MIAMI (CBSMiami) – The dirt is clean and that’s good news for the international consortium behind the on-going $1 billion Port of Miami tunnel dig.

According to CBS4 News partner the Miami Herald, state environmental regulators have approved a controversial plan to deposit soil from the tunnel dig on Virginia Key after testing showed the crushed rock to be clean.

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The State Department of Environmental Protection issued a soil-management permit to Miami Access Tunnel, the international consortium building the $1 billion tunnel, that allows contractors to deposit up to 280,000 cubic yards of fill on the key’s North Point, where the city of Miami plans to use it for environmental restoration.

The DEP earlier this month also approved a second permit for the addition of two lanes to the MacArthur Causeway bridge to accommodate the heavy truck traffic that will use the tunnel, which will connect Watson Island to the port’s Dodge Island beneath Biscayne Bay. That work will add a lane of traffic in each director in the gap at the center of the bridge, and is already under way.

“Harriet” the giant tunnel boring machine, started digging in November.

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The DEP said testing of samples will continue throughout the dig to make sure it remains clean and is good enough for use in residential construction under state standards.

Concerns about the material centered on the tunnel boring machine’s use of lubricants and chemicals sometimes injected into the porous limestone beneath the bay bottom to soften the rock for drilling.

The MacArthur bridge expansion is the first phase in a long-term state plan to rebuild the connection between Interstate 95 and the causeway to Miami Beach. The state Department of Transportation plans to replace the antiquated Interstate 395 span with a safer, more aesthetically pleasing connector, but not until 2021 at the earliest. In the meantime, FDOT plans a temporary makeover and reconfiguration of lanes to accommodate the expected truck traffic once the tunnel opens in 2014.

That will be the first time that port truck traffic can go directly from the interstate to the port.

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