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k' ■ KLEINFELDER directly beneath the former tank bath areas. Access to the Wastewater Treatment area is limited by nearby structures and above ground facilities. The proposed soil sampling locations reflect this limited access. Concrete coring is proposed in all proposed sampling locations. Kleinfelder's approach is based on the following assumptions: 1. The COPC include the five metals listed above, cyanide and both acidic and alkaline solutions. 2. Specific spill areas have not been reviewed or documented in the review information available to Kleinfelder. Kleinfelder contacted Mr. John Jackson, inspector from the County Health Department who has visited the site regarding spill areas. He commented that he was not aware of a specific spill site/area(s). Proposed sampling locations area based on available information and site conditions (2005) regarding tank bath locations (Plating room) and wastewater treatment processes, holding tanks locations, filter areas, etc (Treatment Plant Area). 3. It is Kleinfelder's understanding that subsurface piping is not located in the Plating Room or between the Plating Room and Wastewater Treatment Area. 4. Kleinfelder's proposed sampling depths are based on bottom of tank elevation of the stored COPC (at grade, above grade, or subsurface). 5. Kleinfelder has proposed maximum soil sampling depths of 9 feet below ground surface (bgs) based on concrete flooring and the relative immobility of heavy metals in soil compared to other chemicals such as volatiles. 6. Proposed soil sampling analyses is for surface and near surface sampling initially in the Plating Room. Deeper soil samples will be put on hold pending review of shallower soil samples/analytical results. Subsurface soil sampling analyses will be conducted at locations where the highest metal concentrations for each COPC are detected. This sampling approach is based on an assumption that migration of metals will attenuate fairly rapidly with depth. 7. Similar methodology is proposed in the Wastewater Treatment Area. However, due to concrete subsurface vaults and subsurface secondary containment areas, initial sampling depths in these specific areas are proposed at the base of these features (approximately 5 feet bgs). 8. At this time, solvents have not been noted at the site, although it is not uncommon for plating shops to clean parts with solvents such as Trichloroethene (TICE). Kleinfelder proposes screening the soil samples collected using a photo-ionization detector PID. Readings noted above background levels at approximately 10 ppm or greater will be noted for potential volatile organic analyses by EPA Method 8260. PID readings will be discussed with DTSC prior to requesting additional volatile organic analyses. 57252.T02/ST05R999/DH:Iv Page 13 of 29 0 2005 Kleinfelder, Inc. September 1,2005