The City of Saskatoon retained Associated Engineering to provide engineering services for a major raw water pump station and pipeline. Following the design, the City with Associated Engineering utilized a request for proposal approach in order to retain a contractor for completion of the 1500 mm (60") diameter, coated steel, river crossing pipeline. This pipeline connects the City's new river intake and pump station structure on the east side of the river, to the City's existing 1500 mm (60") diameter raw water supply line on the west side of the river which serves as the primary water supply main to the Avenue H Water Treatment Plant. Isolation valve chambers are located at each side of the crossing at the tie-in locations.
Following a review of multiple proposals involving different construction methods, the City selected Hamm Construction to complete the crossing based on their proposed "isolation by coffer dam" installation method. Regulatory approvals were then obtained, and construction was completed in the summer and fall period of 2010 with Associated Engineering providing engineering services during the construction.
Hamm Construction used a two stage crossing approach involving east and west side coffer dams, dewatering, pipe installation, and coffer dam removal. Rock breakwaters, silt curtains, dewatering filter bags, and interlocking concrete mats were strategies used to manage the river environment by mitigating erosion, and to lessen turbidity loading, meeting regulatory requirements.
The project is an example of a successful team approach used to complete a challenging construction project involving an aggressive schedule, stringent regulatory requirements, and unpredictable river flow conditions.