Abagold WEC BAR - Anchor Environmental

quickly to produce high volumes of harmless gas (nitrogen, carbondioxide and steam). The cartridge is sealed inside a drilled hole andignited. High pressure gas is released and enters into the fracturescaused by drilling and natural fractures or planes of weakness in therock. The gas pressure causes the fractures to expand and the rock tosplit apart. The cartridges are not explosive and not produce the nearinstantaneous pressure or shockwaves of explosives.Probability ofoccurrence withmitigationCumulative impact withmitigationSignificance withmitigationPossibleMediumMEDIUM-HIGHA.4. POTENTIAL IMPACTS TO MARINE BIOTA: WATER QUALITY (Alternatives 1, 2 and 3)Nature of impact Construction activities such as drilling and blasting are likely to generatesediment plumes, which will increase the turbidity of the water and settleon the surrounding seafloor. Another potential source of contamination ofthe water in the vicinity of the construction site is the potential chemicalpollution from the casting of concrete. The construction planning anddesign took into account the sensitivity of surrounding aquaculture facilitiesto alterations to water quality in the near shore environment from whichthey extract water with these principle sources of pollution in mind. As suchthe following features were included at the outset in the project design:Nonex will be used for all blasting. The NoneX rock breaking processproduces a much courser fragmentation when compared to thesmaller particles produced by explosives. Furthermore NoneXdetonations on land have been reported to produce negligible dustand fumes. The use of NoneX blasting technology will result in therelease of gases into the water column. None of the gases producedwill be noxious given that the cartridge is oxygen balanced andsufficient oxygen is available to achieve optimal oxidation to producegases consisting of carbon dioxide, nitrogen and steam.The casting of cement to create the base of the slot-slope wall willtake place within water tight plastic canvas bags supported andshaped within metal frames with shuttering beams. There is apotential that the spillage of cement in the marine environment mayimpair water quality temporarily in the surrounding nearshore watersand thereby impact abalone farming operations. The proposedmethod utilising metal frames, shuttering beams and plastic canvasbags will reduce the likelihood of this impact occurring.The area surrounding the construction site is particularly exposed. It isanticipated that sand particles suspended by drilling and blasting will be57