Tracey Bell of National Grid
Andrew Prophete of National Grid
Gary Riley, Environmental Protection Chair
Community Board 6
Last night, at a special Community Board 6's Public Safety/Environmental Protection and Permits & Licenses Committee meeting, Tracey Bell, Andrew Prophete and Michael Zukauskas of National Grid, together with some of their colleagues, gave the community an update on the development of their remediation plan for the heavily contaminated former gas manufacturing site in Carroll Gardens.
NYS Department Of Environmental Conservation, which is overseeing the brownfield clean-up, was supposed to attend as well, but were unable to travel due to the recent hurricane.
The vast track of land, located between Smith Street and the Gowanus Canal, was once the site of a Citizens Gas Light Company's 12th Ward Gas Work plant where coal and petroleum products into flammable gas for surrounding neighborhoods. Citizen later sold to Brooklyn Union Gas, which became Keyspan, which is now National Grid.The plant was decommissioned in the early 1960's.
What was left behind was a heavily contaminated site. The results of the Remediation Investigation showed contaminants like coal tar in depths up to 150 feet in the ground.
The responsibility for the clean-up falls on National Grid under the supervision of NYS DEC.
To date, National Grid has completed 50% of their remediation design, which has been approved by DEC. Tracey Bell, Andrew Prophete and Michael Zukauskas, in their presentation, stressed that the site presents enormous challenges and that the clean-up is highly complex.
First, there are the enormous amounts of coal tar which saturates the ground. The remedial design calls for a number of recovery wells on the site, into which the tar will collect, so that it can be taken away. (Since December 2010 alone, 7,000 gallons of the tar have been pumped out of the ground.)
Second, the coal tar has been oozing into the Gowanus Canal for decades. To prevent the lateral movement of contaminants into the waterway, the remedial design will include an elaborate 50 foot sheet pile construction wall which will serve as a barrier. The fence will be 25 feet below the canal's mud line and 25 feet above. The joints will be heavily reinforced.
Thirdly, the 72" Bond Street sewer line traverses the site. A section of the mostly brick tunnel needs to be relocated because its current location will interfere with the construction of the barrier wall. Since the flushing tunnel is still in use, the work will need to be carefully coordinated.
The proposed remediation calls for the removal of the top 8 feet of soil throughout the site, which will be backfilled with clean soil to street level.
As part of storm water management and to prevent ground water from leaking into the canal, a High Density Polyethylene (HDPE) liner will be installed 2 feet below grade throughout.
The next step for National Grid is to perform pilot tests for feasibility and on all materials.
The company representatives made sure to mention that these tests will be loud and sometimes disruptive. "We will be moving lots of heavy machinery onto the site." Mr. Phrophete warned.
After the presentation, Gary Reilly, chair of CB6's Environmental Protection Committee, asked National Grid's representatives how the site's remediation plan has changed since the US Environmental Protection Agency declares the Gowanus Canal a Superfund site in 2010. The (EPA has named National Grid as a Potential Responsible Party for the company's role in polluting the canal.)
Andrew Prophete answered that the federal agency has concerns about the design for the barrier wall, the 8 foot cap and the safety of building on the site. "We want to convey that its a safe and constructible design" Mr. Prophete stated. "I am not sure the EPA is totally convinced yet."
He was also quick to mention that the DEC, not EPA is supervising this brownfield clean-up and that DEC has authorized National Grid to move ahead with the already approved remedial plan.
For further information or updates on the remedial work, go to National Grid's Citizen's website here.
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