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Home My WebLink AboutNC0038377_Final Permit_20071214i>IVAT�C� Michael F. Easley, Governor '^? State of North Carolina 01 William G Ross, Jr., Secretary 0? r Department of Environment and Natural Resources Coleen H Sullins, Director Division of Water Quality December 14, 2007 Mr Larry E. Hatcher, Plant Manager Progress Energy Carolinas, Inc. Mayo Electric Generating Plant 10660 Boston Road Roxboro, NC 27574 Subject. Issuance of NPDES Permit NCO038377 Mayo Steam Plant Person County Dear Mr. Hatcher. Division personnel have reviewed and approved your application for modification of the subject permit Accordingly, we are forwarding the attached NPDES discharge permit This permit is issued pursuant to the requirements of North Carolina General Statute 143-2151 and the Memorandum of Agreement between North Carolina and the U S Environmental Protection Agency dated October 15, 2007 (or as subsequently amended) This final permit contains the following significant changes from the draft you were sent on June 6, 2007: ➢ Limits and monitoring requirements for antimony, boron, cobalt, and molybdenum have been added based on the unforeseeable potential these parameters may have to cause an exceedance of water quality criteria ➢ The minimum flow limit has been removed based on your company's decision to accept additional metals monitoring. ➢ The beryllium limit has been updated to reflect the current aquatic life standard of 6.5 jig/ L. If any parts, measurement frequencies or sampling requirements contained in this permit modification are unacceptable to you, you have the right to an adjudicatory hearing upon written request within thirty (30) days following receipt of this Ietter This request must be in the form of a written petition, conforming to Chapter 150B of the North Carolina General Statutes, and filed with the Office of Administrative Hearings (6714 Mail Service Center, Raleigh, North Carolina 27699-6714) Unless such demand is made, this decision shall be final and binding Please note that this permit is not transferable except after notice to the Division. The Division may require modification or revocation and reissuance of the permit This permit does not affect the legal requirements to obtain other permits which may be required by the Division of Water Quality or permits required by the Division of Land Resources, the Coastal Area Management Act or any other Federal or Local governmental permit that may be required. If you have any questions concerning this permit, please contact Toya Fields at telephone number (919) 733-5083, extension 551 Sincerely, S7- �en HSullins cc Central Files Raleigh Regional Office/Surface Water Protection NPDES Unit � Aquatic Toxicology Unit Marshall Hyatt / EPA 1617 Mad Service Center, Raleigh, North Carolina 27699-1617 Telephone (919) 733-7015 FAX (919) 733-0719 OnrthCarolina 512 N Salisbury Street, Raleigh, North Carolina 27604 On the Internet at http Hh2o enr state nc us/ Naturally Equal Opportunity/Affirmative Action Employer It Permit NCO038377 STATE OF NORTH CAROLINA DEPARTMENT OF ENVIRONMENT AND NATURAL RESOURCES DIVISION OF WATER QUALITY PFRMTT TO DISCHARGE WASTEWATER UNDER THE NATIONAL POLLUTANT DISCHARGE ELIMINATION SYSTEM In compliance with the provision of North Carolina General Statute 143-215.1, other lawful standards and regulations promulgated and adopted by the North Carolina Environmental Management Commission, and the Federal Water Pollution Control Act, as amended, Carolina Power and Light d/b/a/ Progress Energy Carolinas, Inc. is hereby authorized to discharge wastewater from a facility located at the Mayo Steam Electric Generating Plant off of US Highway 501 northeast of Roxboro Person County to receiving waters designated as the Mayo Reservoir in the Roanoke River Basin in accordance with effluent limitations, monitoring requirements, and other conditions set forth in Parts I, II, III, and IV hereof. The permit shall become effective January 1, 2008. This permit and the authorization to discharge shall expire at midnight on March 31, 2012. Signed this day December 14, 2007. .een H. Sullins, Director ,ision of Water Quality Authority of the Environmental Management Commission Permit NC00383177 SUPPLEMENT TO PERMIT COVER SHEET All previous NPDES Permits issued to this facility, whether for operation or discharge are hereby revoked. As of this permit issuance, any previously issued permit bearing this number is no longer effective. Therefore, the exclusive authonty to operate and discharge from this facility arises under the permit conditions, requirements, terms, and provisions included herein. Carolina Power and Light d/b/a/ Progress Energy Carolinas, Inc. is hereby authorized to: 1. Continue to operate the following systems located at Mayo Steam Electric Generating Plant, off of US Highway 501, northeast of Roxboro, Person County: • Cooling Tower System (Outfall 001). Less than once per year the cooling towers and circulating water system are drained by gravity and discharged directly to Mayo Reservoir. Ash Pond Treatment System (Outfall 002). Outfall 002 discharges directly to Mayo Reservoir. The ash pond receives ash transport water, coal pile runoff, stormwater runoff, cooling tower blowdown, and various low volume wastes such as boiler blowdown, oily waste treatment, wastes/backwash from the water treatment processes, plant area wash down water, equipment heat exchanger water, and treated domestic wastewater. • Internal Outfall 008. Cooling tower blowdown is directly discharged to the ash pond. Cooling tower blowdown is usually mixed with ash sluice water prior to discharge to the ash pond. Cooling tower blowdown is indirectly discharged to Mayo Reservoir via the ash pond treatment system (Outfall 002). • Internal Outfall 009. Discharge from the FGD blowdown treatment system. • Stormwater Discharge System The facility is permitted to discharge stormwater to Mayo Reservoir through the following outfalls: • Outfall 004 - Drainage from the outside storage area. • Outfall 005 - Drainage from the industrial area and the oil/bottled gas storage area. • Outfalls 006a, 006b, 006c, 006d, 006e - Drainage from the cooling tower(s) chemical feed building structure and the cooling tower area. 2. Discharge from said treatment works and/or outfalls at the locations specked on the attached maps into Mayo Reservoir, which is classified as WS -V waters in the Roanoke River Basin. Permit NCO038377 A. (1) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS [001] During the period beginning on the effective date of the permit and lasting until expiration, the Permittee is authorized to discharge from Outfall 001 (Cooling Tower System) Monitoring is required only during discharge events to the Mayo reservoir Such discharges shall be limited and monitored by the Permittee as specified below PARAMETER LIMITS MONITORING REQUIREMENTS Monthly Daily Average Maximum Measurement Sample Type Sample Frequency Locationl Flow Daily Pump Logs or similar readings Effluent Free Available Chlorine2 200 lig/L 500 Ng/L Weekly Grab Effluent Time of Chlorine Addition2 2 hours Weekly Logs Total Chromium3 0 2 mg/L 0 2 mg/L 2 / Month Grab Effluent Total Zinc3 10 mg/L 10 mg/L 2 / Month Grab Effluent Priority Pollutants 3 No Detectable Amount Annual Grab Effluent pH > 6 0 and < 9 0 standard units Weekly Grab Effluent Notes: 1 Samples taken in compliance with the monitoring requirements listed above shall consist of cooling tower effluent prior to its discharge to Mayo Reservoir 2. Monitoring is required only if chlorine -based compounds is added to the system Neither free available chlorine nor total residual chlorine may be discharged from any single generating unit for more than two hours per day, unless the Permittee demonstrates to the Division of Water Quality that discharge for more than two hours is required for macroinvertebrate control The 500 µg/l limitation is an instantaneous maximum and is to be measured during the chlorine release period The 200 µg/l limitation is an average during the chlorine release period Simultaneous multi -unit chlorination is permitted 3 Limitations and monitoring requirements for the 126 Priority Pollutants (per 40 CFR Part 423, Appendix A, exclusive of zinc and chromium) apply only if these substances are added by the permittee for cooling tower maintenance Compliance with the limitations for the 126 priority pollutants in 40 CFR 423 13 (d) (1) may be determined by engineering calculations which demonstrate that the regulated pollutants are not detectable in the final discharge by the analytical methods in 40 CFR Part 136 All primary industries are required to submit a, priority pollutant analysis in accordance with 40 CFR Part 122 with their application for permit renewal. The above listed effluent limitations shall be sampled prior to draining the cooling tower(s), at a location prior to discharge to Mayo Reservoir There shall be no discharge of polychlorinated biphenyl compounds such as those commonly used for transformer fluid Permit NCO0383 77 A. (2) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS [008] During the period beginning on the effective date of the permit and lasting until expiration, the Permittee is authorized to discharge from Outfall 008 (internal outfall, Cooling Tower System) Such discharges shall be limited and monitored by the Permittee as specified below: PARAMETER LIMITS MONITORING REQUIREMENTS Monthly Daily Average Maximum Measurement Sample Sample Frequency Type Locationl Flow Daily Pump Logs or similar readings Effluent Free Available Chlorine2 200 lug/L 500 ug/L Weekly Grab Effluent Time of Chlorine Addition2 2 hours Weekly Logs Total Chromium3 0 2 mg/L 0 2 mg/L 2 / Month Grab Effluent Total Zinc3 10 mg/L 10 mg/L 2 / Month Grab Effluent Priority Pollutants 3 No Detectable Amount Annual Grab Effluent pH > 6 0 and < 9 0 standard units Weekly Grab Effluent Notes: 1 Samples taken in compliance with the monitoring requirements listed above shall consist of cooling tower blowdown after mixing with the fly and bottom ash, but prior to discharging into the ash pond 2 Monitoring is required only if chlcrine-based compound is added to the system Neither free available chlorine nor total residual chlorine may be discharged from any single generating unit for more than two hours per day, unless the Permittee demonstrates to the Division of Water Quality that discharge for more than two hours is required for macroinvertebrate control The 500 pg/l limitation is an instantaneous maximum and is to be measured during the chlorine release period The 200 µg/l limitation is an average during the chlorine release period Simultaneous multi -unit chlorination is permitted 3 Limitations and monitoring requirements for the 126 Priority Pollutants (per 40 CFR Part 423, Appendix A, exclusive of zinc and chromium) apply only if these substances are added by the permittee for cooling tower maintenance Compliance with the limitations for the 126 priority pollutants in 40 CFR 423 13 (d) (1) may be determined by engineering calculations which demonstrate that the regulated F-ollutants are not detectable in the final discharge by the analytical methods in 40 CFR Part 136 All primary industries are required to submit a priority pollutant analysis in accordance with 40 CFR Part 122 with their application for permit renewal. This outfall is not authorized to discharge directly to the Mayo Reservoir Permit NCO038377 A. (3) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS [002 without FGD wastewater] During the period beginning on the effective date of the permit and lasting until expiration, the Permittee is authorized to discharge from Outfall 002 (Ash Pond Treatment System). Such discharges shall be limited and monitored by the Permittee as specified below. PARAMETER LIMITS MONITORING REQUIREMENTS Monthly Daily Average Maximum Measurement Sample Sample Frequency Type Locationl Flow Weekly Pump Logs or similar readings Effluent Oil and Grease 15 0 m /L 20 0 m /L Monthly Grab Effluent Total Suspended Solids 30 0 m /L 100 0 m /L Monthly Grab Effluent Total Selenium2 3 8 lbs/day 2 / Month Grab Effluent Acute Toxicit 3 Quarterly Grab Effluent Total Arsenic4 Quarterly Grab Effluent 'Total Copper Quarterly Grab Effluent Total Iron Quarterly Grab Effluent pH > 6 0 and < 9 0 standard units 2 / Month Grab Effluent Notes: 1. Samples taken in compliance with the monitoring requirements listed above shall be taken prior to mincing with other waste streams. 2. See A. (8). 3. Acute Toxicity (Fathead Minnow 24hr) No significant mortality at 90%, February, May, August, and November, See A. (7). 