Chancellor Rishi Sunak was only granted planning permission for a new swimming pool at his home after overcoming objections he would create a toxic environment.
The front-bencher looks set to build a lavish outbuilding containing a private pool, gym and tennis court at his Grade II listed private country manor.
Sunak bought the gated property in an isolated hamlet near Northallerton, North Yorkshire, with his wife Akshata Murthy in 2015.
He has now secured planning permission but came under fire for his extravagant expansion at the same time he was proposing to cut Universal Credit by £20 a week.
And documents related to the application show he was only given the green light by Hambleton Council once he overcame fears about the pollution he might cause.
The Environment Agency initially raised concerns that Sunak had failed to supply enough information that the risks of pollution to the water environment could be safely managed.
Fears surrounded his disposal of swimming pool effluent, described as potentially “highly toxic” and foul water sewage as the original application failed to address the issue.
The 20m pool would be ‘L’ shaped and the pool house would also include a hot tub, utility and changing area, and a plant room.
Tim Crawshaw, planning advisor for EA, said in his initial objection: “Although in their application the applicant indicates as means of disposal of foul effluent a non-mains drainage system comprising of a package treatment plant, they have not provided any details on the type of the discharge (to the ground or to surface water), neither any information on its location and the location of the discharge point.
“Additionally there has been no information submitted on the system’s specifications and the predicted maximum effluent volume to allow us to assess whether the system is capable to treat the effluent to a high standard.
“The applicant has not provided information on the means of disposal of swimming pool effluent. Swimming pool effluent discharges result from the cleaning of filters (filter backwash) and the emptying of pool water (drain-down water).
“Please note that filter backwash although of small volume has the potential to be highly toxic.”
Objections were also raised around the pollution prevention measures during construction.
Mr Crawshaw added: “Given the size of the project and the proximity of the site to a number of waterbodies, construction activities have the potential to cause pollution or impact the quality of the water.
“Silt pollution is a major cause of environmental incidents with severe impacts on aquatic life.
“Therefore measures should be taken to prevent run-off water containing sediments from entering and contaminating watercourses.”
As part of the planning process, Sunak was given a list of conditions to meet to overcome the objections.
Among them was a need to provide a drainage plan and clearly demonstrate that the proposed treatment plant was capable of treating the maximum volume to a high standard.
He also needed to indicate the means of disposal of swimming pool effluent.
After submitting further details, the agency said it would support the proposal if the conditions were met.
Planning official for Hambleton Council said in recommending approval of the application: “The Environment Agency withdrew their earlier objection provided that a pollution prevention method statement and contingency plan is attached to any planning permission.”
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