NASHVILLE — Hamilton County's ongoing effort to address its sewer problems has received a state assist in the form of $1.86 million in low-interest planning and design loans for five plans or projects under consideration by the county's Water and Wastewater Treatment Authority.
Tennessee Local Development Authority members approved the five-year, $500,000 loan as well as additional loans for four other WWTA studies last week. All the loans carry a 0.79% interest rate.
Among plans WWTA is studying is whether to replace its existing Signal Mountain Wastewater Treatment Plant with a pump station and force-main pipeline that would connect to the city of Chattanooga's sewer system.
"Really, what we're determining is whether or not we're going to keep the existing Signal Mountain treatment plant and upgrade it or whether or not we're going to build a pump station and pump to Chattanooga," WWTA Executive Director Mike Patrick said Thursday in a phone interview.
Chattanooga and the county have separate sewer systems.
But Patrick quickly noted that "pumping into Chattanooga has its own set of issues in that right now the (inflow and infiltration) that comes off of Signal Mountain is really more than Chattanooga can handle at the point of connection. We're still sort of in the study stage." Infiltration and inflow are excess water that gets into sewer pipes from groundwater and stormwater.
The Signal Mountain plant is on Suck Creek Road.
While the state loans won't cover the entire cost of the studies, Patrick said, the interest rate is "very attractive" and helps spread out the costs of planning or design to try to help out with the burden to ratepayers.
Regarding the Signal Mountain treatment plant, Patrick said "on a day like today, it's working fine. On a day in the wintertime when we have these large rains, we go from, oh, 400,000 gallons to 4 million gallons a day — it doesn't work so well."
But stressing that the authority is "still in the study phase" on that, Patrick said "we're probably leaning more towards actually keeping the wastewater plant there on Signal Mountain. But that's still to be determined."
Other state loans approved for WWTA planning and design work are:
— $587,000 to plan and design the rehabilitation of sewer lines to reduce inflow problems from cracked pipes or holes in manholes as well infiltration problems in four sewer basins in the Soddy-Daisy area. The goal is to improve hydraulic capacity and eliminate sanitary sewer overflows during heavy rain events.
The money will help "figure out how to get the most bang for our buck in those basins in Soddy-Daisy," Patrick said, calling it a "shame" to have to treat rainwater.
— $350,000 for a feasibility planning study on collection system rehabilitation on several sub-basins along streams in the Signal Mountain service area. It will examine the possibility of installing a low-pressure sewer system to replace some gravity sewers along streams or ravines.
A gravity sewer relies on energy resulting from a difference in elevation to carry away wastewater. A pressure sewer system uses grinder pumps to grind sewage into a slurry to transport it more easily. The pressure system uses smaller diameter pipes that can be less expensive and easier to install.
"We've identified basically the worst offender basins up there, that's what we're looking at," Patrick said.
Patrick said in some instances, the lines were placed a half-century ago in places no longer considered acceptable today. Some lines were close to creeks and decades later are now actually in the creek.
Both the county sewer system as well as the city of Chattanooga's have had to hike their rates in order to comply with U.S. Environmental Protection Agency requirements to limit sewer overflows and other water pollution runoff.
— $276,670 for planning and design on rehabilitating sewer lines in sewer basins 5, 6 and 7 in order to improve hydraulic capacity and eliminate sanitary sewer overflows in Red Bank. The basins are "basically" in the middle of Red Bank, near City Hall and up toward the Ashland Terrace areas.
"Those are the three worst basins in Red Bank and contribute the most inflow and infiltration," Patrick said.
— $150,000 for a feasibility study on whether to install a new pump station near Alexian Village on Signal Mountain to transport waste to the Signal Mountain Wastewater Treatment Plant and address "chronic" sanitary sewer overflows.
During Wednesday's meeting of the Tennessee Local Development Authority, state Comptroller Jason Mumpower, TLDA's chairman, noted that some agencies, including the Hamilton County Water and Wastewater Authority, were late in submitting recent required audits.
In a letter dated May 20, 2022, submitted by WWTA to TLDA, WWTA accounting firm Mauldin & Jenkins noted the firm had experienced "significant turnover in key positions with the sudden and unexpected departure of the previous engagement partner and engagement manager" and cited that as the cause of the late filings.