981578
SIXTH FIVE-YEAR REVIEW REPORT FOR
WASTE DISPOSAL ENGINEERING SUPERFUND SITE
ANOKA COUNTY, MINNESOTA
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Prepared by
U.S. Environmental Protection Agency
Region 5
CHICAGO, ILLINOIS
4/20/2023
X Douglas Ballotti
Douglas Ballotti, Director
Superfund & Emergency Management Division
Signed by: DOUGLAS BALLOTTI
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Table of Contents
LIST 01 ABBREVIATIONS & ACRONYMS 3
I. INTRODUCTION 4
FIVE-YEAR REVIEW SUMMARY FORM 6
II. RESPONSE ACTION SUMMARY 6
Basis for Taking Action 6
Response Actions 7
Status of Implementation 9
Hazardous Waste Pit Removal 11
Off-Site Plume Delineation and Source Evaluation 11
Institutional Controls 14
Systems Operations/Operation & Maintenance 16
III. PROGRESS SINCE THE LAST REVIEW 17
IV. FIVE-YEAR REVIEW PROCESS 19
Community Notification, Involvement & Site Interviews 19
Data Review 19
Monitoring Wells 19
Domestic Water Wells 20
Landfill Gas 21
Site Inspection 22
V. TECHNICAL ASSESSMENT 22
QUESTION A: Is the remedy functioning as intended by the decision documents? 22
QUESTION B: Are the exposure assumptions, toxicity data, cleanup levels, and RAOs used at
the time of the remedy selection still valid? 23
QUESTION C: Has any other information come to light that could call into question the
protectiveness of the remedy? 24
VI. ISSUES/RECOMMENDATIONS 24
OTHER FINDINGS 25
VII. PROTECTIVENESS STATEMENT 26
VIII. NEXT REVIEW 26
APPENDIX A - REFERENCE LIST A-l
APPENDIX B - INSTITUTIONAL CONTROL MAP B-l
APPENDIX C - FIVE YEAR REVIEW INPSECTION CHECKLIST AND PHOTOLOG.... C-l
APPENDIX D - SUMMARY OF GROUNDWATER MONITORING D-l
FIGURES
Figure 1: WDE Superfund Site Location 5
Figure 2: Site Features 5
Figure 3: 1,4-Dioxane Plume Exceeding 1 |ig/L 12
Figure 4: Groundwater Monitoring Locations, Qualitative Contamination Levels, and
Groundwater Area of Concern 20
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TABLES
Table 1: Groundwater Action Levels Based on Current Federal and State Drinking Water
Standards and Risk-Based Levels 8
Table 2: Summary of Implemented ICs 14
Table 3: Protectiveness Determinations/Statements from the 2018 FYR 17
Table 4: Status of Recommendations from the 2018 FYR 18
Table 5: PFAS Action Level Exceedances in Domestic Water Wells 21
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LIST OF ABBREVIATIONS & ACRONYMS
ARAR
Applicable or Relevant and Appropriate Requirement
C3
Cryogenic, Condensate, and Compression
CERCLA
Comprehensive Environmental Response, Compensation, and Liability Act
CFR
Code of Federal Regulations
CLP
Closed Landfill Program
COC
Contaminant of Concern
EPA
United States Environmental Protection Agency
EW
Extraction Well
FYR
Five-Year Review
GWAOC
Groundwater Area of Concern
HI
Hazard Index
HBV
Health-Based Value
HRL
Health Risk Limit
IC
Institutional Control
LTS
Long-Term Stewardship
MDH
Minnesota Department of Health
MPCA
Minnesota Pollution Control Agency
NAPL
Non-Aqueous Phase Liquid
NCP
National Oil and Hazardous Substances Pollution Contingency Plan
NPL
National Priorities List
O&M
Operation and Maintenance
OU
Operable Unit
PCB
Polychlorinated biphenyl
PFCs
Perfluorinated Chemicals
PFAS
Per- and Polyfluoroalkyl Substances
PRP
Potentially Responsible Party
RAA
Risk Assessment Advice
RAL
Recommended Allowable Limit
RAO
Remedial Action Objectives
RI/FS
Remedial Investigation/Feasibility Study
ROD
Record of Decision
RSL
Regional Screening Level
Site
Waste Disposal Engineering Superfund Site
UU/UE
Unlimited Use and Unrestricted Exposure
VOC
Volatile Organic Compound
WDE
Waste Disposal Engineering
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I. INTRODUCTION
The purpose of a Five-Year Review (FYR) is to evaluate the implementation and performance of
a remedy in order to determine if the remedy is and will continue to be protective of human
health and the environment. The methods, findings, and conclusions of reviews are documented
in FYR reports such as this one. In addition, FYR reports identify issues found during the
review, if any, and document recommendations to address them.
The United States Environmental Protection Agency (EPA) is preparing this FYR pursuant to the
Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) Section
121, consistent with the National Oil and Hazardous Substances Pollution Contingency Plan
(NCP)(40 Code of Federal Regulations (CFR) Section 300.430(f)(4)(ii)) and considering EPA
policy.
This is the sixth FYR for the Waste Disposal Engineering (WDE) Superfund Site (Site). The
triggering action for this statutory review is the completion date of the previous FYR. The FYR
has been prepared due to the fact that hazardous substances, pollutants, or contaminants remain
at the Site above levels that allow for unlimited use and unrestricted exposure (UU/UE).
The Record of Decision (ROD) (EPA, 1987) did not separate the Site into operable units (OUs),
but the Site is tracked by EPA as two OUs, both of which are addressed in this FYR. OU1
addresses the groundwater remedy and OU2 addresses the landfill remedy. The Minnesota
Pollution Control Agency (MPCA) is the lead agency managing cleanup of the Site under
Minnesota's Closed Landfill Program (CLP). EPA conducts FYRs for the Site in accordance
with a multi-site deferral agreement between EPA and MPCA (EPA & MPCA, 2018).
The WDE Superfund Site FYR was led by Leslie Patterson, EPA Remedial Project Manager.
Participants included John Hunter, Land Manager at MPCA; Dan McNamara, Field
Representative at MPCA; and Ruth Muhtson, Community Involvement Coordinator, EPA. The
review began on June 6, 2022.
Site Background
The Site occupies approximately 114 acres at 14437 Crosstown Boulevard in the City of
Andover, Anoka County, Minnesota (Figure 1). Land use near the Site consists of a mix of
residential, recreational, and commercial uses, with several subdivisions and a stream bordering
directly on the Site (Figure 2). The surrounding land use is expected to remain the same in the
future. Private wells are in use north of the stream and in the neighborhoods to the west and the
south of the landfill.
The Site operated as an open dump from 1963 to 1971, and as a licensed landfill from 1971 until
1983. Approximately 2.5 million cubic yards of solid municipal and industrial wastes and three
million gallons of liquid industrial wastes were disposed in the approximately 76-acre landfill
during this time. WDE constructed a 240-ft long by 90-ft wide by 20-ft deep pit in the landfill for
disposal of hazardous wastes and reportedly disposed of 6,600 containers of hazardous waste
materials in the pit. Waste disposal at the landfill caused groundwater contamination that moved
off-Site. EPA listed the Site on the National Priorities List (NPL) on September 8, 1983.
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Figure 1: WDE Superfund Site Location
Andover
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Figure 2: Site Features
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Landfill
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5
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FIVE-YEAR REVIEW SUMMARY FORM
SITE IDENTIFICATION
Site Name: Waste Disposal Engineering
EPA ID: MND980609119
Region: 5
State: MN
City/County: Andover/Anoka County
NPL Status: Deleted
Multiple OUs?
Yes
Lead agency: EPA
Has the Site achieved construction completion?
Yes
REVIEW STATUS
Author name (Federal or State Project Manager): Leslie Patterson
Author affiliation: EPA Region 5
Review period: 6/6/2022 - 12/23/2022
Date of site inspection: 9/26/2022
Type of review: Statutory
Review number: 6
Triggering action date: 4/24/2018
Due date (five years after triggering action date): 4/24/2023
II. RESPONSE ACTION SUMMARY
Basis for Taking Action
The basis for taking action at the Site was the presence of multiple contaminants in shallow
groundwater and landfill wastes. The ROD did not specify a list of contaminants of concern
(COCs), but hazardous substances that were found in soil and groundwater included: 1,1-
dichloroethane, 1,2-dichloroethene, 1,1,2-trichlorotrifluoroethane, 1,1,1-trichloroethane, methyl
ethyl ketone, methyl isobutyl ketone, dichloroethane, toluene, xylene, methylene chloride,
acetone, tetrahydrofuran, 1,1-dichloropropene, benzene, dibromochloromethane, 1,1,2-
trichloroethane, 1,1,2,2-tetrachloroethane, trichloroethene, 1,3-dichloropropene, ethylbenzene,
cumene, and ethyl ether. The Site posed potential threats to human health and the environment
through direct contact with wastes, soils, and leachate seeps; ingestion of ground or surface water
impacted by the Site; and possible off-Site migration of landfill gas containing hazardous
constituents or posing a potential explosive hazard.
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Response Actions
MPCA ordered the hazardous waste pit to close and stop accepting waste effective
February 1, 1974. In January 1983, the Minnesota Department of Health (MDH) issued a
drinking water well advisory in portions of the City of Andover due in part to the hazardous
substances disposed of at the Site.
On December 31, 1987, EPA signed a Site-wide ROD that included the following Remedial
Action Objectives (RAOs).
• Control potential dust and/or volatilized chemical emissions.
• Control contact with lime sludge.
• Control contact with exposed waste/1 eachate.
• Minimize contaminant releases to the upper sand aquifer.
• Eliminate or minimize contaminant releases to Coon Creek.
• Reduce the probability of incompatible waste reactions.
• Control the effects of possible reactions that may occur.
• Control future exposure to the contaminated upper sand aquifer.
• Protect the lower sand aquifer by controlling the vertical gradient and the impact of
heavier-than-water non-aqueous phase liquid (NAPL) accumulation.
• Control of soil gas migration.
The remedy selected to achieve these remedial objectives include the following major
components.
• Soil and lime sludge cap meeting Resource Conservation and Recovery Act technical
performance standards.
• Gas vents with granular activated carbon filters installed below the lime sludge layer to
the surface.
• Groundwater extraction wells in the upper sand aquifer between Coon Creek and the
landfill.
• Clay slurry wall around the hazardous waste pit with pumping inside the wall.
• Institutional controls (ICs) to prohibit upper sand aquifer wells at the Site and just north
of Coon Creek and to prohibit lower sand aquifer wells near the landfill.
• Carbon adsorption treatment of extracted groundwater (air stripping or a combination is
possible based on design).
• Discharge of treated extracted groundwater to Coon Creek.
• Monitoring, including geophysical work around the Site, to locate heavier-than-water
NAPL, to assure the effectiveness of the remedy.
The ROD indicates that standards set under the Safe Drinking Water Act are applicable or
relevant and appropriate requirements (ARARs) for groundwater outside the landfill boundary,
but does not specify COCs or include numeric groundwater cleanup standards. The ROD also
identifies Minnesota Recommended Allowable Limits (RALs) as levels that may be considered
Since the ROD was issued, MDH discontinued use of RALs and has established promulgated
Health Risk Limits (HRLs) and non-promulgated Health-Based Values (HBVs) and Risk
Assessment Advice (RAA) for evaluating risks to human health from drinking water supplies.
