AGENCY:

Environmental Protection Agency (EPA).

ACTION:

Proposed rule; notice of intent.

SUMMARY:

The Environmental Protection Agency (EPA) Region 4 is issuing a Notice of Intent to Delete the soil, sediment, surface water, surficial aquifer, and the intermediate aquifer of this Site with the exception of a limited area (5,000-8,000 square feet) of the intermediate aquifer below the 1C clay in the vicinity of monitoring wells IMW-01B, MW-128, and OW-143 of the Townsend Saw Chain Co. Superfund Site (Site) located in Pontiac, South Carolina, from the National Priorities List (NPL) and requests public comments on this proposed action. The NPL, promulgated pursuant to section 105 of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) of 1980, as amended, is an appendix of the National Oil and Hazardous Substances Pollution Contingency Plan (NCP). The EPA and the State of South Carolina, through the South Carolina Department of Health and Environmental Control (SC DHEC), have determined that all appropriate response actions at these identified media and/or parcels under CERCLA except for five-year reviews, operations and maintenance and monitoring have been completed. However, this deletion does not preclude future actions under Superfund. All Site areas and media will be included in this partial deletion except for the groundwater in the intermediate aquifer as specified above which will remain on the NPL and are not being considered for deletion as part of this action.

DATES:

Comments must be received by August 21, 2019.

ADDRESSES:

Submit your comments, identified by Docket ID no. EPA-HQ-SFUND-1990-0010, by one of the following methods:

• http://www.regulations.gov. Follow the online instructions for submitting comments. Once submitted, comments cannot be edited or removed from Regulations.gov. The EPA may publish any comment received to its public docket. Do not submit electronically any information you consider to be Confidential Business Information (CBI) or other information whose disclosure is restricted by statute. Multimedia submissions (audio, video, etc.) must be accompanied by a written comment. The written comment is considered the official comment and should include discussion of all points you wish to make. The EPA will generally not consider comments or comment contents located outside of the primary submission (i.e. on the web, cloud, or other file sharing system). For additional submission methods, the full EPA public comment policy, information about CBI or multimedia submissions, and general guidance on making effective comments, please visit http://www2.epa.gov/​dockets/​commenting-epa-dockets.
• Email: Joydeb Majumder, Remedial Project Manager, majumder.joydeb@epa.gov.
• Mail: Joydeb Majumder, Remedial Project Manager, Superfund and Emergency Management Division, Superfund Restoration and Sustainability Branch, U.S. Environmental Protection Agency, Region 4, 61 Forsyth Street SW, Atlanta, Georgia 30303-8960.
• Hand delivery: USEPA Region 4 Superfund Record Center, Attention: Tina Terrell, Records Center, Superfund and Emergency Management Division, Superfund Enforcement Branch, U.S. Environmental Protection Agency, Region 4, 61 Forsyth Street SW, Atlanta, Georgia 30303-8960. Monday to Friday 7:30 a.m. to 4:30 p.m.; Phone: 404-562-9121.

Instructions: Direct your comments to Docket ID no. EPA-HQ-SFUND-1990-0010. EPA policy is that all comments received will be included in the public docket without change and may be made available online at http://www.regulations.gov, including any personal information provided, unless the comment includes information claimed to be Confidential Business Information (CBI) or other information whose disclosure is restricted by statute. Do not submit information that you consider to be CBI or otherwise protected through http://www.regulations.gov or email. The http://www.regulations.gov website is an “anonymous access” system, which means the EPA will not know your identity or contact information unless you provide it in the body of your comment. If you send an email comment directly to the EPA without going through http://www.regulations.gov, your email address will be automatically captured and included as part of the comment that is placed in the public docket and made available on the internet. If you submit an electronic comment, EPA recommends that you include your name and other contact information in the body of your comment and with any disk or CD-ROM you submit. If the EPA cannot read your comment due to technical difficulties and cannot contact you for clarification, the EPA may not be able to consider your comment. Electronic files should avoid the use of special characters, any form of encryption, and be free of any defects or viruses.

