Phosphorus limits could result in system overhauls

Municipalities and manufacturers are facing stringent new limitations from the Wisconsin Department of Natural Resources as they apply for phosphorus emission permits.

Limitations adopted at the end of 2010 are aimed at dialing down the level of phosphorus in the state’s waterways. Permits are gradually being re-issued under the new rules to point sources like factories and city wastewater treatment plants as they each come up for renewal every five years.

The phosphorus caps, which are set on a case-by-case basis, are aimed at reducing the amount of oxygen-depleting algae in lakes and rivers around Wisconsin. The algae can create an impediment to water activities and cause fish in the lake to die, said Art Harrington, shareholder and team leader of the Renewable Energy Practice Group at Godfrey & Kahn S.C. in Milwaukee.

“These criteria are set up to support the use of those lakes and rivers to be fishable and swimmable, so it’s a very stringent number to support that,” Harrington said.

Lake Michigan is big enough that the oxygen levels are fairly normal, but the phosphorus-fed algae washes up on shore and bakes in the sun, creating an unpleasant sewage smell, said Kevin Shafer, executive director of the Milwaukee Metropolitan Sewerage District (MMSD).

The lake’s Green Bay, though, has recently experienced a “dead zone” area with extremely low oxygen levels that has thrown its fishery system out of whack.

Phosphorus comes from point sources such as MMSD, but also non-point sources such as agricultural runoff upstream from the MMSD service area, Shafer said.

Harrington has been advising the City of Oshkosh on its new permit limitations related to Lake Winnebago. The city must reduce its phosphorus discharge from 1 part per million to 0.04 part per billion.

Harrington

Each direct discharger has five to nine years to meet the limits imposed on them through the new permit, he said. Sometimes, they can achieve offset credits for negotiating reductions from dischargers or non-point sources upstream that are contributing to the total phosphorus level in their area.

“The Milwaukee River has a big phosphorus issue coming from all the up-source agricultural operations coming from Washington and Ozaukee Counties and MMSD is at the end of that pipe,” Harrington said. “They only serve a very small portion of the Milwaukee River basin.”

Shafer

This is a big issue that municipalities and many direct dischargers, like paper mills and food processors, will have to address in the next few years, he said.

And meeting the permit limits could cost a significant amount of money. The new technology a municipal discharger would need to install to meet the guidelines could be in excess of $40 million. Those costs are then passed on to ratepayers.

MMSD received a new permit in January. Its Jones Island treatment plant is currently discharging 1 milligram per liter, and needs to meet 0.8 milligrams per liter within three years. The South Shore sewage treatment plant in Oak Creek was at a 1 mg per liter annual average and now much meet a 0.66 mg per liter six-month average from May to October.

It won’t be too difficult to meet those new limits, Shafer said.

“When you operate a water reclamation facility like we do, if your permit is at 1.0 like we had before, you always want to operate it at 0.6, 0.7,” he said. “You always operate much lower than what the permit requirement is.”

But the limits imposed on MMSD may be lowered again when it comes up for renewal in four and a half years. A study is currently being conducted on the Total Maximum Daily Load in the Milwaukee River basin.

“The numbers really aren’t available yet from the consulting firm and to say exactly how it’s going to impact any individual municipal discharger is kind of not possible right now,” said Jackie Fratrick, limits engineer at the DNR.

The study is expected to be completed by the end of the year, Shafer said.

“If we have to, we’ll have to build more capital improvements in the future,” Shafer said.

A 2008 estimate pegged those improvement costs at about $500 million. The costs, which would be passed on to ratepayers, would go toward installing and running biological filters, which require a lot of energy.

“That’s very much on the high end, we don’t know exactly yet, but I don’t know that we’ll be spending that much,” he said.

While it waits for the TMDL results, MMSD has been working with its existing systems to increase biological phosphorus removal in a pilot program at the South Shore plant. The process would filter water through tanks of microorganisms and create a milorganite fertilizer byproduct, removing phosphorus before discharge.

According to the DNR, 25 new permits have been issued in southeastern Wisconsin since the new regulations went into effect. There are about 115 dischargers subject to the permits in the southeastern region.

One of those companies was We Energies, which received a permit for its Menomonee Valley power plant on Jan. 1.

“We didn’t have a limit set before because the permit hadn’t established a limit before,” said Dave Lee, manager of water quality at We Energies. “The way the permit is actually structured is there is an initial limit that goes into effect right away and then by the end of the term of the permit, it will be lower.”

Right now, the plant is operating at 200 parts per billion and within five years it must reduce output to 100 parts per billion, he said.

The water We Energies pulls in from the city is used to produce steam, generating heat and electricity. There is phosphorus in the water initially, and the company also adds a compound containing phosphorus to reduce corrosion in its boilers.

The company is looking at three options: reduce its usage, install more advanced wastewater treatment or water quality trading.

It’s tough to say how much a new treatment system would cost, but it probably would run in the “low millions,” Lee said.

“We’re going to start bringing in some outside engineering help to try to get an answer to that question,” he said.

We Energies is also researching the water quality trading process, in which it would provide its gypsum, a byproduct of its air quality control system, to farmers to reduce their phosphorus runoff.

Alternatively, We Energies could route all or part of its processed wastewater to MMSD for treatment, Lee said.

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