CS19B - Concurrent Session 19B: Back in Time: An Actual Look Inside of a 120-Year-Old Timber Crib Dam

Abstract Description: The Twin Branch Hydroelectric Project is located on the St. Joseph River in Mishawaka, Indiana. Originally constructed in 1903, the facility includes two rollway spillway sections separated by a tainter gate section that was added during a major rehabilitation in the early 1920s. The hydroelectric powerhouse unit is situated at the south (left) abutment of the dam. All three spillway sections are supported on a rock-filled timber cribbing system.

This presentation will focus on investigations conducted at the site in 2019 and 2020, where modern technology was used to capture actual videos and still pictures inside of the 120-year-old timber crib matrix. The videos and pictures revealed information and details not previously disclosed by the original construction drawings or other investigations. This includes visual condition of the timbers, timber cribbing connection details, as well as the effects of time and “modern society” on the timber cribbing system.