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HomeMy WebLinkAboutNC0004961_Revised Plan for Identification of New Discharges_20150521�� MflrE ENERGX CAROLINAS May 21, 2015 Mr Jeffrey Poupart, Section Chief NC Division of Water Resources 1617 Mail Service Center Raleigh, NC 27699-1617 Subject Revised Plan for Identification of New Discharges Riverbend Steam Station NCOOO4961 Gaston County Dear Mr Poupart, Environmental Services Duke Energy 526 South Church Street Charlotte, NC 28202 Mailing Address EC13K / P O Box 1006 Charlotte, NC 28201-1006 RECEIVED/DENR/DWR MAY 272015 Water Quality Permitting Section Duke Energy hereby formally submits the attached revised version of the Riverbend Plan for Identification of New Discharges This version includes edits in response to comments made by the NC Division of Water Resources If you have any questions regarding this submittal, please contact me at (704) 382-7959 or richard baker(cDduke-energy com I cert, 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 infoi matron, including the possibility of fines and nnpt isonment for knowing violations Sincerely, attachment Richard E Baker, Jr, P E , PMP Director, Environmental Programs Duke Energy EHS - CCP attachment �"'EOE"'lE9'/DPN ftWR F)? r 3 Duke Energy Carolinas, LLC I Plan for Identification of New Discharges ��� Riverbend Steam Station Ash Basin TABLE OF CONTENTS Table of Contents Report Verification Table of Contents List of Tables and Figures Section 1 - Introduction Section 2 - Site Description 21 Plant Description 22 Ash Basin Description 23 Permitted NPDES Wastewater and Stormwater Outfalls Section 3 - Site Geology and Hydrogeology 31 Site Geologic/Soil Framework 32 Site Hydrogeologic Framework Section 4 - Identification of New Discharges 41 Purpose of Inspection 42 Seepage 43 Area To Be Inspected for New Discharges 44 Inspection Procedure 45 Stormwater Outfalls Section 5 - References Appendices A — Riverbend Station Ash Basin — Inspection for Identification of New Discharges B — Areas of Wetness Paqe 1 3 3 3 3 7 7 7 9 9 9 9 9 10 11 r 3 Duke Energy Carolinas, LLC I Plan for Identification of New Discharges ��11� Riverbend Steam Station Ash Basin LIST OF TABLES AND FIGURES List of Tables Table 1 — NPDES Wastewater and Stormwater Outfalls List of Figures Figure 1 — Site Location Map Figure 2 — Areas to be Inspected for Seeps Duke Energy Carolinas, LLC I Plan for Identification of New Discharges FN Steam Station Ash Basin SECTION 1 - INTRODUCTION Section 1 - Introduction The purpose of this document is to address the requirements of North Carolina General Statute (GS)l 30A-309 210 (d) Identification and assessment of discharges, correction of unperm►tted discharges, as modified by North Carolina Senate BIII 729, for the Rlverbend Steam Station (RBSS) ash basin operated under National Pollutant Discharge Elimination System (NPDES) Permit NC0004961 The following requirements are contained In General Statute 130A-309 210 d) Identification of New Discharges — No later than October 1, 2014, the owner of a coal combustion residuals surface impoundment shall submit a proposed Plan for the Identification of New Discharges to the Department for its review and approval as provided in this subsection 1) The proposed Plan for the Identification of New Discharges shall include, at a minimum, all of the following a A procedure for routine inspection of the coal combustion residuals surface impoundment to identify indicators of potential new discharges, including toe drain outfalls, seeps, and weeps b. A procedure for determining whether a new discharge is actually present c A procedure for notifying the Department when a new discharge is confirmed d Any other information related to the identification of new discharges required by the Department 2) The Department shall approve the Plan for the Identification of New Discharges if it determines that the Plan complies with the requirements of this subsection and will be sufficient to protect public health, safety, and welfare, the environment, and natural resources. 3) No later than 30 days from the approval of the Plan for the Identification of New Discharges, the owner shall begin Implementation of the Plan in accordance with the Plan The North Carolina Senate BIII 729 establishes the submittal date of this Plan for Identification of New Discharges no later than October 1, 2014 This bill also modified GS 130A to establish the following submittals that are related to this Plan GS130A-309 210(a) was modified to require 2) No later than December 31, 2014, the owner of a coal combustion residuals surface impoundment shall submit a topographic map that identifies the location of all (i) outfalls from engineered channels designed or improved for the purpose of collecting water from the toe of the impoundment and (►►) seeps and weeps discharging from the impoundment that are not captured by engineered channels designed or Duke Energy Carolinas, LLC I Plan for Identification of New Discharges 01Riverbend Steam Station Ash Basin SECTION 1 - INTRODUCTION improved for the purpose of collecting