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Statement of Basis for Remedy Selection at

Former Rohm and Haas Cincinnati Facility2000 West Street

Reading, Ohio

Hamilton County, OhioOHD 000 724 138

Prepared byThe Ohio Environmental Protection Agency

Division of Environmental Response and Revitalization

October 2020

document.docx

Table of Contents1.0 INTRODUCTION........................................................................................................................1-12.0 PUBLIC PARTICIPATION............................................................................................................2-13.0 FACILITY BACKGROUND...........................................................................................................3-1

3.1 OPERATING HISTORY............................................................................................................3-13.2 PHYSICAL SETTING...............................................................................................................3-1

3.2.1 Surface Water................................................................................................................3-13.2.2 Regional Geology and Hydrogeology.............................................................................3-2

3.3 HAZARDOUS WASTE MANAGEMENT.....................................................................................3-33.4 INTERIM CORRECTIVE MEASURES........................................................................................3-43.5 CURRENT STATUS................................................................................................................3-5

4.0 CORRECTIVE ACTION INVESTIGATIONS....................................................................................4-14.1 RCRA FACILITY INVESTIGATION (RFI) RESULTS.....................................................................4-1

4.1.1 Soils...............................................................................................................................4-24.1.2 Surface Water and Sediments.......................................................................................4-24.1.3 Groundwater.................................................................................................................4-34.1.4 Groundwater Use...........................................................................................................4-5

4.2 ECOLOGICAL RISK ASSESSMENT..........................................................................................4-64.2.1 Fate and Transport........................................................................................................4-64.2.2 Chemicals of Potential Ecological Concern....................................................................4-7

4.3 HUMAN HEALTH RISK ASSESSMENT.....................................................................................4-84.3.1 Chemicals of Potential Concern.....................................................................................4-84.3.2 Exposure Assessment....................................................................................................4-94.3.3 Risk Analysis................................................................................................................4-104.3.4 HHRA Conclusions.......................................................................................................4-11

4.4 DUE DILIGENCE SAMPLING OF GROUNDWATER AND SOIL VAPOR......................................4-114.5 PRELIMINARY CORRECTIVE MEASURES EVALUATION.........................................................4-12

5.0 SCOPE OF REMEDY..................................................................................................................5-15.1 INSTITUTIONAL CONTROLS...................................................................................................5-15.2 GROUNDWATER EXTRACTION SYSTEM.................................................................................5-15.3 3-DIMENSIONAL GROUNDWATER FLOW MODEL...................................................................5-25.4 MONITORED NATURAL ATTENUATION..................................................................................5-2

i Proposal TitleiFormer Rohm and Haas Statement of Basis

6.0 SUMMARY AND EVALUATION OF POSSIBLE REMEDY................................................................6-16.1 EVALUATION OF TECHNOLOGIES..........................................................................................6-1

6.1.1 Soil Remediation...........................................................................................................6-36.1.2 Groundwater Remediation.............................................................................................6-3

6.2 REMEDY DESCRIPTION AND EVALUATION............................................................................6-36.2.1 Soil: Instituional Controls...............................................................................................6-36.2.2 Groundwater: No Action................................................................................................6-46.2.3 Groundwater Extraction System....................................................................................6-46.2.4 Monitored Natural Attenuation of Constituents in Groundwater....................................6-46.2.5 Groundwater Restriction for Future Well Installation.....................................................6-6

6.3 REPORTING FREQUENCY......................................................................................................6-67.0 SUMMARY................................................................................................................................7-18.0 REFERENCES...........................................................................................................................8-1

Figures

Figure 3-1 Site Location Map

Figure 3-2 Site Vicinity Map

Figure 3-3 Site Layout Map

Figure 3-4 Cross Section Map D-D’

Figure 3-5 Institutional Controls Map

ii Proposal TitleiiFormer Rohm and Haas Statement of Basis

AcronymsAO Administrative OrderBEHP Bis(2-ethylhexyl)phthalateBGS Below Ground SurfaceBHC Benzene HexachlorideBTEX Benzene, Toluene, Ethylbenzene, XyleneCOPC Constituent(s) of Potential ConcernCOPEC Constituent(s) of Potential Ecological ConcernCSO Combined Sewer OverflowDCA DichloroethaneDDE DichlorodiphenyldichloroethyleneDPT Direct Push TechniqueEDG Environmental Data GroupESL Ecological Screening Levelft3/day Cubic Feet Per DayFI Facility InvestigationGPD Gallons Per DayGPM Gallons Per MinuteHCLRC Hamilton County Land Reutilization CorporationHHRA Human Health Risk AssessmentMBI Midwest Biodiversity InstituteMCL Maximum Contaminant Levelsmg/kg Milligrams Per KilogramMNA Monitored Natural AttenuationMSD Metropolitan Sewer DistrictNRWQC National Recommended Water Quality CriteriaOEPA Ohio Environmental Protection AgencyOMZA Outside the Mixing Zone AveragePAH Polycyclic Aromatic HydrocarbonPCB Polychlorinated BiphenylPCE TetrachloroethylenePCR Primary Contact RecreationQA/QC Quality Assurance/Quality ControlRCRA Resource Conservation and Recovery Act, 42 U.S.C. §2001 et seq.

iii Proposal TitleiiiFormer Rohm and Haas Statement of Basis

RFA RCRA Facility AssessmentRFI RCRA Facility InvestigationROH Rohm and HaasRSL Regional Screening LevelSLERA Screening Level Ecological Risk AssessmentSSO Sanitary Sewer OverflowSVOC Semi-Volatile Organic CompoundSWMU Solid Waste Management UnitUA Upper Aquiferµg/L Microgram Per LiterUSEPA United States Environmental Protection AgencyUSGS United States Geological ServiceUST Underground Storage TankVOC Volatile Organic Compound

iv Proposal TitleivFormer Rohm and Haas Statement of Basis

STATEMENT OF BASIS FORThe Former Rohm and Haas Cincinnati Plant

Reading, OhioOHD 000 724 138

1.0 INTRODUCTIONThe Ohio Environmental Protection Agency (OEPA) prepared this Statement of Basis for the former Rohm and Haas (ROH) facility (Facility or Site) in Reading, Ohio. The purpose of this Statement of Basis is to provide the public with information on the Resource Conservation and Recovery Act (RCRA) Corrective Action remedy the OEPA Is proposing to select prior to taking a final action. The OEPA is issuing this Statement of Basis as part of its public participation responsibilities under RCRA. This Statement of Basis summarizes information found in greater detail in the RCRA Facility Investigation (RFI) and other documents in the Facility’s Administrative Record. The RFI characterized the nature and extent of contamination at the Facility and subsequent documents and discussions with the U.S. Environmental Protection Agency (USEPA) and OEPA addressed the rationale, approach and justification for the proposed remedy at the Facility. ROH, and subsequently The Dow Chemical Company (Dow), prepared these documents in accordance with an Administrative Order on Consent between the USEPA and ROH. The Administrative Order on Consent was terminated in 2017 and regulatory authority was transferred to OEPA at that time. These documents serve as the foundation for the Statement of Basis and should be reviewed to gain a more comprehensive understanding of the Facility and the activities that have been conducted. This Statement of Basis explains the proposed remedy for residual groundwater contamination at the Facility, which has been divided into parcels separately owned by 2000 West Street LLC, the City of Reading and the Port Authority of Cincinnati; however, remedial activities may be performed by former owner Dow. The former ROH Facility is located at 2000 West Street in Reading, Ohio, a northern suburb of Cincinnati. The purpose of this document is:

To identify the proposed corrective action remedy for public comment, To solicit public review of and comment on all remedial alternatives including those not

previously considered, and To provide information on how the public can be involved in the remedy selection.

OEPA will select a specific remedy for the Site only after the public comment period has ended. OEPA may modify the proposed remedy or select another remedy and will consider any public comments or new information obtained. The public is encouraged to review and comment on the proposed remedy. If a public meeting is requested, a newspaper notice will publish the meeting location and date prior to the meeting and the information will be made available via OEPA’s website. In addition, virtual public hearings and meetings are a permissible tool for OEPA to use as part of public participation for permitting, remedy selection, and similar regulatory actions conducted under federal environmental statutes

1Former Rohm and Haas Statement of Basis

2.0 PUBLIC PARTICIPATIONOEPA solicits input from the community on the proposed remedy. Written comments may be submitted before the end of the comment period. The comment period may be extended by OEPA if a specific request for a comment period extension is received within the original comment period. All persons, including any current property owners, may submit comments relating to this matter. Written comments are to be submitted by email to OEPA at [email protected] or directly to Brian Marlatt at [email protected]. When submitting written comments, please indicate the comments concern the Former Rohm and Haas Statement of Basis. If there is public interest, OEPA may hold either a public meeting in Reading, Ohio or a virtual public meeting to discuss the proposed remedy and any additional actions the public may propose. The public was informed of the Statement of Basis and the critical documents are available for public review. Links to the critical documents used to select the remedies may be found in the references in Section 8.0. If significant public interest is shown, the OEPA may offer a public meeting during the public comment period. After considering the comments received, OEPA will summarize the comments and its responses in a response to comments document. This document will be incorporated into the Administrative Record


mailto:[email protected]

mailto:[email protected]

3.0 FACILITY BACKGROUNDWhen operational, the former ROH Cincinnati Plant consisted of a single tract of land totaling 34 acres in the City of Reading, Ohio. Figure 3-1 shows the location of the Facility, Figure 3-2 depicts the surrounding vicinity of the Facility, and Figure 3-3 presents a detailed site map of the Facility. The site was sold and has subsequently been subdivided into seven separate parcels, two of which are currently owned by 2000 West Property LLC, one parcel (a right-of-way for Riesenberg Avenue) by the City of Reading, and the remainder owned by the Hamilton County Land Reutilization Corporation (HCLRC) whose client, The Port, intends to redevelop the land.

3.1 OPERATING HISTORYThe Facility was originally developed in 1949 by Cincinnati Milling Machine as the Carlisle Chemical Works. Prior to Carlisle’s development, the Site was used as a dairy farm and milk bottling facility, winery, smokehouse and fireworks manufacturer. Carlisle Chemical Works operated the facility from 1949 – 1970 at which time it was operated under the name Cincinnati Milacron until 1980. In 1980, the Site was sold to Carstab, a division of Thiokol. In 1982, Morton and Thiokol merged, and the Facility operated as Morton-Thiokol from 1982 – 1989. In 1989, Thiokol was sold and the Facility was operated as Morton International until 1999, when it was purchased by ROH. It operated as ROH until 2009 when ROH was purchased by The Dow Chemical Company. Dow operated the Facility until 2013 when the Facility was sold to PMC Group. The Facility was subsequently sold to 2000 West Property in 2016 and demolition of the Facility began then. Most of the Site is currently vacant with one building (Building 40) being used for light commercial/industrial use and warehousing. From 1950 – 2013, the Facility manufactured synthetic waxes, asphalt additives (anti-stripping agents), antioxidants, phosphonium salts and plastic stabilizers (organotin and cryo-glycolate organotin stabilizers). Raw materials for these products included:

Metallic tin Chloromethane Chlorine Ammonia Ethanol Ethyl chloride Benzyl chloride

3.2 PHYSICAL SETTINGApproximately 27 acres of the former ROH Site comprised the fenced, operational area of the Facility and the remaining 7 acres contain recreational ball fields used by the City of Reading. Surrounding land use at the site consists of the Pristine Superfund Site and former Cincinnati Drum Facility to the north, Riesenberg Avenue, a recreational walking trail, Mill Creek and an asphalt plant to the west, railroad tracks and commercial/industrial properties to the east and a recreational center and residential homes to the south (see Figure 3-2).


3.2.1 SURFACE WATER Mill Creek is the only body of surface water in the vicinity of the Facility. Mill Creek is a tributary of the Ohio River and the confluence of the two streams is located approximately 14 miles south of the Site. The State of Ohio has assigned Mill Creek the following beneficial use designations:

Aquatic Life – warm-water habitat; Recreation – primary contact recreation; and Water Supply – agricultural and industrial.

