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CvvATC A S S O C I A T E S I N C . ATC has conducted groundwater monitoring at the site beginning in June 1999 and continuing through March 2003. Laboratory analytical data indicates that TPHg and BTEX have been consistently detected at low levels in well MW-1; that 1,2-DCA has been detected in wells MW- 1, MW-2, and MW-3 during the fourth quarter 2001 sampling event; and that 1,2-DCA was detected in wells MW-1 and MW-3 during the first quarter 2003 sampling event. The San Joaquin County EHD issued a letter to Ms. Lolly Bozzano on September 11, 2003. The letter included a summary of the EHD review of the "First Quarter 2003 Groundwater Monitoring Report" dated June 26, 2003, prepared by ATC. The EHD concluded that due to the continuing presence of TPHg, and BTEX in groundwater samples collected from monitoring well MW-1 and the presence of 1,2-dichloroethane (1,2-DCA) in groundwater samples collected from wells MW-1 and MW-3, further investigation of the site is warranted. Additionally, the EHD reviewed a Closure Report for the site prepared in 2001 by ATC and discussed the contents with the CVRWQCB. The CVRWQCB felt that the mass of contamination remaining in the soil was higher than the mass calculated in the report and that the feasibility of vapor extraction should be evaluated to remediate the contamination remaining in the soil that could continue to be a source of contaminant impact to groundwater. Based on their review, the EHD requested a work plan to investigate the lateral and vertical extent of the contamination at the site and to evaluate remedial alternatives for cleanup of the site. SCOPE OF WORK Planning and Permits ATC has prepared the drilling permit applications for the proposed subsurface investigation. The permits and associated fees are attached. ATC will also schedule field personnel and equipment, notify Underground Service Alert to locate underground utilities as required, and perform other necessary field preparation and job start-up activities. Installation of Soil Borines One soil boring will be advanced employing electronic Cone Penetrometer Test (CPT) methods at the location shown on Figure 2. The boring will be advanced to approximately 120 feet in order to take readings and identify the two suspected major water bearing zones. The boring will be used with prior data to further evaluate the vertical extent of impacted groundwater and subsurface soil lithology. A total of three soil and two groundwater samples from the CPT boring will be collected for laboratory analysis. A cone mounted with sensors at the tip will be advanced into the soil using direct push rods. The sensors will test the response of the soil to the force of the penetrating cone and this will allow the subsurface stratigraphy to be characterized. The boring will be advanced until a significant clay layer is encountered that appears to separate the shallow water bearing zone from the deeper wA 14885\reportslwkpin.doc 3