City of Toronto Mimico Creek Watermain Crossing
The City of Toronto has utilized CIPP watermain to line it’s watermain since 2002 as an alternative to traditional open-cut replacement. The city has expanded it’s use of the technology over the past 16-years to grow to the largest CIPP lining program in North America, rehabilitating over 40km a year. While projects often are in residential, commercial or industrial areas the City also looks to rehabilitate mains that are in less traditional areas such as railway, highway and waterway crossings. One instance of this less traditional method was the rehabilitation of a watermain that had failed under the Mimico Creek in Etobicoke.
The 12” cast iron watermain had cracked and washed out the surrounding soil and gabion baskets, exposing the watermain. Due to the severity of the break the watermain as isolated and shutdown until it could be rehabilitated. Due to the limited access, difficult sites conditions and severity of the break the City, along with their Consulting Engineer WSP, deemed that the best solution was to structurally rehabilitate the pipe with CIPP lining. The project was designated as an emergency repair and contracted out to FER-PAL Construction Ltd to be completed in the summer of 2018.
Before construction could occur, an environmental assessment was required as an area would need to be cleared to access the watermain. The assessment determined that an area could be cleared without disrupting the native trees to the area, including several black walnut, willows and Siberian elm trees. There was a large amount of Poison Ivy located in the area that was required to be removed prior to construction. Lastly silt bags and clear stone gravel were stationed around the work area as the area was saturated due to its location.
Three points of access would be needed in order to properly line the watermain. The first pit was located within an easement at the top of the escarpment on the west side of the creek. The second pit was located where the existing 90-degree bend was located. The last was at the far north end of the Mimico Creek walking path. During the time of construction, the walking path that was used for access was closed to the public. This was the only disruption to the public for the length of the project.
Once the excavation of the access pits was complete, the pipe was cut into and cleaned. Following cleaning, the watermain was inspected via a CCTV inspection. Upon reviewing the video from the line, a circumferential break was observed underneath the creek as well as a large crack along the vertical stretch of pipe. Due to their size and location of these breaks it was necessary to address the failures within the watermain in order to prevent infiltration of water as well as ensure the resin used to cure the liner was contained. In order to do this six separate Hammerhead Point Repair systems were installed within the watermain (see attached picture). Five separate patches were required to seal the elongated crack along the main while a separate sleeve was used to repair the circumferential break underneath the creek.
Upon the installation of the Point Repair system, FER-PAL installed an Aqua-Pipe CIPP liner in two consecutive stretches, curing them using pressurized hot water. Following the curing of the liner it was CCTV’ed and inspected by the City’s consultant before being reinstated, chlorinated and placed back into service.
Following the lining of the pipe the area was cleaned and restored in the areas disturbed by construction activity. The last stage of the project is to insulate the areas of the watermain that were exposed when the watermain failed.