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Home My WebLink About25035_National Welders Decision Memo 202311131 National Welders/25035-21-060/20231113 DECISION MEMORANDUM DATE: November 13, 2023 FROM: Bill Schmithorst TO: BF Assessment File RE: National Welders 800 Gesco Street, 918 Gesco Street and 659 State Street Charlotte, Mecklenburg County BF # 25035-21-060 Based on the following information, it has been determined that the above referenced site, whose intended use is for no uses other than high density residential, industrial, retail, restaurant, beverage and food production facility, office, recreation, warehousing, institutional, parking, and with DEQ’s written approval other commercial uses, can be made suitable for such uses. Introduction: The Prospective Developer (PD) is RAM Realty Acquisitions V, LLC, a limited liability company, headquartered at 4801 PGA Boulevard, Palm Beach Gardens, FL 33418. The Brownfields Property consists of five parcels totaling approximately 3.9 acres. The Brownfields Property was recently vacant and is currently being redeveloped with new construction. Redevelopment Plans: Planned redevelopment of the Brownfields Property includes construction of three apartment buildings. A passive vapor mitigation system will be installed in each building. Site History: Prior to the construction of an industrial warehouse building in the northern part of the site west of Gesco Street in the 1940s, the Brownfields Property was comprised of agricultural land and a rail spur. In the late 1950s or early 1960s, an industrial facility was developed in the southwestern portion of the site (west of Gesco Street). The eastern part of the site, located across Gesco Street, was used for parking but was otherwise undeveloped. The buildings on the site were occupied by National Welders Supply, where they sold and distributed compressed welding gases. The southwestern building also served as a storage and distribution center for wholesale steel. In the 1980s, the northernmost section of the National Welders Supply facility was demolished, and in the mid-2010s, the remaining parts of the northern site buildings were torn down. The southwestern building was demolished in 2017, and since then, the property has remained vacant and undeveloped. 2 National Welders/25035-21-060/20231113 In August 1996, a heating oil underground storage tank (UST) connected to the former National Welders Supply facility, which was situated in the central area of the Brownfields Property west of Gesco Street, was successfully removed. On June 4, 2003, the DEQ UST Section issued a No Further Action letter for the incident. A Notice of Residual Petroleum (NORP) was recorded on June 11, 2003, imposing a land use restriction specifically for industrial/commercial purposes, preventing the use of groundwater for any activities on the property. Exterior soil gas sampling results from an August 2021 Phase II environmental site assessment indicated that trichloroethylene (TCE) was detected at concentrations as high as 290,000 micrograms per cubic meter (μg/m3). A soil assessment was conducted in May 2022 to identify the approximate source area of the TCE contamination. Results from the soil assessment indicated detections of TCE in soil in the general area of where the elevated soil gas VOC concentrations were previously detected. The area of impacted soil was delineated and approximately 2,600 cubic yards of soil were excavated from the suspected TCE source area and managed in accordance with the approved Brownfields Environmental Management Plan. Post-excavation soil gas sampling indicated that TCE concentrations were reduced to 500 μg/m3 at the location where the highest TCE concentration was previously detected. Potential Receptors: Potential receptors are: construction workers, on-site workers, future residents, and if any, potential-offsite concerns. Contaminated Media: DEQ has evaluated data collected from the following media at the subject property: soil, groundwater, and exterior soil gas. DEQ relies on the following data to base its conclusions regarding the subject property and its suitability for its intended reuse. Please see the Brownfield Agreement’s Exhibit 2 for specific sample locations, dates, and contaminants of concern (COCs). Risk Calculations: Risk calculations were performed using the January 2023 DEQ Risk Calculator https://deq.nc.gov/permits-rules/risk-based-remediation/risk-evaluation-resources. Data from the groundwater site-wide sampling locations exhibiting the highest concentrations were used for calculating risk. For soil and exterior soil gas, the site samples were segregated for risk evaluation purposes by samples collected at proposed Building A and proposed Building B because the buildings are located on opposite sides of Gesco Street. Results of the risk evaluation are presented in the following table. 