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1CW <br /> SECTION 12 <br /> AERIAL CROSSINGS OF WATER MAINS, RECLAIM WATER FORCE MAINS AND <br /> WASTEWATER FORCE MAINS <br /> 12.01 SCOPE <br /> This section covers the construction of new aerial utility crossings as well as the <br /> replacement of existing aerial utility crossings. The desired methods for constructing <br /> new aerial crossings are: 1) to place them on a utility shelf constructed with a new <br /> bridge; and 2) place them on brackets designed and constructed to hold the utility <br /> adjacent to the bridge. Construction of aerial crossings using concrete pilings for <br /> support has been discontinued at the request of the local drainage and water control <br /> jurisdictional authority. <br /> 12.02 GENERAL <br /> A. There are two industry-accepted methods of constructing aerial crossings: ductile <br /> iron and welded steel. Joints are usually constructed using flanges or push-on <br /> pipe. In the case of ductile iron, flanges are screwed onto the pipe. For steel pipe <br /> all flanges are to be factory welded. No field welding is allowed. <br /> B. Where there is a new or existing utility bridge shelf, the aerial crossing shall be <br /> constructed of flanged or push-on ductile iron pipe. The crossing shall be <br /> constructed in place on concrete cradles. No assembly and then lifting into place <br /> will be allowed for ductile iron pipe. Ductile Iron shall be saw cut only, no torch <br /> cutting is allowed. <br /> C. Where there is a bridge hanger installed for the aerial crossing, steel pipe with <br /> factory welded flanges shall be used. All flanges are to be joined using 304 <br /> stainless steel bolts, nuts and washers. The steel pipe crossing will be <br /> preassembled and then lifted into place onto the hangers. If the total span length <br /> is such that it cannot be shipped without special conditions, the span shall be <br /> constructed in two or more sections having factory-welded flanges on both ends. <br /> 12.03 PIPE <br /> A. Ductile Iron: Specifications for ductile iron utility pipe are given in Sections 1 and <br /> 4 of the standards. <br /> B. Steel Pipe: Steel pipe for aerial crossings shall be the size as shown on <br /> construction plans and shall be in shop-finished lengths. No field cutting and <br /> fitting will be allowed. If no plans are available, it will be specified by the design <br /> 12-2 <br />