PONCA CITY – The City (City of Ponca City) is in the process of repairing the Lake Ponca Dam Spillway Crest. The Engineer for the project, Freese and Nichols, was retained by the City in 2018. The General Contractor Restek, Inc. started the construction phase in October 2019. The project is expected to be completed in May 2020, and the total cost is approximately $2 million.
The spillway, built in the 1930s, is located at the northwest end of the West Lake Ponca Dam. As an emergency structure, it was designed and built to function in extreme conditions to prevent overtopping of the dam. During flooding events, this spillway empties large quantity of excessive water into a natural channel.
The main tasks of this repair project include:
- Demolition and removal of the existing weathered concrete overlay on the crest section, which is approximate 19 ft. long and 245 ft. wide.
- Installation of steel reinforcement and rock anchors to resist uplift force during flood loading and improve the structural integrity of the spillway crest.
- Subsequently, a reinforced concrete wall will be constructed against the upstream side of the spillway’s vertical face to provide long-term protection.
- As a final step, a new concrete overlay will be constructed onto the crest section.
The construction is split into two phases. Phase I is to repair the west half of the spillway crest and Phase II is to repair the east half. Therefore, half of this emergency structure will remain in service throughout the entire process.
A temporary cofferdam with active dewatering and bypass system is being used to avoid the lake level lowering during construction, so that recreational activities are not affected.
Photo caption 1: Aerial view of the Lake Ponca Dam Spillway.
Photo Caption 2: A cofferdam is being used on the west half of the spillway.
Photo Caption 3: The east half of the spillway releases excessive water, while the west half of the crest is being repaired.
All images shared were provided by the City of Ponca City.
