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Home My WebLink About25008_North Hills Expansion_AWP_20210427 April 27, 2021 Brad Atkinson NC Brownfields Program NC Department of Environmental Quality Division of Waste Management Mail Service Center 1646 Raleigh, North Carolina 27699-1646 Subject: SUB-SLAB SOIL GAS ASSESSMENT WORK PLAN FORMER JC PENNEY’S AT NORTH HILLS LASITER MILL ROAD RALEIGH, NORTH CAROLINA BROWNFIELDS PROJECT NO.: 25008-21-92 MID-ATLANTIC PE LICENSE: F-0967 REVISION NO.: 1 MID-ATLANTIC JOB NO. 000R3746.02 Dear Mr. Atkinson: On behalf of North Hills Owner, LP, Mid-Atlantic Associates, Inc. (Mid-Atlantic) has prepared this revised Sub-Slab Soil Gas Assessment Work Plan associated with the redevelopment project at the Former JC Penney’s located on Lassiter Mill Road in Raleigh, North Carolina. The objective of this Work Plan is to outline environmental assessment activities requested by the North Carolina Brownfields Program (NCBP) during an onsite meeting on April 15, 2021. NCBP requested the data to augment existing soil gas data to establish more comprehensive ‘baseline’ sub-slab soil gas conditions at the site. The revisions to the April 21, 2021 are based on a telephone conversation with you on April 26, 2021. INTRODUCTION The subject site is comprised of three parcels plus a portion of a fourth parcel totaling 8.63 acres located in North Hills Mall on Lassiter Mill Road in Raleigh, North Carolina. The majority of the site is occupied by a vacant JC Penney Department Store. Data collected during assessment activities associated with a nearby Brothers dry cleaning operation and a nearby Exxon gas station indicate that groundwater at the subject site has been Sub-Slab Soil Gas Assessment Work Plan April 27, 2021 Former JC Penney’s North Hills Page 2 Raleigh, North Carolina impacted by releases originating from these sites. The contaminants released from these sites are volatile organic compounds (VOCs) including chlorinated solvents and gasoline compounds. Assessment activities conducted in association with the dry cleaners have identified VOCs in soil gas on and at properties in the immediate vicinity of the subject site. These data provide a baseline of soil gas conditions at the subject site (Drawing 1). Much of the redevelopment will involve cuts in excess of 20 feet. However, locations coincident with the currently existing building basement and parking deck, will only be cut approximately 3 to 4 feet. During the site visit on April 15, 2021, you and I inspected the basement and ground floor of the parking deck. These areas were compared to the redevelopment plans. Three sub- slab soil gas locations were identified (SG-1, 2 and 3) for additional assessment. These included two elevator banks and the office/workshop/training in the south corner of Building Y (Drawing 1). During the April 26, 2021, you requested the addition of four soil gas samples targeting the Central Elevator, the North Elevators, the North Elevator Pit and the West-Central Elevator. Since soil gas samples SG-5, 6 and 7 (Drawing 1) are located in a deep cut area (>20 feet), these samples will need to be collected using a Geoprobe rig capable of push the sample implant to a depth of 20 feet below land surface. SCOPE OF WORK Mid-Atlantic proposes the following scope of work:  Collect a total of four sub-slab soil gas samples (Drawing 1). One sub-slab soil gas sample each will be collected in the Building T/U elevator bank (SG-1), the Building Y elevator bank (SG-2), the Y Building shop/training/office area (SG-3) and the Central Elevator (SG-4).  Collect a total of three deep (20 feet below land surface) soil gas samples (Drawing 1). These locations include North Elevators (SG-5), the North Elevator Pit (SG-6) and the West Central Elevator (SG-7).  