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Results of Subsurface Investigation Colberg Boat Works Page 2 overexcavated in 1988 In February 1993, Telic Engineering Corporation (TEC) of Stockton, Callforrua, performed a Phase I investigation of the subject site and surrounding area within a one-mile radius TEC's findings are summarized in their report titles Phase I Preliminary Hazardous Materials Site Assessment dated July 21, 1993 On December 12 and 13, 1994, Apex supervised the advancement of 11 subsurface probes to collect soil and groundwater samples at the site Soil and groundwater samples were submitted under chain-of-custody to a state-certified laboratory for analysis Results of the subsurface investigation are summarized in the report titled Phase II Site Assessment Report dated January 23, 1995 The results of the subsurface investigation indicated that areas around the former USTs contained petroleum hydrocarbons Subsequently, Colberg Boat Works was directed by the San Joaquin County Environmental Health Division (SJCEHD) to perform further investigations at the site This investigation was performed according to Apex's Workplan for Limited Subsurface Investigation and Workplan Addendum for Limited Subsurface Investigation dated May 2, 1995 and January 24, 1997, • respectively, as approved by the SJCEHD SOIL BORING AND MONITORING WELL INSTALLATION Prior to field mobilization, the Underground Service Alert was advised to conduct a utility clearance for the site As a further precaution against encountering underground utilities during drilling, the upper five feet of the soil borings were augered by hand All field work was performed according to Apex Standard Operating Procedures (SOP) provided as Appendix A On July 28 and 29, 1997, Apex supervised the drilling, soil sampling and installation of six groundwater monitoring wells at the site at the locations shown on Figure 3 Six soil borings (SB-1 through SB-6) were drilled and completed as groundwater monitoring wells (MW-1 through MW-6) The soil boring drilling and monitoring well installations were performed by Woodward Drilling Company of Rio Vista, Cahforma using a BK-81 hollow-stem auger drill rig fitted with eight-inch diameter augers All drill cuttings are temporarily stockpiled on site between layers of plastic sheeting (visqueen) pending receipt of the analytical results and proper disposal arrangements Soil samples were collected at five-foot intervals during drilling of the soil borings Soil samples were screened in the field for visual and olfactory indications of petroleum hydrocarbons Due to a malfunction of the photoiomzation detector in the field, Apex personnel was unable to screen soil samples for volatile organic vapors Based on SJCEHD's direction and field screening C 1KBPR0]--11C'SIC0L01 00111NVSTRPT WPD