Location:
Montgomery County, Ohio

Owner:
Montgomery County Engineer’s Office

Project Completion Date:
2010

Project Description:
Barr & Prevost was retained by the Montgomery County Engineer’s Department to perform underwater inspections on twelve bridges.

To provide the required services at the lowest cost to the County, each bridge site was initially inspected for access, optimal season for lowest water depth, and to determine the actual number of piers that could be susceptible to scour.  This preparation allowed our project team to become familiar with the site conditions so that we could complete each task order efficiently and cost effectively.

In October - November 2009, the substructure units that would be susceptible to scour for each bridge were inspected by a team comprised of a Registered P.E. Level II Bridge Inspector; a Level II Bridge Inspector and a field survey party chief.  All members of the team were scuba-certified.

In general, the procedure involved preparing a ‘grid’ pattern of survey elevations along the face of the foundations and quarter points between spans at approximately 20’ intervals.  For water depths that exceeded 4’, a light weight boat was used to facilitate obtaining the bottom of river elevations.  This is a method that we typically use to obtain channel sections in deep water for hydraulic analysis.

The data points were collected and downloaded to prepare a digital terrain (contour) model of the river bottom around the piers that would be susceptible to scour.  The contour model provides a permanent baseline for future scour inspections.  Additionally, if significant scour depths are noticed, cross sections can easily be prepared to determine accurate fill quantities for repair.