EXTENSION OF HARBOUR IN NUUK UNDERWATER NOISE FROM BLASTING

Transcription

1 EXTENSION OF HARBOUR IN NUUK UNDERWATER NOISE FROM BLASTING

2 EXTENSION OF HARBOUR IN NUUK UNDERWATER NOISE FROM BLASTING Revision 02 Date Made by Christopher McKenzie Maxon, Ditte Marie Mikkelsen Checked by Emine Christensen Approved by Ditte Marie Mikkelsen Ramboll Hannemanns Allé 53 DK-2300 Copenhagen S Denmark T F

3 UNDERWATER NOISE FROM BLASTING CONTENTS 1. Introduction 4 2. Applicable Acoustic Parameters Background on underwater sound Marine Mammal Frequency Weighting 5 3. Modeling Senario and source level Scenario Source level 7 4. Modeling Methodology Sound Propagation Model 9 5. Bathymetry and Acoustic Environment Bathymetry Geoacoustic Properties Sound Speed Profiles Model Results Sound propagation Impact Assessment Fish Marine Mammals Marine Mammal and Fish Criteria Impacts to fish and marine mammals Mitigating Measures Bubble curtains Sound propagation Impacts to fish and marine mammals Other mitigating measures References 21

4 UNDERWATER NOISE FROM BLASTING 4 1. INTRODUCTION The construction of the Nuuk Harbour Extension will require deepening of the sea bottom. Before the bottom material can be removed, underwater blasting is required. Blasting generates loud underwater sound that can potentially be an environmental impact on the marine life in the area. A modelling study has been carried out to determine the levels of underwater sound resulting from blasting to assess the environmental impact. The acoustic model produces estimates of the anticipated sound field generated from the blasting. The model accounts for source characteristics and acoustic propagation in a complex, multi-layered, nonhomogeneous ocean environment. This approach takes into account the specific properties of the water column and bottom in the area, as much as is known. The scenario modelled as part of this study is described in Section 3, as are the estimated sound source input to the sound propagation model. The modelling methodology is outlined in Section 4. Section 5 describes the source location and modelling parameters required by the propagation model. Finally, the results of the modelling study are discussed in Section 5. The modelling results are used to determine the potential impacts distances from the blasting for the various identified marine life for the area. Potential mitigations measures are identified as well as their estimated effectiveness.

5 UNDERWATER NOISE FROM BLASTING 5 2. APPLICABLE ACOUSTIC PARAMETERS 2.1 Background on underwater sound Underwater sound, like sound in the air, is disturbances from a source in a medium here water travelling in a 3 dimensional manner as the disturbance propagate with the speed of sound. Sound travels at different speed in different media. The speed of sound is determined by the density and compressibility of the medium. Density is the amount of material in a given volume, and compressibility is a measure of how much a substance could be compacted for a given pressure. The denser and the more compressible, the slower the sound waves would travel. Water is much denser than air, but since it is nearly incompressible the speed of sound is about four times faster in water than in air. The speed of sound can also be affected by temperature. Sound waves tend to travel faster at higher temperatures. Underwater sound can be measured as a change in pressure and is described as sound pressure and can be measured with a pressure sensitive device (hydrophone). Because of the large range pressure amplitudes of sound, it is convenient to use a decibel (db) logarithmic scale to quantify pressure levels. The underwater sound pressure level in decibels (db) is defined in the following equation: Sound Pressure Level (SPL) = 20log 10 (P/P 0 ) P is the pressure and P 0 is the reference pressure. The reference pressure is 1 micropascal (µpa) for underwater sound which is different for sound pressure levels in the air. For this reason sound pressure levels in the water and air cannot be directly compared. Underwater sound levels vary in accordance to the sound source s time signature and acoustic environmental conditions and can be future defined in terms of exposure, average and/or maximum levels. The following acoustic parameters are commonly used to assess the noise impact from underwater noise sources for the identified local marine life. The RMS SPL (Lp) is commonly used to evaluate the effects of continuous noise sources. The RMS sound pressure level or SPL (symbol L p) is the mean square pressure level over a time window containing the impulse. The peak sound pressure level (symbol L pk) is the maximum instantaneous sound pressure level attained by an impulse. The sound exposure level (SEL, db re 1 µpa 2 s, symbol LE) is commonly used to quantifying levels of impulsive sources. It is the time integral of the squared pressure over a fixedtime window containing the entire pulse event normalized to 1 second. This measure represents the total energy delivered over the duration of an acoustic event at a receiver location. The SEL is related to sound energy (or exposure) rather than sound pressure. SEL can be a metric that describes the sound level for a single sound pulse or a cumulative metric, if applied over a period containing multiple pulses. 2.2 Marine Mammal Frequency Weighting The potential for underwater noise to impact marine species depends on how well the species can hear the sounds produced (Southall et al. 2007). Noises are less likely to disturb or injure animals if they are at frequencies outside the animals hearing range. For non-injurious sound levels, frequency weighting based on audiograms may be applied to weight the importance of sound levels at particular frequencies in a manner reflective of the receiver s sensitivity to those frequencies (Nedwell and Turnpenny 1998, Nedwell et al. 2007). Based on a review of literature on marine mammal hearing and on physiological and behavioural responses to anthropogenic sound, Southall et al. (249) proposed standard

