Superfund Record of Decision Helena Chemical Company Tampa Plant Tampa Fl


                                    EPA/ROD/R04-96/264
                                    1996
EPA Superfund
     Record of Decision:
     HELENA CHEMICAL CO. (TAMPA PLANT)
     EPA ID: FLD053502696
     OU01
     TAMPA, FL
     05/07/1996

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            RECORD OF DECISION






SUMMARY OF REMEDIAL ALTERNATIVE SELECTION






      HELENA CHEMICAL COMPANY SITE






  TAMPA, HILLSBOROUGH COUNTY, FLORIDA






               PREPARED BY






  U.S. ENVIRONMENTAL PROTECTION AGENCY






                REGION 4






            ATLANTA, GEORGIA

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                            RECORD OF DECISION
                                DECLARATION

SITE NAME AND LOCATION

Helena Chemical 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
Helena Chemical 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., to the extent practicable, the National Contingency Plan  (NCP),  40 CFR
Part 300.

This decision is based on the administrative record for the Helena Chemical Company Superfund
Site.  The State of Florida, as represented by the Florida Department of Environmental
Protection (FDEP),  has reviewed the reports which are included in the Administrative Record for
the Helena Chemical Company Site. In accordance with 40 CFR § 300.430, as the support agency,
FDEP has provided EPA with input during the remedial selection process.  Although FDEP has not
indicated an objection to the overall approach of the selected remedy, FDEP is unwilling to
concur with this ROD because FDEP disputes the remediation goal selected for 4,4-DDT in ground
water.

ASSESSMENT OF THE SITE

Actual or threatened releases of hazardous substances from the Helena Chemical 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.  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 biological treatment (i.e., bioremediation) of pesticides and other site related
contaminants located in 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
to remove pesticides and other site related contaminants.  Because bioremediation is an
innovative treatment technology for presticide removal, low temperature thermal treatment of
contaminated soils/sediments is being proposed as a contingency remedy in the event that
bioremediation is not effective in treatability studies.

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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, and is cost-effective.  This remedy satisfies the statutory preference for treatment as
a principal element and utilizes permanent solution and alternative treatment technologies to
the maximum extent practicable.

Because this remedy addresses surface soils (0 to 2 feet deep),  hazardous substances may remain
onsite in 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                           DATE
ACTING DIRECTOR
WASTE MANAGEMENT DIVISION

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                       TABIiE OF CONTENTS

1. 0   SITE LOCATION AND DESCRIPTION 	 1

2.0   SITE HISTORY AND ENFORCEMENT ACTIVITIES 	 1

3.0   HIGHLIGHTS OF COMMUNITY PARTICIPATION 	 5

4 . 0   SCOPE AND ROLE OF REMEDIAL ACTION 	 5

5.0   SUMMARY OF SITE CHARACTERISTICS 	 6

      5.1   Physiography and Topography 	 6
      5.2   Geology/Hydrogeology 	 6
      5.3   Surface Water Hydrology 	 10
      5.4   Wildlife/Natural Resources 	 12
      5.5   Summary of Site Contaminants 	 14

            5.5.1  Overview 	 14
            5.5.2  Substances Detected in Soil 	 14
            5.5.3  Substances Detected In Ground Water 	 17
            5.5.4  Substances Detected In Sediment 	 20
            5.5.5  Substances Detected In Surface Water 	 22
            5.5.6  Substances Detected In Biota Samples 	 22

6. 0   SUMMARY OF SITE RISK	 22

      6.1  Risk Assessment Overview 	 22
      6.2  Contaminants of Potential Concern  (COPCs)  to Human Health .. 24

           6.2.1  Screening Criteria 	 24
           6.2.2  Contaminants of Potential Concern in Surficial Soil  . 24
           6.2.3  Contaminants of Potential Concern in Surficial Ground
                  Water 	 27
           6.2.4  Contaminants of Potential Concern in Florida Aguifer. 27

           6.2.5  Contaminants of Potential Concern in Sediment 	 27

      6.3  Exposure Assessment 	 27

           6.3.1  Introduction 	 27
           6.3.2  Source,  Mechanism of Release,  and Transport 	 28
           6.3.3  Potential Receptors and Routes of Exposure 	 28

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                 TABLE OF CONTENTS (continued)

            6.3.3.1  Current/Future Onsite Worker 	   28
            6.3.3.2  Current/Future Adole s cent
                      Trespasser 	   28
            6.3.3.3  Current/Future Adult
                      Trespasser/Vagrant 	   28
            6.3.3.4  Future Resident 	   28

     6.3.4  Exposure Point Concentrations 	   29
     6.3.5  Dose Assumptions 	   29

6.4  Toxicity Assessment 	   30
6.5  Risk Characterization 	   31

     6.5.1  Overview 	   31
     6.5.2  Current/Future Onsite Worker 	   33
     6.5.3  Current/Future Adolescent Trespasser 	   33
     6.5.4  Current/Future Adult Trespasser/Vagrant 	   33
     6.5.5  Future Resident 	   33

6.6  Identification of Uncertainties 	   34
6.7  Ecological Evaluation 	   34

     6.7.1  Overview	   34
     6.7.2  Contaminants of Potential Ecological Concern 	   34
     6.7.3  Exposure Assessment 	   35
     6.7.4  Toxicity Assessment 	   35

            6.7.4.1  Exposure to Current Sediments 	   35
            6.7.4.2  Exposure to Future Surface Water 	   35
            6.7.4.3  Exposure to Future Sediment 	   36

     6.7.5  Risk Characterization 	   36

            6.7.5.1  Exposure to Current Sediments 	   36
            6.7.5.2  Exposure to Future Surface Water 	   36
            6.7.5.3  Exposure to Future Sediment 	   37

     6.7.6  Uncertainty Analysis 	    37

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                     TABLE OF CONTENTS (continued)

7.0  DESCRIPTION OF ALTERNATIVES 	  37

     7.1  Remedial Action Obj ectives 	  37

          7.1.1  Beneficial Land Use 	  38
          7.1.2  Human Health Risk 	  38
          7.1.3  Ecological Risk 	  38
          7.1.4  Remediation Goals 	  40

     7.2  Remedial Alternatives 	  40

          7.2.1  Overview 	  40
          7.2.2  Alternative 1:  No Action 	  41
          7.2.3  Alternative 2:  Soil and Shallow Ground Water
                 Containment By Vertical Barriers and a Surface Cap 	  41
          7.2.4  Alternative 3:  Biologically Treat Soil Onsite; Contain,
                 Extract, Treat and Dispose of Ground Water 	  41
          7.2.5  Alternative 4:  Biologically Treat Soil Onsite; Allow Natural
                 Attenuation of Contamination in Shallow Ground Water 	  43
          7.2.6  Alternative 5:  Treat Contaminated Soil by Low
                 Temperature Thermal Desorption (LTTD)  Contain, Treat
                 and Dispose of Ground Water 	  46
          7.2.7  Alternative 6:  Treat Contaminated Soil by LTTD; Natural
                 Attenuation of Ground Water 	  47

8.0  SUMMARY OF THE COMPARATIVE ANALYSIS OF ALTERNATIVES 	  48

     8.1  Statutory Balancing Criteria 	  48
     8.2  Threshold Criteria 	  49

          8.2.1  Overall Protection of Human Health and the Environment 	  49
          8.2.2  Compliance With Applicable or Relevant and Appropriate
                 Reguirements (ARARs) 	  49

     8.3  Primary Balancing Criteria 	  50

          8.3.1  Long-Term Effectiveness and Permanence 	  50
          8.3.2  Reduction of Toxicity,  Mobility,  or Volume Through
                 Treatment 	  50
          8.3.3  Short-Term Effectiveness 	  57
          8.3.4  Implementability 	  57
          8.3.5  Cost 	  57

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                       TABLE OF CONTENTS  (continued)

     8.4  Modifying Criteria 	 58

          8.4.1  State Acceptance 	 58
          8.4.2  Community Acceptance 	 58

     8.5  Comparison of Alternatives 	 59

9.0  SUMMARY OF SELECTED REMEDY 	 60

     9.1  Source Control 	 60

          9.1.1  Maj or Components of Source Control  	 60
          9.1.2  Performance Standards 	 61

     9.2  Ground Water Remediation 	 61

          9.2.1  Major Components of Ground Water Remediation  .... 61
          9.2.2  Performance Standards 	 62

                 9.2.2.1  Extraction Standards 	 62
                 9.2.2.2  Treatment Standards 	 62
                 9.2.2.3  Discharge Standards 	 62
                 9.2.2.4  Design Standards 	 62

     9.3  Compliance Testing 	 62
     9.4  Contingency Remedy 	 62

10.0 STATUTORY DETERMINATION 	 63

     10.1  Protection of Human Health and the Environment  	 63
     10.2  Attainment of the ARARs 	 64
     10.3  Cost Effectiveness 	 65
     10.4  Utilization of Permanent Solutions to the Maximum Extent
           Practicable 	 65
     10.5  Preference for Treatment as a Principal Element  	 65

11.0 DOCUMENTATION OF SIGNIFICANT CHANGES 	 65

APPENDIX A - RESPONSIVENESS SUMMARY

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                          LIST OF TABLES






TABLE 6-1:   CONTAMINANTS OF POTENTIAL CONCERN  	  25






TABLE 6-2:   EXPOSURE PATHWAYS/ROUTES  	  29






TABLE 6-3:   SUMMARY OF POTENTIAL CANCER AND  NON-CANCER RISKS 	  32






TABLE 7-1:   REMEDIATION GOALS  	  39






TABLE 8-1:   POTENTIAL LOCATION SPECIFIC ARARS AND  TBCs 	  51






TABLE 8-2:   POTENTIAL ACTION SPECIFIC AND  TBCs  	  52






TABLE 8-3:   POTENTIAL CHEMICAL SPECIFIC ARARS AND  TBCs 	  55






TABLE 8-4:   COMPARISON OF COSTS  	  58






                            LIST OF FIGURES






FIGURE 1-1:   SITE LOCATION MAP 	    2






FIGURE 1-2:   TOPOGRAPHIC MAP 	    3






FIGURE 5-1:   SITE MONITORING WELLS AND PIEZOMETERS 	    7






FIGURE 5-2:   NORTH-SOUTH STRATIGRAPHIC CROSS SECTION 	    8






FIGURE 5-3:   pH MAP SURFICIAL AQUIFER  	    9






FIGURE 5-4:   SURFACE WATER DRAINAGE PATHWAYS 	   11






FIGURE 5-5:   PHASE I & II SOIL AND SEDIMENT  SAMPLE LOCATIONS 	   15






FIGURE 5-6:   OFFSITE SOIL SAMPLING LOCATIONS 	   16






FIGURE 5-7:   MONITORING WELLS AND PIEZOMETRIC LOCATIONS 	   19






FIGURE 5-8:   PHASE II OFFSITE SEDIMENT SAMPLING LOCATIONS  	   21






FIGURE 5-9:   PHASE II BIOTA SAMPLING LOCATIONS  	   23






FIGURE 7-1:   AREA OF SOIL TO BE REMOVED  (0-1 feet  below land surface)..   44






FIGURE 7-2:   AREA OF SOIL TO BE REMOVED  (1-2 feet  below land surface)  .   45

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Record of Decision
Helena Chemical Company Superfund Site

1.0 SITE LOCATION AND DESCRIPTION

The Helena Chemical Company (HCC) Tampa facility is localed at 2405 North 71st Street in Tampa,
Hillsborough County, Florida, approximately 0.5 mile west of the Tampa Bypass Canal (Figure
1-1). The Site is in the Orient Park Industrial area, the eastern most section of Tampa. The
main operating portion of the facility covers approximately 8 acres and is bounded on the north
by 14th Avenue, on the east by Orient Park Road, on the south by an active railway line (CSX
Railroad), and on the west by 71st Street (Figure 1-1). In addition to this property, HCC also
owns a 3 acre vacant lot immediately west of 71st Street and southwest and west of the facility
proper.

The operating facility includes an office, laboratory, bath house, product storage warehouse,
liguid processing and repackaging warehouse, and several above-ground storage tanks currently
used for emulsifiers, sun oil, and fuel oil (see Figure 1-2). A concrete surface-drainage swale
in the east-central portion of the site empties directly into an unlined stormwater runoff
retention pond located in the extreme southeast corner of the site. A spillway at the
southeastern corner of the retention pond overflows into a drainage ditch parallel to the CSX
railroad. Immediately north of the retention pond, an elevated area approximately 100' x 100'
marks the location of an active septic tank drain field.

The center of the facility is paved with concrete, while the loading dock area west of the
storage warehouse is covered with asphalt. The remainder of the site is grassy, with several
large oak trees on the north side of the property. The adjacent vacant lot is open, with thin
undergrowth and several oak trees. The majority of the site, including the vacant lot, is
fenced. The terrain is relatively flat and gradually slopes to the south and southeast.

2.0 SITE HISTORY AND ENFORCEMENT ACTIVITIES

HCC was built in 1929 as a chemical plant for the production of sulfur and was owned and
operated by Flag Sulfur Company. Details of operations are not clearly described in the
available records. According to the previous and current facility managers, Flag Sulfur
manufactured wettable and dusting sulfur and formulated pesticides, herbicides, fungicides, and
fertilizers; however, no historical records are available regarding the specific products
formulated during Flag's occupancy.

HCC purchased the facility from Flag Sulfur Company, owned by the Duval Corp., in 1967. From
1967 to 1981, HCC produced wettable dusting sulfur and formulated pesticides, herbicides,
fungicides, and liguid and dry fertilizers. The formulation process for liguid products would
consist of mixing a technical (pure) chemical (such as toxaphene) with various solvents (such as
xylene) and surfactant and/or emulsifiers (such as Solar 40 and Polyfon 0) in above-ground
mixing vessels in the Liguid Processing and Packaging LPP Storage Building. Dry products were
formulated in the east end of the Product Storage Building using a Raymond Mill for grinding and
a set of ribbon blenders for mixing. HCC would then package the finished product for resale.
No technical product was ever manufactured by HCC at the Tampa facility; rather, HCC purchased
the technical product and added solvent, emulsifiers, and/or surfactant to give the finished
product certain characteristics reguired for various applications and strengths.

