NMFS has issued the IHA to Rutgers et al:

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For divers in the area of the operating airgun array:

UNDERWATER NOISE AND THE CONSERVATION OF DIVERS' HEARING: A REVIEW Volume I October 1989

In conclusion, the combined evidence of our work and these two other suprathreshold investigations strongly suggest that the current underwater sound pressure level exposure limits are invalid and err on the unsafe side by significant amounts.

http://www.dtic.mil/dtic/tr/fulltext/u2/a220935.pdf


Limits for underwater noise exposure of human divers and swimmers Steve Parvin

Summary

Bio-effects of low frequency underwater sound (100 to 500 Hz)
SPL
dB re.1 μPa
Effect
100 to 500 Hz
184 +
Based on animal models liver haemorrhage and soft tissue damage are likely.
170+
Tolerance limit for divers and swimmers. Sound causes lung and body vibration.
148 -157
The loudness and vibration levels become increasingly aversive. Some divers will contemplate aborting an open water dive.
140 -148
A small number of divers rate the sound as ‘very severe.
136 -140
The sound is clearly audible. The majority of divers tolerate the sound well with only “Slight” aversion.
130
Divers and swimmers able to detect body vibration
80 -100
Auditory Threshold
(SPL = Sound Pressue Level)


Guidance

Recreational divers and swimmers
[TABLE="align: center"]
[TR]
[TD]Frequency range
[/TD]
[TD]100 – 500 Hz
[/TD]
[TD]501 – 2500 Hz
[/TD]
[/TR]
[TR]
[TD]SPL (dB re. 1 mPa)
[/TD]
[TD]145
[/TD]
[TD]155
[/TD]
[/TR]
[/TABLE]

Parvin S J, Cudahy E A and Fothergill D M. “Guidance for diver exposure to underwater sound in the frequency range from 500 to 2500 Hz. Proceedings of Undersea Defence Technology, La Spezia, Italy, 2002.

http://www.subacoustech.com/wp-content/uploads/NPLDiverNoisePresentation.pdf



Recreational scuba divers' aversion to low-frequency underwater sound

D. M. FOTHERG1LL, .1. R. SIMS, and M. D. CURLEY
Our data suggest that LFS exposures up to 145 dB re I µPa at frequencies between 100 and 500 Hz will have minimal impact on the recreational diver.

As a conservative measure, the consensus decision of scientists involved in the LFS program was that the maximal SPL intensity for the guidance should be set at 145 dB re 1 µPa (20).

Copyright C 2001 Undersea and 1 lyperbaric Medical Society, Inc.

(LFS= low-frequency underwater sound)

http://archive.rubicon-foundation.org/xmlui/bitstream/handle/123456789/2368/11732884.pdf?sequence=1


Safe Diving Distance from Seismic Surveying Operations

DMAC 12 Rev. 1 – July 2011 Supersedes DMAC 12 which is now withdrawn

Background


Guidance Note DMAC 012 was issued in 1979 after consideration of the knowledge concerning the effects of seismic operations on divers in the water at that time. Over the last 30 years DMAC has discussed this guidance on a number of occasions and attempted to gain further knowledge from reports of diver/seismic operation interaction. Some of the few available reports have added to our knowledge.

1 Seismic airgun activity results in the transmission of acoustic waves through the water which the diver experiences as a noise analogous to a piling hammer. Multiple reflections of this acoustic wave from the sea surface, seabed and other structures may result in this sounding like a low frequency rumble.

2 The intensity of the sound experienced by the diver is principally dependent on the power of the seismic airgun array and the distance between the diver and the seismic airgun, but other factors may have important effects. These factors include the water depth at which the seismic activity takes place, the presence of thermoclines (layering due to changes in temperature), the depth of the diver versus the depth of the thermocline, bottom conditions, salinity and the sea state.

3 Not all seismic surveys are the same (e.g. ocean bottom cable surveys (OBC), streamer(s), vertical seismic profile surveys (VSP), site surveys, etc.) and there are differences in the types and purpose of source arrays used around the world, e.g. airguns, boomers, sparkers, etc.

4 The multiple factors involved make it difficult to determine a safe or tolerable distance, particularly in shallow water, without performing communication exercises between seismic and diving operations.

