City to repair failing sections of wastewater pipeline
The city of Whitefish is set to begin work on three substantial water and wastewater projects.
City Council March 21 approved construction contracts with four firms for work on water projects for a total amount of $348,000 and wastewater projects for a total of $814,000.
Whitefish has a wastewater collection system with over 58 miles of sewer main and portions of the system are more than 100 years old. Those sections experience a large volume of clear water flow — primarily due to the abundance of surface and groundwater sources, according to Public Works Director Craig Workman.
Workman said the extraneous flow, known as infiltration and inflow, can exceed the capacity of the collector pipes and reduces the performance of the city’s wastewater treatment facility.
Council authorized a contract with Planned & Engineered Construction in the amount of $497,700 for pipeline rehabilitation and Guildner Pipeline Maintenance, Inc. in the amount of $316,550 for manhole rehabilitation work.
An infiltration and inflow mitigation study in 2006 identified over 18,500 lineal feet of sewer main that was in need of repair. A project in 2011 to rehabilitate several thousands lineal feet of main was effective at reducing inflow and infiltration, but analysis performed in 2013 indicated that additional work was needed.
The results of the analysis yielded three specific drainage basins as the priority — Birch Point, City Beach and River Lakes.
Workman said Birch Point and City Beach are some of the oldest sections of the collection system and clear water has been found to be entering the system through old pipes. River Lakes is a new system, he noted, however infiltration and inflow has been discovered in the area through poorly installed manholes.
The project includes the rehabilitation of about 5,000 linear feet of sewer main and about 35 manholes.
The city is currently designing upgrades to its wastewater treatment plant in response to the latest discharge permit from Montana Department of Environmental Quality. The new permit includes discharge limitations that will require the wastewater treatment plant to remove ammonia and nutrients, as well as nitrates.
Workman said the upgrades to comply with the new limitations will be costly and it’s in the city’s best interest to minimize the infiltration and inflow prior to finalizing a new plant design.
“The completion of this project will minimize the [inflow and infiltration] entering the collection system, reducing operation and maintenance costs of the system and likely lower the cost of the new wastewater treatment plant,” Workman said.
The bids for the project came in below estimates. The city originally budgeted just over $1 million for the work.
Grants from the state Department of Natural Resources and Conservation and the Montana Treasure State Endowment Program will provide $625,000 in funding for the project.
City Council also approved a contract with Sandry Construction in the amount of $348,700 for work on Lion Mountain and the Columbia Avenue bridge.
Work on Lion Mountain will construct a water main extension between Highway 93 and Lion Mountain Loop Road to provide better water pressure at the higher elevations west of State Park Road.
“This need has been recognized over the years and became more urgent following the Council approval of the preliminary plat for the Tamarack Ridge subdivision,” Workman said. The construction will also allow the city to abandon the Mountain Park lift station.
The Columbia Avenue Bridge water main replacement project has been planned for several years and will re-establish a missing link in the water main system, noted Workman.
The project includes replacing a broken water main that hangs beneath the bridge. The project came in about $50,000 below estimates.