4. See A. (13). After the FGD treatment system is used to treat FGD wastewater, the effluent limits in Conditions A (4) and A (5) apply There shall be no discharge of floating solids or visible foam in other than trace amounts outside an area five(5) meters from the discharge pipe No chemical metal cleaning waste may be discharged to the ash pond There shall be no discharge of polychlorinated biphenyl compounds such as those commonly used for transformer fluid Permit NCO038377 A. (4) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS [002 with FGD wastewater] During the period beginning upon commencement of the FGD treatment system to treat FGD wastewater and lasting until expiration, the Permittee is authorized to discharge from Outfall 002 (Ash Pond Treatment System) Such discharges shall be limited and monitored by the Permittee as specified below PARAMETER LIMITS MONITORING REQUIREMENTS Monthly Average I weekly Average Daily Maximum Measurement Frequency Sample Type , r , Sample Location' Flow Weekly Pump Logs or similar readings Effluent Oil and Grease 15 0 m /L 20 0 m /L Monthly Grab Effluent Total Suspended Solids 30 0 m /L 100 0 m /L Monthly Grab Effluent Total Selenium 3 8 lbs/day Weekly Grab Effluent Acute Toxicit 3 Quarterly Grab Effluent Total Mercury2,4 0 012 /L Weekly Grab Effluent Total Arsenics Weekly Grab Effluent Total Ber Ilium2 6 5 /L Weekly Grab Effluent Total Cadmium2 2 0 /L Weekly Grab Effluent Total Chlondes2 672 0 m iL 860 0 m /L Weekly Grab Effluent, MZ6 Total Chromium2 50 0 /L Weekly Grab Effluent Total Copper Weekly Grab Effluent Total Fluoride2 18 m /L Weekly Grab Effluent Total Lead2 25 0 p lL 33 8 /L Weekly Grab Effluent Total Man anese2 200 0 H /L Weekly Grab Effluent Total Nickel Weekly Grab Effluent Total Silver Weekly Grab Effluent Total Zinc Weekly Grab Effluent Total Banum2 10 mg/L Weekly Grab Effluent Total Thallium2 0 35 pg/L Weekly Grab Effluent Total Vanadium2 24 0 H /L Weekly Grab Effluent Total Antimon 2 5 6 p9iL Weekly Grab Effluent Total Boron2 750 0 /L Weekly Grab Effluent Total Cobalt' 65 0 c/L Weekly Grab Effluent Total Mol bdenum2 170 N L Weekly Grab Effluent 'Total Iron Quarterly Grab Effluent H > 6 0 and < 9 0 standard units 2 / Month Grab Effluent Notes: 1 Samples taken in compliance with the monitoring requirements listed above shall be taken prior to mixing with other waste streams 2 The limit and monitoring frequency becomes applicable 24 months after the commencement of the FGD system Twice monthly monitoring is required upon initial commencement of the FGD system 3. Acute Toxicity (Fathead Minnow 24 -hr) No significant -mortality at 90%; February, May, August, and November [see A. (7)] 4 The mercury limit will take effect one year after commencement of the FGD system to treat FGD wastewater 5 See A. (13). 6 Instream sampling for chlorides is required at the edge of the mixing zone, 200 meters linear distance from the discharge point Monitoring shall begin upon commencement of the FGD system and shall last for 5 years After the FGD treatment system is used to treat FGD wastewater, the effluent limits in Conditions A (4) and A (5) apply Progress Energy shall inform this office as well as the Raleigh Regional Office, via phone call and via letter, as to when the FGD treatment system will be used to treat FGD wastewater. Permit NCO038377 A. (4) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS [002 with FGD wastewater] Continued There shall be no discharge of floating solids or visible foam in other than trace amounts outside an area five (5) meters from the discharge pipe No chemical metal cleaning waste may be discharged to the ash pond There shall be no discharge of polychlorinated biphenyl compounds such as those commonly used for transformer fluid A. (5) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS [009] During the period beginning upon commencement of the FGD treatment system to treat FGD wastewater and lasting until expiration, the Permittee is authorized to discharge from Internal Outfall 009 (treated FGD wet scrubber wastewater) Such discharges shall be limited and monitored by the Permittee as specified below PARAMETER LIMITS Monthly Daily Average Maximum MONITORING REQUIREMENTS Measurement Sample Sample Frequency Type Locationl Flow Monthly Instantaneous E Total Suspended Solids Weekly Grab E Total Mercury Weekly Grab E Total Selenium Weekly Grab E Total Arsenic Weekly Grab E Total Beryllium Weekly Grab E Total Cadmium Weekly Grab E Total Chlorides Weekly Grab E Total Chromium Weekly Grab E Total Copper Weekly Grab E Total Fluoride Weekly Grab E Total Lead Weekly Grab E Total Manganese Weekly Grab E Total Nickel Weekly Grab E Total Silver Weekly Grab E Total Barium Weekly Grab E Total Thallium Weekly Grab E Total Vanadium Weekly Grab E Total Antimony Weekly Grab E Total Boron Weekly Grab E Total Cobalt Weekly Grab E Total Molybdenum Weekly Grab E Total Zinc Weekly Grab E Notes: 1 E — Effluent from the FGD treatment system prior to discharge to the Ash Pond Permit NC0038377 A. (6) STORMWATER MONITORING REQUIREMENTS/ Qualitative Monitoring Qualitative monitoring requires a qualitative inspection of each stormwater outfall, regardless of representative outfall status, for the purpose of evaluating the effectiveness of the Stormwater Pollution Prevention Plan and assessing new sources of stormwater pollution. No analytical tests are required. Qualitative monitoring of stormwater outfalls does not need to be performed during a representative storm event Stormwater Discharge Characteristics Measurement Frequencyi SampleLocation U f Color Semi -Annual Stormwater Discharge Outfall Odor Semi -Annual Stormwater Discharge Outfall Clarity Semi -Annual Stormwater Discharge Outfall Floating Solids Semi -Annual Stormwater Discharge Outfall Suspended Solids Semi -Annual Stormwater Discharge Outfall Foam Semi -Annual Stormwater Discharge Outfall Oil Sheen Semi -Annual Stormwater Discharge Outfall Other obvious indicators of stormwater pollution Semi -Annual Stormwater Dischar a Outfall Notes: 1. Measurement Frequency Qualitative monitoring will be performed twice per year, once in the spring (April - June) and once in the fall (September - November) A. (7) ACUTE TOXICITY PASS/FAIL PERMIT LIMIT (Quarterly) Outfall 002 (Ash Pond) The permittee shall conduct acute toxicity tests on a quarterlu basis using protocols defined in the North Carolina Procedure Document entitled "Pass/Fail Methodology For Determining Acute Toxicity In A Single Effluent Concentration" (Revised -July, 1992 or subsequent versions). The monitoring shall be performed as a Fathead Minnow (Prmephales promelas) 24 hour static test The effluent concentration at which there may be at no time significant acute mortality is 90% (defined as treatment two in the procedure document) Effluent samples for self-monitoring purposes must be obtained during representative effluent discharge below all waste treatment The tests will be performed during the months of February, May, August and November All toxicity testing results required as part of this permit condition will be entered on the Effluent Discharge Monitoring Form (MR -1) for t_ie month in which it was performed, using the parameter code TGE6C Additionally, DWQ Form AT -2 (original) is to be sent to the following address Attention North Carolina Division of Water Quality Environmental Sciences Section 1621 Mail Service Center Raleigh, North Carolina 27699-1621 Completed Aquatic Toxicity Test Forms shall be filed with the Environmental Sciences Branch no later than 30 days after the end of the reporting period for which the report is made Test data shall be complete and accurate and include all supporting chemical/ physical measurements performed in association with the toxicity tests, as well as all dose/response data. Total residual chlorine of the effluent toxicity sample must be measured and reported if chlorine is employed for disinfection of the waste stream. Should there be no discharge of flow from the facility during a month in which toxicity monitoring is required, the permittee will complete the information located at the top of the aquatic toxicity (AT) test form indicating the facility name, permit number, pipe number, county, and the month/year of the report with the notation of "No Flow" in the comment area of the form The report shall be submitted to the Environmental Sciences Branch at the address cited above Permit NCO038377 Should any single quarterly monitoring indicate a failure to meet specified limits, then monthly monitoring will begin immediately until such time that a single test is passed. Upon passing, this monthly test requirement will revert to quarterly in the months specified above. Should the permittee fail to monitor during a month in which toxicity monitoring is required, then monthly monitoring will begin immediately until such time that a single test is passed. Upon passing, this monthly test requirement will revert to quarterly in the months specified above. Should any test data from either these monitoring requirements or tests performed by the North Carolina Division of Water Quality indicate potential impacts to the receiving stream, this permit may be re -opened and modified to include alternate monitoring requirements or limits NOTE: Failure to achieve test conditions as specified in the cited document, such as minimum control organism survival and appropriate environmental controls, shall constitute an invalid test and will require immediate follow-up testing to be completed no later than the last day of the month following the month of the initial monitoring. A. (8) SELENIUM STUDY The Permittee shall conduct biological and physical/ chemical studies on selenium and its effect in the reservoir. The results shall be submitted each year by May 1 for the prior calendar year. The plan of study shall be submitted to the Director of the Division of Water Quality for approval. A. (9) CRUTCHFIELD BRANCH There shall be no direct discharge of wastewater from the ash pond to Crutchfield Branch. There shall be no violation of water quality standards in Crutchfield Branch due to any indirect discharge from the ash pond. The Permittee shall monitor the waters of Crutchfield Branch, 100 yards downstream of the dike, once per year by grab sample for the following- arsenic, copper, and selenium. A. (10) DOMESTIC WASTEWATER TREATMENT PLANT The domestic wastewater treatment plant shall be properly operated and maintained to ensure treatment of domestic wastewater to secondary levels. A. (11) STORMWATER POLLUTION PREVENTION PLAN The permittee shall develop a Stormwater Pollution Prevention Plan, herein after referred to as the Plan. The Plan shall be considered public information in accordance with Part II, Section E. 10. of this permit. The Plan shall include, at a minimum, the following items: a. Site Plan: The site plan shall provide a description of the physical facility and the potential pollutant sources which may be expected to contribute to contamination of regulated stormwater discharges. The site plan shall contain the following: (1) A general location map (USGS quadrangle map, or appropriately drafted equivalent map), showing the facility's location in relation to transportation routes and surface waters, and the name of the receiving water(s) to which the stormwater outfall(s) discharges. If the discharge is to a municipal separate storm sewer system, the name of the municipality and the ultimate receiving waters, and accurate latitude and longitude of the point(s) of discharge must be shown. Permit NCO038377 (2) A narrative description of storage practices, loading and unloading activities, outdoor process areas, dust or particulate generating or control processes, and waste disposal practices (3) A site map (or series of maps) drawn to scale with the distance legend indicating location of industrial activities (including storage of materials, disposal areas, process areas, and loading and unloading areas), drainage structures, drainage areas for each outfall and activities occurring in the drainage area, building locations and impervious surfaces, the percentage of each drainage area that is impervious. For each outfall, a narrative description of the potential pollutants which could be expected to be present in the regulated stormwater discharge. (4) A list of significant spills or leaks of pollutants that have occurred at the facility during the 3 previous years and any corrective actions taken to mitigate spill impacts. (5) Certification that the stormwater outfalls have been evaluated