The New York State Department of Environmental Conservation has denied a sand mining company's request to expand over an important aquifer in Bridgehampton after environmentalists criticized the agency last year for failing to scrutinize the plan.

The April 3 decision by the DEC's Albany office reverses a ruling made a year ago by the agency's Long Island office, which concluded the expansion of the mine, known as Sand Land, "will not have a significant adverse impact on the environment" and did not require an extensive review.

The Albany decision said Long Island officials failed to consider Sand Land's side business of processing yard waste and construction debris at the mine, which sits within one of Long Island's nine state-designated Special Groundwater Protection Areas.

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Sand Land officials had sought to expand the 50-acre mine by five acres and dig 40 feet deeper, allowing the mine to continue operating for an estimated 25 years.

John Tintle, the mine owner, and David Eagan, his attorney, did not respond to requests for comment. They are allowed to request a public hearing for an appeal of the DEC's new ruling, which was written by its executive deputy commissioner, Marc Gerstman.

Long Island environmental activists this week celebrated the ruling.

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"I've actually never seen such a strongly worded denial," said Adrienne Esposito, director of Citizens Campaign for the Environment. "It sends a significant message to other sand mines that you can't operate as a free-for-all."

Esposito said it's common for Long Island mines to also operate mulch, compost and debris processing sites, and the new ruling could set a precedent. A 2013 DEC study of a Yaphank compost site found high levels of contaminants, such as the mineral manganese, in nearby wells.

Bridgehampton residents and environmental activists criticized the Sand Land proposal at a November hearing. Environmental groups chastised the DEC's Long Island office for its handling of the case and lobbied DEC Commissioner Joseph Martens to move it to Albany.

Representatives of the agency's Long Island office did not respond to requests for comment. DEC officials on Long Island told Newsday last year that they were only considering the sand mining operation, not the mulch and debris processing, when they deemed the expansion to have no major impact to the environment. Gerstman said those side operations must be considered.

In the new ruling, Gerstman cited a federal report that faulted Sand Land's owners in the February 2014 death of a worker at a different mine they operate in East Quogue. Declan Boland, 50, died after a poorly maintained slope collapsed and buried him as he was climbing to put out a fire, according to the Mine Safety and Health Administration.

Gerstman also noted that Sand Land's operators had received 21 federal safety violations between 2009 and 2015. "These violations have direct applicability to Sand Land's operations," he wrote.