The Kalispell City Council awarded a contract on Monday for the first section of pipe in an estimated $14 million, multiyear sewer project.

The $175,000 contract for LHC Inc. will involve a 480-foot section of plastic sewer main that will run under the U.S. 93 bypass south of U.S. 2. The city determined it would save money to finish that portion before the state resumes construction on the bypass this summer.

This would be the start of a major project called the West Side Sewer Interceptor. It’s a 7.2-mile pipeline that would relieve the system from material flowing from west-side neighborhoods. It would also allow the system to accommodate more development in one of Kalispell’s fastest-growing areas.

“We’re going to try and get as much existing flow off of Trunk Line A as we can,” said Keith Haskins, the city’s senior civil engineer.

Trunk Line A is the central sewer main in Kalispell. It starts on U.S. 93 near the intersection with Meridian Road and winds down to the wastewater treatment plant near Kalispell City Airport. Much of that line is original clay pipe and has been in service for nearly 100 years. 

Development in Kalispell has grown slowly since recession-era building slumps in 2010 , 2011 and 2012. According to a report from the city planning department, the city issued 269 building permits in 2014, up 12 from the previous year. But the value of those projects was about $1 million less than 2013 construction.

Still, much of that development occurred “upstream” of the majority of Trunk Line A. That includes residential subdivisions along Three Mile Drive and commercial development along  U.S. 93 North. With future development trends pointing to the northwest parts of town, talks of an interceptor line began.

The project began in earnest in 2009 when the city expanded its Grandview Lift Station, a major station on the north side. With that project, the city made an agreement with the Montana Department of Environmental Quality on a trigger system to move on the West Side Interceptor.

The triggers relate to pumping capacity of the Grandview station. For instance, at 80-percent pumping capacity, the city would begin designing the interceptor. At 95 percent, construction must begin and at 100 percent, the city would have to stop issuing building permits until the new line is complete.

According to data from the city, the capacity at Grandview peaked at 53 percent last year.

A more recent study in 2012 looked at the capacity in Trunk Line A. The city looked at a bottleneck point near Meridian Road and Seventh Street East. The study found that at peak flow, it was at 54 percent of its total capacity. An additional 39 percent was not used but allocated to undeveloped lots for future use.

The flow is measured in equivalent residential units, or ERUs, which measure developments relative to the typical sewage output of a home. Today, the peak flow of Trunk Line A runs at about 1,212 ERUs with a total capacity of about 2,245.

After the 2012 study, the city created another set of project triggers with the state based on Trunk Line A. At 70 percent flow at the bottleneck area, the city must complete designs for the West Side Interceptor. At 75 percent, funding must be secured and at 80 percent, construction must start. At 85 percent, building permits must stop.

The line still sits at about 54 percent. The trigger plan had to be approved by the Department of Environmental Quality because it’s a deviation from standards.

“Right now, we’re OK with that deviation,” Haskins said. “I think it’s a matter of three to five years.”

The West Side Interceptor project is proposed to be built over that time. Along with the small section of pipe approved Monday by the City Council, design work has been ongoing. The city contracted with the engineering firm Robert Peccia and Associates on the project.

According to city reports, the design work so far has cost the city $150,000.  

The overall project will be funded by sewer impact fees — one-time charges for new development. 

There are new development projects in the works that will not only bring in impact fees but also use up remaining ERU capacity in Trunk Line A.

Haskins said that regular development adds about 100 ERUs to the system. Larger projects, such as the planned 28-acre Spring Prairie Phase 4 retail center planned south of Costco, can add around 400 ERUs.

Kalispell City Manager Doug Russell said that the plan is to seek a special revolving loan from the state Department of Environmental Quality and make yearly payments with impact fees.

“We should be able to pay for the West Side Interceptor” with impact fees, Russell said.

For a single ERU, the wastewater impact fee is $5,757. That fee, along with the water service impact fee, was increased a bit in 2013.

This year, Haskins said that the goal is to work on the project design and begin negotiating with landowners. The city will have to purchase land and negotiate easements with property owners for the preferred route.

The aim is to have everything designed, negotiated and ready to go when those construction triggers are met. The overall project will come in sections, so long as development remains steady and the impact fees continue to flow.

“We feel that’s really doable,” Haskins said. “The only question is that if there’s a major housing bust.”

Reporter Matt Hudson may be reached at 758-4459 or by email at mhudson@dailyinterlake.com.