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Home My WebLink About21034_Soil and Soil Gas Workplan 20180103 SOIL AND SOIL GAS SAMPLING WORK PLAN 1300 SOUTH TRYON STREET CHARLOTTE, MECKLENBURG COUNTY, NORTH CAROLINA BROWNFIELDS PROJECT ID. 21034-17-060 ECS PROJECT NO. 49.4161-C PREPARED FOR CBG REAL ESTATE, LLC December 18, 2017 Soil and Soil Gas Sampling Work Plan 1300 South Tryon Street Charlotte, Mecklenburg County, North Carolina ECS Project No. 49-4161-C December 18, 2017 1 TABLE OF CONTENTS 1.0 PROJECT INFORMATION ........................................................................................ 2 2.0 PREVIOUS INVESTIGATIONS ................................................................................. 2 3.0 OBJECTIVE OF THE WORKPLAN ........................................................................... 3 4.0 SAMPLE COLLECTION ............................................................................................ 4 FIGURES Figure 1 Site Location Map Figure 2 Sample Location Map TABLES Table 1 Groundwater Sample Results Soil and Soil Gas Sampling Work Plan 1300 South Tryon Street Charlotte, Mecklenburg County, North Carolina ECS Project No. 49-4161-C December 18, 2017 2 1.0 PROJECT INFORMATION The Site is currently comprised of one parcel identified as Mecklenburg Parcel ID No. 07307210 located in Charlotte, Mecklenburg County, North Carolina. The site is owned by CBG Real Estate, LLC and is approximately 0.332-acres in size and is occupied by a 5,946 square foot commercial building and associated parking areas. The location of the Site is shown on Figures 1 and 2. 2.0 PREVIOUS INVESTIGATIONS ECS conducted a Phase I Environmental Site Assessment (ESA) of the site on April 5, 2017. It appears the site was developed as a commercial property circa 1955, including a ‘cold storage’ building depicted on a 1969 Sanborn Map. Refrigerants, including Freon, ammonia, and glycols are a potential contamination source. A review of the 1929, 1951, 1953, 1962, and 1969 Sanborn Maps depict off-site sources of contamination in close proximity to the site including the presence of “G.T’s (gas tanks)” west-northwest of the site, a welding and auto repair facility north-northwest of the site, and a used auto facility northeast of the site across West Catherine Street. ECS concluded the historic use of the site as a cold storage facility and the nearby off-site sources of contamination to be RECs of the site. ECS conducted a groundwater assessment of the site in May 2017. A ssessment activities included collection of groundwater samples to evaluate the potential for impacts associated with on-site and off-site RECs. ECS collected four groundwater samples via groundwater sampling direct-push technology (DPT) probes. The four borings were advanced on the site, two along the northeast side of the building (GW-1 and GW-2), and two adjacent to the street (GW-3 and GW-4). The borings were also installed downgradient of the offsite RECs. Laboratory analysis of the groundwater samples collected from borings GW-2, GW-3, and GW-4 detected ammonia at concentrations ranging from 0.13 mg/L to 0.37 mg/L which is below the North Carolina Interim Maximum Allowable Concentration (IMAC) of 1.5 mg/L. Ammonia was not detected in the sample collected from GW-1. Laboratory analysis of the samples collected from GW-1 and GW-2 detected tetrachloroethene (PCE) at concentrations above the North Carolina 2L Groundwater Quality Standard (NC2LGWQS) but below the Residential Vapor Intrusion Screening Levels (VISLs). The sample collected from GW-3 detected Methyl-tert-Butyl-Ether (MTBE) at a level below the NC2LGWQS. Analysis of the sample collected from GW-4 detected isopropyl ether at a concentration below the NC2LGWQS and MTBE at a concentration above the NC2LGQS but below the VISLs. Both isopropyl ether and MTBE are associated with unleaded gasoline. The location of the groundwater samples are shown on Figure 2 and a summary of the groundwater analytical results are summarized in Table 1. Depth to groundwater is approximately 25 feet below grade. Soil and Soil Gas Sampling Work Plan 1300 South Tryon Street Charlotte, Mecklenburg County, North Carolina ECS Project No. 49-4161-C December 18, 2017 3 3.0 OBJECTIVE OF THE WORKPLAN The objective of this work plan is to evaluate the potential for a vapor intrusion concern for the future use of the site and to obtain volatile organic compounds (VOC) and semi-volatile organic compounds (SVOC) and total RCRA metal concentrations in the soil at the site. The soil and soil gas sampling will be conducted in general accordance with the North Carolina Department of Environmental Quality’s (NCDEQ) Vapor Intrusion Guidance (April 2014) and the NCDEQ Inactive Hazardous Site Program’s Guidelines for Assessment and Cleanup (October 2015). The proposed sampling plan was also discussed during a telephone call with Mr. Bill Schmithorst on September 25, 2017. ECS