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HomeMy WebLinkAboutNC0004987_Ground Water Information 2014_20141015 (6) • • , • !-1 • • • • • • y X • Groundwater Information • RECEIVED!DENR!DWR OCT 152014 Water a Pem►IWn99 9Zion I • J it _ . • _. .. �.L.L�e/3 rim hreaili -..� .. _ ..✓e[l�„-"r=T.- �_����7�iatJ�' _ .- ... .-J..Z 4. - ��J�.. t.r...�r_�.,� Marshall Ash Basin (NPDES Permit NC0004987) Groundwater Monitoring Program Reports and Recommendations Groundwater monitoring is conducted around the ash basin system at the Marshall Steam Station under NPDES Permit NCOOO4987. The following items are presented to describe potential on- site and off-site receptors, the nature of the groundwater flow regime around the Marshall site, and the Marshall groundwater monitoring program. • Item 1 -Receptor Survey Marshall Steam Station Ash Basin • Item 2 - Generalized Groundwater Flow Direction Figure • Item 3 - Groundwater Monitoring Program Sampling, Analysis, and Reporting Plan The referenced items and documents are included to describe the current state of the groundwater monitoring program and any changes to the existing monitoring plan. Changes to the current program (including installation of additional observation or monitoring wells) which are proposed by Duke Energy in the future may be allowed following consultation with NCDENR and should not require a re-opening of the Marshall NPDES permit. Item 1 - Receptor Survey Marshall Steam Station Ash Basin A receptor survey has been completed to identify private water supply wells, public water supplies, surface water bodies, and wellhead protection areas (if present) within a 0.5-mile radius of the Marshall ash basin compliance boundary. The report presents the methodology and findings of the survey. This report is included as Enclosure 1. Item 2 - Generalized Groundwater Flow Direction Figure The Marshall ash basin site and the generalized groundwater flow directions for the shallow water table are presented in a figure contained in Enclosure 2. The figure presents the generalized groundwater flow direction around the ash basin with arrows depicting probable generalized groundwater flow directions for the shallow water table. These generalized flow directions were developed based on the site hydrogeologic conceptual groundwater flow model, site topography, and historic site groundwater elevation data. Item 3 - Groundwater Monitoring Program Sampling,Analysis,and Reporting Plan The groundwater monitoring program sampling, analysis, and reportinf ,Au) wasDwR developed to support the requirement for groundwater monitoring around the ars �I�s( R�iri OCT 152014 Water civality Permitting Section The Plan describes the groundwater monitoring network, methodologies of field sampling, record-keeping protocols, analytical procedures, data quality objectives, data validation, and reporting that will be used to support the Marshall ash basin groundwater monitoring program. This document is included as Enclosure 3. As stated in the Plan, it is recommended that sample reporting requirements be changed to require reporting within 60 days of the date of sample collection. It is recommended that the compliance monitoring wells at the Marshall site continue to be sampled at a frequency of three times per year and analyzed for the same constituents that have been historically analyzed for the NPDES-required groundwater monitoring. We also plan to develop a groundwater flow model of the site predicting expected groundwater flow paths from areas around the ash pond system to the appropriate receiving water body. The groundwater flow model would be used to verify the current understanding of the groundwater flow directions at the site and could be used to evaluate exceedances if any are found to be related to impacts from the ash basin. We propose that model will be developed and the groundwater flow modeling report be submitted to NCDENR within 120 days of the NPDES permit being issued. As plans are made to develop the groundwater flow model, the installation of additional observation wells in or around the ash basin system may be beneficial to enhance the model. If Duke's evaluation deems additional observation wells to be beneficial, we will communicate our recommendations to NCDENR prior to well installation. NCDENR Aquifer Protection Section (APS) developed a policy for compliance evaluation of groundwater results at