WORK PLANS - Laserfiche WebLink

Home Browse Search

Air Monitoring Summary and Action Levels Combustible Gases Lower Explosive Limit(LEL) Reading Action < 4% LEL Site activities will continue with normal monitoring 4%—20% LEL Stop work until levels dissipate to <4% LEL > 20% LEL Potential explosion hazard. Halt all site activities, research source of release, aerate work area, suppress source. Air Monitoring Summary and Action Levels Hydrogen Sulfide Hydrogen Sulfide (H2S) Reading Action <10 ppm Site activities will continue with normal monitoring Stop work until levels dissipate to <10 ppm; use >10 ppm mechanical ventilation if possible. Consult with CHSD if unable to reduce concentrations below 10 ppm. 8.6.2 Explosive Hazard Methane is a common gas constituent that is generated during the decomposition of organics. Methane, a non-toxic compound, does not have Cal/OSHA or other exposure limits based on toxicity. However, methane is explosive under certain conditions. The Lower Explosive Limit (LEL) for methane is 5% in air, or 50,000 parts per million by volume. At high concentrations, methane can also displace oxygen and cause asphyxiation. Because methane is lighter than air, it does not tend to accumulate in low-lying areas and will rapidly mix with atmospheric air if encountered during drilling activities. Methane concentrations will be continuously monitored using a pre-calibrated gas meter while excavation takes place. 8.6.3 Air Monitoring Equipment and Calibration A PID calibrated to an appropriate calibration mixture will be used to detect organic vapors in and around the work areas. Monitoring will be conducted in and around all work areas and at the workers breathing zone before activities commence to establish a background level, then at 15-minute intervals throughout the day. All equipment will be calibrated according to the manufacturer's recommendation. A calibration log will be maintained and will include the name of the person who performed the calibration, the date and time calibrated, and the instrument reading at the time of calibration. A manual bellows pump or equivalent with colorimetric tubes for chemical specific compounds (e.g., benzene/vinyl chloride/formaldehyde) will be utilized to determine the course of action related to upgrading or downgrading the level of respiratory protection, as applicable. If air monitoring data indicate safe levels of potentially harmful constituents at consistent intervals (5-minute intervals), then monitoring can be conducted less frequently (every 30 minutes). This determination will be 5175.0001S102/HSP Site-Specific Health and Safety Plan I ROUX 130