for the presence of non- stormwater discharges. The certification statement will be signed in accordance with the requirements found in Part II, Section B 11. b. Stormwater Management Plan- The stormwater management plan shall contain a narrative description of the materials management practices employed which control or minimize the exposure of significant materials to stormwater, including structural and non-structural measures. The stormwater management plan, at a minimum, shall incorporate the following: (1) A study addressing the technical and economic feasibility of changing the methods of operations and/or storage practices to eliminate or reduce exposure of materials and processes to stormwater. Wherever practicable the permittee should consider covering storage areas, material handling operations, manufacturing or fueling operations to prevent materials exposure to stormwater. In areas where elimination of exposure is not practicable, the stormwater management plan shall document the feasibility of diverting the stormwater runoff away from areas of potential contamination. (2) A schedule to provide secondary containment for bulk storage of liquid materials, storage of Section 313 of Title III of the Superfund Amendments and Reauthorization Act (SARA) water priority chemicals, or storage of hazardous materials to prevent leaks and spills from contaminating stormwater runoff. If the secondary containment devices are connected directly to stormwater conveyance systems, the connection shall be controlled by manually activated valves or other similar devices [which shall be secured with a locking mechanism] and any stormwater that accumulates in the containment area shall be at a minimum visually observed prior to release of the accumulated stormwater. Accumulated stormwater shall be released if found to be uncontaminated. Records documenting the individual making the observation, the description of the accumulated stormwater and the date and time of the release shall be kept for a period of five years. (3) A narrative description of Best Management Practices (BMPs) to be considered such as, but not limited to, oil and grease separation, debris control, vegetative filter strips, infiltration and stormwater detention or retention, where necessary. The need for structural BMPs shall be based on the assessment of potential of sources contributing significant quantities of pollutants to stormwater discharges and data collected through monitoring of stormwater discharges. (4) Inspection schedules of stormwater conveyances and controls and measures to be taken to limit or prevent erosion associated with the stormwater systems. C. Spill Prevention and Response Plan: The Spill Prevention and Response Plan shall incorporate a risk assessment of potential pollutant sources based on a materials inventory of the facility. Facility personnel (or team) responsible for implementing the plan shall be identified in the plan A responsible person shall be on-site at all times during facility operations that have the Permit NC0038377 potential to contaminate stormwater runoff through spills or exposure of materials associated, with the facility operations. d. Preventative Maintenance and Good Housekeeping Program- A preventative maintenance program shall be developed. The program shall document schedules of inspections and maintenance activities of stormwater control systems, plant equipment and systems. Inspection of material handling areas and regular cleaning schedules of these areas shall be incorporated into the program. e. Training schedules shall be developed and training provided at a minimum on an annual basis on proper spill response and cleanup procedures and preventative maintenance activities for all personnel involved in any of the facility's operations that have the potential to contaminate stormwater runoff. Facility personnel (or team) responsible for implementing the training shall be identified in the plan. L The Stormwater Pollution Prevention Plan shall identify a specific position(s) responsible for the overall coordination, development, implementation, and revision to the Plan. Responsibilities for all components of the Plan shall be documented and position(s) assignments provided. g. Plan Amendment: The permittee shall amend the Plan whenever there is a change in design, construction, operation, or maintenance which has a significant effect on the potential for the discharge of pollutants via a point source to surface waters. The Stormwater Pollution Prevention Plan shall be reviewed and updated on an annual basis. The director may notify the permittee when the Plan does not meet one or more of the minimum requirements of the permit. Within 30 days of such notice, the permittee shall submit a time schedule to the Director for modifying the Plan to meet minimum requirements. The permittee shall provide certification in writing (in accordance with Part III, Standard Conditions, Section B.11.) to the Director that the changes have been made. h. Facility Inspections: Inspections of the facility and all stormwater systems shall occur at a minimum on a semiannual schedule, once in the fall (September - November) and once during the spring (April - June). The inspection and any subsequent maintenance activities performed shall be documented, recording date and time of inspection, individual(s) making the inspection and a narrative description of the facility's stormwater control systems, plant equipment and systems. Records of these inspections shall be incorporated into the Stormwater Pollution Prevention Plan. Visual monitoring as required in A(4) Stormwater Monitoring Requirements/ Qualitative Monitoring shall be performed in addition to facility inspections. L Implementation: Implementation of the Plan shall include documentation of all monitoring, measurements, inspections, maintenance activities and training provided to employees, including the log of the sampling data. Activities taken to implement BMPs associated with the industrial activities, including vehicle maintenance activities, must also be recorded. All required documentation shall be kept on-site for a period of five years and made available to the Director or his authorized representative immediately upon request. A. (12) STORMWATER MINIMUM MONITORING AND REPORTING REQUIREMENTS Minimum monitoring and reporting requirements are as follows unless otherwise approved in writing by the Director of the Division of Water Quality: - a. If a facility has multiple discharge locations with substantially identical stormwater discharges that are required to be sampled, the permittee may petition the Director for representative outfall status. If it is established that the stormwater discharges are substantially identical and the permittee is granted representative outfall status, then sampling requirements may be performed at a reduced number of outfalls. Permit NCO038377 b. Visual monitoring for color, odor, solids, foam, outfall staining, visible sheens and dry weather flow shall be performed at all stormwater discharge outfall locations. All visual monitoring shall be documented and records maintained with the Stormwater Pollution Prevention Plan. The initial visual monitoring event shall be performed during the Spring of 2006. C. For purposes of the stormwater sampling required in this permit, all samples shall be collected from a discharge resulting from a representative storm event (See definitions in Part II, Section A). Failure to monitor storm events in accordance with the specified frequency shall constitute a violation of this permit. If the stormwater runoff is controlled by a detention pond, the following sampling requirements shall apply: (1) If the detention pond detains the runoff generated by one inch of rainfall for 24 hours, visual observations for color, foam, outfall staining, visible sheens and dry weather flow are required, but analytical sampling shall not be required (2) If the detention pond discharges only in response to a storm event exceeding a 25 -year, 24-hour storm, the pond shall be considered a non -discharging stormwater control system and not subject to NPDES requirements, unless the discharge causes a violation of water quality standards. d. Samples analyzed in accordance with the terms of this permit shall be submitted on forms approved by the Director no later than January 31 for the previous year in which sampling was required to be performed. Analytical results from sampling during the final year of the permit term shall be submitted with the permit renewal application. This permit regulates stormwater discharges associated with industrial activity. Non- stormwater discharges which shall be allowed in the stormwater conveyance system are: (1) All other discharges that are authorized by an NPDES permit. (2) Foundation drains, air -conditioner condensate without added chemicals, springs, waterline and fire hydrant, water from footing drains, flows from riparian habits and wetlands, fire -fighting training and fire system testing, wash down water without added chemicals. (3) Discharges resulting from fire -fighting g. If the storm event monitored and reported in accordance with this permit coincides with a non- stormwater discharge, the permittee shall separately monitor and report all parameters as required under the non-stormwater portion of this permit and provide this information with the stormwater discharge monitoring report. No analytical monitoring is required by the permit. A. (13) FISH TISSUE SAMPLING: Progress Energy shall conduct fish tissue sampling for Arsenic on an annual basis. The fish tissue sampling plan shall be approved by the Division's Environmental Sciences Section prior to commencement of sampling. Mayo Permit Update Subject: Mayo Pernut Update From: "Cahoon, Steve" <Steve.Cahoon@pgnmail.com> Date: Thu, 6 Dec 2007 08.54:18 -0500 To: <toya.fields@ncmail.net> Toya, I wanted to get an update on when the final permit for Mayo may be sent to the plant. Do you have any info I can forward to plant folks as well as our construction folks? Also, we are going to add a truck wheel wash to wash gypsum and limestone off truck wheels before it leaves the site, that wash water will go to an oil water separator and then to the ash pond We presently have an oil water separator onsite that goes to low volume waste and then to the ash pond. Will the additional oil water separator change our permit limits at the ash pond? Please let me know Thanks for your help Steve Cahoon Environmental, Health and Safety Services Mail Code PEB4 Vnet - 770-7457 Bell - 919-546-7457 1 of 1 12/17/2007 8 10 AM Mayo NPDES Permitting Options Subject: Mayo NPDES Permitting Options From: "Cahoon, Steve" <Steve. Cahoon@ pgnmail.com> Date: Mon, 19 Nov 2007 15:36:52 -0500 To: <toya.fields@ncmail.net> CC: "Enzor, Earl" <kenneth.enzor@pgnmail.com>, "Hatcher, Larry" <Larry.Hatcher@pgnmail.com>, "Holt, Fred" <fred holt@pgnmail.com>, "Madewell, Alan" <Alan.Madewell@pgnmatl.com> Toya, As a follow up to our earlier phone conversation we have selected an option to proceed with our NPDES permit for the Mayo facility. We would like our permit to reflect the addition of 4 parameters (Antimony, Boron, Cobalt and Molybdenum) without a minimum flow limit, we also request that these parameters have a two year compliance period associated with them as well, to be consistent with other parameters currently in our permit We also request that at this time the permit limit for Beryllium be changed to reflect the current water quality standard of 6 5 ug/I, instead of the current weekly average limit in the draft permit of 0.0068 ug/I The plant requests that the Division proceed with these changes and finalize our permit as soon as possible A formal response selecting the above referenced permit option from the Mayo Plant signatory (Larry Hatcher) will be forthcoming Also, an updated Flow Diagram will be sent with the letter, the updated flow diagram will reflect the proposed future addition of a side stream from the FGD intake pumps to the cooing towers This addition was discussed with the Division in a meeting on November 9, 2007 Please contact me if you have any questions Steve Cahoon Environmental, Health and Safety Services Mail Code PEB4 Vnet - 770-7457 Bell - 919-546-7457 1 of 1 12/17/2007 8 10 AM Mayo FGD & Cooling Tower Make Up Water Balance Ash Pond Ash Sluice " 3,300 GPM Condensers * 3,300 GPM GP 2,000 GPM FGD Heat Exchangers 7,700 GPM 4,300 GPM Mayo Lake Intake: Avg. = 3,800 GPM (FGD MU) + 7,700 (1 CT MU Pump) = 11,500 GPM = 16.6 MGD 258.000 GPM MU CT MU Avg. 1,800 GPM Make Up Water