4300 MarketPointe Drive, Suite 200
Minneapolis, MN 55435
952.832.2600
www.barr.com
CCR Groundwater Monitoring System Certification
Report
Black Dog Generating Plant
Burnsville, Minnesota
Prepared for
Northern States Power Company
April 2019
ii
CCR Groundwater Monitoring System Certification Report
Black Dog Generating Plant
Burnsville, Minnesota
April 2019
Contents
1.0 Introduction ........................................................................................................................................................................... 1
2.0 Site Setting ............................................................................................................................................................................. 4
2.1 CCR Management........................................................................................................................................................... 4
2.1.1 Former Ash Basins (1950s – 1970s) .................................................................................................................... 4
2.1.2 CCR Units (1970s – 2017) ....................................................................................................................................... 4
2.2 Geology .............................................................................................................................................................................. 5
2.2.1 Non-Native Deposits ............................................................................................................................................... 5
2.2.2 Native Deposits .......................................................................................................................................................... 5
2.3 Hydrogeology .................................................................................................................................................................. 6
2.3.1 Groundwater Occurrence ....................................................................................................................................... 6
2.3.2 Groundwater Flow Directions and Rates .......................................................................................................... 6
3.0 CCR Unit Groundwater Monitoring System .............................................................................................................. 8
3.1 Network Installation and Development ................................................................................................................. 8
3.2 Background Wells ........................................................................................................................................................... 9
3.3 Downgradient Wells ....................................................................................................................................................10
4.0 References ............................................................................................................................................................................11
iii
List of Tables
Table 1 Rule Requirements and Compliance
Table 2 Hydraulic Conductivity Summary
Table 3 Well Construction Details
Table 4 Monitoring System Summary
List of Figures
Figure 1 Site Location
Figure 2 Site Map
Figure 3 Cross Section Locations
Figure 4 Geologic Cross Section A-A’
Figure 5 Geologic Cross Section B-B’
Figure 6 Geologic Cross Section C-C’
Figure 7 Geologic Cross Section D-D’
Figure 8 Water Table Map, December 11, 2017
Figure 9 Water Table Map, October 22, 2018
iv
Certifications
I hereby certify that I have examined the facility and, being familiar with the provisions of 40 CFR 257
Subpart D, attest that the groundwater monitoring system has been selected and that this Groundwater
Monitoring System Report has been prepared in accordance with good engineering practice, including
consideration of applicable industry standards and the requirements of 40 CFR §257.91. I hereby certify
that the monitoring system is adequate for this facility. I further certify that I am a duly Licensed
Professional Engineer under the laws of the state of Minnesota.
Jeremy Gacnik Date
PE #: 49292
Revision Date Summary of Revisions
04/15/2019
1
1.0 Introduction
Northern States Power Company, a Minnesota corporation doing business as Xcel Energy (NSPM),
formerly operated three coal combustion residuals (CCR) units, referred to as Ash Ponds 1, 2 and 3
(collectively the Ash Ponds) at its Black Dog Generating Plant (Plant or Site), located in Burnsville, MN
(Figure 1). Coal operations ceased at the Plant in April 16, 2015 and CCR discharges to the Ash Ponds
ceased prior to October 19, 2015. Decommissioning of the Plant’s coal-fired boilers and associated
equipment eliminated placement of CCR related materials in the Ash Ponds. The remaining wastewater
discharged from the Plant was redirected to an alternate discharge system in 2016, thereby allowing for
closure of the Ash Ponds and their associated components. Subsequently, the Ash Ponds were excavated
and backfilled between October 2016 and November 2017.
The United States Environmental Protection Agency (EPA) published a final rule to regulate the disposal of
CCR as solid waste under Subtitle D of the Resource Conservation and Recovery Act (RCRA), 40 CFR Parts
257 and 261 (CCR Rule) in 2015. This report has been prepared to describe the groundwater monitoring
system for the former CCR units and how the groundwater monitoring system has been designed to meet
the requirements of the Rule. This report fulfills the requirement of §257.91(f):
The owner or operator must obtain a certification from a qualified professional engineer
stating that the groundwater monitoring system has been designed and constructed to
meet the requirements of this section.
Specific requirements and demonstration of compliance of the groundwater monitoring system to Part
§257.91 of the Rule are summarized in Table 1 below, and further described in Sections 2.0 through 4.0 of
this report.
