ufcivilengineer
Civil/Environmental
- Jan 2, 2007
- 5
I'm working on a project which is in mountainous terrain. The elevation at the peak is 500 which slopes down at 1H:1V to elevation 405 where there is a level flat area about 12-15 feet wide. I’ll call this “flat area #1”. After “flat area #1” the elevation falls again at 1H:1V to elevation 363 at which there is another flat area and the "proposed facility". I’ll call this “flat area #2”.
Each sloped area will have a wire mesh for stabilization which is being designed by a Geotechnical Engineer.
Using the Rational Method for calculating runoff.
The drainage basin area above “flat area #1” has been estimated to be 0.44 acres.
The runoff coefficient was estimated to be 0.79 (Rocky terrain with some soil and very little vegetation) The rainfall intensity has been estimated to be 4.26 in/hr Using the Rational Method, the peak discharge rate has been calculated to be 1.5 cfs
My thought was to capture the runoff at “flat area #1” via a swale the length of the flat area (about 155 feet long) and convey it to the lower “flat area #2” where the proposed facility is and associated drainage system.
I can size the drainage system to convey the flow. My concern is capturing the flow at each flat area and transporting it in a controlled manner.
My struggle is in calculating the velocity of the surface runoff. Knowing the velocity I could size the energy dissipation required.
I have velocity equations for flatter terrain but I don’t think the equations would apply in such steep terrain. I don’t know how to handle the steeper terrain calculations.
Any reference material and help would be greatly appreciated.
Each sloped area will have a wire mesh for stabilization which is being designed by a Geotechnical Engineer.
Using the Rational Method for calculating runoff.
The drainage basin area above “flat area #1” has been estimated to be 0.44 acres.
The runoff coefficient was estimated to be 0.79 (Rocky terrain with some soil and very little vegetation) The rainfall intensity has been estimated to be 4.26 in/hr Using the Rational Method, the peak discharge rate has been calculated to be 1.5 cfs
My thought was to capture the runoff at “flat area #1” via a swale the length of the flat area (about 155 feet long) and convey it to the lower “flat area #2” where the proposed facility is and associated drainage system.
I can size the drainage system to convey the flow. My concern is capturing the flow at each flat area and transporting it in a controlled manner.
My struggle is in calculating the velocity of the surface runoff. Knowing the velocity I could size the energy dissipation required.
I have velocity equations for flatter terrain but I don’t think the equations would apply in such steep terrain. I don’t know how to handle the steeper terrain calculations.
Any reference material and help would be greatly appreciated.
