Erosion and Sediment Pollution Control Program Manual.pdf

Barrel/Riser Sediment Trap - This device has MODERATE sediment removal efficiency and is an
ABACT for HQ watersheds but not for EV watersheds. The efficiency can be raised to HIGH,
meeting ABACT for HQ and EV watersheds, by substituting a skimmer dewatering device for the
perforated riser.
PA DEP
For traps with barrel/riser spillways, the crest of the riser should be set at the elevation at which the
required 2,000 cubic feet/acre storage capacity is provided. The riser and outlet barrel should be sized
to provide a discharge capacity of 1.5 cfs/acre. Recommended minimum barrel and riser diameters are
contained in Table 8.1. Supporting calculations should be provided. The embankment should provide
at least 12” of freeboard above the maximum design water elevation — the elevation at which the 1.5
cfs/acre discharge capacity is provided. Perforations in the riser to dewater the trap should be limited
to one 1” diameter hole per vertical foot of riser with the lowest perforation at the sediment storage
elevation as shown in Standard Construction Detail # 8-2.
TABLE 8.1
Recommended Minimum Pipe Sizes for Barrel/Riser Sediment Traps
Barrel Diameter (in.) Riser Diameter (in.) Drainage Area (Acres)
12 15 1
New York DEC
15 18 2
18 21 3
21 24 4
21 27 5
363-2134-008 / March 31, 2012 / Page 217