2
Table 1 Rule Requirements and Compliance
CCR Rule Requirements (§257.91) Compliance with CCR Rule
Performance Standard (a): The owner or operator of a CCR unit must install a
groundwater monitoring system that consists of a sufficient number of wells,
installed at appropriate locations and depths, to yield groundwater samples from
the uppermost aquifer” that:
(1) Accurately represent the quality of background groundwater that has not been
affected by leakage from a CCR unit. A determination of background quality
may include sampling of wells that are not hydraulically upgradient of the CCR
management area where:
a. Hydrogeologic conditions do not allow the owner or operator of the
CCR Unit to determine what wells are hydraulically upgradient; or
b. Sampling at other wells will provide an indication of background
groundwater quality that is representative or more representative than
that provided by the upgradient wells; and
(2) Accurately represent the quality of groundwater passing the waste boundary of
the CCR unit. The downgradient monitoring system must be installed at the
waste boundary that ensures detection of groundwater contamination in the
uppermost aquifer. All potential contamination must be monitored.
See Section 2.0 (Site
Setting) and Section 3.0
(CCR Unit Groundwater
Monitoring System) of this
report.
Well Spacing and Site Specific Information (b): The number, spacing, and depths
of monitoring systems shall be determined based upon site-specific technical
information that must include thorough characterization of:
(1) Aquifer thickness, groundwater flow rate, seasonal and temporal fluctuations in
groundwater flow; and
(2) Saturated and unsaturated geologic units and fill materials overlying the
uppermost aquifer, materials comprising the uppermost aquifer, and materials
comprising the confining unit defining the lower boundary of the uppermost
aquifer, including, but not limited to, thickness, stratigraphy, lithology, hydraulic
conductivities, porosities, and effective porosities.
See Section 2.0 (Site
Setting) and Section 3.0
(CCR Unit Groundwater
Monitoring System) of this
report.
Number of Monitoring Wells (c): The groundwater monitoring system must
include the minimum number of monitoring wells necessary to meet the
performance standards specified in paragraph (a) of this section, based on the site-
specific information specified in paragraph (b) of this section. The groundwater
monitoring system must contain:
(1) A minimum of one upgradient and three downgradient monitoring wells; and
(2) Additional monitoring wells are necessary to accurately represent the quality of
background groundwater that has not been affected by leakage from the CCR
unit and the quality of groundwater passing the waste boundary of the CCR
unit.
Seven background wells
and five downgradient
wells exceed the minimum
requirements. See Section
3.0 (CCR Unit Groundwater
Monitoring System) of this
report.
3
CCR Rule Requirements (§257.91) Compliance with CCR Rule
Multiunit Groundwater Systems (d): The owner or operator of multiple CCR units
may install a multiunit groundwater monitoring system instead of separate
groundwater monitoring systems for each CCR unit.
This facility is being
monitored as a multiunit
system using the well
network summarized in
Section 4.0.
Monitoring Well Construction (e): Monitoring wells must be cased in a manner
that maintains the integrity of the monitoring well borehole. This casing must be
screened or perforated and packed with gravel or sand, where necessary, to enable
collection of groundwater samples. The annular space (i.e. the space between the
borehole and well casing) above the sampling depth must be sealed to prevent
contaminating of samples and the groundwater.
(1) The owner or operator of the CCR unit must document and include in the
operating record the design, installation, development, and decommissioning
of any monitoring wells, piezometers, and other measurements, sampling, and
analytical devices. The qualified professional engineer must be given access to
this documentation when completing the groundwater monitoring system
certification required under paragraph (f) of this section.
(2) The monitoring wells, piezometers, and other measurements, sampling, and
analytical devices must be operated and maintained so that they perform to the
design specifications throughout the life of the monitoring program.
See Section 3.0 (CCR Unit
Groundwater Monitoring
System) and the Well
Documentation Memo.
Certification (f): The owner or operator must obtain a certification from a qualified
professional engineer stating that the groundwater monitoring system has been
designed and constructed to meet the requirements of this section. If the
groundwater monitoring system includes the minimum number of monitoring wells
specified in paragraph (c)(1) of this section, the certification must document the
basis supporting this determination.
See the Certifications page
of this report.
4
2.0 Site Setting
The Site is located in the Minnesota River Valley on the south bank of the Minnesota River in Burnsville,
Minnesota (Figure 1). The Plant and associated operational areas, including an electrical substation,
former coal yard, and former Ash Ponds, occupy approximately 115 acres. NSPM’s property also includes
Black Dog Lake, a 500-acre water body developed for cooling Plant discharge water, consisting of Lyndale
Basin, which is located southwest of the Plant, and Cedar Basin, which is located southeast of the Plant
(Figure 1). The undeveloped portion of the property largely consists of lowlands located along the river
and around Black Dog Lake. All of the property except for the 115-acre operating area is under lease to
the United States Fish and Wildlife Service for wildlife refuge management and limited outdoor
recreational use.
2.1 CCR Management
CCR has been managed in basins or ponds at the Site since the facility was constructed in the early 1950s
through closure in 2017, as described in the following subsections.