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The lowest of the MCL, HRL, HBV, and RAA drinking water levels ("Action Levels") for
contaminants that were detected in exceedance of their respective levels during this FYR period
are listed in Table 1. Because specific numeric cleanup standards were not established in the
ROD, and in some cases, ARAR-based standards have been replaced, the action levels in Table 1
are being used as groundwater cleanup standards for the purpose of reviewing the data and
evaluating the remedy.
Table 1: Groundwater Action Levels Based on Current Federal and State Drinking
Water Standards and Risk-Based Levels
Chemical
CAS Number
Action Level, jug/L
Source
1,1,1 -Trichloroethane
71-55-6
200
MCL
1,1,2,2-Tetrachloroethane
79-34-5
2
HRL
1,1,2-Trichloroethane
79-00-5
3
HRL
1,1 -Dichloroethane
75-34-3
80
RAA
1,1 -Dichloroethene
75-35-4
7
MCL
1,2,4-Trimethylbenzene
95-63-6
30
HBV
1,2-Dichlorobenzene
95-50-1
600
MCL
1,2-Dichloroethane
06-02-0107
1
HRL
1,2-Dichloropropane
78-87-5
3
HBV
1,3,5-Trimethylbenzene
108-67-8
30
HBV
1,4-Dioxane
123-91-1
1
HRL
2-Methylnaphthalene
91-57-6
8
RAA
Acetone
67-64-1
3000
HBV
Arsenic
7440-38-2
10
MCL
Barium
7440-39-3
2000
MCL
Benzene
71-43-2
2
HRL
Beryllium
7440-41-7
0.08
HRL
Bis(2-chloroethyl) ether
111-44-4
0.3
HRL
Cadmium
7440-43-9
0.5
HRL
Carbon tetrachloride
56-23-5
1
HRL
Chlorobenzene
108-90-7
100
MCL
Chloroform
67-66-3
20
HRL
Chromium
7440-47-3
100
MCL
cis-l,2-Dichloroethene
156-59-2
6
HRL
Di(2-ethylhexyl) phthalate
117-81-7
6
MCL
Di chl or ofluorom ethane
75-43-4
20
RAA
Ethyl ether
60-29-7
200
RAA
Ethylbenzene
100-41-4
40
HBV
Isophorone
78-59-1
100
HRL
Lead
7439-92-1
15
MCL
Manganese
7439-96-5
100
HRL
Methyl bromide
74-83-9
10
HRL
Methyl ethyl ketone
78-93-3
4000
HRL
Methyl isobutyl ketone
10-01-0108
300
HRL
Methyl tert-butyl ether
04-04-1634
60
RAA
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Chemical
CAS Number
Action Level, jug/L
Source
Methylene chloride
75-09-2
5
MCL
Naphthalene
91-20-3
70
HRL
Nickel
7440-02-0
100
HRL
o-Cresol
95-48-7
30
HRL
o-Di chl orob enzene
95-50-1
600
MCL
p-Cresol
106-44-5
3
HRL
p-Di chl orob enzene
106-46-7
10
HRL
Perfluorobutanesulfonate
45187-15-3
0.1
HBV
Perfluorohexanesulfonate
108427-53-8
0.05
HBV
Perfluorohexanoic acid
307-24-4
0.2
HBV
Perfluorooctane sulfonate
45298-90-6
0.02
HBV
Perfluorooctanoic acid
335-67-1
0.04
HRL
T etrachl oroethene
127-18-4
4
HBV
Tetrahydrofuran
109-99-9
600
HRL
Toluene
108-88-3
70
HBV
trans-1,2-Dichloroethene
156-60-5
9
HBV
Tri chl oroethene
79-01-6
0.4
HRL
Vinyl chloride
75-01-4
0.2
HRL
With respect to surface water, the ROD did not specifically state that federal water quality
criteria established under the Clean Water Act were ARARs for groundwater discharging into
Coon Creek, but stated that the remedy selected was expected to meet the 10"6 risk water quality
criteria for contaminants in Coon Creek.
Status of Implementation
EPA identified two OUs for implementing the remedy selected in the Site-wide 1987 ROD. OU1
refers to the groundwater extraction and treatment system, and OU2 refers to the multi-layer
landfill cover.
The group of PRPs known as the "WDE Group" constructed the OU1 remedy from October
1992 to September 1993 and completed construction of the OU2 remedy in August 1994.
Remedial activities included the construction of a multilayer soil cap, a slurry wall/NAPL control
system around the hazardous waste pit, a landfill gas venting system, two perimeter gas barrier
membranes, stormwater management, and relocation of wetlands. The soil-bentonite slurry wall
was constructed to provide a low-permeable perimeter barrier around the hazardous waste pit
and to contain groundwater and impacted soils. In addition, a groundwater extraction well was
installed inside the north end of the slurry wall to extract groundwater from inside the slurry
wall.
Also in 1994, the Site was deferred to MPCA and entered the CLP. Because the CLP uses mostly
tax dollars to clean up sites instead of pursuing PRPs to pay for cleanup, subsequent activities
were performed by MPCA.
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A groundwater containment and treatment system, consisting of ten groundwater extraction wells
and an on-Site air stripper for treatment, began operating in 1995. In 2002, MPCA discontinued
use of the air stripper for groundwater treatment and installed an on-Site lined aeration basin and
an on-Site infiltration pond. However, no remedy modification was issued. The water from the
aeration basin is discharged to the Metropolitan Council's Metropolitan Wastewater Treatment
Plant.1 In 2012, MPCA added granular activated carbon treatment for poly chlorinated biphenyls
(PCBs) to groundwater extracted from the hazardous waste pit. Quarterly reports indicate that the
current system includes eight active extraction wells (EW-6, -7, -8, -9, -10, -11, -12, -13)
(Willow Brook Engineering, 2022b).
On September 27, 1995, EPA signed a Preliminary Closeout Report to document that remedy
construction was completed at the Site (EPA, 1995). EPA deleted the Site from the NPL on
June 5, 1996, as specified by the deferral agreement between EPA and MPCA (EPA & MPCA,
2018). The response actions for the Site required by the ROD are complete, except for ongoing
groundwater extraction and treatment and monitoring and maintenance of the landfill and long-
term stewardship (LTS) of the ICs. Since contaminants remain at the Site above levels that allow
UU/UE, EPA continues to conduct FYRs to ensure that the Site remedy remains protective of
human health and the environment.
In 1998 the passive gas venting system was replaced by a system of 53 active gas collection
wells and an enclosed flare. Quarterly reports indicate that the current system includes 54 gas
wells (Willow Brook Engineering, 2022b). Gas migration is monitored though a system of
approximately 19 gas probes installed outside the perimeter of the waste. In 2007, MPCA
installed a Landfill Gas-To-Energy system to convert landfill gas to usable energy rather than
combusting it in the enclosed flare. This system operated for three years but was shut down in
2010 due to contaminant characteristics in the landfill gas that made the Gas-to-Energy system
difficult to maintain. At that time, use of the enclosed flare was re-started.
In 2009, MPCA installed a pilot system known as a Cryogenic, Condensate, and Compression
system (known as the "C3 system") to remove vapor-phase contamination from the hazardous
waste pit. The pilot system operated until 2010, and it was replaced by a full-scale system that
began operation in 2013.
In 2016, MPCA installed two additional monitoring well nests north of Coon Creek, consisting
of two wells each (MW-26A and -26B, and MW-39A and -39B), to better understand
groundwater flow direction and chemical constituents in the upper sand aquifer north of Coon
Creek (GHD, 2016). Groundwater in the more contaminated shallow portion of the upper sand
aquifer flows to the north-northeast across the landfill, and is largely captured at the northern
boundary of the landfill. Groundwater that is not captured converges with groundwater flowing
south-southeast on the opposite side (north) of Coon Creek, and presumably discharges into
Coon Creek. Groundwater in the lower portion of the upper sand aquifer flows to the north at the
landfill, converges with groundwater flowing west, and flows away from the landfill to the
northwest (GHD, 2016). Therefore, Coon Creek appears to function as the downgradient
industrial Permit Discharge Permit No. 2169 was due to expire on November 30, 2017; a new or reissued permit
was not available for this FYR.
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(northern) edge of the plume. The 2016 groundwater assessment report found that VOC
analytical results and groundwater flow patterns did not indicate a potential for impacted
groundwater from the WDE Closed Landfill to have any effect on private wells along Andover
Blvd. (north of the Creek) (GHD, 2016).
Hazardous Waste Pit Removal
In 2016, MPCA secured State funds to remove wastes from within the hazardous waste pit for
off-Site disposal. In 2019, contractors to MPCA performed the following activities (GHD, 2022).
• Abandonment and removal of 14 groundwater monitoring wells (NW-1 A, NW-1B, NW-
1C; NW-2A, NW-2B, NW-2C, NW-3A, NW-3B, NW-3C, NW-4A, NW-4B, NW-4C,
W-6, and W-22A), 3 groundwater extraction wells (EW-9, EW-14, and EW-15),
• Abandonment and removal of one landfill gas extraction well (GW-43), eight VEVOR
system extraction and monitoring wells (TW-1, TW-2, TW-3, TW-4, TW-5, TW-6, TW-
7, and TW-8), and 10 VEVOR system vapor intrusion points (VIP-1, VIP-2, VIP-3, VIP-
4, VIP-5, VIP-6, VIP-7, VIP-8, VIP-9, and VIP-10).
• Excavation and off-Site disposal of waste pit drums, the underlying clay liner, and
vadose-zone soils to within approximately one foot of the groundwater table. A total of
14,383 cubic yards of soil and drum material, including 397 drums, were removed.
• Placement, compaction, and grading of backfill in the excavated area, placement of a clay
cover, restoration of the multi-layered geosynthetic liner system, and revegetation.
• Installation of twelve replacement monitoring wells, including shallow "A" and "B"
wells in the upper portion of the upper sand unit on the inside and outside of the slurry
wall (NW-1AR, -1BR, -2AR, -2BR, -3AR, -3BR, -4AR, and -4BR), and deep "C" wells
in the lower portion of the upper sand unit outside of the slurry wall. (NW-1CR, -2CR, -
3CR, and -4CR).
• Installation of one new extraction well (EW-16) at the northern end of the former pit, and
associated forcemain.
• Removal of landfill gas extraction piping, groundwater extraction forcemain piping,
related electrical appurtenances, and an inspection manhole.
• Access road construction and site restoration.
Under its deferral agreement with MPCA, EPA retains authority over the Site to the extent that
proposed response actions are not "at least as protective of human health and environment as
response actions required under CERCLA." In a letter dated October 18, 2017, MPCA agreed to
document its remedy modification decision consistent with existing Minnesota law and
procedures as per the deferral agreement. MPCA provided a partial Removal Action Report
documenting that the substantial portion of the work was performed from October to December
2019 (GHD, 2022), but has not provided the entire report or clarified how the remedy
modification decision was made in accordance with Minnesota law and procedures.
Off-Site Plume Delineation and Source Evaluation
In February 2022, a contractor to MPCA finalized a Preliminary Source Evaluation report that
integrated existing data and information to evaluate the source of 1,4-dioxane groundwater
impacts that had been found in domestic water wells in the "Red Oaks" neighborhood (see the
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aqua-shaded area in Figure 3) located immediately upgradient and southwest of the Site (Braun
Intertec Corporation, 2022a). The report could not rule-out the Site as the source of the 1,4-
dioxane because of its proximity, the presence of chlorinated volatile organic compounds as well
as 1,4-dioxane and other contaminants in groundwater at the landfill, and the incomplete
characterization of the horizontal and vertical extent of these impacts. The report found that a
different Superfund Site, the South Andover Site, appeared to be a potential contributing source
of the 1,4-dioxane groundwater impacts in the Red Oaks neighborhood.
