Emerson Site Hydraulic Analysis Comments.doc
Emerson Site Hydraulic Analysis Comments
1. Need to follow the ECDC and the DOE 1992 Stormwater Management Manual for
Western Washington when designing the detention system for the Emerson lot.
All development sites less than one acre that discharge directly or indirectly to
2.
a stream shall be required to limit the peak rate of runoff to the predeveloped
condition two-year, 24-hour design storm, while maintaining the predeveloped
condition peak runoff rate for the 10-year, 24-hour and 100-year, 24-hour
storms.
3. Need predevelopment conditions peak flows and hydrographs for the 2-year, 24-hour
design storm, 10-year, 24-hour design storm, and 100-year, 24 hour design storm.
The predevelopment condition for all cases other than open water bodies shall
be considered meadows or young second growth forest.
4. Need development conditions peak flows and hydrographs for the 2-year, 24-hour
design storm, 10-year, 24-hour design storm, and 100-year, 24 hour design storm.
5. R/D facility needs to be designed with multiple orifices to maintain the predeveloped
condition for the 2-yr, 10-yr, and 100-yr, 24-hr storms.