Unconnected impervious
Unconnected impervious
(OP)
Version 9, which I recently upgraded to, includes several CN values for impervious and unconnected impervious. A house out in the woods of a 2 or 5 acre (or however large)parcel that is sloped towards the woods seems a pretty straightforward candidate for using "roofs - unconnected impervious", and I can reasonably see the same for certain driveways. But how about a portion of a road where it's runoff is collected in open ditches, routed through a treatment device (say a water quality swale), and ultimately outlet via a level spreading device into those same woods?
Is it reasonable to consider that impervious also as unconnected? I'm not talking about a level spreading device that is situated just 20 or 30 feet or so above a stream channel, intermittent or perennial, but where it's 100 or several hundred feet from a stream or property line.
Is it reasonable to consider that impervious also as unconnected? I'm not talking about a level spreading device that is situated just 20 or 30 feet or so above a stream channel, intermittent or perennial, but where it's 100 or several hundred feet from a stream or property line.





RE: Unconnected impervious
But in the end, this is a matter of what your reviewing agency will accept.
For details see www.hydrocad.net/pervious.htm
Peter Smart
HydroCAD Software
www.hydrocad.net
RE: Unconnected impervious
http://www.hydrocad.net/impervious.htm
Peter Smart
HydroCAD Software
www.hydrocad.net