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WRRF Expansion

Big Sky Water Sewer project



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Frequently Asked Questions

Why does the wastewater treatment plant need to be upgraded and expanded?

As the Big Sky population and development grows, so does the need to meet basic needs such as water and wastewater treatment.  Currently, the Big Sky County Water and Sewer District (District) is generating flows and loads that are encroaching upon the existing treatment facility’s rated treatment capacity and reuse and disposal constraints are driving production of a higher quality effluent.  To proactively plan for increased wastewater treatment demand, the District is in the design phase for a Water Resource Recovery Facility (WRRF) Expansion and Upgrade.  This proactive planning allows for the continued development and improvements in the community without disruption. 

What is included in the WRRF Expansion and Upgrade?

The first project entails increasing the average day rated treatment capacity of the WRRF from 600,000 gallons to 910,000 gallons per day.  Additionally, the BSCWSD has made a commitment (upon completion of the expansion) of 500 Single Family Equivalents to address workforce housing, a community-wide identified necessity.  

The second project entails constructing a lift station and pipelines for the Canyon area to benefit from the WRRF expansion.  The project will help eliminate some Canyon Area septic drain fields as well as recharge groundwater.  The net result will improve water quality, address capacity issues due to population growth and increased tourist visitations, and minimize environmental impacts, most notably on the Gallatin River. 

Will you be putting sewage or wastewater in the river?

No, effluent will not be directly discharged to the Gallatin River.  Any treated water used in the infiltration galleries will be the end product of an advanced wastewater treatment process that exceeds Montana DEQ drinking water standards.

What kind of treatment will be used in the upgraded Water Resource Recovery Facility?

Generally, the treatment process will consist of biological nutrient removal, membrane filtration, and oxidation (e.g., ozonation or advanced oxidation (AOP)).  Ozone and other advanced oxidants react with contaminants extremely rapidly (in seconds).  No treatment chemicals will be discharged from the new WRRF. 

What are the benefits of the wastewater infrastructure improvements?

The collective goals of the wastewater infrastructure improvements are to: 

  • Achieve Class A-1 effluent to maximize reuse opportunities.
  • Reduce effluent nitrogen by ~75% and phosphorous by ~95% which in turn reduces the risk for algal blooms in area streams and the mainstem of the Gallatin River. 
  • Increase available single family equivalents (SFEs) to support community demand (both traditional and work force housing) and decrease the risk of a building moratorium. 
  • Protect the Canyon Area’s groundwater (drinking water source) quality. 

What will the project cost and how will it be funded?

The WRRF Expansion and Upgrade is expected to cost approximately $35M and the lift station, force main, and effluent pipeline are anticipated to cost $12M.  These costs will be refined throughout the design phase of the project.   

Pending voter approval in May, an additional 1% resort tax will be enacted to contribute to the two infrastructure projects.  If approved, funds generated from the resort tax increase will be used to pay for 60% of the WRRF Upgrade and Expansion project.  It is anticipated that the District will pay the remainder with a State Revolving Fund (SRF) loan and existing revenue sources for repayment.  The 1% resort tax fund will be used to fund 100% of the lift station/force main costs.

Will this project impact the current sewer rates?

Pending voter approval of the additional 1% resort tax, current sewer rates will not be impacted by the wastewater infrastructure upgrades.

What is the anticipated schedule for building & Completion?

Final design of the WRRF Upgrade and Expansion will be completed by May 2020.  The resort tax vote will be held in May in conjunction with the general election.  Construction of the WRRF is anticipated to begin in December 2020 with Phase I of the expansion completed by June 2022.  The lift station and pipeline project schedule is uncertain and is dependent upon Canyon residents forming a district.   


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