When the Maytag manufacturing plant in Cleveland, Tennessee, was flooded in the spring of 2003, municipal leaders designated a flood protection project for the Woolen Mill Branch drainage basin as the City’s number one priority.  Following aggressive funding efforts led by Congressman Zach Wamp, FEMA approved a $1.66 million grant for the project, with additional funds provided by the State of Tennessee.

Frequent flooding plagued the area as a result of many  decades of dense development in the highly urbanized Woolen Mill Branch watershed.  In an effort to mitigate the problem, the City designated two sites for potential regional detention ponds. Preliminary studies by the US Army Corps of Engineers confirmed that detention ponds at those locations could reduce flooding. CTI was selected to provide engineering services.

CTI’s design of the  detention ponds significantly reduces flooding within the watershed:

• The 18th Street pond can store over 17 million gallons in a 7-acre impoundment created by a 22-foot-high earthen dam. The pond will reduce the peak storm flows at 18th Street by over 96 percent during a 100-year storm.
• The East Street detention pond can store 3.6 million gallons and will reduce peak 100-year storm flows by 41 percent.

Early in the design phase, CTI identified a third detention pond site and provided a fast-track design that allowed the City Public Works Department to complete construction of the pond 4 months later.

Design of the ponds included relocation of water mains, sewer lines, gas mains, electrical distribution lines, telephone and cable TV lines, and a TVA electrical transmission line. The East Street site  required relocation and mitigation of an impaired stream. The innovative stream design incorporated mesh filter socks filled with mulch, seed, and live wetland tree sprigs along the channel side slopes; a  lined, grass channel bottom to prevent erosion; and a narrow low-flow channel to promote re-establishment of aquatic life. This design allowed construction of a quickly stabilized streambed with fully vegetated side slopes prior to shifting the stream flow into the new channel, as required by TDEC.

Extensive flood modeling completed for the FEMA map revisions indicates that the ponds will reduce flooding dramatically within the watershed. The 100-year flood elevations downstream will be reduced by up to 3 feet along West Fork of Woolen Mill Branch. Flood elevations at the Maytag manufacturing plant will be reduced by nearly 4 feet for a 5-year storm. The success of this flood control project and its impact on the community is demonstrated by the recent addition of 500 new jobs at this manufacturing plant.

Construction of the ponds began in March of 2008 and was completed in August. The two primary detention ponds were completed on time and 8 percent below the $1.93 million budget.