long-term performance monitoring of remediated aquatic ......remedial goals have been achieved and...
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ENSC 501: Independent Environmental Study – Queen’s University
Long-Term Performance Monitoring of Remediated Aquatic Sites: Strategy Specific Considerations
Melanie Fortune BScH Environmental Life Sciences 2011 Candidate
Queen’s University
Kingston, ON [email protected]
613-876-5760 567 4912
Abstract
Currently, the federal government of Canada is responsible for over 1,300 aquatic sites with contaminated sediment that may pose risk to human health and the environment (TBCS, 2011). To ensure a consistent and effective approach to site management, the Federal Contaminated Sites Action Plan (FCSAP) outlines steps to be taken to manage federal contaminated sites including aquatic sites (Chapman, 2010). Long-term monitoring is the final management step and is undertaken after remediation of the site has been completed. The FCSAP aquatic sites framework is currently lacking strategy-specific guidance about performance monitoring, which is used to evaluate long-term effectiveness of remedial strategies, as well as scientific guidance for site closure. A review of relevant scientific literature, guidance documents, international policy and case studies was conducted to identify considerations for performance monitoring and site closure following sediment remediation using four remedial strategies: Monitored Natural Recovery (MNR), capping, dredging and in situ treatment. To support monitoring plan development, information is summarized regarding remedial processes and processes of concern to be monitored as well as possible performance monitoring goals, objectives, indicators, metrics and associated targets specific to each remedy. The level of effort required for performance monitoring and the applicability of site closure to different sediment remediation strategies are also explored. An analysis of performance monitoring case studies highlights examples of monitoring plan components as well as site closure considerations. The results of this review suggest that 1) limited policy exists worldwide regarding site closure and performance-monitoring plans; 2) performance monitoring is specific to the remedial strategy employed; and 3) site closure cannot be achieved for all strategies. Recommendations outlined in this report may be incorporated into Canadian policy to support performance monitoring plan development and implementation under the FCSAP process, as well as an understanding of site closure potential following specific sediment remediation strategies.
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Table of Contents
INTRODUCTION ...................................................................................................................................................... 3
METHODS ................................................................................................................................................................. 4
RESULTS AND DISCUSSION ................................................................................................................................. 5
AQUATIC PERFORMANCE MONITORING & SITE CLOSURE POLICY REVIEW ................................................................. 5
LONG-TERM MONITORING FOLLOWING AQUATIC REMEDIATION ................................................................................. 5
STRATEGY-SPECIFIC PERFORMANCE MONITORING CONSIDERATIONS ............................................ 7
I. MONITORED NATURAL RECOVERY .............................................................................................................................. 7
II. CAPPING ................................................................................................................................................................ ........ 13
III. DREDGING ................................................................................................................................................................ ... 19
IV. IN SITU TREATMENT .................................................................................................................................................. 23
GENERAL PERFORMANCE MONITORING CONSIDERATIONS ............................................................... 29
SITE COMPLEXITY ................................................................................................................................................................ . 29
LEVEL OF EFFORT ................................................................................................................................................................ . 29
SUMMARY OF MAIN POINTS ........................................................................................................................... 32
ACKNOWLEDGEMENTS ......................................................................................................................................... 34
REFERENCES ......................................................................................................................................................... 35
APPENDIXES: PERFORMANCE MONITORING CASE STUDIES............................................................... 39
CASE STUDY: HUDSON RIVER ............................................................................................................................................. 39
CASE STUDY: MCCORMICK & BAXTER CREOSOTING CO. ............................................................................................... 41
CASE STUDY: LOWER FOX RIVER & GREEN BAY ............................................................................................................. 45
CASE STUDY: SAGLEK, LABRADOR ..................................................................................................................................... 47
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Introduction
As a result of anthropogenic activity or natural sources, contaminants such as petroleum
hydrocarbons, polycyclic aromatic hydrocarbons, polychlorinated biphenyls and metals exist in the
environment at levels that may pose risk to human and ecological health. Aquatic environments, such as
wetlands, streams, rivers, lakes, harbours and other water bodies, may be contaminated by the
deposition of contaminants from the atmosphere, groundwater or surface water discharges, the
movement of contaminant-bound soil particles into water bodies by erosion, or from underwater
mineral changes. These processes can lead to elevated contamination levels in sediment, the particulate
accumulated on the bottom of the water body (US EPA, 1998). Managing sediment contamination at
aquatic sites may involve specific remedial strategies such as monitored natural recovery (MNR),
capping, dredging and in-situ treatments.
Currently, the federal government of Canada is responsible for over 1,300 sites with
contaminated sediment that may pose risk to human health and the environment (TBCS, 2011). To
ensure that effective and consistent approaches are used for the management of federal aquatic
contaminated sites, a 10-step guidance framework has been outlined to provide support and advise
custodians under the Federal Contaminated Sites Action Plan (Chapman, 2010). Long-term monitoring is
the final step of this process and occurs after remediation of the site has been completed. Monitoring
involves repeated sampling and analysis to ensure remedial strategies are functioning as required
(performance monitoring), as well as to assess that human health and environmental risks have
decreased to acceptable levels (ecosystem recovery monitoring). When there is confidence that
remedial goals have been achieved and these conditions will persist into the foreseeable future, a
decision of site closure can be made to conclude the FCSAP process (Chapman, 2010).
The scope of this project examines considerations for performance monitoring and its relevance
to site closure. The focus is on remedial strategy specific considerations for contaminated sediment
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sites. The following strategy-specific questions are explored regarding long-term performance based
monitoring plans at contaminated sediment sites:
• What policies are currently in place in Canada and in other jurisdictions to support long-
term performance monitoring strategies for different aquatic remedies?
• What remedial strategy-specific considerations that should be made when designing a
performance monitoring plan following MNR, capping, dredging and in situ treatment?
o What are the processes to be targeted during monitoring?
o What remediation strategy-specific goals and objectives should be included?
o Which indicators and metrics should be examined?
o What level of effort is required for this monitoring?
o When can performance monitoring be discontinued and site closure proceed, if at all?
The goals of the review are to 1) summarize the current state of science and policy for
performance monitoring of aquatic contaminated sites; and 2) provide recommendations that may be
incorporated by the Department of Fisheries and Oceans Canada into scientific guidance and policy
development for site closure of FCSAP aquatic contaminated sites.
Methods
To address the project scope and core questions, a scientific literature review was conducted
regarding strategy-specific remediation considerations to support the development of long-term
performance-based monitoring. The literature review included peer-reviewed scientific journal articles,
guidance documents for contaminated sites, and an overview of international policy concerning
performance-based monitoring requirements and site closure of aquatic contaminated sites. The
recommendations made for Canadian programs in this report are also supported by a review of case
studies of performance monitoring plans used to address different remedial strategies.
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Results and Discussion
Aquatic Performance Monitoring & Site Closure Policy Review
Current policy regarding long-term performance monitoring and site closure for remediated
aquatic sites has been reviewed from North America, Australia and New Zealand, and the European
Union. Results suggest that these jurisdictions generally use a risk-based approach to motivate remedial
action and assess strategy effectiveness; strategy-specific performance monitoring requirements are not
specifically supported (ACT EPA, 2009; Allan et al., 2006; Apitz and Power, 2002; European Communities,
2003; Ferguson, 1999; USEPA, 2002a). It seems that while the U.S. has developed a reporting framework
and procedure for site closure, scientific guidance for site closure attainment has yet to be implemented
across the examined jurisdictions (USDOD, 1999; US EPA, 2000). Knowledge of current policy informs
the following discussion regarding recommendations for strategy-specific performance monitoring
planning and procedures for the Canadian FCSAP Program.
Long-Term Monitoring following Aquatic Remediation
Monitoring contaminated sites involves “the collection and analysis of repeated observations or
measurements to evaluate changes in condition and progress toward meeting a management objective”
(Elixinga et al., 1998; cited in USEPA, 2004). Long-term monitoring is the tenth step of the FCSAP process
Chapman, 2010). It encompasses both performance monitoring and ecosystem recovery monitoring
(SPAWAR and ENVIRON, 2010). The purpose of performance monitoring is to ensure the remedy is
performing as designed. Performance monitoring is conducted over long timeframes following remedial
construction by collecting data to assess important remedial processes that act to reduce risk at the site
as well as potential processes of concern that may cause increased risk. Ecosystem recovery monitoring
complements performance monitoring by assessing the overall reduction of human health and
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environmental risk to reach risk reduction and ecosystem recovery goals (SPAWAR and ENVIRON, 2010).
Site closure is the final decision point that follows the achievement of a site’s performance monitoring
and ecosystem recovery monitoring objectives and marks the completion of the FCSAP process.
