Population Growth Drives Need for Expansion and Upgrade

Twenty years ago, the City of Bozeman was at a crossroads regarding the future of its wastewater utility. Rapid growth, combined with uncertainties associated with future regulatory permitting, has made the facility planning process extremely complex. 

Since 2001, we have been assisting the City with discharge permitting and regulatory strategies for emerging nutrient removal requirements.

In May 2006, we completed a wastewater facilities plan that identified specific improvements needed to meet nutrient removal permit requirements and to accommodate the community's rapid growth and increased solids quantities at the facility. 

In 2007, our team began the design of the $54 million nutrient removal expansion and upgrade, which was commissioned in 2012 after two years of construction. While the biological nutrient removal expansion was under design and construction, we assisted the City in the implementation of an innovative operational strategy — phased nitrification-denitrification. The result was a reduction of total effluent nitrogen by 40% and lower than mandated discharge limits, which helped Bozeman comply with more stringent permit compliance requirements for nutrients.

The facility upgrade was one of our first projects completely designed in 3D, which enabled the City to better visualize the end product and offer constructive input at early design stages. 

Throughout construction and commissioning, we partnered with the City and the contractor to successfully resolve several key issues associated with the design, including additional enhancements to the digester gas management system, modifications to the plant hot water heat recovery systems, additional hydraulic improvements to the new bioreactors to enhance scum removal and enhanced oxygen controls for enhanced nutrient removal.  

• 2010 – Admin/Lab Building: Rebid saved money with the American Recovery and Reinvestment Act grant funding and green design architecture.
• 2011 – Phase 1 Improvements: $53M upgrade to the biological nutrient removal treatment facility. Included bioreactors, clarifiers, headworks, ultraviolet disinfection and support processes to meet treatment and capacity requirements.
• 2012 – Digester Control Building: Solids handling improvements re-packaged and rebid from the Phase 1 project to save money. Included digestion, thickening and dewatering.
• 2012 – Water Quality and Permitting: Ongoing sampling and QUAL2K modeling of the East Gallatin River in support of site-specific nutrient variance. Tailored permitting support and negotiations with the Department of Environmental Quality.
• 2017 – Small Works Improvements: Improvements to clarifiers and digesters, and the addition of an emergency boiler. East Gallatin Avulsion: Designed and implemented a repair for the routing of the East Gallatin River back to the Water Reclamation Facility discharge location. Mixing Zone Study: Sampled the conductivity in cross-sections of the East Gallatin River surrounding the effluent outfall and developed a mixing zone study for the Montana Pollutant Discharge Elimination System’s Discharge Permit.
• 2019: We designed the expansion to the City’s solids handling building to address modifications to heating and ventilation within the building. 

Also in 2019, we ran a brewery waste pilot project, which successfully dosed brewery wastewater into the post-anoxic zone to decrease effluent nitrogen levels. The result was 25% to 40% less nitrogen being discharged into the stream. 

In 2020, the City awarded us the wastewater facility plan update that identifies cost-effective means and methods to maintain compliance with Montana’s water quality standards as the City continues to grow. The facility plan will cover a 20-year planning horizon, and will ultimately identify: capital improvements, process optimization strategies, pollutant minimization program elements and long-range permit compliance approaches necessary to attain water quality standards as Bozeman’s population increases.