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DocuSign Envelope ID: FC9986C3-F179-4A3D-BACO-D8CA9F8B93A7 <br /> Proposal for Additional Remedial Investigation <br /> Hillsborough Dump <br /> ID No. NONCD0000483 <br /> Task Orders 483DP-19 thru 25 <br /> S&ME Project No.4305-17-061G <br /> Task 483DP-22 Monitoring Groundwater and Landfill Gas from Existing Well and Probe <br /> Groundwater samples will be collected from monitor well MW-4 and landfill gas will be collected from landfill gas <br /> probe GP-6 in accordance with the methods described in S&ME's Standard Operating Procedures and Quality <br /> Assurance(SOP/QA)Manual and NCDEQ PRLF Guidance. <br /> Groundwater Sampling_S&ME will gauge depth to water and collect groundwater samples for analysis by a North <br /> Carolina certified laboratory by the following analytical methods: <br /> VOCs by EPA Method 8260 <br /> 1,4-Dioxane by Method 8260 SIM <br /> SVOCs by Method 8270 <br /> Metals by totals analysis (antimony,arsenic, beryllium, cadmium,chromium,copper, iron, lead, <br /> manganese, nickel,selenium, silver,thallium, and zinc) by Method 6020 and 7470/7471 <br /> Ammonia by Method 350.1 <br /> Nitrate and Sulfate by Method 300 or 353.2 <br /> Landfill Gas Probe Sampling_ Batch-certified sampling canisters will be used to collect landfill gas samples from <br /> gas probe GP-6 for laboratory analysis of VOCs by Method TO-15. If methane is detected in a new landfill gas <br /> probe, the landfill gas sample will also be analyzed for mercury by NIOSH Method 6009. Two quality control (QC) <br /> duplicate samples (one for VOCs and one for mercury) will be collected concurrently. <br /> Sample trains will be used that include Teflon tubing, rotometer,valves, gauges,tubing fittings,flow control valve <br /> and sample canisters. After each sampling train is connected, a leak tightness check will be conducted prior to <br /> sample collection. <br /> Vacuum - Leak Tightness Check: <br /> Close the valve at the top of the PVC landfill gas probe. <br /> Ensure that all connections are made, and valves are in correct positions to allow flow from only the <br /> sample train into the sample canister.There should be no flow from the landfill gas probe or from <br /> ambient air sources. <br /> Open the valve to the sample canister to allow flow to the canister only(there should be no flow, as the <br /> valve to the landfill soil gas probe remains closed). <br /> Record the vacuum pressure on the gauge on the sample canister for at least three minutes. <br /> If a change of vacuum is recorded at more than +/- 5 mm of mercury,stop the leak check and check all <br /> fittings and adjust as needed. <br /> Recheck and readjust as needed to ensure that the sample train has no leaks and vacuum pressure <br /> changes are within +/- 5 mm of mercury or less. <br /> March 10, 2022 4 <br />