GEO-HYDRO, INC Consulting in Geology and Hydrogeology

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1 Consulting in Geology and Hydrogeology 16 Mesa Oak Littleton, CO (303) July 24, 2017 Mr. Thomas Cmar Coal Program Attorney Earthjustice 1101 Lake Street, Suite 405B Oak Park, IL Subject: Geo-Hydro, Inc. Review of Proposed Closure and Post-Closure Application Plans Gibson Generating Station Owensville, Indiana Dear Mr. Cmar, Geo-Hydro, Inc. (GHI) has reviewed the Closure and Post-Closure Application Plan 1 (Closure Plan) for the Gibson Generating Station (Gibson), attachments to that plan and other available data as cited. Mark Hutson of Geo-Hydro, Inc. performed this critical review at the request of Earthjustice. The Closure Plan was prepared for Duke Energy (Duke) by ATC and was dated December 16, Critical Review of Closure Plan General Comments and Observations on the Closure Plan The Closure Plan essentially describes a plan for the conversion of previously utilized Coal Combustion Waste (CCW) impoundments, components of the plant waste water treatment system, into unlined landfills located on the floodplain of the Wabash River. Deficiencies and omissions found in the Closure Plan for the Gibson facility include: (1) The key to successful disposal of coal ash is to keep the ash dry. In the context of ash pond closure, capping of the waste is often proposed as a method to prevent precipitation from infiltrating into the ash. Infiltration of precipitation is, however, only one way that water can enter the ash. Wherever the bottom of the ponds is located below the normal groundwater elevation, groundwater will continue to flow through the ash and generate leachate. Leachate that is generated in this manner will flow laterally out of the impoundment and have an adverse impact on water quality downgradient of the ash. Even where the bottom of the ash pond is located above the normal groundwater elevation, high water events (associated with high water in the river) can cause the ash to be re-wetted by rising 1 ATC, 2016

2 groundwater. Episodic re-wetting of ash placed above the normal water table, but within range of high water events will cause continued generation of ash leachate and impacts to downgradient groundwater quality. (2) The data shows that concentrations of ash related constituents have been increasing over time in the Cooling Pond. In essence, this water handling process has turned the Gibson Cooling Pond, the largest hydrologic feature in the vicinity of the plant, into an unlined sluice water and ash leachate holding pond. The entire Gibson Cooling Pond has over time been transformed into a lake of ashcontaminated water. Leakage of water from the Cooling Pond will transport ash-related contaminants through groundwater, the extent of which has not been evaluated. (3) Despite the fact that monitoring conducted to date shows significant ash impacts, the lateral extent of ash-related contaminants in groundwater has not been identified. The Closure Plan proposes (p. 22) to use data from semi-annual groundwater monitoring conducted after closure to better define the extent of the impact to water quality. Monitoring data provided in Table 4 and available in the Indiana Department of Environmental Management (IDEM) virtual file cabinet shows that many of the monitoring wells in the current monitoring system are already known to be contaminated with ashrelated constituents including boron, manganese, sulfate, and total dissolved solids (TDS) in concentrations well above the relevant USEPA water quality standards or Removal Management Levels (RMLs). The sources, magnitude and extent of ash-related groundwater contamination must be determined prior to site closure so that a closure method capable of cleaning-up impacted groundwater may be implemented. (4) Redox sensitive parameters such as arsenic, chromium and other sensitive parameters may be liberated from wastes and/or sediments in response to changes in groundwater elevation, or other changes that affect chemical equilibrium. The closure plan needs to evaluate and describe the conditions that have the potential to affect subsurface redox conditions in order to avoid unexpected releases of ash-related contaminants. (5) The post-closure care period is inadequate, even in the unlikely event that the elevation of the bottom of the ponds is determined to be located well above groundwater. The Closure Plan describes a post-closure care period of at least 30 years. A 30-year post closure care period renders the proposed closure a temporary fix to a permanent problem. Over time, the processes of cap erosion and decomposition, animal burrowing, and/or anthropogenic activities will invariably result in increased infiltration of water into the waste and leaching of contamination into groundwater. Even more problematic is that the monitoring program may have been discontinued by the time that these processes manifest themselves in deteriorating water quality. The proposed Closure Plan essentially pushes the problem under a cover that may last long enough that nobody will be looking. Specific comments on the Gibson North Closure Plan are provided below. 2