2.1.1 Former Ash Basins (1950s – 1970s)
Starting in the early 1950s, prior to the construction of the CCR Units, CCR was managed in on-site ash
basins (Figure 2), as approved by the Minnesota Water Pollution Control Commission. The ash basins were
closed in phases during this period (1950s through 1970s), with the waste surface stabilized and the
facility closed as a solid waste facility. These basins were incised, closed in place, have a soil cover system
and do not impound water. The ash basins are not regulated by the CCR Rule because they were closed
prior to publication of the CCR Rule.
2.1.2 CCR Units (1970s – 2017)
In the 1970s, following closure of the former ash basins, new CCR units (Ash Ponds 1, 2, and 3) were
constructed as incised impoundments within the footprint of the former basins. Legacy materials, which
included legacy materials from historic landfilling and beneficial use activities, were left in place beneath
(i.e., below elevation 695 feet mean sea level (MSL)) and around the footprints of the CCR Units. These
legacy materials are not subject to regulation under the CCR rule and are being managed separately
under a State-approved Response Action Plan. Closure of the ponds consisted of the removal of CCRs
from an elevation of 694.5 feet MSL and above.
The Ash Ponds served as the primary component of the process water treatment system at the Plant
between the 1970s and October 2016. During this time, two pipelines—the ash sluice pipeline and the
bilge water/yard drainage pipeline—discharged into the west end of Ash Pond 3 and a return water
pipeline with an intake at the west end of Ash Pond 2 provided for water reuse in the Plant. Each of the
Ash Ponds was approximately two acres in size, separated from each other by berms. Corrugated metal
culverts in the berms allowed the Ash Ponds to be operated in series (3, 2, 1). Process water that was not
reclaimed for reuse in the Plant was discharged to a settling pond, designated Pond 4. A NPDES approved
discharge control structure in Pond 4 allowed periodic batch releases of water to Cedar Basin. The batch
5
discharges occurred periodically after isolating Pond 4 and determining that the water met permit
discharge criteria.
2.2 Geology
The primary geologic units at the Site include non-native sediments, native sediments, and bedrock. These
units are described in the following subsections.
2.2.1 Non-Native Deposits
The predominant surficial deposit at the Site is fill, comprised of imported soil brought in for the
construction of flood protection berms, raising grade inside the flood control berms, or backfilling the Ash
Ponds. The imported fill consists of structural fill (primarily road base aggregate) or granular fill with sandy
to gravelly silt or silty to lean clay textures. Lesser amounts of native soils consisting primarily of silty or
fine sand-textured river deposits and organic topsoil are present along the northern and southern
margins of the Site. These native soils have been disturbed in many areas with regrading or excavations
conducted as part of Site development and/or operations. The thickness of the non-native fill soils varies
from less than five feet along the Site margins to approximately 20 feet at areas inside the flood
protection berm. The estimated hydraulic conductivity of the saturated non-native deposits is provided in
Table 2.
Legacy materials include ashes generated and deposited into the former ash basins under various
operational permits prior to the construction of the Ash Ponds, and coal from the former Coal Yard, which
was located northeast of the Plant (Figure 2). Legacy materials are present below the footprint of the Ash
Ponds, and extend to an approximate depth of 690-ft MSL in some areas (Barr, 2012). These legacy
materials are not subject to regulation under the CCR rule and are being managed separately under a
State-approved Response Action Plan.
The distribution and thickness of the non-native and underlying deposits in the vicinity of the Ash Ponds
are shown on Figures 4 through 7 (see Figure 3 cross section alignments).
2.2.2 Native Deposits
Alluvium—consisting primarily of fine-grained native sediments described as lean clay, fat clay, and
organic clay/silt with lesser amounts of peat, silt, and silty sand—underlies the non-native deposits across
the Site. The clay and peat deposits are interpreted to be backwater deposition from the Minnesota River
and the silt and silty sand are likely the result of slightly higher energy fluvial regimes of the Minnesota
River channel as it meandered through the river valley or flooded. The alluvial sediments are
distinguishable from underlying fine-grained glacial deposits due to their higher organic content (Balaban
and Hobbes 1990) and/or snail shell fragments. The overall thickness of the alluvium varies from 40 to 60
feet at the Site.
Glacial deposits consisting of till and outwash and bedrock consisting of sandy dolostone of the Prairie du
Chien Group are present below the alluvium. The till is described as a gray to grayish brown, lean clay to
gravelly lean clay, and the outwash consists of silty sand to sand with gravel. Collectively, the glacial
6
deposits vary in thickness from 12 to 40 feet, with a top elevation varying from approximately 630 to 670
feet MSL. The depth to bedrock encountered in investigation borings varied from 70 to 92 feet below
ground surface (bgs) and the elevation of the top of bedrock varies from 620 to 630 feet MSL (Barr, 2012).
2.3 Hydrogeology
The hydrogeologic conditions at the Site have been the subject of detailed site characterization
investigations dating back to the early 1980s. These investigations have included advancing more than
100 soil borings, installing 60+ groundwater monitoring points, conducting field and laboratory hydraulic
testing, monitoring hydraulic head, developing a groundwater flow model, and sampling and analyzing
water chemistry. The following subsections describe the key results of the hydrogeologic investigations
that were considered in the design and construction of the groundwater monitoring system.
