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Herman and Helen's • - 2 - 6 March 2007 <br /> Annual Report <br /> General Comments <br /> 1. Regional Water Board staff concurred with the recommendation to cease remedial system <br /> operation and evaluate rebound conditions for two months ending 12 March 2007, based <br /> on low to non-detect chemical concentrations in the system influent. However, influent <br /> concentrations of TPHg were reported at 1,400 ug/L and 5.000 ug/L approximately one <br /> month preceding system shutdown. Varying concentrations have not been an unusual <br /> occurrence since groundwater treatment was initiated at the site. Continued operation of <br /> the treatment system is needed for groundwater remediation at the site. We concur that <br /> the system must be restarted on 12 March 2007. However, after discussing your 5 March <br /> 2007 request to extend the shutdown of the treatment system with my supervisor, Mr. <br /> James Munch, it was decided that the end of the period of non-operation will be extended <br /> from 12 March 2007 to the week of 26 March 2007 to permit evaluation of the most <br /> recently obtained monitoring data. <br /> 2. The decreasing concentration trends and non-detects (NDs) in deep wells including <br /> MW-11, MW-7, and MW-6, as well as the history of NDs in down gradient wells such as <br /> MW-8 and MW-10, indicate that operation of the groundwater extraction system has been <br /> effective in eventually achieving plume capture. Previous correspondences however, <br /> indicate that system optimization, potentially including relocation of the extraction point is <br /> now necessary. Based on the consistent detections of the highest contaminant <br /> concentrations in the vicinity of MW-4, it is appropriate that relocation of the extraction <br /> point from EW-1 to MW- 4 should be contemplated. An additional factor that also warrants <br /> evaluation is the role of tidal influence on depth to groundwater and fluctuating contaminant <br /> concentrations. By 4 May 2007 please submit an Optimization Report presenting <br /> recommendations for augmenting and/or modifying the groundwater remediation and <br /> sampling at this site. <br /> 3. The system monitoring results listed in Tables 8 and 9 indicate that the unauthorized <br /> November 2006 tertiary butyl alcohol (TBA) release, as well as repeated discharges of <br /> Dissolved oxygen (DO), pH, specific conductance, and turbidity outside the discharge limits <br /> constitute violations of NPDES No. CAG915001 and therefore may be subject to <br /> mandatory minimum penalties (MMPs). These discharges are presently being evaluated by <br /> Regional Board staff to determine whether penalties will be assessed. You will be notified <br /> accordingly. <br /> If you have any questions regarding this letter, you may contact me at (916) 464-4811 or at <br /> betaylor@waterboards.ca.gov. <br /> Brian E. Taylor, R.G. <br /> Engineering Geologist <br /> cc: Ms. Margaret Lagorio, San Joaquin Environmental Health Department, Stockton <br /> Mr. Arthur Deicke, Advanced GeoEnvironmental, Inc., Stockton <br />