KRC comments on Thoroughbred Coal Ash Landfill

 

Ronald D. Gruzesky, Manager By fax and e-mail only

Solid Waste Branch

Division of Waste Management

14 Reilly Road

Frankfort, KY 40601

 

Re: Thoroughbred Generating Company, LLC

Application No. 089-00034 LSI NWI AI#35762

 

Dear Ron:

 

These comments are submitted regarding the draft permit for the special waste landfill intended for disposal of coal fly and bottom ash from the proposed Thoroughbred Generating Company, LLC. coal-fired electrical generating station.

 

Background

 

Disposal of coal combustion wastes presents potential environmental and public health concerns that justify imposition of rigorous design and monitoring standards. The 1988 U.S. Environmental Protection Agency Report to Congress concerning coal combustion wastes (including fly ash, bottom ash, boiler slag and flue gas emission control wastes) acknowledged the range of toxicity and potential for causing groundwater contamination among and within the categories of coal combustion waste. According to the EPA Report Wastes from the Combustion of Coal by Electric Utility Power Plants, EPA/530-SW-88-002:

 

The primary concern regarding the disposal of wastes from

coal-fired power plants is the potential for waste leachate to cause ground-water contamination. Although most of the materials found in these wastes do not cause much concern (for example, over 95 percent of ash is composed of oxides of silicon, aluminum, iron and calcium), small quantities of other constituents that could potentially damage human health and the environment may also be present. These constituents include arsenic, barium, cadmium, chromium, lead, mercury and selenium. At certain concentrations these elements have toxic effects. Id., at ES-4.

 

While the findings of the EPA Report and review of industry-generated studies indicated generally that metals did not leach out of coal combustion waste (CCW) at hazardous (100 x drinking water standards) levels, hazardous levels of cadmium and arsenic were found in ash and sludge samples, and boiler cleaning wastes sometimes contained hazardous levels of chromium and lead. Id.

 

While acknowledging that coal combustion wastes (fly ash and scrubber sludge) do not usually exhibit sufficiently high toxic properties to be classified as hazardous based on TCLP toxicity, a recent study of CCW in Indiana indicated that CCW does contain high enough concentrations of leachable toxic elements to create significant environmental concern. Boulding, J. Russell, Disposal of Coal Combustion Waste in Indiana: An Analysis of Technical and Regulatory Issues (1991).

 

Among the significant findings of this report, which was based on extensive literature review and analysis of coals burned in Indiana utilities (including Kentucky coals), and which should instruct the imposition of final conditions on this permit, were:

 

l. Neither EP nor TCLP tests provide a good indication of leachability of CCW in natural disposal settings. Long-term leaching tests conducted until equilibrium has been achieved for each element of concern, using a leaching solution that approximated percolating groundwater, would give a more accurate depiction of ground-water contamination potential at a disposal site.

 

2. l7 potentially toxic elements are commonly present in CCW: aluminum, antimony, arsenic, barium, beryllium, boron, cadmium, chromium, copper, lead, manganese, mercury, molybdenum, nickel, selenium, vanadium, and zinc.

 

3. Fluidized bed combustion (FBC) wastes retain volatile and semi-volatile elements in the bottom ash to a greater extent than conventional pulverized coal combustion, thus enhancing the leachability of FBC waste elements.

 

4. Leachates from coal power plant ash and flue gas desulfurization wastes typically exceed drinking water standards, but by a factor less than hazardous levels (i.e. 100 x DWS). The major leaching studies on CCW indicate that drinking water standards are typically exceeded by CCW ash leachate at a factor of 1.1 to 10, and often by a factor greater than 10 for one or more elements.

 

5. Disposal of CCW in mine workings may be of particular concern, due to the increase in surface area available for leaching of elements resulting from fracturing of overburden and confining layers; and due also to the higher total dissolved solids levels in mine spoils that compete for sorption sites on solids with toxic elements released from the buried ash.

 

The EPA Report and Boulding study suggest that the management of special wastes at the proposed site must be attuned to the variability of the concentrations of potentially toxic elements in the waste, and to the unique problems presented by the previously-mined nature of the site, and by the fact that the type of special waste is from a fluidized bed combustor.

 

The 1988 EPA Report concluded preliminarily that CCW need not be regulated under RCRA Subpart C as hazardous, but rather that the wastes should continue to be regulated under Subpart D as solid wastes. This conclusion was recently reaffirmed by the agency on an interim basis. In so recommending, EPA determined that while field observations detected off-site migration of potentially hazardous constituents from utility waste disposal sites, reflecting a potentially larger problem than laboratory analyses would suggest, the use of mitigative measures under Subpart D such as installation of liners, leachate collection systems, and ground-water monitoring systems and corrective action to clean up ground-water contamination, would be adequate for protecting public health and the environment. The EPA recommendation was predicated on the application of such measures to the management of CCW. Id. at ES 4-5. This permit, consistent with the problems posed by this type of waste stream and disposal site identified by the literature, and consistent with EPA?s recommendations, should include rigorous controls on placement of the waste, strict limits on concentrations of contaminants in discharge water, and liners in all disposal cells and leachate storage or management ponds or lagoons.

