NC0004979_Allen Pumping Test Work Plan - Rev1_20180523

PUMPING TEST
WORK PLAN REVISION 1
FOR
ALLEN STEAM STATION
253 PLANT ALLEN ROAD
BELMONT, NORTH CAROLINA 28012

SUBMITTED: MAY 2018

PREPARED FOR

DUKE ENERGY CAROLINAS, LLC

Christopher H. Bruce, NC LG 2246
Sr. Geologist

Christopher Suttell, NC LG 2426
Project Manager
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TABLE OF CONTENTS
SECTION PAGE
1.0 INTRODUCTION ......................................................................................................... 1-1
1.1 Site History, Operations, and Coal Ash Management ........................................ 1-1
1.2 Planned Pumping Tests ........................................................................................... 1-2
2.0 SITE CONCEPTUAL MODEL ................................................................................... 2-1
2.1 Site Geology and Hydrogeology ............................................................................ 2-1
2.1.1 Site Geology ......................................................................................................... 2-1
2.1.2 Site Hydrogeology .............................................................................................. 2-2
3.0 WELL INSTALLATION .............................................................................................. 3-1
3.1 Installation of Pumping and Observation Wells .................................................. 3-1
3.1.1 Ash Pumping Well Installation ......................................................................... 3-1
3.1.2 Saprolite Pumping Well Installation ................................................................ 3-2
3.1.3 Ash Observation Well Installation ................................................................... 3-3
3.1.4 Saprolite Observation Well Installation ........................................................... 3-3
3.2 Well Development .................................................................................................... 3-4
4.0 PUMPING TESTS ......................................................................................................... 4-1
4.1 Static Water Level Collection .................................................................................. 4-1
4.2 Pumping System Installation .................................................................................. 4-1
4.3 Oversight of Step-Drawdown Tests ....................................................................... 4-2
4.4 Step Test Recovery .................................................................................................... 4-3
4.5 Constant-Rate Pumping Test .................................................................................. 4-3
5.0 WATER-QUALITY MEASUREMENTS AND SAMPLING ................................. 5-1
6.0 ANALYSIS OF WATER-LEVEL DATA ................................................................... 6-1
6.1 Baseline Analysis....................................................................................................... 6-1
6.2 Step Test Analysis ..................................................................................................... 6-1
6.3 Constant Discharge Rate Test Analysis ................................................................. 6-1
7.0 REFERENCES ................................................................................................................ 7-1
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LIST OF FIGURES
Figure 1 Site Location Map
Figure 2 Allen Plant Vicinity Map
Figure 3 Location for AB-21 Active Ash Basin Pumping Test
Figure 4 Location for AB-35 Inactive Ash Basin Pumping Test
Figure 5 Typical Flow Meter Configuration
Figure 6 Typical Step Test Drawdown Curve

LIST OF TABLES
Table 1 Well Construction Details
Table 2 Summary of Pumping Wells and Observation Wells

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1.0 INTRODUCTION
Duke Energy Carolinas, LLC (Duke Energy) owns and operates the coal-fired Allen
Steam Station (Allen, Plant, or Site), located on the west bank of the Catawba River on
Lake Wylie in Belmont, Gaston County, North Carolina (Figure 1). The Site is
approximately 1,009 acres in area. In addition to the power plant property, Duke
Energy owns and operates the Catawba-Wateree Project (Federal Energy Regulatory
Commission [FERC] Project No. 2232). Lake Wylie reservoir, part of the Catawba-
Wateree Project, is used for hydroelectric generation, municipal water supply, and
recreation.
1.1 Site History, Operations, and Coal Ash Management
Allen is a coal-fired electricity-generating facility with a capacity of 1,155 megawatts
(MW). The facility is situated along Lake Wylie. Commercial operations began at the
five-unit station in 1957 with operation of coal-fired Units 1 and 2 (330 MW total). Unit 3
(275 MW) was placed into commercial operation in 1959, followed by Unit 4 (275 MW)
in 1960, and Unit 5 (275 MW) in 1961. Coal ash residue from the coal combustion
process has historically been disposed of in the Allen ash basins. The ash basins include
the active ash basin and the inactive ash basin (also known as the retired ash basin). The
inactive ash basin area includes the retired ash basin (RAB) lined ash landfill, ash
storage areas, and structural fill areas. The area contained within the entire waste
boundaries of the ash basins (Figure 2) encompasses approximately 322 acres. In
general, the ash basins are located in historical depressions formed from tributaries that
flowed toward Lake Wylie/Catawba River. The ash basins are operated as an integral
part of the station’s wastewater treatment system, which receives flows from the ash
handling system, coal pile runoff, landfill leachate, FGD wastewater, the station yard
drain sump, and Site storm water. Discharge from the ash basin system is permitted by
the North Carolina Department of Environmental Quality Division of Water Resources
(NCDEQ DWR) under the National Pollutant Discharge Elimination System (NPDES)
Permit NC0004979.
Detailed descriptions of the Site operational history, the Site conceptual model, physical
setting and features, and geology/hydrogeology as well as results of the findings of the
Comprehensive Site Assessment (CSA) and other work related to the Coal Ash
Management Act (CAMA) are presented in the following documents:
Comprehensive Site Assessment Report – Allen Steam Station Ash Basin (HDR
Engineering, Inc. of the Carolinas, August 23, 2015).
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Corrective Action Plan Part 1 – Allen Steam Station (HDR Engineering, Inc. of the
Carolinas, November 20, 2015), which included Comprehensive Site Assessment
Supplement 1 as Appendix A.
Corrective Action Plan Part 2 – Allen Steam Station (HDR Engineering, Inc. of the
Carolinas, February 19, 2016).
Comprehensive Site Assessment Supplement 2 – Allen Steam Station (HDR
Engineering, Inc. of the Carolinas, August 2, 2016).
