Guideline for underwater noise: Installation of impact or vibratory driven piles. March 2023.

Abstract

In recent years, there has been a growing concern about the effect of underwater noise from human activities on marine mammals. Based on the advice from a previous working group, the Danish 2016 Guideline for underwater noise from installation of impact-driven piles was formed. The Guideline from 2016 only consider impact in the form of permanent impact on the hearing of marine mammals, as the empirical evidence regarding other forms of impact was considered insufficient at the time the Guideline was formed. Further, frequency weighting principles applied to marine mammals were only just becoming an established scientific approach at the time of writing the 2016 Guideline. This has changed in the recent years, and as part of the process leading to this update of the Danish Guideline, relevant scientific evidence has been extracted by DCE in a series of technical reviews that serve as background reports for this document. The technical reviews from DCE and this Guideline have been discussed in a new working group before being published. The working group consist of following members: - Professor Jakob Tougaard AU/DCE/ Department of Bioscience, section for Marine Mammal Research - Principal Consultant René Smidt Lützen, Vysus Denmark A/S - Special Advisor Anna-Grethe Underlien Pedersen, Danish Environmental Protection Agency - Advisor Nynne Elmelund Lemming, Danish Environmental Protection Agency - Special Advisor Søren Enghoff, Danish Energy Agency - Special Advisor Søren Keller, Danish Energy Agency The most important changes in this current revision of the Guideline are: a. Inclusion of behavioural disturbance of marine mammals and b. Introduction of frequency weighting principles and acoustic criteria according to auditory groups. Both features are deemed more just and biologically correct in assessments of impacts. The Guideline now further specifies: c. Criteria and procedures for use of Acoustic Deterrent Devices (ADD), d. Adapted procedures for impact and vibratory driving and e. Calculation of Distance-to-Threshold. The Guideline relates to a set of standard conditions normally found in the Construction Permit for offshore windfarms. The standard conditions, the Guideline and the DCE background reports can be found on the Danish Energy Agency website, www.ens.dk.