PCBs: Transformer Pad Remediation During Holiday Outageby Patrick Nace, Pentek, Inc.
On-site remediation operations are challenging in a fully active facility. Decontamination activities have to be efficiently completed within the narrow time window allotted by temporary and infrequent outages. Remediation specialists must not only decon facilities without disturbing existing operations, or background cleanliness levels, but they must get out quickly as well, without interrupting resumed plant functioning. An industrial systems plant in Fort Wayne, Indiana, needed to extract deeply-embedded PCB contaminants from a concrete transformer pad. The transformers had been stationed on a mezzanine shelf above the plant floor that comprised approximately 1,000 square feet (90 square meters) of concrete with a 30 linear foot (9 M) perimeter of curbing. PCB dialectic fluids had leaked from the transformers for decades, seeping into the porous strata of the concrete and darkly staining the floor. Testing samples indicated that, before a new protective flooring could be installed, an estimated average removal depth of 1/16-inch (1.6 mm) of contaminated concrete was necessary for elimination of the PCB hazard. CRX Environmental Services, a Pittsburgh-based remediation contractor specializing in PCB removal and lead-based paint abatement, was contracted to scarify the surface with Pentek's dustless decontamination and collection system. The proven dust control inherent in Pentek's scabbling/dust collection process mitigates the need for respiratory protection as well as eliminating special tenting, containment structures, or ventilation schemes to protect personnel, and facility areas. CRX utilized a rental MOOSE robotic scabbler, which removes contaminated concrete to the required depth with pneumatically-driven, tungsten carbide-tipped bits and deposits waste into an integral waste drum. CRX also used Pentek's ancillary manual tools with vacuum attachments: SQUIRREL-III floor scabblers, CORNER-CUTTER needle guns, and ROTO-PEEN Scalers to mechanically abraded the areas inaccessible to the MOOSE, such as the concrete curbing. The ROTO-PEEN Scaler is a shrouded power tool that employs rows of tungsten carbide cutters mounted on a rotary hub to remove hazardous coatings at a nominal rate of 45 square feet per hour. These pneumatic power tools removed coatings and substrate, while all dust and debris was automatically collected by a VAC-PAC Model 24 HEPA vacuum and collection unit--capable of supporting up to ten scabbler over 200 feet away. It was no problem to place the waste collection unit on the plant floor and extend collection hoses to give remediation technicians full access to the work area located on the mezzanine above. Isolated scabbling to depths greater than 1/16-inch was required to deal with "hot-spots" and slab anomalies that were detected during decontamination activities. Results from continuous industrial hygiene monitoring and sampling permitted work without respiratory protection, which enhances productivity and frees workers from the negative health effects of respirator over-usage. The proven durability of the Pentek equipment, which over the years has achieved a 99+ percent availability factor, provided the ability to accomplish the PCB decontamination during one long shift scheduled over the annual Christmas outage. The stainless steel construction of the Pentek system is designed to facilitate deconning following a project (Pentek has never lost a piece of equipment due to latent, post-project contamination). The floor was sampled immediately following the remediation effort to ascertain acceptable residual concentrations of contamination. CRX then coordinated a floor overlay of Silikal methylmethacrylate-based industrial flooring to permanently encapsulate the mezzanine. |
