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Jerry Lile Page 2 <br /> June 27, 2005 <br /> Slough and the Stockton Channel. <br /> HERD has participated in numerous meetings and teleconferences, reviewed numerous <br /> documents, and provided written or oral comments on issues related to preparing an <br /> acceptable human health risk assessment (HHRA). <br /> In a memo dated March 3, 2005 HERD provided review comments on the February 25, <br /> 2004 "Work Plan for Soil Vapor Assessment, Stockton Parcel 2A, L & M Operable Unit, <br /> 666West Weber Avenue, Stockton, California"prepared by Secor in Rancho Cordova, <br /> California and received by HERD on February 28, 2005. <br /> DOCUMENT REVIEWED <br /> HERD reviewed the June 7, 2005 the `Soil Vapor Sampling Work Plan and Response to <br /> DTSC HHRA Comments Dated March 3, 2005, Delta View Apartments, Stockton Parcel <br /> 2A, Stockton, California"prepared by Earth Tech in San Jose, California and received by <br /> HERD on June 8, 2005. <br /> COMMENTS <br /> 1. Responses were provided for HERD's comments 1, 2a, 2b, 2c, 2d, 2e, 2f, 2h, 2i, <br /> and 3c. Items not responded to are associated with the undeveloped area of the L & <br /> M OU. The responses state soil vapor sampling in the apartments' area is proposed <br /> to be conducted consistent with DTSC recommendations in our March 3, 2005 <br /> memorandum, however a few points of the work plan require clarification. <br /> 2. HERD's comment 2.g. requested collection of samples not only from 5 ft, but also at <br /> or just above the capillary fringe for SV-2, SV-6, and SV-7. The responses stated <br /> that item 2g is responded to by SECOR (May 20, 2005 responses, Attachment B). <br /> The text of the work plan does not specify as in the SECOR responses that soil <br /> vapor and geotechnical samples will be collected from dual nested wells at 5 ft and <br /> at or just above the capillary fringe from locations now designated as SV-19, SV-23, <br /> and SV-24 (formerly designated as SV-2, SV-6, and SV-7, respectively). <br /> 3. Include a sampling point in the vicinity of former sample SV-10. <br /> 4. DTSC guidance calls for use of EPA Method 16 for hydrogen sulfide analysis <br /> (DTSC, 2003); however, ASTM Method D-5540 may be used provided QA/QC data <br /> are submitted to verify that the method is as good as or better than Method 16. <br /> 5. Include analyses for PAHs other than naphthalene using method TO-13 SIM. <br /> Include napthalene analyses and quantification in TO-15 SIM. <br /> 6. In addition to reporting soil moisture content (% by weight) include soil water-filled <br /> porosity. <br /> 7. HERD is available to discuss the benefits of separating the L & M OU into two areas <br /> of concern (ADCs), to expedite risk evaluations in the apartments' area. One AOC <br /> 050627JL.doc <br />