Teesworks will start the next phase of dredging, where the material will be disposed of at sea, by the end of March next year.

The first period of dredging, where the material was deposited on land, started in September 2022 and concluded on November 9. However, the second phase, will see 900,000m³ of material dredged from the River Tees and disposed of at an approved location at sea.

A South Tees Development Corporation spokesperson said this would be done in accordance with its licence, which states that dredging can be carried out 24 hours a day. It is understood that a large proportion of this material hasn’t been disturbed and predates the industrialisation of the River Tees, therefore industrial pollutants can’t be found at these depths.

Before the licence was granted, samples of dredge material were tested to ensure it could be disposed of at sea. The dredging is taking place to allow for the construction of the £107m South Bank Quay with building work at the site expected to be completed by June 2023.

Dredging has become a contentious issue in the region. Huge numbers of crustaceans washed up on Teesside’s shores in October 2021 and rows have been ongoing since about the cause.

Labour MPs Andy McDonald and Alex Cunningham have both joined campaigners’ calls for capital dredging to be paused until a further investigation is carried out into whether the practice is linked to the crab deaths. Conservative Tees Valley Mayor Ben Houchen has previously said Labour politicians and eco-activists were trying to stop the development at the Freeport for ideological reasons.

Defra ruled that algal bloom is the most likely cause of the die-off, however, some academics, including Newcastle University’s Dr Gary Caldwell, believe a chemical called pyridine is to blame. He gave evidence at the Environment, Food and Rural Affairs Committee in October and questioned whether maintenance dredging could have disrupted a “pyridine reservoir”.

As the harbour authority, PD Ports carries out the maintenance dredging which takes place six days a week all year round. This is different from the capital dredging being carried out by Teesworks, which started for the first time in September this year.

In the aftermath of the mass die-off, Secretary of Whitby Commercial Fishing Association Joe Redfern told MPs that catches of velvet and shore crabs were “completely decimated” while Hartlepool fisherman Stan Rennie said he had faced a 58% reduction in income.

After the session, the committee chair Conservative Sir Robert Goodwill wrote to Defra secretary Thérèse Coffey. He urged the Marine Management Organisation (MMO) to urgently review dredging activity in the River Tees.

However, the letter from the cross-party committee did not call for it to be paused. The letter states that a complete moratorium on maintenance dredging would lead to the port and its associated industries’ closure, causing further economic damage. It also noted that there are already controls on both capital and maintenance dredging.

Last month, it was announced that an independent panel would be investigating the mass die-off. Defra chief scientific advisor Prof Gideon Henderson will team up with the government’s chief scientific advisor, Sir Patrick Vallance, to co-ordinate the independent group which will include experts from outside of government.

An MMO spokesperson said: “Dredged sediment must meet the highest international standards protecting marine life before it is permitted to be disposed of at sea. No materials have been licensed for disposal at sea in the area, which would fail to meet international standards.”

A spokesperson for South Tees Development Corporation said the work at South Bank Quay is of national significance and will unlock thousands of jobs.

They added: “As would be expected of a nationally significant project, we have complied with the highest legal standards and requirements laid down in licences and guidance right from the very start.

“This work is necessary to ensure the opportunity to bring thousands of jobs to the region is not lost. The first marine deaths occurred 11 months before any work was carried out by STDC and no further issues have been reported by Defra or the MMO in relation to the work carried out so far.

“To date, all works have been completed in accordance with the MMO licence, and were regularly inspected by the MMO, which has been satisfied that we have been compliant with the licensing conditions. We will continue to operate to the highest of standards and the rules and laws set out by Government agencies in this second phase of works.”

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