Management

Section III: Management

Prior to any remedial action, permits and approvals may be required under different legislation. An overview of legislation which may impact sediment management decisions, as well as a brief overview of some remedial options, was previously outlined in An Integrated Approach to the Evaluation and Management of Contaminated Sediments (MOE 1996). This guidance has been updated here to reflect new and amended legislation. However, this document is not intended to provide legal advice and it should not be construed as such. The relevant and applicable legislation should be reviewed and considered before proceeding with a project. It may also be prudent to consult with a lawyer before proceeding with any sediment management option. Updates and amendments to legislation can be accessed through the e-Laws web site.

8. Legislation

8.1 Legislative requirements

Prior to commencing any remediation project, consideration needs to be given to which permits and approvals will need to be obtained and from which appropriate agencies. Depending upon site-specific conditions, a project may require a number of permits or approvals from various government agencies and levels of government, all of which may have jurisdiction over certain aspects of the project.

For example, most large sediment removal projects undertaken by the Province will be subject to the requirements of the Environmental Assessment Act, R.S.O. 1990, c. E.18, as amended. Consideration needs to be given as to whether any exemptions would be applicable to a particular project. Generally speaking, environmental assessments have to identify the potential environmental impacts of all aspects of the remediation project, as well as identifying proposed mitigation measures, the consequences of not performing the project, etc.

Various types of approvals may also be required for work in streams and lakes. For example, the removal of contaminated sediment from a stream using cofferdams and excavating equipment, may require approval under one or more federal or provincial pieces of legislation for example the Navigable Waters Protection Act, R.S. 1985, c. N-22, the Environmental Assessment Act, R.S.O. 1990, c. E.18 as amended, the Public Lands Act, R.S.O. 1990, c. P.43 as amended, and the Conservation Authorities Act, R.S.O. 1990, c. C.27 as amended.

Where the severity of the problem indicates that some type of remedial action will likely be necessary, consideration should be given to proceeding with applications for approvals and permits in the early stages of the project. Such applications can then proceed concurrently with assessment studies.

8.2 Federal legislation

A number of federal Acts apply to remediation work and may require permits and/or approvals in order to carry out remediation projects. Federal legislation can be divided into two groups: federal legislation applying to all proponents, and legislation and policies applying only to federal government departments.

8.2.1 Canadian Environmental Assessment Act

The Canadian Environmental Assessment Act, R.S.C. 1992, c. 37 (CEAA) is administered by the Canadian Environmental Assessment Agency. The Canadian Environmental Assessment Agency is an independent agency that reports directly to the federal Minister of the Environment. The CEAA requires that federal departments, including Environment Canada, agencies, and crown corporations conduct environmental assessments for proposed projects where the federal government is the proponent. It also requires environmental assessments when the project involves federal funding, permits or licenses.

The CEAA and its regulations set out the legislative responsibilities for the environmental assessment of projects that involve the federal government. The CEAA has four fundamental purposes:

• to ensure that the environmental effects of projects receive careful consideration before responsible authorities take action in connection with them;
• to encourage responsible authorities to take actions that promote sustainable development and thereby achieve or maintain a healthy environment and economy;
• to ensure that projects carried out in Canada or on federal lands do not cause significant adverse environmental effects outside the jurisdictions in which the projects are carried out; and
• to ensure that there is an opportunity for public participation in the environmental process.

An environmental assessment is required if a federal authority is required to exercise one or more of the following duties, powers or functions in relation to a project:

• proposes the project
• grants money to a project
• grants an interest in land to a project
• exercises a regulatory duty in relation to a project, such as issuing a permit or licence that is covered under the Law List regulation (SOR/94-636).

Similar to the Environmental Assessment and Review Process (EARP; the process used prior to the CEAA), the CEAA is based on the self-assessment of projects for environmental effects, by federal departments and agencies. The responsible authority may conduct an EA in the form of screening, class screening or comprehensive study.

Under a screening, a responsible authority has the greatest degree of management and flexibility over the scope and pace of the EA process. In cases where there is a sound knowledge of the environmental effects and appropriate mitigation measures for a group or class of projects, the responsible authority may be able to use all or part of a class screening report. The majority of projects covered by the CEAA will undergo an EA through a screening.

Under a comprehensive study, the responsible authority also retains a primary management role over the EA, but has more obligations than in a screening. These include the need to consider a wider range of factors, submit the comprehensive study report to the Agency for review, take public comments into account and consider the need for a follow-up program.

If the screening or comprehensive study identifies the need for further assessment, the project must move to a public review in the form of either a mediation or panel review.

8.2.2 Canadian Environmental Protection Act, 1999

A key aspect of the Canadian Environmental Protection Act, 1999, S.C. 1999, c.33 (CEPA) is the prevention and management of risks posed by toxic and other harmful substances. CEPA provides for the regulation of federal works, undertakings, and federal lands and waters, where existing legislation administered by the responsible federal department or agency does not provide for the making of regulations to protect the environment. In addition, there are provisions for the creation of guidelines and codes for environmentally sound practices and for setting objectives for desirable levels of environmental quality.

8.2.3 Migratory Birds Convention Act, 1994

The purpose of the Migratory Birds Convention Act, 1994, S.C. 1994, c. 22 (MBCA) is to protect and conserve migratory birds, as populations and individual birds, and their nests. The MBCA prohibits the disposal of any substances harmful to migratory birds in any waters or areas frequented by migratory birds (subsection 5.1(1)). In the context of identifying, assessing and managing contaminated sediments in Ontario, the MBCA may be applicable when dealing with the disposal of dredged material.

8.2.4 Fisheries Act

The Fisheries Act, R.S.C. 1985, c. F-14, regulates any activities that can potentially disrupt fish or fish habitat. The Fisheries Act applies to sediment remediation activities that may disrupt fish or fish habitat, which includes all manner of in-stream or in-lake activities associated with sediment remediation projects. Two sections of this Act are particularly relevant: Section 36 regulates the deposition of any substance (which would include contaminated sediment) which is deemed "deleterious" in waters frequented by fish. Section 35 regulates the alteration of fish habitat, including alteration, disruption or destruction of habitat (where habitat is defined as "spawning grounds and nursery, rearing, food supply and migration areas on which fish depend, directly or indirectly, in order to carry out their life processes").

8.2.5 Navigable Waters Protection Act (NWPA)

The Navigable Waters Protection Act, R.S.C. 1985, c. N-22 (NWPA) prohibits any work on, in, upon, under, through or across a navigable waterway. "Work" has been defined to include projects that involve the dumping of fill or the excavation of materials from the bed of navigable waters as well as dredging or disposal operations. An application for exemption is required for such projects. Prior to granting the exemption, Transport Canada reviews the implication of the project for potential impact on navigation.

8.2.6 Canada Water Act

The Canada Water Act, R.S.C. 1985, c. C-11, provides for management of the water resources of Canada, including research and the planning and implementation of programs relating to the conservation, development and utilization of water resources. Part II of the act specifically deals with water quality management and the pollution of waters.

8.3 Provincial legislation

Various Provincial Acts, administered by a number of ministries, may apply to sediment remediation activities.

8.3.1 Environmental Assessment Act

The Environmental Assessment Act, R.S.O. 1990, c. E.18 (EA act) applies to projects being carried out by the Province, municipalities, or public bodies (for example, Conservation Authorities and the Ontario Realty Commission). These public sector actors may have obligations under the Environmental Assessment Act in respect of contaminated sediment management activities and should consult with the Ministry’s Environmental Assessment and Approvals Branch.

8.3.2 Environmental Protection Act

The Environmental Protection Act, R.S.O. 1990, c. E.19 (EPA) regulates the discharge of contaminants and pollutants (including "spills") into the natural environment. The Act aims to protect and conserve the natural environment and to protect human health and plant and animal life from injury and damage and provides for the "repair" of any such damage. This Act has broad applicability to remediation activities.

8.3.3 Ontario Water Resources Act

The discharge of any material into water that impairs or may impair water quality is prohibited by the authority of the Ontario Water Resources Act, R.S.O. 1990, c. O.40 (OWRA). Subsection 1(3) of the Act sets out a list of what constitutes “deemed impairment”. This includes, but is not limited to, material or derivative which causes or may cause injury to or interference with any living organism that lives in or comes into contact with the water or soil or sediment that is in contact with the water; or which causes or may cause a degradation in the appearance, taste or odour of the water, or which causes or may cause injury to or interference with any living organism as a result of it using or consuming the water, soil or sediment that is in contact with the water or any organism that lives in or comes into contact with the water or soil or sediment that is in contact with the water.

8.3.4 Clean Water Act, 2006

The Clean Water Act, 2006 S.O. 2006, c.22 takes a watershed-based approach to source water protection and addresses all sources of drinking water. Its purpose is to protect existing and future sources of drinking water. Source water protection is the first barrier in a multi-barrier approach to protecting the water in Ontario’s lakes, rivers and underground aquifers, and it complements water treatment by reducing the risk that water gets contaminated in the first place. Where contaminated sediment impacts the quality of source water, the Act and associated regulations may require remediation actions to occur.

