PB96-964002
EPA/ROD/R04-96/242
March 1996
EPA Superfund
Record of Decision:
Stauffer Chemical Company,
Tampa, FL
12/01/1995
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RECORD OF DECISION
SUMMARY OF REMEDIAL ALTERNATIVE SELECTION
STAUFFER MANAGEMENT COMPANY SITE
TAMPA, HILLSBOROUGH COUNTY, FLORIDA
PREPARED BY
U. S. ENVIRONMENTAL PROTECTION AGENCY
REGION IV
ATLANTA, GEORGIA
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RECORD OF DECISION
DECLARATION
SITE NAME AND LOCATION
Stauffer Management Company Superfund Site
Tampa, Hillsborough County, Florida
STATEMENT OF BASIS AND PURPOSE
This decision document (Record of Decision), presents the selected remedial action for the
Stauffer Management Company Superfund Site, Tampa, Hillsborough County, Florida,
developed in accordance with the Comprehensive Environmental Response, Compensation
and Liability Act of 1980 (CERCLA), as amended by the Superfund Amendments and
Reauthorization Act of 1986 (SARA), 42 U.S.C. § 9601 et seq., and to the extent practicable,
the National Contingency Plan (NCP), 40 CFR Part 300.
This decision is based on the administrative record for the Stauffer Management Company
Superfund Site. The State of Florida, as represented by the Rorida Department of
Environmental Protection (FDEP), has reviewed the reports which are included in the
administrative record for the Stauffer Management Company Site. In accordance with 40
CFR 300.430, as the support agency, FDEP has provided EPA with input on 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 from the Stauffer Management
Company Superfund 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 SELECTED REMEDY
This action is the first and final action planned for the Site. This action addresses soil,
sediment, and ground water contamination at the Site and calls for the implementation of
response measures which will protect human health and the environment. The selected
remedy includes ex situ anaerobic treatment (i.e., bioremediation) of pesticide contaminated
surface soils and sediments to levels appropriate for future industrial use of the Site. In
addition, the selected remedy includes ground water recovery and treatment with activated
carbon to remove pesticides. Since bioremediation is an innovative treatment technology for
pesticide removal, ex situ thermal treatment of contaminated soils/sediments is being
proposed as a contingency remedy in the event that bioremediation cannot be implemented.
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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, is cost-effective, and utilizes permanent solutions and alternative treatment
technologies or resource recovery technologies to the maximum extent practicable. This
remedy satisfies the statutory preference for remedies that employ treatment that reduces
toxicity, mobility, or volume as a principal element.
Because this remedy results in hazardous substances remaining onsite hi sub-surface soils, a
review will be conducted within five years after commencement of the 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.
RICHARD D. GREEN
ASSOCIATE DIRECTOR OF SUPERFUND
AND EMERGENCY RESPONSE
DATE
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TABLE OF CONTENTS
1.0 SITE LOCATION AND DESCRIPTION 1
2.0 SITE HISTORY AND ENFORCEMENT ACTIVITIES 1
3.0 HIGHLIGHTS OF COMMUNITY PARTICIPATION 4
4.0 SCOPE AND ROLE OF ACTION 5
5.0 SUMMARY OF SITE CHARACTERISTICS 5
5.1 Physiography and Topography 5
5.2 Geology/Hydrogeologv 6
5.3 Surface Water Hydrology 7
5.4 Wildlife/Natural Resources 7
5.5 Summary of Site Contaminants 8
5.5.1 Substances Detected in Soil 8
5.5.2 Substances Detected In Ground Water 14
5.5.2.1 Monitoring Well Network 14
5.5.2.2 Substances Detected in the Surficial
Aquifer 14
5.5.2.3 Substances Detected in the Floridan
Aquifer 14
5.5.3 Substances Detected In Surface Water 19
5.5.4 Substances Detected In Sediment 19
6.0 SUMMARY OF SITE RISK 19
6.1 Risk Assessment Overview 19
6.2 Contaminants of Potential Concern (COPCs) to Human Health 23
6.2.1 Screening Criteria 23
6.2.2 Contaminants of Potential Concern in Surface Soil 23
6.2.3 Contaminants of Potential Concern in Surficial Ground Water ... 25
6.2.4 Contaminants of Potential Concern in Floridan Aquifer 25
6.2.5 Contaminants of Potential Concern in Surface Water 25
6.2.6 Contaminants of Potential Concern in Sediment 25
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TABLE OF CONTENTS (continued)
6.3 Exposure Assessment 25
6.3.1 Introduction 25
6.3.2 Source, Mechanism of Release, and Transport 26
6.3.3 Potential Receptors and Routes of Exposure 26
6.3.3.1 Current/Future Worker 26
6.3.3.2 Current/Future Offsite Resident 27
6.3.3.3 Future Resident 27
6.3.4 Exposure Point Concentrations 27
6.3.5 Dose Assumptions . 27
6.4 Toxicity Assessment 28
6.5 Risk Characterization 29
6.5.1 Overview 29
6.5.2 Current/Future Worker . . 30
6.5.3 Current/Future Offsite Resident 30
6.5.4 Future Onsite Resident/Future Resident 30
6.6 Identification of Uncertainties 32
6.7 Ecological Evaluation 32
6.7.1 Overview 32
6.7.2 Contaminants of Potential Ecological Concern 33
6.7.3 Exposure Assessment 33
6.7.4 Toxicity Assessment 34
6.7.4.1 Surface Water/Sediment 34
6.7.4.2 Surface Soil 34
6.7.5 Risk Characterization 34
6.7.5.1 Surface Water 34
6.7.5.2 Sediment 34
6.7.5.3 Surface Soil 35
6.7.6 Uncertainty Analysis 35
n
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TABLE OF CONTENTS (continued)
7.0 DESCRIPTION OF ALTERNATIVES 36
7.1 Remedial Action Objectives 36
7.1.1 Beneficial Land Use 36
7.1.2 Human Health Risk 36
7.1.3 Ecological Risk 37
7.1.4 Protection of Ground Water 37
7.1.5 Remediation Goals . . . 38
7.2 Soil/Sediment Remedial Alternatives 38
7.2.1 Alternative No. IS: No Action 38
7.2.2 Alternative No. 2S: Limited Action 38
7.2.3 Alternative No. 3S: Native Soil Barrier 40
7.2.4 Alternative No. 4S: In Situ Anaerobic Treatment of Surficial
Soil/Sediment 40
7.2.5 Alternative No. 5S: Ex Situ Thermal Treatment of Surficial
Soil/Sediment 41
7.2.6 Alternative No. 6S: Ex Situ Anaerobic Treatment of Surficial
Soil/Sediment 41
7.2.7 Alternative No. 7S: Disposal of Surficial Soil/Sediment at an
Offsite RCRA TSD Facility . 42
7.2.8 Alternative No. 8S: Ex Situ Anaerobic Treatment of Deep
Soil/Sediment 43
7.3 Ground Water Remedial Alternatives 43
7.3.1 Alternative No. 1GW: No Action 44
7.3.2 Alternative No. 2GW: Institutional Action 44
7.3.3 Alternative No. 3GW: Recovery and Treatment by Activated
Carbon Adsorption with Discharge to Onsite Ponds or the Tampa
Bypass Canal 44
7.3.4 Alternative No. 4GW: In Situ Anaerobic Treatment of Ground
Water 45
8.0 SUMMARY OF THE COMPARATIVE ANALYSIS OF ALTERNATIVES 45
8.1 Statutory Balancing Criteria 45
8.2 Threshold Criteria 48
111
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TABLE OF CONTENTS (continued)
8.2.1 Overall Protection of Human Health and the Environment 48
8.2.2 Compliance With ARARs 48
8.3 Primary Balancing Criteria 49
8.3.1 Long-Term Effectiveness and Permanence 49
8.3.2 Reduction of Toxicity, Mobility, or Volume Through Treatment . . 49
8.3.3 Short-Term Effectiveness 49
8.3.4 Implemeritability 53
8.3.5 Cost . 53
.. 8.4 Modifying Criteria 54
8.4.1 State Acceptance 54
8.4.2 Community Acceptance 55
9.0 SUMMARY OF SELECTED REMEDY 55
9.1 Source Control 55
9.1.1 Major Components of Source Control 55
9.1.2 Performance Standards 56
9.2 Ground Water Remediation 56
9.2.1 Major Components of Ground Water Remediation 56
9.2.2 Performance Standards .. . 57
9.2.2.1 Extraction Standards 57
9.2.2.2 Treatment Standards 57
9.2.2.3 Discharge Standards 57
9.2.2.4 Design Standards 57
9.3 Compliance Testing 57
9.4 Contingency Remedy for Soil/Sediment 58
10.0 STATUTORY DETERMINATION 58
10.1 Protection of Human Health and the Environment 58
10.2 Attainment of the Applicable or Relevant and Appropriate Requirements
(ARARs) 58
IV
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TABLE OF CONTENTS (continued)
10.3 Cost Effectiveness 59
10.4 Utilization of Permanent Solutions to the Maximum Extent Practicable . 60
10.5 Preference for Treatment as a Principal Element 60
11.0 DOCUMENTATION OF SIGNIFICANT CHANGES 60
APPENDIX A - RESPONSIVENESS SUMMARY
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LIST OF TABLES
TABLE 5-1: SUBSTANCES DETECTED IN SURFACE SOILS. 11
TABLE 5-2: SUBSTANCES DETECTED IN SUBSURFACE SOILS 13
TABLE 5-3: REMOVAL ACTION CONFIRMATORY SAMPLING SUMMARY .. 15
TABLE 5-4: SUBSTANCES DETECTED IN SURFICIAL AQUIFER 17
TABLE 5-5: SUBSTANCES DETECTED IN FLORIDAN AQUIFER 18
TABLE 5-6: SUBSTANCES DETECTED IN SURFACE WATER 21
TABLE 5-7: SUBSTANCES DETECTED IN SEDIMENT 22
TABLE 6-1: CONTAMINANTS OF POTENTIAL CONCERN 24
TABLE 6-2: SUMMARY OF CANCER AND NON-CANCER RISKS 31
TABLE 7-1: REMEDIAL GOALS 39
TABLE 7-2: SURFACE WATER DISCHARGE REQUIREMENTS 46
TABLE 8-1: POTENTIAL LOCATION SPECIFIC ARARS AND TBCs 50
TABLE 8-2: POTENTIAL ACTION SPECIFIC ARARS AND TBCs 51
TABLE 8-3: POTENTIAL CHEMICAL SPECIFIC ARARS AND TBCs 52
TABLE 8-4: COMPARISON OF COSTS 54
VI
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LIST OF FIGURES
FIGURE 1-1: GENERAL LOCATION MAP 2
FIGURE 1-2: SITE MAP 3
FIGURE 5-1: SURFACE SOIL COMPOST SAMPLING LOCATIONS 9
FIGURE 5-2: SOIL BORING LOCATIONS : 10
FIGURE 5-3: GROUND WATER SAMPLING LOCATIONS 16
FIGURE 5-4: SURFACE WATER AND SEDIMENT SAMPLING LOCATIONS ... 20
Vll
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Record of Decision
Stauffer Management Company Superfund Site
Pagel
1.0 SITE LOCATION AND DESCRIPTION
The Stauffer Management Company Superfund Site (hereinafter referred to as the
"SMC Site" or the "Site") is located at 2009 Orient Road in Section 14, Township 29
South, Range 19 East, Hillsborough County, Tampa, Florida (see Figure 1-1). The Site
is an inactive pesticide manufacturer/distribution facility which encompasses
approximately 40 acres of land in an industrialized area of Tampa. Land use
surrounding the Site is predominantly commercial/industrial.
Several structures are on the Site including an office, warehouse, laboratory, and
additional buildings in the north-central and western corners of the property (see
Figure. 1-2). The Site is bordered by Universal Waste & Transit, Inc. to the west, the
Hillsborough County Correctional Facility to the south, and the Tampa Bypass Canal
to the east. The CSX Railroad easement is adjacent to the Site's northern perimeter
while a construction materials plant is located directly north of the easement. A
petroleum pipeline runs through the easement north of the Site. The Helena
v. " -nical Company is located northwest of the Site.
The northern portion of the Site is maintained by a caretaker. The southern and
eastern portions are wooded and overgrown. Most of the Site is vegetated, except for
the areas where support facilities are located and an area in the northern portion
where sulfur is known to have been stored. Two secluded bodies of water, a large
and small pond, are located on the Site. The large pond ranges in depth from 3.5 to
11 feet. The small pond ranges in depth from 1 to 10 feet.
2.0 SITE HISTORY AND ENFORCEMENT ACTIVITIES
The SMC Site was used to formulate agricultural chemical products from 1951 until
1986 and is now inactive. Agricultural pesticides, such as herbicides and insecticides
were combined at the plant with raw materials such as kerosene, xylene, clay,
solvents, and diatomaceous earth to form pesticide dusts, granules, and liquids that
were packaged for distribution. A small incinerator located at the Site was used to
burn packaging materials that formerly contained raw materials.
Between 1953 and 1973, waste materials from the facility were disposed of onsite.
Several site investigations by various organizations were conducted at the SMC Site
between 1987 and 1992. A site investigation conducted by NUS Corporation (NUS)
in 1987 revealed the presence of pesticides in onsite soil, surface water and sediment
in onsite ponds, and in ground water underlying the Site. A geophysical survey was
also completed during the investigation which concluded buried metal was present.
Further investigations were conducted at the Site by NUS in 1988 to assess the threat
to human health and the environment posed by the Site, and subsequently to
characterize the Site using the Hazard Ranking System.
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Stauffer Management Company Superfund Site
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FIGURE 1-1 GENERAL LOCATION MAP
c
SOURCE Brandonnampa Quadrangle 75 Minute Series (Topographic) Revised 1987
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Stauffer Management Company Superfund Site
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FIGURE 1-2 SITEMAP
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Stauffer Management Company Superfund Site
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In 1990, a more extensive geophysical survey was performed at the Site by
Environmental Resource Management - South, Inc. (ERM). Additional areas
containing buried metal were identified. As a result, the U.S. Environmental
Protection Agency (EPA) requested a supplemental investigation be conducted at the
SMC Site. Camp Dresser & McKee (CDM) conducted additional site investigation
activities in preparation for initiating a removal action at the Site.
In March 1992, EPA formally requested that Stauffer Management Company perform
a removal action at the SMC Site. The removal action for the Site as well as the
cleanup criteria were outlined in an Administrative Order of Consent .(AOC) which
was signed with the EPA in March 1992, with the agreement that further remedial
activities would be conducted at the Site. Removal activities completed under the
March 1992 AOC were divided into two phases. Phase I included the removal of
buried metal and drums, and onsite soils containing a total pesticide concentration of
1,000 ppm or greater from seven separate areas onsite: the Northeast Corner, the
Crushed Drum Area, the Buried Metal Area, Soil Hot Spot A10, Soil Hot Spot A25,
the Rail Spur Terminus Area, and the Southern Area. Phase n included the
treatment, transportation, and or disposal of all hazardous substances excavated
pursuant to the AOC.
A total of 3,415 cubic yards (CY) of soil was removed from seven different areas and
treated onsite. Of the 3,415 CY excavated, approximately 3,265 CY of contaminated
soils were treated using Low Temperature Thermal Desorption (LTTD) technology.
The remaining 150 CY were set aside for use in treatability studies. Seventeen rolloff
boxes, equivalent to 510 CY of debris, which includes crushed drums, wood, and
other miscellaneous metal, were also removed from the areas onsite; the rolloff boxes
(six profiled as RCRA hazardous and ten profiled as non-hazardous) were shipped
offsite to a RCRA approved facility. The excavated areas onsite were backfilled with
dean soil.
In September 1992, EPA issued an Administrative Order on Consent (AOC) that
required SMC to conduct a remedial investigation and feasibility study (RI/FS) of
remaining soil, sediment, and surface water contamination at the Site. In October
1992, the AOC was amended to include the investigation of ground water
contamination.
3.0 HIGHLIGHTS 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. A Fact Sheet on
the Site was first distributed in September 1993. Since that time, a community
relations plan was further developed and implemented at the Site. An information
repository was established in July 1995, at the Tampa Campus Library of the
University of South Florida, at 4202 East Fowler Avenue, Tampa, Florida.
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Record of Decision
Stauffer Management Company Superfund Site
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The Remedial Investigation/Feasibility Study Reports, the Baseline Risk Assessment
Report, and Proposed Plan for the SMC Site were released to the public in July 1995.
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
information repository. In addition, the Administrative Record and the Site (project)
files are available for review at the EPA Region IV offices in Atlanta, Georgia.
Notices of availability of these documents were published in the Tampa Tribune on
July 20, 23, 26, and 27,1995.
On July 27, 1995, EPA presented its preferred remedy for the Stauffer Management
Company Superfund Site during a public meeting at the Kenley Park Recreation
Center, 1301 North 66th Street, Tampa, Florida. At this meeting, representatives of
EPA 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 60-day public comment period was held from July 20, 1995 through September 17,
1995. 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 ACTION
This ROD addresses the cleanup of pesticide contamination in soils, sediments, and
ground water at the SMC Site. The contaminants are similar to those produced and
distributed at the Site. Contact with contaminants at the Site pose a risk to human
health because EPA's unacceptable risk range is exceeded and concentrations are
above ARARs. Contaminants also pose a risk to environment receptors. The
purpose of this proposed action is to prevent current or future exposure to
contamination. This will be the final response action for this Site.
