The Remediation Services division of Waste Management International (WMI), was contracted by a major Finnish industrial customer to remove PCBs from a facility in Vaasa, Finland. The project called for the dustless decontamination of 165,000 square feet of concrete floors in a former transformer manufacturing plant. Criteria to release the facility for reuse required complete removal -- cleaning beyond detectable limits -- and collection of the contaminated concrete within a two month period. The facility was similar to a hugh parking garage: long, oblong chambers that were minimally lit and interspersed with rows of large columns. Since adjoining property was part of a large industrial park, exacting environmental control was demanded during remediation efforts.

WMI's early attempts to remove the contamination by means of power washing techniques were unsuccessful; it became apparent to the owners that this method actually increased PCB concentration levels and the extent of contaminated concrete. Actual physical removal by scarifying the concrete to the depth of clean, uncontaminated surface was proposed as a direct, long-term remedy to ensure the total eradication of the hazard. It was decided to use Pentek's scabbling system to their overseas partner. Pentek's mechanical scabbling robot, the MooseŽ, removes and captures contaminated concrete to the required depth with pneumatically-driven tungsten carbide-tipped bits. The unit's on-board waste collection unit packages the contaminated dust and debris under strict vacuum control directly into an integral waste drum. This mature remedial technology minimizes hazardous wastes: no water, abrasives or chemicals are added to the waste stream, so all that is collected are the removed contaminants.

WMI decided to evaluate two remediation technologies; a traditional shot blasting machine and the Moose were both brought into the Vaasa facility for on-site demonstrations. "Although the shot blast machine initially showed potential in production, it could not go the distance with the depth criteria we required," said Project Manager, Bruce Gordon. "Blasting was unable to do more than take off the top 1mm of concrete due to dense aggregate layers, which left PCB-contaminated concrete still within the floor." The blasting system was also plagued with maintenance problems caused by the normal wearing of internal components.

"Pentek's Moose floor scabblers, on the other hand, proved to be real work horses," Gordon continued. "They are excellent tools for the aggressive decontamination of concrete, while controlling any cross-contamination hazard." The scabblers also produced a more uniformly keyed surface texture for subsequent industrial floor overlays to better adhere.

As the operators guided the scabbling robots, "plowing" the contaminated concrete and collecting abraded dust and debris, other crewmembers employed manually-guided scabblers for removal work within the trenches, along edges and corners, and around column obstructions. Using this focused, integrated approach, the combined crews moved through the pillar-lined vaults, methodically extracting all contamination.

The units surpassed expectations and directly enabled completion of the project a full three weeks ahead of schedule. "The dependability of the equipment was proven when the twin machines operated continuously 24 hours per day, seven days per week, other than pausing briefly for normal maintenance procedures -- only two hours of forced downtime, altogether," stated John Sotiriou, Pentek's project manager.

The Vaasa facility passed testing evaluations and was released to become a large produce and consumer product