8.3.5 Brownfields Amendments (Record of Site Condition Regulation)

Amendments made to Ontario’s EPA and OWRA, among other provincial statutes, in 2003 are commonly referred to as “the Brownfields Amendments”. Several documents are available that provide information on these amendments, including:

• Ontario Regulation 153/04 (as amended) Records of Site Condition – Part XV.1 of the Environmental Protection Act.
• Soil, Ground Water and Sediment Standards for Use Under Part XV.1 of the Environmental Protection Act (March 9, 2004)
• Procedures for the Use of Risk Assessment under Part XV.1 of the Environmental Protection Act (October, 2005).

This regulation and supporting documents have replaced Guidelines for Use at Contaminated Sites in Ontario (MOE, 1997). A key component of the Brownfields Amendments is the introduction of a Record of Site Condition (RSC), which is used to document the assessment and remedial work conducted at a contaminated property. For properties where sediments are a component of the risk assessment, the legislation and applicable regulations should be consulted for details.

8.3.6 Beds of Navigable Waters Act (R.S.O. 1990, c. B4)

The requirements of the Beds of Navigable Waters Act, R.S.O. 1990, c. B.4, may impact on projects involving beds of “navigable waters”. While the term “navigable waters” is not defined in this Act, it is a term which has been interpreted by the courts over the years. Title to the beds of navigable waters is restricted through grants by the Lieutenant-Governor. Ownership of lands bordering navigable waters does not provide right of use of the beds of those waters.

8.3.7 Public Lands Act

The management, sale and disposition of public lands, which includes the beds of most lakes and rivers as well as seasonally flooded areas, is controlled by the Public Lands Act, R.S.O. 1990, c. P.43. The Ontario Ministry of Natural Resources (OMNR) may define zones as open, deferred or closed for disposition. The Public Lands Act also regulates development, construction, or alteration of any public shorelands, which may apply to remediation projects. All shoreline construction work will require a Work Permit issued by OMNR under this legislation.

8.3.8 Conservation Authorities Act

The restricting or regulating of water through the construction of dams or diversions or depressions in rivers and streams and the placing and dumping of fill within the watershed is placed under the jurisdiction of the local Conservation Authority, under the Conservation Authorities Act, R.S.O. 1990, c. C.27. This Act would be broadly applicable to flow diversions such as coffer dams, channelling, etc. as part of the remediation project.

8.3.9 Lakes and Rivers Improvement Act

Approval for any work that consists of forwarding, holding back or diverting water (e.g., construction of coffer dams for stream remediation) is required from the OMNR under the Lakes and Rivers Improvement Act, R.S.O. 1990, c. L.3. Furthermore, the deposition of any substance or refuse into a lake or river or on the shore is prohibited by this Act.

8.3.10 Planning Act

The Provincial Wetlands Policy Statement, which was issued under the Planning Act, R.S.O. 1990, c. P13 addresses wetland protection and management within the land use planning process.

8.3.11 Mining Act

All aspects of mining activities within the province are regulated under the Mining Act, R.S.O. 1990, c. M14.

8.3.12 Nutrient Management Act, 2002

The purpose of this Nutrient Management Act, S.O. 2002, c. 4 (NMA) is to provide for the management of materials containing nutrients in ways that will enhance protection of the natural environment and provide a sustainable future for agricultural operations and rural development.

8.4 Municipal legislation and policies

Municipal legislation and policies will affect a project where shoreline or upland disposal is to be used. In these cases, municipal zoning or planning guidelines may have to be considered and taken into account. Since each municipality may have different requirements, the proponent is advised to contact the appropriate municipal office during the initial screening stage of the project. Contacting the municipal office will also permit the proponent to assess the need for public information sessions to facilitate public acceptance of the project.

8.5 Great Lakes Water Quality Agreement (GLWQA, 1978)

The Great Lakes Water Quality Agreement is an agreement between Canada and the United States to restore and enhance the water quality of the Great Lakes. The Agreement, first signed in 1972 and renewed in 1978, expresses the commitment of each country to restore and maintain the chemical, physical and biological integrity of the Great Lakes Basin Ecosystem and includes a number of objectives and guidelines to achieve these goals. In 1987, a Protocol was signed amending the 1978 Agreement. The amendments aimed to strengthen the programs, practices and technology described in the 1978 Agreement and to increase accountability for their implementation.

• Annex 2 of the Agreement relates to Remedial Action Plans and Lakewide Management Plans to control and remediate areas where "beneficial uses" have been impaired and specifies the need for source control programs to reduce loadings of Critical Pollutants.
• Annex 7 of the Agreement relates specifically to dredging activities and specifies that the two governments will develop and implement programs and measures to ensure that dredging activities will have a minimum adverse effect on the environment.
• Annex 12 relates to the presence of persistent toxic compounds and stipulates that the governments shall take all reasonable and practical measures to rehabilitate those areas of the Great Lakes adversely affected by these chemicals.
• Annex 14 of the agreement provides for the governments, in cooperation with State and Provincial Governments, to identify the nature and extent of sediment pollution in the Great Lakes System and subsequently develop and evaluate methods to remedy such pollution.

9. Risk management

Risk management is distinct from risk assessment; the latter is primarily scientific, the former includes risk assessment along with other non-scientific considerations such as societal and economic concerns. Good science alone does not yield good management, but is an essential prerequisite for good decision-making. For example, the “range and significance of natural processes…must be adequately assessed prior to the selection, design and optimization of any management options for contaminated sediments” (Apitz et al., 2002).

Application of the framework will assist with identification of actions that may be employed to improve environmental impairments caused by sediment contaminants. These improvements may include: no consumption advisories for public health or wildlife (i.e., guidelines and objectives not exceeded); healthy benthos, fish and wildlife populations (i.e., self-sustaining communities at the expected level of abundance when compared to reference conditions or, in the absence of community structure data, no significant water or sediment toxicity); normal rates of fish tumours, deformities and reproductive problems in fish, birds and mammals (i.e., rates not elevated above reference conditions); and, no restrictions on dredging activities (i.e., guidelines and objectives not exceeded).

This section of the document provides a brief overview of different processes and options for the management of contaminated sediments. This information has been reproduced from material originally provided in An Integrated Approach to the Evaluation and Management of Contaminated Sediments (MOE 1996). No new material has been added. As a result, this information may be dated and other sources that provide newer or more proven techniques may now be available.

9.1 Developing an action plan

9.1.1 Considerations governing sediment remediation

A sediment remediation plan is comprised of a series of carefully laid out steps designed to achieve a desired goal or objective. The most common goal is reducing sediment contamination to an acceptable level. The actions contemplated in the plan must be based on the ecosystem concept to ensure that short term gains do not cloud potential long term problems or that problems are not shifted from the aquatic medium to an upland site. In this regard, the consequences of each proposed action to be taken must be fully evaluated before the plan is adopted.

Since continued inputs of contaminants to an area to be cleaned up will be counterproductive to an effective remedial effort, the most essential feature of any cleanup plan is the control of contaminant sources to the area. All sources of contaminant input must be identified and, where possible, their contribution quantified in order to develop sound source control measures.

Following effective source controls, other sediment remedial actions may be taken to speed up recovery. There is evidence that natural restoration will usually proceed once the sources are controlled. This process, which relies on clean sediment covering over the contaminated material, may require several years. In areas where the supply of incoming sediment is low, other forms of in situ restoration may be needed to speed up the recovery process.

Within the last few years, various sediment clean-up technologies have undergone testing to determine the capabilities of removing and treating contaminated sediment. A summary of findings to date is provided in Section 9.2. These technologies have been tried on relatively small volumes of sediment which makes it difficult at this stage to assess their cost effectiveness on large projects.

Within Ontario, most sediment cleanup operations have traditionally involved some form of dredging and confined or upland disposal, and most of these have been in response to chemical spills. It is now clear that suitable new sites for the placement of large volumes of dredged material are generally rare and existing waste disposal facilities such as sanitary landfills are approaching or already at capacity in most areas.

Where suitable disposal sites are available, such as in the vicinity of major Great Lakes harbours, dredging and confined disposal may still be the preferred option for sediment cleanup, at least until better solutions are found. This is because much knowledge and experience has been gained using this technique and it is not restricted by the volume of material to be removed, as are some of the newer techniques which are now evolving towards a large production scale.

9.1.2 Setting a goal

The International Joint Commission has identified a number of "use impairments" in its "listing/delisting" criteria for Great Lakes Areas of Concern. These include:

• Fish tumours or other deformities.
• Bird or animal deformities or reproductive problems.
• Degradation of benthos.
• Restrictions on dredging activities.
• Eutrophication or undesirable algae.
• Restrictions on drinking water consumption or taste and odour problems.
• Beach closings.
• Degradation of aesthetics.
• Added costs to agriculture or industry.
• Degradation of phytoplankton and zooplankton populations.
• Loss of fish and wildlife habitat.

