(a)  The Division of Highways shall review all drainage prior to acceptance of any facility to the state system.

(b)  All storm drainage shall be adequate so that the road may be maintained without excessive cost, and not cause flooding on private property from runoff of an appropriate storm frequency.  Permanent drainage easements may be required.  The minimum design frequency shall be as follows:

(1)           storm sewer collector ‑‑ 10 year frequency;

(2)           cross drainage ‑‑ 25 year frequency.

(c)  In areas where ditch grades or quantities of flow deem it impracticable to establish and maintain vegetation, an erosive resistant lining such as paving or rock rip rap may be required.

(d)  Subsurface drainage shall be adequate to maintain a stable subgrade.

(e)  When road crossings are within areas designated as flood hazard areas under the Federal Flood Insurance Program, the design must be approved by the responsible local governing agency for its consistency with local flood zoning ordinances.


History Note:        Authority G.S. 136‑18(1); 136‑44.1; 136‑102.6;

Eff. April 3, 1981;

Amended Eff. December 29, 1993; July 1, 1984;

Pursuant to G.S. 150B-21.3A, rule is necessary without substantive public interest Eff. September 6, 2016.