SITE INFORMATION AND CORRESPONDENCE

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Jerry Lile • • Page e 3 June 27,2005 being the Delta View Apartments (the apartments' area) and the second AOC being the urideveloped area. CONCLUSIONS HERD reviewed the June 7, 2005 "Soil Vapor Sampling Work Plan and Response to DTSC HHRA Comments Dated March 3, 2005, Delta View Apartments, Stockton Parcel 2A, Stockton, California"prepared by Earth Tech in San Jose, California. HERD recommends the above modifications to the work plan to obtain adequate soil vapor and geotechnical data for a baseline human health risk assessment of indoor air for the current apartment dwellers within the zone of influence of the SVE system prior to start up of the SVE system. Responses to HERD's comments on the undeveloped portion of the L & M OU remain to be submitted. To expedite risk evaluations in the apartments' area, the responsible parties should address the L & M OU as two areas of concern (ADCs), preparing a separate HRA using a hot spot approach for each AOC. One AOC being the Delta View Apartments (the apartments' area) and the second AOC being the undeveloped area. HERD recommends filling the remainder of the HHRA data gaps in the apartments' area, consistent with HERD's February 2, 2005 memorandum, as soon as feasible and irrespective of the operational status of SVE system. HERD continues to recommend: (1) collecting supplemental data to address all data gaps; (2) submittal of the complete data sets as well as the data sets proposed for use in the HHRA in electronic format to ensure site characterization is adequate for HHRA purposes; and (3) preparation of the revised HHRA consistent with comments provided in HERD's September 9, 2004 and September 28, 2004 memoranda using the DTSC/HERD approved HHRA data set. REFERENCES DTSC, 2003. Advisory Active Soil Gas Investigations. January 28, 2003. Reviewed by: David L. Berry, P .D. Senior Toxicologist Science, Pollution Prevention and Technology Program Human and Ecological Risk Division 050627JL.doc