BY ROBERT J. SMITH
Posted on Monday, July 25, 2005
SILOAM SPRINGS — City Administrator David Cameron wants to kill the green algae that clogs sections of Sager Creek by pumping treated sewage into the stream.
If the plan works as Cameron hopes, treated sewage will beautify the creek by keeping it flowing as it bends around Bob Henry Park and through the rest of the city.
Cameron’s plan is part of a larger, $20 million strategy to build a new sewer treatment plant capable of stripping out almost all of the phosphorus from treated sewage before it’s discharged into the creek.
The city hasn’t determined how to pay for it, but a $15-amonth sewer rate increase, a 1-percent sales tax or some combination of the two are among the possibilities, Cameron said.
A ballot issue could be placed before voters early next year if the city’s Board of Directors approves, Cameron said. If voters are asked to consider a sales tax, the ballot issue will be one that funds the sewer plant project and a variety of other things. Possible projects include new lights for the city’s rodeo arena, a new University Street bridge, upgrading the city’s aquatic center, updating a fire station, adding sidewalks and walking trails, constructing an electrical substation and spending money to eliminate a drainage problem in the Lynndale Estates neighborhood.
Central to the improvements Cameron is pitching are Sager Creek, the sewer plant improvements and meeting Oklahoma’s phosphorus limit. Two companies that make membrane bioreactors will conduct pilot tests beginning this fall to determine whether their screens can remove massive amounts of phosphorus and other unwanted nutrients before it’s returned to the stream. "I’m confident that the technology can take us there," said Steve Jones, a vice president with Garver Engineers in Oklahoma City who’s supervising the project.
REDUCE PHOSPHORUS Siloam Springs was one of five Northwest Arkansas cities that promised Oklahoma in 2003 to discharge no more than 1 milligram of phosphorus per liter of water. Siloam Springs must accomplish the goal by 2009.
That 1-milligram limit is far higher than the phosphorus limit Oklahoma established for its scenic rivers in 2002 and expects Arkansas to meet at the state line.
The rivers must meet a limit of 0.037 milligrams of phosphorus per liter by 2012, as measured at the state line.
Although Sager Creek isn’t one of Oklahoma’s protected scenic rivers, it discharges into Flint Creek soon after crossing the state line. Flint Creek is one of the six protected streams.
With the Siloam Springs sewer plant discharging treated sewage just 750 feet from the state line, there might not be time for its phosphorus content to dip much before it reaches Flint Creek. That’s why the city wants to treat its sewage to 0.037 milligrams or less.
The water flowing into the sewer plant on a typical day carries 14 milligrams of phosphorus per liter of water. After it’s treated, the level is reduced to 3 milligrams. "We don’t want to be worrying about 2012," Cameron said. "We want to do better than 1 milligram sooner than that."
That’s why the city’s board of directors agreed June 21 to spend $500,000 to determine whether Canada-based Zenon Membrane Technology and Memcor Products in Maryland can remove enough phosphorus from the water that’s discharged by Siloam Springs to ensure it meets the 0.037 milligram limit.
The competing companies will begin setting up their pilot sewer plants next month.
They’ll be tested and tweaked by the companies for two months as their employees look to remove phosphorus, nitrates and other contaminants from 30,000 gallons a day. It’s a small portion of the 3 million gallons of sewage that flow into the city’s sewer plant on a typical day.
In October, the city plans to do its own testing, comparing the two plants to determine which one works best at removing the phosphorus and other contaminants.
The key piece of the sewer plants operated by Zenon and Memcor are membrane bioreactors. They are filters with hollow, spaghetti-like straws with pores that catch pollutants in much the way air-conditioner filters collect dust in homes.
The membranes can be cleaned to remove phosphorus and other contaminants, keeping the filters working properly, said Ron Maness, a Zenon regional sales manager. "The 0.037 is a new benchmark for phosphorus removal," Maness said. "No other facility requires that level of removal. We’ve done studies that show using biological nutrient removal and a coagulant that we can get to these ranges, but that’s why we are running the pilot studies. We’re running the pilot study to prove that."
Ed Jordan, vice president and product manager for Memcor, acknowledged that the 0.037 limit will be difficult to achieve, but possible.
EYE APPEAL There’s plenty of water to keep Sager Creek on the move through the winter and spring, but in the dog days of summer, it slows to a snail’s pace. That allows green algae to grow and float on the slowmoving water that has little eye appeal. In some summers, the creek has been crusted over by the algae. "I was put in charge of what do we do about Sager Creek," said Cameron, who was the city’s public works director before becoming city administrator in February. "Sager Creek is our own scenic river. We have folks in town who want to see it restored to its former state."
The city hired the Little Rock environmental consulting firm GBMc and Associates to study the Sager Creek watershed and figure out how to make it better.
Shon Simpson, a principal with the Little Rock firm, said employees have collected fish and insects, studied sources of pollution and will look into the number of cattle and chickens produced in the watershed as they try to figure out the best way to improve Sager Creek. "We are looking at potential restoration remedies of creek to solve the algae problem, and we’ve got some concepts in mind," Simpson said. "The way that creek functions is basically a pool-to-pool scenario because of artificial dams. The flow is so slow through that area that it allows algae to bloom."
He wouldn’t say what concepts his firm will recommend. The work isn’t done. He expects to make recommendations to Cameron in October.
Among the possibilities is Cameron’s idea of pumping treated sewage across town and discharging it at a location near the Siloam Springs Country Club golf course.
From there, the water would flow westward and back through town, keeping the creek fuller than it usually is during the summer months.
How much water is pumped through the pipe and when it will have to be pumped will depend on how much is necessary to eliminate the algae growth if Cameron’s idea becomes the solution. "We’re trying to restore it to more of a natural condition that hasn’t existed for years," Simpson said. "Nothing is certain just yet."