Site closure achievement is dependent on the development of successful monitoring plans that
clearly outline monitoring goals, objectives, indicators and quantifiable target endpoints. The
relationship of these components is depicted in Figure 1. While the goal of performance monitoring is
generally to ensure the remedy is performing as designed to reduce site-specific risk levels, performance
monitoring objectives are remedial-strategy specific (US EPA, 2004). Objectives are established to clarify
the scope and extent of monitoring and are based on site conditions and exposure pathways (NRC,
2007; US EPA, 2005). To assess a site’s monitoring objectives, physical, biological or chemical monitoring
indicators may be evaluated. When all of an objective’s indicators have reached their target endpoints,
monitoring for the given objective is complete. Upon the achievement of all performance and
ecosystem recovery monitoring objectives, the site may proceed to closure.
The development of a monitoring conceptual model is closely linked to the evaluation of
remedial strategy effectiveness outlined by monitoring objectives. A monitoring conceptual model
summarizes how the remedial activity is hypothesized to achieve risk reduction and identifies important
processes, indicators, metrics, and targets for monitoring. Exemplary monitoring conceptual models are
also developed in this report for each of the remedial strategies examined.
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Strategy-Specific Performance Monitoring Considerations
I. Monitored Natural Recovery
Strategy Overview
Monitored Natural Recovery (MNR) is an in situ strategy that uses processes naturally occurring
on the contaminated site to permanently contain, destroy or reduce the sediment contamination as well
as the corresponding bioavailability and toxicity (ASTSWMO, 2009; Magar and Wenning, 2006; SPAWAR
and ENVIRON, 2010). There are multiple physical, chemical or biological processes that may be
employed to remediate sediment contamination in MNR, as shown in Box 1.
Numerous lines of evidence are used to support the decision to utilize MNR on a site, as
discussed in ENVIRON (2006) and Förstner and Apitz (2007). This technology is often combined with
other remedial solutions such as dredging, capping or in-situ treatment (ENVIRON, 2006; Förstner and
• Overall intentions of ecosystem management actionsGoal
• Statement to clarify the scope and intent of monitoring goalObjective
• Phyiscal, biological or chemical component to be sampled and analyzedIndicator
• Qualitative or quantitative evaluation of an indicatorMetric
• Evalution result indicative that objective has been achieved
Target Endpoint
Figure 1 Relationship between monitoring plan components: goals, objectives, indicators, metrics and target endpoints (Adapted from MacDonald et al., 2009).
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Apitz, 2007). MNR has received growing recognition as an alternative to active remedies by the US
Environmental Protection Agency (US EPA, 2005a).
MNR may be supported by engineered means to accelerate natural recovery processes to
achieve risk reduction and ecological recovery (Merritt et al., 2010; SPAWAR and ENVIRON, 2010).
Although enhanced monitored natural recovery is an accepted remedial strategy, it has not been as
comprehensively reviewed as other remedial approaches (Magar et al., 2009; Merritt et al., 2010; NRC,
2007). Enhanced monitored natural recovery primarily involves thin-layer sediment application of
approximately 15-30cm of clean sand, sediment or gravel materials at specific site locations (Merritt et
al., 2010; SPAWAR and ENVIRON, 2009). The installation of flow structures to increase natural
sedimentation rates can also be a part of enhanced monitored natural recovery strategies (Förstner and
Apitz, 2007). The aim of these approaches is not to seal over a contaminated area, as is done during
traditional capping, but to accelerate physical isolation processes such as contaminant burial and
isolation and sediment mixing to dilute surface sediment concentrations. These strategies also facilitate
the re-establishment of benthic organisms to minimize benthic community disruption (SPAWAR, 2003;
US EPA, 2005a).
Box 1 Chemical, physical and biological remedial processes used for MNR.
Physical Processes • Burial and isolation of contaminants in
environments with net deposition • Progressive sediment mixing to dilute
surface sediment contaminants • Contaminant erosion, dispersion and off-
site transport
Chemical Processes • Contaminant transformation • Contaminant weathering • Contaminant sorption, precipitation and
sequestrations
Biological Processes • Contaminant biodegradation • Contaminant biotransformation
Adapted from ASTSWMO, 2009; ENVIRON International, 2006; Magar and Wenning, 2006; SPAWAR and ENVIRON International, 2010; US EPA, 1998; US EPA, 2005a.
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Performance Monitoring Indicators
Performance monitoring objectives for MNR are summarized in Box 2. Monitoring MNR performance
involves ensuring that MNR processes are occurring over the long term to sequester contaminants, as
well as short-term considerations regarding the chemical flux from contaminated sediments into the
water column (SPAWAR and ENVIRON, 2010). The natural recovery processes that are applicable for a
particular site should have been identified as part of the Remedial Action Plan, along with estimates of
the time frame for MNR. For each of the relevant processes, the rate at which it is occurring may be
compared to site-specific estimates to determine if remedial performance is proceeding as predicted to
meet risk-based goals within an established time period (Magar et al., 2009). For example, if physical
natural recovery processes such as burial and isolation were involved in the MNR strategy for a site, the
sediment stability could be monitored using cohesiveness and shear strength indicators to ensure that
there is not a risk of contaminant breakthrough after erosion (Magar and Wenning, 2006). Alternatively,
if chemical or biological transformation was a component of the MNR strategy, monitoring would be
undertaken to deduce the toxicity of generated species from the transformation as well as their
Box 2 Performance monitoring objectives for Monitored Natural Recovery (MNR) (after SPAWAR and ENVIRON, 2010).
1. Have natural chemical transformation processes proceeded to meet remedial goals and is there confidence that this is irreversible?
2. Have naturally occurring contaminant binding, precipitation or sequestration processes
applicable to the site been demonstrated to be stable given current and future site geochemical conditions?
3. Have naturally occurring biological transformation processes proceeded to meet
remedial goals and is there confidence in their irreversibility?
4. Have physical isolation and contamination burial processes effectively isolated sediments and been observed to be stable?
5. Does the chemical flux from the remaining contaminated sediment into water column
stay within acceptable site risk levels?
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geochemical stability in the site environment and their likelihood for reactions to reverse given specific
site conditions. Regardless of specific physical natural recovery processes applicable for the site, the
sediment’s physical stability during recovery should be monitored (SPAWAR and ENVIRON, 2010). More
information regarding the specific lines of evidence that could be incorporated into MNR can be found
in Magar et al. (2009). Lists of monitoring tools that are appropriate for assessing physical and chemical
processes of natural recovery are found in the on-line ISRAP sediment monitoring matrix (SPAWAR and
ENVIRON, 2010). An example of a monitoring conceptual model for physical isolation natural recovery
processes is found in Figure 2.
Figure 2 Example of a monitoring conceptual model for performance monitoring of Monitored Natural Recovery (MNR) using contaminant burial and isolation (after US EPA, 2004).
In addition to monitoring these site-specific processes, monitoring should also be carried out to
assess the chemical integrity of remaining contaminated sediments by monitoring the chemical flux
from these sediments into the water column. Monitoring data is used to fully characterize the chemical
flux process and evaluate risk reduction as MNR progresses. A list of monitoring tools to assess this
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monitoring objective is also found in the on-line ISRAP sediment monitoring matrix (SPAWAR and
ENVIRON, 2010). Common indicators include the chemical analysis of sediment or porewater samples.
Additional long-term monitoring considerations may be incorporated for enhanced monitored
natural recovery processes. If thin-layer sediment application is utilized, indicators for physical processes
such as cap material mixing with underlying sediments, cap erosion and consolidation would also be
considered (Merritt et al., 2010; SPAWAR and ENVIRON, 2010). Supplementary ecological recovery
indicators would also be incorporated to consider the effects of capping materials on benthic
community recovery. Unlike traditional capping, the cap thickness may not be monitored since
containment is not a concern and partial or complete sediment cover will encourage physical isolation
processes (SPAWAR and ENVIRON, 2010).
Spatial and Temporal Considerations for Performance Monitoring
Monitored natural recovery will require more monitoring during the initial recovery phase,
which may last years or decades, and can be reduced during later performance and remedial goal
monitoring (SPAWAR and ENVIRON, 2010; US EPA, 2005a). The US EPA recommends period reviews
every five years during long term monitoring of aquatic risk-indicators (US EPA, 2005a). Event-based
monitoring should also be incorporated to investigate possible risk associated with contaminant release
following high-energy site disruptions, such as storms, high winds or ice scour, especially if burial or
isolation processes were dominant on the site (Magar et al., 2009; SPAWAR and ENVIRON, 2010; US
EPA, 2005a). Recommendations regarding the temporal level of effort required for specific monitoring
considerations are also outlined in the ISRAP sediment monitoring matrix on-line tool and are
summarized in Box 3. For all objectives, monitoring is undertaken on a temporal basis during the natural
recovery process until the processes being monitored can be fully characterized or the consequences of
the examined process for risk reduction can be predicted (SPAWAR and ENVIRON, 2010). Magar et al.,
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(2009) also emphasizes the importance of event-based monitoring until certainty has been achieved
regarding the resiliency of natural recovery processes to disruptive events.