for Basin Level 6,200 GPM Evaporation Cooling Towers * Can utilize either flow path Progress Energy Mayo FGD & Cooling Tower Make Up Water Balance Ash Pond Ash Sluice ' 3,300 GPM Condensers * 3,300 GPM M 2,000 GPM FGD Heat Exchangers 7,700 GPM 4,300 GPM Mayo Lake Intake: Avg. = 3,800 GPM (FGD MU) + 7,700 (1 CT MU Pump) = 11,500 GPM = 16.6 MGD 258,000 GPM D MU CT MU Avg. 1,800 GPM Make Up Water for Basin Level 6,200 GPM Evaporation Cooling Towers * Can utilize either flow path �j+� Progress Energy Progress Energy Carolinas, Inc Attachment 1 b for Fact Sheet Mayo Electric Generating Plant NCO038377 Parameter Estimated FGD (C Waters) Allowable Estimated Effluent Acute Maximum Predicted Blowdown Conc ' WQ standard EPA Criteria\llowat uq/L conc uq/L ^^ Values uq/L conc for RPA # Limit or Monitor? Antimony 440 56 5 6 041 541 Monitor Arsenic 390 10 10 1000 13200 Monitor Barium 25190 1000 1000 8438 111382 Limit Beryllium 250 00068 00068 084 11 09 Limit Boron 790 750 750 265 3498 Monitor Cadmium 80 2 2 027 15 356 Limit Chloride (mg/L) 160000 230 mg/L (AL) 230000 535945 98 7074486 94 Limit Chromium 121 0 50 50 405 1022 5346 Limit Cobalt 770 65 1 65 028 370 Monitor Copper 720 7 (AL) 7 017 224 Monitor Fluoride 184000 1 8 mg/L 1800 61634 8135.69 Limit Lead 790 25 25 265 338 3498 Limit Manganese 14500 200 200 4857 64112 Limit Mercury 380 0 012 0.012 061 805 Limit Molybdenum 12900 170 170 1 90 2508 Monitor Nickel 5760 25 25 079 261 1043 Monitor Selenium 54800 5 5 2500 56 330 00 Keep Limit Thallium 8 0 035 035 005 066 Limit Vanadium 650 24 24 218 2878 Limit Zinc 36900 50 (AL) 50 742 67 9794 Monitor (AL) Concentrations are in ug/L unless otherwise noted ^^ The concentration output is based on the flow from the ash pond (7 3 MGD) + flow from FGD (0 253) = 7 553 MGD = mass (lbs/day)/ (7 553 ' 8 34) = conc mg/L # Estimated effluent conc ' 13 2 IWC = 100% (assumed, since discharge is into the Lake and no modeling was conducted) Limit or monitor determined by one data point (the estimated concentration from the ash pond effluent). As defined in EPA TSD for one data point, CV = 0.6 and the multiplier is 13.2 c Progress Ener 9 9Y LeToya Fields NC Division of Water Quality 1617 Mail Service Center Raleigh, NC 27699-1617 R� -crcc---- - -- LSEP22007 DENR - WATER QUALITY POINT SOURCE BRANCH SEP 2 4 2007, Subject: Carolina Power & Light Company d/b/a Progress Energy Carolina, Inc. Mayo Electric Generating Plant NPDES Permit No. NCO038377 Comments on Draft Permit Dear Ms. Fields: Thank you for working with us through this permit modification. We have evaluated the two options presented to us by the Division. These options are: 1) keeping the minimum flow requirement for Outfall 002 as proposed in the draft permit or 2) accepting additional permit limits for antimony, boron, cobalt and molybdenum with no minimum flow requirement. After evaluating both options we accept the draft permit with a minimum flow requirement of 7.3 MGD, with some qualification as presented below. We believe the Division recognizes that the proposed minimum flow requirement is associated with reducing the level of chlorides in the future FGD wastewater and is a design factor an the mixing zone model. It as our understanding that the proposed minimum flow requirement is expressed as a daily minimum that is proposed to be met at all times, i.e. 24 hours a day/seven days a week/365 days a year. Progress Energy intends to ensure compliance with the proposed limitation by providing supplemental flow by the installation of additional intake capacity with redundancy. However it must be recognized that there will be occasions when ensuring a minimum flow is not needed from a permitting standpoint and to require such without qualification as an unnecessary use of water and power and would mflact unnecessary wear on materials Also at must be recognized that there may be unexpected events such as pump malfunctions, power interruption, etc. that may render the site unable to provide the prescribed continuous flows The intent of the following proposed special condition or note as to attempt to recognize these situations and to provide a qualification that would allow us to have a waiver from the minimum flow requirement during these situations We propose the following language, associated with the minimum flow, be added an a footnote to paragraph A. (4) of our draft NPDES permit - Progress Energy Carolinas, Inc Mayo Steam Plant 10660 Boston Road Roxboro, NC 27574 SEP x 4 2007 The minimum flow requirement is not applicable during the following events. 1) Power failures or other physical or mechanical events unpreventable by the reliability requirements at 15A NCAC 2H .0124. 2) Periods of time when there is no discharge of FGD wastewater through the bioreactor. 3) Maintenance of pumps, or associated conveyance structures that requires the item to be out of service Also, because of the supplemental water required to ensure compliance with the minimum flow requirements, we would like to establish a new Outfall (0 10) at a point beyond (downstream) where the supplemental water is proposed to enter the discharge canal to Mayo Lake. The supplemental water is proposed to be routed to the discharge canal to avoid any conflicts with the technology-based limits for the ash pond discharge. We also request that the compliance point for flow monitoring and the metals monitoring requirements and limits in paragraph A. (4) of the current draft permit be moved from the Ash Pond Discharge (Outfall 002) to the new Outfall (010) Please modify our existing application of record accordingly with the enclosed schematic. We also recommend that the flows at Outfall 010 be determined by summing the flows from Outfall 002, (Instantaneous), Outfall 009 (Instantaneous) and the new supplemental water flow (Pump logs or similar) Also Note 2 of paragraph A. (4) states that the limit becomes effective 24 months after the commencement of the FGD system. We would like that note to read as follows. the limit becomes effective 24 months after the discharge of treated FGD wastewater through Outfall 009 If you have any questions regarding this submittal please contact Steve Cahoon at (919) 546-7457. 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, Larry E. Hatcher — Plant Manager Mayo Electric Generating Plant Re Draft permit status update Subject: Re: Draft permit status update From: Toya Fields <toya.fields@ncmail.net> Date: Wed, 08 Aug 2007 16:32:57 -0400 To: "Cahoon, Steve" <Steve. Cahoon@ pgnmail.com> CC: "Enzor, Earl" <kenneth.enzor@pgnmatl.com> Steve, We've taken a look at your comments. We can remove the flow minimum, but since we can't do a true reasonable potential analysis without that information, we'd have to add limits for nearly all parameters of concern for the FGD system. The draft permit you reviewed had limits for nearly everything predicted to be in the FGD wastewater except antimony, boron, cobalt, and molybdenum. So if you want to remove the flow minimum, we'd just have to add in limits for those four parameters. As always, once the system gets up and running and we have more data to review, you guys will be able to request a re-evaluation of some of these limits. Also, instream monitoring will need to remain in the permit. The requirement is consistent for all other facilities throughout the state that have limits based on dilution models. Its fine if you sample at the boat ramp. I think those were your biggest concerns. Let me know how to proceed. Toya Cahoon, Steve wrote: Sergei was also given worst case scenario parameters in 2005. I believe arsenic was one of the parameters Sergei was concerned about (we are required by permit to conduct biological sampling for arsenic in the Lake for the past two years) in addition we have been monitoring the lake for many parameters including metals since the plant began operation in the mid 1980's. Our biological monitoring team continues to report that we are not seeing any accumulation of arsenic in fish tissue. In my absence please contact Earl Enzor copied on this response or by phone at 546-2136. Thanks' Steve Cahoon Progress Energy Carolinas, Inc. Environmental, Health and Safety Services - POG Vnet 770-7457 Bell (919) 546-7457 steve.cahoon@pgnmail.com -----Original Message ----- From: Toya Fields [mailto:toya.fields@ncmail.net] Sent: Wednesday, August 08, 2007 12:09 PM To: Cahoon, Steve Subject: Re: Draft permit status update Its really not the chlorides we were concerned about, its the other parameters that Sergei added in 2005. I think some of those were based on the 7.3 MGD assumption. Thats what we're taking another look at. Is there anyone that I should direct questions to while you are on vacation? 1 of 2 10/10/2007 1 21 PM Re Draft permit status update Cahoon, Steve wrote: Hey Toya, Keep in mind while you're looking at the permit that the model was set up using worst case scenario numbers for example a worst case input of 20,000 ppm of chlorides from coal versus the expected 15,0Oppm chlorides Ifrom coal and drought conditions in the lake, which are much worse than 7Q10 conditions. We do not expect to see either of these worst case scenario conditions. Let me know if you have questions. Steve Cahoon Progress Energy Carolinas, Inc. Environmental, Health and Safety Services - POG Vnet 770-7457 Bell (919) 546-7457 steve.cahoon@pgnmail.com -----Original Message ----- From: Toya Fields[mai.lto:toya.fields@ncmail.net] Sent: Wednesday, August 08, 2007 11:26 AM To: Cahoon, Steve Subject: Draft permit status update Hi Steve, We're working on your draft modification. We're looking into the flow minimum and trying to determine whether or not changing that 7.3 MGD assumption would have an effect on any of the other permit conditions. I'll let you know when I have more information. Toya Toya Fields - toya.f?elds@:cmail.net Environmental Engineer I Western NPDES Program Division of Water Quality Tel: 919-733-5083 x 551 Fax: 919-733-0719 2 of 2 10/10/2007 1 21 PM Progress Energy LeToya Fields NC Division of Water Quality 1617 Mail Service Center Raleigh, NC 27699-1617 File: 12520 B-1 J U L i 1 2007 J U L 0 6 2007 f Subject: Carolina Power & Light Company d/b/a Progress Energy Carolina, Inc. Mayo Electric Generating Plant NPDES Permit No NCO038377 Comments on Draft NPDES Permit Dear Toya: Enclosed are our comments on the subject draft NPDES permit sent to us by your letter of June 6, 2007. We appreciate the opportunity to comment. If you have any questions please contact Steve Cahoon at (919) 546-7457. 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, Z" E . lam Larry E. Hatcher Plant Manager Mayo Electric Generating Plant Progress Energy Carolinas, Inc Mayo Steam Plant 10660 Boston Road Roxboro NC 27574 Mayo Electric Generating Plant Draft NPDES Permit Comments • Sampling Frequencies r J U L 1 1 2007 9 ,u 4 It is our understanding that the draft permit requires twice monthly monitoring (with no limit) for the parameters referenced by Note 2 until 24 months after the FGD treatment system comes online. After the FGD treatment system has been operational for 24 months then the monitoring frequency for those parameters referenced by Note 2 becomes weekly. Please confirm our understanding. • In -stream monitoring for chlorides has been added at the boundary of the nuxing zone. Additionally it appears that there are limits for chlorides at this boundary. KO'd "& -11 First, Progress Energy requests that the permit be clarified so that the permit cannot be interpreted to have chloride limits at the edge of the mixing zone as this would defeat the purpose of having the same permit limits at the outfall. • A minimum flow limit of 7.3 MGD has been added to Outfall 002. This limit becomes applicable 24 months after the commencement of the FGD system. Consistent with 40 CFR §122 45(f)(1) for water quality based effluent limits, and the Total Maximum Daily Load concept, Progress Energy believes that a mass limitation is more appropriate than a minimum flow requirement for controlling the discharge from outfall 002 Receiving water concentrations are a function of Secondly, Progress Energy requests that this sampling requirement be deleted. 