water from the toe of the impoundment to the Department. The topographic map shall comply with all of the following: a Be at a scale as required by the Department. b Specify the latitude and longitude of each toe drain outfall, seep, and weep c. Specify whether the discharge from each toe drain outfall, seep, and weep is continuous or intermittent. d. Provide an average flow measurement of the discharge from each toe drain outfall, seep, and weep including a description of the method used to measure average flow e Specify whether the discharge from each toe drain outfall, seep, and weep identified reaches the surface waters of the State If the I discharge from a toe drain outfall, seep, or weep reaches the surface waters of the State, the map shall specify the latitude and longitude of where the discharge reaches the surface waters of the State f. Include any other information related to the topographic map required by the Department The Inspection procedures presented In this plan, developed to satisfy the requirements of GS130A-309 210 (d), will be used as the basis for developing the topographic map required by GS130A-309 210 (a)(2) M Duke Energy Carolinas, LLC I Plan for Identification of New Discharges �1J� Riverbend Steam Station Ash Basin SECTION 2 -SITE DESCRIPTION Section 2 - Site Description 2.1 Plant Description RBSS is a former coal-fired electricity generating facility which had a capacity of 454 megawatts located in Gaston County, North Carolina, near the town of Mt Holly (Figure 1) As of April 1, 2013, all of the coal-fired units have been retired The site is located between the south bank of the Catawba River on Mountain Island Lake and the north side of Horseshoe Bend Beach Road The surrounding area generally consists of residential properties, undeveloped land, and Mountain Island Lake 2.2 Ash Basin Description The ash basin system consists of a Primary Cell and a Secondary Cell, separated by an intermediate dike The ash basin at RBSS originally consisted of a single -cell basin commissioned in 1957 and was expanded In 1979 The single basin was divided by constructing a divider dike to form two separate cells In 1986 The ash basin is located approximately 2,400 feet to the northeast of the power plant, adjacent to Mountain Island Lake, as shown on Figure 2 The Primary Cell is impounded by an earthen embankment dike located on the west side of the Primary Cell The Secondary Cell is L' impounded by an earthen embankment dike located along the northeast side of the Secondary Cell The surface area of the Primary Cell is approximately 41 acres with an approximate maximum pond elevation of 724 feet The surface area of the Secondary Cell is approximately 28 acres �^ with an approximate maximum pond elevation of 714 feet The full pond elevation of Mountain Island Lake is approximately 646 8 feet The ash basin system was an integral part of the station's wastewater treatment system which predominantly received inflows from the ash removal system, station yard drain sump, and stormwater flows During station operations, Inflows to the ash basin were highly variable due to the cyclical nature of station operations The Inflows from the ash removal system and the station yard drain sump are discharged through sluice lines Into the Primary Cell The discharge from the Primary Cell to the Secondary Cell is through a concrete discharge tower located near the divider dike Although the station is retired, wastewater effluent from other non -ash -related station discharges to the ash basin is discharged from the Secondary Cell, through a concrete discharge tower, to Mountain Island Lake The concrete discharge tower drains through a 30 - Inch -diameter corrugated metal pipe Into a concrete -lined channel that discharges to Mountain Island Lake The ash basin pond elevation is controlled by the use of concrete stop logs 2.3 Permitted NPDES Wastewater and Stormwater Outfalls �I Table 1 provides a list of existing and proposed permitted NPDES wastewater and stormwater outfalls and descriptions of permitted waste streams mentioned in NCDENR's draft NPDES t Duke Energy Carolinas, LLC I Plan for Identification of New Discharges L-0%11Riverbend Steam Station Ash Basin I of SECTION 2 - SITE DESCRIPTION permits. Locations of existing and potential "new" wastewater and stormwater outfalls included in the draft NPDES permit are shown on Figure 2. Table 1. NPDES Wastewater and Stormwater Outfalls Wastewater Outfalls 001 002 002A 101 102 103 104 105 106 010 107 108 109 110 111 112 011 Coordinates 35° 29' 80" N 80° 58' 13" W 35° 22' 99" N 80° 57'32" W 35°21'51"N 80° 58'20" W 35° 21' 54" N 80° 58'01 " W 35°21'54"N 80° 57'57" W 35° 22'08" N 80° 57'54" W 35° 22' 15" N 80° 57'46" W 35° 22' 02" N 80° 57'46" W 35° 22'01" N 80° 57'28" W 35° 22' 01" N 80* 57'25" W 35° 21' 54" N 80° 57'22" W 35° 22' 15" N 80° 57'46" W 35° 22'08" N 80° 57'36" W 35° 22'08" N 80° 57'36" W 35° 22'08" N 80° 57'32" W Description of Description of Effluent Waste Stream Cooling water consisting of intake screen Catawba River backwash and water from the plant chiller (Mountain