Figure 3: 1,4-Dioxanc Plume Exceeding 1 jiig/'L (Braun Intertec Corporation, 2022d)
A related survey of groundwater use and evaluation of water wells and surface water bodi es that
may be susceptible to impacts from groundwater contamination was prepared in March 2022
(Braun Intertec Corporation, 2022b). The survey inventoried groundwater use (i.e., water wells)
and surface water bodies within a one-mile radius of the edge of the Site waste footprint and
prepared groundwater flow maps using data from the landfill monitoring well network. The
survey found 322 domestic wells, six municipal water supply wells, eight unknown/other wells,
and surface water bodies in the study area.
Concurrently with the source evaluation, the contractor to MPCA prepared a Site Conceptual
Model and 3-D Visualization Modeling report in April 2022 (Braun Intertec Corporation, 2022c).
The report presents a conceptual Site model based on review of existing technical data and 3-D
modeling of stratigraphy and 1,4-dioxane, as well as recommendations for additional
groundwater characterization to fully delineate the extent of COCs. The report found that 1,4-
dioxane was the dominant COC; that the 1,4-dioxane plume in the Red Oaks neighborhood
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appeared to be distinct from that of the Site; but that the extent of neither plume had been fully
delineated laterally or vertically. The report recommended the following.
• Installation of bedrock monitoring wells to determine groundwater gradient direction and
the presence of COCs within the bedrock.
• Installation of additional monitoring wells west and northeast of the infiltration pond to
further define 1,4-dioxane plume west and north of the landfill.
• Additional monitoring wells in the deeper sand aquifer beneath the landfill footprint to
determine COC presence and lateral extent in that unit.
• Additional monitoring wells to evaluate 1,4-dioxane in the area between the two
apparent plumes (in the Red Oaks neighborhood and at the Site).
Following up on the February 2022 source investigation, the contractor to MPCA reported the
results of a summer 2022 groundwater investigation between the Red Oaks neighborhood and
the South Andover Superfund site (Braun Intertec Corporation, 2022d). The report identified
volatile organic compounds (VOCs), 1,4-dioxane, arsenic, manganese, and per- and
polyfluoroalkyl substances (PFAS)/perfluorinated chemicals in groundwater, but determined that
1,4-dioxane was the dominant COC. The report found that a distinct 1,4-dioxane plume appeared
to be associated with at least the north side of the South Andover Superfund Site and the Red
Oaks Neighborhood to the north, but that the magnitude and extent of 1,4-dioxane impacts had
not been laterally or vertically defined in the vicinity of Bunker Lake Boulevard NW, the Red
Oaks neighborhood, or within the WDE landfill monitoring network. The report recommended
further groundwater investigation, including evaluation of groundwater quality in the underlying
bedrock formation, in the vicinity of Bunker Lake Boulevard and at new Site monitoring wells.
Figure 3 shows the area where 1,4-dioxane exceeds the HRL of 1 |ig/L, but the plume boundary
is dashed, indicating significant uncertainty.
EPA did not receive documentation of monitoring wells installed in 2022 in time for the FYR
review, so their locations and the formations monitored are not available, but information on a
public MPCA website provides some additional information.2 Seven new permanent monitoring
wells were installed between the Site and the Red Oaks neighborhood to determine if
contamination is coming into Red Oaks from the Site. Preliminary analysis of groundwater data
from the permanent monitoring wells shows a northerly groundwater flow direction for the
shallow groundwater near the WDE landfill, away from the Red Oaks neighborhood, suggesting
that the 1,4-dioxane contamination found in the Red Oaks residential wells is likely not coming
from the WDE landfill. According to the webpage, residents with wells at or above the health-
based values will continue to receive bottled water, free of charge, until MPCA secures state
funding to implement the long-term drinking water solution of a municipal water supply
connection to the entire Red Oaks neighborhood.
2 https://www.pca.state.mn.us/local-sites-and-proiects/andover-red-oaks-neighborhood-groundwater-contamination
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Institutional Controls
Table 2 describes the ICs that have been implemented or are planned, and Figure B-l in
Appendix B shows the area in which the ICs apply.
Table 2: Summary of Implemented ICs
Modiii.
engineered
controls. ;iihI
iiiviis lliiil do
iiol mipport
I 1 /I 1 l>;iscd
on current
coiitlilions
ICs
Needed
ICs C;illcd
lor in llie
Decision
Documents
Impiicled
Piircells)
IC
OI).jec(i\e
l ille of IC Inslriimcnl
Implemented :ind l);ilc
(or phinncd)
Landfill waste,
soil,
groundwater,
and landfill
gas.
Hazardous
waste landfill
cover.
Yes
Yes
(groundwater
and landfill
cover)
No (landfill
gas)
Landfill and
parcels
generally
depicted by
the outline on
Figure B-l in
Appendix B
Prevent exposure to
landfill contents,
landfill gas, and
contaminated
groundwater; and
protect the landfill
cover.
Landfill Cleanup
Agreement between
Anoka County and the
WDE Group and the
Commissioner of the
MPCA Pursuant to Minn.
Stat. §§115B.39-46 and
282.019, October 27,
1995 (No author, 1995)
Prohibit enclosed
structures on or near the
landfill.
Groundwater
and landfill
gas.
Yes
Yes
(groundwater)
No (landfill
gas)
Land
Management
Area around
the landfill
(see Figure
B-l in
Appendix B)
Require soil gas and
explosive gas
monitoring at structures
between 200 and 500
feet of the waste.
Prohibit groundwater
extraction from the
Upper Sand Aquifer
within 500 feet of limit
of refuse, and from the
Lower Sand Aquifer
within area indicated in
Exhibit A to the
ordinance.
Andover City Ordinance
19, adopted January 16,
1996 (City of Andover,
1996)
Groundwater
Yes
Yes
Generally
depicted by
the green
hatched area
on Figure B-
1 in
Appendix B
Prohibit extraction of
groundwater from the
Upper Sand Aquifer or
Lower Sand Aquifer in
specific areas, without
the prior written
approval of the
Commissioner of
MPCA.
Declaration of Restrictive
Covenants, November
27, 2001 (No author,
2001)
14
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Mcdiii.
engineered
controls. ;iihI
ICs ( idled
Title ol' IC luslrnineiil
Implemented :ind Diitc
(or pliinncd)
iiiviis lliiil do
mil support
I 1 /I 1 hiiscd
ICs
Needed
for in die
Decision
Documents
Impiicled
Piircells)
IC
Object i\c
on current
conditions
Groundwater
Yes
Yes
Area around
the landfill
(see Figure
B-l in
Appendix B)
Prohibit construction of
new water-supply well
within 300 feet of a
mixed municipal solid
waste landfill, or 600
feet for a sensitive
water-supply well.
Minnesota
Administrative Rule
4725.44503
Groundwater
Yes
No
Red Oaks
neighborhood
Prohibit extraction of
groundwater and
construction of new
water-supply wells
without the prior
written approval of the
Commissioner of
MPCA.
Planned/recommended
Landfill and
parcels
generally
depicted by
the outline on
Figure B-l in
Appendix B
Prohibit use that
Landfill cover
and gas
system.
Yes
Yes (landfill
cover)
disturbs the integrity of
the landfill cover,
liners, and any other
components of any
containment system, or
the functioning of any
monitoring system.
Minn. Stat. §115B.412,
Subd.9.4
Status of Access Restrictions and ICs: There have been no changes to the ICs during the period
of this FYR. A new IC restricting groundwater use in the Red Oaks neighborhood is
recommended and has not been implemented; all other ICs in Table 2 have been implemented.
The fence around the Site perimeter, as well as around specific features such as the retention
pond and pump out building area, are in good condition and securely locked.
Current Compliance: Based on the FYR Site inspection conducted on September 26, 2022,
routine Site visits by MPCA and its contractor, and MPCA's knowledge of the Site, there have
been no instances of non-compliance with ICs during the period of this FYR. Trespassers were
reported to have cut the fence in order to use the landfill cover as a sledding hill in February
2022. No damage to the remedy was found and the fencing was repaired (Willow Brook
Engineering, 2022b).
3See: https://www.revisor.mn.gov/rules/4725.4450/ A current zoning map for the City of Andover can be found at
the following Internet web site: https://www.andovermn.gov/documentcenter/view/228
4See: https://www.revisor.mn.gov/statutes/cite/115B.412
15
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IC Follow up Actions Needed: With the discovery of groundwater contamination in private
domestic wells and the planned extension of the municipal water supply to provide water to
residents, an IC that expands the area within which groundwater use is prohibited may be needed
to prevent exposure to the contaminated groundwater. However, a series of investigations to date
(see the Off-Site Plume Delineation and Source Evaluation section above) suggest that the WDE
Site is not the source of the contamination in the Red Oaks neighborhood. Further evaluation will
provide a more definitive conclusion as to the source, and if the WDE Site is found to contribute
to the groundwater contamination in the Red Oaks neighborhood, MPCA should consider
incorporating 1,4-dioxane as a COC in the Site remedy and placing ICs to prevent exposure.
Long-term protectiveness requires continued compliance with the land and groundwater use
restrictions to ensure that the remedy continues to function as intended. MPCA is responsible for
maintaining, monitoring, and enforcing ICs that govern land and groundwater use at the Site. In
February 2018, MPCA developed a LTS plan for the Site that ensures periodic review of ICs and
specifies actions to be taken (MPCA, 2018). The LTS procedures include visually scanning the
Site for noncompliance with ICs, evaluating and potentially updating the Groundwater Area of
Concern (GWAOC) and Methane Gas Area of Concern, and taking appropriate enforcement
actions for instances of noncompliance.
Systems Operations/Operation & Maintenance
A contractor to MPCA performs daily and monthly inspections of the Site infrastructure (e.g.,
gas collection and combustion system, groundwater collection facilities, buildings, control
panels, landfill cover, etc.). The contractor reports significant findings from facility inspections
to MPCA, as well as monthly operation and maintenance (O&M) summaries. Quarterly O&M
reports reviewed indicate a frequent need to replace well pumps, repair treatment pond aerators,
and rehabilitate extraction wells. Several quarterly O&M reports were not provided to EPA for
this FYR, including 1st quarter 2018, 2nd quarter 2020, 2nd quarter 2022, and 3rd quarter 2022.
O&M procedures are not documented in an O&M plan or manual, which is EPA's preferred
method to ensure the consistency and adequacy of O&M activities. Routine O&M activities
documented in quarterly reports include facility and Site infrastructure maintenance and repair,
monitoring of the gas flares, gas probes, groundwater extraction wells, and treatment pond, and
collecting water samples for laboratory analysis. The contractor inspects the landfill gas flare
station and records gas flare data on a bi-monthly basis. The contractor collects extraction well
data, including totalizer readings, hour meter readings, instantaneous flow rates, and cycle
counter readings to analyze individual wells for trends, identify potential maintenance needs, and
evaluate the overall effectiveness of the groundwater treatment system.
Surface water data were routinely collected prior to 2018, but do not appear to have been
collected during this FYR period. Multiple previous FYR Reports found that the landfill was not
impacting the water in Coon Creek based on the data collected during those FYR periods (e.g.,
EPA 2018), and the potential for the Site to impact the creek is expected to be the same or less
during this FYR period than previous FYR periods. Therefore, the lack of surface data during
this FYR period does not call into question the protectiveness of the remedy with respect to the
creek. MPCA has not indicated if it will perform future surface water sampling events.
