Standard Interpretations - Table of Contents|
| Standard Number:||1910.1025; 1926.62|
June 18, 1991
Lead-based paint removal can result in significant lead exposures to workers. The attached article from Maintenance Technology addresses a particular engineering control designed to remove lead-based paint from both steel and concrete surfaces. This control method has been used for lead paint removal from industrial buildings, storage tanks, and ship hulls, as well as building components in public housing units.
The equipment discussed in this article could substantially reduce worker exposure to airborne dust, in particular, lead. It consists of a handheld needle gun unit connected to a vacuum unit with HEPA filter that empties directly into a waste container.
For further information please contact Ira Wainless on FTS 523-7056.
Dustless Needle Guns
Remove Lead Paint Safely
Equipment of the type used on the lead paint removal project consists of handheld needle gun unit connected to vacuum unit with HEPA filter that empties directly into the waste container.Open-blast cleaning of storage tanks before recoating poses a pollution hazard. Silica dust or other abrasive debris along with pulverized coatings, often with a high lead content, can be scattered widely, opening the tank owner and the contractor to various safety and environmental pollution charges.
Risk of environmental violations can be minimized with surface preparation equipment that captures dust and debris at the cutting edge and transports it by vacuum directly into approved waste containers, minimizing pollution of the surroundings and the need for operator respiratory protection.
The equipment's mode of operation minimizes levels of detectable airborne dust during lead paint removal and waste handling operations. This capability can effectively eliminate the need for environmental tenting or containment, and respiratory protection for operators. Therefore, other activities (normal traffic, industrial processes, or painting) can proceed in parallel with lead paint removal.
Project scope. Surface preparation equipment manufactured by Pentek, Inc., Coraopolis, PA, was used recently by Napit Contracting, Inc., to remove lead-based coating from two 500,000 gal jet fuel storage tanks at Chase Field Naval Air Station, Beesville, TX. The tanks were 64 ft in diameter and 25 ft tall and had a total surface area of 17,000 sq ft, including walls, roofs, stairways, and other appurtenances.
The old coating system was composed of red lead primer and white intermediate and top coats containing lead. The contract required stringent control of airborne dust and environmental contamination. The contractor was required to deposit all lead- contaminated wastes into approved 55 gal drums. The government assumed responsibility for disposal of the hazardous waste.
Pentek asked the government to consider surface preparation techniques other than abrasive blasting to near-white metal in accordance with SSPC-SP10. An amendment to the bid invitation allowed power tool cleaning followed by a brush-off blast.
The contractor used Vac-Pac/Corner-Cutter equipment because it effectively stops the escape of airborne paint and debris. The Corner-Cutter consists of multiple reciprocating needles completely enclosed within an adjustable shroud. Disposable shroud adapters are machined to conform to various geometric contours, allowing the unit to remove paint from flat steel and concrete surfaces, outside edges, inside corners, and pipes.
The Vac-Pac module is a self-cleaning, high-efficiency particulate air (HEPA) vacuum filtration system with a self- drumming feature. The unit creates high, uninterrupted vacuum flows. Each vacuum/drumming unit can support the simultaneous operation of up to three needle gun units.
The entire job was performed without tenting or other containment structures. Respiratory protection for equipment operators is not normally required because of the cleanliness of the equipment. However, half-face respirators were worn by the four-man crew as a precautionary measure, as specified in the project health and safety plan.
Once the lead paint was removed, brush-off blasting began. Blasted surfaces were primed daily to prevent flash rusting. The new coating system consisted of epoxy-polyamide zinc-rich primer, epoxy-polyamide white intermediate coat, and polyurethane topcoat.
The entire project was completed in 5 weeks, including mobilization at the site; the contract had allowed 4 months to complete the work.
Equipment. Mobilization was eased significantly by the compactness of the equipment used and by the fact that containment, auxiliary dust collectors, and special waste handling equipment were not required. The entire inventory of lead paint removal equipment consisted of one Vac-Pac Model 9, four Corner-Cutters, an air compressor and waste drums.
The job was conducted without the need to replace any filters in the vacuum unit, and the high-alloy needles supplied with the cutter survived the entire operation (equivalent to approximately 150 hours of continuous operation each).
As described by the Navy's chief field inspector, operations proceeded smoothly and "uneventfully".
Environmental impact. The air was monitored continuously during the project to ensure compliance with Occupational Safety and Health Administration standards and contract requirements. Measured airborne emissions remained well below 30 ug/m3 at all times.
It is estimated that solid material containment efficiency was above 99 percent. this figure is based on the Navy's estimate that "half a coffee cup" of small paint chips were observed on the ground immediately adjacent to the tanks at the end of each shift. each night the contractor was required to vacuum these up using the vacuum/drummer unit. These observations are consistent with Pentek's experience on other jobs.
Waste management. Paint chips, dust, and debris were continuously transported by the vacuum system and deposited into waste containers in a single-step operation. Although the Vac- Pac is designed to accommodate standard Department of Transportation-approved 55 gal drums, Napit used special 21 gal drums to eliminate the need for special handling equipment at the site (a full 55 gal drum weighs in excess of 500 lbs, whereas a 21 gal drum weighs approximately 200 lb and can be easily handled by two people(. Two 21 gal waste drums can be placed directly into a single 55 gal overpack for disposal.
The total quantity of lead-contaminated paint chips generated on the job was equivalent to two 55 gal drums. The Navy's pre-contract analysis estimated that conventional sand- blasting techniques would have generated between 200 and 300 barrels of hazardous waste.
An environmental Protection Agency toxicity test on the point chips confirmed that they were hazardous on the basis of leachable lead content (34 ppm actual vs. 5 ppm limits).
Residual sand from brush-off blasting operations resulted in three 55 gal drums of waste that was not considered hazardous.
Economics. Total cost to the government for surface preparation and waste handling activities was $2.95/sq ft, 50 percent of the total job cost of $100,000.
Total manpower charged by the four-man crew responsible for cutter operations was 672 hours for the entire 17,000 sq ft project, including the nonproductive time that inevitably accumulates during the day. Therefore, average productivity is estimated at 25 sq ft/hr.
Logistics and mobilizations are greatly simplified by the compactness of the equipment and its ability to accommodate multiple operators at distances of up to 100 ft from a single vacuum/drumming area.
Containment of greater than 99 percent of all hazardous materials is both feasible and cost-effective.
TOXICITY TEST RESULTS
Information supplied by Sheldon Lefkowitz, president, Pentek, Inc. Coraopolis, PA.
February 1991 Maintenance Technology Magazine
Standard Interpretations - Table of Contents|