CLAIREVILLE ‘MISSILE’ SOLVES NPS 42 HDD INSTALLATION DIFFICULTY IN TORONTO

摘要

At 1,185 metres (3888 ft.), one of the longest HDDs on the Enbridge Greater Toronto Area (GTA) project in 2015 was the NPS 42-inch crossing under the Claireville Reservoir and Finch Avenue. Originally planned as two bores, the proximity of the exit points made it clear that a single HDD would be more appropriate. Because of the length of the crossing and the environmental requirements of crossing the reservoir, it was also one of the more critical crossings to be directionally drilled on the project. The majority of the bore length was in shale bedrock with no surface casing utilized. As a result the Finch Ave HDD and the Clairveille Reservoir HDD were combined in the design stage to make a single, long HDD where an intersect was considered. Due to the critical nature of this crossing, it was the first HDD on the project to be constructed. Construction started in early January of 2015. Difficulty was encountered during pullback of the NPS 42 product pipe and Mears, the HDD contractor, designed an innovative telescoped pullhead to assist with the pipe installation. This paper will discuss the crossing design, the difficulties encountered, and the innovative solution dubbed the ‘Clareville missile’ which solved the installation problem. With a total of 14 significant HDDs and 3 Direct Pipe installations the GTA project was a significant project for Enbridge Gas from a trenchless respect.