BLUFF CITY, Tenn. (WJHL) – Though they may look like they’re getting worse, Bluff City’s sewer issues are actually getting better, an engineer told Board of Mayor and Alderman members Tuesday night.
Dave Wilson of Mattern & Craig Engineering briefed members Richard Bowling, Eric Ward and Jeff Broyles — Mayor Irene Wells and Alderwoman Carole Keith were absent — at city hall.
Wilson explained that the city has requested an extension on its settlement agreement deadline with the Tennessee Department of Environment and Conservation (TDEC). That Dec. 2016 agreement gave Bluff City until Jan. 31, 2020 to comply with a list of improvements.
Wilson said the city is very close to compliance, and outlined about $600,000 worth of projects that should go a long way toward alleviating overflows at a sewer manhole at 4434 Bluff City Highway. The manhole is near the “Igloo pump station,” which handles nearly all the city’s wastewater before it flows into the Bristol system and on to be treated.
During heavy rains, stormwater infiltrates the sewer system and when it reaches the 300 gallon-per-minute Igloo station, the pump can’t keep up. Bluff City typically calls septic trucks in those instances, but often the line backs up and a manhole several homes up from the station overflows.
A series of more than five overflows in a 12-month period during 2015/16 prompted the initial TDEC order.
Much of the remaining money from a hybrid loan/grant from USDA was slated for use on water treatment plant upgrades. Wilson told members the USDA agreed Bluff City should change course at a meeting Jan. 27.
“They said, ‘we want you to use this money to go after that agreed order — we’ll talk about the water plant afterwards,'” Wilson said.
Wilson showed proposed work on three main projects. One involves replacing two pumps — one aging, the other completely out of commission — at the “Garage pump station.” Additionally, flow from that pump station would be rerouted into a currently unused line and enter the main line downstream of the Igloo station. That would reduce load there by about 10 percent.
Another project would replace an old line along Railroad Street. That, too, should reduce peak flow at the Igloo station. The city will also consider a smaller pump there, which it could route through the 4-inch pipe that was used prior to the most recent Igloo pump station upgrade.
Wilson also recommended about $100,000 worth of flow meters and telemetry equipment for each pump station. It all left Alderman Jeff Broyles encouraged.
“Bluff City is moving forward,” Broyles said. “There’s three basic phases to this project and tonight in hearing what our engineer reported, with the change order, I definitely think we’re going to leap forward to be able to prevent these overflows.
“We have a lot of work to do on our infrastructure and that will continue for years on, but I’m excited to vote for this and hopefully we can go ahead and get this project put together and take a little better care of our citizens.”
What about the overflows?
Wilson said the installation of replacement sewer lines in areas of town during earlier phases of the project has actually increased the amount of water reaching the pump stations during heavy rains. That’s because the new lines don’t allow water to “exfiltrate,” or leach out into the ground.
When the weather is normal, the amount of water reaching Bristol’s system for treatment has decreased by nearly 50 percent over the past two years as the initial work has taken effect.
That saves the city money and is great for the long term, Wilson said, but as long as stormwater continues to “inflow” and “infiltrate” into the sewer lines during heavy rains, the result is more water in the system at those times. That occurs as water overloads the stormwater system, runs off roof drains, and in the case of a remaining old line along Railroad Street, infiltrates old pipes and joints.
When volumes are too high, the Igloo pump struggles to keep up and the lines begin backing up. The manhole at 4434 Bluff City highway typically bears the brunt of that backup, with overflows passing across Mary Moore’s property and making their way to Boone Lake.
A Bluff City report to the Tennessee Department of Environment and Conservation (TDEC) shows that an estimated 24,000 gallons was released from the manhole Feb. 6. Pump trucks hauled another 53,300 gallons away from the pump station before that water backed up to the manhole.