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I , I I I I I I I I I I I I I I I I I I rods to connect the valves to the pipeline. The rod length, diameter and the number of rods all need to be determined in the project design phase. The bends should be secured in place by large masses of concrete (thrust blocks) between the pipeline bend and the existing, undisturbed trench side. The size of the concrete mass must be determined during the final design process to ascertain the best dimensions. Additionally, all the bends should be secured by connecting rods from the bends to the pipeline. 3) HIGHWAY CROSSINGS: The pipeline, as proposed, is to be placed under 1-70 at two locations. This will require jacking a carrier pipe through the highway embankment, welding the sections of steel water pipeline and placing them into the carrier pipe. 4) RIVER CROSSINGS: River Crossings will present a potential for future scour and degradation of the riverbed which, if not designed properly, will cause local scouring to develop and the pipeline to fail. Furthermore, the bottom of the trench may not provide a good, stable foundation for pipeline support. The construction of the pipeline will require concrete encasement in proposed river crossings and placement below the potential scour depth for the Colorado River and the provision of stable, firm support foundations for pipeline. 6.5 Pipeline Construction Method and Considerations Pipeline construction will raise special considerations which will effect the project cost and schedule. The considerations associated with the construction of the subject pipeline are mainly due to adverse subsurface conditions, the presence of structures and obstructions, and permitting requirements. For construction consideration purposes the 10,421 long pipeline has been characterized by five representative cross-sections. The construction considerations and proposed methods which may be employed during construction for each of these sections are summarized as follows: Connection to Existinl! Pine - Junction boxes will be required to provide housings for connections between the new 42-inch steel pipe and the existing concrete pipe. The connection should include pressure surge valves, shut off valves, diversion units and air reI ief valves. A segment of the 24-inch concrete pipe will be removed from the existing pipeline and replaced with a similar length segment of steel pipe. The 24-inch steel pipe will be equipped with a 24-inch valve and a tee incorporated within its length. A 42-inch valve will be connected to the tee and all connections will be rodded and blocked according to design 36