NC0003417_Final Interim Action Plan_Text Only_20160428

410
synTerra
INTERIM ACTION PLAN
H.F. LEE ENERGY COMPLEX
1199 BLACK JACK CHURCH ROAD
GOLDSBORO, NC 27530
APRIL 2016
PREPARED FOR
DUKE ENERGY PROGRESS, LLC
RALEIGH, NORTH CAROLINA
DUKE
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ENL
ROGRESS
Jug . n Mahan, NC PG 2026
Project Manager
Kathy ebb, NC PG 1328
Project Director

Interim Action Plan April 2016
H.F. Lee Energy Complex SynTerra
TABLE OF CONTENTS
SECTION PAGE
1.0 BACKGROUND.......................................................................................................1-1
1.1 Area of Interest...................................................................................................... 1-2
1.2 Constituents of Interest........................................................................................ 1-3
2.0 INTERIM ACTION OBJECTIVES......................................................................... 2-1
3.0 ADDITIONAL ASSESSMENT ACTIVITIES....................................................... 3-1
4.0 INTERIM ACTION TASKS.................................................................................... 4-1
4.1 Permitting.............................................................................................................. 4-1
4.2 Property Acquisition............................................................................................ 4-2
4.3 Pilot Test................................................................................................................ 4-2
4.3.1
Pilot Test Scope of Work.................................................................................
4-2
4.3.2
Background Information................................................................................
4-2
4.3.3
Installation and Development of Groundwater Extraction and
Site Layout — Active Basins
Figure 4-1
ObservationWells..........................................................................................
4-3
4.3.4
Extraction -Well Step -Drawdown Test..........................................................
4-4
4.3.5
Extraction -Well 36 -Hour Pumping Test ........................................................
4-5
4.3.6
Data Evaluation and Report Preparation......................................................
4-6
5.0 SCHEDULE............................................................................................................... 5-1
LIST OF FIGURES
Figure ES -1
Plan View Conceptual Site Model
Figure 1-1
Site Location Map
Figure 1-2a
Site Layout — Inactive Basins
Figure 1-2b
Site Layout — Active Basins
Figure 4-1
Pilot Test Layout
LIST OF TABLES
Table 1-1 Groundwater Monitoring Results
Table 1-2 Groundwater Monitoring Exceedances
Table 1-3 Provisional Background Concentrations - Surficial Aquifer
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LIST OF APPENDICES
Attachment 1 U.S. Corps of Engineer — Wilmington District
General Permit (Regional and Nationwide) Verification
Attachment 2 Test Recovery Well Permit Application
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Interim Action Plan
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H.F. Lee Energy Complex SynTerra
EXECUTIVE SUMMARY
This Interim Action Plan has been prepared for the Duke Energy Progress, LLC (Duke
Energy) H. F. Lee Energy Complex, and provides an update on activities to follow the
Comprehensive Site Assessment (CSA) and Corrective Action Plan (CAP). In
accordance with the North Carolina General Assembly Session Law 2014-122, the Coal
Ash Management Act (CAMA) of 2014, the CSA was submitted to the North Carolina
Department of Environmental Quality (NCDEQ) on August 5, 2015 and the CAP was
submitted in two parts (CAP Part 1 on November 2, 2015 and CAP Part 2 on February 1,
2016).
The H.F. Lee coal ash management areas include the 171 -acre inactive ash basins and
the 143 -acre active ash basin. Interim actions will include additional assessment to
further delineate potential influence in areas around both the inactive and active basins,
additional background well installations and a pilot test to determine aquifer
characteristics in preparation for remedial action design.
A Settlement Agreement between NCDEQ and Duke Energy signed on September 29,
2015, requires accelerated remediation to be implemented at sites that demonstrate off-
site groundwater impacts. Historical and CSA assessment indicates the potential for off-
site impact east of the active basin at H.F. Lee. Figure ES -1 illustrates the area of interest,
the extent of boron above 2L and shows the general area to be addressed for accelerated
remediation. Arsenic and boron have been identified as constituents which occur at
levels above 2L and greater than proposed background concentrations. Arsenic and
boron impact which has the potential to migrate beyond the compliance boundary and
off site will be the focus of remedial efforts. Details for the pilot test procedure to aid in
remedial action design are provided in this report.
