Types of waste associated with removal of TBT hull coatings include:
- Surface cleanings to remove fouling organisms which have the potential to remove TBT paint along with the organisms themselves;
- Paint chips and other paint remnants, either dry from scraping, sanding, etc.; or in washwater, water used in wet blasting;
- Dissolved TBT and degradation products, in washwater and water used in wet blasting;
- Contaminated sand or grit used in blasting; and
- TBT removed from waste materials by physical means, such as filtration or water treatment.
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There are principally three methods for the removal of anti-fouling systems:
Scraping: sanding, grinding, or scraping by hand or equipment to scrape off the paint;
Blasting: grit blasting (dry blasting, wet blasting); and
water blasting/washing: (low, medium and high pressure).
Requirements for removal of AFS:
As with all facilities for coating removal, basic requirements for the facility are an impermeable floor or work surface and a means for capturing and containing AFS waste, fouling materials, dust, and, if water is used for removal, water contaminated with waste.
The floor or work surface should be clean at the start of the operation. Structures and materials within the work space that are not needed during blasting should be removed from the work area.
Persons involved in the removal of AFS coatings should wear personal protective equipment (such as, fluid impermeable gloves, face mask, safety glasses, protective suit; respiratory protection is advisable if waste material is likely to become airborne).
Due to the use of high pressure air or water involved and the potential spread of paint over considerable areas, grit blasting is only recommended for an enclosed area or in a dry dock with features allowing the collection of aerosol particles, solids.
Preparatory assessment and action for removal of AFS:
If possible, prior to starting the anti-fouling coating removal operation, the facility shall ascertain the type of AFS on the hull.
This information may be available on the ship’s documentation as required by the AFS treaty.
When the type of AFS is known, appropriate measures can be taken during removal, handling, treatment, and disposal. For example, waste from a non-biocidal coating may be disposed of differently than waste from a biocidal coating. Chemical treatment of waste materials may differ depending on the nature of the biocide.