WORK PLANS - Laserfiche WebLink

Home Browse Search

Soil Assessment Report 324 East 11th Street Tracy, California October 12,2017 ■ Total petroleum hydrocarbons as diesel(TPHd)by EPA Method 8015M. SITE ASSESSMENT RESULTS Field Observations For boring B-11, light hydrocarbon staining and odors were observed in soil at approximately 9 to 10 ft bgs during field screening of soil samples. Elevated PID readings were measured at approximately 5 ft bgs (99 ppm) and 10 ft bgs (386 ppm) in boring B-11. For borings B-12 and B-13, no staining/odors were observed during visual observation and field screening with a PID. Field observations are noted on the boring logs in Appendix C. Soil Analytical Results Soil analytical results are summarized on Table 1. The laboratory analytical reports are included in Appendix D. All analytical results for TPH,VOCs, SVOCs, PCBs and Title 22 metals were below LTCP criteria or Regional Water Board ESLs, except as clarified below. Petroleum Hydrocarbons and VOCs: No TPHd, TPHg, BTEX or VOCs were detected in soil from boring B-12 at 10 ft bgs. For soil from boring B-11 (adjacent former boring B-1), only low concentrations of benzene, ethylbenzene and naphthalene were detected. While the benzene (0.12 mg/kg) and naphthalene (0.3 mg/kg)concentrations in sample B-11-10' exceeded the Tier 1 ESLs of 0.044 mg/kg and 0.033 mg/kg, respectively, these concentrations were well below the LTCP criteria for benzene and naphthalene shown on Table 1. Oil & grease was detected at a concentration of 69.3 mg/kg for B-11: no ESL or LTCP criteria has been established for oil&grease. Other VOCs detected at low concentrations in boring B-11 include the following petroleum hydrocarbons: n-butylbenzene, sec-butylbenzene, isopropylbenzene,p-isopropyltoluene,n-propylbenzene and 1,3,5-trimethylbenzene. SVOCs:All SVOCs were below ESLs or detection limits for boring B-11, except for 2-methylnaphthalene and 2-methylnaphthalene. The 2-methylnaphthalene concentration of 0.42 mg/kg slightly exceeds the Tier 1 ESL of 0.25 mg/kg. However, this concentration of 2-methylnaphthalene is well below the residential direct exposure human health risk ESL of 240 mg/kg. Pentachlorophenol (PCP) was not detected above the laboratory reporting limit of 1.0 mg/kg. Due to lack of PCP detection, Pangea did not coordinate the contingent analysis for dioxin and furan consistent with the March 15,2016 agency letter. PCBs:PCBs were below detection limits. Metals: Soil from boring B-11 at 10 ft bgs contained elevated arsenic (7.3 mg/kg) and chromium (21 mg/kg) concentrations. Due to these elevated concentrations, Pangea analyzed soil from boring B-12 at 5 ft bgs for arsenic (3 mg/kg) and chromium(24 mg/kg). Pangea corresponded with SJCEHD to determine if additional analyses were required but did not receive a response (Appendix A). All other analyzed 4