HomeMy WebLinkAboutMarshall CSA Work Plan_Final_092514
Marshall Steam Station Ash Basin
Proposed Groundwater
Assessment Work Plan
NPDES Permit NC0004987
September 25, 2014
Duke Energy Carolinas, LLC | Proposed Groundwater Assessment Work Plan
Marshall Steam Station Ash Basin
Table of Contents
i
Table of Contents
Page
Table of Contents ......................................................................................................................... i
Executive Summary .............................................................................................................. ES-1
1.0 Introduction .......................................................................................................................... 1
2.0 Site History........................................................................................................................... 2
2.1 Plant Description ...................................................................................................... 2
2.2 Ash Basin Description ............................................................................................... 2
2.3 Regulatory Requirements ......................................................................................... 3
3.0 Receptor Information ............................................................................................................ 5
4.0 Regional Geology and Hydrogeology ................................................................................... 6
5.0 Site Geology and Hydrogeology ........................................................................................... 7
6.0 Groundwater Monitoring Results .......................................................................................... 8
7.0 Assessment Work Plan ........................................................................................................ 9
7.1 Ash and Soil Sampling Plan ...................................................................................... 9
7.1.1 Boring and Sampling Methods ...................................................................... 9
7.1.2 Proposed Soil and Ash Sampling Locations and Depths ..............................10
7.2 Groundwater Sampling Plan ....................................................................................11
7.2.1 Well Installation and Development ...............................................................12
7.2.2 Hydrogeologic Evaluation .............................................................................12
7.2.3 Groundwater Sampling.................................................................................12
7.3 Surface Water Sampling Plan ..................................................................................13
7.3.1 Ash Basin Surface Water Samples ..............................................................13
7.4 Site Hydrogeologic Conceptual Model .....................................................................13
7.5 Site-Specific Background Concentrations ................................................................13
7.6 Groundwater Model .................................................................................................13
8.0 Proposed Schedule .............................................................................................................15
9.0 References..........................................................................................................................16
Appendix A – Notice of Regulatory Requirements Letter from John E. Skvarla, III, Secretary,
State of North Carolina, to Paul Newton, Duke Energy, dated August 13, 2014.
Duke Energy Carolinas, LLC | Proposed Groundwater Assessment Work Plan
Marshall Steam Station Ash Basin
Table of Contents
ii
List of Figures
1. Site Location Map
2. Site Layout Map
3. Proposed Well and Sample Locations
List of Tables
1. Groundwater Monitoring Requirements
2. Exceedances of 2L Standards
3. Environmental Exploration and Sampling Plan
4. Soil and Ash Parameters and Analytical Methods
5. Groundwater and Surface Water Parameters and Analytical Methods
Duke Energy Carolinas, LLC | Proposed Groundwater Assessment Work Plan
Marshall Steam Station Ash Basin
Executive Summary
ES-1
Executive Summary
Duke Energy Carolinas, LLC (Duke Energy), owns and operates Marshall Steam Station (MSS),
which is located on Lake Norman in Catawba County near the town of Terrell, North Carolina
(see Figure 1). MSS began operation in 1965 as a coal-fired generating station and currently
operates four coal-fired units. The coal ash residue from MSS’s coal combustion process has
historically been disposed in the station’s ash basin located to the north of the station and
adjacent to Lake Norman. The discharge from the ash basin is permitted by the North Carolina
Department of Environment and Natural Resources (NCDENR) Division of Water Resources
(DWR) under the National Pollutant Discharge Elimination System (NPDES) Permit
NC0004987.
On August 13, 2014, NCDENR issued a Notice of Regulatory Requirements (NORR) letter to
Duke Energy, pursuant to Title 15A North Carolina Administrative Code Chapter (15A NCAC)
02L.0106. The NORR stipulates that for each coal-fueled plant owned, Duke Energy will
conduct a comprehensive site assessment (CSA) that includes a Groundwater Assessment
Work Plan (Work Plan) and a receptor survey. In accordance with the requirements of the
NORR, HDR is in the process of completing a receptor survey to identify all receptors within a
0.5-mile radius (2,640 feet) of the MSS ash basin compliance boundary. This receptor survey
will also address the requirements of the General Assembly of North Carolina Session 2013
Senate Bill 729 Ratified Bill (SB 729).
Soil and groundwater sampling will be conducted to provide information pertaining to the
horizontal and vertical extent of potential soil and groundwater contamination. This will be
performed by sampling existing wells, installing and sampling approximately 34 nested
monitoring well pairs (shallow and deep) and one deep (only) monitoring well, and collecting soil
and ash samples. In addition, one observation well will be installed between two outer portions
of the western extent of the ash basin to characterize groundwater flow direction. This work will
provide additional information on the chemical and physical characteristics of site soils and ash,
as well as the geological and hydrogeological features of the site that influence groundwater
flow and direction and potential transport of constituents from the ash basin. Samples of ash
basin water will be collected and used to evaluate potential impacts to groundwater and surface
water. In addition, one water sample may be collected from the surface water located southeast
of the ash basin.
The information obtained through this Work Plan will be utilized to prepare a CSA report in
accordance with the requirements of the NORR. If it is determined that additional investigations
are required during the review of existing data or data developed from this assessment, Duke
Energy and HDR will notify the NCDENR regional office prior to initiating additional sampling or
investigations.
HDR will also perform an assessment of risks to human health or safety and to the
environment. This assessment will include the preparation of a conceptual site model
illustrating potential pathways from the source to possible receptors.
Duke Energy Carolinas, LLC | Proposed Groundwater Assessment Work Plan
Marshall Steam Station Ash Basin
1.0 Introduction
1
1.0 Introduction
Duke Energy Carolinas, LLC (Duke Energy), owns and operates Marshall Steam Station (MSS),
which is located on Lake Norman in Catawba County near the town of Terrell, North Carolina
(see Figure 1). MSS began operation in 1965 as a coal-fired generating station and currently
operates four coal-fired units. The coal ash residue from MSS’s coal combustion process has
historically been disposed in the station’s ash basin located to the north of the station and
adjacent to Lake Norman. The discharge from the ash basin is permitted by the North Carolina
Department of Environment and Natural Resources (NCDENR) Division of Water Resources
(DWR) under the National Pollutant Discharge Elimination System (NPDES) Permit
NC0004987.
On August 13, 2014, NCDENR issued a Notice of Regulatory Requirements (NORR) letter to
Duke Energy, pursuant to Title 15A North Carolina Administrative Code (NCAC) Chapter
02L.0106. The NORR stipulates Duke Energy will conduct a comprehensive site assessment
(CSA) for each owned coal-fueled plant. The CSA will include a Groundwater Assessment
Work Plan (Work Plan) and a receptor survey. In accordance with the requirements of the
NORR, HDR is in the process of completing a receptor survey to identify all receptors within a
0.5-mile radius (2,640 feet) of the MSS ash basin compliance boundary. The NORR letter is
included as Appendix A.
On behalf of Duke Energy, HDR has prepared this proposed Work Plan for performing the
groundwater assessment as prescribed in the NORR. If it is determined that additional
investigations are required during the review of existing data or data developed from this
assessment, Duke Energy and HDR will notify the NCDENR regional office prior to initiating
additional sampling or investigations.
HDR will also perform an assessment of risks to human health or safety and to the
environment. This assessment will include the preparation of a conceptual site model
illustrating potential pathways from the source to possible receptors.
Duke Energy Carolinas, LLC | Proposed Groundwater Assessment Work Plan
Marshall Steam Station Ash Basin
2.0 Site History
2
2.0 Site History
2.1 Plant Description
MSS is a four-unit, coal-fired electric generating plant 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 Hwy 150, east of Sherrills Ford Road and south of Island Point Road, and the
surrounding area generally consists of residential properties, undeveloped land, and Lake
Norman (Figure 1). The ash basin is situated between the MSS to the south, primarily
residences to the west, residences and undeveloped land to the north, and undeveloped land
and Lake Norman to the east. A topographical divide is located along Sherrills Ford Road to the
west and along Island Ford Road to the north. The topography at the site generally slopes
downward from that divide toward Lake Norman.
2.2 Ash Basin Description
The ash basin system consists of a single cell impounded by an earthen dike located on the
southeast end of the ash basin. The ash basin system was constructed in 1965 and is located
approximately 2,000 feet northeast of the power plant. The area contained within the ash basin
waste boundary, which is shown on Figures 2 and 3, is approximately 382 acres in area.
The full pond elevation for the MSS ash basin is approximately 790 feet. The normal pond
elevation of Lake Norman is approximately 760 feet.
The ash basin is operated as an integral part of the station’s wastewater treatment system and
receives inflows from the ash removal system, coal pile runoff, landfill leachate, flue-gas
desulfurization (FGD) wastewater, the station yard drain sump, stormwater flows, and station
wastewater. Due to variability in station operations and weather, inflows to the ash basin are
highly variable. Inflows from the station to the ash basin are discharged into the northwest
portion of the ash basin.
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. The ash basin pond elevation
is controlled by the use of concrete stop logs in the discharge tower.
