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SOIL AND RESIDUE MANAGEMENT PLAN,STOCKTON FORMER MANUFACTURED GAS PLANT SITE <br /> to collect soil from 31h to 21 feet bgs.At 16 feet bgs moisture,a hydrocarbon odor, and a <br /> black-oily color were encountered. The moisture and odors continued between 16 and 20 <br /> feet bgs.At 21 feet bgs metal debris was encountered in addition to perched liquid.The <br /> driller noted that there may also be concrete at 21 feet bgs.Samples were collected from 15 <br /> to 20 feet bgs and sent to QAL and TES. <br /> Source Area 2 <br /> The Source Area 2 sample was collected from a boring that was drilled between borings SB- <br /> 2,B-25, and Sb-9-95.Hand augering was conducted down to 4 feet below ground surface <br /> (bgs).The geoprobe drilling rig was used to collect soil between 4 feet and 16 feet bgs.The <br /> soil encountered between 4 and 8 feet bgs contained a tarry material with strong <br /> hydrocarbon odors.Between 8 and 12 feet bgs there was perched liquid with an oily sheen <br /> and strong hydrocarbon odors.At 16 feet bgs solid lampblack material with the consistency <br /> of licorice was encountered.Samples were collected between 8 and 16 feet bgs and sent to <br /> QAL and TES. <br /> Source Area 3 <br /> The Source Area 3 sample was collected from a boring that was drilled where a plate sits on <br /> top of the tar pit.The geoprobe was usedto drill down to 7 feet bgs,the depth where refusal <br /> was encountered.Tar mixed with wood and fill was encountered between the surface and 7 <br /> feet bgs. Samples were collected from 3 to 7 feet bgs and sent to QAL and TES. <br /> Sample Results <br /> Table 1 presents the laboratory results for the residue samples. Source Area 1 residue passed <br /> the fish bioassay test with an LC50 greater than 750 mg/L and did not exceed the TCLP or <br /> the TTLC thresholds.Total PNAs were less than 1 mg/kg.Source Area 2 residue passed the <br /> fish bioassay test with an LC50 greater than 750 mg/L and did not exceed the TCLP or <br /> TTLC thresholds.Total PNAs were 9.3 mg/kg.The Source Area 3 residue sample did not <br /> pass the TCLP test for benzene at 19 mg/L and it had the highest concentrations of PNAs, <br /> BETX,and TPH.The Source Area 3 sample was the only sample that did not pass the fish <br /> bioassay testing. Based on this limited investigation,it appears that materials from Source <br /> Area 1 and Source Area 2 are classified as non-hazardous and therefore acceptable for <br /> disposal at a Class 11 landfill(such as Forward Landfill).Material from Source Area 3 would <br /> be classified as RCRA hazardous and would be transported to a RCRA Subtitle C licensed <br /> - facility. <br /> Conclusion and Recommendation <br /> Based on the soil sampling results,the following soil management plan will be followed <br /> during the soil excavation,as shown in Figure 1. Source Area 3 residue is a RCRA waste and <br /> will be treated and disposed of appropriately. Soil from Source Areas 1 and 2 as well as soil <br /> from the six non-source areas consists of clean soil or designated Class II soil (based on <br /> recent analytical results and LC50 bioassay test results for residue). Soil from these areas <br /> will be visually segregated and tested for PNAs.If the soil is below the threshold level for <br /> PNAs,it will be used as backfill.Otherwise,the soil will be disposed of at a Class H landfill. <br /> SFO/RESIDUE.DOC 3 <br />