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Work Plan for Destruction of Soil Vapor Extraction and Sparge Wells Former Ranch Market,Riverbank CA Page 3 fence line on the adjacent residence to the north. Mr. Christensen indicated that USTs were removed when the bridge was replaced in 1966-1967,and that additional USTs were installed to the south(closer to Jacob Myers Park)at about that time. Mr. Christensen indicated that the second set of USTs were later removed, but had no specific time-frame for the removal of the second set of USTs. EHD has no record of any USTs at the property, although records for that era are sparse. Based upon the anecdotal evidence presented above,Condor and Mr. Obaid maintain that ample evidence confirms the past existence of the downgradient USTs and further investigation in that area is not the responsibility of Mr. Obaid. GEOCON Consultants, Inc. (GEOCON) previously reported that the property that houses well MW-7 historically operated as a gasoline station and may be the source of downgradient groundwater impact (Groundwater Monitoring Report, Third Quarter 2008, GEOCON, January 9, 2009). GEOCON submitted a work plan dated August 23, 2007 to conduct additional investigation from the former Site USTs to approximately 300 feet downgradient (just past well MW-7) using membrane interface probe (MIP) technology. It is my understanding that GEOCON conducted the field work in August 2008 but never submitted the resultant report. 5.0 AVAILABLE LOGS OF DOMESTIC WELLS Condor conducted file reviews in an effort to identify and include well construction details of nearby domestic wells DW-I R,DW-2R,DW-3,and DW-4.Condor contacted the California Department of Water Resources(DWR)and reviewing available well records from EHD's publicly available records. Well destruction permits were found for wells DW-I and DW-2, and installation permits for DW-1R and DW-2R(Appendix D). However, no specific logs were found for wells DW-3 or DW-4. 6.0 WELL DESTRUCTION WORK PLAN Condor will oversee the destruction of the Site's air sparge test well(AS-1),ten vapor extraction wells(V- 1 through V-10), and twenty air sparge wells (S-1 through S-20) that are no longer in use since active remediation ended in 2008. The locations of remediation wells are shown in Figure 5 (Appendix A). Well destructions will be completed by V&W Drilling (C57-720904), under the direct supervision of Condor, pursuant to state and local guidelines. Copies of well construction logs are included in Appendix E. Condor and V&W Drilling will destroy the wells pursuant to California Well Standards Bulletins 74-81 and 74-90 published by the California Department of Water Resources. 6.1 SITE PREPARATION The proposed monitoring well locations will be marked with white paint and Underground Service Alert (USA)will be notified so that utilities can be located and marked at least 48 hours prior to drilling. Condor will prepare all permit applications for submittal to EHD for the destruction of the wells.Condor will receive all permit applications prior to initiating any fieldwork. 6.2 FIELDWORK PREPARATION Prior to commencement of fieldwork, a tailgate safety meeting will be held, and a site-specific Health and Safety Plan will be reviewed and signed by all field personnel. Well destruction activities will be performed under the supervision of a Condor geologist in accordance with the provisions of the EHD permits. Is �i� CONDOR