40 CFR § 265.303 - Response actions.
(a) The owner or operator of landfill units subject to § 265.301(a) must develop and keep on site until closure of the facility a response action plan. The response action plan must set forth the actions to be taken if the action leakage rate has been exceeded. At a minimum, the response action plan must describe the actions specified in paragraph (b) of this section.
(1) Notify the Regional Administrator in writing of the exceedance within 7 days of the determination;
(2) Submit a preliminary written assessment to the Regional Administrator within 14 days of the determination, as to the amount of liquids, likely sources of liquids, possible location, size, and cause of any leaks, and short-term actions taken and planned;
(3) Determine to the extent practicable the location, size, and cause of any leak;
(4) Determine whether waste receipt should cease or be curtailed, whether any waste should be removed from the unit for inspection, repairs, or controls, and whether or not the unit should be closed;
(5) Determine any other short-term and longer-term actions to be taken to mitigate or stop any leaks; and
(6) Within 30 days after the notification that the action leakage rate has been exceeded, submit to the Regional Administrator the results of the analyses specified in paragraphs (b)(3), (4), and (5) of this section, the results of actions taken, and actions planned. Monthly thereafter, as long as the flow rate in the leak detection system exceeds the action leakage rate, the owner or operator must submit to the Regional Administrator a report summarizing the results of any remedial actions taken and actions planned.
(i) Assess the source of liquids and amounts of liquids by source,
(ii) Conduct a fingerprint, hazardous constituent, or other analyses of the liquids in the leak detection system to identify the source of liquids and possible location of any leaks, and the hazard and mobility of the liquid; and
(iii) Assess the seriousness of any leaks in terms of potential for escaping into the environment; or
(2) Document why such assessments are not needed.