North East File Collection - NEFC

In the aftermath of the crab die-off many people thought that the presence on the South Tees site of 100s of tonnes of chemicals which were highly toxic to the marine environment could not be just a coincidence. However, this was ruled out as possible cause of the die-off by the Independent expert assessment of unusual crustacean mortality in the North-east of England in 2021 and 2022 (CMEP - Crustacean Expert Mortality Panel).

The EIR response 260318_-_stdc_-_comah_chemical_inventory shows that not only was 1000s not 100s of tonnes of highly toxic chemicals in the open on the South Bank site and this material was being actively worked in September / October 2021 (260318_-_stdc_-_disposal_records_of_coke_ovens_hazardous_by-products), but in this EIR response a release of over 300kg per day was recorded in the measurement of polycyclic aromatic hydrocarbons (PAHs) in the outfall to the River Tees from the site.

While it is now know that a release of PAHs occurred in late September / early October, it is not known whether this resulted in 1s or 10s of tonnes of PAHs being released. The total inventory on site was over 4000 tonnes so only 1% loss would have released 4 tonnes.

18th March 2026

Dear South Tees Development Corporation,

As the body responsible for the South Tees Site, I am requesting specific data regarding the management of hazardous chemical legacies inherited from the South Tees Site Company and responsible for the site's classification as a COMAH Upper Tier site.

To understand the environmental context of the site’s redevelopment, please provide:

Request: Monitoring Data: Any internal environmental impact assessments or water quality monitoring reports conducted by the STDC or its predecessors or its contractors in relation to site runoff into the River Tees during the 2017-23 period.

Please handle this request under the Environmental Information Regulations (EIR) 2004, which provide for greater transparency on matters affecting the environment.

Environmental Information Regulations (EIR) 2004 Act - Reference: STDC-008-2026.

Thank you for your request for information received on 18/03/2026. In response to your request, we can now provide the attached response and information - EIR/STDC/South Tees Site Runoff Environmental Assessments-EIR 008 2026 Response.pdf.

If you have any queries or concerns, please contact [1][STDC request email] in the first instance.

Please remember to quote the reference number above in any future communications.

If you are unhappy with the way your request for information has been handled, you may request an internal review within 40 working days by writing to:

• Group Interim Monitoring Officer, South Tees Development Corporation, Teesside Airport Business Suite, Teesside International Airport, Darlington. DL2 1NJ.

If, after your complaint has been determined, you remain dissatisfied with the handling of your request or complaint, you have a right to appeal to the Information Commissioner at:

• The Information Commissioner's Office (ICO), Wycliffe House, Water Lane, Wilmslow, Cheshire, SK9 5AF Telephone: 0303 123 1113 Website: [2]https://ico.org.uk/make-a-complaint/ The ICO does not make a charge for an appeal.

Yours sincerely, [3][email address]

TVCA Governance on behalf of South Tees Development Corporation, Teesside Airport Business Suite | Teesside International Airport, Darlington DL2 1NJ. [4]www.teesvalley-ca.gov.uk

References

Visible links

1. mailto:[stdc%20request%20email]
2. https://ico.org.uk/make-a-complaint/
3. mailto:[email%20address]
4. http://www.teesvalley-ca.gov.uk/

EIR/STDC/South Tees Site Runoff Environmental Assessments-EIR 008 2026 Response.pdf

Thankyou for your email.

I can confirm the below in relation to your request EIR STDC-008-2026

R1 - River Tees outfall is located at the Northerly point of the Teesworks site on the boundary with RBT. The outfall is a culvert that goes from the Teesworks site boundary under the RBT facility to a discharge point within the river Tees.

C3 - This is a monitoring point on the Lackenby channel at the point where the watercourse enters the tidal culvert adjacent to the Teesworks site boundary and PD ports Tees Dock Road.

Kind Regards,

Governance Team [email address]

Tees Valley Combined Authority, Teesside Airport Business Suite, Teesside International Airport, Darlington DL2 1NJ. https://www.teesvalley-ca.gov.uk/

The data supplied documents a massive release of polycyclic aromatic hydrocarbons (PAHs) which started at some time between 28th September and 7th October 2021 (based on PAH measurements) and had ended by 1st November 2021 (based on suspended solids / COD returning to pre-levels).

Estimating the total release of PAHs:

• The concentration of only 8 PAHs were measured,
• Measurement based on single sample taken at one time,
• Unlikely to have been the highest concentration that was released at any time over the period,
• The average concentration could have been considerably higher,
• The duration of these higher concentrations are unknown.

Bearing in mind these uncertainties the total release is very likely to have been considerably more that 1 tonne.

However, based on the concentrations reported the table below shows the quantities that would have been released over different periods of time.

A single accidental release event can not be ruled out such as split in tank caused by the explosive demolition about it or flushing out of a pipe what contained large quantities of PAHs.

However, the documents do suggest the source of the spike in Polycyclic Aromatic Hydrocarbons (PAHs) in the October 2021 runoff water is the massive, exposed stockpile of coal tar “jollop” and the intensive demolition and transport of Coke Oven Gas Main (COGM) deposits occurring at that exact time.

The records provide several pieces of evidence that point to these sources:

1. The Exposed Coal Tar “Jollop” Stockpile and “Contaminated Rain Water” The COMAH (Control of Major Accident Hazards) inventory documents explicitly record the presence of “Contaminated Rain Water” directly associated with an “On ground (tar/coal mix)” at the South Bank Coke Ovens. The records show that this was a massive, irregularly shaped stockpile of coal tar “jollop” that drone and satellite imagery measured at approximately 75m long, 20-26m wide, and 3m high. Coal tar is exceptionally high in PAHs. The records indicate that bulk removal of this stockpile to Port Talbot for re-use did not begin until December 2021 and early 2022. Therefore, thousands of tonnes of PAH-rich coal tar were sitting exposed to the elements throughout October 2021, which would have allowed rainwater to wash directly over the tar and generate contaminated runoff.
2. Major Demolition of PAH-Rich Infrastructure October 2021 coincided with the conclusion of several major demolition projects involving infrastructure heavily contaminated with Naphthalene (a prominent PAH) and coal tar. The demolition and decontamination schedules show that work on the Coke Ovens Battery – East, the Clarifiers, and the Coke Oven Gas Main all concluded on or around 29/10/2021. The Coke Oven Gas Main alone was recorded as containing roughly 1,137 tonnes of deposits and 409 tonnes of Naphthalene prior to these works. The widespread disruption, cutting, and dismantling of these heavily fouled pipelines and vessels during October would have exposed large amounts of trapped PAHs to the open air and rainfall.
3. Intense Disruption and Transportation of Hazardous Waste The weighbridge records demonstrate that October 2021 was a period of intense movement for PAH-bearing wastes, meaning contaminated material was actively being dug up, handled, and loaded on-site.

Throughout the entire month, there were almost daily shipments of “Coke Oven Gas Main Waste,” often exceeding 100 tonnes per day, moving from the site to Bran Sands and Port Clarence.

On 21/10/2021, contractors also began digging up and removing loads of “Tar Breeze Benzol” to Port Clarence , indicating that highly toxic tar and benzole sludges were actively being disturbed on the ground during this window.