Dredging to stop as officials prepare landfill
Petersburg officials are improvising as the North Harbor’s dredge material is more fluid than they expected.
Because copper levels were too high to dispose the spoils into the ocean, the original plan was to use the dredge material to cover the landfill’s scrap metal pile but Karl Hagerman, Public Works Director, stated in a report to the borough that when the project began September 12, “it was immediately evident that the material being delivered to the landfill was different than what the sanitation department was expecting.”
The Army Corp of Engineers tested the consistency of the material.
“It is the consistency that was represented in the reports,” said Julie Anderson, the Corp’s Project Manager for the Petersburg dredging project.
But Anderson and Hagerman agree part of the problem is the material vibrates and de-waters as it’s transported from the barge to the landfill.
“It’s fairly clumpy coming out of the barge,” Hagerman said. “It just jiggles and consolidates all of the water and it turns out to be this slurry type of material that doesn’t stand up. It doesn’t stockpile and it just needs to be retained until the water can leave the material and solidifies.”
Rock-N-Road construction is constructing a containment berm from rock in a local quarry. Hagerman said the rock is successfully holding the material and acts as a filter as it de-waters.
“A lot of times with ditch water you’ll see its cloudy and turbid, there’s suspended solids in there,” Hagerman said. “The water coming out of this stuff is not that way. When it dewaters, when it leaves that material, it’s flowing along the muskeg but it’s not bringing any of the material with it.”
As of Friday, 4,000 cubic yards of the dredge material has been placed in the landfill. Hagerman stated in his report that the amount of rock needed to contain the material is not yet known and neither is the amount of material that will come out of the North Harbor.
“The total quantity will definitely eclipse the 5,000 cubic yard initial estimate and could be double this amount or more,” the report states.
Anderson said dredging operations will stop while officials work to complete the berm at the landfill in preparation for the additional spoils.
In the report, Hagerman wrote, the amount of project contingency funds will cover the cost of the change.