ARCHIVED REPORTS XR0007000 - Laserfiche WebLink

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KI 110Rl -Ad:f,rranal Sail..d tin m-v:.L 31.r,„,St:nn.o bu:,lrrn CA LL)nstI"'OnIs and the other gasoline add it ix,csloxygenates were not present at or above the laboratory reported detection limits. IGroundwater elevation meaSUrcments collected at the site oil September 1$, 1997, indicated that the :sverage depth to grulsndwater %vas approxssmatul\ 6 feet bgs. Groundwater elevation contours ' indicate i N erg ,tcep groundx\ater gradient generally towards the southeast. The groundwater elevation data indicates that the direction of groundwater flow from the former location of the USTs is towards ' monitor well MW but should be greatly influenced by the Empire Tract drainage channel to the south, The channel is ob\inusl)' a groundwater discharge point because of the aggressive pumping ' from the channel up into the Little Connection Slough. It is very likely that the agricultural drainage ditch on the east of the site that runs into the Empire Tract drainage channcl and the Empire Tract ' drainage channel have hydraulic control at the site. Figure 10. Appendix A. shows the location of a geological cross-section through borings HP-2 and 1111-3 (installed in the previous phase of subsurface investigation) and through monitor wells MW- 1, M\V-2. and MW-4. The cross-section (Figure 11, Appendix A) sft()\)s much of the site geoing}' and contaminant distribution data from the present and previous phase of investigation. The data presented from the current and past investigation at the site indicate that the lateral extent of gasoline ' contamination (including 1.3TEX and MTBE) in the vadose zone and in groundwater has been adequately investivated to the north, south, and west of the site. Additional investigation of gasoline ' constituents in site soil and groundwater, particularly MTBE, may be necessary to the east of monitor well MW-2. The groundwater data presented in this report Indicates that gasoline constituents, ' particularly RiTBE, may have impacted the agricultural drainage ditch to the cast of the site and therefore, potentially the Empire Tract drainage channcl and the Little Connection Slough. I The R(7)r0•1 - .Sail awl Gruundii-ater Investigation, dated September 30, 1996, by Condor, ' recommended that the site be evaluated in accordance with the Standard Guide for Rist: Based Corrective Action (RBCA) ASTM E1739-95 to determine if the site warrants closure or active ' remediation. based on the potential threat to human health. The report also recommended that the adjacent agricultural property and the Little Connection Slough should be assessed for potential impact. The results or the monitor well installation and minpling described in this report substantiate 4M A�� ' `J CONDOR