§ 14a.6. Dikes, walls and drainage.
(a) General. The area surrounding a tank or a group of tanks shall be provided with drainage or shall be diked to prevent accidental discharge of liquid from endangering adjoining property or reaching waterways, except that in particular installations these provisions may be waived or altered at the discretion of the fire marshal when the tanks under consideration do not constitute a hazard to adjoining property.
(b) Drainage. If protection of adjoining property or waterways is by means of a natural or manmade drainage system, such systems shall comply with the following:
(1) A slope of not less than 1.0% away from the tank toward the drainage system shall be provided.
(2) The drainage system shall terminate in vacant land or in an impounding basin having a capacity not smaller than that of the largest tank served. This termination area and the route of the drainage system shall be located so that if the flammable or combustible liquids in the drainage system are ignited, the fire will not expose tanks or adjoining property.
(3) The drainage system, including automatic drainage pumps, shall not discharge to adjoining property, natural water courses, public sewers, or public drains, nor discharge in any manner that would constitute a hazard.
(c) Diked areas. If protection of adjoining property or waterways is accomplished by retaining the liquid around the tank by means of a diked area, such diked area shall comply with the following requirements:
(1) Except as set forth in paragraph (2), the diked area shall be designed to contain the volume of liquid that can be released from the largest tank.
(2) For tanks with fixed roofs containing crude petroleum with boilover characteristics, the diked area shall be designed to contain the volume of liquid that can be released from all tanks served by the enclosure.
(3) Walls of a diked area shall be of earth, steel, concrete, or solid masonry designed to be liquid tight and to withstand a full hydrostatic head. Earthen walls 3 feet or more in height shall have a flat section at the top not less than 2 feet wide. The slope of an earthen wall shall be consistent with the angle of repose of the material of which the wall is constructed. Dike walls shall be restricted to a maximum height of 6 feet above interior grade. The use of building walls as part of dike walls is prohibited.
(4) Provision shall be made for draining water from diked areas. Drainage shall have a uniform slope of not less than 1.0% away from tanks toward a sump, drainbox, or other safe means of disposal located at the greatest practicable distance from the tank, and shall be accessible to control under fire conditions. Such drains shall be kept closed except when in use and shall be designed so that they do not permit flammable or combustible liquids to enter natural water courses, sewers, or drains if their presence would constitute a hazard. Pumps or other means used in providing drainage from diked areas shall be manually controlled only.
(5) No loose combustible material, drum, or barrel shall be permitted within the diked area.
(6) In densely populated areas a fence which will enclose the tank or equipment may be required where public access to the tank is not otherwise restricted.
(d) Particular installations. These provisions may be altered in particular installations at the discretion of the fire marshal after consideration of special features such as topographical conditions, nature of occupancy and proximity to buildings, height and character of construction of such buildings, capacity and construction of proposed tanks and character of liquids to be stored, degree of private fire protection to be provided, and facilities of fire departments to cope with flammable or combustible liquid fires.
Source The provisions of this § 13.6 amended June 22, 1984, effective June 18, 1984, 14 Pa.B. 2131; transferred from 37 Pa. Code and renumbered as 34 Pa. Code § 14a.6, February 28, 2014, effective March 1, 2014, 44 Pa.B. 1233. Immediately preceding text appears at serial pages (259909) to (259911).
Cross References This section cited in 34 Pa. Code § 14a.8 (relating to vents); 34 Pa. Code § 14a.111 (relating to storage and handling); 34 Pa. Code § 14a.141 (relating to scope and application); 34 Pa. Code § 14a.151 (relating to scope and application); and 34 Pa. Code § 14a.161 (relating to general provisions).
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