by analyzing for the Target Compound List (TCL) and
the Target Analyte List (TAL) (See Figures 5-2, 5-3).
Groundwater was sampled from 3 depth intervals, (20 feet, 40
feet, and 70 feet) at 9 locations and from 20 feet at an
additional location. Locations were chosen to provide upgradient
and downgradient data for both the historic direction of flow and
the direction of flow currently suspected under the pumping
influence of the Hialeah Preston Wellfield (See Figure 5-4).
These samples were analyzed by both screening and TAL/TCL
methods. Sediment samples were collected from storm drains
around the site (See Figure 5-5). These samples were analyzed
for chromium by screening methods, and selected storm drains were
sampled and analyzed for TAL/TCL constituents.
The sampling results for surface soils are presented in
Table 5-1. A total of eight inorganics and four organics were
detected in the soils at the site. Inorganics, such as,
aluminum, chromium, copper, lead, manganese, and zinc were
detected frequently'in soil samples from both Anaconda and Milgo.
Aluminum, chromium, lead, and zinc were found at elevated
concentrations primarily in the two potential disposal areas near
the former treatment structures and possibl^ location of the
former percolation pond on the Anaconda property. The highest
concentrations of chromium and other inorganics were found in
surface samples from the alley between the former Milgo building
and the former Elgin Watch Company. Results indicate that
average soil concentrations for chromium in background samples
was exceeded in 6 surface (0-2 feet) and 8 subsurface (2-10
feet) samples from the Anaconda property, and 16 surface and 2
subsurface samples from the Milgo property. Almost all of the
Chromium (97%) was found to be in the less toxic trivalent form.
The sampling results for groundwater are also present in
Table 5-1. For total chromium, none of the groundwater samples
had concentrations greater than the State and Federal drinking
water standard of 100 ug/1 except AM-GW-07-01. This well,
located near the probable location of the former Anaconda
percolation pit, was constructed by NUS in 1987. An NUS report
indicated that the well was constructed without a sand pack
around the screen. Subsequent resampling employing methods to
minimize turbidity resulted in a sample that did not contain
detectable chromium.
Although chlorinated volatile organic compounds (VOCs) 1,2-
-------
00
LEGEND
AS-14
.®
AA-SS-04
SCREENING SAMPLE
SAMPLE FOR LABORATORY
ANALYSIS
12
AA-SS-02
• AS-13
• AS-25
AS- 14
AS-1 6
ABANDONED
TREATMENT
. . STRUCTURES
• f \ * ®
-26 / AS-28 A
-/ AS-29
AS
AS-27
GANG NAIL SYSTEM
AA-SS-03
v AS-30 \AA-SS-05
AA-SS-04
-N-
100
SOIL SAMPLING LOCATIONS
ANACONDA OPERABLE' UNIT
ANACONDA/MILGO SITE
MIAMI, FLORIDA
FIGURE No..
5-2
-------
LEGEND
U';-l BG-2
BG-4
BG-3
MI-SS-08-Q1
MS-39"
MS-5 _ X(,
] r
ELGIN WATCH CO.
MI-SS-07-01 ^MI-SS-02
,—MI-S5-
/ MS-38
MS-10
/-MI-:
/MS-1
MS-17 MS-18 .MS-19
MS-28 MS-29 MS-30
MS-6 MS-7 ,t,s_8 \XMS-9
MI-SS-01
MILGO ELECTRONICS ,-Ml-SS-04
MS72I /MS-23 MSr25
yMS-1
MS-2
>
MS-3
MS-4
MS-37
MI-SS-03
'^dJM5-20
MS ^ '
MS-22
i \
'MS-2*4n MS.-26
. V / K* f, * H V
-31 / MS-33 /" MS-35 /
MW 76TH STRETT
MS-32
MS-34
MS- 7
SCREENING SAMPLE
('") SAMPLE fOR LABORATORY
MI-SS-06
SOIL SAMPLING LOCATIONS MILGO
OPERABLE UNIT '
ANACONDA/MILGO SITE
MIAMI, FLORIDA
FIGURE No5
-------
LEGEND
-f- EXISTING WELL
A NEW SHALLOW WELL
" (20 Ft)
,i> NEW INTERMEDIATE WELL
" (40 FT)
D NEW DEEP WELL
(70 FT, RECASED TO 55 FT)
ORAINFIELO
AM-CW-08
MW 76TH STREET
DESK
CONCEPTS
KING METAL
FABRICATION
{+® nl AM-GW-11
I— w—
ANACONDA '
ALUMINUM
^l-M
GANG NAIL SYSTEM
WfW^~
AM-CW-05
AM-GW-02
TIT AM-GW-06
AM-GW-07
MONITOR WELL LOCATIONS
ANACONDA/MILGO SITE
MIAMI, F'LORIDA
j
FIGLIRE No.5-4
-------
LEGEND
A SEDIMENT SAMPLE LOCATIONS
SDS-01
(AM-SD-01) A
SDS-02
ELGIN WATCH CO.
