The City of Boise owns and operates the 4,225 acre Twenty Mile South Biosolids Application Site located southeast of Kuna, ID where biosolids are beneficially recycled to grow corn, alfalfa, and winter wheat.

What we do

The City of Boise produces an anaerobically digested Class B biosolids from their two wastewater treatment plants that use advanced secondary treatment with ammonia removal.  The biosolids are used locally on their city-owned property, Twenty Mile South Farm, to grow crops that generate revenue for the City.  Today, the city conducts all activities at the farm except for the wheat combining.  The City manages all other farming activities from the tillage to the crop selection and planting to harvest. Boise wastewater provides service to approximately 282,400 citizens.

The City invests in a long-term sustainable biosolids program that has cradle-to-grave management focus by:

  • Returning nutrients and organic matter to the soil and revenue to the City’s wastewater fund to offset the cost of wastewater treatment.
  • Eliminating the reliance on and cost of commercial fertilizer by using a locally made, renewable resource.
  • Dialing in an agronomic biosolids application rate and sampling plan to ensure that nutrients stay within the root zone and don’t harm groundwater.

Boise aims to have all new city buildings at zero net energy by 2030. Biosolids program manager Ben Nydegger said, “We will not ever have a power bill, if everything works out how it was designed.  We’re not off the grid, we’re simply consuming power from one side and putting power back in the grid on the other side.” 

Twenty Mile South Farm, Boise ID

The new 14,000 square foot office and maintenance facility is the first commercial Zero-Net Energy facility in the state of Idaho. The energy efficient aspects of the building, including a 56 kW solar array on the roof, are expected to offset $24,000 in power costs annually. The “extra” cost of building this Zero Net Energy facility is expected to be recouped through energy savings in just 14 years.

Twenty mile south farm Boise ID