6 UNDERWATER NOISE FROM BLASTING 6 marine mammal frequency weighting (M-weighting) functions for various functional hearing groups of marine mammals: Low-frequency cetaceans (LFCs) - mysticetes (baleen whales) Mid-frequency cetaceans (MFCs) - some odontocetes (toothed whales) High-frequency cetaceans (HFCs) - odontocetes specialized for using high-frequencies Pinnipeds in water - seals, sea lions and walrus Functional hearing group Estimated auditory bandwidth Low-frequency Cetaceans (LFC) 7 Hz 22 khz Mid-frequency Cetaceans (MFC) 150 Hz 160 khz High-frequency Cetaceans (HFC) 200 Hz 180 khz Pinnipeds (PINN) 75 Hz 75 khz Table 2-1 Functional hearing groups and associated auditory bandwidths (Southall et al. 2007).

7 UNDERWATER NOISE FROM BLASTING 7 3. MODELING SENARIO AND SOURCE LEVEL 3.1 Scenario At the time of writing of this document, the specific amount of blasting material, as well as the drilling depth had not yet been identified. Therefore, a sample scenario was constructed using the simple case of a single explosive charge with size and burial depth as estimated by Rambøll s (Norway) blasting experience. Sound source levels can vary considerably for a given activity. Louder sources were selected for the model scenarios, so that the resulting underwater sound estimates are likely to be similar to or higher than those actually generated. However, actual levels of underwater sound generated during blasting could be higher if particularly larger explosives are used and/or a different drilling depth is used. The construction plan (Supplerende oplysninger i forbindelse med udarbejde af VVM-redegørelse, INUPLAN, ) estimated that there will blasting needed to remove approximately 4,000 m3 for deepening along the south end of the planned pier front. The blasting material has been assumed to be Anfo or Dynomite (Ny containerhav på Qeqertat, INUPLAN A/S, ). Baset on this information and drawings of the planned areas and depth where deepening of the harbour is needed, has Rambølls blasting experience (Rambøll Norway) estimated that a single blast using approximately 54 kg of explosive material drilled to a depth 10m would be enough. The amount of blast energy that transfers into the water would be equivalent to 6 kg explosives in open water (Memo. Undervannssprengning for ny havn, Nuuk Havn. Vurdering av innborede ladninger i berg sin andel til sjokk og støy i vann. Rambøll Norway (SVB-Consult), ) Figure 3-1 Planned excavation areas 3.2 Source level Explosive charge detonations generate impulsive acoustic events. There is a zone in the immediate vicinity of the blast that is dominated by non-elastic strain, fracture, and bulk material transport within the medium. At some distance from the blast, the acoustic overpressure has sufficiently dissipated so that the medium can retain its integrity and respond elastically to the overpressure disturbance; at greater distances the propagation is described well by linear compressional and shear wave theory. Impulsive acoustic events are characterized by broad frequency band energy. However, as sound propagates away from the source certain frequencies become attenuated (diminished in amplitude) with distance more quickly than others. Measured sound spectrum data from underwater blasting (Kjellsby, 1993) was used to calibrate the source

