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DocuSign Envelope ID: FC9986C3-F179-4A3D-BACO-D8CA9F8B93A7 <br /> AVIEW <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 /> Field Screening of Landfill Gas <br /> Upon completion of landfill gas sampling, S&ME will field-screen for the presence of landfill gas. Prior to <br /> screening, S&ME will gauge depths to water(if any) in the probe. Portable meters will be used to collect the <br /> following parameters: <br /> Landfill Gas Meter—GEM5000 PLUS for: <br /> o methane: 0-100%, +/-0.5%to 3.0%accuracy <br /> o hydrogen sulfide: 0-500 ppmv,with +/- 50 ppmv resolution <br /> o carbon dioxide: 0-100%, +/- 0.5%to 3.0%accuracy <br /> 0 oxygen:0-25%, +/- 1.0%accuracy <br /> o barometric pressure: +/- 5.9 inches mercury from calibration pressure, +/- 0.15 inches mercury <br /> accuracy <br /> Mercury Analyzer-Jerome 431X for mercury: Detection Range of 0.003 mg/m3 to 0.999 mg/m3, ±5% at <br /> 0.100 mg/m3 accuracy. <br /> Photo-Ionization Detector- MiniRAE 3000 PID for total VOCs: 0-15,000 ppmv,with +/-0.1 ppmv <br /> resolution over range of 0 to 999.9 ppmv and +/- 1 ppmv resolution over range of 1,000 to 15,000 ppmv. <br /> Thermohygrometer-Will be used to measure ambient air for humidity, and temperature. <br /> The GEM5000 PLUS and PID have internal pumps. New Teflon tubing will be connected from the meters to each <br /> gas probe cap for sampling. <br /> For field instruments used,the following information will be recorded and provided in the appendices of the <br /> report: manufacturer, model number, serial number, date of factory calibration and maintenance, set up <br /> parameters, and detection limit. <br /> Instruments will be calibrated in the field following manufacturer recommendations for each instrument. A <br /> summary of field calibration procedures used (using those recommended by the manufacturer) and bump tests <br /> (to verify full calibration and instrument accuracy) performed before, during and after evaluation,will be <br /> documented. Additional field calibrations that may be required for changing field conditions(such as barometric <br /> pressure or temperature)will be documented. Types of calibration gasses and their expiration dates will also be <br /> documented. <br /> The following steps will be followed: <br /> Step 1 —Calibrate the instruments according to the manufacturer's specifications. In addition, prepare the <br /> instruments for monitoring by allowing them to properly warm up as directed by the manufacturer. <br /> Make sure the static pressure shows a reading of zero on the instruments with this feature, prior to <br /> taking the first sample. <br /> Step 2—Connect the instrument tubing to the landfill gas monitoring well cap fitted with a valve. Purge <br /> sample tubing for at least one minute prior to taking readings. <br /> Step 3—Record the initial readings prior to recording the stabilized readings.A stable reading is one that <br /> does not vary more than 0.5 percent by volume on the instrument's scale. <br /> Step 4—Record the stabilized readings. <br /> Step S—Disconnect the tubing and turn the valve to the off position. <br /> Step 6—Proceed to the next landfill soil gas probe and repeat Steps 2—5. <br /> March 10, 2022 5 <br />