A component of the anaerobic digester at the Viroqua, WI, wastewater treatment facility clogged resulting in a spill from the digester.
The clog, which occurred Feb. 18 coincided with problems with the control system of the digester leading to the alarm system not responding in time to notify staff before the spill.
It is estimated 2,000 gallons overflowed onto the ground, much of which ended up retained on the asphalt surface by large snow piles. This snow and liquid was removed from the asphalt area and returned to the treatment system.
Some of the spill left the asphalt area and went down the bank toward the intermittent stream, an unnamed tributary to the Springville Branch of the Bad Axe River.
This part of the spill was mostly retained by a silt fence on the bank of the stream where it was cleaned up. Some of the spill did reach the stream, estimated at less than 100 gallons.
“The city of Viroqua is committed to protecting the environment and providing a high level of wastewater treatment services,” said Sarah Grainger, city engineer, in a statement. “The city has already made adjustments to the control system to ensure sufficient notification of staff before a possible spill from the digester. In addition, a plan of action is in place to prevent overflows if plugging was to reoccur.”