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Home My WebLink AboutNC0005363_App D Fate and Transport Model Addendum_20160201Corrective Action Plan Part 2 February 2016 W.H. Weatherspoon Power Plant APPENDIX D FATE AND TRANSPORT MODELING SynTerra P:\Duke Energy Progress.1026\ 109. Weatherspoon Ash Basin GW Assessment Plan\20.EG_CAP\CAP Part 2\ Weatherspoon CAP Part 2 February 2016.docx CAP PART 2 SIMULATIONS FOR W.H. WEATHERSPOON POWER PLANT, LUMBERTON, NC December 16, 2015 Prepared for SynTerra 148 River Street Greenville, SC 29601 Investigators Ronald W. Falta, Ph.D. Regina Graziano, M.S. Scott E. Brame, M.S. Lawrence C. Murdoch, Ph.D. This scenario assumes that extraction wells will be installed and active by July 2016 and ash removal will take place in 2018. It assumes that the ash is no longer a source of contaminant loading and that the land under the ash basin has been restored to a condition similar to that before the construction of the ash basins. In this scenario, a line of three extraction wells to the east of the ash basin and one to the southwest of the ash basin prevent existing contaminants in the formations under the basin from migrating to Jacob Swamp. Since pumping was simulated adjacent to Jacobs Swamp, all swamps were defined as drain boundaries so the pumps limit the amount of water influx from the swamp. The best aquifer for the installation of extraction wells is within model layers 3 to 6 which was interpreted by SynTerra (2015) as the surficial aquifer. The calibration process yielded moderate hydraulic conductivities for the surficial layer and relatively low conductivities for the underlying layer which is the confining Pee Dee Aquifer (layer 7). Four extraction wells were simulated, two wells (EXW-were located in layer 3 through 6 and two wells to the east of the ash basin (EXW-01 and EXW-02) were located in layers 3 through 5 because by including the wells in layer 6, the boron plume would only expand in size. A moderate hydraulic conductivity limits the potential productivity of the extraction wells. The pumping rates used to change the hydraulic regime on the southeast side of the site are listed in Table 1. The locations of the four extraction wells used are shown in Figure 1. Three wells were capable of 20 gallons per minute (GPM) and one well (EXW-03) had a pumping rate of about 23 GPM. While it is possible that higher rates could be achieved in the field resulting in a faster rate of contaminant removal, the simulated pumping rates were constrained by the calibration process. Higher rates prevented the flow model from converging and the maximum rates possible were used in the simulation. For this scenario, the results for layers 3 and 6 are presented for boron and arsenic. Figures 1 through 4 display the results of the Extraction Well scenario for the year 2018. Figures 5 through 16 display the results of the Extraction Well and Ash Basin removal scenarios for the years 2020, 2030, and 2045 respectively. P: \ Duke Energy Progress.1026 \ 109. Weatherspoon Ash Basin GW Assessment Plan\ 20.EG_CAP\ CAP Part 2\ Groundwater Modeling\ Fate and Transport Model Addendum_Weatherspoon.docx Page 2 This most aggressive method does show a reduction of boron in the upper surficial aquifer, especially to the southwest where the extraction wells are located. However, the lower surficial aquifer also simulates an increase in the boron plume similar to the Natural Attenuation and Ash Basin Removal scenarios. Arsenic concentrations within the upper and lower surficial aquifers are almost identical with regard to contaminant plume shape and behavior to Natural Attenuation and capping in place and Ash Removal. The reason is that the arsenic is sorbed (has a relatively high Kd) to