THIRD FIVE-YEAR REVIEW REPORT FOR
PARKER LANDFILL SUPERFUND SITE
TOWN OF LYNDON
CALEDONIA COUNTY, VERMONT
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Prepared by
U.S. Environmental Protection Agency
Region 1
Boston, Massachusetts
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Ja1 les T. Owens, III, Director Date
SDMS Doc ID 567594
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TABLE OF CONTENTS
EXECUTIVE SUMMARY 6
I. INTRODUCTION 11
II. PROGRESS SINCE THE LAST REVIEW 11
A. Remedy Implementation Activities 13
B. System Operation/Operation and Maintenance Activities 13
III. FIVE-YEAR REVIEW PROCESS 14
Administrative Components 14
Review of Site-Related Background Documents 15
Review of Site Monitoring Data 15
Review of ARARs and Other Standards 30
Inspection of the Site 33
Interviews with Key Stakeholders 35
IV. TECHNICAL ASSESSMENT 37
Question A: Is the remedy functioning as intended by the decision documents?
37
Question B: ...Are the exposure assumptions, toxicity data, cleanup levels, and remedial action
objectives (RAOs) used at the time of the remedy section still valid? 39
Question C: Has any other information come to light that could call into question the
protectiveness of the remedy? 48
Technical Assessment Summary 48
V. ISSUES / RECOMMENDATIONS AND FOLLOW-UP ACTIONS 50
VI. PROTECTIVENESS STATEMENT 51
VII. NEXT REVIEW 51
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TABLES
Table 1 Protectiveness Determinations/Statements from the 2009 FYR
Table 2 Status of Recommendations from the 2009 FYR
Table 3 Comparison of Unnamed Stream Sediment COC Results from 2009-2013 to
Sediment Results from 2001-2004, 2005-2008 and Remedial Investigation
Table 4 Comparison of Unnamed Stream Surface Water COC Results from 2009-2013 to
Surface Water Results from 2001-2004, 2005-2008 and Remedial Investigation
Table 5 Maximum Concentrations of Groundwater Contaminants that Exceeded IGCLs in
October 2013
Table 6 Water Quality Standards Revised or Developed since 1995 ROD
Table 7 Comparison of IGCLs with Current MCLs and/or VPGQS
Table 8 Comparison of 2009-2013 Maximum Sediment Concentrations to Human Health
Screening Levels
Table 9 Comparison of 2009-2013 Maximum Surface Water Concentrations to Human
Health Screening Levels
Table 10 Comparison of Shallow Overburden Groundwater Concentrations to Vapor
Intrusion Screening Levels
Table 11 Issues and Recommendations/Follow-up Actions
FIGURES
Figure 1 Site Locus
Figure 2 Site Plan and Monitoring Locations
Figure 3 Exceedances of IGCLs for VOCs and SVOCs in Groundwater (2013)
Figure 4 Approximate Buffer Zone of Institutional Controls based on Groundwater
Reclassification
Figure 5 Gas Probe Monitoring for GP-34 Cluster (November 2006 to November 2013)
APPENDICES
Appendix A Existing Site Information
Appendix B Copy of Findings of Fact & Reclassification Order
Appendix C Table of Maximum Concentrations of Groundwater Contaminants that Exceeded
IGCLs (2009 through 2014)
Appendix D Representative Data Plots
Appendix E Interview Documentation
Appendix F Current Toxicity Criteria and Vapor Intrusion Screening Levels for Groundwater
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LIST OF ACRONYMS
ADAF
Age-Dependent Adjustment Factor
ARAR
Applicable or Relevant and Appropriate Requirement
BNA
Bio-Enhanced Natural Attenuation
CERCLA
Comprehensive Environmental Response, Compensation, and Liability Act
CFR
Code of Federal Regulations
CIC
Community Involvement Coordinator
Cis-1,2-DCE
cis-l,2-Dichloroethene
COC
Contaminant of Concern
COPC
Contaminant of Potential Concern
CSM
Conceptual Site Model
CV
Coefficient of Variation
EPA
United States Environmental Protection Agency
ESD
Explanation of Significant Differences
EVO
Emulsified Vegetable Oil
FYR
Five-Year Review
ICs
Institutional Controls
IGCL
Interim Groundwater Cleanup Levels
IRIS
Integrated Risk Information System
IWS
Industrial Waste Site
LEL
Lower Explosive Limit
LTMP
Long-Term Monitoring Plan
MCL
Maximum Contaminant Level
MCLG
Maximum Contaminant Level Goal
MEK
2-Butanone
MNA
Monitored Natural Attenuation
MOM
Management of Migration
NCP
National Contingency Plan
NESHAP
National Emission Standards for Hazardous Air Pollutants
NPDES
National Pollutant Discharge Elimination System
NPL
National Priorities List
O&M
Operation and Maintenance
OU
Operable Unit
PCE
T etrachl oroethene
PRB
Permeable Reactive Barrier
PRP
Potentially Responsible Party
PVC
Polyvinyl Chloride
RAO
Remedial Action Objectives
RCRA
Resource Conservation & Recovery Act
RI
Remedial Investigation
ROD
Record of Decision
RSL
Regional Screening Level
SMCL
Secondary Maximum Contaminant Levels
SVOC
Semi-Volatile Organic Compound
SWDA
Solid Waste Disposal Area
TAL
Target Analyte List
1,1,1-TCA
1,1,1 -Trichloroethane
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LIST OF ACRONYMS (cont.)
TCE
Trans-1,2
UIC
VFA
VI
VISL
VOC
VPGQS
VTAEC
VTDEC
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Trichloroethene
-DCE Trans-l,2-Dichloroethene
Underground Injection Control
Volatile Fatty Acid
Vapor Intrusion
Vapor Intrusion Screening Level
Volatile Organic Compound
Vermont Primary Groundwater Quality Standards
Vermont Agency of Environmental Conservation
Vermont Department of Environmental Conservation
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EXECUTIVE SUMMARY
This is the third Five-Year Review (FYR) for the Parker Landfill Superfund Site, located in the
Town of Lyndon, Caledonia County, Vermont. The purpose of this FYR is to review information
to determine if the remedy is and will continue to be protective of human health and the
environment. The triggering action for this statutory FYR was the signing of the previous FYR
on September 30, 2009.
The remedy selected to address contamination at the Parker Landfill Superfund Site includes a
multi-layer cap over the Solid Waste Disposal Area (SWDA) and Industrial Waste Site (IWS)
areas, active gas collection on the SWDA and IWS-1, a Permeable Reactive Barrier (PRB)
downgradient of IWS-3, bio-enhanced natural attenuation (BNA) of the downgradient aquifer,
and institutional controls.
Section X of the April 7, 1995 Record of Decision (ROD) describes the original remedy for the
Site, which included the following components:
Construction of multi-layer (RCRA subtitle C) caps over the SWDA and three IWS areas
to minimize the potential for transfer of contaminants from the soil and waste into the
groundwater, surface water and sediments;
Installation and operation of a gas collection system in the SWDA and IWS-1 area to
reduce landfill gas accumulation and lateral migration below the solid waste landfill cap;
Installation of a source control groundwater treatment system to address overburden and
bedrock contamination, the configuration of which was to be determined during pre-
design studies of Site groundwater;
Conduct long-term sampling and analysis of groundwater, surface water and sediments to
assess compliance with the groundwater cleanup levels through natural attenuation and to
ensure surface water and sediments in nearby brooks/river have not been adversely
impacted;
Institutional controls to protect the cap, and to restrict groundwater use, including the
extension of municipal water service to all homes potentially affected by contamination;
and
Review of the Site every five years to evaluate the effectiveness of the remedy.
An Explanation of Significant Differences (ESD) was issued in July 2004 detailing a change in
the original groundwater remedy. As stated above, the original groundwater remedy specified in
the ROD included a source control groundwater treatment system (extraction and ex-situ
treatment) and natural attenuation of the downgradient groundwater contamination plume. The
ESD specified that a PRB system would be designed and installed to treat source area
groundwater and BNA would be used to treat downgradient groundwater contamination.
The capping of the landfill was initiated in April 1999. The PRB and BNA systems were
completed in September 2005.
A new wetland area was created during 2000 as a mitigation measure to compensate for wetlands
destroyed during the capping of the landfill. In 2005 and 2006, the compensatory wetland was
expanded to mitigate for wetlands destroyed during installation of the PRB and BNA systems.
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The remedy at the Parker Landfill Superfund Site currently protects human health and the
environment because there is no current use of or exposure to Site media containing contaminant
concentrations exceeding applicable criteria. However, in order for the remedy to be protective
in the long-term, the following actions need to be taken:
Expand the institutional control area to ensure that the boundary encompasses the current
contaminant plume pursuant to the ROD;
Monitor VOC concentration trends in groundwater, surface water and sediments.. Install
groundwater monitoring wells to ensure the plume is within IC control areas as well as to
determine the nature and extent of the contamination.;
Evaluate, monitor and define the extent of 1,4-dioxane in the groundwater;
Evaluate VOCs in groundwater in the vicinity of occupied buildings against appropriate
vapor intrusion screening criteria; and
Evaluate and repair landfill cap settlement in the vicinity of GW-4.
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Five-Year Review Summary Form
SITE IDENTIFICATION
Site Name: Parker Landfill Superfund Site
EPA ID: VTD981062441
Region: 1
State: VT
City/County: Lyndon / Caledonia
NPL Status: Final
Multiple OUs?
No
Has the site achieved construction completion?
Yes
Lead agency: EPA
[If "Other Federal Agency", enter Agency name]: Not Applicable
Author name (Federal or State Project Manager): Leslie McVickar
Author affiliation: US Environmental Protection Agency
Review period: 1/08/14-9/30/2014
Date of site inspection: 5/8/2014
Type of review: Statutory
Review number: 3
Triggering action date: 9/30/2009
Due date (fiveyears after triggering action date): 9/30/2014
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Issues/Recommendations
Issues and Recommendations Identified in (lie l-ive-Year Review:
OU1
Issue Category: Institutional Controls
Issue: Institutional controls need to be expanded to ensure the Site
boundary encompasses the current contaminant plume.
Recommendation: Finalize institutional controls for the Site.
Affect Current
Protectiveness
Affect Future
Protectiveness
Party
Responsible
Oversight
Party
Milestone Date
No
Yes
PRP
EPA / VTDEC
12/31/2016
OU1
Issue Category: Monitoring
Issue: Recent data indicates that conditions have changed in the
groundwater west of the SWDA.
Recommendation: Implement an investigation to evaluate and determine
the current nature and extent of the VOC plume.
Affect Current
Protectiveness
Affect Future
Protectiveness
Party
Responsible
Oversight
Party
Milestone Date
No
Yes
PRP
EPA / VTDEC
12/31/2015
OU1
Issue Category: Monitoring
Issue: Extent of 1,4-dioxane plume needs to be determined and further
monitored.
Recommendation: Continue to monitor and define the extent of 1,4-
dioxane in groundwater to ensure the plume is within the areas of
established institutional control areas.
Affect Current
Protectiveness
Affect Future
Protectiveness
Party
Responsible
Oversight
Party
Milestone Date
No
Yes
PRP
EPA / VTDEC
12/31/15
OU1
Issue Category: Monitoring
Issue: Annual vapor intrusion evaluations must be performed.
Recommendation: Annually evaluate all groundwater VOC data,
particularly in the vicinity of occupied buildings, against appropriate vapor
intrusion screening criteria.
Affect Current
Protectiveness
Affect Future
Protectiveness
Party
Responsible
Oversight
Party
Milestone Date
No
Yes
PRP
EPA / VTDEC
Ongoing
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OU1
Issue Category: Operations and Maintenance
Issue: Localized landfill cap settlement.
Recommendation: Evaluate and repair settlement in the vicinity of GW-4.
Affect Current
Protectiveness
Affect Future
Protectiveness
Party
Responsible
Oversight
Party
Milestone Date
No
Yes
PRP
EPA / VTDEC
12/31/2014
Sitewide Protectiveness Statement
Protectiveness Determination:
Short-term Protective
Protectiveness Statement:
The remedy at the Parker Landfill Superfund Site currently protects human health and the
environment because there is no current use of or exposure to site media containing contaminant
concentrations exceeding applicable criteria. However, in order for the remedy to be protective
in the long-term, institutional controls must be expanded and contaminant concentrations and
trends (i.e., VOCs and 1,4-dioxane) must continue to be monitored and evaluated. Groundwater
plume migration west of the landfill needs to be investigated and evaluated to determine the
current nature and extent of groundwater contamination at the Site. Landfill repairs are
necessary to address an area of settlement at location GW-4. All groundwater data must be
evaluated for future potential vapor intrusion issues.
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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 will continue to be protective of human health and the
environment. The methods, findings, and conclusions of reviews are documented in FYR reports. In
addition, FYR reports identify issues found during the review, if any, and document recommendations to
address them.
The U.S. Environmental Protection Agency (EPA) prepares FYRs pursuant to the Comprehensive
Environmental Response, Compensation, and Liability Act (CERCLA) Section 121 and the National
Contingency Plan (NCP). CERCLA Section 121 states:
"If the President selects a remedial action that results in any hazardous substances, pollutants,
or contaminants remaining at the site, the President shall review such remedial action no less
often than each five years after the initiation of such remedial action to assure that human health
and the environment are being protected by the remedial action being implemented. In addition,
if upon such review it is the judgment of the President that action is appropriate at such site in
accordance with section [104] or [106], the President shall take or require such action. The
President shall report to the Congress a list offacilities for which such review is required, the
results of all such reviews, and any actions taken as a result of such reviews. "
EPA interpreted this requirement further in the NCP; 40 Code of Federal Regulations (CFR) Section
300.430(f)(4)(ii), which states:
"If a remedial action is selected that results in hazardous substances, pollutants, or
contaminants remaining at the site above levels that allow for unlimited use and unrestricted
exposure, the lead agency shall review such actions no less often than every five years after the
initiation of the selected remedial action."
EPA conducted this FYR on the remedy implemented at the Parker Landfill Superfund Site (Site) in the
Town of Lyndon, Caledonia County, Vermont. Figure 1 shows the location of the Parker Landfill
Superfund Site. EPA is the lead agency for developing and implementing the remedy for the Site.
Vermont Department of Environmental Conservation (VTDEC), as the support agency representing the
State of Vermont, has reviewed all supporting documentation and provided input to EPA during the
FYR process.
This is the third FYR for the Site. The triggering action for this statutory review is signature of the last
FYR on September 30, 2009. This FYR is required due to the fact that hazardous substances, pollutants,
or contaminants remain at the Site above levels that allow for unlimited use and unrestricted exposure.
II. PROGRESS SINCE THE LAST REVIEW
The following provides the protectiveness determination and a list of the recommendations presented in
the 2009 FYR for the Site.
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Table 1
Protectiveness Determinations/Statements from the 2009 FYR
ou#
Protectiveness
Determination
Protectiveness Statement
Sitewide
Short-term Protective
The remedy at the Parker Landfill Site currently protects human health
and the environment because there is no current use of or exposure to
Site media containing contaminant concentrations exceeding
applicable criteria. However, in order for the remedy to be protective
in the long-term, institutional controls must be finalized.
Table 2
Status of Recommendations from the 2009 FYR
OU#
Issue
Recommendations
Follow-up Actions
Party
Responsible
Oversight
Party
Original
Milestone
Date
Current
Status
Completion
Date (if
applicable)
OU1
Institutional
Controls
Finalization of
institutional
controls for the
Site, ensuring that
the institutional
control boundary
encompasses wells
with IGCL
exceedances.
Other
EPA/State
September
2010
Ongoing
Institutional
controls have
been
established
consistent with
the August
2003
Groundwater
Reclassification
; however
current Site
conditions may
warrant
expansion of
the Institutional
Control area.
OU1
Updated
VPGQS
and/or MCL
for Acetone
and Arsenic
Evaluate need to
update IGCL and
consider effects on
treatment
technologies.
PRP
EPA/State
September
2011
Completed
Though IGCLs
have not been
formally
changed by
EPA, the
updated
VPGQS and
MCLs were
incorporated as
comparison
criteria in the
2009 long-term
monitoring plan
report.
OU1
1,4-Dioxane
Continue to
monitor and define
the extent of 1,4-
dioxane to ensure
the plume is within
the groundwater.
PRP
EPA/State
September
2013
Ongoing
N/A
OU1
Vapor
Intrusion
Continue to
evaluate VOCs in
PRP
EPA/State
September
2013
Ongoing
N/A
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Table 2
Status of Recommendations from the 2009 FYR
ou#
Issue
Recommendations
Follow-up Actions
Party
Responsible
Oversight
Party
Original
Milestone
Date
Current
Status
Completion
Date (if
applicable)
groundwater
against appropriate
federal and state
vapor intrusion
guidance and
criteria.
IGCL - Interim Groundwater Cleanup Level
MCL - Maximum Contaminant Level
PRP - Potentially Responsible Party
VOCs - Volatile Organic Compounds
VPGQS - Vermont Primary Groundwater Quality Standards
Further explanation regarding the status/completion date of Recommendation #1 from the 2009 FYR is
provided below and in the following sections.
Recommendation 1
The Town of Lyndon updated their zoning bylaws to establish an Institutional Control Area that
mirrors the Groundwater Reclassification Area as shown in Attachment B of the Findings of
Fact and Reclassification Order, Proposed Groundwater Reclassification at the Parker Landfill,
Lyndon, Vermont dated August 21, 2003 (see Appendix B). The Groundwater Reclassification
Area was delineated based on data collected in 2000; however downgradient Interim
Groundwater Cleanup Level (IGCL) exceedances and increasing VOC concentration trends,
including 1,4-dioxane and particularly in the "top-of-rock" groundwater system, continue to be
evident west-southwest of the Solid Waste Disposal Area (SWDA), including near Lily Pond
Road and potentially beyond (i.e., toward the Passumpsic River). The current data suggest a need
for additional monitoring locations and/or installation of additional wells downgradient of the
Site. As a result, the limits of the current institutional controls do not encompass the area of
recent IGCL exceedances as required by the Record of Decision (ROD).
A. Remedy Implementation Activities
No remedial implementation activities, other than the institutional controls (ICs) noted above by the Town
of Lyndon, have occurred since the previous FYR. A summary of remedial implementation activities
previously completed at the Site is included in Appendix A.
B. System Operation/Operation and Maintenance Activities
Operation and maintenance (O&M), including monitoring of select media, are conducted for both the
landfill cap and groundwater remedies, as further described below. Monitoring activities are currently
conducted in accordance with the Updated Draft Final Long-Term Monitoring Plan and associated
Addenda #1 and #2, Permeable Reactive Barrier (PRB) Remedial Design Report and Revised Draft Bio-
Enhanced Natural Attenuation (BNA) O&M Plan.
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Landfill Cay Remedy O&M
O&M for the cap remedy primarily consists of operating the flare system to burn collected methane gas
and maintenance of the cap. Maintenance of the cap includes mowing, cleaning out drainage swales,
repairing erosion damage, replanting grass (as needed) and removing animals that burrowed in the cap.
Periodic gas probe monitoring is also conducted to monitor the migration of methane gas from areas
outside of the cap.
Groundwater Remedy O&M
O&M for the groundwater remedies primarily consists of groundwater, surface water, and sediment
monitoring. Groundwater monitoring wells are grouped into the Management of Migration (MOM),
PRB and BNA monitoring well groups. Annual groundwater monitoring of 32 MOM wells, 29 PRB
wells, and eight BNA wells is currently conducted.1 Every five years, as part of the FYR, an additional
28 MOM wells are also monitored.
Surface water sampling is conducted on an annual basis. Three surface water samples are collected from
the unnamed stream extending along the eastern portion of the SWDA. In addition, sediment sampling is
currently conducted every five years, as part of the FYR, with samples collected from three locations
from the unnamed stream.
III. FIVE-YEAR REVIEW PROCESS
Administrative Components
The Parker Landfill Superfund Site FYR was led by Leslie McVickar of the EPA, Remedial Project
Manager for the Site and Emily Zimmerman, the Community Involvement Coordinator (CIC). John
Schmeltzer, Project Manager for the VTDEC, assisted in the review as the representative for the support
agency.
The review, which began on 1/8/2014, consisted of the following components: review of Site-related
background documents, review of Site monitoring data, review of Applicable or Relevant and
Appropriate Requirements (ARARs) and other standards, inspection of the Site, interviews with key
stakeholders and development of this FYR report.
Community Notification and Involvement
Activities to involve the community in the FYR process were initiated with a news release dated
February 13, 2014 from EPA stating that a FYR of the Site would be conducted. The results of this
FYR report will be made available at the Site information repository located at the Cobleigh Public
Library in Lyndon and at EPA's Records Center located in Boston, Massachusetts.
1 Per the findings of the Five-Year Review Long-Term Monitoring Plan report issued in 2008, four wells (B119C, B126S,
B144A and B201OW) that were previously sampled every five years have been added to the annual monitoring events.
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Review of Site-Related Background Documents
This FYR consisted of a review of documents relevant to the history and status of the Site. The document
review including the following: decision documents including the ROD and Explanation of Significant
Differences (ESD), the previous (2009) FYR report, an updated long-term monitoring plan, long-term
monitoring plan reports (2009 through 2013), the Town of Lyndon's zoning ordinances, institutional
controls documentation, Site inspection reports, and O&M documents and records during the past five
years. Applicable groundwater and sediment cleanup standards, as listed in the April 1995 ROD, were
also reviewed.
Review of Site Monitoring Data
Figure 2 shows the locations of sediment samples, surface water samples, and groundwater monitoring
wells included in the LTMP. A long-term monitoring program is being implemented as required by the
ROD and ESD. Based on the results of the Remedial Investigation (RI), contaminants associated with
the Site were present in soil (mainly below the waste areas), landfill gas, sediment, surface water and
groundwater. The ROD (dated April 1995), original LTMP (dated August 2000) and the Updated Draft
Final LTMP (dated September 8, 2006) specified on-going monitoring requirements for sediment,
surface water, and groundwater at the Site.
The results of a review of available data from the past five years are presented below. These data were
used to determine if any significant changes in Site conditions have occurred within the past five years.
Sediments
As part of long-term monitoring activities required by the ROD, sampling and analysis of sediments was
performed once in the past five years at three locations (SD01, SD02, and SD03) in the unnamed stream
(Figure 2). Sediment samples were collected on October 4, 2013. Samples at each location were
analyzed for VOCs and target analyte list (TAL) metals.
Historically, long-term sediment monitoring data indicate that the concentrations of VOCs and metals
were generally highest in the "upstream" samples collected from SD01 and decreased with distance
downstream. Although no VOCs were detected in the sediment samples collected in October 2013, this
trend generally held true during the most recent monitoring event for metals. Table 3 presents a
comparison of maximum concentrations detected in the long-term monitoring samples collected in the
unnamed stream to the project-specific sediment quality guidelines for Contaminants of Concern
(COCs) established for the Site in the 1993 Final Risk Assessment.
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Table 3
Comparison of Unnamed Stream Sediment COC Results from 2009-2013 To Sediment
Results from 2001-2004, 2005-2008 and Remedial Investigation
Parker Landfill Superfund Site
1
Unnamed Stream
Parameter (COC)
Sediment
Quality
Criteria
RI
Maximum
Concentration
2001-2004
Maximum
Concentration
2005-2008
Maximum
Concentration
2009-2013
Maximum
Concentration
VOCs (mg/kg)
Acetone
0.17
0.24
0.91 J
0.31
ND
2-Butanone
0.91
0.0815
0.16
0.0177 J
ND
Chloroethane
0.59
0.01
ND
ND
ND
Chloroform
0.08
0.0054
ND
ND
ND
Trichloroethene
5.8
0.0054
0.12
0.00144 J
ND
SVOCs (mg/kg)
Bis(2-
ethylhexyl)phthalate
6.2
0.3279
NA
ND
NA
Inorganics (mg/kg)(1)
Arsenic
33
962.3
4.2
2.48 J
ND
Barium
20
809.5
125
no
28.2
Cadmium
5
10.5
1.4
0.462 J
ND
Copper
70
20.7
14.2
13
4.22
Cyanide
0.1
22.6
NA
NA
NA
Iron
17,000
383.000
29.000
25.000
10,800
Manganese
300
2.425
10,400
2.390
220
Nickel
30
24.8
22.4
17.9
3.92
(1) Only COCs with established Sediment Quality Criteria listed. Additional ROD-specified inorganic COCs associated with the unnamed stream include:
aluminum, calcium, chromium, cobalt, lead, magnesium, potassium, vanadium and zinc.
Concentrations in milligrams per kilogram (mg/kg).
Sediment Quality Criteria (mg/kg) are from 1993 Final Risk Assessment by TRC.
RI - 1990-1994 Remedial Investigation by ESE. (Maximum concentration is taken from results for 11 sediment samples on unnamed stream or 4 sediment
samples on Passumpsic River.)
LTM - Long-Term Monitoring activities; conducted semi-annually from October 2001 to April 2004
NA - Not analyzed for given parameter.
ND - Not detected in excess of laboratory reporting limit.
HQ] shading indicates result exceeds given sediment quality criteria.
Bold type indicates maximum concentration has increased since the previous reporting period.
J - Estimated
Table 3 indicates an overall decrease in the concentrations of VOCs within the sediments relative to
concentrations detected during the RI. The reduction in VOC concentrations indicates that the remedy is
successfully minimizing the transfer of VOC contamination from the SWDA and IWS area soil and
waste materials into the sediments.
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In October 2013, barium at the SD01 location was the only metal detected in excess of the sediment
quality criteria. This represents a decrease, particularly for iron and manganese, in the number of metal
exceedances of the sediment quality criteria since the September 2008 sampling event.
Surface Water
Surface water sampling along the unnamed stream was performed at three locations on an annual basis
from April 2004 to the present. The locations of stream surface water samples (SW01, SW02, and
SW03) were co-located with the sediment sample locations (SD01, SD02, and SD03).
