The next wastewater collaboration
In retrospect, it looks like a plan.
In the last decade, Wisconsin regulators and state industries including dairy, food, paper mills and even cities and towns, have been diligently working through new regulations and state law to effectively process wastewater. There’s progress on two key fronts, and a final challenge remains as the state seeks to harness these nutrient-laden waters.
Discharging to Surface Waters
Wastewater from dairy and food plant clean-up, paper processing and city sanitary systems took the spotlight in 2010 when Wisconsin Department of Natural Resources (DNR) approved stringent limits for phosphorus in treated wastewater released to “surface waters” like rivers, streams and lakes.
Lengthy rulemaking yielded options for companies and cities holding wastewater permits, including adaptive management and water quality trading to meet phosphorus targets. Today, 10 municipalities in Wisconsin have completed or are currently partnering with upstream farms and other nonpoint sources to reduce overall output of phosphorus under the adaptive management program.
Four dairy plants are among 14 permit-holders that have successfully implemented water quality trades.
In 2013, Wisconsin’s legislature approved a variance for permit holders because major facility upgrades to meet the tough new phosphorus limits would cause “substantial and widespread adverse social and economic impacts on a statewide basis.”
Wisconsin DNR followed with a multi-discharger variance program, approved by the U.S. Environmental Protection Agency in 2017, that allows permitted industry and municipalities to meet water quality limits for phosphorus more slowly, while paying Wisconsin counties a fee to help farms minimize phosphorus run-off.
Today, 47 towns and cities, four cheese factories and three other firms are using the variance.
Soil Treatment Systems
Many dairy, food and industrial companies use land-based treatment areas, such as dedicated spray fields or terraces or ridge & furrow systems to allow soil and plants to perform the final uptake of nutrients in treated wastewater. Since 2010, nitrogen limits for these treated waters have taken the spotlight.
Wisconsin DNR joined with Wisconsin Cheese Makers Association and Midwest Food Products Association in 2015 for an ambitious study to examine the fate of nitrogen in grassy spray fields and verdant ridge & furrow systems. The University of Wisconsin Soil Science professor Francisco Arriaga and his team performed ground-breaking, on-site studies of three ridge & furrow systems and three spray fields around Wisconsin, capturing data on nitrogen after fresh applications of treated wastewater.
The study, now in final draft form, notes that soil-based wastewater treatment systems “appear to provide an effective means to treat nitrogen,” with management, composition of wastewater and weather as factors affecting performance.
The core innovation in the study was development of chambers to collect air samples above dampened land – gaining denitrification information. The final draft notes that for five days after wastewater soaked a test location, under anaerobic conditions, denitrification increased significantly. In other words, soil microbes readily released nitrogen into the air.
The study should move to published form by the end of 2018.
A broad, third area of wastewater disposal is incorporation of treated water onto fields, or in landfills or other sites. Land application can fortify crops and regenerate ground water, but increased urbanization and competition for useable land is challenging this common option for municipalities and industry.
WCMA recent surveyed dairy manufacturing members in Wisconsin to learn key concerns across the spectrum of surface water discharge, soil treatment systems, and land application. Replies from industry found members “very concerned” with the economic and regulatory climate around all these practices. One commenter noted: “Waste treatment is a significant operating expense for us. We’ve invested millions of dollars in treatment and are frustrated by the increasingly stringent limits and permit requirements.”
The highest-rated survey responses centered on land application. Members surveyed found “strong agreement” with these phrases:
- We are running out of land application options as Wisconsin DNR approves fewer sites.
- We are running out of land application options as Wisconsin DNR approves more limited application rates.
- We are running out of options for disposing of brine as municipalities cease to accept it.
- Wisconsin DNR’s interpretation of NR 214 that prohibits use of manure pits creates challenges for sludge disposal.
Working together, Wisconsin regulators, municipalities and the food industry have made (expensive) headway on treatment of wastewater bound for soil treatment systems and surfaces waters. The next area for cooperation is land application. Wisconsin creates food for the nation and world, and further collaboration is needed to assure our vital clean-up water can be treated and returned to the land.
Umhoefer is the executive director of the WI Cheese Makers Association