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f -> TreadwelMolo r -) ') S.0 SUBSURFACE INVESTIGATION Treadwell & Rollo prepared a 4 November 2004 Work Plan to advance up to five borings to collect soil and groundwater samples in the vicinity of the former UST and pump island locations (Treadwell & Rollo 1 �) 2004b). Based on the results of the initial investigation, two work plan addendums, dated 10 December " 2004 (Treadwell & Rollo 2004c) and 20 January 2005 (Treadwell & Rollo 2005a), were submitted to the Tl SJCEHD. The addendums were submitted to complete unfinished work from the initial Work Plan and to add additional borings to further delineate soil and groundwater impacts. S. 1 Sample Collection The Site Investigation program was completed in three phases of sampling events. As discussed below. _ > Prior to drilling, boring permits were obtained from the SJCEHD, and SJCEHD inspector Vicky McCartney r ) visited the Site during drilling activities. Prior to conducting the subsurface investigations, we notified Underground Services Alert and contracted with a private utility locator to clear proposed boring r _ locations for potential underground utilities. ab I _ ) On.14 November 2004 two borings SB-4 and SB-5 were advanced and shallow groundwater samples were collected from a maximum depth of 35 feet. SB-4 was advanced to a maximum depth of 60 feet bgs and SB-5 was advanced to a depth of 32 feet bgs. In addition to the soil borings, three test pits r ) (TPA, TPB, and TPC) (Figure 2) were excavated and sampled. TPA was in the location of the former I _ pump island . TPB and TPC were located at the locations of former fuel distribution lines. Samples were - \ collected at all three test pits from depths of 2.0, 6.5 and 10 feet bgs. FI J 0 On 20 and 21 December 2004 two additional borings were advanced (SB-2 and SB-3). In addition, SB-5 ! _ ) was advanced to a deeper depth than was completed in previous drilling activities (SB-5b) . SB-2, SB-3, _ ) and SB-5b were all advanced to 60 feet bgs:Groundwater samples were collected from the shallow zone in SB-3 at approximately 32 feet. Deep zone groundwater samples were collected from SB-2. SB-3, and -_ SB-5b at approximately.52, 60, and 45 feet bgs respectively. On 2, 3, and 4 February 2005 two additional borings were advanced (SB-6 and SB-7) to further delineate _? the northern and western extent of groundwater contamination in the shallow and deeper groundwater zones. SB-6 and SB••7 were advanced to approximately 81 and 76 feet bgs respectively. Groundwater r; _) 5 ('D 25971201 . DGD 6 February 2008