Sediments alone may not contribute directly to this extensive list of use impairments but, through the slow release of contaminants in some areas, may be a source of chemicals to the water column. To progress from a contaminated sediment problem to the restoration of designated uses in an area will require a strategy that involves a phased approach, likely over several years, to achieve significant improvements. It must be remembered, however, that a problem which has been in the making for decades may not be solved quickly. It is imperative, therefore, that any cleanup goal aimed at use restoration be based on a realistic schedule that incorporates source controls and the practical constraints of removing or covering over contaminated sediment until a desired concentration is achieved.

Another consideration of a practical nature is that current technology can only handle small volumes of material within reasonable costs. This suggests that it might be more practical and economically feasible to deal initially with the zones of high contamination, often referred to as "hot spots", while addressing the remaining portions of the area as financial and other constraining factors become more favourable. The important aspect of sediment management at this stage is to set realistic goals based on the practical nature of the options for achieving the goals, as well as the social, economic and environmental costs and benefits of achieving the goals. Such analysis must also consider the "do nothing option". The rest of this section describes some of the factors that may be considered in setting cleanup goals.

9.1.2.1 Factors to consider when setting cleanup goals

The nature of the area and the problem

• The size of the area affected needs to be clearly defined since this will have a significant bearing on the remedial option chosen from both a cost and technology perspective.
• The uses the area is put to and the potential for this area to affect adjoining areas through the spread of contaminated sediments.

  Uses may include protection of fisheries and benthic organisms. There is a need to consider both the toxic and bioaccumulative potential of contaminants. In previous sections, the need to look at a range of tests was indicated. This becomes critical at this stage since the severity of the effect will play a major role in arriving at the final decision.

  From a human health perspective, compounds that are persistent and pose a threat to water supplies or fish and wildlife will be weighted differently from compounds that do not pose similar threats. In some cases recreational/aesthetic considerations may be the driving force in a cleanup study.

• The potential for recontamination must be examined from the point of view of existing and proposed land use and source controls. Existing and new industries must incorporate features that will not lead to sediment contamination. It will be prudent to view this aspect not only from a local perspective but also from a broader watershed or regional perspective.
• There is a need to consider whether sediment removal will create additional problems, such as the exposure of historical contamination in deeper layers of the sediment. Care must be taken to ensure that the full depth of the problem has been adequately defined.
• The physical environment of the area needs to be considered. The potential for resuspension of contaminated sediment, with resultant contamination of adjacent or downstream areas will be an important factor in developing a remediation plan.

The nature of the solution

The solution to the identified problem in the area under investigation must be based on a clear understanding of the problem by all members of the decision making team. Science provides a large measure of the problem definition, but often cannot be comprehensive enough to provide answers to all the questions that may arise. The shortcomings are recognised, and methods such as risk analysis are relied upon to provide a structured basis for decision making. Members of the decision making team may experience difficulty in weighing the "apparent conflicts" that arise from considering all the results such as sediment chemistry, benthic surveys, toxicity testing, fish tissue residue, etc. This is especially troublesome when one assessment technique suggests a problem and the others do not. For this reason the framework provides a good basis on which to conduct an evaluation. The stepwise process of the framework eliminates the chances of arriving at erroneous conclusions.

In deciding on a rationale for cleanup, the cleanup objectives may not be realized over the short term and should realistically be viewed as longer term objectives, recognizing also that some of the uses identified may never have existed in the area.

Setting an outline for action

With the exception of spills, which must be cleaned up immediately, the most urgent need in environmental management is to protect the ecosystem from further abuse. Thus, source control must be the foundation of remedial action.

Consideration of remedial action in an area of contaminated sediment requires the development of a cleanup goal. This goal should be based on the "desired state of the environment" or developed in support of certain "attainable" uses. These need to be evaluated within the context of the whole watershed (i.e., a holistic approach). Where feasible, chemical guidelines provide a very convenient tool for setting cleanup goals, although these must be used with care since most chemical guidelines have been developed for broad use and may require some adjustment when applied to specific sites and may, in some cases, be too conservative. Defining cleanup goals that are risk based (i.e. consider the pathways of the contaminants into the aquatic biota and its effect on the overall ecosystem health) differs depending upon whether the risk results are from direct or indirect exposure pathways. In setting cleanup goals to protect aquatic ecosystems, exposure pathways of the contaminants in the sediments should also be considered. Exposure pathways can be both direct, in that aquatic organisms are in direct contact with the sediments, or indirect, in that the organisms do not come into direct contact to the sediment, but are still exposed to the contaminants that originated from the sediment. The final goal could also include intermediate goals, since the achievement of the goal can be phased over time or over a sequence of activities.

The steps involved in developing a cleanup plan have been summarized below:

Development of Remediation Plan

• Base need for remedial action on biological effects and contaminant concentrations
  • severity of biological effects
  • ambient water and sediment quality
  • types of contaminants
• Determine effectiveness of source controls for all sources
  • ability to control sources will affect final remediation target
• Need to consider local land use and local “best use”
  • goal should be reasonably achievable
  • compatible with existing land uses
• Consultation with stakeholders/public
  • stakeholder involvement to ensure “best achievable goals” are being considered
  • consideration of existing goals (e.g. RAP/PAC, publicly established)

The ideal cleanup goal will always be the level that provides for the protection of all sediment uses. In most cases the target will be determined by the local background, ambient values, or based on the results of an Ecological Risk Assessment, since these are the practical limits to cleanup. However, cleaning up to this level will not always be feasible, especially when the area under consideration is large or where there are ongoing sources of contamination. Such areas may require a multi-phased approach, with a lengthy time frame, to achieve source control before any remediation work is undertaken.

In some areas, the ideal cleanup opportunities present themselves and these should not be overlooked. For example, Collingwood Harbour remedial efforts (i.e., dredging) were assisted by the presence, on-site, of facilities designed for navigational dredging that were ready to accept the sediment. Such ideal situations may not exist in all areas; however, all options must be explored.

If cleanup cannot be accomplished in a single operation, then a sequence of operations should be planned and for each one a plan should be developed on what is to be achieved within a given time frame. The plan should be based on the following:

• The cleanup plan must be based on realistic goals. If the goal is too low or cannot be achieved within practical economic limits, then the effort will be of little practical value. The cleanup goal must be compatible with the prevailing land and water uses in the area. The existing uses of the area will influence the final remediation target. For example, an area receiving stormwater runoff from an urban area will require a different cleanup target from one influenced mainly by rural activities.
• The plan should be compatible with proposed local land uses. The proposed uses of the adjoining areas and perhaps the local watershed will influence the remedial plan. For example, an area that is used exclusively for recreation will be considered differently from one with mixed uses.
• The plan must consider the quality of sediment entering the area from remote sources such as upstream areas. This is especially important in enclosed areas such as harbours where most of the sediment that enters the area is deposited. It will be counter-productive in such cases to cleanup existing sediments when the problem could recur over a short time.
• The nature of the contaminants will play a role in target setting. The significance of potential health and environmental effects of contaminants in sediments is determined to a large extent by the types of contaminants encountered. Some compounds, such as the persistent organics, will pose a greater environmental threat and will therefore elicit a different response from decision makers compared to certain metals.
• The goal will also be influenced by cleanup technology, suitable disposal sites for sediment if the removal option is selected and equally importantly, appropriate funding.
• A phased approach would require setting interim targets that can be achieved over a prolonged time frame. Such an approach should clearly identify a number of milestones to ensure that progress is being made.

None of the remedial options are free of risks and any contemplated action will have certain benefits as well as certain negative impacts. Properly designed studies will highlight potential problems and provide some indication of the magnitude andsignificance of potential impacts. In effect, such studies will define the current state of the sediment environment.

In many areas, contaminated sediments have been a historical problem which needs to be resolved. The resolution starts with turning off the sources and, with the help of natural processes, improving the situation. In some cases the problem is so severe that additional efforts will be required to speed up the environmental healing process. Those involved in remediation should be aware that restoration to "pristine" conditions is usually an untenable and often unattainable goal, as is the expectation that immediate results can be obtained. As noted earlier, many areas will require an extended period of time, even with active remedial efforts.

On the other hand, a "do nothing" approach just for the sake of ignoring a problem is not acceptable. In the past, decision making was often delayed as additional information was sought to answer questions as they arose. In many cases, there are no immediate answers to such questions and if we try to answer every scientific question that arises, decisions will seldom be made. Therefore, it is imperative we work with the types of information gathered, recognizing that definitive answers are rarely provided given the current state of the science in information gathering. The framework has been designed such that data gaps can be identified as part of the initial decision-making process, thus avoiding timely and costly delays.

Efforts should be directed towards addressing the essential questions: How much cleanup is needed? Where is it needed? How much will it cost? How can it best be done? The framework outlined in this document addresses the first two questions, and the section that follows addresses remedial options.

9.2 Sediment remediation options

9.2.1 Remediation options

In most cases the choice of remedial options will depend on the nature of the contaminants and the severity of contamination. Where immediate cleanup is required as a result of high concentrations and severe biological effects, the range of options may be more limited than in areas where ontamination is less severe.

Nevertheless, a broad range of options is available for dealing with contaminated sediments and these have been summarized in Figure 6. These range from simple removal technologies to elaborate in-situ treatment. Predictably, as the complexity of the treatment increases, so do the associated costs, and the most elaborate methods are usually also the most expensive.