Table 4 presents the comparison of maximum concentrations detected in the long-term monitoring
samples collected within the unnamed stream to benchmark criteria and maximum concentrations of
COCs detected during the RI. The benchmark criteria are not cleanup goals but were established using
available criteria and guidelines for evaluating chemical toxicity to ecological receptors According to
the ROD, all risk values for exposure to surface water were within or below EPA's acceptable risk
range.
As shown in Table 4, there was an increase in the maximum concentrations of TCE, vinyl chloride, 1,2-
dichloroethene, aluminum, chromium, iron, magnesium, manganese and thallium in the 2001-2004 data
from the ROD levels. However, the 2005-2008 and 2009-2013 maximum concentrations are similar to,
and in most cases lower than, the maximum RI concentrations and therefore, surface water
concentrations are not considered to present an adverse impact.
Table 4
Comparison of Unnamed Stream Surface Water COC Results from 2009-2013
To
Surface Water Results from 2001-2004, 2005-2008 and Remedial Investigation
Parker Landfill Superfund Site
1
Unnamed Stream |
Parameter (COC)
Surface Water
Criteria or
Guidelines
RI
Maximum
Concentration
2001-2004
Maximum
Concentration
2005-2008
Maximum
Concentration
2009-2013
Maximum
Concentration
| VOCs (ug/L) |
Acetone
61,000
15
10
ND
7.03 J
Trichloroethene
21,900
21
920
50
30.6 J
Vinyl Chloride
17,800
1
5.2
0.513 J
0.359 J
cis-1,2-Dichloroethene
11,600
42
350
17.8
25.3 J
trans-1,2-Dichloroethene
11,600
42
2.4
ND
0.277 J
Inorganics (ug/L)
Aluminum
87
116
34,100
199
3,320
Antimony
80
56.5
7.9
ND
ND
Barium
220
291.5
258
31.7
112
Cadmium(1)
0.24
NS
0.8
NA/ND
ND
Calcium
NP
79,400
36,700
59,700
73,200
Chromium
75.4
11.2
52.3
ND
ND
Cobalt(1)
24
NS
19.9
13.4
3.22 J
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Table 4
Comparison of Unnamed Stream Surface Water COC Results from 2009-2013
To
Surface Water Results from 2001-2004, 2005-2008 and Remedial Investigation
Parker Landfill Superfund Site
1
Unnamed Stream |
Parameter (COC)
Surface Water
Criteria or
Guidelines
RI
Maximum
Concentration
2001-2004
Maximum
Concentration
2005-2008
Maximum
Concentration
2009-2013
Maximum
Concentration
Iron
1,000
33,750
945
16,100
Lead(1)
2.69
NS
61.4
13.4
13.3
Magnesium
NP
9,375
11,300
6,050
7,060
Manganese
NP
3,350
6,990
249
2,060
Nickel
45.5
38.8
32.3
ND
ND
Potassium
NP
10,040
4,780
3,060
3,920
Selenium(1)
5
NS
8.3
ND
ND
Silver
2.86
14.4
4.7
ND
ND
Sodium
NP
23,550
15,100
15,100
ND
Thallium
10
1.6
18
ND
ND
Zinc (1)
104
NS
238
9.77 J
64.7
NS - Not summarized in ROD.
NP - Not Published
NA - Not analyzed for given parameter.
(1) Not a COC identified in the ROD; however metal is listed due to previous and/or current exceedances of Surface Water Quality Criteria (ug/L)
Concentrations in micrograms per liter (ug/L).
Surface Water Quality Criteria (ug/L) for VOCs are from 1993 Final Risk Assessment by TRC.
Surface Water Quality Criteria shown for hardness-dependent metals are calculated from average water hardness during RI (85,000 ug/L). Sources of metal
criteria/guidelines are EPA National Recommended Water Quality Criteria (2013) and EPA Region V Ecological Screening Levels (2003).
RI - 1990-1994 Remedial Investigation by ESE. (Maximum concentration is taken from results for 11 surface water samples on unnamed stream)
ND - Not detected.
HQ] shading indicates result exceeds given surface water quality criteria.
Bold type indicates maximum concentration has increased since the previous reporting period.
J - Estimated,
In October 2013, all VOC detections in surface water were below National Recommended Water
Quality Criteria identified in the Final Risk Assessment completed in 1993. Acetone, chloromethane,
styrene, 1,1,1-trichloroethane (1,1,1-TCA), TCE, tetrachloroethene (PCE), cis-l,2-dichloroethene (cis-
1,2-DCE), trans-1,2-dichloroethene (trans-1,2-DCE) and vinyl chloride were the only VOCs detected
during the previous five years. Concentrations of VOCs remained relatively consistent from April 2004
to the present, with TCE and vinyl chloride showing decreasing trends.
October 2013 data show only three exceedances of National Recommended Water Quality Criteria in
surface water (SW01); as noted in Table 4. The remaining metals analyzed for were below this criteria.
Consistent with historic surface water results, fewer metals were detected at lower concentrations, from
upstream (SW01) to downstream (SW03) on the unnamed stream.
Since the 1993 Risk Assessment, there have been increased/decreased concentrations of iron and silver,
respectively (silver to ND levels, though the detection limit for silver (10 ug/L) is slightly above the
guideline (2.86 ug/L)) in the unnamed stream; the two metals of concern at that time. To address this
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potential analytical issue for silver, use of a more sensitive analytical method should be considered prior
to the next round of surface water sampling. Data collected since that time show that both metals remain
below the maximum RI concentrations and impacts to human health and the environment are considered
nominal; with further protection through IC's and access controls
Groundwater Flow
Groundwater contour and potentiometric surface maps for the shallow (overburden), top-of-rock and
bedrock aquifers, as provided in annual Long-Term Monitoring (LTM) Reports by URS, were compared
to evaluate historic changes in groundwater flow. In addition, equipotential contours for PRB Zone A
(shallow), Zone B (intermediate) and Zone C (deep) are presented on an annual basis. Review of the
groundwater flow patterns during the previous (2009) FYR indicated no significant changes in the
groundwater levels or groundwater flow direction within the study area.
The groundwater contour and potentiometric surface contours as shown in Figures 8 and 10 and
presented in the 2009, 2010, 2011, 2012 and 2013 annual LTM Reports (based on quarterly water level
measurements) show some features of note including:
A westward extending component of groundwater flow within the shallow overburden in the
vicinity of monitoring well MW-6A (located approximately 450 feet west of IWS-2; see Figure
2) was distinctive in 2009 and evident in 2010, but was not evident during subsequent
monitoring events;
Historically, a primarily westward shallow overburden groundwater flow direction was evident
south of IWS-3. Based on recent monitoring data, an apparent southwest trending component of
shallow overburden groundwater flow is now evident in the area southwest of IWS-3;
Although some mild variability in the top-of-rock potentiometric surface is evident in the
vicinity of the BNA Well Group, the water level elevations and flow directions have remained
relatively stable over the last five years; and
Although relatively minor fluctuations in the water level elevations have been evident, the
groundwater flow patterns in the vicinity of the PRB have been relatively consistent over the last
five years. As noted in the LTMP reports, localized northward flow, along the alignment of the
PRB, in the northern end of the PRB should continue to be monitored to ensure movement of
impacted groundwater flow through the PRB.
No significant changes in overall groundwater levels or groundwater flow direction within shallow
overburden, top-of-rock or bedrock portions of the study area are apparent during the post-cap period of
October 2000 to the present. Therefore, groundwater flow direction is considered to be consistent with
the last FYR period and groundwater flow patterns appear to be stable.
Groundwater Quality Monitoring
Monitoring of groundwater quality at the Site has been conducted on a regular basis since 1994, prior to
the construction of the cap. A Long-Term Monitoring Plan (LTMP) was prepared for the Site in August
2000. This LTMP established a project timeline for the post-cap sampling of groundwater, surface
water, and sediment samples for laboratory analysis. The long-term groundwater monitoring program
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was initiated in October 2000. An Updated Draft LTMP was issued by URS in September 2006, which
included monitoring procedures associated with the PRB and BNA systems. Results of long-term
monitoring activities are subsequently documented in biannual reports (with presentation of data only)
by URS, and in annual LTM Reports submitted to EPA by URS. During this FYR period (April 30,
2009 to April 30, 2014), groundwater was sampled on an annual basis for a total of five monitoring
events. Additional wells and analyses are performed once every five years in conjunction with the
routine annual sampling event.
While as many as 100 groundwater monitoring wells were once present in the vicinity of the Site, the
original LTMP (dated 2000) reduced the number of wells subjected to periodic groundwater sampling
and analysis to 40 of the wells present prior to cap construction, plus an additional eight wells that were
installed during/after cap construction and subsequently added to the LTMP. The updated LTMP (dated
2006) included the sampling of new wells installed to monitor the PRB and BNA systems, specifying
the sampling and analysis of 89 monitoring wells.
The groundwater monitoring well network being utilized for groundwater monitoring includes wells
screened within three distinct subsurface "zones of interest". Shallow overburden (SO) monitoring
wells are those with screened intervals intercepting the groundwater table.. Monitoring wells with
screens completed in the overburden, but resting on the top of the bedrock interface (i.e., deeper
overburden), are termed "top-of-rock" wells (TOR). Monitoring wells installed in the bedrock are
referred to as bedrock. Bedrock monitoring wells are those with screened intervals below the bedrock.
Laboratory testing of samples collected in LTMP wells have included analyses for VOCs, semi-volatile
organic compounds (SVOCs), and TAL metals. Analyses for VOCs are performed annually, while
SVOC and metals analyses are performed every five years. In addition, geochemistry parameters (e.g.,
temperature, pH, dissolved oxygen, specific conductance, and turbidity) are measured and recorded
annually at each LTMP groundwater sampling point.
Table 5 summarizes the maximum concentrations of the analytes that exceeded IGCLs during the
October 2013 sampling event only. An expanded table, including maximum concentrations of analytes
exceeding IGCLs, by well location, for the previous five years is included as Appendix C. Of the
groundwater monitoring wells sampled as part of the LTMP to date, nearly all have contained
contaminant concentrations exceeding applicable IGCLs for metals and/or VOCs at some point.
Table 5
Maximum Concentrations of Groundwater Contaminants that Exceeded IGCLs in October
2013
Parker Landfill Super
'und Site
Parameter (COC)
Screened
Zone
IGCL
(Mg/L)
2013 Maximum
Concentration
Exceeding IGCLs
(Hg/L)
Location of
Maximum
Concentration
Exceedance
VOCs
1,1 -Dichloroethane 11 '*
TOR
70
88.7 J
B138B
1,1 -Dichloroethene
TOR
7
16.0 J
B138B
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Table 5
Maximum Concentrations of Groundwater Contaminants that Exceeded IGCLs in October
2013
Parker Landfill Super
'und Site
Parameter (COC)
Screened
Zone
IGCL
(Mg/L)
2013 Maximum
Concentration
Exceeding IGCLs
(Ug/L)
Location of
Maximum
Concentration
Exceedance
1,2-Dichloropropane (1)*
TOR
5
8.9
B138B
Cis-1,2-Dichloroethene
TOR
70
2,690 J
B138B
1,4-Dioxane (1)*
TOR
3
980 J
B138B
Benzene
TOR
5
5.58
B137B
Methylene Chloride
TOR
5
5.40 J
B136B
Trans-l,2-Dichloroethene
TOR
100
122 J
B138B
Tetrachloroethene
SO
5
71.8
B170B
Trichloroethene
SO
5
2,860
B170B
Vinyl Chloride
TOR
2
998
B138B
SVOCs
3 -Methylphenol/4 -Methylphenol
TOR
200
524
B113BB
Inorganics
Lead(1)*
SO
15
28.4
B174A
Manganese
TOR
300
2,380
B125A
Vanadium
SO
0.2
24.5
B174A
Concentrations in micrograms per liter (ug/L).
(1) Not a COC identified in the ROD; however compound is listed due to previous and/or current exceedances of IGCLs (ug/L).
J - Estimated.
* - Non-COC contaminants with no ROD assigned IGCLs, but still tracked for risk purposes
.SO - Shallow Overburden.
TOR - "Top -of -Rock." wells
BRB - Bedrock, wells
SO - Shallow bedrock wells
BR - Bedrock wells
Routine reporting limits for vanadium, benzo(a)pyrene, pentachlorophenol and trans-1,3-
dichloropropene exceed IGCLs. Though vanadium reporting limits exceed the risk-based IGCL
established in the ROD (0.2 ug/L), an appropriately sensitive analytical method is being used that can
achieve a current risk-based screening level for this compound (86 ug/L). Benzo(a)pyrene and trans-
1,3-dichloropropene analytical methods being utilized are appropriate; however, it is possible to achieve
lower reporting limits (below the IGCLs) using these methods. A more sensitive analytical method,
such as that being used for benzo(a)pyrene, may be necessary to achieve the pentachlorophenol
IGCL. Further coordination with the analytical laboratory and/or use of a more sensitive analytical
method should be considered to address these issues prior to the next round of groundwater sampling.
Metals Trends
The ROD identified arsenic, antimony, beryllium, chromium, manganese, nickel, and vanadium as
COCs. Recent 2013 monitoring data indicate that only lead, manganese and vanadium currently exceed
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their IGCLs. Arsenic and selenium exceed their applicable IGCLs as of the previous FYR, but were
detected below laboratory reporting limits in 2013. The data indicate that one or more metals exceeded
the corresponding IGCL at 28 of the 51 groundwater monitoring wells sampled in October 2013,
consisting of 12 shallow overburden wells, 10 top-of-rock wells, and six bedrock wells. These data
indicate a prevalence of elevated concentrations of vanadium and manganese (above IGCLs) versus
other metals among overburden, top-of-rock, and bedrock wells.
The recent distribution of elevated manganese concentrations in the shallow overburden and top-of-rock
groundwater, and to a lesser degree in the bedrock groundwater, appears to be somewhat concentrated
downgradient of IWS-1 and IWS-2 (see Figure 2). The concentrations of vanadium appear to be more
widely distributed within the shallow overburden, top-of-rock and bedrock groundwater.
Concentrations of vanadium in excess of the IGCL are generally present downgradient of IWS-1 and
IWS-2, as well as in the vicinity of IWS-3. In addition, the only elevated lead concentration above the
IGCL in recent groundwater monitoring data is in the shallow overburden groundwater at B174A,
located in the vicinity of the Passumpsic River.
Data collected during the first FYR period (April 2003, October 2003, and April 2004) indicated
concentrations of chromium, lead, manganese, nickel, thallium and vanadium above IGCLs in no more
than 10 well locations. Therefore, although there have recently been fewer individual metals exceeding
IGCLs, exceedances continue to be present at more well locations.
SVOC Trends
Consistent with previous monitoring events in which groundwater samples from select monitoring wells
are analyzed for SVOCs, only one SVOC (i.e., 3-methylphenol/4-methylphenol) was detected at a
concentration above its IGCL (200 ug/1) in October 2013. Historically, since 2000, 3-methylphenol/4-
methylphenol was detected in two wells located to the southwest of the landfill (i.e., B113BB and
B138B - see Figure 2). In October 2013, 3-methylphenol/4-methylphenol was only detected in
monitoring well B113BB at a concentration (524 ug/L) in excess of the IGCL.2
The COC list for SVOCs includes both 4-methylphenol and bis(2-ethylhexyl)phthalate; however, bis(2-
ethylhexyl)phthalate has not been detected in any of the monitoring wells during the routine sampling
events conducted since February 2000.
VOC Trends
VOCs are the primary constituents of concern at the Site, due to their prevalence and mobility over other
contaminants in groundwater. Up to 12 different VOCs have been detected at concentrations exceeding
IGCLs during the last five LTM events (2009 through 2013). These VOCs consist of acetone, benzene,
1,1-dichloroethane, 1,1-dichloroethene, cis-l,2-DCE, 1,2-dichloroethane, 1,2-dichloropropane, 1,4-
dioxane, methylene chloride, PCE, TCE and vinyl chloride. Historically, 2-butanone (MEK) was
detected in excess of the IGCL of 4,200 ug/1, but no exceedances were detected during LTM events
within the last five years. In general, the chlorinated VOCs, cis-l,2-DCE, PCE, TCE and vinyl chloride,
have had the highest incidence of detection in groundwater during recent monitoring events.
2 3-methylphenol/4-methylphenol was detected in excess of the IGCL in the duplicate sample collected from B113BB in
October 2013. The original sample exhibited a significantly lower concentration of 10.9 ug/L.
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Specifically, a higher incidence of chlorinated VOCs exceeding IGCLs have recently (October 2013)
been detected in shallow overburden groundwater in the vicinity of the PRB, in top-of-rock wells
located near the BNA and to a lesser degree bedrock wells that are located downgradient of the SWDA
and IWS-1.
At the request of EPA, monitoring for 1,4-dioxane in groundwater was initiated in 2004 and
incorporated into the LTMP at MOM wells starting in 2006. In general, 1,4-dioxane also exhibited a
high incidence of detection in groundwater in excess of the IGCL (3 ug/1) during the previous five years.
Based on the October 2013 sampling results, 1,4-dioxane is primarily present in excess of the IGCL in
top-of-rock groundwater (seven of the 15 wells exhibiting IGCL exceedances in October 2013), and to a
lesser degree the shallow overburden and bedrock groundwater. All exceedances are found
downgradient of the IWS-1 and IWS-2 areas.
The Draft 2013 Annual LTM Report submitted by URS includes an evaluation of groundwater quality
trends, consisting of data plots and non-parametric Mann-Kendall Test analysis of VOCs and SVOCs
detected in excess of IGCLs.3 Historic data plots for wells B138A, B131C and B145B are included in
Appendix D for reference. The Mann-Kendall analysis includes monitoring data collected from 2009
through 2013, as well as prior analytical data if insufficient data were available from the past five years,
for purposes of evaluating changes in concentrations over time. The Mann-Kendall evaluation identified
increasing VOC trends at the 95% confidence level in several wells as follows.
B136B (vinyl chloride)
B137B (benzene)
B138B (1,1-dichloroethane, 1,1-dichoroethene and vinyl chloride)
An increasing trend for 1,2-dichloropropane was also identified at the 80% confidence level in B138B.
In addition, stable conditions which can be in an indication of the effectiveness of the remedy in
reducing concentrations below IGCLs were evaluated. Based on a finding of no trend being identified at
the 80%) confidence level, the Coefficient of Variation (CV) Test identified the following stable
conditions.
B113BB (3-methylphenol/4-methylphenol)
B126A (TCE)
B131C (TCE)
B136C (cis-l,2-DCE and PCE)
B138B (benzene, trans-1,2-DCE and TCE)
B145B (vinyl chloride)
Based on key indicator compound (e.g., TCE and cis-l,2-DCE) trend plots and other data presented in
the Draft 2013 Annual LTM Report submitted by URS, there is an indication of some progress toward
3 1,4-dioxane is not included in this VOC trend discussion because it is discussed in more detail later in this five-year review
report.
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the remedy meeting IGCLs. The following historical trends were observed based on the information
provided in the Draft 2013 Annual LTM Report:
Wells Near Source Areas (Landfill, IWS3, IWS2
No VOCs were detected in the B101 and B102 well clusters.
Prior to the previous FYR, well B103A demonstrated an increase in TCE concentrations from
approximately 200 ug/L in 2005 to 1,360 ug/L in 2008, which is higher than TCE concentrations
in 2000. Since November 2008, a reversal of this trend was observed, with both TCE and vinyl
chloride exhibiting a decreasing trend.
Downgradient of the SWDA, well B113BB showed significant decreases in TCE and cis-1,2-
DCE prior to June 2005, with relatively low concentrations evident following completion of the
groundwater remedial action (installation of PRB and BNA systems) in September 2005. TCE
continued to be detected at well B113BB above the IGCL in October 2013 and a seemingly
isolated spike of TCE was detected in 2012.
No VOCs were detected in excess of IGCLs in the B118 well cluster, located cross-gradient to
IWS-1 and the SWDA, in October 2013.
TCE and cis-l,2-DCE are generally decreasing in concentration within B132 and stable within
B132B; however TCE continues to be consistently detected in excess of the IGCL.
Concentrations of cis-l,2-DCE, as well other VOCs including 1,4-dioxane and PCE, have been
more sporadically detected in B132 and/or B132B over the last five years.
No VOCs were detected in excess of the applicable IGCLs in B137A in October 2013. TCE and
cis-l,2-DCE appear to exhibit a recent increasing trend in B137B. In addition, the Mann-Kendall
evaluation noted an increasing benzene trend in B137B.
No VOCs were detected in shallow overburden well B138A in October 2013. Top-of-rock well
B138B, located downgradient of the SWDA, has shown a significant increasing trend in the
concentrations of TCE, cis-l,2-DCE and vinyl chloride since November 2007, with the highest
concentrations of these VOCs detected to date in October 2013. In addition, other VOCs (i.e.,
1.1-dichloroethane, 1,1-dichloroethene, 1,2-dichloropropane, 1,4-dioxane, benzene and trans-
1.2-DCE) continue to be detected in excess of their respective IGCLs. The Draft 2013 Annual
LTM Report suggests leaching waste materials in the SWDA and/or IWS-1, as well as impacted
soil and waste relocated to the SWDA from IWS-2, or periodic settling and compaction of waste
materials within the SWDA as possible causes of the increasing contaminant concentrations;
however further evaluation and monitoring is required.
TCE and cis-l,2-DCE concentrations have decreased within B139A, located downgradient of the
SWDA. Wells B139B and B139C have not exhibited VOCs in excess of IGCLs in the last five
years.
Bedrock well B143, located downgradient of the PRB, did not exhibit VOCs in excess of IGCLs
in October 2013.
No VOCs were detected at levels above IGCLs in the B159 well cluster in October 2013.
TCE was detected in excess of the IGCL at wells B160A and B160B during the previous five
years.
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Wells Downgradient of the Landfill, IWS3 and IWS2 Areas
No VOCs were detected above the IGCLs in well MW4A in the previous five years.
No VOCs were detected above the IGCLs in wells B125A and B125B in the previous five years.
Data plots generally indicate significant decreases in the concentrations of indicator VOCs since
2000, although within B125B, TCE and cis-l,2-DCE concentrations fluctuated between 2001
and 2005.
No VOCs were detected above IGCLs in B13 IB in October 2013. Although the Mann-Kendall
analysis indicates that TCE concentrations are stable in B131C, the data plots are potentially
indicative of an increasing trend in the concentrations of TCE and cis-l,2-DCE. TCE has been
detected relatively consistently above the IGCL over the last five years.
TCE and cis-l,2-DCE concentrations within B136A have decreased to levels below IGCLs.
Concentrations of TCE and cis-l,2-DCE within B136B have fluctuated over time, but have
generally exhibited decreasing concentrations prior to the last FYR. A spike in the concentrations
of TCE and cis-l,2-DCE was detected in 2011 and a potential increasing concentration trend is
evident in the data plots for B136B. Well B136C had a peak in TCE and cis-l,2-DCE
concentrations in 2005, which temporarily decreased to concentrations below the IGCLs;
however spikes in the concentrations of these VOCs were detected in 2009 and 2012.
Wells Near Downgradient Property Lines
Indicator VOCs were not detected above IGCLs during the last five years in B119C; however, as
discussed below, 1,4-dioxane was detected in B119B and B119C in excess of the IGCL. Well
B119C has generally exhibited a decreasing TCE trend since a peak in 2004.
No VOCs were detected in well B120A in October 2013. TCE and cis-l,2-DCE concentrations
are decreasing at B120C. However, concentrations of TCE remain at a significantly higher
concentration (maximum of 2,220 ug/L during the last five years) than the IGCL. Well B120D
exhibited a peak in TCE concentrations in 2005 followed by a peak in cis-l,2-DCE
concentrations in 2006, which are now followed by decreasing or stable trends through October
2013 when vinyl chloride was the only indicator VOC detected above the IGCL.
With exception of 1,4-dioxane, no VOCs were detected above applicable IGCLs in well B121B
during the past five years. Data plots indicated a decreasing trend in indicator VOCs in B121B.
No VOCs were detected in B1210W in October 2013.
No VOCs were detected in B122 during the October 2013 sampling event.
B126A exhibited a peak in both TCE and cis-l,2-DCE concentrations in 2005 with TCE
concentrations up to 5,000 ug/L, which have been followed by decreasing trends since 2005.
Concentrations of TCE and cis-l,2-DCE were relatively stable in B126B until an increase (up to
approximately 1,000 ug/L for TCE) occurred in 2006. Since 2006, TCE and cis-l,2-DCE
concentrations have decreased, but remain somewhat elevated, with concentrations of TCE
consistently detected in excess of the IGCL.
No VOCs were detected at levels above IGCLs in well B201OW during the past five years.
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Well B145B has exhibited an increasing trend in the concentrations of TCE, cis-l,2-DCE and
vinyl chloride over the last five years, with the highest concentrations of TCE and vinyl chloride
detected to date in October 2013. In addition, benzene and 1,4-dioxane were detected in excess
of IGCLs in B145B during the past five years. Indicator VOCs were not detected in excess of
IGCLs during the past five years in B145C; however 1,4-dioxane (2009 through 2013) and
benzene (2009) have been detected in this well above IGCLs.
BNA Monitoring Wells
BNA monitoring wells have generally exhibited a decrease in TCE concentrations with an initial
increase in cis-l,2-DCE concentrations, followed by a decrease in cis-l,2-DCE, and an increase
in vinyl chloride concentrations. Wells B147B, B149B, and B150B exhibit this trend. This
trend is not as apparent in B172B, although the concentration of TCE within this well has
decreased since 2006.
The TCE concentration within B173B appears to be either stable or increasing slightly since
2006.
Several wells (i.e., B147B, B148B, B149B/B149B-R and B172B) appear to exhibit a slight
increase in indicator VOC concentrations in October 2013; however this may be related to the
diminishing effectiveness of the most recent BNA application in September 2011.
