The Carmi City Council only took up one real matter during its February 4th meeting, that being representatives from Brown and Roberts Consulting Engineers and Land Surveyors, headquartered in Harrisburg. The topic…sewage; or more accurately phosphorous.
Back in August of 2019, the Illinois Environmental Protection Agency issued Carmi a final NPDES permit. NPDES stands for National Pollutant Discharge Elimination System. The paperwork attained at the meeting lays out expectations for the municipality to prepare and submit a feasibility study within 18 months showing how Carmi plans to reduce it’s phosphorous discharge levels to a potential future limit of .5 milligarms per Liter. It was revealed at the meeting that Carmi currently discharges at a level of 2 mg/L and is within the time period for lowering that limit to 1 mg/L, that according Matt Tosh, also of Brown & Roberts.
Jim Brown on behalf of Brown and Roberts, spoke of an energy grant that sewage treatment plant operator Don Davis had been made aware of through the IEPA. A million dollars statewide has been made available for projects. Applications are due by February 28th and the maximum grant is 85% of the total project cost.
To better understand where we go next, it’s important to understand on a basic level how wastewater treatment plants operate. The municipality has an oxidation ditch in which rotating brushes oxidize the wastewater as part of treatment. The original energy assessment called for replacing just two of the four sets of rotating brushes. That project cost was estimated at $127,500 with a payback period of 3.1 years. Brown and Roberts indicated at the meeting they’d done additional work and estimate the project to cost $605,000 for replacement of all four sets of rotating brushes. So why the near half million dollar difference for what appears to be just two more sets of brushes?
“Well there was never any installation (and there were some ancillary parts too). There was also electrical costs that were not included. There’s gotta be electrical improvements to the facility. Our cost estimate has some contingencies. Usually going into a project you have some contingencies. And then the engineering costs also. You’re probably at least at $470,000 in just construction versus the $127,000.”
The project payback on the updated assessment…46 and a half years with the city’s minimum share of estimated total costs expected to be in the neighborhood of $90,750.
There’s much more to the permit and decisions will almost certainly have to be made moving forward regarding the sludge bed and how to most cost effectively remove phosphorous. Currently, it’s estimated the city spends about $30,000 annually on chemicals to remove the phosphorous they do. As of now though with a deadline of February 28th to send in the grant application, Council decided to spend the $3,000 to have Brown & Roberts complete the full application and apply for the grant. The motion passed unanimously. The city will have until March 1st of 2021 to have it’s phosphorous removal feasibility report and discharge optimization plan submitted.