5.0 SUMMARY OF SITE CHARACTERISTICS
5.1 Physiography and Topography
The Site is located in the Gulf Coastal Lowlands Physiographic Province of Southwest
Florida. This physiographic region is characterized by wetlands interspersed with
pine-palmetto flatwoods. Topographic relief at the Site is gentle and slopes eastward
toward the Tampa Bypass Canal. Elevations at the Site range from approximately 28
feet above mean sea level (amsl) in the western portion of the Site, to a low of 15 feet
amsl in the southeastern portion of the Site in the vicinity of the Tampa Bypass
Canal. All surface water runoff at the Site drains to the onsite ponds or to the onsite
ditch.
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Stauffer Management Company Superfund Site
Page 6
5.2 Geologv/Hvdrogeology
The regional geology and hydrogeology of Hillsborough County consists of 8,000 to
13,000 feet of unconsolidated and consolidated sediments overlying a crystalline
basement of metamorphic or igneous rock. The two hydrogeologic units most widely
used for water supply are the surficial aquifer and the Floridan aquifer. The
Hawthorn Group exists between the surficial aquifer and Floridan aquifer and has
limited use in some parts of Hillsborough County. In western Hillsborough County
the Hawthorn Group is comprised of three lithostratigraphic units. These units are,
in descending order, the Peace River Formation, the Arcadia Formation, and the
Tampa Member. Productive carbonate zones existing within the Hawthorn Group
can be considered as the upper Floridan Aquifer.
The surficial aquifer at the Site varies in thickness from 5 to 17 feet, appearing
thickest toward the eastern Site boundary. The aquifer is composed predominately of
fine- to medium-grained quartz sands, with some clayey sand lenses. Recharge to
the surficial aquifer comes directly from rainfall infiltration. Ground water flow in
the aquifer, based on historical water level data, is generally toward the Tampa
Bypass Canal. Because the Tampa Bypass Canal channel fully penetrates the entire
surficial aquifer, ground water from the surficial aquifer discharges to the canal.
The confining unit at the Site, below the surficial aquifer and above the sandy
limestone aquifer, consists primarily of bluish to greenish gray clay with lenses of
sand, shell fragments, and sandy clay, and varies in thickness from 10 to 22 feet.
This hydrogeologic unit is anticipated to correspond with the Peace River Formation.
The unit is regarded as semi-confining due to the presence of permeable sand lenses.
The carbonate rock below the semi-confining unit is considered the upper water-
bearing zone of the Roridan aquifer and is the Arcadia Formation, including the
Tampa Member. The thickness of the unit beneath the Site is unknown; only the top
20 to 25 feet of the formation was penetrated during previous site investigative
activities. Deeper portions of the Floridan aquifer investigated during the RI are
referred to as the intermediate Floridan aquifer. Regional literature indicates that the
upper Floridan may be as thick as 200 feet. The grey to white sandy limestone and
dolostone contain varying amounts of fine-grained, well rounded sand, chert,
concretions, and marl.
Recharge to the upper Floridan aquifer is through water leakage through the sandy
day lenses of the confining unit. The ground water flow direction in the upper
Floridan aquifer at the Site is toward the Tampa Bypass Canal. The Tampa Bypass
Canal cuts through the surficial aquifer and into the upper Floridan aquifer,
providing a discharge point for both aquifers.
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Stauffer Management Company Superfund Site
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5.3 Surface Water Hydrology
The surface water hydrology at the Site is markedly influenced by the surficial sands.
The surficial sands are very permeable, allowing precipitation to infiltrate into the
sands and recharge the surficial aquifer. The surficial sands are permeable enough
such that overland flow does not occur during most precipitation events. In the
event that the precipitation rate exceeds the infiltration capacity of the sands,
overland flow drains to the east into the ponds along the eastern side of the Site and
to the ditch in the wooded southern portion of the Site. Surface waters entering the
ditch are directed into the Tampa Bypass Canal, which flows into the Palm River,
McKay Bay, Hillsborough Bay, Tampa Bay, and eventually into the Gulf of Mexico.
5.4 Wildlife/Natural Resources
The U.S. Fish and Wildlife Service (USFWS) and the Florida Game and Fresh Water
Fish Commission (FGFWFC) were contacted concerning the available information on
wildlife and natural resources in the vicinity of the SMC Site. COM also conducted a
comprehensive threatened and endangered species survey to better define
environmental receptors at the Site. The investigation concluded that there is a wide
diversity of habitats which support an abundance of plant and animal life.
Portions of the vegetated area have been disturbed and community structures have
been recently changed due to site investigation activities. Since much of the area has
been disturbed, opportunistic plants such as weeds and vines have grown on the Site
and produced dense thickets in the southeast portion of the Site. Small stands of live
oak (Quercus virginiana) with and understory of palmettos (Sabel palmetto and/or
Serenoa repens) are found over most of the Site area. Bamboo vme.(Smilax laurilolia)
and Brazilian Pepper (Schinus terebinthifolius) provide significant ground cover in the
southern portion of the surveyed area. The Brazilian Pepper is an exotic species
commonly found in disturbed fields. The Cajeput Tree (Melaleuca quinquenervia) is
another aggressive plant, and an indicator species of disturbed areas, noted at the
SMC Site.
Based on previous Site visits and interviews with federal and state representatives,
the wildlife expected at the Site included a variety of migratory and resident birds,
especially wading birds, songbirds, and water fowl; mammals, such as raccoon,
marsh rabbits, and squirrels; and a variety of reptiles and amphibians. However,
recent habitat disturbance at the Site has likely disrupted traditional wildlife usage
patterns. The following endangered species (E) and species of special concern (SSC)
were identified at the SMC Site at the time of the survey:
American alligator (Alligator mississippiensis) - SSC
Brown Pelican (Pelecanus occidentalis) - SSC
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Stauffer Management Company Superfund Site
Page 8
Snowy Egret (Egretta thula) - SSC
Wood Stork (Mycteria americana) - E
A number of other endangered species and species of special concern were not
observed, but could be expected to be present in habitats at the Site.
5.5 Summary of Site Contaminants
5.5.1 Substances Detected in Soil
Fifteen composite surficial soil samples were collected in the western and southern
areas of the SMC Site, as shown in Figure 5-1, during the RI. Each sample consisted
of 5-point composite samples collected from the ground surface to a depth of 6 inches
below land surface (bis). Each sample was analyzed for the contaminants of concern
(proprietary pesticides, chlorinated pesticides, and VOCs). In addition, eight of the
samples were analyzed for target analyte list (TAL) metals and extractables. Sample
CS-1 was used as a background sample to compare to all soil analytical results.
Eight soil borings were advanced from the ground surface to a depth of 10 feet bis;
boring locations are shown in Figure 5-2. Forty 2-foot interval samples (0 to 2 feet, 2
to 4 feet, 4 to 6 feet, 6 to 8 feet, and 8 to 10 feet), five from each boring, were
collected and analyzed for proprietary pesticides, chlorinated pesticides, and VOCs.
Eight composite samples from 0 to 10 feet were analyzed for extractables, chlorinated
pesticides and polychlorinated biphenyls (PCBs), and TAL metals. VOC samples
were collected from the horizon with the highest flame ionization detector (FID)
headspace reading.
In addition to the surface and subsurface soil samples collected during the RI,
analytical data from soil samples collected in the 1990 ERM investigation and
analytical data from soil samples collected in the 1991 COM investigation were
considered in evaluating remaining soil contamination at the Site. The 1990 and 1991
samples were analyzed for proprietary pesticides, chlorinated pesticides, and VOCs.
These sample results were originally used to determine which areas were to be
addressed in the removal action conducted in 1993 and 1994, and were applicable in
determining areas where soil contamination remains at the Site.
Soil at the Site was found to contain pesticide contamination. The extent of pesticide
contamination in surface and subsurface soils at the Site are illustrated in Figure 5-3.
VOCs, extractables, and metals were detected in soils at the Site, but are generally co-
located where pesticide contamination remains. A summary of substances detected
in surface soils (0-2 ft) at the Site is provided in Table 5-1. Substances detected in
subsurface soils are summarized in Table 5-2.
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Stauffer Management Company Superfund Site
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FIGURE 5-1: SURFACE SOIL COMPOSITE SAMPLING LOCATIONS
too
"^
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Stauffer Management Company Superfund Site
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FIGURE 5-2: SOIL BORING LOCATIONS
sğ. BOBC tooawe
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Stauffer Management Company Superfund Site
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TABLE 5-1: SUBSTANCES DETECTED IN SURFACE SOILS
Ground Water Analyte
Site-Related Samples
Frequency
of
Detection
Proprietary Pesticides:
Atrazine
Butvlate
Carbophenothion
Cvdoate
EPTC
Fonofos
Molinate
Pebulate
Vemolate
1/19
5/27
6/27
4/27
3/27
4/41
5/41
4/27
4/27
Range of
Detected
Concentrations
(mgAcg)
Average
Detected
Concentration
(rag/kg)
Background Samples
Frequency
of
Detection
Range of
Detected
Concentrations
(mg/kg)
Average
Concentration
(mg/kg)
0.026
0.037-47
0.070-20
0.091-0.288
0.032-0.072
0.028-13
0.022-2.9
0.046-0.296
0.032-0.7
0.026
9.5
47
0.185
0.042
0.367
1.1
0.144
0776
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
Chlorinated Pesticides:
4,4'-DDD
4,4'-DDE
4,4'-DDT
Aldrin
Alpha-BHC
Chlordane
Dieldrin
eamma-BHC (Undane)
Toxaphene
16/41
20/41
21/41
1/28
1/28
3/41
2/41
1/19
7/27
0.009-16.7
0.003-43.9
0.002-72
0.05
1.54
0.31-148
0.098-4.6
0.71
0.2-437
13.4
2.9
9.8
0.05
1.54
59
2.3
0.71
181.0
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND .
ND
Volatile Organic Chemicals
Acetone
Ethvlbenzene
Methvlene Chloride
Xvlenes
2/22
2/8
3/22
3/8
0.068-0.28
0.004-0.006
0.004-0.006
0.004-210.0
0.174
0.005
0.005
52.5
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
Inorganics:
Aluminum
Arsenic
Barium
BervUium
Cadmium
Calcium
Chromium (IV)
Copper
Iron
Lead
7/7
4/7
4/7
1/7
2/7
7/7
3/7
6/7
7/7
7/7
139.0-6,960.0
0.59-1.4
9.85-75.4
0.63
0.28-0.44
180.0-40,900.0
3.45-14.6
3.7-105.0
334.0-5,630.0
15.3-43.6
1,612.3
1.0
41.0
0.6
0.4
7,673.1
87
30.0
1,524.6
247
1/1
ND
1/1
ND
1/1
1/1
1/1
1/1
1/1
1/1
351.0
ND
45.8
ND
0.45
1,040.0
3.1
11.4
1,720.0
75.1
351.0
ND
45.8
ND
0.45
1,040.0
3.1
11.4
1,720.0
75.1
-------
Record of Decision
Stauffer Management Company Superfund Site
Page 12
TABLE 5-1: SUBSTANCES DETECTED IN SURFACE SOILS (continued)
Ground Water Analyte
Site-Related Samples
Frequency
of
Detection
Range of
Detected
Concentrations
(mg/kg)
Average
Detected
Concentration
(mgAcg)
Background Samples
Frequency
of
Detection
Range of
Detected
Concentrations
(mg/kg)
Average
Concentration
-------
Record of Decision
Stauffer Management Company Superfund Site
Page 13
TABLE 5-2: SUBSTANCES DETECTED IN SUBSURFACE SOILS
Parameter
Soil (2-4 ft)
Frequency
Detection
Range of
Cone.
(me/ke>
Soil (4-6 ft)
Frequency
of
Detection
Range of
Cone.
(BTIR/kK)
Soil (6-8 ft)
Frequency
_ of
Detection
*s&?
(mg/ke)
Soil (8-10 ft)
Frequency
_ of
Detection
Range of
Cone.
(mK/te)
Proprietary Pesticides
Butylate
Carbophenothion
Cycloate
EPTC
Fonofos
Molinate
Pebulate
Vemolate
Chlorinated Pesticides
4,4-DDD
4,4-DDE
4,4-DDT
Aldrin
alpha-BHC
beta-BHC
Chlordane
delta-BHC
Dieldrin
Endosulfan I
Endosulfan Sulfate
Endrin
Endrin Aldehyde
Ethion
Heptachlor
Heptachlor Epoxide
Malathion
Toxaphene
1/8
1/8
1/8
1/8
1/8
1/8
1/8
1/8
2/8
ND
3/8
ND
1/8
ND
ND
ND
1/8
ND
ND
2/8
'ND
ND
ND
ND
ND
1/8
4.5
3.6
7.8
1.2
0.45
1.7
1.2
4.4
1/8
2/8
1/8
1/8
1/8
1/8
1/8
1/8
12
23-16
11
4.5
5.1
20
11
30
0.29-0.52
0.27-1.4
0.088
0.2
0.089-36
130
2/8
1/8
2/8
1/8
ND
1/8
1/8
ND
1/8
1/8
ND
2/8
1/8
1/8
ND
1/8
ND
ND
2.7-11
11
0.31-7.1
15
23
72
6.1
4.4
2-24
2.6
5.6
1.8
1/8
2/8
1/8
1/8
1/8
1/8
1/8
1/8
4/8
1/8
4/8
1/8
ND
ND
ND
1/8
1/8
ND
ND
1/8
1/8
1/8
ND
ND
1/8
1/8
1.5
0.79-3.2
43
0.87
0.61
2.7
1.8
2.9
0.16-7.9
0.089
0.068-53
0.065
0.21
0.49
110
0.65
0.16
079
330
ND
1/8
ND
1/8
ND
1/8
1/8
1/8
3/8
1/8
2/8
ND
ND
ND
ND
1/8
1/8
1/8
1/8
1/8
1/8
2/8
1/8
1/8
1/8
1/8
2
0.057
1.7
1.7
U
0.36-56
1.4
0.97-4.5
0.22
O.M
O.OS2
0.11
0.24
0.87
0.12-98
59
0.2
0.17
310
Volatile Organic Chemicals
Acetone
Ethvlbenzene
Toluene
Xylenes, Total
3/8
1/8
1/8
2/8
0.043-0.160
28
0.0049
0.0029-180
3/8
3/8
1/8
3/8
0.028-0.71
0.0049-17
0.28
0.012-110
5/8
2/8
1/8
3/8
0.030-1.1
0.46-4.1
1.6
0.0072-32
5/8
2/8
ND
2/8
0.029-3.6
1.7-12
29-76
mg/kg = milligrams per kilogram
ND = Not Detected above quantitation limit
NA = Not Analyzed
-------
Record of Decision
Stauffer Management Company Superfund Site
Page 14
In addition to results from the remedial investigation, data from the removal action indicated that
pesticides remain in subsurface soils. Table 5-3 presents the results of confirmatory sampling and
analyses by compound for each removal action area.
5.5.2 Substances Detected in Ground Water
5.5.2.1 Monitoring Well Network
Fourteen new ground water monitoring wells were installed during the remedial investigation. A
total of 30 monitor wells in 12 well clusters now exist at the Site and were sampled in the remedial
investigation. At each well duster, a surficial aquifer well (A) and an upper Floridan aquifer well
(B) are present. At six well cluster locations, an additional intermediate Floridan aquifer well (C)
as been installed at greater depths in the Floridan aquifer. Well clusters MWT-01 and MWT-03
were considered background ground water locations. Figure 5-3 shows the location of the ground .
water monitoring wells.
5.5.2.2 Substances Detected in the Surficial Aquifer
Twelve surficial aquifer wells were sampled and analyzed for priority pesticides, chlorinated
pesticides, and VOCs. Two surficial aquifer well samples (MWT-14A and MWT-16A) were also
analyzed for TAL metals and extractables. Sampling results are summarized in Table 5-4. Ground
water flow directions in the surficial aquifer were determined to be generally to the south east
toward the Tampa Bypass Canal. The hydraulic gradient across the Site was determined to be 0.01
feet per foot (ft/ft) in the surficial aquifer. A ground water mound is evident in the vicinity of the
ponds indicating a recharge location for the surficial aquifer. The aquifer transmissiviry is
expected to vary considerably due to the presence of the intermittent clayey sand layers
throughout the surficial aquifer sands. The Tampa Bypass Canal acts as a barrier and discharge
point for the surficial aquifer.
