(1) The secondary containment floor shall slope to one or more liquid tight collection points or sumps that allows spilled or deposited materials to be easily removed.

(2) The walls and floor of secondary containment shall be constructed of steel, poured reinforced concrete, precast concrete modules, solid masonry, or other materials or combination of materials that:

(a) [Shall be designed to withstand a full hydrostatic head of any discharged liquid]

(b) Shall have sufficient thickness and chemical resistance to contain a release until it is recovered.

(c) Shall be constructed and maintained to a permeability standard of 1x10-6 cm/sec as determined by ASTM test method D-5084 Measurement of Hydraulic Conductivity of Saturated Porous Materials Using a Flexible Wall Permeameter or other test method approved by the department;

(d) Shall have sufficient structural strength to maintain the containment's integrity under normally anticipated loadings;

(e) Shall be chemically compatible with the materials being stored; and

(f) Shall be properly sealed to prevent leakage.

(3) Any piping through the outside walls of secondary containment shall be installed and maintained such that the structural integrity of the wall is preserved and in such a manner as to prevent leaks.