AutoCAD Civil 3D - Stormwater

AutoCAD Civil 3D - Stormwater

Active Contributor
Posts: 46
Registered: ‎11-13-2006
Message 1 of 3 (193 Views)

SSA 100-yr runoff coeff multiplier for rational

193 Views, 2 Replies
03-01-2012 08:38 AM

I have looked through help and SSA.  I am looking for where the multiplier for 100-year rational runoff coefficients may be applied.  Typically, for 25-yr return period, the C value should be multiplied by 1.1, for 50-yr multiplied by 1.2, for 100-yr, multiplied by 1.25.


Does SSA automatically do this or is there a setting somewhere to apply these multipliers?





Active Member
Posts: 9
Registered: ‎05-20-2011
Message 2 of 3 (143 Views)

Re: SSA 100-yr runoff coeff multiplier for rational

03-26-2012 09:53 AM in reply to: clemk

We are in a similar situation where I am, our regulations have a table that gives a C value for a 5-year winter storm and both 100-year storm values based on the design C value. The only solution I have found is to have 4 different design files.


Not the answer I am sure you have been looking for but the only option as of right now.

Active Contributor
Posts: 38
Registered: ‎05-18-2010
Message 3 of 3 (121 Views)

Re: SSA 100-yr runoff coeff multiplier for rational

03-28-2012 10:39 AM in reply to: clemk

I also have to do separate files.  It seems that it is something that could be incorporated into SSA relatively easily.  Maybe next year's version!

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