5 The duration of a diver’s exposure may limit tolerance.

Guidance

1 Where diving and seismic activity will occur within a distance of 10 kilometres, a joint risk assessment should be conducted, between the operators involved and the seismic and diving contractors in advance of any simultaneous operations.

2 Where possible, plans should be made to avoid overlapping seismic and diving activities. Where this is not possible, the activities should be prioritised and a simultaneous operations (SIMOPS) plan developed.

3 The parties should perform a communication exercise or test at the start of simultaneous operations to determine the acceptable safe distance for the local conditions. Starting at a distance of 10 kilometres, the seismic source array will be gradually ramped up, and the seismic vessel gradually moved closer to the diving operation, with constant communication between the diving supervisor and the seismic party manager. (Note: seismic source ramp ups are now the industry standard in all situations.)

4 The minimum safe distance, as determined from the testing outlined above, should not be compromised by either party.

5 There should be regular contact (at least daily) between the seismic vessel and diving vessel so that both are aware of each other’s work program for the day.

http://www.dmac-diving.org/guidance/DMAC12.pdf

10 kilometers = 6.21371192 miles = 5.39956803 nautical miles


Acoustically enhanced bubble growth at low frequencies and its implications for human diver and marine mammal safety

(Lawrence A. Crum and Yi Maoa)

In general, it was discovered that relatively large SPL’s are required to induce rapid or significant ~and thus dangerous! gas bubble growth, unless the degree of dissolved gas supersaturation was quite large. Under normal conditions, enhanced diffusion produced by sonars and other high intensityacoustic projectors pose little risk to divers and marine mammals unless they are in the immediate vicinity of the source. However, the ‘‘contraindications’’ for their use are as follows:

(1) If the local SPL at the site of the diver or marine mammal is in excess of 210 dB ~re:1µPa!, gas bubble growth is predicted to occur within a period of a few seconds. Furthermore, bubble growth to sizes large enough to block capillaries and other small blood vessels is expected with its associated bioeffects.

(2) If a diver, breathing compressed gas, experiences rapid depth ascents such that the local body fluid is supersaturated with gas, considerably lower SPL’s may result in conditions favorable for bubble growth.

http://www.thecre.com/sefReports/wp-content/uploads/2012/12/Crum-L.A.-Mao-Y.-1996.-Acoustically.pdf


Far-field Measurements of Seismic Airgun Array Pulses in the Nova Scotia Gully Marine Protected Area

CONCLUSIONS

From this study, several conclusions can be drawn:

• The highest average sound pressure level (RMS) measured in the Gully MPA was 145 dB re 1μPa at 90 m depth, 50 km from the seismic array. This sound level was measured within the Gully Whale Sanctuary while the seismic vessel was surveying the western portion of the exploration block. It was estimated that sound levels in the Whale Sanctuary would have been higher, between approximately 153 and 157 dB, when the vessel was at its closest approach to the Gully in the eastern portion of the survey block. The “worst case” sound level at the Gully MPA boundary, i.e., 0.8 km from the source, can be estimated from the extrapolation of near-field measurements in Austin and Carr (2005) to be approximately 178 dB, 14 dB higher than predicted in Moulton et al. (2003).

http://www.dfo-mpo.gc.ca/Library/319590.pdf
 
NMFS issues the IHA to provide authorization to disturb marine mammals (non-lethal take) to applicant. It gives you an authorization harassment of marine mammals which would otherwise be prohibited under the marine mammal protection act.

Since this does not involve geological and geophysical surveys for mineral deposits, no government license or permit is needed.

An environmental assessment is not a permitting document, it is an analysis of reasonably foreseeable environmental consequences of a proposed action. That is the reason that effects to divers is contained in the effects section along with impacts to commercial fishing. It is not really germane to an IHA which does not concern itself with humans-as-marine-mammals.

As I recall (and I could be wrong), the level of exposure for divers discussed in the programmatic environmental impact assessment was established at 145 db (keep in mind, this is the sound level in the water, not air).

I analyzed this issue for oil and gas industry permits in California about 15 years ago. There were a pretty robust set of mitigations involved as conditions of permit approval, from communications with dive shops, notices at beach entry points, Notices to mariners, because it was possible to ensonify the area used by beach divers in addition to divers from private boats and charter boats. I think at the time we were using a 150 db threshold for divers, based on the recommendations from the Nato Undersea Lab protocols.
 
