The cost of demolishing a town's former leisure centre has spiralled to nearly £1.7 million owing to the pandemic and the discovery of previously hidden drains.

An overhaul of the former White Oak Leisure Centre in Swanley has seen the old centre scrapped and a brand new £20m replacement built next door.

Demolition of the former site in Hilda May Avenue is already under way but the project has now seen costs jump by more than 40%.

Originally, Sevenoaks council had set aside just under £1m (£990,992) to cover the sum needed to knock it down.

But it has now incurred additional costs of £698,365, bringing the total expected expenditure to £1,689,357.

Covid-19, supply chain issues and undiscovered drains have all been blamed for pushing the bill up.

The council says most of the costs were "out of its control" but it is actively exploring options to recover some of the construction costs it describes as "preventable".

Work on the new centre began at height of the pandemic with the site having to introduce Covid-19 safety measures to protect workers.

Like many developments it has experienced supply chain problems in the past year.

The council says this has resulted in some building materials becoming much more expensive or unavailable.

Whilst these have added some extra costs to the project, there have also been two further issues which have impacted on the cost of the project.

During the early stages of construction, a network of Kent County Council highway drains were uncovered.

These were not mapped or found during surveys of the site by specialist contractors.

More recently, the council learned that the demolition costs are set to increase as the surveyors working on behalf of the construction firm underestimated the full scale of the work.

The council believe that most of the additional costs may have been preventable and are looking at how these can be recovered.

Cllr Peter Fleming, leader of the council, said: “After opening the new centre that sees an exciting future for health, sport and leisure in the north of the district with both a fabulous new centre and operator, we are determined to provide council taxpayers with the best value for money in any projects we undertake.

“There is no doubt that undertaking a large-scale project during a global pandemic and at a time when the nation is forging new trade arrangements would bring challenges, which we have overcome."

The Tory leader added: “Some of the extra costs we believe could have been avoided and as such we are looking at how best to recover them.”

The new White Oak Leisure Centre opened its doors to the public last month with more than 10,000 people attending.

It's the single largest investment by Sevenoaks council in more than 30 years and offers an all-in-one membership with a host of new facilities.

These include a 25m six-lane swimming pool, 100-station gym and fitness suite, two exercise studios, cycling studio, and a sports hall.

Other attractions featured are TAGactive, a brand new interactive gaming activity, as well as a 140 space car park and coach drop-off point.

Built in the 1960s and extended in the 1970s, the old centre was deemed to be coming to the end of its life and too expensive to run.

But criticisms were levelled at the replacement leisure complex, which was approved in 2020, after some clubs saw their tenure axed and had to be relocated to nearby venues.

Up to 40 apartments will also be attached to the site as part of the final phase, varying between one, two and three-bedroom flats.

During its passage through planning, councillors also agreed funding for sports hall improvements at the nearby Orchards Academy.