Docket: All documents in the docket are listed in the http://www.regulations.gov index. Although listed in the index, some information is not publicly available, e.g., CBI or other information whose disclosure is restricted by statute. Certain other material, such as copyrighted material, will be publicly available only in the hard copy. Publicly available docket materials are available either electronically in http://www.regulations.gov or in hard copy at:

(1) USEPA Region 4, 61 Forsyth Street SW, Atlanta, Georgia 30303-8960, Monday-Friday 7:30 a.m.-4:30 p.m., Contact Tina Terrell 404-562-8835; and

(2) Northeast Regional Library, 7490 Parklane Road, Columbia, South Carolina, Monday—Thursday: 9:00 a.m.-9:00 p.m., and Friday-Saturday: 9:00 a.m.-6:00 p.m., Phone: (803) 736-6575.

FOR FURTHER INFORMATION CONTACT:

Joydeb Majumder, Remedial Project Manager, Superfund Restoration and Sustainability Branch, Superfund and Emergency Management Division, U.S. Environmental Protection Agency, Region 4, 61 Forsyth Street SW, Atlanta, Georgia 30303-8960, phone 404-562-9121, email: majumder.joydeb@epa.gov

SUPPLEMENTARY INFORMATION:

Table of Contents

I. Introduction

II. NPL Deletion Criteria

III. Deletion Procedures

IV. Basis for Intended Partial Site Deletion

I. Introduction

EPA Region 4 announces its intent to delete the soil, sediment, surface water, surficial aquifer, and the intermediate aquifer with the exception of a limited area (5000-8000 square feet) of the intermediate aquifer below the 1C clay in the vicinity of monitoring wells IMW-01B, MW-128, and OW-143 of the Townsend Saw Chain Co. Superfund Site (Site), from the National Priorities List (NPL) and requests public comment on this proposed action. The NPL constitutes Appendix B of 40 CFR part 300 which is the National Oil and Hazardous Substances Pollution Contingency Plan (NCP), which EPA promulgated pursuant to Section 105 of the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) of 1980, as amended. EPA maintains the NPL as the list of Site that appear to present a significant risk to public health, welfare, or the environment. Sites on the NPL may be the subject of remedial actions financed by the Hazardous Substance Superfund (Fund). This partial deletion of the Townsend Saw Chain Co. Superfund Site is proposed in accordance with 40 CFR 300.425(e) and is consistent with the Notice of Policy Change: Partial Deletion of Sites Listed on the National Priorities List. 60 FR 55466 (Nov. 1, 1995). As described in 300.425(e)(3) of the NCP, a portion of a Site deleted from the NPL remains eligible for Fund-financed remedial action if future conditions warrant such actions.

EPA will accept comments on the proposal to partially delete this Site for thirty (30) days after publication of this document in the Federal Register.

Section II of this document explains the criteria for deleting Sites from the NPL. Section III discusses procedures that the EPA is using for this action. Section IV discusses the soil, sediment, surface water, surficial aquifer, and the intermediate aquifer with the exception of the intermediate aquifer below the 1C clay in the vicinity of monitoring wells IMW-01B, MW-128, and OW-143 of the Townsend Saw Chain Co. Superfund Site and demonstrates how it meets the deletion criteria.

II. NPL Deletion Criteria

The NCP establishes the criteria that the EPA uses to delete Sites from the NPL. In accordance with 40 CFR 300.425(e), Sites may be deleted from the NPL where no further response is appropriate. In making such a determination pursuant to 40 CFR 300.425(e), EPA will consider, in consultation with the State, whether any of the following criteria have been met:

i. Responsible parties or other persons have implemented all appropriate response actions required;

ii. all appropriate Fund-financed response under CERCLA has been implemented, and no further response action by responsible parties is appropriate; or

iii. the remedial investigation has shown that the release poses no significant threat to public health or the environment and, therefore, the taking of remedial measures is not appropriate.

Pursuant to CERCLA section 121(c) and the NCP, EPA conducts five-year reviews to ensure the continued protectiveness of remedial actions where hazardous substances, pollutants, or contaminants remain at a Site above levels that allow for unlimited use and unrestricted exposure. The EPA conducts such five-year reviews even if a Site is deleted from the NPL. The EPA may initiate further action to ensure continued protectiveness at a deleted Site if new information becomes available that indicates it is appropriate. Whenever there is a significant release from a Site deleted from the NPL, the deleted Site may be restored to the NPL without application of the hazard ranking system.

III. Deletion Procedures

The following procedures apply to deletion of the soil, sediment, surface water, surficial aquifer, and the intermediate aquifer with the exception of the intermediate aquifer below the 1C clay in the vicinity of monitoring wells IMW-01B, MW-128, and OW-143 of the Site:

(1) The EPA consulted with the State of South Carolina before developing this Notice of Intent for Partial Deletion.