Note that there are six permitted landfill areas and one structural fill area located adjacent to the
ash basin. Two ash landfills (Permit No. 1804) are located adjacent to the east and northeast
portions of the ash basin. The demolition landfill (Permit No. 1804), asbestos landfill (Permit
No. 1804), and industrial landfill (Permit No. 1812) are located adjacent to the northern portion
of the ash basin. The flue gas desulfurization (FGD) landfill (Permit No. 1809) is located
southwest of the ash basin. The structural fill area is located adjacent to and partially on top of
the western most portion of the ash basin. The approximate boundary of these landfill/structural
fill areas are shown on Figures 2 and 3. Existing groundwater monitoring wells associated with
the ash landfills and the FGD landfill are shown on Figure 3.2.3.
Duke Energy Carolinas, LLC | Proposed Groundwater Assessment Work Plan
Marshall Steam Station Ash Basin
2.0 Site History
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2.3 Regulatory Requirements
The NPDES program regulates wastewater discharges to surface waters to ensure that surface
water quality standards are maintained. MSS operates under NPDES Permit NC0004987 which
authorizes discharge of cooling water and intake screen backwash (Outfall 001); treated
wastewater (consisting of metal cleaning wastes, coal pile runoff, ash transport water, domestic
wastewater, low volume wastes, and FGD wet scrubber wastewater) (Outfall 002); yard sump
overflows (Outfalls 002A and 002B); and non-contact cooling water from the induced draft fan
control house (Outfall 003) to the Catawba River (Lake Norman) in accordance with effluent
limitations, monitoring requirements, and other conditions set forth in the permit.
The NPDES permitting program requires that permits be renewed every five years. The most
recent NPDES permit renewal at MSS became effective on March 1, 2011, and expires April 30,
2015.
In addition to surface water monitoring, the NPDES permit requires groundwater monitoring.
Groundwater monitoring has been performed in accordance with the permit conditions
beginning in February 2011. NPDES Permit Condition A (11), Version 1.1, dated June 15,
2011, lists the groundwater monitoring wells to be sampled, the parameters and constituents to
be measured and analyzed, and the requirements for sampling frequency and reporting results.
These requirements are provided in Table 1.
The compliance boundary for groundwater quality at the MSS ash basin site is defined in
accordance with Title 15A NCAC 02L .0107(a) as being established at either 500 feet from the
waste boundary or at the property boundary, whichever is closer to the waste. The location of
the ash basin compliance monitoring wells, the ash basin waste boundary, and the compliance
boundary are shown on Figure 2.
The locations for the compliance groundwater monitoring wells were approved by the NCDENR
DWR Aquifer Protection Section (APS). All compliance monitoring wells included in Table 1 are
sampled three times per year (in February, June, and October). Analytical results are submitted
to DWR before the last day of the month following the date of sampling for all compliance
monitoring wells.
The compliance groundwater monitoring system for the MSS ash basin consists of the following
monitoring wells: MW -4, MW -4D, MW -10S, MW-10D, MW-11S, MW-11D, MW-12S, MW -12D,
MW -13S, MW -13D, MW -14S, and MW -14D (shown on Figures 2 and 3). With the exception of
monitoring wells MW -4 and MW -4D, all the compliance monitoring wells were installed in 2010.
Monitoring well MW -4 was installed by Duke Energy in 1989 as part of the Marshall Dry Ash
Landfill (Permit No. 1804) groundwater monitoring network. Monitoring well MW -4D was
installed by Duke Energy in 2006 as part of a voluntary monitoring system. Based on the
locations of monitoring wells MW -4 and MW -4D relative to the ash basin, they were
incorporated into the ash basin compliance monitoring network.
One or more groundwater quality standards (2L Standards) have been exceeded in
groundwater samples collected at monitoring wells MW -4, MW-4D, MW -10S, MW -10D, MW-
11S, MW -11D, MW -12S, MW -12D, MW-13S, MW-13D, MW-14S, and MW-14D. Exceedances
Duke Energy Carolinas, LLC | Proposed Groundwater Assessment Work Plan
Marshall Steam Station Ash Basin
2.0 Site History
4
have occurred for boron, iron, manganese, pH, sulfate, and/or total dissolved solids (TDS).
Table 2 presents exceedances measured from February 2011 through June 2014.
Monitoring wells MW -41, MW -10S2, MW-11S, MW-12S, MW -13S, and MW -14S were installed
with 10-foot to 15-foot well screens placed above auger refusal to monitor the shallow aquifer
within the saprolite layer. These wells were installed to total depths ranging from 18 feet below
ground surface (bgs) at MW -13S to 52 feet bgs at MW -11S.
Monitoring wells MW -4D3, MW -10D, MW-11D, MW-12D, MW -13D, and MW-14D were installed
with 5-foot well screens placed in the fractured rock transition zone. These wells were installed
to total depths ranging from 46.5 feet bgs at MW -13D to 95 feet bgs at MW-12D.
Note that monitoring wells MW -6S, MW-6D, MW -7S, MW-7D, MW-8S, MW-8D, MW -9S, and
MW -9D were installed by Duke Energy in 2006 as part of a voluntary monitoring system. No
groundwater samples are currently collected from these wells under the compliance monitoring
program. The voluntary wells are shown on Figure 3.
1 Duke Power Company, Marshall Steam Station, Dry Ash Landfill, Monitoring Well Drill Records, July
1989.
2 Wells other than MW -4 and MW -4D have the boring log and well record found in MACTEC’s Ash Basin
Monitoring Well Installation Report (MACTEC Project No. 6228-10-5284) dated August 26, 2010.
3 S&ME, Inc., Ash Basin Monitoring Well Installation, Duke Power-Marshall Steam Station, S&ME Project
No. 1356-06-834, December 4, 2006.
Duke Energy Carolinas, LLC | Proposed Groundwater Assessment Work Plan
Marshall Steam Station Ash Basin
3.0 Receptor Information
5
3.0 Receptor Information
The August 13, 2014 NORR states:
No later than October 14th, 2014 as authorized pursuant to 15A NCAC 02L
.0106(g), the DWR is requesting that Duke perform a receptor survey at each of
the subject facilities and submitted to the DWR. The receptor survey is required
by 15A NCAC 02L .0106(g) and shall include identification of all receptors within
a radius of 2,640 feet (one-half mile) from the established compliance boundary
identified in the respective National Pollutant Discharge Elimination System
(NPDES) permits. Receptors shall include, but shall not be limited to, public and
private water supply wells (including irrigation wells and unused or abandoned
wells) and surface water features within one-half mile of the facility compliance
boundary. For those facilities for which Duke has already submitted a receptor
survey, please update your submittals to ensure they meet the requirements
stated in this letter and referenced attachments and submit them with the others.
If they do not meet these requirements, you must modify and resubmit the plans.
The results of the receptor survey shall be presented on a sufficiently scaled
map. The map shall show the coal ash facility location, the facility property
boundary, the waste and compliance boundaries, and all monitoring wells listed
in the respective NPDES permits. Any identified water supply wells shall be
located on the map and shall have the well owner's name and location address
listed on a separate table that can be matched to its location on the map.
In accordance with the requirements of the NORR, HDR is in the process of completing a
receptor survey for MSS to identify all receptors within a 0.5-mile radius (2,640 feet) of the ash
basin compliance boundary to be submitted to NCDENR no later than October 1, 2014. This
receptor survey will also address the requirements of the General Assembly of North Carolina
Session 2013 Senate Bill 729 Ratified Bill (SB 729). The receptors include, but are not limited
to, public and private water supply wells (including irrigation wells and unused or abandoned
wells) and surface water features within a 0.5-mile radius of the MSS ash basin compliance
boundary. The compliance boundary for groundwater quality, in relation to the ash basin, is
defined in accordance with Title 15A NCAC 02L .0107(a) as being established at either 500 feet
from the waste boundary or at the property boundary, whichever is closer to the source.
The receptor survey will include a map showing the coal ash facility location, the facility property
boundary, the waste and compliance boundaries, and all monitoring wells listed in the NPDES
permit. The identified water supply wells will be located on the map and the well owner's name
and location address listed on a separate table that can be matched to its location on the map.
During completion of the CSA, HDR will update the receptor information as necessary, in
general accordance with the CSA receptor survey requirements. If necessary, an updated
receptor survey will be submitted with the CSA report.
Duke Energy Carolinas, LLC | Proposed Groundwater Assessment Work Plan
Marshall Steam Station Ash Basin
4.0 Regional Geology and Hydrogeology
6
4.0 Regional Geology and Hydrogeology
North Carolina is divided into distinct regions by portions of three physiographic provinces: the
Atlantic Coastal Plain, Piedmont, and Blue Ridge (Fenneman, 1938). MSS is located in the
Charlotte terrane within the Piedmont province. The Piedmont province is bounded to the east
and southeast by the Atlantic Coastal Plain and to the west by the escarpment of the Blue Ridge
Mountains, covering a distance of 150 to 225 miles (LeGrand, 2004).
The topography of the Piedmont region is characterized by low, rounded hills and long, rolling,
northeast-southwest trending ridges (Heath, 1984). Stream valley to ridge relief in most areas
range from 75 to 200 feet. Along the Coastal Plain boundary, the Piedmont region rises from an
elevation of 300 feet above mean sea level, to the base of the Blue Ridge Mountains at an
elevation of 1,500 feet (LeGrand, 2004).
