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ST. BARBARA CATHOLIC SCHOOL TASK 2 75-24272-01 <br />DIOCESE OF ORANGE SEPTEMBER 12TH, 2024 <br />SANTA ANA, CA BID & PERMIT SET <br /> <br />CONDUIT 260111 - 8 <br />3.4 UNDERGROUND DUCTBANK INSTALLATION <br />A. Install top of duct bank minimum 24 inches below finished grade. Adjust depth to avoid <br />interference with gravity flow systems of any kind. Maintain minimum 12 inch clearance <br />between duct bank and any gravity flow system. <br />B. Duct lines shall have a continuous slope downward toward manholes and away from buildings <br />with a pitch of not less than 4 inches in 100 feet. Changes in direction of runs exceeding a total <br />of 10 degrees, either vertical or horizontal, shall be accomplished by long sweep bends having a <br /> minimum radius of curvature of 25 feet, except that manufactured bends may be used at ends <br />of short runs of 100 feet or less, and then only at or close to the end of run. <br />C. Terminate conduit in end bell at manhole and pullbox entries. <br />D. Use suitable separators and chairs installed not greater than 4 feet on centers. Band conduit <br />together with suitable banding devices. Securely anchor conduit to prevent movement during <br />concrete or slurry placement. <br />E. Provide minimum 3 inch concrete cover at bottom, top, and sides of duct bank. Refer to <br />Trenching section for additional information. <br />F. Provide two No. 4 steel reinforcing bars in top of bank under paved areas. <br />G. Encase non-metallic primary and secondary feeders, telephone, fire alarm communications and <br />data conduit installed underground 2 inches or larger in a concrete or 2 sack slurry duct bank <br />unless noted otherwise in the Contract Documents. Space the external surfaces of conduit <br />within a bank a minimum of 3 inches apart except that sound, telephone, data and <br />intercommunication circuits contained within non-metallic conduit shall have a minimum <br />separation of 12 inches from any light or power circuits that parallel them within a bank. Use <br />appropriate manufactured plastic spacers to insure the minimum required concrete or 2-sack <br />slurry coverage. All concrete or slurry duct power banks shall contain a yellow warning strip <br />12” above ductbank. Refer to Division 02. <br />H. Numbers and sizes of ducts shall be as indicated. Depending on the contour of the finished <br />grade, the high-point may be at a terminal, a manhole, a handhole, or between manholes or <br />handholes. Manufactured steel 90-degree duct bends shall be used only for pole or equipment <br />risers, unless specifically indicated as acceptable. The minimum manufactured bend radius <br />shall be 18 inches for ducts of less than 3-inch diameter, and 36 inches for ducts 3 inches in <br />diameter 48 inches for ducts or greater in diameter unless noted otherwise in the Contract <br />Documents. Long sweep bends having a minimum radius of 25 feet shall be used for a change <br />of direction of more than 5 degrees, horizontally or vertically. Both curved and straight <br />sections shall be used to form long sweep bends as required, but the maximum curve used shall <br />be 30 degrees and manufactured bends shall be used. Ducts shall be provided with end bells <br />whenever duct lines terminate in manholes, pullboxes or handholes. Duct line markers shall be <br />provided at the ends of long duct line stubouts or for other ducts whose locations are <br />indeterminate because of duct curvature or terminations at completely below-grade structures. <br />In lieu of markers, a 5-mil brightly colored plastic tape not less than 3 inches in width and <br />suitably inscribed at not more than 10 feet on centers with a continuous metallic backing and a <br />corrosion resistant 1-mil metallic foil core to permit easy location of the duct line, shall be <br />placed approximately 12 inches below finished grade levels of such lines.