EPA Superfund
Record of Decision:
PB94-964051
EPA/ROD/R04-94/180
September 1994
Davie Landfill Site,
Davie, FL, '
8/11/1994
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RECORD OF DECISION
SUMMARY OF REMEDIAL ALTERNATIVE SELEC110N
DAVIE LANDRLL SITE
DAVIE, SROWARD COUNTY, FLORIDA
PREPARED BY
u. S. ENVIRONMENTAL PROTECnON AGENCY
REGION IV
ATLANTA, GEORGIA
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RECORD OF DECSION
DECLARATION
SITE NAME AND LOCATION
Davie Landfill Site
Davie, Broward County, Florida
STATEMENT OF BASIS AND PURPOSE
This decision document (Record of Decision), presents the selected remedial action for the
Davie Landfill Site, Davie, Broward County, Florida, developed in accordance with the
Comprehensive Environmental Response, Compensation and Liability Act C?f 1980
(CERCLA), as amended by the Superfund Amendments and Reauthorization Act of 1986
(SARA), 42 U.S.C. ~ 9601 .t! seq., and to the extent practicable, the National Contingency
Plan (NCP), 40 CFR Part 300.
This decision is based on the administrative record for the Davie Landfill Site. The State of
Florida, as represented by the Florida Department of Environmental Protection (FDEP), has
reviewed the reports which are included in the administrative record for the Davie Landfill
Site. In accordance with 40 CFR 300.430, as the support agency, FDEP has provided EP A
with input pn those reports. Based on comments received from FDEP, it is expected that
written concurrence will be forthcoming; however, a letter formally recommending
concurrence with the remedy has not yet been received.
ASSESSMENT OF THE SITE
Actual or threatened releases of hazardous substances hom the Davie Landfill Site, if not
addressed by implementing the response action selected in this Record of Decision (ROD),
may present an imminent and substantial endangerment to public health, welfare, or the
environment.
DESCRIPTION OF THE SELECfED REMEDY
This action is the second and final action planned for the Site. This action addresses ground
water contamination at the Site and calls for the implementation of response measures
which will protect human health and the environmenl
The selected remedy relies on natural attenuation of vinyl chloride and antiinony. A
ground water monitoring program would be performed to ensure that attenuation is
effective. Ground water would be monitored at wells along the perimeter of the landfill
(compliance wells), as well as in residential wells near the Site, untilleve1s of vinyl chloride
and antimony reach cleanup goals or asymptotic levels. H contaminants are detected in
residential wells in excess of cleanup goals, connections to the local public water supply will
be provided to affected residents. . .
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Attenuation of vinyl chloride is expected to take up to sixteen years. No estimate of the
time required for antimony to attenuate could be made at this time; however, the levels of
antimony detected are relatively low. Antimony is a metal and is expected to adhere to soil
particles rather than move with the ground water. For these reasons natural attenuation of
Antimony concentrations in ground water is expected to be effective.
The Site is being closed by Broward County under a permit with the State of Florida, in
accordance with the Florida Administrative Code, Chapter 17-701, Solid Waste Management
Facilities, and the monitoring required under this remedy is being addressed by the permit
or other County and State actions.
STATUTORY DETERMINATIONS
The selected remedy is protective of human health and the environment, complies with
federal and state requirements that are legally applicable or relevant and appropriate to the
remedial action, and is cost-effective. However, because treatment of the principal threat at
the Site was not found to be practicable, this remedy does not satisfy the statutory
preference for treatment as a principal element.
Because this remedy may result in hazardous substances remaining onsite, a review was
conducted within five years after commencement of the first remedial action and reviews
will continue to be conducted at five-year intervals to ensure that the remedy continues to
provide adequate -protection of human health and the environment. '
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JOHN H. HANKINSON, JR.
REGIONAL ADMINISTRATOR
~.l/J 1994
DATE
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1.0
2.0
3.0
4.0
5.0
5.1
5.2
5.3
5.4
5.5
5.6
5.7
6.0
6.1
6.2
TABLE OF CONTENTS
SITE LOCATION AND DESCRIPI'ION .......................... 1
SITE HISTORY AND ENFORCEMENT ACTIVITIES ................ 1
HIGHLIGHTS OF COMMUNITY PARTICIPATION. . . . .. . ... .... ... 4
SCOPE AND ROLE OF ACTION. . .. . . . .. . . . .. . . .. .. . . .. .. .. . .. 5
SUMMARY OF SITE CHARACTERISTICS. . . . . . . . . . . . . . . . . . . . . . .. 5
Physiography and Topography. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 5
Soils ................................ e. . . . . . . . . . . . . . . . . . . .. 6
Geolo H dro eolo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 6
Surface Water Hydrology. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 7
Demography and Land Use. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 9
Ecological Survey. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 9
Summary of Site Contaminants. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 11
5.7.1 Substances Detected in Ground Water. . . . . . . . . . . . . . . .. . . . .. 11
5.7.1.1
5.7.1.2
Private Wells .. . . . . . . . . . . . . . . . . .. 11
Ground Water. . . . . . . . . . . . . . . . . .. 15
5.7.2 Substances Detected In Surface Water. . . . . . . . . . . . . . . . . . . . .. 20.
5.7.3 Substances Found In Sediments. . . . . . . . . . . . . . . . . . . . . . . . .. 24
5.7.4 Substances Found In Soils. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 24
SUMMARY OF SITE RISK ................................... 29
Risk Assessment Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 29
Contaminants of Potenti,!} Concern (COpes) to Human Heal.!h ....... 29
6.2.1 Screening Criteria. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 29
6.2.2 Contaminants of Potential Concern in Ground Water. . . . . . . . .. 30
6.2.3 Contaminants of Potential Concern in Soils ................. 30
6.2.4 Contaminants of Potential Concern in Surface Water. . . . . . . . .. 30
6.2.5 Contaminants of Potential Concern in Sediments. . . . . . . . . . . .. 33
6.3
Exposure Assessment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 34
6.3.1 Introduction......................................... 34
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6.4
~.5
6.6
6.7
7.0
7.1
7.2
7.3
7.4
8.0
8.1
8.2
8.3
TABLE OF CONTENTS (continued)
6.3.2 Source, Mechanism of Release, and Transport. . . . . . . . . . . . . .. 34
6.3.3 Potential Receptors and Routes of Exposure. . . . . . . . . . . . . . . .. 35
6.3.4 Path.ways ..."."...".".."".".""..."""....""...""""""" 35
6.3.5 . Exposure Point Concentrat:ions and Dose Assumptions. . .. . . .. 36
Toxicity Assessmen.t """""""""""""""""""""""""""""""""""""""" 36
Risk O\aracterization """"""""""""""""""""""""""""""""""""""" 37
Identification of Uncertainties" " " " " " " " . " " " " " " . " " " " " " " " " " " " " " " "" 44
Ecoloiical Evaluation. . . . . . . . . . . ! . . . . . . . . . . . . . . . . . . . . . . . . . .. 44
6.7.1 Overview........................................... 44
6.7.2 Contaminants of Potential Concern. . . . . . . . . . . . . . . . . . . . . . .. 44
6.7.3 Exposure Assessment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 45
6.7.4 Toxicity Assessment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 50
6.7.4.1
6.7.4.2
Ground Water/Surface Water. :. . . .. SO
Sediments ...................... SO
6.7.5 Risk O\aracterization .............................. . . .. 51
6.7.5.1
6.7.5.2
Ground Water/Surface Water. . . . . .. 51
Sediment. . . . . . . . . . . . . . . . . . . . . .. 52
6.7.6 Uncertainty Analysis
" " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " "" 52
DESCRIPTION OF ALTERNATIVFS . . . . . . . . . . . . . . . . . . . . . . . . .. .. 53
Performance Standards. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 53
Alternative No.1: No Action. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 54
Alternative No.2 - Natural Attenuation With Ground Water Monitoring 54
Alternative No.3 - Ground Water Treatment. . . . . . . . . . . . . . . . . . . .. 56
SUMMARY OF THE COMPARATIVE ANALYSIS OF ALTERNATIVES' 56
Statutory Balancing Criteria. . . . . . . . . . . . . . . . . . . . . . . . . . . . .'. . . .. 56
Threshold Criteria. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 58
8.2.1 Overall Protection of Human Health and the Environment. . . .. 58
8.2.2 Compliance With ARARs .. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 58
Primary Balancing CriteIi! .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 59
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TABLE OF CONTENTS (continued)
8.3.1 Long-Term Effectiveness and Permanence. . . . . . . . . . . . . . . . .. 59
8.3.2 Reduction of Toxicity, Mobility, or Volume Through Treatment.. 65
8.3.3 Short-Term Effectiveness. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 65
8.3.4 Implementability...................................... 65
8.3.5 Cost.............................................. -. 66
8.4
~ ................................... -.. . . .. 66
8.4.1 State Acceptance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 66
8.4.2 Community Acceptance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 67
9.0
SUMMARY OF SELECTED REMEDY. . . . . . . . . . . . . . . . . . . . . . . . . .. 67
9.1
Ground Water Remediation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 67
9.1.1 Major Components of Ground Water Remediation. . . . . . . . . . .. 67
9.1.2 Performance Standards. . . . . . . . . . . . .0. . . . . . . . . . . . . . . . . . .. 68
9.1.3 Compliance Testing. . . . . . . . . . . . . . . . ~ . . . . . . . . . . . . . . . . .. 69
10.0
STATUTORY DETERMINATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 69
10.1 Protection of Human Health and the Environment. . . . . . . . . . . . . . . .. 69
10.2 Attainment of the Applicable or Relevant and ApJ'ropriate Requirements
(ARA.Rs) .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 70
10.3 Cost Effectiveness. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 71
10.4 Utilization of Permanent Solutions to the Maximum Extent Practicable. 71
10.5 Preference for Treatment as a Principal Element. . . . . . . . . . . . . : . . . .. 72
11.0
DOCUMENTATION OF SIGNIFICANT CHANGES. . . . . . .. .. ... . .. 72
APPENDIX A - RESPONSIVENESS SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . .. 73
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LIST OF TABLES
TABLE 5-1: CONTAMINANTS DETECTED IN PRIVATE WELL SAMPLING... 13
TABLE 5-2: CONTAMINANTS DETECTED IN GROUND WATER........... 17
TABLE 5-3: CONTAMINANTS DETECTED IN SURFACE WATER........... 22
TABLE 5-4: CONTAMINANTS DETECTED IN SEDIMENT. . . . . . . . . . . . . . .. 25
TABLE 5-5: CONTAMINANTS DETECTED IN SOIL . . . . . . .. . . . . . . . . . . . . .. 27
TABLE 6-1: CONTAMINANTS OF POTENTIAL CONCERN. . . . . . . . . . . . . . .. 31
TABLE 6-2: POTENTIAL EXPOSURE PATHWAYS/ROUTES. . .... .. . . . .... 36
TABLE 6-3: CONTAMINANTS OF POTENTIAL CONCERN IN GROUND
WATER AND TOXICITY ASSESSMENT. . . . . . . . . . . . . . . . :. . . .. 38
TABLE 6-4: CONTAMINANTS OF POTENTIAL CONCERN IN SOIL
AND TOXIOTY ASSESSMENT. . . . . . . . . . . . . . . . . . . . . . . . . . ~ .. 39
TABLE 6-5: CONTAMINANTS OF POTENTIAL CONCERN IN SURFACE
WATER AND TOXICITY ASSESSMENT. . . . . . . . . . . . . . . . . . . . .. 40
TABLE 6-6: CONTAMINANTS OF POTENTIAL CONCERN IN SEDIMENT
AND TOXIOTY ASSESSMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 41
TABLE 6-7: SUMMARY OF UNACCEPTABLE RISK
THROUGH GROUND WATER INGESTION. . .. .. .. . . . . .. .. .. 43
TABLE 6-8: FEDERALLY liSTED THREATENED AND ENDANGERED SPECIES
AND CATEGORY 1 AND 2 CANDIDATES FOR FEDERAL
LISTING IN BROWARD COUNTY. .. . .. . . .. . . .. . . . . .. .. . ... 46
TABLE 6-9: OBSERVED (JANUARY 1993) AND REPORTED FAUNA,
BROW ARD COUNTY LANDFILL, DAVIE, FLORIDA. . . . . . ... . . .. 47
TABLE 7-1: SUMMARY OF REMEDIAL ACI'lON PERFORMANCE STANDARDS 53
TABLE 8-1: POTENTIAL LOCATION SPECIFIC ARARS AND TeBs
.........60
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UST OF TABLES (continued)
TABLE 8-2: POTENTIAL ACfION SPECIFIC ARARS AND TCBs ...... ... . .. 61
TABLE 8-3: POTENTIAL CHEMICAL SPECIFIC ARARS AND TCBs ......... 64
TABLE 8-4: COMPARISON OF COSTS
................................66
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LIST OF FIGURES
FIGURE 1-1: GENERAL LOCATION MAP ...... ~ . . . . . . . . . . . . . . . . . . . . . . 2
FIGURE 1-2: SITE MAP ............................................ 3
FIGURE 5-1: BROWARD COUNTY LAND USE PLAN .................... 10
FIGURE 5-2: PRIVATE WELL SAMPLING LOCATIONS. . . . . . . . . . . . . . . . . .. 12
FIGURE 5-3: GROUND WATER MONITORlNG WELL LOCATIONS. . . . . . . .. 16
FIGURE 5-4: SURFACE WATER, SEDIMENT, AND SOIL
S~GLOCATIONS ................................ 21
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Record of Decision
Davie Uindfill Site
Pagel
LO
SITE LOCATION AND DESCRIYI10N
The Davie Landfill Site is located at 4001 S.W. 142nd Avenue in the Town of Davie,
Broward County, Florida, approximately seven miles west of Ft. Lauderdale, Florida.
The Site is situated between two major drainage canals. The North New River Canal
is approximately 3.5 miles north of the Site and the South New River Canal (C-ll) is
approximately 0.25 miles south of the Site. The general location of the Site is
illustrated in Figure 1-1.
The property surrounding the Site is located above the floodplain and is not classified
as a wetland area. The 21D-acre Site is comprised of a closed 68-acre trash landfill, a
closed 48-acre sanitary landfill, and a pond (formally an 8-acres sludge lagoon). In
addition, there are three onsite borrow pits which are now known as Lakes No.1, 2,
and 3. A dairy farm (Imagination Farms) borders the Site along the western,
southern and most of the eastern boundaries. Camp Seminole of the South Florida
Council of the Boy Scouts of America borders the Site along the northern boundary.
The land use within three miles of the Site is a combination of commercial,
residential, agricultural, and undeveloped land. See Figure 1-2, Site Map.
2.0
SITE HISTORY AND ENFORCEMENT ACI1VITIES
Operation of the Site began in 1964 with the start-up of the County's garbage
incinerator and the opening of the trash landfill to accept trash, construction and
demolition debris, and ash from the County's garbage incinerator. In November
1971, the sludge lagoon was created in a natural depression onsite to receive grease
trap waste, septic tank waste, and treated municipal wastewater treatment plant
sludges. In 1973, a water quality monitoring program was initiated by Broward
County in cooperation with the U.s. Geological Survey (USGS). In June 1975, the
incinerator was closed because particulate matter emissions failed to meet new air
regulations. The sanitary landfill was opened in 1975 and operated until December
1987, when the entire Site was closed to all incoming waste.
The major source of contamination at this Site was the sludge lagoon. In 1975, the
sludge lagoon received an estimated 2,500 tons of waste per month. In 1977, dikes
were constructed around two sides of the sludge lagoon to increase the capacity of
the lagoon to handle the volume of sludge disposal. Later, these dikes were raised to
receive increased loads. By 1980, the volume of sludge placed in the lagoon had
increased to approximately 7,100 tons per month.
In November 1981, concern regarding ground water contamination from the sludge
lagoon resulted in EP A designating the Site as a hazardous waste site under CERCLA
and prompted Broward County to cease all disposal operations at the lagoon.
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Record of Decision
Davie umdfill Site
Page 2
FIGURE 1-1 GENERAL LOCATION MAP
BROWARD COUNTY
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Record of Decision
Davie Landfill Site
Page 3
FIGURE 1-2 SITE MAP
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Record of Decision
Davie Landfill Site
Page 4
In August 1982, BFA sampled the sludge in the lagoon and found high levels of total
cyanides and total sulfides. Subsequent sampling, performed by BFA in 1983 and
1985, showed reduced concentrations of both contaminants. The Site was placed on
BFA's National Priority list (NFL) as a superfund site in September 1983 due to
concerns related to the sludge lagoon. On September 27, 1985, BFA issued a Record
of Decision (ROD) regarding remediation of the sludge lagoon at the Site.
In 1988, Broward County Public Health Unit sampled private wells in the residential
area south of the Site and found high levels of vinyl chloride. Broward County
provided affected residents with bottled water and later municipal water service.
Most residents continue to use their private wells for irrigation.
In 1989, the necessary remedial actions for the sludge lagoon clean up were.
performed by Broward County, pursuant to the ROD. The remedial activities
included the stabilization of the sludge, relocation of the stabilized sludge to lined
Cell No. 14 of the sanitary landfill and placement of a cap on Cell No. 14. The ROD
addressed source control and indicated that a decision on additional action necessary
to address ground water contamination would be made after an evaluation of the
effects of the remedial action and further assessment of data from continued
monitoring.
In 1992, BFA and Broward County entered into an Administrative Order by Consent
{AOC}, for the completion of the RIfFS process consistent with CERCLA and the
NCP. The RI was finalized in January 1994. The FS was finalized in April 1994.
3.0
HIGHUGHTS OF COMMUNITY PARTICIPATION
All basic requirements for public participation under CERCLA sections
113(k}(2)(B)(i-v} and 117 were met in the remedy selection process. Because the Site
is located in a residential area, community relations activities have been focused on
communication between the residents in the affected community and the government
agencies conducting remedial activities at the Davie Landfill Site. Special attention
has been directed toward keeping the community informed of all study resUlts.
Meetings were held with Town of Davie officials. In addition, an availability session
was held with the community in February 1994 to inform residents of the results of
the remedial investigation and risk assessment for the Site.
The Remedial Investigation Report, Baseline Risk Assessment Report, Feasibility
Study Report, and Proposed Plan for the Davie Landfill Site were released to the
public before May 9, 1994. These documents are incorporated in the Administrative
Record for the Site. A copy of the Administrative Record, upon which the remedy is
based, is located at the Broward County Public library, 100 South Andrews Avenue,
Fl Lauderdale, Florida, and in the South Regional Campus of Broward County
Community College, 7300 Pines Blvd., Pembroke Pines, Florida. In addition, the
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Record of Decision
Davie Landfill Site
PageS
Administrative Record and the Site (project) files are available for review at the EP A
Region IV offices in Atlanta, GA. Notices of availability of these documents were
published in the Sun-Sentinel on February 10 and 13, 1994 and May 8 and 11, 1994.
On May 19, 1994, EPA presented its preferred remedy for the Davie Landfill Site
during a public meeting at the Town of Davie Community Hall, 6591 S.W. 45th
Street, Davie, Florida. At this meeting, representatives of EP A answered questions
about sampling at the Site and the remedial alternatives under consideration. A
transcript of the meeting was prepared and is available at the information
. repositories.
A 3o-day public comment period was held from May 9,1994 through June 8, 1994.
EPA's responses to comments which were received during the comment period are
contained in Appendix A of this Record of Decision. .
4.0
SCOPE AND ROLE OF ACllON
The work at Davie Landfill was organized into two operable units (OUs):
.
OUI for source control of contamination from the sludge lagoon; and
om for identification of any additional hot spots at the Site and
remediation of ground water, as necessary.
..
EPA selected a remedy for OUI in a ROD signed on September 27, 1985. That action
was completed in 1989.
This ROD addresses the second remedial action for the Site. No additional hot spots
were identified at the Site during the RIfFS for om. The function of this remedy is
to reduce the risks associated with exposure to contaminated ground water. The
ground water beneath the Site contains elevated levels of contaminants similar to that
present in wastes and leachate at the Site. Although this water bearing zone is
affected, the contamination is at very low levels and residents near the Site have
been, and continue to be, connected to the public drinking water supply if the
contamination begins to affect their private wells. The purpose of this proposed
action is to prevent current or future exposure to contaminated ground water. om
will be the final response action for this Site.
5.0
SUMMARY OF SITE CHARACTERISTICS
5.1
Phvsiogranhy and Tonography
The Site exists on the western edge of the Atlantic Coastal Ridge in a transition area.
between the Everglades and the Atlantic Coastal Ridge. The Everglades region is
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Record of Decision
Davie landfill Site
Page 6
dominated by low lying marshes, sloughs, tree islands, and cypress forests.. The
Atlantic Coastal Ridge is. characterized by higher topography and drained soils.
The topography in the vicinity of the Site is flat with the exception of two former
beach dunes east and northeast of the Site, the C-11 Canal south of the Site; and the
drainage ditch located east of the Site. Elevations in the vicinity of the Site range
from 5 to 29 feet above National Geodetic Vertical Datum (NGVD) with the highest
elevations located along the former beach dune ridges and the lowest elevations in
the numerous canals and lakes in the area.
The topography at the Site is dominated by the two large landfill mounds in the
northwest and the southwest comers of the Site as shown in Figure 1-2. The North
Mound (sanitary landfill) rises to an elevation of 80 feet NGVD. The South Mound
(trash landfill) rises to an elevation of approximately 60 feet NGVD. The lowest
elevations at the Site exist in the pond (former sludge lagoon) and the borrow pit
lakes in its eastern and southern portions.
5.2
Soils
Soils underlying the Site are predominantly classified by the Soil Conseryation
Service (SCS, 1984) as Udorthents. The SCS uses this term to describe soils that have
been modified by spreading mixed limestone fragments, sand, and shell fill material
over the natural surface for urban or recreational purposes. In a landfill setting, this
fill material is typically excavated from borrow pits and spread over natural soil and
solid waste.
The hydrologic properties of this soil type are highly variable and are dependent on
the material, degree of compaction, and the slope and thickness of the layer. In areas
where the Udorthents soils are poorly compacted, permeability is classified as rapid
(6 to 20 inches/hour) and available water content is low. In addition, natural fertility
and organic content are also low.
Prior to Site development, the dominant native soil type was classified as Hallanclale
fine sand. This soil type is still present on the undeveloped areas that surround the
Site. Hallandale fine sand is a nearly level, poorly drained, and sandy soil found in
the broad flats east of the Everglades and west of the Atlantic Coastal Ridge. It is
underlain by limestone at a depth ranging from 7 to 20 inches. Permeability is
. moderate to moderately rapid throughout with water availability ranging from low to
very low. Organic matter content and fertility are low.
