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Printed on:Thursday 02/06/2025 01:08 PM 29C0486/AAAA/147978Pageof4 Department of Transportation - Division of Maintenance Structure Maintenance & Investigations 9 SCOPE AND ACCESS This report summarizes the findings of a field review conducted on 12/12/2024 by the Structure Maintenance & Investigations - Local Agency Hydraulics Branch. There was approximately 12 inches of water flowing in Span 1 at time of inspection. All spans were accessible to probe. The only National Bridge Inventory (NBI) Item reviewed was the Item 113 Scour Code (and applicable SNBI codes - see REVISIONS below). All other NBI codes and elements ratings were carried over from the 4/25/2024 Routine Inspection Report. ORIENTATION The report follows (SM&I) convention and orients the bridge south to north. The south abutment is designated as Abutment 1. HISTORY The only inspection report dated 4/25/2024 mentions exposed footings up to 18 inches vertically at Abutment 1, Pier 2 and Pier 3 on Span 2 side. This report also mentions undermining of Pier 3 on Span 2 side up to 6 inches along the whole length. There are no plans available in Caltrans archive. WATERWAY The channel opening is well aligned to the bridge. It consists of fines and clayey material. A cross section was taken and compared to the previous cross section taken on 4/25/2024. There are no significant changes. SCOUR EVALUATION The footing at Abutment 1 is fully exposed up to 11 inches. Probing along the footing of Abutment 1 concluded that there is undermining of up to 2 inches vertically and 2 to 3 feet horizontally for the entire length. The footing at Pier 2 is fully exposed up to 18 inches on both the Span 1 and Span 2 sides. There is undermining of 2 inches vertically and 4 to 6 inches horizontally for the entire length on Span 1 side. The footing of Pier 2 on Span 2 side is exposed up to 18 inches vertically for the entire length. No undermining was noted. The footing of Pier 3 on Span 2 side is exposed up to 15 inches vertically for the entire length. No undermining was noted. SCOUR CONSIDERATIONS There is scour and undermining in Abutment 1, Pier 2 and Pier 3. Dense material was encountered when probing underneath the footings at all foundations. This material may have a slow rate of scour, but it is not considered non-scourable. For these reasons the bridge is considered scour critical at this time. REVISIONS The National Bridge Inventory Item 113 Code (Scour), has been changed from 6: "Scour calculation/evaluation has not been made." to 3: "Bridge is scour critical; bridge foundations determined to be unstable for assessed or calculated scour conditions". A new federal coding guide is forthcoming. The new guide is the Specifications for the National Bridge Inventory (SNBI). The NBI 113 scour code will be replaced with the SNBI Scour Vulnerability code. During the transition, SMI bridge reports will document both the 113 and the Scour Vulnerability codes. The Scour Vulnerability code has been assigned to D: "Scour appraisal completed. Bridge is, or may become, unstable for scour. Bridge is scour critical." The Channel Protection code has been assigned a N (Not Applicable). No channel protection was noted. The Scour Condition Rating has been assigned a 4 (Poor). The Channel Condition Rating is a 6 (Satisfactory). RECOMMENDATIONS Mitigate the scour vulnerability of the foundations as described in Work Recommendations. INSPECTION COMMENTARY CONDITION INFORMATION