importance in highway practice, a separate section (Section 6.6) is devoted to design and
placement of rock riprap.
6.3.4 Countermeasure Design Guidelines
Hydraulic Engineering Circular (HEC) No. 23 (Lagasse et al. 2001) provides experience,
selection, and design guidance for a wide range of stream instability and bridge scour
countermeasures, including river training devices and revetment armoring.
HEC-23 is organized to:
Highlight the various
groups
of
countermeasures
and identify their
individual
characteristics.
For specific countermeasures, list information on their functional applicability to a particular
problem, their suitability to specific river environments, the general level of maintenance
resources required, and which State Highway Agencies (SHAs) have experience with
specific countermeasures.
Provide general criteria for selection of countermeasures for bridge scour and stream
instability problems.
Discuss countermeasure design concepts including design approach, hydraulic analysis,
environmental permitting, special design considerations related to riprap, filters, and edge
treatment, and biotechnical engineering approaches.
Provide detailed design guidelines for specific countermeasures.
Specific design guidelines are provided in HEC-23 for the following river training devices:
Bendway Weirs/Stream Banks
Spurs
Guide Banks
Check Dams/Drop Structures
Design guidelines are also provided for the following armoring (revetment) countermeasures.
Revetment (summary of HEC-11 guidance)
Soil Cement
Wire Enclosed Riprap Mattress
Articulating Concrete Block Systems
Articulating Grout Filled Mattress
Hydraulic Engineering Circular (HEC) No. 11 (Brown and Clyde 1989) is a comprehensive
design manual for riprap revetment. HEC-11 includes discussions on erosion potential,
erosion mechanisms and riprap failure modes, as well as riprap types including rock riprap,
rubble riprap, gabions, preformed blocks, grouted rock, and paved linings. Design concepts
included in HEC-11 are: design discharge, flow types, channel geometry, flow resistance,
extent of protection, and toe depth. Detailed design guidelines are presented for rock riprap,
6.8
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