The Mill Creek was identified as a priority impaired water on Ohio’s 2018 303(d) list. Biological and chemical stream surveys indicated nutrients, bacteria, organic chemical pollutants, metals and habitat alterations were some of the primary causes of impairment in the watershed (OEPA, 2018). Recent (2016) studies of Mill Creek (MBI, 2016) show that Mill Creek is a recovering system, with most sites that were rated as poor or very poor in 1992 and fair to marginally good in 2011 for aquatic life had improved to fair, good, and in a few instances exceptional quality in 2016. In 2016, of the 33 sites sampled, 12 were in full attainment, 15 in partial attainment and 6 in non-attainment for aquatic life use designations. The closest monitoring station to the Site (at River Mile 13.2 at Columbia Road approximately 0.2 miles downstream) was in partial attainment in 2016 with causes for impairment reported as siltation, nutrients, chlorides and PAHs, all common parameter exceedances for urban streams [Midwest Biodiversity Institute (MBI), 2016]. Impairment of the Primary Contact Recreation (PCR) recreational use in Mill Creek was pervasive throughout the stream in 2016. The PCR 30 day (geometric mean) criterion for E. coli was exceeded at 29 of the 33 sites. Identifying the sources of fecal bacteria in urban areas can be a complex process, but in Mill Creek they are mostly related to combined sewer overflows (CSOs), sanitary sewer overflows (SSOs), urban runoff, and deteriorating sewage collection systems in the older urban areas (MBI, 2016). Contaminated fish tissue due to mercury contamination (statewide) and PCBs (for approximately the lower 20 miles of Mill Creek) prompted the State of Ohio to issue a limited consumption advisory for all fish species (one meal per week of fish caught from all Ohio surface waters due to mercury contamination and one meal per month of fish caught from Mill Creek due to PCB contamination) (OEPA, 2019).Mill Creek currently lies 80 – 100 feet west of the Facility property boundary. Before about 1950; however, aerial photographs indicate that, in the vicinity of the Facility, the creek lay about 300 feet west of its current location. The change is believed to be part of drainage and flood control improvements performed by the U.S. Army Corps of Engineers around 1950.A contributing stream enters Mill Creek from the General Electric property to the northwest of the Facility, and surface drainages also enter Mill Creek from the former Cincinnati Drum and the Pristine properties, upstream of the Facility. Drainage from the Facility does not enter Mill Creek under typical conditions. Instead, this drainage enters the Facility’s sewers, operated by the Metropolitan Sewer District (MSD). Facility runoff does periodically enter Mill Creek during major storm/flooding events. Mill Creek is not used for drinking water supply or agricultural watering in Hamilton County and no surface water intakes are located within three miles of the Facility (TechLaw, 1998). The creek has been, however, reported to be occasionally used for recreational purposes; however, such use is limited based on widespread impairment due to E. coli concentrations (MBI, 2016).

2 Proposal Title2Former Rohm and Haas Statement of Basis

3.2.2 REGIONAL GEOLOGY AND HYDROGEOLOGYHamilton County is located on the west flank of the regional anticline termed the Cincinnati Arch. The Facility is located within the Mill Creek Valley, which is one of a series of buried glacially-incised valleys in the region. The Mill Creek Valley is a buried valley of the Deep Stage Cincinnati River. In general, the lower portion of this valley is formed of the Ordovician Kope Formation, comprising limey shales with limestone interbeds (Osborne, 1968; Osborne, 1974). The valley is filled predominantly with glacial outwash deposits, with lesser amounts of moraine deposits and alluvial deposits from the valley walls.Sand and gravel deposits within the outwash facies filling the buried valleys form a generally prolific aquifer system, referred to as the Buried Valley Aquifer System (E&E, 1991). This aquifer system is the primary source of groundwater for the Cincinnati area and is widely used for municipal and industrial supply. As discussed in the Current Conditions Report (Geomatrix, 2000), the shale bedrock underlying the outwash deposits is not considered a significant source of groundwater in the area of the Facility.Previous drilling in the vicinity of the Facility (primarily for the Pristine investigations) indicated typical local thicknesses for the outwash deposits ranging from 130 to 160 feet. To the east of the Facility, these deposits thin and pinch out against the eastern edge of the Mill Creek Valley. Previous work at this and neighboring facilities have divided the outwash deposits into two aquifers for the purposes of investigation and remediation. These are generally referred to as the Upper and Lower Aquifers. Figure 3-4 depicts the geologic cross section beginning east of Mill Creek and going west across the southern portion of the site. This cross section is generally representative of the entire site.The Upper Aquifer (UA) consists predominantly of clayey sediments, with variable numbers of saturated sand interbeds. For any given location within the Facility, from one to four sand or gravelly sand interbeds may be present. At the Site, the shallow, laterally continuous sand interbed is designated as the “Shallow UA Sand” and all deeper interbeds as “Deep UA Sands.” The depth to saturation within the Shallow UA Sand is as shallow as 5 to 10 feet in the vicinity of the Facility. Historic data suggest that the Shallow UA Sand is likely in hydraulic communication with Mill Creek.Underlying the Upper Aquifer, the Lower Aquifer is a thick sequence comprising predominantly sand and gravels. Its upper portion predominantly comprises silty sand and is reportedly not widely used for local water supply. The lower portion is typically screened by local production wells for large commercial and municipal users. The former Reading municipal supply wells, located north and south of the Facility, did produce from this zone. These wells were closed in the 1990s, however, due to impact from Pristine constituents, especially 1,2-dichloroethane (1,2-DCA) and other chlorinated ethanes and methanes. The Lower Aquifer is not generally used for domestic supply in Hamilton County, based on the prevalence of public supply (E&E, 1991).

3.3 HAZARDOUS WASTE MANAGEMENTIn the past, solvents, fuel oils and other raw materials were stored at the Site in storage tanks, both above and below ground. From 1950 – 1980, six former surface impoundments were used for neutralization and disposal of wastes consisting primarily of hydrochloric acid, methanol, dilute sulfuric acid, resorcinol, and benzoic acid. The disposed waste reportedly also contained metals, waste oils and benzene compounds. Each impoundment was unlined and subsequently filled with soil. Additionally, a concrete storage pad was built over the closed impoundments and used as a hazardous waste drum storage area from 1980 – 1990. Hazardous wastes formerly stored in this area included ignitable wastes, spent solvents, and other liquid wastes generated at the facility.


On August 18, 2000, the USEPA issued a RCRA §3013 Administrative Order (AO) to Morton International, Inc. Paragraphs 16 through 23 of the AO identified several areas for investigation. Most of these areas correspond to single or multiple solid waste management units (SWMUs) identified in the 1998 RCRA Facility Assessment (RFA) (TechLaw, 1998). A listing of the study areas referenced in the AO, and their corresponding SWMU designations where appropriate, is provided in Table 1. In addition, the Current Conditions Report (GeoMatrix, 2000) identified several areas of reported historic waste burial or potential waste management and were added to the list of waste management areas to be investigated for the RFI.

Table 1Summary of Waste Management Areas

Identification DescriptionSWMU 1 Six Former Surface ImpoundmentsSWMU 2 Former 10,000-Gallon Neutralization TankSWMU 3 Former Drum Storage Area – located over the

Former Surface Impoundments (SWMU 1)SWMU 4 Hazardous Waste Drum Storage AreaSWMU 5 Former 10,000-Gallon Sulfide Waste Treatment

TankSWMU 6 Groundwater Collection System – French Drain,

extraction well, collection sump and slurry wallSWMU 7 Groundwater Treatment UnitSWMU 8 Satellite Waste Accumulation AreasSWMU 9 pH Control SystemSWMU 10 Former Swale SystemSWMU 11 Combined Sewer SystemMill Creek Seeps Seeps on east bank of Mill Creek, west of the

Facility5,000-Gallon Ignitable Waste Storage Tank

Formerly used for storage of “ignitable waste”

12,000-Gallon Reactive Waste Storage Tank

Formerly used for storage of “reactive waste”

Wastewater Treatment Tank Formerly used for wastewater treatmentWaste Burial Location A Burial location of small quantities of sodium and

various lab samples, estimated total of 55 gallonsWaste Burial Location B Through 1950, area was used to neutralize acid

wastes. Burial location of excavation and building debris from Building 27 demolition.

Waste Burial Location C Area was used to burn waste solvents (notably hexane, heptane, and methanol). Possible location of three drums, contents unknown, buried in lime and soda ash fill.

Waste Burial Location D One drum of sulfur monochloride buried in lime and soda ash fill.


Identification DescriptionWaste Burial Location E Possible location of one or two drums, contents

unknown, buried in lime and soda ash fill.Waste Burial Location F Former burial location of pipes and equipment,

including sodium metal in pipes, from a building explosion and fire. The debris was later removed.

Waste Burial Location G Possible location of three drums, contents unknown, buried in lime and soda ash.

From: TechLaw, 1998 and GeoMatrix, 2004.

3.4 INTERIM CORRECTIVE MEASURES The former impoundments (SWMU 1) were closed between 1970 – 1980. SWMU 1 consisted of six former unlined ponds that were approximately 2,500 square feet and approximately five to six feet deep. The three westernmost ponds contained crushed dolomite stone to neutralize acid waste. After neutralization, liquids were pumped through two settling ponds located immediately east of the neutralizing ponds. The remaining liquid was discharged into the sixth pond and allowed to evaporate. The westernmost ponds were filled with clean soil in 1970 and 1974. The easternmost neutralization pond and the two settling ponds were filled with clean soil and capped with a 6-inch layer of concrete in 1979. The last remaining pond was dredged and filled with clean soil in 1980. The entire area was covered with asphalt and was then used to store hazardous waste drums (SWMU 3) and later for loading and unloading of materials (TechLaw, 1998).An interim action was also conducted in 1976 that involved the excavation and removal of surface soil (0-6-inch depth) with elevated concentrations of tin [concentrations ranged from 100 – 1000 parts per million (ppm)]. Soils with elevated tin concentrations were located in the southeastern portion of the Facility and sources of the contamination were attributed to leaks from the aqueous tin chloride transfer pipes and storage drums near the former research laboratory. Leaching of tin to the subsurface was not indicated as low levels of tin in the soil 6 – 12-inch depth ranged from 1 – 10 ppm (Geomatrix, 2004). Additionally, a groundwater extraction system (SWMU 6) was installed at the Facility to control groundwater migrating into the adjacent Mill Creek, which is located west of the Facility. The system was installed in 1985 and consists of four components: a French drain, an extraction well, a collection sump and a concrete slurry wall. Groundwater containing volatile organic compounds (VOCs), semi-volatile organic compounds (SVOCs) and metals is extracted from the subsurface and, during Site operations, was transferred to a groundwater treatment unit (SWMU 7). A large portion of the treated groundwater was recirculated as make-up water in the Facility’s non-contact cooling water system. The remainder of the water was discharged to the Cincinnati Metropolitan Sewer District (MSD). Late in the Facility’s operation, some of the treated groundwater was also used in the Facility’s vacuum pump system. Since the Facility operations were dismantled in 2016, the extracted groundwater has been discharged directly to MSD. Three underground storage tanks (USTs) were formerly located in the east central portion of the Site. Two USTs had a volume of 12,000-gallons each and were used for storing heating oil. The third UST had a volume of 300-gallons and stored gasoline used by forklifts at the Site. The heating oil tanks were closed in place in 1992 under the guidance of the State Fire Marshall’s office (BUSTR). During closure of the heating oil USTs, excavated soils that had been surrounding the USTs were sampled were sampled and found to contain low concentrations of benzene, toluene, ethylbenzene and xylenes (BTEX). Approximately 57 tons of soil were removed and disposed off-site at a biotreatment


facility. The gasoline UST was reportedly removed in the 1980s; however, no further information was available regarding this removal. Concurrent with the RFI in 2004, soils exhibiting elevated metal levels at the Trench T-1 location (Waste Burial Area F), which had been identified during the initial FI activities near the fuel tanks south of Building 32, were excavated and removed. This interim measure was performed to remove soils exhibiting the highest known levels of metals at the Facility, thereby mitigating potential risks to construction or on-site workers. The field work associated with these activities included the excavation and off-site disposal to a non-hazardous landfill of approximately 130 cubic yards of soils and the excavation extended to a maximum depth of approximately 8 feet. During the course of the excavation, a total of five drums were identified and removed. Upgrades to the combined sewer system (SWMU 11) were also done to replace areas that had failed due to corrosion and debris accumulation late in 2004 and continued through 2012 as part of a sitewide capital improvement program.

3.5 CURRENT STATUS On December 21, 2017, the USEPA terminated the AO since USEPA deemed that the terms of the Order had been satisfactorily completed. Additionally, on December 14, 2017, USEPA transferred to OEPA the responsibility for leading the remaining corrective actions at the Site. As part of the transfer to OEPA, four areas of concern were identified by USEPA that needed to be addressed in the next phase of corrective action for the Site:

1. Contaminated groundwater in the upper aquifer above drinking water standards.2. Contaminated groundwater in the upper aquifer serving as source of hazardous vapors in

indoor air from industrial and commercial buildings. 3. Contaminated groundwater in the shallow upper aquifer discharging to Mill Creek above

surface water criteria. 4. Contaminated groundwater in the deep upper aquifer which may migrate off-site that is

unsafe for potable use. Institutional controls (see Figure 3-5) were recorded for the property via an environmental covenant on June 25, 2018 by 2000 West Property, LLC that addressed drinking groundwater and exposure to hazardous vapors in indoor air at the Site, as well as prohibiting residential use for the former manufacturing area. For the deep upper aquifer, groundwater flow is towards a central trough, thereby limiting the potential for off-site migration. Additionally, groundwater pumping of the deep aquifer by the nearby Pristine Superfund Site has controlled groundwater elevations and flow patterns. Thus, the only area of concern remaining for the facility subject to corrective actions by Dow is the potential for the shallow aquifer to discharge into Mill Creek at concentrations above levels that are protective of aquatic life. USEPA requires continued operation of the existing groundwater extraction system (SWMU 6) until such time as a final remedy is selected for the Site (USEPA, November 6, 2017).


