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Opaeula No. 1 (Oahu) Dam Improvements

Opaeula No. 1 Reservoir's primary spillway required maintenance, which is one of the most important aspects of a well-operating reservoir. Oceanit provided Kamehameha Schools with engineering services for the construction of improvements to three of its dams.

Kamehameha Schools owns three dams which are registered and identified on both federal and state inventories as dam reservoirs under regulatory jurisdiction of the State’s dam safety program. The dams are Opaeula No. 1 and No. 2 Reservoirs on the north shore of Oahu, and Lalakea Reservoir in the Hamakua District on the Island of Hawaii.

Oceanit provided Kamehameha Schools with innovative engineering services to design, prepare construction documents, and secure required permitting for the construction of improvements to all three dams that incorporated and blended seamlessly into the natural, remote, mountainous environments. Topographic surveys and cadastral services were conducted for the areas under consideration for proposed improvements. Following a review of existing dam and adjacent area conditions, field inspections and assessments, historical architectural surveys, and geotechnical investigations were completed for each dam. Based on the survey and field data, an engineering design report was submitted for each of these dams.

Construction plans, specifications, cost estimates, schedules, and necessary permits for dam removal will be completed for Lalakea, as the entire dam will be decommissioned.

Similar documents and plans are being provided for Opaeula No. 1 and No. 2 Reservoir improvements, that will consist of constructing secondary spillways through the adjacent abutments and grading of earth buttresses on the downstream face of the dams.

For Opaeula No. 1, Oceanit designed improvements which included a new spillway structure, slope stabilization, improved outlet flow control facilities, and an instrumentation / monitoring system. We also prepared an Operation and Maintenance (O&M) manual required by the State of Hawaii, and provided agency coordination and support for the reservoir's Emergency Action Plan (EAP).

Altogether, for all three dams, Oceanit delivered an engineering design report, construction documents, government agency approvals and permits (dam safety, NPDES and grading), services during the construction bidding process, and post design services.