40 CFR § 265.253 - Containment.
If leachate or run-off from a pile is a hazardous waste, then either:
(a)
(1) The pile must be placed on an impermeable base that is compatible with the waste under the conditions of treatment or storage;
(2) The owner or operator must design, construct, operate, and maintain a run-on control system capable of preventing flow onto the active portion of the pile during peak discharge from at least a 25-year storm;
(3) The owner or operator must design, construct, operate, and maintain a run-off management system to collect and control at least the water volume resulting from a 24-hour, 25-year storm; and
(4) Collection and holding facilities (e.g., tanks or basins) associated with run-on and run-off control systems must be emptied or otherwise managed expeditiously to maintain design capacity of the system; or
(b)
(1) The pile must be protected from precipitation and run-on by some other means; and
(2) No liquids or wastes containing free liquids may be placed in the pile.