0� ��✓ The mixing zone model developed by Progress Energy and submitted to the DWQ was based on a worst case scenario of high chloride coal and drought conditions in the lake. The drought conditions reflect a modeling constant that is more 1� 'v conservative than a 7Q10 condition The model produced certain end -of -pipe values that reflected the conservative nature of the model. Consistent with the model, it is our viewpoint that if we are meeting the end -of -pipe limit for then be the the the chlorides we will meeting water quality standard at edge of ` mixing zone Furthermore, sampling for sampling sake when the lake is not 0 �� ;�V, approaching drought conditions appears to be excessive. k� r cryo A weekly sampling requirement at the boundary of the mixing zone will be very burdensome on staff resources as well as dangerous if staff must conduct weekly sampling regardless of weather conditions. If sampling is desired to ascertain chloride levels in the lake near the mixing zone boundary then a less onerous sampling spot would be at the boat ramp (shown on the enclosed attachment). Therefore if the in -stream sampling conditions cannot be deleted, Progress Energy requests the location be switched to the one presented above and the sampling be conducted only when the lake conditions approach drought conditions. • A minimum flow limit of 7.3 MGD has been added to Outfall 002. This limit becomes applicable 24 months after the commencement of the FGD system. Consistent with 40 CFR §122 45(f)(1) for water quality based effluent limits, and the Total Maximum Daily Load concept, Progress Energy believes that a mass limitation is more appropriate than a minimum flow requirement for controlling the discharge from outfall 002 Receiving water concentrations are a function of both discharge flow and discharge concentration mixed with the receiving water constant flow. In other words the discharge can have a low concentration with a larger flow and maintain in -stream standards. Also the discharge can have a higher concentration with lower flow and maintain in -stream standards due to G- mixing caused by wind, and gradient diffusion. In order to control both flow and concentration through a permit limit it is recognized that a mass limit based on modeling conditions is the most appropriate. Also a mass limit helps to encourage water conservation and pollution prevention practices. discharge e uirement of 3 MGD Furthermore, in order to meet the minimum requirement 7 r (J� under normal operating conditions the company would be forced to install extra pumping capacity to pump water from the lake, through the plant and back to the lake to satisfy the permit limit. We believe this is unnecessary when the matter can be better controlled by a mass limit. Consequently Progress Energy requests that the minimum flow limit be replaced by mass limits calculated by the concentration limits and the design 7.3 MGD flow Progress Energy recognizes that past discussions with the Division have indicated that a mass limit is not feasible, but we must request that the Division reconsider this position. If the Division cannot remove the minimum flow requirement from the permit then Progress Energy requests a meeting before the permit is issued to discuss the issues and the following permit language: "The flow limit shall only apply when the plant is in operation or the Bioreactor discharge averages greater than 18,000 ppm chloride with the water level in Mayo Lake below the 407 foot level (lake level at which Mayo's Drought Contingency Plan is activated); normal operating conditions for the plant are at lake level 434 feet." • Total Mercury Limitation f ,y„ The limit for Total Mercury is referenced by Note 2 and 4. We interpret the notes to mean we must monitor for mercury twice a month for 12 months after commencement of the FGD system. For this 12 month period there is no limit. After the 12 month period the limit becomes effective and the monitoring frequency increases to weekly. Please confirm our understanding. Total Beryllium Limitation The present concentration limit for Beryllium of 0.0068 µg/L was based on a currently outdated human health criterion. Recent (May 2007) modifications to f the Division's Water Quality Standards present the only criterion for Beryllium 1. as 6.5 pg/L Progress Energy requests that the Division take this opportunity to revise the weekly average limit for Beryllium to 6.5 pg/L. N� N SOW s !,�sh Pond Discharge Approximate Edge of Mixing Zone .. T Mixing Zone Mayo Dock (Proposed Sampling Point) Proposed Sampling Point Approximate Edge of Mixing Zone "' Progress Energy Mayo Dock (Proposed Sampling Point) Approximate Edge of Mixing Zone Mixing Zone Cove Proposed- - - Sampling Point -sem. __ •�... �' _ �^`� •—_ _ ..-��s. __ _' _ ' . 1- r �� Progress Energy Mayo Dock (Proposed Sampling Point) Sample from Dock Progress Energy RE: Your message i. Subject: RE: Your message From: "Cahoon, Steve" <Steve.Cahoon@pgnmail.com> Date: Mon, 25 Jun 2007 14:05:20 -0400 To: "Toya Fields" <toya. fields@ ncmail. net> Toya, Outages are easy to deal with, our concerns are more with operational issues such as trips offline that cause the units to be down for hours or days, the unit offline because of demand, the unit not running at 100% of load. The 7.3 MGD used in the model was a worst case scenario, if the unit is not running at 100%, or the chloride concentration in the coal is not 20000 ppm as described in the model then the plant won't need to discharge 7.3 MGD to meet the concentration limit at the end of the pipe. We'll be pumping water from the lake just to satisfy the limit. We'll go ahead and send you written comments ( by our 30 day clock they are due to you by July 11, 2007) in our comments we'll try and incorporate language that will satisfy both of our needs. If the Division is unable to incorporate these suggestions into the permit then we do request a face to face meeting to discuss the issue before the final permit is issued to the plant. Steve Cahoon Progress Energy Carolinas, Inc. Environmental, Health and Safety Services - POG Vnet 770-7457 Bell (919) 546-7457 steve.cahoon@pgnmail.com -----Original Message ----- From: Toya Fields [mailto:toya.fields@ncmail.net] Sent: Monday, June 25, 2007 1:31 PM To: Cahoon, Steve Subject: Re: Your message Steve, The flow limit was simply based on our understanding that Progress could meet a 7.3 MGD discharge from the ash pond. If that can't happen during outages then the solution may be as simple as a footnote explaining that the limit doesn't apply during outages (of course other limits based on that 7.3 MGD assumption would still apply). The flow issue may be complicated, but if the solution is that simple then we won't need to devote significant staff hours to meeting on that issue. If the solution is not going to be that simple, then perhaps we will need to meet. I need you to give me some idea of what your full concerns are. If a letter won't suffice, then feel free to give me a call. Toya Cahoon, Steve wrote: Toya, We can send the comments in by letter, but we feel we will still need 1 of 2 10/10/2007 1:19 PM RE: Your. message to meet. The flow issue is somewhat complicated and will be better understood if we can meet face to face. I'm not sure we can explain the Iissue well enough in a letter so that DWQ will be able understand the full impact of the flow limit. Let me know when you can schedule a meeting. Steve Cahoon Progress Energy Carolinas, Inc. Environmental, Health and Safety Services - POG Vnet 770-7457 Bell (919) 546-7457 steve.cahoon@pgnmail.com -----Original Message ----- From: Toya Fields [mailto:toya.fields@ncmail.net] Sent: Friday, June 22, 2007 11:05 AM To: Cahoon, Steve Subject: Your message Hi Steve, I got your message yesterday. The easiest thing to do would probably ne for you guys to submit your written comments and we can schedule a meeting if there are still any outstanding concerns. If there is something that you don't want to put in a letter you can give me a call. I'd rather not schedule a meeting unless there is a significant issue to discuss that we can't come to an agreement on. Thanks, Toya Toya Fields - toy- fields@ncmall.net Environmental Engineer I Western NPDES Program Division of Water Quality Tel: 919-733-5083 x 551 Fax: 919-733-0719 2 of 2 10/10/2007 1:19 PM STATE OF NORTH CAROLINA, PERSON COUNTY PRINTER'S AFFIDAVIT Vickie F. Carver, being duly sworn, deposes and says: That she is Office Manager of The Courier -Times, with its principle place of business located in the city of Roxboro, County of Person, State of North Carolina; that the foregoing or attached newspaper notice was published in The Courier -Times, once a week for I successive weeks, beginning with its issue of 9hay of l"k, 20 � , and ending with its issue of4_ day of r '20 y I ; that The Courier -Times, is the sole owner and publisher of said newspaper, The C ourier-T 1 Affiant) Sworn to and subscribed before me, r this the day of 20�� ki (Notary Public) My commission expires them day of�..,ll�' f N�i20� (Publication Fee $ t n (Notarial Seal) PUBLIC NOTICE STATE OF NORTH CAROLINA ENVIRONMENTAL MANAGEMENT COMMISSION/NPDES UNIT 1617 MAIL SERVICE CENTER RALEIGH, NC 27699-1617 NOTIFICATION OF INTENT TO ISSUE A NPDES WASTEWATER PERMIT On the basis of thorough staff review and application of NC General Statute 143.21. Public law 92.500 and other lawful standards and regulations, the North Carolina Environmental Management Commission proposes to issue a National Pollutant Discharge Elimination System (NPDES) wastewater discharge permit to the person(s) listed below effective 45 days from the publish date of this notice. Written comments regarding the Proposed permit will be accepted until 30 days after the publish date of this notice. All comments received priorto that date are considered in the final determinations regarding the proposed permit. The Director of the NC Division of Water Quality may decide to hold a public meeting forthe proposed permit should the Division receive a significant degree of public interest. Copies of.the draft permit and other supporting information on file used to determine conditions present in the draft permit are available upon request and payment of the costs of reproduction. Mail comments and/or requests for information to the NC Division of Water Quality at the above address or call Ms. Frances Candelaria at (919) 733-5083. extension 520 at the Point Source Branch. Please include the NPDES permit number in any communication. Interested persons may also visit the Division of Water Quality at 512 N. Salisbury Street. Raleigh, NC 27604- 1148 between the hours of 8:00 a.m. and 5:00 p.m. to review information on file. Progress Energy, 10660 Boston Road, Roxboro, NC 27344 has applied for a modificiation of its NPDES discharge permit for Mayo Electric Generating Plant (number NC0038377). discharging to the Mayo Reservoir in the Roanoke River Basin.This modification would allow a mixing zone for chlorides in Mayo Lake. This facility operates two outfalls, 001 (recrculated cooling water), and 002 (low volume waste, ash sluice water, cooling tower blowdown, coal pile runoff, FGD blowdown, etc). Currently total selenium, oil and rease, and TSS are water quaility limited. This discharge may affect future allocations in this portion of the Roanoke River Basin. June 9 7 Mayo-long3.mdb Salinity, ppt 07130!: N Salinity, ppt 1.00 0.23 0.00 Maximum Length = 120 meters Surface Area = 18900 square meters Bottom Area = 13400 square meters Volume = 36320 cubic: meters 500 m Progress Energy Mayo-long3_mdb Salinity, ppt 08/19/2002 00:01 Salinity Maximum Length = 180 met( Surface Area = 21400 squar Bottom Area =15820 square Volume = 43800 cubic mete N A 500 m Progress Energy tf' Start 11 CORMIX-GI << 41 A 4;16 PM ERM Surfacewater Modeling Group A F. s T, F.- 3 Grace Lake, Michigan 3-D Thermal Discharge Modeling Services Include: Study Design and Field Program Layout Model Development and Application NPDES Permit Applications Public Presentations and Testimony Software Development (FORTRAN, VB, ArcGIS) Training for GEMSS and CE -QUAL -W2 1953. 185.3 0 d 175.3 1Z 1653 Temperature (C) August 1977 0 20000 45000 70000 9500G Dist¢w .1—g the slice, -meters CE -QUAL -W2 Model Application to Lake Mohave, CA ERM's Surfacewater Modeling Group (SMG) is an internationally -recognized group of surface water professionals supporting clients since 1976. 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P oiect t__— _. t 0— E.— Wrnp..Wre E.