Spatially, long term monitoring efforts should be focused in areas that are most susceptible to
the slowing or reversal of MNR processes (Magar et al., 2009). While a site may have only one or all
natural recovery processes operating, the dominant natural recovery mechanism often differs within the
site depending on the specific location. For example, in a high energy, main channel area of a water
body, dispersal may be the dominant mechanism operating, and thus monitoring efforts should focus on
indicators of dispersion success for that location. In contrast, in low energy environments within the site,
deposition resulting in a high rate of sedimentation should be monitored as it is facilitating burial of
contaminated sediment (Magar et al., 2009). Monitoring should also be undertaken downstream of the
contamination hot spots to ensure that any dispersal processes are not introducing substantial risk to
off-site locations (ASTSWMO, 2009).
Site Closure Considerations
Generally, if the site has met remedial goals and performance-based objectives, long-term
monitoring of an MNR site can proceed to closure. Process-specific considerations also need to be taken
into account for site closure. For sites remediated using natural chemical transformation processes, site
Box 3 Recommendations regarding the timeframe and frequency of performance monitoring required for Monitored Natural Recovery (MNR) monitoring objectives
Monitoring Indicator Monitoring Timeframe Monitoring Frequency
Chemical Integrity Temporal Annually or more frequently to
establish long-term trend Chemical Recovery
Processes Temporal or Event-Based
Every 1-5 years or following disruptive events
Physical Recovery Processes Temporal or Event-Based
Every 1-5 years or following disruptive events
Adapted from Magar et al., 2009; SPAWAR and ENVIRON, 2010; US EPA, 2005a.
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closure can proceed if the contaminant is degraded to meet remedial goals and there is confidence that
the transformation is irreversible. If binding, precipitation or sequestration processes were used to
reach remedial goals, site closure can be achieved when binding processes are demonstrated to be
stable given the site’s current and future geochemical conditions. Sites that rely on physical isolation
and contamination burial processes and still have contamination on site may be able to terminate
performance monitoring after the isolated contaminated sediment has been observed to be stable for
many years and after numerous high-energy events (Magar et al., 2009).
II. Capping
Strategy Overview
Capping is an in situ remedial technology that involves the controlled placement of clean
material over contaminated sediments without disturbing the original bed (NRC, 1997). By physically
and chemically isolating contaminants and stabilizing the sediment to prevent resuspension, the risks
posed by the contaminated sediments to human health and the environment are reduced (Palermo et
al., 1998; SPAWAR and ENVIRON, 2010). Cap design varies to meet the needs of different site
conditions, such as water depth or hydrodynamic flow. Multiple or single layers of materials may be
used to cover the sediment and can include fine-grained material, sandy material to aid with sediment
stability and geotextile membranes or armour stone used to prevent erosion (SPAWAR and ENVIRON,
2010). Greater experience with capping remedies has been gained over the last decade; cap
performance can now be better predicted and quantified, and this has led to greater acceptance among
agencies (NRC, 2007).
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Performance Monitoring Indicators
Caps are designed and constructed to withstand stresses related to existing and probable
human activities and hydrodynamic conditions in the site environment. However, since contaminated
sediments remain on site, they are subject to long term risks of disruption by natural or human activity
as well as upward diffusion of contaminants through the cap (SPAWAR, 2003). It is crucial to monitor cap
performance (i.e., physical and chemical integrity) over time to determine if the remedial solution is
functioning as expected or if further maintenance is required. Assessment of the impact of the
constructed cap on site hydrodynamics and sediment transport is also important, as changes in these
processes may affect other areas of the site that contain some fugitive contamination (Blake et al.,
2007). A summary of the performance monitoring objectives for capping is presented in Box 4.
Important indicators to detect processes of concern for each performance monitoring objective
recommended for capping strategies are summarized in Box 5. A detailed description of monitoring
indicators and methodology for sampling the chemical and physical integrity of the cap is found in
ASTSWMO (2009) and Palermo et al. (1998), as well as in the online ISRAP sediment monitoring matrix
(SPAWAR and ENVIRON, 2010).
Box 4 Performance monitoring objectives for capping (after SPAWAR and ENVIRON, 2010).
1. Is the chemical integrity of capping material maintained over time and following disruptive events to ensure that risk posed by the contaminated sediment does not pose concern?
2. Is physical integrity of capping material maintained over time and in variable site conditions?
3. Is the impact of the cap on site hydrodynamics and sediment transport acceptable and as predicted?
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The physical integrity of the sediment cap is monitored by indicators of cap thickness,
placement and consistency. The cap is expected to undergo consolidation following its initial
construction, which involves compression of the cap material and some erosion depending on site
conditions and cap design. However, maintenance may be required if there is an indication erosion rates
are greater than expected. The thickness should be assessed in multiple locations to ensure consistency
across the cap (ASTSWMO, 2009). In addition to erosion, the softer layers of the cap are also at risk of
penetration and disruption by submerged aquatic vegetation, groundwater recharge and bioturbation
by burrowing animals, which affect the cap’s character (also described as its cohesiveness or
consistency; Palermo et al., 1998). Cap character can be monitored using similar strategies as those for
determining cap thickness (SPAWAR and ENVIRON, 2010; US EPA, 2005). Unintended cap material
movement may also occur after the initial placement and should be monitored, especially at the cap
edge (Palermo et al., 1998; ASTSWMO, 2009).
The chemical integrity of the cap is also monitored to ensure that the surface water
contaminant flux does not pose risk (US EPA, 2005). To do this, contaminant concentrations in the
surface and cap layer sediments as well as pore water and surface water can be examined as indicators.
An example of a monitoring conceptual model for chemical integrity is provided in Figure 3.
Box 5: Indicators for performance monitoring of capping remedial strategies to detect processes of concern.
Physical Integrity • Cap thickness, monitor for erosion
• Cap placement, monitor for cap movement
• Cap cohesiveness, monitor for disruption
Chemical Integrity • Water (pore and surface) and sediment (at and below
surface) contaminant concentrations, monitor potential flux
Impact of cap on hydrodynamics and sediment transport • Assess erosion, water column transport and deposition
changes on site
Adapted from ASTSWMO, 2009; Blake et al., 2007; Palermo et al., 1998; SPAWAR and ENVIRON, 2010; SPAWAR, 2003; US EPA, 2005.
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Figure 3 Example of a monitoring conceptual model for assessing the chemical integrity of a sediment cap (after US EPA, 2004).
The impact of the cap on site hydrodynamics and sediment transport processes, including
erosion, water column transport and deposition changes, is important to assess as these can impact
exposure risks associated with any contamination remaining on site. Detailed information regarding
hydrodynamics and sediment transport monitoring can be found in the User’s Guide for Assessing
Sediment Transport at Navy Facilities (Blake et al., 2007) and in the ISRAP tool (SPAWAR and ENVIRON,
2010). Habitat restoration and recolonization of the benthic (sediment-dwelling) and macrophyte
community on the cap surface are also important to monitor.
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Spatial and Temporal Considerations for Performance Monitoring
Specific site characteristics affecting risks to the cap integrity (see Box 6) should also be
accounted for in the monitoring plan, as they will affect the level of monitoring effort required. For
example, the frequency of low magnitude physical disturbances such as tidal and wave pumping as well
as boat propeller wash will also impact the expected rate of erosion for the cap; any changes to these
frequencies may require monitoring plan adjustments (US EPA, 2005; SPAWAR and ENVIRON, 2010).
Differences in cap design can subject the cap to different risks regarding physical integrity. For example,
if a cap has an armouring layer, it may be subject to cracking and weathering, which need to be
monitored. Caps at shallow water depths will also require greater monitoring following storm or erosion
events compared to deeper water situations (Palermo et al., 1998).
The USEPA (2005a) outlines recommendations regarding the frequency and time commitment
required for long-term monitoring following capping. The US EPA suggests annual checks of the physical
integrity in selected areas as well as a survey over the entire area every five years. Evaluation of the cap
chemical integrity every five years using a defined grid and monitoring ecological re-colonization based
Box 6 Site characteristics affecting level of effort required for monitoring.
Site Condition Considerations - Frequency of low magnitude disruptions such as wave and tidal pumping, as well as erosion
impacts as a result of navigational activity surrounding the cap: o Boat and ship propellers o Direct hull contact o Anchoring o Bottom drag fishing
- Altering flow patterns or erosion forces due to factors such as damming or breakwater modifications
- Seasonal weather conditions affecting ability to conduct monitoring and maintenance activities
Cap Design Considerations - Sediment cap height and water depth above cap - Incorporation of an armouring layer - Incorporation of a gravel layer
Adapted from: Palmero et al., 1998; SPAWAR and ENVIRON, 2010; US EPA, 2005a.
