ARCHIVED REPORTS_REMOVAL ACTION COMPLETION REPORT

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Draft Removal Action Completion Report Neighborhood C, Mountain House,CA Page 8 Table 1—Action Levels for Total Dust Constituent Cal/OSHA Exclusion Zone NAAQS and Fenceline Name PEL s Action Level California SAAQS b Action Level Total Dust 5 Mg/M3 5 Mg/M3 50 µ m 50 m 'Permissible Exposure Limits(Cal/OSHA Article 107,Table ACI) bNational Ambient Air Quality Standards(NAAQS)and California State Ambient Air Quality Standards(SAAQS,24- hour standard)for respirable dust.Site dust levels were measured using real time aerosol monitors. mg/m3 milligrams per cubic meter(1000µg/m), pg/m3 micrograms per cubic meter(0.001 mg/m) 3.6.2 Meteorological and Dust Monitoring Meteorological conditions varied throughout the Removal Action process. Cool mornings with thin fog warming to mild sunny mid-day conditions were typical. The Air Monitoring Officer observed that airborne precipitation in the form of fog frequently caused elevated results on the personaldataRAM dust monitors, typically before airborne dust was visible and confirmed at upwind monitors. Dust concentrations in air were measured using a real-time dust monitor, with a concentration measurement range of 0.001 to 400 milligrams per cubic meter(mg/m3)total particulate matter. Each dust monitor was calibrated at the beginning of each day using manufacturer-provided equipment.Additional specifications for the dust monitoring equipment are included in Appendix D. Air and meteorological data are included in Appendix E. During the Removal Action, dust concentrations generated by soil movement activities, were kept to a minimum by spray-applied water. When dust concentrations exceeded the Action Levels defined in the RAW, work was temporarily paused and additional water was applied to the excavation area. During excavation, meteorological conditions were monitored using a wind speed and direction recording device and supplemented by a National Weather Service affiliated weather monitoring stations in Byron and Tracy, California. The below list of internet based resources provided forecasted weather and real time wind speed, direction and relative humidity data. Meteorological data collected on-site included wind speed and wind direction. Other meteorological observations including visibility, humidity and temperature were noted in the meteorological log. • http•//www wrh noaa gov/mesowest/mwmgp php?list=l&wfo=sto&map=sto&sort=name • http•//www wunderground com/cgi-bin/findweather/getForecast?query--37.77374268,- 121.5366363 5&sp=KCAMOUNT31 On-Site meteorological monitoring was performed simultaneously with the excavation activities to ensure all necessary precautions had been taken.All meteorological data collected at the Site was documented by the Air Monitoring Officer. As stated above, if wind speeds exceeded 25 miles per hour instantaneously or there was visual evidence of wind carrying dust, then a more aggressive approach to dust control was implemented immediately. Unsafe weather conditions such as thunderstorms did not occur. In general, the upwind dust monitor concentrations were taken to be representative of background dust concentrations and were used to qualify downwind dust monitor readings (Appendix E). There were very few occasions when fenceline action levels were exceeded for total dust. Condor observed that fugitive dust causing fenceline action levels to be approached or exceeded typically occurred as a result of grading operations taking place outside the removal area not associated with dieldrin-impacted soil.