8 UNDERWATER NOISE FROM BLASTING 8 frequency spectrum. Sound propagation models can predict the frequency dependence of attenuation. Sound modelling was performed in in 1/3-octave frequency bands with centre frequencies between 10 Hz and 2 khz. In order to obtain an equivalent source level at 1 m from the source, for the purpose of acoustic propagation modelling, we back-propagated the pressure field according to cylindrical spreading loss, or 10 log(r). The purpose of the back-propagation step is to determine the effective source level at 1 m that is used to initialize the forward acoustic propagation model. The peak overpressure source level in the substrate was 267 db re 1 1 m. This source level would have to be adjusted for charge masses different than specified here. 280 Source spectrum (far field signature) Peak sound pressure level (db re. 1µPa) Source spectrum , , /3 Octaveband center frequencies (Hz.) Figure 3-2: Frequency source spectrum of blasting far field signature.

9 UNDERWATER NOISE FROM BLASTING 9 4. MODELING METHODOLOGY Based on source location and underwater source sound level, the acoustic field at any range from the source is estimated using an acoustic propagation model. Sound propagation modelling uses acoustic parameters appropriate for the specific geographic region of interest, including the expected water column sound speed profile, the bathymetry, and the bottom geoacoustic properties, to produce site-specific estimates of the radiated noise field as a function of range and depth. The acoustic model is used to predict the directional transmission loss from source locations corresponding to receiver locations The received level at any 3-dimensional location away from the source is calculated by combining the source level and transmission loss, both of which are direction dependent. Underwater acoustic transmission loss and received underwater sound levels are a function of depth, range, bearing, and environmental properties. The output values output by the model may be used to compute or estimate specific noise metrics relevant to safety criteria filtering for frequency-dependent marine mammal hearing capabilities. 4.1 Sound Propagation Model Underwater sound source levels are used as input for the Ramboll s acoustic propagation program, which computes the sound field as a function of range, depth, and bearing relative to the source location. Rambolls acoustic underwater sound propagation program uses a version of the widely-used Range Dependent Acoustic Model, AcTUP/RAM (Collins et al., 1996). RAM is based on the parabolic equation method using the split-step Padé algorithm to efficiently solve range-dependent acoustic problems. AcTUP/RAM assumes that outgoing energy dominates over scattered energy, and computes the solution for the outgoing wave equation. An approximation is used to provide two-dimensional transmission loss values in range and depth, i.e., computation of the transmission loss as a function of range and depth within a given radial plane is carried out independently of neighbouring radials (reflecting the assumption that sound propagation is predominantly away from the source). AcTUP/RAM has been included to model (to a first approximation) shear wave conversion at the sea floor; the model uses the equivalent fluid complex density approach of Zhang and Tindle (1995). For reflection from the sea-surface, it is assumed that the surface is smooth (i.e., reflection coefficient with a magnitude of -1). While a rough sea surface would increase scattering (and hence transmission loss) at higher frequencies, the scale of surface roughness is insufficient to have a significant effect on sound propagation at the lower frequencies where most of the energy is. The received underwater sound levels at any location within the region of interest are computed from the ⅓-octave band source levels by subtracting the numerically modelled transmission loss at each ⅓-octave band centre frequency and summing across all frequencies to obtain a broadband value. For this study, transmission loss and received levels were modelled for ⅓-octave frequency bands between 10 and 2000 Hz. Because the source of underwater noise considered in this study are predominantly low-frequency sources, this frequency range is sufficient to capture essentially all of the energy output. The received levels are converted to all the applicable underwater acoustic parameters identified in Section 2.

