A large portion of the community of Thompson Falls is currently served by private septic systems, including approximately 560 residential homes and three schools, and this PER update is the third phase of the City’s four-phase approach to expanding the centralized collection system to all lots within the City limits.
The homes served by private systems are often not in compliance with today’s regulations and are beginning to fail. Lot size limitations prevent replacement with compliant on-site systems, and the Sanders County Sanitarian has reported substandard installations. Substandard systems are incapable of reducing nutrients and pathogens to safe levels. This creates a significant human health and safety issue and threatens Montana’s high-quality waters.
The City’s existing sewer system also has deficiencies that need to be addressed. Some of the collection system mains date back to 1948 and are suffering from root intrusion and settling, which can result in increased infiltration and inflow and sewer backups. Approximately 1,300 feet of 12-inch asbestos cement (AC) pipe along the banks of the Clark Fork River needs replacement and approximately 600 ft of additional pipe that frequently plugs needs replacement. Additionally, the Main Lift Station also does not have permanent back up power and poses a potential for system backups and overflows.
In 2018, the PER evaluated alternatives to connect the unsewered area of the City to the central sewer system, as well as address deficiencies in the current wastewater system. If nothing is done to address the deficiencies in the wastewater system, there will continue to be adverse impacts on the environment and human health.
Phase 1 and 2 is in the process of designing and constructing in the summer of 2020 along with addressing the original existing sewer system deficiencies identified in the 2018 PER. The project is anticipated to bid in the summer of 2020 with construction starting shortly after the bid is awarded. The project is anticipated to be completed at the end of 2021.
Currently, the City is in the process of updating the 2018 Wastewater PER with the 2020 PER update. The preparation of the PER update is the next phase of this critical project to protect valuable groundwater and surface water resources in Thompson Falls.
The PER update evaluates Phase 3 and Phase 4 of the collection system expansion project originally developed in 2018. Phase 3 and Phase 4 expand the collection system to the northwest side of the City where they are currently served by private septic systems with these systems often reported substandard installation. This creates a significant human health and safety issue and continues to threaten Montana’s high-quality waters.