SITE INFORMATION AND CORRESPONDENCE

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' — %.Ole NMW i Page 2,3780 Rinne Road The overexcavation began.on February 23, 2005 and continued for three days. SJCIEHD was on. site at various times during each day of excavation. Initially clean overburden soil was removed from across the entire proposed.excavation area and stockpiled on site. At approximately 6-7 feet bsg there was a sudden color change to the soil as petroleum hydrocarbon contamination became apparent. The soil color became grey to black; there was prominent hydrocarbon odor. Removal of the contaminated soil.began on February 24, 2005. SJC/EHD observed that from this point on only impacted soil was removed from the excavation area. Approximately 400 cubic yards of contaminated soil were removed, though it was obvious that the layer of contamination extended laterally on all sidewalls of the excavation pit. Continued removal of contaminated soil was.not done because.of the restrictions placed.on the remediation by the Cleanup Fund. The depth of the excavation was approximately 12.5 to 13 feet bsg, which is the depth at which groundwater began to seep into the excavation. It was also the depth.at which there was another color change to the soil, back to brown and without apparent contamination. The contaminated soil.stockpile was placed in a separate location from the clean soil stockpile. During the summer months groundwater at this site is first encountered at approximately 8.5 feet bsg, so the remedial.action was performed in the winter months when groundwater is lower and excavation of the contaminated soil could be performed more cost effectively as dewatering of the excavation area would not be required. The SJCIEHD approved excavation as adequate and necessary and the inspections conducted by the SJCIEHD staff confirmed that the remedial action was justified. In a letter dated September 2, 2005, the SJCIEHD informed you that after four quarters of groundwater monitoring and sampling following the remediation, an evaluation for site closure could be made. Reports on three quarters of groundwater sampling have been submitted to the SJCIEHD to date and contaminant levels are below those detected prior to the excavation activities. All of this information can be used to proceed with evaluation of the site for closure. If you have any questions or comments please call Lori Duncan at(209)468-0337. Donna Heran, REHS, Director Environmental Health Department Lori Duncan, Senior REHS Margaret Lagorio, Supervising REHS LOP/Site Mitigation Unit IV LOP/Site Mitigation Unit IV cc: James Barton, CVRWQCB Mark Owens, SWRCB-CUF Ray Kablanow, Geological.Technics