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was discontinued at the facility. In 1981, HCC moved the pesticide, herbicide, and fungicide
formulation operation to an HCC Georgia office. Since 1981, HCC has formulated insecticidal
petroleum oil (a 70-viscosity paraffin-based oil with an emulsifier additive), and liguid
fertilizers. In addition to products produced at the HCC facility, numerous agricultural
products are stored in the warehouse prior to distribution to HCC's 10 Florida sales offices.
The agriculture products processed, formulated, or repackaged at the HCC facility from 1967 to
the present are referenced in Section 3 of the 1995 Remedial Investigation (RI) report.

Historically, most agricultural chemical formulation occurred in the Liguid Processing and
Packaging Storage Building (Figure 1-2), which houses six above-ground tanks used for liguid
agricultural product formulation. Five are currently in use; the sixth (a gas trap tank used
for nitrate fertilizer formulation) is no longer used. Although not currently used, xylene was
previously the most commonly used carrier in pesticides formulated at the facility.

In 1984, FDEP inspected the Helena Site and reguired guarterly monitoring of the surficial
aguifer. From 1988 to 1990, EPA investigated this site and found pesticide contamination in the
on-site soil, sediments, and surficial aguifer. Based on the potential for human exposure via
ingestion of contaminated ground water, EPA proposed this Site to the Superfund NPL in February
1992 and finalized the listing in October 1992. EPA, under CERCLA, negotiated with HCC to
conduct the Remedial Investigation/Feasibility Study (RI/FS) at the Site. HCC agreed to perform
the RI/FS. The primary focus of the investigation has been to determine the nature, magnitude,
and extent of contamination, evaluate potential risks to human health and the environment, and
evaluate potential cleanup alternatives. Neither HCC or EPA have undertaken any Site cleanup to
date. Studies conducted by HCC have documented extensive soil contamination by pesticides
related to former operations by HCC and its predecessors. Ground water contamination cf the
surficial and Floridan aguifers also exists, but to a much lesser extent. The degree of
contamination with respect to potential risks, compliance witl applicable regulatory standards,
and potential for future contamination is summarized in the following sections.

Florida Department of Health and Rehabilitative Services (FHRS), in cooperation with the Agency
for Toxic Substances and Disease Registry (ATSDR), prepared a public health assessment in
September 1993. In that report, FHRS expressed concern for on-site worker contact with
contaminated soils and exposure to sediments and ground water. FHRS made several
recommendations that additional data should be collected. The RI and Baseline Risk Assessment
(BRA) addressed these issues.

3.0 HIGHLIGHTS OF COMMUNITY PARTICIPATION

All basic reguirements for public participation under CERCLA §§ 113(k)(2)(B)(i-v) and 117 were
met inthe 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.

The Remedial Investigation/Feasibility Study Reports, the Baseline Risk Assessment Report, and
Proposed Plan for the HCC Site were released to he 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 4
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 Helena Chemical Company Superfund
Site during a public meeting at the Kenley Park Recreation Center, 1301 North 66th Street,
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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 public comment period was held from July 20, 1995 through September 23, 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 ROIiE OF RESPONSE ACTION

The purpose of the remedial alternative selected in this ROD is to reduce current and future
risks at this Site. The remedial action for soil will remove current and future health threats
posed by contaminated surface soil (i.e., soil from 0 to 2 feet below land surface (blss)) and
will prevent leaching of the soil contaminants to ground water. The ground water remedial
action will reduce future risks posed by potential usage of contaminated ground water. It also
will serve to remove the threat to surface water by reducing the concentrations of surficial
aguifer contaminants reaching nearby surface water systems. This is the only ROD contemplated
for this
Site.

5.0 SUMMARY OF SITE CHARACTERISTICS

5.1 Physiography and Topography

The HCC site is located in an area bordering Six Mile Creek and the Tampa Bypass Canal. The
Site topography is relatively flat, with elevations ranging from 28.7 to 30.7 feet above mean
sea level (Figure 2). The land surface generally slopes south and southeasterly toward the
railroad and the Stauffer facility located along the eastern bank of the Tampa Bypass Canal.
Aerial photographic analyses also suggest that the general topography of HCC and the surrounding
area has sloped south and southeast toward Six Mile Creek (prior to the Tampa Bypass Canal
construction) and south and southeast toward the Tampa Bypass Canal since construction. Flow in
the canal is to the south and west for approximately 3.5. miles, where it enters McKay Bay. At
the 22nd Street Causeway, flow from McKay Bay enters East Bay, which discharges into
Hillsborough Bay approximately 7 miles downstream from the HCC facility. The Tampa Bypass Canal
is classified as a Class III Surface Water by Florida Department of Environmental Protection.

5.2 Geology/Hydrogeology

At the HCC site, a thin veneer (3 to 6 inches) of surface soil and sediments covers fine to
medium-grained sands, making up the surficial deposits. These deposits are underlain by a stiff
intermediate day unit (Intermediate Confining Unit) that was encountered in every soil boring
drilled to sufficient depth at the property. The stiff days encountered at the Site appear to
form a confining unit between the overlying surficial aguifer and the underlying of sandy,
clayey, poorly consolidated limestones that grade into more indurated limestones (see Figures
5-1 and 5-2).

The surficial deposits extend to approximately 11 feet below land surface (bis) and are
primarily unconsolidated, brown, fine-grained sand with organic matter. Traces of day, silt,
medium-grained sand, and shells are common in the fine-grained sand matrix. The surficial
deposits form a sharp contact with the underlying Intermediate Confining Unit. The ground water
level was observed at a depth varying from 2 to 4 feel bis between April 1993 and July 1994.
Specific conductivity values measured in surficial aguifer wells were inversely proportional to
and correlated with pH values. As shown in Figure 5-3, the lowest pH values (1.8 pH units), and
correspondingly, the highest conductivity values (11,750 ms/cm), are concentrated near the
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former
sulfur pit.

The intermediate day unit extends approximately 11 feet bis and is predominantly stiff
blue-green and tan day with 5 to 15 percent quartz sand. This unit was encountered in every
boring drilled to sufficient depth during the RI. The day exhibits low hydraulic permeability,
forming the Intermediate Confining Unit between ground water in the upper superficial aguifer
and lower Floridan Aguifer. The lowest elevations in the clay surface are near the office,
loading dock area, lab, and bath house.

Laboratory analysis of Shelby tube samples indicates permeabilities ranging from 1.6 x 10-7 to
2.9 x 10-10. The thickness of the Intermediate Confining Unit rages from approximately 8 feet
south of HCC on Wheel blast property to, approximately 25 feet in the central and east portions
of the property. The Intermediate Confining Unit is approximately 10 feet thicker in the east
central portion of the site than it is near the office, and 17 feet thicker in the east central
portion of the site than it is south on adjacent property.

The Floridan Aguifer is encountered at 22 to 28 feet bis, the upper section is a tan to white
moderately indurated, sandy, clayey limestone. An extremely well-indurated limestone horizon is
encountered at 30 to 34 feet bis. A confined aguifer is developed in the upper and lower
Floridan limestone. The less consolidated upper material of the Floridan has been assigned to
the Tampa Member of the Arcadia Formation. Limestone above the well-indurated horizon has not
been considered part of the Floridan. The lack of any significant confining unit separating the
upper limestone from the more indurated horizon precludes the hydraulic separation of the two
units. One water supply well open to the Floridan at the HCC site was used to provide water for
pesticide manufacturing and formulation processes. The water supply well, which is 6 inches in
diameter and approximately 500 feet deep, was sampled once during previous investigations.

The lowest pH identified in the Floridan aguifer was 5.38 standard units in a well on the
adjacent Stauffer Management Company Property. Ground water flow is oriented in a radial
pattern to the northeast, east, southeast, south, and southwest. Gradients are the highest in
the southeastern direction, and lowest toward the northeast and southwest.

5.3 Surface Water Hydrology

Surface water at the Site is comprised totally of stormwater runoff (see Figure 5-4). The Site
is subject to flooding during periods of extended, heavy rainfall. Surface water runoff for the
Site as a whole is characterized by a drainage divide at the southern end of 71st Street. From
this divide, flow follows two drainage pathways along the north side of the CSX railroad tracks.
One path is to the east toward Orient Road and the other path is to the west toward the vacant
lot.

Storm water runoff from the central portion of the Site channels into the concrete drainage
swale and flows into the onsite retention pond which is designed to hold storm water runoff
during a 20-year flood. A spillway at the Southeastern corner of the pond allows overflow to
drain into a storm water drainage ditch parallel to the railroad.

On the west and north boundaries of the Site, storm water flows to the southwest where it
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collects in a low area on the southwest end of the vacant lot and to the north via a paired
ditch/culvert system along the east and west shoulders of 71st Street. On the east boundary,
surface water flow continues south along the ditch parallel to Orient Road. Drainage turns
eastward through a culvert under Orient Road, then travels east-northeast for approximately 0.5
mile. The drainage pathway continues through a swale on the north side of the CSX right-of-way.
An earthen berm blocks the drainage way 400 to 500 feet east of Orient Road. A small hole,
which could be a collapsed culvert or possibly a natural erosional feature, is located at the
base of the berm. Water flows from the east side of the berm to an unnamed stream. A culvert
cuts through the Tampa Bypass Canal levee and transports water from the unnamed stream to the
Tampa Bypass Canal.

5.4 Wildlife/Natural Resources

The HCC Site contains several fields and vacant lots. A flat, grassy, maintained field lies in
the northwest corner of the Site. Scattered oak trees (Quercus sp.), cabbage palm trees (Sabal
palmetto), and a camphor tree (Cinnamomum camphora), along with other species, are located along
the borders of this field. The field is well maintained via freguent watering and mowing. To
the east of the northwest field lies a smaller, fenced field which contains the former drum
washing area. Within this area are several oak trees. East of the former drum washing area, in
the northwest corner of the Site, is a less maintained field that contains several oak trees and
a number of cabbage palms and other palms.

A storm water retention pond is located in the southeast corner of the Site. The pond is
unlined and retains water to a depth of 2 feet. Overflow drains via a small concrete spillway
and a small unlined drainage swale off of the property. The pond is surrounded by grass that is
maintained via mowing. The pond banks are grassy, but not maintained, and the grass is about 1
foot tall. This grass extends down into the pond, forming a band of emergent vegetation which
grows throughout the pond's littoral areas and into the pond's middle. The pond seems to
contain a large amount of algae, but is relatively devoid of animals. During an onsite visit in
March 1993, one aguatic beetle was observed in the pond, and there was evidence of some flying
insects moving about over the pond's surface. Some small spider webs also were observed
attached to the emergent grasses. During an onsite visit in October 1993, small aguatic snails
were observed in an open water area where the concrete swale drains into the pond. No evidence
was seen of amphibians, tadpoles, or any minnows or fish during any of the visits to the Site
during 1993. The pond is part of the runoff control system at the Helena property and does not
constitute a significant ecological habitat.

To the west of the facility is a large vacant lot that is not maintained. The lot contains
numerous large oak trees, cabbage palm trees, and other palms. The shrubby understory contains
shrub verbena (Latana camara) , asters, beauty-berry (Callicarpa americana), bluestem (Sabal
minor), wax mallow (Malvaviscus arboreus), purple nightstand (Solanum americanum), muscadine
(Vitis rotundifolia), catbrier (Smilax bona-nox), and a large grove of fishpole bamboo plants
(Phyllostachys aurea), along with other ruderal plants and weeds.

Immediately downstream of the HCC facility, along the CSX tracks toward the Tampa Bypass Canal,
is an extremely disturbed and unnatural habitat containing weedy, ruderal herbs and shrubs.
Isolated examples of cattails (Typha sp.) and a few small willow trees (Salix sp.) grow in and
around this area. As the drainage ditch continues to the east, it becomes drier, and contains
muddy soil inhabited by mosses and grasses. Vegetation along its course includes cattails,
shrub-verbena, rattlebox (Sesbania drumondi), silk-tree (Albizia julibrissin), and other weeds
and shrubs typical of disturbed sites.

The downgradient pathway ends abruptly at the vehicle wrecking yard, where the surface drainage
appears to drain into a small vertical drainage depression, possibly a natural erosional
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feature. It is possible that water draining through this feature exits directly or seeps into
an adjacent wetland area. The wetland area is bounded on the north by Broadway Avenue, to the
south by the CSX tracks, to the west by the vehicle wrecking yard, and on the east by the bypass
canal. A small unnamed stream flows northeast under Broadway Avenue, passing north of the
wetland, and
discharging into the bypass canal. Surface water from the wetland drains north into this small
stream.

The wetland is surrounded by ruderal habitats of one form or another. A maintained grassy
buffer surrounds the north, south, and eastern fringe of the wetland. To the northwest, tall
oak trees stand between the northern part of the wrecking yard and the wetland, while the
southwest border of the wetland diverges into a large population of beardgrass and various
ruderal species (red mulberry [Morus rubra], shrub verbena, silk tree, rattlebox, and various
escaped ornamentals and introduced species which inhabit disturbed sites). Inside the wetland
the approximately 3-meter
overstory is dominated by Carolina willows (Salix caroliniana) and sea myrtle (Baccharis
halmifolia). The understory includes primerose willow (Ludwigia peruviana), duck potatoe
(Sagittaria sp.), pepper vine (Ampelopsis arborea), Virginia creeper (Parthenocissus
guinquefolia), was myrtle (Myrcia cerfira), dewberry (Rubus sp.), and other miscellaneous
wetland herbs and shrubs.

Animal life was not conspicuous in the wetland. No amphibibians or reptiles were noted within
the wetland's confines, even when it was flooded. No mammals were noted abiding within the
area. Birds were seen in the vicinity of, but not within, the wetlands. Potential threatened
or endangered species which were noted to traverse the area under investigation were various
shorebirds, which were seen in and around the bypass canal during this investigation. During
the remedial investigation, shorebirds were noted one afternoon on the HCC facility itself.

The unnamed stream was rich in aguatic life. Downgradient from the wetland outfall mosguito
fish, two small large-mouth bass, and a bluegill panfish were noted. The sediments were rich
with benthic invertebrates with a species of freshwater clam, two snail species, and a small
crayfish noted.

5.5 Summary of Site Contaminants

5.5.1 Overview

The RI concluded that releases of polychlorinated pesticide compounds, semi-volatiles,
inorganics, volatile organic compounds (VOCs), and metals have occurred at the Site. Documented
releases on the site property are as follows:

• Pesticide discharges to the ground (i.e., the retention pond) from the former
pollution control system and from pesticide washouts;

• An approximate 10,000-gallon xylene release to the ground surface in the area
immediately southeast of the aboveground storage tanks and east of the liguid
processing and packaging building;

• A release of magnesium and zinc to the ground in the former fertilizer drum
washing area north of the liguid processing and packaging storage building; and

• Fugitive emissions from the formulation of dry pestides.