5.5.2.3 Substances Detected in the Floridan Aquifer
Eighteen surficial aquifer wells were sampled and analyzed for priority pesticides, chlorinated
pesticides, and VOCs. Two upper Floridan aquifer well samples (MWT-1B and MWT-6B) and one
intermediate Floridan aquifer well sample (MWT-12C) were also analyzed for TAL metals and
extractables. Sampling results are summarized in Table 5-5. At locations with upper and
intermediate Floridan aquifer monitoring wells, maximum detected concentrations were
considered. Ground water flow directions in the Floridan aquifer were determined to be generally
to the east- southeast toward the Tampa Bypass Canal. The onsite ponds do not affect ground
water flow patterns in the Floridan aquifer. The hydraulic gradient across the Site was determined
to be 0.006 feet per foot (ft/ft) in the Floridan aquifer. Other aquifer are not known. The Tampa
Bypass Canal intersects the Floridan aquifer, permitting an upward hydraulic gradient along the
eastern portion of the Site.
-------
TABLE 5-3: REMOVAL ACTION CONFIRMATORY SAMPLING SUMMARY
Parameter
Proprietary Pesticides (tttg/kg)
.Butylate
Carbophenothion
M-Carbophenathion
Cycloate
EPIC
Fonofos
M-Parathlon
Molinate
Vernolate
Chlorinated Pesticides (mg/kg)
Aldrin
alpha-BHC
gamrna-BHC
delta-BHC
4,4'-DDD
4,4'-DDE
4,4'-DDT
Dieldrin
Toxaphene
North
east
Corne
r
150
32
1,405
9
119
442
BDL
146
263
BDL
6
30
1
453
2
2,514
4
BDL
A10
Hot Spot
l
BDL
BDL
BDL
BDL
BDL
BDL
BDL
BDL
BDL
BDL
BDL
BDL
BDL
28
BDL
- 200
BDL
BDL
Crushed
Drum Area
BDL
73
1
BDL
BDL
BDL
BDL
BDL
BDL
32
BDL
BDL
BDL
2
BDL
6
BDL
1,506
A25
Hot Spot
BDL
BDL
BDL
BDL
BDL
BDL
BDL
BDL
BDL
BDL
BDL
BDL
BDL
2
BDL
5
BDL
BDL
Rail Spur
Terminus
Area
2
1
98
5
7
BDL
2
3
17
BDL
BDL
BDL
BDL
1
BDL
BDL
4
BDL
Southern
Area
BDL
89
129
BDL
BDL
BDL
BDL
BDL
BDL
BDL
BDL
BDL
BDL
49
1
10
BDL
BDL
Buried
Metal Area
BDL
BDL
BDL
BDL
BDL
BDL
BDL
BDL
25
BDL
BDL
BDL
BDL
23
15
154
BDL
BDL
NOTES:
1. Only those pesticides detected are indicated above.
2. Values represent a summation of concentrations from all samples collected in each area.
3. BDL - Below detection limit of 1 mg/kg.
-------
Record of Decision
Stauffer Management Company Superfund Site
Page 16
FIGURE 5-3: GROUND WATER SAMPLING LOCATIONS
/ /OMWT-ISA
/ ,'OMMT-EC
// / / &MWT-SB
,' / /
^ABprox.ftOO ft.
MWT-148-^' O I I
UWT-MAf^/ /
FENCE
V-. WOODED AREA
MWT-3A EXISTING SURFKIAL
AQUIFER MONITOR WELL
UWT-R6 A EXISTING UPPER
FLOfUOAN AQUIFER UOMTOR WELL
MWT-I2C EXISTING 04TERMEOIATE FLORDAN
AOUFER MONITOR WELL
SG-2 e EXISTING STAFF GAUGE
UWT-ITAQ NEW SURFIOAL
AOUFER MONI10R WELL
A NEW UPPER
FLOfUOAN AQUIFER MONITOR WELL
Q NEW INTERMEDIATE FLORIDA*
AOUFER MONITOR WELL
SG-I O NEW STAFF GAUGE
-------
Record of Decision
Stauffer Management Company Superfund Site
Page 17
TABLE 5-4: SUBSTANCES DETECTED IN SURFICIAL AQUIFER
Ground Water Analyte
Site-Related Samples
Frequency
of
Detection
Range of
Detected
Concentrations
<|ig/L)
Average
Detected
Concentration
-------
Record of Decision
Stauffer Management Company Superfund Site
Page 18
TABLE 5-5: SUBSTANCES DETECTED IN FLORIDAN AQUIFER
Ground Water Analyte
INORGANICS:
Aluminum
Calcium
Iron
Magnesium
Manganese
Potassium
Sodium
PESTICIDES:
Aldrin
Alpha-BHC
Beta-BHC
Delta-BHC
Butvlate
Cvcloate
4,4-DDD
4,4-DDE
4,4-DDT
Dieldrin
Endosulfan I
Endosulfan Sulfate
EPTC
Fonofos
Heptachlor
Molinate
Pebulate
Variolate (Vernam)
Samples Taken In Floridan Aquifer
Frequency
_, of.
Detection
Range of
Detected
Concentrations
Average
Concentration
-------
Record of Decision
Stauffer Management Company Superfund Site
Page 19
5.5.3 Substances Detected In Surface Water
Thirteen surface water samples were collected from both onsite and offsite locations
(Figure 5-4). SW-1 was designated as representative of background conditions in the
Tampa Bypass Canal. All samples were analyzed for TCL parameters, TAL metals,
proprietary pesticides, and inorganics. Sampling results are summarized in Table 5-6.
Surface water in the onsite ponds and ditch contained a number of pesticide
concentrations. Only one pesticide was detected in surface water from offsite ditches,
and no pesticides were detected in the Tampa Bypass Canal.
5.5.4 Substances Detected'in Sediment
Thirteen sediment samples were collected from the same locations onsite and offsite
as surface water samples (Figure 5-4). SD-1 was designated as representative of
background conditions in the Tampa Bypass Canal. All samples were analyzed for
TCL parameters, TAL metals, proprietary pesticides, and inorganics. Sampling
results are summarized in Table 5-7. Sediment in the onsite ponds and ditch
contained a number of pesticide concentrations. No pesticides were detected in
sediment from offsite ditches, and no pesticides were detected in the Tampa Bypass
Canal.
6.0 SUMMARY OF SITE RISK
6.1 Risk Assessment Overview
CERCLA directs EPA 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 Remedial Investigation (RI)
and includes analyses of samples of ground water, surface water, sediment and 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 due to exposure
to ground water. Section 6.7 describes the potential impacts on aquatic and terrestrial
life associated with contamination in sediment and surface water at the SMC Site.
-------
Record of Decision
Stauffer Management Company Superfund Site
Page 20
FIGURE 5-4: SURFACE WATER AND SEDIMENT SAMPLING LOCATIONS
N
r = 300-
150 0
SW/SD-I
i SW/SO-2
ğS\f/SD-3
/SD-4
LEGEND:
5 SEDIMENT SAMPLE
O SURFACE WATER SAMPLE
. DRAINAGE DITCH
DRECTION OF SURFACE WATCH FLOW
*-Ti CULVERT LOCATION
.PPROX. 200 FT.
-------
Record of Decision
Stauffer Management Company Superfund Site
Page 21
TABLE 5-6: SUBSTANCES DETECTED IN SURFACE WATER
Parameter
Proprietary Pesticides
Butylate
EPTC
Molinate
Pebulate
Vernolate
Chlorinated Pesticides
4^'-DDD
4,4'-DDE
4,4'-DDT
aloha-BHC
beta-BHC
delta-BHC
Dieldrin
Endrin
Ethion
Malathion
Methoxvchlor
VOCs
Acetone
Toluene
Inorganics
Aluminum
Arsenic
Calcium
Iron
Lead
Magnesium
Manzanese
Nickel
Potassium
Sodium
Zinc
Concentrations (ng/U
Tampa Bypass Canal
SW-1
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
60,700
ND
ND
6,080
ND
ND
4.240
12300
ND
SW-2
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
64,800
ND
ND
6,680
ND
ND
3,730
15,200
ND
SW-3
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
66,300
ND
ND
6310
ND
ND
4,380
15,400
ND
SW-4
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
61,000
ND
ND
6,170
ND
ND
4,050
12.400
ND
SW-5
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
327,000
ND
ND
914,000
71
ND
226,000
732,000
ND
Onsite Ditch
SW-6
ND
ND
41
ND
ND
0.47
0.7
05r
ND
1.4
0.64
ND
ND
IS*
2.1*
ND
ND
15
335
ND
68,000
3,600
ND
3,850
220
ND
1,800
10.700
ND
SW-7
ND
ND
ND
ND
0.651
0.19J
0.14
ND
ND
0.29
0.12
0.70
0.14
ND
ND
0.39*
ND
ND
ND
ND
77,500 .
1300
ND
4.630
296
ND
2340
12.400
ND
SW-8
ND
2.8
55
11
ND
ND
ND
ND
ND
0.29
ND
OS
ND
ND
ND
ND
ND
ND
ND
ND
66,100
1.830
ND
4370
279
ND
2370
12.500
ND
Onsite Ponds
SW-10
ND
72.
47
ND
. 12
ND
ND
ND
ND
26'
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
179,000
ND
ND
6,370
ND
ND
2,390
23,400
ND
SW-11
ND
ND
ND
ND.
ND
ND
ND
ND
0.091J
ND
ND
ND
ND
ND
ND
ND
15
ND
9510
ND
183,000
3,750
10
4.980
176
ND
1,290
4,960
118
Offsite Ditches
SW-9
'ND
ND
ND
0.741
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
87,000
ND
ND
22,000
ND
ND
6740
151,000
ND
SW-12
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
254
26.8
198,000
5,760
ND
7,950
927
ND
ND
21,000
ND
SW.13
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
59.400
800
ND
16,800
337
80.5
ND
36.500
ND
NOTES: ND - Not detected
"~~~~ * Quanntation confirmation not conclusive
] - Estimated value.
-------
Record of Decision
Stauffer Management Company Superfund Site
Page 22
TABLE 5-7: SUBSTANCES DETECTED IN SEDIMENT
PARAMETERS
Proprietary Feticides
Butvlate
Carbophenothion
Fonofos
Molinate
Pebulate
Vernolate
Chlorinated Pesticides
4/4'-DDD
4,4'-DDE
4.4--DDT
Aldrin
beta-BHC
Chlordane
delta-BHC
Dieldrin
Endrin
VOCs
Acetone
Chlorobenzene
Ethvlbenzene
Methvlene Chloride
Toluene
Xvlenes (total)
Inorganics
Aluminum
Arsenic
Barium
Cadmium
Calcium
Chromium
Copper
Iron
Lead
Maznesium
Manganese
Nickel
Potassium
Selenium
Sodium
Vanadium
Zinc
CONCENTRATIONS (me/kg)
Tampa Bypass Canal
SD-1
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND-
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
278
ND
ND
ND
2,650
ND
ND
301
5.3
ND
32
ND
ND
ND
ND
ND
14.4
SD-2
ND
ND
ND -
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
0.052!
ND
ND
ND
ND
ND
3,020
0.99
24.5
0.48
20300
L 10.6
5.9
2.820
25.6
835
26.2
ND
147
0.49
86.4
9.6
252
SD-3
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
3,140
1.6
27.8
055
19,900
16.3
6.4
3,190
31
747
30.8
ND
210
0.6
106
13.9
606
SD-1
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
0.0641
ND
ND
ND
ND
ND
9,460
1.4
48.6
0.65
20,500
24.3
10.8
5340
35.4
993
40.4
5.4
488
0.96
108
19.8
405
SD-5
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND '
ND
0.039]
ND
ND
ND
ND
ND
1,140
1.1
10.1
0.87
49300
8.4
10.1
2350
44.6
985
28.3
ND
319
ND
2340
5
195
Onsite Ditch
SD-6
ND
ND
ND
ND
ND
ND
8.8
1.1
ND
ND
ND
ND
ND
3.4
ND
0.220
0.0073J
ND
ND
0.013
ND
1,730
2.1
'ND
0.76
2250
ND
62.4
1.130
40.1
93.7
7.2
ND
ND
ND
ND
9.7
97.5
SD-7
ND
ND
ND
ND
ND
ND.
ND
ND
ND
ND
ND
ND
ND
ND
ND
0.062J
ND
ND
0.010J
ND
ND
4.070
ND
39.5
2.7
49,000
14.5
93.8
5,990
106
U20
S2.1
8.8
634
23
ND
25.0
659
SD-8
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
2.0
ND
ND
ND
ND
ND
l',160
2.7
11.5
0.95
5/420
4.7
19
2.640
30.2
192
15.5
63.6
90.5
0.43
81.5
7.4
168
Onsite Ponds
SD-10
ND
130
ND
12
ND
5.1J
16*
82
120-
20
ND
170
26
no*
36-
ND
1.7
ND
ND
ND
210
11,700
8.1
94.2
2.7
16.300
380
116
23,400
1,800
1360
195
ND
1340
ND
1/420
ND
407
SD-11
63
19
22
ND
4.1
5.0
28
35'
12
ND
ND
ND
ND
ND
ir
ND
0.37
5.1
ND
ND
6.5
3,610
52
42.1
13
2,760
58.7
195
10,900
95.4
285
. 33.9
ND
ND
ND
ND
13.1
200
Offcite Ditches
SD-9
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
0.00211
ND
ND
606
ND
ND
038
2,130
ND
ND
603
9.2
555
16.6
ND
113
ND
794
ND
69.4
SD-12
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
1,170
2.7
21.1
ND
49300
5.1
4.4
1,680
10.2
262
44.9
ND
84.8
ND
75.9
3.8
136
SD-13
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
1.180
1.8
23.6
0.66
21,800
8.7
19.1
3,180
49.7
688
338
3.6
75.3
ND
509
4.0
262
NOTES: ND - Not detected
~~~~"~ " - Ouantitation confirmation not conclusive
J - Estimated value.
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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
and selection of chemicals included the following:
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 (i.e., only slightly
elevated above naturally occurring levels) and only toxic at very high
doses may be deleted.
Inorganic and organic chemicals detected in ground water that exceed j
state or federal maximum contaminant levels (MCLs) should be selected
as COPC.
Inorganic and organic chemicals detected in ground water that exceed .
concentrations that represent a cancer risk level greater than 1 x 10* or a
Hazard Quotient (HQ) of 0.1 using residential tap water assumptions
should be selected as COPC. Region in Risk-Based Concentration
Tables were used to screen chemicals.
As a result of applying the above listed criteria, Table 6-1 lists the contaminants of
potential concern (COPC) associated with the SMC Site. The chemicals 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 Concern in Surficial Soil
Two inorganics were eliminated because concentrations are within two times
background concentrations. Four naturally occurring essential nutrients were
eliminated. Eighteen chemicals were eliminated because they occur at concentrations
below the Region HI Risk-Based screening criteria. Fourteen chemicals reported in
the surface soil onsite meet the COPC criteria (Table 6-1). These were evaluated in
the quantitative risk assessment.
Region IV does not consider direct exposure to subsurface soils to be a standard
scenario that should be evaluated in the baseline risk assessment. Therefore,
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TABLE 6-1: CONTAMINANTS OF POTENTIAL CONCERN
Chemical
Pesticides:
4,4'-DDD
4,4'-DDT
4,4'-DDE
Aldrin
alpha-BHC
Atrazine
beta-BHC
Carbophenothion
Chlordane
Cycloate
delta-BHC
Dieldrin
Endosulfan I
Endosulfan II
Endosulfan Sulfate
Endrin
EPTC
Fonofos
Gamma-BHC (LLndane)
Heptachlor
Heptachlor Epoxide
Molinate
Pebulate
Toxaphene
Vemolate (Vernam)
Volatile Organics:
Bis(2-
ethylhexyDphthalate
Bromodichloromethane
Chlorobenzene
Chloroform
1,2-Dichloroethene (total)
Trichloroethane
Xylene (total)
Inorganics:
Aluminum
Arsenic
Beryllium
Cadmium
Chromium
Lead
Manganese
Nickel
Thallium
Zinc
Floridan
Aquifer
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Surnrial
Aquifer
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Surface
Soil
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Onsite
Surface
Water
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Offsite
Surface
Water
X
X
X
X
Onsite
Sediment
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Offsite
Sediment
X
X
X
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Stauffer Management Company Superfund Site
Page 25
chemicals of potential concern were not selected for subsurface soil; however,
subsurface soil contamination was evaluated to determine what concentration would
be protective of ground water (Section 7.1).
6.2.3 Contaminants of Potential Concern in Surficial Ground Water
Five naturally occurring essential nutrients were eliminated because they are toxic
only at very high doses. Three chemicals were eliminated because they were below
the Region HI Risk-Based screening criteria. Nineteen chemicals reported in the site-
related monitoring wells meet the COPC criteria (Table 6-1). These were evaluated in
the quantitative risk assessment.
6.2.4 Contaminants of Potential Concern in the Floridan Aquifer
Five naturally occurring essential nutrients were eliminated because they are toxic
only at very high doses. Six chemicals were eliminated because they were below
Region III Risk-Based screening criteria. Twenty chemicals reported in the site-
related monitoring wells meet the COPC criteria (Table 6-1). These were evaluated in
the quantitative risk assessment.