4.0 CORRECTIVE ACTION INVESTIGATIONS Historical investigations of soil and groundwater quality, and surface water and sediments of the adjacent Mill Creek indicated the presence of VOCs, SVOCs and metals in shallow groundwater beneath the site. Chemicals were also identified at low levels in soils from various locations across the property. Operations throughout the facility that contributed to the historical contamination include: spills, leaks and other accidental discharges from storage tanks and associated piping; discharge of waste and wastewater to the ground surface and impoundments; and discharge of wastes and wastewaters to sewers with subsequent leakage to surrounding soils. Historic waste management areas, including the Former Swale Area (SWMU 10), aboveground wastewater treatment and storage tanks, and suspected waste burial areas, did not exhibit significant subsurface accumulations of waste materials, oils, sludges, or other concentrated sources of on-going releases. In particular, the large quantities of drums reported for the Former Swale Area were not present. The presence of buried drums or chemical wastes was observed only at Waste Burial Area F. As described in Section 3.4, soils were excavated at this location (Trench T-1) as part of an interim action to reduce potential risks associated with elevated metals detected in the soils (Geomatrix, 2004).The RCRA Facility Investigation (RFI) conducted in 2004 established the nature and extent of contamination of soils and groundwater. Additional groundwater monitoring was conducted through 2016 to track concentration trends in groundwater. In 2017 and 2019, additional soil vapor and groundwater samples were collected as part of due diligence work prior to sale/lease of the property. The results of the RFI and subsequent sampling events are summarized below.

4.1 RCRA FACILITY INVESTIGATION (RFI) RESULTSThe RFI was designed to address critical data gaps and evaluate the possible environmental impact associated with Facility operations. The specific objectives of the RFI were to: (1) evaluate the migration of groundwater and impacts to underlying aquifers, including an evaluation of the effectiveness of the groundwater extraction system; and (2) to evaluate the risks to human health and the environment. Between 2001 and 2002, Geomatrix, a consultant for ROH, performed a number of field activities at the Facility consisting of:

Installation of 32 Upper Aquifer monitoring wells Installation of 3 Lower Aquifer monitoring wells Plugging and abandonment of 14 Upper Aquifer monitoring wells Drilling of 11 stratigraphic borings into the Lower Aquifer or to bedrock Advancement of 46 on-site direct-push technique (DPT) borings Advancement of 10 off-site DPT borings Performance of aquifer testing Performance of sewer video camera survey Collection of 12 creek bank sediment samples [(excluding duplicates and quality

assurance/quality control (QA/QC) samples] Collection of 8 creek bed sediment samples (excluding duplicates and QA/QC samples) Collection of 2 seep samples (excluding duplicates and QA/QC samples) Collection of 166 soil samples (excluding duplicates and QA/QC samples) Collection of 80 groundwater samples (excluding duplicates and QA/QC samples)


Performance of optical brightener testing at 11 of the stream stations Performance of 7 surface geophysical surveys Performance of ecological surveys of the site and Mill Creek Excavation of 8 exploratory trenches.

A Supplemental Facility Investigation (FI) was conducted in 2002 – 2003 by Geomatrix, which consisted of the following activities at the site:

Installation of two on-site Upper Aquifer wells completed in the Deep Upper Aquifer Sands Advancement of 3 on-site stratigraphic borings into the Deep Upper Aquifer Sands, or through

these sands to the Lower Aquifer Advancement of 42 on-site DPT borings Advancement of 10 on-site shallow hand auger borings Analysis of 6 creek bed sediment samples from Mill Creek (excluding duplicates and QA/QC

samples) Analysis of 6 surface water samples from Mill Creek (excluding duplicates and QA/QC

samples) Analysis of 38 soil samples (excluding duplicates and QA/QC samples) Analysis of one DPT groundwater sample Analysis of 39 groundwater samples (excluding duplicates and QA/QC samples).

Overall, five categories of compounds were analyzed during the FI and revised facility investigation: VOCs, SVOCs, pesticides and polychlorinated biphenyls (PCBs), chlorinated dioxin/furans, and inorganics. No chlorinated dioxins were detected in any samples, soil or groundwater. Figure 4-1 depicts the locations VOCs were detected in groundwater and surface water during the RFI investigations. For the purpose of discussing the data, chemicals detected in less than five percent of the samples were eliminated from further consideration in the quantitative risk calculations in accordance with USEPA guidance (USEPA, 1989a). USEPA (1989) states, “Chemicals that are infrequently detected may be artifacts in the data due to sampling, analytical, or other problems....” However, chemicals that were detected at a frequency of <5% but had one or more detections that were above applicable screening criteria were included in the evaluation as part of the Baseline Risk Assessment (Parsons, 2010).

4.1.1 SOILSSoil samples were collected from the surface to the groundwater table [up to 24 feet below ground surface (bgs)]. A total of 137 soil samples were analyzed for various constituents. Thirteen VOCs were detected in soils at a frequency greater than 5% with acetone (detections ranging from 0.0019J – 23 mg/kg), toluene (0.00052J – 240 mg/kg), chlorobenzene (0.00053J – 42 mg/kg), methylene chloride (0.0014JB – 11 mg/kg), and xylenes (0.002J – 50 mg/kg) being the most frequently detected VOCs in soil. Ten SVOCs were detected in site soils at a frequency greater than 5% with bis(2-ethylhexyl)phthalate (BEHP) (0.033J – 150 mg/kg), fluoranthene (0.063J – 4.3J mg/kg), pyrene (0.063J – 11 mg/kg), phenanthrene (0.07J – 9.8 mg/kg), and benzo(b)fluoranthene (0.07J – 7 mg/kg) being the most frequently detected SVOCs in site soils. All 25 inorganics that were analyzed for in soil were detected at a frequency greater than 5% except for silver. Metals detected in soils associated with site operations included arsenic (0.75J – 16.2 mg/kg), chromium (0.55B – 388 mg/kg), lead (2 – 780 mg/kg) and tin (0.96J – 12,700 mg/kg). Chromium speciation analyses were conducted on four soil samples in 2004 and the results confirmed that the chromium observed at the site is present almost exclusively in the trivalent form. Five PCB mixtures were detected in soil; however only one (Aroclor-1254) was detected in more than 5% of the 126 soil samples. The maximum detected concentration was 0.98 mg/kg at location UAW17-40, at a depth of 1.5 feet bgs. Of the twenty-two pesticides


detected, only gamma-Chlordane, 4,4’-DDE, endosulfan sulfate, endrin, endrin ketone, and methoxychlor were detected in more than 5% of the samples analyzed. Maximum concentrations of gamma-Chlordane (1.7 mg/kg), 4.4’-DDE (0.2 mg/kg), endosulfan sulfate (0.48 mg/kg), endrin (3.1 mg/kg), endrin ketone (1 mg/kg) and methoxychlor (5.5 mg/kg) were detected in samples between 9.5 and 13.5 feet bgs.

4.1.2 SURFACE WATER AND SEDIMENTSSix surface water samples were collected from Mill Creek in March 2004. Six VOCs, two SVOCs, no pesticides and eight inorganics were detected in the surface water samples. Concentrations of VOCs and SVOCs were all below 2 μg/L except for acetone, which was detected at 6.3 μg/L. Ten VOCs were detected in 26 sediment samples collected from Mill Creek. Acetone (8 samples) and chlorobenzene (5 samples) were detected most frequently, both at a maximum concentration of 0.018 milligrams per kilogram (mg/kg). Twenty-four SVOCs were detected in seven sediment samples. The highest concentrations of polycyclic aromatic hydrocarbons (PAHs) were anthracene (1.3 mg/kg), benzo(a)anthracene (1.4 mg/kg), benzo(a)pyrene (1.2 mg/kg), benzo(b)fluoranthene (1.3 mg/kg), chrysene (1.7 mg/kg), fluoranthene (4.6 mg/kg), phenanthrene (4.8 mg/kg), and pyrene (3.1 mg/kg). These PAHs were all detected at the same sample location (CS-2A). Twenty-three inorganics were detected in 26 sediment samples collected from Mill Creek. Of the potentially site-related metals, maximum detected concentrations in the sediments were as follows: arsenic – 6.3 mg/kg, chromium – 22.9 mg/kg, lead – 38.3 mg/kg, nickel – 22 mg/kg, and tin – 76.3 mg/kg.

4.1.3 GROUNDWATERGroundwater beneath the facility occurs in two aquifers referred to as the Upper and Lower Aquifers. The Upper Aquifer consists predominantly of clayey sediments, with variable numbers of saturated sand interbeds. For any given location within the Facility, from one to four sand or gravelly sand interbeds may be present. Historic data suggest that the Shallow UA Sand is likely in hydraulic communication with Mill Creek and a portion of the Upper Aquifer outcrops to Mill Creek west of the facility. The Upper Aquifer is not known to be used as a source of potable water. The Lower Aquifer is a thick sequence comprising predominantly sand and gravels and consists of an upper and a lower portion. There are no known active supply wells at or in the immediate vicinity of the facility. Although there is a connection between the Upper and Lower Aquifers, the groundwater analytical results show that groundwater contamination from the Facility has not migrated to the Lower Aquifer.

4.1.3.1 Upper Aquifer ResultsDepending on the constituent, between 123 – 197 separate samples were collected from groundwater from approximately 25 shallow wells in the Upper Aquifer from May 2001 through November 2006. Thirty VOCs were detected in the Upper Aquifer and 24 of these were detected at a frequency greater than 5%. The most frequently detected compounds were chlorobenzene, 1,2-dichlorobenzene, 1.4-dichlorobenzene, and toluene. Eighteen SVOCs were detected in shallow groundwater. Only four SVOCs were detected at a frequency greater than 5% of the samples analyzed. These constituents were aniline, caprolactam, BEHP and 4-methylphenol. Twenty-four out of 26 inorganics were detected in shallow groundwater samples at a frequency greater than 5% of the samples analyzed. Hexavalent chromium was analyzed in seven samples but it was not detected in any of those samples. One PCB, Aroclor 1242, was detected in shallow groundwater; however, it was detected at a frequency less than 5 percent of a total of 123 samples. Twenty pesticides were


detected in shallow groundwater and nine pesticides of these were detected at a frequency greater than 5 percent of the samples analyzed. Beta-BHC, heptachlor epoxide, Endosulfan II, heptachlor, and 4,4’-DDD were the most frequently detected compounds (detected in 29, 14, 17, 14, and 14 samples, respectively. VOCs in the shallow Upper Aquifer are generally highest in the northwestern area of the site. In the deeper Upper Aquifer, VOC concentrations are generally higher in the northeastern area of the site; however, the most frequently detected VOCs in the deeper Upper Aquifer (1,1-dichloroethane, 1,2-dichloroethane, tetrachloroethene, trichloroethene and vinyl chloride) are associated with off-site sources (Geomatrix, 2004). The measured concentrations of SVOCs in the shallow Upper Aquifer were generally limited to the northwestern area of the site; and in the deep Upper Aquifer, the measured concentrations of SVOCs were generally non-detect. For metals, in both the shallow and deep Upper Aquifers, measured concentrations were generally highest in the northwestern and north-central portions of the site. Additional groundwater sampling was conducted at the facility from 2007 – 2010 and in 2012 and 2016. The groundwater samples were analyzed for VOCs, SVOCs, and metals. USEPA approved elimination of pesticides and PCBs from the groundwater monitoring program after the 2004 sampling event due to a general lack of detections and because neither are site-related compounds. In the shallow Upper Aquifer sands, the groundwater flow across the site is generally to the west towards Mill Creek and southwest toward the groundwater extraction well, with a steeper gradient in the eastern portion of the site. In the deep Upper Aquifer sands, the groundwater flow on the western and east central portions of the site are toward a central trough. These hydraulic gradients have been consistent throughout the groundwater monitoring events.

4.1.3.2 Lower Aquifer ResultsThe Lower Aquifer has been evaluated throughout the area of the Facility, including on-site during the course of the Pristine Remedial Investigation. Prior to the commencement of the FI, seven Pristine Lower Aquifer wells were present in three well clusters on the Facility, with additional Lower Aquifer wells off site near the property line.Historical sampling has not indicated impact to the Lower Aquifer by Site operations. Despite this, the USEPA expressed concerns in scoping meetings for the RFI that the limited analyte list used for Pristine sampling may not have fully evaluated the presence or absence of such impact. To resolve these concerns, three Lower Aquifer wells were installed in the northwestern portion of the Facility immediately to the north of the former surface impoundments (SWMU 1). This area was selected for several reasons:

It was the location of the surface impoundments, where large quantities of process wastewater were managed. If significant releases to groundwater had occurred, this was considered to be a likely source area.