Sediment remediation technologies fall into three broad categories: A) natural remediation; B) removal, sometimes followed by some type of treatment and; C) in-situtreatment. Currently, only the first two options have been used on a large scale and can be considered as proven technologies.

The selection of a remedial option requires careful consideration to ensure that any actions taken do not exacerbate the problem. In some situations, in-situ contamination may pose only a minor threat to organisms when in-place, particularly if the material is isolated from the water column, but may become a major concern when disturbed. Removal operations may resuspend contaminated material, thus potentially increasing its availability to aquatic organisms. Removal may also expose deeper layers of contaminated material. Finally, removal will present other concerns since in most cases this will require some type of secure disposal or additional treatment.

Figure 7: Sediment Remediation Options

Enlarge this image

Figure 6 provides a flowchart of sediment remediation options. At the top is a text box: 'Source(s) Controlled'. There is a downward arrow pointing to another text box: 'Remedial Options'. This is followed by a downward arrow that splits into 3 sections. The first is referred to as 'Natural Remediation' and notes Section 9.2.1.1 for additional information; the second is referred to as 'Removal Options' and notes Section 9.2.1.2 for additional information; and the third is referred to as 'In-Situ Treatment' and notes Section 9.2.1.3 for additional information. There are 4 subgroups under the text box 'Removal Options'. These are: (1) Waste Disposal Site, (2) Beneficial Use, (3) Confined Disposal Facilities, and (4) Treat and Dispose. There are 3 subgroups under the text box 'In-Situ Treatment'. These are (1) Isolation, (2) Chemical, and (3) Biological.

9.2.1.1 Natural remediation

Natural remediation can be considered in those situations where the problem is not so severe that material must be removed immediately. Natural remediation is a preferred option where large areas of relatively low contamination are considered. The economic costs of removing and treating such areas usually make this the most viable option. However, in all cases, this option assumes that effective source control has been achieved.

Natural remediation consists of leaving the sediments in-place, to be buried by newer, cleaner material. "Treatment" relies on the finding that many of the contaminants in sediments undergo changes in the sediment. Metals, for example, will often mineralize over time, creating insoluble compounds. Organic compounds will usually degrade over sufficiently long time periods.

In some cases, leaving the material in place may effectively reduce the availability of contaminants. In particular, metal availability can be reduced through natural processes such as diagenesis and mineralization. Most organic compounds, even persistent organics, will decompose as a result of microbial action, though in some cases this process may be exceedingly slow. If the contaminated material is isolated from the water column by a cleaner surface layer, then it would pose little threat to aquatic organisms.

Therefore, for natural remediation to be an effective option the sedimentation rate must be high enough that the material will be covered to a depth required to isolate the material from the water column in a reasonable period of time.

Though often equated with the "do nothing" option there are significant differences between the two. The "do nothing" option does not consider natural burial, rates of sedimentation or severity of contamination. It is most often used where it is not technically feasible or practical to undertake remediation. Natural remediation is not a "do nothing" option but requires evaluation of existing conditions to ensure that sediment burial is achieved within a predefined period of time. Natural recovery may require ongoing care and oversight to ensure environmental conditions are not worsening and recovery is taking place. The application of administrative conditions or rules may be required to ensure that recovery is not negatively affected by human activities.

It is important to determine the dynamics (transport) of both contaminated sediments and clean sediments in order to determine the acceptability of this option. If clean sediments are being continually deposited over historically contaminated sediments and point source controls have been achieved, this may be the preferred option. If however, contaminated sediments are being slowly or episodically removed and re-deposited elsewhere, other remedial options may have to be considered. The advantages and limitations of natural remediation have been summarized below:

Remediation Options - Natural Remediation

Advantages:

• least likely to resuspend contaminants
• no sediment loss due to handling
• no disposal problems
• natural mineralization of metals
• natural decomposition of organics

Suitable for sediment with:

• chronic biological effects
• low bioavailability of sediment contaminants
• low potential for biomagnification

Not suitable for sediment with demonstrated:

• acute toxic effects
• high sediment contaminant bioavailability
• strongly bioaccumulative compounds

Requirements:

• depositional area
• sufficiently high deposition rate
• low potential for disturbance

9.2.1.2 Removal and disposal or treatment

All remediation activities that involve removal of sediments require some type of dredging operation. Dredging can be accomplished using either mechanical or hydraulic dredges. Mechanical dredges include the familiar clamshell dredge, as well as a variety of other modified buckets and may be deployed from the shore or barge-mounted. All have the advantage of being able to remove sediment at in-situ densities with little additional entrainment of water. However, these dredges typically result in high turbidity from re-entrainment of settled material. For remediation of contaminated sites, this is often highly undesirable and necessitates the use of additional measures to contain the suspended material, such as silt curtains. In many cases, physical conditions within the water body preclude the effective use of these mitigation measures and alternative methods of dredging, such as hydraulic dredges, may be required.

Hydraulic dredges typically operate with a much lower turbidity than mechanical dredges. Hydraulic dredges are usually comprised of some type of cutting head that loosens the sediment and mixes it with water, and a pumping system that pumps the slurry either to a holding tank such as a barge, or through a system of pumps to a shore-based holding area. Hydraulic dredges typically entrain large volumes of water in order to achieve a pumpable slurry. Where clean sediments are being removed, as inthe case of navigational dredging, the hopper or barge is allowed to overflow the excess water. For remediation of contaminated sediments, use of hydraulic dredges will necessitate treatment of entrained water since, due to the presence of contaminants, the water cannot be overflowed.

The removal equipment can vary in size, depending on the needs or access restrictions of the area. Most removal equipment has been designed to operate at practical depths of up to 10 m. In deeper water, removal of contaminated sediment may be limited by the availability of suitable equipment. While clamshell-type dredges are theoretically capable of operating at any depth, their accuracy can be substantially diminished at greater depths.

Considerations/limitations

Loss of sediment during the dredging operation is a major concern with removal of contaminated sediment. Loss of material to the water column has the potential to distribute contaminated fine material over a broad area, which can also heighten the bioavailability of contaminants to aquatic organisms. The major concern is to control such losses, either through the use of special cutting and dredging devices that minimize the amount of material that is resuspended, or through the use of additional equipment such as silt curtains that can limit the spread of resuspended material. Both methods have their limitations. Special cutting heads for use with suction hopper dredges will require additional facilities for treatment of entrained water, since these types of dredges typically require high water content in order to remove the material. Silt curtains are suitable for use only in areas of little or no current and during calm weather.

In flowing water situations removal operations may be carried out in the "wet" or "dry". The type of removal operation will depend on the size and flow of the stream or river. In large rivers sediment removal will be carried out using the same equipment as used in standing water (dredges) though containment devices such as silt curtains are often unsuitable in these situations. In smaller rivers and streams, sediment control measures may require the placement of temporary barriers to control resuspension. In some cases the isolation of the contaminated area through the construction of cofferdams and dewatering of the site may be the most preferable.

The actual removal of contaminated sediment can result in a number of adverse effects in shoreline areas through losses of material. Such problems are heightened each time that the material is handled. Such activities are also disruptive to shoreline and navigational uses of the area as heavy equipment is brought in. Most areas will require a shoreline staging area, as well as temporary materials storage and sediment dewatering facilities. Some of the newer technologies will require extensive areas set aside for considerable periods of time for treatment facilities, and most will require transport to a final disposal site. Each of these steps has the potential to result in adverse effects from loss of material. Proper containment devices will be required as well as protective measures for site workers.

Contaminated sediments present special transportation problems. Materials dewatered and treated on the site should be transported in covered containers to minimize losses as wind-blown dust. However, wet materials moved off the site for treatment or disposal must be transported in sealed trucks or other containers.

Temporary or final storage needs must be determined on a site specific basis since this depends on the material involved (i.e. how toxic), the volume, treatment needs, and any possible end-uses after treatment. Storage facilities should be designed to address these specific concerns.

A number of new designs for removal equipment that minimize sediment loss have also been tested, including such specialized devices as the pneuma-pump. The following list of treatment options considers the technologies only in terms of broad categories. Within each category a number of different technologies exist, many of which are proprietary. Sources for detailed information on specific processes are available in a number of publications, including:

• Review of Removal, Containment and Treatment Technologies for Remediation of Contaminated Sediment in the Great Lakes. (Avrett et al. 1990).
• Sediment Treatment Technologies Database. 2^nd Edition. (Wastewater Technology Centre 1993)
• Screening Guide for Contaminated Sediment Treatment Technologies. Environment Canada, St. Lawrence Centre (EC 1993)

Once the contaminated sediment has been removed, a number of disposal options can be considered. Depending on availability and local acceptability, the material could be disposed of in confined disposal facilities (CDFs), in landfills, or hazardous waste landfills. In many cases, however, to keep disposal costs down, pretreatment of the material (i.e. prior to disposal) will be required. The advantages and limitations of this option are summarized in the inset below:

Remediation Options: In-situ Treatment

Advantages:

• eliminates need to remove and treat/ adequately dispose of toxic sediment
• reduces sediment losses through removal and handling

Suitable for sediments with:

• contaminants for which treatment technologies exist
• suitable physical conditions (e.g., for capping)
• ongoing existing sources
• where removal is impractical

Not suitable for sediments of:

• unstable bottom conditions or untreatable chemical compounds
• where rapid removal/isolation required

Requirements:

• contaminants must be amenable to chemical treatment
• must effectively complex/isolate contaminants within a suitable time frame

Dredging, Dewatering, Solidification and Disposal

This option involves the removal of the sediment, subsequent dewatering and solidification and disposal in an acceptable site.

