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Atlantic Richfield Company 3 Former ARCO#4493,205 North Center Street Stockton,CA August 22,2002 performed at the site The Site-Specific Health and Safety Plan was reviewed by the field staff and contractors before beginning field operations at the site Permits Prior to beginning well Installation activities, SECOR secured two revocable permits and two encroachment permits from the City of Stockton A revocable and encroachment permit was required for each side of the North Center Street well installation locations A well installation permit was also obtained from the SJCPHS and is included with the encroachment permits in Attachment B Activities On May 6 through 9, 2002, Gregg Drilling of Martinez, California drilled and Installed three dual completion groundwater monitoring wells under the direction of SECOR staff Each of the three dual completion wells contain one well with a screen interval at approximately 40 feet bgs, and one well screened at approximately 50 feet bgs Well construction specifications are included in Table 1, and in boring logs Included in Attachment C Subsurface Conditions Soil consisted of silty sand from just below ground surface to approximately 5 feet bgs, underlain by silty to sandy clay to 13 feet bgs Silty sand to sandy gravel with minor clayey silt was encountered from 31 to 39 feet bgs Sandy silt to sandy clay was encountered from 41 to 45 feet bgs Saturated silty sand was encountered from these depths to 51 to 56 feet bgs The deeper wells were screened in this silty sand Beneath this silty sand, silty clay was encountered to the bottoms of the borings During drilling, wet soils were consistently present within the silty sand and sand layers in each of the soil borings to the total depth explored Flowing sands saturated with water made soil sampling conditions difficult As a result, soil samples were not collected below 20 feet bgs in boring MW-8, and above 25 feet bgs in borings MW-9 and MW-10 Groundwater was first encountered at approximately 17 feet bgs, and stabilized in each of the wells at 14 to 19 feet bgs Soil Sampling and Analysis The previous boring of B-1 provided soil stratigraphy in the area of boring MW-8 throughout the length of borehole to 60 feet bgs When adverse drilling conditions were encountered within the flowing sands, no samples were collected from the boring of MW-8 Selected soil samples collected from the borings for MW-9 and MW-10 were analyzed for Total Purgeable Hydrocarbons as gasoline (TPHg), benzene, toluene, ethylbenzene, I 1ARC0144931Reports\Dua1We11-Rpt doc