SDS-08 W-GO ELECTRONICS
(AM-SDT-03) SDS-06
0 L. A
A P
SOS-05
—x x—
MW 76TH STREET
DESK SOS-12 SDS-U
CONCEPTS A(AM-SD-OS) ^(AM-SD-04)
KING METAL
FABRICATION
GANG NAIL SYSTEM
ANACONDA
ALUMINUM
ABANDONED
TREATMENT
STRUCTURES
-N-
-SDS-03
SDS-04
.SDS-15
(AM-SD-06)
SEDIMENT SAMPLE LOCATIONS
ANACONDA/MILGO SITE
MIAMI, FLORIDA
FIGURE No.5-5
-------
Table 5-1
Contaminants of Potential Concern
Anaconda/Mlkjo site
Miami, Florida
Bls(2-ethylhexyl)Phthalate
Benzo(b and/or k) flouranthene
Benzo(a]pyrene
4,4'DDE
Aluminum
Arsenic
Barium
Chromium VI
Copper
Lead
Manganese
Mercury
UNFTS
ug/kg
ug/kg
ug/kg
ug/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
MINIMUM
9400
930
320
1.5
110
6.4
8.8
0.45
4
1-7
12
0.16
MAXIMUM
100,000
930
330
2000
31,000
6.4
1100
22
750
790
160
2.93
AVERAGE
39,767
930
325
330
4282
6.4
385
1-4
132
925
38
15
DETECTS
3
1
2
8
18
1
3
5
8
16
15
2
SAMPLES
18
18
18
18
18
16
18
15
18
74
18
18
1,2-dlchtoroethene
Vinyl Chloride
AkJrta
Arochlor-1248
Arsenic
Chromium
Lead
Manganese
UNfTS
ug/l
ug/l
ug/l
ug/l
ug/l
ug/l
ug/l
ug/l
MINIMUM
10
37
0.018
0.91
12
11
4.3
16
MAXIMUM
110
37
0.018
0.91
12
280
31
70
AVERAGE
53
37
0.018
0.91
12
69
13.7
27.2
DETECTS
7
1
1
1
1
7
3
10
SAMPLES
25
25
25
25
25
25
25
25
-------
dichloroethene and vinyl chloride were detected in deep
groundwater samples, evidence suggests that these chemicals may
or may not be associated with releases from activities at the
Anaconda/Milgo site. The specific contaminants that were found
in the deep wells have been cited as an area-wide groundwater
condition, detected at concentrations similar to those found
during this study in an 80 square mile area that includes the
location of the Anaconda/Milgo site. Determination of the nature
and extent of VOC contamination associated with the
Anaconda/Milgo site is confounded by the presence of multiple
other sources of contamination. The sites closest to the Site
are the Ace Parker Site and General Electric Apparatus Company
which are documented sources of VOCs to the groundwater. Also
important to note is that the VOC products that were found at the
Anaconda/Milgo site are considered to be degradation products,
but there is a lack of parent compounds found on the site to
substantiate the presence of these degradation products. In
addition, the majority of these products were found only in the
deeper wells, not in the shallow or intermediate wells. However,
FDEP has suggested that the contaminants may have been associated
with past operations.
Storm drain sediment results indicate that with the
exception of one sample, impact would be minimal. The one sample
location collects storm water from the eastern portion of the
Anaconda property; however, this location is completely covered
by asphalt and has been since 1985. Manufacturing process
activities at the site, particularly in the treatment areas, is
well known and understood. The study area Jias been extensively
modified by land development for commercial/ purposes. The site
is predominantly paved, including areas used in the past for
wastewater disposal. These waste source areas have been unused
for many years. Fate and transport experimentation (See Appendix
F of the RI Report) on site-specific soil indicates that chromium
and lead in the soil at the site would not produce significant
levels of dissolved chromium or lead in groundwater and the site
data supports these conclusions.