Island Lake) system, turbine lube oil coolers, condensate coolers, main turbine steam condensers and the intake tunnel dewatering sump. Catawba River Ash basin discharge consisting of induced (Mountain Island Lake) draft fan and preheater bearing cooling water, stormwater from roof drains and paving, treated groundwater, track hopper sump (groundwater), coal pile runoff, laboratory Yard sump overflow drain and chemical makeup tanks and drums Catawba River rinsate wastes, general plant/trailer sanitary (Mountain Island Lake) wastewater, turbine and boiler rooms sumps, vehicle rinse water, and stormwater from pond areas, upgradient watershed, and miscellaneous stormwater flows. Surface flow towards Catawba River Twelve (12) ash basin groundwater seeps. (Mountain Island Lake) Former stormwater Outfall 1. Contains 35° 29'80" N Catawba River stormwater and groundwater flow, also 80° 58' 13" W (Mountain Island Lake) includes wastewater from 10,000 gallon oil separator tank #3. 4 Duke Energy Carolinas, LLC I Plan for Identification of New Discharges �1J� Riverbend Steam Station Ash Basin SECTION 2 - SITE DESCRIPTION Stormwater Coordinates Outfall Description and Drainage Area Runoff Description Outfalls Receiving Water Body 24 -inch -diameter 35° 21' 38" N corrugated metal pipe SW001 80° 58'30" W (CMP) to intake canal Catawba River (Mountain Island Lake) Drainage area runoff the powerhouse roof, 21 -inch -diameter CMP to switchyard, and yard are south of the SWO02 35° 21'38" N intake canal powerhouse. Rail lines that transport coal are 80° 58'30" W Catawba River located within this area and coal residuals are (Mountain Island Lake) present in the rail bed. 24 -inch -diameter CMP to SWO03 35° 21'40" N intake canal 80° 58'32" W Catawba River (Mountain Island Lake) 15 -inch -diameter 35° 21'22" N reinforced concrete pipe Drainage area runoff from Horseshoe Bend SW004 80° 58'32" W Beach Road. Catawba River (Mountain Island Lake) Drainage area between stormwater outfalls 18 -inch -diameter CMP SWO03 and SW006. The 18 -inch CMP will be SWO03A 35° 21'40" N Catawba River removed. Duke Energy will notify DEMLR 80° 58'32" W (Mountain Island Lake) that the potential for stormwater discharges has ceased, and monitoring requirements will not apply. 35° 21' 39" N 36 -inch -diameter CMP Drainage area runoff from station yard areas SWO06 80° 58'32" W Catawba River and main oil storage tank area. (Mountain Island Lake) 24 -inch -diameter steel Drainage area runoff from the gravel road and SWO07 35° 21'80" N pipe laydown area north of the coal pile storage 80° 58'28" W Catawba River area. The 30 -inch ductile iron pipe leading (Mountain Island Lake) to SWO07 and SWO07 will be removed. 12 -inch -diameter ductile Duke Energy will notify DEMLR that the 35° 21'80" N iron pipe potential for stormwater discharges has SWO07A 80° 58'28" W leading to Catawba River ceased, and monitoring requirements will (Mountain Island Lake) not apply. 35° 21'51" N 36 -inch -diameter CMP to Drainage area runoff from the cinder storage SWO08 80° 58' 16" W Catawba River area, part of the ash stack planning for (Mountain Island Lake) removal, and the coal pile area. 35° 21'38" N 18 -inch -diameter CMP to SW010 80° 58' 41" W Catawba River (Mountain Island Lake) 35° 21'33" N 18 -inch -diameter CMP to Drainage area runoff from the Lark SW011 80° 58'45" W Catawba River Maintenance Facility. (Mountain Island Lake) 35° 21' 37" N 8 -inch -polyethylene pipe SWO12 80° 58'42" W Catawba River (Mountain Island Lake) The 15 -inch CMP leading to SW013 will be 35° 21'42" N 15 -inch -diameter CMP to removed. Duke Energy will notify DEMLR SWO13 80° 58'30" W Catawba River that the potential for stormwater (Mountain Island Lake) discharges has ceased, and monitoring requirements will not apply. 5 Duke Energy Carolinas, LLC I Plan for Identification of New Discharges �1J� Riverbend Steam Station Ash Basin SECTION 2 - SITE DESCRIPTION Stormwater Outfall Description and Outfalls Coordinates Receiving Water Body Drainage Area Runoff Description Drainage area runoff surrounding the septic tank. The 8 -inch CMP leading to SWO14 35° 21'42" N 12 -inch -diameter CMP to and/or any other outfalls in this area will be SWO14 80° 58'30" W Catawba River removed. Duke Energy will notify DEMLR (Mountain Island Lake) that the potential for stormwater discharges has ceased, and monitoring requirements will not apply. 