All bridges over waterways require a scour evaluation and a completed Scour Summary Sheet. The Scour Summary Sheet must be signed and sealed by an engineer and entered into the bridge inspection management system (BIMS) by District Bridge Inspection Staff. Scour evaluation documentation must also be entered into the BIMS. The results of the scour evaluation will determine the Bridge Inspection Coding for Item 113 – Scour. The table below defines the minimum scour design flood frequencies and scour design check flood frequencies for a given hydraulic design flood frequency. These values are to be used to ensure that a bridge will remain stable for a given design flood frequency.

Table 5-3: Hydraulic Design, Scour Design, and Scour Design Check Flood Frequencies

Hydraulic Design Flood Frequency, Q D	Scour Design Flood Frequency, Q S *	Scour Design Check Flood Frequency, Q C *
Q 10	Q 25	Q 50
Q 25	Q 50	Q 100
Q 50	Q 100	Q 200
Q 100	Q 200	Q 500

* Use the values listed or the overtopping event, whichever is the lower event.