The Lower Aquifer is shallower in this area than in any other portion of the Facility. Its depth at this location is only approximately 50 feet, compared to typical depths ranging from 90 to 120 feet in other areas of the Facility. This would make this area of the Lower Aquifer most vulnerable to impact from surficial or near-surface releases.

This area represented a data gap for the Lower Aquifer. Pristine wells were already present in and near the northeast, southeast, and southwest areas of the Facility, so wells in the northwest would complete the monitoring coverage.


Based on analytical results from these Lower Aquifer monitoring wells (LAW05-60, LAW05-150, and LAW12-60), impact from the Facility has not reached the Lower Aquifer. Impact was observed from a number of typical Pristine constituents, including chloroethenes and chloroethanes, which were correlated to the interpreted extent of the Pristine Lower Aquifer plume (Geomatrix, 2004).There were two detections of constituents that, at other locations, have been interpreted to represent possible impact from historical or current Facility operations: chlorobenzene and acetone. The chlorobenzene detection, in well LAW12-60, was a qualified detection at less than 1 μg/L and was not reproduced in a second sampling event. Acetone detections in LAW12-60 samples were nearly as low, at 0.55 and 2.3 μg/L (both qualified detections). Elevated tin has not been observed in any Lower Aquifer sample. In summary, no constituents were detected in the Lower Aquifer at levels that would indicate impact by site-related constituents (Geomatrix, 2004).

4.1.3.3 Groundwater Flow ModelA groundwater flow model was developed for the former Rohm and Haas site. The purpose of this groundwater modeling was to:

1) Quantify current groundwater flow conditions in all three aquifers: The Upper Aquifer Shallow (UAS), the Upper Aquifer Deep (UAD), and the Lower Aquifer (LA).

2) Gain a comprehensive understanding of the groundwater/surface water interactions between the UAS and Mill Creek.

3) Determine loading rate and expected concentrations of COCs in the creek.4) Simulate contaminant transport in the flow model to represent present day conditions.

Using data from multiple previous investigations and a 3-dimensional data visualization (3DVA) model developed by Parsons in 2017, the groundwater model was developed, constructed, and calibrated to simulate steady state groundwater flow conditions. Once target calibration parameters were achieved, the creek was split into several zones within the region of the groundwater plume to estimate the groundwater discharge to the creek. The groundwater discharge values were used to calculate the rate at which chlorobenzene would enter the Mill Creek, and the expected chlorobenzene concentrations within the creek. Chlorobenzene was used as a surrogate of the plume due to its detected concentrations (as of December 2016), number of wells with concentrations, and its proximity to the stream. In addition, the model was used to simulate contaminant transport to represent present day groundwater plume conditions. This analysis included simulating the plume in a 1-dimensional model to observe the predicted longevity of the plume under monitored natural attenuation in downgradient monitoring well MW-EPA-1, as well as for comparison to the MODFLOW 3-dimensional transport model.Parameters used for the model were based on known values for chlorobenzene and site geology. The model was developed and validated using steady-state input parameters. These inputs are average values that best represent the standard flow conditions over a long period of time. After development and validation, the transport of contaminate was simulated under transient conditions that represented the maximum potential for stream impact. Concentrations were added at 10 milligrams per liter (mg/L) for the first 30 years of simulation (representing manufacturing start date to the closure of the surface impoundments, 1950-1980), and then dropped to 6 mg/L from 1980 to 2016 in order to achieve current plume concentrations.As part of the modeling analysis, a scenario in which the slurry wall was removed from the model was tested. This evaluation was to determine the slurry wall’s effect on plume transport and the potential ramifications of removing the wall. Based on assumptions and model parameters the following results were observed:


a) Groundwater particle tracking indicated that shallow groundwater in the UAS in the area of interest does discharge to the creek. Particles travel across the site from East to West with an average velocity of 4.5 feet per day.

b) There is no indication from the groundwater model that groundwater flow is going west of Mill Creek. All particles traveled across the UAS and discharged into the creek.

c) The lowest reported value for Mill Creek stream flow is 5.3 cubic feet/second (Geomatrix, 2000). Assuming the mixing zone (groundwater/surface water interface) is on the eastern portion of the stream, then only approximately half of the stream flow is available for dilution resulting in approximately 2.65 cubic feet/second. The resulting expected concentration for chlorobenzene is 0.014 mg/liter, or 14 micrograms/liter (µg/L), which is below the OEPA outside the mixing zone average (OMZA) standard of 47 µg/L for the protection of aquatic life.

d) The1-dimensional model indicated chlorobenzene concentrations in MW-EPA-1 will fall below the drinking water maximum contaminant level of 100 µg/L in approximately 30 years.

e) The slurry wall has very little effect on groundwater flow and the groundwater plume in the groundwater model.

f) The contaminant transport model supported the conclusions made from the flow model, indicating no concentrations are traveling West of Mill Creek.

4.1.4 GROUNDWATER USEUntil 1994, the City of Reading derived its municipal water supply from two well fields near the former ROH Facility; one approximately 500 feet to the north, the other approximately 1600 feet south-southwest. These well fields were closed after chlorinated solvents attributable to off-site sources were detected. Since 1994, Reading has obtained potable water from the City of Cincinnati. One Lower Aquifer supply well is known to have been historically present in the southwest area of the Facility, near the current location of Building 40. This well was reportedly abandoned in the 1970s. The cities of Glendale, Lockland, and Wyoming, which are all within three miles of the former ROH Facility, currently use the lower portion of the Lower Aquifer for potable water. The groundwater is also used by industries in the area. Groundwater is not known or suspected to be used for domestic water supplies in the immediate vicinity of the Facility. Municipal water supply is available to all residential users in the area. There are no drinking water source water protection areas located within the vicinity of the Site.

4.2 ECOLOGICAL RISK ASSESSMENTA Screening Level Ecological Risk Assessment (SLERA) was performed by Parsons for the former ROH Facility in 2010. The goal of the SLERA was to determine whether constituents suspected to be derived from the Facility posed a potential risk to plants, animals, and ecologically valuable habitats in the vicinity of the Facility.The SLERA report identified and analyzed the following:

Potential ecological receptors, including sensitive and protected species, wetlands and water bodies, and natural areas in the Site vicinity;

Constituent sources, affected media, and constituents of potential ecological concern (COPECs); and

Potential exposure pathways for plants and animals.The former ROH Facility operational area (excluding the recreational fields) was mostly covered with buildings/structures or asphalt when operational. Little vegetation existed to support wildlife


populations and what there was supported a diversity of wildlife species tolerant of human activities. The distinct upland vegetation plant communities identified within the vicinity of the Facility included successional old field and riparian forest. The successional old field was identified along the western fence line of the Site and south of the Site, but only comprised approximately 0.4 acre on the Site itself. It was dominated by panic grasses (Panicum sp.) and goldenrods (Solidago sp.). Other herbs that occurred in lesser abundance include yellow sweet clover (Melilotus officinalis), Queen Anne’s lace (Daucus carota), and teasel (Dipsacus sylvestris). The cover type was periodically disturbed, especially near the park which borders the southern and western portion of the facility and will likely remain in an early successional state. The successional old field serves as wildlife habitat that provides edge, cover and food. Songbirds and mammalian species, such as goldfinches (Carduelis tristis), song sparrows (Melospiza melodia), white-footed mice (Peromyscus leucopus), and meadow voles (Microtus pennsylvanicus), which consume the seeds of grass and forbs, are typically observed in these areas. With an abundant prey base, carnivores, such as red fox (Vulpes vulpes), may also reside in the area. A narrow riparian forest was also located along the banks of Mill Creek with approximately 0.2 acres of this habitat type actually on the Site. The dense canopy was dominated by red maple (Acer rubrum), box elder (Acer negundo), sycamore (Platanus occidentalis), and cottonwood (Populus deltoides) trees. The understory varied in density and was dominated by tartarian honeysuckle (Lonicera tatarica) and sandbar willow (Salix interior). The ground layer was sparse due to the lack of sunlight penetration. The predominant species noted in the ground layer included reed canary grass (Phalaris arundinacea) and goldenrods. The riparian corridor provides habitat for many animals because of the seasonal or perennial presence of water. This water is likely used directly for drinking by animals in the general area. Pooled water (relatively still water along the creek banks), which is essential for breeding populations of amphibians, was not observed. The creek banks are relatively steep in the vicinity of the Site with consistently flowing water. No state or federally listed endangered, threatened species or species of concern have been documented to occur within 2 miles of the former ROH Facility.

4.2.1 FATE AND TRANSPORTA variety of physiochemical and site-specific factors influence the fate and transport of chemicals in the environment. VOCs, SVOCs (primarily PAHs) and inorganic constituents were detected at the Facility.VOCs released to soils can be volatilized to the air, transported to surface waters by runoff, and transported to groundwater by leaching. VOCs tend to volatilize readily from surface water to the atmosphere, and once released, they photodegrade rapidly. In surface waters and soil, some of these compounds are also readily biodegraded by microbes.PAHs are SVOCs that are regarded as persistent in the environment but are also degradable by microorganisms. Degradation is influenced by factors such as temperature, pH, redox potential, microbial species present, chemical structure, concentration and lipophilicity.The fate and transport of metals are largely determined by their low water solubility and tendency to bind to clays, organic matter, and iron and manganese hydroxides in soil and sediment. Metals are generally persistent in soil and sediment and not in groundwater and surface water. Metals can mobilize from the soil into the water column and are most mobile under acidic conditions. Increasing pH usually reduces their bioavailability.


4.2.2 CHEMICALS OF POTENTIAL ECOLOGICAL CONCERNCOPECs were identified by comparing available data on chemical concentrations found in various media with conservative ecological screening values derived by USEPA Region 5 and OEPA. Potential risks posed by each chemical of concern were then evaluated by calculating a hazard quotient (the ratio of media chemical concentration to a screening value) for each contaminant. Hazard quotients greater than 1 indicates a potential risk of adverse effects may exist and further evaluation may be necessary. Due to the limited extent of habitat in the former operational area, the frequency and duration of exposure for terrestrial receptors exposed to contaminants in soil is minimal, thus, exposure pathways were incomplete and further evaluation of soil for ecological receptors was not completed.Thirty sediment samples were collected from along the east bank of Mill Creek and the creek bed sediments and analyzed for VOCs, SVOCs, pesticides, PCBs and metals. The maximum detected concentration of each constituent was compared to the Region 5 Ecological Screening Levels (ESLs) or surrogate values if a Region 5 ESL was unavailable. One VOC (acetone), 19 SVOCs including 16 PAHs, and two metals (lead and tin) were identified as COPECs in the sediment of Mill Creek. The range of detected concentrations of PAHs were similar to concentrations detected throughout the sediments of the Mill Creek as collected and analyzed by the OEPA (OEPA, 2004) and therefore the PAH concentrations detected in the sediments adjacent to the site are consistent with those detected in background locations and were not evaluated further. Likewise, the low detected concentrations of acetone were attributed to laboratory interference based on acetone concentrations detected in laboratory blank samples. Further evaluation of metals and SVOCs in the sediments did not identify potential risk due to the detected concentrations of COPECs in the sediment of Mill Creek based on food web modeling, thus, sediments were eliminated as a medium of concern for ecological receptors. Seven surface water samples (including one duplicate) were collected from within Mill Creek and analyzed for VOCs, SVOCs, pesticides, PCBs and metals. Since ecological receptors are exposed to water as it comes from the ground, results were compared to unfiltered water samples. This is also a more conservative approach since most criteria are published as dissolved concentrations. The maximum detected concentration of each constituent was compared to the Region 5 ESLs and OEPA aquatic life criteria for outside the mixing zone average (OMZA). Based on this comparison, no COPECs in surface water were identified and surface water was eliminated as a medium of concern for aquatic life.The potential for groundwater to discharge to the surface water of Mill Creek was also evaluated for potential risk to aquatic life. Although not currently a pathway of concern based on the data collected directly from the Mill Creek and the operation of a French Drain that collects groundwater from the shallow upper aquifer, this pathway was a potential concern in the future. Therefore, the maximum detected concentrations of constituents in groundwater were compared to Ohio surface water criteria for OMZA concentrations (or Region 5 ESLs if OMZA were unavailable) to identify COPECs in shallow groundwater, which included VOCs, SVOCs, and metals. Fourteen chemicals detected in sitewide groundwater exceeded surface water quality criteria, including four compounds that were detected in groundwater but did not have a screening level for comparison. Overall, the estimated risks to ecological receptors are thought to have minimal ecological significance due to the limited toxicity of the detected compounds to the ecological receptors, the elevated concentrations in background samples, the urbanized setting of the surrounding area, and the operation of a French Drain that collects groundwater prior to discharge into the Mill Creek. Therefore, the SLERA adequately assessed the risks to ecological receptors. However, further assessment of the groundwater to surface water migration pathway and potential effect on the


sediments and surface water of Mill Creek was recommended to evaluate the design and implementation of Corrective Measures, particularly the necessity of the continued operation of the groundwater extraction system.

