ARCHIVED REPORTS XR0011755 - Laserfiche WebLink

Home Browse Search

Evaluation of Natural Attenuation: 7500 West Eleventh Street, Tracy, CA. Page 23 monitoring program conducted at the site. As is documented in Table 2, no 1,2-DCA or EDB were detected in samples from any of the wells conducted during that period. In a meeting held on January 18, 2005 at its offices in Stockton, the SJCEHD directed that the next round of groundwater-quality sampling be expanded from the scope previously approved for the immediately preceding rounds of groundwater-quality monitoring to again include analyses for EDB and 1,2 DCA. This direction was given r even though: 1) several rounds of groundwater-quality monitoring at the site had j demonstrated that no detectable concentrations of EDB or 1,2 DCA were present, either within or beyond the plume of affected groundwater emanating from the 7500 West Eleventh Street property when the analyses were performed by laboratory methods having Method Detection Limits (MDLs) less than or equal to the maximum contaminant - levels (MCL) established by Title 22 of The California Code of Regulations (CCR); and 2) there was no reason to believe that ethanol or methanol had been components of any of 1 the fuels stored in the underground tanks on that site. In strict compliance with SJCEHD's direction, SJC again included EDB and 1,2 DCA in the suite of analytes for the groundwater samples recovered from each of the monitoring -=� wells extant on the site in early March 2005. `j The results of those analyses for 1,2-DCA and EDB on samples recovered from the groundwater quality monitoring wells in March 2005 are also documented in Table 2. As can be seen by examination of that table, none were detected. This conclusively demonstrates that neither of those two lead scavengers is present in the groundwater >rl beneath the Navarra site. 4_:{ 6.3 Absence of Alcohols in Groundwater At the meeting held on January 18, 2005 at SJCEHD offices, agency staff also directed that the March 2005 round of groundwater-quality monitoring include analyses for the alcohols ethanol and methanol. The request was made despite the fact that analyses for ethanol had been performed during several earlier monitoring rounds and none had been '? detected. Moreover, there is no evidence that the tanks that had been located at the 7500 -'' West Eleventh Street site had, at any time, contained any ethanol, methanol or any other alcohol additive. As was readily predictable, the results of the March 2005 sampling :3 round that are recorded in Table 2 again demonstrated that neither ethanol nor methanol are present in groundwater beneath the site. sic