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Marc Oler, Shell - 2 - 13 June 2016 <br /> Shell Pipeline 2016 Release, Tracy, San Joaquin County <br /> The contaminated soil under the pipeline was excavated in 10-foot sections during the initial <br /> response and replaced with backfill material to support the pipeline. Shell screened the <br /> excavation area prior to backfilling. Shell proposes using a drill rig to collect confirmation soil <br /> samples from native soil beneath the pipeline. <br /> Excavated soil will be analyzed for petroleum hydrocarbons and if concentrations are below the <br /> screening criteria, Shell proposes to use it as backfill material. Soil failing the criteria will be <br /> sent offsite for disposal. Shell will excavate Site soil until it passes the screening and cleanup <br /> criteria. <br /> Our comments are: <br /> 1. Central Valley Water Board staff concurs with the excavation of contaminated soil at the <br /> Site. Shell should collect confirmation sidewall samples at least every 20 feet and a <br /> minimum of one every 400 square feet from the floor of the excavation to verify the <br /> contaminated soil has been removed. Shell needs to cxcaVaie contaminated Soil until <br /> the cleanup levels are met and submit a report of findings within 60 days following the <br /> completion of the excavation activities. The report of findings needs to include figures <br /> showing the extent of the excavation, the soil sample results, an estimate of the amount <br /> of mass remaining, an estimate of the amount of crude oil released, and a summary of <br /> the activities. <br /> 2. Central Valley Water Board staff concurs with the Work Plan proposal to collect soil <br /> samples 2 feet below the floor of the excavation from 20 percent of the floor samples <br /> locations. These samples should be analyzed for TPHc, BTEX, and naphthalene. <br /> These data will be used to assess the vertical extent of petroleum hydrocarbon <br /> contamination. <br /> 3. Excavated soil used for backfill material must be sampled and concentrations should be <br /> below the residential screening criteria. <br /> In summary, Shell needs to excavate petroleum hydrocarbon contaminated soil at the Site and <br /> collect confirmation soil samples from the sidewalls and floor of the excavation to verify that <br /> remaining soil concentrations are not above the criteria listed above. Shell needs to submit a <br /> report of findings 60 days following completion of excavation activities. If you have any <br /> questions regarding this letter, you may contact me at (916) 464-4819 or by email at <br /> kshelton watle�rboaar�ds.ca. ov. <br /> KRISTI SHELTON, P.E. <br /> Water Resources Control Engineer <br /> Aboveground Tanks Cleanup Unit. <br /> cc: Alameda County Environmental Health Department, Alameda <br /> San Joaquin County Environmental Health Division, Stockton <br /> Christine Pilachowski, AECOM, Oakland <br /> Joe Morgan, AECOM, Oakland <br />