Charlotte terrane bedrock consists primarily of igneous and metamorphic bedrock. The
fractured bedrock is overlain by a mantle of unconsolidated material known as regolith. The
regolith includes, where present, the soil zone (a zone of weathered, decomposed bedrock
known as saprolite) and, where present, alluvium. Saprolite, the product of chemical and
mechanical weathering of the underlying bedrock, is typically composed of clay and coarser
granular material up to boulder size and may reflect the texture of the rock from which it was
formed. The weathering product of granitic rocks are quartz rich and sandy textured; whereas,
rocks poor in quartz and rich in feldspar and other soluble minerals form a more clayey
saprolite. The regolith serves as the principal storage reservoir for the underlying bedrock
(LeGrand 2004).
A transition zone may occur at the base of the regolith between the soil-saprolite and the
unweathered bedrock. This transition zone of partially weathered rock is a zone of relatively
high permeability compared to the overlying soil-saprolite and the underlying bedrock (LeGrand
2004).
Groundwater flow paths in the Piedmont are almost invariably restricted to the zone underlying
the topographic slope extending from a topographic divide to an adjacent stream. LeGrand
describes this as the local slope aquifer system. Under natural conditions, the general direction
of groundwater flow can be approximated from the surface topography (LeGrand 2004).
Groundwater recharge in the Piedmont is derived entirely from infiltration of local precipitation.
Groundwater recharge occurs in areas of higher topography (i.e., hilltops) and groundwater
discharge occurs in lowland areas bordering surface water bodies, marshes, and floodplains
(LeGrand 2004).
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Marshall Steam Station Ash Basin
5.0 Site Geology and Hydrogeology
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5.0 Site Geology and Hydrogeology
Based on a review of soil boring and monitoring well installation logs provided by Duke Energy,
subsurface stratigraphy consists of the following material types: fill, ash, residuum, saprolite,
partially weathered rock (PWR), and bedrock. In general, saprolite, PWR, and bedrock were
encountered on most areas of the site. Bedrock was encountered across the site ranging in
depth from 36 feet on the northwest extent of the site to 94 feet along the western extent of the
site and to approximately 85 feet on the southeastern extent of the site near Lake Norman. The
general stratigraphic units, in sequence from the ground surface down to boring termination, are
defined as follows:
Fill – Fill material generally consisted of re-worked silts and clays that were borrowed from
one area of the site and re-distributed to other areas. Fill was used in the construction of
dikes and presumably as cover for the landfill and structural fill areas.
Ash – Although previous exploration activities, for which Duke Energy provided boring logs,
did not evaluate ash management areas of the site, ash is expected to be present within the
ash basin, ash landfill areas, and the structural fill area.
Alluvium – Alluvium was not encountered in the boring information provided to HDR.
However, alluvium is expected to be present beneath the southeastern portion of the ash
basin where streams likely existed and flowed toward the Catawba River prior to
construction of the ash basin. Alluvium is unconsolidated soil and sediment that has been
eroded and redeposited by streams and rivers.
Residuum – Residuum is the in-place weathered soil that generally consists of white,
yellow, red, brown, gray, or olive sandy clay to silty sand. This unit was encountered in
various thicknesses across the site.
Saprolite – Saprolite is soil developed by in-place weathering of rock similar to the bedrock
that consists of white, brown, orange, yellow, red, gray, or green silty sand and sandy silt
with trace mica. The primary distinction from residuum is that saprolite typically retains some
structure (e.g., mineral banding) from the parent rock. This unit was found in areas across
the site and was described as white, brown, orange, yellow, red, gray, or greenish-brown
silty sand, course to fine sand, and sandy silt with manganese staining, some quartz rock
fragments, and trace mica.
Partially Weathered Rock (PWR) – PWR occurs between the saprolite and bedrock and
contains saprolite and rock remnants. This unit was described as white, black, gray, and
green medium to very fine sand and sandy silty clay with some rock fragments and
manganese staining.
Bedrock – Bedrock was encountered in borings completed around the western, northern,
and southeastern extents of the ash basin. Depth to top of bedrock ranged from 36 feet to
94 feet below ground surface. Bedrock was described as biotite-gneiss, quartz-sericite
schist, and granite.
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Marshall Steam Station Ash Basin
6.0 Groundwater Monitoring Results
8
6.0 Groundwater Monitoring Results
From February 2001 through June 2014, the compliance groundwater monitoring wells at MSS
have been sampled a total of 11 times. During this period, these monitoring wells were sampled
in:
February 2011
June 2011
October 2011
February 2012
June 2012
October 2012
February 2013
June 2013
October 2013
February 2014
June 2014
With the exception of boron, iron, manganese, pH, sulfate, and TDS, the results for all
monitored parameters and constituents were less than the 2L Standards. Table 2 lists the
range of exceedances for boron, iron, manganese, pH, sulfate, and TDS for the sampling
events listed above.
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Marshall Steam Station Ash Basin
7.0 Assessment Work Plan
9
7.0 Assessment Work Plan
Soil and groundwater sampling will be performed to provide information pertaining to the
horizontal and vertical extent of potential soil and groundwater contamination. Based on readily
available site background information, and dependent upon accessibility, HDR anticipates
collecting soil and/or ash samples from 5 soil boring locations and during installation of
approximately 34 nested monitoring well pairs (shallow and deep) and one deep (only)
monitoring well. Groundwater samples will be collected from the proposed monitoring wells. In
addition, one observation well will be installed between two outer portions of the western extent
of the ash basin to characterize groundwater flow direction. The proposed well and boring
locations are listed in Table 3 and shown on Figure 3. HDR may also resample select existing
monitoring wells to supplement groundwater quality data. This work will provide additional
information on the chemical and physical characteristics of site soils and ash, as well as the
geological and hydrogeological features of the site that influence groundwater flow and direction
and potential transport of constituents from the ash basin.
Samples of ash basin water will also be collected and used to evaluate potential impacts to
groundwater and surface water. In addition, one water sample may be collected from the
surface water located southeast of the ash basin (SW -6) shown on Figure 3.
A summary of the proposed exploration plan, including estimated sample quantities and depths
of soil borings and monitoring wells, is presented in Table 3. If it is determined that additional
investigations are required during the review of existing data or data developed from this
assessment, Duke Energy and HDR will notify the NCDENR regional office prior to initiating
additional sampling or investigations.
7.1 Ash and Soil Sampling Plan
7.1.1 Boring and Sampling Methods
Prior to drilling each boring, all downhole equipment and tools will be cleaned by washing with
high pressure hot water. A designated remote cleaning area will be established in the field.
Water for cleaning will be obtained from a tap or hydrant (to be designated) at MSS, or supplied
by the drilling contractor from an off-site source. Cleaning water will not require collection,
treatment, or disposal.
Borings will be advanced using hollow stem auger or roller cone drilling techniques to facilitate
collection of downhole data. Standard Penetration Testing (SPT) (ASTM D 1586) and split-
spoon sampling will be performed at 2.5-foot to 5-foot increments using an 18-inch split-spoon
sampler. The sampler will be decontaminated with a non-phosphate detergent wash between
sampling depths. Ash and soil samples will be collected by the Project Scientist/Engineer.
Borings will be logged by the Project Scientist/Engineer and ash/soil samples will be observed,
visually classified, and photographed in the field for origin, consistency/relative density, color,
and soil type in accordance with the Unified Soil Classification System (ASTM D2487/D2488).
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Marshall Steam Station Ash Basin
7.0 Assessment Work Plan
10
Samples will be identified with a unique boring number and approximate collection depth (e.g.,
AB-1 (20-22’)). Sample containers will be provided by HDR’s contracted laboratory prior to
commencement of the on-site investigation. Samples will be delivered to the analytical
laboratory in time to extract the samples within their specified hold times (to be provided by the
laboratory). HDR will provide the name, phone number, and email address of the laboratory
project manager to facilitate sample analysis coordination.
Boring locations will be surveyed for horizontal and vertical control upon completion of the field
exploration program.
7.1.2 Proposed Soil and Ash Sampling Locations and Depths
HDR anticipates collection of soil and ash samples for laboratory analysis at 21 locations within
the ash basin and on the ash basin dike (designated as AB-1 through AB-21), four locations
within and immediately adjacent to the ash landfill areas (designated as AL-1 through AL-4),
and five soil boring locations in the ash basin and structural fill area (designated as S-1 through
S-5). The borings located within the ash basin, ash landfill areas, and the structural fill area will
extend approximately 20 feet below the ash/native soil interface or to refusal, whichever is
encountered first. In addition, HDR anticipates collection of soil samples at three background
locations (designated as BG-1 through BG-3).
Soil samples will not be collected for laboratory analysis during installation of monitoring wells
located outside the ash basin waste boundary, the structural fill, and ash landfill areas
(designated as GWA-1 through GWA-7). Proposed boring/well locations are shown on Figure
3.
