I agree with jugglerbri. In addition to what he says, you can also consider the regulatory process. You can't simply install a structure in a stream without a permit. Also, are you filling a wetland? How about sediment and erosion control? Normally, there is local, state and federal regulatory...
You don't mention the size or type of the project area. That may have some bearing on the response. However, in general, from a water quantity standpoint, I can see no reason to detain stormwater unless it is a relatively large area where the discharge could adversely impact flooding or erosion...
First, I recommend you use the Win TR55 version. You can download the users manual, the program, and most importantly for you, a powerpoint tutorial at the following web site.
http://www.wcc.nrcs.usda.gov/water/quality/common/tr55/tr55-beta.html
Also, if you have questions, check the phone...
You will need to provide adequate fencing to keep kids out of this area. Kids are prone to getting into areas they shouldn't. Several years ago, a child drowned in this state when she was sucked through a long culvert during a hurricane. People can argue that she shouldn't have been near the...
You may want to check your hydrology. The peak discharge may be too large. It sounds like you are dealing with a large watershed requiring a computer model such as HEC-HMS or TR20. If so, this model should be calibrated and verified to be sure you are getting the correct results. If you haven't...
First, my advice is to study up on open channel hydraulics. Chow's "Open Channel Hydraulics" is a good source. Second, if you want to do this correctly, I suggest using the HECRAS computer program to model the ditch and the culverts. There can be a lot of headloss at certain culverts...
You will always have a great debate about the Rational Method verses TR55. Personally, I would limit the use of the Rational method to drainage areas up to say 20 acres. Beyond that, I would use TR55 because I believe it provides better detail in describing the physical characteristics of the...
NRCS (formerly Soil Conservation Service) hydrology uses the Manning-Kinematic equation for the solution of overland flow. For the sheet flow segment, the maximum length is 300', with a most likely length of 100' on unpaved areas. For paved areas, lengths may be longer than 100' until flow...
