The bid to expand how much garbage is burned at the downtown Minneapolis incinerator shifted Thursday from City Hall to state agencies.

An appeal to the City Council to approve a higher tonnage limit for the facility next to the new Twins ballpark was sidetracked by Hennepin County and the company that operates the plant for the county. City officials said the county and company intend to seek state approvals first.

The announcement at a council committee came after county and Covanta Energy officials showed up for an appeal hearing, along with a flock of opponents. The latter want the council to uphold the Planning Commission's denial of expanding the facility's maximum tonnage by 21 percent, to an average of 1,212 tons daily.

City planning staff told the council that the county and Covanta indicated they want to seek an amendment to their state air emission permit before obtaining local zoning approvals. Neither Covanta nor county officials involved with the project could be reached afterward for an explanation of the change in strategy. The city permit for the facility contains a limit of a daily average of 1,000 tons per day, which was the limit imposed by state law until that law was amended in 2000.

The council's Zoning and Planning Committee also was told that state officials may be reconsidering an earlier determination that further environmental review for the expansion isn't needed. Although a permit modification can be relatively straightforward, according to state officials, further study of the plant's environmental impacts could lengthen the approval period to up to 18 months from the time a complete application is submitted.

Opponents of the expansion have called for more studies of potential health and other environmental impact of contaminants emitted by the plant. Covanta and Hennepin County have argued that the plant's original review in the 1980s and more recent studies of effects on ballpark users have adequately explored that issue. The ballpark opens next spring, but opponents argue that the facility has a greater effect on downtown workers and residents.

Last week, nine state legislators asked the council to deny the additional tonnage, saying basic questions about its health effects need answering.

Covanta and the county presented data indicating that the facility, which generates electricity and steam, stays well within the limits for air contaminants set by its permit. They argue that air quality in the Twin Cities is affected far more by vehicle emissions than fixed sources such as the burner. They say that the facility affects global warming far less than methane emitted by landfills. Opponents argue that the county, which directs garbage planning within its borders, needs to put greater emphasis on composting and recycling than burning.

Steve Brandt • 612-673-4438