The PMP - Tips on Modeling?
The PMP - Tips on Modeling?
(OP)
I have been working on a retrofit to an existing stormwater pond (increasing its detention time for a 1-year storm event). In the state review process, the project has been referred to the Dam Safety section, which is concerned with the pond's performance during the Probable Maximum Precipiation (PMP) event. Reviewing the data for my region, the design storm they are looking for is a 27" storm event. Plugging this storm event into my model as a 27", 24 hour storm event (predictably) overloads my pond by quite a bit (The 100-year storm event in our area is 5.2")
Has anyone else here designed stormwater ponds with the PMP in mind? Is it really on the order of 5x larger than a 100-year storm event? Have I erred in my modeling at some point?
Has anyone else here designed stormwater ponds with the PMP in mind? Is it really on the order of 5x larger than a 100-year storm event? Have I erred in my modeling at some point?





RE: The PMP - Tips on Modeling?
RE: The PMP - Tips on Modeling?
"The most current definition of PMP is as follows: "Theoretically, the greatest depth of precipitation for a given duration that is physically possible over a given size storm area at a particular geographical location at a certain time of the year." This definition comes from Hydrometeorological Report 55A (HMR 55A). "
Good luck
RE: The PMP - Tips on Modeling?
RE: The PMP - Tips on Modeling?
The pond is in Vermont. Thankfully, we do not have to worry about hurricanes.
That definition sounds odd to me. Most precip physically possible? Isn't it physically possible to get a rain event with 100" of depth? Interpolating the given rainfall depths for 1, 10 and 100 year storms in my area, this PMP event is a 395,000-year storm event. Am I mixing apples and oranges in making this kind of claim?
RE: The PMP - Tips on Modeling?
RE: The PMP - Tips on Modeling?
Good luck
RE: The PMP - Tips on Modeling?
http://www.nws.noaa.gov/ohd/hdsc/studies/pmp.html
RE: The PMP - Tips on Modeling?