T.Y. Lin International was retained by RG&E for work on both Station 5 and the Central Avenue Dam. Work on the Central Avenue Dam included designing a cofferdam to facilitate the installation of a new gate at the dam. The dam in located on the Genesee River and RG&E has performed several gate replacements over the years. Once the cofferdam was in place, it allowed construction crews to replace the gate guides and install the new gate. The cofferdam was designed to withstand 16ft of river water. Two horizontal walers were utilized for the installation of the cofferdam. The bottom waler was a jumbo size beam, W40x277. The design included detailing connection plates to the existing pier to allow the installation of the walers.
TYLI was also retained for work on Station 5, a hydroelectric generating facility. The headgate facility was constructed in 1917 and consisted of an intake structure and dam with six gates, four taintor gates (each 50 feet wide), and two sector gates (each 100 feet wide). A service bridge crosses the entire length of the dam to provide access to the control building, the various operating mechanisms, to carry power and control wiring, and to provide upper support to cofferdams when service to the gates is required. After failure of one of the 100-foot sector gates, the installation of a temporary diversion cofferdam was required.
A review of the original bridge drawings indicated that the service bridge was not designed for the full pond hydrostatic load. To address this situation, TYLI was retained to inspect, evaluate and provide design recommendations so that the pond level could be raised to power generating levels. As part of the investigation, TYLI performed ultra-sonic thickness measurements, analyzed coupons to determine material characteristics, performed structural analysis, and designed remediation details to allow the service bridge to carry the full pond hydrostatic load so that power generation could continue. Due to the material characteristics of the bridge (A7 steel), and the high-stress ranges to which it was subject, there was concern regarding the potential for fracture critical failure. Therefore all repairs and reinforcement details utilized bolted connections and an inspection program to monitor existing weld details.