ARCHIVED REPORTS_2019 SOIL MGMT PLAN (JULY-REVISED)

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22 February 2019 AGE-Project No. 14-3154 Page 8 of 12 The work will be performed following the procedures outlined in Section 6.0 of the EMMP. Based on the quantity and results of the data collected during the April 2018 excavation and removal activities at Parcel B, AGE proposes to collect verification samples on a grid- pattern at 50-foot intervals (total of 7 samples) on Parcel A. If the dimensions of the excavated area are larger than anticipated, additional verification samples will be collected accordingly. Additional sampling will be performed as approved by the EHD. Verification samples will be analyzed for the constituents listed in Section 6.4 of the EMMP. Excavated waste materials will be stockpiled and sampled to characterize the waste for disposal following the procedures listed in Section 6.5 of the EMMP. Except for the DI WET analytical method, stockpiled waste samples will be analyzed for the constituents listed in Section 6.5 of the EMMP (the DI WET testing is not considered necessary since the excavated materials will be removed from the property for offsite disposal and onsite reuse of the materials will not be considered/evaluated). All excavated waste materials will be removed from the subject property and properly disposed. Additional analyses of the stockpiled waste materials will be performed as required by the receiving waste disposal facility. All work associated with the excavation and waste removal activities will be documented in a Verification Report. The report will include a description of work performed and the results of sampling. Conclusions and recommendations will also be included in the report, if applicable. The report will be reviewed and signed by a California Certified Engineering Geologist. To evaluate and characterize sample data collected from Parcel A, the findings and results will be compared to the following appropriate environmental screening levels: the June 2018 Human and Ecological Risk Office (HERO), Human Health Risk Assessment (HHRA)-Note 3 screening levels for industrial/commercial properties, published by the California Department of Toxic Substance Control (herein referred to as DTSC-SLs); to the May 2018 Environmental Protection Agency (EPA) Region 9 Regional Screening Levels for industrial soil (herein referred to as RSLs); and to the January 2019 San Francisco Bay RWQCB Environmental Screening Levels (TPH only) for commercial/industrial shallow soil exposure (herein referred to as ESLs). Additionally, water data, if collected, will be compared to the July 2014 State of California Maximum Contaminant Levels (herein referred to as MCLs). Additionally, sample data will be evaluated and compared to site-specific background concentrations that were developed utilizing data collected from Parcels A and B. Specifically, arsenic will be evaluated using the site-specific background concentration of 8.6 milligrams per kilogram (mg/kg). The DTSC has determined that background concentrations of arsenic in California soils are commonly high, ranging anywhere from 0.6 mg/kg to 11 mg/kg -Background Concentrations of Metals, a Progress Report, Geological Services Unit, Glendale (Arsenic in California Soils). The site-specific background concentration of 8.6 mg/kg for arsenic is the maximum concentration detected in soil samples collected from Parcels A and B. Background concentrations are listed in Table 1.