Abagold WEC BAR - Anchor Environmental

Significance prior tomitigationDegree to which impactcan be mitigatedProposed mitigationCumulative impact withmitigationSignificance withmitigationLOWNo mitigation requiredN/AN/AN/AA.7. POTENTIAL IMPACTS TO NEIGHBOURING USERS: WATER QUALITY AND INTAKE (Alternatives 1and 2)Nature of impact Several abalone farms, including Abagold, extract seawater foraquaculture purposes in the vicinity of the proposed development site.The quality of the feedwater must be maintained so not to adverselyimpact these aquaculture activities. During the project design phasesome of the impacts were anticipated and much consideration was givento reducing or eliminating these impacts through the use of innovativeconstruction methods. The construction planning and design particularlytook into account the sensitivity of surrounding aquaculture facilities toalterations to water quality in the near shore environment from whichthey extract water. The principle concerns regarding water qualityinclude potential chemical pollution from the casting of concrete directlyin the water as well as the increase in suspended solids followingblasting. As such the following features were included at the outset inthe 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.60