By JEFFREY ROBB
Oct. 20, 2000 (Omaha World-Herald)—By next year, people hitting the trail at Papillion's Walnut Creek Lake will pass within feet of the waste from a new 11-house subdivision.
But, if all goes according to plan, the hikers and bikers won't know it from sight or smell.
To pull it off, the neighborhood will employ the latest in wastewater disposal - environmental stealth. The sewage will filter through a man-made wetlands, complete with cattails, brush, bugs and birds.
The idea is catching on around Nebraska, starting with Lincoln, Nemaha and a farm near Greenwood. The Omaha area's first system, which will be Nebraska's largest, is being built at the Hanson's Lakes area in southeast Sarpy County.
The wetlands are designed to treat wastewater for less money and often to match environmental surroundings. Although the current wetlands systems report few problems, the Omaha area systems will be near the Platte River and a pristine dam site.
With construction at Walnut Creek Estates about to start south of Walnut Creek Lake, located at 96th Street and Nebraska Highway 370, some environmental advocates are closely watching the project and hoping for the lake's sake that nothing goes wrong.
"I think caution is appropriate, let's put it that way," said Steve Oltmans, general manager of the Papio-Missouri River Natural Resources District.
The "constructed wetlands" idea employs a combination of engineering know-how and Mother Nature to do the dirty work. The wetlands usually combine with wastewater septic tanks to start the filtering, which Walnut Creek Estates willdo for 10 of its homes.
From there, the wastewater enters a wetlands process scientists still don't completely understand.
One method employed in wetlands has worked in treatment stations for hundreds of years, said John Stansbury, a University of Nebraska assistant professor of environmental engineering.
Man-made treatment plants trickle wastewater through tanks full of rocks, which creates a bacteria film on them, said Stansbury, who's on a university team that studies Nebraska's systems. The wetlands, too, have different sizes of rocks, providing places for bacteria to grow.
The bacteria, when combined with oxygen in the water, eat away at organic matter flowing through the wetland. Ammonia, for instance, converts to a more acceptable nitrate.
Then the wetland plants, whose roots act as a strainer, kick in. Using a process inherent in their nature for untold years, the plants absorb nitrates like fertilizer and turn out oxygen.
In turn, the oxygen can help break down wastewater, completing a cycle.
"It's pretty cool," Stansbury said. "It's surprising that much goes on in there."
As it leaves the wetlands, the water often resembles creek water. Walnut Creek Estates will run that water through another tank before depositing the results in a trench not far from the recreation area's trail.
Bob Dreessen, Walnut Creek Estates' engineer, said the development wouldn't build a risky system with the lake so close.
"We're very, very convinced it's a far better solution than setting the precedent of septic tanks in a sensitive area such as this," Dreessen said.
But concerns have arisen that the systems and their plants might not work during Nebraska winters. Constructed wetlands are more common in the warm southern United States, although Canada and Europe also have them.
Stansbury and Mohamed Dahab, a University of Nebraska-Lincoln civil engineering professor, said the systems remain efficient during the winter. They based their evaluation on reports from Lincoln's Firethorn subdivision, installed as Nebraska's first system in 1995.
Recently, however, a problem at Firethorn let off some smell and forced part of a wetland cell to be rebuilt, Dahab said. When gravel became clogged at the front end, he said, water that normally stays under ground seeped to the wetland's top.
The professors described the problem as minor. Aside from that instance, Dahab said, "If you walked by it, you wouldn't know it was there."
Not everyone at Walnut Creek Lake is sold on the idea. The NRD wanted Papillion to extend city sewer lines to the lake area, but the Papillion City Council authorized construction of the wetlands in early August.
The subdivision will hook up to city sewer service once the open areas leading to the lake fully develop.
"We've had some concerns because it's a new approach," the NRD's Oltmans said. "I think Papillion has to be careful about setting a precedent."
Lee White-Hamilton, who lives and farms near the lake and sits on its Community Clean Lakes Council, questioned the arrangement before the City Council and wanted proof that the city engineer and state regulators approved plans.
"Who's going to clean up the mess if it doesn't work?" White- Hamilton asked. "It definitely needs to be monitored."
The Nebraska Department of Environmental Quality and Papillion's engineer on the project, John Adler of Kirkham Michael Consulting Engineers, have signed off on the system, saying it shouldn't pose problems. The subdivision will test the system monthly.
The wetlands' appearance was a factor in developer Jeff Schmid's decision to use the system. Schmid, a bank president from Papillion, promised at a public meeting that the neighborhood would resemble a scene from "The Sound of Music."
In addition to cutting opportunities for septic tank failures, the wetlands cost less, too, leading to predictions that small towns increasingly will turn to such systems.
Nemaha, which built the wetlands to avoid a potential tripling of its water rates, started using its system last month. The State Environmental Quality Department is monitoring the project to determine if the wetlands are a cheaper, effective alternative, said M.J. Rose, the department's Nebraska environmental partnerships coordinator.
With a glut of septic tanks threatening drinking water and recreational sand-pit lakes, the Hanson's Lakes area chose to build a $3 million wetland system to serve 350 homes. The subdivision would have paid up to $500,000 more to build a sewer plant or connect to Omaha's system, said Jim Olmsted, the subdivision's engineer.
"It's a proven system," he said. "It's a natural biological system."
But just in case, Olmsted said, Hanson's Lakes will have four stations to check for any groundwater contamination. The treated wastewater will flow into the Platte River.
Dahab said the systems always will require proper maintenance and still must prove their long-term effectiveness.
"This type of technology is new to this part of the country," he said. "That's why we're interested."
How constructed wetlands work:
1. Wastewater enters the wetlands after passing through septic tanks.
2. Wastewater is run through a distributor, then filters through layers of various sized river gravel.
3. The wastewater flowing over the rocks causes bacteria to grow on them. The bacteria, with oxygen in the water, then eats organic material in the wastewater and converts it, for example, to more acceptable nitrates.
4. The plants then filter and feed on the nitrates, using them as fertilizer. The end result is naturally filtered water.
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