Level 1 & 2 Scour Assessments
Level 1 Scour Assessments
Stroma can provide level 1 scour assessments to BD97/12 by surveying the riverbed, foundations and any existing protection measures and undertaking a preliminary risk rating.
Level 2 Scour Assessments
Depending on the outcome of the level 1 assessment, Stroma can also proceed to a level 2 assessment involving the calculation of flow depths and velocities under flood conditions resulting in the assignment of a Scour Risk Rating and recommendations for management measures. Our requirements from the client include:
- Topographic survey of the bridge showing its key features (abutments, piers, arches, decks) and including cross-sections through the river channel upstream and downstream of the structure. The survey should include details of the bridge foundations (level) and any existing scour protection
- Geotechnical information/boreholes/trial pitting of the bridge foundations to determine whether undercutting of abutments or piers is likely. This would also include obtaining the grading of granular materials forming the riverbed
- A hydrological analysis to determine extreme flows within the channel (usually based on Flood Estimation Handbook techniques) and a hydraulic model of the watercourse to determine the velocity of water running through the bridge structure during peak flow. We are able to undertake the hydrological analysis and hydraulic modelling if an existing hydraulic model is not available from the Environment Agency
Stroma can also remove the debris deposited during flood events, including when the river is in spate.