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Pacle 5,(,holo, iiu4E.11% 2/1- -% BTEC concentrations in GT-i and GT-2 have followed a similar }path The results are illustrated in Table 2, and the complete laboratory report is contained in Appendix B 6.0 CONCLUSIONS AND RECOMMENDATIONS Published maps of historical groundwater elevations indicate that the predominant groundwater flow direction on the area v, to the south Although the t1our monitoring events that have been performed at the project site have not provided conclusive data on the direction of flow, three of the four event% suggest that 1) GT-1 is the most upgradient well, 2) GT-2 is the mo%t downgradient well, and -3)) flow is generally to the south More definitive mapping of the groundwater gradient and flow direction cannot be accomplished without additional monitoring points The depth to groundwater has decreased by over 3 feet in recent months, and groundwater is now at or slightiy above the screened interval in all three wells A further rise in water level could re,,ult in an apparent decrease in groundwater contamination, as contaminants are carried above the screened interval We therelore do not recommend additional monitoring until Sprint;, when a drop in the piezometric Surface i5 likely to occur The presence of petroleurn hydrocarbons in the three monitoring wells is consistent with the lirnited gradient inibrination, providing further indication that all three wells are downgradient from the UST facility However, the tact that hydrocarbon concentrations in MW-1 are lower than in the other wells is sornewhat surprising, because it is the nearest well to the fornie:r US] facility I his may indicate that groundwater flow has cau,..ed the migration of the; contarnination plunge beyond MW-1 Central Valley Regional Water Quality Control Board policy normally requires that the extent of groundwater contamination be determined before considering requests for site closure lvh , policy further requires that contamination be monitored for several quarters to demonstrate that the; contamination is not migrating to other sites Compliance with these: poltetes will likely require the installation of additional monitoring wells to the South and southwest of the existing wells One well to the north of the former USI facility, in an upgradient position, will also be necessary Upgradient therefore recommends that GTC move quickly to submit an application for additional reimbursement from the State Water Board UST Cleanup Fund, so that the site can remain in compliance with any PHS/EHD requests for further work