OSWEGO National Grid will begin remediation of 90-year-old chemical contamination north of Utica Street between West Third and Fourth streets beginning in April, according to the state Department of Environmental Conservation.

The contamination is related to the Niagara Mohawk Oswego West Utica Street Manufactured Gas Plant (MGP) site, located at 27 W. Utica St. The plant operated between the 1850s and 1930s.

Remedial activities are expected to last about seven months at an estimated cost to the DEC of $3 million. There will be no cost to the city of Oswego.

On Monday, March 16, the DEC postponed a public informational session regarding the cleanup originally scheduled for 6 p.m. Thursday, March 26 at the Oswego County Fire Response Training Center, 720 East Seneca St. The DEC will notify the public when the public session has been rescheduled.

According to the DEC, environmental investigations of the Oswego West Utica Street MGP revealed the presence of coal tar in the shallow subsurface of the southern area of the site. Coal tar contains chemical contaminants including benzene, toluene, ethylbenzene, xylene (BTEX) and polycyclic aromatic hydrocarbons (PAHs). Coal tar was found in the shallow subsurface of the southern area of the site. The site groundwater is also impacted from former MGP operations. BTEX and PAH compounds were also detected offsite in bedrock groundwater, generally south of West Utica St. The impacted groundwater will be remediated under a separate remedial plan that is currently being developed. The area is served by a municipal water supply from a water source unaffected by the site contamination.

The DEC plans excavation and disposal of the top four feet of soil in areas that require solidification. The contaminated soil will be mixed in-place with Portland cement and blast furnace slag using an excavator attachment or auger. The result is a low permeability soil that slows groundwater flow and inhibits the migration of contaminants. The solidification will extend to a depth of 22 feet below the surface.

Monitoring wells, in addition to those already present onsite, will be installed, enabling the observation and collection of coal tar in the groundwater.

According to Oswego City Engineer Jeffrey Hinderliter, the remediation that theyre doing is behind the area of the Car Shop. Theyre going to be opening up the pavement, and theyre going to be excavating the contaminated soil. They bring it up, they mix it with a slurry and put it right back down. The slurry is designed to contain the contaminants. Then theyll restore the surface. Theyve installed monitoring wells, and theyll begin sampling in those monitoring wells to see if the contamination is moving.

A lot of times, Hinderliter continued, these are old petroleum sites, or where there was power generation, there are things of that nature. The concern, because of the Clean Water Acts is always of this getting in groundwater. We dont drink our groundwater. We pull it from the lake, but we are close to the river and the lake. Some of this is ongoing work that the DEC does to find these old sites and to try to stabilize them so that they arent moving offsite. There isnt imminent danger or risk to public health just from them doing this work. Theres not something lingering out there that poses that kind of risk. The biggest thing is that when its in the ground like this you start getting cracks in pavement and the water gets into the soil, then as the water moves through the soil, it picks up these contaminants and brings it offsite. Thats what we want to prevent. There are different ways of doing that. Some places, they just pour a slab over it and make the slab big enough so that surface waters not going to get in there. Other times, like this case, theyll go in, and theyll try to stabilize it in-place. Other times, they cant, and they start removing material. Then, anything thats contaminated, is just moved to a landfill. A lot of it comes down to strategy and cost.

When it comes to contaminated soils, right now theyve done sampling, so theyll pop holes through the pavement, theyll bore, and they sample that soil to see where it is, but until they actually open the pavement up and get working, thats whats going to reveal how far the contamination is. So, part of it is a bit of an unknown. Theyre going to cut the ground open, lay it out, and then remediate it and restore. Thats typically how these projects go.

Although this remediation will be in close proximity to and worked on at the same time as the citys scheduled repaving of West Utica Street between West First and West Fifth streets, Hinderliter expects this project will have no effect on it.

As background, Hinderliter, as Ive said before, a virtual encyclopedia on things like this, recounted some of the plants history.

There were coal bins there, he said. Some of it is just the nature of how things were done then, where oftentimes next to power generation you had a slag pile where all the burnoff is just dumped onsite, or when things are abandoned, tanks are left in the ground. Things like that, the way business was done, its just been left. So, where we wouldnt do these things today, thats how it was done.

Now, Hinderliter said, it falls to the DEC to clean it up.

This is what they regulate, and oftentimes they take on the cost, and they manage it. When theres a contaminated site, it becomes their responsibility to oversee it, to clean it up, and to monitor it. Those monitoring wells, the DEC comes annually and checks those. Its part of their program. As far as National Grids involvement, it may be that they inherited some ownership of it. Those utility companies acquired smaller companies as they grew.

Although these kinds of remediations are intended to prevent contaminants from moving into the groundwater or all the way to the river, Hinderliter doesnt believe thats an imminent threat. But this does serve as an example of a philosophy Hinderliter has expressed since the day he came to Oswego.

We have to be good stewards of our resources, Hinderliter said. As much as people dont like to deal with the State Environmental Quality Review, the SEQR process, thats part of it, trying to look at a project and what could be its future impacts on this site, because presumably its not going away in a year or two. If were building something, we want it to be there for a long time. And so, its doing our best to try to look at what impacts are going to happen, and is there anything we can do now to prevent what we used to do from happening again.

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DEC to remediate chemical contamination between Oswego's West Third and Fourth streets - NNY360