2.3.1 Groundwater Occurrence
The water table is located in the non-native deposits across the Site throughout the year. The underlying
alluvium, glacial deposits, and bedrock are fully saturated. The position of the water table in the vicinity of
the Ash Ponds is illustrated on Figures 4 through 7.
2.3.2 Groundwater Flow Directions and Rates
Groundwater elevations and inferred flow directions along the water table for two synoptic water level
measuring events, December 11, 2017 and October 22, 2018, are shown on Figures 8 and 9, respectively.
In both instances, groundwater elevation maxima occur in close proximity to unlined temporary
stormwater sedimentation basin A (Pond A) with groundwater flowing away from Pond A radially. A
groundwater divide that is roughly aligned with the axis of the Site and parallel to unlined temporary
stormwater sedimentation basin 3 (Pond 3) is present east of Pond A in the vicinity of the Ash Ponds
during both measurement events. The presence of this groundwater divide is consistent with prior Site
investigation results and is a function of the consistent upward hydraulic gradient that results from the
Site location in a regional groundwater discharge zone. Groundwater flow directions in the vicinity of the
Ash Ponds are to the north towards the Minnesota River, to the south towards Cedar Basin, and to the
east towards Pond 4. Pond 4, which is located outside of the flood control berm, was under natural
conditions during the December 2017 monitoring event and shows flow to the north and south consistent
with the groundwater divide. Pond 4 was being dewatered during a dredging project in October 2018
and, as a result of the dewatering, shows inward groundwater flow from the north and south and an
increased gradient from the Ash Ponds.
Since the Ash Ponds were dredged and backfilled, horizontal hydraulic gradients at the Site have varied
from approximately 0.001 ft/ft to 0.04 ft/ft. Based on the hydraulic conductivity of the non-native
sediments (Table 2; Barr, 2012), an effective porosity of 0.27, and the hydraulic gradients observed on the
water table maps, horizontal average linear groundwater velocity estimates range from 0.005 to 0.2 feet
per day.
7
Table 2 Hydraulic Conductivity Summary
Unit
Hydraulic Conductivity1
Horizontal Vertical
(meters/day) (meters/day)
Surficial / Non-Native 4.37E-01 1.95E-01
(n = 7) (n = 5)
Alluvium 5.78E-02 9.96E-05
(n = 20) (n = 31)
1 Geometric mean value of n number of tests.
Prior investigations have demonstrated the consistent vertically upward gradient between the
bedrock/glacial outwash deposits and the water table at the Site (Barr, 2012). The upward vertical gradient
is one to two orders in magnitude greater than the shallow horizontal hydraulic gradient. The upward
vertical gradient prevents downward migration of shallow groundwater to the underlying regional
bedrock aquifer.
8
3.0 CCR Unit Groundwater Monitoring System
The hydrogeologic data from past investigations served as the initial design basis for the CCR
groundwater monitoring system. The CCR groundwater monitoring system components are shown on
Figure 2 and are described below. Cross sectional views of the groundwater monitoring system wells are
provided on Figures 4 through 7. Because the Ash Ponds are close to each other and it is not feasible to
construct a monitoring system that would distinguish the potential impacts of each pond, the background
and downgradient groundwater monitoring network was designed as a multiunit system.
3.1 Network Installation and Development
Each well included in the monitoring system was installed by a well driller licensed by the State of
Minnesota. Well materials and construction methods were consistent with Minnesota Well Code and local
well ordinance. Each well was cased to maintain integrity of the borehole, the well screen was installed
and surrounded by filter pack sand to enable collection of water samples from the targeted interval, and
the well annular space above the screened interval was sealed to prevent surface water infiltration into the
screened interval. The well construction details are provided in Table 3.
Table 3 Well Construction Details
Well
Unique
Well ID
No.
Type Top of
Riser
Elev.
Bottom
of
Screen
Depth
Well Construction Details
Back
-
gro
un
d
Do
wn
-
gra
die
nt
Wate
r
Level
On
ly
Casing Screen
Dia
.
