Polyurea Spray Technology for Secondary Containment
Polyurea spray technology is a plural-component, fast-set elastomeric membrane system that provides for a monolithic, impervious layer. Various formulated systems address the numerous requirements related to secondary containment, including adhesion to the various substrates commonly encountered in these containment areas. For containment areas where solid substrates are not present, geo-membranes can be used with an applied layer of a polyurea system incorporating low shrinkage characteristics designed for the area.
The fast set time of the polyurea spray technology allows for a rapid return to service of the area in a variety of ambient conditions, including cold or humid weather. The polyurea systems also remain flexible at low temperatures, thus eliminating cracking issues found in other liquid applied coatings and sheet-good installed membranes.
Many tanks and piping areas may be prone to leakage. However, it has been shown that most leakages found in these areas are actually due to overfilling of the storage tanks, possibly a result of faulty equipment or operator error.
The polyurea spray elastomer technology has been evaluated under the Florida Department of Environmental Quality (DEQ) requirements for secondary containment liner systems. The technology has passed the testing and is classified as an acceptable secondary containment lining material.
Fully aware of the impending environmental regulations, the U.S. military has issued the polyurea technology successfully for lining various fuel storage containment areas. As a matter of fact, this technology currently is being specified by engineering contract firms working with the U.S. Air Force and U.S. Navy. Work includes application at Patrick air Force Base, Cape Cod Canaveral Air Force Station, AUTEC U.S Navy Base and a variety of fuel storage areas for municipal airports.Most of these areas have an existing epoxy paint system applied to the concrete. The epoxy has cracked with the movement of the concrete over time, thus allowing for a breach in the containment area and potential environmental issues. The polyurea technology, as an elastomeric system, bridges those cracks and yields a superior containment lining material.
For existing asphalt, earthen berm or gravel containment areas, the polyurea system is applied on top of a geotextile membrane, as noted previously. The polyurea system bonds to the geotextile membrane, as well as the existing tanks, pipe penetrations and sump areas, and provides for a seamless installation without the use of mechanical fastening, as is required with sheet-good installed material. Many such applications have been successfully completed at major fuel, oil and chemical storage facilities. The polyurea systems used in these cases is specifically formulated to provide for a low cure shrinkage as applied over the unsupported geotextile membrane, Recent work in North America includes projects that are in the 3000,000 to 4000,000 ft2 (28,000 to 42,000 m2) range. These large projects typically are completed within one month using application-trained installation crews.
With the resurgence of oil and gas exploration in the U.S., containment areas for fractionation fluid are required at each drilling site. For this work, a designed containment area is prepared, metal support walls are constructed, and a designed polyurea spray system is applied over geotextile fabrics. The polyurea system bonds to the wall area and the geotextile fabric to provide for a seamless, leak-free area. The storage tanks are then set within the area and piped in the same day as the liner system installation.