Abagold WEC BAR - Anchor Environmental

mitigationSignificance withmitigationN/AB.4. POTENTIAL IMPACTS TO NEIGHBOURING USERS: WAVE AND CURRENT REGIME CHANGES(Alternative 1, 2 and 3)Nature of impact The development of solid structures and the alteration to the shape ofthe coastline will result in alterations to the nearshore wave regime.Since the seabed is predominantly rocky it is not expected that erosionof the seabed will occur but there may be a slight redistribution of thesand pockets among the rock gulleys. Erosion of structures or coasts isnot expected. The vessels entering the existing port or maneuveringtowards it will not face significant problems from the reflection patternsfrom Abagold since the reflected waves will be unnoticeable at thedistance of the local fishing boat shipping routes to the harbour.During severe storms and spring high tides as the wave energyapproaching the site will be considerable and, with swell from the morewesterly directions (e.g. WSW), there is a potential risk of increasedoccurrence and intensity of reflections towards the Aquafarm pumpstation. Some damage may be inflicted during these events over andabove that expected in the absence of the WEC structures.StatusExtentDurationIntensityProbability ofoccurrenceCumulative impactprior to mitigationSignificance prior tomitigationDegree to which impactcan be mitigatedProposed mitigationNegativeLocalLong-termMediumPossibleMediumHIGHHighconstructing a rock slope against the vertical walls at those locationscomprising a 1 in 2 slope with rock sizes of 1 to 3 tonnes.It should be emphasized that the above recommendation is indicativeonly and that the slope needs to be designed by paying special attentionto the stability of the base of the slope (toe) and the correct weight ofthe rocks to avoid their displacement during storm events.A more detailed assessment using analytical models is necessary toconfirm whether the reflections described are of concern and whetherthe proposed rock slope is sufficient. It is thus recommended that a68