35° 21'42" N 12 -inch -diameter CMP to Pipes discovered during an engineering field SWO15Catawba 80° 58' 30" W River evaluation and designated in this permit as (Mountain Island Lake) stormwater outfalls SW015, SW016, and 24 -inch -diameter CMP to SWO17 and discharging to the Catawba River SWO16 35° 21'42" N Catawba River (Mountain Island Lake). Upon abandonment 80° 58'30" W (Mountain Island Lake) or removal of the pipes leading to these outfalls, Duke Energy will notify DEMLR 35° 21'42" N 30 -inch -diameter RCP to that the potential for stormwater SWO17 80° 58'30" W Catawba River discharges has ceased, and monitoring (Mountain Island Lake) requirements will not apply. Duke Energy Carolinas, LLC ! Plan for Identification of New Discharges 07ZRiverbend Steam Station Ash Basin SECTION 3 - SITE GEOLOGY AND HYDROGEOLOGY Section 3 - Site Geology and Hydrogeology L 3.1 Site Geologic/Soil Framework Riverbend and Its associated ash basin system are located in the Charlotte terrane of the _ Carolina Zone (Pippin et al 2008), or as described In the older belt terminology, the Charlotte Belt of the Piedmont physiographic province (Piedmont) (North Carolina Geological Survey 1985) The Charlotte terrane is characterized by mostly felsic to mafic plutonic rocks which Intrude a suite of mainly metaigneous rocks and minor metasedimentary rocks (Pippin et al _ 2008) it The soils that overlie the bedrock In the area have generally formed from the in-place weathering of the parent bedrock The fractured bedrock Is overlain by a mantle of unconsolidated material known as regolith The regolith, where present, includes the soil zone, a zone of weathered, decomposed bedrock known as saprollte, and alluvium Saprolite, the product of chemical and mechanical weathering of the underlying bedrock, Is typically i composed of silt and coarser granular material up to boulder size and may reflect the texture of the rock from which It was formed The weathering products of felslc rocks may be sandy - textured and rich in quartz content while mafic rocks form a more clayey saprollte (LeGrand 2004) 3.2 Site Hydrogeologic Framework ' Piedmont topography is characterized by gently rounded sloped hills and valleys Recharge -J typically occurs on upland areas and slopes while groundwater discharge is concentrated in surface water bodies and lowland areas LeGrand's (1988, 2004) conceptual model of the groundwater setting In the Piedmont Incorporates the above two medium systems Into an entity that Is useful for the description of groundwater conditions That entity Is the surface drainage basin that contains a perennial stream or river (LeGrand 1988) Each basin is similar to adjacent basins and the conditions are generally repetitive from basin to basin Within a basin, movement of groundwater is generally restricted to the area extending from the drainage divides -� to a perennial stream or river (Slope -Aquifer System, LeGrand 1988, 2004) Rarely does groundwater move beneath a perennial stream or river to another more distant stream (LeGrand � 2004) Therefore, In most cases in the Piedmont, the groundwater system is a two -medium system (LeGrand 1988) restricted to the local drainage basin The groundwater occurs In a system composed of two Interconnected layers residuum/saprollte and weathered rock overlying fractured crystalline rock separated by the transition zone Typically, the residuum/saprollte is partly saturated and the water table fluctuates within It Water movement Is generally through the fractured bedrock The near -surface fractured crystalline rocks can form extensive aquifers The character of such aquifers results from the combined effects of the rock type, fracture system, topography, and weathering Topography exerts an influence on both weathering and the opening of fractures while the weathering of the crystalline rock modifies both transmissive and storage characteristics Duke Energy Carolinas, LLC I Plan for Identification of New Discharges �)� Riverbend Steam Station Ash Basin SECTION 3 - SITE GEOLOGY AND HYDROGEOLOGY The aquifer system In the Piedmont typically exists in an unconfined or semi -confined condition In the bedrock zone Under natural conditions, the general direction of groundwater flow can be approximated from the surface topography Groundwater moves both vertically down through the regolith and parallel to the bedrock surface to areas where groundwater discharges as seepage into streams, lakes, or other surface water bodies RBSS is located on a peninsula in the Catawba River on the north side of Horseshoe Bend 1 Beach Road (Figure 2). This road runs generally west to east and is located along a local topographic divide Based on the slope -aquifer system, groundwater at the site Is expected to flow downward from this topographic divide to the ash basins and discharge into Mountain i Island Lake (Catawba River) 8 Duke Energy Carolinas, LLC I Plan for Identification of New Discharges �1� Riverbend Steam Station Ash Basin J SECTION 4 - IDENTIFICATION OF NEW DISCHARGES Section 4 - Identification of New Discharges 4.1 Purpose of Inspection The purpose of the Inspection is to Identify new discharges and Indicators of potential new discharges, including toe drain outfalls, seeps, and weeps associated with the coal combustion residuals surface Impoundment (ash basin) 4.2 Seepage Seepage Is considered to be the movement of wastewater from the ash basin through the ash basin embankment, the embankment foundation, the embankment abutments, through residual material in areas adjacent to the ash basin, or through the bottom of the ash basin (if the flow eventually reaches the ground surface) Therefore, a seep is defined in this document as an expression of seepage at the ground surface above the ordinary high water mark of any waters