The Davis County waste-to-energy plant is back in full operation as its contractor makes sure that pollutants it produces don't exceed levels recently set by a state variance.

The plant has doubled its input of garbage and fired up a second boiler. The amount of garbage burned each day has been increased from 200 tons to 400 tons, said Jim Young, manager of the Davis County Solid Waste Management and Energy Recovery Special Service District."We are taking all garbage except that which is not processable like dirt, rocks and large metal objects," Young said.

The plant had been diverting garbage because it was exceeding nitrogen oxide pollution levels set by a state permit granted last year.

The Utah Air Conservation Committee approved a variance Aug. 17 allowing the plant to increase nitrogen oxide pollution. The plant is now allowed to discharge 84 pounds per hour of nitrogen dioxides rather than the former ceiling of 30.1 pounds.

Nitrogen oxide, in combination with other air pollution and sunlight, causes an erosion of the earth's ozone layer. Scientists believe that a depleted ozone layer could lead to the "greenhouse effect" or warming of the earth's atmosphere.

State officials said they were willing to grant the variance because of erroneous pollution projections provided by the contractor, Katy-Seghers, on which the original permit was based.

Besides increasing garbage loads, the special service district wanted the variance because of an obligation to supply steam to Hill Air Force Base. The plants burns garbage to produce steam.

The state is expected to grant a permanent permit with the higher pollution levels on Oct. 1. After a public comment period, the special service district expects to cross one of the last hurdles for the plant to go into sustained operation.

"We look forward to Oct. 15. We're cautiously optimistic. Our engineers have been giving us very favorable reports, and we are anxiously waiting for the final recommendation on the facility," Young said.

The plant, which cost $54 million in construction and finance fees, has been plagued by cost overruns and delays.

Burnell Cordner, Bureau of Air Quality director, said even with the new permit, levels will still be far less than most waste-to-energy plants in the United States.