Signal Mountain’s sewer system represents 8.2 percent of the entire system that the Water and Wastewater Treatment Authority maintains, yet 71 percent of overflows throughout the system occur on Signal Mountain, officials said at a meeting of the Signal Mountain Council. The WWTA presented a $40 million plan aimed at alleviating the problem.
The sewage overflows are visible at manholes but even worse, they occur in the middle of the many creeks and tributaries leading to them. That is because when the sewer system was built on Signal Mountain 50 years ago, pipes carrying the wastewater were often put in stream beds where gravity controls that water leading down the mountain. During periods of rain, heavy contamination of E Coli occurs in many of the creeks when there are overflows. Eric Brooks, WWTA chief engineer, said that the water clears itself after about 48 hours, and the tests become negative for E Coli. However, the contaminated water ends up in the Tennessee River.
Sewage has been a problem on Signal Mountain for 50 years, mainly because of where the pipes were located. And now many of those pipes in the streams and underground are cracked and broken. Remediation is complicated because of the underlying rock. WWTA is under a consent decree to eliminate contaminated water from getting in the Tennessee River. The target is to reduce inflow and infiltration and eliminate sanitary sewer overflows. If the WWTA does not take care of the problems, Mr. Brooks said the federal government would likely get involved and do the work. The city of Signal Mountain may not be able to have as much input if that happens versus letting WWTA do it. WWTA is holding public meetings for residents to hear the plans and make comments.
At the town council meeting Monday night, Mr. Brooks and Neeley Langham from Jacobs Engineering presented the plan that has been developed to clean up the water and to bring Signal Mountain into compliance with state and federal requirements.
A system has been designed to move sewage out of the pipes that are now in Shoal Creek, which is in Green Gorge Park, as well as other waterways. The wastewater will be moved to two pumping stations, both along the edges of the park. The locations were determined as the most effective places based on gravity and where there would be the least interruption to the park. A new Druid Road pump station will be on Green Gorge Road between Fern Trail and Druid Road. A Ravine Road pump station is planned on Ravine Road near Whippoorwill Drive. The property is owned by the town and WWTA must be given an easement to build there. There are no alternative places to put the stations, the council and public were told, because of the terrain, topography and the amount of rock. The old pipes and manholes will be abandoned.
The 50x70-foot facilities will be different than any others in the area, said WWTA Executive Director Mike Patrick. But this is because of aesthetics, not new technology. The difference is that these will be designed to fit into the appearance of the existing neighborhoods, with fencing or walls. The designs are not yet finalized.
Each of the two facilities will have a small building and submersible pumps that have electric motors that do not produce much noise, and are designed to have no odor. However, they are not completely sealed, said Mr. Brooks. There will be chemical tanks at the locations for odor control. There will also be a backup diesel-powered generator in each station so that if power is lost during times such as ice storms, the pumps will continue to operate. The plan is to place them 10 feet from the road and keep all the trees possible. Any trees removed will be replaced. And landscaping will be added around the perimeter. There is also the ability to move the stations back farther into the park, which would be less visible from the street, but would require more trees to be cut down. And it will be necessary to have a driveway leading to the stations because large machinery is used for maintenance.
The pump stations are the first phase of the project. Another part of the plan is low pressure pumps that will be needed in areas of high infiltration and inflow of ground water and stormwater entering the pipes. This part of the system puts a grinder pump at individual houses. They grind up the sewage and pump it to sewer mains in the street. This is the system that has been in use in Lookout Mountain, Georgia for many years. The grinder pumps would need to be installed at 37 houses in one neighborhood and at 208 homes in a second neighborhood. These pumps can be camouflaged with an artificial boulder to cover them or a green disk that lies flat on the ground. The WWTA would be responsible for maintaining this system.
A third phase of the plan will be to rehabilitate broken pipes using liners. The broken and cracked pipes are where the excess water enters and overwhelms the sewer system.
The town council room was not large enough to hold all the residents who came to the meeting. Around 15 residents who spoke were mostly property owners who lived near the proposed locations for the pumping stations, with homes on Fern Trail, Ravine Road and Druid Drive. Most people who came were aware of the problem with contaminated water on the mountain, but many told the council that they were not aware that the project was so far along, and they claimed a lack of communication between the town and the citizens.
Tennessee Department of Environment and Conservation (TDEC) put Signal Mountain under a building moratorium in 2007 due to the sewer problems. New construction has not been allowed to connect to the existing sewer system, but instead had to use septic systems. Some who spoke said they were glad to hear there is a plan to solve the problem. One speaker said her neighborhood that is currently on septic tanks would like to be connected to the sewer system. Another said that most residents were aware of the problems and that she had first heard of it in 2007. She said meetings had been held, including two planning commission meetings in July, prior to their recommendation to the council for approving the plan. She urged those who were unaware to listen to the meetings on the town website, or come to them, to know what is going on. She said that, although Green Gorge is a town park, the solution has to be where the problem is.
Of the residents who addressed the council, roughly half were opposed to the proposed plan, half wanted more information and several expressed support for the plan. Concerns about the impact of building the pump stations include the effect they will have on the nearby property values, and the threat of odor, noise and light pollution. The number of trees that will have to be removed is a concern and some questioned if it would be less noticeable to place them farther off the road, which would require cutting even more trees and a longer driveway. One resident said there were no signs warning of the pollution at the entrances to the park, which was disputed by Vice Mayor Elizabeth Baker. Several speakers wanted more studies done and to be shown alternative engineering plans for a solution. The pumps will need new sewer pipes that would go under the roads where there is rock and would need to be blasted, said one speaker. Others wanted to see more plans and for a decision to be slowed down.
Maintenance and repairs of the sewer system by WWTA is mostly done with money that comes from sewer bills. If WWTA does not take care of the problems, it will be fined and then will have to pass the charge onto its customers. For this project American Rescue Plan Act funds are available. That money is eligible to use for water and sewer infrastructure. There is a condition that it has to be obligated by the end of December 2024 and spent by Dec. 31, 2026. The town council does not want to miss the opportunity for a solution to the problem by the money being used elsewhere for other projects.
The council plans are to have a question and answer public meeting on Aug. 7. There will also be a special called council meeting to review the questions and any additional conditions presented to the WWTA before the regular council meeting that will take place on Monday, Aug. 14. A vote to approve granting easements for the two sewer pump stations is expected to take place at that meeting.