6.2.5 Contaminants of Potential Concern in Surface Water
Five naturally occurring essential nutrients were eliminated because they are toxic
only at very high doses. One chemical was eliminated because concentrations did -
not exceed National Abient Water Quality Criteria. Fourteen chemicals reported in -
the onsite surface water (i.e., ponds and ditch) meet the COPC criteria; four chemicals
reported in the offsite surface water (i.e., Tampa Bypass Canal and ditches) meet the
COPC criteria (Table 6-1). These were evaluated in the quantitative risk assessment.
6.2.6 Contaminants of Potential Concern in Sediment
Five naturally occurring essential nutrients were eliminated because they are toxic
only at very high doses. Twenty chemicals were eliminated because concentrations
did not exceed Region in Risk-Based screening criteria. Fifteen chemicals reported in
the onsite sediment (i.e., ponds and ditch) meet the COPC criteria; three chemicals
reported in the offsite sediment (i.e., Tampa Bypass Canal and ditches) meet the
COPC criteria (Table 6-1). These were evaluated in the quantitative risk assessment.
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 SMC Site. Whether
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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 defined 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, and Transport
Surface and subsurface soils beneath the Stauffer Management Company Site became
contaminated through the leaching of waste from buried drums and the former
pesticide disposal areas, and from leaks or spills from past plant operations. The
subsequent infiltration of precipitation resulted in contaminant movement from
surface and subsurface soil to ground water. Runoff and erosion resulted in
contamination of surface water and sediment.
Most of the source was remediated during removal activities; however, the soils
containing total pesticide concentrations greater than 1000 mg/kg (the removal
standard) may still be contributing to ground water contamination. The major
constituent release and transport mechanisms potentially associated with the Site are
the infiltration of precipitation and runoff and erosion of contaminants.
6.3.3 Potential Receptors and Routes of Exposure
6.3.3.1 Current/Future Worker
The current onsite worker was assumed to be exposed to site-related contaminants in
surface soil, onsite surface water and sediment, and air during maintenance,
landscaping, or other outdoor activities. The routes of exposure considered for the
current onsite worker were dermal contact with surface water; incidental ingestion
and dermal contact with surface soil and sediment; and inhalation of volatile
emissions or fugitive dust. It was assumed that if the Site remains industrial in the
future, a future worker would be exposed to site-related contaminants in a similar
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manner as the current worker; therefore, the future worker scenario is the same as
the current worker scenario.
6.3.3.2 Current/Future Offsite Resident
Overland flow at the site drains to the east into ponds along the eastern side of the
Site and to the ditch in the southern portion of the Site. Surface waters entering the
ditch are directed to the Tampa Bypass Canal. Ground water in both the surficial
and Floridan aquifers also discharge to the canal. The Tampa Bypass Canal is used
for sport fishing. Therefore, it was assumed that nearby residents could be exposed
to site-related contaminations in the Tampa Bypass Canal or offsite drainage ditches
during recreational and fishing activities. Potential exposure routes included
incidental ingestion, dermal contact, and ingestion of contaminated fish that may
exist in the Tampa Bypass Canal.
6.3.3.3 Future Resident
Based on surrounding land use, it was assumed that residential development might
occur onsite in the future. The routes of exposure considered for the future resident
were incidental ingestion and dermal contact with surface soil, surface water and
sediment; and consumption of contaminated fish. Ground water was evaluated due
to the possibility of future contamination of offsite private wells or the installation of
a private well onsite.
6.3.4 Exposure Point Concentrations
The 95 percent upper confidence limit (UCL) on the arithmetic mean was calculated
and used as the reasonable maximum exposure (RME) point 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 RME concentration for that contaminant. Exposures point concentrations are
summarized in the Baseline Risk Assessment. The exposure point concentrations 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.
6.3.5 Dose Assumptions
The U.S. EPA has developed exposure algorithms for use in calculating chemical
intakes through the exposure pathways and routes that are relevant for this Site.
Doses are averaged over the number of days of exposure (years of exposure x 365
days/year) to evaluate non-carcinogenic effects, and over a lifetime (70 years x 365
days/year) to evaluate potential carcinogenic health effects. Assumptions used to
evaluate each receptor are described below.
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The body weights used for the child (age 1-6) and adult are 15 kg and 70 kg,
respectively.
Exposed to soil occurs 5 days/week for 50 weeks/year (250 days/year) for the
onsite worker and 350 days/year for the onsite resident. Exposure to surface
water and-sediment occurs 45 days/year for 24 years for onsite and offsite
adult residents; 26 days/year for 25 years for the onsite worker; and 12
days/year for 6 years for the onsite child resident. Exposed to ground water
occurs 350 days/year for the onsite adult and child resident.
Incidental soil ingestion occurs at a rate of 100 mg/day for the onsite worker
and future adult resident and 200 mg/day for the future child resident.
Incidental sediment ingestion occurs at a rate of 100 mg/day for the onsite
worker and future adult resident and 200 mg/day for the future child resident.
Dermal exposure to soil considered an adsorption factor of 1.0 percent for
organics and 0.1 percent for inorganics, with an adherence factor of 1-0
mg/cm2.
Dermal exposure to sediment considered an adsorption factor of 1.0 percent
for organics and 0.1 percent for inorganics, with an adherence factor of 0.6
mg/cm2.
The drinking water ingestion rate was assumed to be 2 L/day for the adult
resident and 1 L/day for the child resident.
The surface water ingestion rate was assumed to be 0.01 L/hour and the
exposure time 2.6 hours/day by adult or child residents.
Exposure to contaminated fish was assumed to occur through ingestion of
0.145 kg of local fish per meal, 48 meats per year for 30 years.
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
potential health risks, both carcinogenic and non-carcinogenic health effects were
considered.
Cancer slope factors (CSFs) are developed by EPA under the assumption that the risk
of cancer from a given chemical is linearly related to dose. CSFs' are developed from
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laboratory animal studies or human epidemiology studies and classified according to
route of administration. The CSF is expressed as (mg/kg/day)"1 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 increased cancer risk is a probability that is generally expressed in
scientific notation (e.g., IxlO"6 or 1E-6). 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 IxlO"6 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. U.S. EPA policy has established that an upper limit cancer.
risk falling below or within the range of 1x10"* to IxlO"4 (or 1 in 1,000,000 to 1 in
100,000) is acceptable.
The toxicity criteria used to evaluate potential non-carcinogenic health effects are
reference doses (RfDs). The RfD 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 RfD, 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 RfD is less than 1.0, there is no
concern for adverse non-carcinogenic effects.
6.5 Risk Characterization
6.5.1 Overview
To evaluate the estimated cancer risks, a risk level lower than 1x10"* is considered a
minimal or de minimis risk. The risk range of IxlO"6 to IxlO"4 is an acceptable risk
range and would not be expected to require a response action. A risk level greater
than 1x10"4 would be evaluated further and a remedial action to decrease the
estimated risk considered.
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 toxirities
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.
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Carcinogenic risks and non-carcinogenic hazards were evaluated for potential
exposures to contaminants of potential concern in soil, surface water, sediment, and
ground water. The receptor population was current/future onsite worker,
current/future offsite resident and future residents. The results are summarized in
Table 6-2 and are described below.
6.5.2 Current/Future Onsite Worker
The total incremental lifetime cancer risks for the current/future onsite worker
through exposure to chemicals in surface soil, sediment, and surface water was
2x10"04, primarily due to incidental ingestion of and dermal contact with chlordane,
toxaphene, and dieldrin in surface soil. The total hazard index for the current/future
worker was 2, primarily due to incidental ingestion of and dermal contact with
chlordane and 4,4'-DDT in surface soil.
6.5.3 Current/Future Offsite Resident
Current residents near the Site were assumed to be exposed to chemicals in offsite
surface water and sediment via incidental ingestion and dermal contact. Ingestion of
contaminated fish was an additional pathway that was evaluated for the offsite
surface water medium. The total cancer risk for the current offsite resident through
all pathways was 8x10"06. The total hazard index for the current offsite resident was
0.1.
6.5.4 Future Onsite Resident/Future Resident
Potential future onsite residents at the Site were assumed to be exposed to chemicals
in onsite surface soil, and onsite and offsite sediment and surface water through
incidental ingestion and dermal contact, and fish ingestion. In addition, the future
resident (onsite or offsite) was assumed to be exposed to chemicals in ground water
through drinking water ingestion.
The total cancer risk for the future resident (adult and child) through all pathways
was 1x10"03 when exposed to chemicals in either the surfirial or Floridan aquifers/-
however, the individual pathway risks from ingesting ground water from the surficial
aquifer is SxlO"04 while the individual pathway risk from ingesting ground water from
the Floridan aquifer is 6xlO"05. Due to the characteristics of the two aquifers, it is
most likely that drinking water wells in the vicinity of the Site would be installed in
the Floridan aquifer. Primary contaminants of concern (COC's) in surface soil are
toxaphene, 4,4-DDD, 4,4-DDT, chlordane, and dieldrin; while the primary COC's in
ground water are alpha-BHC, heptachlor epoxide, beta-BHC, dieldrin, and aldrin.
Surface water was not found to be a pathway of concern; while the primary COC's in
sediment include aldrin, chlordane, and dieldrin.
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TABLE 6-2: SUMMARY OF CANCER AND NON-CANCER RISKS
Exposure
Medium / Path way
Surface Soil
Incidental Ingestion
Dermal Contact
Ground Water
Ingestion
Surface Water
Incidental Ingestion
Dermal Contact
Sediment
Incidental Ingestion
Dermal Contact
TOTAL
Current/Future
Maintenance Worker
Cancer
IxlO4
7xlO"5
NE
NE
3xlO"
NE
5x1 0"5
1x1 0"5
2x10"
HQ
1
0.5
NE
NE
0.01
NE
02
0.1
2
Current
Offsite Resident
Cancer
NE
NE
9xlO"7
7x10-*
-
.4xlO"7
2x10*
8x10-*
HQ
NE
NE
0.01
0.09
0.000006
0.002
0.0001
0.1
Future
Onsite Resident
Cancer
SxlCT4
SxlO-4
SxlCr4
1x10*
SxlO"5
'
IxKr4
3x1 (Ts
IxlO-m
HQ
Adult
1
2
10"
0.04
0.1
0.000006
0.7
0.1
Iff-
Child
10
5
30Ğ
0.006
0.5
0.000006
2
0.2
50b
NOTES: NE Not Evaluated for this receptor.
Carcinogenic toxicity value hot applicable.
* The lifetime carcinogenic risk or hazard index is provided for ingestion of ground water from the surficial
aquifer. The lifetime carcinogenic risk for ingestion of ground water from the Floridan Aquifer is 6xlO"5.
The hazard indices for ingestion of ground water from the Floridan Aquifer for adult and child residents are'
1 and 4, respectively.
b The total carcinogenic risk or hazard index provided includes ingestion of ground water from the surficial
aquifer only. The total carcinogenic risk including ingestion of ground water solely from the Floridan
aquifer is also IxlO"3. The total hazard indices including ingestion of ground water solely from the Floridan
aquifer for adult and child residents are 4 and 20.
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The total hazard index for the future adult resident was 10 when exposed to
chemicals in the surficial aquifer, primarily due to ingestion of manganese, heptachlor
epoxide, molinate, and pebulate in ground water. When exposed to chemicals in the
Floridan aquifer, the total hazard index for the future adult resident was 4, primarily
due to ingestion of manganese and molinate.
The total hazard index for the future 1-6 year old child was 50, primarily due to
ingestion of manganese, cadmium, heptachlor epoxide, molinate, EPTC, and vernolate
in the surficial aquifer. When exposed to chemicals in the Floridan aquifer, the total
hazard index for the future child was 20, primarily due to ingestion of molinate.
Also, exposure to aldrin, chlordane, and dieldrin also contributed hazard quotients
that were greater than unity through incidental ingestion of onsite sediment.
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
concentrations will remain constant over time may overestimate the lifetime
exposure. Contaminants 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 non-carcinogenic
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 greater.
6.7 Ecological 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. Surface soil, ground water, and surface
water and sediments from the in onsite ponds and ditches, as well as, offsite ditches
and the Tampa Bypass Canal were sampled to determine the extent of contamination,
as described in Section 5. Contaminants detected in each media are listed in
Table 5-1 through 5-7.
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6.7.2 Contaminants of Potential Ecological Concern
Contaminants of potential ecological concern (COPECs) were selected by eliminating
from the analysis essential nutrients considered toxic only at very high
concentrations, pesticides occurring at low frequencies, and by eliminating inorganic
analytes whose concentrations were within background concentrations.
6.7.3 Exposure Assessment
Two major habitats, terrestrial and aquatic, are represented on or near the Site. There
are two small forested areas located on the Site that may provide habitat for
terrestrial species. The aquatic habitat is represented by die two onsite pond areas, as
well as, fresh and estuarine deep-water habitat provided by the Tampa Bypass Canal.
Areas adjacent to the Site are heavily urbanized, with very little contiguous
vegetative cover.
Once the contaminants have reached the habitat, one or more of three possible
exposure routes may come into play for a specific receptor. These exposure routes
are ingestion, respiration, and adsorption (direct contact). The exposure point
concentration is the concentration of a contaminant in an environmental media to
which a specific receptor is exposed. The 95 percent upper confidence limit (UCL) on
the arithmetic mean was calculated and used as the exposure point 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. In addition, average
concentrations were evaluated as exposure point concentrations, for consideration in
making risk management decisions. The exposure point concentrations 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.
Direct contact of aquatic receptors with contaminated surface water and sediment
was evaluated. Sediment concentrations of contaminants of concern were compared
to ecological toxicity criteria for benthic invertebrate organisms. Surface water
concentrations of contaminants of concern were compared to toxirity-based water
quality criteria for all aquatic life, including plants, invertebrates, and fish. Two
surrogate terrestrial receptors (American robin and short-tailed shrew) were studied
for exposure to contaminated surface soil via transfer through the carnivorous food-
chain or secondarily through incidental ingestion of the soil.
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6.7.4 Toxicity Assessment
6.7.4.1 Surface Water/Sediment
As a means of characterizing aquatic toxicity, the EPA Region IV Waste Management
Division has established screening levels for surface water at hazardous waste sites,
primarily based upon the Ambient Water Quality Criteria. The pond sediments were
evaluated by comparing maximum sediment concentrations with NOAA Effects
Range Low (ER-L) values. Exceedence of these screening levels might indicate a
potential for adverse ecological effects (depending upon factors such as frequency of
detection, degree of exceedence, etc.), thus indicating a need for more site-specific
ecological investigations, such as toxicity testing. Maximum surface water and
sediment exposure point concentrations for each contaminant of concern were
compared to screening values for a particular contaminant of concern.
6.7.43 Surface Soil
To characterize the terrestrial toxicity due to exposure to surface soil, toxicity
reference values were developed for each terrestrial species from No-Observed-
Adverse-Effect-Levels (NOAELs) obtained from the Integrated Risk Information
System (IRIS) or from mortality events such as the death of 50 percent of the
individuals in an experimental environment (LC50 and LDso values). Exceedence of
these screening levels might indicate a potential for adverse ecological effects
(depending upon factors such as frequency of detection, degree of exceedence, etc.),
thus indicating a need for more site-specific ecological investigations, such as toxicity
testing.
6.7.5 Risk Characterization
6.7.5.1 Surface Water
Comparison of the concentrations of contaminants of concern in surface water with
regional screening values was used to assess the likelihood of adverse effects of
surface water to aquatic life. A number of contaminants in surface water exceeded
regional screening values. 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 that
both chronic and acute adverse effects may have already occurred to aquatic life
inhabiting the onsite ponds. Surface water in the adjacent Tampa Bypass Canal and
offsite ditches does not appear to be adversely affected by site-related contamination.
6.7.5.2 Sediment
Comparison of the concentrations of contaminants of concern in sediment with
regional screening values was used to assess the likelihood of adverse effects of
sediment to aquatic life. A significant number of contaminants in sediment exceeded
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screening values. Sediment screening levels were not available for all the 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 that
benthic organisms in onsite ponds may be severely affected by the presence of
pesticides. Sediment in the adjacent Tampa Bypass Canal and offsite ditches does not
appear to be adversely affected by site-related contamination.
6.7.5.3 Surface Soil
Comparison of the concentrations of contaminants of concern in surface soil with
toxicity reference values was used to assess the likelihood of adverse effects of soil to
terrestrial life. A significant number of contaminants in soil exceeded toxicity
reference values calculated for two surrogate species. The site-related chemicals
which contribute the most to the increased risk are 4,4'-DDD, 4,4'-DDE, dieldrin, and
endrin. There is an indication of possible adverse biological effects to avian and
mammalian species through food chain exposure to soil contaminants.
6.7.6 Uncertainty Analysis
The main sources of uncertainty associated with this ecological evaluation can be
attributed to the items below.
Information necessary to evaluate the potential effects of aquatic
exposures to sediment chemicals is limited.
The possibility that organisms may be acclimated or adapted to chronic
exposure to some chemicals was not considered, and as a result, risks
associated with exposure may be overestimated.
Risk estimates based solely on maximum concentrations in samples
collected during one sampling event may overestimate or underestimate
the actual population- or community-level effects.
Sediments and surface water constitute complex chemical mixtures and
it is possible that antagonistic or synergistic toxicity effects may occur
between any of the chemical constituents. These factors were not
accounted for.
