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_ PARSONS Soil encountered beneath the site during drilling and remediation activities consists predominantly of silts and clays with a bed of sand and silty sand found at depths ranging from 45 to 75 feet bgs with a thickness ranging from 5 to 30 feet. Additional lenses of sands, silts, and clays are found throughout the site. Groundwater elevations and depth to groundwater at the Site have historically ranged from approximately -48.93 to -22.10 feet amsl and 55.72 to 83.32 feet below top of casing (btoc). Historical groundwater data in the shallow zone indicate the groundwater flow direction is typically to the northwest and the northeast. Historical groundwater data in the deep zone indicate the groundwater flow direction is typically between the east and southeast(Arcadis 2016). 3 FIELD PROCEDURES 3.1 Site-Specific Health and Safety Plan As required by the Occupational Health and Safety Administration (OSHA) "Hazardous Waste Operations and Emergency Response"guidelines(29 Code of Federal Regulations Section 1910.120),and by California Occupational Health and Safety Administration (Cal-OSHA) "Hazardous Waste Operations and Emergency Response" guidelines (California Code of Regulations Title 8, Section 5192), Parsons will prepare a site- specific environmental health and safety plan (E-HASP) prior to commencement of field work. The field staff and contractors will review the E-HASP prior to beginning field operations at the Site. 3.2 Preliminary Field Activities Applicable permits will be obtained from the San Joaquin County Environmental Health Department (SJCEHD) prior to commencing field activities. Parsons will initiate an Underground Service Alert(USA)with the local utilities prior to mobilization. Under Parsons' supervision, a geophysical survey will be completed to mark any utilities near the proposed soil boring locations. USA will contact all utility owners of record within the work areas and notify them of the intention to conduct subsurface work in proximity to buried utilities. All utility owners of record, or their designated agents, will be expected to clearly mark the position of their utilities on the ground surface. A private subsurface utility locator will be sent to the Site to mark underground utilities within a radius of 10 feet around each of the proposed soil boring locations. Equipment to be used to locate utility lines may include ground penetrating radar, electromagnetic transmitters and receivers, and cameras. The required minimum radial clearance distance from 0 to 50 kV overhead electric lines for the drill rig is 25 feet. The proposed boring locations will take this into consideration when marked in the field. When working around guy wires, the minimum radial clearance distances for electrical power will be observed and visibly marked and work barriers or spotters provided. 3.3 Soil Boring Procedures Soil borings will be advanced to groundwater or to a maximum of 85 ft bgs using a drill-rig equipped with eight-inch diameter, continuous flight, hollow stem augers. During advancement, soil samples will be collected at five-foot intervals, beginning at 30-feet bgs, using a steel split-spoon sampler driven approximately 18 inches using a 140-pound hammer that is dropped 30 inches. An attending technician will log cuttings in accordance with American Society for Testing and Materials(ASTM) D-2488 under the direction of a State of California Professional Geologist or Professional Engineer. Soil cores will be screened in the field for the presence of volatile organic compounds (VOC) using a photo-ionization 2