In 2014, Bayside Engineering designed an embedded 6′ x 8′ MassDOT/ACOE stream-crossing-compliant culvert replacement on Main Street in Boxford. The culvert replaced a 100 year old 42″ square field stone culvert. The replacement was completed in 4 consecutive days, including paving. These one year inspection photos reflect the accuracy of the hydraulic model and proper culvert size selection.
Financial constraints precluded the relocation of the crossing to eliminate a bend in the channel at the entrance. As such, the culvert entrance was designed with carefully placed large stones rather than dumped rip-rap to help dissipate stream energy at the bend. The width of the culvert was designed to allow for streambed movement similar to the natural stream process. We were pleased to find that there was no scour at the culvert entrance stones and the stream has moved material within the culvert as designed.
The downstream channel stream bed aggregate size is similar to the channel upstream which reflects a barrel velocity that is the same as the channel velocity.
The stream within the culvert has deposited stream bed material creating wildlife refuge areas and permits variable velocity zones in the stream. High-water staining is consistent with the design objective of providing a span that accommodates the 1 year flow event with a similar channel depth to the upstream channel.
The culvert replacement has provided superior wildlife connectivity and reduced downstream erosion.
The project was completed on-time and under budget resulting in an excellent example of how wildlife-sensitive infrastructure upgrades can be accomplished in a timely manner.