5.5.2 Substances Detected in Soil
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During the RI, soil samples were taken from two intervals. Samples were collected in the
interval from ground surface to a depth of 1 foot bis. Samples were collected in the interval
between 1 foot bis and the surface of the water table (typically • 3 ft) . Over one hundred
discrete soil samples (excluding duplicates, guality assurance and split samples) were collected
and analyzed for Target Compound List/Target Analyte List (TCL/TAL) analyses. In addition,
several dozen composite samples were collected and used to delineate ambient levels of site
constituents in soils. Soil sampling locations are shown on Figures 5-5 and 5-6.

Total pesticide detections ranged from 1.7 parts per billion (ppb) to 2,665,060 ppb in the upper
interval, and from 0.116 ppb to 6,485,900 ppb in the lower interval. The highest total
pesticide concentrations in both soil sample intervals were detected in the general vicinity of
the retention pond, the former xylene and toxaphene tanks, west of the active bath house, and in
the septic drain field. The primary pesticide constituents identified in soil samples were DDT
(and its degradation products DDE and ODD), chlordane (alpha and gamma isomers), toxaphene, and
BHC (alpha, beta, delta, and gamma [lindane] isomers). The extent of toxaphene soil
contamination,
both horizontally and vertically, encompasses all areas contaminated by other pesticide
constituents. Those components comprising a less significant fraction of the total pesticides
identified include aldrin, dieldrin, endosulfan I and II, endosulfan sulfate, endrin, endrin
ketone, endrin aldehyde, heptachlor, heptachlor epoxide, and methoxychlor.

Polyaromatic hydrocarbons (PAHs) were the semi-volatiles detected most freguently at the highest
concentrations in Site soil samples. The highesi PAH concentrations in Site soils were located
east of the Product Storage Building, and south of the former xylene and toxaphene storage tanks
and emulsifier storage tanks. Detected PAHs included 2-methylnaphthalene, 2-chloronaphthalene,
acenaphthalene, fluorene, phenanthrene, anthracene, carbazole, fluoranthene, pyrene,
benz(a)anthracene, chrysene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)Opyrene,
indeno(1,2,3-cd)pyrene, dibenz(a,h)anthracene, and benzo (g,h,i)perylene. Other semi-volatiles
identified less freguently and at lower concentrations included phenol, dibenzofuran,
hexachlorobutadiene, hexachlorobenzene, butylbenzylphthalate, and bis(2-ethylhexyl)phthalate.

Ethylbenzene and total xylenes were the volatiles identified most freguently at the highest
concentrations in soil sample. Elevated ethylbenzene and xylene concentrations are concentrated
along the south central and southeast portions of the Site, in the vicinity of the former xylene
storage tanks. Minor fractions of volatiles identified in the soils include carbon
tetrachloride, trichloroethene (TCE), tetrachloroethene (PCE), chloroethane, and toluene, and
the potential laboratory artifacts acetone, methylene chloride, 2-butanone, and chloroform.

In general, the following metals were identified most freguen ly at the highest concentrations:
aluminum, calcium, iron, magnesium, manganese, and zinc. In the areas of the former sulfur pit
and along the CSX railroad tracks, the soil contains residual elemental sulfur.

5.5.3 Substances Detected in Ground Water

During the RI, 31 monitoring wells and two piezometers were sampled at the Helena facility and
surrounding properties. Twenty-five of the wells and the two piezometers are screened in the
surficial aguifer; six of the wells are screened in the Floridan aguifer. Ground water sampling
locations are shown on Figure 5-7. The results of ground water samples show that chlorinated
pesticides, PAHs, phenols, and VOCs have reached the onsite and adjacent surfidal monitoring
wells. Select pesticides, PAHs, phenols, and VOCs also were present in four of the six Floridan
Aguifer monitoring wells.
-------
The highest pesticide concentrations in ground water are just south of the facility. Pesticides
in the surficial aguifer are primarily BHC (indudin lindane), DDT and related degradation
products, and endosulfans. Those components making up a less significant fraction of the total
pesticides in shallow ground water include aldrin, chlordane (both isomers), endrin, endrin
ketone, endrin aldehyde, methoxychlor, heptachlor, and heptachlor epoxide. Pesticides in the
Floridan Aguifer wells are mainly BHC isomers, aldrin, and dieldrin with lower concentrations of
DDT and related degradation products, endosulfan I, endosulfan II, endosulfan sulfate,
chlordane, endrin, endrin ketone, and methoxychlor detected.

Surficial aguifer samples identified a lindane plume in excess of the 0.2 part per billion (ppb)
maximum contaminant level (MCL) moving southeast across the HCC site onto adjacent property.
Lindane concentrations exceeding MCLs were identified in 12 surfidal wells and two surfidal
piezometers. Floridan Aguifer wells contained a lindane plume moving southeast across the
property. Lindane was identified in three Floridan wells with two exceedances of the 0.2 ppb
MCL. Isolated exceedances ofthe MCLs for chlordane, endrin ketone, and heptachlor epoxide also
were identified in surficial aguifer ground water samples.

PAHs and phenols are a concern in ground water. The highes concentrations in the surficial
aguifer were south and southeast of the former xylene storage tanks along the CSX right-of way
and on Wheelblast property adjacent to the site. Detected semi-volatiles in surficial wells
included naphthalene, 2-methylnaphthalene, fluorene, and phenols, including methylphenols,
chlorophenols, and nitrophenols. Lower concentrations of semi-volatiles in Floridan wells
included naphthalene, 2-methylnaphthalene and fluoranthene, and phenols, induding chlorophenol
and methylphenol.

The highest concentration of VOCs in surficial aguifer ground water were ethylbenzene and
xylene, concentrated in the general vicinity of the former xylene and emulsifier storage tanks.
Other VOCs in shallow ground water included carbon disulfide, benzene, chlorobenzene,
chloroform, 1,2-dichloropropane, PCE, and 2-hexanone. VOCs in the Floridan wells induded TCE,
PCE, 1,2-dichloroethene (1,2-DCE), ethylbenzene, xylene, trichloroethane,
trans-1,3-dichloropropene, and chlorobenzene. Acetone, methylene chloride, and 2-butanone also
were detected in samples from both surficial and Floridan wells; however, these are suspected
laboratory artifacts. Primary and secondary MCLs for xylene, ethylbenzene, toluene, PCE, and
TCE were exceeded in select surficial wells. Primary and secondary MCLs for PCE, TCE, and
benzene also were exceeded in select Floridan wells. PCE and DCE identified in the surficial
and Floridan wells appear to be related to the former Alaric property northwest of the Site.

The most commonly detected inorganics in ground water were aluminum, calcium, iron, magnesium,
manganese, potassium, and zinc. The highest concentrations were detected along the southern
edge and south of the facility, coinciding with the plume of low pH, and in the drum washing
area. Infreguently, primary and secondary MCLs were exceeded for antimony, arsenic, beryllium,
cadmium, chromium, lead, nickel, and thallium, generally in the area of low pH. The lov pH
values in ground water are the result of the former sulfur processing facility. Oxidation of
sulfur, as
the result of contact with water; created low pH conditions. The plume of low pH ground water
appears to originate at the former sulfur pit as shown in Figure 6.

5.5.4 Substances Detected in Sediment

Seventeen sediment samples were collected during the RI at locations shown on Figure 5-5 and
Figure 5-8. The samples were analyzed for TCL/TAL compounds. In general, elevated
concentrations of pesticides occur in the retention pond area and attenuate from the pond to the
-------
spillway area. Outside the pond area pesticide concentrations increase along the surface water
pathway south of the Site, culminating in the highest concentrations occurring in the area of
the CSX/Orient Road culvert. Contaminant concentrations decrease downgradient from the
CSX/Orient Road culvert to the drainage depression and wetland adjacent to the Tampa Bypass
Canal. On the west side of the Site, pesticide concentrations are highest directly across from
the product storage area, and decrease along the northern drainage path from this area.
Pesticides detected in sediments include DDT and associated metabolites, aldrin, dieldrin,
endrin, endrin ketone, endrin aldehyde, heptachlor, heptachlor epoxide, endosulfan I and II,
toxaphene, BHC (all isomers), and chlordane (alpha and gamma isomers). Total pesticide
concentrations ranged from 0.3015 ppb (in the unnamed stream) to 2,912,700 ppb (in the onsite
retention pond).

Semi-volatiles detected in sediment samples include PAHs (acenaphthalene, anthracene,
benzo(a)anthracene, benzo(b)pyrene, benzo(b)fluoranthene, benzo(g,h,i)perylene,
benzo(k)fluoranthene, carbazole, chrysene, dibenz(a,h)anthracene, fluoranthene,
indeno(1,2,3-cd)pyrene, 2-methylnaphthalene, naphthalene, phenanthrene, and pyrene). Other
semi-volatiles include phenols, bis(2-ethylhexyl)phthalate, dibenzofuran, dichlorobenzidine,
diethyphthalate, and di-n-butyl phthalate.

The highest concentrations of VOCs were detected in the retention pond. VOCs detected in
sediments include ethylbenzene, total xylenes, toluene, and carbon disulfide.

Inorganics detected in sediments include the aluminum, arsenic, barium, beryllium, cadmium,
calcium, chromium, cobalt, copper, cyanide, iron, lead, magnesium, manganese, mercury, nickel,
potassium, sodium, vanadium, and zinc. The highest concentrations of total metals were detected
in the upgradient wetland sample, and the highest concentration of cyanide was detected in the
background stream sample.

5.5.5 Substances Detected in Surface Water

Surface water was not sampled during the RI due to lack of rainfall of adeguate duration and
magnitude.

5.5.6 Substances Detected in Biota Samples

Two biota samples were collected for analyses. The sample locations are shown on Figure 5-8.
The samples were composed of benthic organisms including freshwater clams, an aguatic snail, and
other benthic organisms. Only a limited amount of material could be collected; therefore, the
samples were submitted for pesticides analysis only. Pesticides were not detected in either
biota sample.

6.0 SUMMARY OF SITE RISKS

6.1 Risk Assessment Overview

CERCIA directs EPAto 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 BRA provides the basis for taking action and indicates contaminants
and the exposure pathways that need to be addressed by the remedial action. This section of the
ROD contains a summary of the results of the BRA conducted for this Site.

The risk assessment is based on the data gathered in the Remedial Investigation (RI) and
-------
includes analyses of samples of ground 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 6.7 through 6.6 address the risk assessment evaluation for human health
due to exposure to surface soil (i.e., 0-2 feet bis), sediment, and ground water. Section 6.7
describe s the potential impacts on aguatic and terrestrial life associated with contamination
in sediment adjacent to the Helena Site.

6.2 Contaminants of Potential Concern (COPCs) to Human Health

6.2.1 Screening Criteria

The chemicals measured in the various environmental media during the RI were evaluated for
inclusion as chemicals of potential Concern in the risk assessment by application of screening
criteria. The screening criteria which resulted in elimination 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 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 10-6 or a Hazard Quotient (HQ)
of 0.1 using residential tap water assumptions should be selected as COPC. Region 3
Risk-Based Concentration Tables were used to screen chemicals.

As a result of applying the above listed criteria, Table 6-1 lists he contaminants of potential
concern (COPC) associated with the HCC 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

Five naturally occurring essential nutrients were eliminated. Twenty-four chemicals were
eliminated because they occur at concentrations below the Region 3 Risk-Based screening
criteria. Forty-eight chemicals reported in the surface soil onsite meet the COPC criteria
(Table 6.1). These were evaluated in the guantitative risk assessment.

While surface soils (0-2 feet bis) are considered a threat to human health due to possible
direct exposure, Region 4 does not consider direct exposure to subsurface soils (> 2 feet bis)
to be a direct exposure threat. However, removal and treatment of contaminated subsurface soil
could minimize the timeframe necessary for ground water restoration and eliminate the need for
deed restrictions and five-year reviews.
-------
TABIiE 6-1. CONTAMINANTS OF POTENTIAL CONCERN (COPCs)
CHEMICAL
GROUNDWATER
FLORIDAN
GROUNDWATER
SURFICIAL
SURFACE
SOIL
SEDIMENT
1,2-Dichloroethene (total)
1,4-Dichlorobenzene
2,4-Dichlorophenol
2,4-Dimethylphenol
2,4-Butanone
2-Hexanone
2-Methylnaphthalene
2-Methodphenol
4,4'-DDD
4,4'-DDE
4,4'-DDT
4-Methyl-2-Pentanone
4-Methylphenol
4-Nirtophenol
Acenaphthylene
Acetone
Aldrin
alpha-BHC
alpha-Chlordane
Aluminum
Antimony
Arsenic
Barium
Benzene
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)fluoranthene
Benzo(g,h,k)perylene
Benzo(k)fluoranthene
Beryllium
beta-BHC
Cadmium
Carbon Disulfide
Chlorobenzene
Chromium
Chrysene
Cobalt
Copper
Cyanide
delta-BHC
Dibenz(a,h)anthracene
Dibenzofuran
X
X
X
X
X
X
X
X
X
X
X

X
X
X
X
X

X
X
X

X
X
X
X
X
X

X
X
X

X
X
X
X

X
X
X

X
X
X
X
X
X
X
X

X
X
X
X
X
X
X

X
X
X
X

X
X
X

X
X

X
X
X
X
X
X
X

X
X

X
X
X
-------
TABIiE 6-1. CONTAMINANTS OF POTENTIAL CONCERN (COPCs) - continued

CHEMICAL GROUNDWATER GROUNDWATER SURFACE SEDIMENT
GROUNDWATER
FLORIDAN
GROUNDWATER
SURFICIAL
SURFACE
SOIL
Dieldrin
Endosulfan I
Endosulfan II
Endosulfan sulfate
Endrin
Endrin aldehyde
Endrin ketone
Ethylbenzene
gamma-BHC (Lindane)
gamma-Chlordane
Heptachlor
Heptachlor epoxide
Indeno(1,2,3-cd) pyrene
Lead
Manganese
Methoxychlor
Naphthalene
Nickel
0,P'DDD
DDE
0,P'DDT
Phenathrene
Sodium
Tetrachloroethene
Thallium
Toluene
Toxaphene
Trans-1,3-Dichloropropene
Trichloroethene
Vanadium
Xylene (total)
Zinc
X
X
X
X
X
X
X
X
X
X
X
X

X
X
X
X

X
X
X
X
X
X
X
X
X
X

X
X
X
X
X
X
X
X

X
X
X
X
X

X
X
X
X
X
X
X
X
X
X
X

X
X
X
X
X
X
X
X

X
X
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6.2.3 Contaminants of Potential Concern in Surficial Ground Water

Three naturally occurring essential nutrients were eliminated because they are toxic only at
very high doses. Fourteen chemicals were eliminated because they were below the Region 3
Risk-Based screening criteria. Forty-eight chemicals reported in the Site-related monitoring
wells meet the COPC criteria (Tabl 6-1). These were evaluated in the guantitative risk
assessment.