PRB Monitoring Wells
Concentrations of VOCs downgradient of the PRB (well clusters B162, B167 and B168) are
lower than VOC concentrations in corresponding upgradient wells (well clusters B164, B165 and
B170), indicating that the PRB continues to be effective in reducing VOC contamination in
groundwater immediately downgradient of the in-situ wall.
Extent of VOCs in Groundwater
Delineating the extent of the VOC plume in groundwater is important for evaluating the effectiveness of
the remedies and implementation of institutional controls. The VOC contaminant plume is defined as
where VOCs exceed IGCLs in groundwater.
Figure 3 presents the IGCL exceedances in MOM and BNA monitoring well groups for VOCs and
SVOCs by flow zone in 2013. All wells shown on the figure were sampled during October 2013 and
only wells that had one or more compounds exceed its IGCL have results shown. The following
observations are based on the depiction in Figure 3:
Shallow overburden IGCL exceedances include 1,4-dioxane, TCE and PCE. With the exception
of 1,4-dioxane in B119B, the shallow overburden exceedances are present in the vicinity and
downgradient of IWS-3;
IGCL exceedances are most prevalent in top-of-rock groundwater, with exceedances of VOCs
and SVOCs downgradient of the SWDA and IWS-1, IWS-2 and IWS-3; and
Bedrock exceedances of IGCLs in B120D, B126B, B136C and B145C include 1,4-dioxane, cis-
1,2-DCE, TCE and vinyl chloride. These wells are generally located downgradient of the
southern portion of the SWDA and IWS-2.
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In October 2013, concentrations of 1,4-dioxane exceeding the IGCL of 3 ug/L were detected in shallow
overburden well B119B (3.6 ug/L) located along Lily Pond Road (Lot 32-131). The IGCL exceedance
at this location is outside of the current Institutional Control Area (see Figure 4). However, public water
is supplied to residences along this road.
In November 2003, groundwater at the Site was reclassified from Class III to Class IV, and a
Groundwater Reclassification Area was delineated based on the area of IGCL exceedances defined from
October 2000 data. As noted in the prior FYR report, exceedances were noted for 1,2-dichloropropane
in the B145B and B145C monitoring wells, which appeared to extend into the 200-foot buffer zone of
the Groundwater Reclassification Area. Exceedances of 1,2-dichloropropane, as well as several more
compounds, including benzene, 1,2-dichloroethane, vinyl chloride, and vanadium were subsequently
detected in the B145B and/or B145C monitoring wells. Exceedances of IGCLs continue to be present in
the B145 well cluster during the past five years. Furthermore, VOC concentrations appear to be
increasing in top-of-rock well B138B, located upgradient to the B145 well cluster, and the highest
concentrations of TCE and vinyl chloride detected to date in top-of-rock well B145B were detected in
October 2013.
Based on an interview with the Zoning Administrator, the Town of Lyndon has updated their zoning
bylaws to establish an Institutional Control Area that mirrors the Groundwater Reclassification Area as
shown in Attachment B of the Findings of Fact and Reclassification Order, Proposed Groundwater
Reclassification at the Parker Landfill, Lyndon, Vermont dated August 23, 2003 (see Appendix B). As
noted above, the Groundwater Reclassification Area was delineated based on data collected in 2000;
however downgradient IGCL exceedances and increasing VOC concentration trends, including 1,4-
dioxane and particularly in the top-of-rock groundwater system, continue to be evident west-southwest
of the SWDA. These data suggest a need for additional monitoring locations and/or installation of
additional wells downgradient of the Site. This information also indicates that the limits of the current
institutional controls that have been established do not encompass the area of recent IGCL exceedances
as required by the ROD. However, public water is supplied to the households within the IGCL
exceedance area.
In addition, several VOCs including 1,1-dichloroethane, 1,4-dioxane, cis-l,2-DCE and/or TCE were
detected in shallow groundwater monitoring wells located near occupied residences (e.g., B118A,
B119B, B120A, B1210W, B126S, B131B, B136A, B137A, B144A, B174A, B201OW, and MW-4A) in
October 2013. Although a risk screening concluded that the vapor intrusion pathway was not significant
at this time, as further described in Section IV, the groundwater trends analysis indicates that
concentrations of several VOCs are increasing. Therefore, groundwater monitoring should continue in
the vicinity of occupied buildings to ensure that concentrations do not increase to levels exceeding the
vapor intrusion screening criteria.
1.4-Dioxane
Groundwater samples have been collected from the MOM monitoring wells for 1,4-dioxane analysis
since the last FYR reporting period. During the October 2013 monitoring event, groundwater samples
from 55 monitoring wells were analyzed for 1,4-dioxane, a solvent additive typically associated with
1,1,1-TCA. The mobility of 1,4-dioxane in the environment is greater than most chlorinated VOCs,
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including 1,1,1-TCA, and therefore, the 1,4-dioxane plume is potentially larger than the plume of other
VOCs.
The Draft 2013 Annual LTM Report includes an evaluation of 1,4-dioxane trends, consisting of data
plots and non-parametric Mann-Kendall Tests combined with the CV test. The Mann-Kendall analysis
includes monitoring data collected from 2009 through 2013, as well as prior analytical data if
insufficient data were available from the past five years, for purposes of evaluating changes in 1,4-
dioxane concentrations overtime.4 The Mann-Kendall evaluation identified increasing 1,4-dioxane
trends in several wells B131C, B137B, B138B and B145B (see Figure 3). Each of these wells is located
downgradient of the SWDA and IWS-1.
As shown on Figure 3, there are multiple 1,4-dioxane exceedances of the IGCL within the shallow
overburden, top-of-rock, and bedrock wells downgradient of the Site, near Lily Pond and Red Village
Roads. The highest concentrations of 1,4-dioxane were detected in top-of-rock wells B138B (980 ug/L),
B131C(160 ug/L) and B113BB (89 ug/L), located immediately southwest (B138B and B131C) and
south of the SWDA (B113BB). The trend evaluation presented in the Draft 2013 Annual LTM Report
indicates increasing 1,4-dioxane trends in top-of-rock wells B131C, B137B, B138B and B145B.
Concentrations of 1,4-dioxane in these wells have generally been increasing since monitoring was
initiated at the request of EPA in 2004. The concentrations of 1,4-dioxane detected in October 2013
represent the highest detections to-date in top-of-rock wells B131C, B137B, B138B and B145B.
Concentrations of 1,4-dioxane in B119B, located downgradient of the B137 and B138 well clusters and
outside the current Institutional Control Area, have also recently (2011 through 2013) shown an increase
in 1,4-dioxane concentrations. Concentrations of 1,4-dioxane in monitoring well B113BB, located
downgradient of the southwestern limit of the SWDA, appear to relatively stable since June 2004.
The highest concentration of 1,4-dioxane detected in the shallow overburden groundwater was
downgradient of IWS-3 in well B160C (8.8 ug/L). 1,4-dioxane was also detected in shallow overburden
well B119B, located downgradient of the Site in the vicinity of Lily Pond Road.
Elevated 1,4-dioxane concentrations present in the bedrock wells (e.g., B120D at 27 ug/L and B126B at
11 ug/L) indicate a potential for the 1,4-dioxane plume to extend beyond the boundary of the
Groundwater Reclassification Area. Continued monitoring of groundwater for 1,4-dioxane is necessary,
and may require the monitoring of additional existing monitoring wells and/or the installation and
monitoring of new groundwater wells.
Landfill Gas
The concentration of landfill gas is monitored at gas extraction wells within the SWDA landfill and off-
cap gas monitoring probes. The landfill gas system, including gas extraction system, flare system,
compressed gases, management and safety equipment, undergoes monthly inspections by the PRP. No
problems were noted during the monthly inspections conducted during the last five years.
The gas extraction wells are also monitored monthly (output only) for flow rate, temperature, vacuum,
and the concentrations of methane, carbon dioxide and oxygen. The data are intended to be used to
4 No trend evaluation was performed on monitoring wells where 1,4-dioxane was not detected or detected fewer than four
times during the monitoring period. This includes a total of 37 monitoring well locations.
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balance the landfill gas management system by optimizing methane gas collection and minimizing the
rate at which oxygen is pulled into the waste from the atmosphere. Monitoring data indicate the landfill
gas management system is properly balanced.
The crawl spaces beneath the mobile homes to the northwest of the landfill were also monitored in the
past for the presence of landfill gas. Subsurface gas monitoring probes were installed mainly in the
northwest portion of the Site to define the extent of landfill gas beyond the boundary of the SWDA
landfill. The subsurface investigations conducted during the installation of the probes indicated there are
two separate zones beneath the mobile home park, shallow and deep, where landfill gas has been shown
to migrate. The zones are separated by a fine-grained silt layer that appears to act as a barrier to retard
the upward vertical migration of landfill gas from the deep zone into the shallow zone.
Probe monitoring data have historically indicated higher and more sustained concentrations of methane
in the deep zone, while the detections in the shallow zone have generally been lower and intermittent.
During previous FYRs, it was noted that there was a strong correlation between periods of low
barometric pressure and the presence of landfill gas in both zones and that the low barometric pressure
was creating a pressure differential between the landfill waste and the surrounding soils causing gas to
migrate from the high pressure (landfill waste) to low pressure (surrounding soils). The rise and fall of
the barometric pressure resulted in a pulsing of landfill gas into the soils below the mobile homes. It
was not clear whether the gas in the shallow zone was the result of vertical migration from the deep zone
or lateral migration directly from the landfill. In either case, gas in the shallow zone has the most
potential to migrate upward into the crawl spaces beneath the mobile homes, or the interior of the mobile
homes where the gas would be cause for concern.
The PRP is currently conducting monitoring of landfill gas probes at a minimum of once per month.
Two levels of contingency are currently in place to protect the safety of the mobile home residents. A
concentration above 20% of the Lower Explosive Limit (LEL) within a shallow probe triggers expanded
monitoring to define the extent of the gas plume until concentrations subside. A concentration of 50%
of the LEL within a shallow probe triggers expanded monitoring of the mobile homes to determine if
explosive concentrations are present. LEL measurements during the last five years did not trigger any
contingency activities.
In general, the methane concentrations in landfill gas probes declined since balancing and optimization
of the landfill gas management system started in January 2003. From October 2002 through January
2005, gas probes were monitored on a daily basis. Beginning in February 2005, following approval of
the Gas Probe Monitoring Program and Contingency Plan in January 2005, barometric-based monitoring
was conducted, which included monitoring on a monthly basis at a minimum, but more frequently if the
barometric pressure fell below the benchmarks.
During the 2001 to 2004 FYR period, data were presented for gas probes GP-21B (shallow) and GP-
21A (deep), showing a significant decrease over that period from the highest methane concentrations (as
percent LEL) of 250 and 74 for the deep and shallow zones, respectively. In response to the 2004 FYR
report recommendations for further monitoring and delineation of the elevated methane concentrations,
additional probes were installed in October 2004 and August 2006, including GP-34A, GP-34B and GP-
35 located downgradient of the GP-21 cluster.
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Building upon the previous FYR, Figure 5 shows the results of the monitoring for GP-34B (shallow) and
GP-34A (deep) from November 2006 to December 2013. This graph indicates that methane has not
been detected in the shallow probe (GP-34B), methane concentrations have decreased in GP-34A (the
deep probe) and have generally been non-detect during the past five years. Over this timeframe,
methane was not detected in either of the GP-21 probes or at GP-35. The methane concentration (as
percent LEL) trends within the GP-34 well cluster continue to indicate that the methane gas collection
system is being properly balanced.
To date methane has not been detected in the crawl spaces below the mobile homes, even when the
concentration of methane in the shallow gas probes exceeded 50% LEL (prior to the current FYR
period). Therefore, the performance standard for the landfill to maintain gas concentrations to 25% of
the LEL in the shallow soil below the mobile homes and 100% LEL at the landfill boundary is
protective. The 25% LEL standard represents a factor of safety of 4 against explosion in subsurface
structures. The factor of safety should be higher for the crawl spaces due to the dispersion of the gas
when it enters the atmosphere. Continued monitoring is critical to ensuring the remedy is protective in
the future.
Review of ARARs and Other Standards
ARARs for the Parker Landfill Superfund Site were identified in the ROD (April 1995) and include the
following:
Federal Safe Drinking Water Act MCLs and Maximum Contaminant Level Goals (MCLGs)
Vermont Hazardous Waste Regulations
Vermont Groundwater Protection Rule and Strategy (VT Primary Groundwater Quality
Standards)
Vermont Water Quality Standards
Vermont Solid Waste Regulations
Vermont Hazardous Waste Regulations
Vermont Land Use and Development Law
Vermont Air Pollution Control Regulations
Federal National Emission Standards for Hazardous Air Pollutants (NESHAP) for Vinyl
Chloride
Federal NESHAP for Benzene Waste Operations
Federal Noise Control Regulations
Vermont Wetland Rules
Vermont National Pollutant Discharge Elimination System (NPDES) Permit
Resource Conservation & Recovery Act (RCRA)
Additionally, the ROD identifies the following as "To Be Considered" criteria:
Federal Safe Drinking Water Act Secondary Maximum Contaminant Levels (SMCLs)
Federal Safe Drinking Water Act Proposed MCLs
Federal Drinking Water Health Advisories
Federal Groundwater Protection Strategy
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Federal Interim Sediment Quality Criteria
Most of the ARARs cited in the ROD related to the design and construction of the landfill cap remedy
have been met. Landfill cap ARARs that apply to ongoing landfill O&M activities include Vermont Air
Pollution Control Regulations (adopted through September 2011 with proposed amendments currently
under review), Federal NESHAP for Vinyl Chloride; Federal NESHAP for Benzene Waste Operations;
and ARARs related to landfill post-closure maintenance and monitoring. These ARARs will be met
with continued operation and maintenance of the landfill gas management system and landfill caps.
The primary ARARs cited in the ROD related to the groundwater remedy include the Federal Safe
Drinking Water Act MCLs, MCLGs and the Vermont Groundwater Protection Rule and Strategy. The
MCLs, MCLGs and Vermont Primary Groundwater Quality Standards (VPGQS) have not been revised
since the signing of the previous FYR in September 2009.5 These ARARs are being complied with or
will be complied with upon remedy completion. The remedy will be operated and groundwater quality
will be monitored until groundwater cleanup goals are attained.
Construction of the PRB component of the groundwater remedy required that wetlands be created on
Site to compensate for those destroyed to construct the PRB. The compensatory wetland was
constructed and is inspected as part of routine O&M activities for the remedy. The principal ARAR for
this portion of the groundwater remedy is the Vermont Wetland Rules. In May 2012, rulemaking
authority concerning Vermont Water Quality Standards, Wetland Rules, Public Water Rules, Surface
Level Rules and Rules Determining Mean Water Levels was transferred from the Vermont Natural
Resources Board to the Agency of Natural Resources. The Vermont Wetland Rules were subsequently
amended (adopted July 16, 2010), becoming effective on August 1, 2010.
ARARs cited in the ROD to address protection of surface water bodies include the Vermont Water
Quality Standards and NPDES provisions of the Clean Water Act. As noted below, the NPDES rules do
not currently apply to the groundwater remedy. The existing Vermont Water Quality Standards became
effective December 20, 2011. Proposed amendments to Water Quality Standards have been filed with
the Vermont Secretary of State on May 23, 2014. The proposed amendments include modifying the
Water Quality Criteria for the Protection of Health and Aquatic Biota (Appendix C of the Water Quality
Standards), including some COCs at the Site (e.g., proposed criteria for iron).
The Vermont NPDES Permit rules do not apply to the groundwater remedy as currently constructed,
because the groundwater remedy does not include a discharge to surface water, as was envisioned in the
ROD-specified groundwater remedy (a pump-and-treat system).
The Vermont Underground Injection Control (UIC) Rule is relevant and appropriate to the groundwater
remedy as currently constructed, because bio-enhancing reagents are injected to support the BNA
component of the remedy. This rule requires that owners of injection wells apply for a permit.
However, because the remedial action is being performed on a Superfund Site, it is not required that a
permit be obtained. However, the substantive requirements of the UIC permit process should be met.
5 As indicated in Appendix C interview record, the VTDEC anticipates adopting a new Groundwater Protection Rule and
Strategy prior to the next FYR due date in 2019.
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Table 6 lists those COCs for which the current MCL or VPGQS is different from the ROD-based IGCL,
or those contaminants that are present in Site groundwater that do not have a ROD-based IGCL but do
have a MCL or VPGQS that is exceeded at some locations. Table 7 presents the ROD-based IGCLs and
their basis, along with the current MCL or VPGQS. IGCLs were established in the ROD for
groundwater COCs. The ROD established IGCLs as MCLs, MCLGs, or VPGQS, as available. For
chemicals lacking regulatory limits, risk-based values were used as IGCLs.
Table 6
Water Quality Standards Revised or Developed since 1995 ROD
Analyte
IGCL in ROD
(ug/L)
Current Standard
(MCL and/or
VPGQS) (ug/L)
Type of Current
Standard
Basis of IGCL
T etrachloroethylene
0.7
5
MCL and VPGQS
VPGQS, 1994
2-Butanone
170
4.2
VPGQS
VPGQS, 1994
1,4-Dioxane
NA
3
VPGQS
NA
Arsenic
50
10
MCL and VPGQS
MCL, 1994
Acetone
3,700
700
VPGQS
Risk based
Chromium
50
100
MCL and VPGQS
VPGQS, 1994
Manganese
180
300
VPGQS
Risk based
Table 7
Comparison of IGCLs with Current MCLs and/or VPGQS
Carcinogenic Constituents
ROD-Based
IGCL
(ug/L)
ROD
Basis
for IGCL
Current
MCL/VPGQS
(ug/L)
Source of Current
MCL/VPGQS
(ug/L)
1,1 -Dichloroethene
7
MCLG
7
MCL [a]
Benzene
5
MCL
5
MCL [a]
Methylene Chloride
5
MCL
5
MCL [a]
T etrachloroethene
0.7
VPGQS
5
MCL [a]
Trichloroethene
5
MCL
5
MCL [a]
Vinyl Chloride
2
MCL
2
MCL [a]
1,4-Dioxane
NA
NA
3
VPGQS [b]
Bis(2-ethylhexyl)phthalate
6
MCL
6
MCL [a]
Arsenic
50
MCL
10
MCL [a]
Beryllium
4
MCL
4
MCL [a]
1,2 -Dichloroethene
70
MCL
70
MCL [a, e]
Acetone
3,700
RB
700
VPGQS [c]
2-Butanone
170
VPGQS
4,200
VPGQS [c]
1,1,1 -T richloroethane
200
MCLG
200
MCL [a]
4-Methylphenol
200
RB
1,920*
Risk-based*
Antimony
6
MCL
6
MCL [a]
Chromium
50
VPGQS
100
VPGQS [c]
Manganese
180
RB
300
VPGQS [d]
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Table 7
Comparison of IGCLs with Current MCLs and/or VPGQS
Carcinogenic Constituents
ROD-Based
IGCL
(ug/L)
ROD
Basis
for IGCL
Current
MCL/VPGQS
(ug/L)
Source of Current
MCL/VPGQS
(ug/L)
Nickel
100
MCL
100
VPGQS [c]
Vanadium
0.2
RB
86*
Risk-based*
Bold and Italicized = IGCL in the ROD is higher than the Current MCIVVPGQS for this analyte.
IGCL = Interim Groundwater Cleanup Level from the ROD
MCL = Safe Drinking Water Act Maximum Contaminant Level
MCLG = Safe Drinking Water Act Maximum Contaminant Level Goal
NA = Not Applicable (no IGCL for this analyte included in ROD)
* = Risk-based screening levels established at a cancer risk of 1 x 10"6 or non-cancer hazard of 1.
RB = Risk-Based
VPGQS = Vermont Primary Groundwater Quality Standard
[a] = National Primary Drinking Water Regulations, 40 CFR Ch. I Part 141, 7-1-02 Edition.
[b] = New interim enforcement standard for 1,4-dioxane, VT Water Supply Division, March 6, 2009.
[c] = Vermont Primary Groundwater Quality Standards, Ch. 12: Groundwater Protection Rule and Strategy, February 14, 2005.
[d] New interim enforcement standard for manganese, VT Water Supply Division, March 6, 2009.
[e] The MCL listed for 1,2-dichloroethene is specific to the cis isomer.
The currently applicable standards for acetone and arsenic are lower (i.e., more stringent) than those
applicable at the time of the ROD. The VPGQS standards for tetrachloroethylene, 2-butanone, and
chromium have increased (i.e., are less stringent) from those applicable at the time of the ROD. The
VPGQS for manganese was reduced from what it was in 2004 (reduced from 840 ug/L to 300 ug/L), but
it remains greater than the ROD IGCL of 180 ug/L.
Vermont also previously revised its enforcement standard for 1,4-dioxane from 20 ug/L to 3 ug/L. It
may be necessary to update the ROD IGCL in the future to accommodate these changes in standards,
both more stringent and less stringent than those applied in the ROD, depending on review of
groundwater quality data as the remedy progresses.
Inspection of the Site
The inspection of the Site was conducted on 5/8/2014. In attendance were Leslie McVickar of EPA,
John Schmeltzer of the VTDEC, David Pettit (project engineer) and Scott Heim (senior ecologist) from
TRC on behalf of EPA, Eric Chadburn of Fairbanks Scales, Incorporated and Frederik Schuele of URS.
The Site inspection included visual inspection of the surfaces of the SWDA and IWS-3 caps, the landfill
gas management system, storm water controls, fencing, the wetland compensation areas, the PRB, and
BNA injection wells. The Site inspection generally included the following.
Walking inspection of the perimeter and top of the SWDA landfill cap was conducted to look for
evidence of erosion, cap disturbance, excessive settlement, and poor growth of vegetation (e.g.,
bare spots, presence of stressed grass cover, abnormal growth of weeds/woody vegetation));
On and off-cap storm water control structures were inspected for damage, settlement,
sedimentation, vegetation and blockage;
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The above-ground portions of structures that penetrate the cap (i.e., gas vents and utility poles)
were inspected for damage;
The landfill gas flare was observed to confirm that the flare was operating at the time of the
inspection; and
The wetland mitigation area was inspected.
Overall, the Site appears in good condition. The findings of the Site inspection are summarized below.
The surfaces of the SWDA landfill cap and the IWS-3 were generally in good condition with no
signs of erosion, holes, cracks or bulging. The cover system appeared to be firm and stable and
the vegetative cover was in excellent condition. Several areas of settlement were observed
including the following:
o The area in the western portion of the landfill, in the vicinity of GW-4, appears to have a
fairly significant degree of settlement. The settlement appears to be approximately one
foot below the previous year's elevation and GW-4 has shifted on a noticeable angle.
Since settlement could cause the cap liner to separate from the well and allow infiltration
of precipitation, Fairbanks Scales, Inc. is conducting an examination of the well to
evaluate the need for repairs.
o A minor area (1-foot by 1-foot) of settlement may be occurring at the interface between
the grassed cap and the stone collection area near the inlet to Culvert #2.
o The slope benches and other drainage ditches were in good condition with no signs of
erosion, undermining or bypass.
o The two gabion-lined downcomers, or letdown channels, on the SWDA cap were in good
condition with no evidence of material degradation, erosion, undercutting, or
obstructions, with the following exceptions:
ฆ Vegetation was observed at the bottom of Downcomer No. 1, along with standing
water. The vegetation should be removed.
ฆ An area of settlement at the top of Downcomer No. 2 was observed. Settlement at
this location has historically been observed. It was monitored since the last FYR
inspection through surveying of five points in the area. Representatives from
Fairbanks Scales, Inc. reported that the survey monitoring was expanded to
include portions of the surrounding cap. It was recently determined that this
settlement area needed investigation and repairs, as the settlement was retaining
water above the geotextile liner and preventing proper drainage. Those repairs are
anticipated to be completed in 2014. However, to ensure the future integrity of
the cap all preventative repairs need to be made and an updated survey performed
annually by a VT licensed surveyor to both monitor over time and to warn of
future necessary repairs.
o No obstructions were observed at the ends of the drainage layer outlet pipes. The crushed
stone layer along the edge of the cover system appeared to be in place and did not appear
to be clogged.
o The sedimentation basin was in good condition and appeared to be functioning properly.
Two riprap-lined drainage structures located on the southern and western sidewall of the
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basin, the inlet culvert and the riprap/gabion erosion control apron, were in good
condition. Sedimentation was observed on the southeastern floor of the basin, and
should be removed. Apparent tire ruts are evident on the southern sidewall. The ruts may
contribute to future erosion and should be repaired.
o The landfill gas flare was operating at the time of the inspection. No obvious damage or
changed condition was apparent. However to fully evaluate the gas management system
at the Site, input gas sampling should be conducted; as this has not been done in many
years.
The perimeter and access roads of the SWDA were in good condition with no signs of erosion,
sedimentation or significant blockage.
The PRB and source area monitoring wells appeared to be in good condition, based on visual
observation. No wells were opened during the Site visit.
The BNA system wells appeared to be in good condition, based on visual observation. Well #14
was observed to be unlocked during the Site visit and should be locked.
The wetland compensation areas appear to be functioning as intended. Surface water appears to
have been impounded at the northern wetland compensatory areas from past beaver activity,
which also may have adversely affected the subsurface hydrology to the southern wetland
compensation area by limiting wetland recharge. Surface water was not present in this wetland
compensation area, though the ground detritus did exhibit staining which is associated with
periodic inundation. Vegetation did not appear stressed, though this inspection occurred prior to
the start of the growing season. Overall, both compensatory wetlands currently contain
characteristics of wetland hydrology and predominantly hydrophytic vegetation.
Interviews with Key Stakeholders
During the FYR process, interviews were conducted with parties impacted by the Site, including the
PRP, local authorities and regulatory agencies involved in Site activities or aware of the Site. The
purpose of the interviews was to document any perceived problems or successes with the remedy that
has been implemented to date. Interviews were conducted between May 30, 2014 and June 10, 2014.
