Storm events present challenges for wastewater treatment utilities every year, and this year has been no different for communities across Minnesota. The MPCA would like to recognize the City of Mora for investing in its wastewater infrastructure and thank its wastewater staff for their efforts in responding to a July 2018 storm event. The combined efforts directly contributed to environmental and human health protection. 

On the morning of July 12, Mora received 8.25 inches of rain in about 3.5 hours. Seven Mora staff members worked continuously in response to the rain event, and as a result no sanitary sewer overflows or releases were reported.

“Having knowledgeable and reliable staff is the main factor to all of this. Everyone remained calm, even at times when it seemed to be overwhelming, going above and beyond to help and accomplish what needed to be done safely,” said Joe Kohlgraf, public works director for Mora, a city of 3,571 in central Minnesota.

In addition to having capable staff, Mora completed a significant wastewater infrastructure upgrade in 2017. A little more than $7 million in state funding helped finance the upgrades, which also results in far less phosphorus in its discharge to the Snake River.

Kohlgraf identified three actions that kept everything up and running during the recent storm:

• New main lift station capacity. “Our old pump set up consisted of three pumps which would do about 1,600 gpm [gallons per minute] and would not have kept up to this storm event. Our three new pumps were pushing around 2,200 gpm and kept that up for the majority of the day. Without this upgrade, we would have been calling the duty officer and bypassing,” he said.
• Replaced old boat clarifiers with new clarifiers. Had the old boat clarifiers been in place, the ability to perform wastewater treatment would have likely been compromised. 
• Back-up power at main lift station. The new generators would have allowed operations to continue if the power had been out for an extended period.       

Following the storm event, Mora is continuing to focus efforts on reducing inflow and infiltration within the collection system. “We are currently scheduling sewer smoke testing to improve our system and pushing our sump pump policy again to keep issues like we had in this event to a minimum in the future,” Kohlgraf said.

The Minnesota Pollution Control Agency (MPCA) would like to thank Mora wastewater professionals, and all statewide wastewater professionals, for their dedication and commitment to improving the environment and enhancing human health.

Photo above right: 8.25 inches of rain in 3.5 hours flooded streets in Mora, Minn., on July 12, but its Wastewater Treatment Facility managed to avoid any sewage releases thanks to the dedication of staff and recent upgrades at the facility.

The MPCA is seeking Wastewater Treatment Facilities (WWTFs) for a pilot project on optimizing practices to meet more restrictive phosphorus limits without having to do costly construction projects.

Background

Lake and River Eutrophication Standards have led to new or more restrictive phosphorous limits in many wastewater discharge permits throughout Minnesota. While the standards will lead to cleaner lakes and streams, they can also lead to major construction projects for WWTFs, which can place municipalities in costly deliberations. But there may be ways to optimize treatment to meet these new limits, without the expensive build-out scenarios. What if, by adjusting recirculation rates, or retention times, municipalities could comply with new limits and avoid new construction?

The MPCA plans to explore these scenarios through a pilot project funded by the Environment and Natural Resources Trust Fund. Communities in other states have documented their success in meeting limits through optimizing practices, providing an example to follow.  The Legislative and Citizens Commission on Minnesota Resources, which recommends proposals for funding, also believed the scenarios were worth exploring. It scored the MPCA’s optimization project proposal as its second highest priority in 2017. The 2018 Legislature then approved a $700,000 grant for the pilot project.

Beginning this fall, the MPCA will coordinate with the Minnesota Technical Assistance Program (MnTAP), and Minnesota Rural Water Association (MRWA) to focus efforts on about five WWTPs and 30 stabilization ponds. The goal is to apply new knowledge to old treatment systems to maximize the treatment potential without costly infrastructure projects.

“We think that we can find ways to get the bugs to work a little harder and drive those Total Phosphorus numbers down, without having to bolt something new onto Minnesota’s treatment plants,” said Joel Peck, municipal liaison with MPCA and manager of the pilot project. “MRWA has such great first-hand understanding of stabilization ponds, and MnTAP has a track record of applying theory to practice for wastewater plants across the state.”

The end result will be a field guide of optimization techniques for operators to use to meet more restrictive phosphorus limits.

