20071134 Ver 1_More Info Letter_20050112

January 12, 2005
County: Madision/Yancey
State Project: WBS No. 34445.1.1 (R-2518A)
Description: US 29 from I-26 to 0.8 Km East of the Yancey Co. Line
Subject: Stormwater Management Plan
ROADWAY DESCRIPTION
The purpose of R-2518A project is to add traffic capacity to US 19/US 19E. Other factors contributing
to the need of the project are system linkage and safety. The project begins at an interchange on US
19/23 (future I-26) north of Mars Hill in Madison County and ends at SR 1186 west of Micaville in
Yancey County.
ENVIRONMENTAL DESCRIPTION
This project is located in the French Broad River Basin. The streams on this project have been assigned
a best usage classification by the North Carolina Division of Water Quality. Surface waters located
within the project area have been given classification WS-II. Classification WS-II waters are protected
as water supplies which are generally in predominantly undeveloped watersheds. Stringent stormwater
management measures may be required on a case-by-case basis where it is determined that additional
measures are required to protect water quality and maintain existing and anticipated uses of these waters.
Point source discharges of treated wastewater are permitted pursuant of applicable rules and regulations.
Class C waters are freshwaters protected for secondary recreation, agriculture, fishing, aquatic life
including propagation and survival, wildlife. Impacts to the natural and human environments are
minimal.
BEST MANAGEMENT PRACTICES AND MAJOR STRUCTURES
Best Management Practices (BMP) used on the project to reduce the stormwater impacts are as follows;
1. Creating grass swales.
2. The use of preformed scour holes.
3. Minimize the ditch grades to lower the velocities in the ditches.
4. Installation of retaining walls to avoid impacting the existing stream.
5. Maintaining separation of off site drainage and roadway drainage.
6. The addition of buried inverts on culvert extensions.
7. Use of sills in proposed culverts to create low flow channels.
8. Retrofit exiting culverts with sills to decrease velocities.
9. Utilized energy dissipaters at pipe outlets to lower outlet velocities.
10. Mitigation plan is being developed to improve existing stream conditions through out this project.
11. North Carolina Department of Transportation has maintained a minimum of 8 meters (25 feet) of
undisturbed vegetated area next to the stream banks to the extent practicable along the project limits.