40 CFR § 194.42 - Monitoring.
(a) The Department shall conduct an analysis of the effects of disposal system parameters on the containment of waste in the disposal system and shall include the results of such analysis in any compliance application. The results of the analysis shall be used in developing plans for pre-closure and post-closure monitoring required pursuant to paragraphs (c) and (d) of this section. The disposal system parameters analyzed shall include, at a minimum:
(1) Properties of backfilled material, including porosity, permeability, and degree of compaction and reconsolidation;
(2) Stresses and extent of deformation of the surrounding roof, walls, and floor of the waste disposal room;
(3) Initiation or displacement of major brittle deformation features in the roof or surrounding rock;
(4) Ground water flow and other effects of human intrusion in the vicinity of the disposal system;
(5) Brine quantity, flux, composition, and spatial distribution;
(6) Gas quantity and composition; and
(7) Temperature distribution.
(b) For all disposal system parameters analyzed pursuant to paragraph (a) of this section, any compliance application shall document and substantiate the decision not to monitor a particular disposal system parameter because that parameter is considered to be insignificant to the containment of waste in the disposal system or to the verification of predictions about the future performance of the disposal system.
(c) Pre-closure monitoring. To the extent practicable, pre-closure monitoring shall be conducted of significant disposal system parameter(s) as identified by the analysis conducted pursuant to paragraph (a) of this section. A disposal system parameter shall be considered significant if it affects the system's ability to contain waste or the ability to verify predictions about the future performance of the disposal system. Such monitoring shall begin as soon as practicable; however, in no case shall waste be emplaced in the disposal system prior to the implementation of pre-closure monitoring. Pre-closure monitoring shall end at the time at which the shafts of the disposal system are backfilled and sealed.
(d) Post-closure monitoring. The disposal system shall, to the extent practicable, be monitored as soon as practicable after the shafts of the disposal system are backfilled and sealed to detect substantial and detrimental deviations from expected performance and shall end when the Department can demonstrate to the satisfaction of the Administrator that there are no significant concerns to be addressed by further monitoring. Post-closure monitoring shall be complementary to monitoring required pursuant to applicable federal hazardous waste regulations at parts 264, 265, 268, and 270 of this chapter and shall be conducted with techniques that do not jeopardize the containment of waste in the disposal system.
(e) Any compliance application shall include detailed pre-closure and post-closure monitoring plans for monitoring the performance of the disposal system. At a minimum, such plans shall:
(1) Identify the parameters that will be monitored and how baseline values will be determined;
(2) Indicate how each parameter will be used to evaluate any deviations from the expected performance of the disposal system; and
(3) Discuss the length of time over which each parameter will be monitored to detect deviations from expected performance.