5.3
GeologvlHvdroJeology
The Site overlies and is open to the Biscayne aquifer, a water table system that has
received sole source designation from EP A In the area of the Site, the Biscayne
aquifer is approximately 100 feet thick and is composed of tWo hy~au1ically
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Record of Decision
Davie undfill Site
Page 7
connected units. The upper unit is composed of approximately 15 feet of limestone
and very fine grained quartz sand overlying about 35 feet of sand and sandstone.
The total thickness of the upper unit is approximately 50 feel The lower unit is
composed of approximately 50 feet of sandstone with extensive solution cavities and
vugs which are at least partially filled with very fine sand. The hydraulic
conductivity of the upper unit is estimated to be 300 gallons per day per foot
(gpd/ ft). The hydraulic conductivity of the lower unit is estimated to be
approximately 10,000 gpd/fl
At a depth of approximately 200 feet below land surface, the base of the surficial
aquifer system is reached. The lithologic unit that is of most importance in the
confining sequence is the Miocene age Hawthorn Group~ The predominance of clays
and marls in the Hawthorn result in it being a confining unit between the Biscayne
and Floridan aquifer systems.
In Broward County, the water available from the Floridan aquifer can not be utilized
without some form of treatment due to high mineral content. In addition, the low
permeability and extensive nature of the Hawthorn confining unit in the study area
make the potential for chemical contaminants entering the Floridan aquifer remote.
Therefore, the discussion of potentially affected aquifers will be limited to the
Biscayne aquifer.
The regional ground water flow direction varies depending on the season and the
elevation of the C-ll Canal. Regional ground water flow is generally from the
northwest to the southeast. This regional pattern can be substantially altered by
back-pumping of the C-ll Canal which is done typically during periods of high
rainfall. The back-pumping of water from the C-ll Canal by the pumps at the 5-9
control structure lowers the water level in the Canal and accentuates the southerly
component of flow direction across the Site. During periods of high canal stage,
ground water flow is away from the canal (to the north on the north side of the
Canal and to the south on the south side of the Canal) and acts as a recharge
mechanism for the aquifer.
5.4
Surface Water Hydrotogv
The Site is located in the C-ll drainage basin whose major features include the South
(C-ll) and North (L-36) New River Canals. The C-ll is approximately one-quarter of
a mile south of the Site while the L-36 is located approximately 31/2 miles north of
the Site. To the east of the Site along Boy Scout Road is a north-south trending
drainage ditch that connects with the C-ll Canal (Figure 1-2). Approximate depth of
this ditch is four feet. Another shallow ditch which also connects to the C-ll is
present west of the Site along Shotgun Road. Neither of the ditches receive direct
storm water runoff from the Site.
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Record of Decision
Davie LandfiU Site
PageS
There is a perimeter berm around the Site sufficient to retain a 25-year, 72-hour storm
onsite. All storm water from the Site is channeled to one of the onsite borrow
pits/lakes or the pond (former sludge lagoon). A shallow ditch does separate the
Site from the Boy Scout Camp. However, this ditch is dry most of the year and is on
the north side of the perimeter berm which prevents landfill storm water runoff from
entering this drainage ditch.
A Storm Water Management Plan (SWMP) for the landfill was prepared in December
1987 as part of the landfill closure design. The water management plan for the Site
meets the South Florida Water Management Disbict's (SFWMD's) criteria for the Site
closure.
In accordance with SFWMD requirements, a dry retention area exists around the
sanitary landfill. This retention area provides 1.4 inches of dry pretreatment volume,
which exceeds the required 0.5 inch of dry pretreatment volume. The runoff
contained in the retention area will pass through a l00-foot sand filter constructed as
part of the landfill closure prior to discharging into Lake 1. Runoff in excess of 1.4
inches discharges into Lake 1 through an existing control structure constructed under
the current SFWMD permit.
The Site is divided into two drainage areas. The northern area (81 percent of the
Site) drains into two lakes, Lakes 1 and 2. The southwestern portion of the Site (19
percent of the Site) drains into Lake 3 which is not directly connected to the other
two lakes. An overflow structure is located in the eastern berm along Lake. 1 but has
not been connected to the Boy Scout Road ditch. The control elevation of this
structure is set at the 25-year storm stage, so that no overflow will occur until the
water levels in the lakes exceed the 25-year storm stage. As part of the closure
design, Lakes 1, 2, and the pond (former sludge lagoon) have been physically
connected, thereby creating one water body. The overflow, when completed, will
discharge' into the ditch immediately east of Boy Scout Road through a proposed
36-inch culvert. This ditch connects into the C-l1 Canal one-quarter mile south of the
Site. Lake 3 has the capacity to retain a 25-year storm. No interconnect or outlet for
Lake 3 currently exists.
The SFWMD allows 20 cubic feet per second per square mile (csm) or 6.5 cubic feet
per second (ds) offsite discharge from this Site for a 25-year design storm. The
retention of the entire 25-year storm therefore exceeds the SFWMD's criteria. The
design also includes a berm around the entire Site with a minimum crest elevation of
10.0 feet. The berm elevation was established so that the 25-year storm could be
retained onsite, if required. The minimum building floor elevation within the Site is
set at elevation 10.0 feet NGVD, thereby providing 25-year flood protection. The
minimum road elevation is 10.0. feet NGVD. A No Discharge Permit application has
been submitted to EP A under the National Pollution Discharge Elimination System
(NPDES) program. .
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Record of Decision
Davie Landfill Site
Page 9
The side slopes of the landfill and the berms will have vegetation to prevent erosion
from sheet flow. In areas where runoff is concentrated, inlets, drain pipes, and
channels are being constructed as part of the closure plan to convey the runoff from
the top of the landfill and down the side slopes into the retention areas.
5.5
Demographv and Land Use
Broward County has an estimated population of 1,278,384, while the Town of Davie
has an estimated population of 49,033 based on 1990 U.s. census results. Davie is
located approximately 2.5 miles west of Fort Lauderdale, a major population center in
the County. Cooper City, which is essentially surrounded by Davie on three sides,
has a population of 22,108. Other population centers adjacent to Davie are Sunrise,
Hollywood, Weston, Plantation, and unincorporated areas of Broward County.
There are various land uses adjacent to the Site. To the north lies Camp Seininole of
the South Florida Council of the Boy Scouts of America. Along the western,
southern, and most of the eastern boundaries lies Imagination Farms, a dairy farm.
To the northeast lies a single-family residential development, Sunny Lake Farms. A
South Florida Water Management District (SIWMD) telemetry tower is located
southeast of the Site along Boy Scout Road and adjacent to the C-11 Canal which is in
the jurisdiction of the SFWMD. Just south of the C-ll Canal is the single family
residential development, Sunshine Ranches. Surrounding area land uses as shown in
the Broward County Land Use Plan prepared by the Broward County Planning
Council (December 9, 1992) as shown in Figure 5-1.
Approximately half of the homes identified within a one-mile radius of the Site, in
addition to Imagination Farms and the Boy Scout Camp, utilize private wells for
domestic purposes (drinking, washing, irrigation, etc.) However, a number of these
homes utilize bottled water for cooking and/or drinking purposes. Homes southwest
of the Site are connected to a public water supply system, South Broward Utilities.
In addition, a section of the Sunshine Ranches subdivision immediatley south of the
Site is also connected to South Broward Utilities.
5.6
Ecological Survey
An ecological survey provided the basis for describing the primary ecological
components of the Site. The purpose of this survey was to provide baseline
information regarding major onsite habitats, vegetation types, and animal species
prior to the initiation of closure activities at the Site. Due to past activities at the
landfill, there was little remaining natural habitat at the Site. Major vegetation
consisted largely of a stand of Brazilian Pepper and Australian Pine around the
perimeter of the Site. Terrestrial features onsite (e.g., mounds, roads, parking areas).
are influenced by past construction and present use. Aquatic features are, for the
most part, also heavily influenced by past construction. For example, borrow pit
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Record of Decision
Davie Landfill Site
Page 10
FIGURE 5-1 BROWARD COUNTY LAND USE PLAN
!
T
LEGEND
. DAvIE LA.\C)fU
C3 RESClENTI&L
V7?I NlUSTRIAl. UTUTY AICI
~ TII&NSPORTA TION
o
~
COI&f:RCIAL ANO
",*-C FAa.ITIES
AGRICUL rURAL
o
SCAU: .. IoIl!S
~
-:.
j~
11
.!
27
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Record of Decision
Davie Landfill Site
Page 11
Lakes 1, 2, and 3 have unnatural straight-sided shapes, with steep banks and limited
littoral zones. The pond (former sludge lagoon) is more natural in both overall shape
and shoreline slope.
A relatively diverse and healthy biological community is present onsite. Ongoing
closure activities have removed most existing vegetation for the purpose of replanting
the Site with a diverse assembly of native species. These replantings will increase the
habitat quality for local wildlife. The temporary loss of wildlife from construction
activities and vegetation removal will probably be compensated rapidly bY
immigration of individuals from adjacent offsite locations. Species in addition to
those presently onsite are expected to colonize onsite habitats as habitat diversity is
increased Plans to regrade (ie., decrease the steepness of the slope) the shoreline
edges of onsite lakes will increase littoral zone aquatic habitats. Littoral zones, or
shallow water shorelines, play an important role in aquatic ecosystem function.
The initial biota survey of surface water bodies onsite was limited to shallow or near-
shore areas accessible by foot. Shoreline vegetation consists of weedy species,
including several types of grasses. A more comprehensive biota survey of deep
waters ,!as not justified based on the results of surface water an~ sediment sampling.
5.7
Summary of Site Contaminants
5.7.1 Substances Detected in Ground Water
5.7.1.1
Private Wells
Sixteen private homes south of the Site were sampled along with two wells at the
Imagination Farms facility west of the Site and two wells at the Boy Scout Camp
north of the Site for a total of 20 wells. The private well locations are shown on
Figure 5-2. The results of the analyses for volatile organic compounds (V0Cs), semi-
volatile organic compounds, metals, and inorganic parameters are provided in Table
5-1, along with applicable federal and state primary and secondary drinking water
standards. Primary drinking water standards are regulated and enforced by federal
and state authorities to protect human health. Secondary drinking water standards
are regulated by federal authorities but are not federally enforceable. Secondary
drinking water standards are intended as guidelines for the states and address
contaminants that affect aesthetic qualities related to public acceptance of drinking
water (i.e., odor, taste, color, etc.).
One private well contained contamination that exceeded a primary drinking water
standard (i.e., Maximum Contaminant Level (MCL) ) for lead with a concentration of
45 ug/L (the primary MCL for lead is 15 ug/L). One well contained manganese at a .
concentration of 71.7 ug/L (the secondary standard for manganese is 50 ug/L).
Another well contained aluminum at a concentration of 218 ug/L (the secondary
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Record of Decision
Davie Landfill Site
Page 12
FIGURE 5-2: PRIVATE WELL SAMPLING LOCATIONS
U:GOCI
~
~
. --.. ..- -...a
---
JIll. -
..r.& ...,
l
"
u~
lOT
SCOUI
C'"
Q
Dr-
I
I
I
I
I
I
<:I.
-----
-,..-
ISAJO' ...
L~
LAK£ .,
_ow
JII' ..
I
_flOOl"- I
tDAIIT ,-
R
sou,.. -
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-..-
a
I?= ~r---
~~~_:::.J
OIIAHG£
I-
,-
0&8SO!"'S ,-
a
-
. PAL-
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Record of Decision
Davie Landfill Site
Page 13
TABLE 5-1: CONTAMINANTS DETECTED IN PRIVATE WELL SAMPUNG
.
Site-Related SamDles Bacbround Samnle (MW.22) ClOud Water
SlaDdards
Range of Frequ~ Range of at DO ItuIdaJd,
ClOud Water ADa1yte Frequeacy Detected
of CoaceatratiODS of Detected ~~cr'trati0D8 ) ~
~ Detectioa (p ) d PII88J)' MCL
...»:....:.-:..'»' ."" ... ~$(..... -.: ».". .:.-'$.~"(.-: . oX ~. ',..." .' ',.' . ""...' *.tI&~.fl.14t.\w.Jtm.~_?&-
:,:,w,.x'*~""'«>>":::::f."w:::~,>,.y..w"~4_~@;.$X.<:L¥.w:'@.w" .~>,oX . , ,. .~~w..
:&:' .:: ';:' .:~::::-:::~?:::::::--:::.:~~m:-:-":~ ~@::m:@~: .~....»:.; .. ..:" . ":x.'" '. . '"' .~~...
Aluminum 3/6 21.0 - 218 3/3 24.6-6'2 200 b)
Barium 6/6 18A - 76.0 3/3 15.8-31.2 2000 d
Calcium 6/6 94.7M- 132.000 3/3 103 QOO.l08.ooo - a)
Cobalt 1/6 4.2 - - - a)
Cyanide 1/20 68 - - 200 c)
Iron 20/20 110- 17 -OW) 3/3 311~11r.m 300 b)
Lead 2/20 33 -45 - - 15 c:)
Malll'lesium 6/6 611'75 - 10500 3/3 531~ 900 - a)
Manllallese 6/6 7.B - 71.7 3/3 21.2-395 50 b)
Potassium 3/6 2-~':U) - 9..540 - - - a)
Sodium - 6/6 18A50 - 97 700 3/3 9 -- -- -- 160 000 c)
Vanadium 2/6 3.7 - 6.2 - - - a)
Zinc 9120 19.4 - 190 3/3 22.4-39.4 5000 b)
bis(2-eth 1 hthalate 6/6 0.2 - 1.0 2/3 0.4-05 6 c)
lA-Dichlorobenzene 2/6 03 - 0.4 - - 75 d
Di-n-butvlohthalate 2/6 0.4 - 0.4 213 0.04-0.06 a)
Pv:rene 1/6 0.08 - - - a)
ChIorobenzene 1/20 7.0 - - l00d
1.2-Dichloroethene 1/6 1.0 - - 10 c:)
r.~-j_I_~~~t~tm~~~ ~~~WA.IEJI _JilDJ~i~~t:~ t[4lRl{¥.4.ilIfMi ~~J~q{~.a~t1~~:. ;:~2m"88
AJbtinitv 20/20 160-460 313 ~290 - a)
BOD 1/20 2.2 2/3 2.2-4.4 - a)
Total Onranic Carbon 20/20 13-3'2 313 22-32 - a)
COD 19120 28-92 3/3 75-89 - a)
Chloride 20120 23-200 3/3 18-68 250 b)
Fecal Coliform 001/100 mL 2120 1-40 1~ 2 1 d
Hardness 20/20 2SO-43O 313 400&0 - a)
Nitrate 9120 O.OS3-0.B7 1/3 0.047 10 c)
Nitrite 4120 O.011-O.02S - - ' 1 c)
Ammonia. Ni-- 20/20 0.23-93 3r.t 0.21-0.99 - a)
Phenolics 1120 0.014 - - - a)
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Record of Decision
Davie Landfill Site
Page 14
TABLE 5-1: CONTAMINANTS DETECI'ED IN PRIVATE WELL SAMPUNG (continued)
Ph 6
TDS 20
Sulfate 16 20
Turbid! , N1U 20/20
- = There was no measurement above the detection Umit.
rJj(1; N~~~r-1iIw
Range of
Detected ConceDtraIioDa
(p )
Ground Wa..
StmcIazU
." DO IIuoIar4.
)~~
c) Met
Ground Wa.. ADalyIe
Site-Related s.m la
~
CODcentnti-
(p
Bac
8-60
1 c:)
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Record of Decision
Davie Landfill Site
Page 15
standard for aluminum is 200 ug/L). Based on the isolated exceedances noted in
these wells, the metals detected appear to be reflective of contamination from
plumbing rather than a ground water quality problems.
Iron was detected in excess of its secondary drinking water standard in every well
except one. Concentrations ranged from 730 ug/L to 4400 ug/L. The secondary
standard for iron is 300 ug/L. The only well which did not exceed the standard for
iron had a concentration of 110 ug/L. Therefore, the high iron concentrations appear
to be ambient to the area based on the high concentrations in almost all monitoring
wells and private wells.
Concentrations of Total Dissolved Solids (TDS) ranged from 370 mg/L to 830 mg/L.
Eight wells contained TDS in excess of ground water standards. The secondary
ground water standard for TDS is 500 mg/L. Exceedances of TDS are considered Site
related.
Of the remaining inorganic parameters, the only drinking water standards to be
exceeded were fecal coliform and turbidity. Fecal coliform was detected in the two
wells at Imagination Farms: one sample contained 1 col./1oo mi. and the other
contained 40 col./loo mi. The primary MCL for fecal coliform is a positive result
(i.e., 1 col./100 mi.). The primary MCL for turbidity is 1 NTU. Turbidity exceeded 1
NTU in all wells except one. These exceedances are not considered Site related.
5.7.1.2 .
Ground Water
Thirteen new monitoring wells were installed as part of this investigation. The
primary purpose for the additional wells was to better determine background/
ambient ground water quality. Ground water samples from these wells, along with
59 existing monitor wells, were collected and analyzed. The monitor well locations
are shown on Figure 5-3. The results of the ground water monitor well analyses are
summarized in Table 5-2.
All of the ground water samples were analyzed for VOC parameters. The only VOC
parameter that was detected at concentrations above its primary drinking water MCL
was vinyl chloride. Vinyl chloride was detected at an estimated concentration of 3
ug/L in the sample collected from MW 13-50 and at estimated concentrations of 2
ug/L in the ground water samples collected from MW 13-25, MW 18-75, MW 19-27,
and MW 19-67. The state of Florida MCL for vinyl chloride in ground water is 1
ug/L while the federal MCL is 2 ug/L. Because a plume of vinyl chloride was
associated with the Site in the past and because the wells in which vinyl chloride was
detected are downgradient of the Site, vinyl chloride contamination is considered Site
related.
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Record of Decision
Davie landfill Site
Page 16
FIGURE 5-3
GRQUND WATER MONITORING WELL LOCATIONS
" II
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ffl
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R
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...
-
w-
c:I
t~
.... CLUSTt. '2
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Record. of Decision
Davie undfill Site
Page 17
TABLE 5-2: CONTAMINANTS DETECTED IN GROUND WATER
18/19 21.8 - 3.1.ZO
3/19 15.0 - 19.1
4/69 6.0 - 14
19/19 24.6 -1725
3/19 1.0 - 1.1
Calcium 19/19 9-'00 - 23310)
Chromium 22/fD 3.1 - 20
Cobalt 2/19 3.8 - 30t
Cotmer 3/69 43 - 33
Cvanide 14/fD 10 - 67
Iron 69/fD 350-17.000
Lead 4/69 4.8 - 73
Mamesium 19/19 6.520 - 29950
Mananese 19/19 115 -103
Mercury 1/69 024
Nickel 3/fD 7JJ -72
Potassium 18/19 570 - 88 900
Sodium 19/19 15.800 -19110)
Thallium 1/19 5.0
Vanadium 9/19 3.1 - 62 - - - a)
Zinc 68/fD 13.0 - 296 3/3 22.4 - 39.4 SOOO b)
~~d£t.iiI~i:~~{&*1f:r*mV{tI~_g.~*8~.'~?:~~' :. ~"'" ,.,~~$Xi!~;-~~~ M ::~:~~~lt~_~iBfitititl~AI.
Ground Water Ana1yte
Site-Related SImoln
f:&':f
Ccm-tratiou
(p
Frequency
of
Detection
", :~e.5~~~~:~~~~~f.~$.t$5J;:W.II__~.:'7:~
'. ».'. ';.:-:.y..:-...-..
, .'
" <-:-)C.....,'?'"
Aluminum
Antimonv
Arsenic
Barium
Bacbround SamDle (MW-22) Ground Water
RaDp of SlaDdards
Frequency DetideeJ .~~
of Ccm~~tiou It) MCL
Detection (Pw&.) c:) I'IIaJr CL
:" < :":>:"W%@ili:¥j@.t.MWJ6¥ffiiWf.i/w.m~_. >::h>:'~" ...,w':'i!4W:
m. :-:.@::-:.:-.:W;:;:~~~':::....,W.. .... :«~m.:\W.:,.....x.. ..1'.-:>... "'.'... ... ~«....,:-:~~
3/3 24.6 - Q 200 »)
- - 6C:)
113 57 SOC)
3/3 15.8 - 312 2000 c:)
- 4 c)
313 103.000 -108.000 -a)
- - 100 c)
- - - a)
- - 1000 c)
- - 200 c:)
313 3.110 -1Uoo . 300 b)
- - 15 c:)
3/3 5.310 - 8900 - a)
3/3 212 - 395 50 b)
- - 2 c)
- - 100 c:)
- - - a)
3/3 9.190 - 40-'00 160000 c:)
- -
AcenaDhthene 1/19 0.45 - - - a)
Anthracene 1/19 0.1 - - - a)
Bis(2-ethvlhexvl)nhthalate 19/19 0.1 - 2.0 2/3 0.4 - 05 6 c)
B 1 hthalate 2/19 0.1 - 02 - - - a)
1A-Didllorobenzene 10/19 02 -2.0 - - 75cl
Diethvlnhthalate 3/19 O.os - 0.1 - - - a)
2A-Dimethvlphenol 1/19 0.3 - - - a)
Di-n-butvlnhthalate 14/19 OJJ6 - 0.6 2/3 0.04 - 0.06 - a)
Isoohorone 1/19 0.08 - - - a)
2-MethvlnaDhthalene 1/19 IJJ - - - a)
4-Methvlnhenol 1/19 0.3 - - - a)
Pvrene 3/19 om - 0.2 - - - a)
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Record of Decision
Davie Landfill Site
Page 18
TABLE 5-2: CONTAMINANTS DETECTED IN GROUND WATER (continued)
Site-Related Smmles BaCkaouDd ~le (MW-22) Cro1Uld Water
Rmp of RaDge of SlaDdarU
Cro1Uld Water ADalyte Frecrv:mcy Detided ~mcy Detected (q~
of CODceatrati0D8 of CODC~:6ti0D8 ,,~a.
'@$kS"" c) 1'rI.muJ CL
.8-Jj
l"" >m',,-. ", ~. '... . " . .' .', .:.:....'. n' ',..' " ~ x :. ..-"~:-::"':;' "::."~ '" -=-,: '.: ::::'x :.,.....
