Title: Evaluation of Transite Wetting Effectiveness During Demolition
U.S. Gaseous Diffusion Plants external walls, such as the Oak Ridge K-25 facility and sister facilities at Piketon, OH, and Paducah, KY are paneled with transite (a cement composite, containing up to 50% asbestos fibers). The current approved method for transite removal is to handle each piece of paneling separately; avoiding any site breakage in order to prevent possible airborne contamination or potential inhalation of asbestos fibers.
The EPA, DOD and DOE at Hanford have been using an alternate method for potentially friable asbestos containing material (ACM) removal from buildings (1, 2, 3). This alternate method includes using water and/or water with a wetting or foaming agent to first soak the panels (to minimize friability) and then subsequently to use heavy demolition equipment to break lose and remove the material from the building.
The work performed to date on this alternative approach has not been evaluated for optimization of the process and the data gathered has not been in a closed system, so absolute values on the emission or release of friable asbestos have not been determined. The studies do show that ambient air monitoring in the use of this alternate technique appears to show airborne asbestos levels to be below regulatory limits.
Materials and Chemistry Laboratory, Inc. (MCL) was contracted to further evaluate this alternative approach for the remediation of transite containing buildings. This study included a comprehensive literature review of the alternative approach, evaluation of water/wetting agents, construction of a test enclosure, and testing the alternative technique in a “closed system”.
This study required the selection of wetting agent and appropriate concentrations for use which included an evaluation of the penetration of the water, wetting agent and water plus wetting agent on pieces of K-25 transite. The effect of exposure time on penetration was also demonstrated. The results of these tests were used to develop the testing methodology for the “closes system” test.
The “closed system” testing study allowed for the break up “demolition” of K-25 transite sections while monitoring the air and water samples in a totally enclosed atmosphere. During these runs air samples were collected and monitored for asbestos by Phase Contrast Microscopy (PCM), NIOSH-7400 and/or Transmission Electron Microscopy (TEM), NIOSH-7402. Water samples were also collected and analyzed for asbestos and gross alpha/beta.
The wetting/penetration test indicated that water or amended water does not penetrate asbestos-cement siding such as transite. Even with a wetting duration of 5 hours there was no evidence of significant penetration within the bulk transite material. The air sampling/fiber counting results during each closed system test showed no decrease in fiber loading with water wetting or amended water wetting. There was no trending suggesting that water or amended water performed better at controlling friable asbestos.