City Of Sidney Working On Sludge Mitigation

In 1959-60, the City of Sidney built a two cell lagoon system to handle waste water. One primary cell was used, with infiltration into the second. In 2011 or 12, the State of Montana mandated that the city upgrade the system. A new cell was built in the footprint of the old second cell, leaving the sludge in the primary one to degrade. Biological agents have been used over the years to help with the process, but there is 60 years of accumulation with one to two feet of sludge over 38 acres of land.

Public Works Director Jeff Hintz explained that mitigation of the sludge is the 4th, and final phase, of the waste water project. Initially, because the sludge is excellent fertilizer with high nitrates, it was thought that neighboring farms could use it. However, soil samples revealed an already high nitrogen content in those fields. Trucking thousands of loads of the sludge to more distant farms would be cost prohibitive.

The idea to leave the sludge where it is and farm the property was presented to the EPA and Hintz said they seemed pretty open to the idea. The plan would involve planting alfalfa which absorbs nitrogen well, cutting that and selling the bales. The first couple of crops would probably have a higher than safe nitrate content so those bales would probably be burned. But in a couple of years, there should be nice crop land which could be leased out. The hope is that eventually, irrigation could be added.

The alfalfa plan is estimated to cost well under $1 million versus the $5.4 million dollar estimate to remove the sludge. Hintz said something needs to be done. The cell was drained last summer and now dust and weeds (which have been mowed), are blowing into the new system. Good vegetation is needed to stop the erosion.

Hintz said soil samples were taken two weeks ago, and although he doesn’t want to get his hopes up, they looked promising. An engineering report will be submitted to the EPA and Hintz said it feels promising that they may let the city continue with the project. “I hope they let us carry on with this idea,” he said. “It would be a waste to let it sit there and do nothing. Why not make it a good cash crop?”