Home / Mound systems
Mound systems in Pine County, MN
Raised sand systems for sites where a standard drain field will not work.
A mound system is a raised bed of sand and gravel that treats wastewater above the natural soil. It is used where the soil is too wet, too shallow, or too slow-draining for a standard in-ground drain field. Pine County's ordinance counts mounds as a standard (Type I) system design under state rules.
Why mounds are common here
Newer systems and systems in shoreland need three feet of separation between the bottom of the soil treatment area and saturated soil or bedrock. Around river valleys, wet ground, and shallow rock, natural soil often does not offer that much. Raising the field gets the separation back. Our town pages for Sandstone, Willow River, and Hinckley explain the local soil and water-table situations where designers reach for a mound.
The parts that need attention
Most mounds use a pump to move effluent from the tank up to the mound, with floats to control it and a control panel with an alarm. Those parts wear out. Under Pine County's ordinance, replacing a pump, float, alarm, or wiring is minor-component work that does not need a construction permit, as long as the system's capacity, function, and layout stay the same. It still has to be done by an MPCA-licensed business.
If the alarm goes off, cut back on water use and call for service. The alarm usually means effluent is not being pumped out of the tank as it should be.
Looking after a mound
Keep vehicles, livestock, and heavy equipment off the mound and its edges, and keep the grass cover healthy. Do not plant trees or shrubs with big roots on or right next to it. Pump the tank on schedule so solids do not reach the pump chamber or the mound. Pine County's ordinance also keeps mound toes and finish grading out of the public road right-of-way.
Tank rules that protect mounds
The City of Rock Creek requires two-compartment tanks, partly because the second compartment helps keep solids from reaching a mound during high-flow events like laundry day. Elsewhere, ask your designer whether a two-compartment tank or an effluent screen makes sense for your system.
Mound system service
- Pump, float, alarm, and control panel checks and repair
- Mound surface and edge inspection
- Tank pumping on a schedule that keeps solids away from the pump
- Design and installation of new or replacement mounds (permit required)
Read the Point-of-sale inspection guide for the point-of-sale rules and who handles septic where.
Sources: Pine County SSTS Ordinance (2025) definitions (Type I), §5.02.03, §6.02.01, road right-of-way setback · Rock Creek Planning Commission minutes, June 2026
Mound systems: questions
My mound alarm is going off. What should I do?
Cut back on water use right away and call a licensed service provider. The alarm usually means effluent is building up in the pump tank.
Do I need a permit to replace a mound pump?
Not from Pine County, if the work does not change the system's capacity, function, or layout. A licensed business must do it. Local units with their own programs may differ.
Areas we serve
Each town page explains who handles septic rules there.
Other services
Holding tanks
Sealed tanks that store wastewater until it is pumped out.
Frozen septic lines
Winter freeze-ups: slow drains, backups, and no flow.
Septic tank pumping
Routine pump-outs to keep solids from reaching your drain field.