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Where gravityeffluent sewers or pressure effluent sewers cross a water line,the orien tation shall be perpendicular to the water line,unless otherwise approved by the Engineer.All piping materials (water and sewer) shall be solvent welded Schedule 40 (watertight)or heat-fused HDPE.The minimum vertical separation between water and sewer at crossings is 18 inches. The minimum horizontal distance between parallel water and sewer pipes is 10 feet pipe-to-pipe. When the separation cannot be met or the sewer must cross above the potable pipeline,a 20-foot length of pipe for each(water and sewer) shall be centered(where possible) at the crossing point to maximize the distance between joints.The sewer line shall be located below the water line unless specifically approved by the Engineer.In all cases,piping within 10 feet of the crossing point shall be bedded in compacted sand for uniform support.The piping shall be installed and bedded to prevent direct contact(minimum 6-inch vertical separation). Special connectors, adapters,primers, glues, or solvents may be required where the material, size, or construction of the pipe changes within the system.Drawings of any approved"as built" changes or conditions noting pertinent dimensions,pipe types, distances,and grades shall be provided to the Engineer by the Installer. 5.3 Tanks Materials All pre-cast concrete tanks shall be constructed to the manufacturer's standard specifications with the custom modifications shown in the plans.If the custom modifications conflict with the manufacturer's standard specifications,the Designer must be notified immediately in writing. Since the tanks (as specified)are an integral part of the design,no substitutions will be allowed. Workmanship The Site shall be adequately prepared by the Installer for placement of the tanks by the tank manufacturer.All tanks shall be set on a level, stable base to minimize the potential for differential settling.Any water encountered within the excavation shall be pumped and distributed away from the area to a location that will not impact other construction activities(e.g.,the drainfields) or water quality. The excavation shall be sufficiently dewatered to enable placement of the tank bedding material to the grades specified,as well as to enable the placement of the tank(s)themselves.Where 2-piece tanks are set,the excavation shall be prepared to provide a minimum clearance of 6-inches on all 4 sides of the tank(or as specified by the tank manufacturer)to facilitate visual inspection for leaks and installation of an exterior bentonite seal.All sealing, grouting, and coating shall be completed prior to backfilling. After placement and sealing, all tanks shall be tested in the field for water tightness.Two-piece tanks shall be backfilled to a point 3 inches below the field seam and the tank filled with water to no more than 6 inches above the seam to check for obvious leaks. Where pipe penetrations are located below the seam,pre-testing for obvious leaks is advised. CAUTION: Filling of the tank(s)shall be monitored closely to assure that no more than 6 inches is allowed to accumulate above the seam. Construct a form with 1-inch x 6-inch lumber to provide for placement of bentonite along the seam around the outside of the tank.It is recommended that bentonite be placed around each pipe penetration to provide secondary protection against leakage.The remaining tank sidewall shall be Valley—Albany,OR East Salem Seventh-Day Adventist Church I P&S Doc:2023240054 East Salem Church PS.docx November 2023 I Page 5