Contractors had until 4 April to apply for prequalification for the 6.5km long South End Sewage Rock Tunnel in Sudbury, Ontario with final tender submissions due just two weeks later on 19 April.
Discussed for the last six years after capacity was reached and future developments had to be suspended, the US$18.6M tunnel will run through the south end of the town in the form of a tee with two additional branches for collecting flows. The tunnel will allow the city to eliminate six sewage lift stations.
The northern Canadian city is steeped in the history of nickel mining, with many operations still ongoing, so the excavation method chosen by the successful contractor is likely to be drill and blast to take advantage of jumbos and scoops from their existing inventory. Project documents call for expertise in rock excavation, scaling, rock bolting, concrete and concrete lined inverts. The project includes three shafts; Yale, Burwash and Green, plus 18 cased dropshafts for ventilation. Experience is also required in reinforced concrete drop structures, directional drilling, jacking and boring, as well as demolition, dewatering and sheet piling.
In a presentation to the city council to update on progress, sewer and water engineer Allan Sweetman described how three options had been considered to address the sewerage capacity problem. These were to upgrade existing infrastructure, expand the existing network or the rock tunnel across the network. Following an environmental assessment in 2001, the tunnel option was chosen by a previous council based upon minimised disruption, operating cost, long term costs and excess capacity for future, growth despite its higher initial cost of nearly US$5.4M more than the cheapest option. The current council now has to progress the project using the city budget and 36.68% of total project costs to a maximum of US$6.9M from Ontario’s Millenium SuperBuild Program.
Sweetman said current plans were to award the tender by May, with the construction to get underway in June. The 3.5 year construction period should be completed by December 2008.