6.2.4 Contaminants of Potential Concern in the Floridan Aguifer

Two naturally occurring essential nutrients were eliminated because they are toxic only at very
high doses. Thirteen chemicals were eliminated because they were below Region 3 Risk-Based
screening criteria. Thirty-five chemicals reported in the Site-related monitoring wells meet
the COPC criteria (Table 6-1). These were evaluated in the guantitative risk assessment.

6.2.5 Contaminants of Potential Concern in Sediment

Sediments were evaluated using typical human health exposure criteria in the Baseline Risk
Assessment. However, because sediments near the site (i.e., sediment located at SD-1, SD-2,
SD-3, SD-4, SD-5, SD-6, SD-7, SD-8, SD-10, SD-14, and SD-15) are located in ditches that only
contain intermittent water, EPA and FDEP agree that those sediments should be treated as soil
and soil remediation goals should be applied. Therefore, sediment risk and remediation
considered the same as surface soil for the purposes of this ROD. Sediments in the wetlands,
unnamed
tributary, and bypass canal were relatively uncontaminated.

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 HCC Site. Whether a contaminant is actually a
concern to human health and the environment depends upon the likelihood of exposure, i.e.
whether the exposure pathway currently is complete or could be complete in the future. A
complete exposure pathway (a seguence of events leading to contact with a contaminant) is
defined by the following four elements:

• a source and mechanism of release from the

• 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, derma absorption).

If all four elements are present, the pathway is considered complete.

6.3.2 Source, Mechanism of Release, and Transport

The primary release mechanisms are leaks and infiltration from the former pollution control and
laboratory waste tanks or drum washing area, and runoff from the retention pond or vacant lot.
The secondary source of chemicals is soil. A secondary release mechanism is infiltration into
the ground water. Contaminated ground water and soil are believed to be the major sources of
-------
potential exposure for human receptors.

6.3.3 Potential Receptors and Routes of Exposure

6.3.3.1 Current/Future Onsite Worker

Onsite workers were assumed to be exposed to Site-related contaminants in soil or air while
involved in outdoor activities. The routes of exposure considered for the onsite worker were
incidental ingestion and dermal contact with surface soil 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 manner as the current worker;
therefore, the future worker scenario is the same as the current worker scenario.

6.3.3.2 Current/Future Adolescent Trespasser

Nearby residents/trespassers could come into contact with soil. Adolescent trespassers were
assumed to be exposed to contaminants in soil through incidental ingestion and dermal contact.

6.3.3.3 Current/Future Adult Trespasser/Vagrant

It is possible that vagrants are gaining access to the site. Vagrants were assumed to be
exposed to contaminants in soil via incidental ingestion and dermal contact.

6.3.3.4 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 soil. Ground water was evaluated due to the possibility of future
contamination of offsite private wells or the installation of a private well onsite. Table 6-2
outlines the potential exposure pathways and routes of exposure for both the current and future
scenarios.
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TABIiE 6-2
Exposure Pathways/Routes
Helena Chemical Company
EXPOSURE
MEDIA
SCENARIO
RECEPTOR
EXPOSURE PATHWAYS
Ground Water Future Onsite Resident l.Ingesticn of drinking water
(Adult-, and Child, 1-6) 2.Inhalation of VOCs in ground
water
Current/
Future
Worker
l.Icidental Ingestion
2.Dermal Contact
Surface Soil
Current/ Offsie Adolescent
Future (7-16)
1.Incidenal Ingestion
2.Contact Dermal
Current /
Future
Adult
Vagrant
1.Incidental Ingestion
2.Dermal Contact
Future Onsite Resident
(Adult; and Child, 1-6)
1.Incidental Ingestion
2.Dermal Contact
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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 time (70 years x 365 days/year) to evaluate potential carcinogenic health
effects. Assumptions used to evaluate each receptor are described below.

• The body weight used for the child (age 1-6) Was 15 kg. The body weight used for
the adolescent (age 7-16) was 45 kg. The body weight used for the adult was 70 kg.

• Exposure to soil occurs 5 days/week for 50 weeks/year (250 days/year) for the onsite
worker, 350 days/year for the onsite resident, and 52 days/year for the
current/future trespasser (adult and adolescent).

• Exposure to ground water occurs 350 days/year for the onsite adult and child
resident.

• Incidental soil ingestion occurs at a rate of 50 mg/day for the onsite worker, 100
mg/day for the 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.

• The drinking water ingestion rate was assumed to be 2 L/day for the adult resident
and 1 L/day for the child resident or future worker.

6.4 Toxicity 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 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., 1x10-6 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 1x10-6 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 has established a policy that an upper limit cancer risk falling below or within the range
of 1x10-6 to 1x10-6 (or 1 in 1,000,000 to 1 in 100,000) is acceptable. It should be noted,
however, that the Florida Department of Environmental Protection (FDEP) has established a policy
that only risk less than 1 x 10-6 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 RID, the
exposure is not expected to cause any non-carcinogenic effects, even if the exposure is
continued for a lifetime. In other words, if the estimated dose divided by the 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 1x10-6 is considered a minimal
or de minimus risk. The risk range of 1x10-6 to 1x10-4 is an acceptable risk range and would
not be expected to reguire a response action. A risk level greater than 1x10-4 would be
evaluated further and a remedial action to decrease the estimated risk considered. It should be
noted, however, that the FDEP has established a policy that only risk less than 1 x 10-6 is
acceptable.

A hazard guotient (HQ) of less than unity (1.0) indicates that he exposures are not expected to
cause adverse health effects. An HQ greater than one (1.0) reguires further evaluation. For
example, although the hazard guotients of the contaminants present are added and exceed 1.0,
further evaluation may show that their toxicities are not additive because each contaminant
affects different target organs. When the total effect is evaluated on an effect and target
organ basis the hazard index of the separate chemicals may be at acceptable levels.

Carcinogenic risks and non-carcinogenic hazards were evaluated for potential exposures to
contaminants of potential concern in soil, sediment, and ground water. The receptor population
was current/future onsite worker, current/future adolescent trespasser, current/future adult
trespasser, and future residents. The results are summarized in Table 6-3 and are described
below.
-------
ABIiE 6-3. SUMMARY OF POTENTIAL CANCER AND NON-CANCER RISKS
Exposure
Medium/Pathway
Surface Soil
Current/Future
Worker
Current/Future
Adolescent
Trespasser
Current/Future
Adult Trespasser
/Vagrant
Future
Resident
Cancer
HQ
Cancer
HQ
Cancer
HQ
Cancer
HQ
Adult
Child
Incidental Ingest
Dermal Contact
Ground Water
Ingestion
Inhalation
TOTAL
NOTES : NE Not
2x10-3
2x10-3

NE
NE
4x10-3
Evaluated for this
5
5

NE
NE
10
recept
5x10-4
6x10-4

NE
NE
1x10-3
:or .
3
4

NE
NE
7

3x10-4
3x10-4

NE
NE
6x10-4

2
2

NE
NE
4

2x10-2
1x10-2

2x10-2
8x10-7
5x10-02 b

10
7

lOOa
la
lOOb

100
50

200a
3a
400b

Carcinogenic toxicity value not applicable.

The hazard index provided is for ingestion of ground water from the surficial aguifer. The hazard indices
for ingestion and inhalation of ground water from the Floridan Aguifer for adult and child residents are 20
and 2, and 50 and 5, respectively.

The limited index provided includes ingestion of ground water from the surficial aguifer only. The total
hazard indices including ingestion and inhalation of ground water solely from the Floridan aguifer for adult
and child residents are 20 and 50, respectively.
-------
6.5.2 Current/Future Onsite Worker

The total incremental lifetime cancer risks for the current/future onsite worker through
exposure to chemicals in soil was 4x10-03, primarily due to incidental ingestion of and dermal
contact with aldrin, toxaphene, and dieldrin in soil. The total hazard index for the
current/future worker was 10, primarily due to incidental ingestion of and dermal contact with
aldrin, chlordane, toxaphene, and 4,4'-DDT in soil.

6.5.3 Current/Future Adolescent Trespasser

Current/future adolescent trespassers near the Site were assumed to be exposed to chemicals in
soil and sediment via incidental ingestion and dermal contact. The total cancer risk for the
current/future adolescent trespasser through all pathways was lxl-03, primarily due to
incidental ingestion of and dermal contact with aldrin, toxaphene, and dieldrin in soils. The
total hazard index for the current/future adolescent trespasser was 7, primarily due to
incidental ingestion of and dermal contact with aldrin, chlordane, toxaphene, and 4,4'-DDT in
soils.

6.5.4 Current/Future Adult Trespasser/Vagrant

Current/future adult trespassers/vagrants near the Site were assumed to be exposed to chemicals
in soil via incidental ingestion and dermal contact. The total cancer risk for the
current/future adult trespasser through all pathways was 6x10-04, primarily due to incidental
ingestion of and dermal contact with aldrin, toxaphene, and dieldrin in soils. The total hazard
index for the current/future adolescent trespasser was 4, primarily due to incidental ingestion
of and dermal contact w ith aldrin, chlordane, and toxaphene in soils.

6.5.5 Future Resident

Potential future residents at the Site were assumed to be exposed to chemicals in onsite soils
through incidental ingestion and dermal contact. In addition, the future resident (adult or
child) was assumed to be exposed to chemicals in ground water through drinking water ingestion
and inhalation. The total cancer risk for the future resident (adult and child) through all
pathways was 3x10-02 when exposed to chemicals in soils and the surficial aguifer, or 3x10-02
when exposed to chemicals in soils and the Floridan aguifer. Primary contaminants of concern
(COCs) in soils are toxaphene, ODD, DDT, chlordane, and dieldrin; while the primary COCs in
ground water are alpha-BHC, tetrachloroethane, benzene, arsenic, dieldrin, and aldrin.

The hazard index was calculated for the future adult resident and the future child
resident. When exposed to chemicals in soils and surficial aguifer ground water, the
hazard indices for the future adult and child residents were 100 and 400, respectively.

When exposed to chemicals in soils and the Floridan aguifer ground water, the hazard indices for
the future adult and child residents were 20 and 50, respectively. Primary contaminants of
concern (COCs) in soils are toxaphene 4, DDT, aldrin, chlordane, and dieldrin; while the primary
COCs in ground water are gamma-BHC, arsenic, dieldrin, dichlorophenol, ethylbenzene, manganese,
and zinc.

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. Soils, ground water, and sediments from offsite ditches and the unnamed tributary to
the Tampa Bypass Canal were sampled to determine the extent of contamination, as described in
Section 5.

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

Three major habitats (aquatic, wetland, and terrestrial) are represented on or near the Site.
The aquatic habitat is represented by the fresh and estuarine deep-water habitat provided by the
Tampa Bypass Canal. Wetland habitats east of the HCC Site have been treated collectively as a
single habitat. There are two areas (vacant lot and operations area) that may provide habitat
for terrestrial species. Areas adjacent to the Site are heavily urbanized, with very little
contiguous vegetative cover. Only the aquatic and wetland habitats were evaluated for potential
ecological risk due to the HCC Site; the terrestrial habitats were not evaluated because soils
will be remediated for protection of human health anyway.

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, inhalation/
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 maximum concentration detected was used as the exposure point concentration of
contaminants of potential concern in each-media evaluated. 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.

6.7.4 Toxicity Assessment

6.7.4.1 Exposure to Current Sediments

Sediments were evaluated by comparing maximum sediment concentrations with EPA Region 4 Waste
-------
Management Division sediment screening levels. Exceedance of these screening levels might
indicate a potential for adverse ecological effects (depending upon factors such as freguency of
detection, degree of exceedance, etc.), thus indicating a need for more site-specific ecological
investigations, such as toxicity testing. Maximum sediment exposure point concentrations for
each contaminant of concern were compared to screening values for a particular contaminant of
concern. Surface water was not sampled during the RI, so no current exposure to surface water
was evaluated.

6.7.4.2 Exposure to Future Surface Water (Ground Water Surrogate)

Future surface water was evaluated by comparing maximum ground water concentrations with EPA
Region 4 Waste Management Division fresh water screening concentrations (chronic). This is due
to the potential role of the ground water underlying the site to move contaminants into nearby
wetland and deepwater habitats. Exceedance of these screening levels might indicate a potential
for adverse ecological effects (depending upon factors such as freguency of detection, degree of
exceedance, etc.), thus indicating a need for more site-specific ecological investigations, such
as toxicity testing. Maximum ground water exposure point concentrations for each contaminant of
concern were compared to screening values for a particular contaminant of concern.

6.7.4.3 Exposure to Future Sediment (Soft Surrogate)

Future sediments were evaluated by comparing maximum soil concentrations with EPA Region 4 Waste
Management Division sediment screening levels. This is due to the potential for soils to
eventually become sediments within the nearby wetland habitat. Exceedance of these screening
levels might indicate a potential for adverse ecological effects (depending upon factors such as
freguency of detection, degree of exceedance, etc.), thus indicating a need for more
site-specific ecological investigations, such as toxicity testing. Maximum soil exposure point
concentrations for each contaminant of concern were compared to screening values for a
particular
contaminant of concern.

6.7.5 Risk Characterization

6.7.5.1 Exposure to Current Sediments

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 wetland and aguatic
life. A number of contaminants in sediment exceeded regional screening values. Screening
criteria were not available for all detected contaminants; therefore, NOAA ERL values were
substituted. Despite the absence of some criteria, the results show that effects already may
have occurred to aguatic life inhabiting the wetlands. The site-related chemicals which
currently contribute the most to the increased risk in sediments are ODD, DDE, DDT, dieldrin,
and chlordane.

6.7.5.2 Exposure to Future Surface Water (Ground Water Surrogate)

Comparison of the concentrations of contaminants of concern in future surface water (ground
water surrogate) with regional screening values was used to assess the likelihood of adverse
effects of future surface water to wetland and aguatic life. A number of contaminants in future
surface water exceeded screening values. 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 severe
effects may occur if ground water contaminants migrate to surface water at current levels. The
site-related chemicals which may contribute the most to the increased risk in surface water are
-------
DDD, aluminum, dieldrin, and endrin.

