Design of proper containment requires the participation of specialists in structural engineering, coatings, ventilation, and exhaust. The following considerations should be
addressed in the development of a containment system:
• The environmental media (air, water, soil) that are vulnerable and the containment methods that will provide the best protection
• Durability
• Compatibility with the selected removal method, and potential for interference with the productive removal of the paint, mill scale, and rust and the application of a new coat of paint
• Ease of construction, disassembly, and moving from one area of the structure to another
• Local climate conditions
• Continued usability of the structure and proximity of nearby structures and people
• Cost-effectiveness
• Compliance with applicable regulations
Materials used to construct containments include rigid panels or flexible materials such as tarpaulins. The selected materials should be fire-retardant, given the sparking hazard, high dust, and high ventilation aspects of the procedure.
The checklist provided in Table 1.16 may be followed in designing an appropriate containment system. Various debris-recovery assessment methods are underdevelopment. Some, such as air monitoring and analysis of soil and water samples to evaluate whether
TABLE 1.16 Containment Design Checklist
1. Review drawings and specifications for project familiarity.
2. Investigate OSHA and EPA regulations affecting worker protection and control over emissions.
3. Determine method of surface preparation to be employed.
4. Examine the structure to be prepared:
• Confirm that the selected method of preparation is suitable.
• Determine if any coats of paint will be applied in containment.
• Assess the load-bearing capacity of the structure to support containment.
• Examine the structure for attachment points for the containment.
• Divide large structures into logical containment units according to size and configuration. Consider the air movement requirements and the need to have a large enough area for productive surface preparation and painting.
• Determine if a working platform should be used on elevated projects. Determine how far ground covers should extend beneath or around the removal operation.
• When working over water, determine if a barge is going to be used for spent abrasive collection or staging, and assess the need for water booms to minimize problems due to inadvertent spills. Determine the need for U. S. Coast Guard approval and navigation restrictions.
• Determine methods for conveying the debris for recycling or disposal.
5. Determine project-specific ventilation requirements.
• Consult Industrial Ventilation: A Manual of Recommended Practice (Committee on Industrial Ventilation, American Conference of Government Industrial Hygienists, Cincinnati; 20th ed., 1988) for engineering guidance.
• Select the air velocity (air speed) throughout the work area and exhaust volume required.
• Determine the necessary transport velocity through the exhaust ductwork required to avoid dropout of debris.
• Lay out the ductwork as short as practical with as few bends as possible. Do not use bends with a centerline radius less than 2 times the duct diameter. Include the use of exhaust hoods or plenums within containment.
• Select the air-cleaning device (dust collector) on the basis of the volume of air and dust loading of the airstream (air-to-cloth ratio).
• Select the fan that will provide an adequate volume of air, and that is able to overcome the resistance throughout the system.
• Provide adequate makeup air (supply air), properly distributed to provide a uniform airflow. Include properly balanced forced air if required.
• Confirm that all of the above will provide ample airflow throughout the work area. If not, consider the use of localized ventilation and exhaust.
6. Obtain and review equipment manufacturers’ technical information.
7. Complete the design package. Utilize the expertise of structural and mechanical engineers,
industrial hygienists, coatings specialists, and equipment specialists.
Source: From K. A. Trimbler, Industrial Lead Paint Removal Handbook, 2d ed., Steel Structures Painting
Council/KTA-Tator, Inc., Pittsburgh, 1993, with permission.
lead content has increased as a result of paint removal activities, have been codified in regulations.
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A method for calculating debris recovery that has been used by the South Carolina Department of Transportation is found in the Struchual Steel Painting Council (SSPC) Guide 61, Guide for Containing Debris Generated during Paint Removal Operations (SSPC 92-07, March 1992). The following equation is used in the SSPC guideline for estimating debris recovery:
where RE = efficiency of recovery
Wd = dry weight of abrasive and paint debris collected
Wa = dry weight of abrasive used
Wp = calculated weight of paint to be removed
This estimation procedure has the limitation of not incorporating the weight of the various release media (air, soil, water), which influence the effectiveness of a containment. A 1 percent debris loss into the soil is not as significant as a 1 percent debris loss into the air. Care must be taken when using this method to measure only the abrasive and paint from the project and not to measure soil that may have come into contact with the debris.
The project designer should incorporate an environmental monitoring plan to evaluate the effectiveness of the containment methods. Reporting and record keeping within the plan should include the following data:
• Name and location of the site, along with a site plot plan
• Identification of the individual or company that is conducting the monitoring
• Name and qualifications of the analytical laboratory used
• Criteria and rationale for selecting monitoring and sampling sites and duration of sampling
• Descriptions of sampling and monitoring methods
• Quality assurance and quality control plans
• Examples of reporting forms
• Acceptance criteria
• Reporting procedures and corrective actions if acceptance criteria are not met
