By Bart Netherland, EI
For the past year and a half, a small team of LDA engineers has been using innovative design approaches to help transition an existing mid-century wastewater treatment plant to a more efficient, durable, environmentally sensitive facility. At the center of this large project is the Central Wastewater Treatment Plant, which was built in 1958 in Nashville on the banks of the Cumberland River where the Kerrigan Tunnel empties into the river.
The project is being administered by The Clean Water Nashville Overflow Abatement Program, an initiative established in 2011 by Metro Water Services to meet the Clean Water Act requirements and promote the environmental health of the Cumberland Water and its tributaries. LDA Engineering is serving as a sub-consultant on the project under Brown and Caldwell.
Dating back to the mid to late 1880’s, the city of Nashville had covered its creeks and used them to convey sewer to the Cumberland River. Starting in the 20th century, cities began constructing pipelines to convey sanitary sewage along with stormwater to treatment plants to improve water quality.
A key area on which LDA team members are involved is site civil work, which includes redesign of the site’s stormwater, paving, grading, and yard piping. In the past, cities often dealt with high levels of stormwater by focusing on controlling the rate of water flow. Today, the goal of cities and civil engineers is to keep more water on site, with a design emphasis on getting water to percolate into the soil. Strategies include removing unnecessary concrete and asphalt pavement, which reduces stormwater run-off and allowing natural grasses to act as a filter before the water percolates down into the subsoil. In addition, retention ponds are being used on the site to capture runoff during rainfall events.
A second area in which LDA engineers are focused is the South Secondary Effluent Conveyance facility. This involves the installation of a pipe between the current plant and a redesigned final disinfection treatment area using ultraviolet light to disinfect the effluent. The 84-inch fiberglass specialty pipe (FRP) is being used to increase the flow from the wastewater treatment plant.
While new development plans are likely to include elements of environmental sustainability and efficiency, the Central Wastewater Treatment Plant project is unique in that it gave the engineering team an opportunity to take an existing site and introduce the new approaches.
– Bart Netherland, E.I., is an engineer at LDA Engineering in Nashville, TN. He is a 2018 graduate from the University of Tennessee – Martin with a B.S. in Engineering in pursuit of his P.E. license. Bart is an active member of professional organizations including the American Water Works Association (AWWA), the American Public Works Association (APWA), and the Tennessee Society of Professional Engineers (TSPE).
Are you attending the 2019 Water Professionals Conference? Look for LDA team member Steve Drummer’s presentation “Sustainability Design for the Central Wastewater Treatment Plant” to learn more on this topic.