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Harding Lawson Ilasociates <br /> . c _ <br /> September 26, 1994 <br /> 29350 4 <br /> Mr.James Brathovde RECEIVE <br /> California Regional Water Quality Control Board � ? � 'fl� <br /> 3443 Rouficr Road SEP 3 <br /> Sacramento, California 95827-3098 ENVIRONMENTAL AALAH <br /> PERMITIOVICLS <br /> Pond Closure Addendum <br /> Confirmation Soil Borings <br /> USC/A Division of Hydrite Chemical Company <br /> 144H Shaw Road <br /> Stockton, California <br /> Dear Mr. Brathnvde: <br /> INTRODUCTION <br /> Harding Lawson Associates (HLA) is pleased to present this addendum to the August 12, 1994 revised <br /> pond closure plan presented to the California Regional Water Control Board (RWQCB) on behalf of <br /> USDA Division of Hydrite Chemical Company (USC)- The site is located at 1448 Shaw Road to <br /> Stockton. California- The revised pond closure plan ciP.soribed the procedures to be employed for <br /> removal of the remaining contents in the pond and a proposed sampling plan to establish clean <br /> closure of the pond. Based on the findings of recent sampling, deeper cunfirnration borings are <br /> necessary. <br /> BACKGROUND <br /> Pond contents have been removed_ CurrenLly, confirmatinn samples have been collected from eight <br /> locations within, and one location outside the pond as shown on the attached Plate. Samples have <br /> boon collected between the depths of 6 and 8 feet in all the borings. Based on the analytical results, <br /> which have shown sodium levels at concentrations above background,additional sampling at depth is <br /> Tequired. <br /> ADDMONAL SAMPLING <br /> To evaluate the sodium levels, HLA will drill swan borings to 20 feet below the existing base of the <br /> pond. Boling locations will coincide with the existing confirmation Sampling locations (SIA, SiB, <br /> S2B, S3, S4, 55, Se, and 57 (sec attached Platc). The bor ngs will be diffled using hnllow seem auger <br /> drilling equipment- Samples will be collected at 8A, 10.0, 12-0 14.0, 16.0, 18.0, and 20.0 feet hgs. <br /> The samples will be collected using a split barreled sampler lined with stainless steel liners. Upon <br /> collection, the samples will be capped, scaled, labeled, and placed in a chilled conlainer. The samples <br /> will be transported to an analytical laboratory under chain of custody procedures. Samples submitted <br /> to the laboratory will be analyzed for sodium. <br /> Upon completion of the borings, they will be backfilled with bentonite chips. The bentonite chips will <br /> be hydrated with 5 gallons of water every 5 feet. <br /> Engiriccrni;i and 3247 Ra s Circa.Sacmmerio.Ca 9iF2J 91E.3H.0793 FAY 91EMS 5633 <br /> Ei,wonmenlM Services 3 Swbs..,,i Nom•.!:•;nuonum,•OF", W, <br /> ZOOS O.LNa VH3VS VTH ££9569milT$ 851171 WH/60 <br />