TRANSPORTATION

The Florida Rock /Clay Scour Procedure is designed to account for the scour resistance of cemented strata, rock, and clay.  The test methods establish the shear stress response of soils and the procedure integrates that response over the lifetime of expected flows at the bridge site.  The procedure involves establishing the shear stress response of a site-specific sample using the RETA and SERF devices above, and then integrating that response over the flows expected in the life of the bridge to predict contraction or local scour at the bridge.

Conservatism in the analysis is maintained by:

Assuming that shear stress does not decrease within a local scour hole
Assuming an extremely aggressive bridge flow history
Assuming no refill of the predicted scour
Using the more conservative of the RETA and SERF results

Rotating Erosion Testing Apparatus (RETA)

Sediment Erosion Recirculating Flume (SERF)

Currently due to its complexity and newness, this procedure is performed exclusively by Ocean Engineering Associates, Inc. in close cooperation with the State Drainage Engineer. Guidance, software, and training are being developed so that procedure may be deployed to the general engineering community. Districts should contact Rick Renna, State Drainage Engineer, if scour-resistant soils are expected top be encountered in bridge design or the evaluation of existing bridge scour.