16
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III. PROGRESS SINCE THE LAST REVIEW
This section includes the protectiveness determinations and statements from the last FYR as well
as the recommendations from the last FYR and the current status of those recommendations.
Table 3: Protectiveness Determinations/Statements from the 2018 FYR
ou#
Protectiveness
Determination
Protectiveness Statement
1
Short-term
Protective
The remedy at OU 1 currently protects human health and the
environment because the groundwater plume is captured and treated,
and groundwater-use restrictions are in place and effective. However,
in order for the remedy to be protective in the long-term, the following
actions need to be taken to ensure protectiveness: conduct additional
sampling for 1,4-dioxane and PFAS/PFCs5 to confirm plume capture
for these contaminants.
2
Short-term
Protective
The remedy at OU2 currently protects human health and the
environment because the landfill cap and active gas collection system
are in place and being effectively maintained, gas probes adjacent to
residences demonstrate current protectiveness, and land use controls
are in place and effective. However, in order for the remedy to be
protective in the long-term, the following actions need to be taken to
ensure protectiveness: document a remedy change decision consistent
with Minnesota law and procedures and ensure that the design and
implementation of the action to remove wastes from within the
hazardous waste pit is at least as protective as the remedy selected in
the ROD.
Sitewide
Short-term
Protective
The remedy for the Site is currently protective of human health and the
environment in the short-term because there is no evidence of a cap
breach, the groundwater plume is captured, existing Site uses are
consistent with the objectives of the land and groundwater-use
restrictions, and institutional controls are in place and effective.
However, in order for the remedy to be protective in the long-term, the
following actions need to be taken to ensure protectiveness: conduct
additional sampling for 1,4-dioxane and PFAS/PFCs to confirm plume
capture for these contaminants; and document a remedy change
decision consistent with Minnesota law and procedures and ensure that
the design and implementation of the action to remove wastes from
within the hazardous waste pit is at least as protective as the remedy
selected in the ROD.
5 Per- and Polyfluoroalkyl Substances (PFAS) / Perfluorinated Chemicals (PFCs)
17
-------
Table 4: Status of Recommendations from the 2018 FYR
ou
Recommendations
Current
Current
Completion
#
Issue
Status
Implementation Status
Date (if
Description
applicable)
1
Additional
Conduct additional
Addressed
The recommended
N/A
sampling of
sampling for 1,4-dioxane
in Next
sampling was
extraction
and PFAS to confirm
FYR
performed, and plume
and
plume capture for these
migration to the north
monitoring
contaminants.
appears to be limited by
wells for 1,4-
a combination of the
dioxane and
extraction system and
PFAS is
discharge into Coon
needed to
Creek. (See Data
confirm
Review for a summary
plume
and evaluation of the
capture.
data.) However, EPA
has not fully evaluated
documentation to
confidently rule out the
Site as a potential source
of groundwater
contamination in the
Red Oaks neighborhood.
2
Issue: The
Document a remedy
Addressed
The hazardous waste pit
N/A
proposed
change decision
in Next
was removed, but
removal of
consistent with
FYR
MPCA has not indicated
the wastes
Minnesota law and
how it selected the
from within
procedures and ensure
remedy modification
the
that the design and
consistent with
hazardous
implementation of the
Minnesota laws and
waste pit is
action to remove wastes
procedures. In addition,
not
from within the
EPA has not received all
anticipated
hazardous waste pit is at
portions of the
by the ROD.
least as protective as the
remedy selected in the
ROD.
completion report.
In addition, the following recommendation was identified during the FYR, which does not affect
current nor future protectiveness:
• MPCA should document past and upcoming changes to the remedy related to the gas
control system, groundwater treatment methods, and hazardous waste pit removal,
consistent with existing Minnesota law and procedures.
MPCA provided partial documentation of the hazardous waste removal activities (GHD, 2022).
MPCA has not identified the process and requirements for selecting and documenting a remedy
change that would be consistent with existing Minnesota law.
18
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IV. FIVE-YEAR REVIEW PROCESS
Community Notification, Involvement & Site Interviews
A public notice was made available by newspaper posting in the Anoka County Shopper, on
August 31, 2022, stating that there was a FYR and inviting the public to submit any comments to
EPA. One resident inquired about the FYR and described concerns with the WDE Site.
According to the interviewee, residents are frustrated about the long wait to be connected to the
municipal water supply and continued reliance on bottled water. The interviewee was also
concerned that the source of the 1,4-dioxane in the Red Oaks neighborhood had not been
identified, believed that the contamination showed up after the removal of the hazardous waste
pit, and suggested it was plausible that the 1,4-dioxane migrated from the WDE Site.
The results of the review and the report will be made available at the Site information repository
located at the offices of MPCA located at 520 Lafayette Road North, St. Paul, Minnesota and on
EPA's website. The Site has been deferred to MPCA's CLP, which involves the public as
appropriate and maintains a web site at: https://www.pca.state.mn.us/featured/cleaning-
hazardous-waste-wde-landfill
Data Review
Analytic data collected from monitoring wells and domestic water wells was downloaded from
the Site webpage in MPCA's Groundwater Contamination Atlas6 (No Author, 2022). Appendix
D presents the location of Site monitoring wells and summarizes the groundwater data
supporting the discussion below. Figure 4 illustrates the monitoring well and private domestic
well locations discussed below and presents MPCA's inferred GWAOC.
The ROD identified the sources of groundwater cleanup levels, some of which have been
updated or replaced over time (see "Response Actions" above). Therefore, this section compares
groundwater concentrations to the current Action Levels in Table 1.
Monitoring Wells
Table D-l in Appendix D summarizes the frequency and locations of Action Level exceedances
of non-PFAS organic chemicals during the FYR period. Groundwater concentrations of many
organic chemicals in the source area, especially in monitoring wells located at the former
hazardous waste pit, exceed Action Levels by several orders of magnitude. At the edge of the
waste, the exceedances are more limited in location and concentration. Beyond the edge of the
waste, exceedances of Action Levels for benzene, trans-1,2-dichloroethene, 1,4-dioxane,
ethylbenzene, trichloroethene, and vinyl chloride were detected north of the waste and south of
Coon Creek. No organic chemicals exceeded Action Levels in the upper sand aquifer north of
Coon Creek.
6https://webapp.pca.state.mn.us/cleanup/search/superfund?src=api&address=14437%20NW%20Crosstown%20Blvd
.%20Andover.%20MN%2055304&siteId=1458-AREA0000000004
19
-------
Table D-2 summarizes the frequency and locations of Action Level exceedances of PFAS
chemicals during the FYR period. Maximum concentrations are generally the greatest in the
source area, where they exceed Action Levels by several orders of magnitude, and lowest outside
of the waste, but wells outside of the waste still had exceedances of the Action Levels. No PFAS
chemicals exceeded Action Levels in the upper sand aquifer north of Coon Creek.
Table D-3 summarizes the frequency and locations of Action Level exceedances of dissolved-
phase inorganic metals during the FYR period. Concentrations were generally consistent within,
at the edge, and beyond the waste, but the greatest concentrations of manganese and arsenic were
outside of the waste. This suggests that the source of the high manganese and arsenic
concentrations may not be the landfilled waste. In the four monitoring wells installed north of
Coon Creek in 2016, only manganese exceeded the HRL of 100 |ig/L.
Figure 4: Groundwater Monitoring Locations, Qualitative Contamination Levels, and
Groundwater Area of Concern7
Legend
Well - Contamination above health-based guidance
Well - Contamination below health-based guidance
Well - Contamination not detected
*
Well - No data from last five years
MDH well advisory
0
Insufficient groundwater sampling data
1
Potential source area
¦
Groundwater area of concern
Groundwater area of concern boundary
high confidence
low confidence
Bunker Lake Boulevard f^rthwe^ 116] ^
Station Parkway Northwest
,39th La""*"
aprive
Serf
i :- Jne
Andover Bouleva
""""No,
. &
B MOrh Larirtfy
r/j Lane Noithwest
'3»h Avenue
,m| Bunker u*« N°rt
Domestic Water Wells
During the FYR period, approximately 164 domestic water wells were sampled for many of the
chemicals listed in Table 1, including several PFAS compounds and 1,4-dioxane (No Author,
2022). The private wells sampled were located north of the Site and Coon Creek, noithwest of
the Site and Crosstown Boulevard, and in an adjacent neighborhood to the south of the Site, as
shown in Figure 4, along with Site monitoring well locations.
1 https://webapp.pca.state.mn. us/cleanup/search/superfund?siteId=1458-AREA0000000004
20
-------
Table D-4 in Appendix D summarizes the PFAS chemicals, number of samples collected, and
maximum and minimum detected concentrations in domestic wells. Six domestic wells had
concentrations of at least one PFAS chemical above the HBV action level, and three wells had
perfluorooctanesulfonate above the regional screening level (RSL) equating to a hazard index
(HI) of one (see Table 5). The six wells are all southwest and upgradient of the Site, but the
upgradient edge of the groundwater area of concern is dashed to show a low level of confidence
in how far upgradient the Site source area may impact groundwater (see Figure 4). Eight PFAS
chemicals with RSLs were not analyzed (See Table D-5).
Table 5: PFAS Action Level Exceedances in Domestic Water Wells
CAS
No.
PFAS Chemical
Well ID
Concentration,
fig/L
Date
Action
Level
Source
Action
Level,
fig/L
Tapwater
RSL,
HI=1,
Hg/L
108427-
53-8
Perfluoro-
hexanesulfonate
(PFHxS)
1000022441
0.28
7/21/2021
HBV
0.047
0.39
1000026119
0.16
8/5/2021
511933
0.12
8/12/2021
174856
0.11
8/25/2021
45298-
90-6
Perfluoro-
octanesulfonate
660093
0.065
8/12/2021
HBV
0.015
0.04
511933
0.047
8/12/2021
1000026116
0.016
8/5/2021
Table D-6 summarizes the non-PFAS chemicals detected in domestic wells. Only 1,4-dioxane
was detected above the Action Level. Concentrations of 1,4-dioxane exceeded the HRL of 1
|ig/L in 42 of the 158 wells sampled. Seven wells had concentrations greater than the tapwater
RSL corresponding to an excess lifetime cancer risk of 10"4 and a HI of one (45.9 |ig/L),
suggesting an unacceptable risk to human health. However, the extent to which the Site
contributes to the groundwater contamination in the Red Oaks neighborhood is unclear given
that the domestic wells are all south-southwest and upgradient of the Site and there appears to be
an upgradient source unrelated to the WDE Site. Wells north of Coon Creek did not have 1,4-
dioxane concentrations above the HRL of 1 |ig/L during the FYR period.
Landfill Gas
Appendix D of the quarterly O&M reports present methane data, gas flow rate, and other data
collected monthly for 53 of the 54 gas extraction wells (GW-43 appears not to be monitored).
Methane percent ranges from 0% to more than 50%, indicting significant ongoing methane
generation within the landfill.
Appendix E to the quarterly O&M reports presents methane data for 17 gas probes installed
around the perimeter of the waste, although the system was reported to include 27 gas probes
previously (EPA, 2018), and it is unclear why several probes are not routinely monitored. Ten
probes along the housing development on the west side of the Site are monitored monthly, and
seven probes along the perimeter of the Site are monitored quarterly. No methane was reported
in the gas probes in the O&M reports available for review during this FYR period, indicating that
the active landfill gas collection and flare system prevents off-site migration of landfill gas.