6.0 SUMMARY OF SITE RISKS
A Baseline Risk Assessment was conducted as part of the RI
to estimate the health or environmental threats that could result
if no further action were taken at the Anaconda/Milgo site.
Results are contained in the Final Baseline Risk Assessment
Report. A Baseline Risk Assessment represents an evaluation of
the risk posed if no remedial action is taken. The assessment
considers environmental media and exposure pathways that could
result in unacceptable levels of exposure now or in the
foreseeable future. Data collected and analyzed during the RI
provided the basis for the risk evaluation. The risk assessment
process can be divided into four components: contaminant
identification, exposure assessment, toxicity assessment, and
13
-------
risk characterization.
6.1 CONTAMINANTS OF CONCERN
The objective of contaminant identification is to screen the
information that is available on hazardous substances present at
the site and to identify contaminants of concern (COCs) in order
to focus subsequent efforts in the risk assessment process. COCs
are selected based upon their toxicological properties,
concentrations and frequency of occurrence at the site.
Contaminants in subsurface soils were not considered to be
chemicals of potential concern for the risk assessment. An
analysis of the leaching potential of subsurface soils present in
the RI Report concluded that contaminant concentrations in
subsurface soils were not presenting a likely threat to the
underlying groundwater. Based on the data evaluation and
screening steps necessary, the following were selected as
chemicals of potential concern for quantitative evaluation of
risk.
SURFACE SOIL; Bis(2-ethylhexyl)phthalate, Benzo(b and/or
k) fluoranthene, Benzo(a)pyrene, 4,4'DDE, Aluminum, Arsenic,
Barium, Chromium VI, Copper, Lead, Manganese, and Mercury
GROUNDWATER: 1,2-Dichloroethene, Vinyl Chloride, Aldrin,
Aroclor-1248, Arsenic, Chromium, Lead, and Manganese.
j
6.2 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. The results
of this exposure assessment are combined with chemical-specific
toxicity information to characterize potential risks. Human
receptors on or near the site were characterized under current
and potential future land use scenarios. The exposure pathways
evaluated quantitatively for the current use scenario were
incidental ingestion of soil, inhalation of particulates from the
soil, and dermal absorption of soil for an adult worker and child
trespasser. The pathways evaluated under the future use
scenario, include the three mentioned above as well as ingestion
of groundwater and inhalation of VOCs during showering again for
the adult worker and child trespasser as well as the adult and
child resident. Since no drinking water wells are known to be
contaminated, exposure to contaminants detected in groundwater is
not a currently complete exposure route. According to subsection
24-12 (Environmental Protection) of the Dade County Code, "No
water supply well shall be constructed or used until a written
approval from DERM has been received...." In addition, also in
this same subsection it is stated "When an approved public water
14
-------
main is made available and operative in a public right-of-way or
easement abutting the property, any existing individual potable
water supply system, device, or equipment shall within ninety
(90) days, be abandoned and the source of potable water for the
residence or building shall be from the approved public water
supply main. " A public water main does exist within the vicinity
of the site. Please see Table(s) 3 and 4 of the Baseline Risk
Assessment for the quantitative results of the exposure
assessment.
6.2.1 Land Use
Study area land use northwest, west, and south of the subject
site includes light industrial and commercial. A number of the
business structures in the site area are vacant. A small
residential apartment building is located north of the Milgo
property. A residential trailer park is located east of the
site. Generally, land use within a 1-mile radius of the site can
be described as commercial/industrial.
6.3 TOXICITY ASSESSMENT
The purpose of a toxicity assessment is to weigh available
evidence regarding the potential of the contaminants of concern
to cause adverse effects in exposed individuals and to provide an
estimate of the relationship between the extent of exposure and
the likelihood of adverse effects. The toxicity assessment is
based on toxicity values which have been derived from
quantitative dose-response information. Tojticity values for
cancer are known as slope factors (SFs) and' those determined for
nonearcinogenic effects are referred to as reference doses
(RfDs).
Slope factors (SFs), which are also known as cancer potency
factors (CPFs), have been developed by EPA's Carcinogenic
Assessment Group for estimating excess lifetime cancer risks
associated with exposure to potentially carcinogenic chemicals.
