Growth in the Community of Elmira, Region of Waterloo, Ontario, Canada, has been limited in recent years by insufficient wastewater treatment capacity and capacity constraints within the existing system. Significant extraneous Infiltration / Inflow (I/I) has been experienced within the system, resulting in basement flooding and bypassing of untreated sewage to the receiving stream.

In 1995, Stantec undertook a detailed I/I study that included extensive flow monitoring, house-to-house surveys, and analyses of both dry weather and wet weather flows. The foundation drains connected to the sanitary sewer system were identified as the primary source of I/I. Stantec developed a Pilot Project to estimate potential reductions in the sanitary sewer flows with private side foundation drain disconnection. Results of the Pilot Project were extrapolated and an I/I reduction program, with specific reduction targets, was developed. Since the Elmira WWTP was at capacity and an expansion was required, Stantec proceeded with a holistic look at the entire wastewater collection and treatment system in order to develop a comprehensive Total Solution.