Data about an M25 runoff pond was mistakenly omitted by contractor Connect Plus Services during NCE’s investigation into their condition.
Additionally, WSP has been contracted to help improve knowledge strategic road network ponds and mitigate environmental impacts of high-risk outfalls for National Highways.
Missing investigation data
Despite the Freedom of Information Act only applying to public bodies, National Highways contractor Connect Plus Services (featuring Egis, Balfour Beatty and Edge Orbital Holdings) said it was to blame for failing to include a balancing pond at Swanley interchange in Kent in a list of 94 M25 road runoff ponds send to NCE earlier in 2024.
This suggests that National Highways does not itself hold data relating to the maintenance of its attenuation ponds around the M25.
The ponds used for water and pollution management around the M25 may be full of hazardous waste as National Highways is unable to identify when the majority (87) were last cleaned.
As part of work to identify the condition of the ponds, NCE assessed aerial imagery and found that Swanley Pond 1 in the northeastern section of the Swanley interchange was listed, but another visible pond in the southeast section was not, so an additional FOI request was submitted.
Swanley interchange ponds, December 1990
The photos above and below show the changes taking place in and around the ponds between 1990 and 2024.
Swanley interchange ponds, May 2024
In response, a Connect Plus Services spokesperson said: “We can only apologise that this pond was not included on the list we submitted in FOI 7760. This omission was an error on our part and due to a data export issue.
“The pond in question falls within the DBFO Co asset inventory database, as per image below showing it within our contractual boundary.”
Image of the southeastern Swanley interchange pond supplied by Connect Plus Services
“As such it is managed in accordance with the DBFO Co contract (design, build, finance and operate contracts) requirements and is monitored, treated and inspected as per the contract and service standards, as outlined in our previous response to Freedom of Information request 7760.
“The pond was last inspected on the 17 August 2022 and next due for inspection in 2024 as per the service standard requirements.”
The failure to include the pond in the original response, which was received approximately one and a half months after the normal deadline for FOI responses, which is 20 working days, raises questions about National Highways’ asset monitoring.
The Connect Plus Services spokesperson continued: “In terms of condition, the asset is performing as required and on the last inspection was condition scored as a ‘Condition Grade 1 – Clear’, which denotes that the ponds were free from silt and invasive vegetation.”
The classification ‘Condition Grade 1 – Clear’ is a new category of information which was not included in the original FOI release data and no explanatory notes were provided to explain what the classification means.
Stormwater Shepherds director of operations Jo Bradley said she thought the classification was internal language developed between Connect Plus Services and National Highways, rather than a standardised condition level.
Bradley said: “[National Highways will] have a service level agreement with the contractors and it will say, ‘Inspect the pond for this, this, this, this, and this’. I have seen a condition report before from a different part of the country and that was only interested in vegetation.”
She said the condition report she had seen from outside London assessed for the presence of invasive weeds and vegetation growth, but it did not mention sediment, and she indicated this may also be the case for the condition inspection at the newly identified Swanley pond.
Road runoff sediment is known to contain hazardous substances and National Highways has a responsibility to apply for permits from the Environment Agency if it believes it is creating pollution.
In May 2024, Stormwater Shepherds and CIWEM (the Chartered Institution of Water and Environmental Management) published a report which found National Highways and other highways authorities in England have no permits in place for managing the pollutants which are washed off their roads.
The Connect Plus Services spokesperson also said: “The asset condition will be updated during the next inspection as per the service standard requirements.”
National Highways and the Department for Transport declined to comment.
WSP appointed by National Highways to support its road runoff pollution management
WSP announced today it has been appointed to the role of technical partner on National Highways’ Water Quality Plan.
The Water Quality Plan aims to “improve knowledge around water run-off from the strategic road network and mitigate the environmental impact of high-risk outfalls as part of National Highways’ Environmental Sustainability Strategy”, according to the consultancy.
Outfalls are often managed by drainage assets like runoff ponds and other hard-engineered pollution control features.
WSP said it would be supported by Mott MacDonald, Ramboll and Aecom to carry out the work. It added: “Working alongside our partners, WSP will provide strong programme management and delivery arrangements to March 2025, with scope to continue to 2030.
“The role will include project and programme management, technical assurance, preliminary design and a programme of work across the third roads investment period (RIS3) as part of a long-term water quality strategy. National Highways is investing £10M this year in establishing the programme, with the technical partner role valued at £4M.”
The Water Quality Plan aims to address the 1,200 highest-risk outfalls by 2030 and WSP said it will validate and verify these high-risk assets and develop preliminary design solutions to mitigate associated risks.
WSP technical partner programme director and UK director of sustainability David Symons said: “We are delighted to have been appointed as Technical Partner, supporting National Highways to improve water quality across its network.
“Our project and programme management capability, relationships and expert knowledge will help us to deliver this vital work to ensure our water and our environment is protected.”
National Highways director of environmental sustainability Stephen Elderkin said: “We are committed to addressing the risk of pollution from road run-off. Bringing external expertise into this area will helps us to deliver our Water Quality Plan 2030.
“We have worked with WSP previously in developing environmental strategies and we look forward to working with them again as we continue to demonstrate that high quality road infrastructure can support positive environmental outcomes.”
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