Hyrologic Soils Groups and Ledge
Hyrologic Soils Groups and Ledge
(OP)
I am a mid level civil engineer and I have been asked by one of my superiors to do what I think is a peculiar thing on one of my stormwater models.
The site in question has a large portion mapped as HSG D and a smaller portion mapped as HSG C. It is a wooded site with exposed and shallow ledge outcroppings.
For the existing conditions model, I am being asked to calculate the ledge area and use a CN 98 for these and use the CN for woods on the remaining portions for both HSG mapped areas. I thought the CN values, combined with HSG included such things as ledge assumptions. Am I wrong?
TIA!
The site in question has a large portion mapped as HSG D and a smaller portion mapped as HSG C. It is a wooded site with exposed and shallow ledge outcroppings.
For the existing conditions model, I am being asked to calculate the ledge area and use a CN 98 for these and use the CN for woods on the remaining portions for both HSG mapped areas. I thought the CN values, combined with HSG included such things as ledge assumptions. Am I wrong?
TIA!





RE: Hyrologic Soils Groups and Ledge
Peter Smart
HydroCAD Software
www.hydrocad.net
RE: Hyrologic Soils Groups and Ledge