ARCHIVED REPORTS_XR0011315 - Laserfiche WebLink

Home Browse Search

c7c0bgica,Techfi'krsI= Page 4 Groundwater Monitoring Report Project No. 989.2 November 20,2001 ' • A low concentration of MTBE i - s present m MW 6. The levels are consistent with previous monitoring events and show a slight increase since the June 2001 monitoring ' event. • MTBE is non-detect in MW-1-5. ' The Laboratory Data Sheets are included in Appendix C. The data is summarized in Table 1 of Appendix A. ' During purging of the monitoring wells, field measurements of the oxidation-reduction potential of the water were measured using an YSI meter. These measurements are ' summarized in Table 3 of Appendix A and the field logs in Appendix B. The results suggest that MW-1, 2, 3, & 4 are near the center of the plume, while MW-5 and 6 are near the margins of the reactive water. 4.0 CONCLUSIONS AND RECOMMENDATIONS ' The followingconclusions have been drawn from the data generated from this site g to investigation work: Conclusions 1. The highest levels of BTEX and TPH-gasoline are present in MW-I & 4. ' ❑ MW-I is closest to the location of the former UST ❑ MW-4 is the nearest down gradient well to the removed UST ' 2. MTBE is only present in MW-6. 3. In the last four monitoring events, MTBE has been present in the wells located parallel to the storm drain between Valley Wholesale Drug Company and Larson Marine. ' 4. Since March 1996 very low levels of MTBE have only been detected twice in wells near the location of the former UST. According to Wm. J. Hunter & Associates, the MTBE detected in MW-1 during the July 2000 monitoring event is suspect. ' Recommendations I. Further define the lateral extent of the plume: Install two monitoring wells along Oak Street; one to the north and one near the northwest corner of the Property. 2. Further define the vertical extent of the plume: Install a deep monitoring well near the former the UST. i3. Examine drainage from Larson Marine to determine if petroleum product can travel from this property, which is elevated above the Valley Wholesale Drug property, to the storm drain located along MW-4, MW-5 and MW-6 at the Valley Wholesale Drug Company site. 4. Continue quarterly monitoring to evaluate the how these new wells improve our understanding of the nature and extent of the groundwater contamination plume.