Access for additional monitoring well and pilot test well installation requires obtaining
Erosion and Sediment Control (E&SC) permitting, a wetlands permit and an extraction
well permit. A schedule of activities which spans final permit approval in May 2016 to
reporting of pilot test results and preliminary groundwater remediation system design
in November 2016 is provided herein.
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1.0 BACKGROUND
Duke Energy Progress, LLC (Duke Energy) owns and operates the H.F. Lee Energy
Complex (Lee Plant) located at 1199 Black Jack Church Road, Goldsboro, North
Carolina. The property encompasses approximately 2,100 acres, including the
approximately 314 -acre ash basins (171 -acre inactive ash basins and 143 -acre active ash
basin). The property includes the cooling pond (Quaker Neck Lake), located to the east
of the plant operations area. The Neuse River flows through the property as shown on
Figure 1-1. The layout of the Lee Plant is shown on Figures 1-2a and 1-2b.
In order to satisfy requirements of the North Carolina Coal Ash Management Act (NC
CAMA), a Comprehensive Site Assessment (CSA) and Corrective Action Plan (CAP)
Parts 1 and 2 were prepared and submitted to the NC Department of Environmental
Quality (DEQ). The most recent document, the CAP Part 2, was submitted to DEQ on
February 1, 2016.
The CAP (Parts 1 and 2) was designed to describe means to restore groundwater quality
to the level of the standards, or as close as is economically and technologically feasible
in accordance with T15A NCAC 02L .0106. Exceedances of numerical values contained
in Subchapter 2L and Appendix 1 Subchapter 02L (IMACs) at or beyond the compliance
boundary were determined to be the basis for corrective action with the exception of
parameters for which naturally occurring background concentrations are greater than
the standards. The CAP Part 2 identified the preferred corrective action, developed a
detailed conceptual design, and provided implementation and monitoring plans.
In addition to CAMA, a Settlement Agreement (Agreement) between DEQ and Duke
Energy signed on September 29, 2015, provided an additional requirement to
implement accelerated remediation at sites that demonstrated off-site groundwater
impacts. Based on data collected for the CSA, potential off-site groundwater impacts
were identified north and east of the active ash basin at the Lee Plant. Duke Energy
provided an Accelerated Remediation Summary to DEQ on February 17, 2016 which
supplemented and updated information included with the CAP Part 2. In
correspondence dated March 28, 2016, DEQ acknowledged receipt of the Remediation
Summary and requested additional information. This report is prepared in response to
the DEQ request for additional information related to the accelerated remediation
activities.
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1.1 Area of Interest
CSA and historical groundwater monitoring results indicate that areas to the east and
north of the active basin have potential to have constituent concentrations greater than
2L beyond the compliance and property boundaries. Historical results prior to the
initiation of compliance monitoring in 2010 are limited. A comprehensive listing of
groundwater sampling results for monitoring wells in these areas is included as Table
1-1.
East Side Active Basin
Based on groundwater monitoring results from wells east of the active basin, arsenic
(CMW-06 and CMW-06R) and boron (CMW-6, CMW-6R and CMW-05) are present at
concentrations above 2L in the surficial aquifer (see Figure ES -1 for the extent of boron
above 2L and Figure 1-2b for well locations). Water level measurements from these and
other nearby wells indicate that there is a component of radial flow to the east (toward
CMW-06R) from the east side of the active basin, before groundwater flow returns to a
natural flowpath south toward the Neuse River (see Figure ES -1). CMW-06R
constituent concentrations have been less than 2L standards due to seasonal variability.
Results from monitoring wells northeast of the active basin (BGMW-10, AMW-14S and
AMW-15S) have not indicated arsenic and boron exceedances. This indicates that radial
flow and constituent migration is towards CMW-06 and CMW-06R areas. CMW-06R is
located at the Compliance Boundary near the property line.
North Side Active Basin
Historical sampling of monitoring well MW -1 just north of the active basin (see Figure
1-2b), indicate exceedances of 2L for arsenic and boron. The last sampling event in
which the boron concentration exceeded the 2L was in September 2013. However, the
most recent data from December 2015, January and March 2016 indicated boron
concentrations of 260 �tg/L, 216 µg/L and 148 µg/L respectively, which are well below
the 2L of 700 �tg/L.
