Who knew if they would ever go away? When one of the first sets of onsite groundwater-treatment wells was installed in 1997 to help treat the remains of a fuel oil/solvent spill that had occurred 20 years earlier, only modeling projections could estimate when the cleanup would be complete. Even then, only designated regulatory agencies could approve when the wells and the associated cleanup system could be decommissioned.
But this summer, the cleanup area adjacent to Building 521, located at Brookhaven Avenue and Sixth Street, became BNL’s first groundwater area of concern (AOC) to be approved for decommissioning by the U.S. Environmental Protection Agency and the New York State Department of Environmental Conservation (NYSDEC) because that area is now deemed cleaned up, as groundwater contaminant concentrations have dropped to below regulatory standards. The location known as Operable Unit (OU) IV, AOC Five consisted of a network of 71 treatment wells and 22 monitoring wells. As part of the system decommissioning, all 71 treatment wells were abandoned and seven of the monitoring wells were abandoned. The remaining monitoring wells will be used to continue to monitor groundwater in this area.
|From left, Project Manager Vinnie Racaniello, Group Manager Bob Howe, and Geologist Lauren Schnitzer inspect the remainder of one of the now defunct air sparging wells|
During the cleanup years, the tall orange monitoring wells had enabled groundwater scientists to measure groundwater quality. The smaller white wells marked the workhorse of the cleanup system, known as “air sparging and soil vapor extraction remediation.” In this process, the white air-sparging wells forced pressurized air below the water table to bubble up the contaminants, which were then “vacuumed up” by the vapor extraction wells and sent through carbon vessels housed in Building 521. The contaminants adhered to the carbon, which was later sent to a licensed disposal facility offsite.
Recently, most of these wells were abandoned by filling their screened segments with sand and then grouting their remainders with a cement bentonite mixture. The pits that remain from the cut wells are being backfilled and the soil re-graded and seeded. As a final act of closure, the surrounding fence will come down and the area of approximately five acres will remain commercial/industrial and part of the core “campus” area.
|Project Engineer, Noel Blackburn,
earlier in December inspects one of the units that make up an air sparging
and soil vapor extraction remediation system that is being decommissioned
near Building 521.
|Once a loud, noise-filled operation with large carbon vessels sucking up solvents, Building 521 is now a silent shell of its former self. Project engineer Noel Blackburn reviews old blueprints.|