AcetoDe 8/69 5.0 - Slim 2/3 6.0 - 16 - a)
2-ButanoDe 4/69 2.0 - 56.0 2/3 2.0 - a\
Carbon Disulfide 29/(8 1.0 -140 2/3 4.0 - 5.0 - a)
OIlorobellzene 8/69 10.-14 - - 100 c\
OIlorolonn 1/(8 72 - - 100 c)
12-DidlJoroethene 7/19 1.0 - 3.0 - - ' 70 c'
VinYl Cdoride 5/69 2.0-3.0 - - 1 c)
":::$:.,:.:.:::::..:...,.:.. ;$X~-:::::::$:::-.. :A&tfni\1ID.~ i£i%11M%%RW1Bl -. ..~ £%tt1t@J1~~~ffi~rrill.g1lt~I~Wt.Jili]~Ul~~t~lliitt~~f:~~tWl{~i~~iif~~~~1~I~t~i~futti~
i.. ." m,<;<',',*,'-%!',
U-DDD 1/69 0.025 - - - a)
4,4-DOO' 2/69 0.044 - 0.071 - - - a)
iit1i1i'8ii_i1lIil{."1I~ "'.mliiii~~i~lit~,~~~it~~~rfI{~i1ilIr.lj~@l~~!tilf~j~ill*]\limiF;,f~t
AJka1initv - 69/(8 18MOO 3/3 250-290 a\
-
BOD S2/(8 1.~ 2/3 224.4 - a)
Total n.......uc Carbon 69/(8 '11-93 3/3 22-32 - a'
COD 65/(8 27450 3/3 75-89 - a)
OIloride 69/(8 8.5-320 3/3 18-68 250 b\
Fecal Coliform. col/l00 mL. 26/(8 I-1NTC 1/3 2 1 c)
Hardness 69/(8 130-630 3/3 400-630 - a\
Nitrate 13/(8 0.013-0.96 1/3 0.047 10 c)
Nitrite 3/69 0.011-0.023 - - 1 c\
Nitrnnft 67/(8 O.an-73 3/3 027-0.99 - a)
Phenolics 2/69 0.01 ().().013 - - - a\
PhOSDharus 42/(8 0.011-2.200 1/3 0.004 - a)
69/69 250-1.700 . b\
TDS 3/3 42G470 SOO
Sulfate 44/69 5.8-2500 2~ 6.4-12 250 b\
, N'IU 69/69 2.1-700 3/3 UO 1 c)
pH. UDits 69/69 6.06-7.96 . 3/3 720-729 6.5-85 b)
- = 1here was no measurement above the detec:tiOft limit.
wr/L = mi~ per liter
m = Not AtiDlkabli!
1NTC = Too'Numerous To Count
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Record of Decision
Davie Landfill Site
Page 19
With the exception of iron, only 8 of the 72 wells sampled contained metals which
exceeded their respective drinking water standards. Sodium was detected in MW
11-31 at a concentration of 191 milligrams per liter (mg/L). The state primary
drinking waterMCL for sodium is 160 mg/L. Antimony was detected in wells MW
5-84, MW 11-57, and MW 18-27 at concentrations of 15 ug/L, 19.1 ug/L and 15.9,
respectively. The primary drinking water MCL for antimony is 6 ug/L. Aluminum
was detected in MW 13-50, MW 18-27, and MW 25-35 at concentrations of 3,720
ug/L, 379 ug/L, and 206 ug/L, respectively. The secondary drinking water standard
for aluminum is 200 ug/L. Manganese was detected in MW 18-27, MW 18-50, and
MW 18-75 at concentrations of 53 ug/L, 103 ug/L, and 74.4 ug/L, respectively. The
secondary drinking water standard for manganese is 50 ug/L. - Antimony is
considered a Site related contaminant because ash in the trash landfill is a possible
source. Sodium, aluminum, and manganese are not considered Site related
contaminants due to the well locations and small number of exceedances.
Iron was detected in every sample analyzed in excess of the secondary drinking
water MCL (300 ug/L). Iron concentrations ranged from 3110 ug/L to 11,600 ug/L
in the background wells, (Well Cluster No. 22), to 17,000 ug/L at Well Cluster No.4.
The average iron concentration in the wells is 5,063 ug/L. High iron concentrations
appear to be ambient to the area.
The primary drinking water MCL for fecal coliform is measured in bacteria colonies
per 100 milliliters of sample (col./100 ml.). The MCL for fecal coliform is a positive
result (ie., 1 col.! 100 ml. or greater). Fecal coliform was detected in 27 wells across
the Site area ranging in concentrations from 1 co1/1oo mI. to TNTC (tOo numerous to
count). Fecal coliform bacteria was detected in the upgradient background wells
located on the Boy Scout Camp (Well Cluster Nos. 22 and 23) as well as in the wells
east and west of the Site (Well Cluster Nos. 24 and 25) and in wells downgradient of
the Site south of the C-11 Canal (Well Cluster Nos. 15 and 18). A total of five
clusters reported fecal coliform bacteria in all three wells. These clusters included
MW-6, MW-8, MW-9, MW-12, and MW-23. Fecal coliform is not considered a Site
related contaminant.
The primary drinking water MCL for turbidity is 1 NTU
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Record of Decision
Davie landfill Site
Page 20
TOO was detected in 45 wen samples in concentrations exceeding the secondary
drinking water standard Concentrations in these wells ranged from 510 mg/L to
1,800 mg/L The secondary standard for TDS is 500 mg/L High TDS values are
considered Site related.
Only one sulfate concentration exceeded the secondary drinking water standard of
250 mg/L. This concentration was detected at well MW 5-39 at a level of 2,500
mg/L. Sulfate is considered a Site related contaminant. .
The secondary drinking water standard range for pH is 6.5 to 8.5 pH units. pH
values below this range were measured in 11 samples from well clusters 7, 9, 12, 13,
15, and 19. The pH values from these samples ranged from 6.06 to 6.49. No pH
values higher than 8.5 pH units were measured.
In summary, vinyl chloride and antimony are considered Site related containinants
which exceed primary drinking water standards. Neither contaminant was detected
in a sufficient number of wells to define a plume. Chloride, TDS, and sulfate are
considered. Site related contaminants which exceed secondary drinking water
standard. Only TDS was detected in a sufficient number of wells to define a plume.
Chloride, TDS, and sulfate contamination may affect the aesthetic qualities of
drinking water near the Site. -
5.7.2 Substances Detected In Surface Water
Twenty-five surface water samples were collected from 15 locations. The surface
water (SW) sample locations are shown on Figure 5-4. Three locations proposed for
sampling in the Work Plan were dry and samples could not be collected (SW-l,
SW-2, and SW-18). The analytical results for VOCS, semi-volatile organics,
pesticides/PCBs, metals, and inorganics measured in the surface water bodies, are
summarized in Table 5-3. Federal and state Water Quality Criteria (WQC) are
provided in Table 5-3 for comparison with surface water contamination levels.
Iron was detected in all samples. Iron concentrations ranged from 39.1 ug/L at
SW-10A to 8,920 ug/L at SW-8B. The sample from SW-8B was the only sample to
exceed the state surface water standard of 1,000 ug/L for iron. High iron
concentrations appear to be ambient to the area.
Beryllium was detected in two of the nine samples for which it was analyzed and
was found at concentrations of 1.0 ug/L and 1.2 ug/L at SW-4A and SW-12A,
respectively. These two samples exceeded the state surface water standard of 0.13
ug/L (annual average). SW-12A is a background sample from the C-11 canal,
whereas, SW-4A was taken from the pond onsite.
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Record of Decision
Davie Landfill Site
Page 21
FIGURE 5-4 SURFACE WATER, SEDIMENT, AND SOIL
SAMPLING LOCATIONS
~
~
LfGOCl
IPWU" --- cu. "ilCATWI
... ..........".
. --
1M. -
tCIU . ruT
- 8I88'Ut,. "ec
~ ....ac:r ...ft'8,."" .......
..ou.'OfI rl811D1
~
""GINA TIOH , "IIMS
IOAOIY ,......
S.'SO-Il Loc.oTED I ...E
WEST OF SW'SO-'
H
I
J
- .22
...
-
..
[~
5WI5O-'
~
... .,
ST"
() ~.;~
::. .... -20
...,
NAGIN& TIDH 'AIIMS
ro...y , ..aa.n
- 5WI5O-'5
...
010'-' ,-
S&-.c
IIMOO
.17
p 00.-.0
v
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TABLE 5-3: CONTAMINANTS DETECTED IN SURFACE WATER
Sit&-Re1ated Samples lSW~~~/B) Freshwater Water
~ty Criteria
Surface Water Analyte ~of Range of Detected of~ Range of Detected (ug/L>
Detedibn COiIcefttratiolls ~~OIIS
L
~~i<{,:~,,:-m1i\Sw. ~.. -:~ .., =' .. .. .. .-::~#~~~tifiK.\V@i~ ~r.{f&1~fk1fr~rl!~I~t
".". , ~ x ..
, .. "~.' ., .., .,
Carbon Disulfide 2 1 1 -15 1/4 I 21 r a)
l~.ii.w?,#,~~~.. .. .~~...)~~i_~~W.m~t.tTh' b)
Calcium 6/6 31 950 - 43.300 3/3 29100 - 83100 NCA
Coooer 2/21 2.6- 9:7 - - 34.ss b)
Cyanide 1/21 11 5.2 b)
Iron 21/21 39.1 - 8920 4/4 50 - 311. 1000 b)
Lead - 2/21 3.9 - 5.4 15.91 b)
Mamesium 6/6 U10 - 11.600 3/3 3-':t70 - 15JIM NCA
Mananese 6/6 1.2- 16 3/3 1- 10.6 NCA
Potassium 6/6 2350 - 17.400 2/3 2160 - 2290 NCA
Sodium 6/6 24.300 - 74.200 3~ 9 "10 - 697m NCA
Vanadium 5/6 3.4 - 20.7 1/3 4 NCA
Zinc 7/21 11.6-45.8 3/4 18.5 -26.5 3091 b)
~ffJ;:~~~:~~~:~~~:~\..Z:@~:~~:~*:s~.~t~~__llm\_~~~~~~~~f.*[iift1fi~~~t~~lr~~~~~1~~~i~~Wl~"1t!~!i~ ~!i~~~tlt.fil~~~~4~
aloha-BHC 1/21 0.012 - NCA
delta-BHC 1/21 0.015 - - NCA
::*:.~~~~:~:::~:-.::::~:::f.m: '~~f~~"). .:~~*~~. ;fu_:r~~fi\8t~_mt$~\1tm_i~~*~il~Mltl~~~1!S&~1fu~1~~~~iit; ',','''.'',
, .. .
ADcalinitv 21/21 88-270 4/4 70-260 >20 b)
BOD 6121 1.2-5.1 1/4 4.1 NCA
Total Onzanic Carbon 21/21 6.9-55 4/4 1~26 NCA
COD 15/21 21-170 2/4 87-130 NCA
O1oride 21/21 25-140 4/4 18-140 NCA
Fecal Coliform col.l100ml 17/21 1-110 4/4 4-94 NCA
Hardness 21/21 72-390 4/4 68-270 NCA
Nitrate 10/21 0.02-0.19 2/4 0.028-0.081 NCA
Nittite 4/21 0.010.0.021 - - NCA
Ammonia Nitrotzen 21/21 0.011-5.8 2/4 0.014-0.18 0.02 b)
Phenolics 1/21 0.013 - - 0.001 b)
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TABLE 5-3: CONTAMINANTS DETECTED IN SURFACE WA~ (cohtinued)
5ite-Related Samples
Freshwater Water
Qua1Jty Criteria
(ug/L)
Surface Water Analyte
~~of
Ph horus
TDS
Sulfate
0.015-0.062
1ro.S60
5.3-14
0.97-35
6.74-&.65
1 4
4/4
0.023
120.480
4 4
3/3
0.97-1.1
7.61-8.41
NCA = No criteria available.
a) = Based on federal water quality criteria (40 CPR Part 131).
b) = Based on Florida Surface Water Standards (PAC, Chapter 17-302).
c) = Based on Region IV Waste Management Division Freshwater Quality Screening
Values (November 16, 1992); acute/chronic.
d Based on undissociated H~.
e Based on phthalate esters. ..
f No WQC available; soluble barium concentration in freshwater would need to
exceed 50 mg/L before toxicity to aquatic life is expected.
g Hardness-dependent criteria; value is based on a calculated average hardness of
354 mg/L Caco3 for ground water.
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Davie Landfill Site
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Fecal coliform were detected in 21 samples. Fecal coliform levels ranged from a low
of 1 colony/100 ml. at four locations to a high of 410 colonies/100 mI. at SW-llA (the
pond).
Ammonia nitrogen was detected in 23 samples ranging in concentration from 0.011 to
5.8 mg/L FIfteen samples exceeded the surface water standard of 0.02 mg/L.
Phenolics were detected in one sample, SW-6A in Lake 1, at a concentration of 13
ug/L. The state surface water standard for phenolics is 1 ug/L.
Turbidity of the samples ranged from 0.97 to 35 NTU. The state standard ~equires
that the turbidity not be greater than 29 units above the background. One sample,
SW-10B in Lake 1, is greater that 29 units above the background samples' turbidity.
Based on the contaminants detected, the most prevalent surface water contaminants
are fecal coliform and ammonia nitrogen. These contaminants are as prevalent in
offsite water bodies as in onsite water bodies. These are not considered Site related
contaminants.
5.7.3 Substances Found In Sediments
Seventeen sediment samples were collected and analyzed in the sediment
investigation. The sediment (5D) sampling locations are shown on Figure 5-4. The
analytical results for VOCS, semi-volatile organics, pesticides/PCBs, metals, and
inorganics detected in the sediments are summarized in Table 5-4. No applicable
ARARs were identified to address contamination in sediments. The National Oceanic
and Atmospheric Administration (NOAA) publishes sediment effect levels which are
typically used as screening values for evaluation of ecological risk; those values are
provided in Table 5-4 for comparison with onsite contamination levels.
Grain size analysis was performed on each sediment sample collected. The. analyses
represent the distributions of sediment grain size in the bottom of the surface water
bodies where the samples were collected. The data indicates that approximately half
of the sediment samples are predominantly of silt size and finer, while the other half
falls into the fine to very fine grained sand size range.
In addition, six sediment samples were screened for dioxins using EP A Method 8270.
. Dioxin was not detected in any of the samples.
5.7.4 Substances Found In Soils
Ten soil samples were collected and analyzed as part of the soil investigation. The
soil boring (5B) sampling locations are shown on Figure 5-4. The samples were
collected from 0 to 2 ft depths from the surface. Table 5-5 provides a summary of
VOCS, semi-volatile organics, pesticides/PCBs, metals, and other inorganic
compounds detected in the soils. No applicable ARARs were identified to address
contamination in soils. '
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Page 25
TABLE 5.4: CONTAMINANTS DETECTED IN SEDIMENT
8ac:k~d SamPles
1SD-1 ~2. 51).7 5I).t2 51).14)
Sediment ~ Ran~ of ~ Range of £R-L £R-M
Analyte Of DeteCted Of l'>ebiCted
DetecIian ~ Detection ~~OI\S .
%~.IIr.6i'4~1f~_i.%I¥m;ft~ifitlf1~~El$.IWffi!4.mf@%.fi.Wk.~lr@I%'Illit~:t~m.-tflW~Jf1;t}'M¥:
Site-ReJated Samples
NOAA Bi~~~ Levels
Acetone 3/12 0.16 - 0.12 1/5 0;13 NELA NELA
2-BulaJlone 1/12 039 1/5 0.045 NELA NELA
Carbon Disulfide 1/12 0.092 1/5 9 NELA NELA
OIlorobenzene 1/12 0.23 - - NELA NELA
Toluene 1/12 0.011 - - NELA NELA
4-MethvlDhenol 1/4 0.025 - - NELA NELA
bis(2- 4/4 0.032 - 0.2 3/3 0.056 - 0.1 NELA NELA
EtlivlhexvUDhthalate
Benzo(b)l1uoranthene 1/4 0.013 - - 48 358
nuoranthene 1/4 0.014 - - 48 358
ButvlbenzvlDhthalate 214 0.011.{).019 1/3 0.008 NELA NELA
Di-n-butvlDhthalate 4/4 0.012 - 0.051 3/3 0.018 - 0.023 NELA NELA
Fluoranthene 3/4 0.017,{).02 1/3 0.004 0.6 3.6
Phenanthrene 3/4 O.cK17-O.cJ09 - - 0.225 138
Pvrene 3/4 0.018 - 0.027 2/3 0.005 035 2.2
U'-DDE
1/12
.001
-
-
II
0.002
0.015
Aluminum 4/4 551 - 18.600 3/3 518 - 2.610 NELA NELA
Arsenic 11/12 1.5 -75 2/5 1.1 - 3.9 33 8S
Barium 4/4 5.8 - 30 3/3 3.95 - 12.1 NELA NELA
1/4 057 1/3 027 NELA NELA
CadJnium 2112 0.94 - 2 - - 5 9
Calcium 4/4 19.800 - 197.000 313 121100 -1IB1IOO NELA NELA
Quomium 12112 1.8 - 40.2 5/5 1.6 - 9.15 80 145
Cobalt 1/4 3.2 1/3 0.56 NELA NELA
Coooer 10/12 33 - 45 415 2.3 - 8.7 70 390
Cvanide
Iron 12/12 2,010 - 28.000 5/5 156.5 - 5.830 201100 b 401IOOb
Lead 12/12 2.6 - 44 5/5 2.3-22 35 110
Malme5ium 4/4 229 - 1..630 3/3 318.5 - 588 NELA NELA
Mananese 4/4 8.7 - 43.4 3/3 12.4 - 13.5 460b 1100 b
Mercury 5/12 O.lJ12 - 0.17 - - 0.15 13
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Record of Decision
Davie Landfill Site
Page 26
TABLE 5.4: CONTAMINANTS DETECI'ED IN SEDIMENT (continued)
Site-Related Samples
Sec:liment
Analyte
£R-L
£R-M
1.2 - 2.S 30 50
150 NEl.A NEl.A
1 2.2
68.45 - 339 NEl.A NEl.A
1.55 - 17.1 NEl.A NEl.A
5.5 - 38 120 270
Ni~eI. 5.5 - 13.7
Potassium 717
SHver 1.2
Sodium 103 - 456
Vanadium 3.1 -77.2
ZJnc 4.7 - 160
1
3
5/5
ER-L = NOAA effects range low.
ER-M = NOAA effects range median.
NEl.A = No effect level. available.
. Based 011 total polynudear aromatic hycbocarbons.
b OMOE 0990) Sediment Quality Guideline, low effect level. and severe effect level..
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TABLE S-S: CONTAMINANTS DETECTED IN SOIL
Site-Reblted Samoles Bacbro nd Samoles
Frequacy RaDge of Frequacy RaDge of
Surface Soil ADalyte I>eted2d Detected
of COD~.Jr:ons of ~.Jr:ons
Detection (m Detection _.1fi{1f.4i~~~Wi}!_jlfj[ifl1jfg~..'dt.£%l:i!~~~MfJi~tt'i!f~~Uit~tllillirit*i1.18RWkfj
Aluminum 2/2 1.470- 2.670 2/2 1560- 1.180
Antimonv 1/2 92 - -
ArseniC 2/8 1.0- 4.9 112 12
Barium 2/2 24.0 - 24.1 2/2 1.4 - 3.3
Cadmium 2/8 004 - 0.5 - -
Calcium 2/2 158 000 - 183.000 2/2 1.880 - 30.400
Oromium 8/8 6.5 - 8.8 2/2 4.9 - 5.1
Cobalt 2/2 0.4 - 0.6 1/2 0.8
CwPer 6/8 2.6- 55.8 - -
Iron 8/8 460- 2.130 2/2 S43 - 989
Lead 7/8 1.4 - 9.1 212 1.4 - 1.5
Mae:nesium 2/2 1 140 - 1 190 2/2 65.4 - 131
ManDllese 2/2 15.8 - 23.9 2/2 2.9 - 6.4
Mercurv 5/8 0.03 - 02 - -
Nickel 2/8 22 - 4.5 1/2 1.4
PotassiUm 2/2 182 - 248 1/2 70.9
Silver 2/8 1.0 - 2.4 1/2 0.44
Sodium 2/2 151 - 297 2/2 10.3 -45.9
Vanadium 2/2 5.9 - 10.6 2/2 2.4 - 4.1
Zinc 7/8 4.6 -47.6 2/2 22 -3:7
Ethvlbenzene 1/8 0.004 - -
Xvlenes 1/8 0.012 - -
-~".Th~1ffJftitll~1i~~~.~.~~ .:.:._m~Mt*%i_f.fJf.fJ2ttB~lfiIT_4t.%.i'nrA.E[Wl:
Aoenaohlhene 1/2 0J117 -
Benzo(b)f]uoranlhene 2/2 0.007 - 0.015 - -
Benzo(Ic)fluoranlhene 1/2 0.012 - -
BenzoCa>ovrene 1/2 0.011 - -
bis(2~vlhexvl)Phthalate 212 0.081-022 212 o.OI.{).(M
ButvlbenzvlDhthaJate 2/2 0.012-0.016 2/2 0.007-0.011
DIbenzofuran 1/2 0.02 - -
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TABLE 5-5:
CONTAMINANTS DETECTED IN SOIL (continued)
Site-Related Samnles
Baebro ad SamDles
Range of Range of
S.....Jt... SoU & --1v6. Freqaen- DetiCted Frequency Detected
_ee ftD8&.1- of -J Coneentratioaa of CoaeentratioD8
Detec:tion (m~' Detec:tion bit2ik'"J
~~;~"¥~~~~~~;~~~@~!__~;Ii~_8i_llli:m:~;m~~[~W&~l!f:mil:m;;fu1m:~Mr¥:iliOOtl
1.2-Dich1orobenzene 1/2
1A-Dic:hJorobenzene
Di-n-butvlDhthaiate
Di-
_L~thaJate
1/2
2/2
112
2/2
1/2
1/2
1/2
2/2
212
0.014
0.062
0.m5 - 0.059
0.15
0.008 - 0.01
0.m5
0.1
0.25
0.004 - 0.015
0.011 - 0.019
-
-
-
-
2/2
0.027 - 0.1X32
-
-
Fluorantbene
Fluorene
2-MethvlnaDhthalene
1/2 0.004
- -
- -
- -
1/2 0.004
112 0.004
NaDhthalene
Phenanthrene
Pvrene
alDha-OIlordaDe
ordane
-
1/2
1/2
2/8
0.0033
0.003
0.0014 - 0.0018
-
-
-
U' -DDE
- = There was no measurement above the detection limit.
112fL = mi~s per liter
NIl. = Not Applicable
-
-
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6.0
SUMMARY OF SITE RISK
6.1
Risk Assessment Overview
CERCLA directs EP A to conduct a Baseline Risk Assessment (BRA) to determine
whether a superfund site poses a current or potential threat to human health and the
environment in the absence of any remedial action. The baseline risk assessment
provides the basis for determining whether or not remedial action is necessary and
the justification for performing remedial action.
