Council updated on sewer project

Lime Springs - Katie Sterk of Bolton & Menk engineering firm updated City Council on the wastewater treatment project that Lime Springs has been investigating for several years.

Sterk gave the latest numbers on a new plant, which ranged from $3.8-12 million.

The Department of Natural Resources has been cracking down on the amount of ammonia nitrogen, E. coli and other elements being released from sewer plants. Lime Springs, along with many other towns in Iowa, needs to update or replace its system. The local plant was built in 1985 and has lived out its usefulness.

In 2015, Lime Springs was given a disadvantaged community status, which allowed the City more time to plan for a new wastewater treatment plant. In that time, water and rates were both raised to show the DNR the town is trying to comply.

Bolton & Menk are again applying for the disadvantaged community status, for the ammonia limit only, which may or may not be accepted.

For the past three years, the company has submitted an annual progress report or alternatives report by Aug. 1 to the DNR. This August, an alternative implementation compliance plan needs to be submitted.

Sterk explained the existing three-lagoon cell plant aeration system and improvements are needed due to age and poor condition.

 

Ammonia

One thing is certain — the current plant has a problem with ammonia. When the water temperature is 45 degrees or above, the ammonia is automatically removed from the water. That’s great in the summer . . . not so much in the winter months.

Sterk gave several removal alternatives.

• Bio-Dome System — This would put submerged aerator domes in a grid throughout the existing ponds. It is affordable, but has not been approved by the DNR, so it is not feasible.

The domes themselves are small and underwater. They’re meant to push concentrated air up from beneath to better oxygenate the water, rather than a dome over the pond system. 

• Mechanical Treatment Facility — This plan works well and is flexible in that additions can be made to the facility in the future. The downfall is the construction cost is $8-$12 million.

• NitrOx System — This would use the existing lagoons, but would need new equipment and facilities as well. It is effective in Iowa but costs $3.8-$4.8 million to build.

• Sterk offered two other alternatives, but neither have been tested in northern Iowa.

 

Disinfection

Another piece of the plant that needs attention is disinfection for E. coli. Sterk had two alternatives.

• Ultraviolet Disinfection — This option is most effective and has no chemicals. In the report given to Council, Bolton & Menk stated, “The costs for the ultraviolet disinfection system to comply with the E. coli limit are not excessive — approximately $750,000 for an installed system.”

“Not excessive” in this case means it is less than a million and will probably need to be done regardless of whether the town gets disadvantaged community status.

• Chlorine disinfection — This is affordable for the town, but may be less desirable because chlorine would need to be added to the lagoon effluent to disinfect it, and then the water would have to be de-chlorinated before being discharged.

Obviously these are some big numbers for the small community of Lime Springs. That means rates will have to be raised, but that has been the case for several years already.

The council has not yet looked into how much rates could increase.

At the meeting, Sterk mentioned an amount of $126.37 as an equivalent average user cost for a $3.8-$4.8 million project with no grants or financial assistance. This number is used by the DNR for an affordability calculation in order to determine eligibility for the Disadvantaged Community Status. It is also used for any future grant and financing applications with SRF, CDBG and other programs. If the City receives Disadvantaged Community status, moving forward with the full project may not be required at this time.

[SRF is State Revolving Fund (which is a source for funding for drinking water and wastewater treatment projects and is administered in Iowa through the Iowa Finance Authority and the DNR). CDBG is Community Development Block Grant (which is a federal program offered through USDA-Rural Development and administered in Iowa by the Iowa Economic Development Authority).]

The engineer explained that the amount of $126.37 is calculated as the monthly cost per each of the 238 users to pay for the project over 30 years if user rates are the only way the City is paying for it. It is not meant as a suggestion for user rates, and this does not mean that the council will opt to raise rates to this amount.

 

More decisions

Besides choosing ammonia and disinfection solutions, the City Council has other huge decisions to make in the near future. 

A few things they are looking at include updating the sewer mains in the streets of town. This would be a two-fold solution. The old mains would be replaced, and the streets would be resurfaced.

This will also be an expensive project, making the sewer plant too expensive to complete, which would allow the City to get grants to do it. The problem may be that no grants would be available.

Or the City could just do the sewer plant, which would leave the street project unfunded.

If Council is given disadvantaged community status, does it continue forward or kick the problem down the street and wait another five years? It would be a crap shoot on whether the project would escalate in price or maybe new technology would be found to do the project cheaper.

Any way a person looks at it, the residents of Lime Springs are looking at higher sewer prices and likely higher property taxes.