4.3 HUMAN HEALTH RISK ASSESSMENTA human health risk assessment (HHRA) was also conducted to identify potential adverse effects to humans. The assessment was based on the assumption that the former operational area of the Facility will remain a commercial/industrial facility and a recreational area for the 7-acre ball fields for the foreseeable future. Future residential use is currently prohibited via an environmental covenant recorded with Hamilton County on June 25, 2018 between 2000 West Property LLC and the OEPA.

4.3.1 CHEMICALS OF POTENTIAL CONCERNChemicals of potential concern (COPCs) were identified for each medium by comparing maximum detected concentrations to risk-based screening criteria and background levels.

4.3.1.1 SoilCOPCs for soil were identified by comparing concentrations detected during the RFI to the lower of the risk-based screening levels for groundwater protection (i.e., soil leaching to drinking groundwater) and Regional Screening Levels (RSLs) for both residential and industrial land use. Residential RSLs were used to evaluate data from the recreational ball fields while industrial RSLs were used to evaluate data and receptors for the former operational area. Comparison to groundwater protection levels identified chemicals that may pose a potential risk as a result of their migration from soil to groundwater. Comparison to RSLs identified chemicals that may pose a potential risk as a result of direct contact by humans with the affected soil. Sixteen COPCs were identified in soil for the industrialized area: acetone, benzene, chlorobenzene, methylene chloride, toluene, benzo(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, BEHP, 1,2-dichlorobenzene, 1,4-dichlorobenzene, Aroclor 1254, endrin, antimony, arsenic and chromium. Benzo(a)pyrene and arsenic were the only identified COPCs for a recreational ball field user. These COPCs were retained for further evaluation in the HHRA.

4.3.1.2 GroundwaterChemicals detected in groundwater were compared to federal Maximum Contaminant Levels (MCLs) for drinking water, or to USEPA RSLs for tap water if an MCL was not available. Chemicals detected in groundwater were considered COPCs if the maximum concentrations exceed the MCL or, in the absence of an MCL, the RSL. As a result, the following COPCs were identified in groundwater: acetone, benzene, chlorobenzene, chloroform, 1,2-dichlorobenzene, 1,4-dichlorobenzene, 1,2-dichloroethane, methylene chloride, tetrachloroethene, toluene, trichloroethene, vinyl chloride, aniline, BEHP, 4-methylphenol, beta-benzene hexachloride (beta-BHC), delta-BHC, 4,4’-dichlorodiphenyldichloroethylene (DDE), gamma-BHC, dieldrin, heptachlor, heptachlor epoxide, aluminum, antimony, arsenic, cadmium, chromium, copper, iron, lead, manganese, nickel, thallium, and vanadium. The potential risk associated with migration of impacted groundwater to surface water was also evaluated for the site. Additional screening was performed to determine COPCs for the potential for migration of impacted groundwater to surface water. The concentrations detected in groundwater were compared to the most conservative surface water screening value available [2009 National


Recommended Water Quality Criterion (NRWQC), 2010 MCL, 2010 RSLs for tap water, or 2009 OEPA Tier I/II surface water screening criteria]. Results of this comparison identified a similar list of COPCs in groundwater: 1,1,2-trichloroethane, 1,2-dichlorobenzene, 1,4-dichlorobenzene, 1,1-dichloroethane, 1,2-dichloroethane, benzene, bromodichloromethane, carbon tetrachloride, chlorobenzene, chloroform, methylene chloride, tetrachloroethene, toluene, trichloroethene, vinyl chloride, 2-methylnaphthalene, aniline, BEHP, naphthalene, aluminum, antimony, arsenic, cadmium, chromium, cobalt, iron, lead, manganese, nickel, thallium, and vanadium. Thus, an additional comparison to OEPA Ohio River Basin human health surface water screening levels was performed for compounds detected in groundwater.For compounds detected in the groundwater samples, seven compounds (1,1-dichloroethene, chlorobenzene, trans-1,2-dichloroethene, 2-chlorophenol, mercury, selenium and silver) had lower OEPA screening levels than the NRWCC, MCL or RSLs. Of these seven compounds, only the maximum detections of 1,1-dichloroethene, 2-chlorophenol and mercury exceeded the OEPA surface water criteria for drinking water. Note that the maximum detections of 1,1-dichloroethene and 2-chlorophenol did not exceed the OEPA surface water criteria for human health non-drinking water sources. The non-drinking water criteria are more applicable to the Mill Creek based on its current water supply designation by the state for agricultural and industrial water supply use only. When compared to OEPA human health screening values for non-drinking water uses, only mercury was identified as an additional compound of concern. However, mercury was eliminated as a compound of potential concern because mercury is not a site-related constituent of concern.

4.3.1.3 Surface WaterSix surface water samples were collected from Mill Creek and compared to federal MCLs or USEPA RSLs for tap water if an MCL was not available. Two COPCs were identified in surface water based on comparison to drinking water screening levels: dibromochloromethane and thallium. Additionally, potential site-related bioaccumulative inorganic compounds that were detected in surface water below drinking water screening levels were retained as COPCs for a fish ingestion pathway scenario. Thus, arsenic, copper and zinc were identified as COPCs for a potential fish ingestion pathway.

4.3.1.4 SedimentHuman health risk-based screening criteria do not exist for sediment. However, RSLs for soils were used to identify COPCs in sediment. Given the off-site location of the sediment in Mill Creek and the local residential area, industrial screening criteria were not considered appropriate for sediments. Therefore, any chemical detected in sediment was considered a COPC if its maximum detected concentration exceeded the soil RSL for residential land use or the soil screening level for groundwater protection. As a result of this comparison, benzo(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, dibenzo(a)anthracene, beta-BHC, dieldrin and arsenic were considered COPCs in sediment. In addition, potentially bioaccumulative organic compounds in sediment were identified as COPCs for a fish ingestion pathway scenario.

4.3.2 EXPOSURE ASSESSMENTAn analysis of potential risk depends on the mechanisms by which people might come in contact with COPCs at the Facility. This includes a characterization of the physical environment and potential receptors, identification of exposure pathways (potential source, points of release), and quantification of specific exposure pathways (exposure concentrations and intake assumptions). The types of activities that might occur at a site and the mechanisms that result in migration of chemicals determine potential exposure to chemicals.


This assessment assumed that the Facility will continue to operate as an industrial/commercial facility for the main manufacturing area and as a recreational area for the ball-fields. Residential use was not considered in the risk assessment based on the historical industrial use and zoning of the site and surrounding area. Additionally, residential use is now prohibited via an environmental covenant recorded with Hamilton County on June 25, 2018 between 2000 West Property LLC and the OEPA. Groundwater is not known or suspected to be used for domestic water supplies in the immediate vicinity of the facility and municipal water supply is available to all residential users in the area. There are no drinking water source water protection areas are located within the vicinity of the site.Several exposure scenarios were considered in the risk assessment. Onsite receptors include industrial workers involved primarily with outdoor activities, industrial workers who spend most of their day indoors, and construction workers. Potential off-site receptors include individuals residing or working down-gradient of the facility, individuals using Mill Creek for recreational purposes, such as fishing, swimming, or wading, and recreational users at the adjacent ball fields. The creek and the ball field recreational users were evaluated quantitatively. For the purpose of risk assessment, offsite residents were evaluated qualitatively.Points of potential human contact with chemicals are on-site soil, on-site groundwater, on-site air, off-site air, off-site (ball fields) soil, off-site surface water in Mill Creek, sediment from Mill Creek and ingestion of fish from Mill Creek. Air exposure point concentrations were estimated using fate and transport models based on concentrations of chemicals in soil and groundwater. Fish tissue concentrations were estimated using bioaccumulation models based on concentrations of chemicals in surface water and sediment.

4.3.3 RISK ANALYSISUSEPA has utilized the acceptable exposure level, or “risk goal”, defined within the National Contingency Plan (NCP) for site cleanup decisions. The NCP defines the acceptable excess upper lifetime cancer risk as generally a range between 1E-6 and 1E-4, with a point of departure of 1E-6 used for screening purposes. For non-carcinogens, the site risk assessment screening uses a Hazard Quotient (HQ) of 0.1 for individual constituents of concern and final remedial goal of cumulative hazard index (HI) not to exceed 1.0. OEPA’s remedial program uses a similar state specific approach. The remedial programs use the same screening level risk goals but has adopted a final remedial excess cancer risk goal of 1E-5. It is important to note these values are goals to aide in the remedy selection process. While some risk values may for this Facility may exceed the OEPA screening level risk goal, the exceedance is minimal and still within the USEPA risk range.

4.3.3.1 NoncancerPotential noncarcinogenic and carcinogenic effects were evaluated for specific pathways and potential receptors. Toxicity criteria were selected from relevant USEPA sources. Potential adverse noncarcinogenic health effects were evaluated using the hazard index approach. This approach compares estimated daily intakes of each chemical to the appropriate reference dose, and then sums the individual chemicals which may have additive effects to develop a hazard index. The noncarcinogenic hazard indices calculated for both onsite industrial and onsite construction workers were below the target hazard index of 1. Therefore, adverse health effects are not expected as a result of onsite exposure to chemicals in soils or groundwater. The potential noncancer hazard quotients and hazard indexes associated with exposure to the COPCs in surface soil near the ball fields by a child recreational user is less than 1, indicating that exposure


to chemicals in surface soil near the ball fields would not result in unacceptable noncarcinogenic health effects under the conditions evaluated.Noncarcinogenic risks for recreational users (adult and child) of the Mill Creek were also well below the target hazard index of 1. Therefore, adverse health effects are not expected as a result of exposure to chemicals in the surface water or sediments of the creek. The potential noncancer hazard quotients and hazard indexes associated with exposure to the COPCs in fish and via incidental ingestion and dermal contact with surface water and sediments by an adult recreational fisherman are also below the target level of 1. Thus, adverse health effects are not expected as a result of exposure to chemicals in fish tissue from the creek.The potential hazard index associated with exposure to airborne COPCs as a result of fugitive dust and volatile emissions for an off-site residential receptor was not calculated. Based on the low contribution of the inhalation pathway to the hazard index for the outdoor industrial worker at the Facility, the potential hazard index for offsite residential receptors is also considered to be well below one, as a result of dispersion of chemicals in air.

4.3.3.2 CancerCarcinogenic risks are defined in terms of the increased possibility of an individual developing cancer as the result of exposure to a given concentration. USEPA’s risk reduction goal is to reduce the threat from carcinogenic contaminants, such that the excess risk of cancer to an individual exposed over a lifetime falls within the range of 1 x 10-6 to 1 x 10-4. However, USEPA prefers to select remedies at the more protective end of the risk range, and generally uses 1 x 10-6 as a point of departure for evaluating risks. The estimated theoretical excess lifetime cancer risk for indoor industrial workers is 1.4 x 10-5 and for outdoor industrial workers is 4.7 x 10-5. Both values are within the acceptable risk range. However, institutional controls have been implemented to maintain the property for industrial/commercial purposes only and ensure that the exposure assumptions remain true. The estimated cancer risk for onsite construction workers is 3.5 x 10-6, which is also within the acceptable risk range. The estimated theoretical lifetime excess cancer risks associated with exposure to the COPCs in surface water and sediments by an adult recreational wader of Mill Creek is 9.7 x 10-7, which is even lower than the acceptable risk range. The estimated theoretical lifetime excess cancer risks associated with exposure to the COPCs in surface water and sediments by a child recreational wader of Mill Creek is 3.7 x 10-6, which is within the acceptable risk range.The estimated theoretical lifetime excess cancer risks associated with exposure to the COPCs in surface soil by a child recreational user age 6-13 at the adjacent ball fields is 2.1 x 10-6, which is within the acceptable risk range. For a child recreational user age 13-17, the total estimated cancer risk is 1.3 x 10-6, which is also within the acceptable risk range of 1 x 10-4 to 1 x 10-6.The estimated theoretical lifetime excess cancer risks associated with exposure to the COPCs in fish and via incidental ingestion and dermal contact with surface water and sediments by an adult recreational fisherman of the creek is 1.2 x 10-4, which is slightly above the acceptable risk range, primarily due to fish ingestion pathway, indicating that exposure via ingestion of fish in the Mill Creek from fishing activities may result in an unacceptable cancer risk under the conditions evaluated for this receptor. The primary chemical of concern is arsenic. Arsenic was detected in only one duplicate sample in surface water; thus, the risk from this compound is likely overestimated based on this low frequency of detection and the utilization of the maximum detected concentration with conservative uptake parameters in the fish tissue modeling.


