specifications - FAACO - Federal Aviation Administration Contract ...

FTWIC-2235June 2009location and depth of all existing utilities along the proposed route of the duct bank.Changes in direction of runs exceeding a total of 10 degrees, either vertical or horizontal,shall be accomplished by long sweep bends having a minimum radius of curvature of 25feet, except that manufactured bends may be used at the end of the run. Manufacturedbends shall have a minimum radius of 18 inches for use with ducts of less than 3 inchesin diameter and a minimum radius of 36 inches for ducts of 3 inches in diameter andlarger. After the duct line has been completed, a standard flexible mandrel not less than12 inches long, having a diameter approximately 1/4-inch less than the inside diameter ofthe conduit, shall be pulled through each conduit, after which a brush with stiff bristlesshall be pulled through each conduit to make certain that no particles of earth, sand, orgravel have been left in the line.C. Terminate conduit in end bell at manhole entries.D. Stagger conduit joints in concrete encasement a minimum of 6" vertically.E. Use suitable separators and chairs installed not greater than 4' on centers. Band conduittogether with suitable banding devices. Securely anchor conduit to prevent movementduring concrete placement.F. Each single conduit of the duct bank shall be completely encased in concrete. Thethickness of concrete shall be as indicated, but not less than 3 inches on the sides, bottom,and top. The thickness of concrete encasement indicated is the minimum thickness, andmay be increased to fit the actual shape of the trench. Provide reinforcing bars whereindicated.G. Provide two No. 4 steel reinforcing bars in top of bank under paved areas.H. Color of concrete encasement shall be red.I. Duct bank trench shall be backfilled with material free from rocks, paving material, orangular substance larger than that specified for Class 12 material in Section 02224,EARTH FILL CLASSIFICATIONS, at the widest point.J. Notify the Contracting officers representative two days prior to concrete encasement ofthe duct bank and again two days prior to backfill so that the duct bank installation can beinspected for conformance with the requirements of this specification.END OF SECTION16111-7 FTWIC-2034