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 1506 - METHODS FOR EROSION AND SEDIMENT CONTROL DURING TERRAIN ALTERATION ACTIVITIES
Section Env-Wq 1506.12 - Sediment Control Methods: Temporary Stormwater Diversion
Current through Register No. 13, March 27, 2025
Temporary stormwater diversion shall comply with the following:
(a) When necessary to minimize release of sediment-laden runoff prior to stabilization of the site and the permanent stormwater management system components, sediment-laden water shall be diverted and stored in temporary diversion practices such as sediment basins or trenches;
(b) Subject to (c), below, temporary diversion practices shall be stabilized prior to receiving runoff;
(c) Except as required by Env-Wq 1511.08 for solar arrays, temporary diversion channels with a gradient of 2 percent or greater shall be stabilized. However, channels with a slope of less than 2% shall be stabilized only if erosion is observed;
(d) The area draining to each temporary diversion practice shall be less than 5 acres;
(e) Temporary diversion channels shall convey, and temporary basins and trenches shall contain, the 2-year, 24 hour design storm without overtopping the banks;
(f) The bed slope of diversion channels shall have a positive grade to assure drainage;
(g) Where diversions carry concentrated flows, energy dissipation methods shall be implemented to disperse flow into areas downstream of the disturbed area;
(h) If erosion of temporary diversion practices occurs during construction, corrective action shall be taken to stabilize the basin, channel, and berm; and
(i) Diversion basins and trenches shall be cleared of sediment whenever sediment accumulates.
(See Revision Note #1 at chapter heading for Env-Wq 1500) #9343, eff 1-1-09