By SUE SUCHYTA
Sunday Times Newspapers
MELVINDALE – Department of Public Works Director Larrie Ordus and C.E. Raines Engineer Bruce Hammonds explained the urgent need for pump station upgrades at the Dec. 7 City Council meeting.
Pump stations, which receive raw sewage through underground, gravity-fed pipes leading to an underground pit, pump sewage upward to pressurized sewer main pipes, a process repeated until sewage reaches a treatment plant. When a pumping station fails, raw sewage can overflow into the environment.
Some pump stations have grinders to break up sewage, so it can flow more easily through the system.
Ordus said the city’s pumping station, 3390 Greenfield, is 20 years old and has issues that need to be addressed.
He said the pump station sewage grinders, which usually last five to seven years, were rebuilt 10 years ago, and when he started on the job two months ago, neither grinder was working.
He said when they don’t work, the flow comes up and floats over them, which impacts the operation of the sanitary sewer system. He said they have gotten one of the grinders working since then.
Ordus said the company that supplied the original grinders is offering a significant cost incentive, nearly half the standard cost, for the city to upgrade to a new grinder, because it wants to phase out making parts for the older model grinders.
He said the first option is to rebuild the grinders without a guarantee; each rebuild would cost $30,000.
The second option is to upgrade the grinders using the current system’s antiquated hydraulic power system, which wouldn’t be the most efficient option, but they would run. The second option cost $45,000 per grinder.
The third option is an upgraded grinder with new control panels and new motors for the hydraulic units, which is $45,500 per grinder.
The fourth option includes an electric motor, which has more torque — twisting force — and is $43,000 per grinder. Ordus said the sewage is broken up better when it goes through the grinders driven by the more powerful electric motors, which subsequently puts less strain on the pump stations.
“If I go with electric, I can possibly keep one (grinder) going now, so we don’t buy two at the same time, and you won’t have to replace them both at the same year again,” Ordus said. “I don’t know how long the one that I got there will keep running, but it is running now, so my recommendation is we go with the electric.”
He said the grinder upgrade is needed, since the sewage pump station is a 24-hours-a-day, seven-days-a-week operation, unlike some pump stations that only run when there is storm water runoff.
“You really have to stay on top of this pump station, because if it doesn’t run, there will be some sewage in some people’s basements,” Ordus said.
Mayor Stacy Bazman said from a safety and liability standpoint the city really did not have a choice.
Councilman Carl Louvet made a motion, supported by Councilman Wheeler Marsee, to purchase the $43,000 updated grinder with an electric motor. The motion passed unanimously.
The gas monitoring system, which is 20 years old, also is not working. The system is designed to detect hazardous gases and fumes.
Hammonds said the system, when working, detects flammable and corrosive gases that occur in a sewage environment. The alarms can alert personnel of hazardous materials that enter into the sewage system, warn them of poisonous fumes, and turn on the ventilation system.
“It is there to protect the people that go in there from the hazardous gases that sewage has with it,” Hammonds said. “It’s also there to protect the pump station while nobody’s there, in case there is a spill of something that enters the sewer system, and the gases get into the plant, it will say we have a problem, send the alarm out, turn the air handling system on a higher speed, and force the fumes or chemicals out. It helps keep the station safer.”
Ordus said the pump station doesn’t have that protection because the gas detection system is not working, and when entering the station a person could encounter a gas like methane, an odorless, flammable hydrocarbon gas that is explosive.
He said the air system fans are running continuously, and the outdated technology of the gas detection system is not running.
“That’s got to be done,” Ordus said. “It is unsafe to go in there without a gas detector.”
The council unanimously approved a motion for $24,000 to replace the gas detector in the pump station.
“There are a lot of other things that are happening there also, that have to be addressed, but not as big as these items,” Ordus said. “These are the large items right now that need to be taken care of, but there are a lot of other issues that we can possibly take care of without having to come here for approval.”
(Sue Suchyta can be reached at [email protected])