CONCRETE PIPE Box Culvert Installation and Handling According to the Ontario Concrete Pipe Association Concrete Pipe Installation Pocket Guide, September 2010 edition, the following is recommended for the installation of box culvert sections: “Precast box units should be constructed as specified in the [project] contract. The foundation must be firm in-situ soil, or compacted backfill to provide uniform support for the full length and width of each box unit. The foundation on each side of the box unit, for a minimum distance equal to the inside width of the box unit should be at least as stable as the foundation directly below the box unit. Bedding should not be placed on frozen earth. “The maximum particle size for bedding should not exceed 25 mm in diameter, unless the bedding layer is at least 150 mm thick, in which case the maximum particle size should not exceed 40 mm in diameter. “Bedding requiring compaction should be placed in layers not exceeding 200 mm in thickness, loose measurement, and each layer should be compacted before a subsequent layer is placed. The type of equipment used must be suited to the material to be compacted, degree of compaction required, and space available. “The surface prepared to support box units should have a minimum thickness top levelling course of uncompacted Granular A or fine aggregates.” For installation of boxes in parallel, ASTM C1577 states that multicell installations are allowed if there is “a means of positive lateral bearing by continuous contact between the sides of the adjacent boxes. Compacted earth fill, granular backfill, flowable fill, or grouting between the units are considered a means of providing such positive bearing.” PAGE 14 LAFARGE PIPE eMANUAL