Interviews are summarized below and complete interviews are included in Appendix E.
Interviews were conducted with representatives of the VTDEC, Town of Lyndon, Vermont and the
PRPs. The interviews were conducted via telephone or email following the Site inspection. The
following provides a summary of each interview.
John Schmeltzer, Hazardous Waste Manager, VTDEC - Mr. Schmeltzer was interviewed via email
on May 30, 2014. Mr. Schmeltzer feels that the management of the Site is going well and the remedial
actions have been effective in mitigating contamination. He said that he has not had any complaints,
violations or other incidents related to the Site that have required a response from VTDEC and is not
aware of any community groups that are actively involved with the project. Although Mr. Schmeltzer
has a good impression of the Site and communication between the VTDEC, EPA and PRPs is good, he
noted two outstanding issues:
An apparent upward trend in COCs and 1,4-dioxane; and
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Localized settlement in the vicinity of extraction Well GW-4.
Mr. Schmeltzer indicated that EPA and VTDEC have directed the PRPs to evaluate the apparent upward
contaminant trend and provide recommended further steps (as necessary) to be undertaken. Further
evaluation of the localized settlement is also currently being evaluated by the PRPs.
Eric Chadburn, Facilities Manager, Fairbanks Scales, Incorporated - Mr. Chadburn was
interviewed by telephone on June 4, 2014. Mr. Chadburn, representing the PRP responsible for landfill
O&M, reported that overall the landfill portion of the Site is in good order and that he has a good overall
impression of the project. Mr. Chadburn stated that since the last FYR, there have not been any
significant changes to the O&M of the landfill. Although no unexpected difficulties with the O&M of
the landfill have developed, Mr. Chadburn noted that further evaluation of the settlement in the vicinity
of extraction Well GW-4 will be conducted and repairs implemented with EPA approval. Mr. Chadburn
also noted that animal burrows are an ongoing concern, but that mitigation measures have been
successful. Mr. Chadburn stated that he had no recommendations for reducing or increasing activities at
the Site, but that they are planning to prepare for when the time comes that there is insufficient methane
to burn, so that they can have a plan in place to deal with it effectively and efficiently.
Frederik Schuele, Project Manager/Hydrogeologist, URS Corporation - Mr. Schuele was
interviewed via email on June 10, 2014. URS Corporation is the consultant representing Vermont
American, the PRP responsible for the groundwater remedies. URS designed and is operating the
groundwater remedies. Mr. Schuele stated that the PRB and BNA groundwater remedies are
functioning as expected and are performing well, without any unexpected difficulties. Mr. Schuele
indicated that the PRB continues to intercept impacted shallow overburden groundwater from IWS-3, as
designed, and that a significant overall reduction in the mass of VOCs is being achieved downgradient.
Similarly, Mr. Schuele stated that BNA monitoring indicates effective reduction in the concentrations
and mass of VOCs in groundwater downgradient of the landfill, with an overall reduction in TCE
concentrations within the BNA treatment zone since 2005 and the continued presence of chlorinated
ethenes, ethene, volatile fatty acids (VFAs) and nutrients in downgradient monitoring wells indicating
active dechlorination throughout the treatment zone and downgradient aquifer.
Mr. Schuele stated that significant changes to the monitoring of the PRB included an addendum to the
LTMP in July 2010 that modified the sampling program to eliminate analysis of ethene, ethane and
chloride. Performance monitoring of the BNA remedial activity continues to be conducted in accordance
with the approved O&M Plan, but the plan was revised in 2011 to accommodate the use of emulsified
vegetable oil (EVO) as an amendment compound, which resulted in an expanded analytical suite and
additional monitoring of additional wells (both monitoring wells and extraction wells).
Mr. Schuele anticipates continued reductions in the concentrations of VOCs downgradient of the PRB
and BNA areas, with an eventual shift to monitored natural attenuation (MNA), but no detailed
projections for achieving cleanup goals have been established. Given that the BNA remedial activity is
not intended to continue indefinitely, BNA O&M modifications were recently proposed to allow for
continued operation of the BNA remedial activity until concentrations of total chlorinated ethenes are
reduced to the point where MNA is feasible and effective. The proposed BNA O&M modifications will
be implemented pending regulatory approval.
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With regard to increasing VOC and 1,4-dioxane trends within the top-of-rock groundwater within the
western-southwestern portion of the Site, Mr. Schuele indicated monitoring and trend evaluations will
continue to better understand the groundwater conditions and conceptual site model (CSM). The CSM
will be revised (as needed) to identify data gaps for the top-of-rock groundwater flow system,
recommend additional sampling locations and propose installation of addition monitoring wells to
further define the impact extents.
Justin Smith, Zoning Administrator, Town of Lyndon, Vermont - Mr. Smith was contacted via
email on June 10, 2014 regarding the Town's efforts to expand the "Institutional Control Area" and any
new areas/roads/housing developments in the vicinity of the Site. According to Mr. Smith, no new
areas/roads have been included in the zoning ordinance within the last five years and no new
construction is proposed/planned in the vicinity of the Site. Mr. Smith stated that the Town has
completed expansion of the "Institutional Control Area" and that the area is identified in the Town's
zoning bylaws.
IV. TECHNICAL ASSESSMENT
Question A: Is the remedy functioning as intended by the decision documents?
Yes. The review of documents, ARARs, and the results of the Site inspection indicate that the landfill
cap and groundwater remedy are functioning as intended by the ROD and ESD. The major components
of the selected remedy in the ROD included:
Multi-layer caps on the SWDA and three IWS areas with gas collection systems at the three
IW S areas;
Source control groundwater extraction and treatment, which was revised in the July 2004 ESD
in favor of the PRB and BNA technologies with pump-and- treat retained as a contingency;
Wetland restoration;
Institutional controls; and
Long-term monitoring to evaluate the performance and protectiveness of the remedy.
The following provides a summary of how the primary components of the remedy are functioning.
Capping and Landfill Gas Management
The capping of the SWDA and IWS-3 area has achieved the remedial objectives of minimizing, to the
extent practicable, the potential for transfer of hazardous substances from the soil and solid waste into
the groundwater, surface water and sediment; and to prevent direct contact/ingestion of soil or solid
waste posing a potential total cancer risk greater than 10"4 to 10"6, or a potential hazard index greater
than one. Construction of the groundwater remedy was completed in September 2005, and the
groundwater was reclassified to Class IV (not potable; suitable for some industrial and agricultural use).
A municipal water line was constructed to service the residences within the proposed institutional
control boundary, preventing current exposures through household water use. However, due to the fact
that institutional controls will need to be expanded to include current IGCL exceedances, the remedy, as
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prescribed in the ROD, has not yet been fully implemented. This does not impact the remedy's
protectiveness at this time since no one is currently using the Site or associated contaminated water.
Should the institutional controls not be finalized, this could impact the remedy's protectiveness in the
future.
Although currently protective, the area in the vicinity of GW-4 on the SWDA has a fairly significant
degree of settlement which requires evaluation and repairs. As noted in Section III, further evaluation
has been initiated by the PRPs.
The landfill gas management system was designed and constructed in accordance with the Landfill Cap
Remedial Design Statement of Work dated November 1996 and standard engineering practice. While
the performance standard for the gas management system is to protect the potentially exposed
individuals and comply with federal and state regulation, there was some concern in the past with the
ability of the landfill gas system to achieve the ROD objective of preventing lateral migration of landfill
gas. The point of compliance for air, consistent with the NCP, shall be the point(s) of the maximum
exposed individual, considering reasonable expected used of the Site and surrounding area. The
maximum exposed individuals include: (1) adjacent residents; (2) O&M personnel; and (3) individuals
working at the facility. The gas collection system is successful in preventing an unacceptable risk of
exposure to the maximum exposed individuals by controlling the release of landfill gas and treating
collected landfill gas. The gas collection and treatment system also complies with federal and state air
regulations.
To date methane has not been detected in the crawl spaces below the mobile homes and monitoring data
indicate that the frequency of detection and concentration of methane in the subsurface has declined
over time to the point where it is currently non-detect in most gas probes. Current monitoring of the
shallow gas probes provides sufficient warning to allow evacuation of the mobile home residents prior
to the development of explosive conditions.
O&M of the caps and landfill gas management system is effective. Minor issues as identified in the Site
inspection continue to be addressed adequately. The landfill gas management system is the only
component of the cap remedy that offers the possibility of optimization.
Groundwater Restoration, PRB and BNA
Several VOCs (i.e., 1,1-dichloroethane, 1,4-dioxane, cis-l,2-DCE and/or TCE) have been detected in
shallow groundwater monitoring wells located near occupied residences as recently as October 2013.
Although risk screening concluded that the vapor intrusion pathway was not significant at this time, the
groundwater trends analysis indicates that concentrations of some VOCs are increasing in a few
locations. Therefore, groundwater monitoring should continue in the vicinity of occupied buildings to
ensure that concentrations do not increase to levels exceeding the vapor intrusion screening criteria.
In addition, there are multiple 1,4-dioxane exceedances of the IGCL within the shallow overburden, top-
of-rock, and bedrock wells downgradient of the Site, near Lily Pond and Red Village Roads. The
highest concentrations of 1,4-dioxane were detected in top-of-rock wells located immediately southwest
and south of the SWDA. The trend evaluation presented in the Draft 2013 Annual LTM Report indicates
increasing 1,4-dioxane trends in top-of-rock wells within these portions of the Site (i.e., B131C, B137B,
B138B and B145B). Elevated 1,4-dioxane concentrations present in the bedrock wells (e.g., B120D and
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B126B) indicate a potential for the 1,4-dioxane plume to extend beyond the boundary of the
Groundwater Reclassification Area. As a result, continued monitoring of groundwater for 1,4-dioxane is
necessary, and may require the monitoring of additional existing monitoring wells and/or the installation
and monitoring of new groundwater wells.
The modified remedy described in the ESD included construction of a PRB within the source area using
a treatment cell with granular zero-valent iron. The PRB continues to successfully intercept the flow
path of impacted groundwater within the shallow overburden moving downgradient from the IWS-3
source area. Monitoring data collected during the last five years continues to indicate favorable
geochemical conditions for dechlorination of VOCs. As a result, the mass of VOCs in the groundwater
continues to be reduced by the PRB as indicated by concentrations of VOCs downgradient of the PRB
(well clusters B162, B167 and B168) exhibiting lower VOC concentrations than in corresponding
upgradient wells (well clusters B164, B165 and B170). However, monitoring should continue in
accordance with the LTMP to evaluate limited detections of VOCs in excess of the IGCLs downgradient
of the PRB (e.g., TCE in B167B and B168B).
The ESD also included BNA treatment of the downgradient portion of the contaminated aquifer. BNA
amendment applications were successfully implemented in November 2005, September 2007 and
September 2009. Although initial applications were successful, the Draft BNA O&M Plan was amended
in September 2011 to include the use of Slow Release Substrate (SRSฎ). Several BNA monitoring wells
have generally exhibited a decrease in TCE concentrations with an initial increase in cis-l,2-DCE
concentrations, followed by a decrease in cis-l,2-DCE, and an increase in vinyl chloride concentrations.
The observation of these trends, in combination with other indicator data (e.g., presence of ethene,
VFAs, etc.), suggests that the BNA portion of the remedy is promoting favorable conditions for natural
attenuation and is functioning as designed.
Ongoing BNA evaluation and monitoring in accordance with the LTMP is required, as concentrations of
select VOCs continue to exceed IGCLs within and downgradient of the BNA well group and some
increasing trends appear to be evident. For example, the TCE concentration within B173B appears to be
either stable or increasing slightly since 2006. In addition, several wells appear to exhibit a slight
increase in indicator VOC concentrations in October 2013, which suggests the potential for rebound to
be occurring following the previous BNA application in September 2011.
Wetland Restoration
Based on Site inspections conducted during that last five years, the wetland compensation areas appear
to be functioning as intended. Surface water appears to have been impounded at the northern wetland
compensatory areas from past beaver activity, which also may have adversely affected the subsurface
hydrology to the southern wetland compensation area. Although surface water was not present in the
southern wetland compensation area in October 2013, the vegetation does not appear stressed. Overall,
both compensatory wetlands currently contain characteristics of wetland hydrology and predominantly
hydrophytic vegetation indicating that this portion of the remedy is functioning as designed.
Question B: Are the exposure assumptions, toxicity data, cleanup levels, and remedial action
objectives (RAOs) used at the time of the remedy section still valid?
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No. Although there have been changes in toxicity values, exposure assumptions and risk assessment
methods since the 1993 risk assessment, the changes do not affect remedy protectiveness as long as the
landfill cap remains intact, the property is not used for residential purposes, municipal water is supplied
to residences within the groundwater plume, and ongoing monitoring and evaluation of groundwater,
sediment and surface water contaminant concentrations relative to current risk-based concentrations
continues.
Question B is addressed by reviewing the human health and ecological risk assessments that formed the
basis for the selected remedies, describing any significant differences as compared to current risk
assessment practice, and qualitatively evaluating the impact of any such differences on remedy
protectiveness.
Human Health Risk Review
The 1993 risk assessment evaluated the risks and hazards associated with current and future ingestion of
groundwater in the entire vicinity of the Site and on the Site, direct contact with and incidental ingestion
of soil and sediment at the Site, and inhalation of VOCs in air emitted from the landfill and the unnamed
stream.
The primary risks and hazards observed in this analysis were those associated with the ingestion of
contaminated groundwater. The primary risk contributors for the groundwater ingestion pathway were
1,2-dichloroethene, TCE, vinyl chloride, 4-methylphenol, arsenic, and manganese. The risks and
hazards associated with incidental ingestion of and dermal contact with soil were less significant than
those estimated for groundwater ingestion. However, elevated risks and hazards for soil exposures in
the IWS-2 and IWS-3 areas were attributable to TCE, barium, chromium, and vanadium for a future
residential scenario. Risks and hazards above EPA's risk management guidelines were also estimated for
future recreational sediment exposure in the unnamed stream, due to arsenic. Potential risks associated
with current trespasser exposure to surface soil, surface water, and sediment and exposure to VOCs in
ambient air were below EPA's risk management guidelines. The risk assessment did not evaluate the
potential for vapor intrusion (VI) from groundwater contaminants into structures overlying the
groundwater, current or future exposures to surface water, or direct contact with soil or shallow
groundwater by excavation workers.
There were no cleanup levels established for the landfill cap remedy as the landfill cap prevents
exposures to contaminated soil and solid wastes. The ROD established IGCLs as MCLs, MCLGs, or
VPGQS, as available. For chemicals lacking regulatory limits, risk-based values were used as IGCLs.
Sediment and surface water are monitored periodically to determine landfill impacts to the unnamed
brook.
In this FYR report, the toxicity values that served as the basis for the cleanup levels, as contained in the
ROD, were re-evaluated to determine whether any changes in toxicity impact the protectiveness of the
remedy. Any changes in current or potential future exposure pathways or exposure assumptions that
may impact remedy protectiveness are also noted. In addition, environmental data, available since the
last FYR, have been qualitatively evaluated to determine whether exposure levels existing at the Site
present a risk to current human receptors.
Changes in Toxicity Criteria
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Tables 1 and 2 in Appendix F present the changes in toxicity values (oral reference doses and oral
cancer slope factors) for compounds selected as compounds of potential concern (COPCs) in the 1993
Risk Assessment. Updated toxicity information was obtained from the EPA's 2014 Integrated Risk
Information System (IRIS) and other current EPA sources (e.g., the Superfund Technical Support
Center). For most contaminants, changes to toxicity values have been minimal and primarily reflect
decreases in toxicity (e.g., acetone, 2-butanone, 1,1-dichloroethene, 1,1,1-TCA, 4-methylphenol, barium
and manganese), though some compounds are now believed to have greater toxicity than thought in
1993 (PCE, TCE, hexavalent chromium and benzene).
Changes in toxicity values for groundwater COCs would not affect remedy protectiveness since
municipal water has been supplied to residences within the groundwater plume. Until IGCLs are
achieved, an evaluation should be performed to demonstrate that the risk and hazard associated with
potable groundwater do not exceed EPA's risk management guidelines. Until IGCLs are achieved and
groundwater use is demonstrated to pose no risk to human health, the installation of private wells and
associated groundwater exposure pathways should be prevented. The Groundwater Reclassification
Area was delineated based on data collected in 2000; however downgradient IGCL exceedances and
increasing VOC concentration trends, including 1,4-dioxane, continue to be evident west-southwest of
the SWDA. As a result, the established institutional controls do not encompass the area of recent IGCL
exceedances as required by the ROD and institutional controls should be expanded to assure future
protectiveness for groundwater exposures.
One compound not identified as a groundwater COPC in the 1993 Risk Assessment is 1,4-dioxane, a
common solvent stabilizer used with 1,1,1- TCA-based degreasers. Recent (2013) groundwater
sampling for 1,4-dioxane resulted in detected concentrations up to 980 |ig/L. Monitoring of 1,4-dioxane
should be continued and a potential exposure to this compound considered in future risk evaluations as
warranted.
Changes in toxicity do not affect the soil remedy since the SWDA and IWS areas have been
consolidated and capped. The risk assessment identified a future risk associated with residential use of
these areas. Therefore, as long as the cap remains intact and the property is not used for residential
purposes in the future, the remedy remains protective for soil exposure pathways.
Changes in toxicity values have the potential to affect remedy protectiveness for sediment and surface
water. However, recent sediment and surface water monitoring data are compared to risk-based
concentrations, developed using the most up-to-date toxicity and exposure information available to
confirm remedy protectiveness. This comparison is presented in the Human Health Risk Evaluation of
Recent Sampling Data section (below).
Changes in Exposure Pathways, Assumptions and Methods
There have been no changes in land use since the last FYR. The landfill property is undeveloped and
fenced, with only the occasional trespasser accessing the property. With respect to groundwater use,
exposures to contaminants in groundwater used as household water or for other purposes are controlled.
Municipal water has been supplied to residences within the groundwater plume. However, additional
enforceable controls may be needed to assure future protectiveness until IGCLs are achieved.
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A new method to evaluate compounds with mutagenic modes of action is now recommended by EPA.
The currently recommended method was not used as part of the 1993 evaluation since the EPA
carcinogen risk assessment guidance was published subsequent to the completion of the Site-specific
risk assessment. Vinyl chloride, methylene chloride, TCE and total chromium (evaluated as hexavalent
chromium) are COCs which have been determined to be carcinogenic through a mutagenic mode of
action. In the 2005 Supplemental Guidance for Assessing Susceptibility from Early-Life Exposure to
Carcinogens, EPA recommends evaluating chemicals with mutagenic modes of action using either
chemical-specific data on susceptibility from early-life exposures or an age-dependent adjustment factor
(ADAF) applied to the cancer slope factor. Because chemical-specific data on susceptibility from early-
life exposures were available for the derivation of vinyl chloride's updated cancer slope factor, the
updated slope factor is used for risk characterization and an ADAF is not applied. ADAFs are applied
when assessing risk for methylene chloride, TCE and hexavalent chromium. None of the other COCs
were determined to be carcinogenic by a mutagenic mode of action. However, because no complete
exposure pathway exists for groundwater and soil exposures are prevented by the landfill cap remedy,
this change in methodology does not affect the protectiveness of the remedy. In addition, continued
evaluation of sediment and surface water monitoring data compared to risk-based concentrations
developed using the most current methodology will assure that these media do not pose a risk to human
health (see Human Health Risk Evaluation of Recent Sampling Data section below)
In February 2014, EPA published updated standard default exposure assumptions for Superfund sites,
based on exposure studies considered and evaluated in the 2011 Exposure Factors Handbook. Some of
the recommended exposure assumptions are more conservative than those used previously, while some
are less conservative. However, these changes in exposure assumptions do not affect remedy
protectiveness due to the presence of the landfill cap preventing exposure, the availability of public
water, and the ongoing monitoring and evaluation of sediment and surface water contaminant
concentrations relative to current risk-based concentrations.
The 1993 Risk Assessment did not specifically assess the risk to excavation workers exposed to soil or
shallow groundwater contamination during intrusive activities. Because this receptor population has not
been evaluated, excavations into areas of the Site with soil and shallow groundwater contamination
should be prevented, or an evaluation should be performed to determine the potential risk to workers
prior to initiating intrusive activities as part of Site re-development.
An additional pathway of potential concern that was not evaluated in the 1993 Risk Assessment is the
VI pathway. This pathway may be of concern at sites where shallow groundwater contaminated with
VOCs exists in close proximity to occupied buildings. The VI pathway from groundwater to indoor air
was evaluated by EPA in 2003. This evaluation determined this pathway to be associated with
negligible risk due to the presence of clean groundwater between the deep groundwater plume and the
vadose zone.
A VI risk analysis was subsequently prepared by URS as part of the 2013 Annual LTM Report. The
evaluation concluded that cancer risks and noncancer hazards associated with the VI pathway are
minimal for residential properties adjacent to the Site. However, because groundwater concentrations
within the landfill property would be associated with risks and hazards above EPA criteria due to TCE
and vinyl chloride, the report recommends the use of land use controls to prohibit redevelopment on the
landfill property.
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Due to the February 2014 update in the standard default exposure assumptions and recent updates to
toxicity values, the vapor intrusion pathway screening evaluation for the current residences was updated
and is presented in the following section.
Human Health Risk Evaluation of Recent Sampling Data
Sediment
Table 8 summarizes the maximum detected concentrations observed in sediment over the last 5 years at
the three locations. As part of long-term monitoring activities required by the ROD, sampling and
analysis of sediments was performed once in the past 5 years at three locations (SD01, SD02, and SD03)
in the unnamed stream, in October 2013.
To conservatively evaluate whether the maximum detected sediment concentrations would pose a risk to
trespassers or recreational users, a comparison to EPA's May 2014 residential soil Regional Screening
Levels (RSLs) was performed. The residential soil RSLs are developed based on current toxicity and
exposure information and correspond to a carcinogenic risk of 1 x 10"6 and a noncarcinogenic hazard of
0.1, to account for the detection of more than one compound in sediment. Because the screening levels
are based on exposures assumed to occur in a residential yard at a frequency, duration, and intensity
greater than sediment exposures within the unnamed brook, comparison directly to residential soil RSLs
would be highly conservative. Therefore, sediment screening levels were developed assuming the
frequency of contact with soil is approximately 7-fold less (up to 52 days per year as assumed in the
ROD) than residential exposures which are assumed to occur daily. The sediment screening levels
presented in Table 8 below are the residential soil RSLs multiplied by the 7-fold adjustment factor.
Table 8
Comparison of 2009-2013 Maximum Sediment Concentrations to Human Health
Screening Levels
Pollutant
2009-2013 Maximum Sediment
Concentration (mg/kg)
Sediment Screening Level (mg/kg)
Aluminum
4,090
53,900
Barium
28.2
10,500
Chromium
7.58
2.1
Cobalt
2.52
16.1
Copper
4.22
2,170
Iron
10,800
38,500
Lead(1)
8.33
400
Manganese
220
1,260
Mercury
0.0341
5.46
Nickel
3.92
1,050
Vanadium
8.74
273
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Table 8
Comparison of 2009-2013 Maximum Sediment Concentrations to Human Health
Screening Levels
Pollutant
2009-2013 Maximum Sediment
Concentration (mg/kg)
Sediment Screening Level (mg/kg)
Zinc
37.4
16,100
(1) Screening Level listed is the residential lead screening level developed using the Integrated Exposure Uptake Biokinetic Model.
Maximum detected sediment concentrations are below the RSLs except for chromium (assuming
chromium is present in the hexavalent form). The sediment chromium concentration exceeds the
sediment screening level set at a cancer risk of 1 x 10"6 by less than 4-fold, indicating an incremental
cancer risk of less than 4 x 10"6. Factoring in the risk and hazard of all chemicals combined, this
comparison of maximum sediment concentrations to sediment screening levels indicates that exposure to
sediment in the unnamed brook would not be associated with a cumulative cancer risk and
noncarcinogenic hazard greater than EPA's risk management criteria and consequently, would not pose
an unacceptable risk to human health.
Routine reporting limits for thallium in sediment (approximately 20 mg/kg to 40 mg/kg) exceed its
sediment screening levels of 0.55 mg/kg set at a noncarcinogenic hazard of 0.1. In addition, two of the
four sediment sample results for thallium were rejected during the data validation process. To address
these potential analytical issue, use of a more sensitive analytical method should be considered prior to
the next round of sediment sampling.
Surface Water
Table 9 summarizes the maximum detected concentrations observed in surface water over the last 5
years at the three locations. Surface water sampling along the unnamed stream was also performed at
three locations on an annual basis from September 2009 to October 2013. The locations of stream
surface water samples (SW01, SW02, and SW03) were co-located with the sediment sample locations
(SD01, SD02, and SD03).
To conservatively evaluate whether the maximum detected surface water concentrations would pose a
risk to trespassers or recreational users, a comparison to the dermal component of the EPA's May 2014
tap water RSLs was performed. Use of the dermal component of the tap water screening levels is
appropriate since depth of surface water in the unnamed brook is less than two feet, making swimming
(and subsequent ingestion exposures) highly unlikely. The tap water RSLs are developed based on
current toxicity and exposure information and correspond to a carcinogenic risk of 1 x 10"6 and a
noncarcinogenic hazard of 0.1, to account for the detection of more than one compound in surface water.
Because the dermal component of the tap water RSL is based on exposures assumed to occur to
household water at a frequency, duration and intensity greater than surface water exposures within the
unnamed brook, comparison directly to the tap water RSL would be highly conservative. Therefore,
surface water screening levels were developed assuming the frequency of contact with surface water
within the unnamed brook is approximately 52 days per year (as assumed in the ROD) compared to
daily dermal contact with household water (i.e., a difference of approximately 7-fold). The surface
water screening levels presented in Table 9 below are the tap water RSLs multiplied by the 7-fold
adjustment factor.