the formation material and desorption is slow for this contaminant. This is why there is little arsenic in the lower layers even after sluicing. P: \ Duke Energy Progress.1026 \ 109. Weatherspoon Ash Basin GW Assessment Plan\ 20.EG_CAP\ CAP Part 2\ Groundwater Modeling\ Fate and Transport Model Addendum_Weatherspoon.docx Page 3 Table 1. Pumping rates of wells used for plume capture on the southeast side of the ash basin. Extraction Well # Pumping Rate (GPM) EXW-01 20 EXW-02 20 EXW-03 20 EXW-04 23 P: \ Duke Energy Progress.1026 \ 109. Weatherspoon Ash Basin GW Assessment Plan\ 20.EG_CAP\ CAP Part 2\ Groundwater Modeling\ Fate and Transport Model Addendum_Weatherspoon.docx Page 4 Figure 1. Simulated 2018 boron concentrations (ug/L) in the top model layer of the surficial aquifer (layer 3) for Extraction Wells. P: \ Duke Energy Progress.1026 \ 109. Weatherspoon Ash Basin GW Assessment Plan\ 20.EG_CAP\ CAP Part 2\ Groundwater Modeling\ Fate and Transport Model Addendum_Weatherspoon.docx Page 5 Boron : 11112018 12:00:00 AM 5000.0 2000.0 700.0 LA ti -03 XVV4A Figure 2. Simulated 2018 boron concentrations (ug/L) in the lowest model layer of the surficial aquifer (layer 6) for Extraction Wells. P: \ Duke Energy Progress.1026 \ 109. Weatherspoon Ash Basin GW Assessment Plan\ 20.EG_CAP\ CAP Part 2 \ Groundwater Modeling\Fate and Transport Model Addendum_Weatherspoon.docx Page 6 Figure 3. Simulated 2018 arsenic concentrations (ug/L) in the top model layer of the surficial aquifer (layer 3) for Extraction Wells. P: \ Duke Energy Progress.1026 \ 109. Weatherspoon Ash Basin GW Assessment Plan\ 20.EG_CAP\ CAP Part 2\ Groundwater Modeling\ Fate and Transport Model Addendum_Weatherspoon.docx Page 7 Figure 4. Simulated 2018 arsenic concentrations (ug/L) in the lowest model layer of the surficial aquifer (layer 6) for Extraction Wells. P: \ Duke Energy Progress.1026 \ 109. Weatherspoon Ash Basin GW Assessment Plan\ 20.EG_CAP\ CAP Part 2\ Groundwater Modeling\ Fate and Transport Model Addendum_Weatherspoon.docx Page 8 Boron : 11112020 5000.0 2000.0 700.0 12:00'00 AM Figure 5. Simulated 2020 boron concentrations (ug/L) in the top model layer of the surficial aquifer (layer 3) for Extraction Wells and Ash Basin Removal. P: \ Duke Energy Progress.1026 \ 109. Weatherspoon Ash Basin GW Assessment Plan\ 20.EG_CAP\ CAP Part 2 \ Groundwater Modeling\Fate and Transport Model Addendum_Weatherspoon.docx Page 9 Boron : 11112020 1 5000.0 2000.0 700.0 2:00'00 AM Y5`+ Ifi Figure 6. Simulated 2020 boron concentrations (ug/L) in the lowest model layer of the surficial aquifer (layer 6) for Extraction Wells and Ash Basin Removal. P: \ Duke Energy Progress.1026 \ 109. Weatherspoon Ash Basin GW Assessment Plan\ 20.EG_CAP\ CAP Part 2 \ Groundwater Modeling\Fate and Transport Model Addendum_Weatherspoon.docx Page 10 ti�4 1 1 _ �4 Ifi Figure 6. Simulated 2020 boron concentrations (ug/L) in the lowest model layer of the surficial aquifer (layer 6) for Extraction Wells and Ash Basin Removal. P: \ Duke Energy Progress.1026 \ 109. Weatherspoon Ash Basin GW Assessment Plan\ 20.EG_CAP\ CAP Part 2 \ Groundwater Modeling\Fate and Transport Model Addendum_Weatherspoon.docx Page 10 Figure 7. Simulated 2020 arsenic concentrations (ug/L) in the top model layer of the surficial aquifer (layer 3) for Extraction Wells and Ash Basin Removal. P: \ Duke Energy Progress.1026 \ 109. Weatherspoon Ash Basin GW Assessment Plan\ 20.EG_CAP\ CAP Part 2\ Groundwater Modeling\Fate and Transport Model Addendum_Weatherspoon.docx Page 11 Figure 8. Simulated 2020 arsenic concentrations (ug/L) in the lowest model layer of the surficial aquifer (layer 6) for Extraction Wells and Ash Basin Removal. P: \ Duke Energy Progress.1026 \ 109. Weatherspoon Ash Basin GW Assessment Plan\ 