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DocuSign Envelope ID: 109A31 BO-29AD-4F2B-8257-8D55D4FF0808 <br /> Proposal for RI—Waste Characterization,Groundwater and Landfill Gas Monitoring <br /> Hillsborough Dump <br /> ID No. NONCDO000483 <br /> Task Orders 483 DP-13 and 14 <br /> S&ME Project No.4305-17-061 E <br /> If the well screen is shortened to accommodate shallow groundwater,a push cap will be placed onto the <br /> cut bottom of the well screen. <br /> A locking compression well plug will be installed at the top of the stick-up PVC well casing. <br /> Coarse sand (#3 sand)will be tremmied into the annulus around the PVC screen and casing from the <br /> bottom of the boring up to approximately one foot above the top of the screen. <br /> A one-foot thickness of bentonite pellets will be poured into the boring around the PVC casing from the <br /> top of the sand to one foot above the sand. The landfill gas probe will be installed to ensure that <br /> there is at least four feet from the top of the bentonite to the ground surface. Approximately one <br /> gallon of clean water will be poured into the boring to hydrate the bentonite seal. <br /> Soil from the drill cuttings will be packed into the boring from the top of the bentonite layer to the <br /> ground surface. This soil layer will be at least four feet thick. <br /> The gas probes will be finished as stick-ups,with concrete pads,protective steel casings and locks. <br /> Field Screening of Landfill. Gas: <br /> S&ME will field screen the installed gas probes(GP-1 through GP-6)for the presence of landfill gas. Portable <br /> meters will be used to collect the following parameters at each landfill gas probe location. <br /> Landfill Gas Meter--GEM5000 PLUS for: <br /> methane:0-100%, +/-0.5%to 3.0%accuracy <br /> hydrogen sulfide:0-500 ppmv,with +/- 50 ppmv resolution <br /> carbon dioxide:0-100%, +/-0.5%to 3.0%accuracy <br /> oxygen:0-25%, +/- 1.0%accuracy <br /> barometric pressure: +/-5.9 inches mercury from calibration pressure, +/-0.15 inches mercury accuracy <br /> Photo-Ionization Detector- MiniRAE 3000 PI for total VOCs:0-15,000 ppmv,with +/-0.1 ppmv resolution over <br /> range of 0 to 999.9 ppmv and +/- 1 ppmv resolution over range of 1,000 to 15,000 ppmv. <br /> A 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 /> January 16, 2020 4 <br />