A “huge” new settlement planned north of Selby would have a “very significant” impact on York and could end up costing the council tens of millions of pounds, a meeting heard.

City of York Council is to lodge an official objection over Selby District Council’s preference for a new community of nearly 3,500 homes at Stillingfleet, around 1km from the York council boundary.

Corporate director of place Neil Ferris also called into question the viability of the proposed development, known as Heronby, and said Selby council officers had failed to engage at key stages of the process on cross-boundary issues.

Cllr Ashley Mason, executive member for economy and place, said: “This development is huge and it’s on our doorstep and for the council not to have come forward with that detail to help us make a really reasoned decision and proper engagement is disappointing.

“The Fulford School impacts and the highways disruption will be very, very significant.”

York Press: An artist's impression of Heronby. Picture: Escrick Park EstateAn artist's impression of Heronby. Picture: Escrick Park Estate

Selby has not yet made a final decision and is currently holding a consultation on its Local Plan, of which Heronby is a key part. The development would be built in stages and would not be finished until the 2060s.

According to a York council report, Selby council and Heronby developer, Escrick Park Estates, have underestimated the likely traffic impact on the A19 and Naburn Lane.

A transport assessment for the development does not propose any improvements to bus or cycle routes, the report said, leading York council officers to believe that a “far larger” proportion of trips to and from Heronby will be made by car.

A “mitigation package” of highways improvements north of Heronby has been offered, but these would be within the York boundary and council officers believe York would end up footing the bill, which would likely run into the tens of millions of pounds.

“This is not acceptable to City of York Council,” the report stated.

The council is also concerned that promises of a new secondary school at Heronby will not materialise because of a lack of pupils.

Officers fear children from Heronby could then end up displacing York children who would expect to get a place at nearby Fulford School, already one of York’s most popular schools.

The council’s report said that the “absence of critical information…calls into question the viability of Heronby’s development and undermines Selby District Council’s assumption that the site is developable.”

Mr Ferris added: “Provision for secondary schools and significant junctions onto major highways are tens of millions of pounds and significant land take.

“If they are necessary within the Heroby development, then there is a question as to the viability appraisal that needs to be undertaken by the developer and therefore the overall robustness of the impact on the Local Plan for Selby.”

Heronby was chosen as the preferred location for a new settlement over sites at Church Fenton and Burn Airfield, but the council does not believe the Selby’s assessment process was sound and said Church Fenton would have been a better option.

Mr Ferris said Selby council had written to York council to say there was more work to do on the transport impacts of its Local Plan, but that it believed it had fulfilled its legal duty to co-operate with York.

Selby’s Local Plan consultation ends on October 28.

A Heronby spokesperson said: "The Heronby project team understands the concerns which have been raised by officers from City of York Council, and are keen to support further engagement between Selby District Council and York prior to the submission of the Selby Local Plan for examination.

"We would also welcome the opportunity to present our detailed highways mitigation programme, and the supporting modelling work which has been undertaken, to officers and members from York."