SFs, which are expressed in units of (mg/kg-day)'1, are
multiplied by the estimated intake of a potential carcinogen, in
mg/kg-day, to provide an upper-bound estimate of the excess
lifetime cancer risk associated with exposure at that intake
level. The term "upper-bound" reflects the conservative estimate
of the risks calculated from the SF. Use of this approach makes
underestimation of the actual cancer risk highly unlikely. SFs
are derived from the results of human epidemiological studies or
chronic animal bioassays to which animal-to-human extrapolation
and uncertainty factors have been applied. Cancer slope factors
for the potential contaminants of concern may be found in Table 6
of the Baseline Risk Assessment.
Reference doses (RfDs) have been developed by EPA for
indicating the potential for adverse health effects from exposure
15
-------
to chemicals exhibiting noncarcinogenic effects. RfDs, which are
expressed in units of mg/kg-day, are estimates of lifetime daily
exposure levels for humans, including sensitive individuals.
Estimated intakes of chemicals from environmental media (e.g. the
amount of a chemical ingested from contaminated drinking water)
can be compared to the RfD. RfDs are derived from human
epidemiological studies or animal studies to which uncertainty
factors have been applied (e.g. to account for the use of animal
data to predict effects on humans). These uncertainty factors
help ensure that the RfDs will not underestimate the potential
for adverse noncarcinogenic effects to occur. Reference doses
for the potential contaminants of concern may be found in Table 7
of the Baseline Risk Assessment.
6.4 RISK CHARACTERIZATION
In this final step of the risk assessment, the results of
the exposure and toxicity assessments are combined to provide
numerical estimates of the carcinogenic and non-carcinogenic
risks for the site. Excess lifetime cancer risks are determined
by multiplying the intake level with the slope factor. These
risks are probabilities that are generally expressed in
scientific notation (e.g. IxlO"6 or 1E-6). An excess lifetime
cancer risk of IxlO"6 indicates that, as a plausible upper bound,
an individual has a one in one million chance of developing
cancer, over a 70-year lifetime, as a result of site-related
exposure to a carcinogen. The NCP states that sites should be
remediated to chemical concentrations that Correspond to an
upper-bound lifetime cancer risk to an individual not exceeding
10~6 to 10~* excess lifetime risk. Carcinogenic risk levels that
exceed this range indicate the need for performing remedial
action at a site. As shown in Table 6-1, the total cancer risk
for all exposure pathways is 8E-7 for the child trespasser and
1E-6 for the adult worker under the current use scenario. The
total cancer risk under the future use scenario as shown in Table
6-2 represents a risk of 8E-07 for the child trespasser and 2E-05
for the adult worker while the risk is 4E-5 for the child
resident and 5E-5 for the adult resident.
In order to characterize potential noncarcinogenic effects,
estimated intake levels are compared with toxicity values.
Potential concern for noncarcinogenic effects of a single
contaminant in a single medium is expressed as the Hazard
Quotient (HQ) (or the ratio of the estimated intake derived from
the contaminant concentration in a given medium to the
contaminant's reference dose). A HQ exceeding unity (1.0)
indicates a potential for site-related noncarcinogenic health
effects. By adding the HQs for all contaminants within a medium
16
-------
Table 6-1
Summary of Cancer and Noncancer Risks by Exposure Route
Current Use Scenario
Anaconda / Milgo Site
Miami, Florida
^ ' "/i./-; -Exposure
K- '<"'*'< ,"" . Route
•?*- '" ' :c- ' -
Inadvertent Ingestion of Soil
Inhalation of Oust
Dermal Absorption of Soil
Total Current Risk
Child Trespasser
Cancer
4E-07
6E-10
4E-07
8E-07
- HI ,
0.01
0.00000003
/ 0.003
r
0.01
Adult Worker
iCancer
1E-06
4E-09
NA
HI
0.01
0.0000001
NA
i
1E-06
0.01
HI Hazard Index
NA Not Applicable
17
-------
Table 6-2
Summary of Cancer and Noncancor Risks by Exposure Route
Future Use Scenario
Anaconda / Mllgo Site
Miami, Florida
Exposure
Route
Inadvertent Ingestion of Soil
Inhalation of Oust
Dermal Absorption of Soil
Ingestion of Groundwater
Inhalation of VOCs
Total Future Risk
. Child Resident
•:
Cancer
7E-06
6E-09
2E-06
1E-04
NA
1E-04
HI
0.3
0.000001
0.03
1.2
NA
1.5
Adult Resident
Cancer
3E-06
5E-09
4E-06
2E-04
2E-05
2E-04
Hj
0.03
0.0000001
0.01
0.5
NA
0.5
Lifetime Resident
(Child + Adult)
Cancer
1E-05
1E-06
6E-06
3E-04
2E-05
3E-04
HI
0^3
0.000001
0.04
1.7
NA
2.1
, ^ s ^ \ > v , •• , ••
~ CHird Trespasser?^--
l\--'* " -' :
Cancer
4E-07
6E-10
4E-07
NA
NA
8E-07
H|
0.01
0.00000003
0.003
NA
NA
0.01
- - Adult Worker "
: Cancer
1E-06
.4E-09
NA
6E-05
7E-06
7E-05
H|
0.01
0.0000001
NA
0.2
NA
0.2
HI Hazard Index
NA Not Applicable
VOCs Volatile Organic Compounds
-------
or across all media to which a given population may be reasonably
exposed, the Hazard Index (HI) can be generated. The HI provides
a useful reference point for gauging the potential significance
of multiple contaminant exposures within a single medium or
across media.
