Ulatis Flood Control Project:Emergency Hawkins Road Bridge Scour Remediation

Ulatis Flood Control Project:Emergency Hawkins Road Bridge Scour Remediation

During a recent bridge inspection, Caltrans noticed that a County bridge, Brynes Road Bridge (No. 23C-166), is severely impacted by scouring of the flood control channel. The County maintains the actual bridge structure, while the Solano County Water Agency is responsible for maintenance of the channel. According to Caltrans, the elevation of the channel flowline near the bridge is actually lower than the elevation of the top of the spread footings of the bridge. Therefore, a minimal amount of additional scour could undermine the bridge footing, endangering the structural integrity of the bridges. SCWA will install a series of boulder weir to inhibit further channel degradation and promote re-establishment of the as-built channel grade by natural recruitment of bed material. SCWA will also backfill the scoured areas immediately surrounding the structures with well-graded rock and cobble ("river run") to provide immediate protection of the exposed footings. The design will specify boulder weir structures that provide for grade control and direct downstream flows towards the central channel thalweg. The weirs will be constructed in such manner as to remain resistant to scour failure by placement of footer rocks below the weir, imbedded into the channel substrate. All rock will be sized to resist entrainment by high flows typically seen in spring runoff season.

Solano