A federal appeals court has refused to overturn a US$2.6m settlement in a dispute over mercury pollution from a cement factory in Alpena.

The decision last week comes more than nine years after a group of Alpena residents filed a lawsuit against Lafarge Corp in federal court in Detroit.

"It is a close call as to whether the district court should have approved the settlement agreement," the appeals court said, referring to US District Judge David Lawson.

"The district court is much nearer to this case than we are, and where the balance is close, we cannot say that the district court abused its discretion in finding the settlement to be fair, reasonable, and adequate," the three-judge panel said.

Under the deal, $1.9 million will be set aside for residents and the lawyers who represented them. It’s not known how many people will apply for compensation. In addition, $700,000 will be spent to pave a road and improve dust collection at the plant.

The settlement was appealed by some of the original plaintiffs who objected to it for several reasons. The appeals court seemed to agree on some points, but not enough to tip the balance.

"The settlement agreement does not entirely comport with the public interest since it does not address the most significant environmental hazards created by the Lafarge plant, such as mercury emissions," the appeals court said.

"Settlements are compromises and therefore plaintiffs cannot get everything they want," the court said.