Raw Water Line and Creek Bank Stabilization, Elkin, NC
The Town of Elkin’s 12-inch emergency raw water line, installed in 2004, withdraws water from the Yadkin River and conveys it directly to the drinking water treatment plant (WTP). The raw water line was installed in reaction to severe drought conditions during 2001. During this time of drought, the town’s primary raw water source, Big Elkin Creek, reached low levels preventing withdraw. While the primary infrastructure is in place, the existing WTP can’t effectively treat the raw water from the Yadkin River due to high turbidity levels. State regulations require pre-settling of raw water having the water quality characteristics of the Yadkin River.
The project, funded by the state Drinking Water State Revolving Fund (DWSRF), consists of approximately 3,690 LF of 12-inch ductile iron emergency raw water line that is being extended from the Town of Elkin WTP to their raw water reservoir. The alignment generally follows Big Elkin Creek along an existing greenway trail. The project provides an important emergency raw water supply for the Town of Elkin. An existing 24-inch gravity raw water line from the reservoir to the WTP also follows the same corridor.
Improvements will also be made to the existing raw water intake pump station. The primary improvements causing land disturbance consist of a backwash line extending from the reservoir to the pump station. The installation of these appurtenances and water line will be on the reservoir dam and will be reviewed and permitted by the state dam safety engineer.
Approximately 100 LF of the existing 24-inch raw water line has been exposed as a result of stream bank erosion of Big Elkin Creek. The project design utilizes natural channel design practices including root wads, rock toes and j-hooks to re-establish the channel banks to protect the raw water line and to direct the stream energy away from the banks. In addition, a tributary confluence is being relocated to prevent further erosion. Design challenges include achieving a no-rise condition despite altering the channel cross-section.