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• • Work Plan for Septic Dralnfield Investigation March 7,2013 8700 Thornton Rd. Project No.1091 Stockton,California Page 2 excavation and approximately 20 cubic yards of hydrocarbon contaminated soil was excavated on December 6 and 7, 2012. The soil was analyzed for acceptance to the landfill. The profile was accepted and the soil was transported to the Potrero Hills landfill near Fairfield, California on January 18, 2013. The permit for the removal of the septic tank from SJCEH is included as Appendix A. The laboratory report for the soil analyses is included in Appendix B. The non- hazardous waste manifest documenting the soil disposal is provided as Appendix C. The hazardous waste tank closure certificate documenting the cleaning of the septic tank is provided as Appendix D. The non-hazardous waste manifest for the septic tank documenting disposal at the Potrero Hills landfill is provided as Appendix E. The excavation was backfilled with clean imported backfill and a new concrete slab was poured to match the surrounding conditions and grades. The purpose of this work plan is to describe methods and procedures for locating the extent and configuration of the septic drainfield and to determine if contaminants have affected soils in the vicinity of the drainfield. Geology and Hydrogeology Based on lithologic data collected from the nearby Former Circle K Store located at 8606 Thornton Road, soils are comprised of clay, sandy silt and fine to medium grained sand. Groundwater was first encountered in this permeable layer. Groundwater is encountered at depths ranging from 28 feet bgs to 37 feet bgs. The depths vary based on the season with the highest elevations occurring during the wet winter months and the lowest elevations occurring in the dry autumn months. SCOPE OF WORK The following sections describe methodologies and procedures for locating and sampling soils in the drainfield. Boring Permit and Buried Utility Location Prior to conducting fieldwork, CES will obtain a soil boring permit from the SJCEH. CES will contract with a C-57 licensed driller to advance the soil borings. CES will mark the general location of the borings in the field with white paint and USA Alert will be contacted to identify any buried public utilities within the site investigation area. If the drainfield is determined to extend offsite, site access to the adjacent property will be negotiated with the offsite property owner.