2018 Comprehensive Site Assessment Update – Allen Steam Station (SynTerra,
January 31, 2018).
1.2 Planned Pumping Tests
Pumping tests to collect Site-specific data for further refining the groundwater flow and
transport model are planned. The groundwater flow and transport model will be used
for closure planning and potential groundwater corrective action evaluation. The
pumping tests would focus on evaluation of field scale horizontal and vertical
variability of the hydrologic characteristics for the saturated media. Each test would
provide estimates of media properties, including transmissivity (T), hydraulic
conductivity (K), and storativity (S).
The following major tasks for well installation and ash basin pumping tests at the Allen
Steam Station are anticipated:
1. Well installation and development
2. Static water-level (baseline data) collection
3. Pumping system installation
4. Step-drawdown tests
5. Step-drawdown test recovery
6. Constant-rate pumping tests
7. Water-quality sampling
8. Data analysis
A portion of this scope of work has been completed with both pumping wells and
observation wells installed at the Site at approximate locations shown on Figure 3 and
Figure 4. Two ash pumping wells and two saprolite pumping wells have been installed
at selected locations. Each pumping well is screened wholly within ash or saprolite/soil.
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A total of seven new observation wells have also been installed. Additionally, three
existing wells will be used as observation points during the pumping test.
Newly Installed Wells:
AB-21 Well Cluster
AB-21-PWA (ash pumping well), AB-21-PWS (saprolite pumping well), AB-21-OWAU
(upper ash observation well at 15 feet from pumping well), AB-21-OWAL (lower ash
observation well at 15 feet from pumping well), AB-21SS (saprolite observation well 30
feet from pumping well)
AB-35 Well Cluster
AB-35-PWA (ash pumping well), AB-35-PWS (saprolite pumping well), AB-35-OWAU
(upper ash observation well at 15 feet from pumping well), AB-35-OWAL (lower ash
observation well at 15 feet from pumping well), AB-35–OWAL30 (lower ash
observation well at 30 feet from pumping well), AB-35SS (saprolite observation well 30
feet from pumping well)
Existing Wells:
AB-21 Well Cluster
AB-21S (upper ash observation well 30 feet from pumping well), AB-21SL (lower ash
observation well 30 feet from pumping well)
AB-35 Well Cluster
AB-35S (upper ash observation well 30 feet from pumping well)
Approximate well construction details are summarized on Table 1.
One pumping test is estimated to take eight (8) days (72 hours for static conditions, 24
hours for step test/recovery, 72 hours for constant-rate discharge test, and 24 hours for
recovery). During this time, water levels in selected wells would be monitored using
pressure transducers and manual water-level readings. During the pumping test,
groundwater samples would also be collected daily for laboratory analysis.
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2.0 SITE CONCEPTUAL MODEL
2.1 Site Geology and Hydrogeology
This section provides a brief summary of the Site geology and hydrogeology. Detailed
descriptions of the Site geology and hydrogeology can be found in the documents listed
in Section 1.
2.1.1 Site Geology
Geology beneath the Allen Plant can be classified into three units: regolith
(shallow), transition zone (deep), and bedrock. Regolith, the shallowest geologic
unit, includes surficial residual soils, fill and reworked soil, alluvium along the
Lake Wylie stream valley, and saprolite. Saprolite is thick, with a depth up to
about 130 feet, and is typically saturated. The regolith is comprised primarily of
fine-grained material, such as silty clay and clayey sand.
The transition (deep) zone at the Allen Site is generally continuous throughout
the Allen Plant area and is comprised mostly of partially weathered rock that is
gradational between saprolite and competent bedrock. The transition zone is as
much as 65 feet thick. The change from partially weathered rock to competent
bedrock is defined by subtle changes in weathering, secondary staining,
mineralization, core recovery, and the degree of fracturing in the rock.
Bedrock at the Site consists of meta-quartz diorite and meta-diabase. Based on
rock core descriptions, the meta-quartz diorite, which is the predominant rock
type at the Site, is very light gray to dark gray, fine- to coarse-grained, non-
foliated and massive to foliated, and is composed dominantly of plagioclase,
quartz, biotite, and hornblende. The meta-diabase is greenish black to very dark
greenish gray, is mostly non-foliated, and is noted as aphanitic to fine-grained,
although it is described as fine- to coarse-grained in some boring logs.
Shallow bedrock is fractured; however, only mildly productive fractures
(providing water to wells) were observed within the top 50 feet to 75 feet of
bedrock. The majority of fractures are relatively small (e.g., close and tight) and
appear to be limited in connectivity between borings. Yields from pumping or
packer testing are low.

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2.1.2 Site Hydrogeology
The Allen groundwater system flow direction within each of the three layers is
generally consistent. Water levels fluctuate up and down with seasonal changes
in precipitation evapotranspiration, but the overall groundwater flow directions
do not change because of seasonal changes in precipitation.
The groundwater system at Allen is consistent with the regolith-fractured rock,
slope-aquifer system and is an unconfined, connected aquifer system. Typically,
groundwater flow within the slope-aquifer system mimics surface topography.
An elongated topographic high creates a groundwater divide that trends
approximately north to south and roughly follows NC Highway 273.
Groundwater to the east of the divide, including groundwater within the Allen
Plant, flows to the east toward Lake Wylie and to the northeast and north toward
Duke Energy property and the discharge canal, as confirmed by water-level
measurements on-Site. Groundwater to the west of the divide flows west toward
the South Fork Catawba River.
The hydraulic head created by the impounded water in the active ash basin
under current conditions creates a slight mounding effect that influences
groundwater flow direction in the immediate vicinity of the basin. Beyond the
area of impounded water, the forces of natural advective flow overcome the
mounding effect and groundwater flow continues toward the east and Lake
Wylie. Water-level measurements from Site wells indicate that the mounding
effect does not extend beyond the ash basin boundary, which in turn indicates
that groundwater does not flow toward the water supply wells in the vicinity of
the basin.