ash basins with no prior groundwater monitoring and published a memorandum providing that policy on June 17, 2011. The memorandum titled Policy for Compliance Evaluation of Long-Term Permitted Facilities with No Prior Groundwater Monitoring Requirements outlined the process for evaluating compliance of groundwater monitoring results based on the requirements in 15A NCAC 2L.0106. The memorandum acknowledges the factors that monitoring well placement and existing conditions at the ash basins have on determination of exceedances of 2L Standards in groundwater monitoring results at ash basins. The memorandum included a flow chart showing the process for determining if a measured groundwater concentration greater than 15A NCAC 02L .0202 would cause the facility to be non-compliant and would result in implementation of corrective action. Duke recommends continued utilization of the June 17, 2011, NCDENR memorandum to evaluate exceedances of 2L Standards at the Marshall ash basin. For exceedances that are not the result of naturally occurring site conditions, the process prescribed in the memorandum —mom requires the permittee to comply with corrective action requirements as specified in 15A NCAC 02L.0106. Enclosures: Enclosure 1 —Receptor Survey Marshall Steam Station Ash Basin Enclosure 2—Generalized Groundwater Flow Direction Figure Enclosure 3—Groundwater Monitoring Program Sampling,Analysis, and Reporting Plan I I I RECEPTOR SURVEY MARSHALL STEAM STATION ASH BASIN I NPDES PERMIT NC0004987 I I ct:N DUKE ENERGY® I IIPrepared for: DUKE ENERGY CAROLINAS, LLC ICharlotte, North Carolina I IPrepared by: I HDR ENGINEERING, INC. OF THE CAROLINAS Charlotte, North Carolina I October 10, 2014 I I 1 1 FN I REPORT VERIFICATION PROJECT: RECEPTOR SURVEY MARSHALL STEAM STATION ASH BASIN ' NPDES PERMIT NC0004987 ' This document has been reviewed for accuracy and quality commensurate with the intended application. Prepared by: 4,tel Date: /° i 6/2b/ Checked by: Date: f0//o/2D1'I Approved by: cekj _ Date: 14 /10 /2O(4- Project Manager: Brooke Ahrens, PE I 1 I 1 1 1 1 RECEPTOR SURVEY ' MARSHALL STEAM STATION ASH BASIN NPDES PERMIT NC0004987 TABLE OF CONTENTS Section Page No. SECTION 1 INTRODUCTION 1 SECTION 2 BACKGROUND 2 1 2.1 Plant and Ash Basin Description 2 2.2 Description of Surrounding Properties 3 SECTION 3 RECEPTOR SURVEY ACTIVITIES 4 3.1 NCDENR Records Review 4 1 3.2 Catawba County Records Review 4 3.3 Utility Department Records Review 5 ' 3.4 HDR Field Survey 5 3.5 USGS Hydrography Review 6 ' SECTION 4 FINDINGS 7 4.1 NCDENR Records 7 1 4.2 Catawba County Records 7 4.3 Utility Department Records 8 1 4.4 HDR Field Survey 8 4.5 Summary of Receptor Survey Findings 9 1 FIGURES 1 Figure 1 Receptor Survey Map TABLES Table 1 Public and Private Water Supply Wells ' (Within 0.5 Mile Radius of Ash Basin Compliance Boundary) 1 I I Section 1 I Introduction IDuke Energy Carolinas, LLC's (Duke Energy) Marshall Steam Station(MSS) is located on Lake Norman in Catawba County near Terrell, North Carolina (Figure 1). MSS is a coal-fired I electricity generating facility with a capacity of 2,090 megawatts which began commercial operation in 1965. ICoal ash residue from the MSS coal combustion process has historically been disposed of in the station's ash basin. The ash basin system consists of a single cell, impounded by an earthen dike, Ilocated on the southeast end of the ash basin. Clarified effluent is discharged to Lake Norman through a discharge tower located within the ash basin. The discharge from the ash basin is Ipermitted by the North Carolina Department of Environment and Natural Resources (NCDENR) Division of Water Quality (DWQ) under the National Pollutant Discharge Elimination System I (NPDES)Permit NC0004987. I HDR Engineering, Inc. of the Carolinas (HDR)has completed a receptor survey to identify water supply wells, public water supplies, surface water bodies, and wellhead protection areas (if present) within a 0.5 mile radius of the MSS ash basin compliance boundary (Figure 1).' The Icompliance boundary for groundwater quality in relation to the ash basin is defined in accordance with 15A NCAC 02L .0107(a) as being established at either 500 feet from the waste Iboundary or at the property boundary,whichever is closer to the source. IThe survey activities performed and the findings of those activities are presented in Sections 3 and 4,respectively. I I I A Drinking Water Supply Well and Receptor Survey, Marshall Steam Station Ash Basin, NPDES Permit NC0004987 report dated September 30,2014(submitted to NCDENR under separate cover), was completed to satisfy the requirements outlined in The Coal Ash Management Act 2014 — General Assembly of North Carolina Senate Bill 729 Ratified Bill(Session 2013)and the NCDENR August 13,2014 Notice of Regulatory I Requirements. 