^^'"_:% U.S. ENV IRONMENTAL PROTECTION AGENCY

i Superfund Explanation of Significant Differences

%p«o%/ Eoambia Wood Treating Company Superfund Site Pensaco/a, Escambia County, Florida

ISS

Pensacola, Escambia Coimly, Florida Mardi 2012

This fact sheet is being issued to document technical changes made during the Superfund cleanup at the Escambia Wood Treating Company Superfund Site in Pensacola Florida. EPA made these changes because the conditions found during coastmction differed from the conditions known when the Record of Decision was signed. When a Remedial Action is adjusted. EPA documents the decision in an ''Explanation of Significant Differ^nces".

In t roduc t ion

The U.S. Environmental Protection Agency (EPA) is conducting a remedial action for the soils portion of Operable Unit 1 (OUl) at the Escambia Wood Treating CompaEiy (ETC) Superfund Site (Site) located in Pensacola. Florida. The EPA issued a Record of Decision (ROD) for this remedy ga February 2, 2006. and began remtdiai constnjction in August 2007. The overall cleanup approach is to treat principal threat wastes tKrough soliditicaiion/siabili7.ution and lo permanenlly isolate conlaminalcd soil in an on-site conlainmenl cell. As of July 2010. ihe consiruciion of the cell was complele. Ag of February 2012, the remaining ROD requirements are closeout items, such as dewatering the cell, institutional controls and deed restrictions. The EPA carried out ihis cleanup llwougli a partuership wifli the Fiorida Department of Environmeiital Protection, which provided teclmical support and 10% of Remedial Action costs.

This ExpJana!ion of Significant Differences (ESD) explains changes to Llie cleanup goals and to construction details specified in tlie ROD, The changes

to these components do not fiuidainenraily alter the overall cleanup approach. The objective of controlling human exposure remains unclianged and has been achieved by the cleanup,

Tliis ESD is being issued as part of EPA's public participation responsibilities under Section 13 7(c) of the Comprehensive EnvinmmenE il Response, Compensation and Liability Act (CERCLA), as amended by the Superfund Amendments and Reauthorization Act (SARA). 42 U.S.C. §§ 9601 el seq.. and Section 300,435(e)(2)(i) of the National Contingency Plan (NCP),40C,F,R.Part300.

This FSD will become part of the Administrative Record in accordance with 40 C.F.R, ij 300.825(a)(2) of the NCP. The Administrative Record contains documents used as the ha.sis for the remedy selected for the Sile, including the ROD and Responsiveness Summary. The Adminisirative Record documents are available for public review in the ETC Site information repository located at llie following locations:

AdmJDistr^iii^e Record and l&focitiatifin RepositorJ<^$ for the ETC Superfiind Site

West Florida Regional LibrdTv Genealogy Branch

5740 N. Ninth Ave Pensacola. Fl 32504

U.S. EPA - Reiiicin 4 Supedund Records

Center 6!FoRtyihSUSW Ai3ania.GA 30303

Site History

The Site is located al 3910 North Palafox. Street in the City of Pensacola, Florida. Operable Unit I refers lo contaminated soils and includes the fonner ETC facihty

area, which covers 26 acres, plus about 69 acres of surrounding neighborhoods purchased by the EPA, which increases the total area of OUl to approximately 100 acres.

The ETC facility manufactured pressure-treated wood products, primarily utility poles and foundation pilings. From 1942 to approximately 1970, coal-tar creosote was the primary wood preservative. Starting in 1963, Pentachlorophenol (PCP) dissolved in No. 6 diesel fuel was also used at the facility and was the sole preservative in use from 1970 until 1982 when the facility closed. In 1991, ETC tded for bankruptcy and abandoned the Site. The company defaulted on its environmentalliabilities, and the case was referred to the Department of Justice (DoJ) lo pursue settlement with the owners. DoJ reached a final settlement with the owners in 2002.

