Wylfa Newydd Nuclear Power Station, Wales
Horizon Nuclear Power propose to build a £14 billion new nuclear power station at Wylfa on the Isle of Anglesey. To minimise movement of materials by road, a marine off-loading facility is proposed which, together with the cooling water intake and outfall, requires large scale marine construction works. Associated developments include a temporary Park and Ride, a temporary logistics centre, and highways improvements (sections of the A5025 to be widened or bypassed). On site accommodation and facilities for up to 4,000 construction workers is also included in the proposals.
Sam was head of discipline for noise and vibration, and acted as expert witness on behalf of Horizon at examination. Click on the buttons below to learn more about some of the challenges of this project.
Terns
One issue for this site is the proximity of nesting sites for protected seabirds (species of tern), which resulted in concerns from Natural Resources Wales that noise from blasting and construction would harm the colony. In the UK there is no accepted procedure for predicting the maximum noise level (LAF,max) from blasting, and therefore Sine Environmental developed a methodology which brought together internationally accepted methods of predicting air overpressure (which include inaudible low frequency pressure waves) with research on typical frequency spectra of different blast conditions to predict the audible component of the air overpressure. This methodology was peer reviewed by Amec (now Wood plc) and later borne out by field tests; the measured noise levels at the tern colony due to out of season test blasts compared well with the predictions. An extensive noise measurement and behaviour observation campaign was also undertaken to identify the threshold at which the nesting terns reacted to existing noises in the environment.
Arctic Tern
Typical tern fly-up.
Arctic Tern
Construction Noise Modelling
Another major concern are construction noise and vibration effects at nearby residential dwellings, as the site is bounded by settlements on three sides. The combined marine and earthworks activities are forecast to require over 700 items of construction plant operating simultaneously during the busiest periods. Many of the construction activities would extend into the evening, and some operations would be 24 hour per day. To minimise disruption to residents, Sine Environmental recommended accelerating the site grading phase, and changing the destination of material arising from this so that it is further from settlements. Doing this minimised the duration that the site grading overlaps with the movement of bulk material arising from the deep excavations, thereby reducing the periods of maximum noise levels near dwellings. Sine Environmental worked with the Horizon property team to develop a voluntary noise insulation scheme and programme to provide new double or secondary glazing, acoustic ventilators, blinds so that qualifying residents would be able to sleep with their windows closed; this scheme also covered noise from the A5025 highway improvements, construction traffic noise and operational vehicle movements in the future.
Performed in accordance with BS5228:2014 using Cadna/A