Erosion and Sediment Pollution Control Program Manual.pdf

TABLE 7.4
Concrete Base Requirements for Various Sizes of Temporary Riser Pipes
Volume of Concrete per
Buoyant Force
Vertical Foot of Riser
Riser Pipe Diameter (in) (lb/V.F. of Riser Height) Height (cf/VF) Needed to
Prevent Flotation
12 49.0 0.69
18 110.3 1.54
21 150.1 2.10
24 196.0 2.75
30 306.3 4.29
36 441.1 6.18
48 784.1 10.98
54 992.4 13.90
60 1225.2 17.16
Georgia DNR
EXAMPLE: Find the volume of concrete required to stabilize a 24 inch diameter riser 10 feet high.
VOL = (2.75 cu. ft./V.F.) (10 feet) = 27.5 cu. ft. ≈ 1 cu. yd.
Note: Minimum 2 #8 rebar placed at right angles and projecting through sides of riser to anchor it to
concrete base. Rebar should project a minimum of ¼ riser diameter beyond outside of riser.
Concrete bases should be poured in such a manner as to insure that concrete fills the bottom of riser to
the invert of the outlet pipe to prevent riser from breaking away from the base. Minimum base width
should equal 2 times riser diameter.
The embedded section of aluminum or aluminized pipe should be painted with zinc chromate or
equivalent.
In permanent basins, a temporary riser is typically attached to the permanent riser by means of a stub.
To promote a tight seal of the temporary stub connection with the permanent riser structure, it is
recommended that a flange plate — welded to the end of the stub barrel — be bolted and caulked to
the permanent outlet structure. Simply grouting the pipe is often not effective and usually requires
constant maintenance.
363-2134-008 / March 31, 2012 / Page 187