The primary wastes managed at the facility were process wastewater and contaminated runoff from the former treatment area. From the mid-1940s tlirough the mid-1950s, wastewater was sent to an unlined pond located in the northeastern part of the Site. After the mid-1950s, this pond was used as a landfill and process wastewater and contaminated runoff were managed by two separate systems.

Previous EPA Actions

Starting in 1982, EPA and Ihe State of Florida cited the ETC facility for numerous violations, including uncontrolled ground water contamination and inadequate financial assurance under hazardous waste regulations. In June 1990, EPA conducted a Facility Assessment at the ETC facility to verify the fmdings of an earlier tile review, to assess the release or the potential for release of hazardous wastes or constituents from the facility, and to assess if further action was needed. The assessment identified 32

Solid Waste Management Units (SWMUs) and recommended the entire facility be treated as an Area of Concern (AOC). The site was uncontrolled, and there were immediate pathways of exposure to open waste pits, contaminated soil, and chemical drums.

In response to the bankruptcy of ETC and the abandonment of the facility in 1991, EPA Region 4 activated the EPA Environmental Response Team to perform a preliminary assessment of the Site. The investigation indicated that a removal action was needed.

In October 1991, EPA began a removal action to address immediate risks of exposure and to stabilize the Site. EPA excavated about 225,000 cubic yards of contaminated material and stored it under a 60-mil (1.5 millimeters [mm]), High Density Polyethylene (HDPE) liner treated to be resistant to ultraviolet light. The former process area and a fomier wastewater pond/landtlll were excavated to approximately 40 feet deep. The removal action was completed in 1992.

EPA proposed the Site for inclusion on the National Priorities List (NPL) in August 1994 and the listing on the NPL was finalized on December 16. 1994. Cleanup actions were divided into two Operable Units; OUl addresses soil contamination and OU2 addresses contaminated ground water.

In 1997, an biterim ROD was issued, selecting permanent relocation of 358 households from the neighborhoods north of the facility (Rosewood Terrace, Oak Park, and Escambia Arms) and the Goulding (Hennan and Pearl Streets) neighborhoods south of the site. The relocation was carried out as part of the National Relocation Pilot Project. The relocation occurred from November 1997 to August 2005. The Clarinda Triangle neighborhood was added to the hiterim Remedy in the 2006 Final OUl ROD. The relocation of the residents in the Clarinda Triangle area occurred from December 2006 to 2009. In total, more than 400 households and about 500 people were relocated, and about 70 acres of land was acquired by the Federal Government.

OUl Final Remedial Action

The 2006 Final OUl ROD presented the final remedy for the contaminated soils. The overall cleanup strategy for the OU-1 final remedy is to treat principal tlireat wastes tlirough solidificationy stabilization and to permanently isolate soil contaminated above the selected cleanup levels in an on-site contaimnent system in order to protect both human and ecological receptors. The major components of the Remedy include:

• E.xcavation of contaminated soil on- and off-site;

• Contaimnent of the containinated soil in a lined cell followed by installation of a multi-layer cap over the contaimnent area compatible, to the extent possible, with the intended future commercial use of the property;

' Solidification/stabilization of identified principal threat waste to form a sub-cap beneath the multi-layer cap;

• Operation & maintenance of the cap and containment system;

• Long-term monitoring of the containment system;

• Institutional controls to restrict future use of the Site to commercial uses compatible with the remedy;

• Five-year reviews of the remedy to ensure protectiveness is maintained; and

• Residential relocation within and immediately adjacent to the Clarinda Triangle neighborhood.

Remedy Implementation

Construction activities began at the ETC site on September 24, 2007. The construction consisted of excavating, stockpiling, and placing containinated soil and debris in a containment cell. The bottom of the containment cell was lined with a composite liner made of 60 mil HDPE and a geosynthetic clay liner. The sloped walls of the contaimnent cell were lined with a 60 mil HDPE liner. The top of the containment cell was lined with a composite liner to exclude water from entering the cell. A drainage system was installed above the containment cell. During excavation and

construction, EPA conducted air monitoring, dust control, and sile restoration to minimize the impacts of the construction on the coinmunity.

