The state Department of Environmental Protection has given its initial approval to a proposed expansion of the coal waste and ash landfill at Allegheny Energy Supply Co.'s Hatfield Ferry Power Station along the Monongahela River in Greene County.

The 180-acre landfill expansion is needed to accommodate additional solid waste that the power plant will produce after it installs a new $650 million air pollution control system to scrub sulfur dioxide from its emissions.

The DEP's environmental assessment of the landfill proposal, commonly referred to as a "harms-benefits analysis," determined that the on-site expansion would be better than opening a new landfill away from the power plant. One reason is that the on-site landfill will eliminate the need for 350 truck trips per day.

"Having the landfill on site is better for the environment and health and safety of area residents," said Ken Bowman, DEP regional director.

If the DEP grants final approval, the expansion of the on-site landfill would add 14.7 million cubic yards of lined disposal capacity, enough for seven years of waste material. The present landfill will be full in one year.

The 1,710-megawatt Hatfield Ferry power plant has long been one of the nation's dirtiest, emitting large amounts of sulfur dioxide, soot and nitrogen oxides.

The pollution control system, scheduled to be installed by 2009, should reduce sulfur dioxide emissions by 255,000 tons and soot emissions by 1,900 tons a year. It will increase the amount of solid waste deposited in the plant's landfill from 445,000 tons to 1.78 million tons a year.

The DEP has notified municipal officials in the area of the landfill permit expansion and has not received any comments from any of them.

The department will now begin a full technical review of the permit application, which must be completed in 90 days. It is accepting public comment about the project throughout the review period.

A public meeting about the permit will be scheduled after DEP receives the completed application and has an opportunity to review it.