Virginia Power yesterday for the second time asked the State Corporation Commission to let it raise electric rates to pay for its Bath County pumped storage facility.

The utility said it has asked to increase consumer electric rates by $68 million, or 2.5 percent, starting Oct. 15, when the new Bath County plant is scheduled to go into operation.

If the request is granted, an average 1,000-kilowatt-hour monthly bill will have risen from $68.82 in October 1983 to $71.25 in October 1985.

Virginia Power first sought an increase in rates of $90 million last November. It split the request into two parts -- one for increased fuel costs and the other for expenses of the Bath County plant.

The Bath County plant is supposed by save consumers money by allowing Virginia Power to generate power at night and other times when use of power is low and store it for use later. To do so, Virginia Power built two lakes -- one a thousand feet above the other -- connected by tunnels. To store power, water is pumped into the upper lake. When electricity is needed, the water is released to plunge down the mountain and spin hydroelectric generators.

Last spring, Virginia Power discovered the tunnels were leaking, and amended its application to call for a $19 million decrease in electric rates because of falling fuel costs.

Virginia Power is injecting concrete into fissures in the mountainside around the tunnels to stop further leakage, said a spokesman. The SCC is investigating the project, reviewing steps the utility is taking to prevent further leakage, and studying whether the plant was properly engineered in the first place.

The Bath County project has been riddled with economic problems.

In 1980, Virginia Power laid off 2,500 workers and delayed the completion date of the plant from 1983 to 1985 because of a sharp slowdown in demand for electricity. The delays have added $460 million to the cost of the project.

In its filing, Virginia Power officials called the rate increase request modest.

"Bringing a massive generating facility on line with such a modest increase in rates is an extraordinary accomplishment," said Jack Ferguson, president and chief operating officer.