of the state. Only seeps that have the presence of a discernible, confined and discrete _ conveyance to the surface water will be considered a new seep warranting further evaluation of i flow and pollutant characterization A weep is understood to have the same meaning as a seep Indicators of seepage Include areas where water Is observed on the ground surface and/or where vegetation suggests the presence of seepage Seepage can emerge anywhere on the downstream face, beyond the toe, or on the downstream abutments at elevations below normal pool Seepage may vary in appearance from a "soft," wet area to a flowing "spring " Seepage may show up first as only an area where the vegetation is lusher and darker green than surrounding vegetation Cattails, reeds, mosses, and other marsh vegetation often become established in a seepage area' However, In many Instances, Indicators of seeps do not necessarily Indicate the presence of seeps 4.3 Area To Be Inspected for New Discharges The areas to be Inspected for new discharges and Indicators of potential new discharges are the areas of the site where water contained in the ash basin might Infiltrate Into the underlying + residual material and be expressed as seepage This would Include the earthen embankment which impounds the ash basin and certain adjacent areas The extent of the areas to be inspected was determined based on the generalized LeGrand conceptual model the concept of the slope -aquifer system, and the site topography In this generalization, flow of water from the ash basin would be expected to be located within the slope -aquifer compartment and to be below the full pond elevation of the ash basin The areas to be inspected are shown on Figure 2 4.4 Inspection Procedure The Inspection procedure for identification of new discharges and Indicators of potential new discharges associated with the Buck ash basin system is provided in Appendix A In addition to the specific requirements for the inspection, Appendix A also provides the general requirements, ' Dam Operation, Maintenance, and Inspection Manual, North Carolina Department of Environment and Natural Resources, Division of Land Resources, Land Quality Division, 1985 (Revised 2007) v 1 0 ► Duke Energy Carolinas, LLC I Plan for Identification of New Discharges 1 �� Riverbend Steam Station Ash Basin r the frequency of Inspections, documentation requirements, and provides a decision flow chart for determining if the potential new discharge Is associated with the ash basin Duke Energy will be further classifying seeps into non -engineered seeps at locations where the seepage emerges from natural or residual material and engineered seeps (I e , toe drains) Appendix B provides the history and current state of seeps Identified with regards to official location and type (non -engineered seeps and engineered seeps) �1 4.5 Stormwater Outfalls If a stormwater outfall is discharged during periods that do not coincide with precipitation events, the water exiting the outfall will be sampled to determine if Coal Combustion Products (CCP) or other wastes are discharging from the outfall These areas will be identified, photographed, sampled, and potentially added to the NPDES wastewater permit 10 Duke Energy Carolinas, LLC ; Plan for Identification of New Discharges ��� Riverbend Steam Station Ash Basin SECTION 5 - REFERENCES Section 5 - References North Carolina Geological Survey, 1985, Geologic map of North Carolina North Carolina Geological Survey, General Geologic Map, scale 1 500000 LeGrand, HE 1988 Region 21, Piedmont and Blue Ridge, p 201-208, in Black, W, Rosenhein, J S , and Seaber, P R, eds , Hydrogeology Geological Society of America, The Geology of North America, v 0-2, Boulder, Colorado, 524p it LeGrand, Harry, Sr 2004 A Master Conceptual Model for Hydrogeological Site Characterization in the Piedmont and Mountain Region of North Carolina, North Carolina Department of Environment and Natural Resources Pippin, Charles G , Chapman, Melinda J , Huffman, Brad A, Heller, Matthew J , and Schelgel, Melissa E 2008 Hydrogeologic Setting, Ground -Water Flow, and Ground -Water Quality at the Langtree Peninsula Research Station, Iredell County, North Carolina, 2000-2005, United States Geological Survey, Prepared in cooperation with the North Carolina Department of Environment and Natural Resources, Division of Water Quality 11 I ti-ore _?