Coquitlam Densification Impacts on Water and Sanitary Sewer Systems

Water Street was retained to provide an assessment of densification on the Coquitlam water and sanitary sewer system following new provincial housing legislation for small-scale, multi-use housing (SSMUH); and transit-oriented development areas (TOA). The assessment focused on evaluating the impacts on the Coquitlam water and sewer system due to SSMUH, TOA, and additional densification of high-density corridors.  These cumulatively increased the City current OCP projection by 60% (+300,000 ca).

The scope included the creation of detailed Bentley SewerGEMS sanitary sewer models for key catchment areas in the City of Coquitlam and updating and model conversion of other catchment models. These models were built using advanced GIS pipe and manhole data, record drawings, and existing flow monitoring information.

Existing water models (for NW and SW Coquitlam) in Bentley WaterCAD were updated with new growth scenarios. The NW model was converted to WaterCAD from Infowater.

To evaluate the impacts of densification, three buildout scenarios were developed based on current development trends and stakeholder input. For each scenario, Water Street analyzed water and sanitary sewer system capacity and fire flow availability to identify infrastructure constraints.  An interesting innovation was GIS lot-by-lot analysis of hydrant access using a hose length calculation routine avoiding private property and other obstructions. Required upgrades were then developed for each development horizon to support long-term infrastructure planning as the City adapts to increased densification