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ADVISORY - ACTIVE SOIL GAS INVESTIGATIONS <br />7.0 METHANE AND HYDROGEN SULFIDE SAMPLING PROGRAMS <br />7.1 METHANE <br />There are several analytical methods appropriate for methane, including: <br />USEPA Methods 8015B modified; <br />TO-3, 3C; <br />ASTM Method D1945; or <br />ASTM Method D1946. <br />Methane may also be measured with a hand held gas emissions monitor or analyzer. <br />The RLs for methane analysis should be determined by project-specific DQ0s. <br />7.1.1 Methane Field Collection <br />The following procedures should be followed when collecting samples for methane <br />analysis: <br />Methane should be collected in gas-tight sample containers such as passivated <br />stainless steel canisters or polymer gas sampling bags. <br />Fixed and biogenic gases such as oxygen, carbon dioxide, methane and <br />ethylene should be analyzed to determine whether methanogenesis is occurring. <br />The RL for oxygen and carbon dioxide should be one percent or less. <br />Prior to sampling, tubing or probe pressure should be recorded in the field logs <br />and reported along with the methane concentration to determine if the area is <br />pressurized. <br />7.1.2 Methane Laboratory Analysis <br />GC calibration curves for methane should be recorded and reported. Hand-held <br />instruments should be calibrated in accordance with the manufacturer's specifications. <br />At least 10 percent of all positive detections with concentrations more than 5,000 parts <br />per million by volume (ppmv) should be confirmed by another hand-held instrument <br />(either different unit or a different brand) or by a GC method when a hand-held <br />instrument is used. <br />7.2 HYDROGEN SULFIDE <br />Hydrogen sulfide may be analyzed using: <br />South Coast Air Quality Management District Method 307-91; <br />ASTM D5504; <br />USEPA Method 16; <br />DraegerTM tubes; or <br />Other equivalent methods. <br />July 2015 40