—Wrnp..9ue &g F Lon9itud aI Slcx � It pe,a) Et o)o J:r 70 n]I.. OSNBN] W 06/l Tem eraturc F Dr1e (mw+M) -e -s-' GEMSS Output Data Visualizer GEMSS itself is a graphical user interface that supports these modules and provides additional capabilities, including: Contact: Venkat S. Kolluru at 610-524-3654 • Grid generation Email: Venkat.Kolluru@erm.com • Geographic information systems (GIS) • Field data importing and visualization • Boundary condition data preprocessors '004 • Post -processors for model output visualization • 3-1) Visualizer Coldwater Plume Discharging at Depth Zo ERM consulting services worldwide www.erm.com ERM Generalized Environmental Modeling System for Surface Waters (GEMSS) TECHNICAL DETAILS GEMSS is an integrated system of 3-D hydrodynamic and transport models embedded in a geographic information and environmental data system. GEMSS includes a grid generator and editor, control file generator, 2-D and 3-D post processing viewers, and an animation tool. It uses a database approach to store and access model results. The database approach is also used for field data; as a result, the GEMSS viewers can be used to display model results, field data or both, a capability useful for understanding the behavior of the prototype as well as for calibrating the model. The field data capability can be used independently of the model application. GEMSS was developed in the mid -80s as a hydrodynamic platform for transport and fate modeling. The hydrodynamic platform ("kernel") provides 3-D flow fields from which the distribution of various constituents can be computed. The constituent transport and fate computations are grouped into modules. GEMSS modules include hydrodynamics, water quality, sediment transport, particle tracking, oil and chemical spills (the Chemical / Oil Spill Impact Module, COSIM), entrainment, and toxics. The theoretical basis of the hydrodynamic kernel of GEMSS is the three-dimensional Generalized, Longitudinal -Lateral -Vertical Hydrodynamic and Transport (GLLVHT) model which was first presented in Edinger and Buchak (1980) and subsequently in Edinger and Buchak (1985). The GLLVHT computation has been peer reviewed and published (Edinger and Buchak, 1995; Edinger, et al., 1994 and 1997). The kernel is an extension of the well known longitudinal -vertical transport model written by Buchak and Edinger (1984) that forms the hydrodynamic and transport basis of the Corps of Engineers' water quality model CE -QUAL -W2 (U. S. Army Engineer Waterways Experiment Station, 1986). The constituent modules as well as the GIS interoperability, the visualization tools, the graphical user interface (GUI), and the post -processors have been developed by Kolluru et al. (1998; 1999; 2003a; 2003b). VALIDATION COSIM was recently used during a major U.S. oil spill in Buzzards Bay, Massachusetts. During a Natural Resource Damage Assessment (NRDA) to assess potential impacts resulting from a release of No.6 Fuel Oil from a fuel barge, COSIM was used on behalf of the responsible party in a cooperative assessment with the U.S. National Oceanic and Atmospheric Agency (NOAA). NOAA is one of the world's leading agencies for managing oil spill responses and assessing spill -related impacts. When use of one of NOAA's in-house models, NRDAM/CME, was rejected by NOAA in response to demands for the best state-of-the-art oil spill model be implemented, NOAA agreed to allow SIMAP (by the trustees) and COSIM (by the responsible party) to be run in parallel. Thus the aquatic injury assessment was performed concurrently with COSIM and SIMAP to form a consensus model, facilitating the cooperative process. The model was successfully calibrated to field observations, shoreline oiling was delineated and potential aquatic injuries associated with the oil's dissolved aromatic hydrocarbons in the water column and nearshore were assessed. COSIM results have been verified through comparisons to field observations for use in other major oil spills including a rupture in a river in Maryland and a barge leak off the coast of California. GEMSS and its component modules have met agency approval in the U.S. and Canada many times since 1981. GEMSS-based studies have been accepted by the U.S. Environmental Protection Agency (EPA), several U.S. state agencies including California, Massachusetts, Pennsylvania, Louisiana, Texas and Delaware. Washington State's Department of Ecology has adopted GEMSS as their standard tool for estuarine and water quality modeling. Most recently GEMSS has been published as a recommended three-dimensional hydrodynamic and water quality model in studies funded by EPA (HGL and Aqua Terra, 1999) and by the Water Environment Research Foundation (Water Environment Federation, 2001). It is the sole hydrodynamic model listed in its WERF model selection tool database for hydrodynamic and chemical fate models that can do 1-D, 2-D, and 3-D time -variable modeling for most waterbody types, all state variables, for J near field and far field simulations, with GUIs, grid generation, GIS linkage, and strong documentation. Outside the U.S., GEMSS and its various software modules have been approved by many regulatory agencies as well. Studies conducted using the hydrodynamic (GEMSS-HDM) and thermal analysis (GEMSS-TAM) modules were approved by the regulatory agency in the State of Bahamas. Similar studies using the same modules were also approved by the regulatory agency in the State of Qatar. Spill impact studies conducted using the COSIM module of GEMSS were also approved by the regulatory agency in the State of Qatar. Studies conducted using the water quality (GEMSS-WQM) module of GEMSS was approved by the overseeing regulatory agency in India. GEMSS-HDM and GEMSS-WQM modules were recently applied to study the hydrodynamic mixing and water quality of the confluence of the Nottawasaga River with Nottawasaga Bay in Ontario, Canada. The model results were accepted by the Lake Simcoe Region Conservation Authority of Ontario, Canada. Buchak, E. M. and J. E. Edinger. 1984. Generalized, Longitudinal -Vertical Hydrodynamics and Transport: Development, Programming and Applications. Prepared for U.S. Army Corps of Engineers Waterways Experiment Station, Vicksburg, Miss. Contract No. DACW39-84-M-1636. Prepared by J. E. Edinger Associates Wayne, PA. Document No. 84-18-R. June. Edinger J.E., J. Wu and E.M. Buchak. 1997. Hydrodynamic and Hydrothermal Analyses of the Once -through Cooling Water System at Hudson Generating Station. Prepared for Public Service Electric and Gas (PSE&G). Prepared by J. E. Edinger Associates, Inc., June 1997. Edinger, J. E. and E. M. Buchak. 1980. Numerical Hydrodynamics of Estuaries in Estuarine and Wetland Processes with Emphasis on Modeling, (P. Hamilton and K. B. Macdonald, eds.). Plenum Press, New York, New York, pp. 115-146. Edinger, J. E. and E. M. Buchak. 1995. Numerical Intermediate and Far Field Dilution Modelling. Journal Water, Air and Soil Pollution 83: 147-160,1995. Kluwer Academic Publishers, The Netherlands. Edinger, J. E., and E. M. Buchak. 1985. Numerical Waterbody Dynamics and Small Computers. Proceedings of ASCE 1985 Hydraulic Division Specialty Conference on Hydraulics and Hydrology in the Small Computer Age. American Society of Civil Engineers, Lake Buena Vista, FL. Aug. 13- 16. Edinger, J. E., E. M. Buchak, and M. D. McGurk. 1994. Analyzing Larval Distributions Using Hydrodynamic and Transport Modelling. Estuarine and Coastal Modeling III. American Society of Civil Engineers, New York. HGL and Aqua Terra. 1999. Selection of Water Quality Components for Eutrophication-Related Total Maximum Daily Load Assessments. Task 4: Documentation of Review and Evaluation of Eutrophication Models and Components EPA Contract Number 68-C6-0020 Work Assignment No. 2-04. Prepared by HydroGeoLogic, Inc. Herndon, VA 20170 and AQUA TERRA Consultants, Mountain View, CA. June. Kolluru, V. S., E. M. Buchak and J. E. Edinger, 1998. "Integrated Model to Simulate the Transport and Fate of Mine Tailings in Deep Waters," in the Proceedings of the Tailings and Mine Waste'98 Conference, Fort Collins, Colorado, USA, January 26-29. Kolluru, V. S., E. M. Buchak, J. Wu, 1999. "Use of Membrane Boundaries to Simulate Fixed and Floating Structures in GLLVHT." In Spaulding, M.L, H.L. Butler (eds.). Proceedings of the 6th International Conference on Estuarine and Coastal Modeling. pp. 485 — 500. Kolluru, V. S., J. E. Edinger, E. M. Buchak and P. Brinkmann 2003. "Hydrodynamic Modeling of Coastal LNG Cooling Water Discharge." Journal of Energy Engineering. Vol. 129, No. 1, April 1, 2003. pp 16 — 31. Kolluru, V.S. and Mike Fichera, 2003. "Development and Application of Combined 1-D and 3-D Modeling System for TMDL Studies." Proceedings of the Eighth International Conference on Estuarine and Coastal Modeling. American Society of Civil Engineers. pp. 108-127, 2003. U. S. Army Engineer Waterways Experiment Station, Environmental Laboratory, Hydraulics Laboratory. 1986. CE-QUAL-W2: A Numerical Two -Dimensional, Laterally Averaged Model of Hydrodynamics and Water Quality; User's Manual. Instruction Report E-86-5. Prepared for Department of the Army, U.S. Army Corps of Engineers, Washington, DC. Final Report. August. Water Environment Federation. 2001. Water Quality Models: A Survey and Assessment. Order No.: D13209WW (Electronic Media). A Cross Section, Vertical Slice through the cove across the entire Mayo Reservoir (West to East) Database: Mayo7010-73.mdb Slice: Slice 1 Date 07/30/2002 00-01 Conc. of Salinity ppt 1 8 It 1.30 �+1.0 16 } 0,6 0 Z 2t OA a 0.3 0.23 a 26 0.2 01 005 1 31 0.00 36 41 13 18 23 28 33 38 43 48 53 7 Index Along the Slice in East Direction Database: Mayo7010-549.mdb Slice: Slice 1 Date: 07/30/2002 00:01 Conc. of salinity ppt 1 6 n N 1.30 1.0 0.8 16 0.6 21 0.4 7.z 0.3 0 3 02 2fi 0.1 a 0.05 31 0.00 36 41 13 1a 23 28 33 3B 43 48 53 I Index Along the Slice in East Direction Database- Maya 7010-349.mdb Slice: Slice 1 Date: 07/30j2002 0001 Conc. of Salinity ppt 1 6 tt 01 30 LO'Q 21 0.4 0.3 0.23 0126- 0.2 ZI 0.05 37 0.00 35- 41: 13 18 23 2B 33 38 43 48 53 1 Index Along the Slice in East Direction Same cross sections as above, but zoomed into the first 900 meters Database: Meyo7O1B-73.mdb Slice: Slice1 Date: 07/30/2002 00:01 Database: Mayo7C!10-549.mdb Slice: Slice 1 Date: 07/30/2002 00:01 Core. of Salinity ppt 132.89 129.72 126-55- Mi 1.30 10 127.36 11.30 08 .8 0-6 w 120.21 0.4 0.3 023 Q 117.04 0.2 0.11 0.05 113.87: 0.00 110-7- 10 7107.53 107-534 0 375.3 750.6 Distance, m Database: Mayo7C!10-549.mdb Slice: Slice 1 Date: 07/30/2002 00:01 Database: Mayo7O10-349.mdb Slice: Slice 1 Date: 07/30/2002 00:01 Conc. of Salinity ppt 132.89 129.7? 126.55 1.30 10 123.38 0.6 0.6 120.21 0.4 0.3 023 Q 117.04 ' 0.2 01.1 0.05 11397 0.00 110.7- 107,531 0 375.3 750.fi Distance, m Database: Mayo7O10-349.mdb Slice: Slice 1 Date: 07/30/2002 00:01 Com. of Salinity ppt 13299 129.72 126.55 1.30 1.0 123.38 0.8 0.6 'r 120.21 0.4 0.3 023 Q 117.04 0.2 0.11 0.05 113.87 0'00 1107 107.53 0 375.3 750.6 Distance. m .40 Y V7 7 Ash Pond & Bioreactor Discharge -'U--I t qb • 4r Mayo Lake Mayo Steam Generating Plant NCO0038377 "4 L Progress Energy Mayo Steam Generating Plant Progress Energy NC00038377 Mayo Steam Generating Plant Progress pro Ener NC00038377 g 9V Calculated monthly averages - ash pond flows Permit -- - NC0038377 Facility ----------------------------------------------------- --- - ---- Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant Outfall - - - - 002 Date - ' -- Jan -04 Param Class Sample - -- -- ---- Flow Recorder UoM ---- mgd Value - -- - ------------- 6.72 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 Feb -04 Flow Recorder mgd 8.13 N00038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 Mar -04 Flow Recorder mgd 7.11 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 Apr -04 Flow Recorder mgd 6.51 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 May -04 Flow Recorder mgd 6.32 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 Jun -04 Flow Recorder mgd 5.90 NC0038377 ------ N00038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant -------------------------- --- ---- ----- ------------ -------------- ----------- Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 ------- 002 Jul -04 -- Aug -04 Flow ------ Flow Recorder ------ Recorder mgd ------ mgd 7.12 - ------- 8.14 N00038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 Sep -04 Flow Recorder mgd 8.01 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 Oct -04 Flow Recorder mgd 5.91 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 Nov -04 Flow Recorder mgd 7.01 N00038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 Dec -04 Flow Recorder mgd 7.11 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 Jan -05 Flow Recorder mgd 7.40 NC0038377 - ------------------- NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant --------------------------------------------- - ' - - ------------ ---------- Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 - --- ------------------------------------------------ 002 Feb -05 Mar -05 Flow I Flow Recorder --------------- Recorder mgd ---------------- mgd 7.30 ---------- -----------------------------------------.. 