 

 

 

 

Specific Comments

 

Against this backdrop, KRC appreciates the incorporation of a synthetic liner and other leachate controls into the project by the project proponent. After review of the application and correspondence between the agency and project consultants, KRC has these remaining concerns regarding the characterization of the waste, and the proposed design and monitoring of the landfill:

 

1. KRC is concerned that the surface water quality and monitoring program is inefficient and ineffective at meeting the regulatory goals.

 

Initially, the drainage from all disturbed areas, to the extent possible, must be passed through sediment control structures in order to meet sedimentation and other water quality parameters. To the extent that there are disturbances, such as road and well construction, that are outside of the areas controlled by diversion ditches and sediment ponds, application of other control measures must be required to assure that sedimentation and chemical contamination from releases of oil, fuels, drilling fluids, or other contaminants, do not violate water quality standards and the environmental performance standards of 401 KAR 30:031.

 

The proposal to monitor inflow into sediment control structures seems wasteful and redundant, since the KPDE permit will require that the outfall from each structure be tested to demonstrate compliance with water quality standards, including RCRA metals and sediment.

 

What is missing is ambient sampling along receiving waters such as Nelson Creek sufficient to determine whether the facility (including roads, well sites, and other sites not controlled by ponds) is preventing additional contributions of suspended solids and other contaminants to waters of the Commonwealth.

 

Water contaminants can come from a number of sources other than sediment structure discharge – windblown ash containing sorbed metals and organics, spillage from roads of product or ash or road treatment wastes, sediment from disturbed areas associated with roads and wells, and other sources. In order to assure that surface waters are protected from contamination from nonpoint sources associated with the facility, sediment pond outfall monitoring under the KPDES program must be coupled with upstream and downstream monitoring of the receiving stream for indicator parameters that would allow a reasoned assessment of whether the facility as a whole was "contaminating surface water." 401 KAR 45:160 Section 9.

 

Absent such ambient (instream) monitoring, the Cabinet cannot state with any degree of confidence that the facility is contaminating surface water, which is the goal for design of a surface water monitoring program – instead, the only data available will be inflow data into the sediment structures for those areas controlled by the structures (which presumably will show elevated levels of sediments and possibly other constituents) and the outfall measurements (which should show reductions sufficient to meet water quality and effluent limits as applicable).

 

The regulation requires that the water monitoring plan be sufficient to determine whether "water leaving the site or facility has been contaminated." It is a broader mandate than simply the monitoring of point source discharges, and in this instance, periodic up- and downstream monitoring is a far better approach than dual influent-effluent sampling of that component of the site runon and runoff being controlled by sediment structures.

 

401 KAR 45:130 requires that the facility be designed in order to assure that he environmental performance standards of 401 KAR 30:031 will be met. Section 4 of that regulation prohibits any discharge of pollutants violating, among other standards, water quality standards, and is not limited to violations of KPDES obligations by point sources. The proposal to sample pond influent might be valuable, on a limited basis, to match with outflow measurements in order to assess the pond effectiveness, but is insufficient to satisfy 401 KAR 45:160 Section 9 and 401 KAR 30:031.

 

2. The engineering design for a special waste landfill is required to demonstrate compliance with the environmental performance standards of 401 KAR 30:031 and the siting standards of 401 KAR 45:130 after consideration of, among other things, the "physical and chemical characteristics of the waste. KRC is uncertain whether there has been adequate characterization of the waste and consideration of the environmental fate of each constituent in the waste ash. As the Cabinet has noted, the composition of the waste ash will vary depending on the fuel burned and combustion conditions. The ash samples in the Thoroughbred application appear to have been derived from coal combustion in the OMU facility, yet it is unclear whether the coal handling, feed and combustion conditions for that unit are comparable to this proposed power plant. To the extent that the waste feed, preparation, combustion temperature and other variables (such as flue gas temperature and efficiency of baghouse capture of particulates with sorbed metals) that may affect the inorganic and organic constituent compositions in the ash differ, additional characterization may be appropriate to assure compatibility of the material with the liner and cover, and the sufficiency of the liner to capture leachate and prevent violations of environmental performance standards, and of the ash handling system to prevent airborne releases.

 

3. In that same vein, KRC questions whether TCLP testing is sufficient to characterize the leachability of the ash under disposal conditions, since if the ash is alkaline, other tests, such as a neutral water 14-day or other types of test might be needed in addition to TCLP to more fully reflect the release of dissolved metals under long-term conditions.

 

4. To the extent that the liner will be placed on spoil, the Cabinet must be assured that differential settling and liner separation due to settlement of the mine spoil has been anticipated and addressed through compaction and design.

 

 

5. Sufficient compaction must also be achieved for any sediment structure or ash pond used for treatment of contact water. In order to prevent leakage into the subsurface, any ash pond should be lined, and incline piezometers or other effective measures employed to assure that the structures are not leaking leachate into the subsoil beneath.

 

Thank you in advance for your consideration of and written response to these comments.

 

Cordially,

 

 

Tom FitzGerald

Director

 

 

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