10 UNDERWATER NOISE FROM BLASTING BATHYMETRY AND ACOUSTIC ENVIRONMENT 5.1 Bathymetry The relief of the sea floor is an important parameter affecting the propagation of underwater sound, and detailed bathymetric data are therefore essential to accurate modelling. A base-level-resolution bathymetric dataset for the entire study area was obtained from the Bathymetrisk undersøgelse ved Ny Atlanthavn, Nuuk (2012) and public domain chart data. Figure 5-1 Bathymetry of Nuuk fjord (Godthåbsfjord)

11 UNDERWATER NOISE FROM BLASTING 11 Figure 5-2: Nuuk harbour bathymetry and sea chart

12 UNDERWATER NOISE FROM BLASTING Geoacoustic Properties Based on seabed information gathered from the Refleksionsseismisk undersøgelse ved Ny Atlanthavn, Nuuk (2012), has a seabed acoustic profile been derived and used for the modeling. The layers used in the modelling and the main parameters are depicted in Table 5-1Fejl! Henvisningskilde ikke fundet.. Seabed layer (m) Material Geoacoustic property 5 10 Mud and clay C p = 1600 m/s α = 0.2 db/λ Ρ = 1.80 g/cm Glacial deposits and coarse sediments C p = 2000 m/s α = 1.05 db/λ Ρ = 1.80 g/cm 3 Table 5-1. Overview of seabed geoacoustic profile used for the modelling (C p = compressed wave speed, α = compressional attenuation, p = density). 5.3 Sound Speed Profiles Water column sound speed profiles (SSPs) for the survey area were computed from temperature and salinity profiles gathered from the Greenland Climate Research and used for the modeling. The SSPs used in the modelling and the main parameters are depicted in Figure Sound speed in water (m/s) Water depth (m) Figure 5-3. Water column sound speed profiles.

13 UNDERWATER NOISE FROM BLASTING MODEL RESULTS 6.1 Sound propagation The sound propagation model was run with the model scenario, source levels, and environmental parameterization described in Sections 3 and 5. The levels depicted at each location are the maximum predicted level for that location at any depth down to the bottom. Table 6-1summarize the results of the acoustic modelling in terms of the underwater sound levels of each specific acoustic metric for the maximum distances ranging from 50 meters to over 25 km. Radii are presented both without frequency weighting and for M-weightings corresponding to low-, mid-, and high-frequency cetaceans and to pinnipeds in water. There is significant sound transmission through the sea bottom as well as through the water. Because the peak in the source spectrum occurs at a lower frequency the reduction in radii associated with the application of M-weightings for mid- and high-frequency cetaceans is more significant. Distance (m) Total (0-Peak) db Total (rms SPL) db Total Unweighted (SEL) db Weighted HFC (SEL) db MFC (SEL) db LFC (SEL)dB Pinnipeds (SEL) db Table 6-1: Estimated maximum radii (m) versus underwater sound levels (db) from the blast in Nuuk Harbour. Figure 6-1 show the noise maps for the un-weighted underwater sound exposure levels (SEL) to 180 db from the blast in Nuuk Harbour. It can be seen that the sound is not spreading omnidirectional due to the interactions with the bathymetry, shoreline and islands.

14 UNDERWATER NOISE FROM BLASTING 14 Figure 6-1: un-weighted underwater sound exposure levels (SEL) from the blast in Nuuk Harbour.