8.03 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 Apr -05 Flow Recorder mgd 6.31 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 May -06 Flow Recorder mgd 5.91 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 Jun -05 Flow Recorder mgd 6.41 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 Jul -05 Flow Recorder mgd 6.11 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 Aug -05 Flow Recorder mgd 6.15 NC0038377 -- NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant -------------------------------------------------------------------------------------- Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 ----- 002 Sep -05 --------------------- Oct -05 Flow ------ Flow Recorder ----- ---- Recorder mgd -------- mgd 5.70 -- - - --- 7.11 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 Nov -05 Flow Recorder mgd 7.69 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 Dec -05 Flow Recorder mgd 7.88 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 Jan -06 Flow Recorder mgd 7.11 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 Feb -06 Flow Recorder I mgd 6.62 NCo038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 Mar -06 Flow Recorder mgd 4.15 NC0038377 --------------- NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant ------- - -- -- -- - - - - - -------------- ------------ Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 ----------- 002 Apr -06 ----------- May -06 Flow ----------------- Flow Recorder --------------- Recorder mgd ------------- mgd 6.22 - - - - - - - - 5.70 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 Jun -06 Flow Recorder mgd 5.66 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 Jul -06 I Flow Recorder mgd 8.80 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 Aug -06 Flow Recorder mgd 5.66 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 Sep -06 Flow Recorder mgd 7.96 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 Oct -06 Flow Recorder mgd 6.96 NC0038377 ----------------- NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant ---- ------ - - - -- ---' - - -- - -- --- ---- ---- ----- Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 - 002 Nov -06 ---- Dec -06 Flow ------------ Flow Recorder - -- - Recorder mgd - - mgd 6.80 -- ----------------------------- - 6.12 Average 6.77 Median 6.76 Max 8.80, Min 4.15 Percentiles 95th i 8.13 stn r 5.66 99th i 8.57 1 st i 4.68 Re Red 'dei ' flows from ash pond (weekly mon@orin r wired Penni Facility Outfall Date Param Cie. Sample 1JoM Value 1400038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 1/8/2004 Flow Recorder mgd 6.33 NC0039377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 1/16/2004 Flow Recorder mgd 6.33 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 1/19/2004 Flow Recorder mgd 7.11 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electro Power Plant 002 129/2004 Flow Recorder mgtl 7.11 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 2/3x2004 iFlow Recorder mgd 9.63 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Elecac Power Plant 002 2/112004 Flow Recorder mgd 7.88 NC0038377 I Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 2/19/2004 Fbw Recorder mgd 7.11 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electrc.Powsr Plant 002 224/2004 Flow Recorder mgd 7.88 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 3x2/2004 Flow Record. mgd 7.88 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 &12/2004 Flow- Record. mgd 6.33 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 &11/2004 Flow Recorder mgd 7.88 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 3262004 Flow Recordw mgd 7.11 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electro Power Plant 002 lW3Ot2OO4 Flow Recorder mgd 6.33 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electro Power Plant 002 4/6/2004 Flow Recorder mgd 5.49 NC0038377 Progreso Energy Carolinas Inc - Mayo Steam Electric Pows, Plant 002 4/15x2004 Flow Record. mgd 7.88 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 4/20/2004 Flow Record. mgtl 6.33 1400038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 4/30/2004 Flow Record. mgd 6.33 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 5/3/2004 Flow- Recorder mgd 8.79 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Elactric Power Plant 002 5x122004 Flow Recorder jm9d 5.49 NC0038377 Progreso Energy Carolinas Inc - Mayo Steam Electro Power Plant 002 5/18/2004 IFIw Record. mgd 5.49 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 5/25/2004 Flow Record. mgd 5.49 NC0039377 Progress Energy Carolinas Inc - Mayo Steam Electro Power Plant 002 6/12004 Flow Recorder mgd 7.11 NC0038377 Progress Energy Carolinas Inc - May. Steam Electro Power Plant 002 6x10/2004 Flow- Record. mgd 6.33 NC0038377 Progress Energy Gamines Inc - Mayo Steam Electric Power Plant 002 8/15/2004 Flow- Recorder mgd 6.33 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 8/23/2004 Flow Recordw mgd 4.65 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 8x292004 Fbw Record. mgd 5.10 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 7/8/2004 Fbw Recordw mgd 5.49 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 7/14/2004 Flow Record. mgtl 5.94 14C0035377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 7/192004 Flow Recorder lmgd 7.88 NC0038377 Progress Energy Carolinas Inc - Mayo Steam EMetric Power Plant 002 728/2004 Flow- Recorder mgtl 9.17 NC0038377 Progrese Energy Carolinas Inc - Mayo Steam Electro Power Plant 002 8/3/2004 Flow Recorder mgd 7.11 NC0039377 Progrees Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 8/12/2004 Flow Record. mgd 7.89 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 811612004 Flow Recorder mgd 10.47 NC0038377 Progress Enwgy Carolinas Inc - Mayo Steam Electro Poww Plant 002 825x2004 Flow Record. mgd 7.11 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electro Power Plant 002 9/2/2004 Fbw Recorder mgtl 9.17 NC0039377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 9/72004 lFbw Record. mgd 7.11 NC0039377 Progress Energy Carolinas Inc - Mayo Steam Electro Power Plant 002 9/15/2004 Flow Recorder mgd 7.88 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 9/212004 Fbw Record. mgd 8.79 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electro Power Plant 002 9292004 Flow- Record. mgd 7.11 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 10/5x2004 Flow Recorder mgd 6.33 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 10/13/2004 Flow Recorder mgd 4.65 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 10/192004 Flow Record. mgtl 6.33 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electro Pows, Plant 002 101282004 Flow Recorder mgtl 6.33 NC0039377 Progress Energy Carolinas Inc - Mayo Steam Electro Power Plant 002 11/12004 Flow Recorder mgd 7.11 NC0038377 Progreas Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 11/9/2004 Flow Recorder mgd 6.33 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electro Power Plant 002 11/162004 Flow Record. mgd 7.11 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Elactric Power Plant 002 11232004 Flow Record. mgd 7.49 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 12/12004 Fbw Recorder mgd 7.11 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electro Power Plant 002 1277/2004 Flow Record. mgd 7.89 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electro Power Plant 002 12/15/2004 Flow Recorder mgd 7.11 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 12212004 Flow Record. mgd 6.33 NC0038377 Progress Energy Carolinas Inc - Maya Steam Electric Power Plant 002 12/30/2004 Flow Record. mgd 7.11 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 1/4/2005 Fbw Recorder mgtl 7.88 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electro Power Plant 002 1/12/2005 Fbw Recorder mgd 7.49 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 1/18/2005 Flow Record. mgd 7.11 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electro Power Plant 002 126x2005 Fbw Recorder mgd 7.11 NC00383n Progreas Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 2/12005 Flow Recorder mgd 7.49 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electro Poww Plant 002 2/82005 Flow Recorder mgd 7.11 NC0038377 Progress Energy Carolinas Inc - Maya Steam Elacifb Power Plant 002 2/15/2005 Flow Recordw mgtl 7.49 NC0038377 Pmgress Energy Carolinas Inc - Mayo Steam Electric Poww Plant 002 2212005 Flow Record. mgtl 7.11 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 3112005 Flow Record. mgtl 8.79 1400038377 Pmgreu Energy Carolinas Inc - Mayo Steam Electric Poww Plant 002 3/8/2005 Flow Recorder mgd 7.48 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electro Power Plant 002 3/152005 Flow Recorder mgtl 7.11 1400038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 322/2005 Flow Record. mgd 7.11 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 3/292005 Flow Recorder mgtl 9.63 NC0038377 Progress Energy Carolinas Ino - Mayo Steam Electric Power Plant 002 4/12005 Flow Recorder mgd 7.88 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002S Flow Record. mgd 7.11 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 4/122005 Flow Recorder mgd 6.33 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 4/19/2005 Flow Recorder mgd 6.72 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Powe, Plant 002 420121105 Fbw Record. mgd 3.49 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 5/3x2005 Fbw Recorder mgd 6.33 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 5/10/2005 Flow Recorder mgtl 4.65 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 5/16/2005 Flow Recorder mgd 6.33 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 5/242005 Flow Recorder mgd 6.33 NC0038377 Progreaa Energy Carolinas Inc - Mayo Steam Electro Power Plant 002 6/12005 Flow Record. mgd 6.33 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electro Power Plant 002 6/8/2005 Flow Recorder mgd 6.33 NC0039377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 61142005 Flow Record. mgd 7.11 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 8x202005 Flow Recorder mgd 6.33 NCDO38377 Progress Energy Carolinas Inc - Mayo Steam Electrc Power Plant 002 6/272005 Flow Record. mgd 5.94 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 7/5/2005 Flow Recorder mgd 7.11 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Poww Plant 002 7/132005 Flow lRecord. mgd 6.33 NG0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 7/18/2005 Flow Record. jmgd 5.49 NC0038377 Pmgress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 7272005 Flow Recorder mgtl 5.49 NC0038377 I Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 8x2/2005 Fbw Recorder mgtl 7.11 NC0038377 I Progress Energy Carolinas Inc - Mayo Steam Electric Pcww Plant 1002 8/9/2005 Flow Recorder jmgd 6.33 NC0039377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 6/15/2005 Flow Recorder mgd 5.48 NCO038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 8/24/2005 Flow Recorder mgd 6.33 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 8/312005 Flout Recorder mgd 5.49 NC0038377 Progress Energy Camlinas Inc - Mayo Steam Electric Power Plant 002 WWW5 Flow Recorder mgd 5.49 NCO038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 9/14/2005 Flow Recorder mgd 5.49 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Elecirc Power Plant 002 9/19/2005 Flow Recorder mgd 5.49 N00038377 Progress Energy Carolinas Inc - Mayo Steam Electro Power Plant 002 9/27/2005 Flow Recorder mgtl 6.33 KC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 10/4/2005 IFIlev Recorder lmgd 6.33 NCO038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 10/13/2005 Flow Recorder mgd 7.88 NCO038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 10/18/2005 Flow Record. mgd 7.11 NCO038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 10/27/2005 Flow Recorder mgd 7.11 NCO038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 11/1/2005 Flow Recorder mgd 7.11 NCO038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 1192005 Flow- Recorder mgd 7.11 NCO039377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 11/152005 Flow Recorder mgd 6.33 NCO039377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 1122/2005 Flow Recorder mgd 10.01 NC003S377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 11292005 Flow Record. mgd 7.88 N00038377 Progress Energy Carolinas Inc - Mayo Steam Electro Power Plant 002 12/8/2005 Flow Record. mgd 11.76 NCO038377 Progress Energy Carolinas Inc - Mayo Steam Electro Pow. Plant 002 12/142005 Flow Record. mgtl 6.33 NCO038377 Progress Energy