� , �-_ � � ., 1 1 •�� __ _ _ k(JNTAIN 1 c1.A f) -r V , l.. L • �`' /' `` _t- ':1707 �r ti ori � i• � i. ASH BASIN J •'�1,'a!4r Tank L Du RIVER3EIND STEAM STAT QAlh ern i\ kAJ _ f •e� s a C 16 _ ��• t - Rozz ell ' i ' I� �� •/ — — Bridae s " NOTES: £V 61- _ I. SOURCES: USGS TOPOGRAPHIC MAP - MT. ISLAND LAKE, it / ell -./ CREATED 1993. USGS TOPOGRAPHIC MAP -LAKE NORMAN - •,' t - - J ` '1 SOUTH, CREATED 1993. tt 1 SCALE (FEET) 1000 0 1000 2000 fm HRR Enghu•rin' Inc. Ll— t8� Flit IR 0 Som auNi Sum Cham. NC 782a SITE LOCATION MAP RIVERBEND STEAM STATION DUKE ENERGY CAROLINAS, LLC GASTON COUNTY, NORTH CAROLINA DATE APRIL 6, 2015 FIGURE 1 RIVERBEND STEAM STATION ASH BASIN INSPECTION FOR IDENTIFICATION OF NEW DISCHARGES Riverbend Steam Station Ash Basin INSPECTION FOR IDENTIFICATION OF NEW DISCHARGES 1. Purpose of Inspection The purpose of the inspection is to identify new discharges and indicators of potential new discharges, including toe drain outfalls, seeps, and weeps that arise after the initial submittal of maps required by North Carolina General Statute 130A-309.210(a)(2)(ii). Seepage is considered to be the movement of wastewater from the ash basin through the ash basin embankment, the embankment foundation, the embankment abutments, through residual material in areas adjacent to the ash basin, or through the bottom of the ash basin (if the flow eventually reaches the ground surface.) Therefore, a seep is defined in this document as an expression of seepage at the ground surface above the ordinary high water mark of any waters of the state. Only seeps that have the presence of a discernible, confined and discrete conveyance to the surface water will be considered a new seep warranting further evaluation of flow and pollutant characterization. A weep is understood to have the same meaning as a seep. If new discharges or indicators of potential new discharges are identified, the decision flow chart (see Figure A- 1) will be used to determine if the potential new discharge is from the ash basin and if notification to the North Carolina Department of Environment and Natural Resources (NCDENR) Division of Water Resources (DWR) is required. 2. General Inspection Requirements 2.1. Inspections are to be performed on areas that are below the ash basin full pond elevation and within the area shown on Figure A-2 The purpose of the inspection is to identify new discharges and indicators of potential new discharges, including toe drain outfalls, seeps, and weeps associated with the coal combustion residuals surface impoundment (ash basin) 2.2. If required, a larger scale figure showing the locations of outfalls from engineered channels will be developed If a separate figure showing outfalls from engineered channels is not developed, Figure A-2 will be revised to show these features. 2.3. Inspections of areas on or adjacent to the ash basin embankments should be performed within two months after mowing, if possible. 2.4. Inspections should not be performed if the following precipitation amounts have occurred in the respective time period preceding the planned inspection. 2.4.1. Precipitation of 0.1 inches or greater within 72 hours or 24.2. Precipitation of 0 5 inches or greater within 96 hours 2.5. Record the most recent ash basin water surface elevation. 2.6 Review previous Inspection for Identification of New Discharge Report(s) prior to performing inspection 2.7. Review the most recent previous dam inspections. Riverbend Steam Station Ash Basin INSPECTION FOR IDENTIFICATION OF NEW DISCHARGES 2 8. Conduct an interview with the Site Environmental Coordinator prior to performing inspection to inquire about possible changes to site conditions, such as pond elevations, operations, additions or removal of wastewater discharges to the ash basin, changes to site surface water drainage, etc. 3. Frequency of Inspections Inspections will be performed on a semi-annual basis during the following months. April to May and October to November 4. Qualifications The inspections shall be performed under the direction of a qualified Professional Engineer or Professional Geologist. 5. Documentation of Inspection The inspection shall be documented by the individual performing the inspection. The report should contain observations and descriptions of the seeps observed, changes in observations compared to previous inspections, estimates of flows quantities, and photographs of seeps and outfalls of engineered channels designed or improved for collecting water from the impoundment Photographs are to be numbered and captioned. In addition, the inspection should also include sampling. The facility shall sample for the following constituents: • Chlorides • Selenium • Fluorine • pH • Mercury (method 1631E) • Total Dissolved Solids • Barium • Antimony • Iron • Thallium j • Manganese • Molybdenum • Zinc • Boron • Arsenic • Aluminum • Cadmium • Sulfate • Chromium • Total Suspended Solids • Copper • Temperature • Lead • Specific Conductance • Nickel This sampling is necessary to demonstrate if a discharge/seep contains Coal Combustion Products (CCPs), if it is some other type of waste stream, or if the seepage is simply not associated with a process wastewater discharge. 2 Riverbend Steam Station Ash Basin INSPECTION FOR IDENTIFICATION OF NEW DISCHARGES 6. Initial Inspection An initial inspection should be performed to identify features and document baseline conditions including location, extent (i.e., dimensions of affected area), and flow. Seep locations should be recorded using a Global Positioning System (GPS) device. Photographs should be taken from vantage points that can be replicated during subsequent semi-annual inspections. 