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DENVER — The contractor on the Central 70 Project received a noise variance early Friday morning to do overnight construction work for the next year.

The Denver Board of Public Health and Environment voted, 3-2, after midnight, to give Kiewit Infrastructure the variance from normal nighttime noise limits.

The construction company had asked for the variance to last for the four years of the $1.2 billion expansion project of Interstate 70 through northeast Denver.

But the board, after a seven-hour hearing, limited the variance to one year as a way for the contractor to be held accountable.

Kiewit officials will put up temporary sound walls and take other measures, including giving hotel vouchers to residents where noises at night will be the loudest.

The demolition of large bridges will have to happen at night as a way to keep the busy interstate open during the day, the contractor said.

The 10-mile stretch of Interstate 70 between Brighton Boulevard and Chambers Road is being widened and a toll lane will be added. And much of the new road will be put below ground.

That will entail the demolition of the viaducts between Brighton and Colorado boulevards with a park built on top.

At that time, traffic will be diverted into a massive open-air trench that will be build alongside the viaduct. And everything will be detoured.

The project, which broke ground last month, is expected to be completed in 2022.