Springfield Lake Wastewater Servicing Study and Concept Design
Devin Bell, Joshua VanAndel, P.Eng., CAMP (Stantec)

Stantec has been working with the Halifax Water to develop wastewater servicing alternatives to the existing separated wastewater system servicing the residential community of Springfield Lake. Due to the hilly terrain around the lake, the existing population of approximately 1500 people are serviced by 12 pumping stations PS as well as a dedicated wastewater treatment facility WWTF.

Halifax Wateres Infrastructure Master Plan has identified the existing WWTF as a candidate for decommissioning and the wastewater flows redirected to a nearby trunk sewer. Halifax Water requested that the existing cascading seriese of PSs be reviewed to see where PSs could be removed from the system. The various options presented to Halifax Water were optimized to provide the lowest environmental impact, minimize the capital costs and life cycle costs of the infrastructure upgrades.

A field-monitoring program was undertaken in 2023 to monitor flows throughout the existing cascading seriese of PSs. System data including set point levels, flows, pump status and existing linear infrastructure were obtained from Halifax Water and were used to aid with the hydraulic model calibration.

The current system was examined to identify the location of a primary PS, to replace the existing WWTF, and an optimal route to convey the flows to the nearby trunk sewer. The 12 PSs were reviewed for potential bypass and elimination using deep gravity sewers, considering a combination of conventional trenching and trenchless technologies. Eight of the PSs could be eliminated, however, financial life cycle costings found that only six would provide a net positive return over the life cycle of the infrastructure.

A Construction Phasing plan was also prepared, looking to balance the disruption time, use of resources and manage the risks and uncertainties associated with this complex project. The Construction Phasing plan also included a decommissioning plan for the existing WWTF.