CONSTITUENT SAMPLING AND ANALYSES
In general, ash is expected to be encountered in AB-series, AL-series, and S-series borings
located within the ash basin, the ash landfill areas, and the structural fill area. Where present,
ash samples will be collected from shallow and deeper vertical intervals to evaluate variations in
type (e.g., fly ash or bottom ash) and chemical profile of the ash. In locations where ash
thickness is expected to be greater than 30 feet, a third ash sample may be collected from a
depth mid-way between the shallow and deeper intervals in a particular boring. Shallow ash
samples will be collected from the 4-foot to 5-foot interval and deeper ash samples will be
collected from the 1-foot to 2-foot interval overlying the ash/native soil interface. The depth of
deeper ash samples is expected to vary based on ash thickness at each specific boring
location. Ash samples will be analyzed by HDR’s subcontract laboratory for total and leachable
inorganic compounds, as presented in Table 4.
Soil samples will be collected below the ash/native soil interface and from the terminus of each
boring to characterize soil quality beneath the ash management areas. Soil samples will be
analyzed by HDR’s subcontract laboratory for total inorganics using the same constituents list
proposed for the ash samples.
INDEX PROPERTY SAMPLING AND ANALYSES
Physical characteristics of ash and soil will be tested both in the field and in the laboratory to
provide data for use in groundwater modeling. The location and depth of the index property
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Marshall Steam Station Ash Basin
7.0 Assessment Work Plan
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samples will be based on site-specific geology and decided upon in the field. Based on HDR’s
current understanding of site-specific geology, five hydrostratigraphic units are present on-site.
In general, a minimum of five in-situ permeability tests, either falling or constant head tests, will
be performed in each of the hydrostratigraphic units. In addition, a minimum of five packer tests
will be performed in bedrock.
Laboratory testing of soil and ash collected from SPT samples will include tests for grain size
(with hydrometer), specific gravity, and porosity (calculation).
7.2 Groundwater Sampling Plan
Groundwater samples will be collected from the proposed 34 nested well pairs (shallow and
deep) and one deep (only) monitoring well shown on Figure 3. Groundwater quality data may
be supplemented through evaluation of historical data or re-sampling of select existing
monitoring wells. The purpose and anticipated construction details of the proposed monitoring
wells are as follows:
AB-series Wells – One shallow well screened across the water table (10-foot to 15-foot
well screen) and one deep well screened in the transition zone (5-foot well screen in
weathered rock below auger refusal) will be installed at each location. The AB-series
well locations were selected to provide water quality data in and beneath the ash basin
waste boundary.
AL-series Wells – One shallow well screened across the water table (15-foot well
screen) and one deep well screened in the transition zone (5-foot well screen in
weathered rock below auger refusal) will be installed at locations AL-1 through AL-3. A
deep well only will be installed at location AL-4. The AL-series well locations were
selected to provide water quality data beneath and adjacent to the ash landfill areas
located along the east/northeast extents of the ash basin (i.e., to evaluate potentially
impacted groundwater beneath the ash landfills and adjacent to the ash basin).
GWA-series Wells – One shallow well screened across the water table (15-foot well
screen) and one deep well screened in the transition zone (5-foot well screen in
weathered rock below auger refusal) will be installed at each location. The GWA-series
well locations were selected to provide water quality data beyond the waste boundary for
use in groundwater modeling (i.e., to evaluate the horizontal and vertical extent of
potentially impacted groundwater around the ash basin).
OB-series wells – The observation well (OB-1) will be installed with a 20-foot screen
(across the water table) and will be used for measuring water levels only (no water
quality samples). OB-1 will be installed between two outer portions of the western extent
of the ash basin. The purpose of OB-1 is to characterize groundwater flow in this area.
BG-series Wells – One shallow well screened across the water table (15-foot well
screen) and one deep well screened in the transition zone (5-foot well screen in
weathered rock below auger refusal) will be installed at each location. The background
well locations were selected to provide additional physical separation from possible
influence of the ash basin on groundwater. These wells will also be useful in the
Duke Energy Carolinas, LLC | Proposed Groundwater Assessment Work Plan
Marshall Steam Station Ash Basin
7.0 Assessment Work Plan
12
statistical analysis to determine the site-specific background water quality concentrations
(SSBCs).
7.2.1 Well Installation and Development
SHALLOW MONITORING WELLS
At each monitoring well location specified on Figure 3 with an “S” qualifier in the well name (e.g.,
AB-1S), a shallow well will be constructed with a 2-inch-diameter, schedule 40 PVC screen and
casing. Each of these wells will have a 10-foot to 15-foot well screen (0.010-slot) set to bracket
the water table at the time of installation.
DEEP MONITORING WELLS
At each monitoring well location specified on Figure 3 with a “D” qualifier in the well name (e.g.,
AB-1D), a double-cased deep well will be constructed with a 6-inch-diameter PVC outer casing
and a 2-inch-diameter PVC inner casing and well screen. The purpose of installing cased wells
at the site is to restrict vertical mixing within the shallow and deeper portions of the unconfined
aquifer during well installation. Outer well casings (6-inch casing) will be advanced to auger
refusal and set approximately 1 foot into PWR. Note that location-specific subsurface geology
will dictate actual casing depths on a per-well basis. Air rotary drilling will be used to advance
the borehole a minimum of 10 feet into PWR or bedrock with the intent of setting a 5-foot well
screen at least 10 feet below the bottom of the outer casing.
All newly installed monitoring wells will be developed using appropriate measures (e.g.,
agitation, surging, pumping, etc.). Water quality parameters (specific conductance, pH,
temperature and turbidity) will be measured and recorded during development and should
stabilize before development is considered complete. Development will continue until
development water is visually clear (target < 50 Nephelometric Turbidity Units (NTU) Turbidity)
and sediment free. Following development, sounding the bottom of the well with a water level
meter should indicate a “hard” (sediment-free) bottom. Development records will be prepared
under the direction of the Project Scientist/Engineer and will include development method(s),
water volume removed, and field measurements of temperature, pH, conductivity, and turbidity.
7.2.2 Hydrogeologic Evaluation
Hydraulic conductivity (slug) tests will be completed in select monitoring wells under the
direction of the Project Scientist/Engineer. Slug tests will be performed to meet the
requirements of the NCDENR Memorandum titled, “Performance and Analysis of Aquifer Slug
Tests and Pumping Tests Policy,” dated May 31, 2007. Water level change during the slug
tests will be recorded by a data logger.
In addition, approximately 5 to 10 packer tests will be conducted during installation of the Type
III wells to facilitate permeability testing of the upper five feet of rock.
7.2.3 Groundwater Sampling
Subsequent to monitoring well installation and development, each newly installed well will be
sampled using low-flow sampling techniques. During low-flow purging and sampling,
groundwater is pumped into a flow-through chamber at flow rates that minimize or stabilize
water level drawdown within the well. Indicator parameters are measured over time (usually at
Duke Energy Carolinas, LLC | Proposed Groundwater Assessment Work Plan
Marshall Steam Station Ash Basin
7.0 Assessment Work Plan
13
5-minute intervals). When parameters have stabilized within ±0.2 pH units and ±10 percent for
temperature, conductivity, and dissolved oxygen (DO), and ±10 millivolts (mV) for oxidation
reduction potential (ORP) over three consecutive readings, representative groundwater has
been achieved for sampling. Turbidity levels of 10 NTU or less will be targeted prior to sample
collection. Groundwater samples will be analyzed by a North Carolina certified laboratory for
the constituents included in Table 5. Select constituents may be analyzed for total and
dissolved concentrations.
7.3 Surface Water Sampling Plan
7.3.1 Ash Basin Surface Water Samples
Surface water samples will be collected from the ash basin at the approximate open water
locations shown on Figure 3 (SW-1 through SW -5). At each location two water samples will be
collected – one sample close to the surface (i.e., 0 to 1 foot from surface) and one sample at the
approximate middle depth of the water body. The middle depth sample will vary based on the
water level in the water body. In areas where the water body is less than 5 feet deep, one water
sample will be collected from the location at the approximate middle depth of the water body. In
addition, one water sample may be collected from the surface water located southeast of the
ash basin (SW -6) shown on Figure 3. Surface water samples will be analyzed for the same
constituents as groundwater samples (Table 5). Select constituents may be analyzed for total
and dissolved concentrations.
7.4 Site Hydrogeologic Conceptual Model
The data obtained during the proposed assessment will be supplemented by available reports
and data on site geotechnical, geologic, and hydrologic conditions to develop a site
hydrogeologic conceptual model (SCM). The NCDENR document, “Hydrogeologic Investigation
and Reporting Policy Memorandum,” dated May 31, 2007 (Reference 6), will be used as general
guidance. In general, the SCM will utilize site information to characterize the geologic and
hydrogeologic characteristics of the area of interest, and, where appropriate, lead directly to the
proper construction of a groundwater flow and transport model.
7.5 Site-Specific Background Concentrations
Statistical analysis will be performed to determine the SSBCs to assess whether or not
exceedances can be attributed to naturally occurring background concentrations or attributed to
potential contamination. Specifically, the relationship between exceedances and turbidity will be
explored to determine whether or not there is a possible correlation due to naturally occurring
conditions and/or well construction.
7.6 Groundwater Model
Groundwater flow and chemical constituent fate and transport at the site will be modeled in
three dimensions using the MODFLOW -2005 groundwater flow numeric engine and the MT3D
transport model with linear isotherm sorption to predict chemical constituent concentrations over
time at the compliance boundary.