Screen
Length
Slot
Size
(ft msl) (ft bgs) Material Material (in) (ft) (in)
W502A 772793 X 708.02 15.5 Steel Stainless 2 10 0.01
W502B 782669 X 707.04 30 Steel Stainless 2 10 0.01
W504A 772794 X 706.93 15.5 Steel Stainless 2 10 0.01
W504B 772795 X 706.19 29 Steel Stainless 2 10 0.01
W506A 772790 X 711.27 16.5 Steel Stainless 2 10 0.01
W600A 824832 X 712.25 18 Steel Stainless 2 10 0.01
W601A 824833 X 709.57 15 Steel Stainless 2 10 0.01
W7A 491943 X 706.03 17.7 Steel Stainless 2 10 0.01
W602A 824834 X 707.25 21 Steel Stainless 2 14 0.01
W603A 824835 X 716.58 25 Steel Stainless 2 14 0.01
W604A 824836 X 716.52 25 Steel Stainless 2 10 0.01
W605A 824837 X 716.74 28 Steel Stainless 2 14 0.01
W14A 496033 X 702.58 16.4 Steel Stainless 2 10 0.01
W505A 772792 X 716.26 22 Steel Stainless 2 10 0.01
W506B 772791 X 711.27 29 Steel Stainless 2 10 0.01
W507A 782677 X 704.60 16.5 Steel Stainless 2 10 0.01
W510A 782674 X 705.79 19 Steel Stainless 2 10 0.01
W511A 784715 X 708.49 15 Steel Stainless 2 10 0.01
W514A 784711 X 712.02 15 Steel Stainless 2 10 0.01
W514B 784712 X 712.15 30 Steel Stainless 2 5 0.01
9
Table 3 Notes:
MSL - mean sea level
bgs - below ground surface
Each well in the monitoring network was developed to remove fines from the water column and to
improve hydraulic connection with well screen filter pack and the surrounding aquifer. The wells were
developed by repeated cycles of disrupting the water column with a surge block, purging, and allowing
the water levels to recover. Monitoring well development was conducted until water purged at sampling
rates yielded turbidity values of 20 NTU (Nephelometric Turbidity Units) or less.
Well nomenclature is generally defined by well screen elevations. A-series wells are screened across the
water table (at depths less than 22 feet), with basal elevations ranging from 684.8 to 695.6 feet MSL.
These wells are generally constructed in the non-native sediments. B-series wells are screened below the
A wells (at depths ranging from 29 to 39 feet), with basal elevations ranging from 665.9 to 685.6 fee MSL.
These wells are generally constructed in the upper to middle portions of alluvium. Due to variable
groundwater elevations across the Site, minor overlap of A and B-series screened intervals exist.
3.2 Background Wells
The location of the Site in a regional groundwater discharge area and the presence of legacy materials
beneath the footprint of the Ash Ponds did not allow the determination of the background groundwater
quality with a standard configuration of upgradient well(s). Therefore, the background monitoring
network was established with multiple wells installed in locations and completed at depths that were
unaffected by the former Ash Ponds but representative of background groundwater quality at the Site
(including legacy materials in the former ash basins). Major cation and anion groundwater chemistry was
used to assess the water quality conditions in each background monitoring system well and to
demonstrate that the wells were not affected by leakage from the Ash Ponds.
The resultant monitoring system includes the seven background wells listed in Table 4, which exceeds the
minimum number (one) required by the rule. The background wells include three wells located in the
footprint of former ash basins (W600A, W601A, and W506A), two wells located in native materials along
the north margin of the Site (W502A and W504A), and two wells completed in the top of the alluvium
beneath (but hydraulically upgradient of) the uppermost aquifer (W502B and W504B).
10
Table 4 Monitoring System Summary
Category Monitoring Well Screen
placement Rationale (CCR Rule)
Background
Wells
W502A A-series
To accurately represent the quality of background
groundwater that has not been affected by leakage from a
CCR unit. A determination of background quality may include
sampling of wells that are not hydraulically upgradient of the
CCR management area where: Hydrogeologic conditions do
not allow the owner or operator of the CCR Unit to determine
what wells are hydraulically upgradient, or Sampling at other
wells will provide an indication of background groundwater
quality that is representative or more representative than that
provided by the upgradient wells... (§257.91(a) (1) and (2).
W502B B-series
W504A A-series
W504B B-series
W506A A-series
W600A A-series
W601A A-series
Downgradient
Wells
W7A A-series
To detect a release from the Site and to account for geologic
and hydrogeologic variability, and to establish a sufficient
number of downgradient monitoring wells at appropriate
locations and depths to yield groundwater samples of the
uppermost aquifer accurately representing the quality of
groundwater passing through the waste boundary (§257.91(a)
(1) and (2)).
W602A A-series
W603A A-series
W604A A-series
W605A A-series
3.3 Downgradient Wells
Five monitoring wells installed at (or as close as practical to) the CCR units boundaries were utilized for
the downgradient monitoring system (Table 4), which exceeds the minimum required (three) by the rule.
Each of these wells is completed in the uppermost aquifer and designed to yield samples that are
representative of the quality of groundwater passing through the three downgradient sides of the former
Ash Ponds waste boundaries.
11
4.0 References
Balaban and Hobbes 1990. Balaban N.H. and Hobbs H.C., eds., 1990. Geological Atlas of Dakota County,
Minnesota: Minnesota Geological Survey County Atlas C-6, plate 4, scale 1:100,000.
http://conservancy.umn.edu/handle/58494.
