Advancing Resilient Wastewater Infrastructure While Preserving Natural Resources

The City of Columbia Falls faced a critical need to improve its wastewater infrastructure to reliably meet Montana Pollutant Discharge Elimination System discharge permit requirements, protect public health, and sustain growth while safeguarding the Flathead River. Aging collection system assets, hydraulic and treatment bottlenecks, and increasing development pressure created urgency for a coordinated, proactive solution that would improve system performance today while positioning the community for the future.

HDR partnered with the city to translate its wastewater facilities plan into a practical, phased program of improvements aligned with the American Rescue Plan Act funding requirements. Phase 1 addressed immediate risks within the collection system, including replacement of a constrained 8-inch sewer main in the Hilltop neighborhood with a 12-inch main, rehabilitation of lift station No. 5, and targeted electrical and controls upgrades. These improvements reduced system vulnerabilities, improved reliability, and strengthened conveyance capacity.

Phase 2 focused on treatment performance and regulatory compliance at the wastewater treatment plant. Our team designed the expansion of the existing bioreactor to transition from a 3-stage A2O process to a 5-stage Bardenpho process by adding post-anoxic and post-aerobic zones. This upgrade enhanced biological nutrient removal for nitrogen and phosphorus, key components to protecting the river and meeting discharge limits, while preserving the city’s ability to accommodate future demand. Early treatment performance data shows substantial improvements in effluent quality: 

• Average effluent total nitrogen is 6 pounds per day, compared to the permit discharge limit of 37.1 pounds per day. 
• Average effluent total phosphorus is 0.76 pounds per day, compared to the permit discharge limit of 4.6 pounds per day. 

The exceptional performance gives the city more flexibility to manage capacity amid ongoing development pressures.

Our team also provided end-to-end support, including capital improvements planning, permitting coordination with the Montana Department of Environmental Quality, SCADA integration, construction administration and commissioning. This holistic approach enabled the city to move efficiently from planning through implementation, minimizing risk and maximizing funding eligibility.

By combining technical rigor with a clear understanding of regulatory and community priorities, we delivered a solution that addresses immediate wastewater challenges and builds a resilient, adaptable system for decades to come, helping Columbia Falls grow with confidence while protecting one of its most valuable natural resources.