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• GEOMATRIX TPHg are100 micrograms per liter(pg/l-)and 5 pg/L,respectively,and are based on taste and odor thresholds for dnnkmg water(Table 4) With the exception of the June 2004 groundwater sampling event and the initial sampling of well MW-1,groundwater samples collected from monitoring wells located dust outside of the area of petroleum affected soil(MW-1,MW-5, and MW-6) are not reported by the laboratory to have ' contained concentrations of petroleum hydrocarbon constituents above analytical reporting limits Upgradient monitoring well MW-1 was sampled a total of 15 times between the period of August ' 1998 to June 2002 Groundwater samples collected from this well are not reported to have shown any detections of TPHd,TPHg,or BTEX with the exception that TPHd was reported as detected at a ' concentration of 66 gg/L in the samples collected in August 1998 Similarly,groundwater samples collected from downgradient wells MW-5 and MW-6 between June 2000 and June 2002 (nine ' sampling events)were not reported to have shown detections of TPHd,TPHg,or BTEX Laboratory results from June 2004 do report the detections of TPHd in groundwater samples from monitoring wells MW-1,MW-5,and MW-6(at concentrations of 59,250,and 170 gg/l r ectrvely)Towever, ' groundwater samples from these wells collected in August 2004 were reported not to contain detectable concentrations of TPHd,TPHg, or BTEX Based on the historical results,the June 2004 results are considered anomalous(See Table 3)-- Deeper monitoring well MW-7 was sampled for the first time in June 2004 and results indicated the presence of TPHd(520 pg/L)and toluene(0 63 gg/L) However,the August 2004 analytical results indicated no detectable TPHd,TPHg, or BTEX Therefore the June 2004 results for MW-7 are also ' considered anomalous The vertical extent of TPH in groundwater at the site is therefore considered constrained by both the results of groundwater samples collected from MW-7 and by reported ' analytical results from grab groundwater samples collected at depths of up to approximately 50 feet bgs in boring SB 12 (Tables 2 and 3) 1 2.3 PRODUCT REMOVAL Free phase petroleum has been sporadically observed in monitoring well MW-2, located within the backfill of the former tank excavation Free product was removed from MW-2 on August 30,2004 using a bailer until no product remained in the well A total of 0 1 liter of product was removed iFollowing product removal,a"petro trap"was installed in MW-2 to passively collect free product The"petro trap"was checked on September 14,2004 and a total of approximately 0 1 liter of product had accumulated and was removed The"petro trap"is currently installed in MW-2 and will continue to be checked on a monthly basis } ' I Toc_Safe19000s199631CAPNCAP txt doe 4