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Waste Science and Technology Corp , December 1993 (ASA/RO) The soil and <br /> groundwater data from this additional investigation are presented in Appendix C, <br /> ' Tables C-1 and C-2. <br /> ' 2.2 Feasibility Study <br /> Following the additional assessment, Black & Veatch developed a feasibility <br /> ' study to determine the best remedial action alternative for the site The feasibility <br /> study is presented in the ASA/RO and consists of the development of several <br /> ' remedial action alternatives and the evaluation of these alternatives according to <br /> implementability, technical feasibility, and cost. Alternatives included extraction and <br /> air stripping, air spargmg and vapor extraction, and in situ bioremediation An <br /> ' innovative active in situ bioremediation was selected as the preferred alternative <br /> based on the feasibility study <br /> ' 2.3 Monitoring <br /> Groundwater monitoring was implemented at the site following the first <br /> investigation in 1989 However, the monitoring was not continuous and several <br /> ' quarters were skipped. Following the additional assessment in September 1993, a <br /> quarterly groundwater monitoring program was implemented Initially, all nine <br /> monitoring wells were monitored and sampled The SJCPHS permitted the District <br /> to reduce the number of wells from which groundwater samples were collected to <br /> three (MW-1, MW-8, and MW-9) beginning with the first quarter of 1994 Water <br /> ' levels were still measured in all nine monitoring wells <br /> In June of 1995, SJCPHS approved of the following changes in the groundwater <br /> ' monitoring program <br /> • Measure dissolved oxygen in MW-1, MW-8, and MW-9 in addition to sampling <br /> for BTEX and TPH-g. <br /> ' • Reduce the number of wells monitored for water levels to seven (MW-1, MW-3, <br /> MW-4, MW-5, MW-7, MW-8, and MW-9) <br /> ' • Reduce the groundwater monitoring and sampling frequency to semi-annual in <br /> 1996 and include MW-1, MW-4, MW-5, MW-8, and MW-9 <br /> ' The District performed the first serni-annual monitoring event in March 1996. <br /> At the request of SJCPHS, methyl tertiary-butyl ether (MtBE) was included in the <br /> list of analytes. MtBE was not detected in any of the groundwater samples collected <br /> ' 96R7 East Bay Municipal Utility District <br /> 40429700fer 11 Final Closure Report <br />