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R <br /> Secondary Containment for <br /> Aboveground Storage Tanks <br /> Minnesota <br /> Pollution <br /> COIIt�OI Tanks/Aboveground Storage Tanks#4.01 • December 2008 <br /> Agency <br /> econdary containment helps prevent Materials <br /> serious environmental problems The acceptable impermeable materials that <br /> from occurring because of tank must be used for construction of the <br /> releases. While the tank itself is vital to containment area for ASTs installed on <br /> minimize the potential for leaks, secondary November 2, 1998, or later include: <br /> containment is another important safeguard <br /> from potential releases. This fact sheet • compacted clay (if clay is used,it must <br /> outlines the requirements and choices have a minimum of 12 inches <br /> available for secondary containment for compacted clay, be protected with <br /> aboveground storage tanks(ASTs) cover material to prevent drying and <br /> according to Minn. R. ch. 7151. erosion, be designed, inspected, and <br /> certified by a registered professional <br /> engineer, and be tested after <br /> Compatibllity installation to meet a permeability rate <br /> If more than one type of substance is stored to water equal to or less than 1 x 10-' <br /> within a single containment area,the cm/sec) <br /> substances must be compatible with each . a geosynthetic clay liner <br /> other and the containment material. <br /> • concrete <br /> VOlume • a synthetic membrane <br /> For containment areas which are exposed • the outer layer of a double-walled tank <br /> to precipitation,the containment area . fabricated steel <br /> capacity (available space)must be at least <br /> 110 percent of the size of the largest tank • fiberglass <br /> in the containment area. Containment areas with tanks that were <br /> For containment areas which are not �nstalled before November 2, 1998, may be <br /> exposed to precipitation,the containment constructed using any of the impermeable <br /> area capacity must be at least 100 percent materials listed above, or may be <br /> of the size of the largest tank in the constructed of native or amended soils that <br /> containment area. have been tested to meet the following <br /> minimum permeability rates for the <br /> A separate containment area is not required applicable substance type and hydrology. <br /> for double-walled tanks. <br /> Soil testing requirements are explained in <br /> the fact sheet"Permeability Testing for <br /> Secondary Containment Areas." <br /> t-a4-01 <br /> Minnesota Pollution Control Agency • 520 Lafayette Rd. N., St. Paul, MN 55155-4194 • www.pca.state.mn.us <br /> 651-296-6300 • 800-657-3864 • TTY 651-282-5332 or 800-657-3864 • Available in alternative formats <br />