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on local expectations is also recommended. Similar temporal recommendations for cap performance
monitoring are provided by SPAWAR and ENVIRON (2010) in the on-line ISRAP sediment matrix and are
summarized in Box 7. Cap settlement and stability should be monitored beginning weeks after the cap’s
placement and continuing until there is enough data to be certain of the cap’s sediment stability in face
of potential site disturbances (several years). The chemical flux through the cap, which reflects cap
chemical integrity, should be monitored every one to five years beginning in the first weeks after
placement and continuing until remedial goals have been achieved. An event-based monitoring program
should also run congruently, requiring the examination of cap integrity following major physical
disturbances such as storms, ice scour, floods and earthquakes. Palermo et al. (1998) explain that it is
after these events when repair or replenishment may be needed and that acquiring an understanding of
the impact of events of different scales will help tailor later monitoring and maintenance efforts.
Site Closure Considerations
Although capping is viewed as a permanent remedy, long term monitoring is required since
contaminants remain on site (ASTSWMO, 2009). Ongoing maintenance and monitoring of the cap’s
structure is generally required in the US and Canada, meaning that site closure is likely not feasible. The
US EPA requires that while contaminants remain on site as they do in the case of capping, monitoring
must be conducted at least once every five years into perpetuity. However, as greater certainty is gained
Box 7 Recommendations regarding the frequency of performance monitoring required for capping.
Monitoring Objective Monitoring Timeframe
Monitoring Approach Monitoring Frequency
Physical Integrity Perpetually Temporal or Event-
Based Every 1-5 years or
following disruptive events Chemical Integrity Perpetually Temporal Every 1-5 years
Cap Impact on hydrodynamics &
sediment transport
After 1 monitoring round
N/A Once
Adapted from SPAWAR and ENVIRON (2010).
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regarding the stability and chemical flux associated with the cap in face of site disturbances, the level of
effort required for performance monitoring can be decreased.
III. Dredging
Strategy Overview
Dredging is used to remove contaminated sediments from a water body and is often applied as
part of navigational and environmental management strategies (NRC, 2007). The environmental
dredging process involves equipment mobilization and set up, site preparation, and sediment removal
and rehandling (Palermo, 1998). Removed sediment can then be treated or destroyed, although it is
often disposed in landfills, near-shore confinement facilities or in confined aquatic disposal facilities
(EPA, 2005a; SPAWAR, 2003).
Although there has been a historic preference of contamination removal, dredging alone is
presently viewed as an ineffective strategy for low sediment concentration goals due to unavoidable
residual contamination, resuspension, and contaminant release (Bridges et al., 2008; NRC, 2007;
SPAWAR and ENVIRON, 2010). Thus, environmental dredging often necessitates follow-up management
technologies such as backfilling, monitored natural recovery or capping to meet remedial goals
(ASTSWMO, 2009; NRC, 2007; SPAWAR and ENVIRON, 2010). Backfilling adds clean material to cover
and mix with residual contaminated sediments to reduce risk (NRC, 2007).
Performance Monitoring Indicators
Long-term monitoring to address the effectiveness of sediment replacement strategies or on-
site contaminated sediment disposal facilities is recommended. Dredging can lead to specific processes
that generate on-site risks, as outlined in Box 8. The resuspension and release of contaminated
sediments creates short-term risks, while residual contamination is of potential concern over the long-
term (NRC, 2007). The presence of residual contamination would typically be identified through
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confirmation sampling during remedial activities. If residual generation is a concern, it is usually
addressed by secondary strategy application such as MNR or capping and their respective performance
monitoring strategies.
Potential performance monitoring objectives related to dredging are shown in Box 9. Biological
monitoring would be incorporated into monitoring programs for ecosystem recovery. If follow-up
methods such as capping, backfilling or MNR are utilized to address residual contamination, monitoring
should be conducted to ensure that the remedial strategy is functioning as designed to reach site goals,
as discussed in earlier sections of this report. If sediment replacement is used to restore water levels
following dredging, monitoring of water depth and replacement material thickness, consolidation and
stability is recommended on a regular basis until the sediment has achieved the stability of the original
location (ASTSWMO, 2009). Any in-water or upland disposal facilities utilized should also be monitored
to ensure no contaminant release occurs and that the structures remain intact. Specific indicators
recommended for monitoring these facilities include: disposal unit integrity, groundwater, surface
water, and sediment or soil monitoring (USEPA, 2005a; NRC, 2007); an example of a monitoring
conceptual model is provided in Figure 4.
Box 8 Contaminant resuspension, release and residual generation processes.
- Resuspension: Dislodgment of embedded sediment - Release: Movement of contaminants from sediment and pore water into the water column. - Residual Generation: Generated residuals result from the redeposition of dislodged or suspended
sediments from resuspension and release processes. Undisturbed residuals were not uncovered or removed by dredging. -
- For information about site conditions that influence these processes, see NRC( 2007). Adapted from: NRC, 2007; Palermo et al., 2008; Patmont, 2006.
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Figure 4 Example monitoring conceptual model for monitoring the integrity of on-site disposal facilities for dredged sediments (after US EPA, 2004).
Spatial and Temporal Considerations for Performance Monitoring
Compared to other remedial technologies, dredged locations require the least level of effort for
monitoring because contaminated sediments are generally removed from the site (ASTSWMO, 2009;
NRC, 2007). However, greater monitoring effort would be required in situations where an engineered
containment facility (ECF) is used for dredged sediment disposal in-situ. Regardless of ECF use on site,
sites located near or in shorelines, at shallow water depths or in wetland areas generally require more
Box 9 Performance monitoring objectives for dredging (after USEPA 2004).
1. Do aquatic or land-based engineered contaminant disposal facilities on site effectively contain contamination and remain intact?
2. Have sediment-replacement initiatives proceeded successfully to achieve the depth, thickness and stability of original sediment bed?
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monitoring than deeper areas as they are more likely to have diverse biota populations as well as be
susceptible to weather events (ASTSWMO, 2009). Additional spatial considerations for monitoring
include: sampling beyond silt curtains used at the dredging perimeter; conducting studies both up and
downstream of dredging areas; and monitoring chemical indicators in deeper locations of lower energy
(ASTSWMO, 2009; NRC, 2007).
The EPA requires that monitoring be conducted at a minimum of every five years (US EPA,
2005a). However, monitoring of ECFs should also be conducted following extreme weather events (e.g.,
floods) and other erosion events. Under adaptive management protocols, it is recommended that a
review of monitoring decision points for site closure should be conducted on a regular basis, as shown in
Box 10.
Site Closure Considerations
Monitoring will be ongoing if any contamination remains on site that poses risk above the
remediation guidelines or if monitoring structures, such as ECFs, exist that require ongoing maintenance
(ASTSWMO, 2009; US EPA, 2005a). Canadian and US policy requires that if these conditions exist,
performance monitoring should be conducted at least once every five years into perpetuity. Otherwise,
once performance-specific goals have been reached, long term performance monitoring can be
concluded.
Box 10 Recommendations regarding the frequency of performance monitoring required for dredging.
Monitoring Objective Monitoring Timeframe Monitoring Approach Monitoring Frequency
Integrity of contaminated disposal facilities
Perpetually Temporal or Event
based Every 1-5 years or
following disruptive events Sediment replacement
initiatives After one monitoring
round N/A Once
Adapted from ASTSWMO, 2009; NRC, 2007; US EPA, 2005a.
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IV. In Situ Treatment
Strategy Overview
In situ treatment encompasses a variety of physical, chemical and biological technologies that
can be used to amend sediments in place by reducing or eliminating their toxicity or bioavailability
(ASTSWMO, 2009; SPAWAR, 2003). While there are advantages to treating sediment in place, such as
reduced contaminant handling and risks of resuspension or volatilization, as well as an ability to address
fluid-phase contaminants, in situ treatment options have been used at few contaminated sites to date
(Renholds, 1998; SPAWAR, 2003). Their current limitation is a result of the complicated nature of
sediment treatment compared to soil treatment or other non-treatment remedial options.
In-situ remediation technologies that are currently in practice include immobilization by
solidification or stabilization, chemical treatment, and bioremediation. Although solidification and
stabilization are not considered accepted sediment treatment approaches, they have been utilized on
small scales to treat metal contamination by injecting agents such as cement or fly ash to sediments
(EPA, 1994b; NRC, 1997; Renholds, 1998). Bioremediation provides amendments such as oxygen,
nutrients or microorganism inoculants to stimulate microbial degradation of organic contaminants in the
sediment (Knox et al., 2008; NRC, 1997; SPAWAR, 2003). Sediment bioremediation demonstrations have
been undertaken at the experimental and field scales, although further research is needed to address
microbial, geochemical and hydrological issues associated with this strategy (EPA, 1994b; NRC, 1997).