15 UNDERWATER NOISE FROM BLASTING IMPACT ASSESSMENT 7.1 Fish Impacts to fish focus on physical damage and behavioural changes. Fish behaviour in response to noise is not well understood. Sound pressure levels that may deter some species, may attract others. In fish, physical damages to the hearing apparatus rarely lead to permanent changes in the detection threshold (permanent threshold shift, PTS), as the damaged sensory epithelium will regenerate in time (Smith et al 2006, Song et al 2008). However, temporary hearing loss may occur (Popper et al 2006). The sound intensity is an important factor for the degree of hearing loss, as is the frequency, the exposure duration, and the length of the recovery time. There is little information available on the hearing abilities of species of particular relevance for the survey area; Atlantic cod and Atlantic herring therefore serve as models for other fish species (Halvorsen et al 2011). The criteria for PTS and TTS are presented in section Marine Mammals Generally, the effect of noise on marine mammals can be divided into four broad categories that largely depend on the individual s proximity to the sound source: Detection Masking Behavioural changes Physical damages The limits of each zone of impact are not sharp, and there is a large overlap between the zones. The four categories are described below, based on Southhall et al Detection ranges depend on background noise levels as well as hearing thresholds for the animals in question. Masking is an impact where repeated or long-term underwater sound masks e.g. communication between individuals. Masking is not considered an issue in relation to the Nuuk Harbour underwater blasting. Behavioural changes are difficult to evaluate. They range from very strong reactions, such as panic or flight, to more moderate reactions where the animal may orient itself towards the sound or move slowly away. However, the animals reaction may vary greatly depending on season, behavioural state, age, sex, as well as the intensity, frequency and time structure of the sound causing behavioural changes (Southhall et al 2007). Physical damage to marine mammals relate to damage to the hearing apparatus. Physical damages to the hearing apparatus may lead to permanent changes in the animals detection threshold (permanent threshold shift, PTS). This can be caused by the destruction of sensory cells in the inner ear, or by metabolic exhaustion of sensory cells, support cells or even auditory nerve cells. Hearing loss is usually only temporary (temporary threshold shift, TTS) and the animal will regain its original detection abilities after a recovery period. For PTS and TTS the sound intensity is an important factor for the degree of hearing loss, as is the frequency, the exposure duration, and the length of the recovery time. The criteria for PTS, TTS and behavioural response are presented in section 7.3. Note that for a single pulse such as blasting, the criteria for TTS and behavioural response are the same (Southhall et al 2007).

16 UNDERWATER NOISE FROM BLASTING Marine Mammal and Fish Criteria Table 7-1 summarizes criteria for assessing impacts to fish and marine mammal. The criteria are associated with different impacts (e.g. PTS, TTS and behavioural), as described in section 7.1 and 7.2. Auditory bandwidth 75 Hz to 22 khz 75 Hz to 22 khz 75 Hz to 22 khz 200 Hz to 180 khz 150 Hz to 160 khz 7 Hz to 22 khz 7 Hz to 22 khz 7 Hz to 22 khz Criteria PTS (Single pulse) TTS (Single Pulse) Behavioural response L p (SPL) db re: 1µPa L ae (SEL) db re: 1µPa 2 -s L p (SPL) db re: 1µPa L ae (SEL) db re: 1µPa 2 -s Fish Fisk 187 db 206 db Scientific name Danish name Functional hearing group Seals Phoca hispida Ringsæl Pinnipeds in water Phoca Grønlands Pinnipeds in groenlandica sæl water Cystophora Klapmyds Pinnipeds in cristata water Whales Phocoena Marsvin high phocoena frequency Physeter Kaskelot midfrequency macrocephalus Megaptera Pukkelhval Lowfrequency novaeanglia Balaenoptera Vågehval Lowfrequency acutorostrata Balaenoptera Finhval Lowfrequency physalus (0- peak) Table 7-1: Criteria applied in the impact assessment. Marine mammals criteria from Southhall et al 2007, fish criteria from Halvorsen et al Note: The peak SPL criterion is un-weighted (i.e., flat weighted), whereas the SEL criterion is M-weighted for the given marine mammal functional hearing group