Arsenic concentrations also appear to be on a downward trend. The highest arsenic
result of 440 µg/L was from December 2007, but the most recent data from December
2015, January and March 2016 indicated concentrations of 11.8 µg/L, 6.61 µg/L and 11.4
µg/L. Two results are only slightly greater than the 2L of 10 µg/L.
The area of MW -1 will continue to be monitored, but at this time it is not considered for
accelerated remediation.
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1.2 Constituents of Interest
Exceedances of 2L or IMAC for arsenic, boron, cobalt, iron, manganese and vanadium
are observed in samples from the monitoring wells east and north of the active basin
(Table 1-2). Provisional background levels for these parameters are shown below.
Table 1-3
Provisional Background Concentrations
Notes: Prepared by: DMY Checked By: KDB
Values reported in micrograms per liter for each constituent
* Interim Maximum Allowable Concentration (IMAC) of the 15A NCACO2L Standard,
Appendix 1, April 2013
BOLDED values exceed 2L or IMAC
ND — Not detected above laboratory reporting limit
Turbidity results >10 not included
Data from 5 sampling events between March 2015 and March 2016
Cobalt, iron, manganese and vanadium concentrations in wells east and north of the
active basin likely reflect background conditions. Arsenic and boron have been
recognized as potential drivers for remediation.
Early (2010 and prior) results from monitoring well MW -1 indicated isolated
exceedances for antimony, beryllium, chromium, lead and thallium. These results are
likely related to samples with high turbidity and similar results have not been observed
in any recent sampling events.
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Range of
Analytical
Observed
Provisional
NCAC 2L
Standard or
Parameter
Background
Background Value
Values
IMAC
Arsenic
ND
ND
10
Boron
ND
ND
700
Cobalt
1.2-14.9
14.9
1*
Iron
14-25,900
25,900
300
Manganese
12-880
880
50
Vanadium
.307-0.627
0.63
0.3*
Notes: Prepared by: DMY Checked By: KDB
Values reported in micrograms per liter for each constituent
* Interim Maximum Allowable Concentration (IMAC) of the 15A NCACO2L Standard,
Appendix 1, April 2013
BOLDED values exceed 2L or IMAC
ND — Not detected above laboratory reporting limit
Turbidity results >10 not included
Data from 5 sampling events between March 2015 and March 2016
Cobalt, iron, manganese and vanadium concentrations in wells east and north of the
active basin likely reflect background conditions. Arsenic and boron have been
recognized as potential drivers for remediation.
Early (2010 and prior) results from monitoring well MW -1 indicated isolated
exceedances for antimony, beryllium, chromium, lead and thallium. These results are
likely related to samples with high turbidity and similar results have not been observed
in any recent sampling events.
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2.0 INTERIM ACTION OBJECTIVES
Interim action activities will consist of additional assessment at both the active and
inactive basins and pilot testing with potential of installing a groundwater extraction
system on the east side of the active basin. Specific objectives are as follows:
'67 Monitoring wells IMW-045, IMW-04BC, IMW-05S and IMW-05BC will be
installed to further delineate potential ash basin influence south of the inactive
basins (Figure 1-2a).
E7 Background monitoring wells AMW-16BC, AMW-17S and AMW-17BC will be
installed north of the active basin to increase the available background data set
(Figure 1-2b).
'67 Monitoring wells AMW-18S and AMW-18BC will be installed to further
delineate potential ash basin influence southeast of the active basin (Figure 1-2b).
'61' A pilot test will be conducted east of the active basin to determine aquifer
characteristics needed to evaluate and design a remedial action strategy in the
area.
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3.0 ADDITIONAL ASSESSMENT ACTIVITIES
Additional monitoring wells are to be installed at both the inactive and active basins.
Details are provided below.
Inactive Basins - Additional Monitoring Wells
Two well pairs (IMW-04S, IMW-04BC, IMW-05S and IMW-05BC) will be installed south
of the inactive ash basins to further define the horizontal and vertical extent of
constituents (Figure 1-2a). Each of these well pairs will consist of wells in the surficial
and in the Cape Fear deposits.
Active Basins - Additional Monitoring Wells
Monitoring wells AMW-16BC, AMW-17S and AMW-17BC are planned to be installed
north of the active basin in order to provide more background data further from the
basin. Monitoring wells AMW-18S and AMW-18BC are planned to be installed
southeast of the active basin in order to provide additional assessment for this area with
a focus on accelerated remediation of arsenic and boron concentrations greater than 2L
standards.