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Table 9
Comparison of 2009-2013 Maximum Surface Water Concentrations to Human Health
Screening Levels
Pollutant
2009-2013 Maximum Surface Water
Concentration (ug/L)
Surface Water Screening Level
(ug/L)
1,1,1 -T richloroethane
1.3
175,000
Acetone
7.03
3,080,000
Styrene
0.733
7,000
T etrachloroethene
0.749
161
Trichloroethene
30.6
48.3
Vinyl chloride
0.359
1.89
cis-l,2-Dichloroethene
25.3
252
T rans-1,2 -Dichloroethene
0.277
2,520
Aluminum
3,320
3,150,000
Barium
112
44,800
Cobalt
3.22
2,380
Iron
16,100
2,240,000
Lead(1)
13.3
15
Manganese
2,060
3,080
Vanadium
6.47
420
Zinc
64.7
1,610,000
(1) Screening Level listed is the Maximum Contaminant Level (MCL) for lead, protective of residential exposures to water including ingestion
and dermal contact.
Maximum detected surface water concentrations are below the surface water screening levels.
Therefore, exposure to surface water in the unnamed brook would not be associated with a cumulative
cancer risk and noncarcinogenic hazard greater than EPA's risk management criteria and consequently,
would not pose an unacceptable risk to human health.
Groundwater
The current VI pathway for residences in the vicinity of the landfill is evaluated using groundwater data
collected between 2009 and 2013. Shallow overburden wells included in the analysis are: B118A,
B119B, B120A, B1210W, B126S, B131B, B136A, B137A, B144A, B174A, B201OW, and MW-4A.
This VI screening consists of a comparison of maximum detected shallow groundwater VOC
concentrations from the vicinity of the occupied residences to groundwater vapor intrusion screening
levels (VISLs) protective of groundwater to indoor air impacts. The VISLs were calculated using
formulas obtained from EPA's 2014 VISL calculator (version 3.2.1) and the EPA's May 2014
residential indoor air RSLs, as presented in Appendix F, Table 3. The VISLs correspond to a cancer
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risk of 1 x 10"6 for carcinogens or a hazard quotient of 0.1 for noncarcinogens, to account for the
detection of more than one compound in groundwater.
VOC concentrations are below VISLs presented in Table 10, except for benzene and TCE. For these
two compounds, the maximum detected concentration exceeds the VISL based on a cancer risk of 1 x
10"6 by less than 2-fold, indicating the cancer risk is less than 2 x 10"6 for each of the compounds. In
addition, the maximum detected TCE concentration exceeds its VISL based on a non-carcinogenic
hazard quotient of 0.1 by approximately 3-fold. Factoring in the risk and hazard of all chemicals
combined, the VI pathway would not be associated with a cumulative cancer risk and noncarcinogenic
hazard greater than EPA's risk management criteria, confirming that the remedy is currently protective
of VI.
Table 10
Comparison of Shallow Overburden Groundwater Concentrations to Vapor Intrusion
Screening Levels
VOC
Maximum 2009-2013 Shallow
Overburden Groundwater Concentration
(ug/L)
Vapor Intrusion Screening Level
(ug/L)
1,1 -Dichloroethane
0.455
7.83
Acetone
3.16
2,240,000
Benzene
3.05
1.59
Methylene chloride
0.338
474
Trichloroethene
1.62
0.521
(a) Values taken from Appendix F. The screening concentrations corresponding to a cancer risk of 10"6 and noncancer hazard of 0.1.
Routine reporting limits for benzene (5 ug/L), TCE (5 ug/L) and VC (1 ug/L) in groundwater samples
are slightly greater than their corresponding VISLs. Because benzene and TCE were detected in
monitoring wells included in the VI screening at estimated concentration less than the reporting limit,
the slightly elevated reporting limits do not compromise the conclusions of the VI screening. For VC,
VISLs are 0.15 ug/L for a cancer risk of 1 x 10"6 and 8.8 ug/L for a HQ of 0.1. The 1 ug/L VC reporting
limit is less than the non-cancer based VISL, but exceeds the cancer-based VISL and would be
associated with approximately a 7 x 10"6 cancer risk. Therefore, the elevated reporting limits for VC in
groundwater would not change the conclusions of this VI screening.
However, the groundwater trends analysis indicates that concentrations of several VOCs are increasing
indicating that groundwater monitoring should continue in the vicinity of occupied buildings to ensure
that concentrations do not increase to levels exceeding the VISLs. In addition, should further Site
development include the construction of occupied buildings above areas where shallow groundwater
VOC contamination is present, the indoor air pathway should be further evaluated to determine the
potential risk to individuals using those buildings. It should be noted that 1,4-dioxane was detected in a
number of the shallow overburden wells. However, because 1,4-dioxane does not readily volatilize
from groundwater and does not meet EPA's definition of a volatile compound, it is unlikely to
contribute significantly to VI risk.
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Ecological Risk Review
EPA's ecological risk assessment evaluated potential risks associated with stream and river surface
water, stream sediment, and surface soil within the IWS areas. EPA ambient water quality criteria and
available sediment screening benchmarks were used to evaluate chemical toxicity to ecological
receptors. Surface soils were evaluated by estimating exposure doses received by various indicator
species representing different foraging guilds. These doses were then compared to toxicity data
obtained from the scientific literature.
The ecological risk assessment concluded that surface water quality in the unnamed stream may be
impacted by elevated concentrations of iron and silver. Sediment concentrations of barium, cyanide and
manganese were elevated above screening benchmarks but the results of macrobenthic invertebrate
community sampling concluded that surface water and sediment contamination within the stream are
unlikely to have resulted in adverse impacts to resident aquatic biota.
Risks to terrestrial receptors exposed to contaminants in surface soil were assessed by modeling
exposures to three indicator species. Based on the modeling, the ecological risk assessment concluded
that concentrations of metals in the IWS area surface soils may impact shrew (insectivores), while
herbivores (e.g., meadow voles) and higher trophic levels (e.g., red fox) are unlikely to be affected.
Because surface soils within the SWDA and IWS areas have been consolidated and capped, there is no
longer a complete ecological exposure pathway between receptors and surface soils. As long as the caps
are maintained, this exposure pathway will remain incomplete.
As part of long-term monitoring activities required by the ROD, sampling and analysis of sediments was
performed once in the past 5 years at three locations (SD01, SD02, and SD03) in the unnamed stream, in
October 2013. Section III (Review of Site Monitoring Data) discussed the comparison of maximum
concentrations detected in the long-term monitoring samples collected in the unnamed stream to the
project-specific sediment quality guidelines established for the Site in the risk assessment. The 1993
ecological risk assessment concluded that barium, cyanide, and manganese concentrations were elevated
above benchmarks but were unlikely to result in adverse effects to resident aquatic organisms. Cyanide
was removed from the long-term monitoring program because the one sample location where an
elevated concentration was detected had been disturbed during the construction of the cap. Maximum
barium and manganese concentrations are lower than detected during the RI. Therefore, the potential
for ecological impacts has decreased and the remedy remains protective with respect to sediment
exposure to aquatic receptors.
Surface water sampling along the unnamed stream was performed at three locations on an annual basis
from September 2009 to the present. The locations of stream surface water samples (SW01, SW02, and
SW03) were co-located with the sediment sample locations (SD01, SD02, and SD03). Section III
(Review of Site Monitoring Data) discusses the comparison of maximum concentrations detected in the
long-term monitoring samples collected in the unnamed stream to National Recommended Water
Quality Criteria. The 1993 ecological risk assessment concluded that aquatic biota in the unnamed
stream may be impacted by elevated concentrations of iron and silver. However, surface water
concentrations of silver have decreased in the unnamed stream to non-detectable levels and the
maximum 2009-2013 iron concentration is approximately 2-fold lower than the maximum RI iron
47
Parker Landfill Superfund Site
Third Five-Year Review Report
September 2014
-------
concentration. Therefore, the potential for ecological impacts has decreased and the remedy remains
protective with respect to surface water exposures.
Question C: Has any other information come to light that could call into question the protectiveness
of the remedy?
Yes. Although the remedy continues to be protective in the short-term, future protectiveness could be
affected by downgradient plume migration. Specifically, top-of-rock wells B131C, B138B and B145B
located downgradient of the SWDA, have shown a significant increasing trend in the concentrations of
TCE, cis-l,2-DCE and vinyl chloride in recent years, with the highest concentrations of these VOCs
detected to-date in October 2013. In addition, other VOCs (i.e., 1,1-dichloroethane, 1,1-dichloroethene,
1,2-dichloropropane, 1,4-dioxane, benzene and trans-1,2-DCE) have been detected in excess of their
respective IGCLs in B138B. The increasing VOC concentration trends indicate a potential for the
contaminant plume to extend beyond the boundary of the Groundwater Reclassification Area (mirrored
by the current Institutional Control Area). However, public water is supplied to residences within the
plume area.
Increasing 1,4-dioxane trends in are evident in top-of-rock wells B131C, B137B, B138B and B145B,
which are located downgradient of the SWDA and IWS-1. The B145 well cluster is located in the
downgradient portion of the current Institutional Control Area buffer. Concentrations of 1,4-dioxane in
these wells have generally been increasing since monitoring was initiated at the request of EPA in 2004.
The concentrations of 1,4-dioxane detected in October 2013 represent the highest detections to-date in
top-of-rock wells B131C, B137B, B138B and B145B. Concentrations of 1,4-dioxane in B119C, located
downgradient of the B137 and B138 well clusters and outside the current Institutional Control Area,
have also recently (2011 through 2013) shown an increase in 1,4-dioxane concentrations.
The Draft 2013 Annual LTM Report suggests leaching waste materials in the SWDA and/or IWS-1, as
well as impacted soil and waste relocated to the SWDA from IWS-2, or periodic settling and
compaction of waste materials within the SWDA as possible causes of the increasing VOC
concentrations; however further evaluation and monitoring is required to determine source(s) and long-
term protectiveness of the remedy. Bosch has proposed updating the CSM for the Site to identify and
define data gaps prior to submittal of the September 2015 LTM Report and anticipates installation and
monitoring of additional monitoring wells.
Based on all of the activities conducted as part of this FYR, no additional information has come to light
which would call into question the current protectiveness of the landfill cap or groundwater remedies.
Technical Assessment Summary
The review of documents, ARARs, and the results of the Site inspection indicate that the landfill cap and
groundwater remedy are functioning as intended by the ROD and ESD. The capping of the SWDA and
IWS-3 area has achieved the remedial objectives of minimizing, to the extent practicable, the potential
for transfer of hazardous substances from the soil and solid waste into the groundwater, surface water
and sediment and to prevent direct contact/ingestion of soil or solid waste posing potential risks to
human health and the environment. The PRB and BNA remedial activities have been successful in
reducing the contaminant concentrations and mass within and downgradient of the treatment areas. In
addition the wetland restoration areas are functioning as designed. Although the remedies are
48
Parker Landfill Superfund Site
Third Five-Year Review Report
September 2014
-------
functioning as designed and are currently protective, some issues requiring further evaluation have been
identified, as described in Section V.
Exposure assumptions, toxicity data, cleanup levels and RAOs were addressed by reviewing the human
health and ecological risk assessments that formed the basis for the selected remedies, describing any
significant differences as compared to current risk assessment practice, and qualitatively evaluating the
impact of any such differences on remedy protectiveness.
There have been no changes in land use since the last FYR. Though there have been changes in toxicity
values, exposure assumptions and risk assessment methods since the 1993 risk assessment, the changes
do not affect remedy protectiveness as long as the landfill cap remains intact, the property is not used for
residential purposes, municipal water is supplied to residences within the groundwater plume, and
ongoing monitoring and evaluation of groundwater, sediment and surface water contaminant
concentrations relative to current risk-based concentrations continues.
An additional pathway of potential concern that was not evaluated in the 1993 risk assessment is the VI
pathway. The VI pathway from groundwater to indoor air was evaluated by EPA in 2003. This
evaluation determined this pathway to be associated with negligible risk due to the presence of clean
groundwater between the deep groundwater plume and the vadose zone. A VI risk analysis was
subsequently prepared by URS as part of the 2013 Annual LTM Report and updated as part of this FYR.
The evaluations concluded that cancer risks and noncancer hazards associated with the VI pathway are
minimal for residential properties adjacent to the Site. However, because groundwater concentrations
within the landfill property would be associated with risks and hazards above EPA criteria due to TCE
and vinyl chloride, land use controls to prohibit redevelopment on the landfill property may be
warranted.
EPA's ecological risk assessment evaluated potential risks associated with stream and river surface
water, stream sediment, and surface soil within the IWS areas. The potential for ecological impacts in
sediments and surface water has decreased and the remedy remains protective with respect to sediment
and surface water exposures to aquatic receptors. Because surface soils within the SWDA and IWS areas
have been consolidated and capped, there is no longer a complete ecological exposure pathway between
receptors and surface soils. As long as the caps are maintained, this exposure pathway will remain
incomplete.
From all of the activities conducted as part of this FYR, no new information has come to light which
would call into question the protectiveness of the landfill cap or groundwater remedies.
49
Parker Landfill Superfund Site
Third Five-Year Review Report
September 2014
-------
V. ISSUES / RECOMMENDATIONS AND FOLLOW-UP ACTIONS
Table 11
Issues and Recommendations/Fo
low-up Actions
ou#
Issue
Recommendations/
Follow-up Actions
Party
Responsible
Oversight
Agency
Milestone
Date
Affects Protectiveness?
(Y/N)
Current
Future
OU1
Institutional
controls need to
be expanded to
ensure that the
boundary
encompasses the
current
contaminant
plume.
Finalize Institutional
controls for the Site.
PRP
EPA/
VTDEC
12/31/2016
No
Yes
OU1
Recent data
indicates that
conditions have
changed in the
groundwater
west of the
SWDA.
Implement an
investigation to evaluate
and determine the current
nature and extent of the
VOC plume.
PRP
EPA/
VTDEC
12/31/2015
No
Yes
OU1
Extent of 1,4-
dioxane plume
needs to be
determined and
further
monitored.
Continue to monitor and
define the extent of 1,4-
dioxane in groundwater to
ensure the plume is within
the areas of established
institutional control areas.
PRP
EPA/
VTDEC
12/31/2015
No
Yes
OU1
Annual vapor
intrusion
evaluations must
be performed.
Annually evaluate all
groundwater VOC data,
particularly in the vicinity
of occupied buildings,
against appropriate vapor
intrusion screening
criteria.
PRP
EPA/
VTDEC
Ongoing
No
Yes
OU1
Localized
landfill cap
settlement.
Evaluate and repair
settlement in the vicinity
of extraction well GW-4.
PRP
EPA/
VTDEC
12/31/2014
No
Yes
50
Parker Landfill Superfund Site
Third Five-Year Review Report
September 2014
-------
VI. PROTECTIVENESS STATEMENT
Site wide Protectiveness Statement
Protectiveness Determination:
Short-term Protective
Protectiveness Statement:
The remedy at the Parker Landfill Superfund Site currently protects human health and the
environment because there is no current use of or exposure to site media containing contaminant
concentrations exceeding applicable criteria. However, in order for the remedy to be protective
in the long-term, institutional controls must be expanded and contaminant concentrations and
trends (i.e., VOCs and 1,4-dioxane) must continue to be monitored and evaluated. Groundwater
plume migration west of the landfill needs to be investigated and evaluated to determine the
current nature and extent of groundwater contamination at the Site. Landfill repairs are
necessary to address an area of settlement at location GW-4. All groundwater data must be
evaluated for future potential vapor intrusion issues.
VII. NEXT REVIEW
The next FYR report for the Parker Landfill Superfund Site is required five years from the completion
date of this review. Therefore, the next five-year review should be completed by September 30, 2019.
51
Parker Landfill Superfund Site
Third Five-Year Review Report
September 2014
-------
FIGURES
-------
b
a?
20QQ
SCALE IN FEET
4000
VERMONT TOPOGRAPHIC MAPS, 1:24000 EDITION. 2003
REASON, VERMONT CENTER FOR GEOGRAPHIC INFORMATION
URS
UBS Cwpanrtkwi
477 Cengnaae St
Portland, ME 04101
Td: 207.879.7^66
Fax: 207.B7R7685
vvw.urvccrp.com
QJENT:
VERMONT AMERICAN CORPORATION
PARKER LANDFILL
SITE LOCUS
FKMRt
1
-------
WELL LOCATIONS SURVEYED BY URS
CORPORATION BETWEEN MARCH 2D00 AND
OCTOBER 2005.
COLOR ORTHOPHOTO FROM NATIONAL
AGRICULTURAL IMAGERY PROGRAM, VERMONT"
CENTER FOR GEOGRAPHIC INFORMATION, INC.
1:40000 <1 METER RESOLUTION) TRUE COLOR*
COLLECTED IN 2009.
URS
URS Corporation
477 Congress Street. Suits 900
Portland, ME 04101-3463
Trt: 207.679.7606
Foe 2Q7.fl7B.7883
w^w, urecorp.com
400
SCALE IN FEET
800
PROJECT Hft
39460936
EES at
FS
APPROVE*
MW
FS
scme iป _ 400'
M1E DEC 2013
LTMP_2013
OJENT:
VERMONT AMERICAN CORPORATION
PARKER LANDFILL
LYNDONVILLE, VERMONT
to
SITE PLAN AND
MONITORING LOCATIONS
FIGURE HOu
-------
Tt
8
B137B
PKR-GW-B137B
10/to/13
PKRGW-B113BB
10/01/13
SWDA
j^ph^d/4Mgthj(phyQ<
ฆฆ
PKR-GWOil DB
10/03/13
PKR-CW-B103A
10/02/13
181310
PKRCW-B1BGA
10/02/13
;qQ0510]
PKR-GW-B1+3S
10/03/13
0*003
0.002
FORMER
a LOCATION
Hor iws-2
Trkfrloroซthซnt
! j
PKR-Gซf-B10OG
IGCL 10/32/13
PKR-SH-B136B
10/04/13
0.003
Msthyten* Chloridi
0.005
ra.005B7l
rQ.07041
Trichlorpgth*nซ
[0.041i]
Vlnyi cNqid*
dป-1,2-0fchlgrorthซnซ
0.070
B136C
Trichlgroซthfnซ
rg-ozsn
Vinyl cWsrid*
* gปป~1,2Pfcftlgroปthปnซ
ro.0111
[0.03741
B130B
TOR
mq/L
IGCL
PKR-GW-B13SB
10/&*
1
B14BB
SEt
IGa
ซ .
PKR-GW-B14ฎ
10/02/13
TrfcNcroethena
0.005
0.0090]
Trichloroathซnซ
aoos
[0.0872]
Vfrijrf chfcrfde
0.002
0.602"
Vfryrf chloride
0.002
[oป3741
da-1,2Ofchloroathcne
0.070
0.933
ds-1,2-DWikroflthenfl
ao7o
[0,675]
URS
URS Corporator
477 Con areas 5trwt, 5ufte 900
Peril and, ME 04101-3453
Tel: 207.B79.76SG
Fasc 207.fl7S.7BB5
wviv-urvcorp-com
SCALE IN FEET
HKT HQ: _ _ . _ _ ___
39460936
CUBdi
VERMONT AMERICAN CORPORATION
E3M FS
SMlฃ: y = 400'
PROJECT;
PARKER LANDFILL
LYNDONVILLE, VERMONT
M1t DEC 2013
DRAW: pg
L7MP_2013
LEGEND
MANAGEMENT OF MIGRATION
WELL GROUP (ANNUAL SAMPLING)
MANAGEMENT OF MIGRATION
WELL GROUP (5-YEAR SAMPLING)
BNA MONFTQRING WELL GROUP
MILLIGRAMS PER LITER
INTERIM GROUNDWATER
CLEANUP LEVEL
CONCENTRATION EXCEEDS IGCL
ESTIMATED CONCENTRATION
_ APPROXIMATE EXTENT OF IGCL
EXCEEDANCES, ALL DEPTH ZONES
WELL SCREEN ZONE
SO SHALLOW OVERBURDEN
TOR TOP-OF-ROCK
BR BEDROCK
~
~
*
(mg/L)
IGCL
[ ]
J
SOURCFS:
WELL LOCATIONS SURVEYED BY URS CORPORATION
BETWEEN MARCH ZOQO AND OCTOBER ZOOS.
COLOR ORTHOPHOTO FROM NATIONAL AGRICULTURAL
IMAGERY PROGRAM. VERMONT CENTER FOR
GEOGRAPHIC INFORMATION, INC. 1:40000 (1 MEIER
RESOLUTION] TRUE COLOR, COLLECTED IN 2009.
IGCLs LISTED ARE BASED ON VALUES PF^SENTED IN
THE RECORD OF DECISION (EPA. 1885), MAXIMUM
CONTAMINANT LEVELS (EPA, 2009), AND VERMONT
PRIMARY GROUNDWATER QUALITY STANDARDS (VTANR,
2005).
DRAFT
400 800
SCALE IN FEET
EXCEEDANCES OF IGCLs
FOR VOCs AND SVOCs
IN GROUNDWATER
2013
-------
Tt
i
raagsn j
i'a.gigg] 4
raoosflpi
ro-gggi j
racsszsi
PKK-GW-BflSB
10/01/1J
SWDA
lphgnq(/4MgthjJphgrol
PKR-CW011BB
10/03/13
PKR-CWB103 A
10/02/13
10131C
FKRCW-BIBdA
10/02/13
PKR-GW-B145B
10/03/13
0-003
0.002
.0-00376
10145C
PKRGWB143C
10/03/13
0-0432'
PKR-G#-0180C
IGCL 10/02/13
10/04/13
IMsthykns Chlorkh
0.002
[0.0351
[q.24P1
[0.0251]
PKR-GW-B14ffi
10/02/13
U374]
0137B
mgA
IGCL
PKR-GW-0137B
10/03/13
MDhwana
0.003
[0.015]
Bซnzenซ
0.005
!0.0033Bl
. ' i ' - ฆ ฆ
FORMER
LOCATION
OF IWS-2
WQm -a
1
ฆJ V w'B1ซA 2
B1MC
rW XI**
0172B
mc/L
IGa
PKR-GW-Bnasr
1O/02/13
Trtdiloroetftone
0.005
0.5531
Vinyl chloride
0.002
0.0933]
cIh-1 ,2-Drchloroalhane
0.070
1.07]
4
- -^i
0173B
TOR
mqA
IGCL
PKRGW-B1730 uf
10/02/13
Banzona
0.009
[0.005371
TrUilorosthana
0.005
[0.0704]
Vinyl chlorido
0.002
[0.0419]
ciป1,2Dishlorerthww
0.070
f 0.170] [
HB12DG
a
igcl
PKR-GW-B120C
10/03/13
1(4Oloxana
0.003
;aoi3i
Trkhtororiheno
0.005
.0.228
IB120D
0R*
|mflA
IGCL
PKR-GW-B1200 "Z
10/03/13
11,4 OlOKOTfl
0.003
0,027]
IW15I chloride
0.002
O.OO+14] I I
LEGEND
MANAGEMENT OF MIGRATION
WELL GROUP (ANNUAL SAMPUNG)
MANAGEMENT OF MIGRATION
WELL GROUP (5-YEAR SAMPUNG)
BNA MONHTORING WELL GROUP
MILLIGRAMS PER LITER
CZZ]
BI4S8-R
I?"/
rnjA
IGCL
PKR-GW-0149B- R
10^32/13
Trichloroetti
m
m
-------
60
50
40
30
0s-
20
10
0
Figure 5
Gas Probe Monitoring for GP-34 Cluster - November 2006 to December 2013
Parker Landfill
M
\ ^\/\ / -
ฆGP-34B (Shallow)
GP-34A (Deep)
Barometric Pressure
cS' cO C?* c?7 & <$> <3* Q3 cj3 q3 <$> Q3 <$* jS* -O* _oy
30.0
29.0
28.0
27.0
bjo
X
26.0
25.0
ai
a.
24.0 |
8
ro
ca
23.0
22.0
21.0
20.0
'ปyy 'y> "y'
^ o>\ V o>\ V Ax
Monitoring Date
-------
APPENDIX A - EXISTING SITE INFORMATION
A. SITE CHRONOLOGY
The chronology of all significant Site events and dates is included in Table A-l.
Table A-l
Site Chronology
Event
Date
Permitted Solid Waste Disposal at Site
October 1971 through 1992
Monitoring wells installed by landfill operator
1979
Preliminary Assessment/Uncontrolled Hazardous Waste Site Evaluation
1984-1985
by VTAEC
Proposed NPL listing date
June 21, 1988
NPL listing date
February 16, 1990
Consent Order for RI/FS
August 1990
Initial Site Characterization activities by ESE, Inc.
Aug. 1990-July 1991
Initial Site Characterization Report by ESE, Inc.
