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i S E C O R - Ms. Devra Lewis April 15, 2004 Page 10 Delta Gateway Apartments will be sent out prior to remedial activities. The RWQCB and SJCEHD will be notified of the scheduled assessment work 48 hours prior to drilling. Access Agreements and Permitting. SVE well permits will be obtained from the San Joaquin County Environmental Health Department (SJCEHD) prior to initiating work. Additionally, access agreements with the City of Stockton Redevelopment Agency and the New Delta Gateway Apartments will be obtained prior to work. Horizontal Soil Borings and SVE Well Installation. Six horizontal borings will be drilled to depths of approximately eight to ten feet beneath five apartment buildings, depending on depths of utilities, shown on Figure 2. The soil borings will be drilled using a horizontal directional drilling rig to construct a continuous borehole using excavated entrance and exit pits. A small diameter boring will be initially drilled and guided to the exit pit using an electronic beacon that is attached to the drill bit that sends a radio signal to a hand held surface unit. Access into the apartments will be required to guide the drill bit underneath the apartments. A minimal amount of biopolymer drilling fluid, which will minimize the damage to the formation adjacent to the borehole, will be used to lubricate the drill bit and remove soil cuttings to the surface. After the drill bit has reached the exit pit, a 6-inch diameter drill bit will be connected to the drill rods in order to ream the hole to the required diameter. A 2-inch diameter high density polyethylene (HDPE) blank pipe with a Schumasoil 40 micron porous polyethylene filtered well screen and grout traps filled with sand connected at each end of the screen will be inserted into a 5-inch diameter carrier casing. Additionally, tremmie pipes will be placed within the carrier casing for sealing and grouting the blank sections of HDPE pipe. The carrier casing will be attached to the end of the drill bit and the pilot hole will be back reamed to the six-inch diameter. The carrier casing will be pulled through the borehole following the drill bit, and the screens will be positioned beneath the apartments. By using the carrier casing, damage to the blank HDPE pipe and Schumasoil screen caused by friction and tensional forces, as well as clogging of the screen with soil, will be avoided. After the carrier casing is installed, a hypochlorite solution will be pumped into the HDPE pipe, filling the area between the screen and the carrier casing in order to develop the screen interval. The hypochlorite solution will effectively dissolve the drilling fluid and mud cake on the borehole wall, leaving the formation with minimal damage. The carrier casing will be attached to a backhoe or bull-dozer tractor and removed from the borehole. After removal of the carrier casing, bentonite chips will be inserted behind the grout basket and hydrated with water using a tremmie pipe. The remaining borehole will be filled with grout using a tremmie pipe. Connection to Remediation System. After completion of the SVE wells the wells will connected to conveyance piping to the remediation compound and hooked up to the remediation system. Soil and Water Disposal. Soil cuttings generated during drilling operations will be temporarily stored onsite in California State Department of Transportation (DOT)-approved 55-gallon drums and/or sealed roll-off bin pending characterization and disposal. A four to one composite soil sample will be collected for soil profiling and will be analyzed for the following: total petroleum hydrocarbons as gasoline (TPHg), total petroleum hydrocarbons as diesel (TPHd), and total petroleum hydrocarbons as motor oil (TPHmo) by EPA Method 8015M; volatile organic compounds (VOCs) including fuel oxygenates by EPA Method 8260; semi-volatile organic compounds (SVOCs) by EPA Method 8270; and total metals by EPA Method 6010. A licensed disposal contractor will remove soil cuttings to an appropriate disposal facility. Water generated during equipment cleaning will be temporarily stored in DOT-approved 55-gallon drums pending transport by a licensed disposal contractor to an appropriate disposal or treatment facility. All drums will be stored in a secure location on the site (fenced compound or lockable cargo container). Stockton Parcel 2A:Work Plan for Pipeline Abandonment, Removal,and Soil Excavation and SVE Well Install