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HomeMy WebLinkAbout23067_Blythe Isenhour_DecisionMemo_20210409DECISION MEMORANDUM DATE: April 9, 2021 FROM: Peter Doorn TO: BF Assessment File RE: Blythe Isenhour 4920 Old Pineville Road Charlotte, Mecklenburg County Brownfields Project No. 23067-19-060 Based on the following information, it has been determined that the above referenced site, whose intended use is for no uses other than multi-family residential can be made suitable for such uses. Introduction: The Brownfields Property site consists of a 1.67-acre parcel of land at 4920 Old Pineville Road, identified as Mecklenburg County parcel number 16907609. The Brownfields Property is in a primarily commercial and light industrial area zoned for Transit Oriented Development in lower South End Charlotte near the Lynx Blue Line light rail. The 4920 Old Pineville Road parcel is developed with an approximately 1,800 square foot (sq ft) office building and an approximately 3,900 sq ft warehouse constructed in the early 1960s. In the late 1990s to early 2000s, a concrete secondary containment system for aboveground storages tanks was added near the southern property boundary and a curbed concrete pad was constructed in the central portion of the property. Much of the remaining property is gravel covered and used for parking and for staging various equipment and materials. The property is currently occupied by Heartwood Tree Services, whose operations include vehicle, tree service equipment, and materials staging, vehicle fueling, administrative offices, and tree clearing debris processing activities. Redevelopment Plans: The Prospective Developer (PD), Boulevard at 4920 Old Pineville, LLC has committed to redevelopment for multi-family residential as townhomes, as well as office, parking, retail, recreational, and with prior written DEQ approval, other commercial uses. Proposed redevelopment includes razing the existing buildings for construction of approximately 48 townhomes. The proposed townhome development will be an extension of the proposed townhome development on the adjacent property to the south (Old Pineville Road, BPN 10061-06-060). Site History: The Brownfields Property was primarily agricultural until the current office building and warehouse building were constructed in 1961. Since construction of the existing buildings, the property has been occupied by Blythe & Isenhour (a general contractor) from the 1960s until the 1990s, by Four Seasons Environmental (an emergency response and remediation contractor) from the 1990s until the early 2000s, and by Heartwood Tree Services since 2003. In April 1990, a 3,000-gallon gasoline underground storage tank (UST) that had been installed in 1982 adjacent to the garage/storage area was removed. Sampling associated with the UST was completed in 2003 and DEQ issued a No Further Action letter for the UST closure on October 29, 2003. During the late 1990 and early 2000s, Four Seasons Environmental occupied the property and used the curbed concrete pad for solidifying waste fluids recovered during responses to hazardous waste spills and from USTs prior to closure activities. The waste solidification process included adding sawdust to the waste fluids prior to loading onto trucks and into drums for transport and disposal at a Subtitle D landfill. In February 2001, a tanker truck overturned on the property spilling approximately 4,000 gallons of used oil and water. Approximately 200 gallons reached a storm drain located in the western portion of the property, but the release to the storm drain was contained and spillage within the storm drain was recovered. Results of an inspection indicated that none of the product reached nearby surface water. The June 20, 2003 Soil Cleanup Report by MACTEC indicates that 1,546 tons of soil were removed and transported off-site for disposal, and that confirmation sample results were below action levels. Photographs from the excavation illustrate buried wood debris in the western portion of the property. In October 2019, Hart & Hickman completed a Phase 1 Environmental Site Assessment (ESA) for the Brownfields Property. In addition to the curbed concrete pad, the 3,000-gallon UST removal, and the 4,000-gallon used oil spill noted above, the ESA also documented a MACTEC report identifying an area of stained soil near the above ground storage tanks. In 2003, MACTEC conducted soil sampling and confirmed petroleum impacts above regulatory thresholds and recommended soil removal. No records are available indicating the impacts were remediated. In March 2020, H&H conducted Brownfields assessment activities involving the collection of soil, groundwater, and soil gas samples (details provided in the Contaminated Media section below). A receptor survey was also performed on and around the Brownfields Property to evaluate land use, water supply, basements, underground utilities, drains, and surface water bodies. Three potential water supply wells were identified within a 1,500 ft radius of the property. The private water supply wells were identified as being located about 650 feet southwest of the property and another about 1100 feet northwest of the property, and an irrigation well was identified about 1200 feet southwest of the property. In December 2020, H&H conducted additional assessment to further investigate the potential for methane in soil gas based on the 2003 photographic evidence of buried wood debris on the property. Trenching performed on December 29, 2020 revealed the presence buried construction debris including lumber, tree stumps, bricks, and tile in the western portion of the property. Buried debris was present at depths up to 15 ft bgs. The prospective developer plans to remove the debris and replace it with structurally suitable back fill during redevelopment activities. Potential Receptors: Potential receptors include residents, on-site