CCR's, What Else?

Timmons, Dale to: James Kohler 01/29/2013 11:18 AM

From: "Timmons, Dale" <Dale.Timmons@naes.com>

To: James Kohler/DC/USEPA/US@EPA

History: This message has been replied to and forwarded.

Hi Jim:

After our discussion the other day, I went back to the Proposed Rule: Hazardous and Solid 

Waste Management System; Identification and Listing of Special Wastes; Disposal of Coal 

Combustion Residuals From Electric Utilities and read the definition of CCR Surface 

Impoundment or Impoundment which appears on Page 35130 of the Proposed Rule. I reviewed 

this in the context of application of Dense Slurry System (DSS) technology on coal combustion 

ash.

That definition is:

“CCR Surface Impoundment or impoundment means a facility or part of a facility which is a 

natural topographic depression, man-made excavation, or diked area formed primarily of earthen 

materials (although it may be lined with man-made materials), which is designed to hold an 

accumulation of CCRs containing free liquids, and which is not an injection well. Examples of 

CCR

surface impoundments are holding, storage, settling, and aeration pits, ponds, and lagoons. CCR 

surface impoundments are used to receive CCRs that have been sluiced (flushed or mixed with 

water to facilitate movement), or wastes from wet air pollution control devices, often in addition 

to other solid wastes.”

The part of the definition that interests me is: “which is designed to hold an accumulation of 

CCRs containing free liquids”.

This part of the definition specifies a design but the spirit of the definition really is directed at 

impoundments that contain free liquids. Arguably, one could design an impoundment to contain 

free liquids but if free liquids were never stored in the impoundment, then it really would not 

meet the intent of this definition.

An example provided as part of the definition includes: “CCR surface impoundments are used to 

receive CCRs that have been sluiced (flushed or mixed with water to facilitate movement)”.

Clearly, DSS technology uses water to facilitate movement of the ash. However, the water is 

also used to cause pozzolanic reactions designed to solidify the ash into a cement product. In 

addition, the water is consumed in these reactions stoichiometrically and thus is not free liquid 

for long; certainly not after 24-48 hours.

Dry ash systems also use water to facilitate movement; although partially for a different reason. 
Dry ash systems mix water with ash with as much as 15-20% water to suppress dust. This is 

done to facilitate movement with reduced risk of generating dust and to assist in compaction and 

solidification once the ash is placed in the impoundment (as with DSS).

One could argue that “dry ash management” mixes water to facilitate movement of the ash and 

thus, even dry systems, from one perspective, could be construed to incorporate mixing with 

water to facilitate movement. Further, “dry” ash is currently being placed into impoundments 

that were originally designed to accept ash containing free liquids. A literal interpretation of the 

definition of an impoundment would mean that impoundments that were designed to accept free 

liquids but which only contain dry ash would still have a questionable definition. These would 

not be attractive interpretations. 

Both dry ash systems and dense slurry systems result in elimination of free liquids from ash 

impoundments. It seems clear that both dry ash management systems and DSS technology 

satisfy the intent of the rule to eliminate free liquids from surface impoundments. In fact, DSS 

results in a product with hydraulic conductivity that is lower than that resulting from dry ash 

management and exhibits reduced risk of dust generation. So, from the perspective of 

environmental protection, DSS is a superior process. 

You had mentioned that you might be able to discuss this topic further internally. Any 

clarification that can be offered on the definition above and it’s applicability to ash management 

systems would be welcomed.

I appreciate your time an attention to this topic and I know that you have your work cut out for 

you.

Best Regards,

Dale Timmons, R.G.| ESS Business Development| NAES Corporation

1180 NW Maple Street Suite 200

Issaquah, WA 98027‐8106

dale.timmons@naes.com

425‐961‐ 4697 (direct)

425‐961‐4700 (main)

425‐961‐4646 (fax)

www.naes.com