Introduction to Disposal Site Monitoring

• The Role of Monitoring
• Conducting Monitoring Studies
• Sediment Chemistry
• Biological Testing
• Integrative Assessment
• Intensity of Monitoring
• Reporting
• Guidelines and Guidance

Canada is a maritime nation. It possesses 243,790 km of coastline, the longest of any nation in the world, and has a vital interest in preserving a healthy marine environment. Though by world standards the Canadian maritime environment is relatively uncontaminated, Canada's territorial waters do have some problems, especially in harbours, estuaries and near shore areas.

Canada regulates disposal at sea through a permit system under the Canadian Environmental Protection Act. This is one of the measures in place to protect Canada's marine environment and meet our international obligations on preventing of marine pollution by disposal at sea, set out in the London Convention 1972 and the 1996 Protocol to the London Convention.

Each year, long-term monitoring is conducted at representative disposal sites. In order to respond to Canada's national and international reporting obligations, a National Compendium of Monitoring Activities, based on regional reports, is produced annually.

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The Role of Monitoring

Disposal site monitoring allows clients continued access to suitable disposal sites by helping to ensure that the permit conditions were met. It verifies that assumptions made during the permit review and site selection process were correct and sufficient to protect the marine environment and human health.

Monitoring also plays a critical role in reviewing the overall adequacy of controls. Information compiled nationally or regionally over time provides the basis to assess whether the disposal at sea regulatory controls, guidelines and permit conditions are adequate to protect the marine environment and human health.

Experience gained with monitoring may also point to the need for research to develop better monitoring tools, or to refine the monitoring program, on specific environmental, health or public concerns. It is also expected that monitoring will uncover gaps in our understanding of impacts, particularly in the area of cause and effect relationships.

Annual meetings with clients and other interested parties will provide additional comments on past monitoring and better indication of Regional priorities for future assessments.

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Conducting Monitoring Studies

Monitoring a disposal at sea site involves an assessment of its physical, chemical and biological features. The impact hypotheses of permit reviews form the basis of subsequent monitoring.

Physical monitoring relates to the collection of relevant geological information for determining the area of deposition, delineating the disposal site boundaries, studying the accumulation of dredged material within the area of deposition, and documenting evidence of sediment transport from the disposal site.

Biological and chemical assessments are undertaken concurrently and the monitoring design for these parameters takes into account the size and dispersal characteristics of the site.

Chemical monitoring is aimed at measuring the levels of chemicals in sediments. Biological monitoring is primarily centred on biological testing in the laboratory and benthic community surveys.

Data interpretation of chemical and ecotoxicological data relies primarily on criteria employed during the permit assessment phase. When possible, data interpretation also takes into account comparisons with spatial and temporal controls, however baseline data at historical sites is generally lacking. Core parameters also include total organic carbon (TOC) and grain size to support data interpretation.

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Sediment Chemistry

Determination of sediment quality currently uses the Lower Action Levels of National Action List set out in the Disposal at Sea Regulations and are presented in Table 1. For other substances, Environment Canada may use the interim sediment quality guidelines or iSQGs. In either case, the following rules are applied for any contaminant concurrently with bioassays:

• if the observed values are below the national screening level, the disposal site sediments are considered harmless for the parameter measured,
• if the observed values are above the national screening level, further determination of sediment quality is based on the concurrent biological measurements,
• if there are clear spatial patterns of contamination or biological responses, or both, stratification of the study area can be considered for further monitoring and making further determinations of sediment quality.

For any specific contaminant, if some values are above and some below the national level, the upper 95% one-sided confidence limit on the mean concentration is calculated and the sediments are considered clean of the contaminant, if this 95% upper confidence limit is less than the national screening level. Given this, sediment chemistry concentrations are recommended to be presented as the upper 95% one-sided confidence limit or 95% U. C. L.

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Biological Testing

Test methods currently used for sediment assessment are listed in Table 2 and include:

• an acute toxicity test using marine or estuarine amphipods( the end point is lethality),
• a fertilization assay using echinoids (the endpoint is significant reduction in fertilization),
• a solid phase toxicity test using photoluminescent bacteria, (the end point is significant reduction in bioluminescence), and
• a bedded sediment bioaccumulation test using bivalves (the end point is significant bioaccumulation).

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Integrative Assessment

If sediments are below national screening levels for contaminants and pass all bioassays, no further action is required. However, if levels of contaminants or bioassay results demonstrate cause for concern then the first step is to verify compliance with the terms of the permits issued since the site was last monitored.

The second step will generally involve checking potential sources of pollutants and conducting further site characterization. After considering this information, the following hierarchy of interpretation guidance can be applied to the concurrent chemical and toxicological data:

1. if sediments at the disposal site contain substances in excess of national screening levels, pass the acute toxicity test, but fail one sublethal or bioaccumulation test: consideration could be given to modifying further use of the site and investigating the long term stability of the material onsite;
2. if the sediments contain substances below the national screening levels, yet fail any of the biological tests, then further investigation would be required to determine if this is the result of either a confounding factor such as laboratory anomaly, or the presence of a contaminant not included in the chemical screening; or
3. if the sediments contain substances in excess of the national screening levels and either fail the acute test or fail two (or more) tests: further monitoring, site closure or remediation could be considered.

As well, benthic community surveys can be used as a general sediment quality indicator. The overall assessment of the disposal site considers all available information from physical, chemical and biological monitoring.

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Intensity of Monitoring

Monitoring at every disposal site is not considered necessary, as current knowledge of impacts related to disposal of dredged material allows for good assessments to be drawn from representative disposal sites. In addition, the program attempts to ensure that the major sites (>100,000 m 3 of dredged materials/year) are monitored on at least a five year cycle. The monitoring of other sites are determined by triggers set out in the national monitoring guidelines which are based on volume, proximity to sensitive areas, or level of concern. The number of sites monitored in a year and the parameters measured at each site depend the available resources through the collection of the monitoring fees from permittees.

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Reporting

Canada's Disposal at Sea Program is administered through regional offices which are largely responsible for the permit review process, as well as for planning, conducting and reporting on monitoring studies undertaken in their administrative areas.

In order to respond to Canada's national and international reporting obligations, a National Compendium of Monitoring Activities, based on regional reports, is produced annually. Readers may request detailed information on any of the monitoring activities in this compendium, from the appropriate regional office.

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Guidelines and Guidance

In 1998, the National Guidelines for Monitoring Dredged and Excavated Material at Ocean Disposal Sites were finalised by the Disposal at Sea Program. These guidelines, which incorporate physical, chemical, biological testing and data interpretation, replace the 1993 interim guidelines and reflect the outcomes of expert workshops and field testing at the Point Grey and Cap-aux-Muels disposal sites. Monitoring studies will be carried out in accordance with the guidelines.

To support the National Guidelines, two technical guidance documents are available. The Technical Guidance for Physical Monitoring at Ocean Disposal Sites provides detailed information on geological surveying methods and sediment transport models. The Technical Guidance for Biological Monitoring covers tools for biological monitoring at disposal sites. The guidance on chemical and toxicological characterisation of sediments developed for assessment of sediments at dredged sites is also employed at disposal sites.

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