• primarily for dredging of sediment defined as hazardous material.
• removal usually requires hydraulic dredging or, if conventional dredging is used, additional containment devices such as silt curtains will be necessary.
• hoppers cannot be overflowed and entrained water must be treated prior to return.
• mechanical dewatering consists of: filters, centrifugation, or thickening.
• evaporation dewatering: requires energy input for evaporation and will require treatment of off-gases.
• choice of dewatering depends on amount of sediment, available temporary storage for material awaiting processing, and desired consistency of the material (depends on disposal alternative).

Removal and Treatment

Most of the post-removal treatment technologies currently developed or being tested fall into one of three major groups: 1) Extraction processes, which involve dissolution of the contaminant in a recoverable fluid; 2) Immobilization processes which chemically fix or alter the contaminants and; 3) Thermal processes which use heat to break down the chemical bonds of the contaminants or to vitrify contaminants and sediments into a solid mass. The advantages and limitations of this method are summarized below:

Remediation Options: Removal and Treatment

Advantages:

• removes toxic sediments
• removes/destroys toxic compounds
• eliminates need for expensive containment (still requires on-land disposal)

Suitable for sediments with:

• acutely toxic effects
• high sediment bioavailability
• highly biomagnifying compounds
• high sediment resuspension
• compounds for which removal/destruction technologies exist

Not suitable for sediments of:

• suitable for most areas though too expensive to consider for areas of low sediment toxicity or bioavailability

Requirements:

• means of minimizing turbidity and loss during removal
• large areas set aside for extended time for equipment and stockpiling of sediment

Few of the methods proposed or tested attain total destruction or removal. The most efficient technologies currently range from 80% efficiency for metals, to in some cases 99% efficiency for organics, though typically these are much less. However, in most cases, the residue will still contain contaminants and only in those cases where concentrations are at or below MOE fill quality guidelines for Lakefilling (MOE, 2003) can the material be safely returned to the aquatic environment. In most cases, the material will have to be disposed of upland in accordance with MOE requirements, such as the Environmental Protection Act, O.Reg. 461/05.

Dredging and Washing/Extraction

Following dredging, the materials are subjected to washing with various solvents that will preferentially bind target contaminants. The solvents are subsequently separated from the sediment. In theory, the cleaned material can be returned to the site, though in most cases it will have to be disposed of at an appropriate upland site. However, since the material will have lower contaminant concentrations at the end of treatment, a larger number of disposal options will be available.

• contaminated sediment is washed in a suitable solvent to remove the contaminants. The solvent is later recovered.
• solvents can be selected to remove either organics or inorganics (because of the different solvents required for each, it does not appear to be feasible to do both at the same time and removal of both will require multiple steps).
• requires a storage area and a treatment facility (i.e., tank of some kind).
• most processes require multiple extraction cycles.
• requires further separation of contaminants from solvent and final disposal of contaminant concentrate.

Dredging and Incineration/Thermal Destruction

• The material is dredged, usually dewatered to some degree and incinerated in high temperature incinerators.
• are among the more effective options for destroying organic contaminants. (up to 99% efficiency of removal)
• incinerators include: fluidized bed, circulating bed combustor, high-temperature slagging, infrared, multiple hearth, plasma arc, Pyretron, and rotary kiln.
• not effective for metals - volatile metals like mercury and lead may require additional steps to ensure removal from flue gases. Incineration can also change oxidation states of some metals, making metals in the final product more mobile.

Dredging and Vitrification

The material is dredged, dried to some degree and treated. The treatment uses high- voltage graphite electrodes to melt material. The molten material then cools to a solid glass-like material.

• does not measurably leach organic or inorganic contaminants.
• energy costs are high (depending on water content) as are operating costs (consumable electrodes).
• may require flue gas collection and treatment since process volatilizes semi- volatile and volatile organics.
• bench-scale tests confirmed better than 99% efficiency in PCB destruction.

Dredging and Low-temperature Thermal Stripping

Sediments are heated to relatively low temperature (ca. 350°C) to remove volatiles and semi-volatiles. The volatiles are condensed and the liquid cleaned and filtered through activated carbon.

• the dry, dust-like sediment will contain materials not driven off by low temperature.

Dredging and Reductive Dechlorination

Sediments are heated in the presence of a reducing agent such as hydrogen to dechlorinate organic contaminants.

• suitable for only a certain number of organic compounds (currently tested only for PAH and PCBs).
• better than 99% efficiency for those compounds tested (PCB and PAH).
• has currently been tested only in pilot and bench scale tests.

Dredging and Biological Treatment

Uses biological methods such as slurry-phase biodegradation. Most available methods rely on bacteria to decompose organic contaminants, either under aerobic or anaerobic conditions. These methodologies may require inoculation/addition of bacteria.

Dredging and Chemical Fixation (Immobilization, Solidification/Stabilization)

These involve a number of methods to limit contaminant mobility through introduction of a chemical fixative. While most require removal of the sediment, some procedures have been proposed for in-situ fixation.

• most effective for treating heavy metal contamination.
• involves injecting a solidifying agent (e.g., cement or lime) together with an additive to prevent organics from interfering with the solidification process.

Dredging and Chemical Treatment

Involves treatment with any of a number of chemicals to neutralize, fix, or alter contaminants in sediment.

• chelation uses chelating molecules to bind and restrain metal ions from forming ionic salts.
• efficiency is variable, depending on chelating agent and dosage.
• other processes include oxidation of inorganics, nucleophilic substitution.

Dredging and Multi-phase treatment

This category of treatment comprises a combination of the above treatments.

9.2.1.3 In-situ treatment

A limited number of options are available for in-situ treatment of contaminated sediment (the advantages and limitations of this option are summarized below). In-situ fixation methods work mainly through aiding natural remediation processes such as decomposition of organics in order to reduce, though not necessarily eliminate, sediment contamination.

Capping

The procedure involves covering existing contaminated sediment with clean material.

• unless capping material is less dense than material being capped, the materials may sink through.
• potential for erosion of cap materials
• reduces navigable depth and precludes future dredging.

In-Situ Fixation/Stabilization

Involves the injection of chemicals/additives that will either bind with contaminants to effectively remove them from circulation, or that enhances their decomposition.

• this is at present only in the developmental stages and has not been demonstrated in full scale.

Capping-Lakefilling (Overfilling)

This is similar to capping except that the area is isolated and the cap extends to the surface to create a lakefill.

9.2.2 Selection of remediation option

Once the available options have been identified the next task is to determine which are most suitable for the site in question. Initially, it needs to be determined whether active remediation is a realistic or feasible goal. Some areas, for example, may be prohibitively expensive and may best be left to natural remediation.

The evaluation of remedial options should include:

• level of contamination and severity of biological effects (some options are not suitable for heavily contaminated/acutely toxic sites)
• volume and type of material to be remediated.
• physical factors such as navigational use.
• suitability of treatment(s) to the type(s) of contaminant(s) (where different classes of contaminants are involved, e.g., organics and metals, treatment may involve different processes for each that may have to be done in series).
• effectiveness of remediation and /or treatment (i.e., will the method remove only some or all of the contaminant of concern; will additional treatment or some type of confined disposal be required; will some steps have to be repeated).
• costs for remediation, including removal, treatment and storage.
• mitigation procedures required.
• potential for reuse of material.
• potential disruptions to current uses of the area (e.g., will navigational routes be affected, disruption/destruction of fish habitat).
• length of time required for the project.
• public acceptance of the option.

A table should be prepared that lists the various options and the evaluation criteria. The most suitable option would then be identified through determination of which option not only meets the remediation target, but also most closely satisfies the priorities developed for the particular area.

9.2.3 Evaluating cleanup options

In evaluating the different options for sediment cleanup, consideration must be given to the "non invasive" option of natural remediation which, as mentioned earlier, relies on clean sediments depositing over the contaminated area through natural processes. The natural remediation option may be the preferred option in those cases where other forms of remedial action may result in a worsening of the situation by making contaminants more readily available through resuspension and dispersion. The natural remediation option would best be considered in depositional areas such as harbours where incoming clean sediments will form a cap over the contaminated material. This will apply to those areas where the sources have been controlled.

A convenient way of summarizing information to be used in deciding on a remedial option for contaminated sediment could be through construction of a matrix as shown in the following hypothetical case.

Evaluation Parameter	Identified Remedial Options
	A	B	C	D	E
Cost Effectiveness	High	Medium	Low	Medium	High
Uses Ecosystem Principles	Medium	Low	Medium	Low	Low
Social Acceptability	Medium	High	Medium	Low	Low
Technical Flexibility *	Low	Medium	High	High	High

Prioritizing Options:

These have to be developed on a site specific basis, since local priorities will differ. However, cost and technical feasibility are typically major determining factors, and further evaluation of an option is usually not warranted if the option is technically unsuitable or the cost is prohibitive.

