WCW24

The Town of Lynn Lake is a remote community of 579 people in northern Manitoba known for its mining and premier sport fishing in the province. The Town's water supply infrastructure was originally constructed in 1955-56 by the local mine to utilize the West Lynn Lake as a raw water source and supply drinking water to both the Town and the mine. No treatment of raw water was provided at the time except for chlorination. A Water Treatment Plant (WTP) building was constructed in 2003 but did not include a treatment system. Due to limited funds, only the building and reservoirs were constructed, and some upgrades to the existing pumphouse were implemented. Between 2010 and 2012, the Town solicited and commissioned a water treatment system consisting of greensand filtration followed by membrane filtration. Shortly after, the treatment system experienced multiple operational issues and equipment failures resulting in the treatment equipment going completely offline. Untreated raw water was chlorinated and stored in an underground concrete reservoir and distributed via the Town's recirculating distribution system. The treated water did not meet the provincial drinking water standards and the Town was put on a boil water advisory in October 2012. In 2020, Stantec was retained to undertake a feasibility study addressing future growth requirements, review alternative raw water supply sources (groundwater vs surface water) and develop/design an appropriate water treatment system to lift the boil water advisory. Groundwater and alternative surface water sources were evaluated, but the only viable option was to continue drawing surface water from West Lynn Lake. Raw water is characterized by high organics (7 to 13 mg/L TOC), color (30 to 60 TCU), iron (0.25 to 1.1 mg/L), low turbidity ( 1 to 3.0 NTU) and very low total alkalinity of 8 to 13 mg/L. Based on technical and economic factors, a dissolved air flotation (DAF) followed by gravity filtration was identified as an appropriate and cost-effective approach to meet the challenges of the raw water quality. A bench-scale study was completed to confirm the effectiveness of the DAF/gravity filtration process including optimal operating conditions and identifying appropriate treatment chemicals and their dose. Utilizing a collaborative approach with the Town, Stantec developed a design that included selective re-use of existing infrastructure, maintaining water supply to the Town during the upgrades/construction, and implementing a DAF/gravity filtration process to meet the drinking water requirements and lift the boil water advisory. The project was delivered within the available budget of $6.4 M and achieved substantial completion on November 3rd, 2023, despite supply chain issues during the COVID-19 era. The Lynn Lake WTP provides a new beginning for the Town as they plan to extend services to promote local mining activity, and residents have seen a significant improvement in their potable water quality. The paper showcases the planning, process design and construction challenges for a small remote community that has struggled with providing the basic amenity of providing clean drinking water to its residents for over a decade.