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� Mr.Scott Rickman Environmental 13 June 2007 Resources Page 2 Management �1 3�d ACTIVITIES COMPLETED Prior to performing field activities, ERM obtained a drilling permit from the San Joaquin County Environmental Health Department. On 20 February 2007, ERM marked the proposed drilling locations. ERM contacted Underground Service Alert on 21 February 2007 to notify them of ther' d filling activities. In addition, ERM contracted Foresite, ap rivate utility locating service, to sweep the proposed drilling locations for underground utilities prior to drilling. Utility clearance activities were ,performed on 26 February 2007. t. Gregg Drilling and Testing, a licensed C-57 drilling company,was contracted to install the six borings. The drilling activities were performed on 27 February 2007. Two of the borings (SB-1 and SB-2) were installed at the presumed downgradient extent of the site. Borings SB-3 and SB-4 were installed inside the warehouse building within the reported footprint of the former wastewater pond. The two remaining borings (SB-5 and SB-6) were installed at the presumed upgradient extent of the property. The boring locations are presented on Figure 2. r All boring locations were cleared to 5 feet below ground surface (bgs) Ja using a hand auger prior to drilling to further eliminate the possibility of breaching underground utilities. The borings were then continuously cored to a total depth of 20 feet bgs using a direct-push sampling rig. An ERM geologist described the visual and olfactory condition of soils encountered on boring logs, which are presented in Attachment A. In addition, the soil cores were screened using an organic vapor analyzer with a photoionization detector (PID) that was calibrated with a 100 part per million isobutylene standard. The results of this field screening are also presented on the boring logs. Upon completion of soil sampling i activities, each boring was backfilled using a neat cement slurry in accordance with the San Joaquin County requirements. Soil g samples were collected from each boring atapproximate 5 foot p pp intervals. Soil samples selected for analysis were properly sealed, labeled, and preserved. A chain-of-custody form was maintained with r the collected samples. ERM submitted the soil samples to Entech L Analytical Labs, Inc. (Entech), a California-certified laboratory located in Santa Clara, California. Selected samples from each boring were analyzed on a standard turnaround basis for total petroleum {