(2) The EPA has provided the state 30 working days for review of this notice prior to publication of it today.

(3) In accordance with the criteria discussed above, the EPA has determined that no further response is appropriate.

(4) The State of South Carolina, through the SC DHEC, has concurred with the deletion of the soil, sediment, surface water, surficial aquifer, and the intermediate aquifer with the exception of the intermediate aquifer below the 1C clay in the vicinity of monitoring wells IMW-01B, MW-128, and OW-143 of the Townsend Saw Chain Co. Superfund Site, from the NPL.

(5) Concurrently, with the publication of this Notice of Intent for Partial Deletion in the Federal Register, a notice is being published in a major local newspaper, the Greenville News. The newspaper announces the 30-day public comment period concerning the Notice of Intent for Partial Deletion of the Site from the NPL.

(6) The EPA placed copies of documents supporting the proposed partial deletion in the deletion docket, made these items available for public inspection, and copying at the Site information repositories identified above.

If comments are received within the 30-day comment period on this document, EPA will evaluate and respond accordingly to the comments before making a final decision to partially delete the soil, sediment, surface water, surficial aquifer, and the intermediate aquifer with the exception of the intermediate aquifer below the 1C clay in the vicinity of monitoring wells IMW-01B, MW-128, and OW-143 of the Townsend Saw Chain Co. Superfund Site. If necessary, the EPA will prepare a Responsiveness Summary to address any significant public comments received. After the public comment period, if EPA determines it is still appropriate to delete the soil, sediment, surface water, surficial aquifer, and the intermediate aquifer with the exception of the intermediate aquifer below the 1C clay in the vicinity of monitoring wells IMW-01B, MW-128, and OW-143 of the Townsend Saw Chain Co. Superfund Site, the Regional Administrator will publish a final Notice of Partial Deletion in the Federal Register. Public notices, public submissions and copies of the Responsiveness Summary, if prepared, will be made available to interested parties and included in the Site information repositories listed above.

Deletion of a portion of a Site from the NPL does not itself create, alter, or revoke any individual's rights or obligations. Deletion of a portion of a Site from the NPL does not in any way alter the EPA's right to take enforcement actions, as appropriate. The NPL is designed primarily for informational purposes and to assist EPA management. Section 300.425(e)(3) of the NCP states that the deletion of a Site from the NPL does not preclude eligibility for future response actions, should future conditions warrant such actions.

IV. Basis for Intended Partial Site Deletion

The following information provides the EPA's rationale for deleting the soil, sediment, surface water, surficial aquifer, and the intermediate aquifer with the exception of the intermediate aquifer below the 1C clay in the vicinity of monitoring wells IMW-01B, MW-128, and OW-143 of the Site:

Site Background and History

Due to contaminated soils, sediments, groundwater, and surface water, the EPA, EPA proposed listing the Site on the National Priorities List (EPA ID: SCD980558050) on June 24, 1988 (53 FR 23988), and finalized the listing on February 21, 1990, (55 FR 6154), under CERCLA, 42 U.S.C. 9601. The 50-acre Site located in Pontiac, Richland County, South Carolina was a small manufacturing facility located approximately two miles south of Pontiac, South Carolina. Starting in 1971, Textron Inc., began utilizing the facility for manufacturing the saw chain component of chain saws. Between 1964 and 1981, under the Townsend Division of Textron, Inc. and a previous owner, Dictaphone Inc., waste rinse waters from on-site plating and parts-assembly processes were discharged to the ground surface in a low-lying area adjacent to the facility. These discharges are the origin of the groundwater and soil contamination. There is one sitewide operable unit that includes soils, sediments, and groundwater associated with the waste water rinse releases from the previous operation.

The Site consists of a 50-acre area associated with a former metal products Manufacturing facility and is referred to as “the Site” in this report. The leading edge of the contaminated groundwater plume has also migrated to a 350-acre parcel of undeveloped land located to the northeast across Spears Creek Church Road, which includes a 113-acre Conservation Easement through the Congaree Land Trust. This 350-acre parcel is referred to as the “off-Site area.” While the off-Site area is technically part of the Superfund site, for ease of understanding, the 50 acre parcel is referred to as “off-Site” to distinguish from the 50-acre area. The Site has 2 underlying aquifers.

