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Home My WebLink AboutNC0005363_Chemical Characterization of water for dewatering of ash basins_20150323 f' W DUKE L.V.Sutton Energy Complex ENERGY® 801 Sutton Steam Rd ICWilmington, NCC28401 PROGRESS 0:910.341.4750 f:910.341.4790 March 23, 2015 RECEIVED/DENR/DWR Certified Mail 47012 1640 0000 4619 6722 Mr.Jeffrey Poupart,Section Chief MAR 31 2015 NC Division of Water Resources 1617 Mail Service Center Water Quality Raleigh, NC 27699-1617 Permitting Section Subject: Addendum to NPDES Waste Water Permit Application Permit Chemical characterization of water for dewatering of ash basins Weatherspoon Plant NC0005363 Robeson County Mr. Poupart, Duke Energy hereby submits the attached characterization of wastewaters for the subject facility. The analysis conducted and reported herein is consistent with the information requested by NC DENR for other Duke Energy sites. This is submitted in support of potential ash pond dewatering activities that would be directed to outfall 001.The attached table provides results of chemical analysis of both ash basin free water and ash basin interstitial water. The ash basin bulk water samples were taken from water above the ash in the basin, and are presented without treatment. Currently,the water level in the ash pond at Weatherspoon is very low, approximately 4 feet deep,therefore the bulk water sample was only taken at one depth. Interstitial water sample results were analyzed 1.)without additional treatment beyond the treatment in the basin and 2.)after treatment with three different sized filters. Because of the low water levels in these basins, Duke foresees dewatering activities involving the use of pumps and/or removal of sections of risers or stop logs to facilitate potential dewatering activities. Specific dewatering work plans will be developed to assure the work will be done safely and in compliance with all applicable requirements. Once developed,these plans can be made available to you for review upon request. The following definitions may be useful as you consider these activities. Ash basin free water: Water in an ash basin located above the settled layer of ash. Ash basin free water has undergone treatment in the ash basin, has the same general characteristics as water discharged when the facility was active sluicing ash to the ash basin, is largely devoid of Total Suspended Solids and meets all applicable NPDES permit limits. Ash basin interstitial water: Water in an ash basin that is located within the pore space of accumulated wastewater sludge or slurry. Ash basin interstitial water must be removed from an ash basin by some means such as trenching,well points,etc. and would likely require additional treatment before being released to the environment. The process we envision for dewatering the ash basins is as follows: Ash basin free water will be removed from the primary basin via the use of pumps. Interstitial water removal will likely be accomplished through rim ditching,trenching,and pumping. Additional treatment of ash basin interstitial water may be completed via chemical and/or physical processes prior to discharge. This treatment system may Weatherspoon Plant NPDES Permit NC0005363 Addendum to NPDES Application require the addition of a coagulant and/or flocculent to enhance solids removal. Compliance monitoring required by the NPDES Permit as well as robust process control monitoring will be performed. Process control monitoring and additional safeguards and controls to be employed include: • All pumps will be controlled to stop at a user-defined level set point which is set manually every 7 days. The maximum free water drawdown rate will be one foot over seven days. Following free water removal, accumulated storm-water will be removed at a maximum rate of 2 feet