GREEN BAY - Six months after overwhelmingly approving $5.3 million in aid to help a local paper mill grow, Brown County supervisors will be asked to increase that contribution by almost $3 million.

That's because the county's original estimate of site-work costs for the Green Bay Packaging Inc. expansion fell about $6.5 million short of what it will cost to do the necessary work, lawmakers were told in a closed-door meeting on Dec. 10.

The impact: Supervisors on Wednesday will be asked to authorize $2.95 million in additional funding to do work that includes building a retention pond, and running a large water line about one-half mile to the NEW Water plant on the opposite side of Interstate 43 from the mill.

Green Bay Packaging has agreed to pay an additional $3.66 million, county officials said.

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"This was the best deal we could work out," county Administration Director Chad Weininger said.

Some supervisors indicated they find the request for an increase troubling. The county board's chairman, though, said it doesn't appear that supervisors can do much but approve the increase.

"The numbers we voted on in June were hard numbers at the time, but once (work started), they weren't," Chairman Patrick Moynihan Jr. said Thursday. "But what do we do? If we say no to the increase, we're going to get sued."

County officials would first be asked to recommend approval at a special committee meeting Wednesday. If a majority of the committee approves, the increase would then need the approval of two-thirds of the full board to go forward.

Officials don't believe the issue will dramatically change the timeline for the project, if it gains approval Wednesday. The timeline projects the new mill to be operational and its predecessor to shut down around 2021.

"If we don't get approval, it's back to the drawing board," said Corporation Counsel David Hemery. "And the best-case scenario would be a delayed project."

A key issue driving the cost increase is the need to install a major pipeline from the paper mill to NEW Water. The county had hoped to run it above ground along the west side of North Quincy Street, then proposed an underground path, but learned that utilities installed previously are blocking the path.

The project also needs an additional pumping station, which would be off Quincy between Chip Street and Bay Beach Road. Quincy Street would also have to be rebuilt once the project is complete, Hemery said.

The pipeline issue, which Public Works Director Paul Fontecchio likened to "a land mine," means the pipe must be buried 18 to 20 feet deep, significantly increasing the cost. The line would enable water from the plant to be treated and reused, rather than merely pumped into the Fox River.

Fontecchio said it's rarely easy to project the cost of a project that will take years to complete.

"In the spring we were asked to put together an estimate, which was very preliminary and based on the information we had at the time," he said. "We do millions of dollars in projects each year. Some come in under budget and some come in over budget."

The $3 million would come from the county's general fund, officials said. The fund now has a balance of almost $23 million.

A $3 million surprise like this typically would prompt a county to borrow the money, but supervisors agreed in June not to do additional borrowing while the county is collecting a local sales tax. The 0.5 percent tax, which began in January, could last until 2024.

Supervisors who chair each of the county board's seven standing committees discussed the issue during the Dec. 10 closed-door meeting with Executive Troy Streckenbach, Administration Director Chad Weininger and the county attorney, Corporation Counsel David Hemery.

RELATED: Green Bay Packaging to expand, add up to 200 jobs, invest over $580M

A person who attended the briefing said officials discussed the need to provide more funding, and circulated drawings indicating the increase would hike the project's cost by at least $5 million, and as much as $8.9 million. Larger increases were considered, but rejected.

That person, who spoke on the condition of anonymity because the meeting had been closed to the public, likened the news to a scene from a famous mobster movie.

"It felt like (board members) got 'Godfathered.' — You know, 'We're going to make you an offer you can't refuse.'"

Supervisors in mid-June voted 23-1 to authorize the county to do $5.3 million worth of work to improve the site, which is in an industrial area near Webster Avenue and Interstate 43 on the city's northeast side. With the latest increase, the county's share of the cost would be just over $8 million.

The board was supportive, though De Pere Supervisor Jim Kneiszel raised concerns at the time that members were given little time to consider the proposal.

"This is a $5 million expenditure," he said at the time. "And as valid as it looks to me, I don’t understand why we couldn’t have at least a month" to study the proposal.

The county is not the only contributor to Green Bay Packaging's $580-million expansion plan, which would retain about 600 area jobs and is expected to eventually add up to 200 more.

RELATED: Green Bay panel OKs $23M tax-rebate plan for GB Packaging

The city of Green Bay committed to roughly $23 million in tax breaks. The state contributed $60 million in enterprise-zone tax credits.

The new mill would increase output at the site from 600 tons of product a day to 1,400 or 1,500 tons per day. The firm ships product from Green Bay by truck and rail to companies that produce corrugated boxes.