New sewer plant begins to take shape

By Cindy Sheets
Contributing Writer

Construction on Perkins’ new wastewater treatment plant is well underway.

Wet weather this spring delayed construction, but crews are now making up time.

“At this point we’re running about 20 percent behind schedule,” Perkins City Manager Pete Seikel said. “It’s a huge project and weather has been a little against us.

“We just had a miserable winter trying to move sludge from the construction site.”

Seikel said crews also had to pump water from the site after four inches of rain was received in June, and recently extreme heat has also affected hours worked.

But now, things are moving along quickly. Quicksilver Construction Company, the project general contractor, started pouring concrete on Tuesday, July 13.

By Friday, panels were being put in place so crews can begin pouring concrete for the plant’s three immense mixing basins.

The new wastewater treatment plant will replace a decades-old lagoon system that was not keeping up with Department of Environmental Quality standards.

Perkins City Commission in February of 2009 approved a sewer rate increase that will, in addition to a loan from the Oklahoma Water Resources Board, pay for the new system. The new rates went into effect in April of 2009.

The 18-month project officially started June 9, 2009, Seikel said.

Prior to construction, the wastewater treatment operation was converted to an overflow or stand-by basin with three floating aereators. “This is what’s giving us our primary treatment now,” Seikel said. “It’s actually doing us a better job than the three lagoons were doing.”

The plant’s original layout included three lagoons and one small standby lagoon which occupied approximately 11 acres.

The new plant’s footprint is much smaller. It will occupy two cells, which will encompass approximately four acres. Cell 3 and the stand-by cell will eventually be done away with.

The new plant will still be fed from two lines that come from town. One line comes from the north and east side of town, while the second line essentially handles the area west of Main Street.

The new plant is called a Sequential Batch Reactor (SBR) System. In an SBR system, treatment first comes into a headworks building where a lot of the solids, including sand and grit are removed. Then, a grinder breaks up solids and biological action begins.

From there, the wastewater goes to a pump station, then sent to three mixing basins (each approximately 13 ft. deep), where it is stirred by high-velocity jet aerators and oxygen is delivered into the wastewater.

Jet mixers also provide mixing in the basins without introducing oxygen.

Jet aerators and mixers are ideal for this type of system because they have no moving parts in the basin and require no maintenance.

Each of the three mixing basins can independently hold the wastewater in different stages – mixing, fill, or decant. The cells are never completely empty.

As the wastewater becomes clean, it is siphoned off. At this point, the clean wastewater is referred to as “supernatant.”

The supernatant is skimmed from just below the surface of the basin. It goes into a disinfectant chamber where it is treated with ultraviolet light.

“This gives a very, very high level of disinfectant – in the 99 percent range,” Seikel said. “It’s much cleaner than anything in the Cimarron River at the moment.

“Another advantage is we’re not using any chemicals. It’s safe for employees and more environmentally friendly.”

The solids that settle, or “sludge,” is pulled off at the bottom of the basins. It is transported to a sludge handling area, where a polymer is introduced. Water molecules in the sludge latch onto the polymer. The sludge is then compressed and becomes a sludge “cake.”

Some water goes back into the system after the polymers are released. This carries beneficial microbes back into the system.

After the cake dries, there are two options: it can go to a landfill or it can be used for farm land application.

The new system should generate an average of 250 pounds of dry ‘cake’ sludge per day.

The whole system can be controlled off-site by computer. The System Control and Data Acquisition (SCADA) lab building will be networked to city hall, where staff can see and adjust:

-how many gallons per hour are being treated

-flow

-stages of treatment

The system designer, Siemens Water Technologies, can also monitor plant operations remotely, and assist by making recommendations.

The current plant has capacity of .23 mgd (million gallons per day).

The new plant’s design capacity is .46 mgd, or double what can now be produced.

It also will have a surge capacity of treating .68 mgd, which will be able to handle storm water and water coming into the system from leaks in the city’s older clay tile pipes.

Seikel noted a lot of the grit that comes into the system is delivered from storm run-off and leaks in the older pipes.

“Basically, we will have double capacity, which means more efficient treatment and high quality effluent (discharge),” he added.

Theck Laird, Quicksilver vice president, said this type of system is easy to expand, if needed, in the future, “We can add [another cell] on to this site. That will increase the flow by one-third. This plant size should be good until around 2030.”

Seikel added, “There’s a lot of redundancy built into the system. It has its own stand-by power and there is a method for storm water to flow into system through the Flow Equalization Basin.”

The total cost of the project is $7.25 million - $2 million will come from Stimulus funds straight off the top, which leaves about $5.25 million to be financed.

That $5.25 million debt will be served by the increased utility rates put in place last April, and from the Oklahoma Water Resources Board Clean Water State Revolving Fund (CWSRF) loan. Seikel said the 20-year note carries only 2.91 percent interest.

“The only other debt on the project is interest on the amount of money spent for construction,” Seikel said.

The actual debt service begins about one year after the plant is accepted, which will probably be in 2012.

“If the weather holds and we can catch up on everything, construction is scheduled to be complete in December of this year, with the Perkins Works Authority accepting the plant in March,” Seikel said. “This will allow us three months training, etc. with new facility.

This is part of the July 29, 2010 online edition of The Journal.

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