Concerns have been raised for the future of Kingston Parkrun if plans to pump treated wastewater into the River Thames go ahead.

Kingston Council claimed it would be difficult for Kingston Parkrun to go ahead safely if Thames Water's controversial wastewater recycling scheme, the TDRA, is built in Teddington, although the firm disputes this.

The council warned proposed design changes to the project would make Burnell Avenue Open Space, where Kingston Parkrun begins, and surrounding paths more difficult to use, which would restrict physical activity and socialising.

The proposed changes involve a longer construction period, more heavy vehicle trips, a higher number of maintenance hatches, extra access requirements and a bigger infrastructure footprint.

The council said: "It is extremely likely that Kingston Parkrun will have to stop for good. When work starts… it would be difficult for it to go ahead safely due to the construction work on the upper and lower paths.

"The green space at Burnell is important as a starting point to thin the runners out before heading onto the towpath. When the works are complete there will be 34 inspection hatches in Burnell green space which impinge on this."

It said Kingston Parkrun sees more than 500 runners every week and is supported by up to 25 volunteers. However, Thames Water told the Local Democracy Reporting Service (LDRS) it is not correct to state Kingston Parkrun would need to stop permanently.

The spokesperson said: "Our expectation is that the event will be able to continue, although a temporary route diversion may be required during construction. We are engaging with Parkrun to explore and agree appropriate arrangements."

Parkrun told the LDRS it makes any changes or closures subject to risk assessments and course condition requirements.

The warning came in Kingston's response to Thames Water's now-closed consultation on proposed design changes to the project, which it has now published.

Overall, Thames Water's Teddington Direct River Abstraction (TDRA) project to ensure London has enough drinking water during times of prolonged dry weather would see up to 75 million litres of water a day taken from the Thames above Teddington Weir and transferred along a new pipeline to an existing underground tunnel.

This water would join the Lee Valley reservoirs, ready to become drinking water. It would be replaced in the Thames with "highly-treated" wastewater from Mogden Sewage Treatment Works via a new tunnel.

As part of the revised proposals, Thames Water changed the design of the proposed intake and outfall structures near Beaufort Road and Burnell Avenue – including increasing the size of the nearby control building and number of maintenance hatches needed.

It is proposing to use a bigger area to divert a power cable at a substation at Beaufort Road and to increase the number and peak levels of heavy goods vehicles (HGVs) servicing the Burnell Avenue worksite, while slashing HGV trips at the Tudor Drive worksite and removing all HGV trips from the Ham Playing Fields worksite.

Other proposed changes involve extending the construction period at the Burnell Avenue worksite and routing construction traffic through Ewell Road, on top of other roads already identified, to service the Burnell Avenue and Tudor Drive worksites.

The firm also scrapped proposals to build an intermediate shaft at Ham Playing Fields.

Kingston Council said that while it recognises the importance of securing long-term water supplies during drought, it has major concerns about the revised proposals and their impact on local residents, green spaces and roads.

The authority said an increase in construction activity could have major traffic impacts on Burnell Avenue, Beaufort Road, Dysart Avenue and Dukes Avenue.

It raised concerns there would be more disturbance to wildlife, including badgers, and about the final quality of the wastewater being pumped into the Thames as it said the river's chemical makeup would be changed.

The council also said the proposals risked undermining the "perception and reality of safe recreational water use" at the River Thames' first official bathing spot nearby, which was designated in May.

It outlined concerns about Thames Water's handling of the consultation, as it said the council was notified late, it was not promoted enough, the response window was short and the firm did not provide inclusive opportunities for people to get involved.

Thames Water's own consultation documents said the proposed changes mean the project would have greater impact on the area – including on recreation, health, open space, traffic, noise, air quality and a conservation area.

The scheme has attracted sustained backlash from local MPs, residents and campaigners, who have raised concerns about its potential impact on the environment, wildlife and human health.

A petition demanding it is scrapped has gained more than 34,200 signatures.

A Thames Water spokesperson told the LDRS the project would keep taps flowing for millions of Londoners in times of drought, and that protecting the environment and recreational space is central to how it is developing.

The spokesperson said: "We would like to reassure river users that our proposed Teddington Direct River Abstraction project would not deteriorate water quality and would be required to meet strict environmental and water quality standards set by the Environment Agency.

"The new treated water outfall would also be located downstream of the bathing water site, and the recycled water would flow downstream over Teddington Weir into the tidal Thames, away from the designated bathing water site.

"We are continuing to work on the best ways to manage potential construction impacts, and will set out our approach in the construction traffic management plan published as part of our development consent order (DCO) application.

"We have run several rounds of public statutory and supplementary consultation, and hold regular meetings with relevant local authorities to keep them updated.

"Since our statutory consultation last year, we have been considering all the feedback received, engaging with stakeholders, and developing our design with information from surveys and technical assessments."

Thames Water said it will continue to engage with locals as it prepares to apply to the Government next year for a development consent order to build the project.

Ali McArthur, global head of event delivery and volunteering at Parkrun, said: "The majority of parkrun events take place on public land, and we have robust safety and policy procedures in place to ensure people can walk, jog, run, or volunteer safely.

"We appreciate the land use granted to us by all the landowners we work with, and any course adjustments or closures happen subject to risk assessments and course condition requirements.

"We always work closely with landowners and event teams to try and keep communities connected and active wherever possible."

Thames Water recently conducted a recreational use survey for the Burnell Avenue Green Space. However, local campaign group, Save Our Lands and River (SOLAR), accused it of being flawed.

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