Thoughts​

There was a lot to unpack in this judgement.

Key points to take away for both acoustics professionals and clients alike are:

• Any noise modelling or assessment of the initial design for the facility undertaken during the planning and/or permitting stages of a project should not be relied upon by a contractor when engaged in a design and build contract. The joint experts found grave errors in the noise models and assessments provided to the Environment Agency, and agreed that it was unlikely that the design in front of the regulators would have been able to operate without causing significant adverse effects to the surrounding community. This did not, however, alter the main contractor’s duty to provide a facility which complied with the environmental permit.

• The experts did not agree what compliance with the permit actually meant in terms of acoustic performance standards. Complicating this matter was the permit requirement to construct and operate the facility in accordance with the reports submitted to the Environment Agency, which set out expected noise levels at offsite receptors, but which the experts had identified as being gravely flawed documents. However, the judgement considered that at the most basic level, compliance with the permit was to ensure that “emissions from the activities shall be free from noise and vibration at levels likely to cause pollution outside the site, as perceived by an authorised officer of the Environment Agency” and that the facility provided by M+W did not achieve this standard.

• It is vitally important to understand that multiple acoustic criteria may be incorporated in a contract. They may be directly referenced, such as a schedule of equipment noise levels set out in an annex, or they may be indirect through a general requirement e.g. to comply in all respect with all the latest relevant legislation, the Environmental Permit and the associated conditions, the Planning Consent, and the Control of Noise at Work Regulations 2005. Both approaches have weight and neither can be ignored by the designers. In some situations, additional studies (e.g. new baseline noise measurements) may be required to establish what the contract noise limits are.

• Some responsibility for site wide noise limits can be passed to equipment suppliers via subcontracts. In an ideal situation, a comprehensive noise model of all plant and equipment would be developed and updated as the design progresses, most likely by the main contractor. However, in lieu of such design coordination, equipment manufacturers may still be obliged under their contract to ensure their items of supply conform with planning/permit noise criteria when considered in isolation.