Recently, the USEPA provided a prepublication copy of standards for the disposal of coal combustion residuals (CCR) in landfills and surface impoundment. Section 257 of the federal code will be modified to include new measures covering the location, design, operation, and closure of existing and proposed CCR disposal units.
Owners of existing CCR surface impoundments will be required to provide assessments of the “structural integrity” of their facilities shortly after publication of the final rules. Owners must obtain a certification from a qualified professional engineer stating that each of these assessments meets the requirements of the stipulated CCR regulations.
Within 18 months of publication, owners or operators of a CCR impoundment must provide the following initial engineering assessments:
Hazard Classification (§257.73(a)2) – The owner is required to document the hazard potential of the impoundment based on the potential loss of human life, economic loss, environmental damage, disruption of lifeline facilities, or other impacts resulting from failure or mis-operation. The hazard classification uses a scale of low, high, or significant, and directly impacts spillway capacity, emergency action planning, and response requirements.
History of Construction (§257.73(c)) – The owner must compile documentation of the physical condition of the impoundment, including information on foundation and abutment soils, embankment and staging information, detailed drawings of the impoundment (including drainage and outlet structures), and normal and peak pool operating elevations.
Structural Stability Assessment (§257.73(d)) – The owner must document the adequacy of the impoundment design, construction, operation, and maintenance. The assessment must document the condition of the impoundment foundation and abutments, slope protection, vegetation, spillway condition and capacity, and associated hydraulic structures.
Safety Factor Assessment (§257.73(e)) – The owner must document the calculated factors of safety for critical cross sections of the impoundment embankments. The safety factor assessment must include stability calculations for operating and loading conditions (such as seismic loading) typical for dam design and construction.
These engineering assessments must be updated every five years following the initial assessment.
Within 24 months, a written Emergency Action Plan (§257.73(a) 3) must be prepared for any CCR surface impoundment classified with high or significant hazard potential. The EAP must contain information on procedures to detect a safety emergency, define responsible persons and notification procedures, provide contact information, include a map delineating the downstream area potentially impacted by a failure, and provide for meetings between the owner and local emergency responders. The written EAP must be reevaluated, at a minimum, every five years.
Longer term (42 months after publication), owners must demonstrate that existing surface impoundments comply with location restrictions for fault areas (§257.62) and seismic impact zones (§257.63). Facilities located within these areas will require site-specific evaluations of the performance of the facilities under seismic (earthquake) events. These evaluations must demonstrate that all structural components (including liners, leachate collection systems, and surface water control systems) are designed to function under the impacts of maximum horizontal ground motion. This task will include performing liquefaction, slope stability, and deformation analyses of waste, foundation, and embankment soils.
Any existing impoundment not demonstrating compliance with these requirements must cease placement of CCR and non-CCR waste streams into the unit within 6 months and commence closure operations in accordance with §257.102.
If you have questions about the proposed changes to the federal rules governing CCR disposal and the engineering assessments discussed, please contact Doug Clark (dclark@cecinc.com; 800-365-2324) or Steve Dixon (sdixon@cecinc.com; 800-365-2324). More information on the proposed rule changes is available at EPA’s website.
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