Basis for ESD

Tills ESD is being issued to change two parts of the 2006 Final OUl ROD, and maintains the protectiveness of the remedy. This ESD adds and updates the cleanup goals to reflect the appropriate level of protectiveness for the potential exposure pathways at the site. The new cleanup goals are protective of human health and the environment and achieve the objectives of the ROD. Also, this ESD changes certain construction requirements in the ROD that were over-specific, and were found to be impractical once the construction was underway.

Original Cleanup Goals from 2006 ROD

The cleanup goals in the 2006 Final OUl ROD were derived from the human health risk assessment, and applicable State regulations. The cleanup goals were

based on achieving a residual excess cancer risk for direct exposure of less than one in a million (IxlO"'') for future cormnercial/industrial land use and protection of groundwater from leaching of contaminants above drinking water standards. The key contaminants of concern (COCs) for OUl are chemicals related lo wood treating operations that were identified in both soil and ground water. For Dioxin and PAHs, COCs found in soil, but not in ground water, the 2006 ROD clean up goals were based on the direct human exposure pathway. For COCs found in groundwater, the 2006 ROD cleanup goals were based on a groundwater exposure pathway, and were calculated using the Summers model (EPA, 1989).

The cleanup goals in the 2006 ROD have two limitations that became evident during the remedial construction; cleanup goals were not developed for all potential pathways for all contaminants, and the Summers model resulted in cleanup goals that were overly conservative. Of the nine COCs in the 2006 ROD, two were based on the direct exposure pathway, and seven were based on the groundwater exposure pathway, as shown in Table I. This ESD establishes cleanup goals for all COCs based on both the direct exposure and leaching-based groundwater protection pathways. This ESD also replaces the Summers model derived cleanup goals with updated site-specific cleanup goals for groundwater protection.

As seen in Table I, Dioxin and Polyaromatic Hydrocarbon (PAH) cleanup goals in the 2006 ROD were based only on direct exposure. The 2006 ROD anticipated that those COCs were limited to surface contamination. As construction and confirmation sampling proceeded, Dioxin and PAHs were found in subsurface soils which would remain buried due to institutional controls placed on the property. EPA and FDEP agreed that a leachabilily-based cleanup goal was appropriate for subsurface Dioxin and PAH contamination.

The 2006 ROD established only leaching-based cleanup goals for Naphthalene, Acenaphthene, Fluorene, Phenanthrene, 2-Methylnaphthalene, Carbazole, and Pentachlorophenol. Once construction and confiniiation sampling began, these COCs were found at the surface often enough that EPA determined a direct exposure cleanup goal was needed. EPA and FDEP agreed to use the FDEP commercial/industrial soil cleanup target

levels (SCTLs) for direct exposure as the cleanup goals for these seven compounds

Daring the review of the cleanup goals, the EPA noted that the 2006 ROD leacliing-based cleanup goals were far more conservative than the established leaching-based cleanup target levels used by the State i)f Florida (SCTLs). Tliis is because the 2006 ROD used the Summers model to derive the cleanup goals. Tlie Summers model is a mathematical estimate of how COCs would leach out of contaminated soil and into groundwater. While the Summers Model is appropriate to use as a screening model, soil cleanup goals derived from the model tend to be higldy conservative. The conservative nature of the Summers Model stems from several of the simplifying assumptions made within the model, (e.g. an infinite source of chemical, no fractionation between pathways^ no biological or chemical degradation, and no adsorption to soil), and the one-dimensional solute fate and transport simulation employed.

