Mitigation of Issues Raised during Construction of Trunk Sewer Rehabilitation Project

This paper presents the approach, methods, and challenges for undertaking repairs to York Region’s sanitary sewers. The Regional Municipality of York (York Region) carried out detailed closed-circuit television (CCTV) inspections on the York-Durham Sewage System (YDSS) to assess the rate of inflow and infiltration and to identify sewer sections in need of immediate repair. Based on the inspections, deficiencies were identified at two (2) maintenance holes and fourteen (14) sewer sections that include minor cracks, infiltration, encrustation, and roots and debris in the system. The diameter of the sewers ranged from 20 to 54 inches (525 to 1,350 mm), with a total distance of 1.2 miles (1.8 km). The rehabilitation consisted of spray applied liners for the maintenance holes and installation of localized chemical grout to the sewer sections. These locations were distributed across York Region in three separate cities, with the location of the proposed rehabilitation work occurred within flood plains, high traffic, and environmentally sensitive areas. York Region, Hatch, and associated contractors collectively worked together to mitigate and resolve project challenges and completed the rehabilitation of the YDSS within the prescribed construction timeline.