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TRACY WWTP—TASK M TOS MDWORDID WELL INSTALLATION WOW" Waste Handling Procedures Liquid and soil waste generated by the well installation will not require special handling. No existing soil or water quality sampling data indicate that conditions have been adversely impacted. Soil waste created during drilling will be retained on the W WTP property. Cuttings at Sites A and B will be spread on the ground near the boreholes. Cuttings from Site C will be moved to inside the fenced area and placed in a location to be determined by the City. Liquid waste,if any,will be treated at the plant. Health and Safety Procedures Fieldwork will be conducted in accordance with the Health and Safety Plan for Field Activities prepared for the site by CH2M HILL.CH2M HILL personnel and subcontractors performing fieldwork specified in this Work Plan will be required to read this health and safety plan prior to performing fieldwork on site. Onsite personnel and visitors will be briefed each day regarding Health and Safety procedures and required to sign the Health and Safety log. In addition,visitors to the site will be asked to read the Health and Safety Plan prior to being in the immediate vicinity of the site activities. Monitoring Well Design Figure 9 shows the schematic of the planned well construction. For consistency,the wells will be constructed in a similar manner to the existing holding pond monitoring wells. Final decisions regarding the length and interval of the well screen will be made by the onsite Professional Geologist. Monitoring wells will be designed and completed in accordance with ASTM standards D6286. The wells will be constructed as follows: • Well riser and screen will be 4-inch,flush-threaded schedule 40 PVC. • Well screen will have 0.020-inch machine slotted openings. It will be 20 feet in length and installed at the bottom of the well. • The end cap will be flush-threaded. • Filter pack will be No.3 Lonestar Monterey Sand,or an equivalent 8 x 20 sand. Filter pack will be emplaced as the augers are withdrawn from the borehole. Filter pack will be surged after emplacement and additional sand added so that the top of the filter pack extends at least 3 feet above the upper well screen interval. • One foot of fine-grained sand(No.60 or similar)will be added to the top of the filter back to reduce the potential for migration of the bentonite seal into the filter pack. • Bentonite pellets will be added to a depth of 2 feet If the bentonite pellets are above the water table, potable water will be added to the pellets for hydration. • Cement grout will be emplaced from the top of the bentonite seal to 1 foot below grade. The grout will consist of Type I or It Portland Cement blended with 5 percent powdered bentonite. Oct"31,1W7 6