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Chevron Products Company Page 2 Chevron Service Station#20-81185 East Hammer Lane,Stockton,CA September 19,2001 The specific scope of work is discussed below: • Groundwater Monitoring Wells. Three soil borings will be advanced at the locations shown on Figure 2 using 8-inch diameter hollow-stem augers to a depth of approximately 60 feet bgs. Groundwater is expected to be encountered at a depth of approximately 50 feet bgs. Upon completion of drilling, a 2-inch diameter groundwater monitoring well will be installed in the borings. The wells will be screened from approximately 5 feet above to 10 feet below first encountered groundwater. • Permitting. The applicable permits for groundwater monitoring wells will be obtained from the City of Stockton and San Joaquin County prior to drilling. • Soil Selection and Analysis. ,Soil samples will be collected at 5-foot intervals and will be sent under chain-of-custody procedures to a California State-certified laboratory for analysis of TPHg using modified EPA Method 8015, and benzene, toluene, ethylbenzene, xylenes (BTEX), and methyl tertiary butyl ether(MtBE) by EPA Method 8260. • Monitoring Well Development and Sampling. Following installation, the monitoring wells will be developed by rigorously surging the wells over the length of the screen interval and by purging approximately 10 casing volumes of water. After well development, groundwater samples will be collected and sent under standard chain-of-custody procedures to a California State-certified laboratory. The groundwater samples will be analyzed for TPHg using modified EPA Method 8015, BTEX, and MtBE using EPA Method 8260. • Well Surveying and Groundwater Gradient Interpretation. A state-licensed surveyor will survey the newly installed wells. Depth to groundwater measurements will be collected during sampling activities and utilized for interpretation of groundwater flow and gradient beneath the site. • CPT Borings. If the presence of petroleum hydrocarbons is confirmed at the site, based on the analytical results from the soil and groundwater samples, eleven CPT borings will be advanced along the eastern property boundary to further evaluate potential MtBE impact to the municipal supply wells. If samples collected during the installation of the wells do not contain detectable concentrations of the chemicals analyzed, the CPT borings will not be advanced. If the CPT borings are necessary, each boring will be advanced to approximately 30 feet below the first encountered groundwater, or until rig refusal is observed, to collect soil stratigraphic data. Adjacent to each CPT borehole, a second direct-push borehole will be advanced to collect discrete soil and groundwater samples. The depths of the soil and groundwater samples will be determined in the field based on the CPT logs. 1:1Chevron12081181Reports1208118 Muni WP 200Ldoc