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' established by the National Institute for Occupational safety and liealth (NIOSH) <br /> concerning the action levels to be utilized when working in a potentially explosive <br /> environment. <br /> NIOSH guidelines on the use of the combustible gas indicator: <br /> 1. 10 percent LEL - limit all activities in area to those that do not generate <br /> sparks. <br /> 2. 20 percent LEL- limit all activities in area. <br /> When readings exceed 20 percent LEL on the indicator all activities must cease <br /> to allow time for the combustible gases to vent. <br /> 3.4.2 Displacement of Combustible Gases <br /> If the explosive/combustible concentrations of gases in the well/borehole are not <br /> diminished after allowing adequate time to vent, then the following steps should be <br /> taken: <br /> 1. Obtain an air compressor (minimum 1.5 horsepower). <br /> ' AY BESOURCE OF <br /> 2. WARNING: AN Alli COMPRESSOR rMa sae diissta ce from t e <br /> IGNITION; therefore, place p <br /> well/borehole(at least 20 feet). <br /> 3. Place hose into the well/borehole until it reaches bottom. <br /> 4. Start air compressor and"run"it for 15 minutes. <br /> 5. Measure the percent LEL in the well/borehole. If explosive reading <br /> continues above 20010 LEL repeat step 3. If level of combustible gases/vapor <br /> in the well are below 20015 LEL proceed with Step 6. <br /> indicator; if <br /> 6. Monitor well/borehole for five mt` continue° combustible <br /> omwitust fling s split spoon <br /> readings remain below 20% LE <br /> sampling activities. <br /> 7. Continue monitoring explosive gas concentrations in borehole. <br /> 3.4.3 Oxygen Monitoring <br /> -contained breathing apparatus when oxygen <br /> NIOSH requires the use of self <br /> = concentrations fall below 19.5%. This conwould be very unlikely since there <br /> condition <br /> he <br /> confined work <br /> should be no activities performed mshould be used to monitor Ithe atmospheric 02 <br /> Oz <br /> situation change, an oxygen indicator <br /> concentration during initial site entry and drilling activities. in normal <br /> Note: The combustible gas indicator is intended for use only <br /> oxygen enriched or defi <br /> concentrations that are less thanicient. Oxygen <br /> ones that <br /> g atmospheres, noteater than normal ay cause er oneo s <br /> readings. <br /> must e rtified for <br /> All monitoring equipment used during <br /> these latmasphtere es consi bs of flammable <br /> operation in a Class I atmosphere. A <br /> vapors and .gases, such..as gasoline and hydrogen. The instrument's instruction <br /> 3-4 <br />