This project was initiated in response to a large watermain break in 2011 on the primary water supply to the south end of Ottawa. Robinson Consultants Inc. was retained by the City of Ottawa to complete a condition assessment and risk analysis to determine the optimal renewal strategy. The project included the design and construction of 1km of 1220mm watermain, 400m of 305mm watermain by directional drilling, a mobile pump station and temporary bypass pipe, three individual spot repairs, pipe material selection, corrosion protection, wire break monitoring system, tender package, construction staging and watermain commissioning plan, full traffic bypass plans for short term closures of Hunt Club Road, public communications and construction administration and inspection.
The Woodroffe Avenue watermain is a 1220mm transmission watermain that is the primarily supply for Barrhaven, Riverside South and the Village of Manotick, serving a population of approximately 100,000 people. Following the break and subsequent electromagnetic inspection, it was determined that 1km of the watermain had to be replaced. While this watermain was isolated for inspection and replacement, the area was being serviced by a 406mm watermain and booster pump. Since the 406mm watermain could not provide adequate supply for peak-summer demands, an outdoor water ban was implemented by the City. Robinson Consultants Inc. fast-tracked the design and tender package to limit the amount of time that this critical watermain was out of service, as well as the length of the outdoor water ban.
In an effort to add additional supply to the isolated section of 1220mm south of the replacement section, a 305mm watermain was constructed by horizontal directional drilling and open-cut methods. The 305mm watermain was connected to an existing 610mm C301(L) PCCP at the north and to the 1220mm C301(L) at the south. Both of these connections were made using a live taps.
A 1km section of 1220mm C301(L) PCCP watermain was replaced within the project limits. This watermain replacement included new valves and valve chambers, hydrants where required and large services to the Nepean Sportsplex. The watermain design included a full cathodic protection design, including coordination with PURE Technologies for the installation of an acoustic fiber optic cable within the watermain, which is used to record prestress wire breaks in real time. Spot repairs were completed at three other locations, where the initial inspection had identified additional distressed pipes.