National Grid has begun a supervised voluntary cleanup of a former manufactured gas plant site on a .75-acre property that it owns at 10 King St.
The cleanup will be supervised by the state Department of Environmental Conservation.
The site is located in Ogdensburgs marina district, for which city officials have renewed high hopes for development.
That makes that land viable for development, a pleased City Manager John M. Pinkerton said Thursday, continued development.
The grassy site is owned by St. Lawrence Gas and is zoned for commercial use. The gas manufacturing plant operated from 1854 to 1930. Its buildings were demolished in the 1930s after the plant was decommissioned.
According to the DEC, the cleanup schedule will include:
■ Contaminated surface and subsurface soils on the site will be excavated and removed for disposal at a permitted facility.
■ The excavation will extend to bedrock, removal of contaminated water and soil containing greater than 500 parts per million total polycyclic aromatic hydrocarbons.
■ Visible purifier wastes and soils containing greater than 27 ppm free cyanide and/or 40 ppm total cyanide identified on the adjacent off-site parcels to the southeast will be excavated and disposed off-site. Soil and fill material overlying the contaminated soil that does not exceed the removal criteria will be excavated, stockpiled onsite and evaluated for use in backfilling the deeper excavations.
■ Enhanced natural attenuation of contaminated groundwater by the addition of oxygen. This will be accomplished by blending oxygen-enhancing amendments into the backfill of the on-site excavation area.
■ Installation of bedrock recovery wells and periodic measurement and removal of liquid.
■ A site cover will be installed to allow for restricted-residential use of the site. The soil cover will be placed over a demarcation layer.
A deed restriction will be implemented to limit the use and development of site property to restricted residential use, commercial and industrial uses. A site management plan will also be developed.
Use of groundwater as a source of drinking water or industrial supply will be restricted without water quality treatment. National Grid will also be required to prepare and submit to DEC a periodic certification of institutional and engineering controls.
Once the cleanup is complete, National Grid will prepare a final engineering report for DECs approval. Once it the report is approved, DEC will allow for the redevelopment of the site.