REGIONAL- Voyageurs National Park, the only water-based park in the national parks system, is a 341-square-mile wonderland of forests, waterways and islands that attracts close to a quarter of a million visitors a year.
To ensure that the park’s waters remain clean and suitable for human recreational activities well into the future, the Voyageurs National Park Clean Water Joint Powers Board (VNPCJPB) has updated its comprehensive wastewater plan for the four access areas bordering the park.
The process began in 2020, with a target date of January 2021 for completion, but various challenges obtaining data for needs assessments and getting feedback delayed its completion by a year.
Developed by engineering firm SEH, Inc., the plan encompasses Ash River Unincorporated Areas, Crane Lake Water and Sanitary District, Kabetogama Township, and Rainy Lake/Rainy River Watershed. It incorporates existing infrastructure where feasible and recommends additional development strategies and system upgrades where deemed appropriate.
Each overall service area was broken down into smaller segments and a needs assessment was performed by SEH considering existing properties and those suitable for future residential or commercial development. Lacking the resources to conduct on-site inspections, SEH relied on a state-recommended alternative mix of soil survey data, government property records, and a review of plat maps to conduct the assessment.
In each of the four service areas, remote and sparsely populated areas will continue to be served by on-site septic systems, as building out the necessary wastewater collection system would be financially prohibitive.
Recommendations for areas with higher population and denser potential development encompass all three phases of wastewater processing, those being collection, treatment, and effluent discharge.
A key collection component to be utilized in all four service areas is low-pressure sewage grinder pumps. These units, installed at each structure, collect wastewater in a chamber until rising water levels trigger a grinder that pulverizes any waste solids. The resulting fine waste slurry is ejected into plastic piping and conveyed by gravity to a larger pressurized plastic forcemain leading to a treatment location.
Estimated costs for recommended improvements include a 30-percent contingency and 25-percent engineering cost. Estimates do not include permanent easements or right-of-way acquisition.
Ash River
The needs assessment determined that there are approximately 81 existing wastewater producing parcels, including seven resorts, and another 47 properties with development potential in two of the three subdivisions of the Ash River Service Area. The third subdivision was not considered as a likely location for development and was not assessed.
A total of 32 existing septic systems were assessed as potentially non-compliant. Those systems will would be replaced or upgraded and properly maintained under the plan.
For the two main Ash River subdivisions, SEH recommends low-pressure grinder pump stations feeding into a centralized aerobic treatment system, as a traditional gravity-based collection would be infeasible due to the high bedrock and water table in the area and the bury depths required. Effluent from the treatment system would be discharged through a soil-based subsurface dispersion system.
The estimated cost for the recommended improvements would be $24.437 million.
Crane Lake
Crane Lake was subdivided into 12 service areas encircling the lake and including its islands. The Crane Lake Water and Sanitary District wastewater treatment system services the most densely populated subdivision, including nine resorts and businesses, with the potential to serve a new national park campground.
There are approximately 200 wastewater producing parcels and 170 properties potentially developable in 11 of the 12 subdivisions.
Across all subdivisions, SEH assessed 66 existing septic systems as potentially non-compliant.
The recommended plan for Crane Lake focuses on the existing centralized low-pressure grinder pump system. The system can be expanded to accommodate future development within the subdivision. An additional alternative for seasonal properties with existing septic systems is to use the systems for preliminary on-site treatment and attach pumps to convey the effluent to the treatment plant for final treatment.
For properties in service areas further away from the existing centralized collection and treatment system, SEH indicated that septic systems with mound treatment systems are likely the most feasible alternative.
The estimated cost for the recommended improvements would be $19.294 million.
Kabetogama Township
Nine subdivisions were established for portions of Kabetogama Township with Kabetogama Lake frontage, eight of which were analyzed for current use and potential development.
The subdivision, including Woodenfrog Campground, Voyageur Park Lodge, Moosehorn Resort and six other resort properties, referred to as K2 in the report, is partially served with a centralized collection and treatment system. Subdivision K4, which includes Northern Lights Resort, already has a collection and treatment system.
Development potential is more restricted in the area, as SEH identified 28 potential development properties. There are approximately 219 existing wastewater producing parcels.
SEH recommends connecting a subdivision adjacent to K2 by grinder stations to K2’s existing treatment system, which would have to be expanded to accommodate the increased flow.
Subdivision K4 would remain decentralized. Four subdivisions are recommended for centralized treatment via low-pressure grinder station pumping systems with a centralized treatment system and subsurface discharge, and two nearby resorts also could connect to the system.
SEH recommends that the subdivision at Slate Point be divided into two smaller centralized collection and treatment areas. Grinder stations and a low pressure forcemain would be used for collection and a medium-sized onsite sewage treatment system would be used for treatment.
The estimated cost for the recommended improvements would be $30.836 million.
Rainy Lake/River
Three subdivisions were established for the Rainy Lake/Rainy River Watershed area, which includes 581 wastewater producing parcels and 553 potential development properties. Subdivision Three was further divided into two sections.
A total of 56 septic systems across all subdivisions were determined to be potentially non-compliant.
An existing and planned sanitary sewer extension along County Rd. 71 would be used for a grinder pump system serving one subdivision and Grassy, Jackfish, and Grindstone Islands. Another subdivision would be served in similar fashion by an extension of an existing centralized system down County Rd. 96. Wastewater flow from these areas would be preliminarily treated at centralized stabilization ponds before being fed to a mechanical treatment plant operated by North Koochiching Area Sanitary District. Other areas would remain decentralized and served by septic systems.
The estimated cost for the recommended improvements would be $30.356 million.
Public comment
Public review and comments for the Comprehensive Wastewater Plan are open until Feb. 23. To review and provide public comments to the comprehensive plan, please visit the project website at https://www.sehinc.com/online/namakan, where a PDF copy of the plan is available to download. The plan provides more detail of the service areas and subdivisions, including an extensive set of maps and line-item budgets.
The VNPCWJPB will meet at 10 a.m. on Wednesday, Feb. 23 at the St. Louis County Public Works Facility located at 9558 Ashawa Rd. in Cook. The meeting will also be open to virtual attendees through Microsoft Teams meeting or by call-in at 872-242-7640, conference ID 998 975 921#.