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7.0 DESCRIPTION OF ALTERNATIVES
7.1 Remedial Action Objectives
Remedial action objectives (RAOs) were developed for the contaminants and media
of concern at the Stauffer Management Company Site. RAOs include restoring the
Site to beneficial use, reducing risk to human health within EPA's acceptable risk
range (i.e., total residual cancer risk between IxlO"4 to IxlO"6 and individual
contaminant HQ of 1), reducing ecological risk, and protecting ground water from
continued degradation by Site contaminants. Remediation goals (RGs) established to
satisfy these RAOs are presented in Section 7.1.5 and Table 7-1.
7.1.1 Beneficial Land Use
The Site is currently zoned for industrial use and future land use is expected to
remain industrial/commercial. Since zoning is expected to remain industrial/
commercial, remediation goals (RGs) were developed based on industrial use. The
alternatives considered will rely on institutional controls to restrict the Site to an
industrial use. Hillsborough County officials have expressed an interest in expanding
the Hillsborough County Correctional Facility onto the Site, which could be done
under current zoning. EPA toxicologists have determined that although a
correctional facility could be considered short-term residential use, outdoor exposure
of inmates is restricted. With institutional controls to prevent gardening or excessive
outdoor activity in the areas where residual pesticides are found, industrial cleanup
standards are considered protective of the health of inmates.
. 7.1.2 Human Health Risk
The estimated potential cancer and non-cancer risks to human health from exposure
of current and future onsite workers to contaminants in surface soil and future offsite
residents to contaminants in ground water are above EPA's target cancer risk range
and above a HQ of 1. EPA considered RGs to reduce the carcinogenic risk of
individual contaminants to IxlO"5 and IxlO'6 and the non-carcinogenic risk
represented by the HQ to 1.
If the carcinogenic risk of individual contaminants in soils/sediments are reduced to
IxlO"5, the residual risk remaining after remediation totals slightly less than IxlO"4. If
the carcinogenic risk of individual contaminants are reduced to IxlO"6, the residual
risk remaining after remediation totals slightly less than IxlO"5. EPA's acceptable
carcinogenic risk range is between IxlO"6 and IxlO"4; therefore either the IxlO"5 or
IxlO"6 individual contaminant RGs would result in a residual risk in the acceptable
range. Other RAOs were considered to determine which carcinogenic RG would be
most appropriate. A individual contaminant HQ of 1 for soil/sediment is generally
considered acceptable unless there is reason to believe that a large number of
contaminants affect the same target organ.
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Ground water is required to meet drinking water standards onsite and surface water
standards prior to entering the Tampa Bypass Canal. For many of the pesticide
contaminants in ground water, primary or secondary maximum contaminant levels
(MCLs) are not available. For those contaminants guidance concentrations based on
health effects were considered. Bioassay tests will be required during remedial
design to determine acceptable surface water standards for many of the
contaminants.
7.1.3 Ecological Risk
Plant and animal life will be protected to some extent by remediation of surface soil
and ground water to levels which protect human health. As ground water is
remediated, surface water, which is hydraulically connected to ground water, also
will be remediated. But sediment contamination, and the risk to wildlife and biota
from contaminated sediment, will remain high unless some action is taken to reduce
contaminant levels. Sediment RGs were calculated based on the Ecological Risk
assessment for ODD, DDE, DDT, Aldrin, Chlordane, Dieldrin, and Endrin; RGs
ranged from 0.02 to 3.3 ug/L. If remediation to these RGs requires more than one
foot of sediment removal, elimination of this exposure pathway should be considered.
This pathway may be eliminated by removing one foot of contaminated sediments
from the ponds and replacing the sediment with a one-foot thick layer of clean fill.
7.1.4 Protection of Ground Water
Subsurface soil contamination is not considered a threat to human health because
there is no current exposure pathway. Institutional controls may be required to
ensure that there are no future exposure pathways which could result due to
development at the Site. But subsurface soils, also, may contribute significantly to
ground water contamination. The ground water pathway was determined to exceed
acceptable risk levels at the Site; therefore, determination of subsurface RGs for the
protection of ground water were considered.
Soil RGs for the protection of ground water at the Stauffer Management Company
Site were determined using the Summers Model (EPA, 1989). The soil RGs derived
by this method address the possibility of contaminants leaching to ground water at
concentrations greater than the ground water RGs. Pesticides are the primary
contaminants of concern at the Site. The remediation of pesticides will reduce the
concentrations of the other contaminants to levels that are protective of ground water,
therefore soil RGs for protection of ground water were determined only for
pesticides.
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7.1.5 Remediation Goals
Surface soil RGs for protection of human health and protection of ground water,
subsurface soil RGs for protection of ground water, and ground water RGs are
presented in Table 7-1. Surface soil RGs are reflective of 1x10"6 cancer risk RGs or
ground water protection RGs for two reasons: residual risk is lower; and IxlO"6 RGs
are generally in the same order magnitude as the ground water protection RGs.
7.2 Soil/Sediment Remedial Alternatives
The FS report included an evaluation of numerous cleanup methods for
soil/sediment. As required by CERCLA, a no further action alternative was
evaluated to serve as a basis for comparison with the other active cleanup methods.
The cleanup methods to address site-related contamination are presented below. A
total of eight (8) soil/sediment remediation alternatives have been considered. These
alternatives represent the range of remedial actions considered appropriate for the
Site. Potential Action-Specific Applicable or Relevant and Appropriate Requirements
(ARARs) are summarized in Table 8-2 for these alternatives.
7.2.1 Alternative No. IS: No Action
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, EPA would take no action to remedy any
contaminated soil and sediment at the Site. The potential risks posed by the presence
of contamination in soil and sediment will not be minimized by this action.
7.2.2 Alternative No. 2S - Institutional Action
This alternative involves physical and legal controls to restrict human behavior and
reduce risks to human health. Physical controls would involve the use of existing
fence to limit future exposure to contaminated areas at the Site. Legal controls would
involve the filing of deed notices and/or restrictions in public property records. The
present worth cost of this remedy represents only periodic fence maintenance and
repairs. This alternative reduces the potential risk associated with dermal contact
with soil/sediment by minimizing exposure at the Site. This alternative poses little
risk short-term or long-term, as long as access restrictions are enforced. Mobility,
toxicity and volume are not reduced by this remedy. The present worth cost estimate
for this alternative would be approximately $ 12,000.
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TABLE 7-1: REMEDIAL GOALS
Chemicals of
Concern
Practical
Quantitation
Levels (1)
Federal or State
ARARs
Health-Based
Remedial Goal
Concentra tions(2)
Ground Water
Protection
Remedial Goals
Selected
Remediation
Goal
SURFACE SOIL tag/kg)
4,4'-DDD
4,4'-DDE
4,4'-DDT
Chlordane
Dieldrin
Molinate
Toxaphene
NA
' NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
12.6
8.9
8.9
23
0.19
NR
2.76
SUB-SURFACE
SOIL (rag/kg)
4,4'-DDT
Aldrin
alpha-BHC
beta-BHC
Dieldrin
Heptachlor
Heptachlor
Epoxide
Molinate
Vernolate
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA .
NA
NA
NA
NA
NA
NA
NA
NA
NR
NR
NR
NR
NR
NR
NR
NR
NR
NR
NR
5.8
NR
0.101
0.74
NR
5.8
0.10
0.004
0.008
0.101
0.19
0.16
0.74
328
12.6
8.9
' 8.9
23
0.19
0.74
2.76
5.8
0.10
0.004
0.008
0.101
0.19
0.16
0.74
328
SEDIMENT (mg/ke) (ECO. RISK)
4,4-DDD
4,4-DDE
4,4-DDT
Aldrin
Chlordane
Dieldrin
Endrin
GROUND
WATER
4,4'-DDT
Aldrin
alpha-BHC
Atrazine
beta-BHC
delta-BHC
Dieldrin
EPTC
Heptachlor
Heptachlor
Epoxide
Molinate
Pebulate
Vemolate
Xylene (Total)
NA
NA
NA
NA
NA
NA
NA
(ug/L)
0.1
0.05
0.05
0.25
0.1
0.05
0.1
NA
0.1
0.1
NA
NA
NA
4
NA
NA
NA
NA
NA
NA
NA
0.003
0.003
0.003
0.003
0.002
0.003
0.00002
NR
NR
. 5.8
0.10
NR
0.101
NR
0.003
0.003
0.003
0.003
0.002
0.003
0.00002
O.I4'
0.05 4)
0.05 4)
3"
0.1 4)
0.05 4)
0.1°
NA
0.4"
0.2 3)
NA
NA
NA
20 5)
074
0.007
0.017
0.471
0.059
0.059
0.007
. 940
0.024
0.011
77
1860
108
NR
NR
NR
NR
NR
NR
NR
NR
NR
NR
NR
NR
NR
NR
NR
0.24
0.05
0.05
3
0.1
0.06
0.1
940
0.4
02
77
1860
108
20
NA - Not Available
NR - Not Required
NOTES:
Practical Quantitation Levels (PQLs) are an estimate of the lowest concentration usually quantifiable by most analytical
laboratories. The source of information was the FDEP Groundwater Guidance Concentrations, June 1994.
Health based concentrations are based on 1x10* carcinogenic risk or a HQ of 1 for non-carcinogens.
Value based on a Federal and State Primary Maximum Contaminant Level (MCL).
Value based on Florida Groundwater Guidance Concentrations (To Be Considered (TBCs).
Value based on a State Secondary Maximum Contaminant Level (MCL).
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7.2.3 Alternative No. 3S - Native Soil Barrier
Alternative 3S consists of implementing the following remedial actions:
Physical and legal controls as described in Alternative 2S;
. Installation of a 2-foot thick pervious soil cap over surface soil above
remediation goals;
Removal of contaminated sediment and placement of sediment in area to be
capped; and
Placement on 1-foot thick layer of dean fill in small and large onsite ponds to
reduce ecological risk.
This alternative involves installation of a pervious soil cap (2-feet minimum
thickness) over approximately 13.4 acres of the Site. Contaminated sediment from
the small ponds would be mechanically dredged and placed into drying beds. Dried
sediment would be placed in the area to be capped. Excess water from the drying
beds would be treated with activated carbon, as necessary, and discharged back into
the ponds. Storm water would be collected and retained outside the capped area.
Land Use restrictions described in Alternative 2S would also be implemented. The
estimated present worth cost of this remedy is $1,720,000, including $1,430,000 in
capital expenditures and $290,000 for Operation and Maintenance over thirty years.
7.2.4 Alternative No. 4S - In Situ Anaerobic Treatment of Surfidal Soil/Sediment
Alternative 4S consists of implementing the following remedial actions:
Remove and dewater contaminated sediments onsite above sediment RGs or to
a depth on one foot;
Anaerobically biodegrade contaminants in surface soils and sediments in situ;
Place legal controls on Site as described in Alternative 2S; and
Place on 1 foot of clean fill in onsite ponds to reduce ecological risk.
This alternative involves in situ (i.e., in place) treatment of both surficial
soil/sediment using anaerobic biodegradation. Contaminated sediment from onsite
ponds would be mechanically dredged and placed into drying beds. Dried sediment
would be treated along with soil. Excess water from the drying beds would be
treated with activated carbon and discharged back into the ponds.
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Implementation of this alternative involves injection of chemicals and nutrients. In
situ treatment cells would be created using high density polyethylene (HOPE) liners
placed over the surface of and vertical barriers around the perimeter of each area
where surficial soil/ sediment contamination exists. Land Use restrictions described
in Alternative 2S would also be implemented. The estimated present worth cost of
this remedy is $3,630,000, including $2,180,000 in capital expenditures and $1,450,000
for Operation and Maintenance over four years.
7.2.5 Alternative No. 5S - Ex Situ Thermal Treatment of Surficial Sou/Sediment
Alternative 5S consists of implementing the following remedial actions:
Excavation of contaminated surface soils (0-2 feet) above RGs;
Remove and dewater contaminated sediments onsite above sediment RGs or to
a depth on one foot;
Thermally treat contaminated surface soils and sediments ex situ;
Place legal controls on Site as described in Alternative 2S; and
Place 1 foot of dean fill in onsite ponds to reduce ecological risk.
This alternative involves excavation, consolidation, and treatment of surficial soil and
sediment ex situ (i.e., out of place). Contaminated sediment from both ponds would
be mechanically dredged and placed into drying beds. Dried sediment would be
treated along with soil. Excess water from the drying beds would be treated with
activated carbon and discharged back into the, ponds. The thermal desorption system
used to treat the surficial soil/sediment at the Site would be similar to the low-
temperature thermal desorption unit previously used to treat soils excavated during
the 1992 Removal Action at the Site. Land Use restrictions described in Alternative 2S
would also be implemented. The estimated present worth cost of this remedy is
$7,440,000, which is a capital expenditure only.
7.2.6 Alternative 6S: Ex Situ Anaerobic Treatment of Surficial Soil/ Sediment
Alternative 6S consists of implementing the following remedial actions:
Excavation of contaminated surface soils (0-2 feet) above RGs;
Remove and dewater contaminated sediments onsite above sediment RGs or to
a depth on one foot;
Biologically treat contaminated surface soils and sediments ex situ;
Place legal controls on Site as described in Alternative 2S; and
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Place 1 foot of clean fill in onsite ponds to reduce ecological risk.
This alternative involves excavation, consolidation, and ex situ bioremediation of soil
and sediment using compost piles. Contaminated sediment from both ponds would
be mechanically dredged and placed into drying beds. Dried sediment would be
treated along with soil. Excess water from the drying beds would be treated with
activated carbon and discharged back into the ponds.
Bioremediation would be accomplished by constructing treatment cells to inhibit the
entrance of oxygen. A leachate collection system and a gas collection system would
be installed in each cell. The leachate and gas would be treated as necessary before
discharge. Land Use restrictions described in Alternative 2S would also be
implemented. The estimated present worth cost of this remedy is $4,130,000,
including $3,600,000 in capital expenditures and $ 530,000 for Operation and
Maintenance over two years.
7.2.7 Alternative 7S: Disposal of Surficial Soil/Sediment at an Offsite RCRA TSD
Facility.
Alternative 7S consists of implementing the following remedial actions:
Excavate contaminated surface soils (0-2 feet) above surface soil RGs;
Remove and dewater contaminated sediments onsite above sediment RGs or to
a depth on one foot;
Ship excavated soils and sediments to offsite RCRA facility;
Place legal controls on Site as described in Alternative 2S; and
Place 1 foot of dean fill in onsite ponds to reduce ecological risk.
This alternative involves the excavation and disposal of pesticide-laden surfirial
soil/sediment at an offsite RCRA treatment, storage, and disposal (TSD) facility for
subsequent treatment and disposal. The excavated areas would be backfilled and
compacted with dean soil from an offsite source.
Since land ban restrictions would apply to the contaminated soil, pretreatment by the
facility would be required prior to disposal. Pretreatment would likely involve
stabilization or incineration. Land Use restrictions described in Alternative 2S would
also be implemented. The estimated present worth cost of this remedy is $18,270,000,
which represents capital expenditures only.
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7.2.8 Alternative 8S: Ex Situ Anaerobic Treatment of Deep Soil/Sediment
Alternative 8S consists of implementing the following remedial actions:
Excavate contaminated surface soils (0-2 feet) and subsurface soils (>2 feet)
above RGs;
Remove and dewater contaminated sediments onsite above sediment RGs or to
a depth of one foot;
Biologically treat contaminated surface and subsurface soils and sediments ex
situ;
Place legal controls on Site as described in Alternative 2S; and
Place 1 foot of clean fill in onsite ponds to reduce ecological risk.
This alternative involves the excavation to 10 feet below land surface, consolidation
and bioremediation of deep soil (surface and subsurface soil) and sediment.
Contaminated sediment from both ponds would be mechanically dredged and placed
into drying beds. Dried sediment would be treated along with soil. Excess water
from the drying beds would be treated with activated carbon and discharged back
into the ponds.
Bioremediation would be accomplished by constructing treatment cells to inhibit the
entrance of oxygen. A leachate collection system and a gas collection system would
be installed in each cell. The leachate and gas would be treated as necessary before
discharge. Land Use restrictions described in Alternative 2S would also be
implemented. The estimated present worth cost of this remedy is $24,050,000,
including $19,200,000 in capital expenditures and $ 4,850,000 for Operation and
Maintenance over two years.
7.3 Ground Water Remedial Alternatives
The FS report included an evaluation of numerous cleanup methods for ground
water contamination at the Site. As required by CERCLA,.a no further action
alternative was evaluated to serve as a basis for comparison with the other active
cleanup methods. The cleanup methods to address site-related contamination are
presented below. A total of four (4) ground water remediation alternatives have been
considered. These alternatives represent the range of remedial actions considered
appropriate for the Site.
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7.3.1 Alternative No. 1GW: No Action
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 mis alternative, EPA would take no action to remedy any
contaminated ground water at the Site. The potential risks posed by the presence of
contamination in ground water will not be minimized by this action.
