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Community Notes: The city’s new WRRF is up and running

By Dan Rimrod, WRRF Superintendent

Big changes have happened since last July’s Community Notes at the newly named Water Resource Recovery Facility.

After 56 years the two primary clarifiers and trickling filter made their last circular turn. Even with maintenance and upkeep they showed it was time.

I looked forward to seeing the trickling filter dome fall in and the bio-tower fall and I missed them both. They said it only took a few pokes of the breaker and the filter dome collapsed. This made me think back years ago on one cold morning the dome was making a lot of movement grinding noises and I got out real fast.

Community Notes: The city’s new WRRF is up and running
Dan Rimrod

The equipment in the new head works building and the oxidation ditches were started up for checks and training from July into August of 2021. A proportioned flow started to enter into the new plant on Aug. 24th.

We would continue to run the old plant and new plant together until we shut down for good on Nov. 15th the old part of plant that was replaced with the new treatment. During this time and some later we started up the new plant generator, influent pumps, equalization pumps and new power supplies to the existing building.

Another part of the project was a new lift station next to the Cedar River on Gilbert Street and that was commissioned on Dec. 14, 2021.

Things are moving along to finish up this project. We are down to some ground work and a few things to make everything work as they should. The WRRF Department is in a better position for higher flows and treatment capabilities.

The effluent is so much clearer and tests have shown that we have gained on nutrient removals, going from 29% to 83.39% total nitrogen removal and 19.9% to 59% total phosphorus removal, which now meet the new Iowa Department of Natural Resources Nutrient Reduction Study limits put into place with our permit renewal in 2014.

One more accomplishment that followed the new treatment was looking into reducing the amount of ultra violet disinfection equipment needed with the new treatment. We were recently able to remove one of the tjhree banks in the U.V. channel.

This means seven modules that contain 56 bulbs and 28 ballasts are no longer needed. This is beneficial as the bulbs, ballasts and operation of this equipment are quite expensive.

Every year I like to end my Community Notes by asking for removal of sump pumps from sanitary sewer connections, which are illegal. Connection to storm sewer is acceptable typically. If I can slowly change the idea that it is fine for homes to be adding extra unwanted flow that all has to be pumped again at a lift station and again at the plant, and then treated, I will keep mentioning it.

Regulations require that we treat all flows, so if we can keep them down the plant can operate more efficiently and without any violations and costly fines.

Chemicals such as gasohol, diesel, grease, paints and any unnecessary materials are NOT to be put into the sewer. The digested treatment and secondary treatment systems operate biologically with living organisms and these substances kill the organisms vital to this treatment process.

“Flushable” wipes are not flushable, but have been seen more and more in the marketplace in recent years. There was a large campaign to include the word “flushable” on packaged items and it has been a big debate in the sewer industry.

The word “flushable” is used to encourage the purchase of these items, but please disregard the word “flushable” on these products, as they often are NOT flushable. Not only could city mains become clogged, but often private sewer lines become clogged first, creating unnecessary expense and mess to the homeowner.


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