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3.0 WELL INSTALLATION
Pumping wells and observation wells were installed in the active ash basin at the AB-21
well cluster and in the inactive ash basin at the AB-35 well cluster (Figure 2, Figure 3,
and Figure 4). Figure 3 and Figure 4 also include a conceptual cross-sectional view of
the wells.
3.1 Installation of Pumping and Observation Wells
The pumping and observation wells were installed in April and May 2018 by a licensed
North Carolina driller using rotary sonic drilling techniques. Continuous cores were
obtained at each boring location. A complete core from each location was retained in a
wooden core box and stored on-Site for potential future use. Newly installed wells were
completed with concrete well pads, protective surface casings, well tags, and locking
caps in accordance with 15A NCAC 02C requirements. Approximate well construction
details are summarized on Table 1. At the time this work plan was written, the newly
installed wells had not yet been surveyed for horizontal and vertical control. Boring
logs and well construction records will be included as part of a technical memorandum
on the results of pumping tests, as referenced in Section 6.
3.1.1 Ash Pumping Well Installation
Ash pumping well AB-21-PWA was installed approximately 30 feet from
existing ash pore water wells AB-21S/SL, and ash pumping well AB-35-PWA was
installed approximately 30 feet from existing ash pore water well AB-35S. Ash
pumping wells were installed using a nominal 13-inch core barrel. The wells
were constructed of 6-inch ID, National Sanitation Foundation (NSF) grade
polyvinyl chloride (PVC) (ASTM D-1785-12) schedule 40 flush-joint threaded
casing terminating in a 10-foot-long 0.010-inch machine-slotted wire -wrapped
PVC screen, hung approximately 1 foot off the bottom of the boring (to allow
filter material below the well screen).
Packed well screens for each well were filled with clean, well-rounded, washed
high grade No. 1 silica sand. The filter pack extended approximately 5 feet above
the top of the screen. An approximate 5-foot pelletized bentonite seal was placed
above the filter pack. The pellets were allowed to hydrate in accordance with
manufacturer’s specifications before the remainder of the annular space, from the
top of the upper bentonite seal to near ground surface, was filled with Agua
Guard cement grout.
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Each ash pumping well was screened wholly within ash. Well construction
details are summarized on Table 1. There are plans to abandon these ash
pumping wells at the conclusion of the pumping test activities.
3.1.2 Saprolite Pumping Well Installation
Saprolite pumping wells (AB-21-PWS and AB-35-PWS) were installed at AB-21
and AB-35 well cluster locations and adjacent to the respective ash pumping
wells. These wells were installed using temporary steel drill-string casing as a
precautionary measure to prevent potential migration from overlying material
along the annular space of the borehole and beneath the ash-soil interface.
Multiple drill string rods/casings were used to construct the saprolite pumping
wells. The largest diameter casing was a nominal 13-inch casing that was
advanced a few feet into saprolite beyond the base of the ash. This casing was left
in place for the remainder of well construction activities. After material within
the 13-inch casing was removed, drilling to the targeted depth resumed using
smaller diameter casing (nominal 10-inch diameter) to install the wells into
saprolite.
Once at the targeted depth, the wells were constructed similar to how the ash
pumping wells were constructed, but with the bentonite seal extending from the
top of the filter pack up into 13-inch casing and above the approximate depth of
the ash/soil interface. After the bentonite seal was hydrated, the remainder of the
annular space, from the top of the upper bentonite seal to near ground surface,
was filled with Agua Guard cement grout and the 13-inch steel casing was
removed.
A notable sequence of finer grained material (silty clay) was observed
immediately beneath the ash at both locations. The silty clay extended at least 10
feet before grading into slightly coarser grained material (primarily silt with
some clay and sand). The saprolite wells were constructed within the coarser
grained material. At the time the work plan was written, final boring logs were
not available.
Each saprolite pumping well was screened wholly within saprolite/soil. Well
construction details are summarized on Table 1. There are plans to abandon
these saprolite pumping wells at the conclusion of the pumping test activities.
However, AB-35-PWS may be left in place at the conclusion of the pumping test
to be used for monitoring as part of the CAMA interim monitoring program. AB-
35-PWS would be used instead of the saprolite observation well AB-35SS, which
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had persistent elevated turbidity throughout development, as discussed below.
Wells AB-35-PWA and AB-35SS have similar screened depth intervals.
3.1.3 Ash Observation Well Installation
A total of five (5) ash observation wells were installed to supplement existing
wells installed within ash pore water. Two wells (AB-21-OWAU and AB-21-
OWAL) were installed at the existing AB-21 well cluster and three wells (AB-35-
OWAU, AB-35-OWAL, and AB-35OWAL30) were installed at the AB-35 well
cluster. Each of these wells is located about 15 feet away from the pumping well,
with the exception of well AB-35-OWAL30 which is located 30 feet from the
associated ash pumping well. Distances from the pumping well for each
observation well are summarized on Table 1.
Ash observation wells were installed using a nominal 6-inch core barrel. The
wells were constructed of 2-inch ID, NSF-grade PVC schedule 40 flush-joint
threaded casing terminating in a 5-foot-long 0.010-inch machine-slotted pre-
packed PVC screen, hung approximately 1 foot off the bottom of the boring (to
allow filter material below the well screen).
Packed well screens for each well were filled with clean, well-rounded, washed
high grade No. 1 silica sand. The filter pack extended approximately 5 feet above
the top of the screen. An approximately 5-foot pelletized bentonite seal was
placed above the filter pack. The pellets were allowed to hydrate in accordance
with manufacturer’s specifications before the remainder of the annular space,
from the top of the upper bentonite seal to near ground surface, was filled with
Agua Guard cement grout.