Last edited:
Draft Amended Environmental Assessment of a
Marine Geophysical Survey
by the R/V
Marcus G. Langseth
in the Atlantic Ocean off New Jersey,
Summer 2015

Here are the only statements on recreational SCUBA diving:

(Snip)

Socioeconomic and Environmental Justice—Implementation of the proposed Project would not affect, beneficially or adversely, socioeconomic resources, environmental justice, or the protection of children. No changes in the population or additional need for housing or schools would occur. Because of the location of the proposed activity and distance from shore, human activities in the area around the survey vessel would be limited to SCUBA diving, commercial and recreational fishing activities and other vessel traffic. Fishing, SCUBA diving, vessel traffic, and potential impacts are described in further detail in §§ III and IV.

Page 10.


(Snip)

Recreational SCUBA Diving

Wreck diving is a popular form of recreation in the waters off New Jersey. A search for shipwrecks in New Jersey waters was made using NOAA’s automated wreck and obstruction information system (NOAA 2014a). Results of the search are plotted in Figure 2 together with the survey lines. There are over 900 shipwrecks/obstructions in New Jersey waters, most (58%) of which are listed by NOAA (2014b) as unidentified. Only one shipwreck, a known dive site, is in or near the survey area (Fig. 2): the Lillian (Galiano 2009; Fisherman’s Headquarters 2014; NOAA 2014a).

Page 32.


(Snip)

(5) Direct Effects on Recreational SCUBA Divers and Dive Sites and Their Significance

No significant impacts on dive sites, including shipwrecks, would be anticipated. Airgun sounds would have no effects on solid structures. The only potential effects could be temporary displacement of fish and invertebrates from the structures.

Significant impacts on, or conflicts with, divers or diving activities would be avoided through communication with the diving community before and during the survey and publication of a Notice to Mariners about operations in the area. In particular, dive operators with dives scheduled on the shipwreck Lillian during the survey would be contacted directly. That dive site represents only a very small percentage of the recreational dive sites in New Jersey waters. No dive vessels were observed in the survey area during the ~14 days that the Langseth was there in July 2014.

Page 54.


(Snip)

Here is the only mention of a 145 db re 1 μPa level:

Thompson et al. (2013) reported decreased densities and reduced acoustic detections of harbor porpoise in response to a seismic survey in Moray Firth, Scotland, at ranges of 5–10 km (SPLs of 165–172 dB re 1 μPa, SELs of 145–151 dB μPa2 · s); however, animals returned to the area within a few hours.

Page 40.

(Snip) = Irrelevant material deleted.

http://www.nsf.gov/geo/oce/envcomp/amended_mountain_nj_margin_ex_draft_18dec14-b.pdf
 
The level and detail of discussion of potential effects looks about right. A level of 150 db would be realized approximately 1.35 nautical miles from the source, more or less. The shipwreck is the only known diving location in the area of the proposed action, so it appears that the step taken to avoid or reduce effects are sufficient.
 
I am reading NJDIVER1's thread with interest.
Although NJDIVER1's hostility to this kind of oceanography is clear from his past posts, he has a point. Embedded in the discussion of seismic impacts is a statement that somehow the diving community will be formally notified that the R/V Langseth will be working in an area over one wreck, the Lillian. How will divers be informed of safe distance during that. The question can be turned to NJDIVER: what can you do to make sure divers, who might be affected, are properly informed? I do not have information suggesting you have contacted the scientists to help work this out. Have you done so? Do you need some contact numbers?

---------- Post added May 17th, 2015 at 04:24 PM ----------

Your attitude is such that you would not take my word for anything, so do the research yourself. And would you dive in the area they are to be operating in during the times they have stated? If so, how close?

It seems you were asked a simple question.
 
This is normally handled by the Captain of the vessel that is taking the divers to the possibly-affected wreck. That Captain is obliged to check the Notices to Mariners. And, of course, that Notice has to be issued. Njdiver1 assumes the system will break down, apparently through malice somewhere along the line. It is not clear why he thinks that. And it is not clear that -- even if it breaks down -- any harm will be caused.
 
