SIDNEY — Shelby County Engineer Robert Geuy, along with Chief Deputy Engineer Nick Miller, Shelby County Sewer District Director Tyler Shuster, and representatives of Jones & Henry Engineers Ltd. gave a presentation regarding upgrades to the Lake Loramie wastewater treatment plant during a meeting of the Shelby County Commissioners on Thursday, Dec. 13.
Geuy began by referencing the most recent National Pollutant Discharge Elimination System permit issued by the EPA in 2015 for the treatment plant. Along with this permit, the EPA issued a compliance schedule, which is an order for required action.
“There were a couple—probably more than two—issues in there that we have to begin the address,” Geuy said.
Pete Latta, principal and director of construction services for Jones & Henry, presented a detailed PowerPoint examining the history of the water treatment plant, the current issues, and possible solutions.
The Lake Loramie Wastewater Treatment Plant was constructed in 1992, two years after the Sanitary District was established. The plant uses BIOLAC, which is an acronym for Biological Wastewater Treatment System using Aeration Chains.
Two of the requirements within the EPA compliance schedule, Latta said, include reducing the phosphorous and eliminating the overflow from the equalization basin, which is designed to provide consistent flow to downstream processes by retaining high flow fluctuations.
As part of the compliance schedule, the Sewer District was required to begin monitoring the phosphorous levels in the water.
“In the monitoring period, what we’ve found is that we’ve exceeded the tentative limit of 1.0 mg per liter for both 2016 and 2017,” Latta said. “What that’s indicating is that the plant is just not able to treat for phosphorous.”
Jones & Henry Senior Engineer Joseph Hotz added that when the treatment plant was built, it was never intended or designed for the removal of phosphorous.
It was also noted that during the 2016 and 2017 monitoring period, the EQ basin overflowed 24 and 46 times, respectively. Each basin overflow is a permit violation.
“The BIOLAC system was designed for an average day flow of 0.4 MGD (millions of gallons per day) and a peak of 0.6 MGD,” Latta said.
The Fort Loramie WWTP is operating close to its design point, at around 87 percent of the average.
“That’s a key trigger point for the EPA,” he continued. “When you start operating at over 80 percent of your design capacity, the EPA starts asking the question, ‘What are you going to do?’”
With regard to peak flow, Latta said, the treatment plant operates even closer to design capacity, at 97 percent of 0.6 MGD.
During the two-year monitoring period, the influent flow rates exceeded peak design flow rate of 0.6 MGD 304 times.
High flows, greater than 0.6 MGD, to the plant cause hydraulic overloading, which lowers the hydraulic retention time in Cell 1 of the BIOLAC, leading to an inability to provide adequate treatment and subsequent violations.
Latta highlighted the inefficient ammonia reduction, phosphorous removal, and E. coli destruction.
Latta also noted deficiencies within the structure of the plant itself, including an uneven aeration grid, and a non-operational clarifier, which is a settling tank for continuous removal of solids deposited by sedimentation.
The plant’s clarifier is currently ineffective, Latta said, due to corrosion of steel weirs, some of which are difficult to reach for cleaning, as well as a build-up of scum, algae, and duckweed.
Deterioration of the existing BIOLAC liner and lagoon embankments also need to be addressed in order to avoid leaks and structural failures.
Latta presented recommendations for ways to address the issues and deficiencies within the wastewater treatment plant. This is laid out in three possible phases.
It was noted that not all three phases may be necessary, but a combination of two may be ideal.
Phase 1 addresses the immediate needs regarding the current compliance schedule for phosphorous removal and elimination of E. coli violations. This would involve the addition of two new clarifiers.
“By building those, it allows you to precipitate out phospherous,” Latta said.
The probable cost of these new structures is estimated around $1.2 million. With other additional costs associated, including things like general site improvements, electrical and controls, and chemical feed and bulk storage, as well as labor costs, the total cost of phase 1 is estimated around $2.5 million.
Phase 2 involves the rehabilitation and upgrade of the BIOLAC. This includes electrical and controls rehabilitation, and lagoon liner replacement, among other structural renovations.
Phase 2 is estimated to cost around $838,000.
Phase 3 involves the addition of a new oxidation ditch, which would cost an estimated $1.8 million. With yard piping and site work, electrical and controls, and labor costs, the total estimated cost of phase 3 is around $2.7 million.
Geuy noted that funding for this project is still being sought. At this point, he said, until an exact course of action is decided on, it is a bit difficult to apply for grants or seek funding.
“We know the long-term solution is phase 3,” he said. “Our preference, dollars and cents-wise, would be to skip phase 2 and go right for 3, but we don’t know what monies we can find.
“I think we’ve all agreed that we should proceed to take the next step and get a preliminary design. That design can be used for the funding agencies, and for negotiations with the EPA of our time schedules, as it shows progress.”
Even before the preliminary design is drawn up, Geuy suggested a meeting with leaders of Fort Loramie is necessary.
“They’re aware of these compliance issues, so they know that we’re working on it,” he said. “I think they should be a part of this; they’re partners in this.”
Commissioner Tony Bornhorst suggested Latta give the same presentation to Fort Loramie representatives. A meeting is likely to be scheduled for sometime in January 2019.