workers, construction workers, and visitors. Contaminated Media: DEQ has evaluated data collected from the following media at the subject property: soil, groundwater, and soil gas. DEQ relies on the following data to base its conclusions regarding the subject property and its suitability for its intended reuse. Soil Soil sampling events occurred on the Brownfields Property in April 1990, May-October 2003, and March 2020. Upon removal of the UST in 1990, Aquaterra collected soil samples from the sidewalls and base of the excavation for analysis of total petroleum hydrocarbons (TPH) as diesel- range organics (DRO) and TPH gasoline-range organics (GRO). Analytical results indicated that no compounds were detected above the laboratory reporting limits. In September and October 2003, Froehling & Robertson, Inc., collected soil samples near the former UST dispenser island and product lines for analysis of TPH-GRO. Laboratory results indicated that no compounds were detected above the laboratory reporting limits. Based on results of the additional soil sampling activities, DEQ issued a No Further Action letter for the UST closure on October 29, 2003. In the Spring of 2003, MACTEC collected three soil samples from the western area of the property where a 4,000-gallon waste oil/water spill occurred in 2001. Those analytical results are not provided, but the June 20, 2003 Soil Cleanup Report notes that concentrations of TPH, Oil and Grease, total arsenic and chromium exceeded the regulatory levels, prompting the recommendation to remove affected soil. In May 2003, after removing 1,546 tons of soil, 13 soil samples were collected from the base of the excavation and analyzed for TPH, Oil and Grease (Method 9071). No concentrations were found exceeding the standard at the time of 250 mg/kg. In July 2003, MACTEC completed a Phase I Environmental Site Assessment (ESA) followed by soil sampling in August 2003 in an area of soil staining near the above ground storage tanks (ASTs). Analysis of soil from 0-1 ft bgs in boring B-1 (location shown below) indicated TPH-DRO at 4,100 mg/kg and TPH-GRO at 340 mg/kg, both exceeding the current DEQ screening criteria of 100 mg/kg and 50 mg/kg respectively. The analysis of soil at 3 ft bgs in B-1 indicated TPH-DRO at 79 mg/kg and TPH-GRO 2.8 mg/kg. No records are available indicating the impacts were remediated. Soil assessment activities in March 2020 included collecting grab and composite soil samples to assess the former solidification pad, the AST containment basin, and the south-central storage building. Composite samples were analyzed for SVOCs and RCRA metals and hexavalent chromium, and associated grab samples were analyzed for VOCs. The grab sample from the former solidification pad was also analyzed for PCBs. Soil from soil gas boring SGP-5 was collected based on screening results and was analyzed for VOCs, SVOCs, RCRA metals and hexavalent chromium. Two background samples were analyzed for RCRA metals and hexavalent chromium. VOCs: Acetone was detected in each sample but only at trace estimated levels well below the Residential PSRG of 12,000 mg/kg. The only other sample where VOCs were detected was the storage shed sample SGP-5. Notable compounds detected include naphthalene, ethylbenzene, and 1,2,4- and 1,3,5- trimethylbenzenes, but all detections were well below the Residential PSRGs. SVOCs: Naphthalene was the one SVOC detected and was only found in SGP-5 at an estimated concentration of 0.11 J mg/kg, below the Residential PSRG of 2.1 mg/kg. Metals: Arsenic, barium, trivalent chromium, hexavalent chromium, lead, mercury, and selenium were detected in soil, and all results were within the range established by the background soil samples BG-1 (0-3 ft bgs) and BG-2 (0-3 ft bgs). Arsenic and hexavalent chromium were the only two metals detected that exceed the PSRGs. Arsenic was detected in all soil samples at concentrations ranging from 1.73 mg/kg (SGP-5) to 6.47 mg/kg (BG-2). All five arsenic detections exceed the Residential PSRG of 0.68 mg/kg, and three detections exceed the Industrial PSRG of 3.0 mg/kg. Estimated concentrations of hexavalent chromium were reported in the background samples ranging from 0.415 J mg/kg in BG-1 to 0.584 J mg/kg in BG-2. Hexavalent chromium in the remaining samples was below the laboratory reporting limit, but the lab reporting limits (<0.321 – <0.349 mg/kg) also exceed the Residential PSRG of 0.31 mg/kg. Groundwater Groundwater sampling occurred on the Brownfields Property in March 2020. The March 2020 Brownfields assessment included installing four temporary monitoring wells (TMW-1 through TMW-4). The wells assessed groundwater down-gradient of the solidification pad (TMW-1), at the upgradient boundary (TMW-2), cross-gradient from the adjacent Old Pineville Road Brownfields Property (TMW-3), and at the down-gradient property boundary (TMW-4). Water-level elevations suggest a groundwater divide in the eastern portion of the property with groundwater at most of the property flowing west-southwest with groundwater flowing east-northeast in the eastern-most portion of the property. Groundwater samples were analyzed for VOCs, SVOCs, and RCRA metals. VOCs: Toluene was the only VOC detected in groundwater at the property. Concentration in TMW-2 (0.28 J ug/L) and TMW-3 (1.7 ug/L) are well below the 2L Standard of 600 ug/L and the Residential Groundwater Vapor Intrusion Screening Level (GW VISL) of 3,800 ug/L. SVOCs: All SVOCs analyses were below laboratory method detection limits. Metals: Arsenic, barium, cadmium, total chromium, and selenium were reported in groundwater, but all concentrations were below their respective 2L Standards. Surface Water Surface water bodies are not present on the Brownfields Property. Soil Vapor In March 2020 seven temporary soil gas sampling points were installed to evaluate the vapor intrusion potential. Points SGP-1 through SGP-3 were placed in the