Well construction details are summarized on Table 1. There are plans to abandon
these ash observation wells at the conclusion of the pumping test activities.
3.1.4 Saprolite Observation Well Installation
Saprolite observation/monitoring well AB-21SS was installed the AB-21 well
cluster, and saprolite observation/monitoring well AB-35SS was installed the AB-
35 well cluster. These wells were installed similar to the saprolite pumping wells
using multiple drill string rods/casings as a precautionary measure to prevent
potential migration from overlying material along annular space of the borehole
and beneath the ash-soil interface.
The largest diameter casing was a nominal 10-inch casing that was advanced a
few feet into saprolite, beyond the base of the ash. A permanent 6-inch diameter
schedule 40 PVC protective outer casing was then installed to the same
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approximate depth and grouted in place. After the grout had sufficient time to
set (approximately 24 hours), drilling was advanced beneath the outer casing
using nominal 6-inch diameter casing to the targeted depth at least 10 feet below
the depth of the surface casing. Two-inch diameter PVC wells were then installed
in an approach similar to that of the installation of the ash observation wells as
described above, but with the bentonite seal extending up approximately 2 feet
into the permanent 6-inch PVC outer casing.
Similar to what was observed at the saprolite pumping wells, a notable sequence
of finer grained material (silty clay) was observed immediately beneath the ash
at both locations. The silty clay extended at least 10 feet before grading into
slightly coarser grained material (primarily silt with some clay and sand). The
saprolite wells were constructed within the coarser grained material. At the time
the work plan was written, final boring logs were not available.
Well construction details are summarized on Table 1. There are plans to keep
the saprolite wells in place at the conclusion of the pumping test so that they can
be used for monitoring as part of the CAMA interim monitoring program.
However, as discussed above, well development efforts at AB-35SS were
unsuccessful at reducing turbidity to less than 10 Nephelometric Turbidity Units
(NTUs). Therefore, AB-35SS may be abandoned and AB-35-PWS may remain in
place for use in the CAMA interim monitoring program.
3.2 Well Development
Newly installed wells were developed until discharge was as clear and stable as
possible. The main objective of the well development was to improve near-well
permeability and stability. Removal of the fine particles from the near-well area will
help create a more permeable zone and minimize the effect of well smear or caking.
Improper well development can cause significant impact to the results of both the step
test and the constant-rate discharge test. This could result in the need to stop the test
(step test or constant-rate test) and redevelop the wells (primarily pumping wells).
Development included surging and high volume water removal. Completion of
development was determined when turbidity remained at less than 10 NTUs after
surging the well or at least 10 borehole volumes were purged.
Turbidity remained greater than 100 NTUs throughout development at observation
wells AB-21-OWAU, AB-21-OWAL, and AB-35SS, after at least 20 well volumes were
removed and more than 10 hours of pumping/surging. Observation of cores from the
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ash observation wells indicated the material was primarily fine-grained (silt),
characteristic of fly ash. Similarly, cores indicated material at AB-35SS was primarily
fine-grained (silt with some clay and sand). Groundwater yield in each well was
reasonable, similar to that of other wells installed in ash or saprolite, indicating the
hydraulic interconnectivity of these wells may be uninhibited. Therefore, development
was considered complete at these locations. Development at the remaining wells
resulted in groundwater and ash pore water turbidity levels being less than 10 NTUs.
After development (if any additional development is necessary), the wells will be
allowed to equilibrate for at least five days prior to the collection of baseline water-level
data.
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4.0 PUMPING TESTS
4.1 Static Water Level Collection
Static water-level (baseline data) collection may commence once the pumping wells and
observation wells have been installed, developed, and allowed to equilibrate (for
approximately five days). Baseline water-level readings would be used to determine
long-term data trends or potential interferences from other pumping/discharge
source(s). Water levels in selected wells would be monitored using pressure
transducers. A summary of the wells to be monitored for each test is included as Table
2. Transducers will be installed in all proposed observation wells at the Site.
Prior to the installation of transducers, an initial round of water levels would be
manually collected from the wells listed in Table 2. Transducers will then be installed
and programmed to collect water-level data every 10 minutes for a minimum of 72
hours before the start of any active pumping (step test). At the end of the 72-hour
period, baseline measurements would be stopped and downloaded for review. Manual
water level measurements will be collected (during the 72 hour constant rate test only)
from wells AB-21D,/BR/BRL, AB-35D/BR, AB-20S/D, AB-23S/BRU, and CCR-23S/D at
frequencies outlined in Table 2.
4.2 Pumping System Installation
Once baseline conditions have been established, a submersible pump would be installed
in the selected pumping well by the Duke well-installation contractor. Two pumping
test would be conducted simultaneously. The initial test would be conducted in the
saprolite pumping well at the AB-21 cluster and the ash pumping well at the AB-35 well
cluster. The second test group would be conducted in the ash pumping well at the AB-
21 cluster and the saprolite pumping well at the AB-35 cluster.
The well-installation contractor would provide and install a flow meter capable of
continuously logging discharge rates and total flow in line with the pump discharge
line. The flow meter would be installed in such a way as to allow it to be full of water at
all times. This can be done by the installation of a 6-inch drop in the discharge line prior
to the flow meter and a subsequent 6-inch rise in the discharge line past the flow meter.
A minimum 1 foot of straight piping will have to be installed after the drop and before
the rise to ensure laminar flow through the transducer. Two ball valves should be
installed in the discharge line. One should be located before the drop, and one should
be located after rise. A photograph showing the general proposed configuration for the
flow meter is presented on Figure 5. A small diameter sampling port should also be
installed somewhere near the flow meter to allow for taking field water quality
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measurements and samples. The remaining discharge line should be extended away
from the test area (300-500 feet) to minimize potential influence of the discharged
groundwater. The AB-35 cluster will be pumped into a holding tank (to minimize head
pressure on the down whole submersible pump) and then discharged into one of the
Primary Ponds within the active ash basin (approximately 1,000 feet to the south). AB-
21 will be pumped to the discharge channel within the active ash basin (located
approximately 400 feet south of the well cluster).
