As a result of the decline in Lake Mead's elevation since 1999, the US Bureau of Reclamation (USBR), in consultation with power customers, has initiated a programme to modify the turbines at Hoover dam to increase their electrical generating capacity at lower lake levels.
In 2005, USBR installed new stainless steel wicket gates in Unit A-1, one of 17 commercial hydroelectric turbine generators at the dam. Changing the wicket gates enabled the unit to be operated with an additional 8MW of available capacity when Lake Mead’s elevation is at 349m above sea level or lower.
Similar results are expected for two other units, one of which received new stainless steel gates this year, and another that will receive new wicket gates in 2007.
‘The turbines at Hoover dam were originally built with cast-steel wicket gates. Newer materials and designs allow for more water flow through the gates, which results in additional available electric capacity,’ said John Keys, Commissioner of USBR. ‘The lower lake elevations resulting from the drought make this is an opportune time to investigate and proceed with wicket gate modifications.’
On 3 March 2006, USBR awarded a US$195,648 contract to Precision Machine & Supply to conduct an analytical study to maximise the turbine system electrical generating capacity and performance of seven additional generating units at the dam, three on the Arizona side and four on the Nevada side.
After an evaluation of the analytical design study, USBR may opt to purchase additional wicket gates for one or more of the seven units. If all the contract options are exercised, the contract value will be more than US$5M over three years.