6.7.5.3 Exposure to Future Sediment (Soil Surrogate)

Comparison of the concentrations of contaminants of concern in future sediment (soil surrogate)
with regional screening values was used to assess he likelihood of adverse effects of future
sediment to wetland and aguatic life. A significant number of contaminants in future sediment
exceeded screening values. Screening criteria were not available for all detected contaminants;
therefore, NOAA ERL values were substituted. Despite the absence of some criteria, the results
how that effects may occur if soil contaminants continue to migrate to sediment at current
levels. The site-related chemicals which may contribute the most to the increased risk in
sediments are DDD, DDE, DDT, dieldrin, and chlordane. Also, there is an indication of possible
adverse biological effects through food chain exposure to 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 aguatic 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 effect.

• Sediments constitute complex chemical mixtures and it is possible that antagonistic
or synergistic toxidty effects may occur between any of the chemical constituents.
These factors were not accounted for.

• Future surface water and sediment concentrations do not account for degradation and
attenuation of contaminant concentrations.

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 Helena Chemical 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 1x10-4 to 1x10-6 and maximum 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 7.1.4 and Table 7-1.

7.1.1 Beneficial Land Use

The Site currently is 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 provide assurance the Site use will remain industrial.
-------
7.1.2 Human Health Risk

If the carcinogenic risk of individual contaminants in soils/sediments are reduced to 1x10-5,
the cumulative residual risk remaining after remediation totals slightly less than 1x10-4. If
the carcinogenic risk of individual contaminants are reduced to 1x10-6, the cumulative residual
risk remaining after remediation total slightly less than 1x10-5. EPA's acceptable carcinogenic
risk range is between 1x10-6 and 1x10-4. FDEP only considers individual contaminant risk less
than 1 x 10-6 accepl able. EPA considers it appropriate to reduce individual contaminant
concentrations so that each individual contaminant's carcinogenic risk is egual to or less than
1x10-6 and the cumulative residual risk is equal to or less than 1x10-5.

For non-carcinogenic risk in soils/sediments, contaminant levels which yield a HQ for an
individual contaminant egual-to 1 is generally considered acceptable unless there is reason to
believe that a large number of contaminants affect the same target organ.

Ground water is required to meet drinking water standards on and offsite 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, concentrations based on health effects were considered. Bioassay tests may
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 soil and ground water
to levels which protect human health. Future sediment and surface water contaminant levels will
be lower than current levels and will be more protective.
-------
TABLE 7-1: REMEDIATION GOALS
Chemical of
Concern

SURFACE SOIL/
SEDIMENT
Aldrin
alpha-BHC
DDD
DDE
DDT
Chlordane
Dieldrin
Heptachlor
Heptachlor Epox
Toxaphene
GROUND
WATER
4, 4 '-DDT
Aldrin
alpha-BHC
beta-BHC
gamma-BHC
Dieldrin
Endosulfan I
Endosulfan II
Xylene (Total)
Practical
Quantitation
Levels (1)
(mg/kg)

NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
(ug/L)

0.1
0.05
0.05
0.1
0.05
0.1
0.05
0.05
4
Federal or State
ARARs
or TBCs

NA
NA
NA
NA
NA
NA
NA
NA
NA
NA

0.1 4)
0.05 4)
0.05 4)
0.1 4)
0.2 3)
0.1 4)
0.35 4)
0.35 4)
20 5)
Health-Based
Remedial Goal
Concentrations(2)
0.18
0.47
12.6
8.9
8.9
2.3
0.19
0.67
0.34
2.76
Ground Water
Protection
Remedial Goals
Selected
Remediation
Goal
0.3
0.006
0.02
0.06
10
0.007
2
2
NR
0.1
0.004
NR
NR
6
NR
0.10
NR
NR
NR
0.18
0.47
12.6
8.9
8.9
2.3
0.39
0.67
0.34
2.76
NR
NR
NR
NR
NR
NR
NR
NR
NR
0.3 4)
0.05
0.05
0.1
0.2
0.1
2
2
20
-------
NA - Not Available
NR - Not Required

NOTES:

1) 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.
2) Health based concentrations are based on 1x10-6 carcinoqenic risk or a HQ of 1 for non-carcinoqens.
3) Value based on a Federal and State Primary Maximum Contaminant Level (MCL).
4) Value based on Florida Groundwater Guidance Concentration (To Be Considered (TBCs).
5) Value based on a State Secondary Maximum Contaminant Level (MCL).
6) FDEP's quidance for qround water is more strinqent for 4,4-DDT than the site-specific health-based remediation qoal
selected. Attainment of a more strinqent level may be necessary to obtain FDEP's concurrence with deletion of this
Site from the National Priorities List in the future.
-------
7.1.4 Remediation Goals

Soil and ground water RGs for protection of htunan health are presented in Table 7-1. Soil RGs
apply to soils and sediments 0 to 2 feet bis and are reflective of concentrations which will
leave, in site soils, contamination at the 1x10-6 individual contaminant carcinogenic risk
levels. Remediation goals were not established for metals and volatiles in soils at the site.
Soils which contain high levels of metals and volatiles are within the areas where soils are
being excavated to remove pesticides; therefore additional goals are not reguired.

Ground water RGs are reflective of concentrations which will leave, in ground water,
contamination at the 1x10-6 individual contaminant risk levels individual contaminant HQ of 1,
or the instrument guantitation limit. In addition to ground water RGs in Table 7-1, the pH in
ground water near the old sulfur pit needs to be increased and stabilized. A pH between 6 and
8.5 is recommended. If high levels of metals remain in ground water after the pH is stabilized,
additional RGs for metals may be reguired.

7.2 Remedial Alternatives

7.2.1 Overview

The FS report included an evaluation of six cleanup methods for contamination in soil, sediment,
and ground water. These alternatives represent the range of remedial actions considered
appropriate for the Site. As reguired by CERCLA, a no further action alternative was evaluated
to serve as a basis for comparison with the other active cleanup methods. Potential Applicable
or Relevant and Appropriate Reguirements (ARARs) are summarized in Section 8 for these
alternatives. The six alternatives that have been identitied for evaluation are listed below:

• Alternative 1: No Action

• Alternative 2: Soft And Shallow Ground Water Containment By Vertical Barriers
And A Surface Cap

• Alternative 3: Biologically Treat Soil Onsite; Contain, Extract, Treat and Dispose
of Ground Water

• Alternative 4: Biologically treat Soil Onsite; Allow Natural Attenuation of
Contamination in Shallow Ground Water

• Alternative 5: Treat Contaminated Soil by Low Temperature Thermal Desorption
(LTTD); Contain, Treat and Dispose of Ground Water

• Alternative 6: Treat Contaminated Soil by LTTD; Natural Attenuation of Ground Water

7.2.2 Alternative 1: No Action

CERCLA reguires that EPA consider the No Action alternative to serve as a basis against which
other alternatives can be compared. Under the no action alternative, the Site would be left as
is. Periodic monitoring of Site ground water would be continued for at least 30 years, at a
present worth cost of approximately $234,000.

7.2.3 Alternative 2: Contain Contaminated Soil And Ground Water With Vertical Barriers and
Surface Cap

Alternative 2 consists of the following remedial actions:
-------
• Implement institutional controls (i.e., fencing and deed restrictions);

• Install a vertical barrier (such as slurry walls, high density polyethylene
sheeting, or sheet piling) to reduce horizontal transport of contaminants in ground
water from the contaminated soil zone; and
• Install a surface cap consisting of asphalt, concrete, clay, or synthetic material
to minimize percolation of precipitation.

This alternative provides an option of containment that reduces short-term risk with moderate to
high capital expenditures and low operating and maintenance costs while protecting public health
and the environment in the long term. Alternative 2 is expected to reguire 1 year to reduce
soil exposure and over 31 years to monitor ground water. The capital and operation and
maintenance (O&M) costs are estimated at $926,000 and $665,000, respectively. The total present
worth cost is approximately $1.6 million.

7.2.4 Alternative 3: Biologically Treat Soil Onsite; Contain Extract, Treat and Dispose of
Ground Water

Alternative 3 consists of the following remedial actions:

• Implement institutional controls (i.e., fencing and deed restrictions);

• Demolish tank farm pads east of the liguid processing building and dispose of
the debris offsite (the tanks may be recycled);

• Excavate material from former sulfur pit and dispose of offsite;

• Neutralize soils in-place if located in areas where sulfur is present but
inaccessible;

• Excavate contaminated surface soils and sediments (0-2 feet bis) above soil RGs;

• Biologically treat contaminated surface soils and sediments;

• Place treated soils back onsite;

• Extract contaminated ground water and treat to meet surface water discharge
standards; and

• Discharge treated ground water to the Tampa Bypass Canal under an NPDES permit.

This alternative is based on the growing technical evidence that reductive dechlorination of
organic compounds under anaerobic conditions can be used to detoxify a wide range of chlorinated
aromatic compounds. The treatment of excavated Site soil would be primarily seguenced anaerobic
treatment, especially for soil contaminated with toxaphene and DDT. This treatment would be
land-based, with shallow berms and liners to prevent migration and management of water during
remediation.

Ground water extraction under this alternative is proposed strictly for purposes of assuring
that the bulk of surficial ground water contaminant mass is contained at the source area.
Restoration timeframe, although difficult to predict reliably, can be expected to be very long,
and may not be significantly accelerated by ground water extraction. The ground water
extraction system envisioned includes several individual wells pumped to an on-site treatment
unit and discharged to surface water (i.e. Tampa Bypass Canal). This extracted ground water
-------
would be treated by any
number of physical/chemical means, such as carbon adsorption. A modification to the facilities
current National Pollutant Discharge Elimination system (NPDES) permit will be required for
surface water discharge. Surface water discharge requirements for the contaminants of concern
need to be determined during design.

Pending more complete determination of aquifer characteristics and plume delineation during
Remedial Design, extraction wells will be operated to contain the highest concentrations of
mobile pesticides, organic solvent and acidity in onsite shallow ground water. Restoration of
shallow ground water quality is the goal, but may be inhibited by the low mobility of
pesticides. The Floridan Aquifer beneath the site will be monitored as part of this
alternative.

The tank farm pads east of the liquid processing and packaging storage building will be
demolished, and underlying contaminated soil excavated. Demolition debris will be tested for
pesticides, and properly disposed offsite. Tanks that are removed as part of the demolition
will be recycled, depending on the condition of the tank and success of decontamination.

Surface soil would be excavated to a depth of 2 feet based on protection of human health.
Excavations would be from around formulation and storage buildings, former tank farm areas, and
the former sulfur pit area (See Figure 7-1 and 7-2). Material from the former sulfur pit will
be disposed offsite, or neutralized to prevent it from further affecting acidity of the ground
water and solubilizing netals. Where sulfur is present but inaccessible (for instance, under
buildings), in-place neutralization will be employed (e.g., injection of alkaline solutions).

Capital and O&M costs are estimated at $1,100,000 and $1,289,000, respectively. The ground
water extraction operation is estimated over a 30 year period. The total estimated present
worth cost, with ground water extraction operation for over 30 years, is approximately $ 2.4
million.

7.2.5 Alternative 4: Biologically Treat Soil Onsite; Allow Natural Attenuation of
Contamination in Shallow Ground Water

Alternative 4 consists of the following remedial actions:

• Implement institutional controls (i.e., fencing and deed

• Demolish tank farm pads east of the liquid processing building and dispose of
the debris offsite (the tanks may be recycled);

• Excavate material from former sulfur pit and dispose of offsite;

• Neutralize soils in-place if located in areas where sulfur is present but
inaccessible;

• Excavate contaminated surface soils and sediment (0-2 feet bis) above soil RGs;

• Biologically treat Contaminated soils and sediments; and

• Place treated soils back onsite.

Alternative 4 calls for natural attenuation of contaminant concentrations in ground water. In
natural attenuation, subsurface processes are allowed to reduce contaminants through dilution,
biodegradation, adsorption, chemical reactions with subsurface material. Natural attenuation
-------
was considered ts an alternative to treatment to minimize cost. It requires a comprehensive
ground water monitoring program, and the development of a Site-specific fate and transport
model, to assure drinking water standards are achieved and the impact to the Floridan aguifer is
limited. Modeling performed during the FS, showed natural attentuation would take over 30 years
(and up to 100 years) for contamination to reach performance standards by natural attenuation.

Capital and O&M costs are estimated at $ 994,000 and $ 847,000. The ground water extraction
operation is estimated for over a 30 year period. The total present worth cost is approximately
$1.8 million.

7.2.6 Alternative 5: Treat Conhuninated Soil by Low Temperature Thermal Desorption (LTTD);
Contain, Treat and Dispose of Ground Water

Alternative 5 consists of the following remedial actions:

• Implement institutional controls (i.e., fencing and deed restrictions);

• Demolish tank farm pads east of the liguid processing building and dispose of
the debris offsite (the tanks may be recyded);

• Excavate material from former sulfur pit and dispose of offsite;

• Neutralize soils in-place if located in areas where sulfur is present but
inaccessible;

• Excavate contaminated surface soils and sediments (0-2 feet bis) above RGs;

• Treat contaminated surface soils and sediments using LTTD;

• Place treated soils back onsite;

• Extract contaminated ground water and treat to meet surface water discharge
standards; and

• Discharge treated ground water to the Tampa Bypass Canal under an NPDES permit.

Alternative 5 differs from Alternative 3 in that contaminated soil is treated by thermal
desorption in a rotary dryer, or by indirect heated vacuum desorber. Thermal desorption is a
commercially available and proven technology for decontamination of pesticide-tainted soil and
debris. Essentially, the temperature of soil is raised only to the level needed to vaporize
organic contaminants from the soil. These vapors then are collected in an off-gas system for
destruction or disposal. As long as soil containing heavy concentrations of elemental sulfur is
separated or blended, Site conditions pose no complication to the use of the technology. The
indirect heated vacuum desorber is a new modification of this proven technology and should be
easier to implement due to its mobility and smaller space requirements.

