New Hampshire Code of Administrative Rules
Env - Department of Environmental Services
Subtitle Env-Wq - Water Quality and Quantity Programs
Chapter Env-Wq 1500 - ALTERATION OF TERRAIN
Part Env-Wq 1508 - PERMANENT METHODS FOR PROTECTING WATER QUALITY
Section Env-Wq 1508.12 - Pretreatment Practices: Sediment Forebays
Current through Register No. 13, March 27, 2025
Sediment forebays shall comply with the following:
(a) Sediment forebays shall not be located in any of the areas identified in Env-Wq 1507.02(c)(1)-(4) unless the practice has an impermeable liner;
(b) Unless otherwise specified, a sediment forebay shall be designed to contain 10% of the WQV;
(c) Sediment forebays for gravel wetland systems shall be designed to drain within 72 hours of storm events;
(d) Forebays shall be no less than 2 feet and no more than 6 feet in depth;
(e) Forebay side slopes shall be no steeper than 3:1;
(f) A fixed vertical sediment marker shall be installed to measure sediment depth; and
(g) Upon completion of maintenance, all disturbed areas shall be re-stabilized in accordance with the approved plans.
(See Revision Note #1 at chapter heading for Env-Wq 1500) #9343, eff 1-1-09