3 1) Page 7, North Ash Pond and North Settling Basin These sections of the Closure Plan describe a water handling process where outflow from the North Ash Pond discharges into the North Settling Basin, and water is pumped from the North Settling Basin to the Gibson Cooling Pond. Time-series plots of water quality data 2 from the Gibson Cooling Pond are provided in Attachment 1. The data shows that concentrations of ash related constituents have been increasing over time in the Cooling Pond. In essence, this water handling process has turned the Gibson Cooling Pond, the largest hydrologic feature in the vicinity of the plant, into an unlined sluice water and ash leachate holding pond. The entire Gibson Cooling Pond has over time been transformed into a lake of ash-contaminated water. Leakage of water from the Cooling Pond will transport ash-related contaminants through groundwater, the extent of which has not been evaluated. 2) Page 8, 6 th paragraph The Closure Plan 3 identifies two irrigation wells (records and ) located within the one-half mile radius from the North Ash Basin System. These wells are presumed to be located upgradient of the North Ash Basin System. This may be correct under normal flow conditions, however, both of these wells are likely downgradient of the East Ash Ponds and Settling Basin and likely to be affected by radial flow of contaminated water out of the impacted Cooling Pond. It would be prudent to include these wells in the groundwater sampling program in order to detect impacts from coal ash. 3) Page 10, 4 th paragraph - The assumption of groundwater flow to the west-northwest toward the Wabash River is an over simplification. Groundwater flow direction in the floodplain of the Wabash River is influenced by the stage of the river as well as by infiltration and radial flow from impoundments. Groundwater flow is highly variable in this setting. 4) Page 14, last paragraph - The Closure Plan indicates that the base of coal ash elevation in the North Ash Basin System is at an elevation of approximately 375 feet. Figure 3 shows the Wabash River at an elevation of and groundwater elevations at up to 385 feet. The data included in the Closure Plan confirm that ash is located four feet below the elevation of the river and 10 feet below groundwater. The high groundwater elevations beneath the ash basins are unlikely to diminish appreciably as long as the overwhelming influence of the Cooling Pond continues to be present. 5) Page 16, 2 nd paragraph - There are no unaffected background wells in the vicinity of the North Ash Basin System. The Closure Plan identifies monitoring wells MW-35A, MW-35B,and MW- 35C as typically located hydraulically upgradient of the North Settling Basin. The MW-5 and MW-6 well clusters are identified as being hydraulically upgradient relative to the North Ash Pond. All of these wells are located downgradient of ash contaminated water that leaks from 2 Water quality data for the Gibson Cooling Water Pond were provided in Table 4. 3 Appendix A, Sheet 3 3

4 the Cooling Pond, the North Ash Pond, and/or the East Ash Ponds. In addition, changes in river stage can significantly change the direction of groundwater flow beneath these facilities. Analytical results summarized in Table 4 shows that concentrations of boron, sulfate and TDS are elevated and increasing in concentration. 6) Page 19, 3 rd paragraph - Characterization of groundwater quality using only six of the 34 analyzed parameters is insufficient. Review of monitoring data obtained from the IDEM Virtual File Cabinet shows that manganese is very often detected and arsenic is sporadically detected in concentrations above their respective water quality standards. Redox sensitive parameters such as arsenic, chromium and other sensitive parameters may be liberated from wastes and/or sediments in response to geochemical changes induced by surface disturbances, changes in groundwater elevation, or other actions that change the geochemical equilibrium. The closure plan needs to identify and evaluate any changes to geochemical conditions that may be anticipated in order to avoid unexpected releases of ash-related contaminants. 7) Pages 21 and 22 - The description of the proposed statistical testing to be utilized during performance monitoring is a prime example of how statistics can be used to minimize the likelihood of detecting continuing releases of ash constituents to groundwater. Performance goals for each well are established based on current conditions for each parameter. The control limit used for comparison to individual monitoring concentrations is defined as the mean value plus 4.5 times the standard deviation of baseline values. Setting the control limit to the mean plus 4.5 standard deviations would be exceptionally effective at assuring that releases to the environment are never identified, regardless of whether or not the selected remedy is effective. The proposed closure plan however goes even further to eliminate the possibility of identifying an insufficient closure. The plan indicates that a potential indicator of a departure from remedy effectiveness is four successive goal limits exceeded in a single monitoring well over the scheduled (semi-annual) monitoring frequency. A single well has to exceed its unreasonably high limit during every sampling event over a two year period in order to be identified as exceeding the goal. This is exceptionally unlikely given the highly variable groundwater flow directions in the floodplain setting. The Closure Plan acknowledges this feature of the proposed data evaluation scheme on page 22 where it states the response of the constituent (parameter) concentrations on site groundwater as a result of corrective actions given the hydrogeologic conditions could take years to evaluate potential concentration shifts. 8) Page 27 - The post-closure care period is inadequate. Even if the elevations of the bottom of the ponds were above groundwater the proposed closure cannot be viewed as permanent. A 30- year post closure care period renders the proposed closure a temporary fix to a permanent problem. Over time, the processes of cap erosion and decomposition, animal burrowing, and/or anthropogenic activities will invariably result in increased infiltration of water into the waste and leaching of contamination into groundwater. Even more problematic is that the monitoring 4

