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Public Works Flood Control

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1. What is the design storm for my project?

The County Title 9 (Title 9: 911-2.010) set the design storm based on the watershed area draining to the creek of drainage facility as follows:

• Area < 1.0 sq. mi. Contain, with sufficient freeboard, a ten year frequency of average recurrence interval (10-year)


• 1.0 sq. mi. ≤ Area ≤ 4 sq. mi. Contain, with sufficient freeboard, a 25-year frequency of average recurrence interval (25-year)


• 4.0 sq. mi.≥ Area Contain, with sufficient freeboard, a 50-year frequency of average recurrence interval (50-year) OR Contain the 100-year frequency of average recurrence interval (100-year)

2. Why do we need a permit to work in the creek?

The District boundaries cover all of Contra Costa County. Within District right of ways, they District can dictate hydrology methods and freeboard standards. The County has adopted our standards and so in the unincorporated areas our standards are used. FEMA will require you to use the FCD flow rates in any FEMA sutdy. The District can generate the flow rates using the Hydro program.

3. What is the drainage easement across my property for? Can I build on it? What can I do on it?

1. Easements provide the Public Works Department and Flood Control District with land rights for construction, reconstruction, maintaining and accessing its drainage facilities and for other related purposes. Some access easements are not used regularly but must be kept clear for potential future use. An easement allows the property owner use of the property as long as it does not interfere with easement rights.


2. No permanent structures or encroachments will be permitted or constructed within or over any drainage easement. This includes, but is not limited to:
   • fill slopes
   
   
   • retaining walls
   
   
   • fencing
   
   
   • sheds
   
   
   • landscaping

   Any such obstructions will be removed as necessary for maintenance and access purposes and will not be repaired or replaced (Title 0; 914-14.010).

4. Are there more Frequently Asked Questions?

Yes. We have written questions and answers to many questions. Click "More..." below. More...