Cost Effectiveness:

Cost effectiveness refers to the financial costs of achieving the desired or stated objectives on sediment cleanup for each of the options being considered.

Costs must include all facets associated with the option, including: equipment, mobilization, removal, treatment, residuals disposal, etc. This has to be done for each phase of a multi-phased operation and must also include any post cleanup costs associated with management of material removed.

Ecosystem Principles:

The basic element in such principles is that extreme caution is used to ensure that a sediment cleanup operation does not result in the transfer of contaminants to another area where they pose a threat. In most situations, when sediment is removed from water it is placed in a confined disposal facility along the shoreline or is disposed of at an upland site.

Social Acceptability:

This includes public response to the measures being proposed as reflected through public advocates on the decision making team. Concerns may be related to the cost of the project, the effort and anticipated accomplishments. For example, Is it a partial or full cleanup effort? Will it take an inordinately long time to effect? Will the proposed solution create problems in other areas (e.g. will material have to be disposed of on land with potential to affect existing land use or environmental quality?).

Technical Feasibility/Implementability:

The method selected must be capable of dealing with the problem without generating any problems of its own, e.g. if dredging is required, then the type of dredge selected should minimize the loss of material through resuspension and dispersion. The size and type of equipment used must fit the problem and the area.

9.3 Remediation plan

The final step, once the remedial options have been identified, is the development of a remediation plan. This will identify the impaired uses, the remediation targets, and the means of achieving these targets. Included in the latter should be any mitigative measures needed to ensure that any adverse effects of the remediation are minimized. This step will also need to identify the means of disposal of the material, and the final best use for the area.

The final remediation plan is based on the results of both the sediment and biological studies and is developed in conjunction with socio-economic considerations. The steps to development of a remediation plan are listed below:

1. Identify both biological/chemical impacts and socio-economic impacts (such as impaired uses, etc.)
2. Determine area to be cleaned up. This is based on both scientific and socio-economic criteria.
3. Determine options for remediation. This should list all suitable options.
4. Identify the benefits and costs of each option on both an environmental and an economic level.
5. Determine the most appropriate cleanup strategy, which may not always be the most desirable from a purely scientific perspective.
6. Develop a detailed plan for remediation, identifying all the major steps and a timetable for implementation. These include the details of removal or in-situ treatment such as schedules, areas, volumes to be treated or removed, temporary and permanent disposal sites, etc.

It is at this level that the truly hard choices must be made. At the earlier steps in this procedure, the scientific criteria have been determined, and the best environmental solutions have been developed. It is unfortunately true however, that the best scientific solutions are not always the most practical. The costs of each option must be weighed against the benefits, and the choice made may not be the best from an environmental perspective. Although it is beyond the scope of this document to describe the socio-economic process associated with sediment cleanup, it is nevertheless a major component of the decision making process and the proper expertise must be obtained to conduct such an assessment.

A number of remediation options are suitable only for certain types of contaminants, or are practical only for low volumes of material. If removal and off-site confinement are considered, then it is necessary to evaluate the safety and integrity of the confinement site. Not all material is suitable for such storage. Dredged material, for example, should be evaluated according to Fill Quality Guidelines for Lakefilling in Ontario (MOE, 2003) to determine suitability for disposal in sites other than registered landfills or hazardous waste sites. This will reduce disposal costs as well as conserve scarce disposal areas.

9.4 Sediment cleanup

9.4.1 Implementation of remediation plan

Once the remediation plan has been developed and approved by all concerned, the plan needs to be implemented. During actual implementation of the plan, all efforts need to be directed towards ensuring that the approved plan is followed, with as little deviation as possible. Some deviations will always be necessary, as unforeseen situations arise. A mechanism for resolving such problems should also be in place, to ensure that the task can be completed quickly. In many cases, the danger of contaminant release or escape (with often broad dispersal) is heightened by prolonging the construction/remediation period.

In all cases, once remediation is underway, a site manager should be present at the site to ensure the remediation plan is being followed, and to deal with unforeseen situations as these arise. The site manager should have overall responsibility for the cleanup actions.

In many cases the specific precautions taken to minimize adverse effects will depend on site-specific considerations. This will be dictated by considerations such as the actual method of removal, the methods of treatment and the means of disposal.

Examples include:

• special handling procedures
• special dredging techniques
• treatment of overflow water from hopper
• silt curtains or other sediment containment devices

Of the intrusive remediation options, in-situ remediation is usually the least disruptive. Depending on the methods used, some disturbance of the surface layers can be expected, though the effects will usually be localized to the immediate area.

During cleanup, a site supervisor should be present at all times to monitor activities at the site. The supervisor needs to be fully aware of the potential problems and fully appraised of the details of site cleanup.

9.5 Post-remediation

9.5.1 Monitoring effectiveness of remediation

An essential element of any cleanup operation is a measure of its effectiveness. Assessment of the effectiveness of the operation should include all of the parameters/uses that were identified as impaired, as a measure of achieving the remediation target. The study can also include additional tests, which may indicate whether the cleanup has resulted in additional effects that may not have been anticipated.

Where chemical criteria were used as targets, biological monitoring should be employed as well. For example, monitoring may reveal that there are no biological impacts despite sediment concentrations in excess of the LEL.

The assessment should also determine whether the "local best use" identified earlier is now achievable. This may not be readily apparent, since any area that has undergone remedial action will require a period of time to stabilize.

Finally a decision must be made on the long term monitoring of the area: how frequently, and for how long such monitoring should be continued, and when can it be stopped, are questions that need to be addressed. In many cases, such long term monitoring should be instituted sometime after the initial post-cleanup assessment in order to measure effects after the area has stabilized. A time period of three to five years between sampling is recommended.

10. Concluding remarks

The purpose of this document is to provide guidance for identifying, assessing and managing contaminated sediments in Ontario. The document provides step-by-step science-based guidance for assessing risks posed by contaminated sediment. The document is intended to be sufficiently prescriptive to standardize the decision-making process, but without using a “cook book” assessment approach that would fail to acknowledge the influence of site-specific conditions on the outcome, nor allow for appropriate use of best professional judgement. Assessing and managing contaminated sediment is complex and is best approached using a multi-disciplined team of qualified persons.

For further support and guidance on the components of this document and on the Provincial Sediment Quality Guidelines outlined herein, please contact the Ministry of Environment’s Standards Development Branch. For queries pertaining to the monitoring and assessment of sediments, contact the Ministry’s Environmental Monitoring and Reporting Branch, and for site specific sediment issues contact your closest regional Ministry of Environment office.

References

Ankley G.T., and M.K. Schubauer-Berigan, 1995. Background and overview of current sediment toxicity identification evaluation procedures. J Aquat Ecosystem Health 4: 133-149.

Apitz S.E., J.W. Davis, K. Finkelstein, D.W. Hohreiter, R. Hoke, R.H. Jensen, J. Jersak, V.J. Kirtay, E.E. Mack, V.S. Magar, D. Moore, D. Reible, and R.G. Stahl Jr., 2002. Critical issues for contaminated sediment management. US Navy, Space and Naval Warfare Systems Center, San Diego, CA, USA. MESO-02-TM-01.

Apitz S.E., J.W. Davis, K. Finkelstein, D.W. Hohreiter, R. Hoke, R.H. Jensen, J. Jersak, V.J. Kirtay, E.E. Mack, V.S. Magar, D. Moore, D. Reible, and R.G. Stahl Jr., 2005. Assessing and managing contaminated sediments: Part I, developing an effective investigation and risk evaluation strategy. Integrated Environmental Assessment Management 1: 2-8.

ASTM, 2000. Standard Test Methods for Measuring the Toxicity of Sediment-associated Contaminants with Fresh Water Invertebrates. E1706-00. In Annual Book of ASTM Standards, Vol. 11.05. Philadelphia, PA. pp. 1109-1225. American Society for Testing and Materials

Averett, D.E., B.D. Perry, E.J. Torrey and J.A. Miller, 1990. Review of Removal, Containment and Treatment Technologies for Remediation of Contaminated Sediment in the Great Lakes. USAE Waterway Experiment Station, Vicksburg, Misc. Paper EL-90-25.

Bailey, R.C., R.H. Norris, and T.B. Reynoldson, 2004. Bioassessment of freshwater ecosystems using the Reference Condition Approach. Kluwer Academic Publishers, Boston, Massachusetts.

Barbour, M.T., J. Gerristen, B.D. Snyder, and J.B. Stribling, 1999. Rapid Bioassessment protocols for use in wadeable streams and rivers: periphyton, benthic macroinvertebrates and fish. 2^nd edition. EPA 841-B-99-001. Office of Water, USEPA, Washington, DC.

Bedard, D., D.Persaud and A. Hayton, 1992. Ontario Ministry of the Environment Laboratory Sediment Biological Testing Protocol. Ont. Ministry of Environment Aug. 1992. 26 pp.

