25 Pa. Code § 299.151 – Storage and containment of ash residue from residual waste incineration.

Ash residue from residual waste incineration shall be stored as follows:

(1) In an enclosed container, which may include a properly tarped container, or in an enclosed area, which may include an adequately ventilated building.
(2) On a pad that is no more permeable than 1 x 10^-7 cm/sec.
(3) In a manner that prevents the release, dispersal or discharge of ash residue into the air, water or onto land.

This section cited in 25 Pa. Code § 299.101 (relating to scope).