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' Chevron Products Company • 2 <br /> Chevron Service Station#20-0797 North West Lane,Stockton CA September 19,2001 <br /> The specific scope of work is discussed below: <br /> • Groundwater Monitoring Wells. Three soil borings will be advanced at the <br /> locations shown on Figure 2 using 8-inch diameter hollow-stem augers to a <br /> depth of approximately 60 feet below ground surface (bgs). Groundwater is <br /> expected to be encountered at a depth of approximately 50 feet bgs. Upon <br /> completion of drilling, a 2-inch diameter groundwater monitoring well will be <br /> installed in the borings. The wells will be screened from approximately 5 feet <br /> above to 10 feet below first encountered groundwater. <br /> • Permitting. The applicable permits for groundwater monitoring wells will be <br /> obtained from the City of Stockton and San Joaquin County prior to drilling. <br /> • Soil Selection and Analysis. Soil samples will be collected at 5-foot intervals <br /> and will be sent under chain-of-custody procedures to a California State-certified <br /> laboratory for analysis of TPHg using modified EPA Method 8015, and benzene, <br /> toluene, ethylbenzene, xylenes (BTEX), and methyl tertiary butyl ether(MtBE) <br /> by EPA Method 8260. <br /> • Monitoring Well Development and Sampling. Following installation, the <br /> monitoring wells will be developed by rigorously surging the wells over the <br /> length of the screen interval and by purging approximately 10 casing volumes of <br /> water. After well development, groundwater samples will be collected and sent <br /> under standard chain-of-custody procedures to a California State-certified <br /> laboratory. The groundwater samples will be analyzed for TPHg using modified <br /> EPA Method 8015, BTEX, and MtBE using EPA Method 8260. <br /> • Well Surveying and Groundwater Gradient Interpretation. A state-licensed <br /> surveyor will survey the newly installed wells. Depth to groundwater <br /> measurements will be collected during sampling activities and utilized for <br /> interpretation of groundwater flow and gradient beneath the site. <br /> • CPT Borings. If the presence of petroleum hydrocarbons is confirmed at the <br /> site, based on the analytical results from the soil and groundwater samples, <br /> seven CPT borings will be advanced along the southern property boundary to <br /> further evaluate potential MtBE impact to the municipal supply well. If samples <br /> collected during the installation of the wells do not contain detectable <br /> concentrations of the chemicals analyzed, the CPT borings will not be advanced. <br /> If the CPT borings are necessary, each boring will be advanced to approximately <br /> 30 feet below the first encountered groundwater, or until rig refusal is observed, <br /> to collect soil stratigraphic data. Adjacent to each CPT borehole, a second <br /> direct-push borehole will be advanced to collect discrete soil and groundwater <br /> samples. The depths of the soil and groundwater samples will be determined in <br /> the field based on the CPT logs. <br /> 1:\Chevron\200794\Reports\200794 Muni WP 2001.doc <br />