ARCHIVED REPORTS_XR0003141 - Laserfiche WebLink

Home Browse Search

Project No 034-98081 Page No 2 Cheirxical Analysis-Groundwater Groundwater samples were collected from the three monitoring wells on September 2, 1999 The groundwater samples were chemically analyzed for benzene, toluene, ethylbenzene, and xylenes (BTEX), methyl tertiary butyl ether (MTBE), and for total petroleum hydrocarbons as gasoline (TPH-G) by EPA Methods 8021B and 8015 Analytical results are presented in Table III (Appendix A) Copies of the analytical results and chain-of-custody record are provided in Appendix B Benzenew data from the current monitoring event is resented on Figure 2 and total groundwater quality g p gm' , petroleum hydrocarbons as gasoline groundwater quality data from the current monitonng event is presented on Figure 3 Based on the data distribution from this quarter's and previous groundwater sampling, groundwater plume contour maps have been drawn Review of the maps shows that plume definition has been accomplished in all directions except to the northwest of monitoring well MW-1 ' DISCUSSION AND RECOMMENDATIONS Water level data shows that groundwater elevation has decreased approximately four feet since the Previous quarterly monitoring event in May 1999 This decrease likely represents normal seasonal fluctuations Groundwater flow direction and gradient is similar to the previous monitoring event 1 The analytical data from Krazan's monitoring well groundwater samples mimic previous anomalous grab ' groundwater data Data from the events, show the benzene concentration in MW-1 is greater than anticipated relative to the concentrations of toluene, ethylbenzene, and xlyenes Refer to section 6 2 of ' Krazan's August 28, 1998 report for Phase I of the current investigation for an extensive discussion of the anomalous groundwater quality data As with the groundwater sample analytical results from Phase I and Phase II of our subsurface ' investigation, the exaggerated ratio of benzene compared to toluene, ethylbenzene and xylenes from monitonng well groundwater samples is quite distinct from that expected or commonly observed for a gasoline source These findings may suggest an off-site source for benzene groundwater contamination KRAZAN&ASSOCIATES,INC Offices Serving the Western United States 3498081 399