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Site Contamination

Site contamination involves occurrences of chemical substances or microorganisms on or below the site surface which are potentially harmful to human health and safety or to the environment considering present or anticipated land use. Site contamination generally involves contamination of soil and ground water.

Sources of Soil contamination

Current or past human activities such as industrialization, urban development, use of chemicals in agriculture, improper waste disposal, mining or natural processes are the prime cause of soil contamination.

Most common chemicals are inorganic (Heavy metals and asbestos), organic (Petroleum hydrocarbons), man made (Pesticides or herbicides) and solvents.

Contamination exposure and associated risk

The most common ways of people exposure to contamination are:

  • Breathing volatiles and dust Absorption through skin
  • Eating food grown in contaminated soil
  • Ingesting soil
  • The immediate and long term health risks are mainly from direct contact with the contaminated soil, vapours from the contaminants, and from secondary contamination of water by the infiltration of soil contamination such as Arsenic, Aluminium, lead, nitrate, chloride into groundwater, aquifers used for human consumption.
  • The affected people are residents on a contaminated site, children in a school or playground, workers in an occupational site, farmers in the farm, or other community groups.

Soil Contamination Effects on Ecosystems

Industrial

  1. Dangerous chemicals entering underground water
  2. Ecological imbalance
  3. Release of pollutant gases Increased salinity

Urban

  1. Public health problems
  2. Pollution of drinking water sources
  3. Foul smell and release of gases
  4. Waste management problems

Agricultural

  1. Reduced soil fertility and higher erodibility
  2. Reduced nitrogen fixation and loss of nutrients
  3. Reduced crop yield
  4. Imbalance in soil fauna and flora

Benefits of Site contamination assessment

Local council

  1. Reduction in expenditure on remediation

  2. Reduced human health risk and health care costs

  3. Improved social amenity of the site

Developer

  1. Reduction in expenditure on remediation
  2. Reduce or avoid long term cost of site maintenance
  3. Time saving on remediation and faster development

Farmer

  1. Reduction in expenditure on remediation

  2. Help to achieve revegetation and rehabilitation goals

  3. Higher price for safe produce

Buyer

  1. Reduction in expenditure on remediation

  2. Peace of mind

  3. Secure investment

The contamination is frequently found while changes in land use, for example industrial to residential, and may have considerable implications for local councils, landowners, prospective purchasers and other stakeholders. The majority of sites will only be remediated when a property transaction occurs and the cost and time implications need to be considered.

Generally jurisdictions apply a ‘polluter-pays’ rule when it comes to attributing responsibility for contamination and its clean-up. If the polluter cannot be found or alive then usually next most obvious party is an owner or occupier liable for contamination. Before purchasing a property one should check what activities have previously occurred at the site and any contamination effect of the activities on the site.

Acid sulphate soil

Acid sulphate soils are naturally occurring soils and sediments containing iron sulphides, primarily pyrite (FeS2) are usually safe when undisturbed and left in their natural condition. During their excavation they came in contact with atmospheric oxygen and can oxidise to produce a variety of iron compounds and sulphuric acid (H2SO4) which has adverse effects not only steel and concrete structures but also have detrimental effects on plants, animals and waterways due to acidification.

It is advisable for any planned construction or ongoing site management, to know where they are and how to deal with the risks if they are disturbed. As a result of increase development across Australia, requirements for the assessment and management of acid sulphate soil are commonly included as part of the planning and approval process.

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Asbestos contamination

Asbestos is naturally occurring mineral fibre and due to its insulation properties of heat and electricity it was commonly used in the construction of homes and buildings. In the past due to lack of knowledge of adverse effects and regulation asbestos was widespread used in building products such as roofing and gutters, walls, vinyl carpet and tile underlay, fencing, shades, telecommunication sheets, packing under beams, concrete formwork.

In general if a building constructed prior to 1990 there is a higher chances of finding asbestos containing material within the soil, either due to bad construction, demolition or asbestos contaminated soil used as a top soil or land fill.

Use of asbestos and asbestos containing products banned in 2003. The like hood of exposure occurring depends on the potential of the asbestos material to release airborne fibres and breathed in.