5 program may have been discontinued by the time these processes manifest themselves in deteriorating water quality. The proposed Closure Plan essentially pushes the problem under a cover that may last long enough that nobody will be looking at water quality impacts by the time they again become problematic. 9) Table 4 Groundwater quality is impaired by these facilities. Review of the analytical data contained in Table 4 shows that the most of the wells that are currently being monitored show concentrations of ash-related constituents at concentrations above applicable USEPA water quality standards or RMLs. Boron at concentrations above its RML 4 in 148 of the 286 reported analyses. Sulfate and TDS were detected in concentrations above their secondary drinking water standards in 114 and 286 samples, respectively. Despite the fact that monitoring conducted to date shows significant impacts, the lateral extent of these impacts has not been identified. 10) Figures and Cross-Sections Comparison of the cross sections included in the Ash Basin Closure Plan 5 and the water level map provided in Figure 3 shows that the bottom of the ash impoundments is below groundwater elevation, even at a normal river stage. High water events in the river will cause even more of the ash to be below the rising groundwater. Episodic rewetting of ash placed above the normal water table, but within range of high water events will cause continued generation of ash leachate and impacts to downgradient groundwater quality. Statement of Qualifications I hold bachelors and master s degrees in geology and have over 35 years of experience on a wide range of environmental characterization and remediation sites. My education includes B.S. and M.S. degrees in geology from Northern Illinois University and the University of Illinois at Chicago, respectively. I am a registered Professional Geologist (PG) in Kansas, Nebraska, Indiana, North Carolina, and Wisconsin, a Certified Professional Geologist by the American Institute of Professional Geologists, and am a Past President of the Colorado Ground Water Association. I have served in various technical and managerial roles in conducting all aspects of site characterization and remediation including definition of the nature and extent of contamination, directing human health and ecological risk assessments, conducting feasibility studies for selection of appropriate remedies to meet remediation goals, and implementing remedial strategies. For the last ten years much of my consulting activity has been related to groundwater contamination and permitting issues at coal ash storage and disposal sites. 4 The RML for boron is 4 mg/l. 5 Appendix A 5

6 Thank you for the opportunity to conduct a critical review of the Gibson North Closure Plan. Given the significant deficiencies identified above, I suggest that IDEM take immediate action to determine to extent of groundwater impacts from the contaminated Cooling Pond as well as the Ash Pond Systems. IDEM should then consider the shortcomings identified herein as well and newly developed information prior to reaching a decision the proposed Closure Plan. Sincerely, Mark A. Hutson, P.G. Geo-Hydro, Inc mhutson@geo-hydro.com 6

7 References ATC (2016), Proposed Ash Basin Closure and Post Closure Plans, Ash Pond System, Gibson Generating Station, Owensville, IN, December 16, McCarthy, G.J., Butler, R.D., Grier, D.G., Adamek, S.D., Parks, J.A., and Foster, H.J. (1997), Longterm stability of landfilled coal combustion by-products, Fuel, vol. 76, No. 8, pp

8 Attachment 1 Gibson Cooling Pond Water Quality Gibson Cooling Pond Boron Concentration Gibson Cooling Pond Sulfate Concentration Boron Removal Management Level Boron (mg/l) 200 Sulfate Secondary MCL Sulfate (mg/l) 0 5/10/ /13/2002 5/12/ /2/2005 5/10/ /10/2008 5/18/ /7/2011 5/14/ /5/2014 5/6/2016 Sample Date 0 5/10/2001 5/13/2003 5/18/2005 5/10/2007 5/12/2009 6/21/2011 5/14/2013 5/4/2015 Sample Date Gibson Cooling Pond TDS Concentration TDS Secondary MCL TDS (mg/l) /10/2001 5/13/2003 5/18/2005 5/10/2007 5/12/2009 6/21/2011 5/14/2013 5/4/2015 Sample Date Data Provided in Table 4 of the Closure Plan