The treatment of ground water will be handled by any number of physical/chemical means, such as
carbon adsorption, which has been shown to effective in the removal of low concentrations of
pesticides and organic solvents from ground water. This treatment will assure that the bulk of
surficial ground water contaminant mass is contained at the source area.
-------
Capital costs are estimated to range from $ 832,000 to $1,756,000, depending on the type of LTTD
selected. O&M costs are estimated to range fron $ 2,827,000 to $3,555,000, depending on the
type of LTTD selected. Total present worth cost, with ground water extraction over a period of
30 years, is estimated to range from $ 3,659,000 to $ 5,311,000.

7.2.7 Alternative 6: Treat Contaminated Soil by LTTD; Natural Attenuation of Ground Water

Alternative 6 consists of the following remedial actions:

• Implement institutional controls (i.e., fencing and deed restrictions);

• Demolish tank farm pads east of the liguid processing building and dispose of the
debris offsite (the tanks may be recycled);

• Excavate material from former sulfur pit and dispose of offsite;

• Neutralize soils in-place if located in areas where sulfur is present but
inaccessible;

• Excavate contaminated surface soils (0-2 feet) above RGs;

• Treat contaminated surface soils using LTTD; and

• Place treated soils back onsite.

Alternative 6 combines the soil treatment method of Alternative 5 (LTTD) with using natural
attenuation for shallow ground water contamination, as described for Alternative 4. Soil
cleanup levels are expected to reguire less than 1 year to achieve. Ground water cleanup levels
are expected to reguire over 30 years (and up to 100 years) to achieve.

Capital costs are estimated to range from $ 726,000 to $1,650,000, depending on the type of LTTD
selected. O&M costs are estimated to range fron $ 2,385,000 to $ 3,113,000, depending on the
type of LTTD selected. Total present worth cost, with natural attenuation over a period of 30
years (and up to 100 years), is estimated to range from $ 3,111,000 to $ 4,763,000.

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 § 00.430. The major objective of the Feasibility Study (FS) was to
develop, screen, and evaluate alternatives for the remediation of the HCC Site. A wide variety
of alternatives and technologies were identified as candidates to remediate the contamination at
the HCC 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 remedial alternative was selected from the screening process using the following
nine evaluation criteria:

• overall protection of human health and the environment;

• compliance with applicable or relevant and appropriate reguirements (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 ant 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 HCC
Site under each of the criteria. A comparison is made between each of the alternatives for
achievement of a specific criterion.

8.2 Threshold Criteria

8.2.1 Overall Protection of Human Health and the Environment

With the exception of the No Action alternative (Alternative 1), all of the alternatives would
provide protection for human health and the environment to some degree. The remaining
alternatives achieve protectiveness through the application of engineering controls, or a
combination of controls and treatment. Since Alternative 1 did not pass this threshold criteria
for providing protection of human health and the environment, it was eliminated from further
consideration.

8.2.2 Compliance With ARARs

The remedial action for the HCC 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 reguirements are those standards, criteria or limitations promulgated under federal
-------
or state law that specially 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 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 5 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 HCC 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 HCC Site.

Chemical-specific ARARs are specific numerical quantity restrictions on individually-listed
contaminants in specific media. Examples of chemical-specific ARARs include the MCLs specified
under the Safe Drinking Water Act as well as the ambient water quality criteria that are
enumerated under the 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 list potential chemical-specific ARARs and TBCs for the HCC Site.

Alternatives 2 through 6 would meet or exceed all chemical-specific ARARs and would be designed
to meet location- and action-specific ARAR 5. Restoration of the surficial aquifer is expected
to be achieved eventually through natural attenuation of pesticide constituents, whether or not
ground water from the surficial aquifer is extracted. For alternatives where excavation and
offsite disposal of sulfur-containing soil is envisioned, transportation and disposal will
comply with RCRA.

8.3 Primary Balancing Criteria

8.3.1 Long-Term Effectiveness and Permanence

Alternative 2 relies strictly on engineered containment of contaminated soils and ground water.
Alternative 2 would be effective and protective as long as the integrity of the cap and slurry
wall were maintained. Alternatives 3 through 6 include excavation and irreversible treatment of
pesticide-contaminated soil, which is the primary source of risk by direct exposure or migration
to ground water. Alternatives 3 and 5 actively address ground water contamination (i.e., through
pumping and treating ground water), where as, Alternatives 4 and 6 passively address ground
water contamination (i.e., through natural attenuation). Ground water remediation, whether
active or passive, will be effective and permanent.

8.3.2 Reduction of Toxicity, Mobility, or Volume Through Treatment

Alternative 2 does not call for treatment. Alternatives 3 through 6 rely on treatment of
pesticide and sulfur-containing soils. Alternatives 3 and 5 rely on treatment of contaminated
-------
ground water to prevent offsite migration and further degradation of the Floridan aguifer.
Alternatives 4 and 6 rely on natural attenuation rather than treatment to restore ground water.
-------
Re qui rement s
RCRA Location Requirements
40 CFR 264.18(c)
Table 8-1: Potential Location Specific ARARs and TBCs

Status Requirement Synopsis

Federal and State Requirements

Relevant and Establish minimum requirements
Appropriate for desiqn, construction, and
operation of a facility where
hazardous waste will be located.
Application to the RI/FS
Treatment, disposal, and storaqe
of hazardous materials may take
place durinq remediation of the
site.
National Historic Preservation
or
Act of 1966 16 U.S.C. 470 et
seq. 36 CFR Part 800

Endanqered Species Act
16 U.S.C. 1531 et seq.
50 CFR Part 402
Not Applicable
Applicable
Requires that the action not

Affect or harm reqistered historic
places or historic landmarks.

Action must avoid jeopardizinq
the continued existence of Isited
endanqered or threatened species
or modification of their habitat.
Not reqistered historic places

historic landmarks are onsite or
nearby.

Endanqered species may be
present in the vicinity of the
HCC Tampa site.
Executive Order 11990
Wetlands Protection Policy

Clean Air Act National
Ambient Air Quality Standards
40 CFR Part 50
Florida Rules on Permits Title
62 Chapter 62-4
Relevant and Sets forth policy for the
Appropriate protection of wetlands.

Applicable Establish emissions standards to
protect public health and public
welfare. These standards are
national limitations on ambient
air intended to protect health
and wleqare.

Relevant and Establish requirements and
Appropriate procedures for all permittinq
required by the FDEP, and
define anti-deqradation
requirements.
There is a wetland east-
northeast of the HCC site.

Hillsborouqh County is a non-
attainment area for ozone and
total suspended particulates.
Requirements may apply to site
dependinq upon remedial
action and discharqe options
selected. Permits are not
required for onsite actions.
-------
Florida Ambient Air Quality Applicable
Standards
Title 62 Chapter 62-2

Florida Water Quality Applicable
Standards
Title 62 Chapters 62-3

Florida Ground water Classes, Applicable
Standards, and Exemptions
Titles 62 Chapter 62-520

Florida Surface Water Applicable
Standards
Title 62 Chapters 62-301 and
62-302
Establish ambient air quality
standards and ambient test
methods.

Establish minimum water quality
criteria for qround water.
Establish water classes, standards
and exemptions for qround
water.

Establish water quality standards
for all waters of the state.
Remedial action may include
technoloqies which have air
emissions.

Remedial objectives require
remediation of the surficial and
Floridan aquifers.

Remedial actions may include
classinq qround water.
Remedial objectives require
protection of surficial water,
Remedial actions may impact
surficial water bodies.
Florida Industrial Wastewater Applicable
Facilities Requlations
discharqed
Title 62 Chapter 62-660
Florida Underqround Injection Applicable
Control Requlations
Establish effluent limitations and
minimum treatment

requirements for industrial
facilities; establishes water
quality criteria.

Establish construction standards,
permittinq procedures, and
operatinq requirements for
underqround injection wells.
Remedial action may require
treated effluent to be

as per state and federal
requlations.
Remedial actions may include
underqround injection as a
disposal option for treated
effluent.
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Re qui rement s
Table 8-2: Potential Action Specific ARARs and TBCs

Status Requirement Synopsis

Federal and State Requirements
RCRA Identification of Hazardous Applicable
Waste
40 CFR 261
RCRA Identification Hazardous
Waste
40 CFR 261.33 (d)
for
Applicable
Criteria for identifyinq those
solid wastes subject to
requlation as hazardous waste
under RCRA

Defines a material as hazardous
waste if it is a residue or
contaminated soil, water or

other debris resultinq from the
cleanup of a spill into or on
nay land or water any
or manufacturinq chemical product
intermediate havinq the qeneric
name listed in the section.
Application to the RI/FS
Suspected hazardous wastes at
should be identified as
RCRA hazardou waste for offsite
disposal or treatment.

Soil and qround water
contamination at HCC may be
identified as hazardous waste

disposal or treatment.
RCRA Facility Standards
RCRA Manifest System,
Recordkeepinq, and Reportinq
offsite
40 CFR 264 Subpart E
site
Relevant and Establish minimum standards
Appropriate for the acceptable manaqement
of RCRA hazardous wastes.
include preparedness and
prevention measure, qeneral
facility standards, and
continqency and emerqency
procedures.

Relevant and Establish the rules and
Appropriate recordkeepinq requirements for

offsite transportation of RCRA
hazardous materials for
treatment and/or disposal.
These standards may be relevant
and appropriate to HCC if
treatment, stranqe, and/or
disposal of RCRA hazardous
wastes occurs onsite durinq
remediation.
These procedures may be relevant
and appropriate to HCC if

transportation of RCRA
hazardous for treatment and/or
disposal is necessary durinq

remedial.
-------
RCRA Ground Water Monitoring
Requirements
40 CFR 264 Subpart F
Not Applicable
Establish minimum
requirements for qround water
monitorinq and protection
standards for RCRA facilities.
All onsite remedial actions are
qoverned by CERCLA.
RCRA Closure and Post-closure
Requirements
40 CFR 264 Subpart G
Not Applicable
Establish minumum
requirements for closure and
post-closure care of a RCRA
facility enqaqinq in treatment,
storaqe, and/or disposal of
hazardous wastes. Closure
requirements include in-place
wastes and remediated areas.
All onsite remedial action are
qoverned by CERCLA.
RCRA Storaqe Requirements Relevant and
40 CFR Subparts I, J, and L Appropriate
RCRA Landfill Requirements Relevant and
40 CFR 264 Subpart M Appropriate
Establish minimum
requirements for the storaqe of
hazardous wastes.
Establish minimum
requirements for the desiqn
and construction, operation and
maintenance, monitorinq and
inspection, closure and post
closure care for a hazardous
waste landfill.
These requirements may be
relevant and appropriate bacause
RCRA hazardous waste may be
stored onsite prior to offsite
disposal or onsite treatment.

These requirements may be
relevant and appropriate if
remedial actions include RCRA
hazardous waste to be landfill
onsite.
RCRA Treatment Requirements
40 CFR Subparts 0 and X
onsite
Relevant and Establish minimum
Appropriate requirements for the permit

approval, operation, and
standards for incineration and
other treatment for hazardous
wastes.
Treatment standards may be
relevant and appropriate to

remediation includinq
incineration and/or treatment of
hazardous and/or treatment of
-------
Re qui rement s
RCRA Land Disposal Restrictions
40 CFR 268

date
Clean Air Act National Ambient
Air Quality Standards
40 CFR Part 50
Table 8-2: Potential Action Specific ARARs and TBCs

Status Requirement Synopsis

Federal and State Requirements
Applicable
Applicable
Clean Water Act Discharqe
Limitations NPDES Permit 40 CFR
122,125,129,136 Pretreatment
Standards
40 CFR 403.5, 40 CFR 455.20
Applicable
Certain classes of waste are
restricted from land disposal
without acceptable treatment.
Establish standards for
emissions to protect public
health and public welfare.
These standards are national
limitations on ambient air
intended to protect health and
welfare.

Prohibit unpermitted discharqe
of any pollutant or combination
of pollutants to waters of the
U.S. from any point source.
Standards and limitations are

established for these discharqes
and discharqes to Publicly
Owned Treatment Works
(POTWs).
Application to the RI/FS
Removal of soil from HCC for
land disposal may triqqer the
requlation after its effective

for CERCLA wastes on 5/8/93.

Hillsborouqh County is a non-
attainment area for ozone and
total suspended particulates.
Remedial actions may include the
discharqe of treated qround
water, runoff, or other flows to
surface water or publicly owned
treatment facility.
-------
Safe Drinking Water Act
Underground Injection control
Program
site
40 CFR 144
Applicable
Regulate the use of five classes
of underground injection wells
for disposal of hazardous

substances.
Would be relevant and
appropriate if injection well
technology is used as apart of

remediation.
Department of Transportation
Rules for the Transport of
of
Hazardous Substances
49 CFR Parts 107 and 171-179
Applicable
Regulate the labeling,
packaging, placarding, and

transportation of solid and
hazardous wastes offsite.
Remedial actions may include the
offsite transport and disposal

solid and hazardous wastes.
Florida Air Pollution Rules Title Applicable
62 Chapter 62-2
Florida Rules on Permits Title 61 Relevant and
Chapter 62-4 Appropriate
Florida Ambient Air Quality Applicable
Standards
Title 62 Chapter 62-2

Florida Water Quality Standards Applicable
Title 62 Chapter 62-2
Establish emission standards,
emissions rates, baseline areas,
and source classifications for
protection of health and
welfare. Identifies new source
reguirement, test and analysis
methods.

Establish reguirements and
procedures for all permitting
reguired by the FDEP and
define anit-degradation
reguirements.

Establish ambient air guality
standards and ambient test
methods.

Establish minimum water
guality criteria for ground
water.
Remedial actions may include
technologies that have air
emissions.
Reguirements may apply to site
depending upon remedial actions
and discharge options selected.
Permits are not reguired for
onsite actions.

Remedial actions may include
technologies which have are
emissions.

Remedial objectives reguire
remediation of the surficial and
Floridan aguifers.
-------
Florida Ground Water Classes, Applicable Establish water classes, Remedial actions may include
Standards, and Exemptions standards, and exemptions for classing ground water.
Title 62 Chapter 62-520 ground water.

Florida Surface Water Standards Applicable Establish water guality Remedial objective reguire
Title 62 Chapter 62-301 and 62- standards for all waters of the protection of surficial water.
302 state. Remedial actions may impact
surficial water bodies.

