Investigation of pollution incidents

    Gathering science-based evidence

    Gathering evidence for licence compliance and enforcement action, under the Environmental Protection Act 1994, often involves the design and conduct of scientifically robust studies of environmental harm, such as contamination of waterways and consequent harm to plants and animals. A number of methods are used to gather this information. This includes assessing contamination of water, sediments and organisms within waterways that have been exposed to impacts from undesirable practices such as the release of unauthorised discharges.

    The evidence gathered is often used in the Planning and Environment Court for cases where individuals and companies are disputing alleged breaches of development approvals or licence conditions. In addition, it is used in prosecutions in the criminal courts against individuals and companies for allegedly causing environmental harm under the Environmental Protection Act.

    Gathering investigative evidence can involve a range of techniques. This includes sampling environmental materials (e.g. water and sediment sampling) in a range of environments (e.g. sampling drain lines as well as creeks) to detect contaminants and find the sources of contamination (e.g. oil contamination via a stormwater drain). Samples of potentially impacted plant and animal life are also taken for evidence of contamination and/or evidence of adverse effects attributable to contamination (biomonitoring).

    The quality of sample-based evidence of contamination is assured by compliance with accepted codes of sample collection and sample preservation, such as those published in the Department's Water Monitoring and Sampling Manual.

    Photo of an oyster.
    Photo of oysters in bags.
    Photo of a crab.
    Photo of a crab.

    Biomonitoring - assessing contamination of organisms

    ‘Biomonitoring’ means the use of living organisms (plants or animals) as indicators of ecological health and/or the presence of contamination.

    The presence or absence of plant and animal species, or their abundance relative to what is expected at a ‘healthy’ location, can be used as an indication of ecological health. At impacted sites, some of the more tolerant species may dominate, and less tolerant species may be absent.

    Where contaminants are present, these can often be identified and quantified by chemical analysis of samples of plants and animals from that location. This kind of biomonitoring has three important advantages over simply analysing water and sediments for the presence of contaminants:

    • many organisms accumulate contaminants, making them easier to detect and measure
    • the presence of contaminants in the tissues of plants and animals is irrefutable evidence that the environmental contaminants are present in a form that organisms can absorb
    • only sampling water and sediment may fail to detect intermittent releases of contamination, whereas plants and animals that are resident in the area of interest tend to accumulate and retain the evidence.

    Species used by the department to detect and quantify contaminants in Queensland estuaries have included:

    • Typha (bulrushes), which are useful accumulators of metals and other contaminants.
    • Oysters, which can be sampled in situ. Alternatively, they can be deployed in cages to places where they are not naturally growing to monitor contaminants.
    • Crabs, such as mud crabs (Scylla serrata), fiddler crabs (Uca coarctata) and semaphore crabs, Heloecius cordiformis, are common species used as ’sentinel organisms’ to detect and quantify contaminants in Queensland estuaries.

    Case studies

    Contamination of the marine environment by processing waste from scrap aluminium recycling

    Although the recycling of scrap aluminium, such as empty drink cans, consumes less energy than extracting aluminium from bauxite ore, the recycling process generates intractable wastes, such as slags and saltcake.

    A company purporting to use those wastes to produce useful products set up at a shore-side location near Rockhampton. Although the company did extract some additional aluminium from the slags and saltcake, an ever-increasing stockpile of processed waste began to accumulate and leach toxic materials on to mudflats and the marine environment adjacent to the site. This was largely due to poor stormwater management. Testing demonstrated the toxicity of the waters escaping from the site to marine life. As a consequence of proceedings in the Planning and Environment Court, the company ceased operations and was required to remove the accumulated toxic wastes from the site.

    Contamination of sediment from a development site silting up a creek

    When developers clear vegetation from land to build roads and other infrastructure, the exposed soil is prone to erosion. Developers are required to manage runoff and sediment control to prevent siltation of creeks. Excess sediments washed into creeks can harm aquatic animals by blocking out light, destroying essential habitat and smothering plants.

    There have been a series of successful prosecutions of developers who failed to construct and manage adequate sediment and runoff control systems.

    One of these was in Townsville. Scientific investigation of the sediment chemistry demonstrated that the sediment that flowed into the creek came from the development site and not from other tributary sources. The company was prosecuted and fined.

    Tallow from a meat rendering works escaping into a creek

    In Mackay, escape of hot tallow from a meat rendering works fouled the bed of a tidal creek and smothered aquatic life. Spills of animal fats and vegetable oils into creeks can cause similar harm to aquatic life as spills of petroleum-based oil. The company was prosecuted and fined.