Soil samples will be collected from the borings installed for new well installation. Soil
samples will be collected from screened intervals in order to provide additional data
points for future refinement of the monitored natural attenuation (MNA) evaluation
which was included with CAP Part 2. Groundwater samples will be collected as soon as
feasible after well installation and development.
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4.0 INTERIM ACTION TASKS
Interim action tasks include securing permits for well installation, potential property
acquisition to aid in assessment and remediation access, and pilot testing.
4.1 Permitting
Required permits for interim action well installations include the following:
Erosion and Sediment Control (E&SC) Plan
The E&SC plan and permit are administered by the DEQ Washington Regional Office.
Initial E&SC plans and drawings were presented to DEQ in a meeting between DEQ
Duke Energy and SynTerra representatives at the Washington Regional Office on
January 12, 2016. The E&SC plan was based upon the previously approved plan for
CSA well installations conducted in 2015. DEQ requested revisions to the E&SC
drawings during the January 12, 2016 meeting. The revised plans were submitted to
DEQ on January 21, 2016. DEQ did not respond or review plans until early April. A
second meeting at the Washington Regional Office between DEQ Duke Energy and
SynTerra representatives was arranged and held on April 20, 2016. At the meeting, DEQ
requested additional revisions to the E&SC drawings. Revised drawings are in
preparation as of the date of this report.
Wetlands Permit
Wetlands permitting is administered by the U.S. Army Corps of Engineers (USCOE) —
Wilmington Office. Approval for the additional assessment wells (IMW-04S, IMW-
0413C, AMW-18S and AMW-18BC) was obtained on January 21, 2016. Documentation is
provided as Attachment 1. Duke Energy has requested approval for installation of the
pilot test wells. This documentation is expected in late April/early May.
Extraction Well Permit
The extraction well permit is administered by the DEQ Washington Regional Office.
The permit application was submitted on April 19, 2016. Documentation is provided as
Attachment 2. Approval is anticipated in May 2016.
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4.2 Property Acquisition
Duke Energy is currently pursuing the purchase of parcels located north and east of the
active ash basin. Existing monitoring wells are located near the current property
boundary in these areas.
4.3 Pilot Test
A conceptual approach to address off-site migration of arsenic and boron has been
developed. Groundwater would be extracted via recovery wells or a groundwater
collection trench on the east side of the active basin to limit further migration of
constituents. The area is shown on Figure ES -1. Pilot testing is proposed to gather
aquifer -specific parameters to aid with remedial action design.
4.3.1 Pilot Test Scope of Work
The groundwater remediation pilot test for H.F. Lee Energy Complex will
provide aquifer information needed to develop the remediation system design. A
summary report will present pilot test results and synthesize new data with that
from previous assessment activities.
The area of the pilot test and pilot test well locations are shown on Figure 3. The
area is located to the east of the active basin and partially within mapped
wetlands. Details of the pilot test procedure are provided below.
4.3.2 Background Information
Surficial soils at the site are comprised of Quaternary alluvial deposits associated
with the adjacent Neuse River, consisting primarily of silty and clayey sands
with interbedded clay, which contain the surficial aquifer. Underlying this
formation, at depths of around 20 -feet below grade in the area of the active basin,
is the Black Creek Formation, consisting primarily of dark, carbonaceous -rich,
clay. The Black Creek Formation confines the lower boundary of the surficial
aquifer. Depths to groundwater in the area of the active basin are generally
approximately two to five feet below grade. Overall groundwater flow in the
area of the active basin is generally southerly toward the Neuse River.
Work tasks to be conducted for the aquifer testing are listed as follows.
00 Installation and development of groundwater extraction and
observation wells.
if Extraction -well step -drawdown test.
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0 Extraction -well constant -rate 36 -hour pumping test.
t1 Data evaluation and report preparation.
Details of the above work tasks are presented as follows.
4.3.3 Installation and Development of Groundwater
Extraction and Observation Wells
One groundwater extraction well and five observation wells will be installed to
facilitate the aquifer test. Approximate proposed locations of the extraction and
observation wells are shown in Figure 4-1. The observation wells will be
installed at distances from the extraction well varying from approximately 15
feet to 150 feet, and in various orientations relative to the extraction well, to
evaluate water -table drawdown response from groundwater extraction with
respect to both distance and direction.