Carolinas Inc - Mayo Steam Electric Pow. Plant 002 12202005 Flow Recorder mgd 7.11 NCO038377 Progress Energy Carolinas Inc - Mayo Steam Electro Power Plant 002 1228/2005 Flow Recorder mgd 6.33 NCO038377 Programs Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 IIWOO6 Flow Recorder mgd 7.88 NCO038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 1/122008 Flow Recorder mgd 7.88 NCO038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 1/172006 Flow Recorder mgd 7.11 NCO038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 1282006 Flow Recorder mgd 6.33 NCO039377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 1/312006 Flow Record. mgtl 6.33 NCO039377 Progress Energy Carolinas Inc - Mayo Steam Electro Power Plant 002 2/72006 Flow Record. mgtl 6.33 NCO039377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 2/152006 Flow Record. mgd 6.33 NCO039377 Progress Energy Carolinas Inc - Mayo Steam Electro Power Plant 002 2232006 Flow Record. mgd 7.11 NCO039377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 2282006 Flow Recorder mgd 6.72 NC0039377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 3/6/2006 Flow Recorder mgd 1.91 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 392006 Flow Recorder mgd 2.38 NCO038377 Progress Energy Carolinas Inc - Mayo Steam Electro Pcww Plant 002 3/18/2006 Flow Recorder mgd 5.49 NCO039377 Progress Energy Carolinas Inc - Mayo Steam Electro Power Plant 002 3/212008 Flow Record. mgtl 4.65 NCO038377 Progress Energy Carolinas Inc - Mayo Steam Electro Power Plant 002 3902006 Flow Recorder lmgd 6.33 r4com377 Progress Energy CaroAnas Inc - Mayo Steam Electric Power Plant 002 4/42006 Flow Record. mgtl 7.11 NCO038377 Progress Energy Carolinas Inc - Mayo Steam Electro Power Plant 002 4/122006 Flow Recorder mgd 5.94 NCO038377 Progress Energy Carolinas Inc - Mayo Steam Electro Power Plant 002 4/18/2006 Flow Record. mgd 5.49 NCO038377 Progress Energy Carolinas Inc - Maya Steam Electric Power Plant 002 426/2008 IFIDW Record. mgd 6.33 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electro Power Plant 002 5/32006 Flow Record. mgd 5.49 NCO038377 Progress Energy Carolinas Inc - Mayo Steam Electro Power Plant 002 5/70/2006 Flow Record. mgtl 6.33 NCO038377 Progress Energy Carolinas Inc - Mayo Steam Electro Power Plant 002 5/16/2006 Flow Record. mgtl 6.33 NCO038377 Progress Energy CaroAnas Inc - Mayo Steam Electro Power Plant 002 5/23/2006 Flow Recorder mgd 4.65 NCO038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 82/2006 Flow Record. mgtl 5.49 NCO038377 Progress Energy Card Inc - Mayo Steam Electric Pow. Plant 002 8/6/2006 Flow Record. mgtl 4.65 NC0038377 Progress Energy Cana Inc - Mayo Steam Electric Power Plant 002 8/142006 Flow Record. mgd 6.33 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 6202006 Flow Recorder mgd 5.49 NCD038377 Progress Energy Carolinas Inc - Mayo Steam Electric Pow. Plant 002 628/2008 Flow Record. mgd 6.33 NC0039377 Progress Energy Carolinas Inc - Mayo Steam Electro Power Plant 002 7/82008 Flow Recorder mgd 17.12 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electro Power Plant 002 7/102006 Flow Record. mgd 7.11 NCO038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 7/19/2006 Flow Recorder mgd 5.49 NCO038377 Progress Energy Carolinas Inc - Mayo Steam Electro Power Plant 002 725/2008 Flow Recorder 5.49 NCO038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 8/42008 Flow Recorder 5.49 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 8/8/2006 Fbw Recorder 5.49 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electro Power Plant 002 8/16/2006 Fbw Recorder Vmgd 5.49 NCO038377 Progress Energy Carolinas Inc - Mayo Steam Electro Power Plant 002 8/22/2006 Fbw Record. 5A9 NCG038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 8/302006 Fbw Record. 6.33 NCO038377 Progress Energy Carolinas Inc - Mayo Steam Electro Power Plant 002 9/7/2006 Fbw Recorder 6.33 NCO038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 9/142006 Flow Recorder mgd 11.31 NCO038377 jProgress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 9212006 Flow Record. 1.9d 6.33 NC0038377 Progress Energy Carolnes Inc - Mayo Steam Electric Power Plant 002 926/2006 Flow Record. mgd 7.88 NCO038377 Progress Energy Carolinas Inc - Mayo Steam Electro Power Plant 002 1032006 Flow Recorder mgd 7.88 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electro Power Plant 002 10102006 Flow Recorder mgd 8.79 NC0038377 Progress Energy Carolinas Inc - Mayo Steam Electro Power Plant 002 10172006 jFbW Recorder mgd 6.33 NC0038377 Progress Energy Carolinas Inc - Mayo Staam Electric Power Plant 002 10282006 Flow Record. mgtl 6.33 NCO039377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 10312006 Flow Recorder mgd 5.49 NC003B377 Progress Energy Carolinas Inc - Mayo Steam Electro Power Plant 002 11/72006 Flow Recorder mgd 5.49 NCO038377 Progress Energy Carolinas Inc - Mayo Steam Electro Paw. Plant 002 11/14/2006 Flow Recorder mgd 7.49 NCO038377 Progress Energy Carolinas Inc - Mayo Steam Electric Pow. Plant 002 11212006 Flow Record. mgd 7.11 NCO038377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 11/302006 Flow Recorder mgd 7.71 NC0038377 Progress Energy Carolinas Inc- Mayo Steam Electric Power Plant 002 12/72006 Fbw Recorder mgd 6.33 NCO038377 Progress Energy Carolinas Inc- Mayo Steam Electro PowerPlant 002 12/14/2006 Flow Recorder mgd 6.33 NCO038377 Progress Energy Carolinas Inc - Mayo Steam Electro Power Plant 002 12/21/2006 Flow Recorder mgd 5.49 1,100035377 Progress Energy Carolinas Inc - Mayo Steam Electric Power Plant 002 1229/2006 Flow Recorder mgtl 6.33 Average, 6,75 Median 6.33 Maximum 17.12 Minimum 1.91 Percentiles 95th x 1 9.17 4,65 991h % 11.50 1. x 3.02 �� V'Or � Progress Energy LeToya D. Fields NC Division of Water Quality 1617 Mail Service Center Raleigh, NC 27699-1617 MAR 2 1 2107 2007 Subject: Carolina Power & Light Company d/b/a Progress Energy Carolina, Inc. Mayo Electric Generating Plant NPDES Permit No. NCO038377 Mixing Zone Submittal — Response to Request for Additional Information Dear Toya: Progress Energy Carolinas, Inc. is in receipt of your request for additional information dated March 6, 2007, regarding the Mayo mixing zone submittal. We would like to schedule a meeting with the appropriate Division staff to discuss the mixing zone submittal, particularly Item 1 below, before the final end of pipe limit for the mixing zone is established. Please contact Mr. Steve Cahoon, at (919) 546-7457, to schedule the meeting. The following items are provided to address your request for additional information. • The submittal states that the ash pond flow rate used for the model was 7.3 MGD. How was this estimate determined? What is the range of discharge rates that might be expected from the ash pond? Response: The average discharge estimate of 7.3 MGD was provided by reviewing long term data from past NPDES permit applications. The mixing zone is dependent upon two factors, in stream flow of the reservoir and the ash pond discharge. In order to reduce model variability we maintained one of the variables constant (ash pond discharge @ 7.3 MGD) which maintained the mixing zone to a small size, but requires the use of mass based limits to account for the variation in flow from the ash pond. We felt this would be the best option for regulatory approval of a mixing zone because it greatly reduced the size of the mixing zone with an end of pipe concentration of 672 ppm. Modeling low flow conditions in the reservoir and low flow conditions of the ash pond (3.49 MGD monthly average for the ash pond) results in an end of pipe concentration of 1353.7 ppm, and more than doubles the size of the requested mixing zone for chlorides. Internally, we felt representing the mixing zone in this manner would be more acceptable to the Division along with the mass based limit to account for the variability of flow in the ash pond discharge. However, if Division policy requires concentration based limits for the chloride mixing zone, we request the Division consider the additional information provided with this Progress Energy Carolinas, Inc. Mayo Steam Plant 10660 Boston Road Roxboro, NC 27574 MAR 21 2007 submittal which describes the low flow conditions in both the ash pond and the reservoir and predicts an end of pipe concentration of 1353.7 ppm at these low flow conditions. The Division would then develop an end of pipe concentration limit for the mixing zone based on the low flow conditions in both the ash pond and reservoir; which will yield a larger mixing zone in the lake to accommodate the variation in the ash pond discharge. The monthly average variation in the ash pond discharge over the last two years ranges from 3.49 MGD to 17.12 MGD. • The document characterizes the discharge plume during low flow conditions. Please include a similar characterization for periods of "normal " and "high " flows. What size plume might be expected to exceed water quality standards during those conditions? If possible, please provide graphics similar to Figure 2 to characterize the plume during these conditions. Response: Please see Attachment 1, which includes a characterization of flows for "low" "normal" and "high flows. • In September 2006, Progress Energy was able to provide salinity surface contours for the entire reservoir (similar to Figure 9) depicting concentrations in increments of 0.2 ppt. If possible, please provide similar representative graphics for "low", "normal", and "high" periods of flow. Response: Please see Attachment 2, which provides salinity surface contours for low, normal and high flows. These graphics were depicted in 0.01 ppt for your convenience. • Please verify that Progress Energy is only requesting a mixing zone for chlorides. Response: At this time Progress Energy is only seeking a mixing zone for chlorides. At some point in time there may be a need to request additional mixing zones for other parameters based on the actual performance of the bioreactor. In our response to the Mayo Draft NPDES permit dated, February 26, 2007, our response indicated a need for a compliance period for several parameters, in part that compliance period would allow for time to assess the performance of the bioreactor and allow us to petition the Division for mixing zones for additional parameters if needed. • Please provide a map indicating the location of the dam discharge (to the creek). Response: Please see Attachment 3 for the map. Enclosed with this submittal is a check for $860.00 for a major permit modification associated with the mixing zone request. If you have any questions relating to this submittal please contact Steve Cahoon. MAR 2 12007 1 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, J c W-�-- Larry E. Hatcher Plant Manager Mayo Electric Generating Plant Attachment 1 Mayo Reservoir simulation from 2001 to 2003 uses the outflow from the dam as observed at USGS gage #02077670 shown below. Average flow rate for that station is 40 cfs. In the simulation, the scrubber discharges a constant 0.253 mgd at 20,000 ppm of chloride. The Ash Pond recirculates a constant 7.3 mgd at 2 ppm of chloride. 1000 :11 600 V 3 O LL 400 200 [I] Mayo Creek d/s of Dam USGS #02077670 High Flow 945 cfs 4/11/03 Normal Flow 40 cfs 2/07/03 Low Flow 3.5 cfs 8/19/02 1/1/00 5/31 /00 10/29/00 3/29/01 8/27/01 1/25/02 6/25/02 11/23102 4/23/03 Date Attachment 1 Page 1 Low Flow Condition - August 19, 2002 — ---- Mayo-long3-mdb Salinity. pt OBASnOO2 00:01 Mayo-long3.mdb Salinity, ppt 08/19/2002 00:01 Attachment 1 Page 2 Normal Flow Condition - February 7, 2003 Mayo-longlmdb Salinity. ppt 02/07/2003 00:01 Mayo-long3_mdb Salinity. ppt 02/07/2003 00:01 Attachment 1 Page 3 High Flow Condition - April 10, 2003 Mayo-long3.mdb Salinity. ppt 04/10/2003 00:00 Mayo-long3_mdb Salinity. ppt 04/10/2003 00:00 Attachment 1 Page 4 Attachment 2 Attachment 2: Mixing Zone depictions of the combined ash pond and FGD blowdown based on GEMSS modeling results during low, normal, and high reservoir flows. Osefearge Cove \ 100. i50m f f t ! 400 mg.L '_ , - t t , 325 mgL C! 0 Low Flow 3o mgL CI - r -130, 130, t 80m t00m � ZOOrr'r Of t r ! f Discharge Myo Lake overview f 400 mgL cr - ! Cove ! 325 mgt- Cf - ! 130 mgL C, Normal Flow 67m 85. 110m 7 40D mgL cr - Legend 325 .OL Cr - Depth (ft) 230 .gL Cr =OD -29 -3D-59 6D-89 _ 9D- 11.9 - 12D -1JJ High Flow & D9.1 -Y Pout D o.x 0.5 1.5 ks Attachment 2: Mixing Zone depictions of the combined ash pond and FGD blowdown based on GEMSS modeling results during low, normal, and high reservoir flows. Attachment 3 4 Mayo Creek rge Cove 'A - :.,.) Low- Level Release Discharge Structure ,r L 4-1 Spi