1 I I 1 Section 2 Background 2.1 Plant and Ash Basin Description ' MSS is a coal-fired electricity generating facility with a capacity of 2,090 megawatts located in Catawba County, North Carolina near the community of Terrell. The site is located north of NC 1 Hwy 150, east of Sherrills Ford Road and south of Island Point Road, and is generally situated between residential properties and Lake Norman (Figure 1). The ash basin is situated between the MSS to the south,primarily residences to the west and north, and Lake Norman to the east. A topographic divide is located along Sherrills Ford Road and along Island Ford Road. The topography at the site generally slopes downward from that divide toward Lake Norman. The ash basin was constructed in 1965 and is located approximately 2,000 feet northeast of the power plant, as shown on Figure 1. The waste boundary associated with the ash basin is 1 approximately 382 acres in area and is also shown on Figure 1. The approximate pond elevation for the ash basin is 790 feet. The normal pond elevation of Lake Norman is approximately 760 1 feet. The ash basin system is an integral part of the station's wastewater treatment system, which receives inflows from the ash removal system, coal pile runoff, landfill leachate, FGD wastewater, the station yard drain sump, stormwater flows, and station wastewater. During ' station operations, inflows to the ash basin are highly variable due to the cyclical nature of station operations. Inflows from the station to the ash basin are discharged into the southeast portion of the ash basin. The ash basin pond elevation is controlled by the use of concrete stop logs. The discharge from the ash basin is through a concrete discharge tower located in the eastern portion of the ash basin. The concrete discharge tower drains through a 30-inch diameter slip-lined corrugated metal pipe which discharges into Lake Norman. I 1 2 I I I ISection 2 Background 1 2.2 Description of Surrounding Properties Properties located within a 0.5 mile radius of the MSS ash basin compliance boundary generally Iconsist of undeveloped land and Lake Norman to the east, residential properties located to the north and west, the MSS station and several residences to the south, and commercial properties Ito the southeast along NC Hwy 150. IFigure 1 depicts the general land use surrounding the MSS. I I I I I I I I I I 1 3 I I 1 1 Section 3 1 Receptor Survey Activities 3.1 NCDENR Records Review 1 On July 10, 2014, Mr. Justin Schumacher with HDR contacted Mr. Sean McGuire, Geographic Information System (GIS) Specialist with the NCDENR Department of Environmental Health 1 (DEH) Public Water Supply Section (PWSS), by telephone. Mr. McGuire stated that the Public Water Supply Water Sources GIS point data set was in the process of being updated. The most ' current GIS data set of public water supply locations available from North Carolina state agencies was provided by Mr. McGuire via electronic mail on July 14, 2014. The GIS point data for the public water supply wells includes, but is not limited to information such as public water supply (PWS) system identification numbers, ownership information, PWS source type, well depth, and well yield. HDR reviewed the GIS data set to identify public water supply sources within a 0.5 mile radius of the MSS ash basin compliance boundary. On August 15, 2014, HDR reviewed the NCDENR Division of Water Resources (DWR) Source Water Assessment Program (SWAP) online database for public water supply sources to identify wells located within a 0.5 mile radius of the ash basin compliance boundary, to confirm the location of wells included in the Public Water Supply Water Sources GIS point data set, and to identify wellhead protection areas located within a 0.5 mile radius of the compliance boundary. The NCDENR SWAP database provides detailed assessments of all public drinking water intakes and wellhead protection areas in North Carolina. The website address is: (http://swap.ncwater.org/website/swap/viewer.htm). 