Appendix A: Design Procedure for Riprap Armor
increase in stone size, for riprap subject to attack by large floating debris. Riprap
deterioration from debris impacts is usually more extensive on bank lines with steep slopes.
Therefore, riprapped slopes on streams with heavy debris loads should be no steeper than 1V
on 2.5H.
A.10 QUALITY CONTROL
Provisions should be made in the specifications for sampling and testing the quarry
and in-place riprap as representative sections of revetment are completed. Additional sample
testing of in-place and in-transit riprap material at the option of the Contracting Officer should
be specified. The frequency of sample testing depends on the ease of producing riprap
material that complies with the specifications. The size of the test samples should be
sufficient to be representative of the riprap material. Truckload samples are usually
satisfactory for in-transit material. The following tabulation provides two methods of
determining the riprap sample (area versus volume) and should be used as a guide for in-place
samples:
Riprap Layer Thickness
Size of Samples
(in.)
Bulk Volume
Area
(cu. yd.)
(ft)
12
1
6x6
18
2
8x8
24
5
10 x 10
30
10
13 x 13
36
16
15 x 15
The primary concern of riprap users is that the in-place riprap meets specifications. Loading,
transporting, stockpiling, and placing can result in deterioration of the riprap. Coordination
of inspection efforts by experienced staff is necessary. Additional guidance can be found in
EM 1110-2-2302.
A-33
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