Chemical treatment methods deliver agents to detoxify contaminants by means of direct injection, gas-
permeable membranes or chemically reactive caps. Reactive capping aims to stabilize contaminants,
lower contaminant bioavailability and reduce contaminant release into the water column by placing
layers containing active amendments, possibly mixed with natural substrates or other inert materials,
over contaminated sediment (Paller and Knox, 2010). Imbedded amendment layers contain
sequestering agents to target specific contaminants and can include rock phosphates, organoclays,
- 24 -
zeolites, clay minerals or biopolymers (Knox et al., 2010). While chemical treatment technologies are not
considered reliable compared to traditional remediation methods, reactive capping has been utilized in
field trials and is perceived to have great potential as a permanent remedial solution (Knox et al., 2006).
Performance Monitoring Indicators
In situ treatments cover a large range of methods and processes, and the set of appropriate
monitoring indicators would depend on which treatment is used at the site. Considering the limited
application of in-situ treatment technologies and doubts regarding their long-term effectiveness,
performance monitoring is crucial to ensure the achievement of remedial objectives. To develop an
appropriate long-term monitoring plan to address performance-based success, it is important to
consider possible risks associated with each technology and subsequently develop relevant monitoring
objectives and approaches to address them. Examples of common treatment processes, associated
potential site risks, and general monitoring considerations have been highlighted in Box 11. Exemplary
monitoring objectives for in situ treatment are provided in Box 12 and an exemplary monitoring
conceptual model for reactive capping can be found in Figure 5.
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Box 11 Main categories of in situ treatment and associated processes of concern and monitoring considerations.
Category & General Aim
Description
Strategy-associated Processes of Concern
Comparable Traditional Technology
General Monitoring
Considerations Immobilization- Reduce contaminant mobility in place
Solidification - Additions to physically bind contaminants and convert sediment to block with high structural integrity
- Erosion - Increase in sediment volume, possible impact on dissolution and advection processes (site geochemical conditions) - Flux of contamination from sediment surface to water column
Capping - Physical integrity - Chemical integrity (chemical flux) - Impact on site hydrodynamics and sediment transport
Stabilization - Additions to reduce the solubility or mobility of the contaminants, with or without changing the physical characteristics of the treated material
Bioremediation - Promote natural biological processes to reduce toxicity
- Addition of microorganisms and/or chemicals to sediments to initiate or enhance bioremediation
- Changes in site conditions inhibiting processes - Product toxicity, bioavailability and mobility - Transformation reversibility - Achievement of desired transformation rates - Flux of contamination from sediment surface to water column
MNR - Chemical recovery processes - Chemical integrity (chemical flux)
Chemical Treatment - Detoxify or immobilize contaminants in place
Reactive Capping
-Place layers containing active amendments, possibly mixed with natural substrates or other inert materials, over contaminated sediment
- Erosion - Flux of contamination from sediment surface to water column - Impact of additions on dissolution and advection processes (site geochemical conditions) - Reversibility of detoxification and immobilization reactions - Achievement of bioavailability and toxicity reduction
Capping & MNR
- Physical integrity - Chemical integrity (chemical flux) - Impact on site hydrodynamics and sediment transport - Chemical recovery processes
Direct Injection
- Inject reactors for abiotic treatment into sediment subsurface
Gas Permeable Membranes
- Reactants delivered using gas permeable membranes
Adapted from ASTSWMO, 2009; Madalski, 2008; Magar et al., 2009; Magar and Wenning, 2006; NRC, 1997; Renholds, 1998; SPAWAR and ENVIRONl, 2010; SPAWAR, 2003.
- 26 -
Figure 5 Example of a monitoring conceptual model for reactive capping as an in situ treatment (after US EPA, 2004).
As outlined in Box 11, effective indicators for in situ treatments generally include those used for
MNR, such as monitoring applicable chemical or biological transformation, binding, precipitation or
sequestration processes stimulated by a specific treatment method. In the case of immobilization as
well as chemical sediment treatment, similar considerations to traditional capping would be
Box 12 An example of performance monitoring objectives for in situ treatment using reactive capping (after USEPA 2004).
1. Is the chemical integrity of capping material maintained over time and following disruptive events to ensure that risk posed by the contaminated sediment does not pose concern?
2. Is physical integrity of capping material maintained over time and in variable site conditions?
3. Is the impact of the cap on site hydrodynamics and sediment transport acceptable and as
predicted?
4. Have chemical transformation processes occurred as expected to meet remedial goals and is there confidence that they are irreversible?
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incorporated to monitor the stability and contaminant flux of the engineered components, in addition to
their possible impact on hydrodynamics. Additional ecological considerations would be incorporated
into ecological and habitat recovery monitoring to consider the potential ecological impacts of
chemically active amendments, such as toxicity and pH changes as well as changes in sediment texture
and particle size (Paller and Knox, 2010).
Spatial and Temporal Considerations for Performance Monitoring
Given the broad range of methods covered by in situ treatment strategies and the
complementary range of performance-based monitoring objectives, there are also many factors
affecting the spatial and temporal level of effort required for monitoring. Generally speaking, event-
based and temporally based monitoring should be undertaken to monitor any applicable chemical
recovery processes as well as the physical stability or integrity of any amendments associated with the
technology. Temporal monitoring should be conducted regarding the possible contaminant flux from
sediment into the water column and a one-time only assessment should be done regarding the potential
impact of sediment amendments on hydrodynamics and sediment transport. These temporal
considerations for monitoring are summarized in Box 13. Spatial considerations for monitoring would
also be specific to the treatment approach utilized. For example, if amendment addition was a
component of the treatment process, monitoring should be conducted both upstream and downstream
of the amended area as well as within the amended sediment and along its edge.
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Site Closure Considerations
Generally, if the site has met remedial goals and performance-based objectives, long-term
monitoring following in situ remediation can proceed to closure. Performance goal completion and
subsequent site closure procedures will be specific to the type of in situ treatment used. Due to the
limited application of these technologies outside of a research setting, little guidance is available
regarding site closure procedures following in situ treatment. Generally, process-specific considerations
would need to be geared to support the specific treatment strategy utilized. Performance monitoring
completion would be based on the achievement of objectives established to address performance-
associated risks outlined in Box 11, such as those provided in the example in Box 12. Monitoring
objectives for various in situ capping technologies can be similar to those for traditional treatment
technologies, especially for capping and MNR processes.
The US EPA requires that while contaminants remain on site, prior to the completion of in situ
treatment performance-monitoring objectives, monitoring must be conducted at least once every five
years. For sites remediated using chemical or biological transformation treatment methods, site closure
can proceed if the contaminant is degraded to meet remedial goals and there is confidence that the
Box 13 Recommendations regarding the temporal level of effort required for performance monitoring of in situ treatments.
Monitoring Objective Monitoring Timeframe Monitoring Approach Monitoring Frequency
Physical Integrity Perpetually
Temporal or Event-Based
Every 1-5 years or following disruptive
events Chemical Integrity Perpetually Temporal Every 1-5 years
Amendment Impact on hydrodynamics &
sediment transport
After one monitoring round
N/A Once
Chemical Recovery
Processes
Until confident in irreversibility
Temporal or Event-
Based
Every 1-5 years or following disruptive
events Adapted from Magar et al., 2009; SPAWAR and ENVIRON, 2010; US EPA, 2005a.
- 29 -
transformation is irreversible. If isolation treatment methods were used to reach remedial goals, site
closure for performance monitoring can be achieved when binding processes are demonstrated to be
stable given the site’s current and future geochemical conditions.
General Performance Monitoring Considerations
Site Complexity
Each contaminated site is uniquely affected by specific contaminants of concern at different
concentrations throughout the site. Varying ecological, geochemical, geographical, social, and economic
settings exist for each scenario and influence the selection of an appropriate remedial strategy (NRC,
2007). Individual sites can also exhibit varying characteristics within themselves and be quite complex.
This complexity requires integrated monitoring plans that may require a greater level of effort. For
example, a site may extend over multiple water bodies with varying use characteristics or have a wide
range of contaminant characteristics. When this is the case, multiple sediment remediation strategies,
such as capping, dredging, MNR or in situ treatment may be undertaken within the same site. This was
seen on the Hudson River site, as well as Lower Fox River & Green Bay site as showcased in the
Appendix 2 Case Studies. On these sites, dredging was undertaken to address areas most severely
contaminated, capping to address areas of low energy and MNR in areas of low concern. This complexity
motivates the need to develop complementary monitoring plans, combining considerations for multiple
treatment strategies to evaluate their performance.
Level of Effort
The level of effort refers to the spatial and temporal extent of sampling that should be
undertaken in order to ensure that a site’s performance monitoring plan is sufficient to evaluate remedy
effectiveness. Generally speaking, the spatial and temporal extent of monitoring should be determined
- 30 -
by strategy-specific and site-specific considerations. Strategy-specific considerations are referred to in
their respective sections above, while site-specific considerations are explored here.
Temporally, the monitoring program should extend through the period of most rapid change
and into the period of stabilization following remedial implementation in order to provide reasonable
assurance regarding whether the remedy will or will not meet its performance criteria (SPAWAR, 2003).