The risk assessment is based on the data gathered in the Remedilll InvesHgatipn Report
(CDM,1993) and includes analyses of samples of groundwater, surface water,
sediment, and surface soil. Estimates of current risks are based on this investigation
and in the absence of any site-specific remediation, future risk estimates are based on
the assumption that current soil and ground water chemical concentrations will
persist. Sections 6.2 through 6.6 address the risk assessment evaluation for human
health. Section 6.7 describes the potential impacts on aquatic and terrestrial life
associated with contamination at the Davie Landfill Site.
6.2
Contaminants of Potential Concern (COPCs) to Human Health
6.2.1 Screening Criteria
The chemicals measured in the various environmental media during the RI were
evaluated for inclusion as chemicals of potential concern in the risk assessment by
application of screening criteria. The screening criteria which resulted in elimination
of chemicals included the following:
.
Non-carcinogenic chemicals detected in a medium at a frequency of less
than five percent may be deleted;
.
Inorganic contaminant concentrations less than two times greater than
the average detected value of the respective background sample may be
deleted;
.
Essential nutrients present at low concentrations (ie., only slightly
elevated above naturally occurring levels) and only toxic at very high
doses may be deleted; and
Non-carcinogenic chemicals that through an analysis of toxicity and
concentration contribute less than one percent of the total risk may be
deleted.
.
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As a result of applying the above listed criteria, Table 6-1 lists the contaminants of
potential concern (COPC) associated with the Davie Landfill Site. The ch~cals
listed in Table 6-1 are of greatest concern because of their toxicity, their relation to
background concentrations, their prevalence onsite, and the likelihood of human
exposure.
6.2.2 Contaminants of Potential Concem in Ground Water
Monitoring well duster MW-22 (Figure 5-3) is upgradient of the Site and provided
background ground water quality data. No inorganic chemicals could be eliminated
from the ground water pathway based on the two times rule because all monitoring
well data either exceeded two times the background .levels or background levels were
"non-detect". Five naturally occurring essential nutrients were eliminated because
they were only slightly elevated above two times background levels; they are
essential human nutrients; and they are toxic only at very high doses. Seventeen
contaminants were eliminated by the concentration-toxicity screening.
Twenty chemicals reported in the downgradient and cross-gradient monitoring wells
meet the COPC criteria (Table 6-1). These were evaluated in the quantitative risk
assessment, butit should be noted that concentrations for a number of cQntaminants
listed are below the drinking water standards or MCLs for these paramet~.
6.2.3 Contaminants of Potential Concem in Soils
All analytical soil data were used in the identification of COPes in soils. The
background location used in the risk assessment was selected as a sampling site in
which soil was undisturbed by either dairy farming or landfill activities. Three
inorganics were eliminated based on a comparison to background levels. One
inorganic was eliminated as an essential human nutrient that is only toxic at very
high doses. Fourteen contaminants were eliminated through the concentration
toxicity screening. Twenty chemicals reported in the soil meet the COPC criteria
(Table 6-1). These were evaluated in the quantitative risk assessment.
6.2.4 Contaminants of Potential Concem in Surface Water
The surface water from Lakes 1 and 2 and the nature pond (former sludge lagoon)
were evaluated together since these waterways are interconnected. The surface water
from Lake 3 was evaluated separately, as was the surface water from the canals
adjacent to the Site. Background surface water sample locations included SW-7 and
SW-14 located at the Boy Scout lake and SW-12 located approximately 1.5 miles west
of the landfill in the C-ll Canal. .
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TABLE 6-1: CONTAMINANTS OF POTENTIAL CONCERN
Cont8mlnanls Ground Soil Surface Water Surface Water Sediment Sediment Sediment
Water (Lake. 1,2 Ie (Canal.) (Lake 1,2 Ie (Lake 3) (Canals)
Pond) I Pond)
INORGANICS
Aluminum X X X X
Antimony X X
ArseNc X X X
Barium X X X X
Beryllium X X X
Cadmium X X
CuomJum(toIsD X X X X
Cobalt X X
Copper X X X X X
Cyanide X X
Lead X X X X X
Manganese X X X
Mercury X X X X
Nickel X X X X
SOver X
ThalUum X
Vanadium X "-..-. X X X
1Jnc X X X
SIiMI.VOUmB ORGANICS
8enzo(a)pyrene X
8enzo(b)8uOI'8nthene X X
Benzo(k)ftuoranthene X X
BIs(2-EthyJhexyl)phthalate X X X X X r
I,4-Dlchlorobenzene X X . . X
Isophorone X
r.[
i2.
l~~
;1'1:
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TABLE ~1: CONTAMINANTS OF POTENTIAL CONCERN (continued)
Contamlnanl8 Ground Soil Surface Water Surface Water Sediment Sediment Sediment
Water (Laket1,2 . (Canall) (Lake 1,2. (Lake 3) (Canlll)
Pond) Pond)
VOLATILB ORGANICS
Acetone X
Carbon DIsu1fIcIe X X I
OIJorolonn X
Vinyl Ododde X
PESTICIDES
aJpha-BHC (Undane Isomer) X
delta-BHC (Undane Isomer) X
aJpha-Ollordane X
pmma-OIJordane X
4.4'.DDD X
4,4'-DDB X X
4.4' -DOT X
-........
~po
s. I
" D.
i2.
fgi,
~lif
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Lakes 12 and Nature Pond
Seven inorganics were eliminated based on the two times background rule. One
naturally occurring essential nutrient was eliminated. One contaminant was
eliminated based on the concentration toxicity screening. Eight contaminants
reported in the. surface water of Lakes 1 and 2 and the nature pond meet the COPC
criteria (Table 6-1). .
Lake 3 .
Only one contaminant (iron) was detected in the surface water of Lake 3, and it was
eliminated from further consideration because it is an essential nutrients. Therefore,
no contaminants reported in the surface water of Lake 3 meet the COPC criteria
(Table 6-1).
Canals i.e. C-ll and ditch on Bo Scout Road
Five inorganics were eliminated based on the two times background rule. One
naturally occurring essential nutrient was eliminated. No contaminants were
eliminated based on the concentration toxicity screening. Seven contaminants
reported in the surface water of the C-ll canal and the ditch on Boy Scout Road meet
the COPC criteria (Table 6-1). .
6.2.5 Contaminants of Potential Concem in Sediments
The sediments from Lakes 1 and 2 and the nature pond were evaluated together
since these waterways are interconnected The sediment from Lake 3 was evaluated
separately, as was the sediment from the canals adjacent to the Site. Background
sediment sample locations included SD-1 and SD-2 on Imagination Farms, SD-7 and
SD-14 located at the Boy Scout lake, and SD-12 located approximately 1.5 miles west
of the landfill in the C-11 Canal.
Lakes 12 and Nature Pond
One inorganic was eliminated based on the two times background rule. Five
naturally occurring essential nutrients were eliminated. Ten contaminants were
eliminated based on the concentration toxicity screening. Sixteen contaminants
reported in the sediment of Lakes 1 and 2 and the nature pond meet the COPC
criteria (Table 6-1).
Lake 3
Five inorganics were eliminated based on the two times background rule. No
contaminants were eliminated based on the basis of being essential nutrients or due
to the concentration toxicity screening. Three contaminants reported in the sediment
of Lake 3 meet the COPC criteria (Table 6-1).. .
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Davie Landfill Site
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Canals i.e. C-ll and ditch on Bo Scout Road
Seven inorganics were eliminated based on the two times background rule. One
naturally occurring essential nutrient was eliminated. Six contaminants were
eliminated based on the concentration toxicity saeening. Nine contaminants reported
in the sediment of the C-l1 canal and the ditch on Boy Scout Road meet the COPC
criteria (Table 6-1).
6.3
Exposure Assessment
6.3.1 Introduction
The purpose of the exposure assessment is to estimate the magnitude of potential
human exposure to the contaminants of potential concern at the Davie Landfill Site.
Whether a contaminant is actually a concern to human health and the environment
depends upon the likelihood of exposure, i.e. whether the exposure pathway is
currently complete or could be complete in. the future. A complete exposure
pathway (a sequence of events leading to contact with a contaminant) is defmed by
the following four elements:
.
a source and mechanism of release from the source;
.
a transport medium (e.g., surface water, air) and mechanisms of
migration through the medium;
.
the presence or potential presence of a receptor at the exposure point;
and
a route of exposure (ingestion, inhalation, dermal absorption).
If all four elements are present, the pathway is considered complete.
.
6.3.2 Source, Mechanism of Release, an~ Transport
The source of contamination at the Site remains the trash and sanitary landfill
mounds. The former sludge lagoon no longer appears to be a significant source of
contamination. The two major constituent release and transport mechanisms
potentially.associated with the Site are as follows:
.
The infiltration of precipitation through the landfill and the percolation
of the resulting leachate into the ground water; and
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Release of leachate to surface waters, sediments, and soils through
leachate seeps.
Because of the present landfill cover, the active landfill gas recovery system, and the
minimal presence of VOCS in the contaminated media, exposure to constituents in air
transport is not considered significant at the Site.
.
6.3.3 Potential Receptors and Routes of Exposure
Current
Currently, there are workers onsite conducting the closure of the landfill. There is,
also, the possibility of trespassers gaining access to the Site by scaling the perimeter
fence. These two populations could be exposed to surface soil, surface water, and
sediments on the Site. Therefore, it was assumed that a hypothetical youth trespasser
(age 7-16) and worker could be potentially exposed to the contaminants through
dermal contact with and ingestion of contaminants in surface water, sediment, and
surficial soils.
Future -
Exposure to contaminated ground water was not evaluated for current residents
living adjacent to the Site, since residents within areas of known contamination have
been placed on municipal water. However, future residential exposure to ground
water could occur if contaminated ground water spreads to new areas downgradient
of the Site or if new wells are placed in contaminated ground water. In addition,
area residents could potentially be exposed to surface water, surficial soils, and
sediments if the landfill is opened as a park, which is the current plan for future land
use at the Site. The future resident scenario was evaluated in order to evaluate these
risks.
The County worker population can be receptors for contaminants in surface water
and soils when onsite maintenance work is performed. The risk to these workers
should be the same as that evaluated for the current worker.
6.3.4 Pathways
Table 6-2 outlines the potential pathways for both current and future use exposure
scenarios. All possible pathways were first hypothesized and evaluated for
completeness. The current pathways represent exposure pathways which could exist
under current Site conditions while the future pathways represent exposure pathways
which could exist, in the future, if the current exposure conditions change.
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TABLE 6-2
POTENTIAL EXPOSURE PATHWAYSIROUTES
~ Saurto Receptor ~ Patb-JI
Media
GIOIIIId W.. Fatme R.esicleot (CIiJd 8Dd Aduh) l.Juaeatioo of driDkiDg water
2. ID1IIIuiaa of vOCa re1eued to
indoor air
3. Dermal COIII8Ct
Sedimeat C'uneat Trespasser (YoadI, 7-16) 1. 1nc:idemaJ. iDgeatioo
Adah WOlter 2. Dermal coo&8I:t
Surface W.. C'uneat Trespasser (YoadI, 7-16) 1. Incideatal iDgeatioo
Adah WOlter 2. Dermal COIII8Ct
Surface SaiJJ C'umat Trespasser (YoadI, 7-16) 1. Incideatal iDgeatioo
Adah WOlter 2. Dermal COIII8Ct
Funn Resicleot (CIiJd and Aduh) 1. Dermal COIII8Ct
2. Incideatal iDgestioo
6.3.5 Exposure Point Concentrations and Dose Assumptions .
The 95 percent upper confidence limit (UCL) on the arithmetic mean was calculated
and used as the exposure concentration of contaminants of potential concern in
each-media evaluated, unless it exceeded the maximum concentration. Where this
occurred, the maximum concentration was used as the exposure point concentration
for that contaminant. Exposures point concentrations are summarized in Section 6.4,
Tables 6-3 through 6-6.
The exposure point concentrCitions for each of the contaminants of potential concern
and the exposure assumptions for each pathway were used to estimate the chronic
daily intakes for the potentially complete pathways. EP A guidance was used to
determine parameters needed to calculate chronic daily intakes. The guidance
addresses assumptions with regard to drinking water ingestion, inhalation of VOCs
while showering, incidental ingestion of soil, dermal contact with soil, incidental
water ingestion while wading, and dermal adsorption while wading.
.6.4
Toxicitv Assessment
The purpose of the toxicity assessment is to assign toxicity values (criteria) to each
contaminant evaluated in the risk assessment. The toxicity values are used in
conjunction with the estimated doses to which a human could be exposed to evaluate
the potential human health risk associated with each contaminant. In evaluating
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potential. health risks, both carcinogenic and non-carcinogenic health eHects were
considered.
Cancer slope factors (CSFs) are developed by EP A under the assumption that the risk
of cancer from a given chemical is linearly related to dose. CSFs are developed from
laboratory animal studies or human epidemiology studies and classified according to
route of administration. The CSF is expressed as (mg/kg/ dayj! and when multiplied
by the lifetime average daily dose expressed as mg/kg/ day will provide an estimate
of the probability that the dose will cause cancer during the lifetime of the exposed
individual. This inaeased cancer risk is expressed by terms such as 1x1~.. This is a
hypothetical estimate of the upper limit of risk based on very conservative or health
protective assumptions and statistical evaluations of data from animal experiments or
from epidemiological studies. To state that a chemical exposure causes a 1x10"'
added upper limit risk of cancer means that if 1,000,000 people are exposed one
additional incident of cancer is expected to occur. The calculations and assumptions
yield an upper limit estimate which assures that no more than one case is expected
and, in fact, there may be no additional cases of cancer. USEP A policy has
established that an upper limit cancer risk falling below or wit:h4\ the range of 1xlO"'
to 1x1()"4 is acceptable.
The toxicity criteria used to evaluate potential non-carcinogenic health effects are
reference doses (RIDs). The RID is expressed as mg/kg/ day and represents that
dose that has been determined by experimental animal tests or by human observation
to not cause adverse health effects, even if the dose is continued for a lifetime. The
procedure used to estimate this dose incorporates safety or uncertainty factors that
assume it will not over-estimate this safe dose. If the estimated exposure to a
chemical expressed as mg/kg/day is less than the RID, the exposure is not expected
to cause any non-carcinogenic effects, even if the exposure is continued for a lifetime.
In other words, if the estimated dose divided by the RID is less than 1.0, ~re is no
concern for adverse non-carcinogenic effects.
Exposure Point Concentrations and Toxicity Potency Factors used to calculate Human
Health Risks are summarized in Tables 6-3 through 6-6.
6.5
Risk Characterization
To evaluate the estimated cancer risks, a risk level lower than lxl~ is considered a
minimal or de minimis risk. The risk range of 1xlO"' to 1x1()"4 is an acceptable risk
range and would not be expected to reqUire a response action. A risk level greater
than 1x1()"4 would be evaluated further and a remedial action to deaease the
estimated risk considered.
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TABLE 6-3: CONTAMINANTS OF POTENTIAL CONCERN IN GROUND WATER AND
TOXICITY ASSESSMENT
Background
Toxicity
CSF 31/(D\g/kg/day) RID 2 D\g/ltg/day
Media and Clem1c:a1
INORGANICS:
AlmninUll\ 18/19 500 24.6 - 62 NC NC
Antimony 3119 10.2 ND NC .0004
Alsellic: 4/69 5.0 5:J 1:75 .oom
BariUll\ 19/19 19.2 15.8 - 31.2 NC .W
BeryDiwn 3/19 om ND 4.3 .005
CJuoJniuJn (total)4 '12/69 1.5 ND NC .005
Cobalt 2/19 9.5 ND NC NC
Cyanide 14/69 9.2 ND NC .a2
Lead 4169 2.6 ND N1V N1V
Manganese 19/19 43.1 21.2 - 39.5 NC .005
ThaDiUll\ 1/19 2.8 ND NC N1V
VOLATILE ORGANICS:
Acetone 8/69 48.9 6.0-16 NC .1
Carbon Disulfide 29169 12.6 4.0-5.0 NC .1
CIlorobenzelle 8/69 3.6 ND NC .02
CIlorofonn 1/69 3.5 ND .0061 .01
Vinyl CIloride 5/69 3.0 ND 1.9 NC
SEMI-VOLA'l1US: 19/19 1.4
bis(2-ethylhexy1)phtbaJate 0.4-0.5 .014 .a2
I,4-Did1lorobenzene 10/19 2.0 ND .a24 .3
Isophorone 1/19 0.08 ND .0009S .2
PfSTIODfS/PCBs: 1169 0.02S ND .24 .Im
4,4-DDD
4,4-DDT 2/69 0.05 NO .34 .0005
Expo8are PaIIIt CAI.~.t.d..I. dellnsl . the ~ upper Cllllfldence dImdc81_1km or the muIInwn de-.I CllllC!fttratton, whkbewr Is IIa.
2 Ref8ace ~ (RIDt) haw been dewIoped by EPA lor Indkadng die potsIliII for ~ health ee- fram ~ ID dIemkaIt erhllllIn& non-c:an:Inopnk ~
Adaplld fram USEPA IRIS. 1993 and USEPA He8lth ar- SoumnaIy T"" OED 92IJO.6.303 U992).
3 CuIa!r potency '-n (CPFs) haw been doMIoped lor estIznallllg -- I1IeIIzne cancer rIsb 880CIated with expa8U1e to po-dally c:an:InogenIc c:IIo!InDls. Aclapll!cl from
U5EPA IRIS, 1993 and U5EPA Health U- SamIIuIry Table, OED 9200.6-3113 U992). anIs8 oIIIerwt8e naIed.
4 &poIare PoInt CAI.~..t..d6..ft lor total CIIroIl\lalno 8DXIcIty lor CIIroIlllalll VI.
ND = Not Detected
NC = Not of Conc:em
N1V = No Toxicity Data AvaDab1e
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TABLE 6-4: CONTAMINANTS OF POTENTIAL CONCERN IN SOIL
AND TOXICITY ASSESSMENT
Background
Toxicity
CSF 3 1 /C1ng/kg/ clay) RID 2 mg/kg/ clay
Media and Otemical
INORGANICS:
Antimony 112 9.2 ND NC .0004
Arsenic 2/8 2.3 1.2 1.75 .rom
Barium 212 24.1 1.4-3.3 NC .W
Cadmium 2/8 0.36 ND NC. .(1)]
Copper 6/8 55.8 ND NC NC
Lead 7/8 9.1 1.4-15 N1V N1V
Manganese 2/2 23.9 2.9-6.4 NC .14
Mercury 5/8 0.13 ND NC .rom
Nidtel 2/8 2.9 1.4 NC .m
Silver 2/8 1.3 0.44 NC .005
Vanadium 212 10.6 2.4..1.1 NC JXJ7
7mc 7/8 47.6 2.2-3.7 NC .3
SEMI-VOLATILES: 0.015 .73
Benzo(b)fluoranthene 2/2 ND NC
Benzo(lc)£luoranthene 1/2 0.012 ND .73 NC
Benzo(a)pyrene 1/2 0.011 ND 7.3 NC
l,4-Didllorobenzene 1/2 0.062 ND .m4 .3
PE5I1aDFS/PCBs: O.oem
alpha-Ollordane 1/2 ND 1.3 .00006
pmma-Otlordane 1/2 O.cm ND 1.3 .00006
4,4'..DDE 2/8 0.0018 ND .34 .fXX1l
2
Exposure Pvlnt ConcemntIon defined . the 9SYO DJIP!I' aIIIIIcIeDa! cMadc:al _tIon at the IIIIIXIznam deIec:Ied alllCelltlatkm,. wNcbew!r 18 leas.
Reference do8os (RfDo) have been dewIoped by EPA for Indtca1lng the potmtI8I for ~ II8Ith e«- fnIIII expa8IIft to c:heInIc:aII edIIIttIns 1IOII<8I'd>--semc e«-.
Adaplll!d from USEPA IRIS, 1993 8IId USEPA He81th E«- 5aDanary TIbW. OERR 92OCJ.6.3(D (1992).
3
Cancer P'tI!N.'f r-m (C"F8) have been cIewIoped for eltlmatlftg - IIfedDIe -- rIIb 88OcI8I8I with apc81Ift to potentially .....:h.ogerdc dwmb1s. Adapted from
USEPA IRIS, 199311ftd USEPA He81th ~ SamInIay T8bIe, OERR 92110.6-303 (1992). II1II88 otberwI8e noeed.
NO = Not Detected
NC = Not of Concern
N1V = No Toxicity Data Available
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TABLE 6-5: CONTAMINANTS OF POTENTIAL CONCERN IN SURFACE WATER AND
TOXICITY ASSESSMENT
Background
Toxicity
CSF 31/(mg/kg/day) RID 2 mg/kg/day
Media and 0emic:a1
INORGANICSc
Al\lDlinum 3/3 505 21.4-118 NC NC
Berymmn 1/3 1.05 1.2 4.2 .005
~ 1/10 2.6 ND NC NC
Vanadium 3/3 20:7 4 NC .3
VOLAm.E ORGANICSc
Carbon Disulfide 2/10 5.3 21 NC .1
SEMI-VOLA11LFS
Bis(2-ethylhexyl)phthaJate 3/3 0:7 0.2-0.3 .014 .02
PFSTICIDES/PCBs 0.012
alpha-BHC 1/10 ND 6.3 NC
delta-BHC 1/10 0.015 ND NC NC
INORGANICSc
Al\lDlinum 2/3 105 21.4-178
Barium 3/3 62.1 4.32
~ 1/7 9:7 ND
Cyanide 1/7 1.6 ND
Lead 2/7 4.6 ND
Vanadium 2/3 15.4 4
SEMI-VOLA11LES:
bisa-ethylhexy1)phthaJate 1/3 3.0 0.2-0.3
2
Rsmlllble Mulmam ExpoIQft defined . the ~ upper mnftdmce c:!ImdI:8l mncmtratilm 01' the IIIIIXIInam detecII!d CDIID!IIIntIon. ~ Is lei.
Re&ftnce cs- atm.) haw been dewJoped by EPA lor indicating the P*fttIaI for adwae hmlth eH«b from eIpDI1De III chemicals echilltlng JIOIH3f'do.oser* eff-.
AdapIed from USEPA IRIS, 1993 and USEPA Health E«- SammIIt Table,. OERR 92IJO.6.303 (1992).
