Scotland’s environmental watchdog has criticised nuclear waste handling at the UK Trident bomb base on the Clyde after a “significant” mix-up over the disposal of submarine waste.

During an August 2017 visit to the Royal Naval Armaments Depot at Coulport, Scottish Environment Protection Agency (Sepa) staff found untested waste from submarines, potentially containing radioactive material, had been mixed with other waste.

This meant that radioactive waste could have been taken off site and disposed of as if it were non-radioactive waste.

Sepa also said that the Royal Navy was in breach of an agreement about when and how it should tell Sepa about waste incidents, prompting the SNP to say the issue was “deeply worrying” while calling on the UK Government to investigate.

The Ministry of Defence (MOD) is supposed to tell Sepa ‘without delay’ when an environmental incident occurs. It should then provide a written report within 14 days.

Documents released under freedom of information legislation show that an internal MOD probe found that no radioactive waste left the site. But the only reason the untested material was not taken off the base is because vigilant civilian waste contractors refused to pick up the incorrectly processed waste.

A Sepa letter to the MOD said that the watchdog considered this type of incident as “significant” adding that had the Royal Navy been a civilian operator, it would have considered issuing a formal written warning.

Sepa’s chief officer, John Kenny, told The Ferret that the incident raised concerns regarding the “adequacy of arrangements for radioactive waste handling” at the Coulport site.

SNP defence spokesperson Stewart McDonald MP described the MOD waste failings as “deeply worrying” and said the incident raised questions that must urgently be answered by the UK Government.

“Are these incidents a result of negligence or is the Ministry of Defence wilfully cutting corners and putting public health and our environment at risk? While Scotland has the injustice of having unwanted nuclear weapons on our lochs, the MOD is failing basic standards.”

He called for the MOD to be made accountable to the Scottish Government for the environmental impact of its operations in Scotland. “This is not the first time the MOD has been guilty of safety breaches so it seems lessons are not being learned,” he argued.

This is not the first time the Ministry of Defence has been guilty of safety breaches so it seems lessons are not being learned. The MoD must be fully answerable to the Scottish Government and Scottish Parliament on environmental issues. Stewart McDonald MP

Devolved environmental laws applying to civilian industrial sites that handle nuclear material do not apply to military sites such as Coulport and the neighbouring nuclear submarine base at Faslane.  This limits the action that Sepa can take to ensure the MOD follows environmental guidelines.

Campaign group Navy not Nuclear pointed to a long history of MOD “poor practice” when it comes to handling nuclear materials in Scotland, dating back more than a decade.

“The most damning thing about this is that nothing has changed,” it said. “The MOD are still failing to follow their own operating procedures, and they’re still failing dismally when it comes to telling the regulator and protecting the environment.”

The group called for more to be done by both the MOD and Sepa to alert the public when environmental incidents occur.

“It shouldn’t be the case that this information should come to light by freedom of information, they should have a statutory public duty to disclose this information,” it said.

Trident nuclear safety reports suppressed by the Ministry of Defence

Arthur West, chair of the Scottish Campaign for Nuclear Disarmament (CND), echoed these concerns, and said it was time for the MOD to “up their game”.

He said: “Scottish CND are very concerned that the documents reveal that Sepa think a written warning would have been handed out to a civilian operator who had behaved in a similar way.”

In response, Sepa’s John Kenny said: “In August, during a Sepa inspection, MOD Coulport notified a Sepa officer that a limited quantity of radioactive waste had been incorrectly categorised.

“Whilst Sepa considers this type of incident as significant, and the incident does raise concerns regarding the adequacy of arrangements for radioactive waste handling, MOD has conducted a full investigation and a number of actions have been recorded which Sepa will robustly inspect against moving forward.”

Following the breach in waste management procedures, MOD site managers admitted there had been “clear process failings and a lack of management supervision”, and ordered a full internal review of waste handling and staff training.

Perfect storm: MoD report says Trident nuclear plans in trouble

Documents also reveal that the Royal Navy sought guidance from Sepa in October 2017 on what they should do with radioactive bilge water produced by the Trident submarine fleet.

In a letter to Sepa on 10 October 2017, the Royal Navy admits that “levels of tritium have been detected in submarine systems generally regarded as non-radioactive”. The letter goes on to suggest that it may be appropriate to discharge this waste into the sea.

Sepa has still not provided finalised guidance to the navy on how it should treat radioactive bilge water produced in Scotland.

However, Kenny insisted that there was no risk to human health or the environment from the liquid waste and that Sepa would shortly reach a decision about “the appropriate regulatory steps” that may need to be taken.

“Sepa’s first priority is always human health and the environment. Having moved quickly to confirm there was no risk to human health or the environment, we remain confident that trace levels remain so low as not to require a permit under any other circumstances,” he said.

“By comparison, excluding the impacts from oil or grease, one litre of the highest concentration of effluent would have the same radioactive impact as approximately 1/10 of a banana. We advised the Ministry of Defence in October, and again in December, of our expectation that they inform their contractor and other relevant parties.”

The Ferret previously revealed details of MOD plans for 14 new developments at the Trident nuclear base, said to be worth £1.3bn. These developments include plans for a “nuclear support hub,” a “submarine support hub,” and Coulport “water refurbishment”.

The MOD insisted that it has “a transparent and constructive relationship with the Scottish Environmental Protection Agency”.

A spokesperson added: “The safety of the public, our submarine crews, the defence workforce and the protection of the environment remain our priority.

“We fully comply with applicable environmental legislation and routinely work with other agencies to share best practice and on how to manage and process radioactive waste.”