For the second time in two months, a short section of above-ground pipe burst at a biodigester near Waunakee, discharging thousands of gallons of animal waste.
Meanwhile, the biodigester operators said Wednesday they were told by a consultant last week of a fix that probably would have prevented both releases.
“We were evaluating the engineering proposal and preparing a recommendation to present to the DNR and Dane County,” said Jim Ditter, CEO of PPC Partners, which owns the Clear Horizons biodigester.
About 20,000 gallons spilled onto the ground at about 4 p.m. Monday, said county lakes and watersheds director Kevin Connors, who visited the site Tuesday. Workers stopped the breach within 15 minutes, and the manure flowed into a retention basin without reaching waterways outside of the biodigester property on Cuba Valley Road, Connors said.
“Fortunately they had people on the site this time and we didn’t have as big a mess as we did last time,” said Josh Wescott, chief of staff to Dane County Executive Joe Parisi.
The Clear Horizons facility has been scrutinized since Nov. 24 when 300,000 gallons spilled and at least some flowed a mile away to reach Six Mile Creek, which leads to Lake Mendota.
Biodigesters produce electricity and reduce the nutrients in dairy manure that farmers spread on fields as fertilizer.
Those nutrients make their way into rivers and lakes. In Madison they have contributed to algae blooms, unpleasant odors and bacteria-tainted water that forces beach closings.
‘Order placed today’
Ditter said spills on Nov. 24 and again on Monday appear to have happened the same way — an equipment vibration or shift in the soil fractured a fitting on a short length of curved pipe leading from a pump house to underground lines that feed the digesters.
The Nov. 24 spill was far larger because it happened at 11 p.m. Manure backwashed out of the digester tank for roughly six hours until an employee arrived for work in the morning. Alarms and monitoring devices failed to activate, the plant manager said at the time.
The Clear Horizons facility features three 1.25 million-gallon digester tanks surrounded by protective berms. But both ruptures occurred at a pump house 200 feet outside the berm.
On Wednesday, hours after the county executive’s office brought the second spill to light, the company announced it had a fix for the pipe malfunctions.
“Ground settling or slight pipe movement caused susceptible pipes to fail at the elbow,” spokesman Leo Maney said in a statement. “Clear Horizons is immediately implementing corrective actions to install flexible connectors at the elbows of these pipes to prevent future failures.”
“It cost approximately $650 for each flexible elbow and we have identified 20 elbows that need replacing,” Ditter said in an email to the State Journal on Wednesday. “The order was placed today.”
The company also is evaluating electronic safety controls and making plans to add monitoring devices that would help isolate ruptures and shut down the system in the event of a problem, Maney’s statement said.
As livestock operations in Wisconsin continued to grow in 2013, about 1 million gallons of manure was spilled, more than in any year since 2007, state Department of Natural Resources records show. The DNR responds to about 50 spills each year.
The Nov. 24 Clear Horizons spill and another 300,000-gallon discharge on Feb. 5 at the UW-Madison’s Arlington Agricultural Research Station were two of the four largest spills in the last 15 years, a DNR database shows.
The State Journal reported in December that there were many similarities between the large spills at the UW-Madison research station and Clear Horizons.
The UW-Madison pipe rupture happened at 3 a.m. when no employees were present. It continued for hours before employees arrived at work in the morning. An unknown amount of manure eventually reached the Yahara River.
The break occurred in a short section of above-ground pipe similar to the rupture point at each of the Clear Horizons incidents. Vibrations from a pump broke a fitting on the pipe.
UW-Madison responded by building a berm to channel any future spill into a lagoon, installing a $3,000 automatic shutoff valve, and replacing a short length of old chain that broke. For years, it had held the pipe steady when a pump kicked on.
A call for safeguards
“It doesn’t take much runoff to cause a lot of algal growth, so incidents like these suggest that all manure digesters should be required to install measures like automatic shutoff valves that will kick in when a pressure drop is detected and berms to reduce the risk of manure running into nearby streams, rivers and lakes,” said Shahla M. Werner, director of the Sierra Club’s Wisconsin chapter.
The Madison-based Clean Lakes Alliance urged the company and the DNR to ensure proper safeguards.
“We cannot play Russian roulette with our lakes,” the alliance said in a statement. “The gamble is too great.”
Before the Monday incident, Clean Horizons was already scheduled to meet Thursday with county officials to discuss last year’s spill.
Until their statement Wednesday, the digester operators hadn’t answered questions Parisi raised in November about whether they have adequate staffing and equipment, Wescott said.
In a letter sent Tuesday, Parisi requested that Clear Horizons “thoroughly review and modify” its current operational plan, review of staffing levels, procedures, safety features and “most critically — whether the most effective personnel resources and expertise are being utilized.”
Reports on the November spill have been forwarded to DNR enforcement staff, but no determination on any fine or other action has been decided, agency spokesman Bob Manwell said.
No fish kills were reported after that spill. Area farmers and contractors worked for days to pick up the manure and spread it on farm fields, county officials said.