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Pilkington North America Page 2 of 3 500 E. Louise Ave. Lathrop, CA October 27, 2015 Former Tiered Permitted Used Oil Treatment Area NFAR analyzed by EPA Method 8015M for diesel and motor oil. The contaminant concentrations were less than the reporting limits in all samples except for 140 mg/kg TPHmo in 62-10'. Sample B2- 10' was also analyzed for polychlorinated biphenyls (PCBs) by EPA Method 8082, for semivolatile organic compounds (SVOCs) by EPA Method 8270C, total petroleum hydrocarbons quantified as gasoline (TPHg), benzene, toluene, ethylbenzene and xylenes (BTEX) and methyl tert-butyl ether (MTBE) by EPH Method 8260B. The concentrations of all these analytes in the sample analyzed were less than the method reporting limits. A No Further Action Required (NFAR) letter was requested from the EHD for the release in the former tiered permitted used oil treatment facility area, but the EHD could not issue an NFAR letter as the work was performed without EHD oversight. On April 20, 2015, after obtaining the approval of the Central Valley Regional Water Quality Control Board (CVRWQCB) and the California Department of Toxic Substances Control (DTSC), the EHD entered into a contractual agreement with the responsible party to provide regulatory oversight of the case investigation pursuant to the California Health and Safety Code, Section 101480. By letter dated June 2, 2015, the EHD provided an evaluation of the investigation to date and directed resampling of soil near the most impacted deep soil sample (WTP#3) and submission of the sample for the laboratory analyses needed to complete the analytical protocol for releases associated with waste oil tanks or tanks of unknown contents. The protocol included analyses for volatile organic compounds (VOCs) by EPA Method 82608, for heavy metals (often referred to as the CAM 17 metals or the Title 22 metals) by EPA Method 6010B for most of the metals and by EPA Method 7062 for antimony and arsenic, EPA Method 7131 for cadmium, EPA Method 7421 for lead, EPA Method 7471A for mercury, EPA Method 7521 for nickel, EPA Method 7742 for selenium, and EPA Method 7841 for thallium. Two soil samples were collected on June 11, 2015 by a representative of the consulting firm AGE under observation by a representative of the EHD. The samples were collected from locations considered and approved by the EHD as the most likely to have been impacted by VOCs or metals had such a release occurred and not been fully removed by the soil excavation. The two soil samples were submitted to McCampbell Analytical, Inc. for the required analyses. VOCs were not detected in the soil sample collected for that analysis (B2'-12') and detected metals in sample WTP#3-8' did not exceed common background concentrations in California soil. However, the CVRWQCB expressed concern that with soil impacted by 140 mg/kg TPHmo at 10 feet bsg, there was the potential that groundwater had been impacted by petroleum hydrocarbons due to the close proximity of groundwater to the base of the excavation. In response to the CVRWQCB concerns, AGE collected three grab groundwater samples around the former TPUOFT area on July 31, 2015 for analysis for TPHmo. Laboratory analysis of the three samples did not detect quantifiable concentrations of petroleum hydrocarbons. By email dated September 2, 2015, the CVRWQCB concluded that the former TPUOTF did not currently appear to pose a threat to groundwater and supported a No Further Action Required (NFAR) determination by the EHD. Findings Based on the remedial actions noted above and findings of the various investigations, and with the provision that all information provided to this agency was accurate and representative of site conditions, this agency has determined that the site investigation and corrective action carried out at the former TPUOTF is protective of human health and the environment and that no further actions are required relative to the former TPUOTF.