Prepared by:
Rachael Fletcher, Environmental Monitoring and Reporting Branch
Paul Welsh and Tim Fletcher, Standards Development Branch
Ontario Ministry of the Environment

May 2008
PIBS 6658e
© 2008, Queen’s Printer for Ontario

For more information:

E-mail: picemail.moe@ontario.ca
Website: Ministry of the Environment and Climate Change

Preface

Historically, two Ministry of the Environment documents addressed the assessment and management of sediment:

  • MOE 1993 – Guidelines for the Protection and Management of Aquatic Sediment Quality in Ontario. This document provided a set of numerical guidelines for protection of sediment dwelling organisms and guidance on using PSQGs to assess contaminated sediment.
  • MOE 1996 – An Integrated Approach to the Evaluation and Management of Contaminated Sediments. This document built on the information provided in MOE 1993 by providing additional guidance on assessing contaminated sediment, determining sediment management options, and implementing sediment remediation.

Recently, under the 2002 Canada-Ontario Agreement Respecting the Great Lakes Basin Ecosystem (COA), the Ministry and Environment Canada developed a harmonized framework for assessing contaminated sediments in the Great Lakes (COA 2007, Canada-Ontario Decision Making Framework for Assessment of Great Lakes Contaminated Sediment). This COA sediment assessment framework builds on Ontario’s existing ecosystem approach to sediment assessment; it identifies all possible sediment assessment outcomes based on four lines of evidence (sediment chemistry, toxicity, benthos alteration, and biomagnification potential) and provides more specific direction on next steps in making sediment management decisions.

While developed specifically for use in the Great Lakes, the Ministry recognized that the COA sediment framework can be applied to assess contaminated sediments province-wide. This document incorporates the COA sediment assessment framework with existing Ministry guidance on assessing and managing contaminated sediments (MOE 1993 and MOE 1996) into a single integrated Ministry guidance document for identifying, assessing, and managing contaminated sediments in Ontario. To avoid confusion, the previous Ministry sediment guidance documents have been replaced with this integrated document.

Minor modifications were made to portions of the previous Ministry guidance documents to either update sections with current information (e.g., update the section on legislation; replace Open Water Disposal Guidelines with Lakefill Guidelines) or to make the material easier to read (e.g., some sections were rearranged). However, no changes were made to the Provincial Sediment Quality Guidelines (PSQGs) or to the process used to develop them. For this document, the only significant change to previous MOE guidance is the addition of the COA sediment assessment framework. The Ministry is planning to review PSQGs and the protocol used to derive them. This document may be revised in the future based on the results of this review.

Minor modifications were also made to the COA sediment assessment framework to ensure that the information is consistent with existing Ministry regulations and environmental programs. These changes did not change the process outlined in the COA sediment assessment framework.

Public consultation on the methodologies and guidelines referred to in this integrated sediment guidance document have occurred via the Environmental Registry as follows:

  • An Integrated Approach to the Evaluation and Management of Contaminated Sediments (MOE 1996) was posted on the Environmental Registry with a public comment and review period starting April 19, 1995 through to May 19, 1995 (see EBR # PA5E0016)
  • Canada-Ontario Agreement Contaminated Sediment Assessment Decision-Making Framework (COA 2007) was posted on the Environmental Registry with a public comment and review period starting November 21, 2006 through to January 20, 2007 (see EBR # PA06E0007)
  • Guidelines for the Protection and Management of Aquatic Sediment Quality in Ontario (MOE 1993) was not posted on the Environmental Registry as it predates the establishment of the registry. However, it was reviewed by the Advisory Committee on Environmental Standards, an independent advisory body in place at that time to advise the Ministry of the Environment on environmental standards.

Executive Summary

Contaminated sediment is a major environmental concern in many areas of Ontario, especially the Great Lakes (IJC 1985). Persistent toxic substances that have accumulated in bottom sediments from industrial, municipal and non-point sources are a threat to the survival of bottom-dwelling (benthic) organisms and their consumers, and can impair the quality of the surrounding water. In order to deal effectively with sediment contamination problems, environmental managers need to determine levels of contaminants that do not pose a risk to sediment-dwelling organisms and their consumers (or to other water uses), from levels of contaminants that are potentially detrimental.

It has long been recognized that sediment chemistry alone is not sufficient to accurately predict adverse biological effects. Thus, sediment chemistry is usually only used as an initial screening tool for determining if higher ‘effects based’ tiers are needed. The use of biological endpoints, such as information on sediment toxicity, the benthic community and/or biomagnification potential are often needed to properly assess the potential ecological and human health risk posed by contaminated sediment. This document provides guidance on identifying, assessing, and managing contaminated sediments in Ontario using both chemical and biological information. It integrates the guidance provided in two earlier Ministry documents for assessing and managing contaminated sediment (MOE 1993, MOE 1996) with a decision-making framework for assessing contaminated sediments developed jointly by the Ministry and Environment Canada (COA 2007).

This document is comprised of 3 parts:

  1. Identifying potential sediment contamination (from MOE 1993, Guidelines for the Protection and Management of Aquatic Sediment Quality in Ontario).
  2. Assessing the potential for contaminated sediments to impair the aquatic environment (from COA 2007, Canada-Ontario Decision Making Framework for Assessment of Great Lakes Contaminated Sediment).
  3. Managing contaminated sediments to reduce contamination and adverse impacts to the aquatic environment (from MOE 1996, An Integrated Approach to the Evaluation and Management of Contaminated Sediments).