is proposing samples be collected in the area for the proposed building pad to “forecast” worse case conditions that might develop under the proposed building. To determine this, three exterior soil gas samples are proposed. In addition to the soil gas samples, ECS will collect three soil samples for analysis of VOCs, SVOCs, and total RCRA metals. Owner and Prospective Developer’s Representative: Mr. Niall Hanley CBG Real Estate, LLC P.O. Box 12526 Raleigh, North Carolina 27605 919-412-2262 niall@hibernianco.com Site Environmental Representative: Mr. John M. Stewart, P.G. ECS Southeast, LLP 4811 Koger Boulevard Greensboro, North Carolina 27407 336-856-7150 JStewart1@ecslimited.com Reporting A report of the results of the sampling outlined in this work plan will be submitted to NCDEQ- Brownfields Program. If unidentified and unexpected conditions are encountered during the assessment, CBG Real Estate, LLC will be notified. The responsibility of notifying NCDEQ and other external parties lies solely with CBG Real Estate, LLC and/or with ECS acting on their behalf. The NCDEQ Brownfields Program (NCBP) contact is: Bill Schmithorst, Brownfields Project Manager William.Schmithorst@ncdenr.gov NCDEQ, DEQ, NC Brownfields Program Phone: 919-707-8159 Bill Schmithorst, the Brownfields Project Manager, will be notified 5 days prior to starting the field Soil and Soil Gas Sampling Work Plan 1300 South Tryon Street Charlotte, Mecklenburg County, North Carolina ECS Project No. 49-4161-C December 18, 2017 4 work. Deviation from Approved Plan This work plan is intended to be dynamic and to be adapted to specific and actual site conditions. Accordingly, should such conditions warrant a change either by addition, deletion or modification of a procedure, such may be accomplished with agreement between CBG Real Estate, LLC’s representative and ECS after consultation with, and subject to approval by the NCBP. Such changes will comply with applicable local, State, and Federal rules and regulations. A written amendment shall be prepared and submitted to NCBP for approval (the use of e-mail correspondence shall suffice for approval, followed by a hard copy or electronic copy provided on Disk or similar media) prior to implementation. 4.0 SAMPLE COLLECTION 4.1 Soil Gas Number and Sample Location ECS is proposing to collect samples from three locations across the site. The exterior soil gas samples will be collected from a depth of 5 feet below grade. The approximate locations of the proposed samples are shown on Figure 2. Probe Placement and Sample Collection The exterior soil gas samples will be collected by advancing a decontaminated hand auger to a depth of 5 feet below the ground surface (bgs). The soil samples collected in the hand auger will be screened in the field with a flame/photo-ionization detector (FID/PID). Once the boring has reached termination depth, dedicated Nylafow tubing and air stone will be lowered into the boring. Approximately one foot of clean coarse sand will placed around the air stone. A seal consisting of three feet of bentonite powder will be hydrated with distilled water. The soil gas probe will be allowed to stabilize for 24 to 48 hours before the soil gas sample is collected. A dedicated syringe will be used at each sample location and connected to the tubing to purge the tubing and annular space around the sample probe.. Three volumes of the tubing will be purged prior to sample collection. As the tubing is purged, evidence of water entering the tubing will be noted. Following purging, the tubing will be connected to a 400 ml Summa canister, which will be used to collect the sample. The Summa canister will be fitted with a flow regulator. The flow rate for both purging and sample collection will be 0.2 liters per minute. The pressure in the canister will be recorded before and after sample collection while making sure the vacuum does not reach zero. Other parameters that will be measured include ambient temperature before and after sample collection and recent weather conditions. Prior to sample collection a shut-in test will be conducted to assess for leaks in the fittings and regulator. The probes will be removed and the holes filled cement grout following sample collection. Soil and Soil Gas Sampling Work Plan 1300 South Tryon Street Charlotte, Mecklenburg County, North Carolina ECS Project No. 49-4161-C December 18, 2017 5 Leak Detection Prior to collecting the soil vapor samples, laboratory grade helium gas will be used as a quality assurance control measure to confirm the integrity of the probe seal at each sample location. A plastic cylinder (approximately 1.75 quarts) will be placed and sealed over the sampling point and purged with laboratory grade helium. The probe point tubing and tracer gas tubing will be placed through the cylinder wall via rubber grommets. The cylinder will be placed on a 4-inch rubber gasket and held securely to the slab with