over 1 day. Additionally, dewatering discharge rates will not exceed historical discharge rates of 2.1 MGD(as reported in our 2009 permit application). • The ash basin pumps will be controlled with a real-time process control total suspended solids(TSS) meter.A real-time process control pH meter will control a carbon dioxide injection system to maintain pH between 6.0 and 9.0 standard units(SU). • In addition to the real-time monitoring,handheld TSS and pH meters will be used daily for additional process control field measurements of samples. The handheld TSS meter will undergo laboratory validation and site-specific field verification. Daily pH monitoring will be conducted with a portable pH meter. Discharge flow rates will be monitored daily using an inline flow meter,a handheld flow meter,or a v-notch discharge weir. Normal monitoring required by the NPDES permit will continue uninterrupted during the dewatering process. As the dewatering process transitions from the removal of ash basin free water to the removal of ash basin interstitial water phase it is anticipated that a filtration system may be used to maintain compliance with permit limits. Please include a provision in the modified permit to allow the use of a coagulant or flocculent from the state's approved list to facilitate the filtration process if needed. If you have any questions regarding this submittal,please contact LeToya Ogallo,Environmental Specialist at our NC Regional Headquarters at(919)546-6647 or Letoya.Ogallo@Duke-Energy.com. I certify, under penalty of law, that this document and all attachments were prepared under my direction or supervision in accordance with a system designed to assure that qualified personnel properly gather and evaluate the information submitted. Based on my inquiry of the person or persons who manage the system, or those persons directly responsible for gathering the information, the information submitted is, to the best of my knowledge and belief, true, accurate, and complete. I am aware that there are significant penalties for submitting false information,including the possibility of fines and imprisonment for knowing violations. Sincerely, d/411t-? - Allen A.Clare Station Manager Enclosures cc: Kent Tyndall LeToya Ogallo Table 1 Weatherspoon Plant Ash Basin Water Characterization- Samples Collected February 4, 2015 i Sample Description Interstitial 20u Interstitial 10u Interstitial 0.45 u Parameter Units Bulk Water Interstitial Water filter filter filter Oil and Grease mg/L < 5 Nitrite+Nitrate mg-N/L < 0.01 < 0.01 < 0.01 < 0.01 < 0.01 Total Kjeldahl Nitrogen mg-N/L 0.25 1.1 1.1 1 0.81 Bromide mg/L < 0.10 0.64 0.65 0.65 0.64 Chloride mg/L 2.51 25.52 25.70 25.44 25.51 Fluoride mg/L < 0.10 0.79 0.79 0.79 0.80 Sulfate mg/L 25.40 14.58 14.64 14.63 14.84 Aluminum(Al) mg/L 0.13 0.18 0.17 0.11 < 0.05 Barium(Ba) mg/L 0.14 1.57 1.55 1.45 0.86 Boron(B) mg/L < 0.5 2.9 2.85 2.83 2.81 Calcium(Ca) mg/L 13.7 176 175 174 169 Iron(Fe) mg/L < 0.1 37.2 36.8 31.2 < 0.1 Magnesium(Mg) mg/L 1.77 35.5 35 35.2 34.6 Manganese(Mn) mg/L < 0.05 1.05 1.02 1.01 0.95 Phosphorus(P) mg/L < 0.2 < 0.2 < 0.2 < 0.2 < 0.2 Zinc(Zn) mg/L < 0.05 < 0.05 < 0.05 < 0.05 < 0.05 Antimony(Sb) ug/L 6.72 < 1 < 1 < 1 < 1 Arsenic(As) ug/L 9.46 1070 1080 901 112 Cadmium(Cd) ug/L < 1 < 1 < 1 < 1 < 1 Chromium(Cr) ug/L < 1 < 1 < 1 < 1 < 1 Copper(Cu) ug/L 2.14 < 1 < 1 < 1 < 1 Lead(Pb) ug/L < 1 < 1 < 1 < 1 < 1 Molybdenum(Mo) ug/L 27.6 25.1 25.2 25.5 23.1 Nickel(Ni) ug/L 2.55 11.6 11.5 11.4 11.1 Selenium(Se) ug/L 40.3 < 1 < 1 < 1 < 1 Thallium(TI)Low Level ug/L 0.86 < 0.2 < 0.2 < 0.2 < 0.2 Vanadium(V) ug/L 14.1 6.02 6.02 4.89 < 1 Mercury(CVAFS) ng/L 3.75 3.18 2.7 1.09 < 0.50 pH* SI Units 6.97 7.53 7.81 7.68 7.55 TDS mg/L 87 990 960 960 970 TSS mg/L < 5 91 92 54 < 5 * pH samples analyzed outside of the EPA hold time of 15 minutes