The Pressure District (PD) 7 Elgin Mills Road Project was initiated in response to increased demand for water necessitating reinforcement of the water transmission supply grid in York’s Pressure District (PD) 7. The project was comprised of approximately 2 kms of 600mm CPP watermain following Elgin Mills Road in Richmond Hill and serves to connect York’s existing 600mm watermain at Enford Drive in the west to York’s existing 750mm watermain at Bayview Avenue in the east. This stretch of watermain overcame numerous technical challenges and resulted in a noteworthy accomplishment. With one single 720m drive, COLE successfully designed and orchestrated the longest curved microtunnel in North America.
This was achieved using an Earth Pressure Balance Microtunnel Boring Machine (MTBM) launched at Bayview and jacking 1800mm pipe in a continuous 24 hour / 7 day per week operation. The CPP watermain installation included the crossing of three TRCA regulated tributaries, a CNR double track crossing, crossing of the York Durham Sanitary Trunk Sewer (YDSS), two jack and bore installations and two (2) tunnels with total length 900m installed by Earth Pressure Balance MTBM method. Challenging ground conditions included artesian and perched water in variable soil types. PTTW, groundwater control and disposal were factors. Connections to existing pipes involved tapping live and interconnecting midblock to the local municipality’s distribution system. Proactive vehicular and pedestrian management, planning and controls are additionally cited for the success of the project.