21
-------
Site Inspection
The inspection of the Site was conducted on September 26, 2022. In attendance were Leslie
Patterson of EPA and Dan McNamara of MPCA. The purpose of the inspection was to assess the
protectiveness of the remedy. Site components such as the groundwater extraction system piping
and well heads, gas flare system, landfill cover, detention pond with aerator, roads, and fencing
appeared to be in good condition and no evidence of trespassing or IC noncompliance was noted.
Appendix C presents the Site inspection checklist and photolog.
V. TECHNICAL ASSESSMENT
QUESTION A: Is the remedy functioning as intended by the decision documents?
Question A Summary:
No; a remedial system is operating and generally meets the 1987 RAOs specified in the ROD,
but the remedial components differ from the remedy selected in the ROD and the Site has not
been ruled out as a contributing factor to contaminated groundwater in neighborhoods where
residents have private groundwater wells.
Remedial Action Performance
The 1987 ROD called for a lime sludge cap, clay slurry wall around the hazardous waste pit,
carbon adsorption and/or air stripping treatment of extracted groundwater, discharge of treated
extracted groundwater to Coon Creek, venting of landfill gas, and monitoring forNAPL. These
components of the selected remedy have been discontinued or replaced by alternative means to
meet RAOs without issuing a remedy modification document, so are not operating as intended
by the ROD. The landfill gas and waste containment systems generally meet the RAOs of
preventing or minimizing further contaminant release and preventing or minimizing exposure to
contaminated waste. The extent of the 1,4-dioxane plumes related to the Site and in the Red Oaks
neighborhood have not been delineated, so the Site has not been ruled out as a contributing factor
to 1,4-dioxane, and potentially PFAS, contamination in private domestic wells. EPA
recommends additional delineation of the vertical and lateral extent of PFAS and 1,4-dioxane to
determine if the Site is a source.
System Operations/O&M
MPCA has not documented its O&M procedures in an O&M plan or manual, and updated
figures and descriptions of the current as-built remedial systems are not available. The
procedures and rationale for the frequency of groundwater, surface water, and landfill gas
monitoring are not clear. Surface water monitoring was not performed during this FYR period,
although some groundwater contamination migrates beyond the northern boundary of the waste
and discharges into Coon Creek. Quarterly reports indicate a frequent need to replace well
pumps, repair treatment pond aerators, and rehabilitate extraction wells. Without a written O&M
Plan or manual, it is unclear how consistency and optimization of O&M activities are achieved.
22
-------
Implementation of Institutional Controls and Other Measures
Locked fencing and secured wellheads help prevent exposure to contaminated materials and
damage to remedial components. ICs are also in place and are effective at the Site, but the
discovery of upgradient groundwater contamination in the Red Oaks neighborhood requires
additional groundwater restrictions in this area. If the contamination is found to be unrelated to
the WDE Site, then those ICs would be independent of the WDE remedy.
QUESTION B: Are the exposure assumptions, toxicity data, cleanup levels, and RAOs used
at the time of the remedy selection still valid?
Question B Summary:
No. Land use near the Site is unchanged, but an exposure pathway to contaminated groundwater
through private residential well use has been discovered. Standardized risk assessment
methodologies have not changed in a way that invalidates the RAOs and cleanup expectations in
the ROD. However, State-established groundwater cleanup levels have changed from RALs to
HBVs and HRLs, and it is unclear what the numeric standards are that correspond to the ROD's
expectation of meeting "10"6 risk water quality criteria".
Changes in Standards and To Be Considered
The 1987 ROD did not identify specific COCs or numeric standards for specific chemicals in
groundwater or surface water. The federal MCLs identified in the ROD as ARARs for
groundwater have not changed, but Minnesota has discontinued use of RALs and established
promulgated HRLs and non-promulgated HBVs and RAA criteria. This does not affect
protectiveness because Site data are compared to the updated standards as Action Levels. In
addition, the ROD did not specify numeric standards that correspond to "10"6 risk water quality
criteria".
Changes in Toxicity and Other Contaminant Characteristics
Toxicity information has become available for several PFAS chemicals, such that screening
levels and Action Levels have been calculated.
Changes in Exposure Pathways
The Site appears to be a source for 1,4-dioxane and PFAS contaminants that migrate beyond the
waste to the north and potentially discharge into Coon Creek, but monitoring of domestic wells
and monitoring wells north of Coon Creek do not indicate that those domestic wells are affected
by Site contaminants. The neighborhood south and west of the Site is upgradient of the Site,
indicating an off-Site source of the 1,4-dioxane in groundwater in this neighborhood, but the Site
has not been ruled out as a contributing source.
Expected Progress Towards Meeting RAOs
The remedy appears to adequately contain and treat landfill gas. The remedy largely contains and
treats contaminated groundwater, but some groundwater contamination migrates beyond the
northern boundary of the waste and discharges into Coon Creek.
23
-------
QUESTION C: Has any other information come to light that could call into question the
protectiveness of the remedy?
No. There have been no climate-related effects or natural disasters, significant changes in
precipitation or temperature, or increased risk of floods that adversely impacted the Site remedy.
No other events have affected the protectiveness of the remedy, and there is no other information
that calls into question the short-term protectiveness of the remedy.
VI. ISSUES/RECOMMENDATIONS
Issues/Recommendations
()l (s) without Issues/Recommendations Identified in the Fi\e-Year Rcxicw:
None.
Issues itncl Recommendations Identified in the Fi\e-Year Rexiew:
OU(s): 1
Issue Category: Remedy Performance
Issue: The WDE Site has not been ruled-out as a contributing source
for 1,4-dioxane and PFAS in the Red Oaks neighborhood.
Recommendation: Evaluate the existing hydrogeologic and
contaminant distribution information to determine if the Site is a
contributing source to the 1,4-dioxane and PFAS plumes affecting
private residential wells
Affect Current
Protectiveness
Affect Future
Protectiveness
Party
Responsible
Oversight
Party
Milestone Date
Yes
Yes
EPA/State
EPA
11/30/2023
OU(s): 1
Issue Category: Remedy Performance
Issue: The ROD does not specify groundwater COCs or include
numeric groundwater cleanup standards, and in some cases, ARAR-
based standards have been replaced, so it is unclear how to evaluate
the performance of groundwater containment.
Recommendation: Specify groundwater COCs and numeric
groundwater cleanup levels in a remedy modification document
consistent with Minnesota law and procedures.
Affect Current
Protectiveness
Affect Future
Protectiveness
Party
Responsible
Oversight
Party
Milestone Date
No
Yes
State
EPA
12/31/2023
24
-------
OU(s): 2
Issue Category: Remedy Performance
Issue: The removal of the wastes from within the hazardous waste
pit was not anticipated by the ROD.
Recommendation: Document the remedy modification decision
consistent with Minnesota law and procedures.
Affect Current
Protectiveness
Affect Future
Protectiveness
Party
Responsible
Oversight
Party
Milestone Date
No
Yes
State
EPA
12/31/2023
OU(s): 2
Issue Category: Remedy Performance
Issue: EPA does not have complete documentation that the removal
of the hazardous waste pit has resulted in a remedy at least as
protective of human health and environment as response actions
required under CERCLA.
Recommendation: Provide the entire completion report for the
hazardous waste pit removal to EPA.
Affect Current
Protectiveness
Affect Future
Protectiveness
Party
Responsible
Oversight
Party
Milestone Date
No
Yes
State
EPA
6/30/2023
OTHER FTNDTNGS
In addition, the following are recommendations that were identified during the FYR and may
improve management of O&M, but do not affect current or future protectiveness:
• O&M procedures are not documented in an O&M plan or manual. Updated figures and
descriptions of the current as-built remedial systems are not available. The procedures
and rationale for the frequency and sampling locations of groundwater, surface water, and
landfill gas monitoring are not clear. EPA recommends that MPCA develop an O&M
plan that presents this information.
• MPCA should document past and upcoming changes to the remedy related to the gas
control system and groundwater treatment methods, consistent with existing Minnesota
law and procedures.
• Groundwater data suggest that a portion of the groundwater plume discharges into Coon
Creek. Data collected prior to 2018 have indicated that the discharge does not cause an
exceedance of Minnesota Class 2B chronic surface water quality criteria, but it is unclear
whether potential impacts from groundwater discharge continue to be evaluated. EPA
recommends that MPCA either describe the sampling program to evaluate potential
impacts to Coon Creek in an O&M Plan or prepare a memorandum documenting that
there is no longer any potential for unacceptable impacts to the Creek, which would
support discontinuing monitoring the creek.
25
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VII. PROTECTIVENESS STATEMENT
Protectiveness Statement(s)
Operable Unit: Protectiveness Determination: Planned Addendum Completion Date:
1 Protectiveness Deferred 3/31/2024
Protectiveness Statement:
A protectiveness determination of the remedy at OU1 cannot be made at this time until further
information is obtained. Further information will be obtained by taking the following action:
evaluate the existing hydrogeologic and contaminant distribution information to determine if
the Site is a contributing source to either the 1,4-dioxane plume or affecting private residential
wells, or the isolated PFAS exceedances. It is expected that this action will take approximately
one year to complete, at which time a protectiveness determination will be made.
Protectiveness Statement(s)
Operable Unit: Protectiveness Determination:
2 Short-term Protective
Protectiveness Statement:
The remedy at OU2 currently protects human health and the environment because the landfill
cap and active gas collection system are in place and being effectively maintained, no methane
is detected in gas probes adjacent to residences, and ICs are in place and effective. However,
in order for the remedy to be protective in the long-term, the following actions need to be
taken to ensure protectiveness: document a remedy change decision consistent with Minnesota
law and procedures and provide the entire completion report for the hazardous waste pit
removal to EPA.
Sitewide Protectiveness Statement
Protectiveness Determination: Planned Addendum Completion Date:
Protectiveness Deferred 3/31/2024
Protectiveness Statement:
A protectiveness determination of the remedy at the Site cannot be made at this time until
further information is obtained. Further information will be obtained by taking the following
action: evaluate the existing hydrogeologic and contaminant distribution information to
determine if the Site is a contributing source to either the 1,4-dioxane plume or affecting
private residential wells, or the isolated PFAS exceedances. It is expected that this action will
take approximately one year to complete, at which time a protectiveness determination will be
made.
VIII. NEXT REVIEW
The next FYR report for the WDE Superfund Site is required five years from the completion date
of this review.
26
-------
APPENDIX A - REFERENCE LIST
Braun Intertec Corporation. (2022a). Preliminary Source Evaluation. #05-979608: February 8,
2022.
Braun Intertec Corporation. (2022b). Groundwater and Surface Water Receptor Survey. #05-
979609: March 18, 2022.
Braun Intertec Corporation. (2022c). Site Conceptual Model and 3-D Visualization Modeling.
#05-979611: April 28, 2022.
Braun Intertec Corporation. (2022d). Groundwater Investigation. #05-979610: October 7, 2022.
City of Andover. (1996). Ordinance 19P: An Ordinance Amending Ordinance No. 19N, Known
as the Building Ordinance of the City of Andover. January 16, 1996: #05-271402.
EPA & MPCA. (2018). Amended and Restated Agreement Between the United States
Environmental Protection Agency and the Minnesota Pollution Control Agency
Regarding Qualified Municipal Waste Landfills under the Minnesota Landfill Cleanup
Law. June 6, 2018: #05-550841.
EPA. (1987). Record of Decision: Remedial Alternative Selection. December 31, 1987: #05-
164783.
EPA. (1992). Record of Decision. September 30, 1992: #05-164786.
EPA. (1995). Preliminary Close Out Report. September 27, 1995: #05-132482.
EPA. (2018). Fifth Five-Year Review Report for Waste Disposal Engineering Super fund Site.
April 24, 2018: #05-940662.
