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three orders of magnitude from a high of 24,000 in MW-2. TBA in MW-2 has been below detection levels for the last four quarters. TAME in MW-2 has been below detection levels for the last five' quarters. Well MW-1R is slightly down-gradient from the USTs; t't shows a steady decrease in concentration of MtBE since a peak in May of 2003 and is now nearly at the detection level. TPH-g in MW-4 has hovered at or below the detection limit (50 pgl�,) for the last three quarters;this quarter the concentration of TPH-g in this well is 60 pg/L,_All other analytes except for toluene have been below detection limits for more than a year. Toluene is only present at the site in MW4. Cumulative analytical results of groundwater samples collected from current and past sampling events are presented in Tables 1 and 2. Well construction details and status of screened intervals relative to current groundwater elevation are provided in Table 3. The two shallow zone wells are the only ones sampling the top of the water column;all other wells have submerged screens. 5.0 CONCLUSIONS AND RECOMAMNDATIONS During this sampling episode, ATG employed low flow sampling techniques. In general TPH-G, BTEX and fuel oxygenates have decreased this quarter compared to last quarter. The only increase in concentration noted this quarter is in MW-4 with a TPH-g concentration of 60 gg/L, compared to 56 pg/L last quarter. Based on the findings derived from the groundwater monitoring and sampling event conducted in November 2005, ATC recommends continued quarterly monitoring of the remaining wells. ATC will continue to use the low flow purge method. The performance bond required by the City of Stockton has been renewed for another year. Quarterly GW Monitoring Report-4th Qtr 2005 Oulk Stop No.132 V TC Quik Stop Markets,Inc. ATC Project No.75.62503.3206 December 16,2005 Page 3 of 4