After completion of the initial set of 72-hour pumping tests, the pump at both locations
would be moved to the second set of test locations (AB-21 ash pumping well and AB-35
saprolite pumping well).
4.3 Oversight of Step-Drawdown Tests
After the pumping system has been installed, the well will be allowed to fully recover
(assumed to be 12 hours). Once the pumping wells have fully recovered, SynTerra in
conjunction with the drilling contractor will conduct a step-drawdown test (initial test
in AB-21 saprolite pumping well and AB-35 ash pumping well). A typical step test
drawdown curve is presented in Figure 6.
A step-drawdown test (or step test) is a single-well pumping test designed to
investigate the performance of a pumping well under controlled variable discharge
conditions. During the step-drawdown test, an initial rate of 1 gallon per minute (gpm)
would be used. The discharge rate would be increased approximately 5 gpm per step
period (subject to change based on field observations). The duration of each step would
be approximately 2 hours (subject to change based on field observations). This duration
should allow wellbore storage effects to dissipate. This process would continue until the
well can no longer sustain the selected flow rate (curve does not flatten out) or a
maximum of 20 gpm flow rate is reached. After completion of the step test, the
pumping well would be allowed to return to static conditions (recovery tests).
Data from the step test will be used to determine an appropriately conservative initial
pumping rate (Qmax) for the constant-rate pumping tests. A Qmax resulting in a
drawdown after 72 hours that is approximately 25 percent of the water column (see
Section 5.2) should be calculated. At the end of the test and prior to shutting down the
pump, the flow will be adjusted to the selected Qmax using one of the ball valves. As the
pump is shut down, the remaining ball valve will be closed to prevent the discharge
line from draining into the well (which would affect recovery data).
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After completion of the initial set of 72-hour pumping test and recovery, the pump at
both locations will be moved to the second set of test locations (AB-21 ash pumping
well and AB-35 saprolite pumping well). A second set of step tests will be conducted at
these new locations following the same procedure.
4.4 Step Test Recovery
Once the step test is complete, the pump will be shut off and the flow meter will be
isolated (using ball valves upstream and downstream of the flow meter). The well will
be allowed to fully recover prior to the start of the constant-discharge test. It is
anticipated that recovery will take less than 12 hours. Monitoring of water levels will be
continued at the same frequency during recovery.
Once recovery is complete, water-level readings using the transducers will be stopped
and the data downloaded and analyzed.
4.5 Constant-Rate Pumping Test
Once the step-drawdown test has been completed, water levels in the pumping well
and affected observation wells have returned to static conditions, and transducers have
been stopped and reprogramed, a constant-rate pumping test will be conducted at each
location (initial two locations AB-21 saprolite pumping well and AB-35 ash pumping
followed by AB-21 ash pumping well and AB-35 saprolite pumping well). Prior to the
start of any active pumping, a round of water-level measurements will be collected in
the monitored wells for each test location (Table 2).
A constant-rate pumping test involves a control well that is pumped at a constant rate
while water-level response (drawdown) is measured in one or more surrounding
observation wells and in the pumping well. The goals of a constant-rate pumping test
are to estimate hydraulic properties of a saturated porous media such as T, K, and S and
to identify potential boundary conditions that may exist.
Discharge rate would be measured approximately every 15 minutes during the initial
portion of the test (first 4 hours). If discharge rate is stable, flow readings may be
conducted at longer intervals (based on field observations). Water-level transducers will
be set to record measurements every minute for the duration of the 72-hour test and
recovery period.
Once pumping has started, the test will run uninterrupted for up to 72 hours. During
that period, water levels will be continuously monitored, with data logging pressure
transducers and flow measurements continuously recorded (24 hours per day) using an
electronic flow meter that averages measurements at 5-minute intervals. Manual water-
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level readings would be collected every 2 hours at each selected well during active
pumping to provide automated data backup (see Table 2). Manual flow measurements
may be conducted based on field observations, as described earlier in this section.
Groundwater quality field readings and laboratory samples will be collected from the
discharge at selected intervals during active pumping (see Section 4.0).
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5.0 WATER-QUALITY MEASUREMENTS AND SAMPLING
In order to help identify the potential geochemical changes that may accrue in the ash
pore water during the active pumping, water-quality data will be collected during each
pumping test. Water-quality data will include the collection of both field reading and
laboratory samples. Particular emphasis will be placed on collection of conductivity and
pH data. Changes in water chemistry (conductivity and pH) may indicate contact with
a recharge boundary. Groundwater samples will be collected from the pumping well
discharge and analyzed for IMP constituent list.
Water-quality measurements will be collected from the discharge during the entire
constant-rate discharge test. Readings of pH, specific conductance, temperature,
dissolved oxygen, oxidation-reduction potential (ORP), and turbidity will be collected
once every hour during the test. To facilitate this, a YSI Pro Plus water-quality meter
will be plumbed into the discharge line. Flow through the meter will be regulated with
both upstream and downstream valves.
Water-quality samples for laboratory analysis will be collected from each of the
pumping wells prior to the step-drawdown test and once per day during the constant
rate pumping test. Each sample will be collected from a sampling port plumbed into the
discharge line. Water will be collected in laboratory-prepared sample bottles and
immediately placed on ice under strict chain-of-custody.
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Duke Energy Carolinas, LLC, Allen Steam Station SynTerra

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6.0 ANALYSIS OF WATER-LEVEL DATA
Analysis of water-level fluctuations in monitoring wells initially will be conducted
using Aqtesolv® Version 4.5. Baseline data, step test data, constant-rate discharge data
(pumping test), drawdown data, and analytical results will be summarized and
included as part of a technical memorandum on the results of the pumping tests.