Barr, 2012. Phase II Investigation / Risk Evaluation Report, Coal and Ash Pond Decommissioning Project,
VIC Site VP26870. July 2012.
Figures
SITE LOCATION
13
77
77
P o w e r p l a n t
§̈¦35W
§̈¦35W
13
NSPM Property Boundary
0 0.25 0.5Miles
Z
Source: USGS 1:24,000 Scale Topographic Map
FIGURE 1SITE LOCATION
Black Dog Generating PlantNSPM
Burnsville, Minnesota
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FormerCoalYard
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Minnesota
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Ash Pond 1
Ash Pond 2
Ash Pond 3
Former Pond 4
Lyndale Basin
Pond A Pond
B
ProcessWater Pond
W7A
W507A
W14A
W514A
W511A
W510A
W506A
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ZData Sources:Site Features: AeroMetric 2010Process and Stormwater Ponds, Sampling, Well and Piezometer Locations, VIC Site Boundary,and Groundwater Contours: Barr Engineering Company
FIGURE 2SITE MAP
Black Dog Generating PlantNSPM
Burnsville, Minnesota
Source Drawing: 1101101pln1ft.dwg
Revision Date: 03/26/2019
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Surface Water ElevationMeasurement LocationFormer CCR Unit (Former Ponds 1-3)Legacy Ash Basin BoundaryLined Stormwater PondUnlined Stormwater Pond River Flow Direction
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Ash Pond 2
Ash Pond 3
Former Pond 4
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A
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C
B
C'
B'
D
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W7A
W605A
W604A
W603A
W602A
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W108
W509B W509A
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ZData Sources:Site Features: AeroMetric 2010Process and Stormwater Ponds, Sampling, Well and Piezometer Locations, VIC Site Boundary,and Groundwater Contours: Barr Engineering Company
FIGURE 3CROSS SECTION LOCATIONS
Black Dog Generating PlantNSPM
Burnsville, Minnesota
Source Drawing: 1101101pln1ft.dwg
Revision Date: 03/26/2019
!> Downgradient Well!> Background Well!( Well Location!. Boring_Locations
á
á Cross_Sections_Former_CCR_UnitLegacy Ash Basin BoundaryLined Stormwater PondUnlined Stormwater Pond
3/8”
1/4”
1/4”
1/4”
SAND AND GRAVEL
BEDROCKBEDROCK
PEAT
FILL
SAND AND GRAVEL
PEAT
FILL
ASOUTH
A'NORTH
MW
-1
PZ-
5
PZ-
3SB
-6
Elev
atio
n, F
eet (
MSL
)
6pt Arial
8pt Arial Italic
Soil classifications - ALL CAPS 8pt ArialAll other text - Caps and Lower Case 8pt Arial
11pt Arial Bold
9pt Arial
11pt Arial
8pt Arial
8pt Arial
8pt Arial
2.0 Th
.6 Th
.75 to 1.0 Th
Update horziontal scale every time
Upd
ate
verti
cal s
cale
eve
ry ti
me
filep
ath
does
NO
T au
to u
pdat
e
690
700
710
720
680
670
690
700
710
720
680
670
LEGEND
Geologic Contact
Inferred Geologic Contact
Approximate Water Table (December 2017)
Monitoring Well Screen
Soil Boring/Piezometer
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23 M
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Approximate Horizontal Scale in Feet10X Vertical Exaggeration
Figure 4
GEOLOGIC CROSS SECTION A-A'Black Dog Generating Plant
NSPMBurnsville, Minnesota
""" "
660
680
700
720
W7BW7A
W602A P-6W60
2A
P-6
W7A
SILTY CLAY(ALLUVIUM)
SILTY CLAY(FILL)
SAND
ASOUTHWEST
A’NORTHEAST
PG sand with silt
clayey sand
sandy lean clay
silty clay - fill
fat clay
silty clay
Fill
Lean clay
Fat clay
3/8”
1/4”
1/4”
1/4”
SAND AND GRAVEL
BEDROCKBEDROCK
PEAT
FILL
SAND AND GRAVEL
PEAT
FILL
ASOUTH
A'NORTH
MW
-1
PZ-
5
PZ-
3SB
-6
Elev
atio
n, F
eet (
MSL
)
6pt Arial
8pt Arial Italic
Soil classifications - ALL CAPS 8pt ArialAll other text - Caps and Lower Case 8pt Arial
11pt Arial Bold
9pt Arial
11pt Arial
8pt Arial
8pt Arial
8pt Arial
2.0 Th
.6 Th
.75 to 1.0 Th
Update horziontal scale every time
Upd
ate
verti
cal s
cale
eve
ry ti
me
filep
ath
does
NO
T au
to u
pdat
e
690
700
710
720
680
670
690
700
710
720
680
670
LEGEND
Geologic Contact
Inferred Geologic Contact
Approximate Water Table (December 2017)
Monitoring Well Screen
Soil Boring/Piezometer
\\bar
r.com
\pro
ject
s\M
pls\
23 M
N\1
9\23
1910
85 B
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Site
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085.
