Abstract
Wave Swell Energy (WSE) deployed the UniWave200 Wave Energy Converter (WEC) at Grassy Harbour, King Island, in early 2021. The project received planning and environmental approvals from King Island Council. A licence and lease for the WEC footprint and marine cable route was received from Crown Land Services.
There is a relatively high background noise from a working port and mine within close proximity to the deployment zone. Due to this context, and expected low noise emissions, the environmental impact assessment documents concluded there was very low risk of noise impacts to recreational beach users and marine fauna from the project.
The installation was approved by King Island Council without a requirement for detailed noise modelling or baseline noise measurements. There were no complaints from stakeholders or the general public regarding noise disturbances, and no evidence for any impact on marine fauna arising from noise emissions.
During operation, WSE undertook a campaign of noise monitoring to provide input for future assessments, and for scoping more detailed studies for future projects. Eight locations above water and on land were selected, and sound pressure levels were measured with a hand-held device, and the results recorded and collated.
The results confirm that noise levels from the turbine operation at the WEC itself increased with turbine operational speed. The noise from the airflap vents was consistent across turbine speeds.
For receptors at the nearest accessible point on the beach (50m from the WEC), the highest recorded sound level was 64.3dB, which is a little louder than normal conversation, and a little softer than a washing machine.
For monitoring locations on the water or the beach at 100m from the WEC or beyond, little discernable increase in noise with operation of the turbine and increasing turbine speed was detected.
It is not possible to directly compare the results of the noise monitoring to the proposed limits for vessels and motors operated on water in the EPA guidelines, as the monitoring locations were generally greater distances than those in the proposed EPA limits. This reflected the exclusion zones created for the WEC, and the minimum distance of a potential receptor on the beach to the device.
The EPA Guideline proposed limit is 74dB measured at 25m distance. The readings taken in the noise monitoring campaign did not exceed 64.3dB measured at 50m distance.
The noise monitoring program for the King Island UniWave200 project collected limited data (no baseline, limited acoustic detail eg frequency, tonal components, impulsiveness, modulation etc), however it verifies the expectations of the pre-approval environmental assessment documents. The results provide useful scoping information for designing acoustic studies if required for future projects in noise sensitive environments. These studies should also consider the need for measurement of vibration in the underwater environment.