By Boyd Ramsey
On Friday, Dec. 19, 2014, the United States Environmental Protection Agency (EPA) issued rules on the disposal of coal combustion residuals (“coal ash”). These rules take effect 180 days after publication in the Federal Register, but for general intents and purposes will affect geosynthetics users immediately.
In short, the EPA is requiring coal ash to be disposed of in a manner consistent with Subtitle “D” of the RCRA (Resources Conservation and Recovery Act) that governs disposal of municipal solid waste. Additional benefits to the geosynthetics industry are the inclusion in the new rules of approval for “alternative clay liners” (read GCLs, geosynthetic clay liners) and rules governing capping and closure of both new and existing sites that mandate the use of composite liners for capping. Both of these should serve to broadly expand the geosynthetic market size in the USA.
Sales and technical comments
The fate of coal ash storage sites and the application of these regulations are summarized here:
- Existing unlined units with groundwater contamination issues must be closed.
- Existing unlined units with structural integrity issues must be closed.
- All other existing unlined units must dewater and close (Subtitle “D” compliant cap) within three years from the date the rule becomes effective or become subjected to the rules as a “new” site.
- Any vertical or lateral expansion at a unit makes that unit subject to the regulations applied to new sites.
- Lined units will close with a (Subtitle “D” compliant cap) when appropriate.
Importantly, the regulations include the approved use of “alternative clay liners” on a national level. (In the past this was done on a state-by-state basis.) The Geosynthetic Materials Association (GMA) worked hard to get this provision included in the rules and I am pleased that it is present. The specific language and references are included in the notes at the end of this document.
Further, the “Florida method” for composite liners using ash/fill materials as a portion of the barrier system is not allowed. (See note below.) The use of a GCL alone is also prohibited. (See note below.)
Dam safety controls and seismic analysis are now a part of the site engineering and risk reviews.
Leachate control (opportunities for drainage geocomposites) is mandated as identical to Subtitle “D”—a maximum of 30cm of leachate above the composite liner system.
Quoting notes and text from the new regulations
RE: Alternative clay liners: pages 240–245 Section “D” Design Criteria – Liner Design: “While EPA agrees with those commenters arguing that new CCR disposal units should only be installed with a composite liner system of some kind, the Agency has concluded that not all alternative designs for a composite liner system should necessarily be rejected as insufficiently protective… EPA’s own studies showing that a GM/GCL liner can be constructed to achieve hydraulic efficiencies in the range of 99–99.9%, which meets or exceeds the hydraulic performance of a GM/compacted clay liner (CCL) design. 67 In addition, these high efficiencies demonstrate that the GCL component of a GM/GCL composite liner is at least as effective in impeding leakage through holes in the GM component of the composite liner system as a CCL with a hydraulic conductivity no more than 1×10-7 cm/sec.68 In fact, EPA has developed guidance for the selection and installation of various types of liners including a GM/GCL.69… EPA has concluded, consistent with many of the comments received and its own analysis, that an alternative composite liner for new CCR units is warranted (my emphasis added)… As such, the Agency is allowing new CCR units to be designed and constructed with an alternative composite liner, as described below, provided the lower component of the composite liner meets a specified performance standard.”
RE: The “Florida design” pages 245–246, Section 2:
“Liner Designs That Would Not Meet the Requirements of a Composite Liner or Alternative Liner… EPA has also determined that the double liner system set forth in Florida regulations (see Florida Rules 62-701.400(3)(c),F.A.C) also does not (my emphasis added) meet the level of performance achieved by EPA’s composite liner system or the alternative liner system.”
RE: No GCLs alone page 246, Section 2:
“…Taking all of this information into account, the Agency remains unconvinced that a GCL alone is a viable alternative to a composite liner.”
Boyd Ramsey is the chairman of the Geosynthetic Materials Association’s Executive Council.