Number of fields in Dunn County used by septic haulers now down to fewer than 120 per year
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By LeAnn R. Ralph
MENOMONIE — Although the number of fields initially approved by the Wisconsin Department of Natural Resources in Dunn County for septic haulers to land spread sludge was 400, that number is now down to fewer than 120 per year.
Neil Koch, a retired hydrogeologist and a resident of the Town of Menomonie, spoke at the Dunn County Planning Resources and Development Committee’s November 20 meeting about the land spreading of septic tank sludge.
There were 400 sites that the DNR approved for land spreading of septic tank sludge, but 150 of those sites were not suitable because the percolation rate is more than six inches per hour, Koch said.
A fast percolation rate means that there is a greater chance of the groundwater becoming contaminated.
Twenty years ago, the DNR agreed to remove the unsuitable sites from the approved list, Koch said.
Koch noted that he had recently contracted to have his septic tank pumped, and that the waste from the septic tank was taken to the Menomonie wastewater treatment plant, which charges a fee of $75 for treating the wastewater and the sludge.
Koch said he was asking Dunn County to write a letter to the state of Wisconsin asking that the land spreading of septic waste be banned.
Michigan has banned land spreading of septic waste but has made some adjustments so that if the source of the septic waste is too far from a municipality that will accept the waste, it can still be land spread, he noted.
Dunn County has one aquifer to provide groundwater, and the state Legislature must look at ways to protect the groundwater, Koch said.
DNR
Two representatives for the DNR were available on-line at the PR&D committee to answer questions and one representative attended the meeting in person.
Peter Carlson, a wastewater specialist and septic coordinator for the West Central Region, said that he could act as a resource and provide information for the PR&D committee.
Ben Hartenbower, a water resources engineer with the DNR who works with surface water effluent limits for point sources, also was on-line.
Lis Osborne, a resident of Menomonie, is the regional non-point source coordinator with the DNR who attended the meeting in person.
Osborne read an e-mail message from Steve Warner of the DNR, who works with land application management plans.
120 sites
In 2021-2022, the DNR rescinded numerous septic sites in Dunn County, and there are 120 sites that are approved today, although even if a site is approved, that does not mean the site is used, Osborne read from the e-mail message.
Some septic hauling businesses maintain backup sites that have not been used for five or 10 or 20 years, she said.
The actual number of fields that are used is less than 120 sites per year, Osborne said.
The DNR is working statewide to pare down approved lists and is abandoning and rescinding previously-approved sites. In six counties, 30 businesses were audited, and many of them had voluntarily abandoned some or all of the fields they had used, she said.
The DNR is cataloging currently approved sites in a database, which is an extensive effort. Wastewater management is acquiring funds to continue the digitization process. The project is large and involves 5,700 approved sites in Wisconsin, Osborne said.
Businesses rely heavily on the wastewater treatment plants of municipalities to dispose of septic tank waste. In many counties, only a small percentage is land spread, and the remainder is taken to wastewater treatment plants, she said.
Many of the wastewater treatment plants return the treated sludge to farm fields where the biosolids are land applied. In rural areas, there are fewer municipal wastewater treatment plants. Many areas may have limited facilities to accommodate the septic tank waste, Osborne said.
In some areas, land spreading is the only option available. The natural resources code encourages the spreading of treated septic waste, Osborne said.
Numbers
Diane Morehouse, county board supervisor from Menomonie and a member of the PR&D committee, asked if the proportion of septic systems is known that use wastewater treatment plants as opposed to those that are land spread.
The amount of septic waste accepted by wastewater treatment plants could be reviewed, but some of that could come from outside the county or the state. What has been land spread in 2023 could be determined, said Carlson, the wastewater specialist and septic coordinator for the West Central Region.
Morehouse said she would like to see the statistics for 2023.
Hauler
Lewis Bjork, of Lewis Bjork Septic and Lewis Bjork plumbing out of Menomonie, also addressed the PR&D committee.
Whether the septic waste is taken to a wastewater treatment plant or is land spread directly, a portion of the septic waste is going to end up on the landscape, he said.
Septic tanks are required to be pumped every three years, and when they are pumped, the sludge and the scum occupies one-third of the tank’s capacity, Bjork said.
The contents of the septic tank must be removed, because if the tank fills up to the point where it goes out into the drain field, the drain field will fail, he said.
