Rock Outlet Protection Source Equation

[HHguy]

I'm looking for the equation(s) used to establish the Rock Outlet Protection nomographs used by so many jurisdictions. You know, the ones based on Tw < or > .5 dia., enter the figure with a Q and Pipe dia. to get a d50 then further to get length of level section. I think the source is SCS, perhaps a Maryland office. In this day of spreadsheets, why use figures !?

 

[wasserjunge]

Any luck with this request, HHguy???? I am looking for the same thing.

 

[KThomson]

In the &quot;Standards for Soil Erosion and Sediment Control in New Jersey&quot; - the equations are as follows

TW<0.5 Do La=(1.8*(q/(Do^.5))) + (7*Do)
W=(3*Wo)+La

TW>0.5 Do La=3*(q/(Do^.5))
W=(3*Wo)+(0.4*La)

D50= (0.016/Tw)*(q^1.33)
Where Tw can not be computed use Tw=0.2*Do

Do=maximum inside culvert height in feet (or diameter of round pipe)
Wo=maximum inside culvert width in feet (or diameter of round pipe)
q=unit discharge = Q/Wo (CFS per foot for conduit design storm or 25 yr storm, whichever is greater)
La= length of apron
W=width of apron (Width should be at least 3 times the culvert width)


Hope this helps!!

Kate