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Home My WebLink About12033 N Tryon Auto Repair Vapor Intrusion Evaluation_20130205 Vapor Intrusion Evaluation Auto Repair Shop Property 2109 North Tryon Street Charlotte, North Carolina H&H Job No. CLT-300 February 5, 2013 Via Email February 5, 2013 NC DENR Brownfields Section 1314 Mallard Ridge Rd Tega Cay, SC 29708 Attn: Carolyn F. Minnich Re: Auto Repair Shop Property Vapor Intrusion Evaluation 2109 North Tryon Street Charlotte, North Carolina H&H Job No. CLT-300 Dear Carolyn: This vapor intrusion evaluation was conducted on the referenced property to facilitate Brownfield planning. The subject automobile repair shop currently occupies a 0.17-acre parcel that fronts North Tryon Street. The rest of the property is comprised of an automobile storage lot. A residence (1930s - 1940s), a dry cleaner (1940s - 1970s), and an automotive radiator repair shop (1970s - 1990s) previously occupied the site. A site location map is included as Figure 1 and a site map is included as Figure 2. Step 1: Groundwater Screening Because the property is small and the surrounding properties have been assessed, one groundwater sample collected in June 2009 from a temporary monitoring well (RS-DPT-1) located along North Tryon Street has been analyzed. This temporary well was installed to 25 ft below ground surface (bgs) with a pre- packed well screen. Following well installation, H&H allowed the water level to equilibrate in the temporary well and measured the depth-to-water. Groundwater was encountered at approximately 17 ft bgs. Following depth-to-water measurement, H&H purged each temporary monitoring well utilizing a peristaltic pump and low flow purging methods, and the water quality parameters (pH, conductivity, temperature, and turbidity) were measured. H&H then collected a groundwater sample after stabilization of the water quality parameters. The groundwater sample was analyzed for volatile organic compounds (VOCs) by EPA Method 6200B, polycyclic aromatic hydrocarbons (PAHs) by EPA Method 8270D, Carolyn F. Minnich February 5, 2013 Page 2 S:\AAA-Master Projects\City of Charlotte - CLT\CLT-300 Brownfield Grant Activities\North Tryon Vapor Intrusion Evaluations\Auto Repair Vapor Evaluation\Auto Repair Vapor Intrusion Evaluation.docx RCRA metals by EPA Method 6010, and hexavalent chromium by EPA Method 7196A. No VOCs or PAHs were detected in RS-DPT-1. Concentrations of barium, chromium (total), and hexavalent chromium were detected in the groundwater sample. However, these metals detections are not considered relevant to this vapor evaluation. To further evaluate potential vapor intrusion at the site, groundwater data from the adjacent property to the south, the Swofford property, was evaluated. A 1,1-DCE plume underlies the Swofford property, and may have migrated onto the subject site. Therefore, to conduct this evaluation, off-site Swofford monitoring wells closest to the subject property (MW-6 and MW-7) were included in the evaluation. In addition, a cross-gradient well (MW-2) located on the Nisbet Oil Property, and a cross-gradient Swofford temporary monitoring well located south of the subject property (SA-DPT-1) were also incorporated into this evaluation. Historical groundwater analytical data for the previously described monitoring wells is included on Table 1. Only Swofford property monitoring wells MW-6 and MW-7 indicated impacts exceeding the IHSB screening criteria. As suspected based on the Swofford property history, 1,1-DCE is present in both wells at concentrations exceeding both the ISHB residential and industrial/commercial vapor intrusion screening criteria. TCE was detected in MW-6 and trichlorofluoromethane was detected in MW-7; both at concentrations exceeding the IHSB residential screening criteria. Historical 1,1-DCE concentrations are depicted on Figure 2. MW-6 and MW-7 are located approximately 60 ft and 20 ft upgradient