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' Fourth Quarter/Annual <br /> 2008 Groundwater <br /> ARCADIS Monitoring Report <br /> Chevron Bulk Fuel Terminal <br /> 100-1621 <br /> 22888 Kasson Road <br /> ' Banta, California <br /> October. Operafion of the system was verified approximately every two weeks through <br /> routine site visits.Throughout 2008 pressure readings at the compressor ranged <br /> between 6 and 15 psi, pressure readings at the wellheads ranged between 0 and 13 <br /> psi and flow readings at the well heads ranged between 0.0 and 1.9 cfm. <br /> ' The biotransformation of MTBE to TBA in monitoring well MW-50A is a strong indicator <br /> of the positive effects of the groundwater oxygenation system. Since the groundwater <br /> system became operational on April 19,2004 a declining trend of MTBE has been <br /> observed.The TBA/MTBE ratio of groundwater samples collected from MW-50A <br /> during the first, second,third, and fourth quarter of 2008 were as follows:20, 100,4 <br /> ' and 30,respectively. <br /> Recommendations <br /> I • Continued operation of the groundwater oxygenation system in accordance with <br /> the CAO <br /> • All newly installed monitoring well clusters(MW-70 through MW-76, MW-79 and <br /> MW-80)will be sampled on a quarterly basis during 2009 <br /> • Installation of monitoring well clusters MW-76 and MW-77 in accordance with the <br /> approved workplan <br /> • Monitoring wells MW-24A through MW-32A will be sampled on a semi-annual <br /> basis(First and Third Quarter). Groundwater samples collected from MW-24A <br /> ' through MW-32A will be analyzed for the following constituents: <br /> o TPH-DRO by USEPA Method 8015B and TPH-GRO by USEPA <br /> 80158 modified <br /> o MTBE,TBA, and TAME by USEPA Method 8260B <br /> The next groundwater monitoring and sampling event has been scheduled for <br /> February 4,2009. <br /> 1 <br /> 17 of 17 <br />