Duke Energy Carolinas, LLC | Proposed Groundwater Assessment Work Plan
Marshall Steam Station Ash Basin
7.0 Assessment Work Plan
14
The groundwater model layers will be developed based on hydrogeologic properties and other
data obtained during the site investigation and the SCM. The model will include the effects of
recharge from precipitation.
Site soil samples will be collected and used to develop site-specific distribution coefficient, Kd,
terms using batch methods (“US EPA Batch-type procedures for estimating soil adsorption of
chemicals Technical Resource Document 530/SW-87/006-F”).
The selection of the initial concentrations and the predictions of the concentrations for
constituents with respect to time are to be developed with consideration of the following data:
Site-specific analytical results from leach tests and from total digestion of ash samples
taken at varying locations and depths within the ash basin and ash storage piles (if
present).
Analytical results from appropriate groundwater monitoring wells or surface water
sample locations outside of the ash basin.
Analytical results from monitoring wells installed in the ash basin pore-water (screened
in ash).
Published or other data on sequential leaching tests performed on similar ash.
The groundwater modeling will be conducted in general conformance with the requirements of
the May 31, 2007, NCDENR Memorandum titled, “Groundwater Modeling Policy.”
The groundwater model and the report on the results of the groundwater modeling will be
prepared by Dr. William Langley, P.E., Department of Civil and Environmental Engineering,
University of North Carolina at Charlotte. Dr. Langley will perform the work under contract with
HDR and the groundwater model report will be included as an attachment to the CSA. The
groundwater model will be used, as required, to evaluate options for potential corrective action
in the subsequent phase of work.
Duke Energy Carolinas, LLC | Proposed Groundwater Assessment Work Plan
Marshall Steam Station Ash Basin
8.0 Proposed Schedule
15
8.0 Proposed Schedule
Duke Energy will submit the CSA Report within 180 days of NCDENR approval of this Work
Plan. The anticipated schedule for implementation of field work, evaluation of data, and
preparation of the Work Plan is presented in the table below.
Activity Start Date Duration to Complete
Field Exploration Program 10 days following Work Plan approval 75 days
Receive Laboratory Data 14 days following end of Exploration Program 15 days
Evaluate Lab/Field Data, Develop SCM 5 days following receipt of Lab Data 30 days
Prepare and Submit CSA 10 days following Work Plan approval 170 days
Duke Energy Carolinas, LLC | Proposed Groundwater Assessment Work Plan
Marshall Steam Station Ash Basin
9.0 References
16
9.0 References
1. Fenneman, Nevin Melancthon. “Physiography of eastern United States.” McGraw-Hill.
1938.
2. Heath, R.C., 1984, “Ground-water regions of the United States.” U.S. Geological Survey
Water-Supply Paper 2242, 78 p.
3. LeGrand, Harry E. 2004. “A Master Conceptual Model for Hydrogeological Site
Characterization in the Piedmont and Mountain Region of North Carolina, A Guidance
Manual,” North Carolina Department of Environment and Natural Resources Division of
Water Quality, Groundwater Section.
4. NCDENR Memorandum “Performance and Analysis of Aquifer Slug Tests and Pumping
Tests Policy,” May 31, 2007.
5. NCDENR document, “Hydrogeologic Investigation and Reporting Policy Memorandum,”
dated May 31, 2007.
6. US EPA Batch-type procedures for estimating soil adsorption of chemicals Technical
Resource Document 530/SW -87/006-F.
Figures
SITE LOCATION MAP
MARSHALL STEAM STATION
_ DUKE ENERGY CAROLINAS, LLC
CATAWBA COUNTY, NORTH CAROLINA
SEPTEMBER 2014
FIGURE
1
NOTES:
1. PARCEL DATA FOR THE SITE WAS OBTAINED FROM DUKE ENERGY REAL ESTATE AND IS APPROXIMATE. SCALE (FEET)
2. WASTE BOUNDARY AND ASH STORAGE AREA BOUNDARY ARE APPROXIMATE. "'oo' o boo
3. AS -BUILT MONITORING WELL LOCATIONS PROVIDED BY DUKE ENERGY. ®_
4. COMPLIANCE SHALLOW MONITORING WELLS (S) ARE SCREENED ACROSS THE SURFICIAL WATER TABLE. r / 000'
5. COMPLIANCE DEEP MONITORING WELLS (D) ARE SCREENED IN THE TRANSITION ZONE BETWEEN COMPETENT BEDROCK AND THE REGOLITH.
6. TOPOGRAPHY DATA FOR THE SITE WAS OBTAINED FROM NC DOT GEOGRAPHIC INFORMATION SYSTEM (GIS) WEB SITE (DATED 2007).
7. AERIAL PHOTOGRAPHY WAS OBTAINED FROM WSP DATED APRIL 2014.
8. THE COMPLIANCE BOUNDARY IS ESTABLISHED ACCORDING TO THE DEFINITION FOUND IN 15A NCAC 02L.0107 (a).
SITE LAYOUT MAP
DUKE ENERGY CAROLINAS, LLC
MARSHALL STEAM STATION ASH BASIN
NPDES PERMIT NO. NC0004987
CATAWBA COUNTY, NORTH CAROLINA
N
LEGEND:
DUKE ENERGY PROPERTY BOUNDARY
ASH BASIN WASTE BOUNDARY
LANDFILL/STRUCTURAL FILL BOUNDARY
ASH BASIN COMPLIANCE BOUNDARY
ASH BASIN COMPLIANCE BOUNDARY COINCIDENT
WITH DUKE PROPERTY BOUNDARY
STREAM
TOPOGRAPHIC CONTOUR (4-FT INTERVAL)
ASH BASIN COMPLIANCE GROUNDWATER
MONITORING WELL
DATE
9/25/2014
FIGURE
2
NOTES:
1. PARCEL DATA FOR THE SITE WAS OBTAINED FROM DUKE ENERGY REAL ESTATE AND IS APPROXIMATE.
2. WASTE BOUNDARY AND ASH STORAGE AREA BOUNDARY ARE APPROXIMATE. SCALE (FEET)
3. AS -BUILT MONITORING WELL LOCATIONS PROVIDED BY DUKE ENERGY. Soo' 0 boo,
4. COMPLIANCE SHALLOW MONITORING WELLS (S) ARE SCREENED ACROSS THE SURFICIAL WATER TABLE.
5. COMPLIANCE DEEP MONITORING WELLS (D) ARE SCREENED IN THE TRANSITION ZONE BETWEEN COMPETENT BEDROCK AND THE REGOLITH. ���
