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Mr. Jeff Tierney <br />September 2, 2020 <br />DATA EVALUATION <br />The San Francisco Bay Regional Water Quality Control Board (SFRWQCB) Environmental Screening <br />Levels (ESL5)1 were selected as screening level criteria for constituents detected in soils samples. <br />Based on the general compositions of TPH-DRO (C10-C22), TPH-MO (C22-C32), and TPH-MO (C32- <br />C40), "Petroleum - Diesel" was considered the most representative of TPH-DRO (C10-C22) and <br />"Petroleum — Motor Oil" was considered the most representative of TPH-MO (C22-C32) and TPH-MO <br />(C32-C40). <br />The SFRWQCB's most conservative Soil Tier 1 ESLs were used to evaluate TPH detected in the soil four <br />sidewall samples. Detected concentrations in the soil samples did not exceed the Tier 1 Soil ESL for <br />"Petroleum - Diesel" of 260 ring/kg or "Petroleum — Motor Oil" of 1,600 mg/kg. Soil analytical data <br />compared to residential, commercial/industrial, construction worker, leaching to groundwater, and Tier 1 <br />Soil ESLs are presented in Table 1. <br />SUMMARY AND RECOMMENDATIONS <br />Response activities included temporary removal of approximately 80 feet of track, excavation of <br />approximately 71 cubic yards of TPH-affected soil and ballast, imported crushed rock subbase and ballast <br />backfill, and track replacement. Waste generated during the response activities was properly <br />containerized in seven roll-off bins and is currently pending profile approval for disposal at Waste <br />Connections, Potrero Hills Landfill in Potrero, California. Final waste manifests and associated weigh <br />tickets will be provided under separate cover. <br />Six soil samples were collected from the excavation sidewalls and floor and analyzed for TPH-DRO and <br />TPH-MO. Detected TPH-DRO and TPH-MO concentrations in the soil samples did not exceed the Tier 1 <br />Soil or residential shallow soil exposure ESLs. <br />The objectives of the response activities are considered met as summarized in this Report and no further <br />action is recommended. <br />CLOSING <br />Please feel free to contact Brittani Jacobsen at 916 865 3145 or Brittani.Jacobsenaarcadis.com or Scott <br />Hackman at 916 786 7369 or scot hackmara.arcadis.com if you have any questions regarding the <br />information presented in this Report. <br />1 SF-RWQCB. 2019. Environment Screening Levels Rev. 1. January. <br />arcadis.com <br />2020.09.02_Stktn_20.07.22_Loc Dsl Rls_Sum Rpt_Draft <br />Page: <br />4/5