:I
Qncer poII!IIq '-IS (Q'N) haw been developed Cor estimating - 1Ile!IIne I:aIM8 rtsb assocIaIed with expoawe to potmtlally cardnogenIc dwmiI:aJs. Adapted from
USEPA IRIS, 1993 and USEPA Health ElIecI8 SwIuNIy TabM. OED 9200.6.W3 awn. IIIIIsa othenof8e --
ND = Not Detected
NC = Not of Concern
N'lV = No Toxicity Data AvaiJable
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TABLE 6-6: CONTAMINANTS OF POTENTIAL CONCERN IN SEDIMENT
AND TOXICITY ASSESSMENT
Media and 0\emica1
BackgroWKI
CSF 31/CDlg/kg/day)
INORGANICS:
Aluminum 2/2 18,600 51~2,610 NC NC
Barium 2/2 ao 3.95-12.1 NC .w.
Beryllium 1/2 057 0.27 4.2 .005
Cadmium 2/6 2.0 ND NC .001
OIromium (totalrt 6/6 38.3 1.6-9.15 NC .005
Cobalt 1/2 3.2 0.56 NC NC
Copper 5/6 29 2.3-8j NC NC
Lead 6/6 44 2.3-22 N'IV N'IV
Manganese 2/2 43.4 12.4-135 NC .14
Mercury 3/6 0.17 ND NC .0003
Nid
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TABLE 6-6: CONTAMINANTS OF POTENTIAL CONCERN IN SEDIMENT
AND TOXICITY ASSESSMENT (continued)
Media and Ctemic:al
Background
Toxicity
<:sF 31/Cmg/kg/day) RID 2 mg/ltg/day
Copper 3/4 45 2.3-8.7 NC NC
Lead 4/4 29 2.3-22 N1V N'IV
Mercury 1/4 0.17 ND NC .rom
Nidtel 1/4 10 1.2-2.5 NC .02
Zinc 4/4 100 5.5-38 NC .3
SEMI.VOLA11LPS
Di-n-butylphlhalate 2/2 .024 0.018-0.023 NC .1
PESTICIDES/PCBs
4,4' -DDE 1/4 .001 ND .34 .fXX17
2
Exposure PoInt CollCl!ftlr8tion defined as 1M 95" upper confidence d\emicII con_lion, or the IDaXfmwn concentration detl!Ctl!d, whlchewr Is less.
Ref8ena! dooes CRfDs) have bien cIewIoped by EPA Cor indicating tile potential Cor advene health effects from exposure II> c:hemIca1s echIbttlng no~ effecIs.
Adapted from TJSEPA IRIS, 1993 md USEPA Health EffectI5wNn8ry Table, OaR 92tJ0.6.303 (1992).
3
Cancer potellC)' facIon (CPFs) have been developed Cor estimating - lifetime cancer risks aaocIated with exposure to potl!lltiaDy carcinogenic chemicals.. Adapted from
USEPA IRIS, 1993 and USEPA Health Effects SuIIunaJy Table, OED 9200.6-303 (1992). unless otherwise noted.
4
Exposure point concentration Cor total Chromllllll; toxicity Cor ChromillDl VI.
ND :: Not Detected
NC :: Not of Concern
N'IV = No Toxicity Data Available
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A hazard quotient (HQ) of less than unity (1.0) indicates that the exposures are not
expected to cause adverse health effects. An HQ greater than one (1.0) requires
further evaluation. For example, although the hazard quotients of the contaminants
present are added and exceed 1.0, further evaluation may show that their toxicities
are not additive because each contaminant affects different target organs. When the
total effect is evaluated on an effect and target organ basis the hazard index of the
separate chemicals may be at acceptable levels.
Carcinogenic risks and non-carcinogenic hazards were evaluated for potential
exposures to media-specific contaminants of potential concern in surface soil, surface
water, sediment and ground water. Receptor populations were workers, trespassers
and area residents that could, theoretically, use the ground water for a household
water source.
Estimated potential exposure to contaminants of concern in surface water, surface soil
and surface sediments are within EPA's acceptable carcinogenic risk range or
non-carcinogenic hazard.
Estimated potential added cancer risks and non-carcinogenic hazards from the use of
contaminated ground water for household use are outside EPA's-acceptable range. .
The estimated cancer risk exceedances are related to vinyl chloride and arsenic
concentrations. The arsenic. concentration is well below the MCL. .The maximum
vinyl chloride concentrations in downgradient wells exceeds the primary drinking
water MCL by 1 to 2 ug/L. The estimated non-carcinogen risk exceedance is related
to antimony concentrations. Antimony was measured at 15 to 19 ug/L while the
primary drinking water MCL is 6 ug/L. A summary of the risks is provided in Table
6-7.
TABLE 6-7: SUMMARY OF UNACCEPTABLE RISK
THROUGH GROUND WATER INGESTION a
Anlimon
Arsenic 1 x 10"
4 x 1()'4
CIlorofonn 4 x 10"
Cuomium NA
Man ese NA
Vin 1 CIloride 1 x 10"
l,4-Dichlorobenzene 1 x 10"
2.0
1.0
0:7
0.5
0.1
0.6
0.2
TOTAL 3 x 1()'4 4.0 2.0
!hf,f.imf}t.1!..lflm1:i!~V:~~~~~~~.~~~~_M.
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6.6
Identification of Uncertainties
Uncertainty is inherent in the risk assessment process. Each of the three components
of risk assessment (data evaluation, exposure assumptions, and toxicity criteria)
contribute uncertainties. For example, the assumption that ground water and soil
concentrations will remain constant over time highly overestimates the lifetime
exposure. Contaminants dissolve in rainwater and migrate from the soil, degrade as
a result of biological action (organics), are dispersed and diluted in ground water,
and otherwise are subject to a variety of attenuation processes. In addition; for a.risk
to exist, both significant exposure to the pollutants of concern and toxicity at these
predicted exposure levels must exist. The toxicological uncertainties primarily relate
to the methodology by which carcinogenic and noncarcinogenic criteria (i.e., cancer
slope factors and reference doses) are developed. In general, the methodology
currently used to develop cancer slope factors and reference doses is very
conservative, and likely results in an overestimation of human toxicity and resultant
risk.
The use of conservative assumptions throughout the risk assessment process are
believed to result in an over-estimate of human health risk. Therefore, actual risk
may be lower than the estimates presented here but are unlikely to be gr~ater.
6.7
Ecolopca1 Evaluation
6.7.1 Overview
The risk to the environment is determined through the assessment of potentially
adverse effects to ecosystems and populations resulting from Site-related
contamination using qualitative methods. Ground water, soil, surface water, and
sediments throughout the landfill area were sampled to determine the extent of
contamination, as described in Section 5. Ground water discharge to surface water at
the canal is presumed to occur at the Site; therefore, ground water data was used to
address ecological concerns. Contaminants detected in each media are listed in Table
5-1 through 5-5.
6.7.2 Contaminants of Potential Concem
All organic parameters detected above method detection limits were considered to be
contaminants of potential concern to ecological life. Inorganics at concentrations
greater than two times the mean background concentration were considered
contaminants of potential concern. Since all inorganic parameters detected in ground'
water exceeded twice the mean background values, all inorganic parameters were
considered to be chemicals of potential concern. In soils, three contaminants
(aluminum, chromium, and cobalt) were eliminated as contaminants of potential
concern based on background screening. For Lakes 1 and 2 and the pond, inorganic
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parameters in surface water eliminated based on background screening included
barium, calcium, iron, magnesium, manganese, sodium, and zinc. For Lake 3, iron in
surface water was eliminated based on background screening. No inorganic
parameters in the surface water of the C-11 Canal and the Boy Scout Road Ditch
were eliminated based on background screening. Arsenic in sediments of Lakes 1
and 2 and the pond was eliminated based on background screening. For sediment in
Lake 3, arsenic, copper, iron, lead, and zinc were eliminated based on background
screening. In the C-11 Canal and Boy Scout Road Ditch, aluminum, barium, calcium,
magnesium, manganese, sodium, and vanadium were eliminated based on
background screening. The remaining inorganic parameters were carried through the
ecological risk assessment as contaminants of potential concern.
6.7.3 EXposure Assessment
Davie Landfill is a disturbed site impacted by past and present human activities.
Habitat losses undoubtedly occurred when the Site was originally developed and as
construction and maintenance activities continued. With the creation of Lakes 1, 2,
and 3 and the remediation of the former sludge lagoon, available aquatic habitats
were increased. However, Lakes 1,2, and 3 provided limited shallow water habitat
because the edges of the lakes dropped off sharply into deep water. During closure
of the landfill,. the shores of the lakes are being regraded to provide a more natural
shoreline, suitable for aquatic life and accessible to terrestrial wildlife. In addition,
dairy cows from adjacent properties have impacted the shoreline habitats at the Site.
Construction of a new fence around the Site as part of the landfill closure plan is
expected to alleviate the habitat destruction caused by the dairy cows. .
Two species may be a potential concern at this Site. The bald eagle (HaliJleetus
leucocephalus), a federal endangered species, is known to use areas near the Site,
especially the Everglades area to the wesl In addition, a species of special concern to
the state, the eastern burrowing owl (Athene cunicularia), has been reported on the
Site. A list of federally listed threatened and endangered species and category 1 and
2 candidates for federal listing in Broward County is provided in Table 6-8. None of
the species on this list were identified onsite during the ecological characterization
conducted as part of the remedial investigation. Lists of observed (January 1993) and
reported fauna at the Davie Landfill are provided in Table 6-9.
The target receptors were divided into two main categories: terrestrial and aquatic.
Since clean soils have been placed over the Site and former leachate seeps redirected
by the low-permeability cover, exposure of terrestrial wildlife through ingestion of
contaminated soils and vegetation and uptake of soil contaminants by plant roots are
no longer deemed a viable pathways. Thus, no risk is expected for these terrestrial
receptors. The threat to burrowing animals is not expected to be significant because
the landfill cover is approximately two-feet thick.
..
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TABLE 6-8: FEDERALLY LISTED THREATENED AND ENDANGERED SPEOES
AND CATEGORY 1 AND 2 CANDIDATES FOR FEDERAL USTING
IN BROWARD COUNTY
SC1ent1fic Name
Status
Common Name
Amphibians and Reptiles
Alliqator mississicoiensis
Caretta caretta caretta
Chelonia ~ mvdas
Dermochelvs coriacea
Drvmarchon corais couDeri
Eretmochelvs imbricata
imbricata
GoDherus Dol vphemus
LeDidochelvs ~
ODhisaurus COmDressus
Pituoohis melanoleucus
muqitus
pseudobranchus striatus
lustricolus
Rana areolata aeSODUS
Scelooorus woodi
Birds
Ammodramus maritima
Charadrius melodus
Dendroica kirtlandii
Falco Dere
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TABLE 6-9: OBSERVED OANUARY 1993) AND REPORTED FAUNA,
BROWARD COUNTY LANDFILL, DAVIE, FLORIDA
COMMON NAME SCIENT1FIC NAME COMMENTS
INVERTEBRATES .
Apbida Order H-.-, family ApItJ4idM OBSERVED
IIecdc8 Order CA/qInrI. &milia C«d1vlJi4M, OBSERVED
(Lad""'p, GrouIId Bccdca. WeeWa) 0urIbiIIM. ~ (acIuIIa)
Buaerf1ica Order~ OBSERVED
(Zebra, Zebra SwaIIowIaiI, Ibree uaidcalificd 1pCCica) (aclulla IIId - lpCCiea uaidcatiflClt larvae)
CicIdu Order H_pImI, family ~ OBSERVED
(lIIIidcnIiflClt lpCCiea) (8du118)
0amIcI1Iic8 (N.now-wift&cd) Order OtlMiII4, family C-I~ OBSERVED
(8C'ICn1ll1lidcalificd lpCCica) (acIuIIa)
Dnpllic8 Order OtlMiII4, varioua Camilica OBSERVED
(_rallI1IidcaIiflClt 1pCCica) (acIuIIa)
Fire AsII8 ~,-- OBSERVED
- (.duJu, pupae, ---)
FGe. Order DiptDa, familia MIIKIIlM, OBSERVED
(H-, Ct'8ftC, MOIqUiIo, llllidcaliticd 1pCCica) TIpIIIi4M. (aduIIa)
OIlid4lu, CIe.
Graubappcn Order OnMpImI OBSERVED
(-m II1Iidcalifacd 1pCCiea)
.
Hooey 8eea ApIs JMlllfna OBSERVED
Lcafboppcts Order HOIIIDfMrG, family OMlkm*,- OBSERVED
(lIIIidcnIifacd lpCCiea)
Mollaa Order Lqi4tJptDrI OBSERVED
(two unidentified lpCCica) (aclulla IIId - lpCCiea uaidcaliflCd 1uY8e)
SII8i1a (aquatic) CIua~ OBSERVED
Spidcn Order.ilrGlvGe. family"""", CIe. OBSERVED
(Aqiope, Orb WC8VCI', uaidcalificd 1pCCiea) (acluba IIId weba)
Spilllcbup Ordcr~. family ~ OBSERVED
(uaidallified 8pCCiea)
0- SliDtbup ~ bU.rJre OBSERVED
Wupa V"'.. OBSERVED
(tIaree uaidcatificd apoeia) (8daIIa IIId aat8)
w.. Striden Ordcr "-lpIna, CaIIIi1y Gnri4II6 OBSERVED
(Ulli4eftI;racd lpCCiea) (MuIu)
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TABLE 6-9: OBSERVED (JANUARY 1993) AND REPORTED FAUNA,
BROWARD COUNTY LANDFILL, DAVIE, FLOIqpA
(continued)
COMMON NAME SCIEN11FIC NAME COMMENTS
f1SII
~.. M~ ,OImt1iIIa REPORTED
Leu& IGJIjIitb HelD'llllllMf«-tJ OBSERVED
(ptaumpCive) (pouibl)' FIIIIIIMJIg 'P.) (OI!II immature lpCCimco)
MCMqUiIoWa GGmbIaiII MUnooId OBSERVED
"AMPBIJIIANS "" "" ." ..
. " ""
Ftop &1M 'P. OBSERVED
(uaidcalifscd) (pouibl)' R. Illriftllarl4) (acIuIta)
SouIbem Leopard Frop &IM~ OBSERVED
(aclulla. immatUre and maIIIre larvae, CII')
REPT1LES ." .<::-" "::""
. ". ..
Cubao Browo AAoIca - MDIi6 ",m"lrei OBSERVED
(aclulta aad immalUre)
Florida w... SIIata Ner0di4/tI#:UIM pkIi-n OBSERVED
(rJucc aduIIa)
Greca ADoIc MDIi6~ OBSERVED
(ainalc adult)
SoWI...--. Five-&lcd Stiak ~~ OBSERVED
(ainglc adak)
Turda ~~. /On.oItnrtt1ft 1Hrrui. OBSERVED
(praumpIivc Must. Mud, 01' Coaccr lpCCica) IC. 611brvbrwn. 01' 0IrpetrrJ' jIorld.tINI (_II protrUding from ...al&r only)
BIRDS . .." ". . "" ..
AmcricaD KaIIeI FGlco"""wrlla OBSERVED
Bald Eqlc R~~ REPORTED
Bara Owl l;to IIlIM REPORTED
IIIaI:It VuIIunI 0-",. -- OBSERVED
CallIe E,ret 1lIIbtIkw". OBSERVED
c- QaJ1iauIc (Moocbca) GtIIIiIutI4 dII«OpfI6 OBSERVED
c- CiftIUIId Doft ~"..",.. OBSERVED
c-T- sr-. IIl1vIttIiJ OBSERVED
Earaa IIunowiaI Owl ""'- ~ REPORTED
Orca& Blue HmID MIa Itero4IG OBSERVED
(CoaImoG and White Pbue) ,
Orca& E,ret ~.u- OBSERVED
Orca& Hcncd Owl ..~ \ REPORTED
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Record of Decision
Davie landfill Site
Page 49
TABLE 6-9: OBSERVED OANUARY 1993) AND REPORTED FAUNA,
BROWARD COUNTY LANDFILL, DAVIE, FLORIDA
(continued)
COMMON NAME SCIENTIFIC NAME COMMENTS
KiDdccr ~ YOCijervs OBSERVED
LiaIc Blue H- E:,MItI conuIeG OBSERVED
Moat Parsbct MyIDpdIIiI ~ OBSERVED
(p1aumpUw)
Mounaiaa Dove ZeNridG MGCnNUII OBSERVED
PadIiaa Birda o.w P-mJ- HEARD
(varioua 1pCCia) (uaidcatifd canl)
Riag_bd Duck AyrIIycr coIJIuV OBSERVED
Spenowa Family EmbnizJdM OBSERVED
(1IIIicIcaIi1icd)
Tufte)' Vultuft 0IIJuura.",. OBSERVED
-
MAMMALS .
MUllclicl Famil)' MIISUliIIM OBSERVED
(Ullidcntifd) (ttacb oaI)')
Raccooa Proeyort IDIDr REPORTED
(ttacb obaerwd)
RocIcat o.w~ OBSERVED
(Ullidcntifaed) . (burrows oat)')
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Record of Decision
Davie Landfill Site
Page 50
A qualitative exposure assessment was used for aquatic biota living in the water
column (aquatic community) and those living in or on the bottom sediments (benthic
community).
The exposure point concentration is the concentration of a contaminant to which an
ecological receptor is expected to be exposed. The average exposure point
concentration was calculated as the arithmetic mean of the contaminant
concentrations. Undetected values were not incorporated into the calculation of
average concentrations. The average and maximum concentrations for ground water,
surface water, and sediment contaminants were used in the risk characterization.
6.7.4 Toxicity Assessment
6.7.4.1
Ground Water/Surface Water
As a means of characterizing aquatic toxicity, the EP A has developed water quality
criteria (WQC) for the protection of 95 percent of all aquatic life where sufficient data
are available. The Region IV Waste Management Division has established screening
levels for surface water at hazardous waste sites, primarily based upon the Ambient
Water Quality Criteria. Exceedance of these screening levels might indicate a
potential for adverse ecological effects (depending upon factors such as frequency of
detection, degree cjf exceedance, etc.), thus indicating a need for more site-specific
ecological investigations, such as toxicity testing. In addition, Florida Department of
Environmental Protection (FDEP) has established its own water quality criteria, which
vary depending on use classification for the surface water body. Class ill criteria
were established to protect recreation and the propagation and maintenance of a
healthy, well-balanced population of fish and wildlife. For those contaminants that
did not have established WQC, acute and chronic toxicity values were based on a
percentage of median lethal concentrations for various organisms obtained from
available literature.
6.7.4.2
Sediments
The toxicity of contaminants to aquatic biota living in or near the bottom sediments
(benthic community) can be assessed by comparing sediment contaminant
concentrations to sediment biological effect ranges published by the National Oceanic
and Atmospheric Administration (NOAA). The NOAA sediment effects range values
were developed to determine concentrations of contaminants which may result in
adverse ecological effects. These values are based upon available sediment data
collected primarily in marine and estuarine environments throughout the United
States. The Effects Range-Low (ER-L) values represent the lower tenth percentile of
the range of concentrations in which effects were observed or predicted. The Effects
Range-Median (ER-M) values represent the 50th percentile concentrations.
.
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Record of Decision
Davie Landfill Site
Page S1
For iron and manganese the Ontario Ministry of the Environment (OMOE) sediment
quality guidelines were used to determine risks. In the OMOE guidelines, the
Lowest Effect Level is the level of sediment contamination that can be tolerated by
the majority of benthic organisms. The Severe Effects Level is the level of sediment
contamination at which pronounced disturbance of the sediment dwelling community
is expected. .
For organic non-polar chemicals lacking biological effects levels, an alternative
approach was applied using the Equilibrium Partitioning (EP) Approach to evaluate
the potential for adverse effects associated with exposure to impacted sediments.
6.7.5 Risk Characterization
6.7.5.1
Ground Water/Surface Water
Comparison of the concentrations of contaminants of potential concern with federal
Water Quality Criteria (WQC), regional screening values, and state water quality
standards, was used to assess the likelihood of adverse effects of ground water and
surface water to aquatic life:
.
Numerous contaminants in ground water (presuming ground water discharges
to surface water) exceeded federal WQC, regional screening values, and state
water quality standards. As impacted ground water migrates downgradient
toward a surface water discharge point, a significant loss of VOCs is expected
through volatilization, retardation, and degradation. Inorganics are expected
to adsorb to sediment and organic materials within the aquifer such that their
surface water concentrations also will be reduced. Therefore, it is conservative
to assume that aquatic life will be effected by ground water contamination.
Concentrations of carbon disulfide, bis(2-ethylhexyl)phthalate, and aluminum,
in surface water of Lakes 1 and 2 and the pond, exceed WQC for these
contaminants. It should be noted that the maximum detected concentrations of
carbon disulfide and bis(2-ethylhexyl)phthalate in Lakes 1 and 2 and the pond
do not exceed two times the average background concentration, so their
presence may. not be Site-related. .
.
.
In the C-ll Canal and the Boy Scout Road Ditch, the maximum detected
concentration of bis(2-ethylhexyl)phthalate, aluminum, cyanide, and iron
equaled or exceeded federal, regional, and/or state chronic WQC.
Water quality criteria were not available for all detected contaminants; therefore, the
contribution of all the contaminants of potential concern could not be evaluated.
Despite the absence of some criteria, the results show a limited potential for both
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Davie landfill Site
Page 52
chronic and acute adverse effects to occur to aquatic life inhabiting Lakes 1 and 2, the
pond, the C-ll Canal, and the Boy Scout Road ditch.
6.7.5.2
Sediment
To assess potential adverse effects on benthic organisms from exposure to potentially
toxic sediment, contaminants of potential concern identified in sediments were
compared with available NOAA sediment biological effect ranges, Ontario Ministry
of the Environment (OMOE) sediment quality guidelines, and Equilibrium
Partitioning concentrations:
.
All sediment contaminant concentrations in all waterbodies fell below the ER-
M levels. In Lakes 1 and 2 and the pond, maximum detected concentrations of
lead, mercury, silver, and zinc exceeded the ER-L value but not the ER-M
value, indicating a low potential for ~cological effects.
.
There were no exceedances of the biological effects levels for contaminants
detected in Lake 3.
The Il'WCiIUum detected concentration of mercury in sediments of the C-ll
Canal and the Boy Scout Road ditch exceed the ER-L value for this constituent
but not the ER-M value, indicating a low potential for ecological effects. The
maximum detected concentration of iron exceeded the OMOE Lowest Effect
Level. The detected concentration of butylbenzylphthalate exceeded the .
calculated sediment concentration (based upon equilibrium partitioning).
Sediment biological effects levels were not available for all the detected contaminants;
therefore, the contribution of all the contaminants of potential concern could not be
evaluated. These results suggest, based on available data, that a slight potential
exists for adverse effects to occur to benthic and aquatic life inhabiting Lakes 1 and 2,
the pond, the C-ll Canal, and the Boy Scout Road ditch.
