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Traditional Lagoon system: Two part system
- 1. Plumbing from the house: pipes with clean outs that carry wastewater to the lagoon.
- 2. Lagoon: shallow body of wastewater where final treatment occurs and reintroduction of wastewater into the environment occurs.
A lagoon must be nearly watertight.
- NDEQ allows a maximum seepage of 1/8 inch per day.
- The bottom and sides of the depression are lined with a watertight material such as bentonite clay or a synthetic liner specifically made for this purpose.
- A lagoon must be surrounded by a 4-foot high fence with a locking gate and sign.
- There must be a 2 X 2 ft concrete pad in the center of the lagoon directly below the opening of the outlet pipe to protect the integrity of the liner.
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Lagoon size is determined by the number of bedrooms, and the annual evaporation, and precipitation rates for the geographic region.
- The majority of loss to the environment occurs through evaporation to the air.
- There must be a minimum of 2 feet between the bottom of the lagoon and groundwater. The liquid depth of a lagoon should be maintained between 2 to 5 feet.
- There must be a depth marker near the center of the lagoon.
- Maintain a minimum of 1 foot of freeboard.
What Happens in the Lagoon?
- Evaporation reduces the liquid volume of wastewater, returning water vapor to the environment. Solids settle to the bottom and form sludge.
- Algae and anaerobic microorganisms help treat the wastewater.
Regulations
- To construct and use a domestic wastewater treatment lagoon, NDEQ state regulations require a 3-acre minimum lot size. Counties may have more stringent regulations than the state, but never more lax.
- Some counties do not allow lagoons - check local zoning restrictions.
- NDEQ regulations state that lagoons must be at least 50 feet from property lines and 100 feet from drinking water wells.
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