Water Street developed the sanitary sewer master plan for servicing of the 580 ha Silver Valley area in Maple Ridge which is expected to grow from a current serviced population of 6,000 to over 15,000 at buildout.

The work included creating a calibrated sewer model that included the existing sewer system, current and future development. Sanitary unit residential base flow and inflow and infiltration loads were derived from wet and dry weather flow monitoring of four pump stations in the service area. Demand assignments were based on the OCP zoning densities and calculated PWWF and RDII loads. Modelling and analysis was completed used Bentley SewerCAD and ESRI ArcGIS.

The scope included:

• Development of actual and design rates for base sanitary flows, groundwater infiltration (GWI), and rainfall derived inflow and infiltration (RDII)
• Flow testing and rating of existing pump stations
• Addressing operation and maintenance upgrades required
• Recommended a revised servicing strategy and capital plan