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DISCUSSION <br /> Results of this monitoring event indicate that the levels of dissolved hydrocarbons are generally consistent <br /> with levels detected in previous sampling events, with the following exceptions TPHG, benzene, <br /> ethylbenzene, and total xylenes were detected to well MW-1 at concentrations of 109 micrograms per liter <br /> (pg/L), 3 29 ug/L, 1 89 pg/L, and 0 89 pg/L, respectively MTBE was below method reporting limits in <br /> wells MW-2 and MW-5, and was detected in well MW-3 at a concentration of 18 0 ug/L The groundwater <br /> flow direction (southeast) and gradient were generally consistent with previous sampling events <br /> Groundwater elevation increased 3 21 feet in the wells from the previous sampling event (December <br /> 1999) <br /> A letter concerning oxygenate sampling of wells at this site was sent to the San Joaquin County Public <br /> Health Services (SJCPHS) along with the Tank Removal Report on May 4, 1998 The SJCPHS letter <br /> dated June 18, 1998, allowed analysis of samples from current monitoring wells using U S Environmental <br /> Protection Agency (USEPA) Method 8020 After installation of any new on-site or off-site wells, SJCPHS <br /> will require oxygenate analysis using USEPA Method 8260 <br /> ARCO will transfer this project to another consultant The new consultant will begin providing services <br /> during the second quarter 2000 <br /> ATTACHMENTS <br /> • Table 1 Groundwater Monitoring Data <br /> • Figure 1 Groundwater Analytical Summary (First Quarter 2000) <br /> • Figure 2 Groundwater Elevation Contour (First Quarter 2000) <br /> • Appendix A Sampling and Analysis Procedures <br /> • Appendix B Laboratory Analysis Reports and Cham-of-Custody Records <br />• • Appendix C Field Data Sheets <br /> CPIN1CamPk\Data\Archrve\Arco105481Qtrly10548Q100 DQC-98\11 1 IT Corporation <br /> 05/05/00 <br />