GHD. (2016). Groundwater Assessment North of Coon Creek. June 28, 2016: #05-2001393.
GHD. (2022). Removal Action Documentation Report: Industrial Waste Pit Removal Action.
June 2022: #05-2004873.
MPCA. (2006). Land Use Plan: Waste Disposal Engineering Landfill. March 30, 2006: #05-
295632.
MPCA. (2018). Long-Term Stewardship Plan for Institutional Controls (ICs) at the Waste
Disposal Engineering Landfill. February 23, 2018: #05-UPLOADED.
No author. (1995). Landfill Cleanup Agreement between Anoka County and the Waste Disposal
Engineering (WDE) Group and the Commissioner of the Minnesota Pollution Control
Agency. October 27, 1995: #05-269791.
A-l
-------
No Author. (1996). Access Easement and Use Restrictions Agreement between the
Commissioner of the Minnesota Pollution Agency, the WDE PRP Group, and Gerald G.
and Carol A. Windschitl. January 4, 1996: #05-269793.
No author. (2001). Declaration of Restrictive Covenants. November 27, 2001: #05-269792.
No Author. (2022). Groundwater Monitoring Data and Monitoring Well Information. September
13, 2022: #05-2004704.
Willow Brook Engineering. (2018a). Quarterly Monitoring Report (2nd Quarter 2018). July 20,
2018: #05-2004920.
Willow Brook Engineering. (2018b). Quarterly Monitoring Report (3rd Quarter 2018). October
20, 2018: #05-2004874.
Willow Brook Engineering. (2019a). Quarterly Monitoring Report (4th Quarter 2018). January
20, 2019: #05-2004875.
Willow Brook Engineering. (2019b). Quarterly Monitoring Report (1st Quarter 2019). April 20,
2019: #05-2004876.
Willow Brook Engineering. (2019c). Quarterly Monitoring Report (2nd Quarter 2019). July 20,
2019: #05-2004877.
Willow Brook Engineering. (2019d). Quarterly Monitoring Report (3rd Quarter 2019). October
20, 2019: #05-2004878.
Willow Brook Engineering. (2020a). Quarterly Monitoring Report (4th Quarter 2019). January
20, 2020: #05-2004879.
Willow Brook Engineering. (2020b). Quarterly Monitoring Report (1st Quarter 2020). April 20,
2020: #05-2004880.
Willow Brook Engineering. (2020d). Quarterly Monitoring Report (3rd Quarter 2020). October
20, 2020: #05-2004881.
Willow Brook Engineering. (2021a). Quarterly Monitoring Report (4th Quarter 2020). January
20, 2021: #05-2004883.
Willow Brook Engineering. (2021b). Quarterly Monitoring Report (1st Quarter 2021). April 20,
2021: #05-2004882.
Willow Brook Engineering. (2021c). Quarterly Monitoring Report (2nd Quarter 2021). July 20,
2021: #05-2004884.
Willow Brook Engineering. (202 Id). Quarterly Monitoring Report (3rd Quarter 2021). October
20, 2021: #05-2004885.
A-2
-------
Willow Brook Engineering. (2022a). Quarterly Monitoring Report (4th Quarter 2021). January
20, 2022: #05-2004886.
Willow Brook Engineering. (2022b). Quarterly Monitoring Report (1st Quarter 2022). April 20,
2022: #05-2004887.
A-3
-------
APPENDIX B - INSTITUTIONAL CONTROL MAP
Figure B-l: Area Restricted in the November 27, 2001 Declaration of Restrictive Covenants (modified from MPCA's
Groundwater Area of Concern Map,dated December 5, 2017)
Site Features
Waste Footprint
''V Groundwater Plume
Groundwater Area of Concern
An area where the
groundwater may be affected
by landfill contamination.
Land Management Area
Designates the property that
. — is under the responsibility
' —' and control of the MPCA
for the purpose of taking
environmental response actions.
Monitoring Well
® Sealed (4)
® Active (72)
O Pumping Wells (8)
B-l
-------
APPENDIX C - FIVE YEAR REVIEW INPSECTION CHECKLIST AND PHOTOLOG
I. MU IM'ORM \ I ION
Site name: Waste Disposal Engineering
Date of inspection: September >. 2022, !2pi
Location and Region; Awlovcr, Anoka Co., MM; 15
oflkv. or a.mjuiin kadinti the fiu*u>ar
review; EPA Region §
Remedy Includes: (Check all that apply)
~Landfill cover/containment Monitored natural attenuation
Access controls Groundwater containment
tettiuliona! controls Vertical barrier walls
^-Groundwater pump and treatment ' 5/v 1
Sijfface water collection and treatment :
^fxher / ftiTLTe
Attachments: Inspection team rosier studied Site map attached
II. INTERVIEWS (Check ail that apply)
0&\! site manager John Hunter Land Manager
Name
Interviewed it site at office ~iypfwne Phone no,
rrooiems, suggestions, Report attached _
2 „ 0& M staff Pan McNamara Field Representative
Name Title Dale
Interviewed %M site at office by phone Phone no. _______
Problems, suggestions; Report attached , ,
C-l
-------
usilfA' \w o office. |>ohec department, office ol public health or em iioniitenial health, /onita- oifiee,
teeordet of deeds. or other cit\ and counts offices, etc ) Hll in all that appl\
Agency
Contact
Name I itle Date Phone no
Ptoblems. suggestions. Report attached
A|>e»e\
Contact
Name Ink" Date Phone no
Problems, suuuestions, Report attaeheil
Agency
I ontact
Name Title Dale Phone no
I'lobleiii-H. Mit'iiesttons: Report attached
Asienev
l ontaei _ _ _
Name Title Date Phone no
Problems, suuue.stions, Report attached _ _
4. Other interviews (optional) Report attached.
C-2
-------
out/ K \,> < • mis p
III. OVMIt DOC I MIMSX Ul ( ORDs \ I Rll IH) :• - • u! .,P;^ .
n Records
Remarks,
Readily available
Up to
N/A
Uim ti;irut' ( (inipli;)nic Ktronh
Water (cfljuent) „ |.eaiiily
Rcmarks i*'" P :*?>< ,J^r 4- ;
Readily available
available
_
Up to dale
I !p to date
\ \
N \
10. I \rtns Srcurii v I <>«s
Remarks
Readily available
I "p to d.itc
\ A
C-3
-------
< Alt I ,V V/ '/<¦-> ' ^
IV. « »A. M ( OS|S
O&M Orgsnizfitton
„ m-IUHI>C
PRPlri-hottse
Federal Facility in-house
Other
; for State'"
Contractor fori
Contractor for federal Factln>
U.vM < ..Sl ken.Ids
Readily available Up to«
Funding mccltanism/agrecment in place
Original O&M cos!«
Total annual cost, by year
From
To
Date
Date
From
To
Dale
Date ,
From
To
/
Date
Ae
from
To
/
Date
/
/ Date
From
To/
Dale
/
Dale
otal cost
Total cost
Total cost
Total cosl
Breakdown attached
if available
Breakdown attached
Breakdown attached
Breakdown attached
Breakdown attached
Breakdown attached
Total cosl
I H-.iiili. ui,(H(1 ... I miMialh HiUl. OWI < ..Ms Diir m
AL CONTROLS Applicable
V f Ciliiit;:
1, fencing damaged
Remarks
Location shown on site,map
N/A
1, ©titer Access Restrictions
-1 ml ollli > si t III Il\ lilt.(suits
Location shown on site tnap
N/A
C-4
-------
tJHil/ K V> ^ < ' (•«'/> J*
< . ImliiutitHiiil ( Dntroh (i( si
Inipli-nn-ntatiun and color fi-im-nt
Site conditions imply ICs not properly implemented
Site conditions imply ICs not being fully enforced
Type of monitoring (e.g., self-reporting, drive by) _
Frequency.
Responsible party/agency.
Contact
Name
Reporting is up-to-date
Reports are verified by the lead agency
i nk
Yes
Yes
N/A
N/A
Specific requirements in deed or decision documents have been met
Violations have been reported
Other problems or suggestions: Report attached
Date
Yes
Yes
Yes
Yes
No
No
Phone no
N/A
N/A
Remarks
, H n au- .'lilvqu.nc ICs are inadequate
N/A
I), ((tiurui
Vi
Remarks
jCLLL
lag Location shown on site map I
isS*la«L_
No vandalism evident
N/A
i and use
Remarks
:^aOL
N/A
X I. (a M K VI SI I I < ONDI I |()\v
N/A
Remarks
N \
C-5
-------
< >Mt / H P
Remarks
\n I \MII II I. ( (HI Rs N \
\ 1 HKH.Ii Stirlurt-
Settlement (Low spots)
A real extent......
Remarks
Location shown on site map
Depth
not evident
< I.Hkv
Lengths....
Remarks
Location shown on site map
Widths Depths.. ._...
not evident
t fusion
Areal exteml,.
Remarks
Location shown on site map ^-JSfosfon not evident
Depth
Location shown on site map i#^Hoies
Depth
H»lo
Areal extent _
Remarks
not evident
Vegetative Cove r K^iss vt pnn»crly established No signs of stress
Trccs/Shrubs (indicate size and locations on « diagram) ,
Remain V- : «.. l«- , i< "
Rcnisrk s
Buiuts
Areal extent_
Remarks
Location shown on site map
Height
not evident
C-6
-------
OSH-m Nu. 9J55.7-0SB-P
u
O.
Wet Areas/Water Damage i.Wtf'.tie.ts/water damage not evident
Wet areas Location shown on site nap Area! extent
Ponding Location shown on site map Areal extent
Seeps Location shown on site map Areal extent
Soft subgrade Location shown on site map Areal extern
Remarks
9,
histahilin
Areal extent
Remarks
Slides Location shown on site inap ^^Pirtfvtiience of slope instability
K. Bene lies Applicable N/A
(Horizontally constructed mounds of earth placed across a steepJaitimU side slope to interrupt the slope
in order to slow clown the velocity of surface runoff and injptfipt and convey the runoff to a lined
channel.) * /
1-
i Iiims B\p;tss B«*n
eli Localipirlnown on site map .VAotokay
1
Bitit h tlrriu'lu'd
Rcnisrks
-
3.
lil'IU'h 0\ tTtOpfKH
Remarks
i Location shown on site imp N/A or okay
_ -zzn
€, I.
etdown Channels Applicable N/A
(Channel lined with erosion control mats, riprap, grout bags, or gabions tfijf'deseeiid clown the sleep
side slope of the cover and will allow the runoff water collected by thejj6»elies to move off of the
landfill cover without creating erosion gullies.) /*
I.
v. <;
Location shown on site map /* No evidence of settlement
Depth /
Remarks
2,
'•'•HlMl ail.i
Material type
fan Locution shown on/tle map No evidence of degradation
Areal extcjrt
Remarks
-
/
3.
Areal extent
Locatkm^town on site map No evidence of erosion
Kenwrks
...
/ — — —
C-7
-------
OSWEM No, 9SS5,7-OSB-f"
4.
Undercutting Location shown on site map (^evidence of undercutting
Areal extent Depth
Remarks
5,
Obstruction*.
Location shown on site map
Size
Remarks
Areal extent
6
f vhamm \ imitative (I \]v
yM&€\< idence of excessive growth
l^egetation in channels does not obstruct Jlow
Location shown on site map -\rcal evicnt
Remarks
D.