6.1 Baseline Analysis
Baseline data will be evaluated to determine whether any long-term trends or
interference from nearby production wells are observable. If long-term data trends are
observed, the baseline data will be used to adjust the pumping test drawdown data to
compensate for the observed trend.
6.2 Step Test Analysis
Step test analysis will be conducted in the field. The Theis (1935) step-drawdown
procedure will be used to analyze data. Additional analytical methods (Dougherty-
Badu, 1984; Hantush-Jacob, 1955; Theis, 1935; and Hantush, 1961) may be used
depending on results of the step test drawdown data.
Step test results will be used to calculate a flow rate that will result in a drawdown of
approximately 25 percent of the saturated thickness after 72 hours (and excel spread
sheet will be provided for making these calculations).
6.3 Constant Discharge Rate Test Analysis
Final analysis methods of drawdown data are dependent on actual results of the tests.
Initially, it is assumed that the proposed pumping wells are confined. However,
drawdown data may indicate that they are semi-confined or unconfined. Water-levels
in ash pore water wells remained unchanged during development of saprolite wells
indicating the saprolite zone may be confined or semi-confined from the overlying ash
pore water with the ash basins. Additionally, drawdown may be observed only in the
pumping well. That would result in analysis of the data as a single-well pumping test. If
data indicates drawdown in one or more observation well, the test will be analyzed as a
multiple-well pump test. Suggested analytical methodologies for data analysis of both
single-well and multiple-well pump tests are outlined in the Technical Guidance
Manual for Hydrogeologic Investigations and Groundwater Monitoring, Chapter 4,
Slug and Pumping Test, Table 4.2 (single-well pump test) and Table 4.7 (multiple-well
pump test) (Clemson, February 1995) at: http://www.clemson.edu/ces/hydro/murdoch
/PDF%20Files/Pumping%20tests,%20EPA%20guidance.pdf
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7.0 REFERENCES
Theis, C.V., 1935. The relation between the lowering of the piezometric surface and the rate and
duration of discharge of a well using groundwater storage, Am. Geophys. Union Trans.,
vol. 16, pp. 519-524.
Dougherty, D.E and D.K. Babu, 1984. Flow to a partially penetrating well in a double
porosity reservoir, Water Resources Research, vol. 20, no. 8, pp. 1116-1122.
Hantush, M.S. and C.E. Jacob, 1955. Non-steady radial flow in an infinite leaky aquifer, Am.
Geophys. Union Trans., vol. 36, pp. 95-100.
Hantush, M.S., 1961b. Aquifer tests on partially penetrating wells, Jour. of the Hyd. Div.,
Proc. of the Am. Soc. of Civil Eng., vol. 87, no. HY5, pp. 171-194.

Pumping Test Work Plan Revision 1 May 2018
Duke Energy Carolinas, LLC, Allen Steam Station SynTerra

FIGURES

SOURCE: USGS TOPOGRAPHIC MAP OBTAINED FROM THE USGS STORE AT http://store.usgs.gov/b2c_usgs/b2c/startj%%%28xcm =r3standardpitrex_prd%%%29/ .do
� GRAPHIC SCALE
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,,,, IN FEET syn:'Cerra 148 RIVER STREET, SUITE 220 111111: GREENVILLE, SOUTH CAROLINA 29601 ----.....::'------------1 PHONE [phone]
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DUKE www.synterracorp.com
� .... ENERGY DRAWNBY:JOHNCHASTAIN DATE: 11/21/2017 • J PROJECT MANAGER:CHRIS SUTTELL CONTOUR INTERVAL.; 10 FEET
CAROLINAS LAYOUT: 1-1 SITE LOC MAP MAP DATE: 2016
FIGURE 12016 USGS TOPOGRAPHIC MAP ALLEN STEAM STATION DUKE ENERGY CORPORATION BELMONT, NORTH CAROLINA BELMONT & W CHARLOTTE NC QUADRANGLES
01/18/2018 5:33 PM P:\Duke Ener Carolinas\17.ALLEN\05.EHS CAMA Compliance Support\A,sscssment\CSAs\2018-01 CSA Update\DWG\DE ALLEN CSAUP FIG 1-1 SITE L0C MAP.dw
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DCANAL RDSOUTHPOINT RDS POINT RDARMSTRONG RDLOWER ARMSTRONG RDNOTES:
1. IT IS HEREIN NOTED THAT DUKE ENERGY IS NOT WAIVING THE RIGHT TO ACOMPLIANCE BOUNDARY(S) TO THE FULL EXTENT SET OUT IN THE LAW ORATTEMPT TO IMPAIR THE DEPARTMENT'S ABILITY TO CHANGE THE COMPLIANCEBOUNDARY(S) IN THE FUTURE, IF CIRCUMSTANCES WARRANT.