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Figu
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supp
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tionB
B.ai
0 100
Approximate Horizontal Scale in Feet10X Vertical Exaggeration
Figure 5
GEOLOGIC CROSS SECTION B-B'Black Dog Generating Plant
NSPMBurnsville, Minnesota
"
""
"""
660
680
700
720
W7BW7A
W603A W509BW509AL14
0 50 10
Feet
silty clay - fill
fat clay
silty clay
silty sand with gravel - fill
legacy materials
silt
lean and fat clay
PG sand
silty sand
sandy silt
lean clay
silty sand (sometimes with gravel) - fill
legacy materials
silty or clayey sand
FAT CLAY
W7A
L14 W60
3A
W50
9A /
W50
9B
Ash Pond 1
CLAY(ALLUVIUM)
SILTY CLAY AND SILTY SAND(FILL)
LEGACY MATERIALS
LEGACY MATERIALS
BNORTHWEST
B’SOUTHEAST
SILTY SAND(ALLUVIUM)
Ash Pond 3
3/8”
1/4”
1/4”
1/4”
SAND AND GRAVEL
BEDROCKBEDROCK
PEAT
FILL
SAND AND GRAVEL
PEAT
FILL
ASOUTH
A'NORTH
MW
-1
PZ-
5
PZ-
3SB
-6
Elev
atio
n, F
eet (
MSL
)
6pt Arial
8pt Arial Italic
Soil classifications - ALL CAPS 8pt ArialAll other text - Caps and Lower Case 8pt Arial
11pt Arial Bold
9pt Arial
11pt Arial
8pt Arial
8pt Arial
8pt Arial
2.0 Th
.6 Th
.75 to 1.0 Th
Update horziontal scale every time
Upd
ate
verti
cal s
cale
eve
ry ti
me
filep
ath
does
NO
T au
to u
pdat
e
690
700
710
720
680
670
690
700
710
720
680
670
LEGEND
Geologic Contact
Inferred Geologic Contact
Approximate Water Table (December 2017)
Monitoring Well Screen
Soil Boring/Piezometer
\\bar
r.com
\pro
ject
s\M
pls\
23 M
N\1
9\23
1910
85 B
lack
Dog
Site
Env
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3191
085.
17 B
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Rem
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Figu
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supp
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CC
.ai
0 100
Approximate Horizontal Scale in Feet10X Vertical Exaggeration
Figure 6
GEOLOGIC CROSS SECTION C-C'Black Dog Generating Plant
NSPMBurnsville, Minnesota
""
"
""
660
680
700
720
W108
W605A
W602AW601A
L3
0 50 100
Feet
W60
2A
L3
W60
1A
W10
8
W60
5A
CLAY (ALLUVIUM)
LEGACY MATERIALS
SILTY SAND(ALLUVIUM)
SAND WITH SILT(FILL)
Ash Pond 1
Ash Pond 2
CNORTH
C’SOUTH
Ash Pond 3
POND 2
POND 1
PG sand with silt
clayey sand
sandy lean clay
PG sand
Legacy material
silt with sand
PG sand
Legacy material
sandy lean clay
silty sand with gravel (fill)
Legacy material
lean clay
rock, sand and gravel
legacy material
lean clay
silty sand
fat clay
3/8”
1/4”
1/4”
1/4”
SAND AND GRAVEL
BEDROCKBEDROCK
PEAT
FILL
SAND AND GRAVEL
PEAT
FILL
ASOUTH
A'NORTH
MW
-1
PZ-
5
PZ-
3SB
-6
Elev
atio
n, F
eet (
MSL
)
6pt Arial
8pt Arial Italic
Soil classifications - ALL CAPS 8pt ArialAll other text - Caps and Lower Case 8pt Arial
11pt Arial Bold
9pt Arial
11pt Arial
8pt Arial
8pt Arial
8pt Arial
2.0 Th
.6 Th
.75 to 1.0 Th
Update horziontal scale every time
Upd
ate
verti
cal s
cale
eve
ry ti
me
filep
ath
does
NO
T au
to u
pdat
e
690
700
710
720
680
670
690
700
710
720
680
670
LEGEND
Geologic Contact
Inferred Geologic Contact
Approximate Water Table (December 2017)
Monitoring Well Screen
Soil Boring/Piezometer
\\bar
r.com
\pro
ject
s\M
pls\
23 M
N\1
9\23
1910
85 B
lack
Dog
Site
Env
ironm
ent\2
3191
085.