The wells will be installed by a North Carolina licensed driller under supervision
by SynTerra. Extraction and observation well specifications are summarized as
follows.
The groundwater extraction well will be installed to the top of the Black Creek
Formation or, if feasible, to approximately 2 -feet below the top of the Black Creek
Formation to a depth of approximately 20 -feet below grade. Samples for sieve
analysis will be taken from the screen interval to enhance the design of the
extraction well. The sand and screen types are subject to change based on the
sieve analysis results. The anticipated well construct will utilizing 6 -inch inside
diameter (I.D.) Schedule 40 PVC well casing and a 10 -feet length of FreeFlow®,
well screen, or equivalent. FreeFlow Screen is manufactured by wrapping a V-
shaped profile 'wire' cylindrical around longitudinal placed support rods
creating a continuous non -clogging slot opening, providing free flow and
optimal sand control.
The observation wells will also be installed to the top of the Black Creek
Formation as described above. The wells will be constructed utilizing 2 -inch I.D.
Schedule 40 PVC casing and 10 -feet lengths of Schedule 40 machine -slotted
screen (0.010 -inch slots).
A sand pack will be installed in the annular space for each extraction and
observation well from the base of the well boring to approximately 2 -feet above
the top of well screen. A granular bentonite seal will be installed in each well
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annulus above the sand pack, and the remaining annular space will be tremie-
grouted to grade with cement/bentonite slurry. The extraction and observation
wells will be completed within steel protective stick-up casings set within
concrete pads.
The extraction and observation wells will be pumped or bailed (for the
observation wells) until the well -development water is reasonably clear of
suspended solids and field measurements of development -water pH, specific
conductance, and temperature indicate stabilized readings.
Drill cuttings generated from the well installations will be spread onto the
ground surface near each well location but will not be placed in wetlands. Well -
development water will be discharged to the ground surface at each well
location.
4.3.4 Extraction -Well Step -Drawdown Test
A one -day step -drawdown test will be completed for the groundwater -extraction
well to identify the optimal groundwater extraction rate to use for the
subsequent 36 -hour constant -rate pump test. The step -drawdown test will be
conducted in accordance with the following procedure.
The static depth to groundwater will be measured in the groundwater extraction
well utilizing an electronic groundwater -level meter. The static groundwater
column in the extraction well will be calculated.
A submersible pump with variable frequency drive (VFD) controller will be
inserted into the extraction well to a depth of approximately 1 -foot from the well
bottom.
Upon stabilization of the groundwater level in the extraction well following
pump insertion, operation of the submersible pump will be initiated at the lowest
groundwater extraction rate capable of producing flow from the well, utilizing
the VFD controller. Groundwater levels will be measured utilizing the
groundwater -level meter at a frequency of approximately once per minute, and
the groundwater -level versus elapsed time readings will be recorded.
Upon stabilization of groundwater levels at the initial setting, the groundwater
pumping rate will be increased utilizing the controller VFD, with the amount of
increase based on the degree of groundwater drawdown observed under the
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initial pump setting. Groundwater drawdown versus time measurements will
continue as described above.
The above procedure will be repeated until groundwater drawdown equivalent
to approximately 80% of the available groundwater column is observed. The
VFD setting at this pumping rate (the "optimal" pumping rate) will be recorded.
Upon stabilization of groundwater levels at the optimal pumping rate,
groundwater pumping will be ceased, and groundwater recovery versus time
data will be collected until the well achieves at least approximately 85% of its
original level, or over a maximum of 2 hours.
Dewatering of the active ash basin was implemented on April 21, 2016. Water
from the active ash basin is currently being discharged through the NPDES
outfall. Groundwater extracted for the pilot test will be transferred to the active
basin upon DEQ concurrence. This method will prevent pumped water from
infiltrating into the extraction wells cone -of -depression.
4.3.5 Extraction -Well 36 -Hour Pumping Test
Water levels will be allowed to equilibrate for three days to a week after the step -
drawdown test before the pumping test. The constant -rate 36 -hour pumping test
will provide data for use in evaluating aquifer hydraulic parameters. The test
will be conducted as follows.
