ARCHIVED REPORTS_XR0004886 - Laserfiche WebLink

Home Browse Search

�i T/ Quik Stop Market No 121 CCI Project No 12118-2 Page 2 approved by the California Regional Water Quality Control Board (CRWQCB) and the EPA The groundwater samples were analyzed for total petroleum hydrocarbons as gasoline (TPHg) and benzene, toluene, ethyl benzene and total xylenes (BTEX), using EPA Test Method 8015 and 8020 and MTBE using EPA Test Method 8260 Summary of Laboratory Results Groundwater samples collected from the site indicated two of the three wells (MW-1 and MW-3) to have detectable TPHg contamination The laboratory reported monitoring well MW-1 to contain TPHg at 800 micrograms per liter(ug/1)and MW-3 was reported to contain 94,000 ug/l TPHg None of the wells were reported to have detectable concentrations of BTEX compounds It should be noted the TPHg concentrations reported in MW-1 and MW-3 were flagged by the laboratory The laboratory indicated the TPHg results were within quantitation range,however,the chromatographic pattern was not typical of fuel The laboratory also reported two of the three wells to have detectable MTBE The highest . concentrations of MTBE were reported in MW-3 at 110,000 ug/l Monitoring well MW-1 was reported to have MTBE at concentrations of 1,000 ug/l The results of the groundwater analysis are summarized in Table 2 The analytical reports from Entech and chain-of-custody documents are attached in Appendix B Discussion Groundwater measurements taken in the three onsite monitoring wells on April 6, 2000 indicated the depth-to-groundwater ranged from approximately 19 94 to 20 66 feet below the top of the well casings The water table has dropped approximately 2 5 foot since the July sample round Groundwater contours in the vicinity of the three monitoring wells indicate the groundwater flow direction to be toward the south-southeast, at a relatively flat gradient of approximately 0 0008 feet per foot (Figure 3) The groundwater flow direction determined during this sample round is approximately the same flow direction reported in previous quarterly reports During sampling of the wells, a moderate petroleum odor was noted in well MW-3 No unusual odors were noted in the other two wells Groundwater samples collected during this quarterly sample round indicate two of the three wells to contain detectable concentrations of TPHg and MTBE compounds In response to elevated levels of MTBE reported in well MW-3, CCI pumped groundwater from well MW-3 using a vacuum truck The purpose was to remove as much of the MTBE concentrations . in and around the well as possible