7.3.2 Alternative 2GW: Institutional Actions
This alternative involves several physical and legal controls to restrict human
behavior and reduce risks to human health and the environment through the filing of
deed restrictions to limit use of the Site and the placement of supply wells on the
Site. The existing fence would continue to limit access to the Site. Annual
monitoring of ground water would be used to monitor natural attenuation of
contaminant concentrations. It is expected that natural attenuation of current
contamination could occur in 44 years due to biodegradation only. The ability of this
remedy to meet remediation goals depends on how well the soils and sediments at
the Site are remediated. Additionally, adsorption of contaminants to soil and/or
dilution of contaminants should contribute to attenuation of contamination in ground
water. The present worth cost is for annual ground water monitoring only and totals
$ 97,000.
7.3.3 Alternative 3GW: Recovery and Treatment by Activated Carbon Adsorption
with Discharge to Onsite Ponds or the Tampa Bypass Canal
Alternative 3GW consists of implementing the following remedial actions:
Extract contaminated ground water;
Treat contaminated ground water to meet surface water discharge standards;
Discharge treated ground water to onsite ponds or to the Tampa Bypass Canal
under an NPDES permit; and
Place legal controls on Site as described in Alternative 2S until RGs are met.
This alternative involves ground water recovery and treatment. Ground water would
be recovered using an interceptor trench approximately 15 feet deep along the eastern
property boundary line and a series of extraction wells on the Site. Ground water
would be extracted at an approximate rate of 20 gallons per minute (gpm) from the
trench with a total extraction rate less than 200 gpm. Ground water collected would
be pretreated to remove iron and suspended solids by greensand filtration prior to
treatment with activated carbon, anaerobic biodegradation, or ultraviolet light
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enhanced chemical oxidation. The processes used would be further evaluated during
remedial design; carbon adsorption was assumed for cost purposes.
Treated effluent would be pumped to onsite ponds or the Tampa Bypass Canal for
discharge. A National Pollution Discharge Elimination System (NPDES) permit is
required to discharge treated ground water to offsite surface water. Discharge
requirements for the contaminants of concern are provided in Table 7-2. The
estimated present worth cost of this remedy is $3,540,000, including $1,640,000 in
capital expenditures and $ 1,900,000 for Operation and Maintenance over thirty years.
7.3.4 Alternative 4GW: In Situ Anaerobic Treatment of Ground Water
. This alternative involves in situ treatment of ground water using anaerobic
biodegradation. Implementation of this alternative involves
Create in situ treatment cells using HDPE liner placed over the surface of and
vertical barriers around the perimeter of the area where ground water
contamination exists;
Inject easily oxidized substrate chemicals (e.g., benzoate), sulfate to replace
oxygen electron receptors, and other nutrients;
Monitor ground water extensively; and
Place legal controls on Site as described in Alternative 2S until RGs are met.
A treatabiliry study would be required prior to design of the treatment process.
Extensive ground water monitoring would be required to maximize the use of
additives and verify cleanup of pesticides. The estimated present worth cost of this
remedy is $2,790,000, including $1,700,000 in capital expenditures and $ 1,090,000 for
Operation and Maintenance over five years.
8.0 SUMMARY OF THE COMPARATIVE ANALYSIS OF ALTERNATIVES
8.1 Statutory Balancing 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 SMC Site. A wide variety of alternatives and technologies
were identified as candidates to remediate the contamination at the SMC 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 alternatives and
evaluated in detail. One soil/sediment remedial alternative and one ground water
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TABLE 7-2: SURFACE WATER DISCHARGE REQUIREMENTS
Ecological Chemical
Of Concern
Aluminum
Cadmium
Iron
Lead
Manganese
Zinc
Xylene (Total)
4,4'-DDD
Aldrin
alpha-BHC
Atrazine
beta-BHC
Butylate
Cycloate
Dieldrin
Endosulfan n
EPTC
HeptacWor
Heptachlor Epoxide
Molinate
Pebulate
Vernolate
Range of Detects in
Shallow Ground
Water (ug/L)
415-6,420
16
18,000-18,200
8
227-392
70-169.
34-740
0.3
0.07-0.2
- 0.1-9
3
6
0.8-130
2-590
0.06-0.1
02
7-9,400
0.1
0.6
1-7,700
0.6-18,000
4-130
Surface Water Discharge Standards 1)
Annual Average
(ug/L)
87
0.66
13
59
TBD
0.00014
TBD
0.046
TBD
TBD
0.00014
TBD
0.00021
0.00021
TBD
TBD
TBD
Maximum
(ug/L)
750
1.79
1000
33.78
65
TBD
3
TBD
TBD
TBD
0.0019
0.056
TBD
0.0038
0.0038
TBD
TBD
TBD
Notes: 1. Inorganics Based on Region IV Freshwater Quality Criteria and
Pesticides Based on Florida Administrative Code (FAQ Chapter
17 Part 302.530.
TBD No Data Available. Discharge Criteria To Be Determined During
Remedial Design.
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remedial alternative were selected from the screening process using the following
nine evaluation criteria:
overall protection of human health and the environment;
compliance with applicable or 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, workers, or the environment during the course of implementation;
implementability, that is, the administrative or technical capacity to carry out -
the alternative;
cost-effectiveness 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;
(2) 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
(3) Modifying Criteria - state and community acceptance are modifying criteria
that are formally taken into account after public comments are received on the
proposed plan and incorporated into the ROD.
The following analysis is a summary of the evaluation of alternatives for remediating
the SMC Site under each of the criteria. A comparison is made between each of the
alternatives for achievement of a specific criterion.
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8.2 Threshold Criteria
8.2.1 Overall Protection of Human Health and the Environment
With the exception of the No Action alternatives (Alternatives IS and 1GW), all of the
alternatives would provide protection for human health and the environment to some
degree. Alternatives 2S and 2GW would limit access and exposure to contaminants
but would not control migration of contaminants to ground water and outside the
Site boundaries. Alternatives 3S through 7S and 3GW through 4GW would limit
access and exposure, eliminate further migration, and reduce risk by removing
contamination from soil/sediment and ground water. Alternative 8S would be most
protective because it would remediate soils/sediment to protect ground water. Since
Alternatives Is and 1GW did not pass this threshold criteria for providing protection
of human health and the environment, they will be eliminated from further
consideration.
8.2.2 Compliance With ARARs
The remedial action for the SMC Site, under Section 121 (d) of CERCLA, must comply
with federal and state environmental laws 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 potential location-specific ARARs and TBCs for the SMC
Site.
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
requirements can be ARARs. Table 8-2 lists potential action-specific ARARs and
TBCs for the SMC Site.
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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 Clean Water Act. Because there are
usually numerous contaminants of potential concern for any remedial site, various
numerical quantity requirements can be ARARs. Table 8-3 lists potential chemical-
specific ARARs and TBCs for the SMC Site.
Alternatives 2S through 8S would meet or exceed all chemical-specific ARARs and
would be designed to meet location- and action-specific ARARs. Alternatives 2GW
through 4GW may meet all ARARs.
8.3 Primary .Balancing Criteria
8.3.1 Long-Term Effectiveness and Permanence
Alternatives 4S, 5S, 6S, 85, 3GW, and 4GW are effective and permanent, but some
would require a long time period to remove all contamination. Alternative 3S and
2GW do not actively remove contamination, but biodegradation and attenuation
would reduce contamination over time and the reduction would be permanent.
8.3.2 Reduction of Toxicity, Mobility, or Volume Through Treatment
Alternative 3S would aid in the reduction of mobility, but toxitity and volume of
contaminated soils/sediments would not be reduced for a long period of time
(natural biodegradation and flushing). Alternatives 4S through 7S would be effective
at completely reducing toxitity, mobility, and volume of contaminants in surface
soil/sediment. Alternative 8S would be effective at completely reducing toxicity,
mobility, and volume of contaminants in surface and sub-surface soil/sediment and
ground water.
Sorption of contaminants to soil particles would aid in the reduction of mobility of
contaminated ground water for Alternative 2GW, but toxicity and volume would not
be reduced for a long period of time (natural biodegradation). Alternatives 3GW and
4GW would actively reduce toxicity, mobility, and volume of contaminated ground
water at the Site. The success of the ground water remedy depends in large part on
the success of the source control conducted at the Site.
8.3.3 Short-Term Effectiveness
Equipment and personnel decontamination facilities would be necessary for all
alternatives, except Alternative 2S. Handling of chemicals to sustain anaerobic
conditions would be conducted under strict health and safety protocol for
Alternatives 4S, 6S, 8S and 4GW. Air monitoring would be necessary during
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TABLE 8-1: POTENTIAL LOCATION SPECIFIC ARARS AND TBCs
Stktvfctd te
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TABLE 8-2: POTENTIAL ACTION SPECIFIC ARARS AND TBCs
%S " X * Sv-
^Y* , SUhdird JtequlreniĞnt CrlttrU
Resource Conservation and Recover Aet (RCRAI.
as amended
RCRA Land Disposal Restrictions
RCRA Waste Management Program
Clam Air Aet
National Primary and Secondary
Ambient Air Quality Standards
National Emissions Standards for
Hazardous Air Pollutants
(NESHAPs)
Occupational Safely and Health Administration
Citation
42 USC 6901, 6905, 6912, 6924,
6925
40 CFR Part 268
40 CFR 2 Part 64
40 CFR Part 50
40 CFR Part 61
29 CFR 1910 Part 120
Description
Provides for proper disposal of regulated
contaminants found In soils.
Requires owner/operator to control wind
dispersal of participate matter and provides
technical criteria of hazardous waste material
and treatment, storage, and disposal (TSD).
Sets primary and secondary air standards at
levels to protect public health and public
welfare.
Provides emissions standard for hazardous air
pollutants for which no ambient air quality
standard exists.
Provides safety rules for handling specific
chemicals for site workers during remedial
activities.
Comment
Potentially applicable to the SMC Site.
The control of fugitive dust emissions Is
potentially relevant to this site.
May be relevant or appropriate If onsfte
treatment units are part of remedial actions.
May be relevant or appropriate If groundwater
recovery and/or onslte treatment units are part
of remedial actions.
Health and safety requirements are applicable to
all potential remedial actions.
to
ET
1
n
o
li?
II.
Ğ o
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TABLE 8-3: POTENTIAL CHEMICAL SPECIFIC ARARS AND TBCs
SUndatd Requirement, Criteria,
otLlmluHon - ..
fafe Drinking Water Ael
National Primary Drinking Water
Standards
Maximum Contaminant Level Coats
Clean Water Act
Ambient Water Quality Criteria
Resource Conservation and Recaoerv Ael (RCRA),
RCRA Groundwater ProtecHon
STATE
EPI-P Printing Water Standards.
Monitoring and Reoortlnt
Florida Surface Water Quality Standards
FPEP Water Quality Standards
MO A A Suggested Guidance tot Evaluation of
Sediment Contamination Data
CiUriort
40 USC SecHon 300
40 CFR Part 141
Publication L. W 99-399,100
Stat. 642 (1986)
33 USC SecHon 1251-1376
40 CFR Part 131
42 USC 6901, 6905, 6912, 6924,
6925
40 CFR Part 264
PA.C. Chapter 17-550
FA.C. Chapter 17-302
F.A.C. Chapter 17-3
To Be Considered (TBC)
Description
Establishes health-based standards for public
water systems (maximum contaminant levels).
Establishes drinking water quality goals set at
levels of no known or anticipated adverse health
effects.
Sets criteria for water quality based on toxlclty
to aquatic organisms and human health.
Provides for groundwater protection standards,
general monitoring requirements, and technical
requirements.
Regulates water systems within the state that
supply drinking water that may affect the public
health.
Establishes surface water quality standards
within the state.
Establishes groundwater classification and water
quality standards. Applicable to groundwater at
the site.
Evaluates sediment values based on In stream
studies.
Comment
The MCLs for organic and Inorganic
contaminants are potentially applicable to the
groundwater contaminated by the site since It Is
a potential drinking water source.
Proposed MCLCs for organic and Inorganic
contaminants are potentially applicable to the
groundwater used for drinking water.
The AWQC for organic and Inorganic con-
taminants are potentially relevant and
appropriate.
The RCRA MCLs are relevant and appropriate
for groundwater at the site.
Provides the state with the authority needed to
assume primary enforcement responsibility under
the federal act. Potentially applicable to
groundwater at the site.
These standards are established for the protection
of aquatic organisms and human health.
Potentially applicable for site surface water.
Guidelines for allowable levels of toxic organic
and Inorganic compounds In groundwater used
for drinking water. Applicable to groundwater
at the site.
Mot a standard, but used as TBC values related
to sediment contamination and potential
ecological Impacts. Potentially applicable to site
sediments.
s,iЧ-
to m a
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construction of Alternatives 3S through 8S and 3GW and during operation of
alternative 4S, 5S, 6S, 8S and 4GW to ensure that workers and the public are
protected from air emissions. The heavy construction equipment may also create
some noise nuisance.
During the implementation of all the alternatives, both onsite workers and people
surrounding the site will be protected from possible impacts caused by construction
or O&M activities.
8.3.4 Implementability
The implementability of an alternative is based on technical feasibility, administrative
feasibility and the availability of services and materials. Alternative 2S involves only
access restrictions, which are easily implemented. Alternative 3S is relatively easy to
implement since most of the contaminated soil remains in place and capping the
material requires very little design effort. Alternative 4S would be difficult to
implement, since it requires creating anaerobic conditions in situ while controlling
leachate and offgas emissions. Alternative 5S has been used at the Site in previous
work and would be moderately easy to implement, since required controls are
known. Alternative 6S would be moderately easy to implement, since anaerobic
conditions and leachate and offgas collection would be easier to control than in
Alternative 4S and pilot tests are already underway. Alternative 7S would be easy to
implement because it primarily involves excavation and shipping materials.
Alternative 8S would be more difficult to implement since large scale excavation
might be required.
Alternative 2GW could be implemented immediately since there are no engineering
considerations involved. Alternative 2GW involves monitoring ground water
annually. Alternative 3GW would require approximately 14 months to implement
and annual monitoring for 30 years. Alternative 4GW would take longer than 14
months to implement because pilot studies would be required to design the system
and more engineering controls would be required to create anaerobic conditions in
ground water while controlling offgases, but annual monitoring would not be
required when complete.
8.3.5 Cost
A summary of the present worth costs which includes the capital as well as the
operation and maintenance cost for each of the alternatives is presented in Table 8-4.
These costs were presented in the FS and are based on less stringent Remedial Action
Performance Standards than presented in Section 7-1. However, the present worth
costs to dean up to the recommended performance standards are within the range
the FS cost estimates are considered accurate (+50% to -30% accuracy), and the
relative cost of each alternative should be similar to that presented in the FS.
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TABL1
Alternative
SOIL/SEDIMENT
IS. No-Action
25. Institutional Actions
3S. Native Soil Barrier
45. In Situ Anaerobic Treatment of
Surfirial Soil /Sediment
5S. Ex Situ Thermal Treatment of
Surficial Soil/Sediment
6S. Ex Situ Anaerobic Treatment of
Surficial Soil /Sediment
75. Disposal of Surficial
Soil/Sediment at Offsite RCRA
TSD Facility
85. Ex Situ Anaerobic Treatment of
Deep Soil/Sediment
GROUND WATER
1GW. No Action
2GW. Institutional Actions
3GW. Recovery and Treatment by
Activated Carbon Adsorption
with Discharge to Onsite
Ponds or the Tampa Bypass
Canal
4GW. In Situ Anaerobic Treatment of
Ground Water
E 8-4: COMPARISON OF COSTS
Present-worth Cost
$0
$12,000
S 1,720,000
$ 3,630,000
S 7,440,000
$ 4,130,000
$ 18,270,000
$ 24,050,000
SO
$ 97,000
$ 3,540,000
S 2,790,000
Capital Cost
SO
$0
S 1,430,000
$ 2,180,000
$ 7,440,000
$ 3,600,000
$ 18,270,000
$ 19,200,000
$0
$0
$ 1,640,000
$ 1,700,000
Operation and
Maintenance Cost
$.0
$ 12,000
$290,000
$1,450,000
SO
$530,000
$0
4,850,000
$0
$97,000
S 1,900,000
$ 1,090,000
Alternatives 2S and 2GW are the least costly alternatives, other than the No Action
alternatives. Of the treatment alternatives, Alternatives 6S and 3GW are less
expensive than Alternative 8S, which affords the same level of protection. A
summary of the present worth costs which includes the capital as well as the
operation and maintenance cost for each of the alternatives is presented in Table 8-4.
8.4 Modifying 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 SMC 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 EPA on all major documents in the
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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.
8.4.2 Community Acceptance
Based on comments expressed at the July 27,1995, public meeting and receipt of 6
written comments during the comment period, it appears that the community does
not disagree with the selected remedy. Specific responses to issues raised by the
community can be found in Appendix A, The Responsiveness Summary.
