BANGOR, Maine — The dredging needed to clean up coal tar that was deposited along the Penobscot River’s shoreline years ago has been delayed by a week, a consultant said Monday.
The dredging originally was scheduled to begin today, but has been postponed until Monday, Sept. 21, Eugene McLinn, who works for Wisconsin consultant firm RMT Inc., the business hired to do the work.
“There was a delay in getting some of the materials, the turbidity curtains,” he said. “Those are the curtains set up to keep the soils in and the fish out” while the dredging work is conducted.
McLinn, who also is a geologist, has worked with city officials for 11 years to find a solution to Bangor’s coal tar problem.
Workers could be seen Monday installing a portion of the bright orange containment curtain, which floats on the surface and extends down to the riverbed.
Brewer resident Lesley Spaulding Sr. sat watching the operation at midday Monday from the Brewer side of the river, something the octogenarian says he does “seven days a week.” In his vehicle were two pairs of binoculars and a camera.
“They burned coal to make the gas for all the homes,” he said, recalling a time in his youth when residents used the Bon Ton II ferry to travel between Bangor and Brewer.
Coal tar is a known carcinogen and was deposited along the riverbed by Bangor Gas Works, which operated from 1881 to 1963 on land where Shaw’s supermarket now sits. The dark and gooey substance is a byproduct of gas manufacturing and was deposited in the river through an old stone sewer that connected to the Main Street gas plant.
The $7 million cleanup and containment project will remove 6,000 to 7,000 cubic yards of tainted and smelly sediment, approximately 10,000 tons, from the river’s edge over a 15-day period.
Once the coal tar-contaminated materials are removed from the water they will be taken to an interim warehouse set up behind the new Tim Hortons coffee shop on Main Street, for treatment before being shipped to the Juniper Ridge landfill in Old Town or the Pine Tree landfill in Hampden.
A sloped stone cap eventually will seal off the contaminated area and trap any remaining toxic tar, while allowing methane and other gases to escape.
The cap will be constructed of a layer of clay and an impermeable layer that allows gases through but not the remaining tar droplets. Those gases will be vented along the waterfront, and the top of the cap will be created with stones that will resemble a regular Maine shoreline, McLinn has said.
Settlement funds from Citizens Communications Co., a group of third parties a federal judge ruled was responsible for a majority of the cleanup, will fund the project. Bangor tax increment financing district funds will cover any additional costs.
Once the dredging work begins, “we’ll do this work rain or shine,” McLinn said.