Rocky Fork Dam is an 80-foot high, high-hazard, concrete gravity dam in Highland County that is owned and operated by the Ohio Department of Natural Resources (ODNR). The dam was constructed in the early 1950's and has had no safety issues nor significant repair work since its construction. The reservoir is controlled by a single 5'x7' sluice gate that is operated by the original gate controls installed in the 1950's.
An inspection of the dam in 2021 indicated that there was some leakage around the sluice gate and that a number of areas of exposed concrete on the dam needed patched or repaired. ODNR implemented a rehabilitation project to repair the concrete and to replace the existing sluice gate. Tetra Tech was hired to prepare the final designs for this work.
The concrete repairs were straightforward but there were several challenges with the new gate design. Unfortunately, the only access to the gate was by entering the outlet of the sluiceway, then walking upstream to the gate. There was no access to the gate from the operating gallery. Obviously, only the downstream side of the gate could be inspected this way.
The original dam designers had specified a reinforced concrete frame around the sluiceway inlet. This frame held a trashrack but was also designed to hold a bulkhead when needed. Unfortunately, there was no housing nor an operator to remove the trashrack or install the bulkhead; divers would have to be used for all of the work. In addition, the condition of the original bulkhead was suspect, so a new steel bulkhead would have to be designed.
Consequently, divers were used to first remove the existing trashrack from the frame and then measure the sluiceway inlet for the new bulkhead design. The new steel bulkhead was then designed and fabricated. In early January, the new steel bulkhead was delivered to the site and installed on the sluiceway inlet. Tetra Tech's engineers and staff from the Construction Manager on the project were able to enter the sluiceway from the downstream end and complete their inspection of the upstream face of the gate and the upstream portion of the sluiceway. Based on the results of this inspection, a new 5'x7' gate is currently being designed for the project. Once the new gate is ready, divers will be used to install the bulkhead again so that the existing gate can be replaced.
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