The portion of the Site being proposed for deletion in today's action are soil, sediment, surface water, surficial aquifer, and the intermediate aquifer with the exception of the intermediate aquifer below the 1C clay in the vicinity of monitoring wells IMW-01B, MW-128, and OW-143, for a limited area (5000-8000 square feet) in the vicinity of the three wells. Since June 2016, all of the contaminated groundwater plume has been remediated to levels below the Safe Drinking Water Act Maximum Contaminant Levels (MCLs) except for a limited area (5000-8000 square feet) in the vicinity of three wells located in the on-site area (IMW-01B, MW-128, OW-143).

Site-specific geological and stratigraphic information was developed during the installation of test borings and monitoring well boring. Soils underlying the Site can be divided into three units; Unit I exposed at the surface and consists of alternating layers of sand, silty or clayey sand, and silt or clay lenses. These various layers appear to be hydraulically connected. Perched water zones occur within the upper part of Unit I. Unit II is a low-permeability confining unit consisting of hard, dry, kaolinitic silty clays or clayey silt. Unit II appears to be laterally continuous on the Site property. Unit III consists of slightly silty, fine-to medium-grained sand. Because only a few Site well borings have penetrated into Unit III, its hydrogeologic and stratigraphic characteristics are not as well known. Units II and III and the lower portion of Unit I are part of the Middendorf Formation. Sand strata within the Middendorf are productive aquifers, and the formation serves as a major aquifer in South Carolina.

There is potential redevelopment of the western portion of the Site west of Spears Creek Church Road to commercial property including retail and other commercial uses. AMBAC Intermodal (formerly American Bosch), a manufacturer and supplier of fuel injection equipment operates on approximately five acres of the fifty-acre Site. The remaining portion of the Site east of Spears Creek Church Road has been redeveloped to various commercial uses.

Remedial Investigation and Feasibility Study (RI/FS)

In August 1991, the EPA entered into an Administrative Order on Consent with Homelite Division of Textron, Inc. to perform a Remedial Investigation/Feasibility Study (RI/FS). Investigation results indicated that hazardous substances, including chromium and volatile organic compounds (VOC) were present in soil and groundwater at the Site and groundwater and surface water in the off-Site area.

A Baseline Risk Assessment (BRA) was conducted in 1993. The BRA concluded that, under the industrial land use scenario that existed at the Site in 1993, the Site did not present any unacceptable human health risks via any medium. However, under the anticipated future land use scenario, which assumed residential and commercial land uses in the off-Site area and continued industrial land uses on the Site, excess human health risks existed through contact with contaminated ground water (e.g. ingestion, inhalation, and dermal exposure).

The Feasibility Study, completed on August 19, 1996, considered remedial options including a Resource Conservation and Recovery Act (RCRA) cap, solidification/stabilization, in-situ chemical treatment, and excavation/offsite disposal as alternatives to address contaminated soils. The FS considered groundwater use restrictions/institutional controls, groundwater extraction/treatment/spray field discharge, groundwater extraction/treatment/publicly-owned treatment works (POTW) discharge, and in-situ chemical treatment to address contaminated groundwater.

Selected Remedy

On December 22, 1993, an Interim Record of Decision (IROD) was issued for the Site. The interim remedy selected in the IROD was intended to prevent the continued off-Site migration of the chromium-contaminated groundwater plume. The interim action consisted of the following remedial components:

(1) Planning and execution of a hydrogeologic investigation that would support the remedial design of an Interim Action Pump and Treat System (IAPTS). This system would, at a minimum, prevent further off-Site migration and enlargement of the contaminant plume; and

(2) Expeditious design and construction of such a system and initiation of ground water pump-and-treat operations.

The EPA issued the ROD for the Site on December 19, 1996. Based on the results of the RI/FS and the Baseline Risk Assessment, the EPA determined that remediation of soils, groundwater, and sediments would be required for the protection of human health and the environment.

The remedial action objectives includes:

Soils

Prevent the leaching of contamination into groundwater, which can contribute to human health risk via groundwater;

Groundwater

(1) Prevent exposure to chemicals of concern in groundwater which pose an unacceptable human health risk;

(2) Reduce concentrations of chemicals of concern, thereby restoring potential use of the aquifer as a potable water source; and

(3) Prevent or reduce the continued discharge of contaminated groundwater to surface water, such that surface water quality standards are not exceeded.

