Sewer Plant Rife With Pump Problems

Mounting Frames Have Failed Repeatedly

PRAIRIE GROVE — The mounting frames on the two screw pumps at Prairie Grove's new wastewater treatment plant have failed repeatedly since the plant opened last summer and the city is waiting on the manufacturer to come up with a new design, according to Larry Oelrich, director of public works and administrative services.

“We're on our fifth failure,” Oelrich said. “These weigh hundreds of pounds. When the brackets fail, they flop sideways and jump up and down. When it breaks, it flops and beats everything to death.”

Oelrich said city employees have been instructed to turn off the pumps before doing any maintenance work.

“The whole thing is coming loose, the gearbox and the motors and the reducers that turn the pumps. It's dangerous for my staff.”

The structure is still under warranty by Lakeside Manufacturing and the firm has agreed to extend the warranty. Oelrich said he does not plan for the warranty period to start until the manufacturer has corrected the problem.

He said Lakeside initially redesigned the mounting frames and thought it had solved the problem but then the brackets on one of the screw pumps failed again last week.

“They've been willing to help but nothing has worked,” Oelrich said. “Obviously something is wrong with the design.”

The two screw pumps are located at the front of the city's new sewer plant. The pumps lift the water up through the plant. If the pumps are not working, then the water has nowhere to go and can overflow. Oelrich said the city reported one small overflow in November that resulted from a mounting failure.

The plant has an audio and visual alarm and the Prairie Grove Police Department notified city workers that the alarm was going off. Oelrich said a small amount of wastewater overflowed onto the ground but employees were quickly on the scene and able to stop the overflow.

The city is currently only using one screw pump because the gear house on the second one has been damaged. Oelrich said the manufacturer is paying to rent a portable pump at the plant, just in case another bracket fails.

“When you get down to one pump, if something happens to it, you have major problems,” Oelrich said.

In addition, he said the city is running the one pump continuously, though the pumps are designed to stop and start as needed.

He said the pump generates a tremendous amount of torque when it starts and he does not want the mounting brackets to break on that pump.

Oelrich said Lakeside Manufacturing has screw pumps all over the country but the mounting design differs from plant to plant based on the needs of the facility.

The sewer plant went online July 19 and cost $9.4 million.