6. TOPOGRAPHY DATA FOR THE SITE WAS OBTAINED FROM NC DOT GEOGRAPHIC INFORMATION SYSTEM (GIS) WEB SITE (DATED 2007).
7. AERIAL PHOTOGRAPHY WAS OBTAINED FROM WSP DATED APRIL 2014.
8. THE COMPLIANCE BOUNDARY IS ESTABLISHED ACCORDING TO THE DEFINITION FOUND IN 15A NCAC 02L.0107 (a).
9. PROPOSED SOIL BORING AND WELL LOCATIONS ARE APPROXIMATE AND MAY BE ADJUSTED BASED ON FIELD CONDITIONS.
10. WLO = WATER LEVEL ONLY
LEGEND:
DUKE ENERGY PROPERTY BOUNDARY
ASH BASIN WASTE BOUNDARY
LANDFILL/STRUCTURAL FILL BOUNDARY
ASH BASIN COMPLIANCE BOUNDARY
ASH BASIN COMPLIANCE BOUNDARY COINCIDENT
WITH DUKE PROPERTY BOUNDARY
STREAM
TOPOGRAPHIC CONTOUR (4-FT INTERVAL)
!� ASH BASIN COMPLIANCE GROUNDWATER
�l MONITORING WELL
ASH BASIN VOLUNTARY GROUNDWATER
MONITORING WELL
LANDFILL GROUNDWATER MONITORING WELL
(FOR ASH LANDFILLS AND FGD RESIDUE LANDFILL)
PROPOSED SOIL BORING/GROUNDWATER
MONITORING WELL LOCATION
PROPOSED OBSERVATION WELL (SEE NOTE 10)
O PROPOSED SOIL BORING LOCATION
• PROPOSED SURFACE WATER SAMPLE LOCATION
PROPOSED WELL AND SAMPLE LOCATIONS
DUKE ENERGY CAROLINAS, LLC
MARSHALL STEAM STATION ASH BASIN
NPDES PERMIT NO. NC0004987
CATAWBA COUNTY, NORTH CAROLINA
DATE
9/25/2014
FIGURE
3
Tables
Table 1 – Groundwater Monitoring Requirements
Well Nomenclature Constituents and Parameters Frequency
Monitoring Wells: MW-4, MW-4D,
MW-10S, MW-10D, MW-11S, MW-
11D, MW-12S, MW-12D, MW-13S,
MW-13D, MW-14S, MW-14D
Antimony Chromium Nickel Thallium
February,
June,
October
Arsenic Copper Nitrate Water Level
Barium Iron pH Zinc
Boron Lead Selenium
Cadmium Manganese Sulfate
Chloride Mercury TDS
TABLE 2 – EXCEEDANCES OF 2L STANDARDS FEBRUARY 2011 – JUNE 2014
Parameter Boron Iron Manganese pH Sulfate
Total
Dissolved
Solids
Units µg/L µg/L µg/L SU mg/L mg/L
2L Standard 700 300 50 6.5 - 8.5 250 500
Well ID Range of Exceedances
MW-4 No
Exceedances
No
Exceedances
No
Exceedances 5.5 – 6.0 No
Exceedances
No
Exceedances
MW-4D No
Exceedances 376 No
Exceedances 5.9 – 6.2 No
Exceedances
No
Exceedances
MW-10S No
Exceedances 373 – 616 65 5.1 – 5.7 No
Exceedances
No
Exceedances
MW-10D No
Exceedances 371 – 406 59 – 97 6.2 – 6.4 No
Exceedances
No
Exceedances
MW-11S No
Exceedances 324 – 467 No
Exceedances 5.9 – 6.4 No
Exceedances
No
Exceedances
MW-11D No
Exceedances 325 – 839 No
Exceedances
No
Exceedances
No
Exceedances
No
Exceedances
MW-12S No
Exceedances
No
Exceedances 54 – 127 4.9 – 5.7 No
Exceedances
No
Exceedances
MW-12D No
Exceedances 305 – 970 No
Exceedances 5.9 – 6.4 No
Exceedances
No
Exceedances
MW-13S No
Exceedances 324 – 1,470 54 5.8 – 6.3 No
Exceedances
No
Exceedances
MW-13D No
Exceedances
No
Exceedances
No
Exceedances 5.9 – 6.4 No
Exceedances
No
Exceedances
MW-14S 3,190 – 4,530 322 – 1,270 66 – 192 5.2 – 5.5 280 – 400 570 – 650
MW-14D 2,750 – 3,660 No
Exceedances 51 – 73 5.3 – 5.6 270 – 310 510 – 540
TABLE 3 – ENVIRONMENTAL EXPLORATION AND SAMPLING PLAN
MARSHALL STEAM STATION
Exploration
Area Soil Borings Shallow Monitoring Wells Deep Monitoring Wells Surface Water
Boring IDs Quantity
Estimated
Boring Depth
(ft bgs)
Well IDs Quantity
Estimated
Well Depth
(ft bgs)
Screen
Length
(ft)
Well IDs Quantity
Estimated
Casing Depth
(ft bgs)
Estimated
Well Depth
(ft bgs)
Screen
Length
(ft)
Quantity of
Locations
Quantity of
Samples
Ash Basin
AB-1 through
AB-21, SB-1
through SB-5
26 40-90 AB-1S through
AB-21S 21 15-50 10-15 AB-1D through
AB-21D 21 25-75 40-90 5 5 10
Ash Landfill AL-1 through
AL-4 4 65-115 AL-1S, AL-2S,
AL-3S 3 40-80 15 AL-1D, AL-2D,
AL-3D, AL-4D 4 50-100 65-115 5 N/A N/A
Beyond Waste
Boundary N/A 0 N/A GWA-1S through
GWA-7S 7 20-50 15 GWA-1D through
GWA-7D 7 30-80 45-95 5 N/A N/A
Background BG-1, BG-2,
and BG-3 3 55-105 BG-1S, BG-2S,
and BG-3S 3 30-50 15 BG-1D, BG-2D,
and BG-3D 3 40-90 55-105 5 N/A N/A
Notes:
1. Estimated boring and well depths based on data available at the time of work plan preparation and subject to change based on site-specific conditions in the field.
2. Laboratory analyses of soil, ash, groundwater, and surface water samples will be performed in accordance with the constitu ents and methods identified in Tables 4 and 5.
3. Additionally, soils will be tested in the laboratory to determine grain size (with hydrometer), specific gravity, and permeability.
4. During drilling operations, downhole testing will be conducted to determine in-situ soil properties such as horizontal and vertical hydraulic conductivity.
5. Actual number of field and laboratory tests will be determined in field by Field Engineer or Geologist in accordance with project specifications.
TABLE 4 – SOIL AND ASH PARAMETERS AND ANALYTICAL METHODS
INORGANIC COMPOUNDS UNITS METHOD
Antimony mg/kg EPA 6020
Arsenic mg/kg EPA 6020
Barium mg/kg EPA 6010
Boron mg/kg EPA 6010
Cadmium mg/kg EPA 6020
Chloride mg/kg SM4500-Cl-E
Chromium mg/kg EPA 6010
Copper mg/kg EPA 6010
Iron mg/kg EPA 6010
Lead mg/kg EPA 6020
Manganese mg/kg EPA 6010
Mercury mg/kg EPA Method 7470A/7471
Nickel mg/kg EPA 6010
pH SU EPA 9045
Selenium mg/kg EPA 6020
Thallium (low level) mg/kg EPA 6020
Zinc mg/kg EPA 6010
Notes:
1. Soil samples to be analyzed for Total Inorganics using USEPA Methods 6010/6020
and pH using USEPA Method 9045, as noted above.
2. Ash samples to be analyzed for Total Inorganics using USEPA Methods 6010/6020
and pH using USEPA Method 9045; select ash samples will also be analyzed for
leaching potential using SPLP Extraction Method 1312 in conjunction with USEPA
Methods 6010/6020. SPLP results to be reported in units of mg/L for comparison to
2L Standards.
TABLE 5 – GROUNDWATER AND SURFACE WATER PARAMETERS AND ANALYTICAL
METHODS
PARAMETER UNITS METHOD
FIELD PARAMETERS
pH SU Field Water Quality Meter
Specific Conductance mmho/cm Field Water Quality Meter
Temperature ºC Field Water Quality Meter
Dissolved Oxygen mg/L Field Water Quality Meter
Oxidation Reduction Potential mV Field Water Quality Meter
NPDES CONSTITUENTS
Antimony µg/L EPA 200.8 or 6020
Arsenic µg/L EPA 200.8 or 6020
Barium µg/L EPA 200.7 or 6010
Boron µg/L EPA 200.7 or 6010
Cadmium µg/L EPA 200.8 or 6020
Chloride mg/L EPA 300.0
Chromium µg/L EPA 200.7 or 6010
Copper mg/L EPA 200.7 or 6010
Iron µg/L EPA 200.7 or 6010
Lead µg/L EPA 200.8 or 6020
Manganese µg/L EPA 200.7 or 6010
Mercury µg/L EPA 245.1
Nickel µg/L EPA 200.7 or 6010
Nitrate as Nitrogen mg-N/L EPA 300.0
Selenium µg/L EPA 200.8 or 6020
Sulfate mg/L EPA 300.0
Thallium (low level) µg/L EPA 200.8 or 6020
Total Dissolved Solids mg/L EPA 160.1 or SM 2540C
Zinc mg/L EPA 200.7 or 6010
ADDITIONAL GROUNDWATER CONSTITUENTS
Alkalinity (as CaCO3) mg/L SM2320B
Calcium mg/L EPA 200.7
Ferrous Iron mg/L SM4500-Fe
Magnesium mg/L EPA 200.7
Potassium mg/L EPA 200.7
Sodium mg/L EPA 200.7
Sulfide mg/L SM4500S-F
Total Organic Carbon mg/L SM5310
Note:
1. Select constituents may be analyzed for total and dissolved concentrations.
Appendix A
Notice of Regulatory Requirements Letter from
John E. Skvarla, III, Secretary, State of North
Carolina, to Paul Newton, Duke Energy, dated
August 13, 2014.
A 4
A=(WA
4AF1
NCDENR
North Carolina Department of Environment and Natural Resources
Pat McCrory John E. Skvarla, III
Governor Secretary
August 13, 2014
CERTIFIED MAIL 7004 2510 0000 3651 1168
RETURN RECEIPT REQUESTED
Paul Newton
Duke Energy
526 South Church Street
Charlotte, NC 28202
Subject: Notice of Regulatory Requirements
Title 15A North Carolina Administrative Code (NCAC) 02L .0106
14 Coal Ash Facilities in North Carolina
Dear Mr. Newton:
Chapter 143, North Carolina General Statutes, authorizes and directs the Environmental
Management Commission of the Department of Environment and Natural Resources to protect
and preserve the water and air resources of the State. The Division of Water Resources (DWR)
has the delegated authority to enforce adopted pollution control rules.
Rule 15A NCAC 02L .0103(d) states that no person shall conduct or cause to be conducted any
activity which causes the concentration of any substance to exceed that specified in 15A NCAC
02L .0202. As of the date of this letter, exceedances of the groundwater quality standards at 15A
NCAC 02L .0200 Classifications and Water Quality Standards Applicable to the Groundwaters
of North Carolina have been reported at each of the subject coal ash facilities owned and
operated by Duke Energy (herein referred to as Duke).