Surface Water

(1) Reduce contamination to levels which (a) cannot pose ecological risk to tributary flora and fauna, and (b) are incapable of recontaminating tributary sediment;

(2) Prevent exposure of the tributary ecosystem to chemicals of concern, and/or reduce the concentrations of chemicals of concern such that no unacceptable ecological risks are present. The selected remedy, as stated in the ROD, included several major components and a contingency remedy. The selected remedy includes:

Soil Treatment

(1) Excavation and removal of the uppermost highly contaminated soils, and treatment of surficial soils through in-situ chemical treatment.

Groundwater Remediation

(1) In-situ chemical treatment of ground water;

(2) Continued operation of IAPTS; and

(3) Sediment removal action at the off-Site area seep (to be performed upon completion of the chromium ground water cleanup.

Site Monitoring

(1) Continued quarterly sampling/analysis of Site ground water.

(2) Additional quarterly sampling of surface water in the unnamed off-Site tributary. and

(3) Periodic sampling of treated Site soils.

Response Actions

The Remedial Design and Remedial Action were implemented by Textron, Inc. through two Unilateral Administrative Orders. The Site's principal exposure pathway of concern was ingestion of groundwater.

Therefore, the soil cleanup goal was based upon leachability to groundwater. Although not prescribed in the Site's Interim Record of Decision, approximately 75 tons of soils from hotspot areas contaminated with chromium, lead, and several other heavy metals, were excavated and disposed of properly in 1995 and 1996. The excavations were located near the northeast and northwest corners of the manufacturing facility. Soils with contamination above the cleanup goal for hexavalent chromium had been removed and no further soil remediation was required based on currently available data. Between June and December 1995, a five-well IAPTS was constructed and new treatment equipment installed for the wastewater treatment system. The system consisted of the three original recovery wells located along Spears Creek Church Road, and two new recovery wells located in the off-Site area. The IAPTS began operating in December 1995. Groundwater from these wells was pumped to a treatment facility at the manufacturing facility and treated in electrochemical precipitation cells. Treated groundwater was then discharged to an on-Site, South Carolina DHEC-permitted spray field.

Remedial design work for the in-situ chemical treatment technology began in May 1997 and was completed in September 1999. Injection lines of wells on 40-foot centers were used to place a ferrous sulfate solution in contact with chromium contaminated groundwater. The solution converted the main contaminant, hexavalent chromium, into an inert and harmless type of chromium mineral, which remains safely in the subsurface. The 2001 ESD established an updated chromium soil cleanup number. Based upon this ESD, no additional soil cleanup was necessary.

In April 2002, the IAPTS was shut down as a trial measure because it was thought to be affecting groundwater flow pathways and potentially affecting chemical treatment activities. The system has remained shut down since this time. While in operation, the IAPTS recovered over 550 pounds of chromium from groundwater. During 2000-2003, the in-situ treatment was implemented along successive injection well lines, proceeding northeastward across Spears Creek Church Road and into the off-Site area. Since 2002, the off-Site area was largely the focus of treatment; however, spot treatments have been performed on small resistant areas within the former plume area onsite. In September to October 2004, seven additional monitoring wells were installed in four locations in the off-Site area. The wells were installed to better characterize groundwater flow direction both above and below the 1C clay.

The Explanation of Significant Difference (ESD) issued in April 2007, was to add two remedy components to the original remedy to enhance remedy performance and to place the IAPTS into stand-by mode. The two new remedy components were institutional controls (ICs) over the 39.79 acres portion of the Site on the western side of Spears Creek Church Road including parcel 28800-01-03 and a portion of parcel 28800-01-22 and installation of a Permeable Reactive Barrier (PRB) in the off-Site area to prevent discharge of TCE and chromium contaminated groundwater to surface water. The objectives for ICs were to (1) restrict the use of ground water as a drinking water source until MCLs are met for the Site and off-Site area; (2) restrict the use of the Site (property associated with original facility operations) to commercial, industrial, or light industrial land uses only; and (3) restrict the use of the off-Site area in order to protect the future PRB from damage. The IAPTS would remain in stand-by mode until determined that it needed to be reactivated or dismantled.