Co*t-i P> nctr ations v^pplicab"- \ A
1.
t .a\ \ i*tits A,
y/rroperly secured/locked i^fuiiclioriing
Evidence of leakage at penetration
N/A
Remarks
Passive
, •Routinely sampled j^eSod condition
Needs Maintenance
2,
(,a\ Monitonnu I'ntlH's
wiroperly secured/locked ^ftfnctioning
Evidence of leakage at penetration
Remarks
^Routinely sampled l£HSod condition
Needs Maintenance N/A
3,
MMMv Wells (within surf«.«rea of landfill),.
v^roperly secured/locked patterning vftoutinely sampled i^Mcxfaiiiciitton
Evidence of leakage a! penetration Needs Maintenance N" \
Remarks
4.
i Wdiuu-l NJraelii.H Wtlls
vWoperly secured/locked vtfSnctk»mg
Evidence of leakage at peneiraiion
Remarks
MCoiitineiy sampled fc»
-------
USUI h' ,\<
K. t.iis ( olleetiun and I reatmeiit
i-XppI
icuhle
N A
(,as I roatineiit I acilitici
\yPfarinp Thermal destruction Collection for reuse
< uhhJ condition Needs Maintenance
Remarks y t \ i . •,«. I> i k < \> a
\ fl *'C»1 S.V. <'<• *> ', ^L. )
f iC i tv * \ 1 ii* ¦ '¦*»*, t
,i I
2, (.as Collection Wrlls. Manifolds ami i'ipin^
¦ ,/CkhhI comlition Needs Maintenance
RctlMI ks
" if iil'-f*
(Ja\ Monitorin<> Facilities, (c t; , uas mitn»onnj> of adjacent homes or buildings)
(iood condi I ton Needs Maintenance ,Xa
Remarks v , i, t1 , , „ » v , > d r'.
J
1 . ('o\ cr Orainaue i a> er
Outlet Pipes Inspected
Remarks
Applicable
luneiiuninu
*3" \
N '\
Outlet Uock Inspected
Remarks
l-tmclionmg
N \
(,, Detftniiui Sedimentation i'oiuis
t*-Applicab!e
\
Siltutioii \real extent
Siltation not ev idem
Remarks
Depth
I-1 osiun A real cx tent
( rosioi* not e\ idcnl
Remarks
Depth
Outlet \Sorks
ReinarLs
Itmclionsne
N A
4, Ham
Remarks
hmctiomne
N A
-&>
.'o e^coA i
,v >,
C-9
-------
H.
Hvrainiji" Walls • \. \
DffermONtt Locatioj>0 Nik- Dischar^ \ ... .
N A
I.
Nidation 1 ocatton shown on site inpf> Siltation not evident
\tcal extern Depth
Remarks
/
2.
Vegetative Growth Lo^rfion shown on site map
Vegetation does not impede,Jow
Arsii extern /* Type
Remarks
N/A
/
3.
Erosion / Location shown on site map
Areai extent / Depth
Remarks /
Erosion not evident
4,
Discharge Structure Functioning N/A
Remarks
VIII. VERTICAL BARRIER WALL'S
Applicable N A
1,
Settlement Location shown y*f site map
Area! extent Depth /
Remarks
Settlement not evident
2.
Performance MonitorlngType of^onitoring
Performance no! monitored /
Frequency / Evidence of breaching
Head differential /
Remarks /
/
C-10
-------
t mi / r v. v;f» • 11<){ p
IVCHOISimUIKSIKIUMHIIKRfMiDlis Applicable N \
V (,i
-------
mil / \.. v 1 F
C, Treatment System yk^plieable N/A
1. Treatment Train (Check components that apply I
Metals removal Oil/water separation Bioremediation
Air stripping , Carbon adsorbers «
Additive {eg,, chelation agent, noccuIent)__^_
Others
Good condition Needs Maintenance
Sampling ports properly marked and functional
Sampling/maintenance log displayed unci up to date
Equipment properly identified
Quantity orgroundwater treated annually.
Quantity of surface water trotted annually.
Remarks t7 k,—
Electrical Enclosuu-s and Panels (properly rated unci functional)
N/A condition Needs Maintenance
Remarks
3,
I .ink". \ illlltV s
N/A
Remarks
>torage,\ essels
t^wod condition
Prop*r secondary attainment Needs Maintenance
4
Uis> iiai ji Mr lit mi •• :.nJ Vj.j.i.i Uii.uii.
N/A faSftJod condition
Remarks
Needs Maintenance
5, I t< .mm nr HtiililintifM
N/A {ytfood condition (esp. roof and doorways) Needs repair
Chemicals and equipment properly stored
Remarks „ — _ _
6. Monitoring Wells (pump and treatment remedy)
~'"Properly secured/locked jJPtfnctioning tJMitinely sampled i-^Sood condition
All required wells located Needs Maintenance N/A
Remarks,,
I) Mi'intoi inu D.ita
1, Monitoring Qi^'1
l/fs routinely submitted on time Is of acceptable quality
2. Monitoring data suggests;
Groundwater plume is effectively contained Contaminant concentrations are declining
C-12
-------
t >,\ll i H <)
I HI K M Mi 1)11 s
If there are remedies applied at the site which are not covered above, attach an inspection sheet describing
the physical nature and condition of any facility associated with the remedy, An example would be soil
vapor extraction.
\l OS I K u 1 OHst lU \i ions
,4,
Describe issues and observations relating to whether tic remedy is effective and functioning as
designed. Begin with * brief statement of what the remedy is to accomplish (i.e., to contain contaminant
plume, minimize infiltration and gas emission, etc.).
i!
X .(t * .x*. .. jf,„ V »~ . <•/>> • • 1' . - j£-*„ • , - , .
» w . \->t c . i-.j ' » •./ . t_ * 'i . 4•. *
rim
Ji£dhk
; " v ,, v , / , /
ff, "i..i *
aT~
> of OA \t
Describe issues and observations related to the implementation and scope ofO&M procedures. In
particular, discuss their relationship to the current and long-term protcciivcness of the remedy.
:«.<« v, • i . t-. ¦ i
¦V,. . » . I,
i A* t*> ,/ * y V*.*. ~. '
-------
OSIVE/i ,¥», 93SSJ4BB-P
Early Indicators of Potential Remedy Problems
Describe issues and observations such. as unexpected changes in the cost or scope of O&M or a high
frequency of unscheduled repairs, that suggest thai the protectiveness of the remedy amy be
compromised in the future.
I). < )pjM.« 1 itmlti v Stir < >|.limiAtnnii
Describe possible opportunities for op|iniization in monitoring tasks or the operation of the remedy.
../i i . ./jr. -v , > tt. -
, ' T i w < -ti J. i'ly 4
C-14
-------
Date:
September 26,2022
Site Name:
Waste Disposal Engineering Superfund Site
Direction
Photo
Taken:
NW
Description:
Gas flare system.
Site Name:
Waste Disposal Engineering Superfund Site
Date:
September 26,2022
Photo
No.
Direction
Photo
Taken:
NA
Description:
Extraction well
manifold in the
groundwater
pump out
building.
C-15
-------
Site Name:
Waste Disposal Engineering Superfund Site
Date:
September 26,2022
Photo
No.
Direction
Photo
Taken:
NA
Description:
Filtration tanks
for removing
PCBs, initially
for EW9, now
EW16.
Site Name:
Waste Disposal Engineering Superfund Site
Date:
September 26, 2022
Photo
No.
4
Direction
Photo
Taken:
NW
Description:
Groundwater
pump out
building
surrounded by
fencing and
signage.
C-16
-------
Site Name:
Waste Disposal Engineering Superfund Site
Date:
September 26,2022
Photo
No.
Direction
Photo
Taken:
NW
Description:
Wellhead
enclosure and
electric box for
EW-10.
Site Name:
Waste Disposal Engineering Superfund Site
Date:
September 26, 2022
Photo
No.
6
Direction
Photo
Taken:
NA
Description:
EW-10
wellhead.
C-17
-------
Site Name:
Waste Disposal Engineering Superfund Site
Date:
September 26,2022
Photo
No.
Direction
Photo
Taken:
E
Description:
Northern edge of
waste.
Site Name:
Waste Disposal Engineering Superfund Site
Date:
September 26, 2022
Photo
No.
8
Direction
Photo
Taken:
w
Description:
Former methane
to electricity
generation
building, now
equipment
storage.
C-18
-------
Site Name:
Waste Disposal Engineering Superfund Site
Date:
September 26, 2022
Photo
No.
Direction
Photo
Taken:
NNE
Description:
View of landfill
surface and gas
extraction wells
near the former
hazardous waste
pit.
Site Name:
Waste Disposal Engineering Superfund Site
Date:
September 26, 2022
Photo
No.
10
Direction
Photo
Taken:
NW
Description:
View toward the
detention pond
from the top of
the landfill, near
the hazardous
waste pit.
C-19
-------
Site Name:
Waste Disposal Engineering Superfund Site
Date:
September 26,2022
Photo
No.
11
Direction
Photo
Taken:
N
Description:
Wellheads of
new monitoring
wells installed in
the area of the
former
hazardous waste
pit after its
removal.
Site Name:
Waste Disposal Engineering Superfund Site
Date:
September 26, 2022
Photo
No.
12
Direction
Photo
Taken:
SE
Description:
View of the top
of the landfill
from the former
hazardous waste
pit.
C-20
-------
Site Name:
Waste Disposal Engineering Superfund Site
Date:
September 26,2022
Photo
No.
13
Direction
Photo
Taken:
NA
Description:
Inside the
electric box for
EW-16.
Site Name: Date:
Waste Disposal Engineering Superfund Site September 26, 2022
Photo
No.
14
Descrip
Outfall
detentio
Direction
Photo
Taken:
E
tion:
into the
n pond.
C-21
-------
Site Name:
Waste Disposal Engineering Superfund Site
Date:
September 26,2022
Photo
No.
15
Direction
Photo
Taken:
SE
Description:
Wastewater
detention pond.
C-22
-------
APPENDIX D - SUMMARY OF GROUNDWATER MONITORING
Figure D-l: Monitoring Wells and Piezometers
WELL LOCATION
CROSS-SECTION LOCATION
WASTE DISPOSAL ENGINEERING INC. CLOSED LANDFILL
ANDOVER, MINNESOTA |jun24.2016
GROUNDWATER ASSESSMENT NORTH OF COON CREEK
ACTIVE MONITORING WELL LOCATIONS FIGURE 1
D-l
-------
Table D-l: Non-PFAS Organic Chemical Action Level Exceedances in Monitoring Wells and Piezometers within the Waste, at Waste Boundary, and Outside of
Waste, 2018-2022
Action
Level
Source
Action
Level,
fig/L
In waste1
Edge of waste2
Outside waste3
CAS No.
