SITE INFORMATION AND CORRESPONDENCE

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Mr. Anthony Sa0ara • Page 5 April 14, 1988 Should you have questions in redrafting the CRP, please call Leticia Rico at (916) 920-7516 or William Kilgore at (916) 924-2599. 19. Page 26 and page 10. At this stage of the investigation, you may want to take a greater number of samples at or near the surface around the outside of the building to identify the limit of the surface contamination. Are there field methods (other than pH) to identify and roughly quantify possible metals contamination? If so, this type of method may be useful in roughly delimiting the extent of contamination without the time and expense of remobilizing and analyzing additional soil samples. In any case, the taking of more samples and archiving them for possible future analysis may save the cost of remobilizing for another sampling round. An aerial photo of the site show areas of staining. A copy of the photo is enclosed with the areas of soil staining outlined in red. We may require that these and the rest of the site be sampled in a random manner unless historical information is submitted that is adequate to ensure that these areas are uncontaminated. Methods for developing a sampling plan for these areas are contained in Test Methods for Evaluating Solid Waste, 3rd Edition, SW-846 USEPA 9/86 which is enclosed. This question may be resolved at the time of the on-site inspection by DHS and your staff. 20 . Page 27, section 2 . 5. 1, and page 10, section 2 . 2 . 1 (a) . Specify sample collection procedures in detail . The use of core sleeves is not recommended in this situation. There is a good probability that the acid conditions in the soil will leach some of the zinc or copper in the sleeves and give artificially high metals concentrations in the subsequent sample analysis. The use of core sleeves prevents the recording of lithology of the soils at the site. We believe that detailed and accurate bore logging is paramount in discovering the fate of contaminants. Soil boring holes are to be back filled with bentonite-cement. The Workplan is to be revised to include provisions to ensure that cement or bentonite-cement used for sealing the boring is commercially produced and mixed to manufacturer's recommended guidelines, including the water, or if cement or bentonite-cement from bags is used that it be blended to Halliburton cementing table specifications. If bentonite is used in the cement and it is not drybatched (blended) with the cement, but added to water separately, special procedures for "pre-hydrating" recommended by Halliburton must be followed (procedures are enclosed) . Cement or formulations of cement must be thoroughly mixed in the fluid state. This is achieved by utilizing commercial manufacturers, a grout plant, venturi mixer, or a high shear mud pump.