17 UNDERWATER NOISE FROM BLASTING Impacts to fish and marine mammals Table 7-2 summarize the results of the acoustic modelling in terms of the underwater sound levels of the maximum distance from the blast to each specific underwater noise impact thresholds identified for the types of marine life in the area. Marine mammal and fish noise exposure criteria used in the quantitative assessment (PTS = Permanent threshold shift; a permanent elevation of the hearing threshold in certain frequencies. TTS = Temporary threshold shift; a temporary elevation of the hearing threshold in certain frequencies). Seals Scientific name Danish name Frequencyweighting network Distance to criteria Derived from noise propagation modelling, PTS (Single pulse) meters TTS (Single Pulse) L p (SPL) L ae (SEL) L p (SPL) L ae (SEL) Phoca hispida Ringsæl M pw 120 m 1200 m 250 m m Phoca groenlandica Grønlandssæl M pw 120 m 1200 m 250 m m Cystophora cristata Klapmyds M pw 120 m 1200 m 250m m Whales Phocoena phocoena Marsvin M hf 20 m 80 m 70 m 550 m Physeter macrocephalus Kaskelot M mf 20 m 150 m 70 m 700 m Megaptera novaeanglia Pukkelhval M lf 20 m 500 m 70 m 7000 m Balaenoptera acutorostrata Vågehval M lf 20 m 500 m 70 m 7000 m Balaenoptera physalus Finhval M lf 20 m 500 m 70 m 7000 m Fish Fisk none 3500 m 4000 m Table 7-2: Maximum distance from the blast to each specific underwater noise impact thresholds identified for the types of marine life in the area. Note: The peak SPL criterion is un-weighted (i.e., flat weighted), whereas the SEL criterion is M-weighted for the given marine mammal functional hearing group

18 UNDERWATER NOISE FROM BLASTING MITIGATING MEASURES In practice, various approaches may be used to reduce the impact for a given overall explosive charge, including sub-dividing a large charge into a series of smaller, time-delayed charges or using additional mitigation measures such as bubble curtains (Wright and Hopky, 1998). 8.1 Bubble curtains Bubble curtains are commonly used to reduce acoustic energy emissions from high-amplitude sources. Bubble curtains can be generated by releasing air through multiple small holes drilled in a hose or manifold deployed on the seabed near the source. The resulting curtain of small air bubbles in the water provides significant attenuation for sound waves propagating through the curtain. The bubble curtain is often use as a mitigation choice for underwater pile driving and blasting activities at construction sites. Research has been performed to quantify the effectiveness of bubble curtains at attenuating impulsive sounds (eg. Koschinski & Kock, 2009; Schmidtke, 2010; Nützel, 2008). Nützel (2008) established that the reduction of peak pressures of explosion shockwaves depends on the air flow rate. An average of 15.4 db decrease in the peak pressure was measured with the bubble curtain air flowrate of 20 m 3 /min. In another experiment with 25 charges (Grunau (2008)) estimated the reduction of the peak pressure of the shock wave by as much as 17 db Sound propagation The effect of a bubble curtain was included in the modelling results by applying a flat reduction of 15 db (average of the above-listed attenuations) to the non-mitigated source levels. Table 8-1 summarize the results of the acoustic modelling in terms of the underwater sound levels, with a bubble curtain, of each specific acoustic metric for the maximum distances ranging from 50 meters to over 25 km. Radii are presented both without frequency weighting and for M-weightings corresponding to low-, mid-, and high-frequency cetaceans and to pinnipeds in water. Distance Total(0- Total Total Weighted (m) Peak) db (rms Unweighted (SEL) db SPL) (SEL) db HFC MFC LFC Pinnipeds Table 8-1: Estimated maximum radii (m) versus underwater sound levels (db) from the blast WITH BUBBLE CURTAIN in Nuuk Harbour. Weighted columns are based on Table 2-1.

