The hydrologic criteria to be used for the C-SWPPP’s Stormwater Management and Sediment Control section shall be as follows:
(A) The 25-year, 24-hour duration design storm for all cross-drain culverts and drainage designs.
(B) The 10-year design storm for all interior culverts and drainage conveyance system designs, plus 25-year design storm for all channel conveyances.
(C) The 2-year, 10-year and 25-year, 24-hour design storms for all detention and retention basins using procedures contained in the Stormwater Management Design Manual or approved by the Stormwater Administrator. All drainage designs shall be checked using the 100-year, 24-hour storm for analysis of local flooding, and possible flood hazards to adjacent structures and/or property.
(D) All hydrologic analysis will be based on pre-development and post-development land use conditions.
(E) For the design of storage facilities, a secondary outlet device or emergency spillway shall be provided to discharge the excess runoff in such a way that no danger of loss of life or facility failure is created. The size of the outlet device or emergency spillway shall be checked for passing the 100-year, 24-hour storm, as a minimum requirement.
(Ord. 2819, passed 6-17-19)