To enhance groundwater cleanup, a bio-stimulation approach and a pilot test of a combination of fatty acids and ferrous sulfate injection system (creating a BioBarrier) was conducted in 2009. Based on the results of the pilot study, construction of the BioBarrier by injection was initiated in 2010 in lieu of the PRB proposed in the 2007 ESD. The initial BioBarrier consisted of twelve new wells for injection of the carbon source substrate that were installed along the top of the slope (upgradient area) and three new injection wells in the downgradient area in late 2011.

As of 2012, the BioBarrier had reduced chromium concentrations in the leading edge of the plume to below MCLs. A second round of Phase 2 ferrous sulfate injections were conducted in 2012 and completed by April 2013. By mid-2013, the combination of the BioBarrier and upgradient ferrous sulfate injections, the overall plume area had been reduced to 53,400 square feet from an original size of 400,250 square feet. Since that time, remedial activities at the Site have largely consisted of installation of injection wells and injection of the carbon source amendment to address residual areas of the plume. Since June 2016, all of the plume has been remediated to levels below the MCL except for a limited area (5000-8000 square feet) in the vicinity of three wells located in the “on-Site area” (IMW-01B, MW-128, OW-143).

In 2013, fourteen new injection wells were installed. Seven injection wells were installed in the perched groundwater table in the western area of the Site and seven injection wells were installed in the BioBarrier area to augment existing injection wells.

Cleanup Levels

The Remedial Design for the Soil/Sediment remedy began in 1995 and was completed in 1997 by the PRP with EPA oversight. Soil cleanup levels for chromium were attained by soil removals conducted in 1996. As of April 2017, all groundwater monitoring wells with the exception of IMW-01B, MW-128, and OW-143 in the intermediate aquifer below the 1C clay had attained and maintained the groundwater cleanup goals for a period of at least eight separate and distinct sampling rounds pursuant to the February 24, 2015, Textron Verification Monitoring Strategy.

Semi-annual sampling of surface water and sediments in the tributary to Spears Creek have demonstrated a declining trend in (contaminant or chromium) concentrations over the past eight years as groundwater remediation progressed. The ESD did not establish a chromium cleanup goal for sediment. The 2010 Five-Year review referenced the Ecotox threshold of 81 mg/kg for total chromium. Chromium concentrations are below screening values in 11 of 12 samples analyzed at 4 locations and any sporadic exceedances do not present significant risks to ecological receptors. No additional response action for chromium in sediments was required.

The Ambient Water Quality Criteria (AWQC) for surface water for ecological protection for hexavalent chromium is 11 ug/L and the AWQC for trivalent chromium is 74 ug/L which are typically adjusted for hardness. The 2001 ESD set the stream cleanup goal as 40 ug/L which was retained in the 2010 and 2015 five-year reviews. As of July 2016, surface water sampling results for total and hexavalent chromium had been well below that level for eight sampling events and below detection levels for six sampling events.

Operation and Maintenance

EPA approved an Operations, Maintenance, and Performance Monitoring Plan for the Site in August 2001. This plan encompasses the operation and maintenance of both the in-situ chemical injection treatment and pump-and-treat systems. The Plan was revised in March 2002, to shut down the IAPTS as a trial measure. The Site's 2007 ESD further stipulated that the IAPTS should be maintained in a stand-by condition for reactivation, if needed. The 2010 five-year review listed as one recommendation the evaluation of the need to continue holding the lAPTS in stand-by condition at the Site due to the improved performance of the in-situ treatment. The November 22, 2010, semiannual groundwater results demonstrated two years of consecutive reduction in the contaminant plume size and contaminant concentrations.

In 2012, an assessment of historic and recent volatile organic chemical concentration data at the Site was conducted for the three chlorinated VOCs that had been detected over time (perchloroethylene, trichloroethylene, and 1,1 dichloroethylene). The data evaluation determined that the initially low concentrations observed at the Site had declined over time due to attenuation and the in-situ reductive processes employed in the remediation. Groundwater MCLs for the 3 VOCs are met. The potential for vapor intrusion issues was also evaluated using the most conservative (95th percentile) and median attenuation factors for soil types. Allowable groundwater concentrations were back-calculated from USEPA indoor air Regional Screening Levels, the indicated attenuation factors, and Henry's Law Constants. All detections of perchloroethylene and 1,1 DCE in the most recent data were below the allowable groundwater concentrations calculated using the most conservative attenuation factors. The most recent TCE groundwater concentrations were an order of magnitude below with the allowable concentrations derived from the median attenuation factors for depths of greater than 5 meters which corresponds with Site groundwater depths (approximately 30 ft bgs). Additionally, all VOC detections were from wells screened below the middle clay layer which provides a barrier to vertical vapor migration or adjacent to the Congaree Land Trust where development would be prohibited. There is no vapor intrusion pathway of concern at the Site.