Once Ihe limitations in applying the Summers Model were identified, EPA and FDEP conducted a site-specific leaching study lo evaluate the leaching behavior of the COCs at the site. The Icacliing study followed FDEP's "Guidance for Detemnning Leachability by Analysis of SPI.P Resulls" which is consistent with F.PA guidance for conducting leachability studies. The study confirmed that the Summers model does not accurately predict the leaching of COCs from actual site soil and that the Summers model derived cleanup goals were more conservative than necessary to achieve the remedial action objectives established in the ROD. After evaluation of the data and discussion with FDEP, HPA and FDEP agreed that the FDEP's leaching-based SCTLs would be appropriate cleanup goals for the leaching-based groundwater protection exposure pathway.

Table 1. 2006 ROD Soil Cleanup Goals for ETC OU-1

Contaminant of Concern

Ben2o(a)pyrene EQ (cPAHs)

Dioxin TEQ (2,3.7.8-TCDD)

Naphthalene

Acenaphthene

Fluorene

PhenanUirene

2-Metl'iylnaphthalene

Carbazole

Pentachlorophenol

Direct Exposure Pathway

2006 ROD Cleanup Goal

400

0 1)30

None

None

None

None

None

None

None

LeacIting'Based Groundwater E.xp0sure Pathway

2006 ROD rieaimp Goal (Summers Model) (jig/kg)

None

None

419

1,954

1,525

3,829

2.394

6.5

5.1

Revised Cleanup Coals

Thjs ESD replaces the cleanup goals in the 2006 ROD with the cleanup goals in Table 2. Tiiese cleanup goals more accurately refiect Ihe potential routes of exposure al ihe site, achieve the remedial action objectives established in the ROD. and provide for a cleanup that is protective oi human liealih and ihe environment under the plaimed future use of the sile. Under Ihe National Contingency Plan, EPA's goal is to r«iuce the excess cancer risk to the range IxlO"^ (one in ten thou.sand) lo IxlO'*^ (one in one million) for the expected future land use al ihe Sile. The new cleanup goals for OUl are based on a future commercial/industrial land use for the ETC Site and on achieving a residual excess cancer risk of less than 1x30" (one in one million) with a hazard quotient less than 1. The AJAAR-based direct exposure cleanup goal for dioxin TEQ (2,3,7,8 TCDD) is unchanged from the 2006 ROD and is based on Florida Statute Section 376.30701 requiring cleanups to attain an incremental lifetime cancer risk of < I X 10" (less than one in one million) and a hazard index of <1 (less than one) fornon-carcinogens.

The EPA and FDEP modified the excavation plan so That the direct exposure cleanup goals were used in the former neighborhoods, since there is no site-related groundwater contamination in the former neigliboriioods. For the top six feet of soils at the fonner facility, the more conservative of the direct exposure or the leaching-based cleanup goals were used. For former facility soils deeper than sLx feet, only the leaching-based cleanup goals were used. This is compatible with t3ie institutiona3 controls al the site, which will restrict digging deeper than six feet to protect the contaimnent cell.

Cleanup goaSs were applied to different areas on the site based on the e\lent of coniamination in the area. Table 3 presents the application of the cleanup goals in different parts of the sile.

Table 2. Revised Soil Cleanup Goals for ETC OU-l

Contaminant of Concern

B6rLZo(a)pyre[ie EQ (cPAUs)

Dioxin TEQ (2,3,7,S-TCDD)

Naphthalene

Acenaphthene

Fluorene

Phenantlirene

2*McLhylnaphthalene

Carbazole

Pentachlorophenol

Direct Exposure Pathway

Revised Cleanup Go»] (^^kg) Source (FAC 62-777 Table II)

Direct Exposure Commerciaiy Industrie SCTL

700

0.030

300.000

20.000.000

33.000.000

36.000,000

2,100,000

240.000

28.000

teaching-Based Groundwater Exposure Pathway

Revised Cleanup Goal (^g/kg) Source ffA C 62-777 Table If)

Leachability Based on Groundwater Criteria SCTL

8,000

3,000

1,200

2.100

160.000

250,000

8,500

200

30

T a b l e 3. Appl ica t ion of C l e a n u p Goals S c o p e a n d R o l e of A c t i o n

Portion of Site

Fonner neighborhoods -Surface soil coniamination only

Former Facility ~ Surface soils (0-6 feet)

Fomier Facihty ~ Subsurface soils (deeper than 6 feet)

Cleanup Goals Applied

Direct exposure cleanup goals only.

