4.10.1105    SECONDARY CONTAINMENT AT PERMANENT STORAGE FACILITIES

(1)  Any individual primary containment capable of storing more than 500 U.S. gallons or 4,500 pounds and in-service for more than 14 consecutive days and its associated appurtenances must be placed within secondary containment that meets the following requirements:

(a)  secondary containment not protected from precipitation shall contain at least 125% of the volume of the largest primary containment within the secondary containment plus the displacement of all other primary containment, appurtenances, and other items which cause displacement within the secondary containment.

(b)  secondary containment located indoors or under a roof to prevent accumulation of precipitation shall contain at least 110% of the volume of the largest primary containment plus the displacement of all other primary containment, appurtenances, and other items which cause displacement within the secondary containment.

(c)  the walls and floors of secondary containment shall be constructed of steel, poured reinforced concrete, precast concrete modules, solid masonry, synthetic liners, or other materials that will provide secondary containment. Floors and walls constructed of clay, natural soil, natural soil clay mixtures or clay bentonite mixtures are prohibited. Materials used in the secondary containment shall be chemically compatible with the pesticides being stored. A written conformation of compatibility from the manufacturer and kept on file at the PSF or at the nearest office from which the PSF is administered is recommended.

(d)  walls shall withstand a full hydrostatic head of any spill, and shall be sealed to prevent leakage.

(e)  piping through the outside walls of a secondary containment is prohibited.

(f)  the secondary containment floor shall slope to a liquid tight collection point or sump that allows spilled or deposited material to be easily removed. Any pump used for recovering materials from the secondary containment shall be manually activated.

(g)  synthetic liners shall be installed under the supervision of a qualified representative of the manufacturer, a contractor certified by the manufacturer, or a certified engineer. All seams shall be tested and repaired, if necessary, in accordance with the manufacturer's recommendation. A record regarding installation date, life expectancy and chemical compatibility must be kept.

(h)  a prefabricated secondary containment shall be composed of a rigid prefabricated basin having a base and walls constructed of steel or synthetic materials which are resistant to corrosion, puncture and cracking.

(i)  the prefabricated secondary containment shall withstand all foreseeable loading conditions, including the primary containment load and a full hydrostatic head of any spill. Multiple basins shall be connected in a manner which assures an adequate transfer of discharge between basins.

(j)  discharge outlets, valves or gravity drains shall comply with ARM 4.10.1103(5)  .

(k)  secondary containment for pesticides must be separate from containment for fertilizer, but they may have a common wall or partition.

History: Sec. 80-8-105, MCA; IMP, Sec. 80-8-105, MCA; NEW, 1999 MAR p. 54, Eff. 1/15/99.