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Mr. Robert Doss, P.E. <br /> April 12, 1995 <br /> Page Two <br /> 2 . The DTSC and the Regional Water Quality Control Board <br /> instructed PG&E to evaluate the Long Term Monitoring Program <br /> Guidance to prepare modifications to the current groundwater <br /> monitoring program. This guidance document was distributed <br /> to PG&E at the February 28, 1995 meeting. As recommended in <br /> the guidance document, new wells, guard wells and <br /> downgradient leading edge wells should be monitored on a <br /> quarterly basis. Monitoring wells MW-4 and MW-5 serve as <br /> leading edge wells located downgradient of contaminant <br /> plumes as depicted on figures 3-8 , 3-15, and 3-16 and thus <br /> should continue to be monitored on a quarterly basis and not <br /> modified as discussed in Section 4 . <br /> 3 . Section 2 . 4 discusses relevant features near the Stockton <br /> Former MPG site including ongoing investigation of soil and <br /> groundwater conducted by the City of Stockton at the Fire <br /> Department site located across the street to the subject <br /> site. If not done yet, PG&E should obtain and evaluate data <br /> collected by the City that may be useful in providing <br /> additional information of upgradient offsite groundwater <br /> conditions, local groundwater gradients, etc. Such <br /> additional information should be evaluated and used if <br /> appropriate in characterization of the subject site. <br /> 4 . Recommendations made in the Report include further <br /> evaluation of the groundwater gradient due to <br /> inconsistencies encountered during the site investigation. <br /> Please note that until the gradient is absolutely defined, <br /> conclusions and recommendations based on an assumed gradient <br /> direction may not be appropriate and may be subject to <br /> modifications. A statement to this affect must be included <br /> in section 4 . 0 (Conclusions and Recommendations. ) <br /> Please submit the Final Revised Phase III Report within two <br /> weeks from receipt of this letter. If you have any questions, <br /> please contact me at (916) 255-3737 . <br /> in�ly, \ , <br /> Fernando Amador <br /> Hazardous Substances Engineer <br /> Site Mitigation Branch <br /> Enclosure <br /> cc: See Next Page <br /> FA.eb <br /> FA07.045/3 <br />