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Nestle USA Inc. 0 - 2 - 0 29 August 2005 <br /> immediate vicinity, there were no soil vapor samples collected to assess the residual levels of <br /> contamination that may have been outside the radius of influence of VE-8. <br /> The final confirmation sampling performed at the Stockton Avenue property does not meet today's <br /> standards of performance for SVE in our Region and is inconsistent with the final confirmation <br /> sampling that Nestle performed for the Industrial Avenue SVE system in 2001. Furthermore, <br /> Nestle's Water Quality Assessment dated August 1994(Section 6: Recommendations for Soil Source <br /> Area Remediation) indicates Nestle intends to assess whether remediation is complete at SVE sites <br /> by advancing borings and collecting soil samples for analysis. Today, soil vapor data is considered a <br /> better indicator than soil samples for assessing the effectiveness of SVE,but it is clear that Nestle <br /> intended to do intrusive sampling to assess the effectiveness of SVE systems and this was not <br /> conducted at the Stockton Avenue property. Therefore, we request that Nestle submit a work plan by <br /> 14 October 2005 to assess potential residual vadose zone contamination at the Stockton Avenue <br /> property and complete assessment of the SVE remedial actions conducted in the 1990s. The work <br /> plan should include advancement of several borings in the former hotspots and collection of soil <br /> vapor samples from multiple depths for laboratory analysis. The new data should be used to <br /> complete assessment of potential vapor intrusion hazards near the Stockton Avenue source area. We <br /> recommend including the proposed vapor sampling in the Industrial Avenue area in this work plan. <br /> 3. New guidance on evaluating vapor intrusion into indoor air has been issued by the Department of <br /> Toxic Substances Control (DTSC) since Regional Board staff provided comments on the Draft Risk <br /> Evaluation on 10 November 2004. Future investigations and assessment of potential vapor intrusion <br /> hazards should follow this guidance. <br /> If you have any questions,please contact me at (916) 464-4733 (mpierceQwaterboards.ca.eov). <br /> Marcus L. Pierce, C.Hg. <br /> Engineering Geologist <br /> cc: <br /> Ms.Noelia Marti-Colon, Nestle USA,Inc. <br /> Mr. Binayak Acharya, Environmental Cost Management <br /> Ms. Margaret Lagorio, San Joaquin County Environmental Health Department, Stockton <br /> Mr. Matt Machado, City of Ripon <br />