SITE INFORMATION AND CORRESPONDENCE_2001-CURRENT

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Former Unocal#5098 • 5606 Pacific Avenue, Stockton -2- 8 February 2002 2. The shallow and deep designations used in the monitoring reports are misleading, because the Wards site does not have shallow-screened wells, and monitoring wells MW-8D and MW-24S/D are all screened deeper than the "deep" identify gr, p � MW-23S/D, f1'hydrostrati a hic units where Unocal and Wards wells are completed as Units 1, 2, 3,or p screened wells. Therefore,please A, B, C, etc., and present this classification in the Well Details table and in future cross-sections. 3. TPHg and benzene constituents in gro (highest concentrations in the coreareas dwater are similar to previous mo nitoring eve t areas). The exception to this statement is MW-9,rwhich was installed in September 2001 and sampled twice to date. easing concentrations &'adient of the core MW-9 is more than 200 feet down core area, and maximum concentrations in September 200werent of 1,070 e Wards contaminant 59.8 99/1 for benzene. Please present a discussion in the 01.2002 r groundwater contamination ie present in µ for TPHg and report to explain the 4. To aid in evaluating cleanup activities,prepare trend-analysis and Wards monitoring wells. We suggest using Unocal wells MW 11 and MW-12 and Ward wells MW-2 and MW-3 near the core of the respective y graphs for representative Unocal extensive sampling history for these analyses. Additional downgradioundwater errt wells may es that abe quested ata later date; therefore; you may want to include trend-analysis graphs of representative downgradient wells at this time. The graphs must include TPHg acrd benzene constituents on one axis, and water level elevation on the second axis. 5. Groundwater analyses conducted for the Q4-2001 Report only analyzed samples for specific constituents as listed in C&A NO. 5-00-707, and did not report all peaks identified by the EPA Method 8260B analysis. For the Q1-2002 monitoring and sampling event, and for all future monitoring and sampling events, analyze the groundwater samples for TPHg by EPA Method 8015M, and volatile organic compounds by EPA Method 8260B, and report all peaks. 6. The approval to discontinue analysis for ethanol and methanol at this time was agreed to prior to the Q3-2001 sampling;however,previous ethanol and methanol sampling results must be included in the analytical data tables. 7. As required by C&A NO. 5-00-707, the quarterly status report is to include a summary of all activities completed during the previous quarter including investigation activities, groundwater rr oa `177 29 and sampling, and remedial activities. The following information in the Q3-2001 Report or the Q4-2001 Report: was not presented a. Appropriate conclusions summarizing groundwater flow direction and constituent trends, and how these relate to the extent of groundwater contamination(increasing or decreasing). b. Appropriate recommendations for future activities at the site, such as modifications optimize remedial systems, and/or completing additional investigation activities. to