While more intense performance monitoring would be undertaken following the remedy construction
phase, or in the case of MNR, baseline monitoring (US EPA, 2005a), as the site is closer to achieving
outlined remedial objectives, the temporal intensity of monitoring may be decreased. An adaptive
management approach is recommended throughout performance monitoring, as the level of effort
should be adjusted based on remedy performance over time. For example, if there is concern regarding
whether the site will achieve remedial objectives within established time periods, the frequency of
monitoring should be increased to gather more information to decide if different remedial options need
to be applied. A case study highlighting adaptive management can be found in Appendix 2.
Monitoring may be conducted using a temporal or event-based approach depending on the
monitoring objective being investigated, site conditions, as well as available resources. For example, it is
important to consider seasonal weather conditions that may affect the ability to conduct monitoring at
different time periods (US EPA, 2005a). Event-based monitoring should be undertaken to examine
remedial performance following disruptive events that may pose additional risk, such as storms, ice
scour, flood flow stages, and earthquakes. It is logical to focus monitoring following these events to
determine if any maintenance or remedy adjustments are required in areas where the physical or
chemical integrity of remaining contaminated sediment may be compromised (Palmero et al., 1998;
SPAWAR and ENVIRON, 2010; US EPA, 2005a). Developing an understanding of the resiliency of remedial
processes and structures to disturbance events of varying severity can be used to adjust the level of
effort devoted to future monitoring.
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Spatial considerations are also important to incorporate when designing performance-based
monitoring plans. As discussed earlier when referring to specific remedial strategies, remedial
implementation success may vary across the site. Generally, this can be a result of natural variation in
environmental factors, contamination characteristics or remedial process implementation. For example,
the presence of bedrock, harbor infrastructure or debris may influence the ability to dredge effectively
across the site’s location (NRC, 2007). Another example of this would be when monitoring physical
integrity of a cap or contaminated disposal facility, high-energy areas should be monitored at a greater
temporal frequency than low energy areas, which are less prone to erosion risks. Determining
appropriate sampling locations may be based on site-specific characterizations, risk, technological
considerations, financial constraints or the presence of “hotspots” of contamination.
The level of effort required for monitoring is also influenced by the number of samples required
during each sampling event. Monitoring datasets need to be rich enough in order to determine the
remedy’s performance progress. Determining an appropriate sample size sufficient for robust
hypothesis testing and modeling is a statistically based decision. Standard statistical tests, such as those
discussed in the NRC’s Dredging at Superfund Sites document (2007), are utilized to draw conclusions
from the monitoring data. Tools to determine appropriate sample sizes and spatial sampling
frequencies can be found in the EPA document Guidance on systematic planning using the data
quality objectives process (2006).
The spatial and temporal extent of sampling undertaken to ensure that a site’s performance
monitoring plan is sufficient to evaluate remedy effectiveness should be determined by strategy-
specific, as discussed in sections above and site-specific considerations, as discussed here.
- 32 -
Summary of Main Points
• A review of international policy found that specific scientific guidance is lacking regarding long-
term monitoring programs for aquatic contaminated sites that lead to site closure. It is
recommended that Canada’s FCSAP protocol incorporate strategy-specific performance
monitoring plan elements that include exit criteria for site closure where appropriate.
• Performance monitoring goals, objectives, indicators, metrics, and associated completion
targets to evaluate if remedial processes are occurring as designed and document the
achievement of site closure if feasible are specific to the remedial strategy used at a site.
Developing and executing effective performance monitoring plans requires evaluation of the
mode of action for each remedial strategy and the processes that need to occur for remediation
to be successful.
• Performance monitoring considerations for four aquatic remedial strategies were evaluated:
monitored natural recovery (MNR), capping, dredging, and in situ treatment. The main
conclusions are as follows:
- Monitored natural recovery (MNR) involves the use of natural processes that act over time
to decrease the risk from contaminated sediments to acceptable levels. MNR performance
monitoring can therefore be quite varied due to the wide scope of remedial processes that
may occur at a specific site.
- Monitoring the physical and chemical integrity of a sediment cap is important to ensure
that contaminants are effectively isolated from the surrounding environment. Since
contaminants remain on the site at levels that may pose risk, site closure is generally not
feasible.
- 33 -
- Since dredging involves the physical removal of contaminated sediments, performance
monitoring following dredging is largely unnecessary. However, follow-up remedial
strategies and associated strategy-specific performance monitoring may be required if
significant residual contamination remains after dredging.
- In Situ treatment technologies encompass a large range of treatment methods that are
increasingly involved in site remediation. Within this category, similar remedial processes to
traditional strategies can be identified for performance monitoring.
• The level of effort required regarding temporal frequency of monitoring as well as the number
of samples collected depends on site-specific considerations as well as the type of remedial
strategy employed.
• Not all remedial strategies may lead to site closure, as continual performance monitoring is
required while contaminants remain on site in concentrations that may pose ecological and
human health risks.
• The information from this review was incorporated into the document “Developing Long-Term
Monitoring Programs that lead towards Site Closure for FCSAP Aquatic Contaminated Sites:
State of Science Review and Technical Guide,” prepared by the Environmental Sciences Group of
the Royal Military College to support policy development by the Federal Department of Fisheries
and Oceans.
- 34 -
Acknowledgements
- Dr. Ken Reimer, Professor at the Royal Military College of Canada, for his expert guidance and support as Primary Supervisor, as well as the invitation to participate in the assembly of the report entitled “Developing Long-term Monitoring Programs that Lead to Site Closure for FCSAP Aquatic Contaminated Sites: State of Science Review and Technical Guide” for the Department of Fisheries and Oceans (DFO).
- Dr. Tamsin Laing of the Environmental Sciences Group (ESG) at the Royal Military College of Canada
for her expert direction, feedback and encouragement throughout the project as Secondary Supervisor.
- Dr. Daniela Loock, Dr. Astrid Michels, and Viviane Paquin of the Environmental Sciences Group (ESG) for their feedback on the report content and direction.
- Keith Lennon (DFO) and Eric Chiang (DFO) for their valuable feedback regarding the scientific content.
- Dr. Brian Cumming for his coordination throughout the ENSC 501 course.
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Appendixes: Performance Monitoring Case Studies
Case Study: Hudson River
Site Custodian: General Electric Co. Site Location: New York, United States US EPA Region 2 Primary Sediment Contaminant: PCBs Sediment Remedial Strategies Applied:
Dredging, Capping, Monitored Natural Recovery Site Summary: This project is currently in progress. Phase 1 of the project, dredging 9.6 km of the river, has been completed. It is now proceeding to its second and final phase, involving additional dredging as well as capping and MNR in some site areas. The monitoring scope has been developed to follow Phase 2 efforts and a summary of it is used here as a performance monitoring plan case study to exemplify considerations for a multi-strategy, complex site. Further Site Information: http://www.epa.gov/hudson United States Environmental Protection Agency. (US EPA). 2010. Operation, Maintenance, and Monitoring Scope for Phase 2 of Remedial Action. Attachment E to Statement of Work Hudson River PCBs Site. http://www.epa.gov/hudson/phase2_docs/attachment_e.pdf (accessed 03 16, 2011). -----------------------------------------------------------------------------------------------------------------------------
Summary of Performance Monitoring Plan
Dredging No performance monitoring was outlined to address dredging performance since dredged sediment was disposed off-site and secondary strategies to address residual contamination were monitored. Monitored Natural Recovery 1. Objective: Determine post-remediation PCB concentrations in sediments in non-dredge areas
and backfill areas of the Upper Hudson River. Indicator: Sediment chemistry
Metrics: Total Organic Carbon, PCB concentrations Monitoring Approach: Temporal
Frequency: Every 3 years Exit criterion: Recovery criterion met.
2. Objective: Provide data on select areas that exceeded the removal criteria that were not
targeted for dredging because evidence suggested that burial by cleaner sediments was occurring. The monitoring objective is to assess whether the deposits have experienced
Figure 6 Dredging the river during Phase 1 of remediation. Source: http://www.hudsondredging.com/
- 40 -
erosion. Indicator: Bathymetric surveys
Metrics: Sediment height Monitoring Approach: Temporal
Frequency: First and ninth years following dredging Exit criterion: Following two investigations.
3. Objective: Determine sedimentation and resuspension rates in areas of the Upper Hudson River that were not dredged.
Indicator: Sediment Chemistry Metric: Bereillium-7 radioisotope level Monitoring Approach: Temporal
Frequency: Every 3 years Exit criterion: Specific Berillium-7 concentrations to inform whether recovery criterion met.