proposed northern townhome footprint, SGP-4 through SGP-6 in the proposed southern townhome footprint, and SGP-7 in the proposed eastern townhome footprint. Soil gas borings were installed to depths of 5 to 12 ft bgs. Field screening of soils recovered from each boring indicated the presence of potential impacts at 2-4 ft bgs in SGP-5 (see soil discussion above). Several VOCs were detected at each point and the notable detections that exceeded the Residential Soil Gas (SG) VISLs (based on a cancer risk of 1.0E-6 and an HQ of 0.2) were naphthalene, ethylbenzene, 1,2,4- trimethylbenzene, and 1,3,5- trimethylbenzene. The DEQ Risk Calculator was used to further evaluate the potential risk from vapor intrusion. The highest soil gas concentration of each parameter was used to calculate the potential for indoor air risk. This worst-case scenario calculated a residential carcinogenic risk of 9.6x10-5 and a residential non-carcinogenic (HI) Hazard Index of 6.5. In December 2020, trenching activities were conducted in the western portion of the property to locate possible buried debris and assess the presence of methane. Buried debris was discovered in Areas 1, 2 and 3 identified in green on the map below. Plywood and planks were found at 3-4 ft bgs in Area 1; bricks and tiles were found in Area 2 from 5-15 ft bgs; and bricks, fence posts, tree trunks and other organic debris were discovered in Area 3 at 5-9 ft bgs. Field screening for landfill gases was conducted during trenching activities using a calibrated Landtec GEM 5000. The only methane detected during screening was in Area 3 at 4-5 ft bgs at 0.2% by volume (4% LEL). Screening detected no methane below the buried debris in Area 3. As a proactive measure, the prospective developer plans to remove the debris and import structurally suitable back fill during redevelopment activities. Post-removal methane monitoring will also be required. Sub-Slab Vapor Sub-slab vapor samples under the existing structures on the Brownfields Property were not collected because all buildings will be demolished prior to construction of the townhomes. Indoor Air Indoor air at the Brownfields Property was not collected because all buildings will be demolished prior to construction of the townhomes. 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 calculate risk based on data available for media including soil, groundwater, and soil gas. Risk Calculation Table 1 displays the risk calculated for the Brownfields Property using the maximum soil, groundwater, and soil gas concentrations from the assessment reports excluding the TPH results for B-1. Risk Calculation Table 2 displays risk associated with maximum concentrations in soil sample near the AST area (B-1, COMP-2, SB-2A, and SGP-5). Based on the detections of metals and organic compounds in soil, restrictions regarding soil will be imposed at the site. Based on the 2003 TPH data from B-1, impacted soil in the area of the AST containment system should be removed during AST decommissioning or building demolition. While groundwater on the Brownfields Property does not appear to be impacted above the 2L Standards, a groundwater use restriction should be included because the dataset is very limited and other potential contaminant sources are in the vicinity of the property. Since the site is intended for residential use as townhomes and the soil gas to indoor air risks (using maximum concentrations from the site) indicate an HI of 6.5, vapor intrusion mitigation (VIM) systems (minimum passive systems capable of converting to active systems) are required for each townhome building, in accordance with the Brownfields Program Minimum Requirements for Townhome Developments, dated May 2020, this will be included in the BFA as Ex.3. On December 29, 2020, H&H confirmed the presence of buried construction debris in the western portion of the property and field screening detected methane at one location near the debris. The prospective developer plans to remove the debris and import structurally suitable back fill during redevelopment activities. Based on the presence of methane near buried debris, post-removal methane soil gas testing is required to demonstrate that methane is not an issue for the proposed town home development. On February 15, 2021, DEQ requested a methane soil gas sampling work plan be submitted for approval prior to the start of development activities. The Environmental Management Plan (EMP) approved by DEQ on December 23, 2020, will need to be followed to safely direct the handling and disposal of potentially contaminated materials when building demolition, soil grading, or excavation activities begin. Per the terms of the EMP and the LUR, final grade soil sampling will be required prior to occupying the Brownfields Property. Required Land Use Restrictions: • No use other than multi-family residential and associated parking, drives, and walkways without DEQ approval. • HOA Declarations • Townhomes allowed, so Townhome Min requirements • Methane monitoring post-debris removal • No childcare, adult care centers or schools without DEQ approval • EMP required prior to redevelopment • Annual development summary report required • Demolition must comply with state & local requirements • ASTs must be removed with 90 days of recordation • No use of groundwater or surface water • No soil import/export without DEQ approval • Final grade sampling required • No soil disturbance without DEQ approval or EMP • Vapor intrusion mitigation required • DEQ shall not be denied access • Any required wells or vapor points must be maintained • Deed or other instrument conveying an interest shall contain the Notice • No use of contaminants known to be present on the BF Property • Annual LURU to DEQ Based on the site-specific data provided to the Brownfield program, the site is suitable for the approved uses only if the agreed upon land use restrictions in the BFA are abided by.