While EKPC’s application for a US$43M rise in annual rates is still pending, the US state’s Public Service Commission has granted an almost immediate rate rise of US$19M which will be passed on to customers of its distribution cooperatives. EKPC consists of 16 cooperatives and its financial difficulties could affect the reliability of energy services, noted the Commission in a statement. The financial problems are being probed by the Commission, the review having started in 2006.

Giving more information on the nature of the financial problems, the Commission added that reduced generation output had forced EKPC to buy more expensive electricity from outside its system, that there was the possibility of fines over alleged environment violations at some plants, and that its credit rating was lower because borrowings were higher. It also said EKPC was currently unable to meet certain payments to the Rural Utilites Service, a federal agency that loans to such coooperatives at favourable rates.

In addition, the reservoir of Lake Cumberland has been partially drawn down for safety reasons at Wolf Creek dam. Apart from about US$25M in costs to maintain its operations at Cooper hydro plant at the reservoir due to the reduced economic capacity of the reservoir, EKPC will also have to buy electricity from outside to replace the inexpensive power normally received from the US Army Corps of Engineers (USACE) plant at Wolf Creek dam.

In January, theUSACE Nashville District announced an immediate draw down in the level of Lake Cumberland to about 207m following the findings of studies that classified Wolf Creek dam as a having ‘high risk’ of structural failure. The reservoir is the largest east of the Mississippi and the ninth biggest in the US.

Levels in Lake Cumberland are usually 220m in summer, 210m in winter. Maximum pool elevation is 232m. The emergency reduction in water level to about 207m will be held for the rest of this year. USACE said the action would both reduce pressure on the structure and foundation seepage.

Wolf Creek, designed and built over 1938-52, is a 1748m long dam built as a combination of rolled earth fill and concrete gravity structure. Maximum height above foundation level is 79m. Its power plant has six turbine-generators with a total installed capacity of 270MW.

Foundation seepage, caused primarily by the underlying karst limestone, has been the key problem at Wolf Creek dam and works are ongoing with an accelerated grouting programme. Seepage problems were first noted in 1968 with muddy flows in the tailrace and two sinkholes appearing near the toe of the dam embankment. Since then there has been initial grouting works, then a diaphragm wall was installed.

USACE has stated that Wolf Creek is one of the highest risk dams in its inventory. As such, a further grouting programme is underway and a concrete diaphragm wall is to be built hundreds of feet below the existing wall. USACE has said the works could cost more than US$300M but have a benefit to cost ratio of seven to one. Works recently began and are scheduled for completion in 2014.

At present, 15 holes have been grouted of the 19 drilled to date parallel to the dam’s gallery.