Full Text
CITY OF ANAHEIM DRAINAGE MANUAL FOR PUBLIC AND PRIVATE DRAINAGE FACILITIES APPENDIXES AUGUST 2005 Appendix A Drainage Parameters ---PAGE BREAK--- 1 City of Anaheim Department of Pubic Works STORM DRAINAGE PARAMETERS April 30, 2004 A. HYDROLOGY Hydrology for Storm Drainage studies shall be based on the “Orange County Hydrology Manual (October 1986, and Addendum No.1 May 1996)”. However, the City of Anaheim requires of all storm events (10-year, 25-year, or 100-year) to be based on the “high confidence” level storm frequency events. B. STREET AND HIGHWAY Maximum flooded widths and depths for local streets and highways shall be per the following: TABLE 1 Type of Street Frequency Storm Maximum Allowable Flooding See Figure No. 10 yr Top of Curb 1 Local Street 100 yr At or below *ROW Line 2 10 yr 17 feet 1 25 yr Top of Curb 1 Highway 100 yr At or below *ROW Line 2 Sump Condition Street or Highway Same as above Same as above 1 & 2 * ROW - Right-of-Way ---PAGE BREAK--- 2 C. DRAINAGE SYSTEM REQUIRED The drainage systems are required per the “County of Orange Local Drainage Manual (January 1996)”. However, the City of Anaheim requires the design and installation of a storm drain system when any of the conditions listed below exists: 1. The limitations outlined in Table 1 & Figures 1 & 2 are exceeded. 2. Excess nuisance water in residential areas (maximum surface flow is 1,000 feet). 3. The need for cross-gutters across any arterial highway. 4. Median drainage is required. 5. Product of depth times velocity is greater than six at street/highway gutter flowline. 6. Future upstream development will cause drainage problems. D. DRAINAGE SYSTEM DESIGN The drainage system design shall be per the “County of Orange Local Drainage Manual (January 1996)”. However, the City of Anaheim requires the drainage system be designed with a minimum size to fully convey all storm water in that system for: 1. A 25-year storm event for all drainage areas/basins tributary to the Santa Ana River watershed or, 2. A 10-year storm event for the drainage areas/basins tributary to the other watershed facilities The above criteria are the minimum requirements for sizing a storm drainage system and that sizing must be increased, as necessary, to address all requirements including those noted for the 100 year storm event. ---PAGE BREAK---