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Home My WebLink About21059_South Street Condos West_Decision Memo_20190613DECISION MEMORANDUM DATE: June 13, 2019 FROM: Brad Atkinson TO: BF Assessment File RE: South Street Condos - West 611 West South Street Raleigh, Wake BF # 21059 Based on the following information, it has been determined that the above referenced site, whose intended use is for no uses other than office, open space, recreation, high- density residential, parking, and subject to DEQ’s prior written approval, other commercial uses commercial, can be made suitable for such uses. Introduction: This Agreement concerns 0.914 acres located at 611 West South Street, Raleigh, NC. The property is composed of one parcel with Wake County Tax Parcel ID # 1703462162. This parcel was formed from the recombination of four previous parcels with addresses of 609, 611, 615, and 617 West South Street. Prior to recombination, the respective Wake County Tax Parcel ID Numbers were: 1703461141, 1703460192, 1703460143, 1703369192. Both two building which most recently occupied the Brownfields Property were razed in 2016 and the site has been graded in preparation for construction. Redevelopment Plans: The Brownfields Property is planned for redevelopment as a single three story building containing 32 condominium units. Proposed uses are: office, open space, recreation, high-density residential, parking, and subject to DEQ’s prior written approval, other commercial uses. Site History: The Brownfields Property was developed with one single-family residence prior to 1914 until at least 1950. By 1972, the single-family residence had been replaced by two cinderblock buildings. One building was owned by a welding and fabrication company from 1982-1985. All other known use of either building had been for automobile sales or service until the buildings were razed in December of 2016. The presence of chlorinated solvents in the soil and groundwater is believed to have come from the automobile service businesses that operated at the site. After the building were razed, the site was graded in preparation for construction of the proposed condominiums. During grading, considerable fill material containing brick, concrete, and concrete block was discovered. The fill is believed to have been put in place prior to 1914 when the single family home was constructed, or prior to 1972 when the two cinderblock buildings were first noted as being present on the site. The fill material was excavated and disposed under manifests at a permitted disposal facility. The site was then backfilled with fill material sourced from a NC DOT road revision project in Raleigh and from insitu soil from a recently cleared and grubbed area at the Buffalo Land Clearing and Inert Debris Landfill located south of Raleigh. At that point, the developer learned of the Brownfields Program and elected to submit an application into the program. The fill material was soon thereafter sampled. Detectable concentrations of VOCs or SVOCs were not identified in any of the soil samples submitted for analysis. Barium, chromium (total), lead, and mercury were detected at concentrations above the laboratory method detection limit (MDL) but below the IHSB Health Based PSRG for unrestricted site use in 8 samples collected from the Buffalo Landfill fill. No regulatory actions are registered with DEQ for the Brownfields Property. Potential Receptors: Potential receptors are: construction workers, on-site workers, future residences, visitors, animals, and trespassers. Contaminated Media: DEQ has evaluated data collected from the following media at the subject property: soil, groundwater, and storm water. DEQ relies on the following data to base its conclusions regarding the subject property and its suitability for its intended reuse. Soil Metals were detected in the soil which exceed their respective IHSB Residential PSRG. Arsenic was detected up to 7.25 mg/kg and chromium (total) was detected up to 21 mg/kg. VOCs and SVOCs were detected in soil which exceed their respective IHSB Residential PSRG. Trichloroethelene was detected up to 1.14 mg/kg, naphthalene up to 54.7 mg/kg, benzo(A)anthracene up to 16.3 mg/kg, benzo(B)fluoranthene up to 10.6 mg/kg, benzo(K)fluoranthene up to 4.41 mg/kg, benzo(A)pyrene up to 11.8 mg/kg, dibenza(A,H)anthracene up to 1.84 mg/kg, and indeno(1,2,3-CD)pyrene up to 19.2 mg/kg. Groundwater No metals or SVOCs were detected in groundwater above their respective 2L standard. VOCs were detected in groundwater above their respective NC 2L groundwater standard. 1-2 dichloroethane was detected up to 2.98 ug/ml, tetrachloroethae up to 6.64 ug/ml, and trichloroethane up to 39.8 ug/ml. Surface Water / Storm Water: Surface water and storm water are piped under the Brownfields Property and exit an outfall immediately south of the Brownfields Property. Water from the outfall was sampled and detectable concentration of VOCs were identified. 