19 UNDERWATER NOISE FROM BLASTING 19 Figure 8-1 shows the noise maps for the un-weighted underwater sound exposure levels (SEL) to 180 db from the blast with a bubble curtain in Nuuk Harbour. It can clearly be seen the reduced area of noise SEL over 180 db comparing to the area without the bubble curtain (Figure 4). Figure 8-1. With bubble curtain un-weighted underwater sound exposure levels (SEL) from the blast in Nuuk Harbour Impacts to fish and marine mammals The impacts to fish and marine mammals were evaluated based on the noise modelling, and the criteria presented in section 0. The maximum distance from the blast to each specific underwater noise impact threshold are presented in Table 8-2.

20 UNDERWATER NOISE FROM BLASTING 20 Scientific name Danish Functional Frequenc Distance to criteria name hearing y- Derived from noise propagation group weightin modelling, meters g network PTS (Single TTS (Single pulse) Pulse) Seals Phoca hispida Ringsæl Pinnipeds in water Phoca groenlandica Grønlandsæl Pinnipeds in water Cystophora cristata Klapmyds Pinnipeds in water Whales L p L ae L p L ae (SPL) (SEL) (SPL) (SEL) M pw na 100 m 150 m 1000 m M pw na 100 m 150 m 1000 m M pw na 100 m 150 m 1000 m Phocoena phocoena Marsvin high frequency M hf na Na Na 50 m Physeter macrocephalus Megaptera novaeanglia Balaenoptera acutorostrata Balaenoptera physalus Kaskelot mid-frequency M mf na Na Na 50 m Pukkelhval Low-frequency M lf na 70 m Na 500 m Vågehval Low-frequency M lf na 70 m Na 500 m Finhval Low-frequency M lf na 70 m Na 500 m Fish Fisk none 500 m 300 m Table 8-2: With Bubble Curtain, maximum distance from the blast to each specific underwater noise impact thresholds identified for the types of marine life in the area. Note: The peak SPL criterion is unweighted (i.e., flat weighted), whereas the SEL criterion is M-weighted for the given marine mammal functional hearing group As is evident, the potential impacts to marine mammals can be significantly reduced by applying the bubble curtain. Further mitigating measures may also be applicable, as detailed below. 8.2 Other mitigating measures The timing of the blast is integral to the impact assessment. The majority of the marine mammals encountered in the area are migratory, and it is thus possible to adjust the blasting to avoid periods where mammals are abundant or nursing. Several international guidelines address mitigating measures in connection with underwater noise. Agreement on the Conservation of Small Cetaceans of the Baltic and North Seas dated 31/03/1992 (ASCOBANS), suggest several steps to mitigate the impacts to marine mammals. Use of observers to ensure that no marine mammals are within a safety zone at the start of blasting and to ensure that blasting is aborted. Soft start procedure, a method of gradually increasing the sound intensity at the start of the operation, so mammals are scared away from the blasting spot.