9.0 SUMMARY OF SELECTED 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, EPA has selected Alternatives 6S (Ex Situ
Anaerobic Treatment of Surficial Soil/Sediment) and 3GW ([Ground Water] Recovery
and Treatment by Activated Carbon Adsorption with Discharge to Onsite Ponds or to
the Tampa Bypass Canal) for this Site. If, after pilot tests are complete, Alternative 6S
cannot economically meet the remedial goals for soil/sediment at this Site, a
contingency soil/sediment remedy, Alternative 5S (Ex Situ Thermal Treatment of
Surficial Soil/Sediment), will be implemented instead. The selected alternatives for
the Stauffer Site are consistent with the requirements of Section 121 of CERCLA and
the NCP. Based on the information available at this time, the selected alternatives
represent the best balance among the criteria used to evaluate remedies. The selected
alternatives will reduce the mobility, toxicity, and volume of contaminated ground
water at the Site. In addition, the selected alternatives are protective of human health
and the environment, will attain all federal and state ARARs, are cost-effective and
utilize permanent solutions to the maximum extent practicable. The estimated
present worth cost of Alternatives 6S and 3GW are $ 4,130,000 and $ 3,540,000,
respectively. The estimated present worth cost of the contingency soil/sediment
remedy, Alternatives 5S, is $ 7,440,000.
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.
9.1 Source Control
9.1.1 Major Components of Source Control
Since subsurface soil contamination is not addressed in Alternative 6S, sediment
removal to a depth of one foot and placement of one foot of dean fill in the onsite
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ponds is likely to be more cost effective than remediation to sediment RGs.
Performance standards for the selected remedy will reflect 1 foot of sediment removal
rather than RGs in Table 7-1.
The major components of source control in the selected remedy (Alternative 6S) to be
implemented include:
Excavation of contaminated surface soils (0-2 feet) above RGs;
Removal and dewatering of a 1-foot thick layer of contaminated sediments
from onsite ponds;
Biological treatment of contaminated surface soils and sediments ex. situ to soil
RGs;
Placement of controls on the Site to restrict excavation and gardening through
the filing of deed notices and the use of existing fence to limit exposure to
contaminated areas until RGs are met; and
Placement of 1 foot of dean fill in onsite ponds to eliminate exposure pathway.
9.1.2 Performance Standards
The performance standards for surface soil remediation are based on protection of
ground water and/or protection of human health, and are listed in Table 7-1. This
remedy does not require sub-surface remediation of contaminated soils to levels
listed in Table 7-1. Since subsurface soil contamination is not addressed, sediment
removal to a depth of one foot and placement of one foot of clean fill in the onsite
ponds is likely to be more cost effective than remediation of sediments to RGs.
Performance standards for the selected remedy will reflect 1 foot of sediment removal
rather than RGs in Table 7-1.
9.2 Ground Water Remediation
9.2.1 Major Components of Ground Water Remediation
The major components of the ground water remediation portion the selected remedy
(Alternative 3GW) are as follows:
Extract contaminated ground water;
Treat contaminated ground water to meet surface water discharge standards;
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Discharge treated ground water to onsite ponds or to the Tampa Bypass Canal
under an NPDES permit; and
Place controls on Site to restrict use of ground water beneath the Site through
the filing of deed notices in order to limit exposure to contaminated ground
water until RGs are met
9.2.2 Performance Standards
9.2.2.1 Extraction Standards
Ground water will be extracted from the surficial aquifer at a rate of to be
determined during remedial design.
9.2.2.2 Treatment Standards
Ground water will be monitored in the Floridan and surficial aquifer until the
maximum concentration levels for ground water in Table 7-1 are attained.
9.2.2.3 Discharge Standards
Discharges from the ground wafer treatment system shall comply with all ARARs,
including, but not limited to, substantive requirements of the NPDES permitting
program under the Clean Water Act, 33 U.S.C. § 1251 et seq., and all effluent limits
established by EPA in Table 7-2.
9.2.2.4 Design Standards
The design, construction and operation of the ground water treatment system shall be
conducted in accordance with all ARARs, including the RCRA requirements set forth
in 40 C.F.R. Part 264 (Subpart F).
9.3 Compliance Testing
Ground water and surface water monitoring shall be conducted at this Site. Ground
water shall be sampled from existing and new monitoring wells, as determined
during remedial design. After demonstration of compliance with Performance
Standards, the Site shall be monitored for five years. If monitoring indicates that the
Performance Standards set forth in Paragraph B.3 are being exceeded at any time
after pumping has been discontinued, extraction and treatment of the ground water
will recommence until the Performance Standards are once again achieved. If
monitoring of the surface water indicates contaminant levels are not decreasing, the
effectiveness of the source control component will be re-evaluated.
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9.4 Contingency Remedy for Soil/Sediment
Should pilot studies demonstrate that the selected remedy described above (biological
treatment), cannot achieve performance standards established for the Site, in an
economical manner, then the treatment technology used for soil/sediment
remediation at the Site will be low temperature thermal desorption (LTTD) instead of
biological treatment. LTTD has been successfully used in the past at this Site to treat
pesticide contaminated soils. The performance standards described in Section 92.1
apply .to LTTD as well as biological treatment.
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 reduces 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 soil/sediment and ground water treatment as delineated
through the performance standards described in Section 9.0 - SUMMARY OF
SELECTED REMEDY. The residual risk due to individual contaminants will be
reduced to a probability of IxlO"6 for carcinogens and HQ of 1 for non-carcinogens.
The residual carcinogenic risk at the Site, which is the sum of individual carcinogenic
risks, will be reduced to acceptable levels (i.e., cancer risk between IxlO"6 and IxlO"4)
once performance standards are achieved. 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. § 9621, 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 requirements. The selected remedy was found to
meet ARARs identified in Tables 8-1, 8-2, and 8-3. The following is a short narrative
explaining the attainment of pertinent ARARs.
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Chemical-Specific ARARs
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 CFR 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.
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.
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, EPA has
concluded that the selected remedy, Alternatives 6S and 3GW, affords the highest
level of overall effectiveness proportional to its cost. Section 300.430(f)(l)(ii)(D) of the
NCP also requires EPA 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 selected remedy has a relatively high present worth, capital, and operation and
maintenance cost compared to other remedies, but best satisfies the criteria for long-
term effectiveness and permanence and short-term effectiveness. This alternative will
reduce toxicity, mobility, or volume through treatment.
The estimated present worth costs for the soil/sediment and ground water selected
remedies are $ 4,130,000 and $ 3,540,000, respectively.
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10.4 Utilization of Permanent Solutions to the Maximum Extent Practicable
EPA has 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 SMC Site. Of those alternatives that
are protective of human health and the environment and comply with ARARs, EPA
has determined that Alternative 6S, combined with Alternative 3GW, 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.
10.5 Preference for Treatment as a Principal Element
The statutory preference for treatment is satisfied by the selected remedy.
11.0 DOCUMENTATION OF SIGNIFICANT CHANGES
There have been no significant changes in the selected remedy, Alternatives 6S and
3GW, from the preferred remedy described in the proposed plan. The remedial
goals listed in Table 7-1 of the ROD are slightly different than the goals listed in
Table 1 in the proposed plan due to errors noted and corrected in response to
comments in Appendix A. Sub-surface soil RGs for atrazine, delta-BHC, EPTC, and
Pebulate were dropped because detected onsite concentrations are lower than
concentrations required for ground water protection or ground water detections are
lower than ground water RGs. The sub-surface soil RG for dieldrin was changed
from 0.007 mg/kg to 0.01 mg/kg because the Practical Quantitation Level (PQL) for
dieldrin is 0.01 mg/kg. A ground water RG for xylenes (total) of 20 ug/L was added
because xylenes enable pesticide transport in ground water; 20 ug/L is a Florida
secondary MCL. Sediment RGs for protection of human health were eliminated
because the pathway (i.e., ingestion of sediment) did not exceed 1 x 10"4 carcinogenic
risk or HQ greater man 1. Sediment RGs for the protection of plant and animal life
were added to reduce the ecological risk; however, based on the remedy selected,
removal on one foot of contaminated sediment in ponds and replacement with one
foot of clean fill was selected to eliminate the sediment exposure pathway.
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APPENDIX A - RESPONSIVENESS SUMMARY
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RESPONSIVENESS SUMMARY
STAUFFER MANAGEMENT COMPANY SUPERFUND SITE
TAMPA, HILLSBOROUGH COUNTY, FLORIDA
Introduction
This responsiveness summary for the Stauffer Management Company Superfund Site
documents for the public record concerns and issues raised during the comment
period on the proposed plan. EPA's responses to these concerns and issues are
included.
Overview of Comment Period
The proposed plan for the Stauffer Management Company Superfund Site was issued
on July 18, 1995. A sixty-day public comment period for the proposed plan began
July 20,1995, and ended September 17,1995. Two written comments with multiple
concerns were received during that comment period. A public meeting was held on
July 27,1995, at the Kenley Park Recreation Center at 1301 North 66th Street, Tampa,
Florida. Many comments were received and addressed during that meeting. A
transcript of the meeting was prepared and is available at the information repository
near the Site.
Concerns Raised During the Comment Period
Private Well User Concerns:
1. One commentor asked if EPA plans to test private wells near the Site. The
commentor asked when EPA was going to take some action to help
"everybody", in particular the private well users in the area of the Site. The
commentor noted the large number of hazardous sites located in the area.
Response: A well survey was conducted as part of the RI/FS for the Helena
Chemical Company Site, located across the street from SMC, and was cross-
referenced in the SMC Site Administrative Record. The results of the well
survey indicate that only monitoring wells are open to the surficial aquifer;
drinking water wells around the Site are open to the Floridan Aquifer.
Ground water contamination at the Site is primarily located in the surficial
aquifer. Minor amounts of contamination have been detected in the Floridan
Aquifer beneath the Site.
Private wells were not sampled during the RI/FS; contaminated ground water
in the surficial aquifer, from the SMC Site, discharges to the Tampa Bypass
Canal and does not extend to any private wells. If the contamination migrates
to an area where private wells exist, EPA will require that the private wells be
monitored to ensure that human health is protected.
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Stauffer Management Company Site
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EPA does not have the authority or funds to address all local ground water
issues. Local water quality is generally considered to be under the jurisdiction
of local government. If contamination from a Superfund Site affects the water
quality in a private well, EPA can require that the responsible parties provide
an alternate drinking water source to the well users. However, EPA's
Superfund program cannot provide public water supplies to well users just
because of the number of hazardous waste sites in the area.
EPA recommends that the commentor work with the county and state health
departments to determine if privates wells might be affected by sites
upgradient from the wells. The health department may also agree to test a
' well and determine if alternate water sources are available.
Concerns Related to Past Exposures:
2. One commentor questioned why EPA is proposing to remediate the Site now
when residents have already moved out and the area is industrial. The
commentor wanted to know what was going to be done to help former
residents and address their past exposure.
Response: EPA is proposing to remediate the Site in order to protect current
and future onsite workers and to protect the waters in the Tampa Bypass
Canal and Horidan aquifer from contaminated ground water. EPA wants to
prevent current and future exposure at the Site. The Agency for Toxic
Substances and Disease Registry (ATSDR) and the State of Florida Department
of Health and Rehabilitative Services (HRS) should be contacted to address
past exposure issues. ATSDR and HRS can perform surveys and studies to
track public health concerns and determine if they can be linked to discharges
from a particular facility.
Concerns about the Remedial Investigation/Feasibility Study:
3. Camp Dresser & McKee Inc. (COM) requested that in the future EPA remove
the CDM logo from document pages modified by EPA or include a written
disclaimer on modified document pages.
Response: EPA modified pages by striking through incorrect information and
writing in more appropriate information. The EPA modifications were
necessary because the document was submitted several weeks late and the
schedule for completion of the ROD prohibited EPA from offering CDM a
third opportunity to make corrections. The modified pages were attached to a
memorandum which clearly indicated that the changes were being made by
EPA. If EPA needs to revise information on future documents, the CDM logo
will be removed.
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Responsiveness Summary
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PageS
4. One commentor suggested that the RI/FS did not consider past drainage paths
or investigate fully those paths. The commentor suggested that EPA
investigate further downstream in McKay Bay since most of the contamination
in adjacent drainage ways may have been removed when the Tampa Bypass
Canal was constructed. The commentor suggested that more sources are likely
present than those identified in the RI/FS.
Response: EPA's investigations typically begin onsite and are extended offsite
if data indicates that contamination has migrated offsite. Since the Tampa
Bypass Canal was constructed in the early 1970s, contamination that may have
migrated to the old Six Mile Creek was probably removed or covered with fill.
Since numerous facilities discharge water to McKay Bay, there is no direct
pathway to link contamination at the Site to contamination in McKay Bay. An
investigation and clean up of McKay Bay may be pursued by another agency
in a separate action, but it will not be investigated further as part of the SMC
Site.
A review of the RI/FS will reveal that EPA and SMC have attempted to
identify all possible sources of contamination at the Site. Since ground water
remediation is dependent on source removal to be effective, it should be
evident during the course of cleanup if additional sources are present. If
additional sources of ground water contamination are discovered during the
course of remediation, the sources will be removed and treated.
5. One commentor asked EPA to explain bioremediation.
Response: Bioremediation is a method of treating contaminated material by
means biological processes. Biological treatment of hazardous organic
substances (bioremediation) is based on the use of either aerobic or anaerobic
bacteria. Aerobic biodegradation is accomplished in the presence of oxygen
and is particularly effective on aromatic hydrocarbons (VOCs and petroleum-
based compounds). Anaerobic biodegradation is carried out in an oxygen-free
environment and has been shown to degrade chlorinated compounds such as
pesticides and herbicides. Success depends on using microorganisms well-
acclimated to the specific waste type and having sufficient nutrients available.
6. One commentor asked EPA to explain the difference between thermal
desorption and incineration.
Response: Low Temperature Thermal Desorption (LTTD) is a treatment
process in which contaminated soil/sediment is excavated and placed in a heat
exchanger (thermal processor) with temperatures much lower (<1000°F) than
those achieved by incineration (>2000°F). Air emissions from LTTD are less
costly to deal with than for incineration. LTTD leaves the soil intact and
vaporizes the pesticides, whereas incineration leaves ash ttiat must be disposed
of in accordance with regulatory requirements.
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7. One cofnmentor asked if bioremediation has been used successfully at other
Sites.
Response: No, not yet. However, bioremediation of pesticide contaminated
soil is considered an innovative technology and is currently being considered
for use at several Sites in EPA Region IV. At least two different companies are
developing the technology. Results are not yet available to demonstrate
complete success at other sites.
8. One commentor asked EPA what the difference was in the timeframe to
remediate contamination using bioremediation versus doing nothing.
Response: Bioremediation of contaminated soils is expected to take four years
at the SMC Site. The timeframe required for natural degradation/attenuation
of contaminants in soil has not been determined. Pesticide levels in soils are
expected to remain at current levels indefinitely unless remediated.
9. One commentor. asked why air sparging was not considered if oxygen levels
were important to bioremediation.
Response: It is possible that air sparging might be used .in the remediation
process if oxygen is needed to induce bioremediation. This will be determined
in remedial design. Air sparging is not adequate as a stand alone process for
remediation of pesticides.
10. One commentor asked how far south of the Helena site contamination was
located.
Response: Soil contamination was found on the CSX railroad easement south
of the Site and on the property south of CSX railroad. Ground water
contamination was determined to extend approximately 200 ft south of the Site
under several adjacent properties, including the SMC Site.
11. One commentor wanted to know the total volume of contaminated soil.
Response: Exact volumes based on the clean up levels proposed by EPA are
not available. Based on earlier cleanup level assumptions, the responsible
parties estimate that approximately 5,100 cubic yards of material would require
excavation, and approximately 6,400 cubic yards would require treatment,
assuming expansion of soils after excavation. The volumes now are expected
to be slightly higher due to the lower clean up standards proposed by EPA.
12. One commentor questioned EPA regarding elimination of COCs in an
Amendment to the FS. Page 2-2 of the Final FS (EPA mark-up page Al) states
that no remediation goals were calculated for certain chemicals of concern
(COCs). The commentor requested that language be provided giving rationale
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for elimination. In addition, the commentor stated that EPA developed
remediation goals for heptachlor in groundwater, which is not consistent with
the text on page AL
Response: The sentence that states that no remediation goals were calculated
for certain chemicals should have been crossed out. This section is supposed
to be a summary of the Baseline Risk Assessment and should reflect every
contaminant for which remediation goals were calculated because of risk. The
appropriate section to discuss the need for eliminating remediation goals is
Section 3.
13. One commentor questioned EPA regarding revisions to Table 3-6 in an
Amendment to the FS. The commentor asked why the revised Table 3-6 is not
consistent with the rest of the Final FS. The commentor stated that if only
industrial land use is considered for the site, residual risks for onsite residents
should not be shown; it would be more appropriate to only show residual
risks for the onsite worker.
Response: The consultant that prepared the FS evaluated residual risk based
on residential and industrial land use in order to provide the PRPs, EPA, and
the public with the differences in cost required to remediate to stricter levels.
The purpose of the markup pages in the amendment was to provide an
indication of where EPA considered the changes to be necessary and to give
the reader an idea of what the changes described in the July 12,1995,
Memorandum to the Administrative Record would look like in the document.