7. Inspection For New Seeps at Outfalls From Engineered Channels Inspect the outfalls from engineered channels designed and/or improved (such as through the placement of rip -rap) associated with the ash basin dikes to identify new seeps or indicators of new seeps. 7.1. Inspect all outfalls from engineered channels designed and/or improved (such as through the placement of rip -rap) 7.2. Document the condition of the outfall of the engineered channel with photographs. Photographs are to be taken from similar direction and scale as photographs taken during the initial inspection 7.3 Observe outfall for seepage and for indicators of seeps. 7.4 Compare current seepage location, extent, and flow to seepage photographs and descriptions from previous inspections. 7.5. Record flow rate if measureable. 7.6. Sample for the following constituents to demonstrate if a discharge/seep contains CCPs, if it is some other type of waste stream, or if the seepage is simply not associated with a process wastewater discharge• - • Chlorides • Fluorine • Mercury (method 1631E) • Barium • Iron • Manganese • Zinc • Arsenic • Cadmium • Chromium • Copper • Lead • Nickel 3 • Selenium • pH • Total Dissolved Solids • Antimony • Thallium • Molybdenum • Boron • Aluminum • Sulfate • Total Suspended Solids • Temperature • Specific Conductance 0 V Riverbend Steam Station Ash Basin INSPECTION FOR IDENTIFICATION OF NEW DISCHARGES 8. Inspection For New Seeps Not Captured by Engineered Channels Inspect areas below the ash basin full pond elevation and within the slope -aquifer system shown on Figure A-2 to identify new seeps or indicators of new seeps. Inspect topographic drainage features that potentially could contain new seeps that potentially discharge from the ash basin Investigations should include areas where perimeter ditches/swales are located around active or inactive ash basins. 8.1. Previously Identified Seeps a) Inspect previously identified seep locations. Document the condition of the seeps with a photograph. Photographs are to be taken from similar direction and at a similar scale as the photograph documenting original photograph of seep. Describe the approximate dimensions and flow conditions of the seep. This information may help to demonstrate changing site conditions over time. b) If flow measurement device is installed at the outfall, record flow. c) Observe seep to determine if changes to location, extent, or flows are present. Document changes to location, extent, and/or flow amount or pattern d) Sample for the following constituents to demonstrate if a discharge/seep contains CCPs, if it is some other type of waste stream, or if the seepage is simply not associated with a process wastewater discharge: • Chlorides • Fluorine • Mercury (method 1631E) • Barium • Iron • Manganese • Zinc • Arsenic • Cadmium • Chromium • Copper • Lead • Nickel 8 2 New Seep or Indicators of Seep • Selenium • pH • Total Dissolved Solids • Antimony • Thallium • Molybdenum • Boron • Aluminum • Sulfate • Total Suspended Solids • Temperature • Specific Conductance a) Mark the location of new seep or indicators of seep using a GPS device b) Document the condition of the seeps or indicators of seeps with a photograph 4 Riverbend Steam Station Ash Basin INSPECTION FOR IDENTIFICATION OF NEW DISCHARGES c) Describe the approximate dimensions and flow conditions of the seep. d) Sample for the following constituents to demonstrate if a discharge/seep contains CCPs, if it is some other type of waste stream, or if the seepage is simply not associated with a process wastewater discharge: • Chlorides • Fluorine • Mercury (method 1631E) • Barium • Iron • Manganese • Zinc • Arsenic • Cadmium • Chromium • Copper • Lead • Nickel • Selenium • pH • Total Dissolved Solids • Antimony • Thallium • Molybdenum • Boron • Aluminum • Sulfate • Total Suspended Solids • Temperature • Specific Conductance e) Map the location of new seep or indicator of seep using GPS coordinate points collected during the site visit. f) If seep or indicator of seep was not caused by changes in surface water drainage and if the location is below the ash basin pond elevation, utilize the decision flow chart to determine if the seep represents a discharge from the ash basin and if notification to DWR is required 9. Update Maps Identifying Seeps If new seeps are identified during the inspection, Figure A-2 shall be updated to show the location of the new seeps. All seeps located below the ash basin full pond elevation and within the slope -aquifer system shown are to be shown on Figure A-2. 10. Decision Flow Chart The decision flow chart developed to determine whether a new seep discharges from the ash basin is found on Figure A-1. 