The European Diving Technology Committee (EDTC), another organisation dedicated to promoting diving standards, is also concerned that safety standards in the offshore wind sector are far less stringent than in the offshore oil and gas sector.
"The companies concerned say there was a tragic accident, or a work place accident, but the real picture seems to be that they aimed to save money by choosing a company offering to do the work the cheapest, but without the necessary know-how and experience," said the Divers Association, which is working to throw more light on the fatalities.
"The association is pressing for full investigations of all three cases on grounds of criminal negligence," the body stressed.
"Such diving accidents simply should not happen," said Claus Mayer, an EDTC executive board member and CEO of diving firm Nordseetaucher. "Our company will get involved in offshore wind when the safety requirements have been raised," he added.
But the authorities appear to be unsure over who is responsible for safety rules in the German offshore sector.
The most recent death was that of British diver Richard Wilkinson-Lowe, aged 26, on 13 July 2013 at the Riffgat site. He was working with diving company RS Diving, off the Union Beaver vessel, which is owned and operated by Dutch-Belgian company URS Salvage and Contracting, according to the Divers Association. Leer and Emden police said on 13 July 2013 that the diver was working at a depth of 20 metres at 4am when a so-called concrete mattress fell on him. The mattresses were being laid to weigh down and fix electricity cables to the sea bed.
Why the diver was so close to the mattress that he could be buried under it is not explained in the police report.
Shortly after the incident, energy firm EWE denied pressure to keep to schedules had played a part in Wilkinson-Lowes' death.
A third organisation, the Federal Bureau of Maritime Casualty Investigation, the BSU, investigates all types of marine accidents to or on board German-flagged ships worldwide. Within German territorial waters, the BSU acts regardless of the flag of the ship involved. Riffgat lies in German territorial waters.
The BSU investigated what happened in Marsaxlokk, Malta, when a Dutch diver died in June 2004 while filming underwater from the German container ship CMA CGM Verlaine. But the BSU told Windpower Monthly in November that it did not investigate the diving deaths at Riffgat and Alpha Ventus because they were not accidents at sea in the sense of "1a" of marine safety law. It was unable to say which authority would be responsible for an investigation.
Prior to the Riffgat case, on 3 May 2012, 48-year-old Steven O'Malley died while working at the Alpha Ventus wind farm. He was working for UK subsea engineering firm SubC, according to the Divers Association, carrying out maintenance work on the upper part of turbine foundations in water depths of just two metres. According to an Alpha Ventus press release, the emergency doctor's provisional diagnosis was a heart attack.
Apart from raising questions over why someone with a risk of heart attack was diving, and whether proper health checks had been carried out, the Divers Association wants clarification on why the diver could not be saved.
The association's Tom Wingen, who has watched the 36-minute video of what happened as recorded by the diver's helmet camera, said O'Malley became distressed four minutes after the dive began, but that it took 14 minutes to get him back on board the vessel, turning what should have been a rescue into a slow body-recovery operation. There was no diving launch-and-recovery system available, Wingen observed.
On the suggestion of the police, he submitted a subtitled video to the Danish Maritime Accident Investigation Board (DMAIB). This is the initial investigating authority, as the diver was working from a Danish vessel, and the wind farm does not lie in German territorial waters but in the German exclusive economic zone.
Series of errors
Back in 2010, the first German offshore wind diver death was of 27-year-old Swedish diver Patrick Costello, who was working at the Bard Offshore 1 wind farm for Swedish company NDE, according to the Divers Association.
The diving operation was carried out from the anchor-handling tug supply ship Maersk Tender. The task was to remove material from the seabed at a depth of 40 metres, using a 20-metre long iron tube (dredger pipe) to which two H girders were fitted and hung by crane down into the water to be lowered to the seabed.
The review of the case by the Danish Division for Investigation of Maritime Accidents, issued in October 2011, describes a long series of failures that played a role in leading to the death. It states that although the diving company presented a written risk assessment, this was a standard version from the firm's management system not one directly addressing anything relating to the diver's safety or a possible rescue effort. In its assessment, the Danish investigation division found the task should have been considered particularly risky.
Other observations in the review include that the general rule not to stand or pass under a suspended load - in this case, the dredger pipe and girders - was disregarded. Further, it was not realised that the diver's umbilical could be trapped between the H-girders and the dredger pipe and therefore no action was taken to avoid it. The umbilical did become trapped between the pipe and a girder, cutting off Costello's air supply and contributing to his death.
Even before the emergency, there was a technical malfunction at the diving control-station air-distribution panel that caused a periodically inadequate air supply for both Costello and his standby diver, which also put the life of the standby diver at risk while trying to aid Costello.
Both Costello and the standby diver appear to have taken supplies from their bailout bottles, and this meant the air was not available for Costello when the emergency occurred.
Costello was also believed to be under the influence of nitrogen narcosis - a temporary alteration in consciousness caused by high pressure gases that occurs when diving at 25-30 metres or deeper - and "could not be expected to be rational". But this had not been considered when planning the work, the review said.
Inadequate test procedures failed to identify a malfunctioning communication system used in the rescue operation, caused by wrongly connected microphone/earphones in the helmet. This caused "severe misunderstandings" between the standby diver and the diving supervisor, delaying the standby diver's rescue efforts.
The report states that the standby diver was on board the ship until the emergency occurred, so the time spent preparing him to help was far too long to be of any efficient life-saving assistance. Further, the return to surface was slowed because the standby diver had to make decompression stops.
"Despite the comprehensive list of failures in the investigation report, no legal action has been taken against any of the companies concerned," said Wingen.
Indeed, the DMAIB said in its review on Costello's death at Bard Offshore 1 that it aims only to clarify the actual sequence of events leading to the accident.
"With this information in hand, others can take measures to prevent similar accidents in the future. The aim of the investigations is not to establish legal or economic liability," said the DMAIB
The EDTC is critical of diving standards in the offshore wind industry and urges for their improvement to match those in the oil and gas sector, where most of the diving work is done from closed diving bells and decompression takes place on the ship, not in the water, observed Mayer.
But in Germany, oil and gas production is subsumed under mining law, which does not cover offshore wind. As the only German firm with a permit to perform diving work in connection with the North Sea oil and gas sector, Mayer says Nordseetaucher has insisted on using the stringent Norwegian Norsok rules rather than the German rules, BGV C23. The German rules and regulations apply to inshore and inland diving.
But Norsok rules are not applied in the German offshore wind sector and standards that are used appear to be lax. These issues highlight an inadequacy in current legislation in many of the European offshore countries, including Germany, Denmark and Belgium, to deal with safety of divers in the offshore wind sector.