Project assistance completion report : High Dam rehabilitation/modernization, USAID grant no. 263-0160

All planned outputs were achieved. The power station, replacement circuit breakers, and relaying protection are operating normally; some of the equipment and the rehabilitation work performed are still under warranty. Leakage rates for the rehabilitated gates on average are less than 5% of the maximum allowable tolerance, which means more water to generate power and less down time for maintenance. The formal and informal training provided by project contractors greatly enhanced the capabilities of High Dam Power Station staff. A computer-based maintenance scheduling program introduced by the Egyptian Electrical Authority (EEA) subsequent to the PACD should complement this training. General lessons learned are as follows. (1) Whenever possible, project contractors and subcontractors should use personnel of the GOE implementing agency in rehabilitation or modernization projects at existing facilities. Use of this procedure in this project gave the contractor ready access to an onsite pool of skilled workers, and enhanced their operation & maintenance (O&M) skills. (2) In rehabilitation work on older power stations, unforeseen conditions are often encountered which require additional work to be performed or justify canceling work found to be unnecessary. USAID showed the necessary flexibility when problems were discovered in the hydraulic gates, 15KV circuit breakers, and other systems which required additional funding. Conversely, original components of the project were deleted when it was found that spare parts could be acquired, thus eliminating replacement of the 132KV circuit breakers. In the FruCon contract, it was discovered that the 150-ton gantry crane main drive reducer had damage due to a faulty design, and that the intake gate lifting mechanism wire rope had been previously damaged; in both cases, the equipment or parts were replaced. Additionally, since removal of rock and concrete in order to place the temporary sealing bulkhead was not permitted by the Ministry of Irrigation, which is responsible for the dam structure, the contractor was required to initiate a design change which allowed the work to continue. Specific lessons are as follows. (1) Replacement of the first 6 units occurred during a drought that had resulted in inordinately low water levels in Lake Nasser, which in turn threatened safe operation of the new runners. At the request of the EEA, additional tests and studies were conducted which have provided the EEA with operating procedures that will extend the range of operation under the most adverse head conditions. (2) The U.S. Bureau of Reclamation (BUREC) has revised many of its testing and inspection procedures based on what was learned in this project, which required exhaustive and rigorous testing of the welding. The comprehensive testing program has been the subject of several technical papers presented at technical association meetings. (3) To ensure that the concrete used to rehabilitate the draft tubes has a compressive strength of 9,800 pounds per square inch, the project: used modern additive materials in mixing the concrete and high-quality assurance procedures throughout the entire batching, placement, and curing of the concrete; imported the cement from the United States (the local cement did not reach the compressive strength requirements), and developed techniques to use liquid nitrogen to cool the aggregate rock in the batching operation. (4) A sophisticated and technically advanced bulkhead device (a sealing barrier) was designed by BUREC for this project which allowed a dry working environment. The use of this large bulkhead (approximately 11 meters by 28 meters) developed for the High Dam will reshape industry practices for similar projects in the future.