11. Procedure for Notifying NCDENR DWR if New Discharge Is Confirmed Duke Energy will notify the DWR Regional Office by mail within 5 days after the discovery of a new seep unless a different timeframe is established and specified in reissued permits. If the new seep represents 5 7 1 Riverbend Steam Station Ash Basin INSPECTION FOR IDENTIFICATION OF NEW DISCHARGES a significant change in flow or pollutant loading from the facility, or a bypass or upset, it may fall under provisions that would require immediate reporting. D Rlverbend Steam Station Ash Basin INSPECTION FOR IDENTIFICATION OF NEW DISCHARGES Figure A-1 - Decision Flow Chart for Determining If New Seep Represents Discharge From the Ash Review previous seep inspection reports I Perform inspection for new seeps I Is new seep located below elevation of ash basin? Yes Is new seep located within slope -aquifer boundary system as shown on Figure A-27 Yes Does new seep present concentrated flow that could be collected measured and sampled? Yes Collect water quality sample at seep and perform the following analyses • Field parameters pH, specific conductance, temperature, turbidity • Constituent analyses NPDES parameters, plus mayor cations and anions Compare analytical results from seep to relevant ash basin and groundwater sampling results to determine if analytical results from new seep indicate discharge from the ash basin Do analytical results from new seep indicate discharge from ash basin? Yes j Prepare report documenting inspection and evaluation Notify DWR that new seep identified and based on above evaluation, the new seep represents discharge from ash basin No No New seep is not hydraulically related to ash basin New seep presents diffuse flow conditions No Photograph, map location, add to seep location map, describe flow conditions, and approximate area of seepage No New seep is not related to ash basin Prepare report documenting inspection and evaluation Notify DWR that new seep was identified, however new seep does not represent discharge from ash basin Notes: 1 If no new seeps are identified, Inspection will be documented however no notification to NCDENR DWR is required 2 If new seeps are identified that do not represent discharge from the ash basin during the same inspection that identifies new seeps that do represent a discharge from the ash basin, a single report will be submitted to NCDENR DWR. 7 Table B-1 - Riverbend Steam Station Ash Basin — Seep Locations and Descriptions Area of Location Coordinates Flow Seep Type Wetness Description p (Engineered or Non -Engineered) Description Latitude Longitude S-1 35 365 -80.967 Continuous Located west of the Primary Cell and north of the Cinder Storage Area Seepage at multiple locations near the toe of the Primary Cell and Cinder Storage Area dikes and collect in the general area of S-1 The flow is generally overland with no well defined channel S-2 35.365 -80.966 Continuous Located west of the Primary Cell dike at the end of rip -rap lined channel, near the toe of the Primary Cell dike The channel collects seepage from the toe of the dike and flows through a defined channel approximately 1 to 2 -ft wide. S-3 35.369 -80965 Continuous Located west of the Secondary Cell in a drainage feature downgradient from the toe of the Secondary Cell dike. Seepage is upgradient of the S-3 device. S-4 35 371 -80.963 Continuous Located north of the Secondary Cell downgradient of the toe of the northern Secondary Cell abutment. Seepage flows from channels sampled via S-5 and S-9 S-5 35 370 -80963 Continuous Located north of the Secondary Cell along the toe slope of the northern Secondary Cell abutment. Seepage flows from multiple locations upgradient of the S-5 device S-6 35.367 -80.958 Continuous Located east and downgradient of the ash basin, flowing in the general direction of groundwater flow from the ash basin S-7 35 367 -80957 Continuous Located east and downgradient of the ash basin, flowing in the general direction of groundwater flow from the ash basin. S-8 35 365 -80.956 Continuous Located east of the ash basin and Secondary Cell dike. S-9 35.371 -80.963 Continuous Located north of the Secondary Cell northern abutment at the end of rip -rap lined channel, near the toe of the abutment The channel collects seepage from the toe of the abutment and flows through a defined channel approximately 2 -ft wide. S-10 35 369 -80960 Intermittent Located east of the Secondary Cell dike downstream of a rip -rap lined channel at the toe of the dike. The channel collects seepage from the toe of the dike and may (intermittently) flow through a defined channel approximately 2 to 3 -ft wide Flow was not exhibited at the time of sampling S-11 35.369 -80.960 Continuous Located east of the Secondary Cell dike downstream of a rip -rap lined channel at the toe of the dike The channel collects seepage from the toe of the dike and flows through a defined channel approximately 2 to 3 -ft wide S-12 35.368 -80959 Continuous Located at the end of a concrete channel downstream of the toe of the Secondary Cell dike Seepage flows from multiple locations along the ground surface downgradient of the toe of the dike and flows overland Notes- I Flow description for each sample location is based on multiple site visits performed by HDR Engineering, Inc (HDR) from November 2013 until April 2014 2. S-10 did not exhibit flow at the time of sampling 3 Flow measurements and analytical samples were collected (except for S-10) on April 29, 2014 4 Location coordinates for sampling locations were recorded by HDR using a handheld Trimble GPS unit and are approximate i f