All state highway stream crossings, and other locations determined by the developer and/or the district, shall be encased with steel casing. Steel casing shall be of sufficient diameter, size, and strength to enclose the carrier pipe and to withstand maximum highway loading. Sizing and wall thickness of casing is subject to approval by the district. The carrier pipe shall be ductile iron, Class 52, restrained joint pipes unless otherwise approved by the district. Casing spacers shall be installed at each 10 feet of the pipeline. The spacers shall be stainless steel casing insulator, Model-M12-SS by Calpico, Inc., Typ. or approved equal. Sand backfill between the casing and the carrier pipe shall be required. In order to prevent the sand from being washed from the casing, the ends of the casing shall use end seal Model C by Calpico, Inc., before backfill and testing of the pipe are completed. [Res. 735 § 1, 2017.]
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