Importance

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Abstract

Apparatus and method for constructing a manhole collar between an existing manhole cone and a precast manhole ring. The apparatus includes a circular slip form tube, tapered from a larger top diameter to a smaller bottom diameter; at least two support arms, radially extending from adjacent the top of the slip form tube for placement on a support surface, such as a road surface, to hold the tube at a selected height relative to ground level within a manhole cone; and a plurality of fasteners for attachment of a precast manhole ring about the exterior periphery of the slip form tube for supporting the ring at a selected height relative to the manhole cone and the roadway surface. The apparatus may include a concrete spill retention ring, placeable upon the top rim of the manhole cone and around the slip form tube to prevent concrete from entering the manhole cone. The method of the invention includes the steps of supporting the slip form tube upon the roadway surface by the arms; fastening the manhole ring to the tube for proper positioning thereof; leveling the tube and ring; and the pouring of concrete about the slip form tube to form a ring-supporting concrete collar between the manhole cone and the manhole ring.

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First Claim