For divers in the area of the operating airgun array:

NJDIVER1, here is an article about Attenuation, meaning the physics about the gradual loss in intensity of any kind of flux through a medium. The source, Norwood Resource, is an oil & gas industry page, but the issue of sound in the water column applies to any unrelated seismic study, such as that of Rutgers' oceanographers. It is from correspondence with the author of this article, John Hughes, that I learn that sound in shallow water approaching shore attenuates sufficiently rapidly that a diver at the near-shore artificial reefs such as Axel Carlson would probably not notice the sound of the Langseth.

If your persistence on this question is genuine curiosity, and not (as it appears) a desire to find ways to derail the Rutgers project, I suggest you contact Hughes at Norwood.



How quickly does sound attenuate in water?
 
Lamont-Doherty and NSF Seismic Survey in the NW Atlantic Ocean offshore NJ, Summer 2015

[TABLE="class: MsoNormalTable, width: 80%"]
[TR]
[TD="width: 20%"]
Status
[/TD]
[TD="width: 20%"]
Public Comment Period
[/TD]
[TD="width: 20%"]
Issued Date
[/TD]
[TD="width: 20%"]
Effective Dates
[/TD]
[/TR]
[TR]
[TD="width: 20%, bgcolor: transparent"]
ACTIVE
[/TD]
[TD="width: 20%, bgcolor: transparent"]
closed
[/TD]
[TD="width: 20%, bgcolor: transparent"]
05/07/15
[/TD]
[TD="width: 20%, bgcolor: transparent"]
06/01/2015 - 08/31/2015
[/TD]
[/TR]
[/TABLE]
SUMMARY: We have issued an IHA to Lamont-Doherty Earth Observatory, in collaboration with the National Science Foundation, and Rutgers University to take, by Level B harassment only, marine mammals, incidental to conducting a marine seismic survey in the northwest Atlantic Ocean off the New Jersey coast in summer 2015.

Incidental Take Authorization Documents:
· IHA Application [pdf]
· Federal Register notice of Proposed IHA
· References [pdf]
· Public Comments [pdf]
· Issued IHA[pdf]
· Federal Register notice of Issued IHA

Environmental Analyses:
· National Science Foundation's 2014 Draft Amended EA [pdf]
· NSF's 2014 Final EA [pdf]
· NMFS' 2015 EA [pdf]
· NMFS' FONSI [pdf]

http://www.nmfs.noaa.gov/pr/permits/incidental/research.htm#nj2015
 
Lamont-Doherty and NSF Seismic Survey in the NW Atlantic Ocean offshore NJ, Summer 2015

[TABLE="class: MsoNormalTable, width: 80%"]
[TR]
[TD="width: 20%"]
Status
[/TD]
[TD="width: 20%"]
Public Comment Period
[/TD]
[TD="width: 20%"]
Issued Date
[/TD]
[TD="width: 20%"]
Effective Dates
[/TD]
[/TR]
[TR]
[TD="width: 20%, bgcolor: transparent"]
ACTIVE
[/TD]
[TD="width: 20%, bgcolor: transparent"]
closed
[/TD]
[TD="width: 20%, bgcolor: transparent"]
05/07/15
[/TD]
[TD="width: 20%, bgcolor: transparent"]
06/01/2015 - 08/31/2015
[/TD]
[/TR]
[/TABLE]
SUMMARY: We have issued an IHA to Lamont-Doherty Earth Observatory, in collaboration with the National Science Foundation, and Rutgers University to take, by Level B harassment only, marine mammals, incidental to conducting a marine seismic survey in the northwest Atlantic Ocean off the New Jersey coast in summer 2015.

Incidental Take Authorization Documents:
· IHA Application [pdf]
· Federal Register notice of Proposed IHA
· References [pdf]
· Public Comments [pdf]
· Issued IHA[pdf]
· Federal Register notice of Issued IHA

Environmental Analyses:
· National Science Foundation's 2014 Draft Amended EA [pdf]
· NSF's 2014 Final EA [pdf]
· NMFS' 2015 EA [pdf]
· NMFS' FONSI [pdf]

http://www.nmfs.noaa.gov/pr/permits/incidental/research.htm#nj2015
 

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