3 National Welders/25035-21-060/20231113 Proposed Building A Risk for Individual Pathways Output Form 1A Version Date: January 2023 Basis: November 2022 EPA RSL Table Site ID: 25035-21-060 Exposure Unit ID: Building A Soil Gas, Groundwater, Soil Receptor Pathway Carcinogenic Risk Hazard Index Risk exceeded? Soil 6.7E-06 1.0E+00 YES Groundwater Use* 3.9E-04 1.4E+01 YES Soil 1.2E-06 1.8E-01 NO Groundwater Use* 8.4E-05 3.0E+00 YES Construction Worker Soil 3.5E-07 8.5E-02 NO Soil 3.7E-06 2.4E-01 NO Surface Water* NC NC NC Receptor Pathway Carcinogenic Risk Hazard Index Risk exceeded? Groundwater to Indoor Air 1.1E-04 6.7E+00 YES Soil Gas to Indoor Air 1.5E-04 3.4E+01 YES Indoor Air NC NC NC Groundwater to Indoor Air 2.3E-05 1.6E+00 YES Soil Gas to Indoor Air 8.3E-06 2.7E+00 YES Indoor Air NC NC NC DIRECT CONTACT SOIL AND WATER CALCULATORS Resident Non-Residential Worker Recreator/Trespasser VAPOR INTRUSION CALCULATORS Resident Non-Residential Worker Proposed Building B Risk for Individual Pathways Output Form 1A Version Date: January 2023 Basis: November 2022 EPA RSL Table Site ID: 25035-21-060 Exposure Unit ID: Building B Area Soil Gas and Soil Receptor Pathway Carcinogenic Risk Hazard Index Risk exceeded? Soil 1.4E-06 3.3E-02 NO Groundwater Use* NC NC NC Soil 3.1E-07 2.4E-03 NO Groundwater Use* NC NC NC Construction Worker Soil 5.2E-08 2.7E-02 NO Soil 7.7E-07 1.8E-02 NO Surface Water* NC NC NC Receptor Pathway Carcinogenic Risk Hazard Index Risk exceeded? Groundwater to Indoor Air NC NC NC Soil Gas to Indoor Air 3.9E-06 1.1E-01 NO Indoor Air NC NC NC Groundwater to Indoor Air NC NC NC Soil Gas to Indoor Air 1.7E-07 8.6E-03 NO Indoor Air NC NC NC DIRECT CONTACT SOIL AND WATER CALCULATORS Resident Non-Residential Worker Recreator/Trespasser VAPOR INTRUSION CALCULATORS Resident Non-Residential Worker 4 National Welders/25035-21-060/20231113 The risk calculations indicated the following based on available data, including the following media: groundwater, soil, and exterior soil gas. Soil  Arsenic and hexavalent chromium were detected above NC Preliminary Soil Remediation goas, but at levels comparable to background concentrations. Groundwater  Chlorinated compounds were detected above NCAC 2L Groundwater Standards. It is not known if the source of the contaminants is onsite or offsite. Surface Water  Surface water is not present on the property. Exterior Soil Gas  After completion of the soil excavation activities, TCE was detected above the NC Residential Vapor Intrusion Screening Levels at concentrations up to 2,300 µg/m3 near proposed Building A.  TCE is the risk driver for the Brownfields Property. Sub-Slab Vapor  There are no buildings on the property, so sub-slab samples were not collected. Indoor Air  There are no buildings on the property, so indoor air samples were not collected. Based on the results of the risk evaluation, the Residential Hazard Index risk threshold was exceeded for soil gas and groundwater to indoor air under a residential use scenario. Elevated concentrations of VOCs detected in groundwater will require a land use restriction prohibiting groundwater use. Municipal water is available at the Brownfields Property, further minimizing the potential exposure risks. A DEQ-approved Environmental Management Plan (EMP), has been prepared to prevent exposure to site workers and future residents from unacceptable levels of contaminants, and to manage the safe handling and disposal of potentially contaminated materials during construction. In addition, final grade soil sampling of exposed areas will be required prior to occupying the Brownfields Property to demonstrate that the property is safe for the intended use. A passive vapor intrusion mitigation system is planned for each building. The vapor mitigation will be designed to have the capability to be converted to an active system, if necessary. 5 National Welders/25035-21-060/20231113 Land Use Restrictions: The standard land use restrictions including land use, Environmental Management Plan and reporting requirements, prohibition on groundwater use, soil restrictions, vapor intrusion mitigation, access, notification, and prohibition on the use of known contaminants, and the annual land use update obligation are required for this Brownfields Agreement. Based on the site-specific data provided to the Brownfield Redevelopment Section, the site reuse is suitable for the site as long as the agreed upon land use restrictions in the BFA are abided by. Property Management  Environmental Management Plan  A passive vapor intrusion mitigation system is being installed.  Pre- and post-occupancy sub-slab vapor sampling will be required in the VIMP.  TCE was detected in exterior soil gas.  Final grade soil sampling is required.