ARCHIVED REPORTS XR0010903 - Laserfiche WebLink

Home Browse Search

-------------------------- Groundwater monitoring was conducted for the first quarter of 1996 on January 16; the Project Status Report for that activity was issued on February 7, 1996. Groundwater monitoring was r. ; conducted for the second quarter of 1996 on March 18. In an additional analysis, MTBE was not detected in the sample collected from MW-1. The Project Status Report for that activity, the last issued by W W.Irwin,Inc.,was issued on April 4, 1996. i. Horizon Environmental replaced W.W. Irwin, Inc. as the consultant-of-record in June 1996. Horizon conducted groundwater monitoring activities for the third quarter of the year on July 11; i the Project Status Report was issued for the activity on July 23, 1996. GROUNDWATER MONITORING: OCTOBER 29, 1996 r• Soundingand Sampling P g Monitoring wells MW-4, MW-5, MW-6, MW-7, and MW-8 were sounded on October 29, 1996 utilizing a SolinstTm, electronic, hand-held, water-level indicator. Groundwater was sounded at an average depth of 15.14 feet below the tops of the well casings (see Table 1). The average depth- to-water in the wells has risen 0.63-foot since July 11, when it was 15.77 feet. Table 2 lists clock _.r times of soundings for monitoring activities performed since September 19, 1994, with Stockton- convected times and heights of highest& lowest tides. Horizon Field Methods and Procedures are included as Appendix A. Monitoring Well Data Logs are included as Appendix B. The local groundwater flow direction on October 29, 1996 was approximately due east along a gradient of 0.012. Between July 11 and October 29, the flow direction has remained unchanged ` (see Figure 3). Analytical Results { The sample collected from monitoring well MW-6 revealed 1210 micrograms per liter (µg11) of TPH g and 87µg11 of benzene. TPH-g has increased 26% since the monitoring activity of July 11, r + but benzene concentrations have declined 20.9% since that date. Only benzene exceeds the MCL of 1µg11 assigned by the California Department of Health Services. TPH g and BTEX were not <_ detected in the sample collected from monitoring well Nff only 0.5 µg11 of total xylenes were r~_ detected in the sample collected from MW-8. C> ' The analytical results are compiled in Table 3. The Sherwood Labs analytical report and chain-of- custody hain-ofcustody are included as Appendix C. i 2005-41.496 4 HORIZON ENVIRONMENTAL INC.