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15 September 2020 Project No. 18-4357 Page 3 of 4 JANUARY 2019 AdvancedGeo An Employee -Owned Company �. Chromium and lead were detected at maximum concentrations of 89.3 mg/kg and 7.07 mg/kg, respectively. Chromium concentrations were consistent with the other samples collected at the site and the STLC results for chromium ranged from 0.069 mg/I to 0.098 mg/I. Chromium STLC results were significantly below the hazardous waste level of 5.0 mg/I and lead was not detected at TTLC levels that required STLC analysis. The chromium and lead concentrations were significantly below DTSC-SLs. 3.0. WASTE DISPOSAL On 11 December 2018, LD Transportation LLC and Instrat Incorporated of Rio Vista, California, transported and disposed of approximately 20 yards of non -hazardous soil excavated from the site. The waste removed from the site was transported and disposed at Recology Hay Road Landfill in Vacaville, California. A copy of the non -hazardous waste manifest documenting waste disposal is included as Appendix B. On 19 February 2019, Atlas Environmental Solutions transported and disposed of approximately 1,360 pounds (2 drums) of hazardous soil excavated from the site. The waste removed from the site was transported and disposed at US Ecology in Beatty, Nevada. A copy of the hazardous waste manifest documenting waste disposal is also included as Appendix B. 4.0. CONCLUSIONS AND RECOMMENDAITONS The investigation area on the property has been assessed and a substantial volume of TPH-impacted soil has been removed from the site (20 yards of non -hazardous soil and 1,360 pounds of hazardous soil). Additionally, confirmation soil samples have been collected and analyzed in the impacted locations. The vertical extent of impacted soil is defined as well as the horizonal extent (Figure 4 and Revised Site Assessment Report). In an approximately 2,000 square -foot area, twenty-two (22) soil samples collected between depths of 2 and 5 feet bsg were analyzed for TPH and metals. Nearly all of the TPH impacted soil was removed from the site even though concentrations were all significantly below environmental screening levels. The responsible party has gone above and beyond the regulatory requirements, at considerable expense, to assess and remediate the investigation area. It's AGI's professional opinion that no additional assessment or confirmation soil sampling is necessary in the investigation area. Therefore, AGI recommends the site be issued a No Further Action letter. In an email dated 25 March 2019, EHD staff stated that the remedial requirements have been met and a No Further Action letter would be issued (Appendix C).