Capping 1. Objective: Determine whether the physical integrity of individual cap layers/components has
been maintained. Indicator: Cap material characteristics Metric: Sediment Thickness Monitoring Approach: Temporal and Event Based Frequency:
- Annually for 5 years, then every 5 years, then every decade. - Immediately following events that are at or exceed design characteristics
Exit criterion: N/A - monitor into perpetuity
2. Objective: Determine whether the effectiveness of the cap for chemical isolation has been maintained. Indicator: Sediment Chemistry Metric: PCB Concentration Monitoring Approach: Temporal and Event-Based Frequency:
- Every 10 years - Following flood events at or exceeding design specifications
Exit criterion: After 30 years, or when cap determined to meet design specifications. -------------------------------------------------------------------------------------------------------------------------------
Performance Monitoring Plan Reflections
Specific targets associated with each metric to indicate successful remedy performance could be specified in the performance monitoring plan.
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Case Study: McCormick & Baxter Creosoting Co.
Site Custodian: US EPA Site Location: Portland, Oregon US EPA Region 9 Primary Sediment Contaminants: Arsenic, PAHs, PCP, dioxin, NAPL Sediment Remedial Strategies Applied: Capping, In Situ Remediation Site Summary: As a result of earlier industrial activity, the site soil, groundwater and the sediment of the nearby Stockton Channel, Old Mormon Slough and
NewMormon Slough were contaminated. Regarding the sediment remediation, Phase I of the sediment remedy (bank stabilization) was completed in 2003 and Phase II (placement of a sand cap over the contaminated sediment) was completed in 2006. The multi-layer sediment cap was composed of sand (2-5 ft. covering contaminated sediment), organoclay (In Situ Remediation component: has affinity for organic compounds to prevent release of NAPL phase) and armouring (6-inch-minus, 10-inch-minus and riprap). Articulating concrete block (ACB) mats were installed along the shore and in shallow water where erosive forces would be the greatest due to wave action. Further Site Information: http://www.mandbsuperfund.com/SitePages/Home.aspx Oregon Department of Environmental Quality (DEQ). 2006. Second Five-Year Review Report for McCormick and Baxter Creosoting Company Superfund Site Portland, Multnomah County, Oregon. ORD009020603. Hart Crowser, Inc. and GSI Water Solutions, Inc.. 2010. Operational and Maintenance Report January 2009 to December 2009 McCormick and Baxter Superfund Site Portland, Oregon. Oregon Department of Environmental Quality. 15670-05/Task 7. -----------------------------------------------------------------------------------------------------------------------------
Summary of Performance Monitoring Plan
Capping 1. Objective: Maintain contaminant concentrations in surface sediments below the following
risk-based cleanup goals, as specified in the record of decision. Indicator: Surface sediment chemistry
Metrics: concentration of Arsenic, Pentachlorophenol (PCP), Total carcinogenic PAHs (cPAHs), Dioxins/furans
Monitoring Approach: Unspecified – assumed to be temporal, every 5 years. Exit criterion: Perpetual monitoring to see maintenance of levels of arsenic – 12 mg/kg,
dry weight; PCP – 100mg/kg dry weight, cPAHs – 2mg/kg, dry weight;
Figure 7 McCormick & Baxter site overview, cap outlined indicated in royal blue. Source: http://www.mandbsuperfund.com/SitePages/Home.aspx
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Dioxins/furans – 8 x 10 -5 mg/kg dry weight.
2. Objective: Identify potential areas of concern in the cap through monitoring visible discharge of creosote to the Willamette River, indicative of degradation of chemical integrity. Indicator: Water appearance Metric: Shoreline sheen or ebullition visibility Monitoring Approach: Temporal Frequency: Weekly basis during extreme low river stages (Sept – Oct) Exit criterion: Perpetual monitoring of the presence or absence of sheen and ebullition.
3. Objective: Minimize releases of contaminants from sediment that might result in contamination of Willamette River in excess of Federal and State ambient water quality criteria Indicator: Surface water chemistry, Inter-armor and sub-armor pore water chemistry. Metrics: concentration of total metals (arsenic (III), chromium (III), copper and
zinc), PCP, PAHs (acenaphthene, fluroanthene, naphthalene, total carcinogenic PAHs (TPAH), dioxans/furans), total suspended solids (TSS), total dissolved solids (TDS), dissolved metals
Monitoring Approach: Temporal Frequency: Semi-annually Exit criterion: Perpetual monitoring of water quality compared to a group of water quality
criteria and recommended values: arsenic (III) – 190 μg/L; chromium (III) – 210 μg/L; copper – 12μg/L; zinc – 110 μg/L; PCP – 13 μg/L; acenaphthene – 520 μg/L; fluroanthene; naphthalene – 620 μg/L; TPAHs – 0.031μg/L; dioxans/furans – 1 x 10-5 ng/L
4. Objective: Maintain armouring layer to within 50% of design specifications and uniformity
and continuity of articulate concrete block (ACB) on shoreline Indicator: Rock armouring, ACB
Metric: Rock armouring thickness, appearance of ACB Monitoring Approach: Temporal
Frequency: In-water surveys conducted annually in spring, or as needed. Near-shore areas (ACB) examined weekly
Exit criterion: Perpetual monitoring to maintain the following: 6-inch rock armouring – maintain thickness of a min. 6 inches, 12-inch rock armouring – maintain thickness of a min. 7.5 inches, 24-inch rock armouring – maintain thickness of a min. 12 inches ACB characteristics not specified
In Situ Treatment:
1. Objective: Maintain sorption capacity of the organoclay cap. Indicator: Organoclay Chemistry
Metric: Organoclay creosote concentration Monitoring Approach: Temporal Frequency: 2006, 2008, 2009, 2015, and then every 5 years. Exit Criterion: Perpetual monitoring to maintain at least 20% excess sorption capacity of cap.
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Adaptive Site Management Performance Monitoring Plan In response to observed gas bubbles escaping from the surface of the cap, as well as sheen observed on the surface water above the sediment cap, additional monitoring was conducted, exemplifying an adaptive site management approach. The monitoring program implemented in 2008 and was referred to as their Ebullition and Sheen Investigation. Some of the main components are summarized here. For more information, please see the report below. Hart Crowser, Inc. & GSI Water Solutions, Inc.. 2009. Operations and Maintenance Report January 2008 through December 2008, Appendix G: Ebullition and Sheen Investigation. 15670-03/Task 9. Capping:
1. Objective: Determine if chemical integrity of cap is maintained, or whether creosote and PAH contamination is fluxing through the cap via an ebullition pathway.
Indicator: Cap sand layer physical properties, Nature of cap sand layer Metric: Cap sand layer thickness, Evidence of visible NAPL contamination in sediment core Monitoring Approach: Temporal Frequency: 2008, 2009 Exit Criterion: Not specified, monitoring for specific investigative purpose.
Indicator: Surface water, pore water & sediment chemistry
Metric: surface water, pore water and sediment PAH concentration Monitoring Approach: Temporal Frequency: 2008, 2009, 2015, and then every 5 years
Exit Criterion: Perpetual monitoring to maintain l surface water concentration of 0.018μg/L (associated with ebullition escape from cap). Otherwise not specified, assumed to be ceased following specific study.
2. Objective: Understand extent, frequency and seasonality of sheen releases Indicator: Surface water appearance Metric: Sheen appearance classification Monitoring approach: Temporal Frequency: Weekly during 2008.
Exit Criterion: Not specified, monitoring for specific investigative purpose. Information gathered compared to previous year’s data.
3. Objective: Determine if ebullition is a potentially significant contaminant pathway.
Indicator: Gas and water samples from cap sediment flux Metric: Concentration of contaminants in flux, frequency of flux Monitoring approach: Temporal Frequency: One set of sampling events in 2008 Exit Criterion: Not specified, monitoring for specific investigative purpose.
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In Situ Remediation 1. Objective: Determine if organoclay mats are performing as designed.
Indicator: Organoclay adsorptive capacity, permeability, chemistry in cap sand, porewater
Metric: Organoclay chemistry, gas permeability rates, contaminant concentration in cap sand surrounding cap, pore water contaminant concentrations
Monitoring Approach: Temporal Frequency: 2008, 2009 Exit Criterion: Not specified, assumed to be ceased following specific study. Compared contaminant concentration to concentrations in surrounding sediment.
2. Objective: Determine if degradation is occurring in the cap to break down the organophillic clay in a manner that will impact longevity.
Indicator: Cap Organoclay Chemistry Metric: Hexane extractable material level (degradable organic matter level), total organic carbon, NAPL visual saturation. Monitoring Approach: Temporal Frequency: 2008, 2009 Exit Criterion: Not specified, assumed to be ceased following specific study.
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Performance Monitoring Plan Reflections
- The monitoring approach and frequency of could be more clearly discussed for some
objectives. - Data was provided regarding sampling completed to date, although future monitoring
requirements beyond 2011 could also have been outlined. - Adaptive site management was used in a timely fashion in order to accommodate new
information that raises important questions for monitoring.