.
6.7.6 Uncertainty Analysis
The main sources of uncertainty associated with this ecological evaluation can be
attributed to the following:
.
Environmental chemistry and sample analysis,
.
Exposure Assumptions, and
.
Toxicity criteria.
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Davie Landfill Site
Page 53
While environmental parameter estimation and exposure assumptions provide
uncertainty, the primary sources of uncertainty are the interpretation and application
of available toxicological data.
7.0
DESCRIPTION OF ALTERNATIVES
7.1
Performance Standards
Estimated potential human exposure to Site contaminants in surface water, surface
soil, and surface sediments do not result in unacceptable cancer or non cancer risks at
the Davie Landfill Site. However, the estimated potential cancer and non-cancer risks
from exposure to ground water are above EPA's cleanup target cancer risk range and
an HQ above 1. Cosure of the landfill and completion of the cover system is
expected to reduce contamination from the landfill and potential risks to human
health. Contaminants in ground water at levels above ARARs are listed in Table 7-1.
There is a low potential risk associated with exposure of aquatic life to contamination
in surface water and sediments in onsite water bodies. Cosure of the landfill and
completion of the cover system is expected to reduce contamination from the landfill
and potential risks to ecological life. . .
Actual or threatened releases of hazardous substances from this Site, if not addressed
by implementation of the response action selected in this ROD, may present an
imminent and substantial endangerment to public health, welfare, or the
environment.
The Feasibility Study Report evaluated possible alternatives for remediation of
conditions at the Davie Landfill Site. A total of three (3) alternatives have been
established for detailed analysis consideration. These alternatives were selected to
provide a range of remedial actions for the Site.
TABLE 7-1: SUMMARY OF REMEDIAL ACfION PERFORMANCE STANDARDS
(Ground water)
Contaminant Concentrations Detected (pg/D Background (pg/D Perfonnance Standard
Mean Max (pg/D
Vinyl OIIoride 2.2 3 ND 1 a
Antimony 16.7 19.1 ND . 6b
a- State of F10rida Primary Drinking Water Level
b- Safe Drin1cing Water Act MaJdmum Contaminant Leve1
(MCL).
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Record of Decision
Davie Landfill Site
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Alternative No.1: No Action
7.2
The no action alternative was developed as required by the National Oil and
Hazardous Substances Pollution Contingency Plan (NCP), the regulation
implementing the Superfund law. It is used as a baseline for comparing other
alternatives. Under this alternative, EP A would take no action to minimize the
impact ground water contamination has on the area. There is no cost associated with
this alternative because no additional activities would .be conducted.
However, at Davie Landfill, a number of County and State actions are being executed
at the Site which should reduce contamination in the ground water. Broward County
is in the process of closing the landfill in accordance with the requirements of FDEP
closure permit number SF06-143540. Oosure is expected to eliminate the source of
contamination at the Site. The permit is subject to 15 general conditions and 25
specific conditions including the following:
.
monitoring ground water at the Site for twenty years,
.
providing written proof that the Site is zoned for parks and recreation, and
.
providing-public potable water and sewer to the park.
Natural attenuation of the contaminants in ground water is anticipated after closure
of the landfill is complete. Broward County estimates that over $14 million have
been invested or committed for closure of the landfill in accordance with the permit.
Approximately $1.3 million of that total is associated with ground water monitoring,
zoning the Site, and potable water and sewer extension to the Site.
In addition to the actions required under the permit, the State Health Department
monitors residential wells near the Site for contamination and urges residents with
wells affected by contamination from the Site to connect to a public water supply
using funds provided by the State of Florida Water Quality Assurance Trust Fund.
Because this alternative would result in contaminants remaining onsite, CERCLA
requires that the Site. be reviewed every five years. If indicated by the review,
remedial actions would be implemented at that time to address the contaminated
ground water.
7.3
Alternative No.2. Natural Attenuation With Ground Water Monitoring
This remedial alternative involves action aimed at limiting exposure, and primarily
consists of the following: (1) natural attenuation of vinyl chloride and antimony;
(2) ground water monitoring; and (3) provision of alternative water to residences
with contaminated wells. These remedial activities are expected to limit contact with
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Record of Decision
Davie Landfill Site
Page 55
contaminated ground water in the vicinity of the Davie Landfill Site and includes
utilization of a comprehensive ground water monitoring plan to periodically evaluate
the quality of the ground water emanating from the Site.
A literature search was conducted during the FS to determine the length of time for
natural attenuation to decrease concentrations of vinyl chloride to below the MCL of
1 ug/L. Based on that search it was determined that vinyl chloride has a half-life
ranging from 8 weeks to 95 months. The highest concentration of vinyl chloride
detected at Davie Landfill was 3 ug/L; therefore, calculations indicate that a
maximum of 16 years may be required to reduce vinyl chloride concentrations to 0.75
ug/L, which is below the MCL.
No estimation of the time required for antimony to attenuate could be made because
antimony is a metal, is present in low concentrations in the ground water samples,
and is expected to adhere to soil particles rather than move with the ground water.
The suspected source for antimony is the incinerator ash buried in the trash landfill.
There is no direct exposure pathway to the ash or soil to which the antimony may
adhere. That is why the ash and soil do not need to be remediated. Natural
attenuation by adherence to soil is expected to be effective for antimony. .
A ground water monitOring progr~ would be performed to ensure that attenuation
is effective. Ground water would be monitored at wells along the perimeter of the
landfill (compliance wells), as well as in residential wells near the Site, unti1levels of
vinyl chloride and antimony reach performance standards (see Table 7-1). If vinyl
chloride is detected in residential wells at concentrations above 1 ug/L at least three
times, then a source for alternative water will be provided to affected residences.
Monitoring will contjnue for at least one year after the concentrations in all
monitoring wells decrease below the performance standards. Should any
concentrations above performance standards be detected within this post-remediation
monitoring period, actions would be taken to verify the contaminant levels, and if
verified, additional control measures may be evaluated.
The Site is being closed by Broward County under a permit with the State of Florida,
in accordance with the Florida Administrative Code, Chapter 17-701, Solid Waste
Management Facilities. The monitoring required under this remedy is being
conducted by Broward County in accordance with the FDEP closure permit.
Provision of public water to private well users with wells affected by Site-related
contamination is being provided through the State of Florida Water Quality
Assurance Trust Fund. The County is to provide EP A with quarterly reports which
include any ground water monitoring results for that period, residential well
monitoring results, and any provisions made to extend the public water supply.
Because all monitoring costs are included in County and State actions described
previously, no additional costs are anticipated for this action unless Broward County
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Record of Decision
Davie Landfill Site
Page 56
fails to perform the actions required by the permit. Ground water monitoring,
zoning the Site, and potable water and sewer extension to the Site are estimated at
$1.3 million. In addition, EP A estimates that up to $100,000 may be required over the
next sixteen years to provide public water to affected residents if the State Trust Fund
cannot be accessed.
7.4
Alternative No.3 - Ground Water Treatment
This alternative includes ground water extraction, physical/chemical treatment of the
extracted water, and discharge to surface water. A National Pollutant Discharge
Elimination System (NPDES) permit would be required to discharge treated ground
water to a surface water body located offsite. A ground water monitoring program
would be necessary to ensure that the ground water treatment system is effective and
that contaminants do not migrate.
A ground water model was used to determine the time required to circulate clean
ground water through the contamination zone and reduce contaminant levels below
cleanup goals. The model indicates it would take 12 years to reduce vinyl chloride
levels below cleanup goals and 146 years to reduce antimony levels. For the
purposes of the cost analysis a maximum of 30 years of extraction and treatment was
assumed During the remedial design (RD), treatability studies may be conducted, if
required, to determine the effectiveness of treatment on the extracted ground water.
Due to the existing low concentrations at the Site, extraction alone, through dilution,
may reduce contaminant concentrations to below discharge standards. Filtration to
remove the high iron content would likely be the only treatment that would be
necessary to meet surface water discharge standards. Final treatment methods would
be determined during the remedial design for the system. Any wastes generated
during the treatment process would be disposed of at a regulated facility. The actual
number of extraction wells required would be determined during the RD. For the
purposes of this analysis, three extraction wells were considered appropriate.
The estimated capital cost for a three well, 150 gpm extraction system is $2,490,000.
Operation and Maintenance costs for thirty years of operation are estimated at
$3,460,000. The total present worth cost of this remedy is estimated at $5,950,000.
8.0
SUMMARY OF THE COMPARATIVE ANALYSIS OF ALTERNATIVES
8.1
Statutory Balandn8 Criteria
This section of the ROD provides the basis for determining which alternative
provides the best balance with respect to the statutory balancing criteria in Section
121 of CERCLA, 42 U.s.C. ~ 9621, and in the NCP, 40 CFR ~ 300.430. The major
objective of the feasibility study (FS) was to develop, screen, and evaluate alternatives
for the remediation of the Davie Landfill Site. A wide variety of alternatives and
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Rec:ord of Decision
Davie Landfill Site
Page 57
technologies were identified as candidates to remediate the contamination at the
Davie Landfill Site. These were screened based on their feasibility with respect to the
contaminants present and the Site characteristics. After the initial screening, the
remaining alternatives/technologies were combined into potential remedial
alternative~ and evaluated in detail. The remedial alternative was selected from the
screening process using the following nine evaluation criteria:
.
overall protection of human health and the environment;
.
compliance with applicable relevant and appropriate requirements (ARARS);
.
long-term effectiveness and permanence;
reduction of toxicity, mobility, or volume of hazardous substances or
contaminants;
.
.
short-term effectiveness or the impacts a remedy might have on the
community, ~orkers, or the environment during the course of implementation;
.
implementability, that is, the administrative or technical capacity to carry out
the alternative;
.
cost-eHectiveness considering costs for construction, operation, and
maintenance of the alternative over the life of the project;
.
acceptance by the State, and
.
acceptance by the Community.
The NCP categorizes the nine criteria into three groups:
(1)
Threshold Criteria - overall protection of human health and the environment
and compliance with ARARs (or invoking a waiver) are threshold criteria that
must be satisfied in order for an alternative to be eligible for selection;
Primary Balancing Criteria - long-term effectiveness and permanence;
reduction of toxicity, mobility or volume; short-term effectiveness;
implementability and cost are primary balancing factors used to weigh major
trade-offs among alternative hazardous waste management strategies; and
(2)
(3)
Modifyini Criteria - state and community acceptance are modifying criteria
that are formally taken into account after pul;>lic comments are received on the .
proposed plan and incorporated into the ROD.
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Record of Decision
. -Davie Landfill Site
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The following analysis is a summary of the evaluation of alternatives for remediating
the Davie Landfill Superfund Site under each of the criteria. A comparison is made
between each of the alternatives for achievement of a specific criterion.
8.2
Threshold Criteria
8.2.1 Overall Protection of Human Health and the Environment
All of the alternatives, including No Action, shoUld provide some degree of
protection for human health and the environmenl Alternatives 1 and 2 include
ground water monitoring and natural attenuation to meet clean-up goals and public
water is provided to residents to protect human health. Alternative 3 would provide
protection of human health and the environment through active remediation of the
ground water.
8.2.2 Compliance With ARARs
The remedial action for the Davie Landfill Site, under Section 121{d) of CERCLA, -
must comply with federal and sta~ ~vironmentallaws that either are applicable or
relevant and appropriate (ARARs). Applicable requirements are those standards,
criteria or limitations promulgated under federal or state law that specifically address
a hazardous substance, pollutant, contaminant, remedial action, location, or other
circumstance at a CERCLA site. Relevant and appropriate requirements are those
that, while not applicable, still address problems or situations sufficiently similar to
those encountered at the Site and that their use is well suited to the particular site.
To-Be-Considered Criteria (TBCs) are non-promulgated advisories and guidance that
are not legally binding, but should be considered in determining the necessary level
of cleanup for protection of human health or the environment. While TBCs do not
have the status of ARARS, EPA's approach to determining if a remedial action is
protective of human health and the environment involves consideration of TBCs
along with ARARs. .
Location-specific ARARs are restrictions placed on the concentration of hazardous
substances or the conduct of activities solely on the basis of location. Examples of
location-specific ARARs include state and federal requirements to protect floodplains,
critical habitats, and wetlands, and solid and hazardous waste facility siting criteria.
Table 8-1 summarizes the potentiallocation-specific ARARs for the Davie Landfill
~te. .
Action-specific ARARs are technology- or activity-based requirements or limitations
on actions taken with respect to hazardous wastes. These requirements are triggered
by the particular remedial activities that are selected to accomplish a remedy. Since
there are usually several alternative actions for any remedial site, various
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Record of Decision
Davie Landfill Site
Page 59
requirements can be ARARs. Table 8-2 lists potential action-specific ARARs and
TBCs for the selected and contingency ground water remedy for the Davie Landfill
Site.
Chemical-specific ARARs are specific numerical quantity restrictions on individually-
listed contaminants in specific media. Examples of chemical-specific ARARs include
the MCLs specified under the Safe Drinking Water Act as well as the ambient water
quality criteria that are enumerated under the Oean Water Act. Because there are
usually numerous contaminants of potential concern for any remedial site, various
numerical quantity requirements can be ARARs. Table 8-31ists potential chemical-
specific ARARs for the Davie Landfill Site.
All alternatives will meet their respective ARARs. The ARARs that apply to this Site
include chemical, action, and location-specific ARARs. Alternatives 1 and 2 would
comply with all ARARS (i.e., federal and state Maximum Contaminant Levels
(MCLs» through monitoring and natural attenuation. The point of compliance would
be determined through the FDEP closure permit. Alternative 3 would meet all
ARARS (i.e., federal and state MCLs and surface water discharge requirements,
RCRA Subpart G, NPDES permitting requirements, etc.) through active ground water
remediation.
Long-term monitoring is required in all alternatives. Additional statistical analysis of
data will further substantiate the presence/absence of contaminants in ground water.
This long-term monitoring will provide the data necessary for a statistical .
determination of constituent concentrations in ground water. If it becomes apparent
that MCLs will not be met through attenuation, EPA, in consultation with FDEP, will
re-evaluate the effectiveness of the remedy.
8.3
Primary Balancing Criteria
8.3.1 Long-Term Effectiveness and Permanence
Alternative 3 provides the highest degree of long-term effectiveness and permanence
because this alternative uses treatment technologies to reduce hazards posed by the
contaminants in the ground water at the Landfill Site. Calculations indicate that
vinyl chloride concentrations could be reduced to cleanup levels (Table 7-1) after 12
years of ground water extraction; Aritimony concentrations are expected to take up to
146 years of ground water extraction before cleanup levels are attained.
Natural attenuation, as provided in Alternatives 1 and 2, also would be considered
. effective from a long-term standpoint. Calculations indicate that vinyl chloride
concentrations could be reduced to cleanup levels (Table 7-1) through natural
attenuation in up to 16 years. No estimate of the time required for antimony to
attenuate could be made at this time; however, the levels of antimony detected are
-------
TABLE 8-1: POTENTIAL LOCATION SPECIFIC ARAKS AND TCDs
fmaL
ReIOUlO8 Con8elY8t1on and Recovery
AlA (RCRA). .. emended
.
RCM location 8tand8rd8
EndIngeI8d 8pecIn AlA
ann Wat8r hA
DI8dg8 and FI A8qWem8nta
(SectIon 4(4)
RIve,. and He1bor8 Act of 1888
(SectIon 10 "-nnl)
. Wldema.. hA
National ¥A1d1f8 Refuge Syat8m
42 use 8901
40 CFR 264.18(b)
18 use 1531
33 use SectIon 1251
40 CFR 230
33 use SectIon 403
18 use 1311
18 use 688
&0 CFR 27
Atrutment,etorage,ordlsposal(TSD)faclftymLl8tbe If .oId. 818 generat8d dumg treatment, the
..1gnecI, conatrucf8d, operated, and mahtahed 80 potential disposal faclfty ooutd be located wlthh the
avoid WI8hcM on . 1QO.year ftoodplah. 1QO.year ftoodplih. RequIrement.. I8levart and
appruptfat8.
Requfre. action to ooneelV8 endangered apecl8. or
threetened ape.., IncUfIng ooneullaUon with the
Depar1ment of Int,rbr. .
Requlnt. pennlt ford\8charge 01 dl8dged or m mateltal
Into aquatlnnvtonment.
Requfrel pennlt for 8tructu",. or work In or allecthg
navigable watera. .
Area mLl8t be admhlstel8d to leave It un.mpall8d a.
wlldema.. and will p",eerve It a. a wlldema...
Re.trfct8 actMtI.. wlthh National \WeI1'e Refuge..
No allernattie wID be _eloped that would
dlecharge dredged or OJ mateltallnto an aquatJo
environment.
No alternative lnvolY.. wolle that would alleet 8
navigable waterway.
No wlldeme.. al8a. exist on.1Ie or adjacent to the
aile.
No wlldlfe ",fuge a",a exist Of1aMe or adjacent to
the llIe. .
r. f.
i~
!,f.
-------
TABLE 8-2: POTENTIAL ACI10N SPECIFIC ARARS AND TCBs
EIIaa.
--.... eM""'" MIf~A~
~I .. MII8fIfIIif
~ of HlZ8rdilu8w....
.......... for 8tanIa8, 1'NIIm8rI.1IId
DIIpOIII of HuIIdou8 WIIt8
ACM I.wId DIIpOIII""".
~forca.nnloft, .....
TrIn8poIIIdan IIId DIIpoeIt of HIDrdoU8
W""
ftMft W8I8r Aft lIMA'
AmIIfpnI Wlf8rGud1 QIIIfII (AWOC)
.,... AYIIIIIIII ~ (BAT) T8CtInoIof1
NdIIIIII PcIIMInI DIIcNrge EIImhdIon
""'"' (NPDEI) hmIII RIguf8IIonI
DI8c:tI8rgI mull be oonIIIItnI wIh till
I'8qIMrnInII of. w- 0UIIIIy M8181g11M11t
PIIn IppIW8d bJ EPA
DIId\wg8 mull nat Incn8I8 oorAImIIlIIIt
00\IlO8l6II1II0118 In oIrIII8lU1f8C8.....
42 use 81101, 8805, 8112, 8124,
-
40 em ael
FIdInII I8qUhmenII 'or duslllcatlon IIId . IOIIcIa ..' C11ft1'1118d tIItougII grounctftIer
Id."lIlIclllon of IIuIrdou8 waltlL 1r'8IIInMII, . II . poIlIIIIeI ARAR.
R8gIIIt. atorage. 1rMInIn, chpoIII, IIId . IOIIcIa .. 0If*III8d ~ grounctWIIer
operIIIIon of IIu.wdoua ..,.. Ir8IImInI. . II . poIenIIaI MAR.
PnMdH lor pruper cIspoaI of reguteI8cI Pat8ntIIIIy 811 MAR . meIIII NmCIVII II perl of
conIImInIIItIIlouncIln 1IudgI. 1IIIc:t8d 1'III'IICIy.
AeguIII. atonIOI. Ir8n8poItIIIon, and opIIIIIIon of May be 811 MAR . meIIII ~ II pII1 of
1IazIrdou8..,. generalorl. 1IIIc:t8d I'III'IICIy eM to I/udgI ptOdud..
40 em 284
40 em aes
40 em Part 288
40 em -
40 em 284
s:I use 8IctIon 1251.1378
40 em PIIIt IS1
811. atllIta lor wet.r quaIIIy II8Md OIl IOIdcIIy 10 TIle AWOC lor CIrgInIO IIId InorgenIo CCIIIIIIMIantl
aquIIIIo 0111111111118 and humen h88IIh. .. poIlII!IIIIy Nlwlllt IIId 1IppnIpfI8I. II dlChlrlll
of 1r88t8d grounctnter II requInId.
u.. of b8I8 ....... tlCllncllogy -1OIIIIcaIIy PClt8lCI8IIy IIppIIc8bII I trMtecl grounct«ater II
adllMIJIe II NqUlred 10 control cll8cftarge of IOXIo cIIc:tIarged 10 . pIMcIy ownId IIeatmInI wOlb
poIIuIanI8 '0 POTW. (POTW). '
. u.. of In ...... 1IdInoIogy IOOIICII'IIIoIa, POCInIIIIIy ~ 11ruIed 8IIIvInI1s dsdlaiged
ac:IIIMtJIt lor toxto poIIuIantl cllc:tl1IgId to IUIf8C8 10 8111f1lC8 wet.r.
wet...
4OCf!R 122
40 em 122 8_1t C
40 em 122
DlldlII'II8I11U81 OOIIIPI'I willi EPA~
Wiler Qu8IIIy MfInIOIIMtII Plan.
Pof~1Iy ~ . graunctIrII.r Is dtdIervecllO
eurllIC8'wet.r.
8IctIon 121 (cI)(2)(8)(111)
8118ct8d NIIIIChIIdIon mustlS18tlllsll . 8IIndIrd Pofenllllfy IIIPftc8IJI8 . gIOUIICtt¥If.r Is dlsdll/VICf to
of conIrOI to maintain IUrllIC8 wat.r qulllly. eurllIC8 wet..
&,:10
~.a '
i~
{!f:
...lrtJ
-------
. TABLE 8-2: POTENTIAL ACI10N SPECIFIC ARARS AND TCBs (continued)
NIIIcINII PrtnIJy 8ftd 8ecIondIIr AmIII8nI All
0UIIIIr 8t8ncIIrd8
NIIIcINII EmII8Iaftt 8f8ndIrdI tor HaI8dM
All PoIIUnI8 (NE8HAP8)
AlIUI8~
P--IIttMI ".,.".""".."" .A~
8WI
..;
~ 1ft It"".,. W.,.,.",1W A¥IdI W.fII(
Dull"'" I!MItrI8lldt .
AnItd8 ~8t~ fItaJHIIuIh
AnItd8 Rurf8,. W., nu.tIIv e.tt8118
,urfltft8 Waf" ~MIIIIIIt and U----
Ad lAWIM'
AIItit W"""'dI~~M
40 CfR P8It 80
SIt. pImIIy and NCOfIdIIy 8Jr 8IIIIdIrd8 II IMI8
10 prurtc:t fMIIo hMIIII and fMIIo ....
PnI¥IdI8 eml8slon8 8tIndIud for tIuIrdou8 8Jt
po/Iutant8 for wtllctllIO 8mbIInt U ~ 8tIIIIdIrd
ixI8t8.
RequIM noIIIIcaIIon IIId perfonnlllCl lilting by
CJWII8I' 01' Clpendor.
PrMtH 8114'" ruIt8 lor II8ncIInO Ip8CIIIo cII8mIo
- for 811. wortI818 cbtng 1'81118C1118dM1188.