2. PROPERTY BOUNDARY PROVIDED BY DUKE ENERGY CAROLINAS.
3. NATURAL RESOURCES TECHNICAL REPORT (NRTR) PREPARED BY AMEC FOSTERWHEELER, INC., MAY 29, 2015.
4. AERIAL PHOTOGRAPHY OBTAINED FROM GOOGLE EARTH PRO ON OCTOBER 11,2017. AERIAL WAS COLLECTED ON OCTOBER 8, 2016.
5. DRAWING HAS BEEN SET WITH A PROJECTION OF NORTH CAROLINA STATEPLANE COORDINATE SYSTEM FIPS 3200 (NAD83).
FIGURE 2ALLEN PLA
WI
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D ICINITY MAPALLEN STEAM STATIONDUKE ENERGY CAROLINAS, LLCBELMONT, NORTH CAROLINADRAWN BY: B. YOUNGPROJECT MANAGER: C. SUTTELLCHECKED BY: L. DRAGO
DATE: 01/26/2018
148 RIVER STREET, SUITE 220GREENVILLE, SOUTH CAROLINA 29601PHONE [phone]www.synterracorp.com
P:\Duke Energy Progress.1026\00 GIS BASE DATA\Allen\Map_Docs\CSA_Supplement_2\Fig02-01 - Plant Vicinity Map.mxd
500 0 500 1,000250
GRAPHIC SCALE IN FEET
ASH BASIN WASTE BOUNDARY
INACTIVE ASH BASIN WASTE BOUNDARY
LANDFILL BOUNDARY
DORS FILLS BOUNDARIES
ASH BASIN COMPLIANCE BOUNDARY
LANDFILL COMPLIANCE BOUNDARY
DUKE ENERGY CAROLINAS ALLEN PLANTSITE BOUNDARY
<STREAM (AMEC NRTR 2015)
WETLAND (AMEC NRTR 2015)
LEGEND
AB-21SAB-21DAB-21SLACTIVE ASH BASAB-21BRAB-21BRLGROUNDSURFACE10 BGS10020020 BGS30 BGS40 BGS50 BGS60 BGS70 BGS80 BGS90 BGS100 BGSGROUNDSURFACE10 BGS20 BGS30 BGS40 BGS50 BGS60 BGS70 BGS80 BGS90 BGS100 BGS300ASHTRANSITION ZONEAB-21SAPROLITE110 BGS110 BGS120 BGS120 BGS130 BGS130 BGS05/22/2018 1:58 PMP:\Duke Energy Carolinas\17.ALLEN\_Admin\PCRs & Proposals\2018 Ash Pump Test\Work Plan\dwg\DE ALLEN Aquifer Recover 5-4-18.dwg148 RIVER STREET, SUITE 220GREENVILLE, SOUTH CAROLINA 29601PHONE [phone]www.synterracorp.comFIGURE 3PROPOSED LOCATIONS FORACTIVE ASH BASIN PUMPING TESTSALLEN STEAM STATIONPROJECT MANAGER:LAYOUT:DRAWN BY:CHRIS SUTTELLDATE:CHRIS BRUCE / C. NEWELLACTIVE3/29/1850050100GRAPHIC SCALEIN FEETCONCEPTUAL PROPOSED PUMPING TESTWELL SCHEMATICPROPOSED PUMPING WELL (ASH PORE WATER)PROPOSED OBSERVATION WELL (LOWER ASH PORE WATER)AB-21SWELL IN ASH PORE WATERPROPOSED OBSERVATION WELL (SAPROLITE)PROPOSED OBSERVATION WELL (UPPER ASH PORE WATER)ASH BASIN WASTE BOUNDARY (APPROXIMATE)LEGENDCCR-21SAB-21DWELL IN TRANSITION ZONEWELL IN ALLUVIUM/SAPROLITEEXISTING AB-21SLALLEN STEAM STATION253 PLANT ALLEN RDBELMONT, NORTH CAROLINAPROPOSED PUMPING WELL (SAPROLITE)AB-21BRWELL IN BEDROCKEXISTING AB-21SBGSBELOW GROUND SURFACEAREA OF CONCENTRATION IN GROUNDWATER ABOVE NC2L(SEE NOTE 1)NOTE:1.GENERALIZED AREAL EXTENT OF MIGRATION REPRESENTED BY NCAC 02LEXCEEDANCES OF MULTIPLE CONSTITUENTS (BORON AND ARSENIC) INMULTIPLE FLOW ZONES.AQUIFER TEST DISCHARGE LINE AND DIRECTION OF FLOWAB-21SSAB-21-PWSAB-21-PWSAB-21-OWALAB-21-OWAUCONCEPTUAL LAYOUT, ACTUAL LOCATIONS HAVENOT BEEN SURVEYEDAB-21SSAB-21-PWSAB-21-PWSAB-21-OWALAB-21-OWAUDISCHARGE LINE
FLOW METER CONFIGURATION
THIS SHOWS THE GENERAL CONFI GURATION OF THE DISCHARGE LINE AND FlLOW METER.
FLOW METER TYPE MAY VERY BUT SHOULD =oLLOW THIS GENERAL CONFIGUJRATION.