Chemical
#
Exceedances
Maximum
Location of
#
Exceedances
Maximum
Location of
#
Exceedances
Maximum
Location of
Exceedance,
Hg/L
Maximum
Exceedance
Exceedance,
Hg/L
Maximum
Exceedance
Exceedance,
Hg/L
Maximum
Exceedance
67-64-1
Acetone
HBV
3000
6
130,000
NW-3AR
None
None
71-43-2
Benzene
HRL
2
37
84
NW-2B
30
51
W-11A
26
35
B2
95-50-1
1,2-Dichlorobenzene
MCL
600
1
1,700
NW-1AR
None
None
75-34-3
1,1 -Dichloroethane
RAA
80
11
72,000
NW-2B
None
None
06-02-0107
1,2 -Dichloroethane
HRL
1
10
170
NW-2B
None
None
75-35-4
1,1 -Dichloroethene
MCL
7
8
1,500
NW-2B
None
None
156-59-2
cis-1,2 -Dichloroethene
HRL
6
18
84,000
NW-2B
3
25
W-11A
None
156-60-5
trans-1,2-Dichloroethene
HBV
9
5
170
NW-2B
1
18
W-11A
1
13
B2
75-43-4
Dichlorofluoromethane
RAA
20
7
440
NW-2B
None
None
78-87-5
1,2 -Dichloropropane
HBV
3
4
44
NW-2B
None
None
123-91-1
1,4-Dioxane
HRL
1
53
5,600
NW-1AR
32
390
W-10B
66
330
B2
100-41-4
Ethylbenzene
HBV
40
17
4,900
NW-2B
1
550
W-11A
1
44
B2
78-93-3
Methyl ethyl ketone
HRL
4000
6
97,000
NW-3AR
None
None
10-01-0108
Methyl isobutyl ketone
HRL
300
6
11,000
NW-3AR
None
None
75-09-2
Methylene chloride
MCL
5
12
51,000
NW-2B
None
None
109-99-9
Tetrahydrofuran
HRL
600
6
14,000
NW-2B
None
None
79-34-5
1,1,2,2-Tetrachloroethane
HRL
2
1
2.4
NW-1AR
None
None
127-18-4
T etrachloroethene
HBV
4
10
4,400
NW-1AR
None
None
108-88-3
Toluene
HBV
70
10
39,000
NW-2B
None
None
108-67-8
1,3,5-Trimethy lbenzene
HBV
30
2
56
NW-2B
None
None
79-00-5
1,1,2-T richloroethane
HRL
3
8
81
NW-2B
None
None
79-01-6
Trichloroethene
HRL
0.4
13
4,700
NW-1AR
None
1
0.53
W-7
95-63-6
1,2,4-Trimethy lbenzene
HBV
30
13
250
NW-2B
1
38
W-11A
None
71-55-6
1,1,1 -T richloroethane
MCL
200
8
42,000
NW-2B
None
None
75-01-4
Vinyl chloride
HRL
0.2
28
10,000
NW-2B
18
95
W-11A
30
7.3
W-2A
1 In-waste wells, as determined from their location depicted on Figure D-l, include: NW-1A, NW-1AR, NW-1B, NW-1BR, NW-1C, NW-1CR, NW-2A, NW-2AR, NW-2B, NW-2BR, NW-2C, NW-2CR, NW-3A,
NW-3AR, NW-3B, NW-3BR, NW-3C, NW-3CR, NW-4A, NW-4AR, NW-4B, NW-4BR, NW-4C, NW-4CR, W-22A, W-32A, W-32B.
2 Edge of waste wells, as determined from their location depicted on Figure D-l, include: PZ-1, PZ-2, PZ-4, W-10A, W-10B, W-l 1 A, W-l IB, W-l 1C, W-l ID, W-25A, W-34D, W-38B.
3 Wells outside the waste, as determined from their location depicted on Figure D-l, include: Al, A2, A3, Bl, B2, B3, PZ-5, W-12A, W-12B, W-12C, W-13A, W-13B, W-15C, W-15D, W-16, W-17, W-19, W-l A,
W-1C, W-21A, W-21B, W-23E, W-26A, W-26B, W-26D, W-2A, W-2B, W-3, W-39A, W-39B, W-4, W-7.
D-2
-------
Table D-2: PFAS Organic Chemical Action Level Exceedances in Monitoring Wells and Piezometers within the Waste, at Waste Boundary, and Outside of Waste,
2018-2022
Action
Level
Source
Action
Level,
Ug/L
In waste1
Edge of waste2
Outside waste3
CAS No.
Chemical
#
Exceedances
Maximum
Exceedance,
Ug/L
Location of
Maximum
Exceedance
#
Exceedances
Maximum
Exceedance,
Ug/L
Location of
Maximum
Exceedance
#
Exceedances
Maximum
Exceedance,
Ug/L
Location of
Maximum
Exceedance
108427-
53-8
Perfluorohexanesulfonate
HBV
0.047
15
0.39
NW-1B
1
550
W-11A
9
0.17
B2
307-24-4
Perfluorohexanoic acid
HBV
0.2
13
2
NW-4B
4
0.61
W-11A
9
0.52
B2
335-67-1
Perfluorooctanoic acid
HRL
0.035
27
6.9
W-32A
14
1.8
W-11A
57
1.4
B2
45298-90-
6
Perfluorooctane
sulfonate
HBV
0.015
17
0.74
W-32A
1
0.021
W-11A
8
0.071
B2
Table D-3: Inorganic Chemical Action Level Exceedances in Monitoring Wells and Piezometers within the Waste, at Waste Boundary, and Outside of Waste, 2018-
2022
Action
Level
Source
Action
Level,
fig/L
In waste1
Edge of waste
2
Outside waste3
CAS No.
Chemical
#
Exceedances
Maximum
Exceedance,
Ug/L
Location of
Maximum
Exceedance
#
Exceedances
Maximum
Exceedance,
Ug/L
Location of
Maximum
Exceedance
#
Exceedances
Maximum
Exceedance,
Ug/L
Location of
Maximum
Exceedance
7439-96-5
Manganese, dissolved
HRL
100
13
2,890
NW-2B
16
1,980
W-10B
70
3,480
W-26A
7440-38-2
Arsenic, dissolved
MCL
10
14
32.5
NW-3C
10
23.5
W-11B
17
48.5
W-2A
D-3
-------
Table D-4: PFAS Chemical Concentrations in Domestic Wells, 2018-2022 (Action Level Exceedances Indicated in Red)
CAS No.
PFAS Chemical
Number
of Wells
Sampled
Number of
Samples
Collected
Number
of
Detections
Maximum
detection,
jig/L
Minimum
detection,
jig/L
Action
Level
Source
Action
Level,
jig/L
Tapwater
RSL,
HI=1,
jig/L
108427-53-8
Perfluorohexanesulfonate (PFHxS)
156
274
104
0.28
0.00058
HBV
0.047
0.39
113507-82-7
Perfluoro(2-ethoxyethane)sulfonic acid (PFEESA)
145
226
0
NA
NA
NA
NA
NA
13252-13-6
Hexafluoropropylene oxide dimer acid (HFPO-DA)
145
226
0
NA
NA
NA
NA
0.06
151772-58-6
Nonafluoro-3,6-dioxaheptanoic acid (NFDHA)
145
226
0
NA
NA
NA
NA
NA
2058-94-8
Perfluoroundecanoic acid (PFUnA)
145
226
2
0.001
0.00087
NA
NA
NA
2706-90-3
Perfluoropentanoic acid (PFPeA)
156
274
143
0.016
0.00076
NA
NA
NA
2706-91-4
Perfluoropentasulfonate (PFPeS)
145
226
55
0.073
0.00084
NA
NA
NA
27619-97-2
lH,lH,2H,2H-Perfluorooctane sulfonic acid (6:2FTS)
145
226
1
0.0019
0.0019
NA
NA
NA
2991-50-6
N-ethyl perfluorooctanesulfonamidoacetic (NEtFOSAA)
145
226
0
NA
NA
NA
NA
NA
307-24-4
Perfluorohexanoic acid (PFHxA)
156
274
101
0.022
0.00076
HBV
0.2
NA
307-55-1
Perfluorododecanoic acid (PFDoA)
145
226
1
0.00098
0.00098
NA
NA
NA
335-67-1
Perfluorooctanoic acid (PFOA)
156
274
103
0.017
0.00049
HRL
0.035
0.06
335-76-2
Perfluorodecanoic acid (PFDA)
145
226
0
NA
NA
NA
NA
NA
375-22-4
Perfluorobutanoic acid (PFBA)
156
274
247
0.083
0.00096
HRL
7
NA
375-85-9
Perfluoroheptanoic acid (PFHpA)
145
226
25
0.0066
0.00083
NA
NA
NA
375-92-8
Perfluoroheptasulfonate (PFHpS)
145
226
2
0.012
0.0011
NA
NA
NA
375-95-1
Perfluorononanoic acid (PFNA)
145
226
0
NA
NA
NA
NA
0.059
377-73-1
Perfluoro-3-methoxypropanoic acid (PFMPA)
145
226
0
NA
NA
NA
NA
NA
39108-34-4
lH,lH,2H,2H-Perfluorodecane sulfonic acid (8:2FTS)
145
226
0
NA
NA
NA
NA
NA
45187-15-3
Perfluorobutanesulfonate (PFBS)
156
274
116
0.055
0.00081
HBV
0.1
6
45298-90-6
Perfluorooctane sulfonate
156
274
22
0.065
0.00067
HBV
0.015
0.04
756426-58-1
9-Chlorohexadecafluoro-3-oxanonane-l-s(9Cl-PF30NS)
145
226
0
NA
NA
NA
NA
NA
757124-72-4
lH,lH,2H,2H-Perfluorohexane sulfonic acid (4:2FTS)
145
226
0
NA
NA
NA
NA
NA
763051-92-9
1 l-Chloroeicosafluoro-3-oxaundecane (1 lCl-PF30UdS)
145
226
1
0.00074
0.00074
NA
NA
NA
863090-89-5
Perfluoro-4-methoxybutanoic acid (PFMBA)
145
226
0
NA
NA
NA
NA
NA
919005-14-4
4,8-Dioxa-3H-perfluorononanoic acid (ADONA)
145
226
0
NA
NA
NA
NA
NA
D-4
-------
Table D-5: PFAS Chemicals with Regional Screening Levels but no Groundwater Monitoring Data or Action Levels
CAS No.
PFAS Chemical
Action
Level
Source
Action Level,
JLig/L
Tapwater RSL,
HI=1, fig/L
1763-23-01
Perfluorooctanesulfonic acid (PFOS)
NA
NA
0.04
2795-39-3
Potassium perfluorooctanesulfonate
NA
NA
0.04
29420-49-3
Potassium perfluorobutanesulfonate
NA
NA
6
355-46-4
Perfluorohexanesulfonic acid (PFHxS)
NA
NA
0.39
375-73-5
Perfluorobutanesulfonic acid (PFBS)
NA
NA
6
45285-51-6
Perfluorooctanoate
NA
NA
0.06
62037-80-3
Ammonium perfluoro-2-methyl-3-oxahexanoate
NA
NA
0.06
72007-68-2
Perfluorononanoate
NA
NA
0.059
Table D-6: Concentrations of Non-PFAS Chemicals with Action Levels in Domestic Wells, 2018-2022 (Action Level
Exceedances in Red)
CAS No.
Chemical
# of
Wells
Sampled
# of
Samples
# of
Detections
Maximum
Detection,
fig/L
# of
Detections
Above
Action
Level
# Wells
with
Action
Level
Exceedence
Action
Level
Source
Action
Level,
fig/L
Tapwater
RSL, HI=1
& ELCR=
10 4, jig/L
123-91-1
1,4-Dioxane
158
278
203
2200
45
42
HRL
1
45.9
71-43-2
Benzene
157
244
3
0.71
0
0
HRL
2
33.2
74-87-3
Chloromethane
157
244
1
1.4
0
0
NA
NA
188
75-34-3
1,1 -Dichloroethane
157
244
1
0.51
0
0
RAA
80
275
75-71-8
Dichlorodifluoromethane
157
244
3
5.5
0
0
RAA
500
197
79-01-6
Trichloroethene (TCE)
157
244
1
0.12
0
0
HRL
0.4
2.83
7440-38-2
Arsenic, Dissolved
2
2
1
3.19
0
0
MCL
10
5.17
7439-96-5
Manganese, Dissolved
2
2
1
59.9
0
0
HRL
100
432
D-5
------- |