Florida Stormwater Discharge Applicable Establish design and Remedial actions may impact
Regulations Title 62 Chapter 62.25 performance standards and stormwater discharge patterns at
permit reguirements for HCC.
stormwater discharge facilities.
-------
Re qui rement s
Table 8-2: Potential Action Specific ARARs and TBCs

Status Requirement Synopsis

Federal and State Requirements
Florida Drinkinq Water Standards Applicable
Title 62 Chapter 62-550
Florida Resource and Recovery
and Manaqement Requlations
Title 62 Chapter 62-7
Applicable
Establish MCLs for drinkinq
water. Establishes secondary
requirements.
Establish quidelines for
resource recovery proqrams as
well as hazardous waste site
disposal and monitorinq
criteria.
Application to the RI/FS
Remedial objectives require
restoration of the surficial and
Floridan aquifers to drinkinq
water status.

If hazardous wastes or other
wastes are disposed of onsite,
these requlations would become
applicable.
Florida Hazardous Waste Rules
Title 62 Chapter 62-730
Applicable
Florida Hazardous Substances
Release Notification Rules
Title 62 Chapter 62-150
Applicable
Establish standards for
qenerators and transporters of
hazardous wastes, and owners
and operators of hazardous
waste facilities. Outlines
permittinq requirements.

Establish notification
requirements in the event of a
hazardous substance release.
Applicable if remedial actions
qenerate and/or transport
hazardous wastes.
May apply in the event of a
hazardous substance release in
conjunction with remedial
activities.
Florida Underqround Injection Relevant
Control Requlations Appropriate
Title 62 Chapter 62-28
Florida Rules on Hazardous Applicable
Waste Warninq Siqns
Establish construction
standards, permittinq
procedures, and operatinq
requirements for underqround

Establish standard warninq
messaqes and specifications for
siqns used at hazardous waste
sites.
Remediation may include
underqround injection as a
disposal option for treated
effluent.

Remediation systems may require
siqns for public notification.
Appropriate siqns are located on
the site.
-------
Table 8-3: Potential Chemical-Specific ARARs and TBCs
Re qui rement s
RCRA Maximum
Concentration Limits 40 CFR
264 Subpart F
Status
Requirement Synopsis
Safe Drinkinq Water Act
MCLs
of
40 CFR 141.11-141.16
Clean Water Act Federal
Water Quality Criteria 51
bodies
Federal Reqister 43665
Federal and State Requirements

Not Applicable Maximum Concentration Limits
have been established for 14
toxic compounds under RCRA
qround water protection
standards. A compliance
monitorinq proqram is
included for RCRA facilities.

Relevant and MCLs have been set for toxic
Appropriate compounds as enforceable

standards for public drinkinq
water systems. SMCLs are
unforceable qoals requlatinq
the aesthetic quality of drinkinq
water.

Relevant and Effluent limitations must meet
Best Achievable Technoloqy

(BAT) qoals. Water Quality
Criteria for ambient water
quality are provided for toxic
chemicals.
Application to the RI/FS
HCC Tampa site is not a RCRA
site.
The surficial and Floridan Aquifer
are actual and potential sources

drinkinq water.
Any remedial requirinq
discharqe to surface water

will have Ambient Water Quality
Criteria (AWQCs) as a potential
qoal.
-------
Clean Air Act National
Emission Standards for
Hazardous Air Pollutants
(HAPs)
40 CFR 61

Clean Air Act National
Ambient Air Quality
total
Standards 40 CFR Part 50
Relevant and Establish emissions standards,
Appropriate monitoring and testing
reguirements, and reporting
reguirements for eight
pollutants in air emissions.

Applicable Establish emissions standards
to protect public health and

public welfare. These
standards are national
limitations on ambient air
intended to protect health and
welfare.
No HAPS have been identified for
HCC Tampa site.
Hillsborough County is non-
attainment area for ozone and

suspended particulate; thus,
constraints on VOC emission will
apply.
Clean Air Act New Source
Performance Standards 40
CFR Part 60
Relevant and Establish new source
Appropriate performance standards to
ensure that new stationary
sources reduce emissions to a
minimum. These standards are
for sources that cause or
contribute to air pollution that
may endanger public health or
welfare.
Remedial actions may include
technologies which have air
emissions.
Florida Air Pollution Rules
Title 62 Chapter 62-2
Applicable
Establish emission standards,
emissions rates, baseline areas,
and source classifications for
protection of health and
welfare.
Remedial actions may include
technologies that have air
emissions.
-------
Florida Rules Permits
Title 62 Chapter 62-4
onsite
Florida Ambient Air Quality
Standards
Title 62 Chapter 62-2

Florida Water Quality
Standards
aquifer.
Title 62 Chapters 62-3
Relevant and
Appropriate
Applicable
Applicable
Establish requirements and
procedures for all permittinq
required by FDEP and identify
anti-deqradation requirements.
Establish ambient air quality
standards and ambient test
methods.

Establish minimum water
quality criteria for qround

water.
Requirements may apply to site
dependinq upon remedial action
and discharqe options selected.
Permit are not required for

response action.

Remedial actions may include
technoloqies which have air
emissions.

Remedial objectives require
remediation of the surficial
-------
Re qui rement s
Florida Ground water
Classes, Standards, and
Exemptions

Florida Surface Water
Standards
Title 62 Chapters 62-301 and
62-302

Florida Drinking Water
Standards
to
Title 62 Chapter 62-550
Table 8-3: Potential Chemical-Specific ARARs and TBCs

Status Requirement Synopsis

Federal and State Requirements
Applicable
Applicable
Applicable
Establish water classes,
standards and exemptions for
qround water.

Establish water quality
standards for all waters of the
state.
Establish MCLs for drinkinq
water. Establish secondary

requirements for drinkinq
water.
Application to the RI/FS
Actions may include classinq
qround water and establishinq
standards.

Remedial objectives require
protection of surface water.
Remedial actions may impact
surface water bodies.

Remedial objectives require
restoration of surficial aquifer

drinkinq water standards.
-------
contaminated ground water to prevent offsite migration and further degradation of the Floridan
aguifer. Alternatives 4 and 6 rely on natural attenuation rather than treatment to restore
ground water.

8.3.3 Short-Term Effectiveness

Risks to the community and Site workers posed by the implementation of all alternatives are
minimal. Engineering controls can be expected to control emissions to air and surface water.
The discharge of contaminated shallow ground water to the Tampa Bypass Canal is projected not to
cause exceedances of Ambient Water Quality Criteria. Time for restoration of the surficial
ground water guality to MCLs is very long because of the nature of the constituents and their
release to ground water. Alternatives 3 and 5 provide more control over contaminated ground
water than Alternatives 4 and 6 by keeping contaminated ground water from migrating offsite or
to the Floridan aguifer.

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

Beyond the technical and scheduling difficulties associated non-intrusive remedy construction at
a facility with ongoing operations, all active alternatives are easily undertaken. Pilot-scale
treatability testing will be reguired for biological treatment to assure the same level of
reliability in achieving soil treatment goals that LTTD provides.

8.3.5 Cost

The biological alternatives represent the least costly treatment approach, not significantly
more costly than the containment measures of Alternative 2. The operation and maintenance cost
of ground water extraction, treatment, and disposal under Alternatives 3 and 5, is partially
offset by the increased monitoring cost to document natural attenuation of Site constituents in
surficial ground water (Alternatives 4 and 6).

A summary of the present worth costs which includes the capital as well as the operation and
maintenance cost for each of the alternatives presented in Table 0-4. 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 cleanup costs to meet performance standards are
within the range of the FS cost estimate (+50% to-30% accuracy). Therefore, the cost of each
alternative should be similar to the cost estimates presented in the FS.

8.4 Modifying Criteria

8.4.1 State Acceptance

The State of Florida, as represented by the Florida Departlnent of Environmental Protection
(FDEP), has been the support agency during the Remedial Investigation and Feasibility Study
(RI/FS) process for the HCC 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 Administrative Record. Although FDEP has not indicated an objection to
the overall approach of the selected remedy, FDEP is unwilling to concur with this ROD because
FDEP disputes the remediation goal selected for 4,4-DDT in ground water.

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.
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TABLE 8-4: COMPARISON OF COSTS

Alternative Present-worth Cost Capital Cost Operation and
Maintenance Cost

1. No-Action $ 234,000 $ 20,000 $ 214,000

2. Soil and Shallow Ground $ 1,591,000 $ 926,000 $ 665,000
Water Containment

3. Biologically Treat Onsite Soil; $ 2,389,000 $ 1,100,000 $1,289,000
Contain, Extract, Treat, &
Dispose of Ground Water

4. Biologically Treat Onsite Soil; $ 1,841,000 $ 994,000 $ 847,000
Natural Attenuation of Ground
Water

5. Treat Onsite Soil with LTTD; $ 3,659,000 to $ 832,000 to $2,827,000 to
Contain, Extract, Treat, & $5,311.000 $ 1,756,000 $ 3,555,000
Dispose of Ground Water

6. Treat Onsite Soil with LTTD; $ 3,111,000 to $ 726,000 to $ 2,385,000 to
Natural Attenuation of Ground $4,763,000 $1,650,000 $3,113,000
Water
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8.5 Comparison of Alternatives

All alternatives, except Alternative 1, provide protection of human health and the environment
and achieve all identified ARARs. With respect to short-term effectiveness and
implementability, Alternatives 2, 3 and 5 are comparable, because they address exposure to soil
and ground water. Alternatives 4 and 6 are equally effective and implementable as Alternatives
3 and 5 for soil, but less effective at addressing short-term exposure to ground water.

The soil treatment components of Alternatives 3 through 6 achieve overall protectiveness and
risk reduction by permanently treating the waste and using the treated materials to prevent
contact with less affected soils beneath the treatment areas. Alternative 2 achieves similar
risk reductions, but does not satisfy the statutory preference for reducing the toxicity and
volume of the waste, although the mobility of Site contaminants would be greatly reduced.
Therefore, Alternatives 3-6 are preferable to Alternative 2 for soil remediation.

Alternatives 3 and 4 (biological treatment) are designed to provide an innovative,
cost-effective and timely remediation tool that will naturally and permanently detoxify
contaminated soil or sediment without adversely influencing its physical character.
Alternatives 5 and 6, treatment of soils by LTTD, would make use of a proven treatment
technology that could be expected to achieve the remedial goals specified in this ROD.

Alternatives 3 and 5 actively remediate ground water using a pump and treat system. Alternatives
4 and 6 passively remediate ground water using natural attenuation. To some extent, the ground
water restoration rate is controlled by natural attenuation processes, whether or not ground
water extraction is undertaken. Alternatives 3 and 5 provide more protection and control over
contaminated ground water by keeping it from migrating offsite and into the Floridan Aguifer.

Alternatives 3 and 5, therefore, are those that best meet the statutory preference for permanent
solutions that reduce the toxicity, mobility and volume of waste materials while using
technologies that can reasonably be expected to a achieve the remedial goals determined to be
protective of human health and the environment, and to achieve ARARs. They also fulfill the
other criteria regarding long- and short-term effectiveness and implementability. The projected
cost for Allernative 3 is significantly less than that for Alternative 5. Given that
Alternative 3 can be implemented at significantly less cost than could Alternative 7,
Alternative 3 is the
preferred alternative.

EPA recognizes, however, that the preferred remedy includes a soil treatment technology
(biological treatment) that is an innovative technology that has not been demonstrated capable
of achieving performance standards specified in Section 9, below. EPA, therefore, will retain
Alternative 5 as a contingency remedy to be implemented should treatability studies of
biological treatment prove that this technology is incapable of achieving the performance
standards for this Site. The only difference between Alternative 3 and Alternative 5 is the
soil treatment technology to be employed. Alternative 5 contains low temperature thermal
desorption (LTTD) as the soil treatment technology.

9.0 SUMMARY OF SEIiECTED 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 alternative 3 (i.e., bioremediation of contaminated soils and
pump and treat of contaminated ground water) for this Site. The selected alternatives for the
Helena Chemical Company Site are consistent with the requirements of Section 121 of CERCLA and
the NCP. Based on the information available at this time, the selected alternative represents
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the best
balance among the criteria used to evaluate remedies. The selected alternative will reduce the
mobility, toxicity, and volume of contaminated soil and ground water at the Site. In addition,
the selected alternative is protective of human health and the environment, will attain all
federal and state ARARs, is cost-effective and utilizes permanent solutions to the maximum
extent practicable. At the completion of this remedy, the residual risk associated with this
Site will fall within the acceptable range mandated by CERCLA and the NCP of 10-6 to 10-4 which
is determined to be protective of human health. The unacceptable level of risk posed to
environmental receptors also will be adeguately addressed. The estimated present worth cost of
Alternative 3 is $ 2.5 million.

Actual or threatened releasesof 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

The major components of source control in the selected remed, (Alternative 3) include:

• Implement institutional controls (i.e., fencing and deed restrictions);

• Demolish tank farm pads east of the liguid processing building and dispose of
the debris offsite (the tanks may be recycled);

• Excavate material from former sulfur pit and dispose of offsite;

• Neutralize soils in-place if located in areas where sulfur is present but
inaccessible;

• Excavate contaminated surface soils and sediments (0-2 feet) above soil RGs;

• Biologically treat contaminated Surface soils and sediments; and

• Place treated soils back onsite.

9.1.2 Performance Standards

The performance standards for soil and sediment remediation are based on protection of human
health, and are listed 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 of the selected remedy (Alternative
3) are as follows:

• 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
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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.

Remediation of the Floridan aguifer may be necessary, depending on the results of monitoring.
Further delineation of contaminants in the Florida aguifer will be reguired as part of this
monitoring effort. If an additional ground water action is reguired to remediate the Floridan
aguifer, this decision document may reguire modification.

9.2.2 Performance Standards

9.2.2.1 Extraction Standards

Ground water will be extracted from the surficial aguifer at a rate to be determined during
remedial design.

9.2.2.2 Treatment Standards

Ground water will be monitored in the Floridan and surficial aguifer until the maximum
concentration levels for ground water in Table 7-1 are attained. EPA considers the
site-specific remediation goals in Table 7,1 to be protective of human health and the
environment as they fall within EPA' s risk range and are based on an EPA approved site-specific
risk assessment. However, on June 2, 1994, FDEP issued guidance suggesting minimum criteria for
ground water which are more stringent than the selected remediation goal for 4,4-DDT.
Attainment of a mote stringent level
may be necessary to obtain FDEP's concurrence with deletion of this Site from the National
Priorities List in the future.

9.2.2.3 Discharge Standards

Discharges from the ground water treatment system shall comply with all ARARs, including, but
not limited to, substantive reguirements of the NPDES permitting program under the Clean Water
Act, 33 U.S.C. § 1251 et seg., 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 reguirements set forth in 40 C.F.R. Part 264
(Subpart F).

