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Mr. Vaughn 3 1 March 1995 <br />this usage, and should indicate if the high limits are the result of matrix interference or other <br />problems. The results obtained clearly show that these soils are not "inert". The analytical <br />methods used for diesel and total petroleum hydrocarbons (water -leachable) were, apparently, <br />8015 (a GC/FID method) and 418. 1, but the lab documentation is incomplete and unclear. <br />The analytical results obtained for the diesel, BTEX, and total petroleum hydrocarbons were <br />averaged in order to assess the levels present. This is not appropriate. Therefore, I base my <br />conclusions on the individual analyses, emphasizing the BTEX results. <br />The Report presents analytical results, for comparison purposes, of asphalt from a Fremont, CA <br />city street and from redwood extract. After discussion with staff of the Underground Tank Unit, <br />I consider these analyses irrelevant and inappropriate and have disregarded them. <br />The City of Tracy wishes to reuse these soils in construction projects. After reviewing the <br />analytical results, I suggest the following: <br />1. We approve the proposed reuses p gr v-'dgthat the BTEX -containing soils are encapsulated, that <br />is, placed in an area such that they will be underlain by low -permeability, co_ I )acts fill and <br />overlain by asphalt pavement. The soils containing diesel and petroleum compounds (some <br />reported as heavier -than -diesel) may be used if adMiMd with asphalt, but not as unmixed fill. In <br />all cases, ground water may not be shallower at any time than 5 feet below the base of the filled <br />areas. <br />2. We also should request reports on the disposition of the soils prior to approval of the reuse. In <br />addition, we should request notification prior to the removal of the soils from the treatment units so <br />that we may observe and sample if we wish. <br />In conclusion, I do not believe that this sampling and analytical work is of high quality or in <br />compliance with our requests or the terms of the WDR Order 94-216. However, there is sufficient <br />information for us to allow certain restricted reuses. Expediting the proper closure of this site is, I <br />believe, desirable. <br />C <br />