Return to Bulletin Contents.| Waterways Experiment Station | Structures Laboratory |
Volatile organic compound (VOC) emissions are known to result in the formation of ground-level ozone that may impact human health and plant life. On June 25, 1996, the U.S. Environmental Protection Agency (EPA) proposed a standard intended to govern the VOC content of architectural and industrial maintenance coatings sold in the United States. The regulation would reduce annual VOC emissions by 20 percent from the 1990 value.
The proposed rule describes 55 categories of architectural coatings and specifies the maximum allowable VOC for each. This rule would be applicable to the manufacture and import of coatings for sale in the United States effective April 1, 1997.
There are currently several states that already regulate the VOC-content of architectural coatings, most notably California. A national rule issued by the EPA would establish a minimum standard for all states, but states would retain the right to promulgate more stringent rules. In all probability, states with existing rules will exercise this right. California probably will not adopt the less stringent levels of the proposed national rule.
Civil Works Guide Specification CWGS-09940, "Painting: Hydraulic Structures" (December 1995), covers the requirements for painting hydraulic structures and appurtenant items. The full range of coatings specified in CWGS-09940 are described by just nine of the EPA's fifty-five categories. Table 1 lists these nine categories as well as some additional coating categories potentially of interest in Civil Works painting. Most of the coatings specified in CWGS-09940 may be categorized as industrial maintenance, metallic-pigmented, or impacted-immersion. Of lesser importance or lower use are coatings covered by the EPA categories for high-temperature, flat, floor, and nonflat coatings as well as primers and pretreatment wash primers.
Table 2 lists the coatings found in CWGS-09940 and their VOC contents and summarizes the potential options for complying with the proposed rule.
The Paint Technology Center of the U.S. Army Construction Engineering Laboratories (CERL) has been proactively researching low VOC coating technologies for many years. The goal has always been to be good environmental stewards while maximizing coating performance. Of longstanding concern has been the potential ban of vinyl coatings (V-766, V-102, V-103, V-106, and VZ-108) that the Corps of Engineers uses for protecting major components of hydraulic structures exposed to freshwater immersion. These coatings have very high VOC levels and were always assumed to be vulnerable to regulatory impact. Extensive research efforts at CERL in the early 1980's were unsuccessful at reformulating the vinyls. Subsequent work has focused on the identification of a suitable substitute technology. These efforts, while nominally successful, have yet to identify an appropriate technology to replace the vinyls.
The author had the fortunate opportunity to participate in a prerule-making regulatory negotiation between impacted sectors of the architectural coatings industry and the EPA. As a result, the EPA was able to establish the need for a separate category for impacted-immersion coatings. This need was supported by research conducted by CERL and presented to the EPA. The proposed rule would allow the continued use of vinyls for the most severe applications where other coating technologies fail, in other words impacted-immersion. Users of CWGS-09940 would need to limit the use of vinyls to this type of end use, and alternate systems such as systems 6-A-Z and 21-A-Z would need to be specified for nonimpact immersion. Users in states with existing or proposed state VOC regulations should note that the impacted-immersion category may not be a part of their state rule, and to the extent that this is true, Corps vinyls will probably not be allowed in those states.
Steel Structures Painting Council (SSPC) Paint 20 (1991), Zinc-Rich Primers (Type I - Inorganic and Type II - Organic), describes a range of commercially available coatings but does not limit VOC. Type I coatings, specified in CWGS-09940 for use on steel subject to elevated temperatures, typically have VOC contents less than the proposed EPA requirement of 500 g/L for metallic-pigmented coatings. Type II coatings, used by the Corps for painting over galvanizing, usually but not always, have VOC's less than 500 g/L. The SSPC is in the process of updating their specifications to include VOC limits. This action should resolve any concern that the Corps could be specifying noncompliant coatings when SSPC Paint 20 is called for.
Suitable low-VOC latex FED SPEC and General Services Administration (GSA) commercial item descriptions exist to replace the current generation of interior alkyds (TT-P-30, TT-E-505, TT-E-506, TT-E-508, and TT-E-509) specified in CWGS-09940 for use on masonry and wood substrates. The performance attributes for latex gloss and alkyd enamels are similar. While alkyds offer certain advantages such as excellent block resistance, latex coatings exhibit advantages of their own, such as superior flexibility.
Commercial item description A-A-50542 describes high-performance floor coatings for use on concrete. The VOC limit of 420 g/L established by the specification is above the 400-g/L limit proposed by the EPA. It is highly likely that GSA will act to lower the specified VOC content to the regulated limit. Another alternative for the Corps would be to use a lesser performing coating such as TT-E-2784, an acrylic enamel, to meet the EPA limit.
Other actions unrelated to the pending VOC requirements include the elimination of SSPC Paint 27 (1991), Basic Zinc Chromate-Vinyl Butyral Wash Primer, and the elimination or augmentation of Paint Systems 21-A-Z and 21-B-Z. The wash primer contains a hexavalent chromium compound with associated health and environmental risks. The Paint Technology Center is in the process of evaluating alternates to SSPC Paint 27 for use on nonferrous metal substrates. System 21-A-Z consists of E-303, zinc-rich epoxy primer, and MIL-P-24441 epoxy polyamide topcoat. A commercial item description for a similar system is under development. This effort is in keeping with the requirements of the revised Federal Acquisition Regulation to buy commercial products and to eliminate or reduce the use of MIL SPECS.
Regulated categories of paints other than those listed in CWGS-09940 may also have some applications in Civil Works projects. Antifouling coatings may be used to reduce the impact of zebra mussels on Corps structures. Research underway at CERL seeks to identify the most appropriate coatings for use by the Corps. Concrete-curing and form-release compounds are used in the placement of concrete. Their use is described elsewhere in Corps guidance. Concrete protective coatings may be used on some local projects to reduce water and chloride penetration that may cause degradation of the concrete. Fire-retardant coatings are used to retard ignition and flame spread or to delay structural weakening of steel and may find occasional use on Corps projects.
The CERL Paint Technology Center is working with CECW-EE to update CWGS-09940 to be compliant with the EPA's proposed rule. For additional information, contact Tim Race at (217) 373-6769.
Comments