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19 April 2006 AGE-NC Project No. 99-0645 Page 2 of 3 Historically, low concentrations of dissolved petroleum hydrocarbon constituents were detected sporadically in monitoring well MW-1 before its destruction in September 2002. MTBE was detected in MW-1 R during its initial ground water monitoring in October 2003 at a concentration of 120 pg/1; TPH-g was detected in well MW-2 during its second ground water monitoring in April 2002 at a concentration of 130 µg/1. Monitoring well MW-3 has remained uncontaminated. The concentrations of petroleum hydrocarbon contaminants in wells MW-1. MW-1R, and MW-2 have declined below detection limits between the initiation of groundwater monitoring in November 2001 or October 2003 (MW-1R) and the present. The concentration of petroleum hydrocarbons in soil vapor samples extracted from well V W 1 B, installed in the area of greatest adsorbed petroleum hydrocarbon contamination,has declined below laboratory detection limits between initiation of SVE remediation in October 2004 and the present. In order to ensure that ground water monitoring wells do not provide a vertical conduit for contaminants, AGE proposes to properly destroy them in accordance with San Joaquin County Environmental Health Department (EHD) Standards For Well Construction and Destruction. PROCEDURES As required by EHD permitting, a health and safety plan will be prepared in accordance with Occupational Safety and Health Guidance 1Vlanual for Hazardous Waste Site Activities (National Institute for Occupational Safety and Health Administration, U.S. Coast Guard and U.S. Environmental Protection Agency, 1985).Prior to drilling activities,each proposed drilling location will be clearly marked and an utility clearance obtained through Underground Service Alert. Based on the EHD "Standards" the wells will be sounded for total depth and checked for integrity, any obstruction found in the well will be removed. Well boxes and caps will be removed to expose the casing. As required by the Standards, wells showing no history of contaminant impact will be destroyed by pressure grouting; impacted wells (even if currently non-detect) will be destroyed by complete over-drilling. Due to historical analytical results from well installation, groundwater monitoring, and vapor sampling activities(see the Tables in CSR),none of the seven existing on-site wells qualify as 'non- detect'. .MW-IR, MW-2, VW-lA, VW-1B, and VW-2 are all clearly impacted according to the Standards. Although contamination was not encountered in soil samples from 70 feet - 100 feet below surface grade (bsg) in pilot boring B-3, completed as MW-3, and quarterly groundwater samples have been non-detect throughout monitoring activities (the one detection in the fourth quarter 2004 event was proven erroneous), nearby VW-3 suggests that these wells are located in an area of suspected soil contamination. Low levels of MTBE were detected during the advancement Advanced CeoEnvironmental,Inc.