40 CfR P8It e.
40 CfR eo (8""'" A)
II CfR 1810 P8It 120
FAC 1T-52O
EIt8bII8h8. ClftlUllCMatlr 1l1lldanf8.
. iiiilJnahe. llII1ace watlr quality 1IIndard8 and
gu/d8I!nI. for aIIoWIbIIlIVeft of metII8 8IId PAH.
(loxto 0I'gIII\1c8) In 8Ulf1Cl WIIlr U88d for r8C18l11on
IIId pnIpIgIIIIon and malntllllllOl of 8IIIIIIII" WIll-
btIIIIOId population of II8h IIId wIkIIf..
RIguIaI. 8Ulf1Cl WII.r dIIcIIIrgu IIId cIIcIIIrgt.
108 POTW.
E8fIbII8ht. l1l8I no w81188 ... to lit cbdIlI'gIId to
any WIllIS at tilt 8IaI. WI\tIoUI being given tilt
InNIIm8nI nlClSlllty 10 prurtd tilt btnIIIc:ItI \118 of
IIIdI WIIIfS.
FAC 17-302.530
FAC 17043
FAC t7-au
May lit I818vIlll 01' 1IppI'IIpItat. . 0II8II. trNImIIII
unlll .. pIIt at I8I'ftIIIIIIICtIoII.
May lit I818vIlll 01' 1JIPft1PfaI. . 0II8II. IrNlment
"""I .. pIIt Of I'II'IIIdIIIICtIoII.
May be I'IIIVIIII 01' 1ppnIpIIIk. . 0II8II. trNImIIII
unll8 .. pIIt of I8IIIICI8I 8CtIon.
ttIIIIII and 8114.., ~.. ...1pIIIIc8IIIt 10 811
poItnIIIIl8I'ftIIIIII acIIon8.
May be tppIIcIbIt llIouId graunct«atlr dedlargt
(I.... "'nJtc::llon) be 1Ittcttd.
May be IppIIc8bIt llIouId llI1flCl watlr cIIldIl/VI be
Nlec:ttd.
MI' be an ARAR lhould IrNImInt IIId dIdIargt 10
8Ulf1Cl wattr be Nlec:ttd.
No wtllllnds tXIII ntar lilt lilt.
r
p:la
~!
fe.
l!~
~ r; I:
-------
TABLE 8.2: POTENTIAL ACI10N SPECIFIC ARARS AND TCBs (continued)
RJI:P A11r~ 1'!IlItIMI......,..
00Vtm8 lie COIIItrudIon CIIIInJedlon WIII8 10 II1II AppIIc8IIIe 8IIouId inJectIon be 8118decl.
Infed8d ffuId8 rwmIfn In lie Infedld zone 8IId II1II
IIIIIppftIV'Id lnI.n:tIInge beIwttn ..pr... It
proIIIIIIecI.
E8I8tIII8fIH .", qtII/IIy 8Iandanf8 wIIIIln lie 1f8t.. May be an MAR IIrIIImtnt CIII oIrpIItI fnIm CWIIII.
Ir8IImtnI ,",II II required IMtng lIIIItdIaIIon.
FAC CIIIpItt 17-2
&.KIL
CIIr filS......
FAC 1M2
E8I8tIII8fIH POTW dI8dwgIlmIIl.
May be IIJPIICIbIt 8IIouId POTW dlldllI'Dt be
88Itct1d.
...
-."''''.''",
,,~
~. !
i2.
';Pgf
' .
tf
-------
TABLE 8-3: POTENTIAL CHEMICAL SPECIFIC ARARS AND TCBs
8IIIIL .
.... DItnIdng WIItr Ad
NIIIIonII PIImIIy DIInIdng W- 8tIndIrdI
MaInun ~ L8VII GoIII
a.n w.., Act
AmbI8nI W"" QUIIIy Crl8ItII
RtlauIC8 COUlllndIOn IIId RIoowIJ Act
(ACRA), ullMlldld
RCRA CIRIunctnrtr PlatICtlcln
. .
II..""'~
AIIMI DNIna w.r.r llfaftdlldl
AIIMI~R--
40 use 8ecIIon aoo
40 CFR PM 141
PWIk:8tIon L ... 88-388. 100
8181. 842 (1l1li8)
a3 use 8Ic:IIOn 125'.'318
40 CFR PIIt 131
42 use 8905, .'2. 8924, 882S
40 CFR Pili 284
FAa 17.550
FAC 17-520, 17.522
E8IIbII8tIH IIuIIfI.bued lllandanliforlMJllOWIIIlrlYlC1IIII
(1IIIIIdmIIn 0DIUIIIInInt ""III).
E8I8IIIIIIht1 dltnllfng wat., quaIIIy Q08I8 ... 81 ..,. of no
Icnown or ~Id acMIlII heIIIII 8118d8.
8111 aft.. for WIIIlr qulllly b888d on toIdcIIy to 8qUIIIo
0I'IIIIII1ImI1IId human li8liiii.
PftIII/fdI8 for grouncfW8Ilr prallCIIon 8I1IIdam. gentrII
I'IIOIIIIoIfng ~11, 8IIcI1lCtlnlc8l18qu1rem1nt1.
E8IIbII8tIH drfnldng WIIIlr 8CandanI8 rot pII)IJo w.."
IYICIllllIn FIofIdL
EII8IIII8fIH grouncfW8Ilr quIII\y It8IIcIInI8.
The MClI for 0f'gIIII0 IIId inorganic contaminants
.. IppIIc:tIIIt 10 '" pmdwIIlr conI8mInIIld by
the "'1 8Ince . II . patlllllll drinking wllir IOIRI.
PftIpOMd MClo. for 0IgIIII1c and InoIgInIc
contamlnanla ... ~ 10 till grounctw8l.r
pattnllllly UMd for drtnIdng WIIIlr.
The AWOC for organic IIId inorganic contaminants
... IppIIc:tIIIt 10 1118 "'1.
The RCRA ~., monllOllng rwquIl'lmlnll...
I'8I8v8nIIIId ICIPftIIII'IIII for grounctffllir .. till 1111.
App/IcIbII 10 fIOUIIdWItlr.. ItI8 1111.
App/IcIbII 10 gI'OUIIdwIIlr II ItI8 .11..
i',o
~. R
i~
i.!r
t.jf :I
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Record of Decision
Davie Landfill Site
Page 6S
relatively low. Antimony is a metal and is expected to adhere to soil particles rather
than move with the ground water. For these reasons natural attenuation is expected
to be effective for antimony. Because these remedies may result in contaminants
remaining onsite, a 5-year review would be necessary to verify that the remedies
included in these alternatives remain protective.
. -
8.3.2 Reduction of Toxicity, Mobility, or Volume Through Treatment
Coupled with the source containment alternative (OU1 ROD), completed in 1989,
Alternative 2 will result in permanent remediation of the ground water and will pose
no continued risk to the surrounding public or the environment upon completion.
Alternative'2 will rely on natural attenuation and dilution to reduce the toxicity,
mobility, and volume of .ground water contaminants at the Site and attain ARARs
within 16 years (Section 7.3). Because Alternatives 1 and 2 do not involve any
construction, they will not generate any waste residuals.
Alternative 3 provides for active ground water remediation through extraction and
discharge to surface water with some treatment to meet discharge standards. In
Alternative 3, toxicity, mobility, and volume of contaminated ground water are
reduced through remediation. Alternatives 1 and 2 do not provide for ground water
treatment, but rather attenuation of contaminants over time. Alternative 3 best
satisfies CERCLA's statutory preference for treatment and use of treatment to reduce
toxicity, mobility, and volume of contaminants.
8.3.3 Short-Term Effectiveness
Alternatives 1 and 2, which require no construction, are expected to have the greatest
short-term effectiveness because implementation presents no risk to workers,
community, and the environment. Alternative 3 also is effective in the short-term.
The installation of ground water extraction wells may impose risks through
disturbing the soil and ground water, however, this is not expected to pose any
short-term environmental or public health hazards.
8.3.4 Implementability
The implementability of an alternative is based on technical feasibility and the
availability of services and materials. Alternative 1 would be the simplest to
. implement Materials, services, and capabilities are readily available for maintenance
of the landfill cover system and monitoring through the FDEP closure permit
Periodic maintenance of the cover should provide reliability in the future. The
ground water monitoring program would determine the effectiveness of attenuation
of the contaminants in ground water. Alternative 2 would be only slightly less
simple to implement than Alternative 1, because it requires EP A to remain involved
with the Site for a period of time to ensure that contaminant levels meet ARARs, it
does not require construction and the obtaining of permits. Alternative 3 is the most
p
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Record of Decision
Davie Landfill Site
Page 66
difficult to implement, and includes ground water extraction, treatment and discharge
to surface water. A National Pollutant Discharge Elimination System (NPDFS)
permit is required for discharges offsite. Treatability testing may be required to
define the design parameters for these processes.
8.3.5 Cost
Alternatives 1 and 2 have no present worth cost because EP A would not require any
additional actions beyond those required for landfill closure. If Broward County
stopped performing work under the State of Florida Permit, the cost for Alternative 2
would increase to approximately $1.3 million. If the State trust fund is not accessed
to provide public water to affected residents, the cost for Alternative 2 could increase
by another $100,000. Alternative 3 has an estimated present worth cost of $5,950,000,
including O&M costs. The present worth value represents the total cost of the
remediation expressed in today's dollars. These estimates are based on a 5% interest
rate.
I TABLE 8-4: COMPARISON OF COSTS I
Alternative Present.worth COst Capital Cost Operation and
Maintenance Cost
1. No-Action $0 $0 $0
2. Natural Attenuation and $0 $0 $0
Ground water Monitoring
(cost if no FDEP permit) ($1,400,000) ($ 100,(00) ($1,300,00)
3. Ground water Treatment $ 5,950,000 $ 2,490,000 $ 3,460,000
8.4
Modifvin~ Criteria
8.4.1 State Acceptance
The State of Florida, as represented by the Florida Department of Environmental
Protection (FDEP), has been the support agency during the Remedial Investigation
and Feasibility Study (RI/FS) process for the Davie Landfill Site. In accordance with
40 C.F.R. ~ 300.430, FDEP as the support agency, has provided input during this
process by reviewing and providing comments to EP A on all major documents in the
Administrative Record Based upon comments received from FDEP, it is expected
that written concurrence will be forthcoming; however, a letter formally
recommending concurrence with EPA's selected remedy has not yet been received.
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Record of Decision
Davie Landfill Site
Page 67
8.4.2 Community Acceptance
Based on comments expressed at the May 19, 1994, public meeting and receipt of 6
written comments during the comment period, it appears that the Davie community
generally agrees with Alternative .2 as the selected remedy. Specific responses to
issues raised by the community can be found in Appendix A, The Responsiveness
Summary.
9.0
SUMMARY OF SELEerED REMEDY
Based upon the comparison of alternatives in the feasibility study (FS) and upon
consideration of the requirements of CERCLA, the NCP, the detailed analysis of
alternatives and public and state comments, EP A has selected Alternative 2 for this
Site. The selected alternative for the Davie Landfill Site is consistent with the
requirements of Section 121 of CERCLA and the NCP. Based on the information
available at this time, the selected alternative represents the best balance among the
criteria used to evaluate remedies. The selected alternative will reduce the mobility,
toxicity, and volume of contaminated ground water at the Site. In addition, the
selected alternative is protective of human health and the environment, will att~ all
federal and state ARARs, is cost-effective and utilizes permanent solutions to the
maximum extent practicable.
9.1
Ground Water Remediation
9.1.1 Major Components of Ground Water Remediation
The major components of the selected remedy (Alternative #2) which address ground
water remediation are as follows:
.
natural attenuation of vinyl chloride and antimony,
.
ground water monitoring to confirm natural attenuation,
.
monitoring of residential wells to determine the impact upon such
private wells, and
.
public water supply connections for residents that have been affected by
contamination in excess of the levels above performance standards.
Implementation of Alternative 2 in conjuction with the QUI and the landfill closure
will protect human health and the environment. Completion of the landfill. closure
under the FDEP permit is expected to eliminate the only remaining source of
contamination in the ground water, surface soils, surface water, and sediments. The
FDEP permit also requires that the Site be zoned for parks and recreation and that
public water and sewer be provided to park facilities. Because ground water samples
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Record of Decision
Davie und61l Site
Page 68
taken from the landfill property showed no significant amounts of contamination, no
further deed restrictionS or ground water use restrictions are considered necessary on
the landfill property.
A reduction in the concentration of contaminants in ground water should be achieved
within a reasonable timeframe given the low levels of contamination, low likelihood
of exposure, and the relatively long timeframe required for extraction and treatment
of ground water. Contaminated ground water is not being used for drinking water in
the vicinity of the Site. Residential areas adjacent to the Site are monitored and
provisions have been made to provide public water to residents with wells found to
have contaminated ground water. Ground water use controls will continue to be
implemented to ensure that ground water is not used before levels protective of
human health and the environment are reached.
The purpose of the selected remedy is to ensure that contaminant levels reach
ARARs. Should contaminant levels approach asymptotic levels before reaching
ARARs, EP A, in consultation with FDEP, will re-evaluate the effectiveness of the
selected remedy. Because this remedy will result in hazardous substances remaining
in the ground water above health-based levels for a time exceeding five years, a
review will continue to be conducted every five years after commencement of the
OUt remedial action to ensure that the remedy continues to provide adequate
protection of human health and the environment. No additional capital costs are
associated with this remedy, provided Broward County continues to perform under
the state closure permil
9.1.2 Performance Standards
Ground water will be monitored until the following maximum concentration levels
are attained.
Contaminant
vinyl chloride
antimony
Concentration
} ug/L
6 ug/L
A literature search was conducted and calculations were performed during the FS
that indicate the natural attenuation of vinyl chloride will achieve ARARs in 16 years.
No estimation of the time required for antimony to attenuate could be made because
antimony readily binds to soil and is unlikely to move with the ground water and
thereby contaminate the ground water. Because the levels of antimony detected are
relatively low, antimony is a metal, and antimony is expected to adhere to soil
particles rather than move with the ground water, natural attenuation is expected to
be an effective remedy for antimony to reach ARARs. The major federal and state
ARARs and TBCs for this alternative can be found in Tables 8-1, 8-2, and 8-3 of this
ROD.
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Record of Decision
Davie Landfill Site
Page 69
9.1..3 Compliance Testing
A ground water compliance program will be developed to monitor the progress of
the ground water restoration. Ground water samples will be collected from existing
monitoring wells. These samples will provide confirmation that levels of vinyl
chloride and antimony are continuing to decline and that contamination has not
continued to migrate or contaminate other nearby residential wells.
Ground water samples will be collected from the monitoring wells and analyzed for
vinyl chloride and antimony levels in accordance with the approved FDEP ground
water monitoring plan until ARARs are reached. If levels are exceeded or
contaminant levels approach asymptotic levels before achieving ARARs, EP A, in
consultation with FDEP, will reevaluate the effectiveness of the remedy and the need
for further action. Irregardless, monitoring will continue until ARARs are met. Post
remediation monitoring will be conducted for a minimum of one year to confirm that
the performance standards have been attained.
10.0
STATUTORY DETERMINATION
Under Section 121 of CERCLA, 42 U.S.c. ~ 9621, EPA must select remedies that are
protective of human health and the environment, comply With applicable or relevant
and appropriate requirements (unless a statutory waiver is justified), are cost
effective, and utilize permanent solutions and alternative treatment technologies or
resource recovery technologies to the maximum extent practicable. . In addition,
CERCLA includes a preference for remedies that employ treatment that permanently
and significantly reduce the volume, toxicity, or mobility of hazardous wastes as their
principal element. The following sections discuss how the selected remedy meets
these statutory requirements.
10.1
Protection of Human Health and the Environment
The selected remedy provides protection of human health and the environment by
eliminating, reducing, and controlling risk through engineering controls and/or
institutional controls and ground water treatment, if required, as delineated through
the performance standards described in Section 9.0 - SUMMARY OF SELECTED
REMEDY. The carcinogenic risk due to vinyl chloride and the non-carcinogenic risk
due to antimony will be reduced to acceptable levels (i.e., cancer risk between 1x1~
and 1x1o-t and Hazard Index less than or equal to 1) once performance standards are
achieved.
Ground water monitoring will be implemented in accordance with performance
standards described in Section 9.0 - SUMMARY OF SELECTED REMEDY to ensure
that no exposure through ingestion of contaminated ground water occurs. Active
remediation will not be implemented for ground water. Residents found to have
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Record of Decision
Davie Landfill Site
Page 70
contaminated wells will be placed on public water. Implementation of this remedy
will not pose unacceptable short-term risks or cross media impact.
10.2 Attainment of the Applicable or Relevant and Appropriate Requirements
~ARARs)
Remedial actions performed under Section 121 of CERCLA, 42 u.s.c. 99621, must
comply with all applicable or relevant and appropriate requirements (ARARs). All
alternatives considered for the Site were evaluated on the basis of the degree to
which they complied with these ~equirements. The selected remedy was found to
meet or exceed ARARs identified in Tables 8-1, 8-2, and 8-3. The following is a short
narrative expl~g the attainment of pertinent ARARs.
Chemical-Specific ARARs
Ground water performance standards identified as primary drinking water MCLs are
the remedial action goals set out in this ROD. If it becomes apparent that MCLs will
not be met due to attenuation, EPA, in consultation with FDEP, will re-evaluate the
effectiveness of this remedy. Performance standards are consistent with ARARs
identified in Table 8-3.
Action-Specific ARARs
Performance standards are consistent with ARARs identified in Table 8-2.
Location-Specific ARARs
Performance standards are consistent with ARARs identified in Table 8-1.
The selected remedy is protective of species listed as endangered or threatened under
the Endangered Species Act. Requirements of the Interagency Section 7 Consultation
Process, 50 CPR Part 402, will be met. The Department of the Interior, Fish &
Wildlife Service, will be consulted during the remedial design to assure that
endangered or threatened species are not adversely impacted by implementation of
this remedy.
Waivers
Waivers are not anticipated at this Site at this time. Should contaminants reach
asymptotic levels prior to reaching performance standards, a waiver may be
considered provided affected residential areas are provided with public water.
Other Guidance To Be Considered
Other Guidance To Be Considered (TBCs) include health-based advisories and
guidance. TBCs have been utilized in estimating incremental cancer risk numbers for
remedial activities at the Site and in determining RCRA applications to contaminated
media. . .
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Record of Decision
Davie Landfill Site
Page 71
10.3
Cost Effectiveness
After evaluating all of the alternatives which satisfy the two threshold criteria,
protection of human health and the environment and attainment of ARARs, EP A has
concluded that the selected remedy; Alternative 2, affords the highest level of overall
effectiveness proportional to its cost. Section 300.430(f)(1)(ii)(D) of the NCP also
requires EP A to evaluate three out of five balancing criteria to determine overall
effectiveness: long-term effectiveness and permanence; reduction of toxicity, mobility,
or volume through treatment; and short-term effectiveness. Overall effectiveness is
then compared to cost to ensure that the remedy is cost-effective. The selected
remedy provides for overall effectiveness in proportion to its cost.
The ~elected remedy has a low present worth, capital, and operation and .
maintenance cost compared to more exotic remedies, while satisfying the criteria for
long-term effectiveness and permanence and short-term effectiveness. This
alternative would not reduce toxicity, mobility, or volume through treatment;
however, the reduction of toxicity, mobility, or volume through this action would be
monitored until ARARs are attained.
The estimated present worth cost for the selected remedy is $0. Should Broward
County fail to perform the work required under the FDEP landfill closure permit and
fail to access the State of Florida Water Quality Assurance Trust Fund to provide a
source of public water to affected residents, then the estimated total present worth
cost for the selected remedy will be $1,400,000.
The $ 6 million cost increase for Alternative 3 is not warranted since Alternatives 1
and 2 will protect human health and the environment. EP A believes the selected
remedy, Alternative 2, will eliminate the risks to human health at no additional
capital or O&M cost to the PRPs while satisfying residents' desires to maintain EP A
involvement and also satisfying statutory requirements for EP A to remain involved.
10.4
Utilization of Permanent Solutions to the Maximum Extent Practicable
EP A and the State of Florida have determined that the selected remedy represents the
maximum extent to which permanent solutions and treatment technologies can be
utilized in a cost-effective manner for the final remediation at the Davie Landfill Site.
Of those alternatives that are protective of human health and the environment and
comply with ARARs, EP A and the State have determined that Alternative 2 provides
the best balance of trade-offs in terms of long-term effectiveness and permanence,
reduction in toxicity, mobility, or volume achieved through treatment, short-term
effectiveness, implementability, and cost, while also considering the statutory
preference for treatment as a principal element and consideration of state and
community acceptance. The selected remedy will not satisfy the statutory preference.
for treatment. However, the selected remedy does provide for long-term
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Record of Decision
Davie Landfill Site
Page 72
effectiveness and permanence, is easily implemented, reduces toxicity, mobility or,
volume, and is cost effective. ..
The Davie community is concerned about water quality around the Site. Many
members of the community would like to be furnished with a source for public water
regardless of whether their wells are contaminated or not. However, the community
generally agrees with the selected remedy.
10.5
Preference for Treatment as a Principal Element
The statutory preference for treatment is not satisfied by the selected remedy;
however, natural attenuation is a cost effective method to address the residual threat
to ground water posed by the existing contaminants, vinyl chloride and antimony.
Based on the ground water contaminants present and their low concentrations,
relative to the drinking water quality standards, the scattered occurences of
contamination which prevented the identification of the plume, the low mobility of
antimony, and the fact that the primary source of the contamination at the Site, the
sludge lagoon, has been remediated, EP A concluded that it was impracticable to treat
the ground water effectively. The remedial objectives of the selected remedy address
the health and environmental threats at the Site: ingestion of contaminated ground
water.
11.0
DOCUMENTATION OF SIGNIFICANT CHANGES
There have been no significant changes in the selected remedy, Alternative 2, from
the preferred remedy described in the proposed plan.
-------
APPENDIX A - RESPONSIVENESS SUMMARY
-------
RESPONSIVENESS SUMMARY
OPERABLE UNIT 2
DAVIE LANDFILL SUPERFUND SITE
DAVIE, BROWARD COUNTY, FLORIDA
Introduction
This responsiveness summary for the Davie Landfill Superfund Site documents for the
public record concerns and issues raised during the comment period on the proposed
plan for operable unit 2 (OU2). EPA's responses to these concerns and issues are
included. .
Overview of Comment Period
The proposed plan for operable unit 2 (OU2) at the Davie Landfill Superfund Site was
issued on May 6, 1994. The thirty~ay public comment period for the proposed plan
began May 9, 1994, and ended June 8, 1994. Six written comments, some with
multiple concerns, were received during that comment period. A public meeting was
held on May 19, 1994 at the Town of Davie Community Hall, at 6591 S.W. 45th Street,
Davie, Florida. Several comments were received and addressed during that meeting.