The potential lifetime excess cancer risk associated with exposure to airborne COPCs as a result of fugitive dust and volatile emissions for an off-site residential receptor was not calculated. Based on the low contribution of the inhalation pathway (3.0 x 10-7, which is less than 1 x 10-6) to carcinogenic risk for the outdoor industrial worker, potential cancer risks for off-site residential receptors are also considered to be well below the acceptable risk range, based on dispersion of chemicals in air.

4.3.4 HHRA CONCLUSIONSResults of the HHRA indicated that the estimated risks and hazards for industrial workers, construction workers, recreational users of Mill Creek, ball field recreational users, and offsite residents are within acceptable target risk ranges and below the target hazard index of 1 for pathways and media evaluated. The estimated theoretical lifetime excess cancer risks associated with exposure to the COPCs in fish and via incidental ingestion and dermal contact with surface water and sediments by an adult recreational fisherman of Mill Creek was slightly above the acceptable risk range, primarily due to fish ingestion pathway. The primary chemical of concern is arsenic. Arsenic was detected in only one duplicate sample in surface water; thus, the risk from this compound is likely overestimated based on this low frequency of detection and the utilization of the maximum detected concentration with conservative uptake parameters in the fish tissue modeling. Based on the results of the RCRA Facility Investigation and risk assessments, the levels of impact to soils and groundwater are low and declining or stable. All risk based on current scenarios were within acceptable bounds as established by the USEPA.

4.4 DUE DILIGENCE SAMPLING OF GROUNDWATER AND SOIL VAPORIn May 2017, Tetra Tech, Inc (Tetra Tech) collected six sub-slab soil vapor samples, six indoor air samples and one outdoor ambient air sample from in/near Building 40, which is located in the southwest portion of the Site. Historical groundwater sampling data collected from monitoring wells that are screened in the shallow aquifer near Building 40 indicated the presence of VOCs that are often associated with vapor intrusion. The samples were collected on behalf of the property owner (QCPOH, Inc.) and were collected to demonstrate that the sub-slab soil vapor and/or indoor air concentrations were below USEPA Vapor Intrusion Screening Levels (VISLs) for industrial/commercial use prior to the lease of Building 40 to a third party tenant. Although VOCs were detected in the samples from each media, there were no detections that exceeded the VISLs for a commercial use scenario (Tetra Tech, 2017). In February 2019, EDG collected groundwater samples from six site wells and analyzed the groundwater samples for VOCs, SVOCs and metals as part of due diligence studies for property transfer. Groundwater concentrations in the samples collected by EDG were similar to the groundwater data collected in 2016 by Dow and the detected concentrations show continued stable and/or decreasing trends for the contaminants of concern.

4.5 PRELIMINARY CORRECTIVE MEASURES EVALUATIONRemedial alternatives must meet several criteria according to OEPA guidance, including the mitigation of unacceptable risks and control of contaminant migration. Historic data and operation of the groundwater extraction system indicate that the migration of contaminated groundwater is currently under control. Natural mechanisms, source control, and source removal appear to have reduced the number, concentration, and extent of site contaminants. Table 1 presents a summary of the identified contaminants of concern in each media of concern, the maximum detected


concentration and the generic remediation goals (RGs) that apply following the completion of the RFI. These generic RGs are given as a cumulative excess lifetime cancer risk of 1 x 10-5 (i.e., 1 in 100,000) and a cumulative non-cancer hazard goal equal to a Hazard Index (HI) of 1. These generic RGs are based on preventing unacceptable human health and environmental risks due to direct contact with contaminated subsurface soil and groundwater and inhalation of vapors from contaminated groundwater.

TABLE 1Medium Final

Contaminant of Concern

Max. Concentrati

on

RG Units RG Basis

Soils: Human Direct Contact – Industrial Exposure Scenario

1,2-Dichlorobenzene 2,800 380 mg/kg Soil Saturation

Arsenic 16.2 15.2 mg/kgSite-Specific Background

Groundwater – Potable Use

1,1-Dichloroethane 6.7 2.8 µg/L Tapwater RSL1,2-Dichloroethane 14 5 µg/L MCL

1,4-Dichlorobenzene 330 75 µg/L MCL

Acetone 38,000 14,000 µg/L Tapwater RSLBenzene 120 5 µg/L MCL

Chlorobenzene 5,200 100 µg/L MCLMethylene Chloride 19 5 µg/L MCLTetrachloroethylen

e 81 5 µg/L MCLTrichloroethene 5.8 5 µg/L MCLVinyl Chloride 6 5 µg/L MCL

Aniline 180 130 µg/L Tapwater RSLBenzo(a)anthracen

e 2.2 0.3 µg/L Tapwater RSLBenzo(a)pyrene 2.1 0.2 µg/L MCL

Benzo(b)fluoranthene 3.1 2.5 µg/L Tapwater RSL

Naphthalene 11 1.7 µg/L Tapwater RSLPentachlorophenol 8.6 1 µg/L MCL

Antimony 18 6 µg/L MCLArsenic 340 10 µg/L MCLBarium 5,300 2,000 µg/L MCL

Cadmium 6.8 5 µg/L MCLChromium 7,700 100 µg/L MCL

Cobalt 18 6 µg/L Tapwater RSLIron 25,000 14,000 µg/L Tapwater RSL


TABLE 1Medium Final

Contaminant of Concern

Max. Concentrati

on

RG Units RG Basis

Manganese 4,700 430 µg/L Tapwater RSLNickel 660 390 µg/L Tapwater RSL

Thallium 3.3 2 µg/L MCLVanadium 250 86 µg/L Tapwater RSL

Groundwater – Vapor Intrusion to Indoor Air – Industrial Exposure Scenario

1,4-Dichlorobenzene 330 22 µg/L

Commercial VISL

Benzene 120 11 µg/LCommercial

VISL

Chlorobenzene 5,200 3,100 µg/LCommercial

VISL

Chloroform 7.3 5.5 µg/LCommercial

VISL

Ethylbenzene 76 28 µg/LCommercial

VISL

Vinyl Chloride 6 3.3 µg/LCommercial

VISL

Groundwater – Groundwater to Surface Water Exposure Aquatic Life – Ohio River Basin Outside the Mixing Zone Average (OMZA)

1,2-Dichlorobenzene 490 230 µg/L OMZA x 10

1,4-Dichlorobenzene 330 94 µg/L OMZA x 10Carbon Disulfide 250 150 µg/L OMZA x 10Chlorobenzene 5,200 470 µg/L OMZA x 10

Aniline 180 41 µg/L OMZA x 10Barium 5,300 2,200 µg/L OMZA x 10

Chromium 7,700 1,500 µg/L OMZA x 10Tin 4,500 1,800 µg/L OMZA x 10

Notes:RSL – Regional Screening Level, November 18, 2019MCL – Maximum Contaminant LevelVISL – Vapor Intrusion Screening Level, USEPA Version 3.5.1, commercial scenarioOMZA – Outside the Mixing Zone Average, OEPA, 1/12/2015

Current risks were determined to be acceptable and do not require further action. Therefore, the proposed alternative must address only future risks, ensuring that current conditions do not change in a manner that would create an unacceptable exposure scenario. Therefore, the final remedy must meet the following criteria:

Concentrations of chemicals in groundwater and the overall extent of impacted groundwater decline;


Onsite land use remains consistent with the commercial/industrial scenario considered in the risk assessments; and

Onsite groundwater remains unused.Continued monitoring of the groundwater using a portion of the existing groundwater monitoring network can achieve the first criterion, assuming natural processes continue to reduce groundwater constituents. The institutional controls already in-place for the Site restrict the placement of any new water wells within the Site. Existing institutional controls also restrict the future use of the former manufacturing area to commercial/industrial use only and building over areas with potential vapor intrusion concerns, thus achieving the second two criteria.


5.0 SCOPE OF REMEDYThe purpose of the proposed remedy is:

To monitor the natural attenuation of contaminants in groundwater To prevent the installation of new drinking water wells at the Site To protect surface water from contaminants in groundwater migrating to Mill Creek To implement institutional controls to establish the future use of the Facility as

commercial/industrial, and To implement institutional controls to establish building criteria to prevent migration of vapors

to indoor air

5.1 INSTITUTIONAL CONTROLSInstitutional controls have been implemented at the Site as part of negotiations between the current property owner and the USEPA and OEPA during transfer of regulatory oversight from the USEPA to OEPA. Future residential use is currently prohibited via an environmental covenant recorded with Hamilton County on June 25, 2018 between 2000 West Property LLC and the OEPA. This environmental covenant also prohibits groundwater underlying the property from being extracted for any purpose, potable or otherwise, except for investigation, monitoring and remediation of groundwater or in conjunction with construction or excavation activities or maintenance of subsurface utilities. In addition, as part of the environmental covenant, the construction of new buildings on the Property are prohibited unless an OEPA approved vapor mitigation system is installed or OEPA confirms that soil gas concentrations are below vapor intrusion screening levels. Additionally, occupancy of existing buildings on the Site is restricted until OEPA approves of a vapor intrusion evaluation to determine if the building should be retrofitted with a vapor barrier system. The environmental covenant also limits the current owner from interfering with the operation and maintenance of the groundwater extraction system while Corrective Actions are being implemented.

5.2 GROUNDWATER EXTRACTION SYSTEMA French drain groundwater recovery system (SWMU 6) was installed in 1985 along the western Site boundary to intercept groundwater flow that otherwise would reach Mill Creek. A concrete slurry wall was constructed at the north end of the French drain near the property boundary to prevent the French drain from drawing groundwater from properties immediately to the north. A 4-inch recovery well was installed at the former location of a swale. The combined flow from the groundwater recovery well and the French drain system were treated with hydrogen peroxide and was permitted for discharge to the Cincinnati Metropolitan Sewer District (MSD) from the time the system was installed to May 1992. Use of the recovered groundwater for in-plant process purposes was started in the early 1990’s.The recovered groundwater was treated at the Facility prior to use for plant processes. The nature of the pre-use treatment was modified several times over the years. The groundwater recovery system is equipped with a pump with a nominal rating of 10 gallons per minute (gpm) for the combined flow from both the recovery well and the French drain. Since the Site was dismantled, extracted groundwater has been directly discharged to MSD. The groundwater recovery rate in 2012 averaged 4.7 gpm [6,770 gallons per day (gpd), 905 cubic feet per day (ft3/d)]. In 2013, an evaluation was


conducted to determine the potential impact of ceasing operation of the groundwater recovery system (Parsons, 2013). The groundwater flux to Mill Creek has been estimated in several previous evaluations of the site. For the 2013 evaluation of the system, the flux into Mill Creek was estimated using the observed saturated thickness of approximately 6 feet, the lower hydraulic gradient (0.019 ft/ft) observed in the vicinity of Mill Creek, and the lower estimate of hydraulic conductivity (20 ft/day) that Geomatrix noted for the western area of the site based on the testing of the French drain (Geomatrix 2004). Thus, the flux to Mill Creek was estimated at approximately 806 ft3/d (6,030 gpd). This groundwater flux represents approximately 0.007 percent of the mean flow of Mill Creek (12,000,000 ft3/d) and approximately 0.2 percent of the 7Q10 flow (423,000 ft3/d [3,160,000 gpd]) of Mill Creek. This scenario also fits the available information on the hydraulics of the site and is in-line with the average groundwater recovery of 905 ft3/day recorded in 2012. The conclusion of the evaluation, based on estimated surface water concentrations in Mill Creek, is that the effect of shutting down the groundwater extraction system would have no discernible effects on the concentrations of constituents detected in the creek, even during low flow conditions, due to the low groundwater flux rate observed at the Site and concentrations of contaminants of concern present in the surface water from upstream sources.

5.3 3-DIMENSIONAL GROUNDWATER FLOW MODELA 3DVA groundwater flow model was developed and a Groundwater Model Report was submitted to OEPA in March 2020. The purpose of the 3DVA model was to calculate the rate at which chlorobenzene, used as a surrogate of the plume due to its detected concentrations (as of December 2016), number of wells with concentrations, and its proximity to the stream, would enter the Mill Creek, and the expected chlorobenzene concentrations within the creek. In addition, the model was used to simulate contaminant transport to represent present day groundwater plume conditions.Parameters used for the model were based on known values for chlorobenzene and site geology. As part of the modeling analysis, a scenario in which the slurry wall was removed from the model was also tested. This evaluation was to determine the slurry wall’s effect on plume transport and the potential ramifications of removing the wall. Based on assumptions and model parameters, groundwater from UAS at the Site does discharge to the Mill Creek. However, there is no indication groundwater flow is going beyond Mill Creek to the west. As there is no groundwater flow going beyond Mill Creek, there are no concentrations of Site contaminants traveling beyond Mill Creek to the west. The resulting expected concentration for chlorobenzene entering Mill Creek is 14 µg/L, which is below the OEPA outside OMZA standard of 47 µg/L. In addition, the1-dimensional model indicated chlorobenzene concentrations in MW-EPA-1 will fall below the drinking water MCL of 100 µg/L in approximately 30 years due to natural attenuation. Lastly, any future removal of the slurry wall should very little effect on groundwater flow and the groundwater plume.The conclusion of this modeling indicates surface water will not be adversely impacted from contaminants in groundwater migrating to Mill Creek above the OEPA OMZA water quality standard.

