Sewer Upgrades Seek to Limit Overflows, Phosphorous

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Brad Talley, Superintendent of the Department of Water Pollution Control, watches treated water flow into the flood waters of the Wabash River Monday, June 29, 2015, at Lafayette Wastewater Treatment, 1700 Wabash Avenue. A large pipe discharges water treated at the facility into the Wabash River. However, Talley said the high level of the Wabash, swollen from recent rainfall, prevents the treated water from flowing out of the pipe. So treated water flows out of a final treatment tank and into the river.
(Photo Credit: John Terhune/Journal & Courier)

Article courtesy of Hannah Smith Kiefer | July 10, 2015 | JCOnline | Shared as educational material

If you live in Greater Lafayette, you know how bad the Wabash River can smell when it rains. Many in the community consider it dirty and polluted.

Some of that speculation, it turns out, is based on truth. Although levels are much lower than 10 or 20 years ago, raw sewage still escapes into the Wabash during periods of heavy rain.

But officials at local wastewater treatment plants have plans to fix the stink entirely.

More than 100 towns in Indiana use combined sewer systems, which house stormwater and sewage in the same pipes. They are designed to overflow during storms rather than back up into homes or businesses, said Dave Henderson, West Lafayette utilities director.

But the systems fell out of use with the Clean Water Act in 1972, Henderson said.

The Environmental Protection Agency in 1989 established a strategy to fix the overflows across the nation. Under the strategy, treatment plants statewide submitted plans to reduce overflows to the Indiana Department of Environmental Management.

In Lafayette, one solution has been the award-winning Durkee’s Run sewer project. Its final phase is set to finish in August, said Brad Talley, Lafayette’s water pollution control superintendent.

Durkees Run, however, is only one phase of a long-term plan to reduce sewage overflows. Talley said the plan will take about 20 years due to the complexity and costliness of the projects.

Currently, the Lafayette plant handles about 52 million gallons of water per day, Talley said. During periods of heavy rain, overflows still are relatively common, occurring about 75 times during an average year.

By 2029, Talley said the city will be allowed four overflows per year on average.

When work on Durkees Run wraps up, Lafayette will turn its attention to the north end of the city, where crews will address the Greenbush Street combined sewer overflow. This fall, crews will install a 60-inch diameter sewer pipe in that area.

“Much of the long-term plan addresses storage of the combined sewage until the collection system can catch up,” Talley said. “Then the excess will be conveyed to the plant for treatment.”

Overflows in West Lafayette

In West Lafayette, the treatment plant faces similar requirements when it comes to overflows, but Henderson broke down the standard differently.

By the year 2027, Henderson said, the plant must handle about 2 inches of rain an hour without any overflow. An extreme rain event like that typically occurs “once every 10 years,” he said.

To meet state and federal standards, West Lafayette has expanded the plant’s wet weather system, which has increased plant capacity.

“It was first put online in 2003,” Henderson said. “Now, it’s been converted over to partial treatment.”

While the plant can handle on average about 22.5 million gallons per day or more than 30 million gallons per day for short periods, the wet weather system adds an additional 113 million gallons per day.

“For the bigger events, it fills up and discharges,” he said. “It treats (the water) with a bleach solution to kill bacteria, and then another chemical to neutralize the remaining bleach at the end of the treatment.”

Henderson said the wet weather system also will likely be expanded in 2026.

Phosphorous reductions

Both plants also must reduce the amount of phosphorous flowing out of the treatment plants into the Wabash River, in accordance with federal and state requirements aimed at reducing levels of the element making it into the Gulf of Mexico.

By August 2016, Lafayette must meet the phosphorous limit of less than 1 milligram per liter. Currently, the treatment plant sends out water between 5 and 7 milligrams per liter, Talley said.

Workers are installing tanks to hold the chemicals that will take phosphorous out of the water.

“The project is expected to be complete by the end of the year, and we will start early 2016 with actually the process part of it,” Talley said. He said the phosphorous improvements cost about $2.5 million.

For West Lafayette, Henderson said the phosphorous levels at the plant are between 3 and 4 milligrams per liter but need to be at 1 milligram or less per liter. He said the phosphorous removal plan at the plant is “well ahead of schedule.”

“We’ve got to hit our limit in February, and we’re well on track,” he said.

Henderson said he hopes to implement the chemical process by the end of summer. Upgrades for the phosphorous removal cost about $800,000.

He added that, despite the chemicals added during the removal process, no extra chemicals will go into the Wabash as a result.

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