A transcript 01 the meeting was prepared and is available at the information
repositories near the Site.
Concerns Raised Durina the Comment Period
Private Well User Concerns:
1.
Several citizens expressed concern about ground water quality near the Site
and their general desire to be placed on public water. Residents feel that
Broward County has polluted the aquifer which most adjacent residents access
for drinking water through private wells. They want Broward County to pay for
extending public water lines and for residential connections. Several residents
indicated that they thought Broward County should pay their water bills.
Response: Contaminants detected were found in very small quantities at
sporadic locations. The proposed remedy includes monitoring 01 monitoring
wells and residential wells downgradient of the Site until concentrations of vinyl
chloride and antimony reach ARARS (i.e., primary drinking water standards). 11
contaminant levels reach asymptotic levels before reaching ARARs, EPA, in
consultation with FDEP, will re-evaluate the effectiveness of the selected
remedy. The remedy also requires Broward County to provide residents with
contaminated wells connections to public water. The remedy does not require
Broward County to provide access to public water to residents not affected by
contamination. .
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Broward County's Public Health Unit has performed the residential monitoring at
the Site since 1988, and will continue to monitor residential wells downgradient
of the areas placed on public water. Broward County is responsible for
ensuring that monitoring of residential areas is conducted. whether through the
Public Health Unit or another county office.
Currently, public water supply connections are being paid for through the State
of Florida Water Quality Assurance Trust Fund. If the trust fund cannot be
accessed to pay for public water connections for affected residents, Broward
County will be required to pay for the connections.
The remedy does not require Broward County to pay for residential water uses
of affected residents; the county only is required to provide an alternate source
of water to affected residents.
2.
Several residents who live northeast of the Site expressed concern that a
leachate force main from the landfill was routed through their neighborhood.
The residents are concerned that the line will leak and contaminate their private
wells. They are concerned that no one monitors their wells. They insist that
Broward_County agreed to provide public water to their homes wh~n the
leachate line was installed, but that Broward County never installed public water
lines. They do not trust Broward County officials to look out for their welfare.
Response: The leachate collection line was constructed in 1992 with HDPE
pipe as a modification to the FDEP permit for the closure of the landfill. The
pipe was installed in 500 ft lengths with fusion welds. This type of pipe is
typically used to convey leachate because it is chemically resistant to
contaminants found in leachate; it is strong enough to bear the overburden
loads typically imposed at landfills; and it is flexible enough to withstand uneven
settlements without breaking. The pipe lengths are long to reduce the number
of connections required and the pipes are fusion welded to reduce the
possibility of leakage. The pipe was hydrostatically tested (i.e., tested with high
pressure water) prior to being put in service and the pressure at the beginning
and end of the line is checked twice per week to determine if there have been
any unexplained pressure drops. Broward County officials have said that no
decrease in pressure or volume, which might indicate a leak, has been
observed since the pipeline has been in operation.
The Broward County Public Health Unit has monitored at least one resident on
37th Court and has not found contamination. The Health Unit has agreed to
monitor a few homes in the area for a short period of time in order to.alleviate
residential concerns. .
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3.
Broward County agreed to provide $175,000.towards the installation of public
water supply lines to the residential area northeast of the Site when the pipeline
was being installed. Town of Davie officials have developed plans which they
estimate will require more than $175,000 to implement. The Town currently is
evaluating ways to finance the shortfall.
Two residents who live northeast of the Site asked that their wells be tested.
4.
Response: EPA forwarded those requests to the Broward County Public
Health Unit The director of the Public Health Unit indicated that those wells
would be sampled, if possible, when sampling in that area was performed.
A citizen asked that more sampling be done southeast of the Site.
Response: Broward Counties Public Health Unit will continue to monitor
residential areas southeast of the Site. This area has been monitored since
1988. EPA determined that enough data currently exists to make a decision
regarding remediation at the Site, but monitoring will continue to be performed
in the residential area southeast of the Site.
5.
A resident asked about orange pipes that used to be on 36th Court. The
resident indicated that crews used to periodically take samples from the pipes,
but the pipes no longer are visible or are being sampled.
Response: The orange pipes were not installed as part of the leachate force
main or any landfill activities. EPA has been unable to locate any information
regarding the orange pipes.
6.
A citizen asked if Broward County was going to reimburse residents south of
the Site who hooked up to public water at their own expense.
7.
Response: EPA can require that Broward County provide an alternate water
source to private well owners impacted by contamination from the Site. EPA
does not have the authority to require Broward County to reimburse residents
for past damages.
A citizen expressed concern about public water supply wells being affected by
contamination, specifically the "Ivanhoe" well field.
Response: The nearest public water well field is in Cooper City, 2 miles
southeast of the Site. There are several clusters of monitoring wells between
the Site and the well field. The local water authorities analyze the water daily. .
If the Site were affecting water quality at the public water well field, there would
be indications from monitoring wells. The Ivanhoe we~1 field is several miles
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P8Q8 4
west of the Site, is upgradient of the Site, and therefore, should not be affected
by contamination.
Landfill Closure Concerns:
8.
A citizen expressed concern about the facility becoming a park.
Response: Based on the Risk Assessment performed by EPA, the soils,
surface water, and sediments at the closed landfill are not hazardous to the
public. Therefore, EP A is not restricting access to the landfill. The Site has
been zoned for Parks and Recreation. Continuing concerns regarding the use
of the Site for a Park should be directed toward Broward County and Town of
Davie officials.
9.
. A citizen asked why organic matter was dumped onsite along the shoreline of
Lake NO.3.
Response: The closure plan for the landfill requires that topsoil and grass
cover the slopes and shoreline leading to the Lakes to reduce erosion, thereby
maintaini!1g the integrity of the closure system. The topsoil and gr~ss should
improve the habitat for terrestrial wildlife at the Site.
Natural Resource Concerns:
10.
One comment stated that the proposed plan did not go far enough in predicting
the damage to natural resources.
Response: Seventy-two (72) ground water monitoring wells were sampled,
twenty (20) private wells were sampled, 25 surface water samples were taken,
17 sediment samples were taken, and 10 soil samples were taken. Natural
Resource Trustees for the state and federal government were asked to
comment on the location and number of samples prior to beginning field
activities at the Site. Until this comment was received, there was no indication
from any group reviewing the reports that the Remedial Investigation/Feasibility
Study (RI/FS) at the Site was lacking in any area. Based on the results of the
RI, EPA does not feel that a more detailed investigation is warranted at this
Site.
RifFS Concerns:
11.
A citizen asked if we sampled in the C-ll canal.
Response: Yes. Sediments and surface water were sampled at 4 locations in
the C-ll canal. Nine contaminants of potential conce~ were found in the
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Page 5
12.
sediment and seven contaminants were found in the surface water. More
information on the contaminants of potential concern can be found in Tables
3-5 and 3-8 of the Baseline Risk Assessment or in Tables 6-5 and 6-6 of the
Record of Decision (ROD). The effects of the contaminants of concern in
sediment and surface water on human health and the environment were
evaluated in the Baseline Risk Assessment and were found to be below a level
which would harm human health or the environment.
One comment stated that an insufficient number of samples was taken in the
0-11 canal and that the full impact on biota from the existence and transport of
contaminants within 0-11 has not been determined yet by. either bioassay or
toxicological studies. This comment also stated that background sample
locations SD-9 and SD-12 were not truly background. The citizen questioned
the impact of Site contaminants on the Everglades.
Response: Sediments and surface water were sampled at 4 locations in the
C-ll canal. EPA and state and federal trustees reviewed the work plan which
described those locations and determined that this number of samples was
adequate to characterize the surface water chemistry near the landfill. Site-
specific ecological testing, such as the bioassays and toxicological testing
mentioned, often are recommended if Site contaminant concentrations exceed
the screening values or literature information for the appropriate media.
However, additional factors, such as the number of samples and the -number of
contaminants exceeding screening values, the degree of exceedance, factors
affecting bioavailability, etc., are considered in making the decision to conduct
such testing. Based on the results of the RI, EPA determined that no further
testing was necessary.
13.
C-l1 Canal sampling location SD-9 was not used as a background location
(Section 2.1, page 2-14 of the Baseline Risk Assessment). SD-12 was used as
a background location. SD-12 was collected 2.5 miles west of the Site and 3.5
miles east of the pumping station. Because of the distance between the pump
station and the sample location, it is unlikely that these sediment samples could
be affected by backpumping of the canal. Similarly, it is unlikely that Site-
related contaminants have impacted the Everglade region west of the Site.
Therefore, SD-12 is considered representative of ambient sediment chemistry.
One comment questioned why the detection limit for vinyl chloride was 10 ug/L
when the MCL is 1 ug/L
Response: The detection limit for vinyl chloride should have been less than or
equal to 1 ug/L The 10 ug/L value in the groundwater samples is a .
quantification level. Above 10 ug/L the analyses can be accurately quantified.
Below 10 uglL the analyses can be estimated. Any d~tection of vinyl chloride
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. Responslven.. Summary
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Page 6
below 10 ug/L. was reported as an estimate and was labeled with a J. The
minimum instrument detection level was 1.3 ug/L .
Because there is a substantial data base regarding vinyl chloride in this area
based on testing methods with detection limits of 1 ug/L, EPA did not feel that it
was necessary to resample with lower detection limits in order to determine the
extent of contamination. The sampling results gathered in the RI agreed with
other results taken in this area. This means that the locations where vinyl
chloride was detected in the RI are the same locations where vinyl chloride has
been detected in previous sampling events. In addition, the levels of vinyl
chloride estimated in the RI are in the same range as the levels detected in
previous sampling events.
14.
The Florida Department of Health and Rehabilitative Services (HRS) provides
quarterly groundwater testing for residences in the area surrounding the Site.
The detection limit in the test method used by HRS is 1 ug/L. The County also
tests groundwater quarterly using a method with a detection limit of 1 ug/L.
One comment stated that secondary drinking water standards were violated for
iron, sodi~m, aluminum, and manganese.
Response: A 1991 study performed by the U.S. Geological Survey, in .
cooperation with the Florida Department of Environmental Regulation, Maior-
Ion and Selected Trace-Metal Chemistry of the Biscavne Aauifer. Southeast
Florida. reports iron concentrations in the Biscayne Aquifer in South Florida for
182 samples that range from below detection limits (BDL) to 21,000 ug/L The
iron reported in the RI was well within the range of naturally occurring iron
reported by the USGS (350 ug/L to 17,000 ug/L). Iron is ubiquitous in the
ground water in South Florida.
15.
Less than 5% of the ground water samples contained exceedances for sodium,
aluminum and manganese. The sodium and manganese analyses fell within
the range of background values for the Biscayne Aquifer as reported by the
1991 USGS Study. The exceedances do not define a plume and occur
scattered throughout the sampling area. The risk assessment performed for
this Site indicated that none of these contaminants are considered to contribute
significantly to the calculated human h~alth risk.
One comment stated that the detection limit for Antimony (15 ug/L) was higher
than the MCL (6 mg/L), therefore the contamination at the Site due to antimony
may be more extensive than indicated in the RI.
Response: Antimony was not identified as a contaminant of concern at this
Site prior to the RI, and therefore, the detection limit w:as not of great concern
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DavIe L8nc1fiII OpenIbIe Unit 2
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prior to the investigation. The 15 ug/L value in the groundwater samples is a
quantification level. Above 15 ug/L the analyses can be accurately quantified.
Below 15 uglL the analyses can be estimated. Any detection of antimony below
15 ug/L would have been reported as an estimate and labeled with a "J". The
minimum instrument detection level was approximately 2 ug/L.
16.
Twenty-five percent of the samples were tested for antimony. No estimated
values were reported. Three wells analyzed positive for antimony at 15 to 19
ug/L. Antimony is expected to readily bind to the soil; therefore, antimony is not
expected to migrate into the groundwater and contaminate the groundwater.
One comment stated that antimony was detected in 8 out of 8 sediment
samples above the biological Effects Range-Low concentration, mercury was
detected in 9 out of 22 sediment samples above the biological Effects Range-
Low (ER-L) concentration, and silver was detected in 2 out of 22 sediment
samples above the biological Effects Range Low (ER-L) concentration. The
commentor implied that a more extensive response was required to address
this contamination.
Response: It appears that the commentor misinterpreted the results of the RI.
Table ES.4 in Appendix E of the RI provides a summary of metals detected in
sediments near the Site. When a contaminant is tested for but not detected it is
reported with a "<" symbol or a "U" qualifier and a number. The number
represents the quantltatlon limit (Le., the detection limit above which the
reported values are considered accurate). Below that number the concentration
can be estimated but not determined with the required degree of accuracy.
Any detections below the quantitation limit would have been reported as an
estimated value and labeled with a "J". The lowest level that can be estimated
is referred to as the instrument detection limit. The instrument detection limit is
typically 10-15% of the quantitation limit.
The NOAA Sediment Effects Range Low (ER-L) and Effects Range Median
(ER-M) concentrations are used as screening values to determine if more
detailed studies are required. Concentrations above the ER-L, but well below
the ER-M, indicate a low potential for detrimental effects. Based on the limited
exceedances at the Site, EPA determined that additional studies were not
warranted.
Based on Table ES.4 of the RI, antimony was not detected in any sediment
samples, either as an estimated value or above the quantitation limit.
Cuantitation limits vary from sample to sample depending on the presence 01
other contaminants in the sample and the concentration of those contaminants. .
This is because the presence of other contaminants makes it more difficult to
segregate out the exact amount present of any particu.lar contaminant below the
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Responaiven.. Summary
Davie L8ndfill Operable Unit 2
Page 8
quantitation limit. The quant/tat/on limit for antimony in sediment ranged from
2.6 - 6.6 mgJkg in 7 samples and was 23.3 mglkg in 1 sample; these
quantitation limits were above the NOAA Effects Range-Low (ER-L)
concentration of 2 mglkg but below the Effects Range-Median (ER-M)
concentration of 2S mglkg.
Mercury was detected in 5/17 sediment samples at concentrations ranging from
0.072~.17 mglkg. Four of the samples (at 0.17 mglkg) slightly exceed the ER-
L for mercury of .0.15 mglkg but are below the ER-M of 1.3 mgfkg. Sample. SD-
9, located somewhat upstream from the landfill, was the only sample from the
C-l1 canal in which mercury was detected. If the landfill were the source of the
mercury, one might have expected to find detections of mercury in canal
sediment samples SD-8 and So...13, which are downgradient from the landfill.
Therefore, EPA believes the mercury contamination in the C-ll canal sample is
not Site related.
Silver was detected in 1/6 sediment samples. Silver was detected at 1.2 mg/kg,
which is slightly above the Effects Range-Low (ER-L) concentration of 1 mglkg
but below the Effects Range-Median (ER-M) concentration of 2.2 mglkg.
17.
- "
One comment expressed concern that the Boy Scout Lake and other
recreational water bodies may be affected by contaminated sediments through
runoff pathways.
Response: Surface water runoff is contained onsite by an extensive "storm
water management system. The Boy Scout Lake should not be impacted by
runoff from the Site, because a perimeter berm prevents water from flowing
offsite. If storm water exceeds the retention capacity of onsite structures, it will
be released, in a controlled manner via an existing underground culvert. to the
canals adjacent to the Site.
18.
Onsite lake sediments contain higher contaminant levels than the Boy Scout
Lake and these lakes have direct contact with onsite runoff. The risk
assessment conducted as part of the RifFS indicates that the sediments in
onsite lakes do not pose a significant human health threat, and only pose a low
risk to aquatic life.
Broward County does not agree that vinyl chloride and antimony concentrations
are site related. The county contends that septic tanks may account for or
contribute to the detection of vinyl chloride, and that the fact that the Davie
Landfill Site and surrounding area was a bombing range for the U.S. Army
during World War II may account for the presence of antimony.
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o.vIe L8ICIftII 0penbI. Unh 2
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Response: Since 1988, Broward County has reported exceedances of drinking
water standards for vinyl chloride in well clusters MW-11, MW-12, MW-13,
MW-15, MW-19, and MW-20. All of these well clusters, except for MW-20, are
located downgradient of the landfill and all of these well clusters, except for
MW-19, are located upgradient from the residential area (Sunshine Ranches).
Vinyl chloride also was detected in other onsite wells at or below drinking water
standards.
The residential wells where vinyl chloride was detected were downgradient of
the landfill. If residential septic systems were another source of vinyl chloride
contamination, then Broward County's Public Health Unit should be detecting
vinyl chloride more often in wells located downgradient, not upgradient, from the
septic tanks. The health unit has reported vinyl chloride in a few wells
downgradient of the landfill; however, in most residential wells sampled near the
Site, vinyl chloride was not detected.
Antimony was detected in two wells on the Site and one well off the Site. The
trash landfill contains ash from the former incinerator and ash can be a source
for antimony. Prior to this comment, EPA was not aware that the landfill and
sarrounding area had been used as a bombing range during World War II.
However, if the source for antimony was from activity during World War II, EPA
would expect to detect antimony more extensively on and off the Site.
Risk Assessment Concerns:
19.
Broward County does not agree with the major assumptions driving the risk at
the Site, specifically the future resident scenario.
Response: The future resident scenario was evaluated to determine the worst
case of possible exposure. The risk was evaluated based on exposure to each
contaminated media: ground water, surface soil, surface water, and sediment.
The risk assessment concluded that surface soil, surface water, and sediment
at the Site do not contribute significantly to the risk to future residents; however,
the ground water is a significant source of concern.
The county contends that the Site has been zoned for parks and recreation,
that the landfill will never become a residential area, and that public water will
be supplied to the Site for any park facilities as stipulated in the FDEP Closure
Permit. However, residential areas surround the Site and EPA contends that
the future resident scenario is applicable to current residents living adjacent to
the Site because most residents have private wells which tap into the
contaminated aquifer and because most residents will have access to surface
soils, surface water, and sediments at the Site when it is opened as a park.
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Da~.~fln~.Unb2
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Concerns About The Remedy Selected:
20.
A citizen commented that an insufficient number of alternatives were analyzed.
Response: General response actions for ground water remediation under the
National Contingency Plan (NCP) include no action, institutional controls, and
several extraction, treatment, containment, and disposal options. A preliminary
screening of technologies was conducted in the FS on the basis of
effectiveness, technical implementability, and cost. The most viable options
were evaluated as alternatives.
21.
A citizen commented that more emphasis needs to be put on Broward County
being the responsible entity. The citizen did not believe that monitoring was
enough of an action at the Site.
Response: Broward County is the only responsible party at the Site. Broward
County has assumed responsibility for all past and present remedial activities at
the Site and always has been identified as the responsible party for the Site.
This Site was originally placed on the National Priorities List (NPL) due to
contamination from the former sludge lagoon. The sludge lagoon remediation
was performed in 1989 and is referred to as operable unit I (OU1). The ground
water at the Site is being addressed as operable unit 2 (OU2).
It has been five years since Broward County remediated the major source of
contamination at the Site (i.e., QUI). Closure of the landfill essentially is
complete through a FDEP permit, thereby eliminating the source of the low level
contamination. The Broward County Public Health Unit has monitored the
ground water since 1989, and, as verified in the RI for OU2, only low levels of
contamination remain in the ground water. As the levels of contamination
decrease, the cost effectiveness of removing and treating the ground water also
decreases. Based on a literature search and calculations done during the FS
(pages 4-7 and 4-13 of the FS), vinyl chloride will attenuate in less than or
equal to 16 years and cost nothing, whereas, extraction and treatment of vinyl
chloride would take approximately 12 years and $ 6,000,000.
The residential area being impacted by contamination was provided by the
Broward County Public Health Unit with access to a public water source in 1988.
In the 6 years since those residents were provided access to public water, two
homes southeast of those residents were found to have drinking water
violations for vinyl chloride. Those residents then were provided access to
public water through a state water quality trust fund. .
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22.
Based on the RifFS and residential well monitoring results. the continued
effects of contamination on residential areas are considered limited. The
private wells users near the Site will continue to be monitored until the levels of
vinyl chloride and antimony reach ARARs and Broward Cou.nty will be
responsible for providing affected residents with access to a public water
source. either through the state trust fund or through county funds.
Another comment indicated a preference for a remedy which removes or
reduces harmful contaminants at the Site.
Response: Ground water extraction. treatment. and surface water discharge
was considered as a possible alternative at this Site. Due to the low levels of
contamination at the Site. extraction of vinyl chloride would take approximately
12 years as opposed to the 16 years estimated for natural attenuation.
Antimony would be even more difficult to extract and will likely adhere to soil
particles rather than be removed through ground water extraction. Because
current contaminant levels in the ground water already meet most surface water
standards. except for iron, the extracted ground water probably would not
require extensive treatment. Therefore, extraction of the ground water would
involve pumping ground water to surface water with little required treatment.
Because natural attenuation will achieve the same cleanup standards in only a
slightly longer time period than would ground water extraction, EPA has
determined that it is more appropriate to allow the contaminants to attenuate at
this Site.
23.
Broward County commented that residential monitoring is now and will continue
to be monitored by the State Public Health Department. Broward County stated
that monitoring will not be provided by the Broward County Office of Integrated
Waste Management and is not included in the Water Quality Management Plan
for the Davie Landfill. In addition. Broward County stated that if public water
needs to be provided. it is intended that the primary source of funding for the
supply of water will be through the State of Florida Water Quality Assurance
Trust Fund.
Response: As the only responsible party for remediation of the Davie Landfill
Site, Broward County will be held responsible for the execution of all activities
required in the selected remedy. Broward County will be held responsible for
monitoring the landfill and residential areas until contaminant levels reach
ARARs. Broward County will be held responsible for providing public water to
residents affected by contamination from the Site. EPA will not object to the
county using other resources to assist in the execution of the work, but.
Broward County always will be held responsible if those resources faH to
perform as required.
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P8g8 12
Condition #11 of the FDEP Closure Permit for the Davie Landfill, as modified on
September 1, 1988, requires that the county "continue the random groundwater
monitoring of the private residents' water supplies which are affected by the
landfill plume for its forward movement/recession until the Corrective Actions
For Ground Water Contamination Cases (CAFGWCC) has been resolved in
writing by the Department" The permit further requires that Broward County
"continue to provide bottled water to those residents whose private water
supplies are determined to be affected by this plume." The permit states that
this "determination shall be done in writing by the Broward County Public Health
Unit. It
If Broward County fails to perform any component of EPA's selected remedy,
EPA will pursue additional enforcement activities, or EPA will take over
execution 01 the work and pursue cost recovery actions against Broward
County.
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