Borgmann U., W.P. Norwood, T.B. Reynoldson, and F. Rosa, 2001. Identifying cause in sediment assessments: bioavailability and the Sediment Quality Triad. Can J Fish Aquat Sci 58: 950-960.

Burgess R.M., M.G. Cantwell, M.C. Pelletier, K.T. Ho, J.R. Serbst, H.F. Cook, and A. Kuhn, 2000. Development of a toxicity identification evaluation procedure for characterizing metal toxicity in marine sediments. Environmental Toxicology and Chemistry 19: 982- 991.

Burgess R.M., M.C. Pelletier, K.T. Ho, J.R. Serbst, S.A. Ryba, A. Kuhn, M.M. Perron, P. Raczelowski, and M.G. Cantwell, 2003. Removal of ammonia toxicity in marine sediment TIEs: a comparison of Ulva lactuca, zeolite, and aeration methods. Marine Pollution Bulletin 46: 607-618.

Burgess R.M., 2000. Characterizing and identifying toxicants in marine waters: A review of marine toxicity identification evaluations (TIEs). International Journal of Environment and Pollution 13: 2-33.

Burton G.A. Jr., P.M. Chapman, and E.P. Smith, 2002. Weight-of-evidence approaches for assessing ecosystem impairment. Human Ecological Risk Assessment 8: 1657-1673.

CCME, 1996. A framework for ecological risk assessment: General guidance. Canadian Council of Ministers of the Environment. Winnipeg, MN, Canada. EN-108-4-10-1996E.

Chapman P.M., B.G. McDonald, and G.S. Lawrence, 2002. Weight of evidence frameworks for sediment quality and other assessments. Human Ecological Risk Assessment 8: 1489-1515.

Chapman P.M., F. Wang, C. Janssen, R.R. Goulet, and C.N. Kamunde, 2003. Conducting ecological risk assessments of inorganic metals and metalloids – Current status. Human Ecological Risk Assessment 9: 641-697.

Chapman P.M., 1996. Presentation and interpretation of Sediment Quality Triad data. Ecotoxicology 5: 327-339.

COA, 2007. Canada-Ontario Decision-Making Framework for Assessment of Great Lakes Contaminated sediment. Prepared by Environment Canada and the Ontario Ministry of the Environment. Draft Report. 43pp.

Death, R.G., 1995. Spatial patterns in benthic invertebrate community structure: products of habitat stability or are they habitat specific? Freshwater Biology 33 (3), 455–467.

Di Toro, D.M., C.S. Zarba, D.J. Hansen, W.J. Berry, R.C. Swartz, C.E. Cowan, S.E. Pavlou, H.E. Allen, N.A. Thomas, and P.R. Paquin, 1991. Pre-draft technical basis for establishing sediment quality criteria for nonionic organic chemicals using equilibrium partitioning. Office of Science and Technology. USEPA. Washington, DC.

Environment Canada. 1993. Screening Guide for Contaminated Sediment Treatment Technologies. Environment Canada, St. Lawrence Centre.

Environment Canada, 1997a. Biological test method: Test for survival and growth in sediment using larvae of freshwater midges (Chironomus tentans or Chironomus riparius). Report EPS 1/RM/32.

Environment Canada, 1997b. Biological Test Method: Test for Survival and Growth in Sediment Using the Freshwater Amphiphod Hyalella azteca. EPS 1/RM/33 – December 1997.

Environment Canada, 1998. Biological test method: Reference method for determining acute lethality of sediment to marine or estuarine amphipods. EPS 1/RM/35.

Environment Canada, 1999. Guidance document on the application and interpretation of single-species tests in environmental toxicology. EPS 1/RM/34.

Environment Canada, 2002. Metal mining guidance document for aquatic environmental effects monitoring. Ottawa, ON.

EPA/USACOE, 1998. Evaluation of dredged material proposed for discharge in waters of the U.S. - Testing manual. U.S. Environmental Protection Agency and U.S. Army Corps of Engineers. Washington, DC, USA. EPA-823-B-98-004.

Flood, K., A. Laine, D. Poirier and M. Mueller, (in press) An In Situ Toxicity Study of the Acute Effects of Mine-Tailings Effluents on Aquatic Biota, Manitouwadge, Sept. 15^th - Oct. 1^st, 1991. Ontario Ministry of the Environment and Energy.

Freshman J.S., and C.A. Menzie, 1996. Two wildlife exposure models to assess impacts at the individual and population levels and the efficacy of remedial actions. Human Ecological Risk Assessment 3: 481-498.

Galloway T.S., R.J. Brown, M.A. Browne, A. Dissanayake, D. Lowe, M.B. Jones, and M.H. Depledge, 2004. A multibiomarker approach to environmental assessment. Environmental Science and Technology 38: 1723-1731.

GLWQA, 1987. Great Lakes Water Quality Agreement, International Joint Commission

Gooday, A. J., C. M. Turley, and J. A. Allen, 1990. Responses by Benthic Organisms to Inputs of Organic Material to the Ocean Floor: A Review [and Discussion]. Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences, Vol. 331(1616): 119-138

Grapentine L., J. Anderson, D. Boyd, G.A. Jr. Burton, C. DeBarros, G. Johnson, C. Marvin, D. Milani, S. Painter, T. Pascoe, T.B. Reynoldson, L. Richman, K. Solomon, and P.M. Chapman, 2002a. A decision making framework for sediment assessment developed for the Great Lakes. Human Ecological Risk Assessment 8: 1641-1655.

Grapentine L., C.H. Marvin, and S. Painter, 2002b. Development and application of a sediment quality index for the Great Lakes and associated areas of concern. Human Ecological Risk Assessment 8: 1549-1567.

Grapentine L., D. Milani, and S. Mackay, 2003a. A study of the bioavailability of mercury and the potential for biomagnification from sediment in the St. Lawrence River (Cornwall) Area of Concern. NWRI, Environment Canada, Burlington, ON, Canada.

Grapentine L., D. Milani, and S. Mackay, 2003b. A study of the bioavailability of mercury and the potential for biomagnification from sediment in Jellicoe Cove, Peninsula Harbour. NWRI, Environment Canada, Burlington, ON, Canada.

Hawkins, C.P., R.H. Norris, J. Gerristen, R.M. Huges, S.K. Jackson, R.K. Johnson, and R.J. Stevenson, 2000. Evaluation of the use of landscape classifications for the prediction of freshwater biota: synthesis and recommendations. Journal of the North American Benthological Society 19(3): 541-556.

Hayton, A., D. Hollinger and J. Martherus, 1991. Identification of Sources of Chlorinated Dioxins and Furans in Frog Creek Using Introduced Mussels, Elliptio complanata. Ontario Ministry of the Environment and Energy, 1991.

Ho K.T., R.M. Burgess, M.C. Pelletier, J.R. Serbst, H. Cook, M.G. Cantwell, S.A. Ryba, M.M. Perron, J. Lebo, J. Huckins, and J. Petty, 2004. Use of powdered coconut charcoal as a toxicity identification and preparation manipulation for organic toxicants in marine sediments. Environmental Toxicology and Chemistry 23: 2124-2131.

IJC, 1985. 1985 Report on Great Lakes Water Quality. Great Lakes Water Quality Board. 121p. International Joint Committee.

Ingersoll C.G. and D.D. MacDonald, 2002. Guidance manual to support the assessment of contaminated sediments in freshwater ecosystems. Volume III: Interpretation of the results of sediment quality investigations. EPA-905-B02-001-C, USEPA Great Lakes National Program Office, Chicago, IL, USA.

Jaagumagi R., and D. Persaud, 1993. Sediment Assessment: A Guide to Study Design, Sampling and Laboratory Analysis. Ontario Ministry of the Environment and Energy. July 1993. 39 pp.

Jarvinen A.W., and G.T. Ankley, 1999. Linkage of effects to tissue residues: Development of a comprehensive database for aquatic organisms exposed to inorganic and organic chemicals. SETAC Press, Pensacola, FL, USA.

Klerks, P.L. and J.S. Levinton, 1989. Rapid Evolution of Metal Resistance in a Benthic Oligochaete Inhabiting a Metal-polluted Site. Biological Bulletin 176: 135-141.

Krantzberg G., T.B. Reynoldson, R. Jaagumagi, S. Painter, D. Boyd, D. Bedard, and T. Pawson, 2000. SEDS: Setting environmental decisions for sediment management. Aquatic Ecosystem Health Management 3: 387-396.

MacDonald, D.D., 1994. A review of environmental quality criteria and guidelines for priority substances in the Fraser River Basin. Fraser River Action Plan. Environment Canada. DOE FRAP 1994-30

MacDonald D.D., and C.G. Ingersoll, 2002a. A guidance manual to support the assessment of contaminated sediments in freshwater ecosystems. Volume I: An ecosystem-based framework for assessing and managing contaminated sediments. EPA-905-B02-001A, USEPA Great Lakes National Program, Office, Chicago, IL, USA.

MacDonald D.D., and C.G. Ingersoll, 2002b. Guidance manual to support the assessment of contaminated sediments in freshwater ecosystems. Volume II: Design and implementation of sediment quality investigations. EPA-905-B02-001-B, USEPA Great Lakes National Program Office, Chicago, IL, USA.