Prior to initiation of the pumping test, a submersible pump will be installed in
the extraction well as described above for the step -drawdown test. In addition,
pressure transducers with integrated digital data loggers will be installed within
the five observation wells. Prior to installing the pump and transducers, static
groundwater levels will be measured in the extraction and observation wells.
Prior to initiating the pumping test (i.e., one -day following pump and transducer
installations), static groundwater levels will be measured in the extraction well
and observation wells, plus any other accessible site monitoring wells in the
pumping test area. At least one "background" monitoring well, located in an
area where no water -table drawdown from the pump test would be reasonably
expected, will be included in the monitoring -well network for the pumping test.
The submersible pump will be started at the controller VFD setting resulting in
the optimal pumping rate during the step -drawdown rate. Transducer/data-
logger recordings for the observation wells will be initiated simultaneously with
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the initiation of extraction -well pumping. To account for the majority of
groundwater drawdown that typically occurs during the early stages of pump
tests, the data -loggers will be programmed to record transducer readings in
accordance with a logarithmic schedule. By this manner, readings will be
collected at short (<1 second) intervals at the commencement of pumping, then
the frequency of readings will be gradually reduced to a minimum of once per 30
minutes (for example) after the initial period of rapid groundwater drawdown is
over.
Groundwater drawdown in the extraction well will be measured manually
approximately once per 30 minutes using an electronic meter. Groundwater
levels in remaining accessible site monitoring wells, as per above, will be
measured once every 30 minutes to 2 hours depending on accessibility.
Following an elapsed time of approximately 36 -hours, groundwater extraction
will be ceased. Simultaneous with the cessation of pumping, the observation -
well transducers/data-loggers will be reset to record groundwater recharge data
in accordance with the same logarithmic schedule used for the pumping portion
of the test.
Groundwater extracted during the 36 -hour pumping test will be transferred to
the active basin upon DEQ concurrence.
The submersible pump used for the step -drawdown test and 36 -hour pumping
test will be powered utilizing a gasoline -powered generator. Two generators
will be used on an alternating basis during the pump test. Re -fueling of each
respective generator will be conducted while it is in its off cycle.
Groundwater sampling and analysis of the recovery well will be conducted at
the beginning and end of the 36 hour pump test to determine chemistry
variability for NPDES permitting.
4.3.6 Data Evaluation and Report Preparation
Groundwater versus time drawdown data will be analyzed utilizing log -log
curve -matching (e.g., Theis method) and/or semi -log curve -matching (e.g., Jacob
method) techniques to estimate the hydraulic conductivity and storage
coefficient for the shallow site aquifer in the test area. Drawdown data will be
further evaluated utilizing spatial and graphical analyses to evaluate potential
zones of influent/capture from extraction -well pumping.
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A project report will be prepared that details methods, results, and conclusions
of the aquifer testing. The report will include test -data output, curve -matching
diagrams, maps/graphs for the drawdown analyses, and extraction/observation
well logs.
4.2.7 Groundwater Modeling
A site-specific flow and transport model was constructed and calibrated for the
site as part of CAP activities. The existing groundwater model will be used to
run simulations of the drawdown effects of the pilot test to evaluate potential
effects to the wetlands and refine modeling predictions associated with
groundwater remedial options. Results are anticipated to be used to assist in
obtaining U.S. Corps of Engineers approval for installation and long term system
operation of a groundwater collection system.
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5.0 SCHEDULE
A schedule of interim action and additional assessment items follows:
�? Negotiation of parcel acquisition east of the active ash basin — Ongoing
17 E&SC Permit - May 2016
167 USCOE permit for well installation in wetlands - May 2016
17 Extraction Well Permit - May 2016
147 Access to drilling locations - May 2016
17 Additional assessment well installations - May 2016
01 Pilot test well installation - June 2016
41 Conduct pilot test - July 2016
4' Pilot test report - September 2016
01 Initiate permitting for groundwater extraction system - November 2016
1? Complete feasibility study and preliminary groundwater remediation system
design - November 2016
161, Submit CSA Supplemental report summarizing additional assessment findings -
2016
1611 Obtain permitting approval, including modification to the NPDES permit, for
groundwater extraction treatment system - March 2017.
+611 Initiate construction of the groundwater extraction treatment system - Timeframe
is difficult to determine until initital aquifer testing is completed and permitting
agencies have provided input.
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Plan\Final Interim Action Plan HF Lee April.docx