This section was developed using information and original text from the Zebra Mussel (Dreissena polymorpha) Control Handbook for Facility Operators.
Specialized coatings can be effective in controlling zebra mussels in raw water systems.
Antifouling coatings leach a toxin, typically cuprous oxide, into the water to repel fouling organisms, such as the zebra mussel. These products are effective for approximately 2 to 5 years. Before application carefully examine the data provided by the vendor for effectiveness, long-term success, and environmental soundness. Follow up this information with a call to the local regulatory agency to verify use of the product and any possible usage constraints.
Foul-release coatings present a slippery surface that minimizes the adhesion of the zebra mussel. The most commonly used and highly successful of these is a nontoxic silicone-based paint. The surface created inhibits the ability of byssal thread attachment (Leitch 1993). The silicone-based coating requires several layers to make it effective, and therefore it can be quite costly, averaging $80 - $100 per square meter (Claudi and Mackie 1994). Effectiveness lasts up to 5 years at which time recoating may become necessary. These products are considered to be more environmentally sound because they do not leach toxins. However, they are subject to abrasion, and therefore their use should be limited to areas that are not susceptible to damage caused by ice or debris.
Thermal-spray coatings are metallic coatings such as zinc, copper, and brass. Thermal-sprayed coatings are applied by melting a wire feedstock and propelling the molten droplets in a stream of compressed air on the surface to be treated. These coatings repel zebra mussels through the slow dissolution of metal ions into the water. Zinc thermal spray also provides excellent corrosion resistance on steel surfaces. Copper and brass should never be applied directly to steel because the steel will corrode. Thermal spray coatings should not be used on nonferrous metal substrates. With proper surface preparation they may be used on concrete. Thermal spray coatings are potentially the most durable and lasting zebra-mussel repellent coatings.
The use of coatings as a control measure should be preceded by a complete understanding of recognized or predictable impacts on the operation of the facility. Other control options should be considered as appropriate. HQUSACE (1995) recommended the two coating systems described below for the control of zebra mussels. Coating system A is for use on mild steel or concrete and can be expected to provide effective protection for 10 or more years. Coating system B is for use on mild steel and on some previously painted surfaces. System B should provide approximately 3 years protection.
Coating System A: This coating system consists of a zinc thermal spray coating system number 3-Z, described in CWGS-05036, Metallizing Hydraulic Structures (HQUSACE 1993a). This specification contains all of the necessary guidance including surface preparation, coating application, and safety guidance. The metallized coating should not be top-coated or sealed. The system may only be applied to blast-cleaned surfaces and is not appropriate for application over existing coatings.
Coating System B: This coating system is comprised of a base anticorrosive system and an antifouling topcoat. Coating system number 5-E-Z described in CWGS-09940 Painting: Hydraulic Structures and Appurtenant Works (HQSACE 1993c), comprises the anticorrosive portion of the system. Military Specification MIL-P-15931F, Paint, Antifouling, Vinyl, Type I, Class 2 (HQUSACE 1993b), is applied over the base anticorrosive system. MIL-P-15931 should be spray applied to a dry film thickness between 3 and 5 mils. Surface preparation, coating application, and safety guidance for system 5-E-Z are detailed in CWGS-09940. The safety guidance in CWGS-09940 is also appropriate for the application of MIL-P-15931.
MIL-P-15931 may also be used over some existing coatings, including Systems 3, 3-A-Z, 4, and 5-A-Z, described in CWGS-09940, ”Painting: Hydraulic Structures and Appurtenant Works” (HQSACE 1993c), provided the receiving surface has been cleaned and is in good condition. Existing coating systems to be top-coated with MIL-P-15931, “Paint, Antifouling, Vinyl, Type I, or Class 2” (HQUSACE 1993b) should be cleaned using high-pressure water at 10,350 kPa. Prior to top-coating, the cleaned surface should be dry and free of visible deposits that may interfere with inter-coat adhesion.
For additional information on conducting environmental assessments for zebra mussel control, see Tippett et al. (1993). For additional information on the use of coatings to prevent zebra mussel fouling, contact The Paint Technology Center, U.S. Army Construction Engineering Research Laboratories (CERL), 1-800-USACERL, extension 6769 or 7237. The CERL staff can provide additional information on the use of coatings to prevent zebra mussel fouling.
Management and Control Contents
Management and Control Options
Proactive Control Methods