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j 3 0 CONCLUSIONS, RECOMMENDATIONS AND PROJECT STATUS Between September 21 p , and December 20, 2005, the groundwater surface dropped an average ' of 0 63 feet, the groundwater gradient decreased from 0 0024 to 0 0019 foot/foot, and the direction of groundwater flow remained toward the east-southeast The groundwater surface configuration appears to be consistent with historical and seasonal trends Between September 21, and December 20, 2005, the concentrations of gasoline compounds in ' groundwater remained relatively stable, except for significant increases in the concentrations of MTBE in MW-2 from 4,670 to 30,800 micrograms per liter (pgll), and in MW-4 from 2 2 to 15 0 fag1l Gasoline hydrocarbons are concentrated as free product near former UST#3, and concentrations of gasoline compounds decrease with distance from the source area As shown on the isoconcentration maps, the lateral extent of TPH-as-gasoline and benzene are defined (Figures 5 and 6), and the lateral extent of MTBE in groundwater is mostly defined (Figure 7) MTBE appears to be preferentially migrating away from the former UST source area in the downgradient direction The vertical extent of impacted groundwater has not been investigated 1 During the fourth quarter of 2005, approximately 1 50 ounces of free product were removed from MW-1 in three monthly site visits On November 1, 2005, EHD met with representatives of the San Joaquin County Facilities Management Department In a letter summarizing the meeting dated November 17, 2005, EHD states that Cross sections should be prepared by your consultant to identify potential or likely contaminant migration pathways EDB should be added to the suite of analytes being tested for in the groundwater samples A generalized stratigraphic cross-section is included as Figure 8 The cross-section shows that a sandy silt soil exists at approximately 50 feet bgs Since this sandy soil interval coincides with the groundwater table, it may represent a contamination migration pathway in the downgradient direction EDB was added to the groundwater analytical program, beginning this quarter Ramage Environmental recommends that upon the availability of funding, the previously-approved remedial feasibility testing and vertical investigation tasks be completed In the meantime, monthly free product removal and quarterly groundwater monitoring should continue r •