3.2 Catawba County Records Review ' HDR contacted the Catawba County Environmental Health Department to inquire about the location and details (if available) for registered private water supply wells located in Catawba 1 County within a 0.5 mile radius of the ash basin compliance boundary. On August 20,2014,Ms. Brooke Ahrens with HDR contacted Mr. Mike Cash, Environmental Health Supervisor with the 1 4 i 1 ISection 3 Water Supply Well Survey Activities Catawba County Environmental Health Department. Mr. Cash indicated that Catawba County began collecting well record information for private water supply wells in 1998. Mr. Cash provided well record information for four wells located within a 0.5 radius of the compliance boundary. Mr. Chad Hearn with HDR contacted the Catawba County Utilities and Engineering Department on April 15, 2014 to inquire about municipal water supply to properties located in Catawba 1 County within a 0.5 mile radius of the ash basin compliance boundary. Mr. Jonathan Greer, Project Manager with the Utilities and Engineering Department indicated that the City of ' Hickory provides municipal water supply to properties located within a 0.5 mile radius of the compliance boundary. 111 3.3 Utility Department artment Records Review HDR contacted the City of Hickory Public Utilities Department to inquire about municipal water supply to properties located within a 0.5 mile radius of the ash basin compliance boundary. On August 20, 2014, Ms. Brooke Ahrens of HDR contacted Ms. Tracy Church with the City of Hickory, by telephone. Ms. Ahrens subsequently provided Ms. Church a list of properties where 1 neither a water supply well or a water meter was observed in the field to confirm municipal water service to these addresses. Ms. Church reviewed the City's billing records to confirm which properties were currently connected to the City's water service. 3.4 HDR Field Survey HDR personnel performed a field reconnaissance on March 31,2014 to attempt to identify water supply wells and surface waters located within a 0.5 mile radius of the ash basin compliance boundary. A windshield survey was conducted from public roadways to identify water meters, valves, and any potential well heads/well houses. Prior to conducting the field reconnaissance, HDR personnel reviewed orthophotography obtained from NC OneMap GeoSpatial portal (dated 1 2010) to identify potential well heads/well houses and surface waters within a 0.5 mile radius of the ash basin compliance boundary. 1 5 I I Section 3 Water Supply Well Survey Activities In addition, HDR personnel contacted Duke Energy site personnel to identify water supply wells located on Duke Energy property. 3.5 USGS Hydrography Review ' HDR reviewed the United States Geological Survey (USGS) National Hydrography Dataset (NHD) obtained from the USGS National Map Viewer (http://viewer.nationalmap.gov/viewerf) to identify surface waters within a 0.5 mile radius of the ash basin compliance boundary. Hydrography data obtained from the USGS NHD is included on Figure 1. I I I I I I I I 6 I I Section 4 Findings ' Details of the findings from the local and state records review and field survey activities are provided in Sections 4.1 through 4.5. A general summary of the receptor survey findings is provided in Section 4.6. 1 4.1 NCDENR Records Four public water supply wells were identified in the Public Water Supply Water Sources GIS point data set (obtained from NC OneMap GeoSpatial Portal) and on the NCDENR SWAP online database within a 0.5 mile radius of the ash basin compliance boundary. These wells are identified with PWS preceding the Public Water Supply System ID Number. Available well information for the identified public wells is provided in Table 1. The locations of these wells are identified on Figure 1. One of the public wells identified is registered to Duke Energy Carolinas LLC (PWS ID: 0118676). HDR contacted MSS personnel to confirm the location of the well. Mr. George 1 Tolbert, Environmental Coordinator at MSS, confirmed that one water supply well is located on the MSS site in the location depicted by the Public Water Supply Water Sources GIS point data set,as shown on Figure 1. No wellhead protection areas were identified on the NCDENR SWAP online database within a 1 0.5 mile radius of the ash basin compliance boundary. 