(i) double-walled piping;

(ii) a synthetic trench liner; or

(iii) another method that meets the requirements of this section and is designed and constructed in accordance with a consensus code, standard or practice developed by a nationally recognized association or independent testing laboratory which meets the standards of this section.

(i) be designed and constructed with a permeability rate to the substance stored of 1 × 10^-6 cm/sec or less;

(ii) be designed, installed, and operated to prevent any migration of hazardous substances out of the system to the environment at any time during the use of the piping;

(iii) allow for detection and collection of releases, spills and accumulated liquids until the collected material is removed;

(iv) be constructed of, or lined with materials that are compatible with the hazardous substances to be placed in the piping, and have sufficient strength and thickness to prevent failure due to physical contact with the materials to which it is exposed, climatic conditions, and the stress of daily operation;

(v) be placed on a suitable foundation which prevents failure due to settlement, compression or uplift;

(vi) be sloped or otherwise designed and operated to drain and remove liquids resulting from leaks, spills and precipitation. Spilled or leaked substances must be removed from the secondary containment system within 24 hours. If the owner or operator can demonstrate that removal of the spilled or leaked substance, or accumulated precipitation cannot be accomplished within 24 hours, then it must be removed in as timely a manner as possible to prevent harm to human health and the environment; and

(vii) be provided with a leak detection system that is designed and operated so that it will either detect the failure of the primary containment structure or the presence of any spill, leak, or release of hazardous substance or accumulated liquid in the secondary containment system within two hours. If the owner or operator can demonstrate that existing detection technologies or site conditions will not allow detection of a spill, leak or release within two hours, then the leak detection system must detect failure of the primary containment structure at the earliest feasible time.

(i) outer walls of double-walled piping must be protected from corrosion as prescribed in section 599.13(b) of this Part;

(ii) the outer jacket must enclose the primary piping;

(iii) the jacket must be designed to allow for monitoring of leaks as specified in section 599.15(b) of this Part; and

(iv) the jacket must allow for safe venting of vapors.