Groundwater Assessment Plans
No later than September, 26 2014 Duke Energy shall submit to the Division of Water Resources
plans establishing proposed site assessment activities and schedules for the implementation,
completion, and submission of a comprehensive site assessment (CSA) report for each of the
following facilities in accordance with 15A NCAC 02L .0106(g):
Asheville Steam Electric Generating Plant
Belews Creek Steam Station
Buck Steam Station
Cape Fear Steam Electric Generating Plant
Cliffside Steam Station
1636 Mail Service Center, Raleigh, North Carolina 27699-1636
Phone: 919-807-64641 Internet: www.ncdenr.gov
An Equal Opportunity 1 Affirmative Action Employer— Made in part by recycled paper
Mr. Paul Newton
August 12, 2014
Page 2 of 3
Dan River Combined Cycle Station
H.F. Lee Steam Electric Plant
Marshall Steam Station
Mayo Steam Electric Generating Plant
Plant Allen Steam Station
Riverbend Steam Station
Roxboro Steam Electric Generating Plant
L.V. Sutton Electric Plant
Weatherspoon Steam Electric Plant
The site assessment plans shall include a description of the activities proposed to be completed
by Duke that are necessary to meet the requirements of 15A NCAC 02L .0106(g) and to provide
information concerning the following:
(1) the source and cause of contamination;
(2) any imminent hazards to public health and safety and actions taken to mitigate
them in accordance to 15A NCAC 02L .0106(f);
(3) all receptors, and significant exposure pathways;
(4) the horizontal and vertical extent of soil and groundwater contamination and all
significant factors affecting contaminant transport; and
(5) geological and hydrogeological features influencing the movement,. chemical, and
physical character of the contaminants.
For your convenience, we have attached guidelines detailing the information necessary for the
preparation of a CSA report. The DWR will review the plans and provide Duke with review
comments, either approving the plans or noting any deficiencies to be corrected, and a date by
which a corrected plan is to be submitted for further review and comment or approval. For those
facilities for which Duke has already submitted groundwater assessment plans, please update
your submittals to ensure they meet the requirements stated in this letter and referenced
attachments and submit them with the others.
Receptor Survey
No later than October 14t', 2104 as authorized pursuant to 15A NCAC 02L .0106(g), the DWR is
requesting that Duke perform a receptor survey at each of the subject facilities and submitted to
the DWR. The receptor survey is required by 15A NCAC 02L .0106(g) and shall include
identification of all receptors within a radius of 2,640 feet (one-half mile) from the established
compliance boundary identified in the respective National Pollutant Discharge Elimination
System (NPDES) permits. Receptors shall include, but shall not be limited to, public and private
water supply wells (including irrigation wells and unused or abandoned wells) and surface water
features within one-half mile of the facility compliance boundary. For those facilities for which
Duke has already submitted a receptor survey, please update your submittals to ensure they meet
the requirements stated in this letter and referenced attachments and submit them with the others.
If they do not meet these requirements, you must modify and resubmit the plans.
Mr. Paul Newton
August 12, 2014
Page 3 of 3
The results of the receptor survey shall be presented on a sufficiently scaled map. The map shall
show the coal ash facility location, the facility property boundary, the waste and compliance
boundaries, and all monitoring wells listed in the respective NPDES permits. Any identified
water supply wells shall be located on the map and shall have the well owner's name and
location address listed on a separate table that can be matched to its location on the map.
Failure to comply with the State's rules in the manner and time specified may result in the
assessment of civil penalties and/or the use of other enforcement mechanisms available to the
State.
We appreciate your attention and prompt response in this matter. If you have any questions,
please feel free to contact S. Jay Zimmerman, Water Quality Regional Operations Section Chief,
at (919) 807-6351.
2hn
ierely,
E. Skvarla, III
Attachment enclosed
cc: Thomas A. Reeder, Director, Division of Water Resources
Regional Offices — WQROS
File Copy
August 12, 2014
GUIDELINES FOR COMPREHENSIVE SITE ASSESSMENT
This document provides guidelines for those involved in the investigation of
contaminated soil and/or groundwater, where the source of contamination is from:
■ Incidents caused by activities subject to permitting under G.S. 143-215.1
■ Incidents caused by activities subject to permitting under G.S. 87-88
■ Incidents arising from agricultural operations, including application of
agricultural chemicals, but not including unlawful discharges, spills or
disposal of such chemicals
Comprehensive Site Assessment (CSA)
NOTE: Regional Offices may request additional information in support of the CSA to aid
in their review and will not approve the CSA if any of the elements specified below have
not been included or have not been sufficiently addressed
Minimum Elements of the Comprehensive Site Assessment Report:
A. Title Page
• Site name, location and Groundwater Incident number (if
assigned) and Permit Number;
• Date of report;
• Responsible Party and/or permiee, including address and
phone number;
• Current property owner including address and phone
number;
• Consultant/contractor information including address and
phone number;
• Latitude and longitude of the facility; and
• Seal and signature of certifying P.E. or P.G., as appropriate.
B. Executive Summary
The Executive Summary should provide a brief overview of the pertinent
site information (i.e., provide sufficient information to acquaint the reader
with the who, what, when, where, why and how for site activities to date).
1. Source information:
Type of contaminants
2. Initial abatement/emergency response information.
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3. Receptor information:
•
Water supply wells;
•
Public water supplies (wells, surface water intakes);
•
Surface water bodies;
•
Wellhead protection areas;
•
Deep aquifers in the Coastal Plain physiographic region;
•
Subsurface structures; and
•
Land use.
4. Sampling/investigation results:
•
Nature and extent of contamination;
•
Maximum contaminant concentrations;
•
Site hydrogeology.
5. Conclusions
and recommendations.
C. Table of Contents
• First page number for each section listed.
• List of figures (all referenced by number and placed in a
single section following contents text).
• List of tables (all referenced by number and placed in a single
section following contents text).
• List of appendices.
D. Site History and Source Characterization
• Provide a history of property ownership and use. Indicate
dates of ownership, uses of the site, and potential sources of
contaminants.
• Discuss the source(s) of contamination, including primary
and secondary sources.
• For permitted activities, describe nature of activity, permitted
waste, application of all instances of
over-application/irrigation of wastes or water
• Summarize assessment activities and corrective actions
performed to date including emergency response, initial
abatement, primary and secondary source removal.
• Discuss geographical setting and present/future surrounding
land uses.
E. Receptor Information
Provide a site map showing labeled well locations within a
August 12, 2014
minimum of 1500 feet of the known extent of contamination.
Key to the table and maps described.
NOTE: As the known extent of contamination changes, the
receptor survey must be updated to reflect the change. This
applies throughout the Receptor Information section.
• In table format, list all water supply wells, public or private,
including irrigation wells and unused wells, (omit those that
have been properly abandoned in accordance with 15A
NCAC 2C .0100) within a minimum of 1500 feet of the known
extent of contamination. Note whether well users are also
served by a municipal water supply.
• For each well, include well number, well owner and user
names, addresses and telephone numbers, use of the well,
well depth, well casing depth, well screen interval, and
distance from source of contamination;
NOTE: It will often be necessary to conduct any or all of the
following in order to ensure reliability in a water supply well
survey.
o Call the city/county water department to inquire about
city water connections,
o Visit door-to-door (make sure that you introduce
yourself and state your purpose to residents prior to
examining their property) to obtain accurate
description of water usage, and if some residents are
not at home, ask surrounding neighbors who are
home about the water usage at those residences.
Even if a public water line is available, some
residents still use their well water and are not
connected to the public water system; and
o Search for water meters and well houses.
• Site map showing location of subsurface structures (e.g.,
sewers, utility lines, conduits, basements, septic tanks,
drain fields, etc.) within a minimum of 1,500 feet of the known
extent of contamination;
• Table of surrounding property owner addresses;
• Discuss the availability of public water supplies within a
minimum of 1,500 feet of the source area, including the
distance and location to the nearest public water lines and
the source(s) of the public water supply;
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• Identify all surface water bodies (e.g., ditch, pond, stream,
lake, river) within a minimum of 1,500 feet of the source of
contamination;
• Determine the location of any designated wellhead protection
areas as defined in 42 USC 300h-7(e) within a minimum of
1,500 feet of the source of contamination. Identify and
discuss the location of the water supply well(s) for which the
area was designated a wellhead protection area, and the
extent of the protected area. Include information about the
well owner, well -construction specifications (especially at
screened intervals), pumping rate and pumping schedule.
Information regarding designated wellhead. protection areas
may be obtained by contacting the Public Water Supply
Section at (919) 707-9083;
• Discuss the uses and activities (involving possible human
exposure to contamination) that could occur at the site and
adjacent properties. Examples of such activities and uses
include but are not limited to use of a property for an office,
manufacturing operation, residence, store, school, gardening
or farming activities, recreational activities, or undeveloped
land;
• Determine whether the contaminated area is located in an
area where there is recharge to an unconfined or
semi -confined deeper aquifer that is being used or may be
used as a source of drinking water. Based on a review of
scientific literature on the regional hydrogeology and well
construction records and lithological logs for deeper wells in
the area, identify and describe the deep aquifers underlying
the source of contamination. Include information on the depth
of the deep aquifer in relation to the surficial saturated zone,
the lithology and hydraulic conductivity of the strata between
the surficial aquifer and the deeper aquifer, and the
difference in groundwater head between the surficial aquifer
and the deeper aquifer. Discuss the local and regional usage
of the deep aquifer and the draw down from major pumping
influences. Also, specify the distance from the source of
contamination to major discharge areas such as streams and
rivers. Cite all sources and references used for this
discussion.
NOTE: This requirement (last bullet) only pertains to
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August 12, 2014
contamination sources in the Coastal Plain physiographic region
as designated on a map entitled "Geology of !North Carolina"
published by the Department in 1985. However,
recharge/discharge, hydraulic conductivity, lithology, head
difference, etc. is also important information at mountains
and piedmont sites.