4.2 Catawba County Records Based on records reviewed, the Catawba County Environmental Health Department has record of four registered private water supply wells located within a 0.5 mile radius of the ash basin compliance boundary. These wells are identified with PRW preceding the identification number as it is referenced to available well information provided in Table 1. The locations of these wells are identified on Figure 1. 1 7 1 Section 4 Findings 4.3 Utility Department Records On August 21, Ms. Tracy Church with the City of Hickory Public Utilities Department indicated the City currently provides municipal water service to 12 of the properties located within a 0.5 mile radius of the ash basin compliance boundary where a water supply well or municipal water service meter was not observed during HDR's field reconnaissance. Ms. Church also indicated that several properties where a water supply well or municipal water service meter was not observed in the field were not currently connected to the City's water 1 service. 4.4 HDR Field Survey During the field reconnaissance, HDR field personnel identified 57 private water supply wells at properties located within a 0.5 mile radius of the ash basin compliance boundary. Fifty-three of the 57 identified wells are included on Figure 1 as "field identified"private water supply wells. Catawba County provided records for 4 of the 57 identified wells, plus the well record for the public water supply well owned by Duke Energy Carolinas, LLC (PWS ID: 0118676). The ' wells that Catawba County had records for are included on Figure 1 as "recorded"private water supply wells. These four wells (PRW-1 through PRW-4), along with the four public water ' supply wells (described in Section 4.1) are the only wells included in Table 1. The locations of the four public water supply wells included in NCDENR's records and located within a 0.5 mile radius of the compliance boundary were confirmed in the field, and by Duke Energy personnel (PWS ID: 0118676). From the public roadway, HDRersonnel identified municipal water service meters for several P p properties located within a 0.5 mile radius of the ash basin compliance boundary along Sherrills Ford Road and the neighborhood where Cape Cove Drive is located. Wells are not shown on Figure 1 at these properties. 1 8 1 ' Section 4 Findings I For properties where water supply wells were not visible from a public right-of-way, HDR was not able to confirm the location or presence of a well. As described in Section 4.3, the City of Hickory indicated that several properties where a water supply well or municipal water service meter was not observed in the field were not currently connected to the City's water service. ' Therefore, it is assumed that the properties which are not currently connected to the City's water service and where a water supply well was not observed from a public right-of-way are supplied water by private water supply wells. Approximate locations based on structures identified during the field reconnaissance and/or orthophotography review are included on Figure 1 as "assumed" private water supply wells. A total of 17 assumed private water supply wells are located within a 0.5 mile radius of the ash basin compliance boundary. Several surface water bodies were identified and/or confirmed during HDR's field reconnaissance. The surface water bodies located within a 0.5 mile radius of the ash basin compliance boundary generally toward Lake Norman from the topographic divide along Sherrills Ford Road. 4.5 Summary of Receptor Survey Findings A summary of the receptor survey fmdings is provided below. The identified water supply wells and surface water bodies are shown on Figure 1. Available property and well information for the 8 water supply wells registered with Catawba County and NCDENR is provided in Table 1. • A total of 57 private water supply wells were identified within a 0.5 mile radius of the ash basin compliance boundary. The Catawba County Environmental Health Department had records for 4 of the 57 identified private water supply wells. • 17 private water supply wells are assumed at residences located within a 0.5 mile radius of the ash basin compliance boundary. • Four public water supply wells were identified within a 0.5 mile radius of the ash basin compliance boundary. The Catawba County Environmental Health Department had records for one of the public water supply wells (PWS ID: 0118676, owned by Duke Energy Carolinas, LLC). I9 I ISection 4 Findings • Several surface water bodies that flow from the topographic divide along Sherrills Ford Road toward Lake Norman were identified within a 0.5 mile radius of the ash basin. I • No wellhead protection areas were identified within a 0.5 mile radius of the ash basin compliance boundary. I I I I I I I I I I I I 1 10 I I NOTES: SCALE (FEET) 1. PARCEL DATA FOR THE SITE WAS OBTAINED FROM DUKE ENERGY REAL ESTATE AND IS APPROXIMATE. 