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HomeMy WebLinkAbout23077_Diversey Water Tech_Decision Memo_20210423DECISION MEMORANDUM DATE: April 23, 2021 FROM: Kathleen Markey and Jordan Thompson TO: BF Assessment File RE: Diversey Water Technologies 1200, 1208, 1210 & 1212 S. Mint St. and 1201 S. Graham Street Charlotte, Mecklenburg County Brownfields Project No. 23077-19-060 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, recreational, commercial and parking, can be made suitable for such uses. Introduction: The Brownfields Property consists of four parcels totaling approximately 1.606 acres of land. The property is associated with Mecklenburg county Parcel Identification Numbers 07326604, 07326605, 07326606, and 07326607. Redevelopment Plans: The Prospective Developer (PD) has demolished the existing structures that are located on the Brownfields Property. The PD intends to redevelop the Brownfields Property for high density residential, recreational, parking, and commercial uses. Site History: The Brownfields Property was historically used for residential purposes prior to 1911. Following that time, the Brownfields Property has been used for commercial purposes. The eastern and northern portions of the site were utilized by two machine shops and a welding shop by 1929. A propane gas supply company occupied the southern portion of the former buildings from the 1950’s to the 1960’s. In the early 1950’s, an office building was constructed on the southernmost parcel. A warehouse building was constructed on the northern portion of the property in 1964 it was subsequently utilized for: a manufacturer of chromium-based water treatment chemicals and fuel oil additives (1960s to late 1990s), janitorial supply companies (1970s to 2000s), a heating, ventilation, and air conditioning (“HVAC”) control panel repair business (mid-2000s to mid-2010s), and a furniture and millwork company (late 2010s). The welding shop and machine shop that had been on the property since the 1920’s was demolished in the early 1970’s. A sign company occupied the property in the 1970’s, followed by a steel rule die company in the late 1970’s, a printing company in the 1990’s and medical offices in the 1990’s through the 2000’s. The Brownfields Site is also associated with IHSB number NONCD0001610. A former occupant of the Brownfields Property, Mechanical Systems & Services (MS&S) (located at 1201 S. Graham St in the northeastern portion of the property), was previously registered as a Resource Conservation and Recovery Act (RCRA) Large Quantity Generator (LQG) of ignitable (D001), corrosive (D002), chromium (D007), mercury (D009), carbamodithioic acid, bis-1,2-ethanediyl, salts and esters (U114), hydrazine (U133), and TCE (U228) hazardous wastes. No RCRA compliance violations were reported in connection with the facility. The below figure depicts the Brownfields Property in a recent configuration and outlines areas of concern based on former site operations. Environmental Assessment Overview: Soil and groundwater assessment activities were conducted in 1992 and 1993 in the vicinity of the existing warehouse and adjoining office building. According to the June 1994 Investigation of the Diversey Water Technologies Inc. Site report (“1994 Report”), chromium and lead were detected above the North Carolina Department of Environmental Quality (“DEQ”) Residential Preliminary Soil Remediation Goals (“PSRGs”) in shallow soil samples collected on the southwestern portion of the Brownfields Property near an 18-inch diameter corrugated metal pipe. The former use of the pipe is unknown. Metals, including nickel, chromium, iron, lead, and manganese were detected above the North Carolina Administrative Code Title 15A Subchapter 2L Standards (“2L Standards”) in groundwater samples collected at the Brownfields Property. The 1994 Report also indicated trichloroethylene (TCE) was detected above the 2L Groundwater Standard, with the highest concentration identified near the northwestern corner of the Brownfields Property. The detection of TCE was further evaluated and documented in the February 1997 Comprehensive Site Assessment Report, the highest concentrations of TCE in groundwater were confirmed to be in the northwestern corner of the Brownfields Property. Soil sampling did not indicate the presence of TCE, the report concluded that the TCE was likely due to one or more off-site sources. In 2019 a Phase II assessment was conducted, with the report issued in December 2019 including the collection of soil, groundwater, soil gas, and sub-slab vapor samples. This assessment further documented the presence of TCE in groundwater in the northwest portion of the property. The results above an applicable standard are summarized further below. The Phase II assessment indicated that there was a detection of benzo(a)pyrene and hexavalent chromium at concentrations above the residential PSRG for soil. The sub- slab vapor and exterior soil gas results indicated the presence of multiple VOCs including low concentrations of chlorinated and petroleum-related compounds. However, none of these concentrations exceed the residential SGSLs. A July 2020 Brownfields Assessment Report conducted as part of a work plan approved by NCDEQ detailed results of additional soil, groundwater, and vapor intrusion sampling conducted at the Brownfields Property in May 2020. One soil, one groundwater, seven sub-slab vapor, and two soil gas samples were collected to obtain additional assessment data and to confirm select historical vapor intrusion assessment results. Based on the sub-slab results additional samples were collected in July 2020 and reported in the August 2020 Vapor Intrusion Assessment Report. The results above an applicable standard are summarized further below. Potential Receptors: Potential receptors are; construction workers, on-site workers, future residences, visitors and trespassers. Contaminated Media: DEQ has evaluated data collected from the following media at the subject property: soil, groundwater, soil vapor and soil gas. DEQ relies on the following data to base its conclusions regarding the subject property and its suitability for its intended reuse. Below is a sample location map depicting the most recent sample locations collected on the Brownfields Property. Soil Soil samples were collected in assessments conducted in 1994, 2019 and 2020. The 1994 Report, conducted under IHSB supervision, indicated that nickel, chromium, iron, lead and manganese were identified above residential IHSB Preliminary Soil