City Council hears report on plans to upgrade water treatment plant
Published 3:55 pm Tuesday, August 25, 2020
Continued improvements to the City of Albemarle’s Wastewater Treatment Plant were discussed at Albemarle City Council’s recent meeting.
Through 2019, the plant had a number of non-compliant events at the Long Creek plant, including sustained high-flow events and low biological strength.
Adam Kiker of LKC Engineering presented a plan to City Council to make improvements to the plant, with a total project budget of $16.7 million.
The current system using surface aerators has low efficiency, consuming a lot of energy, according to Kiker. The mixers have to be either on or off, and the maintenance and replacement costs per year currently are budgeted at $60,000.
Kiker said this comprehensive plan “is geared towards bringing this plant into compliance and satisfying the electrical upgrades identified in 2013” while making the upgrades “in one fell swoop.”
The plan begins with converting the aeration to a fine-bubble diffusion. This method uses pipes at the bottom of a basin with round diffuser heads rather than surface aerators.
The presentation stated fine bubble diffusion will allow basins to be completely mixed and operators are able to control the dissolved oxygen by throttling the air. There are no mechanical compliments in the aeration basins which allows for proper biological treatment,
Basins 1 through 4 will be converted into flow equalization basins. The basins will then be cleaned with the disposal of accumulated sludge. Only two basins will be needed for the city’s capacity of 8 million gallons, meaning the other two basins can be used as storage.
The new process will also use less than half of the electricity which could be a savings of more than $180,000 annually in electricity costs.
A new supervisory control and data acquisition system (SCADA) will be added to the plant while an electrical systems upgrade will support the new aeration system, according to the presentation.
Kiker said the costliest parts of the plan are the aeration conversion system and the electrical upgrade.
Aeration conversion electrical upgrades would cost less ($4.2 million) than the 2013 plan construction estimate of $7.17 million.
LKC also presented a slightly less expensive project which would maintain the current aeration process of $12 million but implement the electrical upgrades from the 2013 plan.
Albemarle City Manager Michael Ferris said the city was already on the $12 million path from the 2013 plan, acknowledging the electrical issues might lead to overflows.
“What we are looking to (the board) is the fine-bubble system,” Ferris said, noting the savings in electricity over a 20-year loan period “closes the gap fairly significantly.”
“Should you get a large volume of rainwater, by doing this system, we would be able to treat what is there more effectively and efficiently,” Ferris added. “Secondly, we leave two of the basins open for the overflow. That means it doesn’t overflow, spill and cause those issues. There’s a lot of benefit to this…that’s the crossroads we are at because we don’t want to go down one path and have to back up or spend money to duplicate or go a different route from what we have spent money on so far.”
Kiker said the more expensive project tackles the compliance problem and fixes the maintenance issues.