"' synTerra
148 RIVER STREET. SUITE 220 GREENVILLc, SOUTH CAROLIN/\ 29601
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DRAWN BY· CHRIS BRUCE DATE; 04/01/18 PROJECT MANAGER:CHRIS SlJTTEU LAYOUT: Flgul"8 3
Or;: 04/2018ll:201\M � DukeEner Carollras 17ALLEN\ Admln PC�&.Pro
FIGURE 5
TYPICAL FLOW METER CONFIGURATION
ALLEN STEAM STATION
DUKE ENERGY CAROLINAS, LLC
BELMONT, NORTH CAROLINA
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DRAWN BY:CHRIS BRUCE OATE:04/0'\,118 PROJECT MANAGER: CHRIS SUTTELL LAYOl/T: Figure 4
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Pumping Period 2, Layer: 1
Pumping Period 3, Layer: 1
Pumping Period 4, Layer: 1
Pumping Period 5, Layer: 1
Pumping Period 6, Layer:
Pumping Period 7, Layer:
Pumping Period 1
Pumping Period 1
Pumping Period 1
Pumping Period 1
Pumping Period 1
Pumping Period 1
Recovery Period
FIGURE 6
TYPICAL STEP TEST DRAWDOWN CURVE ALLEN STEAM STATION DUKE ENERGY CAROLINAS, LLCBELMONT, NORTH CAROLINA
Pumping Test Work Plan Revision 1 May 2018
Duke Energy Carolinas, LLC, Allen Steam Station SynTerra

TABLES
TABLE 1
WELL CONSTRUCTION DETAILS
PUMPING TESTS WELLS
ALLEN STEAM STATION
DUKE ENERGY CAROLINAS, LLC, BELMONT, NC
P:\Duke Energy Carolinas\17.ALLEN\05.EHS CAMA Compliance Support\Assessment\Pumping Tests\Work Plan\Revision 1\Table 1 - Well Construction - Allen Ash Basin Pumping Test as built Page 1 of 1
Identification Well Purpose
Approximate
Distance from
Pumping Well
(feet)
Monitoring Zone
Base of
Ash
(Feet BGS)
Borehole Diameter
(Inches)
Surface
Casing
Depth
(Feet BGS)
Well
Diameter
(Inches)
Total Well
Depth1
(Feet BGS)
Screen
Length
(Feet)
Top of Filter
Sand Pack
(Feet BGS)
Top of
Bentonite
Seal
(Feet BGS)
Active Ash Basin
AB-21-PWA Pumping NA Lower Ash Pore Water 50 13 NA 6 48 10 33 27.5
AB-21-PWS Pumping NA Shallow (Saprolite)54 13* (0-57 feet BGS)
10 (57-89 feet BGS) 57*6 89 10 67 53
AB-21-OWAU Observation 15 Upper Ash Pore Water 54 6 NA 2 20 5 10 7
AB-21-OWAL Observation 15 Lower Ash Pore Water 54 6 NA 2 53 5 43 40
AB-21S Observation 30 Upper Ash Pore Water 53 8 NA 2 21 15 4 2
AB-21SL Observation 30 Lower Ash Pore Water 53 8 NA 2 45 10 32 29
AB-21SS Observation 30 Shallow (Saprolite)54 10 (0-60 feet BGS)
6 (60-89 feet BGS)60**2 89 10 74 68
Inactive Ash Basin
AB-35-PWA Pumping NA Lower Ash Pore Water 60 13 NA 6 58 10 43 38
AB-35-PWS Pumping NA Shallow (Saprolite)63 13* (0-65 feet BGS)
10 (65-99 feet BGS)65*6 99 10 84 63
AB-35-OWAU Observation 15 Upper Ash Pore Water NA 6 NA 2 45 5 35 30
AB-35-OWAL Observation 15 Lower Ash Pore Water NA 6 NA 2 56 5 48 39.5
AB-35S Observation 30 Upper Ash Pore Water 56.5 8 NA 2 50 15 34 32
AB-35-OWAL30 Observation 30 Lower Ash Pore Water NA 6 NA 2 55 5 47 40
AB-35SS Observation 30 Shallow (Saprolite)61.5 10 (0-65 feet BGS)
6 (65-99 feet BGS)65**2 99 10 84 63
Prepared by: CHB Checked by: CJS
Notes:
Well construction details are approximate and wells are not yet surveyed for horizontal and vertical control.
1 - "Total Well Depth" is the depth to the bottom of the screened interval, as measured during well installation.
*Temporary steel casing left in-place during well installation
**Permanent 6-inch PVC surface casing
Bold - Indicates existing well location
BGS - Below ground surface
NA - Not applicable
PWA - Pumping well Ash
PWS - Pumping well Shallow (saprolite)
OWAU - Observation well ash upper
OWAL - Observation well ash lower
OWAL30 - Observation well ash lower 30 feet offset from pumping well
SS - Shallow (saprolite), to distinguish between ash pore water wells considered by HDR to be "S" (shallow) wells.
TABLE 2
SUMMARY OF PUMPING WELLS AND OBSERVATION WELLS
ALLEN STEAM STATION
DUKE ENERGY CAROLINAS, LLC, BELMONT, NC
P:\Duke Energy Carolinas\17.ALLEN\05.EHS CAMA Compliance Support\Assessment\Pumping Tests\Work Plan\Revision 1\Table 2 - Summary of Proposed Pump and Observation WellsTable 2 - Summary of Proposed Pump
and Observation Wells Page 1 of 1
Well ID Baseline Data
Collection1
Step Test
(Ash)
Pumping Test2
(Ash)
Step Test
(Saprolite)
Pumping Test2
(Saprolite)
Pressure
Transducer Data
Collection
Location
Manual Water Level
Readings Frequency3
AB-21-PWA X X X X X 2 Hours
AB-21-PWS X X X X X 2 Hours
AB-21-OWAU X X X X 2 Hours
AB-21-OWAL X X X X 2 Hours
AB-21S X X X X 2 Hours
AB-21SL X X X X 2 Hours
AB-21SS X X X X 2 Hours
AB-21D/BR/BRL X X X 3 Times per Day
AB-20D X X 3 Times per Day
AB-23S/BRU X X 3 Times per Day
CCR-23S/D X X 3 Times per Day
AB-35-PWA X X X X X 2 Hours
AB-35-PWS X X X X X 2 Hours
AB-35-OWAU X X X X 2 Hours
AB-35-OWAL X X X X 2 Hours
AB-35-OWAL30 X X X X 2 Hours
AB-35S X X X X 2 Hours
AB-35SS X X X X 2 Hours
AB-35D/BR X 3 Times per Day
Prepared by: CHB Checked by: CJS
Notes:
1 - In addition to transducer data, manual water levels will be collected as outlined.
2 - In addition to transducer data, manual water levels will be collected as outlined.
3 - Manual water levels will be collected during the 72 hour constant rate test only.
PWA - Pumping well Ash
PWS - Pumping well Shallow (saprolite)
OWAU - Observation well ash upper
OWAL - Observation well ash lower
OWAL30 - Observation well ash lower 30 feet offset from pumping well
SS - Shallow (saprolite), to distinguish between ash pore water wells considered by HDR to be "S" (shallow) wells.
Inactive Ash Basin
Active Ash Basin