800' 0 800' 1,600' 2. WASTE BOUNDARY AND STRUCTURAL FILL BOUNDARY WERE PROVIDED BY DUKE ENERGY AND ARE APPROXIMATE. 3. ORTHOPHOTOGRAPHY WAS OBTAINED FROM NC ONEMAP GIS WEB SITE (DATED 2010). !" _ 4600' 4. THE COMPLIANCE BOUNDARY IS ESTABLISHED ACCORDING TO THE DEFINITION FOUND IN 15A NCAC 02L .0107 (a). 5. PUBLIC WATER SUPPLY WELL LOCATIONS OBTAINED FROM NCDENR'S PUBLIC WATER SUPPLY WATER SOURCES GIS POINT DATA SET (LAST UPDATED ON NOVEMBER 18, 2009) 6. LOCATION OF PRIVATE WATER SUPPLY WELLS DENOTED AS "PRW" ARE APPROXIMATE AND BASED ON CATAWBA COUNTY ENVIRONMENTAL HEALTH DEPARTMENTS AVAILABLE WELL RECORDS. 7. HYDROGRAPHY WAS OBTAINED FROM THE USGS NATIONAL MAP VIEWER AND DOWNLOAD PLATFORM ON MARCH 24, 2014 (http://nationalmap.gov/viewer.htrnl). F�2 RECEPTOR SURVEY MAP DUKE ENERGY CAROLINAS, LLC MARSHALL STEAM STATION ASH BASIN NPDES PERMIT #NC0004987 CATAWBA COUNTY, NORTH CAROLINA N IARY ARY ARY COINCIDENT IOUNDARY N R SUPPLY WELL PLY WELL LY WELL DATE OCT. 10, 2014 FIGURE 1 I I I I I I I I ITABLES I I I I I 1 RECEIVEDIDENR/DWR OCT 152014 IWater Uuaiity Permitting Section I I I M i M= M M M M = M= M = = == M Table 1 Public and Private Water Supply Wells Within 0.5 Mile Radius of Marshall Ash Basin Compliance Boundary Duke Energy Carolinas, LLC/Marshall Steam Station Well ID Public Water Party ProAddress Reported Well Approximate Distance from Ash Direction Wdl Well Casing well (shown on Figure I) System Name (well location) Pared ID Number Use Basin Compliance from Ash Depth Depth yield Boundary (111) Basin (R-bgs) (R-bgs) m (gp ) PWS 0118621 Midway Restaurant and 8693 E NC 150 Hwy 461708998493 Transient, 2 325 SE 245 N/A Manna Terrell, NC 28682 Non -Community 20 PWS 0118736 The Old Country Church 8455 E NC 150 Hwy 461707773629 Transient' 1225 S-SE N/A N/A 40 Terrell, NC 28682 Non-Community, PWS 0118780 Mott's Grove UNIC 8790 Sherrills Ford Rd g61803100104 Transient, 1,475 SW N/A N/A 40 Sherrdls Ford, NC 28673 Non -Community PWS 01 19676 2 Duke Energy Carolinas LLC 8320 E NC 150 Hwy 461803426350 Non -Transient, 700 S 540 91 30 Terrell, NC 28682 Non-Community1 PRW-1 N/A 2971 Steam Plant Rd 460804939276 Domestic 475 W 185 80 Shemlls Ford, NC 28673 10 PRW-2 N/A 8526 Sherrills Ford Rd 4616030^_ 1923 Domesttc 650 W 205 145 Sherrills Ford, NC 28673 PRW-3 N/A 8883 Sherrills Ford Rd 461701097362 Domestic 2,250 W-SW 240 100Sherrdls Ford, NC 28673 A37 PRW-4 N/A 8846 Greenwood Rd 461709994339 Domestic 1,625 SE 206 108 Terrell, NC 28682 Notes: 1. Public water supply well (PWS) information obtained from NCDENR's Public Water Supply Winer Sources Geographic Information System (GIS) point data set and NCDENR's SWAP online database 2. Well construction information (well depth, casing depth, and well yield) for public well PWS 0118676 obtained from well construction record provided by Catawba County Environmental Health Department. 3. Pnvate water supply well (PRW) information obtained from the Catawba County Environmental Health Department's available records on May 13, 2014. (Note: Catawba County began obtaining well records in 2008 ) 4. Owner and property information for private water supply wells obtained from Catawba County Interactive GIS Website. 5. Distances between well and the Marshall Ash Basin Compliance Boundary are approximate and based on location information provided by NCDENR's data set, Catawba County GIS website, the Catawba County Environmental Health Department records, and observations during HDR's field survey. 6. Non -Transient, Non -Community Well serves at least 25 of the same persons 6+ months per year (e.g., schools, daycares, mdusmes). 7. Transient, Non -Community Well serves 25+ people at least 60 days per year (e.g., restaurants, churches, DOT rest areas). 8. N/A indicates not available 9. ft-bgs indicates feet below ground surface 10. gpm indicates gallons per minute 1. S = South, W = West, SW = Southwest, SE = Southeast, S-SE = South -Southeast, W-SW = West -Southwest Page 1 of 1