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Mr. Marshall Cloud <br /> May 25, 2006 <br /> Page 2 <br /> DTSC has reviewed the SAP and has the following comments: <br /> General Comments: <br /> 1) The Draft SAP is unclear as to whether previously collected analytical data will be <br /> used to augment the proposed data set in this sampling plan. The revised SAP <br /> should identify the previously collected data that will be used to support the <br /> development of an updated human health risk assessment. <br /> 2) The Draft SAP proposes only 24 soil borings to cover a site area that is close to <br /> 7,000 acres. While the SAP provides a brief overview of previous soil and soil gas <br /> data in Appendix A of the report, it does not provide historical sampling locations, the <br /> types of data collected, nor locations and results from previous soil removal actions. <br /> DTSC recommends an updated Draft OU2 HHRA SAP be developed and submitted <br /> to the regulatory agencies. DTSC recommends the revised SAP include both <br /> figures and tables clearly identifying the locations and results of previous removal <br /> actions, sampling results, and characterization studies. The revised SAP should <br /> provide a rationale consistent with existing guidance as to why this number of <br /> samples is sufficient or, if appropriate, expand the number of samples and provide a <br /> rationale for why the revised number is sufficient. <br /> Specific Comments: <br /> 1) Page 2-3, Exposure Area 1; It is stated in the report that Exposure Area (EA) 1 <br /> encompasses "...the commercial industrial building areas in the Central Area and <br /> the northern portion of the South Balloon." Figure 3 of the SAP shows the boundary <br /> limits for EA 1 ending north of South Crane Way. As stated in the June 2002 Final <br /> Remedial Action Report for Institutional Controls at South Balloon Area, the South <br /> Balloon is identified as"...south of the centerline of South Crane Way." Please <br /> revise this section of the SAP to state EA1 encompasses only the Central Area. <br /> 2) Page 2-9, OU2 Record of Decision bullet; See specific comment #1. <br /> DTSC recommends that DDJC-Sharpe revise the Draft OU2 HHRA SAP to provide both <br /> figures and tables to summarize the historical sampling results and previous removal <br /> actions planning on being used to augment the proposed sampling effort. HERD's <br /> comments on the Draft SAP are attached to this letter. DTSC recommends <br /> incorporating HERD's comments into the development of the human health risk <br /> assessment. <br />