Final Report - Flathead County, Montana

discussed earlier in this report and improvements will have to be made to increase
conveyance capacities of the West Trunk Line, which serves areas west and northwest
of the WWTF, and to the South Trunk Line, which serves areas south-southeast of the
WWTF. An increase in conveyance capacity will also be needed for the trunk line that
serves the downtown area of Bigfork from the Bay Lift Station to the WWTF. The
increase in conveyance capacity of this section of gravity sewer is not necessarily
needed to facilitate existing or proposed development outside of the current District
boundaries, but it is needed to improve sewer service and reduce District maintenance
costs within the District boundaries. There is very little potential for the addition of new
sewer system users in this area of the District.
The conveyance capacity of the North Trunk Line, as well as the existing lift
stations and force mains serving this area is very good and there is substantial reserve
capacity to serve infill development and areas currently outside of the District. There
are still several sections of 8” sewer main along the North Trunk Line, however, each of
these sections are reported to have slopes greater than 1.0% which greatly increases
conveyance capacity.
Northwest of District: The greatest concentrations of existing septic systems in the
northwest portion of the Bigfork Water & Sewer District, and outside of the District
boundaries in this general area, are in the Mayport Harbor area, the northwest corner of
Holt Drive and along Pine Needle Lane. There is already public sewer available to the
Mayport Harbor area; however, the District reports that very few of the existing
residences have connected to the sewer system. There is no public sewer available to
the northwest corner of Holt Drive or along Pine Needle Lane. Both of these areas
would have to annex to the District and install sewer extensions to serve these areas.
The northwest corner of Holt Drive could be served by a low pressure grinder pump
system or by a gravity collection system with a lift station and force main. A gravity
sewer main extension could be installed along Pine Needle Lane to serve existing and
future residences.
Due a lack of conveyance capacity in the West Trunk Line, as previously discussed, the
District is reluctant to annex any additional users in this general area. There are already
a significant number of undeveloped lots within this portion of the service area that will
generate additional flow to the West Trunk Line and until the capacity of these gravity
collection mains are addressed, the annexation of additional users is unlikely.
South-Southeast of District: The greatest concentrations of existing septic systems
south-southeast of the District are in the Ranch Subdivision, along MT Hwy. 35 to
Woods Bay and along the east lakeshore to Woods Bay. It should be noted that a
significant number of these existing systems along Hwy. 35 and the east lakeshore are
in Lake County.
The Bigfork Water & Sewer District is working closely with existing water and/or sewer
districts in Lake County to provide wastewater treatment system capacity to all or a
large portion of these currently unsewered areas. A Memorandum of Understanding
(MOU) was signed in 2008 by the Bigfork Water & Sewer District, the Greater Woods
Sewage Treatment in the Flathead Basin 16