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' Chevron Products Company Page 2 [;hevron Service Station 9 0557 139 South Center Street Stockton California Se tember 18 2002 lie mile west of the site. The Highway 4 overpass is located south of the site across Washington Street. A summary of activities previously performed at the site was presented in the CAP Work Plan. SITE ASSESSMENT ACTIVITIES AND FINDINGS On September 11 and 12, 2001, a SECOR representative supervised V & W Drilling (V & W) of Rancho Cordova, California, as they advanced four soil borings (MW-9S, MW-10, MW-11, and MW-12) to approximately 32 feet below ground surface (bgs) using 8-inch hollow stem augers and one soil boring (MW-9A) to approximately 57 feet bgs using 10-inch hollow stern augers at the locations shown on Figure 2. Soil samples were collected for logging purposes only. Upon completion of drilling, 2-inch diameter groundwater monitoring wells were installed in each of the shallow borings and a 4-inch diameter groundwater monitoring well was installed in the deep boring. On February 19 and 20, 2002, a SECOR representative supervised Gregg Drilling (Gregg) of Martinez, California as they advanced four soil borings (OS-1S/1D, OS-2S/2D, OS-3S/3D, and OS-4S/4D) to approximately 45 feet bgs using 8-inch hollow stem augers at the locations shown on Figure 2. Soil samples were collected for logging purposes only. Upon completion of drilling, two ozone spargepoints were installed in each of the boreholes (for a total of eight [8] spargepoints). The spargepoints were completed to approximate depths of 30 and 45 feet bgs, respectively, in each borehole. On June 18, 2002, a SECOR representative supervised Cascade Drilling Incorporated (Cascade) of Rancho Cordova, California, as they advanced one offsite soil boring (MW-13) to approximately 33.5 feet bgs using 8-inch hollow stem augers at the location shown on Figure 2. Soil samples were collected for logging purposes only. Upon completion of drilling, a 2-inch diameter groundwater monitoring well was installed in the boring. A summary of all field and laboratory procedures followed for these activities are included in Attachment A. The results of the well installation activities are described below: ' • Subsurface Conditions. A mixture of silty clay to clayey silt with intermittent narrow sand layers was encountered in all of the borin��rr tg thei respective total depths. Groundwater was first encountered at approximatelN to 3 feet bgs in each borehole. ' Boring logs with well construction details are included in Attachment B. • Well Surveying. A state-licensed surveyor surveyed the newly installed wells to known vertical and horizontal datum. • Monitoring Well Development and Sampling. The monitoring wells were developed by Gettler-Ryan Incorporated (G-R) af44rupon completion of well installation activities. Groundwater samples have been collected by G-R from each of the new groundwater monitoring wells on a quarterly basis since its respective installation date. Results of ' quarterly monitoring and sampling of these wells have been presented in G-R's • groundwater monitoring and sampling reports for each respective quarterly event. I:\Chevron\90557\REPORTS\CAPtCAP Progress Reports\Well Install&OS Progress.doc