Across the United States, there are more than 30,000 protected areas managed by an array of federal, state and local authorities. These spaces have been identified as areas in need of protection and management in order to conserve the natural landscape. Located in Marion County, Tennessee, Sequatchie Cave is one of 85 natural areas in the state according to the Tennessee Department of Environment and Conservation (TDEC). Easily accessible to the public, the cave’s frequent use and daily traffic flow had started to take a toll on the site. KCI teamed up with TDEC to design and implement on-site improvements for this natural area.
Originally a popular roadside park, visitors often stop by Sequatchie Cave to feel the natural breeze blowing out of the cavern or to cool off in the water flowing from the mouth of the cave. This creek, also known as Owen Spring Branch, is a tributary of the Little Sequatchie River and is home to many aquatic and cave species. In 2001, this site was designated as a state natural area because of the endangered and rare species that the cave and its cold spring water support, including the Royal Snail and the Sequatchie Caddisfly, both exclusively found in Marion County. The Royal Snail resides in the muddy area along the edge of the bank, while the Sequatchie Caddisfly can be found on vegetation overhanging the stream and on logs within the creek.
With little protection between the aquatic habitat at the cave and the adjacent chip and tar parking area, stormwater from the road was flowing down the bank creating a concentrated area of erosion. This was causing the chert, a fine-grained sedimentary rock that had previously been placed on the bank to help with stabilization, to erode directly down into the pool of water at the mouth of the cave and compromise the habitat of the caddisfly and snail. TDEC reached out to KCI to help implement conservation efforts. Our team was asked to plan and design onsite improvements that could help protect the water quality and the habitat for these species.
Understanding the community’s investment in the cave, engineers knew that public outreach and partnership would be essential throughout the project. Our team participated in several public meetings where they educated the locals about the area’s importance and explained how they could support the efforts. Using input generated from these meetings, engineers and scientists proposed improvements including reducing the impervious area that was draining to Owen Spring, addressing the stormwater coming off of those surfaces, stabilizing the bank and replacing the chert material and enhancing the habitat for the targeted organisms. With final designs complete, the firm’s in-house specialty contracting group, KCI Environmental Technologies and Construction (ETC), submitted a bid and was awarded the construction phase of the project.
To stabilize the bank, equipment operators had to carefully remove all the chert, making sure none of the material endangered the species in the water below. Field crews were then able to begin building vegetated soil lifts. Topsoil was wrapped in biodegradable matting to create stacked layers with cuttings from willows and dogwoods between each layer. This vegetation in the lifts, once grown, will help reduce erosion on the bank.
To address the impervious area issue, our team worked with the county highway department to cut and tear out the parking lot asphalt, reducing the size of the lot and replacing a portion of it with pervious concrete. A bioretention-based best management practice (BMP) was also installed to further treat stormwater runoff before it enters the pool of water at the mouth of the cave.
Boulders and a small fence were put in place at the top of the bank to direct visitors where to walk without harming the environment. However, knowing that the public would still want to access the site, a planned path was designed and stone steps were installed to provide an entry point to the water. The state added a kiosk at the top of the bank so visitors could learn more about the importance of the site and the endangered species living there.
As a designer, it was really nice to have our construction crew out here doing the work. Our team's close working relationship allowed us to easily bounce ideas off of each other throughout the process.
Adam SpillerPractice Leader, Senior Environmental Scientist
With construction complete and watershed improvements implemented, the public is now able to enjoy this natural site without endangering the landscape or the species that live there. Future research, data gathering and conservation efforts will continue to ensure that water quality and both species are being protected.