A septic tank is an anaerobic environment. The size of the septic tank depends on how many people are using the septic system, which is determined by the number of bedrooms in the house. For every bedroom, it is assumed that two people are using the septic system, Bjork said.
Each person is assumed to be generating 50 gallons of wastewater per day, so a three-bedroom house would be generating an estimated 300 gallons per day. The regulations are based on a “worst case scenario,” so the 300 gallons is multiplied by 1.5, so the design flow for the septic system would be 450 gallons, he said.
“Wastewater treatment in Wisconsin is really good,” Bjork said.
A 900 gallon tank would be assumed to be taking in 450 gallons over a 24-hour period. The solids will sink, and the scum will rise to the top. The wastewater coming out of the septic tank that goes into the djainfield contains nutrients and viruses, he said.
Treatment vs. land application
When the septic tanks are pumped, the hauler must do something with it — take it to a wastewater treatment plan, haul it out of state, or land-apply it, Bjork said.
The City of Menomonie’s wastewater treatment plant will treat the septic waste for viruses and other pathogens, and then the water will be returned to the river or some other surface water. Every wastewater treatment plant follows the same process, he said.
People have probably noticed the blue trucks in Menomonie from the wastewater treatment plant. The trucks are taking the sludge and scum to the storage tanks out by the glass plant, Bjork said.
At a certain time of the year, the city contracts to land spread the sludge and work it into the soil. The sludge then becomes nutrient for plants, he said.
The wastewater treatment plant can only take in so much. The plant must also process wastewater from the City of Menomonie and from UW-Stout, and after a heavy rain, there is an upsurge of water, too, Bjork said.
When the wastewater treatment plant is not accepting the contents from septic tanks, then there is no option if it cannot be land spread, he pointed out.
Chippewa and Eau Claire will not take waste from septic tanks. “They do not want it. They do not want to charge for it. They do not have the staff or the facilities,” Bjork said, adding that he sometimes has the ability to take the septic tank waste to the wastewater treatment plant in Bloomer.
Land application is not free. The septic waste is difficult to land apply. It must be applied at the right amount, with an adjusted pH level and an adjusted temperature. It cannot be over applied, he said.
Bjork noted that he started working in the septic business for Todd Sinz in 1995 and that he also is a certified soil tester and a master plumber and is licensed to drill wells, too.
Banning the land spreading of septic tank waste was tried in Dane County, and it did not work. It will not work in Dunn County, he said.
Every year, septic haulers must report every gallon they have hauled to zoning and to the DNR, Bjork said.
“We are going in the right direction. The equipment is getting better,” he said.
Instead of each truck hauling 10 tanks per day, the haulers now do three or four per day, Bjork noted.
DNR regulations
Lime is used with the septic waste to control the pH along with viruses and pathogens. The DNR regulations have always been there. In the last five years, there has been more contact with the DNR, more e-mails messages from the DNR and more continuing education, Bjork said.
Land applying is very complicated, and it is much easier to take the septic tank waste to a wastewater treatment plant, he said.
When septic waste is land applied, there are many variables: the timing, the pH of the load, the temperature, the driveways used. It must all be reported, and it cannot be over-applied, Bjork said.
Since it has become more complicated to land-apply waste from septic tanks, many haulers over the last five to 10 years have downgraded their licenses and only take the septic tank waste to wastewater treatment plants, he said.
“It is so much easier. No lime. No approved sites. If the treatment plant would guarantee that they would always take it, I would never put another load on the ground. But that is not the world we live in,” Bjork said, adding that septic haulers must have the ability to use wastewater treatment plants and to land apply septic tank waste.
During the summer, 25 to 30 percent of the septic tank waste goes to the wastewater treatment plant, and in the winter 50 to 100 percent goes to the wastewater treatment plant, he said.
The septic waste is applied at 12,900 gallons per acre, which is the amount used by the plants. Every truck is subject to being checked by a DNR game warden, other DNR personnel and the Wisconsin Department of Transportation, Bjork said.
Every septic hauler Bjork employs must have continuing education every year and must update the certification every year. Ultimately, Bjork said, he is the hauler in charge.
The number of gallons hauled is kept in the trucks and in the office, Bjork said.
Neil Koch asked the PR&D committee to take action on his request, but the committee is not in a position to take action at the November 20 meeting, said Tom Quinn, county board supervisor from Downing and chair of the PR&D committee.
The issue concerning septic tank waste will be put on a future agenda for discussion and further consideration, he said.
