Australian and New Zealand Environment and Conservation Council, 2000
Removal
Removal processes on small craft (<25m) should use the best available techniques that do not entail excessive cost. The same tarpaulin and sheeting processes should be used when removing paints as have been specified for the application of paints. This would allow cheap collection of wastes for off site disposal.
No removal should be undertaken while the vessel is in the water. Removal should not be undertaken on beaches or in the intertidal zone. All removal should be undertaken at appropriately equipped and approved facilities.
Old antifouling coatings are not to be burnt off. Over the past fifty years antifouling formulae have used a variety of extremely hazardous active chemicals and the practice of burning these paints may place both the operator and people in the immediate vicinity at risk. Further, the burning of antifouling paint residues after removal may generate highly toxic fumes, smoke and gases. All antifouling paint residue should be treated as contaminated waste and should be disposed of in accordance with the requirements of local environmental and/or waste disposal authorities.
5.1 In General
- Measures must be undertaken to contain wash waters and to segregate wash water from non-contaminated flows.
- Measures should be taken to prevent particulate matter being flushed from a dry dock, slipway or hardstand when a vessel is being treated or refloated.
- Measures should be taken to reduce wind-blown particulates.
- Release of either particulates or wet waste, contaminated with tributyltin, into the adjacent water way must be avoided.
- All antifouling wastes should be treated as controlled wastes as they are all contaminated with biocides. Such waste should be collected for disposal at an appropriate facility, in accordance with local environmental and/or waste disposal authorities.
- Paint scrapings should be treated as contaminated waste and disposed of in accordance with the requirements of local authorities.
- Residues should not be washed into the sea.
5.2 Releases to Air
- Wet abrasion is preferable to dry abrasion, which can create toxic dust.
- Dry grit blasting creates dust problems and methods should be employed to contain this dust.
- Use of wet methods controls particulate emission to air but generally creates high volumes of liquid waste. Ultra high pressure water blasting, with lower volumes of liquid waste, is likely to become widely available in the future.
- Vacuum blasting, or containment blasting, with reusable abrasives and separation equipment is the current best option for removal of used antifouling coatings.
If vacuum or containment blasting is employed emission targets should be as follows:-
- if operating without wet particulate arrest, exhaust emissions of 35mg/m3 should be targeted;
- if operating with wet particulate arrest, exhaust emissions of 20mg/m3 should be targeted.
5.3 Releases to Water
- Use of water during removal should be minimised by moving towards ultra high pressure water blasting, vacuum or containment blasting.
- Use of high pressure blasting should be minimised and coloured run off should be avoided.
- Where practical, water should be recollected for either recycling or for release to sewer (with the approval of local sewerage authorities) so that the water can be treated.
- Release to sewer, where approved by local authorities, should be controlled to allow maximum dilution in the sewerage system.
The discharging of wastewater, contaminated by antifouling paints, to the sewerage system may cause concern with sewerage managers because sewage treatment is dependent on bacterial processes. Antifouling paints have broad toxic effects and their biocidal impacts on bacteria in sewage systems is unknown. However, the quantities of water flowing through the sewage systems compared to the quantities of waste water evolved during boat cleaning are sufficiently different to allow the yard operator to take advantage of dilution effects. Gradual release of waste water from shipyards to the sewer, i.e. by releasing the water through a very small aperture pipe, will assist in minimising any potential biocidal effects. Approval would need to be sought from the relevant sewerage manager.
- Hosing and brushing down activities, without the use of detergents or abrasives to remove weed and barnacles, generally do not require specialised treatment to retain and dispose of material removed. However, if the material includes live organisms from another country or a distant part of Australia, all debris should be collected for disposal as solid waste. Check with the port or marina management on controls on ballast or fouling organisms.
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