Disposal at Sea Info:

Disposal At Sea Monitoring Program

Disposal site monitoring is an integral part of the Disposal at Sea Program. Monitoring data provides important feedback to the permit application review process whereby terms and conditions of the permits may be incorporated and modified as necessary to ensure that the marine environment is protected.

At a minimum, the major disposal at sea sites (those receiving more than 100 000 cubic metres of material per year) are monitored on a five year cycle. For other disposal sites, monitoring programs are established on a site-specific basis. Current understanding of environmental effects related to the disposal of dredged and excavated material allow environmental assessments to be drawn from representative disposal sites.

There are thirty-eight designated disposal at sea sites in the Pacific and Yukon Region, of which fifteen are routinely used.

Click here to see a map of the disposal sites off the coast of British Columbia.

The Point Grey disposal site is the largest multi-user disposal site in the Pacific and Yukon Region. As a result, the most comprehensive monitoring programs have been focused at this location.

Sediment samples from the disposal sites and reference areas are collected and analysed for chemical, biological and physical characteristics. Trace metal levels are measured as well as polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs), sediment particle size distribution, total organic carbon, and dioxins. Guidelines for sampling and testing these sediments are routinely updated to keep pace with new technology.

Two main types of sampling methods are used: grab samples and core samples. Grab samples are obtained using a modified stainless steel Smith-McIntyre benthic grab sampler. This type of sampler is used to collect an undisturbed sediment sample from the ocean floor which can be analysed for sediment chemical concentrations. A gravity core sampler is used to obtain vertical sediment cores from the ocean floor. Cores are typically one to two meters in length and ten centimetres in diameter. The cores are sectioned and each section is analysed for the previously mentioned chemical parameters.

In addition to physical and chemical analyses, some sediment samples are tested for toxicity using various marine organisms. The biological tests are designed to measure acute, chronic and sub-lethal effects, all of which can indicate unacceptable environmental impacts from ocean disposal activities. In addition to contaminant effects, several factors can influence test results, for example: fine grain size, or the presence of toxic levels of ammonia or sulphide in marine sediments.

In recent years, the physical environment of the Point Grey disposal site has been visually characterised with the use of underwater video and sidescan sonar surveys.

A remotely operated vehicle (ROV) equipped with video and still cameras is used to record images of the disposal site and the surrounding ocean floor. Predetermined track lines plotted across the disposal site are followed by the ROV and continuous images of the ocean bottom are recorded. These visual images aid in the qualitative evaluation of the disposal site environment.

Sidescan sonar mosaics of the ocean floor are used to illustrate the placement of material at the disposal site. Both these systems are often used in the evaluation of ocean disposal activities and to monitor change in the benthic environment at the disposal sites

Results of the Ocean Disposal Control Program monitoring surveys are published in Environment Canada reports as part of annual summaries of all ocean disposal activities in the Pacific and Yukon Region.

Monitoring Picture Gallery

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