of the subject site, respectively. Based on the proximity to the subject property, there is potential that groundwater impacts exceeding the vapor intrusion screening criteria are present on the northwestern portion of the subject property. Step 2: Soil Vapor Assessment/Screening Soil vapor assessment has not been conducted at the property to date. H&H recommends that one soil gas sample be collected in the western portion of the site, downgradient of MW-6 and MW-7. This sample should be analyzed for 1,1-dichloroethene, trichloroethene, and trichlorofluoromethane, at a minimum. A proposed soil gas sample location is shown on Figure 2. Carolyn F. Minnich February 5, 2013 Page 3 S:\AAA-Master Projects\City of Charlotte - CLT\CLT-300 Brownfield Grant Activities\North Tryon Vapor Intrusion Evaluations\Auto Repair Vapor Evaluation\Auto Repair Vapor Intrusion Evaluation.docx Step 3: Indoor Air Sampling This step has not been conducted at the property to date. Step 4: Recommendations Based on our review of available data, H&H recommends conducting soil vapor sampling as noted above in Step 2 to determine if a vapor intrusion risk exists at the subject site. Should you have any questions or require any additional information concerning this submittal, please feel free to contact me at (704) 586-0007. Sincerely, Hart & Hickman, PC Bruce Hickman Principal Engineer Attachments cc: David Wolfe, City of Charlotte (Electronic Copy) Cindy Nolan, US EPA (Hard Copy) Geoffrey Curme, Mount Vernon Asset Management, LLC (Hard and Electronic Copy) Peter McGrath, Moore & VanAllen (Electronic Copy) S:\AAA-Master Projects\City of Charlotte - CLT\CLT-300 Brownfield Grant Activities\North Tryon Vapor Intrusion Evaluations\Auto Repair Vapor Evaluation\2009 Soil and GW Sampling Results Property Auto Repair Swofford Swofford Swofford Nisbet Sample ID RS-DPT-1 SA-DPT-1 MW-6 MW-7 MW-2 Date 6/19/2009 6/19/2009 2/25/2009 2/25/2009 11/24/2008 VOCs (6200B) Chloroform <1.0 <1.0 <1.0 0.14J <0.50 7.3 351,1-Dichloroethane <1.0 <1.0 0.32 J 0.72 J 2.5 65 330 1,1-Dichloroethene <1.0 <1.0 208 389 18 38 160 1,2-Dichloroethane <1.0 <1.0 0.75 J 1.5 <0.50 20 98Dichlorodifluoromethane<1.0 <1.0 0.83 J 1.2 <1.0 1.4 6.3 Methyl tert-butyl ether <1.0 <1.0 0.28 J <1.0 <0.50 3,900 20,000 1,1,1-Trichloroethane <1.0 <1.0 146 284 12 1,500 6,300 Trichloroethene <1.0 <1.0 2.0 0.86 J <0.50 1.1 4.4Trichlorofluoromethane<1.0 <1.0 20.9 43.6 <0.50 37 160 PAHs (8270D)<11.1 NA NA NA BRL ---- RCRA Metals (6010C/7470A) Barium 104 49.2 NA NA NA ---- Chromium 9.7 6.8 NA NA NA ---- ---- Chromium (VI) (7196A)<100 68 NA NA NA ---- Notes:1) NC DENR Inactive Hazardous Sites Branch (IHSB) Residential Vapor Intrusion Screening Levels (July 2012) 2) NC DENR IHSB Industrial/Commercial Vapor Intrusion Screening Levels (July 2012) Concentrations reported in µg/LBold indicates exceedance of IHSB Residential Vapor Intrusion Screening Levels Underline indicates exceedance of IHSB Industrial/Commercial Vapor Intrusion Screening Levels Laboratory analytical method shown in parentheses J=estimated value; NS=not specified; NA=Not AnalyzedVOCs=volatile organic compounds; PAHs=polynuclear aromatic hydrocarbons 11/24/2008 and 6/19/09 groundwater samples collected by H&H 2/25/09 groundwater samples collected by Newfields Environmental on behalf of Leisch Associates, Inc. Table 1 IHSB Residential Acceptable Groundwater Concentration 1 IHSB Industrial/ Commercial Acceptable Groundwater Concentration 2 H&H Job No. CLT-300 Charlotte, North Carolina Auto Repair Shop and Surrounding Properties Summary of Historical Groundwater Sampling Results 0 2000 4000 APPROXIMATE SCALE IN FEET N U.S.G.S. QUADRANGLE MAP QUADRANGLE 7.5 MINUTE SERIES (TOPOGRAPHIC) TITLE PROJECT SITE LOCATION MAP AUTO REPAIR SHOP PROPERTY 2109 NORTH TRYON STREET CHARLOTTE, NORTH CAROLINA DATE: JOB NO: REVISION NO: FIGURE: 10-30-12 0 1 CLT-300 CHARLOTTE EAST, NC 1967 REVISED/INSPECTED 1988 DERITA, NC 1993 SITE