5.4 MONITORED NATURAL ATTENUATIONIn addition to institutional controls, monitored natural attenuation will be utilized to demonstrate a clear and meaningful trend of decreasing and/or contaminant mass and concentration over time. Data collected since 2001 already indicates that the concentrations of contaminants detected in


groundwater are decreasing. Maximum concentrations have also declined from historical highs, and the number of compounds detected in groundwater has decreased as well. Therefore, natural mechanisms and source elimination activities appear to be meeting the objective of restoring impacted waters.To further evaluate natural attenuation, chlorobenzene concentrations were used as a surrogate of the existing groundwater plume and added to the groundwater flow model discussed in Sections 4.1.3.3 and 5.3. The concentrations were used to simulate the existing groundwater plume conditions at the Site, as of December 2016 and calculate future expected concentrations when allowing for natural attenuation. The model indicated chlorobenzene concentration in MW-EPA-1 will fall below the drinking water MCL of 100 µg/L on approximately 30 years, supporting the use of monitored natural attenuation as a viable remedy for the Site.


6.0 SUMMARY AND EVALUATION OF POSSIBLE REMEDYThe following is a description and evaluation of the possible remedy considered for this Statement of Basis.

6.1 EVALUATION OF TECHNOLOGIES The following criteria were used by the OEPA in evaluating the remedy:

Overall Protection – technology must provide adequate protection of human health and the environment,

Restoration of impacted groundwater, Controlling the sources of releases, Prevention of plume migration, Long and short term reliability and effectiveness, Reduction of toxicity, mobility, or volume of wastes, Implementability, and Cost

CRITERIA USED TO EVALUATE REMEDIAL ALTERNATIVES The overarching objective of corrective action activities is to reduce, eliminate or otherwise manage risk posed by contamination at the site. In developing the array of those alternatives represented within the CMS Report the following considerations was used as the basis for OEPA’s selection of their preferred alternative(s):

a) Reliability. Alternatives that minimize or eliminate the potential for release of hazardous wastes and constituents into the environment will be considered more reliable than other alternatives. For example, recycling of waste and off-site incineration would be considered more reliable than land disposal. Institutional concerns such as management requirements can also be considered as reliability factors.

b) Implementability. The requirements for implementing the alternatives will be considered, including phasing alternatives into operable units and segmenting alternatives into project areas on the site. The requirements for permits, zoning restrictions, rights of way and public acceptance are examples to be considered.

c) Effects of the Alternative. The alternative posing the greatest improvement to (and least negative impact on) public health, welfare and environment will be favored.

d) Safety Requirements. The alternatives with the lowest adverse safety impacts will be favored.

e) Whenever two or more alternatives are identified as meeting the site remedial response objectives, the lowest cost alternative that is technologically feasible and reliable and which effectively mitigates and minimizes damage to and provides adequate protection of public health, safety, or the environment will be the selected alternative. Total cost includes implementation of the alternative and the operation and maintenance of the proposed alternative.

In addition to the criteria above, OEPA considers the final remedial alternative must meet five criteria. The first four have become known as the “threshold criteria.” The fifth criteria have, in usage, become known as the “balancing criteria” and is used to assist in selecting one of several remedies which meet the threshold criteria. The elements of each of these criteria are listed below. Criteria for Evaluation of Corrective Measures (or Remedial Alternatives)


1) Protect human health and the environment Corrective measures must be protective of human health and the environment. Remedies may include those measures that are needed to be protective but are not directly related to media cleanup standards, source control, or management of wastes. An example would be a requirement to provide alternative drinking water supplies in order to prevent exposures to releases from an aquifer used for drinking water purposes. Another example would be a requirement for the construction of barriers or for other controls to prevent harm arising from direct contact with waste management units.

2) Attain Media Cleanup Standards Set by the Implementing Agency Remedies will be required to attain media cleanup standards set by the implementing agency which may be derived from existing state or federal regulations (e.g. ground water standards) or other standards. The media cleanup standards for a remedy will often play a large role in determining the extent of and technical approaches to the remedy. In some cases, certain technical aspects of the remedy, such as the practical capabilities of remedial technologies, may influence to some degree the media cleanup standards that are established.

3) Control the Sources of Releases A critical objective of any remedy must be to stop further environmental degradation by controlling or eliminating further releases that may pose a threat to human health and the environment. Unless source control measures are taken, efforts to clean up releases may be ineffective or, at best, will essentially involve a perpetual cleanup. Therefore, an effective source control program is essential to ensure the long-term effectiveness and protectiveness of the corrective action program.” The source control standard is not intended to mandate a specific remedy or class of remedies. Instead, the Permittee/Respondent is encouraged to examine a wide range of options. This standard should not be interpreted to preclude the equal consideration of using other protective remedies to control the source, such as partial waste removal, capping, slurry walls, in-situ treatment/stabilization and consolidation.

4) Comply with Any Applicable Standards for Management of Wastes The Permittee/Respondent shall include a discussion of how the specific waste management activities will be conducted in compliance with all applicable state or federal regulations (e.g., closure requirements, land disposal restrictions).

5) Other Factors (Balancing Criteria) There are five general factors that will be considered as appropriate by the implementing agency in selecting/approving a remedy that meets the four standards listed above. These factors represent a combination of technical measures and management controls for addressing the environmental problems at the facility. The five general factors include:a) Long-term Reliability and Effectiveness Demonstrated and expected reliability is a way of assessing the risk and effect of failure. The Permittee/Respondent may consider whether the technology or a combination of technologies have been used effectively under analogous site conditions, whether failure of any one technology in the alternative would have an immediate impact on receptors, and whether the alternative would have the flexibility to deal with uncontrollable changes at the site (e.g., heavy rain storms, earthquakes, etc.). Most corrective measure technologies, with the exception of destruction, deteriorate with time. Often, deterioration can be slowed through proper system operation and maintenance, but the technology eventually may require replacement. Each corrective measure alternative should be evaluated in terms of the projected useful life of the overall alternative and of its component technologies. Useful life is defined as the length of time the level of effectiveness can be maintained.” b) Reduction in the Toxicity, Mobility or Volume of Wastes


As a general goal, remedies will be preferred that employ techniques, such as treatment technologies, that are capable of eliminating or substantially reducing the inherent potential for the wastes in SWMUs (and/or contaminated media at the facility) to cause future environmental releases or other risks to human health and the environment. There may be some situations where achieving substantial reductions in toxicity, mobility or volume may not be practical or even desirable. Examples might include large, municipal-type landfills, or wastes such as unexploded munitions that would be extremely dangerous to handle, and for which the short-term risks of treatment outweigh potential long-term benefits. Estimates of how much the corrective measures alternatives will reduce the waste toxicity, volume, and/or mobility may be helpful in applying this factor. This may be done through a comparison of initial site conditions to expected post-corrective measure conditions.” c) Short-term Effectiveness Short-term effectiveness may be particularly relevant when remedial activities will be conducted in densely populated areas, or where waste characteristics are such that risks to workers or to the environment are high and special protective measures are needed. Possible factors to consider include fire, explosion, exposure to hazardous substances and potential threats associated with treatment, excavation, transportation, and re-disposal or containment of waste material.”d) Implementability Implementability will often be a determining variable in shaping remedies. Some technologies will require state or local approvals prior to construction, which may increase the time necessary to implement the remedy. In some cases, state or local restrictions or concerns may necessitate eliminating or deferring certain technologies or remedial approaches from consideration in remedy selection. Information to consider when assessing implementability may include: The administrative activities needed to implement the corrective measure alternative (e.g., permits, rights of way, off-site approvals, etc.) and the length of time these activities will take; the constructability, time for implementation and time for beneficial results; the availability of adequate off-site treatment, storage capacity, disposal services, needed technical services and materials; and the availability of prospective technologies for each corrective measure alternative.e) Cost The relative cost of a remedy may be an appropriate consideration, especially in those situations where several different technical alternatives to remediation will offer equivalent protection of human health and the environment but may vary widely in cost. However, in those situations where only one remedy is being proposed, the issue of cost would not need to be considered. Cost estimates could include costs for: engineering, site preparation, construction, materials, labor, sampling/analysis, waste management/disposal, permitting, health and safety measures, training, operation and maintenance, etc.

6.1.1 SOIL REMEDIATIONThe risk assessment concluded that soils do not pose a threat to human health or the environment, under the existing industrial land use scenario. This assumption will remain valid as long as the environmental covenant is valid.

6.1.2 GROUNDWATER REMEDIATIONBased on the current non-use of Site groundwater, no current human health risks are associated with contaminated groundwater. However, groundwater is a resource that must be protected and


restored, and the potential exists for possible future adverse effects on human health. Technologies for addressing groundwater contamination are:

No Action, and Monitored Natural Attenuation (MNA) and Source Control

6.2 REMEDY DESCRIPTION AND EVALUATION

6.2.1 SOIL: INSTITUIONAL CONTROLSInstitutional controls consist of legal/administrative measures such as an environmental covenant and notice to ensure land use remains industrial/commercial at the Facility.

6.2.1.1 Decision: Institutional controls have been instituted at the Site to ensure the Facility will not be redeveloped for residential use in the future, per the assumption in the risk assessment. Additionally, the environmental covenant prohibits construction of buildings on top of areas with the potential for detected constituents to migrate into indoor air at harmful concentrations. Thus, institutional controls meet the overall protection criteria, as well as short- and long-term effectiveness. Institutional controls are not cost prohibitive and have already been implemented at the Facility. To ensure that the terms of the institutional controls are being followed, an annual report will be prepared to verify site conditions. In addition, a Soil Management Plan will be prepared for the Site to address building restrictions and potential future intrusive work given the Site history and since 1,2-dichlorobenzene was detected in soil above soil saturation limits at one location in the northwest portion of the Site near monitoring well UAW08-20.

6.2.2 GROUNDWATER: NO ACTIONNo Action consists of shutting down the French Drain groundwater extraction system and conducting no further monitoring of the situation.

6.2.2.1 Decision:No Action will not verify that groundwater contaminants are decreasing and not migrating offsite into Mill Creek at harmful levels. No Action would not meet the source control and reduction criteria; therefore, No Action is not selected.

6.2.3 GROUNDWATER EXTRACTION SYSTEMThe existing groundwater extraction system has been collecting shallow groundwater at the perimeter of the Site since the mid-1980s. An evaluation of possible shutdown of the system in 2013 indicated that the system could be shut down with minimal impact to the adjacent Mill Creek.

6.2.3.1 Decision:The groundwater extraction system will be shut down as source control has been accomplished and the groundwater concentrations have stabilized or are decreasing. Monitoring of the perimeter wells along Mill Creek will be conducted to verify that shut down of the system has no adverse impacts on the creek. Additionally, these perimeter wells will serve as the point of compliance for potential


migration to Mill Creek. As the City of Reading owns the land directly adjacent to Mill Creek, ROH will have an annual meeting with the City of Reading to determine if there are any proposed changes to the land use adjacent to Mill Creek and to confirm that no applications have been submitted to the City for potable use of groundwater in the vicinity of the Site. A similar annual meeting will also be held with the Hamilton County Health Department regarding applications to install a potable well within the City of Reading limits. The groundwater extraction system will not be removed from service and monitoring will not begin until a detailed groundwater sampling and monitoring plan has been approved by OEPA. Additionally, the groundwater extraction system will be maintained until it has been demonstrated that concentrations of COCs in the downgradient monitoring wells have not increased. Maintenance procedures for the groundwater extraction system will be included in the groundwater sampling and analysis plan.