Marvin C., L. Grapentine, and S. Painter, 2004. Application of a sediment quality index to the Lower Laurentian Great Lakes. Environmental Monitoring Assessment 91: 1-16.

McCarthy L.H., R.L. Thomas, and C.I. Mayfield, 2004. Assessing the toxicity of chemically fractionated Hamilton Harbour (Lake Ontario) sediment using selected aquatic organisms. Lakes Reservoirs Research and Management 9: 89-103.

Mearns A.J., R.C. Swartz, J.M. Cummins, P.A. Dinnel, P. Plesha, and P.M. Chapman, 1986. Inter-laboratory comparison of a sediment toxicity test using the marine amphipod, Rhepoxynius abronius. Marine Environmental Research 19: 13-37.

MOE, 1983. Handbook of Analytical Methods for Environmental Samples. Volume I and II. Ministry of the Environment, Ontario.

MOE, 1987. Development of Sediment Quality Objectives. Phase I - Options. Ministry of the Environment, Toronto, Ontario. Prepared by Beak Consultants Ltd.

MOE, 1988. Development of Sediment Quality Guidelines. Phase II - Guideline Development. Ministry of the Environment, Ontario. Prepared by Beak Consultants Ltd.

MOE, 1993. Guidelines for the protection and management of aquatic sediments in Ontario. Ministry of the Environment, Toronto, Ontario.

MOE, 1996. An integrated approach to the evaluation and management of contaminated sediments. Ministry of the Environment, Toronto, Ontario.

MOE, 2003. Fill Quality Guidelines for Lakefilling in Ontario. Ministry of the Environment, Toronto, Ontario.

MOE, 2004a. Method E3012, The Determination of Total Carbonate-Carbon in Soil and Sediments by Coulometry. Etobicoke, Ontario. 20 pp.

MOE, 2004b. Method E3412, The Determination of Polychlorinated Biphenyl Congeners (PCBs) in Soil, Sediment and Vegetation by Gas/LiquidChromatography-Electron Capture Detection (GLC-ECD).

MOE, 2004c. Method E3245, The Determination of Arsenic, Selenium and Antimony in Vegetation, Compost, Soil and Sediments by Hydride-Flameless Atomic Absorption Spectrophotometry (HYD-FAAS).

MOE, 2005a. Method E3328, The Determination of Particle Size Distribution on Sediments, Particulate Matter and Liquids by the Coulter Model LS130PS Analyzer. Etobicoke, Ontario. 23 pp.

MOE, 2005b. Method E3116, The Determination of Total Kjeldahl Nitrogen and Total Phosphorus in Soil, Sediments and Sludge by Colourimetry.

MOE, 2005c. Method E3062, The Determination of Heavy Metals in Sediments by the Spectro Inductively Coupled Plasma-Optical Emission Spectrometer (ICP-OES).

Neff, J.M., D.J. Bean, B.W. Cornaby, R.M. Vaga, T.C. Gulbransen and J.A. Scanlon. 1986. Sediment Quality Criteria Methodology Validation: Calculation of Screening Level Concentrations from Field Data. Battelle Washington Environmental Program Office for U.S. EPA. 60 p.

Newell, A.J., D.W. Johnson and L.K. Allen. 1987. Niagara River Biota Contamination Project: Fish Flesh Criteria for Piscivorous Wildlife. New York State Dept. Environ. Conserv., Div. Fish and Wildlife. July 1987. 182 pp.

O’Connor T.P., 2004. The sediment quality guideline, ERL, is not a chemical concentration at the threshold of sediment toxicity. Marine Pollution Bulletin 49: 383-385.

Pavlou, S.P., 1987. The use of the equilibrium partitioning approach in determining safe levels of contaminants in marine sediments. In: K.L. Dickson, A.W. Maki, and W.A. Brungs (Eds). Fate and effects of sediment-bound chemicals in aquatic systems.Proceedings of the sixth Pellston Workshop. Pergamon Press. Toronto, Ontario.

Pavlou, S.P. and D.P. Weston, 1984. Initial Evaluation of Alternatives for Development of Sediment Related Criteria for Toxic Contaminants in Marine Waters (Puget Sound). Phase II: Development and Testing of the Sediment-Water Equilibrium Partitioning Approach. Report prepared by JRB Associates for U.S. EPA. 89 p.

Pelletier M.C., K.T. Ho, M. Cantwell, A. Kuhn-Hines, S. Jayaraman, and R.M. Burgess, 2001. Use of Ulva lactuca to identify ammonia in marine and estuarine sediments. Environmental Toxicology and Chemistry 20: 2852-2859.

Persaud, D., R. Jaagumagi and A. Hayton. 1993. Guidelines for the Protection and Management of Aquatic Sediment Quality in Ontario. Ontario Ministry of the Environment and Energy. 1993. 30pp.

Porebski, L.M., K.G. Doe, B.A. Zajdlik, D. Lee, P. Pocklington, and J.M. Osborne, 1999. Evaluating the techniques for a tiered testing approach to dredged sediment assessment – a study over a metal concentration gradient. Environmental Toxicology and Chemistry 18: 2600-2610.

Power, E.A. and R.S. Boumphrey, 2004. International trends in bioassay use for effluent management. Ecotoxicology 13: 377-398.

Rempel, L.L., J.S. Richardson, and M.C. Healey, 2000. Macroinvertebrate community structure along gradients of hydraulic and sedimentary conditions in a large gravel- bed river. Freshwater Biology 45 (1), 57–73.

Reynoldson, T.B., R.C. Bailey, K.E. Day, and R.H. Norris, 1995. Biological guidelines for freshwater sediment based on benthic assessment of sediment (the BEAST) using a multivariate approach for predicting biological state. Australian Journal of Ecology 20: 198- 219.

Reynoldson TB, and K.E. Day, 1998. Biological guidelines for the assessment of sediment quality in the Laurentian Great Lakes. NWRI Report No. 98-232, Burlington, ON, Canada.

Reynoldson T.B., S.P. Thompson, and D. Milani, 2002a. Integrating multiple toxicological endpoints in a decision-making framework for contaminated sediments. Human Ecological Risk Assessment 8: 1569-1584.

Reynoldson T.B., E.P. Smith, and A.J. Bailer, 2002b. A comparison of three weight-of-evidence approaches for integrating sediment contamination data within and across lines of evidence. Human Ecological Risk Assessment 8: 1613-1624.

Simpson S.L., G.E. Batley, J.L. Stauber, C.K. King, J.C. Chapman, R.V. Hyne, S.A. Gale, A.C. Roach, W.A. Maher, and A.A. Chariton. 2005. Handbook for sediment quality assessment. Environmental Trust, Canberra, Australia.

Skei, J.M. 1992. A review of Assessment and Remediation Strategies for Hot Spot Sediments. Hydrobiologia 235/236: 629-638.

Suns, K. and G. Hitchin, 1994. Organic Contaminants in Forage Fish from Toronto Area Streams. Ontario Ministry of the Environment and Energy, March 1994. 31 pp.

Suter II, G.W. 1996. Risk characterization for ecological risk assessment of contaminated sites. Office of Environmental Management, US Department of Energy, Oak Ridge, TN, USA. ES/ER/TM-20.

Suter II, G.W., S.B. Norton, and S.M. Cormier, 2002. A methodology for inferring the causes of observed impairments in aquatic ecosystems. Environmental Toxicology and Chemistry 21: 1101-1111.

Tetra Tech Inc., 1986. Development of Sediment Quality Values for Puget Sound. Vol. 1. Puget Sound Dredged Disposal Analysis Report. 129 p.

USACE/USEPA, 1998. Evaluation of dredged material proposed for discharge in waters of the U.S. testing manual. EPA-823-B98-004. USEPA, Washington, DC, USA

USEPA, 1988. Description and use of health risk assessments. Integrated risk information system background document 1. Washington, DC. 19pp.

USEPA, 1998. EPA’s contaminated sediment management strategy. Office of Water, U.S. Environmental Protection Agency, Washington, DC, USA. EPA-823-R-98-001.

USEPA, 2002. A guidance manual to support the assessment of contaminated sediments in freshwater ecosystems: Volume III - Interpretation of the results of sediment quality investigations. EPA-905-B02-001-C. Great Lakes National Program Office, Chicago, IL.

USEPA, 2003. Generic ecological assessment endpoints (GEAEs) for ecological risk assessment. Risk Assessment Forum, U.S. Environmental Protection Agency, Washington, DC, USA. EPA/630/P-02/004F.

Wastewater Technology Center, (1993). Sediment Treatment Technologies Database. 2^nd Edition. Burlington Ont.

Wenning R.J., and C.G. Ingersoll (Eds), 2002. Use of sediment quality guidelines and related tools for the assessment of contaminated sediments. Executive Summary Booklet of a SETAC Pellston Workshop. SETAC Press, Pensacola, FL, USA.

Wong C., 2004. Evaluating the ecological relevance of sediment quality guidelines. Poster Presentation at the 31^st Annual Aquatic Toxicity Workshop, Charlottetown, PEI, October 24-27, 2004.