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Boulder County Floodplain Compliance

Boulder County suffered devastating floods in September of 2013. Many homes in Boulder County were completely damaged or had access cut off during the floods. As the community began to be rebuilt, many bridges were built over waterways to regain access to homes and many of the bridges were not permitted.The inspections by Matrix provided relevant structural capacity and hydraulic opening information about the bridges to lead to future compliance or other corrective action by the County.

Matrix was hired to inspect 30 private driveway bridges in Boulder County to determine if they were compliant with County transportation and drainage standards. These structures provide access from residences to the main arterials in Boulder County and were either damaged during the September 2013 floods or reconstructed after them. The bridges primarily consisted of timber and steel girder superstructures, timber and concrete bridge decks, and shallow foundation substructures. To analyze compliance, Matrix inspected the bridges to determine their structural capacity and the maximum storm event each could pass within their hydraulic openings. The structures were inspected in accordance with Federal Highway Administration (FHWA)-National Highway Institute (NHI) criteria. Data was collected on all bridge elements so that load ratings could be performed for vehicular and pedestrian loadings. All data was imported into Boulder County’s asset management program to categorize which structures may need to be rehabilitated or replaced.

The data collected during this project provided the County with the necessary information to take appropriate measures to mitigate future damage during flood events.