ARCHIVED REPORTS_XR0008736 - Laserfiche WebLink

Home Browse Search

' On January 9, 2003, ATC personnel conducted a 500-foot physical reconnaissance to identify any undocumented wells and confirm that no surface water bodies are present in the immediate vicinity of the • site No undocumented surface water bodies or groundwater wells were observed during this phase of the ' survey As noted above, several wells associated with the ongoing site assessment and remediation that exists on the subject property are listed in the DWR search 60 FINDINGS AND RECOMMENDATIONS ' Based on historical research, field observations, Iaboratory analytical results and groundwater gradient and flow direction calculations, it is ATC's opinion that the extent of hydrocarbon and/or fuel oxygenate- impacted soil has been defined to an acceptable level in the northern, southern, eastern, and western directions at the site Based on the data collected during the most recent groundwater monitoring event which was conducted ' on January 16, 2003, the hydraulic gradient was calculated and flow direction determined A hydraulic gradient of approximately 0 001 vertical feet to horizontal foot (ft/ft) trending towards the northwest was calculated TPHg concentrations were reported above their respective laboratory detection limits in ten of the twenty-one wells (MW-1 through MW-17, VW-1 through VW-3 and EX-1) The highest TPHg concentration was reported in VW-1 at a concentration of 28,000 micrograms per liter (pg/L) Newly , ' installed groundwater monitor wells MW-13, MW-14 and EX-1 had reported TPHg concentrations of 190, 320, and 11,000, respectively Benzene was reported in eight of the wells sampled Reported liebenzene concentrations ranged from below the laboratory detection limits of 0 5 µg/L to the highest concentration of 8,800 µg/L, detected in VW-1 Groundwater extraction well EX-1 had a reported benzene concentration of 3,100 pg/L Toluene was reported in six of the wells sampled The highest ' toluene concentration was reported in VW-1 at a concentration of 850 pg/L Newly installed well EX-1 had a reported toluene concentration of 740 µg/L Total Xylene constituents were reported in eight of the 1 wells sampled Total Xylenes were reported above laboratory detection limits of 0 5 µg/L to the highest concentration of 2,200 gg/L in VW-1 Newly installed wells MW-14, and EX-1 reported Total Xylene constituents at concentrations of 4 6, and 1,000 µg/L, respectively MTBE was detected in the newly 1 installed wells MW-13 MW-14, MW-16, and EX-1 at concentrations of 13, 10, 28, and 330, respectively Based on the Department of Water Resources database review of potential receptors within a 2,000-foot ' radius of the site, three wells not associated with the site were identified It is not know weather those wells are actively pumping The 500-foot well canvass did not reveal any undocumented production ' wells 1 EZ 100966ASAR.rpt ATC Associates Inc ' 11San Diego1PZ Serveli 009661RepartsU 00966SAR001 rpt ATC Project No 43 25827 0026 ' 13