The new runner is scheduled for delivery to the dam in February 2012 for installation by USBR. If it performs as anticipated, USBR may exercise a contract option for additional runners for generating units N-6, A-1, and N-5. If the contract option is exercised, the total investment in the new turbines will be approximately $11.56M. If ordered, the additional runners would arrive at the dam in November 2013, 2014 and 2015, respectively.
There are 17 commercial generators in the Hoover Dam power plant – nine in the Arizona wing and eight in the Nevada wing. Since 1947, an average of about 4.4BkWh of energy has been generated at the dam annually. The energy is marketed to customers in southern California, southern Nevada and Arizona under 30-year contracts signed in 1987.
The existing turbines at Hoover Dam are designed, in general, to operate over a higher range of lake levels. At very low lake levels, operation of existing turbines becomes rough and inefficient.
For example, the existing N-8 turbine is designed to operate when Lake Mead is as low as elevation 1050ft above mean sea level (msl), but will operate more roughly below that level. The new N-8 turbine will be designed to operate smoothly and efficiently at lake levels down to elevation 1000 msl. Lake Mead is currently at elevation 1099 feet msl, or about 120 ft below the full operating level. The water level has dropped as Hoover Dam has continued to provide consistent water deliveries to Colorado River water users in the Lower Colorado River Basin during the worst drought on record in the basin since the early 1900’s.
