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r1 g, Atlantic Richfield Company • • 4 ARCO Station #595,6100 North Highway 99 Stockton CA February 15 2002 beginning field operations at the site The Site Health and Safety Plan is included as Attachment B • Shallow Monitoring Well Installation. Two 2-inch diameter shallow groundwater monitoring wells will be installed at the locations shown on Figure 2 The wells will be installed using drill rig equipped with 8-inch diameter hollow-stem augers to a depth of approximately 70 feet below ground surface (bgs) Based on previous assessment activities at the site, groundwater is anticipated to be encountered at approximately 60 feet bgs The groundwater wells will be screened from approximately 50-70 feet bgs • Deep Monitoring Well Installation. Three 2-inch diameter deep groundwater monitoring wells will be installed at the locations shown on Figure 2 The wells will be installed using a drill rig equipped with 8-inch diameter hollow-stem augers to a depth of approximately 100 feet below ground surface (bgs) Based on previous assessment activities at the site, impacted groundwater appears to extend to a depth of 95 feet bgs The groundwater wells will be screened from approximately 95 to 100 feet bgs, ideally in a silt/sand interval Generalized cross-sections showing the lithology underlying the site are included as Figures 3 and 4 • Well Permitting and Encroachment Permits The applicable permits for • well installation will be obtained from the San Joaquin County PHS/EHD prior to drilling Additionally, prior to installing the proposed offsite wells, appropriate access agreements and/or encroachment permits from the City of Stockton will be secured • 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 Selected soil samples will be analyzed for TPHg and TPHd using modified EPA Method 8015, and benzene, toluene, ethylbenzene, xylenes, and MtBE using EPA Method 8020 A minimum of three samples from each of the bonngs (including the samples collected at the capillary fringe and the deepest sample) will be sent to the lab for the above analysis Additionally, the samples collected from the capillary fringe will also be analyzed for fuel oxygenates MtBE, DIPE, TAME, EtBE, TBA, 1,2 DCA, and EDB by EPA Method 8260 • Monitoring Well Development and Sampling. After installation, the monitoring wells will be developed by rigorously surging the well 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 and TPHd using modified EPA Method 8015, benzene, toluene, ethyl-benzene, xylenes, WPLAN595-2-15-2002