February 10, 1992
RI/FS
July 1990-June 1991
RI report complete
May 2, 1994
FS report complete
June 1, 1994
ROD Signature
April 4, 1995
Quarterly Groundwater Monitoring
1999-2007
First Five-Year Review Report
September 2004
Annual Groundwater Monitoring and Reporting
2007-present
Second Five-Year Review Report
September 2009
Landfill Cap
AOC for Remedial Design
December 1996
Cap design start
1997
Cap design complete
1999
CD for Remedial Action (cap)
April 1999
Cap Construction start
April 1999
Cap Construction end
November 2000
Cap Remedy complete
December 2001
Groundwater Treatment Remedy
Unilateral Administrative Order for Remedial Design and Remedial
Action
April 26, 1999
Class IV Groundwater Reclassification Petition
May 31,2001
Draft Institutional Control Report
December 13, 2002
VTDEC Reclassification of Groundwater to Class IV
November 6, 2003
Downgradient Pre-Design Technical Report by URS
November 7, 2003
Draft Source Area Pre-Design Technical Report by URS
January 9, 2004
L2014-202
1
Appendix A
-------
Table A-l
Site Chronology
Event
Date
Alternative Technology Analysis and Evaluation by URS
July 14, 2004
Declaration for the ESD
July 2004
EPA Approval of the Remedial Design
September 22, 2004
PRB and BNA groundwater remediation system construction begins
September 2004
PRB and BNA system construction complete
September 2005
Overall Remedy
Preliminary Construction Completion Report signed
September 2005
First full-scale BNA groundwater remediation system injection event
November 2005
Final Inspection performed and Site is determined to be Operational and
Functional
May 2006
Second full-scale BNA groundwater remediation system injection event
September 2007
Third full-scale BNA groundwater remediation system injection event
September 2009
Lyndon Amendment to draft BNA Operation and Maintenance Plan
September 2011
Fourth full-scale BNA groundwater remediation system injection event
(initial event employing Slow Release Substrate [SRSฎ])
September 2011
B. BACKGROUND
Physical Characteristics
Figure 1 in the FYR shows the location of the Parker Landfill Superfund Site on the southern side of
Lily Pond Road in the Town of Lyndon, Caledonia County, Vermont. The current Site configuration is
shown on Figure 2 in the FYR. The Site consists of 25 acres located in an area of hilly terrain in the
southeast portion of Lyndon, approximately 0.2 miles southeast of Lily Pond. An unnamed stream
traverses the Site from northeast to southwest, joining a larger unnamed stream immediately southwest
of the Site that flows to the Passumpsic River approximately H-mile southwest of the Site. The Site is
accessed via four roads: three that begin at Lily Pond Road and intersect the southwest and west sides of
the Site, and one entering the Site from the east.
The Site is surrounded by residential areas to the north, wooded, hilly areas to the east, wooded areas
and agricultural land to the south, and residential areas to the west. Pastures and cropland are located to
the south of the Site, beyond Brown Farm Road. A nursing home and a private school are located
approximately '/2-mile southwest of the Site, on Red Village Road. Residential properties located in the
vicinity of the Site include three mobile home parks located immediately northwest of the Site and
assisted living homes located downgradient of the Site.
Land, Resource, Operational and Regulatory History
Historical records reviewed by ESE as part of a 1992 Initial Site Characterization indicate that prior to
permitted landfilling of the Site, the Site area consisted of a borrow pit for the mining of sands, and was
used as a Town disposal area starting in the late 1950s.
L2014-202
2
Appendix A
-------
A Land Use Permit to operate a solid waste disposal facility at the Site was granted by the Vermont
District No. 7 Environmental Commission on July 17, 1971. Approval to operate as a sanitary landfill
was granted under the authority of the Vermont Health Regulations on October 20, 1971. Operation of
the landfill began in 1972, and continued through 1992. There were four distinct waste disposal areas at
the Site; all were unlined. The largest waste disposal area is the solid waste disposal area (SWDA),
comprising approximately 14 acres. Adjacent to the SWDA are three smaller industrial waste areas
(IWS-1, IWS, 2 and IWS-3), located on the west, south, and east sides of the SWDA, respectively.
During a Preliminary Assessment completed in 1985, the Vermont Agency of Environmental
Conservation (VTAEC; currently VTDEC) discovered that prior to 1983, uncontrolled disposal of
industrial wastes occurred at the Site, resulting in the landfill receiving approximately 1,330,300 gallons
of liquid industrial wastes and 688,900 kilograms of solid, semi-liquid and liquid industrial wastes.
These wastes included waste oils, plating solutions, degreasers, paint sludge, coolant oils, sodium
hydroxide, and TCE or 1,1,1-TCA sludge.
As a result of the findings of the VTAEC during the 1985 Preliminary Assessment and Uncontrolled
Hazardous Waste Site Evaluation, the Site was referred to EPA for inclusion in the National Priorities
List (NPL) under CERCLA. EPA added the Site to the NPL as a Superfund Site on February 16, 1990.
An Administrative Order by Consent for the Remedial Investigation/Feasibility Study (RI/FS) was
issued by EPA to the Respondents/PRPs on August 8, 1990. The August 1990 Consent Order for the
RI/FS included an order that operations at the landfill must cease on or before July 1, 1992.
The Village of Lyndonville operates a municipal water system that supplies water to the residences
north and west of the Site, including the nearby mobile homes. In the Fall of 1991, this municipal water
supply line was extended to properties located along Red Village Road, less than '/2-mile southwest of
the Site. Prior to this, these properties utilized private wells.
Based on the results of RI groundwater studies, it was predicted that groundwater contamination could
be adequately addressed by a combination of source control (i.e., capping of the waste areas),
groundwater source controls (i.e., pump and treat system to address contaminants from source area), and
natural attenuation. Cap construction began in 1999, approximately five years after the completion of
the RI and four years after the signing of the ROD.
According to Site reports from the early 1990s, the private drinking water wells located within a three-
mile radius of the Site served a population of approximately 525. However, due to the implementation
of institutional controls near the Site and the expansion of the Village of Lyndonville's municipal water
supply infrastructure, this number is expected to be much lower now. The municipal water supply wells
that serve as a source of drinking water for the Village of Lyndonville are located 1.75 miles north of the
Site, and provide water for a population of over 3,200.
Potential human and ecological receptors to Site contamination include users of private wells up to 0.5
mile downgradient from the Site, recreational users of the Passumpsic River and the unnamed tributaries
flowing from the Site, and biota inhabiting the Passumpsic River and related tributaries.
Geology and Hydrology
Based on the results of the RI/FS, the Site area is underlain by four major surficial geologic deposits. An
esker (a linear landform resulting from deposition by glacial meltwater) located to the west of the
L2014-202
3
Appendix A
-------
Landfill, consists of coarse to medium sand, gravel, and cobbles in graded and cross-bedded deposits.
An esker delta deposit, consisting of cross-bedded coarse to fine sand and gravel, trends west to east just
south of the Landfill. A Proximal Unit, consisting of medium to fine sand and silty fine sand, extends in
an easterly direction from the esker. This Proximal Unit is extensive throughout the area under
investigation and underlies the SWDA and IWS areas. A Distal Unit, consisting of very fine sand, silt,
and clay overlies the lower Proximal Unit and is overlain by an upper Proximal Unit in the immediate
vicinity of the SWDA, IWS 1, and IWS 2. Both the Proximal and Distal Units pinch out against the
steeply rising bedrock just east of the Landfill.
The surficial deposits are underlain by two fractured bedrock formations. The Waits River Formation, to
the west, consists of a calcarious phyllite. The Gile Mountain Formation, to the east, consists of a
siliceous phyllite. The contact of these two formations is gradational and is located immediately east of
the SWDA.
The Site contains three groundwater flow paths. The upper portion (upper Proximal) of the aquifer
underlying the Site has a southwesterly groundwater flow direction. The lower portion (Proximal) of the
aquifer exhibits a regional groundwater flow in a westerly direction. The fractured bedrock aquifer
exhibits groundwater flowing in a south/southwesterly direction. Shallow groundwater flow in the upper
Proximal portion of the aquifer at IWS 3 is southwest toward IWS 2. Flow in the lower Proximal unit,
the principal water-bearing unit underlying much of the Site, is to the west-southwest. It is believed that
groundwater flow in the fractured bedrock is generally south/southwest and could be related to a fracture
zone along the eastern margin of the SWDA.
History of Contamination
Between 1979 and 1984, routine groundwater monitoring conducted by the VTDEC indicated the
presence of chlorinated VOCs in the groundwater and in the unnamed stream adjacent to the landfill. In
1984, VOCs were detected at concentrations exceeding federal MCLs in groundwater in five private
wells approximately 0.5 miles southwest of the Site.
In 1985, VTDEC informed four PRPs of their responsibility for performing investigative work and
remediation at the Site. Following EPA's placement of the Site on the NPL, between 1990 and 1994,
the PRP consultant, ESE, completed and performed the RI/FS at the Site. The RI/FS report summarized
the field investigations, described the nature and extent of wastes and related contaminant source areas,
and described subsurface hydrogeology at the Site assessed as part of the field investigation. The
SWDA was estimated to contain approximately 2 million cubic yards of waste, and based on field
studies, was estimated to be about 55 feet deep on average. Based on observations during the RI/FS, the
SWDA was considered a diffuse source of leachate and contaminants to soil and groundwater. RI/FS
assessment results indicated that the IWS areas, due to their history of accepting industrial wastes, were
serving as additional, discrete source areas from which the VOCs were leaching into Site soils and
groundwater.
Basis for Taking Action
According to the ROD, COCs for Site groundwater were designated as those constituents detected
during the RI at concentrations exceeding cleanup goals based on ARARs. COCs include PCE, TCE,
cis-l,2-DCE, 1,2-dichloropropane, 1,2-dichloroethane, benzene, vinyl chloride, and 2-butanone (all
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VOCs), as well as, 3-methylphenol, 4-methylphenol, chromium, nickel, manganese, and vanadium.
During the RI, these contaminants were detected at the highest concentrations at the source area, and
were thought to be decreasing in concentration with distance from the landfill as a result of diffusion and
natural degradation processes.
Based on the results of RI groundwater studies, it was predicted that groundwater contamination could
be adequately addressed by a combination of source control (i.e., capping of the waste areas),
groundwater source controls (i.e., pump and treat system to address contaminants from source area), and
natural attenuation. Cap construction began in 1999, approximately five years after the RI and four
years after the signing of the ROD. The ROD specified that the groundwater treatment was to be
selected based on pre-design studies conducted subsequent to the RI. Post-cap groundwater monitoring
confirmed the effectiveness of the cap in reducing the mass loading of contaminants to groundwater in
the source area. However, monitoring data suggested there had not been a significant reduction in
contaminant concentrations in the downgradient plume due to natural attenuation. Chlorinated VOCs
such as TCE and cis-l,2-DCE were detected at significantly higher concentrations than previously
detected in the area between the landfill and the Passumpsic River.
C. REMEDIAL ACTIONS
Remedy Selection
The ROD for the Parker Landfill Site was signed on April 4, 1995. The original remedies selected
within the ROD to address contamination at the Parker Landfill Superfund Site consisted of (1) multi-
layer caps (including gas management) over the SWDA and IWS areas, and (2) source control
groundwater extraction and treatment. The ROD also required the installation of additional groundwater
monitoring wells, long-term monitoring of groundwater, surface water and sediment in the vicinity of
the Site, and five-year Site reviews.
The 1995 ROD describes the remedy required for the Site as follows:
Construction of multi-layer (RCRA subtitle C) caps over the SWDA and IWS areas;
Installation and operation of a gas collection system to reduce landfill gas accumulation and
lateral migration below the SWDA and IWS areas that were capped;
Installation of a source control groundwater treatment system to address overburden and bedrock
contamination, of which the configuration was to be determined during a pre-design phase;
Conducting long-term sampling and analysis of groundwater, surface water and sediment to
assess compliance with the groundwater cleanup levels through natural attenuation and to ensure
surface water and sediments in nearby brooks/river have not been adversely impacted;
Institutional controls to protect the cap and to restrict groundwater use, including the extension
of municipal water service to all homes potentially affected by contamination; and
Review of the Site every five years to evaluate the effectiveness of the remedy in ensuring the
protection of human health and the environment.
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Although the ROD specified that groundwater extraction wells would be placed in both the overburden
and bedrock aquifers at the source area as part of the groundwater remedy, specific treatment
technologies to treat the extracted groundwater and methods for discharge of treated water were to be
determined during the design phase, in order to ensure that the most effective and least costly alternative
is used. Under a 1999 unilateral order, pre-design studies and groundwater monitoring were conducted.
A revised Feasibility Study was completed under this order in July 2004, to both address current
conditions at the Site and to evaluate the most contemporary technologies available to best meet the
objectives identified in the ROD. In July 2004, EPA issued an ESD for the groundwater component of
the ROD remedy. The adjustment in the groundwater remedy was due to changes in the extent of the
downgradient groundwater plume and the emergence of more effective treatment technologies to
address source area groundwater contamination. The ESD called for active treatment of the source area
groundwater plume using a permeable reactive barrier wall, and active in-situ treatment of the
downgradient plume using enhanced bioremediation.
Cay Remedy
The RAOs for the cap remedy (i.e., capping SWDA and IWS areas) are as follows:
Minimize, to the extent practicable, the potential for transfer of hazardous substances from the
soil and solid waste into the groundwater, surface water and sediment;
Prevent direct contact/ingestion of soil or solid waste posing a potential total cancer risk greater
than 10"4 to 10"6, or a potential hazard index greater than one; and
Comply with federal and state ARARs.
Groundwater Remedy
The RAOs for the groundwater remedy (i.e., source control groundwater treatment) are as follows:
Prevent ingestion of groundwater containing COCs in excess of federal or state standards, or
posing a potential total cancer risk greater than 10"4 to 10"6, or a potential hazard index greater
than one; and
Comply with federal and state ARARs.
Although EPA issued an ESD for the groundwater component of the ROD remedy in July 2004, the
RAOs for the groundwater remedy remained unchanged.
The cleanup levels selected, as identified in the ROD, are summarized in the following table:
Table A-2
ROD-Specified Cleanup Levels
Contaminant of Concern
Interim Cleanup Level (jig/L)
Basis
1,1 -Dichloroethene
7
MCLG
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Table A-2
ROD-Specified Cleanup Levels
Contaminant of Concern
Interim Cleanup Level (jig/L)
Basis
1,2-Dichloroethene
70
MCL
1,1,1 -Trichloroethane
200
MCLG
2-Butanone (MEK)
170
VPGQS
4-Methylphenol
200
Risk-Based
Acetone
3,700
Risk-Based
Benzene
5
MCL
Methylene Chloride
5
MCL
T etrachl oroethene
0.7
VPGQS
Trichloroethene
5
MCL
Vinyl Chloride
2
MCL
Bis (2-Ethylhexyl)
Phthalate
6
MCL
Antimony
6
MCL
Arsenic
50
MCL
Beryllium
4
MCL
Chromium (Hexavalent)
50
VPGQS
Manganese
180
Risk-Based
Nickel
100
MCL
Vanadium
0.2
Risk-Based
MCL - Maximum Contaminant Level
MCLG - Maximum Contaminant Level Goal
VPGQS - Vermont Primary Groundwater Quality Standard
Remedy Implementation
Landfill Cay Remedy Implementation
Construction of the cap began in April 1999 and was completed in December 2001. The design
components of the cap were set forth in the Landfill Cap Remedial Design Statement of Work dated
November 1996. Industrial wastes and contaminated soils were excavated from IWS-2 in June 1999 and
placed into the SWDA area prior to capping, eliminating the need for a separate cap over IWS-2. A
continuous multi-layer cap was constructed over SWDA and IWS-1 between May 1999 and October
2000. A separate multi-layer cap was constructed over IWS-3. The landfill gas management system
was constructed to control gas generated in the SWDA and IWS-1 areas (no gas recovery in IWS-3).
The active gas management system consists of 17 gas extraction wells, piping and blowers, and an
enclosed flare to destroy VOCs and methane. A compensatory wetland was constructed to mitigate
wetlands lost during construction of the cap. Institutional controls associated with the landfill cap
remedy have been defined and have been implemented; however expansion of the institutional controls
is required based on current IGCL exceedances and VOC trends.
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Groundwater Remedy Implementation
Source Area Groundwater - Permeable Reactive Barrier
The PRB technology uses a reactive media of granular zero-valent iron to treat chlorinated VOCs in
groundwater by permanently reducing the volume and toxicity of the contaminants through reductive
de-halogenation, as electrons transfer from the iron to halogenated VOCs at the iron surface contact
point. The result is halogen ions being replaced by hydrogen species that yield the non-halogenated
compounds ethene or ethane. These, in turn, are mineralized by bio-degradation in the groundwater
downgradient of the PRB treatment cell.
The "Draft Source Area Pre-Design Technical Report" dated January 9, 2004, evaluated the feasibility
of a zero-valent iron PRB wall to passively intercept the upgradient portion of the VOC-contaminated
plume, and to effectively reduce concentrations of chlorinated VOCs in groundwater at the source area.
This report concluded, based on column testing and bench-scale studies, that a zero-valent iron PRB
would be effective in reducing concentrations of chlorinated VOCs to below the groundwater cleanup
goals at the Site.
The PRB was installed using an open trench technique with excavation by an extended-arm backhoe,
using a bio-polymer slurry for support (guar gum). The trench is approximately 2.5 feet in width and
approximately 235 feet in length. The trench depth is approximately 62 feet deep, decreasing linearly to
an approximate 30-foot depth at the eastern end. The trench was backfilled with a granular iron/sand
blend.
The PRB is comprised of four sections containing different iron/sand blends. Iron percentages by
weight of 34.5 percent, 61.2 percent, 100 percent, and 51.3 percent correspond to different VOC
contaminant zones. This material was placed in the trench continuously using a tremie pipe to an
elevation of two feet above the high groundwater table, and was backfilled with sand. In order to
adequately monitor the performance of the PRB and to reduce contaminant concentrations in the
groundwater, additional monitoring well clusters were installed.
A total of eight monitoring wells, in three well clusters were installed within the trench during
construction. Each cluster was bound together with nylon ties surrounding a section of reinforced steel
bar and suspended in the excavation as the trench was backfilled with the iron/sand blend. These wells
are 1-inch diameter and constructed using a 10-foot polyvinyl chloride (PVC) screen and riser. In
addition, 21 monitoring wells in eight clusters were installed at strategic locations around the PRB
perimeter. All wells were tested during construction to assess groundwater quality and geochemistry.
The initial testing indicates that VOC concentrations have reduced and that there is an elevated
concentration of ethene/ethane. As designed, a reactive zone was established and de-chlorination is
occurring. O&M is currently being performed by the PRPs.
The physical extent of the PRB cell constructed to intercept contaminated groundwater is noted above.
The cell was constructed adjacent to the south-eastern edge of the landfill. In order to construct the
PRB, the following activities occurred: 1) relocation of a power line; 2) up-grade of an access road; 3)
abandonment of select groundwater monitoring wells; 4) extension of an existing stream culvert; 5) re-
grading of the area where the PRB was located (including erosion and sediment control measures and
seeding); and 6) construction of a gravel work pad and guide wall.
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Downgradient Groundwater - Bio-Enhanced Natural Attenuation
Construction of the bio-enhanced natural attenuation technology included limited modification of the
terrain in the downgradient area to improve access to install a series of injection/extraction wells. Area
preparation included limited clearing of trees and brush, construction of an access road, and the
extension of an electrical power line from Lily Pond Road. The wells installed span a distance of
approximately 500 feet and are located approximately 40 feet apart. To meet the cleanup objectives,
groundwater is periodically withdrawn from the extraction wells and amended using a sodium
lactate/nutrient solution and re-injected back into the overburden groundwater via injection wells. Based
on the pre-design test results this solution contains: 60% sodium lactate; ammonium bromide;
ammonium carbonate; and ammonium phosphate. Full scale applications have been conducted in
November 2005, September 2007 and September 2009.
Although initial applications were successful, due to the technological advancements in the effectiveness
of biodegradation compounds, a review of alternative organic carbon sources was conducted in 2011. As
a result, the Draft BNA O&M Plan was amended in September 2011 to include the use of Slow Release
Substrate (SRSฎ). The application of SRS, which contains sodium lactate, yeast extract, nutrients, 60-
percent by weight emulsified soybean oil and surfactants, was conducted for the first time in September
2011.
As with the PRB technology, a post implementation monitoring program is ongoing to track the induced
effects within the groundwater system. This includes quantifying geochemical field parameters that
contribute to, or are indicators of, the degradation of the chlorinated organic contaminants.
Compensatory Wetland
The PRB work pad construction required removing approximately 0.26 acres of wetland, as
characterized in a Wetland Investigation Summary letter submitted to EPA on October 29, 2004. A
compensatory wetland was constructed along the west side of the unnamed stream approximately 1,550
feet downstream from the PRB. This location is within the 50-foot-wide conservation easement located
adjacent to the unnamed stream and was selected based on guidance from EPA, the U.S. Fish and
Wildlife Service and the VTDEC.
A design plan for the compensatory wetland was prepared by URS and submitted for review and
comment by EPA and the VTDEC on August 17, 2005. Based on both federal and state comments,
URS revised the plan and resubmitted it on August 18, 2005. EPA approved the design on August 19,
2005. The compensatory wetland is 0.44 acres in size. This ratio was approved by EPA and the
VTDEC based on the designated space available within the conservation easement area. With this
approval, the wetland requirements are achieved.
Wetland construction commenced on August 23, 2005. An existing log pile was relocated to an area
located beyond the conservation easement area. This work was completed on August 29, 2005.
Institutional Controls
Institutional controls have been partially implemented. Institutional controls consist of easements and
enforceable local or state regulations to restrict groundwater use. The area of restricted groundwater use
was specified in the ROD to extend from the upgradient perimeter of the landfill to all downgradient
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boundaries of the contaminant plume (both in overburden and bedrock aquifers). The restricted
groundwater use area includes a buffer zone around the contaminated area, to prevent potential
spreading of the plume caused by drawdown in active private wells outside the area.
In 2002, a municipal water line was constructed to service the residences within the proposed
institutional control boundary. The reclassification of groundwater from a Class III (all groundwater) to
Class IV (not potable; suitable for some industrial and agricultural use) category was established for the
119-acre area including the landfill and downgradient plume in November 2003. The Town of Lyndon
has updated their zoning bylaws to establish an Institutional Control Area that mirrors the Groundwater
Reclassification Area as shown in Attachment B of the Findings of Fact and Reclassification Order,
Proposed Groundwater Reclassification at the Parker Landfill, Lyndon, Vermont dated August 23, 2003
(see Appendix B). However, the Groundwater Reclassification Area was delineated based on data
collected in 2000 and downgradient IGCL exceedances and increasing VOC concentration trends,
including 1,4-dioxane and particularly in the top-of-rock groundwater system, continue to be evident
west-southwest of the SWDA. These data suggest a need for additional monitoring locations and/or
installation of additional wells downgradient of the Site. As a result, the current institutional controls
that have been established do not encompass the area of recent IGCL exceedances as required by the
ROD.
System Operation/Operation and Maintenance
Operations and maintenance, including monitoring are conducted for both the landfill cap and
groundwater remedies, as further described below.
Cay Remedy O&M
O&M for the cap remedy primarily consists of operating the flare system to burn collected methane gas
and maintenance of the cap. Maintenance of the cap includes mowing, cleaning out drainage swales,
repairing erosion damage, replanting grass (as needed) and removing animals that burrowed in the cap.
Periodic gas probe monitoring is also conducted to monitor the migration of methane gas from areas
outside of the cap.
Groundwater Remedy O&M
O&M for the groundwater remedies primarily consists of groundwater, surface water, and sediment
monitoring. Groundwater monitoring wells are grouped into the MOM, PRB, and BNA monitoring well
groups. Annual groundwater monitoring of 32 MOM wells, 29 PRB wells, and eight BNA wells is
currently conducted. Every five years, as part of the FYR, an additional 28 MOM wells are also
monitored.
Surface water sampling is conducted on an annual basis and sediment sampling is currently conducted
every five years, as part of the FYR.
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Appendix A
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APPENDIX B
Copy of Findings of Fact & Reclassification Order
-------
State of Vermont
Dopartnwm of Fish and UMife
OtpMBitnt of Forest*. Parks mi Recreatim
Oepartowsnt of Environmental ConMrvafon
Sm Otologist
RELAY SERVICE FOR THE HEARING IMPAIRED
1-800-25^01ป1 TDO>Voioป
1-800-253-0188 \toio#>TOO
AGENCY OF NATURAL RESOURCES
Dep:irtm500. if you have more specific questions on the status of the site, please contact John Schmcltzer ol the
Waste Management Division at. (802) 241-3886.
Sincerely, ,
Tina Hubbard
Drinking Water Source Protection Specialist *
c: Groundwater Coordinating Committee
Regional Offices - Sane/Essex Jct/Pittstord/Ri.tl wrtSrmqir a'St Johnsbury
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Findings of Fact & Reclassification Order
Proposed Groundwater Reclassification at the Parker Landfill
Lyndon, Vermont
August 21. 2003
Prepared by:
The Vermont Agency of Natural Resources
and the
Vermont Groundwater Coordinating Committee
-------
Findings of Fact & Reclassification Order
Parker Landfill, Lyndon, Vermont
Introduction
I his document represents the Vermont Agency of Natural Resources' findings and determination
to reclassify groundwater from Class iif to Class IV at the Parker Landfill, located in Lyndon,
Vermoni (see map, Attachment A), i he 250-aere reclassification area is shown in map view in
Attachment B. 1 he findings are based on the considerations outlined in Section 12-403 of the
Vermont Groundwater Protection Rule and Strategy, effective January 20, 2000. A copy of the
rule is available online at mvw.vermontdri.nkinawater.org or by contacting the Department of
Environmental Conservation, Water Supply Division, 103 South Main Street. Waterbury.
Vermont 05671-0403 or at (802) 241-3400.
Copies of the petition to reclassify and other supporting documents are available at the
Waterbury Office of the Department of Environmental Conservation, Waste Management
Division. Much of the information contained here was obtained from the petition to reclassify
groundwater, prepared by URS Corporation (March 25, 2002).
Background .
The Parker Landfill is located on approximately 25 acres situated on the east side of Lily Pond
Koad m the southeast portion of the I own oi Lyndon. Caledonia County. Vermont in vegetated,
hilly terrain. Residences border the north and northwest portions of the property. The land
slopes westward toward the Passumpsic River. Portions of the Parker Property are currently used
by tne owner as a storage and maintenance garage for heavy equipment. Part of the property is
also planted in hay.
