A Tale of Two Towns - Water Distribution and Treatment Challenges
Warren Martin (Stantec Consulting Ltd.)

Stantec completed water system assessments for two 2 municipalities located in Newfoundland and Labrador. The scope of the assessments included a site visit, operations staff interviews, water distribution modeling, water quality and treatment review which all resulted in infrastructure recommendations for water supply, distribution and treatment.

The Town of Howley has been on a boil water advisory since 2016. Reported issues include low distribution system pressure, low chlorine residuals, aged water storage tank and lack of multi-barrier treatment. This is a small system with an average day demand of 85 m3/day but a large RV park increases summer demand by approximately 35%. Treated water quality has high colour at 56 TCU and extremely high HAAes and THMes at 384 ug/L and 180 ug/L respectively. The report found that very small pipe diameters in the distribution system as small as 50 mm and storage tank elevation was limiting the available flow in the system. The storage tank capacity needs to be increased from 120 m3 to 379 m3. However, water treatment improvements are required first to remove the organics prior to proceeding with the storage tank upgrades to control the organics/DBP issues. Proposed upgrades at the intake, water treatment plant, storage tank, chlorine booster station and distribution system were provided.

The Town of Twillingate has also been experiencing issues with their distribution system and water quality and treatment. Stantec created a hydraulic model of their existing water system and recommendations ranged from additional watermain looping and changes to pump operations. Water quality was examined, and it was observed THMes and HAAes were elevated at 162 ug/L and 170 ug/L respectively. Short- and long-term treatment recommendations were made and ranged from additional sampling and reviewing the existing CT strategy as well as conceptual options for water treatment system