The monitoring wells located on and around the Site are regularly sampled at designated quarterly or semi-annual intervals. Groundwater sampling at monitoring wells will continue until all the remedial goals for all contaminants are achieved at the three remaining monitoring wells that have not yet attained Site cleanup standards. Future groundwater restoration activities may include additional subsurface injections of ferrous sulfate and a blend of fatty acids to address chromium MCL exceedances in the intermediate aquifer below the 1C clay in the vicinity of monitoring wells IMW-01B, MW-128, and OW-143.

Institutional Controls (ICs)

The 2007 ESD required ICs over the 39.79 acres portion of the Site on the western side of Spears Creek Church Road including parcel 28800-01-03 and a portion of parcel 28800-01-22. The restrictions limit soil and groundwater use and restrict the property use to commercial, industrial or light industrial uses. Groundwater use is prohibited for potable, irrigation or other uses except with express written consent of Textron, Inc. This was implemented in a Declaration of Covenants and Restrictions recorded on Deeds recorded at the Richland County Register of Deeds on February 9, 2007 in Instrument #2007011804. The ICs are recorded on the deed, are transmitted to successors, and are verified during the five-year Review process.

Five-Year Review

Previous five-year reviews were conducted because hazardous substances remained on Site above levels which allowed for Unlimited Use/Unrestricted Exposure and the Site groundwater had not attained all cleanup levels contemplated in the Record of Decision (ROD) and subsequent Explanation of Significant Difference (ESD). Five year Reviews will no longer be conducted at the portions of the Site deleted from the NPL which achieved Unrestricted Use/Unlimited Exposure (UU/UV). Five-year reviews will continue to be conducted for that portion of the Site designated for industrial and commercial uses. A 39.79-acre portion of the Site including parcel 28800-01-03 and a portion of parcel 28800-01-22 meets clean up criteria, but has Institutional Controls, requires five-year reviews and does not meet Unlimited Use/Unrestricted Exposure criteria. Five-year reviews will continue for that portion of the groundwater of the Site still on the NPL. The last five-year Review was completed in July 2015 and found the remedy protective of human health and the environment. There were no Issues or Recommendations in the Five-Year Review. The next Five-Year Review is scheduled to be completed in July 2020.

Community Involvement

On June 12, 1991, April 14, 1992, August 23, 2001, and June 6, 2006, EPA, SC DHEC, and Textron representatives conducted public availability sessions for RI/FS kickoff, the interim groundwater remedy ROD, and two Explanation of Significant Difference proposals addressing groundwater. On August 31, 1993 and September 17, 1996, EPA, DHEC, and Textron representatives conducted proposed plan meetings. EPA conducted community interviews during December 10-13, 1991, prior to the Site National Priority Listing. EPA and DHEC conducted community interviews for the three Five-Year reviews in 2005, 2010, and 2015.

Determination That the Criteria for Deletion Have Been Met

The EPA has followed procedures required by 40 CFR 300.425(e) regarding requirements for deletions. EPA consulted with the State of South Carolina through the SC DHEC. South Carolina issued a May 12, 2017, concurrence letter indicating its agreement with today's proposed action.

The implemented remedy achieves the degree of cleanup or protection specified in the ROD and ESD for the areas proposed for deletion. The selected remedial and removal action objectives and associated cleanup levels for the areas proposed for deletion are consistent with agency policy and guidance. No further Superfund response in the areas proposed for deletion are needed to protect human health and the environment.

List of Subjects in 40 CFR Part 300

• Environmental protection
• Air pollution control
• Chemicals
• Hazardous waste
• Hazardous substances
• Intergovernmental relations
• Penalties
• Reporting and recordkeeping requirements
• Superfund
• Water pollution control
• Water supply

Authority: 33 U.S.C. 1321(d); 42 U.S.C. 9601-9657; E.O. 13626, 77 FR 56749, 3 CFR, 2013 Comp., p. 306; E.O. 12777, 56 FR 54757, 3 CFR, 1991 Comp., p. 351; E.O. 12580, 52 FR 2923, 3 CFR, 1987 Comp., p. 193.