comparing runnoff on different road surfaces
comparing runnoff on different road surfaces
(OP)
My question is "would the runnoff produced from a paved (asphalt) road surface be similar to the runnoff from a dirt road surface which has been overlaid with compacted 'crusher waste'. In this case the dirt road with the crusher waste appeared to be impervious and gthe underlying dirt has a high clay content. In this case the roadway surfaces have the same angle and orientation.





RE: comparing runnoff on different road surfaces
RE: comparing runnoff on different road surfaces
is there a formula or table which I could reference or is this dependent on factors which need to be analysed before calculating etc. Also it is generally well know that dirt (with the compacted crusher waste on top " would be similar in runnoff etc.
Templeton
RE: comparing runnoff on different road surfaces
RE: comparing runnoff on different road surfaces
10-year and 100-year storms
gravel road 0.60 - 0.88
asphalt 0.75 - 0.95 (rational method)
Ron - By the way, it is no longer the SCS, they changed the name several years ago from SCS to NRCS.
RE: comparing runnoff on different road surfaces
RE: comparing runnoff on different road surfaces
From NRCS TR-55:
Paved: (excluding r/w)
98 (regardless of soil classification)
Paved: (including r/w, presumes open ditches)
A: 83
B: 89
C: 92
D: 93
Gravel: (includes r/w)
A: 76
B: 85
C: 89
D: 91
Dirt: (includes r/w)
A: 72
B: 82
C: 87
D: 89
Your soil type is probably B or C, depending. There's a chart in TR-55 to look it up.
Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East - http://www.campbellcivil.com
RE: comparing runnoff on different road surfaces
the soil is considered to be a clay (HbC)with runnoff being 'slow to medium' so I'm assuming that is a 'c'
It would appear the difference is no more than 5%
I suspect it may be less because the original road surface did seem impermiable because of the highly compacted 'crusher waste' overlay. The fines in that material seemed to form a cement like barrier which would contrast to a straight gravel base.
Thanks very much for pointing me to the 'tables'.
Templeton