Section Env-Wr 403.04 - Design Floods for New Dams(a) A new dam shall be designed to safely pass the flows indicated below without manual operation and with the freeboard requirements indicated: (1) A non-menace structure shall pass the 50-year flood or, at the owner's option, the site-specific inflow design flood, with one foot of freeboard or, at the owner's option, freeboard equal to the effects of maximum wave run-up;(2) A low hazard structure shall pass the 100-year flood or, at the owner's option, the site-specific inflow design flood, with one foot of freeboard or, at the owner's option, freeboard equal to the effects of maximum wave run-up;(3) A significant hazard structure shall pass 1/2 of the probable maximum flood (PMF) as determined using Hydrometeorological Report No. 52 (HMR 52) from the National Oceanic and Atmospheric Administration (NOAA), 1987, available as noted in Appendix B, or the site-specific inflow design flood, with freeboard equal to the effects of maximum wave run-up; and(4) A high hazard structure shall pass the PMF as determined using HMR 52, 1987, available as noted in Appendix B, or the site-specific inflow design flood, with freeboard equal to the effects of maximum wave run-up;(b) Wave run-up calculations shall identify maximum wind speeds and fetch limitations.(c) For a significant hazard or high hazard dam, and when the option is applied for a non-menace or low hazard dam, the owner shall submit wave run-up calculations with the application.(d) The owner shall submit the results of calculations performed for hydrologic and hydraulic analyses pursuant to (a), above, and Env-Wr 403.05 with the application.N.H. Admin. Code § Env-Wr 403.04
#1716, eff 2-20-81; ss by #2207, eff 12-13-82; ss by #2900, eff 11-7-84, EXPIRED 11-7-90
New. #5080, eff 2-22-91; rpld by #6462-B, eff 2-21-97
New. #8414, eff 8-20-05; ss by #10510, eff 1-22-14