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r <br /> =-� Geological Audit Services, Inc. <br /> m-m 1803 W March Lane, Suite A• Stockton, CA 95207 • (209) 956-0264. FAX (209) 956-0700 <br /> v <br /> 15 June 1992 <br /> (GeoAudlt CV 43C4-1. 1) <br /> CS - LA <br /> Ms. Margaret Lagorio, RENS AUG 4F ' <br /> Public Health Services - San Joaquin County � 4 Igg2 <br /> Environmental Health Division ENVIpONMENTAL NEALT <br /> 009 <br /> Stockton, 2 <br /> California 95201 <br /> Sub]ect: Progress Report for Vacuum Extraction at Genova Bakery - <br /> 749 North Sierra Nevada, Stockton, California <br /> Dear Ms. Lagorio: <br /> In accordance with the request of our client, the Estate of Angelo <br /> Rolleri, we have prepared this report to update you on the progress <br /> of the mitigation project up to 10 June 1992 at the referenced <br /> address. <br /> The vacuum extraction at the referenced address has been in <br /> • operation since 15 August 1991. Between 15 February and 26 March <br /> 1992 the vacuum extraction unit was repaired. Since 27 March 1992 <br /> • the unit has been in operation for practically 24 hours/day, <br /> extracting an average of 65 cubic feet per minute (cfm) of vapor <br /> from the well. to After initial adjustment and scheduled <br /> maintenance, the vacuum extraction system has been operating <br /> practically 24-hours/day, extracting an average of 60 cubic feet <br /> per minute (cfm) of vapor from the well. During the first 96 hours <br /> the unit was operated by the recovered vapor only. After that <br /> period, supplemental fuel (natural gas) has been added as needed. <br /> As of 10 June 1992 , the vacuum extraction unit is in operation for <br /> approximately 5, 205 hours. <br /> Organic vapor (OV) concentrations are measured on weekly basis at <br /> the inlet, pre-catalyzer outlet and post-catalyzes with a photo- <br /> ionization detector (PID: Thermo Environmental 580A, 10. 0 eV lamp <br /> energy, calibrated to isobutylene) . The recovered OV concentrations <br /> from the well prior to combustion (y-axis) are plotted versus time <br /> (x-axis) on Figure 1. During organic vapor readings, fluctuations <br /> were noted in the concentration of hydrocarbon vapors. For <br /> recording purposes, however, the highest levels were consistently <br /> recorded. <br /> A destruction rate of greater than 90% has been achieved throughout <br /> the entire operational period. Organic vapor records demonstrated <br /> • an initial increase followed by an overall decline. Currently, the <br /> average OV readings in the last 7 monitoring periods is less than <br /> 1, 000 ppm as isobutylene, representing approximately 40% of the <br /> (average) highest readings of 2, 200 ppm. These data indicate an on- <br /> going venting progress. <br /> Environmental Services • Hydrogeology•Geotechnical Services <br />