Potential sediment contamination is identified by comparing concentrations of substances in sediment to the Provincial Sediment Quality Guidelines (PSQGs); a set of numerical guidelines for the protection of sediment dwelling organisms. When PSQGs are exceeded, additional biological assessments, such as sediment toxicity tests and other biological effects (e.g. benthic community and biomagnification potential), are evaluated. Assessment of contaminated sediment relies on the approach provided in the COA Sediment Framework (COA 2007). The framework considers four lines of evidence simultaneously (sediment chemistry, toxicity, benthos alteration, and biomagnification potential), and this information is then assessed in a decision-making matrix whereby the need for management actions can be identified. The assessment component of the 1996 MOE guidance document and the COA framework both consider the same lines of evidence. However, the COA framework is more structured and transparent. The sequential process to assessing sediment contamination outlined in the COA framework has been adopted and incorporated into this document. The decision matrix, which is compiled following the assessment of the four lines of evidence, allows areas to be identified that require no additional action, further assessment, or specific management decisions.

Prior to any remedial action, permits and approvals may be required under different legislation. An overview of the legislation which may impact management decisions, as well as a brief overview of some remedial options, are provided based primarily on information contained in MOE 1996 but updated to reflect new and amended legislation.

Acknowledgements

Many ministry staff contributed their knowledge, expertise and time to review this document and make useful comments and suggestions. The two MOE documents that make up an integral part of this document were originally developed by R. Jaagumagi, D. Persaud and A. Hayton. The sediment assessment portion of this document, derived from the COA sediment assessment framework, was a result of input from staff from provincial and federal government agencies, as well as external agencies (including academia, the private sector, and other governments). The final COA document was prepared by P.M. Chapman, under the guidance of J. Anderson (Environment Canada) and D. Boyd (MOE), and the members of the COA Sediment Task Force.

1. Introduction

1.1 Background

Contaminated sediments are a major environmental concern in many areas of Ontario, especially the Great Lakes (IJC 1985). Persistent toxic substances that have accumulated in bottom sediments from industrial, municipal and non-point sources are a threat to the survival of bottom-dwelling (benthic) organisms and their consumers, and can also impair the quality of the surrounding water.

Sediments contaminated by such substances have become a critical problem for environmental managers. In order to deal effectively with sediment contamination problems, environmental managers need to determine levels of contaminants that do not pose a risk to sediment-dwelling organisms and their consumers (or to other water uses), from levels of contaminants that are potentially detrimental.

The need for biological effects-based guidelines for the evaluation of sediment is well recognized. Current sediment related issues are much broader than those identified in the early 1970's and knowledge based on information accumulated over the last decade or so (e.g., 1980s) requires that strategies be developed to manage contaminated sediment. Guidelines for the evaluation of sediment must provide the basis for determining when sediments are considered clean, what levels of contamination are acceptable in the short-term, and when contamination is severe enough to warrant significant remedial action.

It has long been recognized that sediment chemistry alone cannot be used to predict biological effects. Thus, sediment chemistry is often only used as an initial screening tool for determining if higher ‘effects based’ tiers are needed. The use of biological endpoints, such as sediment bioassays, benthic community evaluation and biomagnification potential are crucial in the assessment of sediments for dredging, cleanup or monitoring.

1.2 Purpose

In the 2002 Canada-Ontario Agreement (COA) Area of Concern (AOC) Annex, Result 4 “Management Strategies for Contaminated Sediment”, both Canada and Ontario committed to developing a ‘risk-based decision-making framework’ for the assessment of contaminated sediments. COA Annex AOC: Result 4 identifies the need to develop management strategies for contaminated sediment in the Great Lakes. Towards that goal, the Ministry of the Environment (MOE) and Environment Canada have developed a sediment assessment tool.

Two Ministry guidance documents were historically available with respect to the assessment and management of contaminated sediment:

  • MOE 1993 – Guidelines for the Protection and Management of Aquatic Sediment Quality in Ontario (PSQGs). This document provided a set of numerical guidelines for protection of aquatic biota: the No-Effect Level (NEL), the Lowest Effect Level (LEL) and Severe Effect Level (SEL). The NEL are based on the related Provincial Water Quality Objectives (PWQO) and the LEL and SEL are based on co-occurrence of chemical and biological information. Some guidance on using PSQGs to assess contaminated sediment was also provided in this document.
  • MOE 1996 – An Integrated Approach to the Evaluation and Management of Contaminated Sediments built on the information provided in MOE 1993 by providing additional guidance on assessing contaminated sediment and information on managing sediment contamination.

The COA Sediment Decision-Making Framework (COA 2007) provides one consistent and harmonized approach to assess contaminated sediment. The framework provides a decision making framework that considers four lines of evidence simultaneously (sediment chemistry, toxicity, benthos alteration, and biomagnification potential), and identifies the need for management actions based on observed exceedances/effects in the different lines of evidence. The previous MOE 1996 document and the COA sediment assessment framework both consider the same lines of evidence. However, the COA framework is more structured and transparent.

This document provides guidance on identifying, assessing, and managing contaminated sediments in Ontario using both chemical and biological information. It integrates the guidance provided in two earlier Ministry documents for assessing and managing contaminated sediment (MOE 1993, MOE 1996) with a decision-making framework for assessing contaminated sediments developed jointly by the Ministry and Environment Canada (COA 2007). This document comprises 3 parts:

  1. identifying sediment contamination;
  2. assessing its potential to impair the aquatic environment; and,
  3. managing the problem.