Collingwood Stormwater Technology Pilot

The Town of Collingwood will conduct a pilot project to reduce inflow of stormwater into the sanitary sewers and stormwater infrastructure from private properties during critical stormwater events. They will install 75 networked sump pump systems in neighbourhoods at high risk from basement flooding, while removing non-compliant connections to the sanitary sewer and redirecting discharge to Low Impact Development (LID) features. Data from the networked sump sumps will feed into a sewer flow monitoring program which was recently conducted as part of the Town’s sanitary sewer master planning study. The environmental objective of the pilot is to reduce stormwater runoff by 50% during 24-hour rain events in the target areas. The LID installations will include two permeable parking lots at an institutional and a commercial site, as well as three rain gardens, ten internet-based home roof cisterns and the 75 smart sump pump installations at residential sites. The pilot project will develop a continuous hydrologic simulation model integrating data from the LID installations, climate projections, and GIS-based decision support system tools for water management. These findings will be used to develop an analysis of how community interventions could be scaled up within the municipality, and whether they would significantly reduce the extraneous inflows to the sewage system. The Master Servicing Plan for the Water and Sanitary Sewer System will quantify the scale of inflow and infiltration to the sewer system, and develop a long-term strategy to address inflow (unauthorized residential connections or unidentified cross connections) and infiltration (groundwater seepage). Future recommendations for scaling up the pilot project through a broader lot level incentive program will focus on the Pretty River and Black Ash Creek drainage systems. In the spring of 2016, during a storm surge, Collingwood’s wastewater treatment plant (WWTP) released untreated sewage into South Georgian Bay with a negative environmental impact on the Collingwood Harbour which is used for swimming, fishing, and boating. Research by other municipalities indicates that inflow and infiltration from private properties may account for a significant portion of the storm event day flow rates that WWTPs receive, which can be seven times greater than the average flow rate. The study aims to identify key factors for WWTP influent spikes during recent winter-spring snowmelt periods as well as quantify their magnitude to develop a solution. The pilot project complements the Town’s approved Master Servicing Plan, which identifies inflow and infiltration as a major issue under public works. The need for pro-active planning on stormwater management is also reinforced by the Town’s Development Charges analysis from 2014 which highlights expected increases in wastewater treatment requirements. Greenland has consulted with several municipal bodies in the development of the project, including the County of Simcoe, Hagersville, and the City of Welland, and anticipates that the project model would be broadly replicable in other municipalities, and offer significant knowledge value on how to improve stormwater management at the community level. General lessons will be shared through the University of Waterloo’s Intact Centre on Climate Adaptation. (Project description from original funding application)