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Mr. Daniel Decker - 2 - 13 July 2001 <br /> MW-4B, as requested in our 22 June 2001 letter. Furthermore,the hydropunch locations should <br /> include samples from deeper than 80 feet bgs based on the concentrations from deep samples at <br /> HP-01 and several locations where concentrations increase with depth. <br /> 4. The Work Plan does not discuss how field staff will determine if the casing in the water wells is <br /> intact. The Work Plan should discuss this. Furthermore, the Work Plan should discuss how <br /> these locations would evaluate the distribution of contaminants in the vicinity of the two wells if <br /> the casing is intact and groundwater samples are not collected. <br /> 5. The Work Plan states that HP-1 and proposed discrete sampling in PW-01 and PW-02 adequately <br /> address the area between MW-lA and MW-2A. We disagree with this conclusion. There is a <br /> 200-foot area between MW-lA, MW-2A,HP-1, and HP-7 where no soil or groundwater samples <br /> have been collected. Hydropunch samples from HP-7 from two distinct depths had <br /> concentrations above water quality goals. This area and the contamination in the shallow water- <br /> bearing zone southeast and southwest of MW-2A is not defined. <br /> 6. The Work Plan proposes to collect two groundwater samples to evaluate natural attenuation and <br /> chemical treatment technologies. Two samples will not adequately address the two identified <br /> water-bearing zones or the general chemistry parameters within and outside of the plume areas. <br /> By 3 August 2001,please submit a revised work plan that addresses the above comments. The interim <br /> remedial action plan,which is due by 26 October 2001, should include the pre-remediation testing <br /> results and recommendations for monitoring wells to delineate the lateral and vertical extent of <br /> groundwater contamination. If you have any questions you may contact me at (916)255-3119 or by <br /> email at Iewisdna,rb5s.Swrcb.ca.Rov. <br /> &013-t,CC_—X�4UJ-6A- <br /> DEVRA LEWIS <br /> Environmental Specialist II <br /> cc: Mr. Jeff Wong, San Joaquin County Health Department, Stockton <br /> Ms. Linda Huff, Huff&Huff, LaGrange, Illinois <br /> Mr. Joe Weidmann, Haley&Aldrich, Inc., San Diego <br />