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Geological reckntcs Inc. • • Page 2 Geoprobe Investigation Project No. 425.2 September l8,2008 GTI installed five new water-table monitoring wells and one intermediate depth, discretely screened, monitoring well. In mid 1998, GTI installed two additional intermediate depths, discretely screened, monitoring wells and one deep discretely screened, monitoring well. Quarterly groundwater monitoring reports have been submitted throughout the project. In late July 2001, GTI and Del Tech performed a limited soil excavation at the site and removed approximately 500 cubic yards of contaminated soil. Analytical data show that approximately 4,900 pounds of TPH-G were removed from the site. At the end of October 2001, the stockpiled soil was transported and disposed of at Forward Landfill. GTI submitted a report on the soil excavation activities on January 28, 2002. In the letter dated June 28, 2004, Nuel C. Henderson, Jr., R.G., San Joaquin County Environmental Health Department (SJC/EHD) reviewed and accepted the proposed method of in situ oxidation remedial method in the Feasibility study dated 28 April 2004, and directed GTI to prepare and submit the work plan for Bench Scale Testing. GTI prepared and submitted the Work Plan dated August 16, 2004 for Bench Scale Study to Mr. Nuel Henderson of SJC/EHD and Mr. James Barton of California Regional Water Quality Control Board — Central Valley Region (CRWQCB-CV). Mr. James Barton on a telephone conversation(September 22, 2004) with GTI discussed the issue of pre-bench scale testing to determine if we could proceed directly to the pilot testing and skip the full Bench Scale Testing. After the telephone conversation with Mr. James Barton, GTI discussed this issue with Dr. Angus McGrath of SECOR International Incorporated. Dr. Angus McGrath agreed to write the report based on his other similar studies of chemical oxidation from the groundwater and soil analysis from the anticipated target zones of chemical oxidation. Mr. James Barton directed GTI to write the Work Plan Addendum for Pre Bench Scale/Pilot Testing. GTI prepared and submitted the Plan Addendum — Pre Bench Scale/Pilot Testing dated September 22, 2004 to SJC/EHD and CRWQCB-CV. Mr. James Barton approved the work plan in the letter correspondence dated October 4, 2004 with some conditions. The purpose of this Pre Bench Scale Testing and study was to determine whether a full Bench Scale Testing is necessary prior to a Pilot Study. GTI performed bench scale testing/study in the months of December 2004 thru March 2005 according to the work plan approved in a letter correspondence dated October 4, 2005 by CRWQCB. GTI prepared and submitted the bench scale testing/study report dated March 10, 2005 to county and CRWQCB. However, Mr. James Barton (CRWQCB) in his emails dated February 23 and 24, 2005 gave the indication to skip the full scale bench scale testing. GTI interprets from these emails that CRWQCB should not have any objection if GTI moved forward to the pilot testing. GTI proceeded with ozone sparging and vapor extraction pilot testing. Monitoring during the pilot test showed that hexavalent chromium was present in the groundwater, so further use of ozone sparging was abandoned.