“If we can solve this through process control, rather than expensive construction projects, the people of Minnesota win, with cleaner waters and less expensive ways to get there,” Peck said.

How to sign up for the pilot project

The MPCA, MnTAP and MRWA are looking for WWTPs and pond systems to take part in the pilot project. There is no cost to you or your municipality.

If you anticipate new phosphorus limits in your permits and want to know if optimization can work for your system:

• Fill out the form at on the MRWA website: www.mrwa.com/pondopt.html.
• Or email Joel Peck at joel.peck@state.mn.us, or Jon Vanyo at jvanyo@umn.edu 

The MPCA has great news to report. At the request of the Metropolitan Council Environmental Services (MCES) and City of Minneapolis, the agency recently terminated Minnesota’s last remaining Combined Sewer Overflow (CSO) permit. 

Combined sewer systems – carrying wastewater and stormwater in the same pipe – were first used in the mid-1800s to better manage sewage flow in urban streets. At that time, the combined sewage flowed straight into lakes and rivers. Cities added wastewater treatment systems in the early 1900s to treat the combined sewage before being discharged. Combined sewers work well until stormwater runoff overwhelms the capacity of the piping system, leading to wastewater bypassing treatment and flowing directly into surface waters. Combining wastewater and stormwater also adds to treatment costs and can require building unnecessary treatment capacity.

In the 1980s, MCES and the City of Minneapolis started three decades of aggressively identifying and separating remaining combined sewer areas. As of 2017, Minneapolis has removed almost 4,000 acres of stormwater drainage from the city’s sanitary sewer system. While isolated combined sewers still exist today, the sewer systems in Minneapolis are essentially separated and the risk of overflows is low. Sewer separation work has been so successful that there has not been a documented CSO overflow in 8 years.

This success story is especially noteworthy considering that similar-sized cities across the U.S. continue to spend billions of dollars to comply with federal CSO management requirements. EPA implemented these irequirements in 1994, but MCES and Minneapolis was already working to reduce combined sewers. Previous work done in Minnesota means that cities today can use limited public dollars for other pressing infrastructure needs like renewing and replacing aging infrastructure.

Photo above: MPCA personnel look over sewer separation work in the agency’s back parking lot in St. Paul in 1993.

The MPCA is in line for a $250,000 grant to help municipal wastewater treatment plants (WWTPs) in Minnesota reduce mercury pollution and save money. The grant comes from the Environment and Natural Resources Trust Fund, funded by lottery proceeds. Pending authorization from the Minnesota Legislature, the three-year project would begin in 2019 and conclude in 2022.  

Many Minnesota cities need guidance on the wastewater treatment technologies available to cost-effectively reduce mercury pollution. This project will produce a document that summarizes and evaluates mercury treatment technologies, allowing municipalities to select a mercury treatment strategy that appropriately meets their community’s needs while also minimizing mercury pollution. The study will develop a guidance document by evaluating the mercury treatment performance of 13 wastewater plants in Minnesota’s Lake Superior Basin that implement a variety of mercury treatment technologies, ranging from chemical precipitation to filtration. Design for mercury removal is presently based on controlling effluent solids, and this study will provide a foundation for evaluating the relationship between mercury treatment and particulate solids control.

The MPCA will elucidate the effectiveness of mercury removal by analyzing:

• Existing mercury wastewater compliance data
• Detailed engineering design analyses of wastewater plants
• Mercury mass balances

The agency will also examine mercury removal mechanisms through sampling and analysis of mercury speciation in various plant locations, targeting those unit operations expected to be critical for removing mercury or changing the partitioning behavior of mercury.

Reducing mercury in wastewater discharges is important for Minnesota waters and fish populations. Mercury accumulates in fish tissue, leading to limits on how much fish people can eat. Read more about mercury pollution on the MPCA website.

Failing to submit all required forms with eDMRs is a common problem seen by MPCA data management staff. Here are a few tips on submitting forms:

• Influent and effluent are different forms; be sure to submit both! (Make sure to maximize the Excel spreadsheet version of the eDMRs to access all sheets.)
• Quarterly and Annual DMRs are separate from the monthly DMRs. (Need to be downloaded separately from the monthly DMRs.)
• Attach all documents required. (Release Sampling Reports, cover letters, etc.)

Additional information is available on the MPCA DMR webpage.