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0 • <br /> The letter stated that the nature of the `glass batch (dust) material' proposed for disposal at the <br /> WDS indicated that some of the dust contains selenium. It was stated that selenium bearing dust <br /> is being disposed of as hazardous waste to IT Corporation and the majority of the dust for onsite <br /> disposal has the approximate composition: <br /> Component Percen . . - <br /> sand and glass dust T-717— <br /> dolomite <br /> 0-60dolomite 10-40 <br /> soda ash 15-25 <br /> limestone 2-10 <br /> roue 1-3 <br /> salt cake 0.5-2 <br /> cobalt 0-0.25 <br /> The letter referenced previous analytical testing and stated that with this information they were <br /> requesting permission to dispose of the water material at their WDS on May 6, 1983 and that <br /> because they agreed any dust containing selenium is hazardous (and that typically selenium Is <br /> not used at the Lathrop facility) and because they planned to remove wood, plastic and metal for <br /> the waste disposal stream, they were requesting the Water Board reconsider their previous <br /> decision which denied a Class III designation for their WDS. <br /> -TAO MILEF 'j Ayen Repo State Ilpartmeht ref _ er1i� s <br /> The letter references the `Preliminary Investigation for Surface and Subsurface Contamination of Soils <br /> and Groundwater Final Report"apparently prepared by Woodward Clyde Consultants (report was not <br /> available for our review).The letter stated the following deficiencies to the report including: <br /> TTLC is to be used to classify wastes with respect to hazardous/nonhazardous and should not be <br /> considered a goal or cleanup level. <br /> Analytical results for hexavalent chromium (Cr') were inadequate based on the detection limits <br /> and test method and it was requested all wells be resampled and analyzed for CR VI in <br /> accordance with EPA test methods for evaluating Solid Waste (SW--846) before abandonment of <br /> the wells can be considered. <br /> The proposed excavation of a maximum of two feet of soil along the west side of the building <br /> appears adequate except in areas of LSB-4 and LSB-7 because copper concentrations in the soil <br /> samples at these two locations increases with depth. Therefore, soil excavation in these areas <br /> needs to be deeper.After soil is excavated, then confirmation samples should be collected. <br /> Removing the concrete sump should eliminate the source of groundwater contamination. <br /> Comments pertaining to cleaning and replacing the sump backfill material were planned to be <br /> submitted following a detailed explanation was provided. Confirmation samples and testing must <br /> include CR VI in addition to copper and lead. <br /> Groundwater monitoring wells must continue to be maintained, sampled and analytical testing <br /> conducted and reported. <br /> Ninyo i£Moore 1 500 E.Louise Avenue,Lathrop,San Joaquin County,California 1 104690095 1 August 11,2017 15 <br />