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detected at a level of 5,000 ppmv or more,obtain fixed and biogenic gas valves or the equivalent; (e.g.,oxygen,carbon dioxide,methane,and ethylene)data by using a b. 100-mL gas-tight syringe fitted with an inert valve and wrapped in Thermal-Conductivity Detector(TCD)or a hand-held instrument.The RL for oxygen and carbon dioxide should be one percent or less. aluminum foil; E. Pressure Reading:Record pressure readings of each sampling tube c. Gas-tight glass bulb wrapped in aluminum foil;or system in the field logs and report along with the methane concentration to d. Glass-lined or silicon coated SUMMA°canister. determine if the area is pressurized F. Special GC Requirements:The GC method requires calibration curves D. Precautions • for analytes such as methane since it is not a normal target analyte for is. Hydrogen sulfide is avoid unstable in the presence of oxygen and such an analytical method. moisture;therefore,avoidid contact of hydrogen sulfide samples with G. Special Hand-Held Instruments Requirements: Hand-held instruments oxygen and moisture. should be calibrated in accordance with the manufacture's instructions. b. Due to the high reactivity of hydrogen sulfide gas,avoid contact of When a hand-held instrument is used to analyze methane samples, confirm at least 10 percent of all positive methane samples(e.g.,more hydrogen sulfide samples with metallic or other non-passive surfaces during sample collection,storage,and analysis. than 5,000 ppmv),rounded to the nearest whole number,by another hand-held instrument(different unit or brand)or by a GC method. - c. Care must be taken so that GC components do not react with the 2. Hydrogen Sulfide Sampling Program:Hydrogen sulfide may be analyzed sample. Typically glass-lined injection ports and Teflon'tube packed columns are used to avoid loss of hydrogen sulfide due to reaction with by a GC using the South Coast Air quality Management District(SCAQactive surfaces.307-91 or EPA Method 16;or by an appropriate hand-held instrument (e.g.,LTX-310 calibrated for hydrogen sulfide,Jerome 631-X or Drager"" 4.0 Analytical Result Reporting: tubes). A. Reporting Limit:The RL should be equal to or less than 0.5 ppmv or be Consult Appendix H for reporting format and parameters. sensitive enough to allow for a modeled ambient air concentration(at least one microgram per cubic meter)at the soil surface. B. Holding Time:Hydrogen sulfide samples should be extracted directly into a hand-held.analyzer within 30 minutes of collection to minimize the risk of losing the hydrogen sulfide due to reaction with active surfaces. If a hand- held instrument is not used,hydrogen sulfide samples should be analyzed as below: r.r4s a. Within 30 minutes of collection,using the GC procedures;or h. Within 24 hours of collection,if a surrogate is added to the samples or ^ �' 100 percent duplicate samples are collected. C. Sample Containers:The following sample containers are recommended for hydrogen sulfide: a. Minimum one(1)liter black Teclar bag fitted with polypropylene 12110/2009 -43- 12/10/2009 -44-