Remediation Goals (PSRGs). No VOCs were identified during the 1994 sampling event. The December 2019 phase II identified arsenic and hexavalent chromium concentrations above residential PSRGs. Benzo(a)pyrene was also detected at a concentration above the residential PSRG. The 2019 phase II did not detect any VOCs above residential PSRGs. The 2020 Brownfields Assessment Report identified arsenic above residential PSRGs near the northern corner of the site. The 2020 sampling event did not identify VOC concentrations above PSRGs and did not identify SVOCs at concentrations greater than method detection limits. Groundwater Depth to groundwater is approximately 14.8 feet below ground surface to 36.07 ft below ground surface and groundwater flow is northwest towards Irwin Creek. The 1994 Report indicated the presence of trichloroethylene (TCE) in groundwater above 2L Standards near the northwestern corner of the property. Following these results, additional assessment was conducted from 1994-1996 to evaluate the source of the TCE. TCE appears to be sourced from one or more off-site properties based on the concentrations in the northwest and southwest area of the Brownfields Property. 1,2-Dichloroethane was detected above the 2L standard in one deep groundwater sample collected in the northwestern portion of the site. The 2019 phase II identified chromium above the 2L standard near the northwestern and central portions of the site. TCE was also detected at 4.2 ug/L near the northwestern portion of the site in this assessment, consistent with the historical groundwater data. In the 2020 Brownfields Assessment Report, chromium was detected in the southern portion of the site at a concentration above the 2L standard. This sample did not contain VOCs that were above the method detection limits. Surface Water Surface water is not located on the site. Soil Vapor Soil Vapor was not sampled at this site. Sub-Slab Vapor and Soil Gas In the December 2019 Phase II Environmental Site Assessment, Benzene, naphthalene, and chloroform were identified near the southeastern portion of the Brownfields property at concentrations exceeding the DEQ Residential Sub-slab and Exterior Soil Gas Screening Levels (“SGSLs”). Chloroform and naphthalene exceeded the residential SGSLs in one sub-slab vapor sample collected near the center of the property. In the 2020 Brownfields Assessment Report, benzene, ethylbenzene, naphthalene, and vinyl chloride exceeded the residential SGSLs. The 2020 Brownfields Assessment Report also identified the presence of 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzen and xylenes near the northern, southern, and western portions of the site at concentrations exceeding residential SGSLs. The northern portion of the site identified benzene, 1,2- dichlorobenzene, 1,4- dichlorobenzene, ethylbenzene, naphthalene, 1,2,4- trimethylbenzene, 1,3,5-trimethylbenzene, and/or xylenes at concentrations exceeding the Residential SGSLs. The southernmost sub-slab sample that was collected in the August 21, 2020 report identified 1,2,4- trimethylbenzene that exceeded the Residential SGSLs. Indoor Air The onsite structures will be demolished, therefore indoor air was not evaluated on the Brownfields Property. Risk Calculations The DEQ Risk Calculator was developed to evaluate the risk of multiple contaminants and multiple exposure routes associated with contaminated environmental media at a site. The risk evaluation procedures, equations, and default parameters used to create the calculator follow the current USEPA risk assessment guidance. The DEQ Risk Calculator dated July 2020 was used to evaluate the following. The Brownfields Property was evaluated as a whole. The risk calculations indicated the following based on available data, including the following media: groundwater, soil (based on confirmatory soil data), soil gas, and sub-slab soil gas samples: Based on the above risk calculations, exposure risk is exceeded for direct groundwater contact for both residential and non-residential reuse due to the hazard index exceedance of 1. Additionally, the risk calculator indicates that risk is exceeded for residential and nonresidential vapor pathways for groundwater and soil gas to indoor air. Based on available data for this site, the risk calculator indicates that for the planned residential structures (as well as any potential future non-residential structures), vapor intrusion and Hazard Index risk exceeds appropriate risk levels and that VI mitigation measures approved by DEQ will be a necessary requirement of redevelopment plans on the property. Required Land Use Restrictions: • There will be no use other than high density residential, retail, office, recreational, parking, open space, and with prior written DEQ approval, other commercial uses. • No groundwater or surface water use. • No disturbing soil without DEQ approval or for landscape/mowing/pruning/repair of underground infrastructure (written notice to DEQ), • Soil Import/Export must be approved by DEQ. • Access to Brownfields Property for environmental assessment. \ • Standard vapor intrusion LUR. • No childcare or adult care centers. • NBP reference in deed. • No contaminants (as included in Ex. 2 to the BFA) on property except for de minimis amounts, fluid in vehicles, fuels for generators/equipment. • Final grade sampling will occur for volatile organic compounds by EPA Method 8270, semi-volatile organic compounds by EPA Method 8270 and RCRA Metals by EPA Methods 6020/7471. Based on the site-specific data provided to the Brownfield program, the site reuse appears suitable for the site as long as the agreed upon land use restrictions in the BFA are abided by. PMU NOTES As part of active Brownfields work, an EMP and VIMP for this property have been approved. As of recordation, the site buildings have been demolished and construction is underway. The VIMS is designed as a passive system below enclosed areas of the Brownfields Property (excluding a large parking deck). Following installation, influence sampling will be conducted and following, concurrent soil gas and indoor air sampling (IAS sampling especially needed because this is a TCE impacted site). Following installation and approval of occupancy, a minimum of 3 years of annual sampling will be conducted on the property to determine VIMS effectiveness and if the system needs to become active. If areas exist that qualify for final grade sampling, the EMP has committed to a separate work plan for those. Further, there is an LUR requiring final grade sampling.