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S E C O R l <br /> • Ms. Devra Lewis <br /> April 8, 2005 <br /> Page 4 <br /> PSV-7: This soil vapor monitoring point was proposed to evaluate the effectiveness of well <br /> SVE-2. The location was established out side of the excavation limit so that the liner <br /> placed at the bottom of the excavation would not be punctured. Further discussion of this <br /> well is included in the response for comment 7. <br /> PSV-8: This soil vapor monitoring point was proposed to evaluate the effectiveness of SVE <br /> system in the area between the dual phase extraction system and the screened areas of <br /> ASVE-3 and ASVE-4. Further discussion of this well is included in the response for <br /> comment 9. <br /> PSV-9: This soil vapor monitoring point was proposed to evaluate the effectiveness of well <br /> ASVE-6. Further discussion of this well is included in the response for comment 7. <br /> 9. As shown on Figure 3 of the Work Plan, there is a large area between the dual <br /> phase extraction system west to the screened areas of ASVE-3 and ASVE-4. The L&M <br /> OU needs to discuss how it will determine the effects of the SVE system in this area. <br /> . An additional soil vapor monitoring point (PSV-8) is proposed as requested; however since <br /> the screen interval for wells ASVE-3 and ASVE-4 are beneath the apartments and not in <br /> this area it may not be able to determine the effects of the SVE system in this area. <br /> 10. Regional Board staff concurs with moving proposed soil vapor monitoring points <br /> under the apartment buildings, as requested in DTSC's attached in memorandum, to <br /> accommodate data needs for the completion of a human health risk assessment. <br /> L&M OU agrees with the request; however please note the final locations will depend on <br /> available access. <br /> 11. Regional Board staff does not concur with drilling soil vapor monitoring point <br /> borings deeper than the proposed total depth of the proposed soil vapor monitoring <br /> point to collect additional data for the human health risk assessment, as commented <br /> on in the attached DTSC memorandum. For the data needed from deeper depths, the <br /> L&M OU will need to use a separate boring from the proposed soil vapor monitoring <br /> point installation boring. <br /> Comment noted. <br /> 12. The L&M OU may collect additional data requested by DTSC from either installing <br /> additional soil vapor monitoring points or from active soil gas sampling. <br /> Comment noted. <br /> Stockton Parcel 2A:Agency Response Letter 6-10-04. SECOR Intemational Incorporated <br />