Jun. 4—Decatur Utilities is planning its most expensive project ever with close to $120 million being spent on two sewer system improvements as part of its effort to stop sewage overflows.

One project involves renovation of the wastewater treatment plant on Alabama 20 and the other involves replacing with much larger pipe a collector sewer main that feeds into the treatment plant.

DU spokesman Joe Holmes said the renovations of the sewer treatment plant would include “some new odor controls. We do expect improvements with the new equipment, but because it a wastewater plant, odor will never be completely eliminated.”

The DU board voted in a called meeting last week to recommend approval of the improvements to the Dry Creek Wastewater Treatment Plant and Moulton Street collector sewer main.

“We think these two projects are going to be generational for the wastewater system in Decatur,” DU General Manager Ray Hardin said.

Hardin said the city “has had a problem with sanitary sewer overflows (SSOs) for a long, long time, specifically caused by rain getting into the sewer system.”

DU was sued by the state in 2019 because of the overflows. The DU board approved a plan in 2020 to perform extensive repairs and replacement of portions of the sewer system as part of its settlement of the state’s lawsuit, which was finalized in March 2021.

Construction for both projects, expected to receive City Council approval Monday night, would begin later this summer. DU could then complete its compliance with the settlement agreement by March 29, 2026, Hardin said.

“Internally, we want to have no overflows, but the agreement was to minimize SSOs,” said Hardin, who added that they haven’t had any rain-induced overflows in two years since the project began.

As part of the settlement with the state, the utility board approved a 10-year plan funded by $165 million in bond proceeds paid for with a customer rate hike.

DU has made $3.84 million in interest on the unspent bond proceeds to date, but it will need another $15 million from the wastewater operation’s cash reserves or possibly another bond issue to complete the projects, Hardin said.

Hardin said they originally created a budget to replace 1 million linear feet of pipe, including 800,000 feet of clay pipe and 200,000 feet of cement pipe, in 10 years. They also planned to replace the Clark Springs collector and lift station 7 at the Pines in Northwest Decatur.

However, Hardin said they revised the budget to do the headworks and Moulton Street collector projects. This required reducing by half the amount of pipe replacement that is being funded with the bond issue, he said.

—

Sewage backs up

Jimmy Evans, Gas, Water and Wastewater operations manager, said the wastewater system has a “surcharged condition” in dry and wet weather conditions.

Evans explained that a surcharge condition is when the wastewater’s flow into the collector lines “isn’t moving quick enough so it begins to back up into the system and ultimately creates sanitary sewer overflows.”

For example, Hardin said there’s a line that runs along the ditch on the west side of Central Parkway across from the DU offices. Wastewater backs up and then overflows from this line.

In addition to cracks in the old pipes, Hardin said SSOs also result when sewage backs up in the system. The plan addresses backups.

—

Collector project

One cause of backups is when the sewer mains are too small, so DU is planning the $22.62 million installation of a new Moulton Street collector 60-inch sewer main to upgrade from 20- and 24-inch mains while replacing aging gravity sewer.

Evans said this will provide significant flow capacity increases for moving wastewater collected from various areas of the city to the treatment plant.

Evans said the collector starts at Moulton Street. It follows the Dry Branch Creek easement and crosses Finley Drive, to the Norfolk Southern railroad south of Davis Street Northwest.

He said they will then tunnel underneath the railroad. The new main will continue along Davis Street, cross the Leon Sheffield Magnet Elementary School parking lot on the east side of Decatur Fire & Rescue’s Station 2. They will tunnel under Alabama 20 and connect with the new head station at the treatment plant.

—

Pump station

The other part of the plan is replacing the influent pump station and headworks at the treatment plant at Decatur Utilities’ wastewater treatment plant, located on Alabama 20 at the Tennessee River, next to Ingalls Harbor, for $90.5 million.

Tom Cleveland, DU water-wastewater resources manager, said this part of the plant went online in 1958.

“It’s the oldest part of the plant,” Cleveland said.

Cleveland said the current wet well doesn’t meet submergence requirements. The new wet well will be 11.62 feet deeper, dropping the depth below ground to 519 feet. The added depth, he said, should help eliminate the surcharge problem and create more capacity for future growth.

The DU board voted to award the contract for the influent pump station and headworks to Garney Construction Co., of Nashville, Tennessee, for a low bid of $90.5 million. Thalle Construction Co. was the other bidder at $97.9 million.

DU put a 5% construction contingency of $4.53 million in its plans for this project to cover any unanticipated cost increases, Evans said.

The board awarded the contract for the Moulton Street collector main replacement to John Plott Co., of Tuscaloosa, for a low bid of $22.62 million. Six companies submitted bids. Cleary Construction was the next lowest bid at $26.62 million.

DU put a 10% construction contingency of $2.26 million in its plans for this project to cover any unanticipated cost increases.

— bayne.hughes@decaturdaily.com or 256-340-2432