1,2 Dichloroethane was detected at .0407 ug/l, tetrachloroethane at 1 ug/l, and tricholorethane at 5.4 ug/l. Soil Vapor Soil vapor sampling was not conducted. The PD plan to install podium style parking on the ground floor of the building which will mitigate any potential vapor intrusion issues. Sub-Slab Vapor Sub-slab sampling was not conducted as no slabs were present. Indoor Air Indoor air sampling was not conducted as no buildings were present. Risk Calculations Risk Calculations were performed using the DWM Risk Calculator (February 2018 version). For the purposes of evaluating the Brownfields Property spatially, the site was evaluated as a whole. For DWM, an acceptable carcinogenic risk is considered to be less than 1.0E -04 and an acceptable noncancer hazard index is less than 1.0. Exposure scenarios with unacceptable risk calculation results based on the known contaminants in the media at the Brownfields Property are indicated in the following tables and are signified by a “Yes” in red under the Risk Exceeded column. Risk calculation results for the South Street Condos – West project indicate that the concentration of contaminants in groundwater: • exceed the acceptable carcinogenic risk and the non-cancer hazard index of 1 for residential exposure scenarios; • exceed the acceptable non-cancer hazard index of 1, but not the acceptable carcinogenic risk level for non-residential exposure scenarios. Risk calculation results indicate that the concentration of contaminants in soil: • exceed the acceptable carcinogenic and the non-cancer hazard index of 1 for residential and construction exposure scenarios; • but does not exceed for non-residential worker scenarios. Soil gas samples were not collected, so no risk calculation for soil gas was generated. Summary of Risk Assessment Output Output Form 1A Version Date: February 2018 Basis: November 2017 EPA RSL Table Site ID: 21059-17-092 Exposure Unit ID: Entire site Receptor Pathway Carcinogenic Risk Hazard Index Risk exceeded? Soil Combined Pathways 8.7E-04 2.5E+00 YES Groundwater Combined Pathways*2.4E-04 1.6E+01 YES Soil Combined Pathways 4.7E-05 2.8E-01 NO Groundwater Combined Pathways*4.5E-05 3.4E+00 YES Construction Worker Soil Combined Pathways 6.1E-05 2.7E+00 YES Soil Combined Pathways 4.8E-04 1.1E+00 YES Surface Water Combined Pathways*1.2E-06 1.9E-01 NO Receptor Pathway Carcinogenic Risk Hazard Index Risk exceeded? Groundwater to Indoor Air 3.6E-05 7.9E+00 YES Soil Gas to Indoor Air 0.0E+00 0.0E+00 NO Indoor Air 0.0E+00 0.0E+00 NO Groundwater to Indoor Air 5.9E-06 1.9E+00 YES Soil Gas to Indoor Air 0.0E+00 0.0E+00 NO Indoor Air 0.0E+00 0.0E+00 NO Pathway Source Source Soil NM Source Groundwater NM Source Soil NM Source Groundwater NM 2. * = If concentrations in groundwater exceed the NC 2L Standards or IMAC, or concentrations in surface water exceed the NC 2B Standards, appropriate remediation and/or institutional control measures will be necessary to be eligible for a risk- based closure. Protection of Surface Water Exceedence of 2B at POE? Exceedence of 2B at POE? VAPOR INTRUSION CALCULATORS Resident Non-Residential Worker CONTAMINANT MIGRATION CALCULATORS Target POE Concentrations Exceeded? Protection of Groundwater Use Exceedence of 2L at POE? Exceedence of 2L at POE? 1. If lead concentrations were entered in the exposure point concentration tables, see the individual calculator sheets for lead concentrations in comparison to screening levels. Note that lead is not included in cumulative risk calculations. Notes: PRIMARY CALCULATORS Resident Non-Residential Worker User Defined Red shading LICR> 1E-04 or HI> 1. LICR = Lifetime Incremental Cancer Risk HI = Hazard Index Concentrations of chlorinated solvents in the groundwater are sufficiently high to warrant the installation of vapor mitigation measures unless additional data is produced to indicate mitigation is not warranted. Required Land Use Restrictions: Land use restrictions will include the standard Environmental Management Plan, groundwater, soil disturbance, well abandonment, known contaminants, and vapor mitigation LURs. Residential use will be limited to high-density multi-family, and there will be prohibitions regarding commercial use that use chlorinated solvents. Based on the site-specific data provided to the Brownfield program, the site reuse is suitable for the site as long as the agreed upon land use restrictions in the BFA are abided. Based on the site-specific data provided to the Brownfield program, the site reuse is suitable for the site as long as the agreed upon land use restrictions in the BFA are abided by. Potential Post-Recordation Concerns: The surface water / storm water pipe which transects the Brownfields Property will be replaced by the PD due to the unsure integrity of the current terracotta pipe. The PD has included provisions in the EMP as to how to address soil, groundwater, surface water and potential storm water during the pipe replacement process.