a heavy weight. During the purging stage, the cylinder will be flooded with laboratory grade helium via the hose placed through the cylinder wall. A Model MGD-2002 Multi-Gas Leak detector or similar will be connected to the probe tube and the air stream being purged will be measured for helium. A helium concentration of less than five percent helium will be considered acceptable. If concentrations greater than five percent helium are measured, the probe tube seal will be reseated and the leak detection process will be repeated. Sample Analysis Following sample collection, the canisters will be labeled and maintained under chain-of-custody until delivered to H&P Mobile Geochemistry Inc. in Carlsbad, California. A Chain-of-Custody document will be utilized throughout the collection and transportation of the samples. Each sample will be analyzed for VOCs using EPA Method TO-15. The laboratory results will be reported at or below the applicable vapor intrusion screening levels (VISL) and J Flags will be reported. Following collection of the soil gas samples, the probes will be removed and the borings will be filled and capped with asphalt. Quality Control One duplicate sample will be collected and analyzed for the same compounds using EPA Method TO-15. 4.2 Soil Samples Three soil borings will be advanced to a depth of 5 feet below the ground surface. A soil sample will be collected from each boring between the ground surface and a depth of 5 feet. More specifically, as the soil borings are advanced, the soil will be classified in the field by an ECS professional and screened for volatile organic vapors using a FID/PID. Visual signs of a release such as staining will also be noted and placed on the soil bore log. The soil sample from each boring showing the greatest FID/PID reading will be selected for analysis. If no organic readings are detected or the readings are all essentially the same, then the sample from a depth of two feet will be selected for analysis. Each sample will be packaged and submitted to a North Carolina certified laboratory to be analyzed for VOCs and SVOCs using EPA Method 8260 and 8270, respectively, and total RCRA metals using EPA Methods 6020/7470/7471. One sample will be analyzed for hexavalent chromium. The laboratory results will be reported at or below the Industrial/Commercial Preliminary Health-based Soil Remediation Goal (PSRGs) and J Flags will be reported. Soil and Soil Gas Sampling Work Plan 1300 South Tryon Street Charlotte, Mecklenburg County, North Carolina ECS Project No. 49-4161-C December 18, 2017 6 Quality Control One duplicate sample will be collected and analyzed using VOCs and SVOCs using EPA Method 8260 and 8270, respectively, and total RCRA metals using EPA Methods 6020/7470/7471. A Level II QA/QC package will be requested from the laboratory. Report ECS will prepare a written report documenting the field activities, sampling procedures, sample locations, soil gas probe construction diagrams, laboratory procedures and results, and conclusions. Soil gas sampling field data, including leak testing and pressure readings, will be included in the report. FIGURES FIGURE 1 SITE LOCATION MAP SOIL & SOIL GAS WORKPLAN 1300 SOUTH TRYON STREET CHARLOTTE, MECKLENBURG COUNTY, NORTH CAROLINA ECS PROJECT NO. 49-4161-C SOURCE: USGS TOPOGRAPHIC MAP: DERITA & CHARLOTTE EAST, DATED 2016 NORTH CAROLINA QUADRANGLE SCALE: 1” = 2,000’ SITE LEGEND SOURCE: GOOGLE EARTH 2016 AERIAL PHOTOGRAPH (VIA THE INTERNET) SCALE AS SHOWN FIGURE 2 SAMPLE LOCATION MAP SOIL & SOIL GAS WORKPLAN 1300 SOUTH TRYON STREET CHARLOTTE, MECKLENBURG COUNTY, NORTH CAROLINA ECS PROJECT NO. 49-4161-C APPROXIMATE LOCATION OF SOIL & SOIL GAS SAMPLE PREVIOUS GROUNDWATER SAMPLE LOCATIONS GW-1 GW-2 GW-3 GW-4 TABLES Parameter Sample ID GW-1 GW-2 GW-3 GW-4 Collection Date 4/26/17 4/26/17 4/26/17 4/26/17 Screened Interval 31-35ft 31-35ft 36-40ft 36-40ft Ammonia as N Ammonia BRL 370 310 130 --1,500 3,170 13,300 Glycols Glycols BRL BRL BRL BRL -- -- -- -- Semivolatile Organic Compounds by GC/MS SVOCs BRL BRL BRL BRL -- -- -- -- Volatile Organic Compounds by GC/MS Isopropyl Ether BRL BRL BRL 2.4 70 --1,390 5,860 Methyl-tert-Butyl-Ether BRL BRL 2.2 120 20 --4,500 19,700 Tetrachloroethylene 1.5 4.0 BRL BRL 0.7 --11.5 48.4 Notes: Results presented in micrograms per liter (ug/L), analogous to parts per billion (ppb) BRL = Compound not detected at a concentration above the method reporting limit DWM = Division of Waste Management VISL = Vapor Intrusion Screening LevelBold denotes a detection above the North Carolina 2L Groundwater Quality Standard DWM Non- Residential VISL COMPARISION CRITERIA NC 2L Groundwater Quality Standards DWM Residential VISL TABLE 1: SUMMARY OF GROUNDWATER ANALYTICAL RESULTS 1300 SOUTH TRYON STREET CHARLOTTE, MECKLENBURG COUNTY, NORTH CAROLINA ECS PROJECT NO. 49-4161-B ANALYTICAL RESULTS WHITE POINT PARTNERS - PHASE II ESA Interim Maximum Allowable Concentration (IMAC)