A massive dredging project at the Port of Hueneme that had been held up for decades because of sediment contamination was approved Friday by the California Coastal Commission.

The proposed solution is to dig a hole underwater in the harbor, fill it with the contaminated sediment from an area estimated to be about 70 acres of surrounding seafloor, and then cap it with sand and gravel.

"It's designed to be safe for more than 8,000 years," said Anthony Taormina, executive director the Oxnard Port District, which oversees the commercial operations at the Port of Hueneme.

The sediment is contaminated by such things as pesticides, tributylin and PCBs, but not to a level where they would be considered hazardous materials. Much of the pollution came from sources that were off the base and outside of the harbor, such as an Oxnard sewage treatment plant and urban and agricultural runoff. The tributylin, or TBT, is likely from anti-fouling paints used in ship building.

It took some time to come up with a way to safely dispose of the polluted sediment, but the port has to be dredged to remain viable, Taormina said.

Similar "confined aquatic disposal" sites have been created at the port in Tacoma, Wash., and in the 1990s in the ports at Long Beach and Los Angeles.

While the $13 million project will take more than a year of around-the-clock, seven-days-a-week work to complete, it's much cheaper than the alternative of trucking the dredged material to a landfill. One estimate for trucking out debris was about $32 million.

The district recently completed a mitigated negative declaration on the dredging proposal, in lieu of a full environmental review.

The efficacy of that document, which concludes the environmental impacts of digging up and burying an estimated 327,000 cubic yards of material does not warrant more in-depth study, will be voted on by the Oxnard Harbor District board. An information-only item is on the agenda, which can be viewed at http://www.portofhueneme.org. The board's meeting is at 5 p.m. Monday.

Sediment has piled up to depths of 10 to 14 feet in some spots, Taormina said.

"It's critical both for the Navy and the harbor district to ensure harbor operations, and provide the design depths for commercial and Navy vessels to come in and out of the port."

The areas around the Oxnard Harbor District wharfs have not been dredged for almost two decades, while the Navy berths were last dredged in 1965.

The Coastal Commission's approval of the dredging plan came over the objections of the Los Padres chapter of the Sierra Club.

Al Sanders, the conservation chairman for the group, argued the plan should have a more extensive environmental review to look at the potential impacts of the project.

But Navy and Oxnard Harbor District officials argued this was by far the most environmentally sound solution to cleaning up the polluted sediment and clearing the areas where shallow water levels are preventing access to ship traffic.