Coxwell Bypass Tunnel—Project Update Mid-Construction

Abstract

The City of Toronto (Toronto) has developed a comprehensive Wet Weather Flow Master Plan to address degraded environmental conditions in the Lower Don River. The Plan includes an integrated system of tunnels and storage tanks to intercept these wet weather flows, along with key infrastructure upgrades at Ashbridges Bay Treatment Plant (ABTP). It is referred to as the Don River and Central Waterfront and Connected Projects (DRCW Project). The DRCW Project consists of five substantial infrastructure projects that, working together, will significantly improve the water quality in the Lower Don River, Taylor-Massey Creek and along Toronto's Inner Harbour. Toronto engaged Black & Veatch, in association with R.V. Anderson Associates (BV/RVA) and North Tunnel Constructors (JayDee Canada, Michels Canada, and C&M McNally Tunnel Constructors) to deliver the Coxwell Bypass Tunnel (CBT) project, which is one of three tunnels that form the backbone of the DRCW Project. The CBT is a fully deep-rock tunnel 10.5 km long by 6.3 m finished diameter and includes five deep-rock WWF storage shafts, 11 deep-rock drop shafts and deaeration/adit tunnels, and two at-grade sewer connection structures. On average, the five WWF shafts are 20 m inner diameter by 50 m deep. The CBT was tendered in late-2017 and awarded in early-2018. Construction is underway with a Tunnel Boring Machine in a single pass with a precast concrete tunnel lining. This paper provides an update on construction of the CBT, and as of January 2021, the project is approximately 60% complete.