6.2.4 MONITORED NATURAL ATTENUATION OF CONSTITUENTS IN GROUNDWATERMonitored natural attenuation relies on natural or intrinsic processes such as adsorption, dispersion, biodegradation, and dilution to dissipate constituents that are present in groundwater to achieve remedial goals. The primary means of evaluating the performance of MNA is through an ongoing monitoring program and the continued assessment of the data to verify that natural attenuation is continuing to abate the chemicals of concern.At the Facility, eight site-related constituents have been detected in perimeter groundwater near Mill Creek above their respective remedial goals for protection of aquatic life within the shallow Upper Aquifer. The constituents in groundwater have the potential to undergo natural attenuation through a number of mechanisms. The dissolved organic constituents have the propensity to adsorb to soils, thus attenuating their migration. These constituents can also undergo chemical changes due to dissolution, dilution, and hydrolysis to further attenuate their potential migration. These constituents, especially the VOCs, have been shown to be biodegradable. The limitations of natural attenuation as a remedial technology include the resistance of some of the constituents to these processes. VOCs are less retarded in migratory potential but are more readily degradable. The timeframe associated with the more complex constituents can be longer due to the number of transformations required to degrade the constituents. Since the decline in concentrations and number of constituents indicates that MNA is occurring at the Facility, and the process results in the permanent destruction/adsorption of chemical constituents, MNA is anticipated to be both reliable and effective in the long term. Chemical species that may represent daughter products are present only at low concentrations and appear to be stable or decreasing. Future groundwater monitoring will be conducted to provide data to quantitatively evaluate the degree to which natural attenuation is progressing at the Facility. The groundwater monitoring program will focus on collecting data that would be necessary to demonstrate a clear and meaningful trend of decreasing contaminant mass and concentration over time at appropriate monitoring points. The groundwater monitoring network will include the following wells:

UAW07-20 UAW08-20 MW-EPA-1 UAW05-20 UAW03-20 UAW02-20 UAW25-20


UAW01-30 UAW21-30

These wells were selected for monitoring as they are adjacent to the western property line and therefore closest to Mill Creek and they have historically had the highest detections of Site-related contaminants; or these wells have had the highest number of contaminants detected in the wells. Monitoring wells located along the northern perimeter of the Site were not included in the proposed groundwater monitoring network as they are adjacent to the Pristine Superfund Site and detections of VOCs in these wells are consistent with detections of Pristine-related compounds of concern and, as such, the area is already being monitored on an annual basis as part of the Pristine work (GHD, 2019). However, data from some of these up-gradient wells may be included in the monitoring program to establish background conditions and flow direction. A detailed groundwater sampling and analysis plan will be developed for the Site following the selection of the remedy. Site wells that are not part of the groundwater monitoring program will be abandoned in accordance with state guidance. No wells will be abandoned until the groundwater sampling and monitoring plan has been approved by OEPA.Ten times the OEPA surface water quality criteria is chosen as being adequately protective for groundwater migrating to surface water based on the groundwater flux to Mill Creek. The estimated groundwater flux represents approximately 0.007 percent of the mean flow of Mill Creek and approximately 0.2 percent of the 7Q10 flow. Groundwater will be analyzed for the following list of compounds of concern:

ANALYTE 10 X OEPA SURFACE WATER QUALITY CRITERIA (ΜG/L)*

1,2-DICHLOROBENZENE 2301,4-DICHLOROBENZENE 94CHLOROBENZENE 470CARBON DISULFIDE 150ANILINE 41BARIUM 2200CHROMIUM 1500TIN 1800

*Ohio Water Quality Criteria for the Ohio River Basin, 2/3/2017, (OMZA times a protectiveness factor of 10).

ROH will conduct quarterly groundwater monitoring for an initial period of 2 years following shutdown of the groundwater extraction system. After two years, the frequency of sampling may be reduced to annual sampling if it is adequately demonstrated that there are no significant changes in concentration or distribution of constituents are observed. Approval to decrease the monitoring frequency will be based on a statistical evaluation of the data. The monitoring program may be terminated when the following criteria are met: (a) concentrations of monitoring analytes are below 10 times the water quality criteria and concentrations have been demonstrated to be stable and or show decreasing trends, and (b) concentrations remain below these levels for at least three consecutive years of monitoring. After each monitoring event, ROH will conduct a statistical evaluation of the data with input from OEPA to determine the effectiveness of the remedy and if additional corrective measures may be


required. The statistical methods that will be utilized in the evaluation will be specified in a detailed groundwater sampling and analysis plan.

6.2.4.1 Decision:Monitored natural attenuation measures the natural reduction of chemical constituents. In conjunction with the previously operated groundwater extraction system and previously implemented source removal activities (removal of storage tanks and contaminated soils), this remedy will achieve the objective of groundwater protection. This technology is not cost prohibitive and is implementable.

6.2.5 GROUNDWATER RESTRICTION FOR FUTURE WELL INSTALLATIONThe potential exists for future occupants to install a drinking water well at the Site. To prevent this, an environmental covenant has been implemented at the Site prohibiting installation of any groundwater wells except for the sole purpose of investigation, monitoring and remediation of groundwater or in conjunction with construction or excavation activities or maintenance of subsurface utilities.

6.2.5.1 Decision:Institutional controls which restrict future installation of domestic drinking water wells have been implemented at the Site. This will ensure that future groundwater will not pose an adverse risk to future Site occupants. These controls are not cost prohibitive to maintain and can be implemented by the current owner. ROH and/or the current owner may request permission to change these restrictions in the future when groundwater monitoring data demonstrates that safe levels have been achieved. As stated previously, ROH will have an annual meeting with the City of Reading to confirm that no applications have been submitted to the City for potable use of groundwater in the vicinity of the Site. A similar annual meeting will also be held with the Hamilton County Health Department regarding any applications to install a potable well within the City of Reading limits

6.3 REPORTING FREQUENCYAn annual report will be provided to OEPA in accordance with the recordkeeping and reporting requirements specified in OAC 3745-54-100. Reporting requirements will also be specified in the groundwater sampling and analysis plan.


7.0 SUMMARYThe OEPA has prepared this Statement of Basis for the former ROH Site in Reading, Ohio. The purpose of this Statement of Basis is to provide the public with information on the RCRA Corrective Action remedy the OEPA Is proposing to select prior to taking a final action. Remedial alternatives must meet several criteria according to OEPA guidance, including the mitigation of unacceptable risks and control of contaminant migration. Historic data and operation of the groundwater extraction system indicate that the migration of contaminated groundwater is currently under control. Natural mechanisms, source control, and source removal appear to have reduced the number, concentration, and extent of site contaminants. Current risks were determined to be acceptable and do not require further action. Therefore, the proposed alternative must address only future risks, ensuring that current conditions do not change in a manner that would create an unacceptable exposure scenario. Therefore, the final remedy must meet the following criteria:

Concentrations of chemicals in groundwater and the overall extent of impacted groundwater decline;

Onsite land use remains consistent with the commercial/industrial scenario considered in the risk assessments; and

Onsite groundwater remains unused.Continued monitoring of the groundwater using a portion of the existing groundwater monitoring network can achieve the first criterion, assuming natural processes continue to reduce groundwater constituents. The institutional controls already in-place for the Site restrict the placement of any new water wells within the Site. Existing institutional controls also restrict the future use of the former manufacturing area to commercial/industrial use only and building over areas with potential vapor intrusion concerns, thus achieving the second two criteria.Monitoring of the perimeter wells along Mill Creek will be conducted to verify that the overall area and distribution of impacted groundwater does not significantly expand or shift location, and the concentrations of individual constituents are stable or declining and remain below 10 times applicable surface water quality criteria. Such monitoring will also be used to verify that shut down of the groundwater extraction system has no adverse impacts on Mill Creek. As the City of Reading owns the land directly adjacent to Mill Creek, ROH will have an annual meeting with the City of Reading to determine if there are any proposed changes to the land use adjacent to Mill Creek and to confirm that no applications have been submitted to the City for potable use of groundwater in the vicinity of the Site. A similar annual meeting will also be held with the Hamilton County Health Department regarding applications to install a potable well within the City of Reading limits. ROH will conduct quarterly groundwater monitoring for an initial period of 2 years following shutdown of the groundwater extraction system. After two years, the frequency of sampling may be reduced to annual sampling if it is adequately demonstrated that there are no significant changes in concentration or distribution of constituents are observed. Approval to decrease the monitoring frequency will be based on a statistical evaluation of the data. The monitoring program may be terminated when the following criteria are met: (a) concentrations of monitoring analytes are below 10 times the water quality criteria and concentrations have been demonstrated to be stable and or show decreasing trends, and (b) concentrations remain below these levels for at least three consecutive years of monitoring. After each monitoring event, ROH will conduct a statistical evaluation of the data with input from OEPA to determine the effectiveness of the remedy and if additional corrective measures may be


required. The statistical methods that will be utilized in the evaluation will be specified in a detailed groundwater sampling and analysis plan. The groundwater extraction system will not be removed from service and monitoring will not begin until this plan has been approved by OEPA. Additionally, the groundwater extraction system will be maintained until it has been demonstrated that concentrations of COCs in the downgradient monitoring wells have not increased. Maintenance procedures for the groundwater extraction system will be included in the groundwater sampling and analysis plan. Institutional controls have been implemented at the Site as part of negotiations between the current property owner and the USEPA and OEPA during transfer of regulatory oversight from the USEPA to OEPA. Future residential use is currently prohibited via an environmental covenant recorded with Hamilton County on June 25, 2018 between 2000 West Property LLC and the OEPA. This environmental covenant also prohibits groundwater underlying the Site from being extracted for any purpose, potable or otherwise, except for investigation, monitoring and remediation of groundwater or in conjunction with construction or excavation activities or maintenance of subsurface utilities. In addition, as part of the environmental covenant, the construction of new buildings on the Site are prohibited unless an OEPA approved vapor mitigation system is installed or OEPA confirms that soil gas concentrations are below vapor intrusion screening levels. Additionally, occupancy of existing buildings on the Site is restricted until OEPA approves of a vapor intrusion evaluation to determine if the building should be retrofitted with a vapor barrier system. The environmental covenant also limits the current owner from interfering with the operation and maintenance of the groundwater extraction system while Corrective Actions are being implemented.The remedy meets the evaluation criteria and will be protective of human health and the environment. Based on current information, the propose remedy provides a good balance between controlling unacceptable future risk due to groundwater contamination with future use of the Facility.


8.0 ReferencesEcology & Environment, 1991. Screening Site Inspection Report for Carstab Corporation, Reading,

Ohio, August 19. Geomatrix, 2000. Current Conditions Report, Morton International, Inc., Reading, Ohio.

http://edocpub.epa.ohio.gov/publicportal/ViewDocument.aspx?docid=1379614 Geomatrix, 2004. Revised Facility Investigation Report RCRA 3013 Administrative Order. Morton

International, Inc., Reading, Ohio. September 2004. http://edocpub.epa.ohio.gov/publicportal/ViewDocument.aspx?docid=1379603

GHD, 2019. Round 52 Groundwater Sampling Results, Pristine, Inc. Site, Reading, Ohio. September 30, 2019. http://edocpub.epa.ohio.gov/publicportal/ViewDocument.aspx?docid=1158924

Midwest Biodiversity Institute (MBI), 2016. Biological and Water Quality Study of Mill Creek 2016. Hamilton County, Ohio. Technical Report MBI/2017-6-8. Columbus, Ohio.

Ohio Environmental Protection Agency (OEPA), 2004. Water Quality Permit Support Document to Assess the Proposed Expansion of the Butler County Upper Mill Creek WWTP.

OEPA, 2018. 2018 Integrated Water Quality Monitoring and Assessment Report. June 2018.OEPA, 2019. Ohio Sport Fish Consumption Advisory. March 2019. Osborne, Robert, 1968. American Upper Ordovician Standard. IX. Bedrock Geology of Eastern

Hamilton County, Ohio. The American Association of Petroleum Geologists Bulletin, Vol. 52-11, pp. 2137-2152.

Osborne, Robert, 1974. Bedrock Geology of the Cincinnati East Quadrangle, Hamilton County, Ohio. Ohio Division of Geological Survey, Report of Investigations No. 94.

Parsons, 2010. Revised Baseline Risk Assessment, Rohm and Haas Chemicals LLC, Reading, Ohio. October 2010. http://edocpub.epa.ohio.gov/publicportal/ViewDocument.aspx?docid=1379611

Parsons, 2013. Evaluation of Shutdown of Groundwater Recovery System, Former Rohm and Haas Chemicals Facility, Reading, Ohio. April 22, 2013. http://edocpub.epa.ohio.gov/publicportal/ViewDocument.aspx?docid=1379612

Parsons, 2020. Groundwater Modeling Report, Rohm and Haas Chemicals, LLC, Reading, Ohio. March 2020. http://edocpub.epa.ohio.gov/publicportal/ViewDocument.aspx?docid=1350610

TechLaw, 1998. Preliminary Assessment/Visual Site Inspection Report for Morton International, Inc., Reading, Ohio. EPA ID No. OHD000724138.http://edocpub.epa.ohio.gov/publicportal/ViewDocument.aspx?docid=1379597

TetraTech, 2017. Vapor Intrusion Evaluation Report, Building 40 on Former Rohm and Haas Chemicals Facility, 2000 West Street, Cincinnati, Ohio. June 6, 2017. http://edocpub.epa.ohio.gov/publicportal/ViewDocument.aspx?docid=1379610

U.S. Environmental Protection Agency (USEPA), 1989. Risk Assessment Guidance for Superfund (RAGS): Part A.

USEPA, 2017. Response to July 28, 2017 letter from Dow Chemical Company. From Mirtha Capiro, USEPA to Carl Coker, The Dow Chemical Company, November 6, 2017. http://edocpub.epa.ohio.gov/publicportal/ViewDocument.aspx?docid=1379613


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