The Parker Landfill was approved as a disposal facility for solid waste in 1971. Ray O, Parker &
Sons, Inc. began operating the facility in 1972. Prior to 1972. the disposal area was used as a
sand pit and a town disposal area. The industrial wastes disposed at the site included
trichoroethylcne, sodium hydroxide, 1,1,1- trichloroethane. acetone, lacquer and stain sludge,
paint sludge, tetrachloroelhane. barium chloride, chromium, nickel plating rinse waters, polyester
resin, mercury, electroplating sludge and water soluble coolants. Approximately 1.330,300
gallons of liquid industrial wastes and 688,900 kilograms of liquid, semi-solid, and solid
industrial wastes were disposed of at the site between 1972 and 1983. {Source: EPA Record of
Decision, 1995]
In February 1990, Parker Landfill was placed on the National Priorities List. In 1999. EPA
signed a I ns lateral Administrative Order (UAO) with a potentially responsible partv, Vermont
American Corporation, requiring groundwater clean-up. Under a Consent Decree with other
potentially responsible parties, the waste was covered with a multi-layered cap. The cap was
completed in the summer of 2001.
1
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The overburden at the site consists of glaeio-fluvial and giacio-lacusirine materials. The waste
units are situated on top of a thin sandy unit that has a perched water table. Directly beneath the
waste units, the thin sandy zone is underlain by a much thicker silly layer that appears to have
acted as a barrier to downward contaminant migration. Downgradient from the landfill, near the
Passumpsic River, the silty layer pinches out and a thick, transmissive. sandy formation
comprises the overburden. Bedrock in the area is metamorphic, and includes the Waits River
and Gile Mountain formations.
Surface water runoff from the site generally flows west toward the Passumpsic River. An
unnamed stream flows in a southwesterly direction along the east side of the landfill before
joining two other unnamed streams south of the landfill. These streams discharge to the
Passumpsic River. The groundwater How system from the landfill also converges on the
Passumpsic River. .Upward hydraulic gradients from nested wells near the river indicate that the
river is a groundwater discharge location.
During a site inspection in 1984, the State detected contaminants in a stream bordering the
landfill, in groundwater at the landfill, and in four private wells located less than a mile from the
landfill. Subsequent investigations have shown that soil, soil gas, surface water and groundwater
at the site are contaminated with a wide range of chemicals. As part of groundwater
investigations, about 120 monitoring wells have been drilled and tested. The main contaminants
of concern in the groundwater are trichloroelhylene (TCE) and its daughter products.
Concentrations greater than 10,000 ug/L of TCE have been seen in shallow wells near the waste
units, suggesting that TCE has likely reached the subsurface in non-aqueous form. Near the
waste units, the highest contaminant concentrations are found in the perched water above the silt
layer. Further down gradient, near the Passumpsic River, contamination is minimal in the
shallow sandy overburden, but wells screened in sand at the top of the bedrock and in upper
portions of the bedrock itself show elevated TCE concentrations. Samples from one top-of-roek
well (R120C) near the river have contained nearly 5,000 ug/L of TCE. T he presence of TCE in
this well cannot be explained entirely by the prevailing groundwater flow pattern, suggesting
dense-nonaqueous-phase liquids may be present in the subsurface.
The reclassification area encompasses 250 acres. It includes a zone where 95% confidence-level
statistics indicate that groundwater is contaminated above the Vermont Groundwater
Enforcement Standards (VGES), and a 200-foot buffer around the upgradient and crossgradient
boundaries of the contamination zone. The downgradient boundary of the reclassification area is
the Passumpsic River.
The UAO between Vermont American and EPA requires groundwater extraction and treatment
as the groundwater clean-up technology, but site investigators are now looking at other treatment
options. Long-term monitoring of groundwater and institutional controls to prevent
inappropriate uses of contaminated land and water at. the site are also required by the UAO.
More than forty wells are currently included in the long-term monitoring program.
All homes and businesses within the reclassification area have been connected to the municipal
water supply. Under the institutional control plan for the site, all private wells identified within
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the reclassification area have been either converted to monitoring wells or abandoned in
accordance with state regulations.
Agency Review . ' .
Below is the Agency of Natural Resources' review of the Parker Landfill site with respect to the
Groundwater Protection Rule and Strategy Section 12-403 Class 1, H. Ill and IV Groundwater
Reclassification Process. This information is based on the following document:
Petition for Groundwater Reclassification, Parker Landfill. Inc., Lyndon, Vermont. tJRS
Corporation, March 25, 2002.
In determining whether or not to reclassify groundwater as Class I, II, III, or IV, the Secretary
shall consider the following:
(1) I he use or potential future use of the groundwater as a public water supply source
Municipal water is available to the properties within the Class IV Groundwater Area and
easements are or will be in place to restrict groundwater use. However, the overburden aquifer is
transmissive and could represent an enticing water supply opportunity to individuals unaware of
contaminant risks. A Class IV designation for the groundwater in the area would provide another
institutional control to prohibit future public water supply development.
(2) TheexteaLfifM ivitv which poses a risk to the groundwater
Disposal of industrial wastes, the high-risk land use which led to the present contamination, was
discontinued in 1983. Solid waste disposal was discontinued in 1992. Residual contamination in
the subsurface from past disposal practices may be serving as a continuing source of groundwater
contamination.
(3) The current water quality of the groundwater
Numerous rounds of groundwater sampling have been performed at the Parker Landfill between
October 1984 and October 2000. About 120 wells have been drilled and tested. The
contaminant zone boundaries have been defined using a 95% confidence level statistic for
monitoring points which exceed the Vermont Groundwater Enforcement Standards (VGES).
Dissolved I Cfc concentrations in groundwater have been detected at levels as high as 5,000 ug/L
sn a deep monitoring well near the Passumpsic River (# B120C). TCE concentrations near the
center of the contamination zone range up to 10,000 ug/L. Over the approximately 125-acre
areal extent of the plume, groundwater quality consistently exceeds the VGES for TCE.
Due to elevated contaminant levels, the groundwater is unsuitable for use as drinking water. The
groundwater should not be used for agricultural, industrial, or commercial uses in situations
where it may cause health risks.
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(4) The availability ol' groundwater in quantities needed for beneficial use
According to the Vermont Groundwater Protection Rule and Strategy, beneficial use refers to
.specific groundwater uses deemed appropriate for a designated groundwater class. Class IV
groundwater is not considered to be a potable water source but may be suitable lor some
agricultural, commercial, or industrial uses,
As noted above, the groundwater in the Class IV Groundwater Area has no beneficial uses at
present. Although the subsurface water resource is capable of yielding a plentiful supply, the on-
site groundwater will be unsuitable for any beneficial use unless it recei ves treatment or until
present levels of contamination are substantially reduced.
Reclassification of the groundwater to Class IV is necessary to protect future users from
inappropriate use of the groundwater for potable supplies. Other protections, such as deed
restrictions or landowner agreements, will prevent other inappropriate beneficial uses of the on-
site groundwater. The Secretary will not issue permits for drinking water supplies within the
Class IV boundary.
(5) The consequences of potential groundwater contamination and the availability of alternate
sources of water
Use of any onsite water source must be avoided until contaminant, concentrations are reduced by
the site remediation system to be constructed and by natural attenuation. A Class IV designation
will prevent development of any water supply requiring a permit from the Secretary. Municipal
water is available as an alternative water source within the Class IV Groundwater Area.
(6) 1 The classification of adjacent surface waters
Groundwater from the site discharges to an unnamed stream and to the Passumpsic River. The
State of Vermont has classified these waters as Class R. Class R waters are considered suitable
for the following uses: water supply with filtration and disinfection; irrigation and other
agricultural uses; swimming, and recreation.
The surface water data indicates that the groundwater contamination is not adversely affecting
the water quality of the Passumpsic River. However, TCE has been detected at low*
concentrations in the samples taken from the unnamed stream near the landfill.
(7) The probability for use as a public water supply source
Although the site could potentially provide high-yield water supplies, it is both unsuitable for use
as a potable supply and unlikely to be needed for such use in the future. The town of Lyndon
gets its water supply from a sand and gravel aquifer on the opposite end of the town. The
municipal water system was expanded this past spring with the addition of one more well at the
well field. In the case of an unanticipated need for an additional public water supply source in
the area, a Class IV designation will prevent the inappropriate development of a public water
supply at the Parker landfill.
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(8) to determining the maximum beneficial use of the groundwater
Lnder the Lnilaiera! Administrati ve Order (UAO) between Vermont American Corporation and
EPA. the properties in the groundwater reclassification area will be subject to other institutional
controls to prevent inappropriate uses of contaminated land and water at the site, including an
easement that prohibits groundwater use.
RECLASSIFICATION AREA
! he 2>0-acre reclassification area has been delineated in accordance with the DEC guidance
document entitled "Procedure for Class IV Groundwater Reclassification," dated November 12,
2000. Supporting documentation outlining the basis lor the delineation is available in the
I ctition for Gtoundwater Reclassification, Parker fundi! 1!. Lyndon, Vermont. URS Corporation,
March 25,2002.
Hie Class IV Groundwater Area is shown on the map, Attachment B, and a legal description of
the reclassification area boundary is file at the DEC Water Supply Division Waterbury, VI.
Attachment C provides a list of current property owners within the Class IV Groundwater Area
boundaries.
MONITORING AND MANAGEMENT .REO^OTRIMEWTS
Restrictions on groundwater use and additional monitoring requirements for the .Parker Landfill
may be applicable under Sections 12-401(7), which states:
Any classification or reclassification decision issued by the Secretary may include special
conditions for the management of the classified groundwater area which shall apply to
activities regulated by the Secretary.
Long-term monitoring of groundwater at the site is required by the U.S. Environmental
Protection Agency. More than forty wells are currently included in the long-term monitoring
program. Ihe Class IV boundary delineation shall be evaluated if contaminant levels in the
sentinel wells along the eastern and western boundaries of the Class FV Groundwater Area equal
or exceed Vermont Preventive Action Levels.
5
-------
Rationale for Reclassifying (iroumhvater at the
Parker Landfill, Lyndon, Vermont
f he following is a fisting of reasons for reclassifying the groundwater at the Parker Landfill
located in Lyndon, Vermont from Class 111 to Class fV.
1, 5 The groundwater beneath the site Is not used and is not li Kely to he used as
a public water supply source.
2. 1 he groundwater is contaminated by a number of organic contaminants and
metals as summarized in the Petition for Graumhuiter Reclassification.
3, *1 lie groundwater quality does not meet the Vermont Groundwater Enforcement
Standards set forth in the Groundwater Protection Rule and Strategy.
4. 1 he groundwater is degraded to the point that it is not suitable as a source of
potable water but may be suitable for some agricultural, industrial, or commercial
uses.
5, Local surface waters that receive groundwater discharges are classified hv the
State of Vermont as Class B.
6. The current activities at the site are intended to prevent the further degradation of
groundwater quality.
Findings of Fact
1. Since 1984, environmental investigations at the Parker landfill have identified a zone of
groundwater contamination stemming from the disposal of industrial wastes.
2. In 1999, EPA signed a Unilateral Administrative Order (HAD) with Vermont American
which outlined the steps by which groundwater contamination originating from the Parker
Lanufill would be investigated, remediated, and monitored over the long term.
3. Based on information prepared by URS Corporation, the environmental consultant for
Vermont American, the DEC Waste Management Division submitted a reclassification
petition on March 25. 2002.
4. 1 he Agency of Natural Resources reviewed the application and determined that the
groundwater beneath an 250-acre area at the Parker Landfill meets the criteria for
reclassification from Class III to Class IV in accordance with the Groundwater Protection
Rule & Strategy and 10 V.S.A, Chapter 48.
I hereby make the findings of [-act identified above arid reclassify the groundwater to Class IV
tinder the Parker Landfill and adjoining property identified in this document.
-fA Date 0 -3
Elizabeth McLain, Secretary " 1 ~~
Agencv of Natural Resources
-------
Attachment A
S77T-
Parker Landfill Site j$S I
Parker Landfill
Lyndon, Vermont
Site Location Map
\
-------
-------
Findings of Fact & Reclassification Order
Parker Landfill, Lyndon, Vermont
Attachment C
List of Property Owners within the Reclassification Area
Map Lot
Owner
Property Mailing Address
">X
Parker
D&A r-nterprises, Jne
P.O. Box 25
Lyndonville, VT 05851
Anne U. Parker
P.O. lJox 25
Lyndonville, V I 05851
Ray 0. Parker and Sons. Inc.
P.O. Box 25
Lyndonville, VT 05851
.12-129
Parker
32-130
Parker
32-131
Parker
32-132
Parker
14-19
Parker
14-129
Mark DeLuca
10 Light Plant Drive
Lyndonville, VT 05851
14-5
Rolf Gidlow/Sylvia Dodge
580 Red Village Road
Lyndonville, VT 05851
14-6
Pine Knoll Rehabilitation & Health
601 Red Village Road
Lyndonville, VT 05851
14-7
Riverside School
30 Lily Pond Road
Lyndonville, VT 05S51
14-132
Riverside School
30 Lily Pond Road
Lyndonville, VT 05S51
14-9
Joyce Jones
49 1 .ight Plant Drive
Lyndonville, VT 05851
14-10
Denise Brown
737 Red Village Road
Lyndonville, VT 05851
14-1 t
Blanche She!In
794 Red Village Road
Lyndonville. VT 05851
14-12
Erven Griffith
P.O. Box 232
Lyndonville, VT 05851
14-122
Village of Lyndonville
P.O. Box 167
Lyndonville, VT 05851
14-123
Northern Vermont Railroad
P.O Box 39
Newport, VT 05855
-------
Parker Landfill Class IV Reclassification
Response to Questions and Comments from Interested Parties
August 21, 2003
What is the Groundwater Coordinating Committee and who are its members?
The Groundwater Coordinating Committee is a multi-age my group established by the Secretary
of the Agency of Natural Resources (ANR) under the authority of 10 VSA Chapter 4$ $1392. The
official members of the Committee include representatives from the following organizations:
Agency of Agriculture, Food, and Markets
Department of Forests, Parks, and Recreation
Department of Health
Department of Environmental Conservation
Water Supply Division
Waste water Management Division
Waste Management Division
Water Quality Division
Geology Division
Currently, the Committee also includes a representative from the Agency of Transportation, an
EPA representative, an industry representative from a hydrogeological consulting firm, and 47
other interested parties from both government and the private sector. The group advises the
ANR Secretary on matters concerning groundwater, including groundwater classification.
What is the purpose of the 200 ft buffer around tie contamination zone at tie Parker
Landfill site?
The zone of contamination is defined by assessing the existing groundwater quality data to
determine where groundwater quality exceeds Vermont Groundwater Enforcement Standards
(I 'GES) at a 95% statistical confidence level. Since monitoring wells can he sparse at many
sites, hydrogeologists must use their best judgment to interpolate between monitoring points in
order to draw a continuous line. There is uncertainty associated with this process. The buffer
provides some leeway for error.
The 200ft buffer also provides protection from inadvertent withdrawal of contaminated water
into a residential well placed outside the contaminant zone boundary. In creating the Class IV
boundary, petitioners are required to calculate the radius of influence for a hypothetical 1
gallon-per minute (gpm) well - a yield thai could serve a large single family home. If the
calculated radius of influence is greater than 200feet, then the buffer is enlarged to equal that
radius. If smaller, the 200ft buffer is maintained.
1
-------
For the Parker Landfill reclassification, the petitioner took a more conservative approach and
calculated the radius of influence for a 3 gpm well (large enough to serve a small subdivision}.
In this geological setting, even the radius for the 3 gpm well was calculated to he less than 200
feet, so the buffer width ur/.v set at 200ft.
The 200ft minimum buffer width is consistent with general regulatory setback requirements for
residential water supply wells. According to the Water Supply Rule, no such well may he
constructed within 200feet of any hazardous waste site. Public and small-scale water system
wells are. subject to more stringent installation criteria.
Why does die reclassification boundary follow property boundaries and not the outer
margin of the 200 ft buffer around the contamination /one?
Once a zone of contamination and its buffer are determined, the state's procedure for
reclassification allows for adjustments to the boundary to improve future administration of the
Class IV area. In order to protect public health, is especially important to make sure the Class
IV boundary is recognizable on the ground and not just on maps. In most cases, the boundary is
adjusted to follow property lines or transportation corridors. In the Parker Landfill case, the
Class IV boundaries were adjusted to match the outer boundaries of the properties in which
easements prohibiting groundwater use are being obtained. The attainment of these easements-
is required as part of the institutional control plan. As part of their obligations under a
Unilateral Administrative Order (UAO) with the USEPA. Vermont American must obtain these
easements.
The reclassification reduces the value of property in that people are less likely to want to
buy land that they can't install a well on. Why shouldn't f be allowed to install a well on
the portion of my property outside the buffer zone?
The Groundwater Coordinating Committee prefers to follow property boundaries or
transportation corridors in outlining a Class IVarea to make the boundary easier to
administrate. However, the Committee is willing to reconsider this practice on a case-by-case
basis. In this case, the Committee has elected to alter the proposed Class IV boundary to bisect,
rather than encompass, Lot 14-10 in response to a request from the property owner, Denise
Brown.
What happens to the reclassification area if the contamination is cleaned up?
If site data provide conclusive evidence that groundwater within all or part of the Class IV Area
has been rendered potable, all or part of the area may be reclassified as Class HI. At present,
there are no cases in the Stale of Vermont where a Class IV designation has been altered to
reflect improvements in groundwater quality.
2
-------
APPENDIX C
Table of Maximum Concentrations of Groundwater Contaminants
that Exceeded IGCLs (2009 through 2014)
-------
Appendix C
Maximum Concentrations of Groundwater
Contaminants that Exceeded IGCLs by Well Location
(2009 through 2013)
Parker Landfill Superfund Site
Well
Location
Screened
Zone
Parameter (COC) (1)
IGCL
(ug/L)
Maximum
Concentration
Exceeding IGCLs (ug/L)
Date of Detected
Exceedance
B101Bฎ
TOR
Vanadium
0.2
3.33
10/1/2013
B102Aฎ
SO
Vanadium
0.2
4.2
10/2/2013
B103A
SO
Cis-1,2-Dichloroethene
70.0
79.5
9/30/2009
T etrachloroethene
5.0
27.6
9/28/2011
Trichloroethene
5.0
1160
9/30/2009
Vanadium
0.2
4.83
10/2/2013
B103C ฎ
TOR
Vanadium
0.2
3.56
10/2/2013
B113A ^
SO
Manganese
300.0
470
10/4/2013
Vanadium
0.2
28.5
10/4/2013
B113BB
TOR
1,4-Dioxane ^
3.0
138 J
9/22/2010
Acetone
700.0
1110
9/30/2009
Methylene Chloride
5.0
5.51 J
9/30/2009
Trichloroethene
5.0
187
9/26/2012
Vinyl Chloride
2.0
30.7
9/26/2012
3-Methylphenol/4-Methylphenol
200.0
524
10/1/2013
B118C ฎ
BR
Vanadium
0.2
2.18
10/3/2013
B119B ฎ
SO
1,4-Dioxane ^
3.0
3.60
10/3/2013
Vanadium
0.2
3.37
10/3/2013
B119C
TOR
1,4-Dioxane (3:>
3.0
4.64
9/30/2009
Manganese
300.0
321
10/3/2013
B120Aฎ
SO
Manganese
300.0
1510
10/15/2013
Vanadium
0.2
4.21
10/15/2013
B120C
TOR
1,4-Dioxane (3:>
3.0
30.1 J
9/23/2010
Benzene
5.0
5.59
9/23/2010
Cis-1,2-Dichloroethene
70.0
910 J
9/23/2010
Methylene Chloride
5.0
48.8 J
9/27/2009
T etrachloroethene
5.0
13.7 J
9/23/2010
Trichloroethene
5.0
2220 J
9/27/2009
Vinyl Chloride
2.0
40.2 J
9/23/2010
B120D
BR
1,4-Dioxane (3:>
3.0
27
10/3/2013 &
9/26/2012
Cis-1,2-Dichloroethene
70.0
160
9/27/2009
Trichloroethene
5.0
40.7
9/27/2009
Vinyl Chloride
2.0
159
10/5/2011
Vanadium
0.2
1.3
10/3/2013
B121B
TOR
1,4-Dioxane ^
3.0
3.22
9/22/2010
Vanadium
0.2
1.64
10/3/2013
Page 1 of 4
-------
Appendix C
Maximum Concentrations of Groundwater
Contaminants that Exceeded IGCLs by Well Location
(2009 through 2013)
Parker Landfill Superfund Site
B1210Wฎ
SO
Vanadium
0.2
13.6
10/3/2013
B122 (2)
TOR
Vanadium
0.2
1.37
10/3/2013
B125A
TOR
Manganese
300.0
2380
10/4/2013
B126A
TOR
1,4-Dioxane ^
3.0
5.53
9/22/2010
Trichloroethene
5.0
25.1
9/26/2012
Well
Location
Screened
Zone
Parameter (COC) (1)
IGCL
(ug/L)
Maximum
Concentration
Exceeding IGCLs
(ug/L)
Date of Detected
Exceedance
B126B
BR
1,4-Dioxane ฎ
3.0
24.00
9/26/2012
Cis-1,2-Dichloroethene
70.0
249 J
9/22/2010
Trichloroethene
5.0
379 J
9/22/2010
Vinyl Chloride
2.0
12 J
9/22/2010
Vanadium
0.2
3.97
10/3/2013
B131C
TOR
1,4-Dioxane ฎ
3.0
160
10/1/2013
Trichloroethene
5.0
12.6
10/1/2013
B132
TOR
1,4-Dioxane ฎ
3.0
8.4 J
9/25/2012
Cis-1,2-Dichloroethene
70.0
101
9/22/2010
Tetrachloroethene
5.0
8.96
9/22/2010
Trichloroethene
5.0
154
9/22/2010
Vanadium
0.2
4.29
10/3/2013
B132B
BR
1,4-Dioxane ฎ
3.0
3.67
9/30/2009
Manganese
300.0
1130
10/3/2013
Vanadium
0.2
1.42
10/3/2013
B136A
SO
1,4-Dioxane ฎ
3.0
31.3 J
9/22/2010
Vanadium
0.2
1.67
10/4/2013
B136B
TOR
1,4-Dioxane ฎ
3.0
12.2 J
9/22/2010
Cis-1,2-Dichloroethene
70.0
2080
9/29/2011
Methylene Chloride
5.0
6.11 J
9/24/2009
Tetrachloroethene
5.0
13.8
9/29/2011
Trichloroethene
5.0
4070
9/29/2011
Vinyl Chloride
2.0
50.8
9/26/2012
Manganese
300.0
1310
10/4/2013
Vanadium
0.2
1.54
10/4/2013
B136C
BR
1,4-Dioxane ฎ
3.0
52.6
9/24/2009
Cis-1,2-Dichloroethene
70.0
1460 J
9/24/2009
Methylene Chloride
5.0
13.5 J
9/24/2009
Trichloroethene
5.0
587
9/26/2012
Vinyl Chloride
2.0
556 J
9/24/2009
B137Aฎ
SO
Manganese
300.0
327
10/3/2013
Vanadium
0.2
10.6
10/3/2013
Page 2 of 4
-------
Appendix C
Maximum Concentrations of Groundwater
Contaminants that Exceeded IGCLs by Well Location
(2009 through 2013)
Parker Landfill Superfund Site
B137B
TOR
1,2-Dichloroethane
5.0
8.09
9/22/2010
1,4-Dioxane ฎ
3.0
15
10/3/2013
Benzene
5.0
5.58
10/3/2013
B138Aฎ
SO
Vanadium
0.2
4.74
10/4/2013
B138B
TOR
1,1 -Dichloroethane
70.0
88.7 J
10/1/2013
1,1 -Dichloroethene
7.0
16 J
10/1/2013
1,2-Dichloropropane ฎ
5.0
9.53
10/3/2011
1,4-Dioxane ฎ
3.0
980 J
10/1/2013
Benzene
5.0
6.15
9/30/2009
Cis-1,2-Dichloroethene
70.0
2690 J
10/1/2013
trans-1,2-Dichloroethene
100.0
122 J
10/1/2013
Trichloroethene
5.0
920 J
10/1/2013
Vinyl Chloride
2.0
998
10/1/2013
Well
Location
Screened
Zone
Parameter (COC) (1)
IGCL
(ug/L)
Maximum
Concentration
Exceeding IGCLs (ug/L)
Date of Detected
Exceedance
B139A
SO
Trichloroethene
5.0
46.3
9/22/2010
B139C
BR
Vanadium
0.2
4.24
10/2/2013
B144A
SO
Vanadium
0.2
1.72
10/3/2013
B144B ฎ
TOR
Manganese
300.0
428
10/3/2013
Vanadium
0.2
4.09
10/3/2013
B145B
TOR
1,4-Dioxane (3:>
3.0
49
10/3/2013
Trichloroethene
5.0
157
10/3/2013
Vinyl Chloride
2.0
3.76
10/3/2013
B145C
BR
1,4-Dioxane ^
3.0
8.3
10/3/2013
Benzene
5.0
14.9
9/30/2009
B147B
TOR
Cis-1,2-Dichloroethene
70.0
928
9/21/2010
Methylene Chloride
5.0
8.87 J
9/24/2009
Trichloroethene
5.0
255
9/21/2010
Vinyl Chloride
2.0
1370 J
9/24/2009
B148B ^
TOR
Cis-1,2-Dichloroethene
70.0
675
10/2/2013
Trichloroethene
5.0
105
9/21/2010
Vinyl Chloride
2.0
450
9/25/2012
B149B-R
TOR
Cis-1,2-Dichloroethene
70.0
856
10/2/2013
Trichloroethene
5.0
181
10/2/2013
Vinyl Chloride
2.0
385
10/2/2013
B150B
TOR
Benzene
5.0
5.67 J
9/26/2011
Cis-1,2-Dichloroethene
70.0
4980
9/24/2009
Methylene Chloride
5.0
8.94 J
9/24/2009
Trichloroethene
5.0
291
9/24/2009
Vinyl Chloride
2.0
825
10/2/2013
Page 3 of 4
-------
Appendix C
Maximum Concentrations of Groundwater
Contaminants that Exceeded IGCLs by Well Location
(2009 through 2013)
Parker Landfill Superfund Site
B160A
SO
T etrachloroethene
5.0
5.23
9/27/2009
Trichloroethene
5.0
66.7
9/27/2009
B160B
SO
1,4-Dioxane ^
3.0
4.09
9/27/2009
Trichloroethene
5.0
68.7
9/27/2009
B160C
SO
1,4-Dioxane (3:>
3.0
12.1
9/28/2009
Trichloroethene
5.0
6.02
9/28/2009
B163A
SO
T etrachloroethene
5.0
4.01
9/29/2009
Trichloroethene
5.0
44.4
9/27/2012
B164A
SO
Trichloroethene
5.0
5.1
9/27/2012
B164B ^
SO
Trichloroethene
5.0
22.7
9/25/2009
B165B
SO
Cis-1,2-Dichloroethene
70.0
1640
9/25/2009
T etrachloroethene
5.0
73.1
10/3/2011
Trichloroethene
5.0
2440 J
9/25/2009
B165C
SO
Cis-1,2-Dichloroethene
70.0
1060
9/22/2010
T etrachloroethene
5.0
19.8
10/2/2013
Trichloroethene
5.0
729
10/2/2013
Vinyl Chloride
2.0
5.05 J
9/22/2010
B166C
SO
Cis-1,2-Dichloroethene
70.0
119
9/23/2010
Vinyl Chloride
2.0
2.68
10/4/2011
B167C
SO
Trichloroethene
5.0
8.61
9/25/2009
B168B
SO
Trichloroethene
5.0
8.82
10/3/2013
Well
Location
Screened
Zone
Parameter (COC) (1)
IGCL
(ug/L)
Maximum
Concentration
Exceeding IGCLs
(ug/L)
Date of Detected
Exceedance
B168C
SO
Cis-1,2-Dichloroethene
70.0
143
9/26/2009
Vinyl Chloride
2.0
4.5
9/26/2009
B169B
SO
Cis-1,2-Dichloroethene
70.0
365
9/27/2012
Tetrachloroethene
5.0
8.12
9/27/2012
Trichloroethene
5.0
183
9/27/2012
Vinyl Chloride
2.0
3.42
9/23/2010
B169CC4)
so
Cis-1,2-Dichloroethene
70.0
247 J
9/29/2009
Vinyl Chloride
2.0
8.1
9/29/2009
B170B
so
Cis-1,2-Dichloroethene
70.0
1570
9/26/2009
Tetrachloroethene
5.0
82.3
10/3/2011
Trichloroethene
5.0
4060 J
9/26/2009
B170C
so
Cis-1,2-Dichloroethene
70.0
290
9/26/2009
Vinyl Chloride
2.0
9.36
9/26/2009
B171B
so
Trichloroethene
5.0
5.24
9/26/2009
B171C
so
Trichloroethene
5.0
8.22
10/3/2013
B172B
TOR
Benzene
5.0
12 J
9/21/2010
Cis-1,2-Dichloroethene
70.0
1400
9/26/2011
Tetrachloroethene
5.0
6.45
9/21/2010
Page 4 of 4
-------
Appendix C
Maximum Concentrations of Groundwater
Contaminants that Exceeded IGCLs by Well Location
(2009 through 2013)
Parker Landfill Superfund Site
Trichloroethene
5.0
975
9/21/2010
Vinyl Chloride
2.0
93.3
10/2/2013
B173B
TOR
Benzene
5.0
8.17 J
9/21/2010
Cis-1,2-Dichloroethene
70.0
341
9/21/2010
Trichloroethene
5.0
143
9/21/2010
Vinyl Chloride
2.0
112
9/21/2010
B174A
SO
Lead (3)
15.0
28.4
10/4/2013
Manganese
300.0
1040
10/4/2013
Vanadium
0.2
24.5
10/4/2013
B174B
TOR
Vanadium
0.2
4.63
10/4/2013
B174C
BR
Vanadium
0.2
1.30
10/4/2013
MW4A
SO
1,4-Dioxane ฎ
3.0
7.55 J
9/22/2010
Vanadium
0.2
2.18
10/4/2013
Notes
ug/L - micrograms per liter
(1) Groundwater samples only analyzed for metals and SVOCs during the October 2013 sampling event.