Preparation of a Soil Gas Assessment Report to document field activities and provide analysis of the data collected. SAMPLING METHODOLOGY At each sub-slab location, a rotary-impact drill equipped with a decontaminated spline drill bit will be utilized to drill a 5/8-inch diameter hole through the concrete/asphalt slab. At each location the field technician will log the materials and condition beneath the slab. A vapor sampling probe will be established using a new “Vapor Pin™”, a brass barb fitting with a silicone sleeve that creates a seal with the concrete when inserted using an installation/extraction tool. The Vapor Pin will then be fitted with ¼-inch outer diameter rigid-wall Teflon tubing to complete the vapor sampling probe assembly. A leak check will be performed at each probe location using a plastic shroud, helium gas, Sub-Slab Soil Gas Assessment Work Plan April 27, 2021 Former JC Penney’s North Hills Page 3 Raleigh, North Carolina and a portable helium gas detector. A plastic shroud will be placed over the sub-slab vapor probe location and the entire sample train with the tubing of the probe exiting the shroud through a small hole. A 3-way valve will be placed on the probe termination and connected to the sampling apparatus. Helium will be released into the shroud via tubing from the cylinder, and a grab sample collected by filling a Tedlar bag using the exhaust port of the purge syringe. Sub-slab samples will then be collected using 1-liter stainless steel canisters at a maximum flow rate of 200 milliliters per minute (ml/min). Mid-Atlantic will fill the laboratory provided Summa canister such that the final vacuum in the canister is at least three to four inches of mercury. The sub-slab samples will be collected in accordance with the NCDEQ Division of Waste Management (DWM) Vapor Intrusion Guidance Document (March 2018). At each soil-gas location, the pavement, if present, will be removed and cleared from the boring location and a boring will be advanced to a depth of 20 feet below land surface using a direct-push drill rig. One-quarter inch outer-diameter Teflon-lined tubing will be inserted into each boring to within four inches of the bottom of the boring. A screen will be placed on the tip of the tubing and a sand pack will be installed around the screen and tubing at approximately one foot from the bottom of the boring. A six- inch thick hydrated bentonite seal will be installed above the sand pack. The assembly, including the sample train, will be leak-tested prior to sampling. A laboratory-supplied Summa canister will then be attached to the tubing to collect a soil-gas sample. Air within the tubing and sand pack will be purged prior to sample collection. The sampling will be conducted in general accordance with the Vapor Intrusion Guidance (March 2018) document. LABORATORY ANALYSIS The soil gas samples will be submitted to Pace Analytical Laboratory (Pace) of Mount Juliette, Tennessee for analysis. Soil gas samples will be analyzed for VOCs in accordance with the EPA Compendium Method TO-15. The sampling and analysis plan for soil gas is summarized in Table 1. Reporting limits and method detection limits will meet applicable screening criteria including the reporting of estimated concentrations as “J” flags. Laboratory Level II QA/QC will be provided. QA/QC One duplicate soil gas sample will be collected in the field. The duplicate sample will be analyzed for EPA Compendium Method TO-15 (Table 1). The laboratory provided Summa canisters will be closed with a final vacuum in the canister is at least three to four inches of mercury to assist in the evaluation of sample integrity during transit. The chain-of-custody will be completed in the field and packed with the samples. The Mid-Atlantic field technician will return to the office with the packed boxes which will be shipped to the laboratory located in Mount Juliette, Tennessee. TABLE AnalysisSG‐11 Sub‐slab1SG‐21Sub‐slab1SG‐31Sub‐slab1SG‐41Sub‐Slab1SG‐5120 feet bls1SG‐6120 feet bls1SG‐7120 feet bls1Duplicate Sample1 TOTALS:8bls = below land surfaceNorth ElevatorsNorth Elevator PitWest‐Central ElevatorBuilding T/U ElevatorsTABLE 1SAMLPING AND ANALYSIS PLAN SUB‐SLAB SOIL GAS ASSESSMENTFORMER JC PENNEY'S NORTH HILLS LASSITER MILL ROADRALEIGH, NORTH CAROLINASamplesEPA Method TO‐15Samples Location Sample IDProposed # of SamplesProposed Sample Interval Building Y ElevatorsBuilding Y Offices/Workshop/TrainingCentral ElevatorSub‐Slab Soil Gas SamplesDeep Soil Gas Samples DRAWING UPUPR(7A,/101 S7A,R 1S101).&.&.A102101A A101 A100S101A10210101D/(AS,1*A1002)),&( 21(A1032)),&( 7:2A104R(S,D(17 (17R<A101DR< &/(A1 /2&.(RSA113A0(A11A101BA103 A104 A108A1060(&+.A106A9A10A107A113B +354.83+355.33+377.5012 treads @ 7"R(+7')0A,17(1A1&(S+2P1137RA,1,1*100BR(A.112:22D S+2P114/AU1DR< S72RA*(101D,SPA7&+110)SA((/(9A72RSA1D/2BB<:20(1'S/2&.(RR2200(1'S/2&.(RR220(/(&7R,&A/D2&. 2)) ,&( JIE