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VERTICAL AND LATERAL EXTENT is A Zone . The SB8 location should be considered the lateral and vertical extent of the TPHg, BTEX and MTBE Plume originating at R603. Degradation protected from the earlier modeling indicated that the following concentration would be expected in the A Zone at SB8- TPHg = 378 ug/L, Benzene = 35 ug/L. Sample results showed below laboratory lower detection lunits for the compounds of concern TPHg, BTEX indicating degradation of better than 99 95 % for TPHg and 99 8% for Benzene MTBE found at SB8 is not considered a part of the R603 plume Historic evidence of MTBE associated with R603 (MW2, MW10 and MW13), suggests that there is no connection with the MTBE in MW11 or MW12 MTBE was confirmed only once in MW8 (September 1997 Method 8020 = 14 ug/L confirmed present with Method 8260) but all other times has been below Method 8260 LLDL leaving a gap in trying to connect MW12 - SB8 MTBE plume to R603 Lilcewise no MTBE was detected in any wells as early as MW11 and groundwater flow directions make it impossible to connect the MTBE at MWl l to R603 B Zone The SBS B-Zone samples were below LLDL for all compounds of concern MTBE was not found in the second water zone (B-Zone) A Zone concentrations were between 18 ug/L at the 48-52 foot sample depth and 12 ug/L at the 84-88 foot sample depth. As discussed in earlier reports, MTBE found at this distance from R603 may be attributed to two other sources (Canepia's Car Wash approximately 4000 feet southwest of SB8 and Chevron approximately 8000 feet northwest of SB8) CURRENT CONDITIONS OF SITE Since the CRWQCB-CVR review dated duly 17, 2000, all product dispensing piping and the three 10,000 gallon capacity double walled UST's have been removed and documentation sampling occurred, See Update Status Report #56 and Figure S. On November 3, 2000 soil samples were obtained from native soil beneath each end of the removed USTs. Ms. Letitia Briggs of the San Joachim County Environmental Health Department (SJC-EHD) was present to observe the sampling activities Native soils beneath the USTs were sampled using the direct push continuous core method All sample results were below laboratory lower detection limits for TPHg, BTEX using EPA method 5030, modified 8015, and 8020, for Oxygenated Volatile Organics. Di- 6 R-603 May 2001