Our firm designed the Town of Arnprior’s original primary treatment plant in the 1960s. In later years, the plant was expanded and secondary treatment was added. As the Town continued to grow, capacity and other issues at the plant required attention. We carried out an update to the Class Environmental Assessment (EA) to identify and address these needs. The public consultation process with the Ministry of the Environment (MOE), Ministry of Natural Resources, and Ontario Power Generation was supplemented by a Project Liaison Committee including senior town management and operations staff, council representation, and the MOE.
Notwithstanding complex geotechnical conditions, the EA analysis concluded that an expanded plant on the current site offered superior cost benefits over a new plant on a new site. The site’s geotechnical challenges, including karstic features and limited bearing capacities, steep bedrock, and significant dewatering requirements dictated customized solutions for each new plant component location. Other constraints requiring innovative solutions included a confined site, no buffer zone to neighbouring residential areas, a prominent location within the community, and several species at risk.
The level of detail included in Phase 3 of the Class EA allowed the project to be considered “shovel ready” for funding initiatives. The ESR’s recommendations included expansion for a build-out population of 11,000, nitrification, upgraded screening, elimination of hydraulic bottlenecks, reduction of primary bypassing, capturing most wet weather flows (up to 59,000 m3/day), secondary bypass flow, a central odour control system, disinfection upgrades, anaerobic digestion, and extension of the outfall sewer to the Ottawa River. We subsequently prepared the detailed design and contract documents for a multi-million dollar construction contract for all of these upgrades. The project has now been successfully implemented and will provide the Town with safe and reliable wastewater treatment for years to come.