20.EG_CAP\ CAP Part 2\ Groundwater Modeling\Fate and Transport Model Addendum_Weatherspoon.docx Page 12 Figure 9. Simulated 2030 boron concentrations (ug/L) in the top model layer of the surficial aquifer (layer 3) for Extraction Wells and Ash Basin Removal. P: \ Duke Energy Progress.1026 \ 109. Weatherspoon Ash Basin GW Assessment Plan\ 20.EG_CAP\ CAP Part 2\ Groundwater Modeling\Fate and Transport Model Addendum_Weatherspoon.docx Page 13 Figure 10. Simulated 2030 boron concentrations (ug/L) in the lowest model layer of the surficial aquifer (layer 6) for Extraction Wells and Ash Basin Removal. P: \ Duke Energy Progress.1026 \ 109. Weatherspoon Ash Basin GW Assessment Plan\ 20.EG_CAP\ CAP Part 2\ Groundwater Modeling\ Fate and Transport Model Addendum_Weatherspoon.docx Page 14 k:1 Figure 11. Simulated 2030 arsenic concentrations (ug/L) in the top model layer of the surficial aquifer (layer 3) for Extraction Wells and Ash Basin Removal. P:\Duke Energy Progress.1026 \ 109. Weatherspoon Ash Basin GW Assessment Plan\ 20.EG_CAP\ CAP Part 2 \ Groundwater Modeling\ Fate and Transport Model Addendum_Weatherspoon.docx Page 15 Figure 12. Simulated 2030 arsenic concentrations (ug/L) in the lowest model layer of the surficial aquifer (layer 6) for Extraction Wells and Ash Basin Removal. P: \ Duke Energy Progress.1026 \ 109. Weatherspoon Ash Basin GW Assessment Plan\ 20.EG_CAP\ CAP Part 2\ Groundwater Modeling\Fate and Transport Model Addendum_Weatherspoon.docx Page 16 Figure 13. Simulated 2045 boron concentrations (ug/L) in the top model layer of the surficial aquifer (layer 3) for Extraction Wells and Ash Basin Removal. P: \ Duke Energy Progress.1026 \ 109. Weatherspoon Ash Basin GW Assessment Plan\ 20.EG_CAP\ CAP Part 2 \ Groundwater Modeling\ Fate and Transport Model Addendum_Weatherspoon.docx Page 17 Boron : 11112045 12:00:00AM b STu, 5000.0 20(00.0 700.0 Figure 13. Simulated 2045 boron concentrations (ug/L) in the top model layer of the surficial aquifer (layer 3) for Extraction Wells and Ash Basin Removal. P: \ Duke Energy Progress.1026 \ 109. Weatherspoon Ash Basin GW Assessment Plan\ 20.EG_CAP\ CAP Part 2 \ Groundwater Modeling\ Fate and Transport Model Addendum_Weatherspoon.docx Page 17 Boron : 11112045 1 5000.0 2000.0 700.0 2:00'00 AM Y5`+ Figure 14. Simulated 2045 boron concentrations (ug/L) in the lowest model layer of the surficial aquifer (layer 6) for Extraction Wells and Ash Basin Removal. P: \ Duke Energy Progress.1026 \ 109. Weatherspoon Ash Basin GW Assessment Plan\ 20.EG_CAP\ CAP Part 2 \ Groundwater Modeling\Fate and Transport Model Addendum_Weatherspoon.docx Page 18 ti�4 1 1 _ �4 Figure 14. Simulated 2045 boron concentrations (ug/L) in the lowest model layer of the surficial aquifer (layer 6) for Extraction Wells and Ash Basin Removal. P: \ Duke Energy Progress.1026 \ 109. Weatherspoon Ash Basin GW Assessment Plan\ 20.EG_CAP\ CAP Part 2 \ Groundwater Modeling\Fate and Transport Model Addendum_Weatherspoon.docx Page 18 Arsenic : 11=045 12:00:00 AM 1000.0 r 10.0 4 1 � t �� ti ^MI'IiY-i}t f :u !A RIL U.S. Feat 1000 Figure 15. Simulated 2045 arsenic concentrations (ug/L) in the top model layer of the surficial aquifer (layer 3) for Extraction Wells and Ash Basin Removal. P: \ Duke Energy Progress.1026 \ 109. Weatherspoon Ash Basin GW Assessment Plan\ 20.EG_CAP\ CAP Part 2 \ Groundwater Modeling\Fate and Transport Model Addendum_Weatherspoon.docx Page 19 Figure 16. Simulated 2045 arsenic concentrations (ug/L) in the lowest model layer of the surficial aquifer (layer 6) for Extraction Wells and Ash Basin Removal. P: \ Duke Energy Progress.1026 \ 109. Weatherspoon Ash Basin GW Assessment Plan\ 20.EG_CAP\ CAP Part 2\ Groundwater Modeling\Fate and Transport Model Addendum_Weatherspoon.docx Page 20