The more conservative of the direct exposure or leaching-

based cleanup goals.

Leacliing-bascd cleanup goals only.

Revised Construction Specincatit>ns

This ESD also documents changes in certain construction requirements in the ROD that were over-specific, and were found to be impractical once the construction was undeAvay.

The 2006 ROD specified 'The principal tlireat wastes will be mixed with cement to form a sub-cap three- to four-feet in thickness above the compacted soil to at or near to existing grade." The thicknes.s of the soUdified/stabilized sub-cap was based on the estimated volume of principal threat waste and the anticipated area of the contaimnent cell. Once construction began, two factors affected the thickness of the sub-cap; the dimensions of the cell changed, and less principal threat waste was found. The layout of the cell increa.-icd to about IS acres from about 15 acres because the volume of the containment cell increased from 399,010 cubic yards to 557,000 cubic yards. Further, less principal threat waste wag encountered during the excavaiinns than estimated. The cast half of the sub-cap thickness was reduced after this became apparent. The sub-cap ihickiiess was reduced to two feet, but the compressive strength was increased, allowing the eastern sub-cap to maintain the equivalent shear resistance as the rest of the cap. To assure the strengtli of Ihc entire sub-cap, (he final lift of material contained a cement content of eight percent across the entire sub-cap.

The purpose of this ESD is to document the decision to modify the soil cleanup goals and to modify construction requiremenls in the 2006 ROD. The original remedy, as written in the 2006 ROD^ did not derive cleanup goals for direct exposure and protection of groundwater for all COCs, and was overly specific in certain design requirements.

A p p l i c a b l e o r R e l e v a n t a n d A p p r o p r i a t e

R e q u i r e m e n t s ( A R A R s )

This ESD does not change the AJIAR analysis presented in the 2006 ROD, which provides a detailed discussion of potential ARARs for a wide range of activities at the Site. Cleanup or remedial actions must comply with applicable or relevant and appropriate requirements (ARARs) under hedcral environmental laws, and State environmental or facility siting laws. Identification of ARARs must be done on a Site-specific basis. Although on-Sitc portions of cleanup activities at CERCLA Sites arc exempt from permitting requiremenls, they must meet the substantive requirements of the ARAJRs.

I m p a c t of M o d i f i c a t i o n s

The implementation of the modified soil cleanup goals resulted in some cost savings, while still providing the same degree of protection for human exposure and groundwater. Figure I shows the excavation grids where the leacliing based cleanup goal for Dioxin was applied. The implementation of the reduced subcap thickness prevented the unneeded stabilization/ solidification of tens of thousands of cubic yards of soil to meet the ROD specification while providing significant cost savings and meeting the long-term performance and reuse objectives established in the ROD.

ligure 1. Grid Layout Showiiiy Grids witliSubsuriace Dioxiu above Surface SCTLS

OVERALL GRID LAYOUT FOR AREAS SOUTH OF FXC04

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Statutory Determination

The changes to the ROD documented in this ESD are protective of human health and the environment, comply with Federal and State requirements that are applicable or relevant and appropriate to this remedial action, are cost effective, and use permanent solutions to the maximum extent practicable for this Site.

Who Can You Call For Answers?

If you have a question about activities on the Site, please call Erik Spalvins, the EPA rernedial project manager. He can be reached at (800) 435-9234 or via email at spalvins.erik@epa.gov.

Author iz ing S igna tu re

1 have determined that the remedy for the Site, as modified by this ESD, is protective of human health and the environment, and will remain so provided that the actions presented in this report are implemented as described above.

This ESD documents the significant changes related to the remedy at the Site. U.S. EPA selected these changes after consultation with the FDEP.

U.S. Environmental Protection Agency

lor Superfund Division

Date: