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� v <br /> 1 <br /> ATC <br /> A S S O C I A T E S I N C <br /> r <br /> Laboratory results of the effluent vapor sample indicated a destruction efficiency during the long <br /> test of approximately 99 percent for TPHg, approximately 99 percent for benzene, approximately <br /> ' 99 percent for toluene, approximately 99 percent for ethylbenzene, and approximately 99 percent <br /> for MTBE <br /> ' 6.0 SOIL AND PURGE WATER DISPOSAL <br /> 1 On March 21, 2002, ATC personnel met with American Remedial Technologies (ART) who <br /> picked up 22 55-gallon steel drums containing soil cuttings generated from subsurface <br /> investigations performed at the site The drums were transported to the ART facility in Lynwood, <br /> ' California where the soil was treated to nondetectable levels using thermal desorption and <br /> recycled A copy of the non-hazardous waste manifest is included in Appendix J <br /> On June 21, 2002, ATC supervised the transport of 500 gallons of non-hazardous liquid waste <br /> generated during subsurface investigations and purged from the groundwater wells during recent <br /> quarterly monrtonng events American Valley Waste Oil transported the waste to the Seaport <br /> 1 Environmental disposal facility in Redwood City, California A copy of the non-hazardous waste <br /> manifest is contained in Appendix J <br /> 7.0 DISCUSSION <br /> The soil vapor extraction pilot test yielded a ROI of approximately 30 feet As shown in Section <br /> ' 5 2, approximately 2 64 pounds of TPHg and BTEX were removed during the vapor extraction <br /> pilot tests Soil vapor extraction appears to be a viable method for remediating TPHg and BTEX <br /> impacted soil at the site In ATC's experience, soil vapor extraction is also a moderately effective <br /> method for remediating TPHg, BTEX, and MTBE impacted groundwater Soil vapor extraction <br /> is ineffective in preventing off-site migration of the impacted groundwater plume but this does not <br /> 1 appear to be a concern at this time <br /> 8.0 RECOMMENDATIONS <br /> 1 ATC will prepare a Corrective Action Plan for the site If soil vapor extraction is the selected as a <br /> remedial alternative, ATC recommends enhancing soil vapor extraction with another alternative <br /> ' such as air sparging ATC will monitor wells MW1 through MW7 quarterly <br /> w%25771reporislr,fs doc 10 <br />