Our firm carried out a Sanitary Study to review the general operating condition and capacity of an interceptor sewer in the Alvin Heights area, referred to as the Alvin Heights Pull-Back Sewer, and to assess the impact on the Ottawa Outfall Collector Sewer under both existing and future development conditions.
The Sanitary Study encompassed a large area that included the Alvin Heights and Thorncliffe Village residential developments, Rockcliffe Air Base, National Research Council of Canada, Montreal Road Scientific Campus, Montfort Hospital, and future residential area referred to as the Pace 2000 Lands. The general operating condition of the pull-back sewer was assessed as well as its capacity under both existing and future development conditions. The continued need for the RCAF Pumping Station in the Regional system was evaluated. Performance of the sanitary drainage systems was evaluated in light of the Combined Sewer Overflow (CSO) Policy developed as part of the Region’s Wastewater Master Plan.
In evaluating the performance of the sanitary sewers against the CSO Policy, the XP-SWMM software platform was utilized with real-time sanitary flow data. The flow data was used to establish dry-weather flow patterns via a hydrograph separation exercise, and to calibrate a number of sewersheds to establish a correlation between the model and the monitored sanitary flow data. Once the calibration and validation exercise was completed, simulated sanitary sewer flows for 25 scenarios were generated under existing and future development conditions. Three important criteria for evaluating the alternatives were developed: achieving the CSO Policy performance objective, limiting the flow contribution to the Ottawa Outfall Collector to less than its locally allocated capacity, and constructing the most cost effective option. Recommendations were then proposed for the alternatives that satisfied these three criteria.
We worked collaboratively with the Region’s Environment and Transportation Department and the various groups impacted by the Study to ensure the requirements of the stakeholders were addressed.