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iProject No 034-98081 Page No 2 Chemical Analysis - Groundwater Groundwater samples were collected froinZ the three monitoring wells on January 28, 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 Certified Analytical Results and Chain-of-Custody Record are provided in Appendix C Benzene groundwater quality data from the current monitoring event is pi esented on Figure 2, and total petroleum hydrocarbons as gasoline groundwater quality data from the current monitoring 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 MWA ' DISCUSSION AND RECOMMENDATIONS Water level data shows that groundwater elevation has increased approximately two Feet since our first monitoiing event in October 1998 This increase likely represents normal seasonal recharge Groundwater flow direction is similar to the previous monitoring event but at a slightly smaller gradient The analytical data from Krazan's monitoring well groundwater samples mimic previous anomalous grab groundwater data Compared with the October 1998 sampling event, benzene concentrations this quarter fell to non-detected levels in monitoring wells MW-2 and MW-3, but increased in well MW-1 During both events, 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 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 monitoring well groundwater samples is quite distinct from that expected or commonly observed for a gasoline source These findings continue to suggest an off-site source for benzene groundwater contamination KRAZAN& ASSOCIATES, INC Offices Serving the Western United States 349&0$1199