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! • <br /> aCaliformi -Regional Water Quality Control Board V.Central Valley Region <br /> Steven T. Butler,Actmg Cpair <br /> Winston H.Hickox Gray Davis <br /> Secremryfor Sacramento Main l)ffice Governor <br /> Ewironmeted Internet Address: http://www.sweb.ca.gov/- gcb5 <br /> Protection 3443 Routier Road,Suite A,Sacramento,California 95827-3003 <br /> n Q l Phone(916)255-3000•FAX(916)255-3015 <br /> 10 March 1999 <br /> Mr. Tony Martin <br /> Kleinfelder, Inc. <br /> 2825 East Myrtle Street <br /> Stockton, CA 95205 <br /> SPRECKELS MANTECA,SAN JOA QUIN COUNTY(Case No. 860) <br /> I have reviewed the Revised Proposal Evaluation Monitoring Work Plan dated 6 January 1999 for three <br /> new monitoring wells and a replacement well for MW-6 at the Spreckels site. The revised work plan <br /> was also discussed in our phone conference on 5 March 1999. The original work plan proposed to install <br /> 20 foot long well screens at the top of the water table. This approach did not consider site specific <br /> factors that could influence contaminant migration. The revised work plan includes a field sampling <br /> strategy to ensure that new wells are screened at appropriate depths in the aquifer. <br /> The sampling strategy consists of collecting soil samples for lithologic classification and water samples <br /> for chemical characterization at five foot intervals. The maximum proposed depth for the borings is 80 <br /> feet. The work plan includes a qualifier that if an aquitard, defined as clay layer of five or more feet in <br /> thickness, is encountered, then the well screen will be placed above it. <br /> Based on our phone conference, I understand that the proposed sample intervals were intended to <br /> represent the sample frequency and not necessarily the exact sample depths. Kleinfelder geologists will <br /> collect samples based on the lithology and water chemistry observed in the field. More frequent or <br /> continuous samples may be collected in the first boring or two to adequately characterize local <br /> stratigraphy and ensure proper screen placement. In addition, if a clay layer is encountered, the <br /> underlying sands will be tested for contamination. With this understanding, I concur with this sampling <br /> strategy as discussed in our phone conference rather than that described in the revised work plan. <br /> The revised work plan states (page 9)that evaluation monitoring will be conducted until the ponds are <br /> closed and an end to monitoring is approved by the Board. In addition,the work plan states that an <br /> Engineering Feasibility Study pursuant to Title 27 does not appear to be appropriate and will not be <br /> conducted. These issues will be addressed once we have a better understanding contaminant migration <br /> from the lime ponds. <br /> California Environmental Protection Agency <br /> 0 Recycled Paper <br />