F. Regional Geology and Hydrogeology
Provide a brief description of the regional geology and hydrogeology. Cite
all references.
G. Site Geology and Hydrogeology
• Describe the soil and geology encountered at the site. Use
the information obtained during assessment activities (e.g.,
lithological descriptions made during drilling, probe surveys,
etc.). This information should correspond to the geologic
cross sections required in N. below; and
• Based on the results of the groundwater investigation,
describe the site hydrogeology, including a discussion of
groundwater flow direction, hydraulic gradient, hydraulic
conductivity and groundwater velocity. Discuss the effects of
the geologic and hydrogeological characteristics on the
migration, retardation, and attenuation of contaminants.
H . Soil Sampling Results
Using figures and tables to the extent possible, describe all soil sampling
performed to date and provide the rationale for sample locations, number
of samples collected, etc. Include the following information:
• Location of soil samples;
• Date of sampling;
• Type of soil samples (from excavation, borehole, Geoprobe,
etc.);
• Soil sample collection procedures (split spoon, grab, hand
auger, etc.)
• Depth of soil samples below land surface;
• Soil sample identification
• Soil sample analyses;
• Soil sample analytical results (list any contaminant detected
above the method detection limit); and
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• Identify any sample analytical results that exceed the
applicable cleanup levels.
NOTE: Information related to H. above should correspond to the
sampling location and sampling results maps required in N. below.
I . Groundwater Sampling Results
Using figures and tables to the extent possible describe the groundwater
sampling performed to date and provide the rationale for sample locations
(based on source and contaminant type), number of samples collected,
etc. Include the following information:
• Location of groundwater samples and monitoring wells;
• Date of sampling;
• Groundwater sample collection procedures (bailer, pump,
etc.);
• Groundwater sample identification and whether samples
were collected during initial abatement, CSA, etc.;
• Groundwater sample analyses;
• Groundwater sample analytical results (list any contaminant
detected above the method detection limit; and
• Identify all sample analytical results that exceed 15A NCAC
2L or interim standards.
NOTE: Information related to 1. above should correspond to the
sampling location and sampling results maps required in N. below.
J. Hydrogeological Investigation
Describe the hydrogeological investigation performed including all
methods, procedures and calculations used to characterize site
hydrogeological conditions. The following information should be discussed
and should correspond to the maps and figures required below:
• Groundwater flow direction;
• Hydraulic gradient (horizontal and vertical);
• Hydraulic conductivity;
• Groundwater velocity;
• Contaminant velocity;
• Slug test results; *
• Aquifer test results;
• Plume's physical and chemical characterization; and
• Fracture trace study if groundwater in bedrock is impacted.
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August 12, 2014
* Check with the Regional Office prior to performing these tests
and study to see if necessary for the site.
K. Groundwater Modeling Results
Groundwater modeling or predictive calculations may be necessary at
some sites (source area proximate to surface water, source area located
within wellhead protection area or source area overlying semi -confined or
unconfined deeper Coastal Plain aquifer) to verify, based on site specific
hydrogeological conditions, whether groundwater contamination poses a
risk to receptors. For contamination shown to pose a risk to receptors,
groundwater modeling may be necessary to determine an appropriate
cleanup level for contaminated groundwater. Modeling should illustrate the
input data used to complete the model and will generally be required for
natural attenuation proposals (see Groundwater Modeling Policy at
http://portal. ncdenr.org/web/wq/aps/a-wr)ro/policy).
NOTE: Input data for models should be derived from site specific
information with limited assumptions or estimates. All assumptions and
estimated values including biodegradation rates must be conservative
(predict reasonable worst -case scenarios) and must be well documented.
L. Discussion
• Nature and extent of contamination, including primary and
secondary source areas, and impacted groundwater and
surface water resources;
• Maximum contaminant concentrations;
• Contaminant migration and potentially affected receptors
M. Conclusions and Recommendations
If corrective action will be necessary, provide a preliminary evaluation of
remediation alternatives appropriate for the site. Discuss the remediation
alternatives likely to be selected. Note that for impacts to groundwater
associated with permitted activities, corrective action pursuant to 15A
NCAC 2L .0106(k), (1) and (m) is not applicable, unless provided for
pursuant to 15A NCAC 2L .0106(c) and (e) or through a variance from the
Environmental Management Commission (EMC).
N. Figures
9 71/2 minute USGS topographic quadrangle map showing an area
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within a minimum of a 1,500-foot radius of the source of
contamination and depicting the site location, all water supply wells,
public water supplies, surface water intakes, surface water bodies,
designated well head protection areas, and areas of recharge to
deeper aquifers in the Coastal Plain that are or may be used as a
source for drinking water;
Site map locating source areas, site boundaries, buildings, all water
supply wells within a minimum of 1,500 feet, named
roads/easements/right-of-ways, subsurface utilities, product or
chemical storage areas, basements and adjacent properties, scale
and north arrow;
At least two geologic cross sections through the saturated and
unsaturated zones intersecting at or near right angles through the
contaminated area using a reasonable vertical exaggeration.
Indicate monitoring well/sample boring/sample locations and
analytical results for soil samples. Identify the depth to the water
table. Provide a site plan showing the locations of the cross
sections;
■ Site map(s) showing the results of all soil sampling conducted.
Indicate sampling identifications, sampling depths, locations and
analytical results;
■ Site map(s) showing the results of all groundwater sampling
conducted. Indicate sampling locations, monitoring well
identifications, sample identifications, and analytical results;
Separate groundwater contaminant iso-concentration contour maps
showing total volatile organic compound concentrations, total
semi -volatile organic compound concentrations and concentrations
for the most extensive contaminant. Maps should depict the
horizontal and vertical extent. Contour line for applicable 2L
standard should be shown in bold;
■ Site map(s) showing the elevation of groundwater in the monitoring
wells and the direction of groundwater flow. Contour the
groundwater elevations. Identify and locate the datum (arbitrary
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August 12, 2014
1000, USGS, NGVD) or benchmark. Indicate the dates that water
level measurements were made. There should be one map for each
series of water level measurements obtained;
■ Groundwater contaminant iso-concentration contour cross-section;
and
■ Site map(s) showing the monitoring wells.
NDTE: If possible, use a single base map to prepare site maps using a
map scale of 9 inch = 40 feet (or a smaller scale for large sites, if
necessary). Maps and figures should include conventional symbols,
notations, labeling, legends, scales, and north arrows and should
conform to generally accepted practices of map presentation such as
those enumerated in the US Geological Survey pamphlet, "Topographic
Maps".
O. Tables
List all water supply wells, public or private, including irrigation wells
and unused wells, (omit those that have been properly abandoned
in accordance with 15A NCAC 2C .0100) within a minimum of 1500
feet of the known extent of contamination For each well, include the
well number (may use the tax map number), well owner and user
names, addresses and telephone numbers, use of the well, well
depth, well casing depth, well screen interval and distance from the
source of contamination;
List the names and addresses of property owners and occupants
within or contiguous to the area containing contamination and all
property owners and occupants within or contiguous to the area
where the contamination is expected to migrate;
■ List the results for groundwater samples collected including sample
location; date of sampling; sample collection procedures (bailer,
pump, etc.); sample identifications; sample analyses; and sample
analytical results (list any contaminant detected above the method
detection limit in bold); and
List for each monitoring well, the monitoring well identification
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August 12, 2014
numbers, date water levels were obtained, elevations of the water
levels, the land surface, top of the well casing, screened interval
and bottom of the well.
P Appendices
• Boring logs and lithological descriptions;
• Well construction records;
• Standard procedures used at site for sampling, field equipment
decontamination, field screening, etc.;
• Laboratory reports and chain -of -custody documents;
• Copies of any permits or certificates obtained, permit number,
permitting agency, and
• Modeling data and results;
• Slug/pumping test data; and
• Certification form for CSA
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DIVISION OF WATER RESOURCES
Certification for the Submittal of a Comprehensive Site Assessment
Responsible Party and/or Permittee:
Contact Person:
Address:
City: State: Zip Code:
Site Name:
Address:
City: State: Zip Code:
Groundwater Incident Number (applicable):
I, , a Professional Engineer/Professional Geologist
(circle one) for (firm or
company of employment) do hereby certify that the information indicated below is
enclosed as part of the required Comprehensive Site Assessment (CSA) and that
to the best of my knowledge the data, assessments, conclusions,
recommendations and other associated materials are correct, complete and
accurate.
(Each item must be initialed by the certifying licensed professional)
1. The source of the contamination has been identified. A list of all
potential
sources of the contamination are attached.
2. Imminent hazards to public health and safety have been identified.
3. Potential receptors and significant exposure pathways have been
identified.
4. Geological and hydrogeological features influencing the movement
of groundwater have been identified. The chemical and physical character of the
contaminants have been identified.
5. The CSA sufficiently characterizes the cause, significance and
extent of groundwater and soil contamination such that a Corrective Action Plan
can be developed. If any of the above statements have been altered or items not
initialed, provide a detailed explanation. Failure to initial any item or to provide
written justification for the lack thereof will result in immediate return of the CSA to
the responsible party.
(Please Affix Seal and Signature)
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