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Case Study: Lower Fox River & Green Bay
Site Custodians: Brown County, East Bay, US EPA, Georgia-Pacific Consumer Products LP Site Location: Green Bay, Wisconsin, US US EPA Region 5 Primary Sediment Contaminant: PCBs Sediment Remedial Strategies Applied: Capping, Monitored Natural Recovery, Dredging Site Summary: In some site areas, dredging is used to remove contaminated sediment followed by sand covers or engineered cap placement in most severely contaminated regions. Dredged sediment is disposed in off-site, upland landfills. Some site areas of lower concentration were not dredged, although received sand covers. Monitored natural recovery is used in other site areas based on natural sedimentation processes. Further Site Information: http://www.epa.gov/region5/sites/foxriver/index.html Anchor Environmental, L.L.C., Tetra Tech EC, Inc., J. F. Brennan Co, Inc., Boskalis Dolman. 2008. Lower Fox River Remedial Design 60 Percent Design Report for 2010 and Beyond Remedial Actions, Appendix H: Operation, Maintenance and Monitoring Plan. Prepared for: Appleton Papers Inc., Georgia-Pacific Consumer Products LP NCR Corporation. -----------------------------------------------------------------------------------------------------------------------------
Summary of Performance Monitoring Plan
Dredging No monitoring was included in OMMP to address dredging performance since dredged sediment was disposed off-site and secondary strategies to address residual contamination were monitored. Capping
1. Objective: Ensure that the cap’s thickness does not diminish by erosion. Indicator: Cap sediment
Metrics: Cap surface elevation and cap material thickness Monitoring Approach: Temporal and event based, performed in all cap areas
Frequency: - Minimum of every 2 years following initial construction monitoring,
continuing every 5 years afterwards - Following flood event of a recurrence interval of 20 years or more,
following major river construction, or if there is a greater than 1 foot drop in water levels compared to cap design specifications. If cap integrity and performance is verified following a 20-year event, event based monitoring will be undertaken following 50-year events.
Figure 8 Site overview - Green Bay and the Lower Fox River. Source: Anchor et al., 2008.
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Exit criterion: N/A – monitor into perpetuity, compare data to baseline measurements and to minimum cap isolation or armour/bioturbation layer thickness. Response actions such as cap repair, additional institutional controls, or cap removal and dredging are required when comparisons indicate concern in more than a minor area of the cap.
Cap A: Minimum 7 inches of in-place sand and gravel Cap B: Minimum of 10 inches of in-place sand and gravel Cap C: Minimum of 18 inches of in-place sand, gravel and armour material Shoreline caps: Specifications vary – may resemble Caps A-C above.
*Note regarding Monitoring Location: focused monitoring in capping areas with high peak bottom shear stresses from floods, seiches, wakes, propeller wash and/or other forces.
2. Objective: Ensure that chemicals of concern from the underlying sediments do not migrate
through the cap and into the river. Indicator: Surface sediment chemical profile Metric: PCB concentrations
Monitoring Approach: Temporal and event based Frequency: - Additional monitoring conducted based on results of initial sediment
height indicator results - Minimum of every 2 years following initial construction monitoring,
continuing every 5 years afterwards - Following particularly disruptive events
Exit criterion: N/A – monitor into perpetuity. No action taken if PCB concentrations are less than 2.0ppm. If breakthrough is indicated, response actions such as increasing the thickness of the cap, increasing monitoring level of effort or cap removal and dredging are undertaken. *Note Conducted in capping areas associated with high bottom shear stresses.
Monitored Natural Recovery 1. Objective: Confirm that sedimentation processes proceeding as predicted.
Indicator: Sediment chemistry Metric: PCB concentration and Total Organic Carbon
Monitoring Approach: Temporal and event based Frequency:
- Minimum of every 2 years following initial construction monitoring, continuing every 5 years afterwards
- Following particularly disruptive events Exit criterion: N/A – monitor into perpetuity, compare data to baseline sampling data to determine if additional cap maintenance is required. Samples containing concentrations less than 0.25ppm during early sampling event will not be included as sampling locations in later monitoring efforts.
-------------------------------------------------------------------------------------------------------------------------------Performance Monitoring Plan Reflections - Specific monitoring objectives for MNR were not clearly outlined.
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Case Study: Saglek, Labrador
Site Custodian: Department of National Defence Site Location: Saglek, Labrador Primary Sediment Contaminant: PCBs Sediment Remedial Strategy Applied: MNR Site Summary: Marine sediment was contaminated as a result of contamination of an adjacent beach. After active terrestrial remediation removed the source of contamination, sediment burial and transport was predicted to reduce ecological and human health based risks as a result of the movement of contaminated sediments within 10 years to deeper aquatic locations not accessible to receptors of concern. Further Site Information: http://www.rmc.ca/aca/cce-cgc/gsr-esr/esg-gse/saglek-eng.asp Environmental Sciences Group. 2008. Assessing Marine Ecosystem Recovery from a Local Historical PCB Source in Saglek, Labrador. Prepared for: North Warning System Office. RMC-CCE-ES-08-13. -------------------------------------------------------------------------------------------------------------------------------
Summary of Performance Monitoring Plan
1. Objective: Validate the sediment transport model to compare the distribution of predicted PCB concentrations in sediment over time.
Indicator: Contaminant depth profile Metric: PCB concentration, grain size, total organic carbon Monitoring Approach: Temporal
Frequency: 2006, 2009, 2010 and plans for two additional years Exit criterion: Compare PCB distributions throughout the basin sediment to
predicted distributions from the sediment transport model. Discontinue monitoring when the average sediment PCB concentration has decreased below 77ppb at up to a 40m depth in zones of concern (a risk-based criterion to protect guillemot receptors).
2. Objective: Re-map sediment bathymetry to gain an understanding of the frequency and
magnitude of sediment transport events such as underwater slope failures, which can potentially lead to the reworking of contaminated sediments and deviation from the predicted sediment transport model.
Indicator: Sub-bottom profile Metric: Sediment elevation
Monitoring Approach: Temporal Frequency: Once
Exit criterion: Following understanding of the influence of mass sediment transport events on overall movement of sediments over time.
Figure 9 Active soil excavation on site conducted to remove source of sediment contamination. Image Source: http://www.rmc.ca/aca/cce-cgc/gsr-esr/esg-gse/saglek-eng.asp
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-------------------------------------------------------------------------------------------------------------------------------Performance Monitoring Plan Reflections - Performance monitoring plan could outline exit criteria more specifically. - Monitoring frequency could more clearly outlined.
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Case Study: Grasse River
Site Custodians: Alcoa Inc., US EPA, Department of Defence Site Location: Massena, New York Primary Sediment Contaminant: PCBs Sediment Remedial Strategy Applied: In Situ remediation using Activated Carbon Site Summary: This site was a pilot project conducted by Aloca Inc. in 2006 to assess the use of in situ remediation using activated carbon application to the upper layer of the contaminated sediment bed to remediate widespread, diffuse PCB contamination. Activated carbon has been shown in previous studies to decrease the bioaccumulation of PCBs in aquatic life. Other, more traditional remedial technologies have been piloted on the site to reduce PCB concentrations in sediment, water and fish. A three-year monitoring plan was conducted following the application of the activated carbon to evaluate the treatment effectiveness. Further Site Information: http://www.thegrasseriver.com/ Alcoa Inc.. 2006. In-Situ PCB Bioavailability Reduction in Grasse River Sediments. Final Work Plan. Available at: <http://www.thegrasseriver.com> and Massena Public Library, Massena, NY. -------------------------------------------------------------------------------------------------------------------------------
Summary of Performance Monitoring Plan
1. Objective: Evaluate the sediment stability in the pilot study area after treatment with activated carbon. Indicator: Sediment physical characteristics
Metric: Total suspended solids Monitoring Approach: Temporal
Frequency: 12 and 24 months following remedy application. Exit Criterion: N/A, study conducted over 2-year period.
2. Objective: Evaluate the uniformity of mixing of activated carbon for in-situ sediments. Indicator: Sediment chemistry and physical properties
Metric: PCB congeners, visual abundance of carbon particles, sediment TOC level Monitoring Approach: Temporal
Frequency: 12 and 24 months following remedy application. Exit Criterion: N/A, study conducted over 2-year period.
Figure 10 Grasse River Site Overview. Source: Alcoa, 2006.
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3. Objective: Evaluate the activated carbon effectiveness: aqueous equilibrium and PCB desorption Indicator: Surface sediment chemistry (top 3 inches)
Metric: PCB congeners, aqueous equilibrium Monitoring Approach: Temporal
Frequency: 12 and 24 months following remedy application. Exit Criterion: N/A, study conducted over 2-year period. -------------------------------------------------------------------------------------------------------------------------------
Performance Monitoring Plan Reflections
Monitoring was only intended to occur over 2-3 years following the pilot study remedial implementation. For this reason, site closure considerations were not developed for this site and endpoints were based on time, not remedial performance.
Plan examined had specific objective statements and indicator/metric information clearly displayed in table format.