(2) Well location only sampled in during this FYR period.
(3) Not a COC identified in the ROD; however compound is listed due to previous and/or current exceedances of IGCLs (mg/L) for risk purposes.
(4) - 1,2-dichloroethane, 1,2-dichloropropane and/or tetrachloroethene listed in Table 3 of 2009 annual report as exceeding the applicable IGCL;however the listed
concentration is below the IGCL.
J - Estimated.
SO - Shallow Overburden.
TOR - Top of Rock.
BR - Bedrock.
Page 5 of 4
-------
APPENDIX D
Representative Data Plots
-------
Near source areas
Date
Non-detected results were assigned a value of 0.0001 mg/L for charting purposes IGCL is listed in parentheses after constituent name
-------
Dowtigradient of source area
Son-detected results were assigned a value of 0.0001 mg/L for charting purposes
Date
IGCL is listed in parentheses after constituent name
-------
Near downgradient property line
Non-detected results were assigned a value of 0.0001 mg/L for charting purposes
Date
IGCL is listed in parentheses after constituent name
-------
APPENDIX E
Interview Documentation
-------
INTERVIEW RECORD
Site Name: Parker Landfill
EPA ID No.: VTD981062441
Subject: Five Year Review
Time: 2:28 pm Date: 5/28/2014
Type: Telephone Visit Other: Email Location
of Visit: N/A
Incoming Outgoing
Contact Made By:
Name: Jeff Saunders
Title: Project Manager/Geologist
Organization: TRC Environmental
Individual Contacted:
Name: John Schmeltzer
Title: Hazardous Site Manager
Organization: VTDEC
Telephone No: 802-241-3886 Street Address: 103
Fax No: City, State, Zip: Waterbury, Vermont
E-Mail Address: john.schmeltzer@state.vt.us
South Main Street, West Building
05671-0404
Summary Of Conversation
1
-------
Ql. What is your overall impression of the project?
A1. I have a good impression. VT DEC believes that the remedies at this site have been effective to mitigate
the contamination. Recently, it appears that there may be an increase in groundwater contamination in
monitoring wells approximately southwest of the covered landfill. EPA and the state has directed one of the
responsible parties to take a closer look at this apparent upward trend and recommend next steps (if any). They
are in the process of doing so.
Q2 Have there been any complaints, violations, or other incidents related to the site requiring a response by
your office?
A2. No
Q3 Are there any community groups that are active or involved in the project? A3.
No
Q4 Do you feel well informed about the site's activities and progress?
A4. Yes. ..The responsible parties and EPA have kept me informed of the site's activities and progress.
Q5 Are you aware of anyone using groundwater near the site?
A5. No, given that properties downgradient of the landfill are connected to municipal water and there are
institutional controls (groundwater use restrictions and town zoning restrictions) prohibiting groundwater use.
Q6 Are there any new state regulations (since 2009) that are applicable to the site?
A6. No,,,It is anticipated that a new groundwater and protection rule will be adopted prior to the next 5-year
review in 2019.
Q7 Are there any outstanding issues at the Parker Landfill?
A7. The two outstanding issues are the apparent upward trend in contaminants of concerns and dioxane and
localized settlement on the landfill. Both of these issues are currently being addressed by the responsible
parties.
INTERVIEW RECORD
Site Name: Parker Landfill
EPA ID No.: VTD981062441
Subject: Five Year Review
Time: 11:20 am
Date: 6/4/2014
Type: Telephone X Visit
Location of Visit: NA
Other
Incoming X Outgoing
Contact Made By:
Name: Jeff Saunders
Title: Project Manager / Geologist
Organization: TRC Environmental
Individual Contacted:
Name: Eric Chadburn
Title: Facilities Manager
Organization: Fairbanks Scales, Inc.
1
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Telephone No: 802-748-5 111 Fax
No:
E-Mail Address:
Street Address: 2176 Portland Street
City, State, Zip: St. Johnsbury, VT 05824
Summary Of Conversation
Q1 What is your overall impression of the project?
A1 Great. The site conditions, gas management and working relationship with interested parties, including the
US EPA and VTDEC, are all very good.
Q2 Have there been any significant changes to the O&M of the landfill within the past 5 years?
A2 No, current O&M practices have been and continue to be successful.
Q3 Have there been any unexpected difficulties with continued O&M of the landfill?
A3 There have been no unexpected difficulties with the O&M in the past five years. The settlement in the
vicinity of extraction Well #4 is currently being address collectively with the US EPA and VTDEC, but this
type of issue is not uncommon following landfill closure. Pending approval, further evaluation of the
settlement, including potentially temporarily exposing a limited portion of the liner, will be conducted and
repairs will be implemented (as needed). Woodchuck burrows are an ongoing concern, but this is not an
unexpected challenge and, although time consuming, the current management strategy has successful.
Q4 Do you have any recommendations for reducing or increasing activities at the Site?
A4 No, O&M activities will continue as currently approved/scheduled with mitigation measures (e.g.,
settlement, burrows, etc.) implemented on an as needed basis. Looking forward, preparing for the time when
there is not enough methane to burn to effectively and efficiently manage the associated changes will become
an area of focus.
INTERVIEW RECORD
Site Name: Parker Landfill
EPA ID No.: VTD981062441
Subject: Five Year Review
Time: 11:17 am Date: 6/10/2014
Type: Telephone Visit Other: Email
Location of Visit:
Incoming Outgoing
Contact Made By:
Name: Jeff Saunders
Title: Project Manager/Geologist
Organization: TRC Environmental
Individual Contacted:
Name: Frederik Schuele
Title: Hydrogeologist, Project
Manager
Organization: URS Corporation
1
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Telephone No: 207-879-7686 ext. 224 Fax
No:
E-Mail Address: Frederik.Schuele@urs.com
Street Address: 477 Congress Street, Suite 900
City, State, Zip: Portland, ME 04101
Summary Of Conversation
Q1 What is your overall impression of the project? A1
Positive.
Q2 Are the groundwater remedies functioning as expected?
A2 Yes both the BNA and the PRB groundwater remedies are functioning as expected and performing well.
Q3 How well is the remedy performing?
A3 The PRB continues to intercept impacted shallow overburden groundwater from the IWS-3 source area.
Using conservative assumptions, and based on volumetric mass flux estimates derived from 2013 performance
monitoring data, the PRB remedial activity results in a significant overall reduction in the mass of total CVOCs
in downgradient groundwater. PRB performance monitoring data from 2013 are consistent with conditions
observed during previous year (i.e., 2008 through 2012). BNA monitoring data collected in 2013 indicate that
the BNA Remedial Activity is effectively reducing the concentration and mass of CVOCs in groundwater
downgradient of the landfill. Overall, trichloroethene concentrations within the BNA Treatment Zone have
been substantially reduced since the start of the BNA Remedial Activity in 2005. The presence of chlorinated
ethenes, ethene, VFAs, and nutrients in monitoring wells situated downgradient of the BNA Treatment Zone
indicates that active dechlorination of chlorinated ethenes extends from the BNA injection wells through the
BNA Treatment Zone and into the downgradient aquifer.
Q4 Have there been any significant changes to the monitoring for either of the PRB or BNA system in the last
five years?
A4 Monitoring of the PRB remedial activity for CVOCs has been performed annually since 2008, in
accordance with the 2006 Long-Term Monitoring Plan (LTMP) for the Parker Landfill. An addendum to the
LTMP in My 2010 modified the sampling program for the PRB by eliminating analysis for ethene, ethane, and
chloride. Performance monitoring of the BNA remedial activity is conducted in accordance with the BNA
Operation and Maintenance (O&M) Plan, and has historically entailed monitoring of the 14 BNA injection
wells. The BNA O&M plan was substantially revised in 2011 to include the use of emulsified vegetable oil
(EVO) as an amendment compound. As a result, performance monitoring for the BNA remedial activity was
1
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revised to include an expanded analytical suite, as well as the downgradient BNA monitoring wells, and the
BNA extraction wells.
Q6 Have there been any unexpected difficulties with respect to continued operation/implementation of the
groundwater remedies?
A6 No, there have not been any unexpected difficulties with the remedies.
Q7 What is your projection for achieving the cleanup goals in either of the treatment areas?
A7 Remedial activity monitoring data show marked reductions in the concentrations of CVOCs immediately
downgradient of the PRB and downgradient of the BNA. These conditions are expected to continue into the
future, and eventually allow for the ROD-selected remedy of monitored natural attenuation to prevail in the
areas downgradient of the landfill. However, actual cleanup projections have not been revisited since they were
provided in the design documents.
Q8 Do you have any recommendations for reducing or increasing activities at the Site?
A8 BNA performance monitoring data collected to date demonstrate that the BNA is fulfilling its designated
role of enhancing conditions favorable for groundwater remediation through natural attenuation. However, the
BNA remedial activity is not intended to continue indefinitely. The function of the BNA is to enhance the
monitored natural attenuation remedial activity in achieving IGCLs in groundwater downgradient of the Parker
landfill. Recently proposed BNA O&M plan modifications are intended to allow for continued operation of the
BNA Remedial Activity until concentrations of total chlorinated ethenes in the vicinity of the BNA area are
reduced to where monitored natural attenuation processes (e.g., advection, diffusion, and natural
biodegradation) will effectively continue groundwater remediation downgradient of the landfill. The proposed
performance monitoring program is designed to evaluate the continued enhancement of natural attenuation
processes that extend from the BNA extraction wells, through the BNA Treatment Zone, and into and beyond
the downgradient BNA Monitoring wells. If the proposed BNA O&M Plan modifications are approved by the
EPA, the revised BNA performance monitoring program will be implemented as of the next scheduled
performance monitoring event, and future re-applications of BNA amendments will be scheduled when the
proposed re-application criteria are met.
Long-term groundwater monitoring data collected from monitoring well clusters B119, B131, B137, B138, and
B145 indicate that levels of CVOCs and 1,4-dioxane are increasing within the top-of rock groundwater flow
system in the western/southwestern portion of the Study Area. Potential source materials and conditions for the
increases were identified in the 2013 Draft Annual Monitoring Report. Monitoring and analyses will continue
to be conducted to evaluate constituent trends at these monitoring locations, and the data obtained will be
analyzed to develop a better understanding of groundwater conditions in the vicinity of these wells. In addition,
the Conceptual Site Model for the Parker Landfill will be updated by incorporating information generated from
investigations, monitoring, and remedial activities performed at the Parker Landfill from 2005 through 2013.
The updated CSM will identify data gaps for the top-of-rock groundwater flow system in the
western/southwestern portion of the Study Area, and is expected to recommend proposed locations for the
installation of additional monitoring wells to better define the extent of CVOCs and 1,4-dioxane in
groundwater west/southwest of the landfill.
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2
INTERVIEW RECORD
Site Name: Parker Landfill
EPA ID No.: VTD981062441
Subject: Five Year Review
Time: 4:03 pm
Date: 6/10/2014
Type: Telephone
Location of Visit:
Visit
Other: Email
Incoming Outgoing
Contact Made By:
Name: Jeff Saunders
Title: Project Manager/Geologist
Organization: TRC Environmental
Individual Contacted:
Name: Justin Smith
Title: Zoning Administrator
Organization: Town of Lyndon, Vermont
Telephone No: 802-626-1269 Fax
No:
E-Mail Address: justin@lyndonvt.org
Street Address: Zoning Department
City, State, Zip: Town of Lyndon, Vermont
Summary Of Conversation
Q1: Are you familiar with the activities at the site in the last five years and the institutional controls (IC)
being implemented to restrict use of groundwater? Al. Yes.
Q2: Have any new areas/roads been included in the zoning ordinance within the last five years? A2.
No.
Q3: In 2003, the State of Vermont reclassified groundwater from Class III to Class IV. Has the Town of
Lyndonville completed expansion of the "Institutional Control Area"? A3. To the best of my knowledge
yes.
Q4: Will a Town ordinance continue to be sought to fulfill the ROD institutional control requirements and is
there an anticipated completion date?
A4. I am unaware of there being any intention of adding anything to the ordinances, we already have the
Institutional Control area identified in our zoning by-laws.
Q5: What, if any, new construction is proposed/planned in the vicinity of the site?
A5. None at the moment within the IC District.
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1
APPENDIX F
Current Toxicity Criteria and Vapor Intrusion Screening Levels for
Groundwater
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Table 1
Current Toxicity Criteria for Carcinogens
Constituent
Current Weight
of Evidence
Classification
1993 Oral
Slope Factor
(mg/kg-d)-1
2014 Oral
Slope Factor
(mg/kg-d)-1
Acetone
Inadequate (b)
Benzene
A (b)
2.9E-02 (a)
5.5E-02 (b)
Butanone, 2-
Inadequate (b)
Chloroform
B2 (b)
6.1E-03 (a)
3.1 E-02 (g)
Chloroethane
Likely (d)
2.9E-02 [c]
None (b)
Dichlorodifluoromethane
--(b)
Dichloroethane, 1,1-
C(b)
5.7E-03 (g)
Dichloroethene, 1,1-
Suggestive (b)
6E-01 (a)
None (b)
Dichloroethene, 1,2- (total)
Inadequate (b)
Dichloropropane, 1,2-
B2(f)
6.8E-02 (e)
3.6E-02 (g)
Dioxane, 1, 4-
Likely (b)
1.0E-01 (b)
Ethyl Benzene
D (a)
1.1 E-02 (g)
Methylene Chloride
Likely (b)
7.05E-03 (a)
2.0E-03 (b)
Methyl-2-Pentanone, 4- (MIBK)
Inadequate (b)
Tetrachloroethene
Likely (d)
5.2E-02 [c]
2.1 E-03 (b)
Toluene
Inadequate (b)
Trichloroethane, 1,1,1-
Inadequate (b)
Trichloroethene
Carcinogenic to Humans (b)
1.1E-02 [c]
4.6E-02 (b)
Vinyl Chloride
A (b)
1.9E+00 [c]
7.2E-1 adult (b)
Vinyl Chloride (cont'd)
1.4E+00 from birth (b)
Xylenes, Total
Inadequate (b)
Bis(2-ethylhexyl) Phthalate
B2 (b)
1.4E-02 (a)
Same (b)
Dibenzofuran
D (b)
Diethyl phthalate
D (b)
Di-n-butylphthalate
D (b)
Fluoranthene
D (b)
Fluorene
D (b)
Methylnaphthalene, 2-
Inadequate (b)
Methylphenol, 4- (p-cresol)
C(b)
Naphthalene
C(b)
Phenanthrene
D (b)
Pyrene
D (b)
Aluminum
Inadequate (d)
Antimony
Inadequate (d)
Arsenic
A (b)
1.75E+00 (a)
1.5E+00 (b)
Barium
D (b)
Beryllium
B1 (b)
4.3E+00 (a)
None (b)
Cadmium
B1 (b)
Chromium (total)
D oral, A inh. (b)
None
5.0E-01 (h,i)
Cobalt
Likely (d)
Copper
D (b)
Cyanide
Inadequate (b)
Iron
C(d)
Lead
B2 (b)
Manganese
D (b)
Nickel
--(b)
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Selenium
D (b)
Vanadium
Inadequate (d)
Zinc
Inadequate (b)
(a) IRIS, Integrated Risk Information System, 1993
(b) IRIS, Integrated Risk Information System, 2014 (http://www.epa.gov/iris/)
(c) Interim value from ECAO, 1992
(d) PPRTV value from STSC, 2014
(e) Health Effects Assessment Summary Tables (HEAST), FY 1992
(f) Health Effects Assessment Summary Tables (HEAST), FY 1997
(g) California OEHHA value, 2014
(h) New Jersey Department of Environmental Protection, 2014
(i) Value is for hexavalent chomium
A = Known human carcinogen
B1 or B2 = Probably human carcinogen
Tables 1_2
Table 2
Current Toxicity Criteria for Non- Carcinogens
Constituent
1993 Oral RfD
mg/kg-d
2014 Oral RfD
mg/kg-d
Acetone
1E-01 (a)
9E-01 (b)
Benzene
4E-03 (b)
Butanone, 2-
5E-02 (a)
6E-01 (b)
Chloroform
1E-02 (a)
Same (b)
Chloroethane
4E-01 [c]
None (b)
Dichlorodifluoromethane
2E-01 (a)
Same (b)
Dichloroethane, 1,1-
1 E-01 (e)
2 E-01 (d)
Dichloroethene, 1,1-
9E-03 (a)
5E-02 (b)
Dichloroethene, 1,2- (total)
9E-03 (e)
2E-03 (b,n)
Dichloropropane, 1,2-
9E-02 (k)
Dioxane, 1, 4-
3E-02 (b)
Ethyl Benzene
1 E-01 (a)
Same (b)
Methylene Chloride
6 E-02 (a)
6E-03 (b)
Methyl-2-Pentanone, 4- (MIBK)
5 E-02 (a)
8E-02 (f)
Tetrachloroethene
1 E-02 (a)
6E-03 (b)
Toluene
2E-01 (a)
8E-02 (b)
Trichloroethane, 1,1,1-
9 E-02 (e)
2E+00 (b)
Trichloroethene
6E-03 [c]
5E-04 (b)
Vinyl Chloride
None
3E-03 (b)
Xylenes, Total
2E+00 (a)
2E-01 (b)
Bis (2-ethylhexyl) Phthalate
2 E-02 (a)
Same (b)
Dibenzofuran
4E-03 [c]
1E-03 (d)
Diethyl phthalate
8E-01 (a)
Same (b)
Di-n-butylphthalate
1 E-01 (a)
Same (b)
Fluoranthene
4 E-02 (e)
Same (b)
Fluorene
4 E-02 (e)
Same (b)
Methylnaphthalene, 2-
None
4E-03 (b)
Methylphenol, 4- (p-cresol)
5E-03 (e)
1 E-01 (k)
Naphthalene
4 E-02 (e)
2E-02 (b)
Phenanthrene
4E-02 (e,g)
2E-02 (b,g)
Pyrene
3 E-02 (a)
Same (b)
Aluminum
1E+00 [c]
Same (d)
Antimony
4E-04 (a)
Same (b)
Arsenic
3E-04 (a)
Same (b)
Barium
7 E-02 (a)
2E-01 (b)
Beryllium
5E-03 (a)
2E-03 (b)
Cadmium
5E-04 (a,h)
Same (b,h)
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Chromium (total)
5E-03 (a,i)
3E-03 (b,i)
Cobalt
3E-04 (d)
Copper
4E-02 (f)
Cyanide
2E-02 (a)
6E-04 (b,m)
Iron
None
7E-01 (d)
Lead
Manganese
5 E-03 (a)
2.4E-02 (b,l)
Nickel
2E-02 (a,j)
Same (bj)
Selenium
5 E-03 (a)
Same (b)
Vanadium
7E-03 (e,k)
5E-03 (b)
Zinc
2E-01 (a)
3E-01 (b)
(a) IRIS, Integrated Risk
Information System, 1993
(b) IRIS, Integrated Risk
Information System, 2014 (http://www.epa.g
(c)lnterim value from ECAO, 1992
(d) PPRTV value from
STSC, 2014
(e) Health Effects
Assessment Summary Tables (HEAST), FY 1992
(f) Health Effects Assessment
Summary Tables (HEAST), FY 1997
(g) Value is cross-assigned
from Naphthalene
(h) Cadmium RfD is for
water, 1E-03 mg/kg-d is the RfD for food
(i) Value is for hexavalent chromium
(j) Value is for nickel, soluble salts
(k)ATSDR, 2014
(I) Value is for manganese (non-diet)
Tables 1 2
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Table 3
Vapor Intrusion Screening Levels for Groundwater1
Residential Target
Indoor Air
Concentration
(ILCR=1E-06)
Residential Target
Indoor Air
Concentration
(HQ=0.1)
Target Groundwater
Concentration
(ILCR=1E-06)
Target Groundwater
Concentration
(Hl=0.1)
Basis of Target
Concentration
Dimensionless
C=Cancer Risk;
InhalationUnit Risk
Reference
Henry's Law
Chemical
N/C=Non cancer Risk
(Mg/m3)"1
Concentration (Mg/m3)
|jg/m3
|jg/m3
Constant (unitless)
mq/l
mq/l
Acetone
NC
NA
3.10E+04 A
NA
3.20E+03
1.43E-03
NA
2.24E+06
Benzene
C
7.80E-06
3.00E+01
3.60E-01
3.10E+00
2.27E-01
1.59E+00
1.37E+01
1,1-Dichloroethane
C
1.60E-06 C
I NA
1.80E+00
NA
2.30E-01
7.83E+00
NA
Methylene chloride
C
1.00E-08
6.00E+02
1.00E+02
6.30E+01
1.33E-01
7.53E+02
4.74E+02
Trichloroethene cis-1,2-
Dichloroethene
C
NC
4.10E-06
NA
2.00E+00
NA
4.80E-01
NA
2.10E-01
NA
4.03E-01
1.67E-01
1.19E+00
No value available
5.21E-01
No value available
Table Footnotes:
Toxicity Values used as basis of Target Indoor Air and Groundwater Concentrations are available on the Regional Screening Levels Table at http://www.epa.gov/reg3hwmd/risk/human/index.htm (May
2014)
Toxicity Value References: C = CalEPA; I = IRIS; ATSDR = Agency for Toxic Substances and Disease Registry
Henry's Law Constants from Regional Screening Levels Table (May 2014)
Screening value is based on 1x10~6 cancer risk or HI = 0.1.
Residential Target Indoor Air values are found in Regional Screening Levels table (http://www.epa.gov/reg3hwmd/risk/human/index.htm).
The equation for the target groundwater concentration (Cgw) is:
Cia,target
Cgw = AFgw x (1000 L/m3) x HLC where Cia is the target indoor air concentration, AFgw is the generic attenuation
factor for groundwater (default value = 0.001) and HLC is Henry's Law Constant.
The lower of the target groundwater concentration based on an ILCR of 1E-06 or a HQ = 0.1 is selected as the groundwater Vapor Intrusion Screening Level (VISL).
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