9.3 Compliance Testing

Ground 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 9.2.2.2 are being
exceeded at any time after pumping has been discontinued, extraction and treatment of the ground
water will recommence until the Performance Standards once again are achieved. If monitoring of
the surface water indicates contaminant levels are not decreasing, the effectiveness of the
source control component will be re-evaluated.

Compliance testing of the residual soils that have been subjected to treatment will also be
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performed, to insure compliance with the requirements established as performance standards for
the soil treatment technology.

9.4 Contingency Remedy

Should treatability studies demonstrate that the selected remedy described above (biological
treatment), cannot achieve performance standards established for the Site soils, the treatment
technology used for soil remediation at the Site will be low temperature thermal desorption
(LTTD) in lieu of biological treatment. LTTD has been used successfully at other NPL sites with
similar soil contaminants and levels of contamination, and therefore can be expected to
satisfactorily achieve performance standards at this Site.

Using this technology, contaminated soils exceeding performance standards would be treated
on-site by means of low temperature thermal desorption (LTTD). This process involves processing
contaminated soils through a rotary dryer or kiln. The soil mass is heated to a temperature
level that is sufficient to drive the contaminants off of the soil matrix, but not high enough
to actually incinerate or destroy the contaminants. Soil contaminants are volatized from the
solid and purged from the kiln or dryer by means of an inert purge gas. After the purge as
leaves the
desorption unit, it is treated by an off-gas treatment system that prevents the soil
contaminants from being released into the environment. Typical air pollution control equipment
(such as cyclonic precipitators and baghouses) also are used to protect air quality during
operation of desorption units.

Numerous vendors for this type of treatment system exist, and EPA has experienced good success
with its use on soils contaminated with pesticides at other Superfund sites. Treatability
studies would likewise be necessary in order to assess the suitability of this technology for
application at the Helena Chemical Site. The performance standard for this treatment system
would likewise be the LDRs for site specific contaminants.

10.0 STATUTORY DETERMINATION

Under Section 121 of CERCLA, 42 U.S.C. § 9621, EPA must select remedies that are protective of
human health and the environment, comply with applicable or relevant and appropriate
requirements (unless a statutory waiver is justified), are cost effective, and utilize permanent
solutions and alternative treatment technologies or resource recovery technologies to the
maximum extent practicable. In addition, CERCLA includes a preference for remedies that employ
treatment that permanently and significantly reduce the volume, toxicity, or mobility of
hazardous wastes as their principal element. The following sections discuss how the selected
remedy meets these statutory requirements.

10.1 Protection of Human Health and the Environment

The selected remedy provides protection of human health and the environment by eliminating,
reducing, and controlling risk through engineering controls and/or institutional controls and
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 1x10-6 for carcinogens and a 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 1x10-6 and
1x10-4) 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)
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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.

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 determing 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, Alternative 3, affords the highest level of overall effectiveness proportional to its
cost. Section 300.430(f)(1)(ii)(1 )) 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 Selected remedy is $ 2.5 million.

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
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solutions and treatment technologies can be utilized in a cost-effective manner for the final
remediation at the HCC Site. Of those alternatives that are protective of human health and the
environment and comply ply with ARARs, EPA has determined that Alternative 3 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, implemantability, and
cost, while also considering the statutory preference for treatment is 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

The remedy described in this Record of Decision is the preferred alternative described in the
Proposed Plan for this Site. There have been several small changes in the information presented
in the Proposed Plan:

1. The remedial goals in ground water for Endosulfan I and II in the Proposed Plan are 0.2 ug/L
and 0.2 ug/L, and are incorrect. The remedial goals in ground water for Endosulfan I and II
in the ROD (Table 7-1) are 2 ug/L and 2 ug/L. The remedial goals in the ROD represent
concentrations reguired to yield a HQ of 1.

2. The present worth cost of Alternative 5 in the Proposed Plan is $ 6,500,000. The present
worth cost of Alternative 5 in the ROD ranges from $ 3,659,000 to $ 5,311,000. The cost in
the Proposed Plan was incorrect.

3. The present worth cost of Alternative 6 in the Proposed Plan is $ 5,800,000. The present
worth cost of Alternative 6 in the ROD ranges from $ 3,111,000 to $ 4,763,000. The cost in
the Proposed Plan was incorrect.
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APPENDIX A
RESPONSIVENESS SUMMARY
HEIiENA CHEMICAL COMPANY SUPERFUND SITE
TAMPA, HILLSBOROUGH COUNTY, FLORIDA
Introduction
This responsiveness summary for the Helena Chemical Companay 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.
The proposed plan for the Helena Chemical 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
23, 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 well: 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. The results of the well survey indicate that only monitoring wells are open to the
surficial aguifer; drinking water wells around the Site are open to the Floridan Aguifer.
Ground water contamination at the Site is primarily located in the surficial aguifer. Minor
amounts of
contamination have been detected in the Floridan Aguifer beneath the Site.

Private wells were not sampled during the RI/FS; contaminated ground water in the surficial
aguifer, from the HCC 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
reguire tt at the private wells be monitored to ensure that human health is protected.

EPA does not have the authority or funds to address all local ground water issues. Local water
guality is generally considered to be under the jurisdiction of local government. If
contamination from a Superfund Site affects the water guality in a private well, EPA can reguire
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:
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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 Floridan aguifer 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
(HR) 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. 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.

4. 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.

5. 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 ower (<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 that must be disposed of in accordance
with regulatory requirements.
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6. One commentor 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.

7. 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 reguired 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.

8. 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 adeguate as a stand alone process for remediation of pesticides.

9. 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.

10. 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 9,600
cubic yards of material would reguire excavation and treatment. The volumes now are expected to
be slightly higher due to the lower clean up standards proposed by EPA.

11. One commentor asked to which surface water body treated ground water will be discharged to
in Alternative 3. The commentor asked if a National Pollution Discharge Elimination System
(NPDES) Permit will be reguired for the discharge.

Response: Helena Chemical Company currently has a NPDES permit to discharge process water to
the Tampa Bypass Canal. The existing permit would have to be modified for discharge of
additional effluent.

12. One commentor asked what timeframe is reguired to remediate soils and ground water to the
proposed cleanup goals in Alternative 3.

Response: Soil remediation timeframe cannot be determined until pilot study has been performed.
If the timeframe is excessive, costs will increase and it will likely be more appropriate to use
LTTD to treat soil 5. Ground water remediation is estimated at over 30 years.

Concerns about the Baseline Risk Assessment:

13. One commentor asked what studies show is a safe amount of time (hours) to be in the
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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.
Current workers should be monitored for health effects.

14. 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.

15. 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 reguired 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.

16. 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:

17. One commentor asked if the monitoring well network would be expanded to areas that 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 adeguate to define contamination in the surficial aguifer; as
contaminants migrate, the network will have to be expanded. Contamination levels in the
Floridan aguifer need to be monitored and contamination in the Floridan aguifer needs further
delineation to ensure public health is protected.

18. One commentor asked why EPA would select a remedy (such as thermal desorption) which could
make contaminants airborne.

Response: EPA will reguire that adeguate 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.
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19. 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 for
people who line or work near the Site to leave the area during performance of work at the Site.

20. 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.

21. On commentor asked if Helena and Stauffer PRPs are working together, since contaminants
and remedies are similar.

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.

22. One commentor asked if pesticide odors and emissions are expected during excavation, and
if so what measures will be taken to protect the health of onsite workers and people surrounding
the Site.

Response: Odor problems were experienced at an adjacent facility during excavation of pesticide
contaminated soil; therefore, it is reasonable to expect that odor problems need to be consider
likely at this Site. EPA will ensure that odor problems are anticipated and dealt with promptly
during excavation. EPA will reguire that reasonable air emissions controls re installed.

23. One commentor suggested that a ground water capture analysis be completed to demonstrate
that a contaminated water plume is fully captured, prior to implementing final design of the
ground water treatment recovery system.

Response: An analysis will be performed during remedial design to estimate the extraction
system reguired to ensure plume capture.

24. One commentor suggested that EPA reguire monitoring of the Floridan aguifer or set
performance standards that would trigger the reguirement to remediate the Floridan aguifer if
the standards are exceeded.

Response: The proposed remedy reguires monitoring of the Floridan aguifer. The need to
remediate the Floridan aguifer will be evaluated if monitoring results demonstrate that
additional ground water actions are necessary.

25. One commentor suggested that the use of the 20 parts per billion (ppb) Florida Secondary
Maximum Contaminant Level (SMCL) for xylene as a performance standard is needlessly restrictive.
The commentor noted that 10 parts per million (ppm) is the primary drinking water standards set
by EPA and the State of Florida and is considered protective of public health or all public
drinking water systems in the State of Florida. The commentor so noted that the 20 ppb
secondary standard is based on odor and the aesthetic guality of the water, and that the
surficial aguifer is not likely to be used as a drinking water source due to the low volumes it
would produce, especially when access to the higher guality, higher yielding Floridan aguifer is
so readily available.

Response: The 20 ppb Florida SMCL was proposed as a cleanup goal to ensure that xylene would
not be available in ground water to transport any residual pesticides that might be lingering in
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soil.

26. One commentor asked EPA to set a cleanup goal of 50 mg/kg of total chlorinated pesticides
in the soil rather than setting cleanup goals for 9 individual compounds.

Response: EPA has determined that it would be more appropriate to set cleanup goals for
individual contaminants so that when cleanup is complete, no pesticide will be present above
their appropriate risk level. If total pesticides is used as a cleanup goal, the performance
standard at Helena would have to be set at the lowest standard determined acceptable for the 9
pesticides of concern (Toxaphene @ 2.8 ppm). This level may be unnecessarily stringent for the
other pesticides at the Site.

27. One commentor reguested that EPA retain a contingency in the ROD to excavate and ship
contaminated soils to an offsite, regulated and permitted hazardous waste incinerator, in
addition to the low temperature thermal desorption (LTTD) contingency remedy.

Response: Offsite disposal of contaminated soils was considered in the FS, but was dropped in
the analysis because the cost was determined to be prohibitive by the PRP and EPA. Offsite
disposal was not carried through the FS or the Proposed Plan, and therefore, cannot be included
in the ROD. If offsite disposal is latter determined to be appropriate for this Site, a ROD
amendment will have to be approved.

28. One commentor noted that a an inaccurate statement is made in paragraph 2 on page 4. The
statement that the primary contaminant of concern include metals is inaccurate; metals are not
included in the list of contaminants of concern in the proposed plan.

Response: The comment is noted. Several metals were detected in ground water at concentrations
that exceed drinking water Standards. EPA considers pH of soils in the former sulfur pit at the
site as the source for the release of metals to ground water. For that reason, EPA reguired hat
the pH of soils be stabilized between 6.5 and 8.5 in the Proposed Plan and he ROD, rather than
setting cleanup goals for individual metals. If stabilizing the pH is not effective at reducing
the concentration of metals in ground water, cleanup goals that address specific metals may be
reguired.

29. One commentor guestioned the cleanup goal in the proposed plan for Endosulfan I and II of
0.2 ppb, since the Florida guidance concentration is 0.35 ppb.

Response: The cleanup goal for Endosulfan I and II was presented incorrectly in the proposed
plan; the cleanup goal for Endosulfan I and II should have been 2 ppb. This error has been
corrected in the ROD and is explained in Section 11 of the ROD. The cleanup goal in the ROD is
a health based goal generated based on specifics of the Sate. The Florida guidance
concentration is not a Site-specific number.

30. One commentor stated that the cost of Alternative 5 should be 3.6 to 5.3 million dollars
versus $6.5 million as reported in the proposed plan. The commentor also stated that the cost
of Alternative 6 should be 4.3 to 6.6 million versus $5.8 million as reported in the proposed
plan.

Response: The commentor is correct regarding the cost of Alternative 5; the error is noted in
Section 11 of the ROD. The commentor and the Proposed Plan are both in error regarding the cost
of Alternative 6. The commentor notes costs which reflect excavation of contaminated soii to a
depth of 4 feet, treatment with LTTD, and natural attenuation of ground water contamination. The
proposed remedy only reguires excavation of contaminated soil to a depth of 2 feet, treatment
with LTTD, and natural attenuation of ground water contamination. The cost of Alternative 5
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should be 3.1 to 4.8 million dollars. The error is noted in Section 11 of the ROD.

31. One commentor objected to a statement in the proposes plan that contaminants would migrate
downgradient in the Floridan aguifer. The commentor noted that the RI/FS did not establish that
my contaminants are migrating through the confining layer at the HCC site. The commentor
suggested that the low levels of pesticides found in the Floridan aguifer monitoring wells are
more likely the result of well installation artifacts rather than actual contamination within
the aguifer. The commentor recommended that EPA retain natural attenuation as a contingency
ground water remedy in the ROD.

Response: The comment is noted. The proposed remedy, Alternative 3, reguires that the
surficial aguifer ground water be extracted and treated and that the Floridan aguifer ground
water be monitored. If natural attenuation is demonstrated to be effective during remedial
design, ROD amendment will have to be approved.

Concerns From Adjacent Property Owner:

32. One commentor stated that an acceptable site access lease with compensation will be
reguired from Helena prior to access or work being conducted on adjacent property.

Response: If the remedial action prevents the current owner from conducting work, then
compensation may be appropriate. However, ground water extraction systems are typically
constructed below grade and only result in temporary access being reguired during construction
and to maintain and sample the system.

33. One commentor asked that EPA reguire Helena Chemical Company to remove and dispose of
drill cuttings remaining from a well installation project performed by an adjacent property
owner. The commentor stressed that the wells were installed to protect the adjacent property
owner from liability at the Site and that Helena Chemical Company and EPA sampled the wells and
used the results in the RI/FS.

Response: EPA does not have the authority to reguire Helena Chemical to dispose of materials
generated during the investigation conducted by another party, even if the expense of disposal
is necessary because of contamination cause by Helena Chemical Company. The adjacent property
owner may pursue recovery of costs through an independent legal action, if desired.

34. One commentor asked that EPA reguire Helena Chemical Company to reimburse the adjacent
property owner for the license access agreement with CSX reguired to install monitoring wells on
the CSX right-of-way. The commentor stressed that the wells were installed to protect the
adjacent property owner from liability at the Site and that Helena Chemical Company and EPA
sampled the wells and used the results in the RI/FS.

Response: EPA does not have the authority to recover losses incurred by property owners
adjacent to Superfund Sites. The adjacent property owner may pursue recovery of costs through
an independent legal action, if desired.
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