21 UNDERWATER NOISE FROM BLASTING REFERENCES Codispoti, L.A., Kravitz, J.H., Collins, M.D., Oceanographic Cruise Summary, Baffin Bay-Davis Strait- Labrador Sea, Summer Informal rept. 3 Sep-14 Oct 1967 Naval Oceanographic Office NSTL Station, MS Collins, M. D A split-step Pad e solution for the parabolic equation method. The Journal of the Acoustical Society of America, 93(4), Duncan, A.J., Maggi, A.I., A Consistent, user friendly Interface for Running a Variety of Underwater Acoustic propagation Codes. Proceedings of ACOUSTICS Fisher, F.H. and V.P. Simmons Absorption of sound in sea water. J. Acoust. Soc. Am. 62: Hage, T., 2013 Undervannsprengining for Nuuk Havn. Vurdering av inneborede ladninger i berg san andel til sjokk og støy i vann. (unpublished correspondance) Halvorsen, M.B., Casper, B.M., Woodley, C.M., Carlson, T.J., Popper, A.N., Predicting and mitigating hydroacoustic impacts on fish from pile installations. NCHRP Research Results Digest 363, Project 25-28, National Cooperative Highway Research Program, Transportation Research Board (available at National Academy of Sciences, Washington. Henriksen, N., Higgins, A.K., Kalsbeek, F., Christopher; T., Pulvertaft, R., Greenland from Archaean to Quaternary Descriptive text to the Geological map of Greenland, 1: Geology of Greenland Survey Bulletin(185), Jensen, F.B., Kuperman, W.A., Porter, M., B.,, Schmidt, H., Computational Ocean Acoustics, Second Edition Springer, New York, Dordrecht, Heidelberg, London. Johnsen, J Acoustic exposure of fish from underwater explosions, Norweigian Defence Reseach Establishment. Koschinski, S. & Kock, K.-H. (2009). Underwater Unexploded Ordnance Methods for a Cetacean-friendly Removal of Explosives as Alternatives to Blasting. International Whaling Commission. Scientific Committee Paper SC/61/E21 Kyhn, L.A., Boertmann, D., Tougaard, J., Johansen, K., Mosbech, A., Guidelines to environmental impact assessment of seismic activities in Greenland waters. Danish Centre for Environment and Energy, Roskilde. Nauta, Martin R., Refleksionsseismisk undersøgelse ved Ny Atlanthavn, Nuuk 2012 for Inuplan A/S Nauta, Martin R., Bathymetrisk undersøgelse ved Ny Atlanthavn, Nuuk 2012 for Inuplan A/S Nedwell, J.R. and A.W. Turnpenny The use of a generic frequency weighting scale in estimating environmental effect.. Workshop on Seismics and Marine Mammals 23 25th June, London, U.K. Nedwell, J.R., A.W.H. Turnpenny, J. Lovell, S.J. Parvin, R. Workman, J.A.L. Spinks, and D. Howell A validation of the db ht as a measure of the behavioural and auditory effects of underwater noise. 534R1231 prepared by Subacoustech Ltd for the U.K. Department of Business, Enterprise and Regulatory Reform under Project No. RDCZ/011/0004. Nützel, B. (2008). Untersuchungen zum Schutz von Schweinswalen vor Schockwellen. Technischer Bericht TB Forschungsanstalt der Bundeswehr für Wasserschall und Geophysik (FWG). Kiel. 18 pp. Popper, A. N., Smith; M. E., Cott, P. A., Hanna, B. W., MacGillivray, A. O., Austin, M. E., Mann, D. A Effects of exposure to seismic airgun use on hearing of three fish species. J. Acoust. Soc. Am. 117(6): Schmidtke, E (2010). Schockwellendämpfung mit einem Luftblasenschleier zum Schutz der Meeressäuger. Smith, M. E., Coffin, A. B., Miller, D. L., Popper, A. N Anatomical and functional recovery of the goldfish (Carassius auratus) ear following noise exposure. J. Exp. Biol. 209: Song, J., Mann, D. A., Cott, P. A., Hanna, B. W., Popper, A. N The inner ears of Northern Canadian fishes following exposure to seismic airgun sounds. J. Acost. Soc. Am. 124(2): Southall, B.L., Bowles, A.E., Ellison, W.T., Finneran, J.J., Gentry, R.L., Greene, C.R.J., Kastak, D., Ketten, D.R., Miller, J.H., Nachtigall, P.E., Richardson, W.J., Thomas, J.A., Tyack, P., Marine mammal noise exposure criteria: initial scientific recommendations. Aquatic Mammals 33,

22 UNDERWATER NOISE FROM BLASTING 22 Wahlberg, M A review of the literature on acoustic herding and attraction of fish. Fiskeriverket rapport 1999(2) : 5-44.