EPA agrees that it would have been preferable, had time permitted, to have
the whole document revised. Since EPA was concerned primarily about
residual risk to the industrial worker, that is what was calculated in EPA's
revisions to Table 3-6. There is enough information available in the record to
determine those the residual residential risk if needed in the future.
14. One commentor questioned EPA regarding Table 4 of Attachment B in EPA's
Amendment to the FS. The commentor stated that Table 4 should present
recommended remediation goals for subsurface soil. Also, footnote 2 is
missing and should be added, footnote 1 appears to be mislabelled and should
be corrected, and acronyms should be defined.
Response: The commentor is correct. This error has been corrected in EPA's
November 27,1995 memorandum to the Administrative Record concerning
revisions to the Final Feasibility Study Amendments (hereafter referred to as
the "November 27,1995 FS Revision Memo").
15. One commentor requested that EPA justify requiring ground water cleanup
when future land use was considered to be commercial.
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Response: Future land use at the Site is expected to remain commercial, and
EPA anticipates restricting ground water use at the Site so that no future onsite
exposure to ground water can occur. However, unless the ground water is
contained with a barrier or extraction system, there is no way to prevent the
contaminated ground water from migrating offsite. Contaminated ground
water currently discharges into the Tampa Bypass Canal. Although
contaminant levels are not detected in the Tampa Bypass Canal due to the
effects of dilution, discharge is occurring. In addition, contaminants have been
detected at unacceptable levels in the Floridan aquifer, the primary drinking
water aquifer in Tampa. Therefore, future exposure to contaminated ground
water could occur if contaminants migrate offsite and if private wells are used
on adjacent properties.
16. One commentor noted that the fact sheet states that remediation goals for the
SMC site are based on industrial use of the Site; however, the remediation
goals stated for groundwater are not based on industrial use, but are based on
tiie Federal Safe Drinking Water Act (SOWA) maximum contaminant levels
(MCLs), Florida Groundwater Standards, or residential health-based
concentrations. The commentor requested clarification.
Response: Only surface soil remediation goals are based on a future industrial
use scenario. Since contaminated ground water beneath- the Site is currently
allowed to migrate offsite and to the Floridan aquifer, Federal Safe Drinking
Water Act (SDWA) maximum contaminant levels (MCLs), Florida Ground
Water Standards, and residential health based concentrations were considered
to determine remediation goals for ground water. This information has been
clarified in the ROD.
Concerns about Remediation Goals for Sediments:
\
17. One commentor questioned EPA regarding revisions to Table 3-4 in an
Amendment to the FS. EPA's memorandum regarding the amendment to the
Final FS states (4th paragraph, p. 2) that Table 2-5 should represent
remediation goals for carcinogenic risk of 10"5 to 10"6 and hazard quotient (HQ)
of 1. However, the sediment remediation goals for residents (Table 3-4) are
based on an HQ of 0.1. This should be corrected.
Response: The sediment remediation goals for residents in the Table 3-4 on
page A-12 of EPA's amendment to the Final FS should reflect 10* carcinogenic
risk goals and goals reflecting a HQ of 1, as follows: aldrin = 8.33 mg/kg,
chlordane = 12.7 mg/kg, dieldrin = 1.5 mg/kg). This error has been corrected
in EPA's November 27, 1995 FS Revision Memo.
18. One commentor questioned EPA regarding revisions to Table 3-4 in an
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Amendment to the FS. The commentor asked why the sediment remediation
goals for the residential scenario were crossed out?
Response: The goals on Table 3-4 were crossed^ out because they were
incorrect. The goals listed in the response to comment 13 should have been
written in adjacent to the crossed out numbers. This error has been corrected
in EPA's November 27,1995 FS Revision Memo.
19. On commentor asked how or why EPA calculated sediment remediation goals
for the worker scenario. EPA's Final Revised BRA states that, "remedial goal
options were developed for all exposure pathways that have a total
. carcinogenic risk exceeding 1 x 1CT4 or a total hazard index that exceeds 1 (p. 6-
1). These risk levels were not exceeded for pathways associated with sediment
exposure by workers, and remediation goals for sediment based on the worker
scenario were therefore not calculated in the Final Revised BRA. Because there
is no excess risk from future exposure to sediment at the site, remediation of
sediment should not be required.
Response: The commentor is correct, remediation of sediment based on
worker exposure should not be required and the error has been corrected in
EPA's November 27,1995 FS Revision Memo and Section 11 (Significant
Changes) in the ROD. However, sediment contamination remains a significant-
source of risk to ecological life at this Site, though difficult to quantify. EPA
recommends that one foot of sediment be removed from the onsite ponds and
replaced with one foot of dean fill. The clean fill will eliminate one exposure
pathway to ecological life at the Site.
Concerns about Remediation Goals for Soils:
20. One commentor questioned EPA regarding revisions to Table 3-4 in an
Amendment to the FS. The commentor asked why the health-based
remediation goal for chlordane in soil for the residential scenario should be
0.495 mg/kg, not 0.33, as presented. A concentration of 0.495 mg/kg
corresponds to a 10"6 cancer risk, and 0.33 mg/kg corresponds to an HQ of 0.1.
Response: The health based remediation goal for chlordane in soil for the
residential scenario should be 0.495 mg/kg, not 0.33, as presented. This error
has been corrected in EPA's November 27, 1995 FS Revision Memo.
21. One commentor asked why the remediation goals for soils did not increase
exactly two times if EPA revised the worker soil ingestion rate from 100 to 50
mg/day.
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Response: The remediation goals for surface soils are based on assumed
worker exposure due to incidental ingestion of contaminated soils and dermal
contact with contaminated soils. The dermal contact component did not
change when the ingestion rate was lowered. Therefore, the remediation goals
did not increase by exactly two times.
Concerns about Remediation Goals for Ground Water:
22. . One commentor questioned EPA regarding revisions to Table 3-5 in an
Amendment to the FS. The commentor asked why the MCL for bis(2-
ethylhexyDphthalate (0.006 mg/1) is less than the PQL (0.010 mg/1).
Response: Since remediation below the PQL is impractical, the PQL should
have been selected as the remediation goal for bis(2-ethylhexyl)phthalate in
groundwater. This error has been corrected in EPA's November 27,1995 FS
Revision Memo.
23. One commentor requested that EPA justify not establishing ground water
remediation goals for manganese, cadmium, arsenic, bis(2-ethylhexyl)phthalate,
bromodichloromethane, and chloroform.
Response: EPA is not aware of any evidence that would indicate that metals
were disposed of in any waste streams onsite. There are no know low pH
areas onsite that would lead to dissolution of metals. Exceedances of screening
levels for manganese, cadmium, and arsenic required that these metals be
maintained as contaminants of concern in ground water; however, there are no
known sources of metals being remediated at the Site. For that reason,
remediation goals are not recommended at this time; however EPA
recommends that metals be monitored in the surficial aquifer and the Floridan
aquifer to ensure that high levels do not persist.
Bis(2-ethylhexyl)phthalate was detected in one monitoring well screened in the
Floridan aquifer. Since it was not detected in surficial soil, subsurface soil, or
surficial aquifer ground water, EPA does not believe that the contaminant is
Site-related. EPA recommends that SMC monitor the Floridan aquifer for
bis(2-ethylhexyl) phthalate to verify that contaminant levels are not persistent.
Bromodichloromethane and chloroform were detected in the Floridan aquifer,
but were not detected in the surficial aquifer. Bromodichloromethane was
detected on one onsite Floridan well and one offsite Floridan well. Since there
is no reason to suspect bromodichloromethane contamination is Site-related,
EPA recommends that it be monitored rather than setting a remediation goal.
Chloroform was detected in four Floridan wells and may be related to the Site;
however, since the risk due to chloroform was less than 1 x 10"6, a RG was not
established for chloroform.
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24. The remediation goals for aldrin, alpha-BHC, atrazine, beta-BHC, dieldrin, and
EPTC in groundwater from Table 1 of the fact sheet are inconsistent with the
table presented on page 3 of EPA's memorandum (amendment to the Final
FS). According to the information presented on page 3, the RAOs should be
0.007, 0.017, 0.47, 0.059, 0.007, and 94 ug/1, respectively.
Response: The table on page 3 of EPA's memorandum (amendment to the
Final FS) should reflect goals determined on Table 3-5, page A-13 of EPA's
amendment to the Final FS. RAOs should be 0.007, 0.017, 0.47, 0.059, 0.007,
and 940 ug/1 for aldrin, alpha-BHC, atrazine, beta-BHC, dieldrin, and EPTC,
respectively. This error has been corrected in EPA's November 27,1995 FS
Revision Memo.
25. Table 3-5 from EPA's amendment to the Final FS shows a groundwater RAO
for bis(2-ethylhexyl)phthalate; however, this is not reflected in Table -1 of the
Fact Sheet or page 3 of EPA's amendment to the Final FS. This should be
clarified.
Response: Bis(2-ethylhexyl)phthalate should be crossed out on Table 3-5, as is
reflected in EPA's November 27,1995 FS Revision Memo.
Concerns about Remediation Goals for Subsurface Soils:
26. On commentor questioned inconsistencies between the proposed plan and
EPA's amendment to the Final FS. The remediation goals for aldrin, alpha-
BHC, atrazine, beta-BHC, and dieldrin in subsurface soil presented in Table 1
of the Fact Sheet are inconsistent with Table 2 from Attachment B of EPA's
amendment to the Final FS (EPA's Soil Remedial Action Objectives
Determination). According to the information presented in Table 2, the
remedial action objectives (RAOS) .for aldrin, alpha-BHC, beta-BHC, and
dieldrin should be 0.1, 0.0038, 0.456, 0.0084, and 0.101 mg/kg, respectively.
Response: The Remedial Action Performance Standards for subsurface soils in
Table 1 of the Fact Sheet and Table 3 on page B-12 of EPA's amendment to the
Final FS (EPA's Soil Remedial Action Objectives Determination) should reflect
goals calculated on Table 2 of EPA's amendment to the Final FS. This error
has been corrected in EPA's November 27,1995 FS Revision Memo. The
change will be noted in Section 11 (Significant Changes) in the Record of
Decision (ROD). However, it should be noted that the preferred remedy does
not require subsurface soil remediation.
27. One commentor asked how remediation goals for subsurface soil were
calculated. EPA selected concentrations based on the lowest dilution factors
evaluated. There appears to be inconsistency in numbers from Table 2 in
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Appendix B (EPA Soil Remedial Action Objectives Determination) and Table 4
in Appendix B, which presents the final remediation goals. Remediation goals
for aldrin, alpha-BHC, atrazine, beta-BHC, and dieldrin presented in Table 4
do not coincide with those in Table 2, and appear much too low based on
EPA's modeling' analysis. Please clarify or provide sample calculations.
Response: The low dilution factor was considered the most reasonable value
because it was based on the hydraulic conductivity determined by CDM
during onsite slug tests. Refer to response for comment 18 for further
clarification of other issues.
Concerns about the Baseline Risk Assessment*
28. One commentor asked what studies show is a safe amount of time (hours) to
be in the general area.
Response: There is no limit to the amount of time that it is safe to be in the
general area near the Site. The risk from the Site is relevant only to a person
or persons who are onsite for a long period of time (long-term exposure).
EPA's risk evaluation is based on an onsite worker being exposed 8 hours per
day, 5 days per week, and 50 weeks per year for 25 years. The Site should be
remediated before long term exposure occurs to onsite workers. There are
very few onsite workers because the facility is closed; those workers who do
go onsite are being monitored for health effects.
29. One commentor asked if pesticides could have bioaccumulated in vegetables,
cattle, etc., grown on soil contaminated in the 1950s or 1960s.
Response: Pesticides can bioaccumulate in the food chain. Therefore, it is
possible that biota and wildlife at the Site have bioaccumulated pesticides.
30. One commentor asked how many years a person would have to be exposed to
contaminated ground water or soils to develop cancer or non-carcinogenic
effects?
Response: Toxicologist are divided on the length of exposure required to
cause cancer. Typically one exposure to a carcinogen EPA's risk assessment
evaluates the probability that a dose will cause cancer during the lifetime of
the exposed individual. It should be noted that each person has a one in four
chance of developing cancer in his/her lifetime. If 10,000 onsite workers are
exposed to site contaminants at current concentrations, two additional
incidents of cancer are expected to occur.
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31. One commentor asked if property owners south of the Helena Site have been
made aware that sulfur and other pesticides may have flowed in drainage
structures to their properties in the past.
Response: Property owners have been made aware that the SMC Site and the
Helena Chemical Company Site are being remediated. They have been made
aware of the results of the investigations through pubic fact sheets. They have
been made aware that detailed information is available at the information
repository near the sites.
Concerns About The Proposed Remedy:
32. One commentor requested that the EPA allow a performance-based standard
for remediating soils in lieu of specifying a specific soil remediation
technology.
Response: The purpose of the Feasibility Study performed by the Potentially
Responsible Parties (PRPs) was to evaluate available technologies for
remediating contamination at the Site. The purpose of the Record of Decision
(ROD) is to make a decision regarding performance standards and the
preferred remediation technology based on the Feasibility Study. At the
Stauffer Management Company Site, EPA has proposed a remediation
technology and a contingency remediation technology; the contingency
remediation technology is to be executed if the preferred remediation
technology cannot achieve performance standards or is not cost effective. If
during subsequent pilot studies or during Remedial Design (RD), an
alternative technology is identified that is technically sound and cost effective,
the PRPs may request a review by EPA. However, if a technology other than
the preferred technology or the contingency technology is proposed and
approved, a ROD amendment would be necessary.
33. One commentor requested that EPA add a one-year ground water monitoring
phase (four quarterly sampling events) as a component of Remedial Design
(RD), since the ground water sampling in the Remedial Investigation was
conducted very soon after the source removal was complete. The commentor
suggested that contaminant levels in ground water will be lower when
resampled due to source removal.
Response: Specific details regarding RD are typically determined after the
ROD is approved. Most ground water remediations require that additional
ground water sampling be performed as the initial phase of design. If there
are compelling reasons why an extended ground water monitoring program
would be beneficial, it will be determined during remedial design, but not in
the Record of Decision.
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34. One commentor identified several inconsistences in background documents
and Table 1 in the Proposed Plan.
Response: These errors have been corrected in EPA's November 27,1995 FS
Revision Memo and have been described, when necessary, in Section 11 of the
ROD.
35. One commentor asked if the monitoring well network would be expanded to
areas mat he indicted may be a continuing source.
Response: The monitoring well network will be expanded as necessary to
ensure that the extent on contamination is known and is being controlled to
protect human health and the environment. The current network is adequate
to define contamination; as contaminants migrate, the network will have to be
expanded.
36. One commentor asked why EPA would select a remedy (such as thermal
desorption) which could make contaminants airborne.
Response: EPA will require that adequate engineering controls are in place to
ensure that workers and the surrounding community are protected during the
execution of any remedy at a Site. EPA will only select a remedy if it reduces
the overall risk to human health and the environment. If the remedy itself
were to increase the risk, EPA would not agree to execution of the remedy.
37. One commentor asked when excavation of soils would begin at the Site and if
people who live or work around the Site should leave the area when the
excavation is being done.
Response: Excavation of soils will not begin until the remedial design is
complete (at least 18 to 24 months from approval of the ROD). Engineering
controls will be utilized to ensure no hazardous conditions exist for those who
live and work near the Site. There will be no need to leave the area during
performance of work at the Site.
38. One commentor asked if the PRPs have selected a consultant to do the
remediation.
Response: EPA is not aware of any consultants selected by the PRPs for
performance of the work.
39. On commentor asked if Helena and Stauffer PRPs are working together, since
contaminants and remedies are similar.
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Response: EPA understands that the Helena and Stauffer PRPs have met on
occasion, but no agreement has been reached to work together to remediate
these sites.
40. On commentor asked if EPA is contributing to the development costs of the
technology being developed by the Stauffer PRPs.
Response: The Stauffer PRPs are paying for development of technology to
bioremediate pesticides at the Site.
41. One commentor asked if proposed cleanup goals for residential use would be
more appropriate because Hillsborough County has expressed interest in
expanding die jail onto the Stauffer Site.
Response: EPA toxicologists have determined that although a correctional
facility could be considered short-term residential use, outdoor exposure of
inmates is restricted. With institutional controls to prevent gardening or
excessive outdoor activity in the areas where residual pesticides are found,
industrial cleanup standards are considered protective of the health of inmates.
42. One commentor asked if EPA's preferred remediation alternative will
remediate deep contaminated subsurface soil such that the subsurface soil is
no longer a potential source of ground water contamination on the Site.
Response: EPA's preferred alternative is to remediate surface soils and
ground water. In theory, subsurface soil contamination will be remediated as
the ground water is remediated. EPA and FDEP encourage the PRPs to
remediate subsurface soils in order to reduce the ground water remediation
timeframe required; however, the proposed remedy does not require
subsurface soil remediation.
43. One commentor recommended air monitoring and air emission controls be
used during excavation of soils onsite because of the numerous complaints
received about methyl mercaptan odors during the previous removal action at
the Site.
Response: EPA will ensure that odor problems are anticipated and dealt with
promptly during excavation. EPA will require that reasonable air emissions
controls are installed.
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