17 B
lack
Dog
Rem
edia
tion\
Wor
kFile
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R-G
W M
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Figu
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supp
ort\C
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Sec
tion
DD
.ai
0 100
Approximate Horizontal Scale in Feet10X Vertical Exaggeration
Figure 7
GEOLOGIC CROSS SECTION D-D'Black Dog Generating Plant
NSPMBurnsville, Minnesota
"""""
660
680
700
720
W605A W604A W509B W509AP-3
0
W60
5A
P-3 W60
4A
W50
9A /
W50
9B
LEGACY MATERIALS
LEAN AND FAT CLAY(ALLUVIUM)
SAND(FILL)
DSOUTHWEST
D’NORTHEAST
SAND(ALLUVIUM)
PG sand
Legacy material
sandy lean clay
silty sand (sometimes with gravel) - fill
legacy materials
silty or clayey sand
PG sand
legacy materials
PG sand
lean clay with sand
legacy materials
lean clayFAT CLAY
%9
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Cedar Basin
Plant/Substation
Minnesota
River
Pond 4
Lyndale Basin
Process
Water PondPo
nd B
696
Ash Pond 1
Ash Pond 2
Ash Pond 3
W7A698.78
W605A696.9
W14A697.65
W604A699.02
W603A699.64
W602A698.58
W601A700.62
W600A703.22
W514A700.89
W511A699.49
W510A699.55
W507A694.66
W506A700.35
W504A696.23
W502A698.44
ScreenHouse689.2
Pond A702.8
Pond 3698.9
Pond 4699.9698
698
700
700
698
702
702
SW512694.9
698
W505A
Barr F
ooter
: ArcG
IS 10
.6.1,
2019
-04-12
13:29
File:
I:\Cli
ent\X
cel_E
nergy
\Blac
k_Do
g_Pla
nt\Wo
rk_Or
ders\
Envir
onme
ntal_M
onito
ring\M
aps\R
eport
s\201
9 Grou
ndwa
ter N
etwork
Cert
ificati
on\Fi
gure
8 Wate
r Tab
le Ma
p Dec
embe
r 11,
2017
.mxd
Use
r: bal
0 400 800
Feet1 inch = 400 feet
ZData Sources:Site Features: AeroMetric 2010Process and Stormwater Ponds, Well and Piezometer Locations, VIC Site Boundary,and Groundwater Contours: Barr Engineering Company
FIGURE 8WATER TABLE MAPDecember 11, 2017
Black Dog Generating PlantXcel Energy
Burnsville, Minnesota
Source Drawing: 1101101pln1ft.dwg
Revision Date: 03/26/2019
!> Monitoring Well
%9Surface Water ElevationMeasurement LocationWater Table Contour (2 ft) Apparent Groundwater Flow DirectionFormer CCR Unit (Former Ponds 1-3)Lined Stormwater PondUnlined Stormwater Pond River Flow Direction
700.04 Elevation in Feet MSL
%9
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ScreenHouse699.3
SW512699.1
Pond A704.9
Cedar Basin
Plant/Substation
Minnesota
River
Lyndale Basin
Pond A
Pond 4
ProcessWater Pond
Pond
B
Note: Pond 4 was drained on June 21, 2018and dewatering, dredging and filling occurredthrough 2018.
694696698
698
694
Ash Pond 1
Ash Pond 2
Ash Pond 3
702
704
70470
2
Pond 3702.1
700
700
700
W511A693.25W14A
696.78
W7A698.9
W602A700.12
W510A694.69W603A
701.6
W604A702.12
W605A702.07
W601A702.33
W506A702.62
W600A704.15W502A
701.29
W504A700.17
W514A703.12
W507A698.78
W505A
Barr F
ooter
: ArcG
IS 10
.6.1,
2019
-04-12
13:23
File:
I:\Cli
ent\X
cel_E
nergy
\Blac
k_Do
g_Pla
nt\Wo
rk_Or
ders\
Envir
onme
ntal_M
onito
ring\M
aps\R
eport
s\201
9 Grou
ndwa
ter N
etwork
Cert
ificati
on\Fi
gure
9 Wate
r Tab
le Ma
p Octo
ber 2
2 201
8.mxd
Use
r: bal
0 400 800
Feet1 inch = 400 feet
ZData Sources:Site Features: AeroMetric 2010Process and Stormwater Ponds, Well and Piezometer Locations, VIC Site Boundary,and Groundwater Contours: Barr Engineering Company
FIGURE 9WATER TABLE MAP
October 22, 2018Black Dog Generating Plant
Xcel EnergyBurnsville, Minnesota
Source Drawing: 1101101pln1ft.dwg
Revision Date: 03/26/2019
!> Monitoring Well
%9Surface Water ElevationMeasurement LocationWater Table Contour (2 ft) Apparent Groundwater Flow DirectionFormer CCR Unit (Former Ponds 1-3)Lined Stormwater PondUnlined Stormwater Pond River Flow Direction
700.04 Elevation in Feet MSL