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David Wang, P.E. , Chief <br /> Page 4 <br /> Novpmbpr 8. 19Q0 <br /> o The limited number of ground water samples taken from the <br /> intermediate zone. <br /> o Questions concerning of the validity of past ground <br /> water samples. <br /> o The three to four year gap in sampling periods. <br /> The Department is aware of the time and expense required to <br /> collect water samples. We, therefore, propose that any water <br /> sampling program be established. The program should determine <br /> the frequency of sampling events, the range of chemicals to be <br /> sampled, and provide guidance for deleting chemicals from the <br /> sampling protocol. <br /> 4) Future RI/FS activities should consider other potential <br /> sites not listed in the reports cited by this memorandum. <br /> It has been the Department's experience that <br /> investigations are sometimes focused too quickly on known <br /> sources of contamination. Eventually, other sources are <br /> discovered and added to the RI/FS, usually causing <br /> program delays and cost overruns. <br /> 5) When well clusters are constructed, it is recommended <br /> that the deepest well be continuously logged. <br /> SPECIFIC COMMENTS <br /> 1) A synthetic (non-organic) polymer is recommended as an <br /> option for use with mud-rotary drilling. All information <br /> regarding synthetic polymers is requested for review. <br /> This material should receive the Department's approval <br /> prior to its usage. <br /> 2) Provisions for archiving cores are contained in the <br /> Department' s draft standards dated August 1990 . A copy <br /> of the provisions pertaining to cores is included as an <br /> attachment. <br /> 3) The Department is concerned that a grout mixture of 4 . 5 <br /> gallons per bag of cement may be too thick for pumping. <br /> We recommend a 7 to 10 gallon range. Additional <br /> recommendations are contained in an attachment to this <br /> memorandum. <br /> 9 <br /> Jim Pinasco <br /> Waste Management Engineer <br /> Site Mitigation Branch <br /> Attachment <br />