The total Hazard Index/ representing the nonearcinogenic
risk for the current use scenario is shown in Table 6-1 and is
equal to 0.01 for the child trespasser and 0.01 for the adult
worker. Under the future use scenario in Table 6-2, the child
trespasser remains the same while the future worker changes to
0.1. The child resident HI is 1.3 while the adult is 0.4. Based
upon the results of the baseline risk assessment, the site is
protective of human health and the environment.
6.5 ENVIRONMENTAL ASSESSMENT (EA^ .
The environmental evaluation (EA), also known as the
ecological assessment, is a "qualitative and/or quantitative
appraisal of the actual or potential effects of a hazardous waste
site on plants and animals other than people and domesticated
species". Environmental receptors that are expected to inhabit
the study area were identified during an ecological survey
conducted as part of the RI. The survey consisted of both a
field survey to determine current conditions and resident
species, and a literature search to determine the historic
ecology in this part of south Florida. The Florida Game and
Freshwater Fish Commission file and the U.s; Department of the
Interior Fish and Wildlife Service were contacted to determine if
any occurrence of threatened or endangered species had been
documented at or near the site. Current site conditions are
quite different from a natural state. The site is located in a
highly industrial/commercial section of Miami. Human presence,
buildings, parking lots, and noise do not encourage or sustain
many plant or animal species.
During the onsite survey, only 27 plant species (11 of which
were native) and only 2 species of wild fauna (common skink and
norway rat) were observed. There were no indications that any
sensitive species utilize this area as habitat or during
migration. The contaminants of concern at the site occur in
surface soils and groundwater. Impacts on surface water bodies
due to groundwater discharge are not expected due to the
localized nature of groundwater contamination, shallow hydraulic
gradient, and distance to the nearest surface water body (the
site lies 2 miles south of the Little River Canal and 2 miles
northeast of the Miami Canal). Due to the existing development
on the site, site surface soils are of limited value as a habitat
for flora and fauna. Lacking suitable habitats and exposure
routes for site contaminants, there is no identifiable risk to
ecological receptors.
19
-------
7.0 DESCRIPTION OF THE "NO ACTION WITH MONITORING" ALTERNATIVE
This remedy applies to the site-related soil and groundwater
contamination. Due to past soil remediation and the presence of
low concentrations of groundwater contaminants that do not exceed
health-based levels, no further action is necessary to address
the Anaconda/Milgo site. Four post-RI supplemental sampling
events will take place in order to verify that no site-related
release of contaminants is occurring. As of the time this Record
of Decision document was written, one sampling event had already
taken place and indicated that the contaminants found during the
RI were no longer present in the groundwater at the site. If the
results of the monitoring show that there is no unacceptable risk
from exposure to site-related contaminants in the groundwater,
then the site will be considered for deletion from the NPL.
However, should groundwater monitoring indicate that the site
poses a threat to human health or the environment, EPA, in
consultation with'the State of Florida, will reconsider the
protectiveness of the "No Action with Monitoring" alternative and
the feasibility of groundwater remediation will be re-evaluated.
8.0 DOCUMENTATION OF SIGNIFICANT DIFFERENCES
The selected remedy as presented in this decision document
has no difference, significant or otherwise, from the preferred
alternative presented in the proposed plan.
20
------- |