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� <br /> Permeability rates to water for secondary <br /> containment areas made of native or amended soils re-November 2, 2008,tanks onl <br /> Substance Classification If ground water or bedrock is If ground water or bedrock is <br /> < 10 feet from grade or AST is within > 10 feet from grade or AST is within <br /> 100 feet of Class 2 water 100 feet of Class 2 water <br /> Type A Minimum of three feet of soil at Minimum of three feet of soil at <br /> 1 x 10-5 cm/sec 1 x 10�cm/sec <br /> Type B I Minimum of three feet of soil at Minimum of three feet of soil at <br /> ' 1 x 10�cm/sec 1 x 10-3 cm/sec <br /> Type C I Minimum of three feet of soil at No minimum permeability standard <br /> 1 x 10-3 cm/sec <br /> Type A substances include gasoline, aviation gas, Temp01'aly ta11kS <br /> naphtha, denatured ethanol,hazardous materials, and <br /> mixtures or blends of these with Types B and C Temporary tanks are ASTs located at a facility for more <br /> substances. (Antifreeze is considered a Type A than 30 days, but less than one year. Secondary <br /> substance.) containment areas for temporary tanks must meet the <br /> volume requirements described above, and be <br /> Type B substances include crude oil, diesel, kerosene,jet constructed either of the impermeable materials listed <br /> fuel, fuel oil types one through four, waste oils, and above or meet the applicable permeabiliry rate from the <br /> mixtures or blends of these with Type C substances. table above. <br /> (Virgin lube oil is considered a Type B substance.) <br /> Drainage <br /> Type C substances include asphalt cement, roofing flux, precipitation that collects within the secondary <br /> fuel oil types 5 and 6, and other regulated substances containment area must be discharged in compliance with <br /> which are not petroleum-based and not hazardous all state and federal regulations <br /> materials. <br /> Release detection design Containment evaluation <br /> For ASTs installed on November 2, 1998, or later, and Owners and operators of tanks must retain, for the life of <br /> for ASTs installed before that date which are lifted or the tank system,the following written records of <br /> moved after that date, the area of secondary containment sampling and testing used to evaluate permeability of <br /> which is directly under the tank must be designed to soil containment areas: <br /> allow for visual detection of a release of a substance . classification of soils used in containment area <br /> through the tank floor. construction <br /> Release detection designs that can be used include: • soil descriptions and logs of each sample location <br /> • tank is elevated • a table of individual permeability tests <br /> • continuous concrete slab under the tank( in the case • Permeability of the soil expressed as cm/sec for each <br /> of a Type A substance, slab must be treated with sample location and for each containment area <br /> material that is impermeable to the substance) <br /> • fiberglass or steel pad under the tank Need more information? <br /> • synthetic membrane under the tank Visit the AST Program at <br /> www.pca.state.mn.us/cleanup/ast.html. The site has <br /> • double-walled tank(shop fabricated) forms, fact sheets, and other information about ASTs <br /> • double bottom tank(field erected) and AST requirements. <br /> You can also call the MPCA at 651-296-6300 or <br /> 1-800-657-3864. <br /> Secondary Containment for Aboveground Storage Tanks • t-a4-01 • December 2008 � MEn+tiesaw Po��uiton <br /> �.— Controlllger►cy <br /> Page 2 <br />