Developers behind the Matlock Spa build, the 432 houses planned for Cawdor Quarry, are facing a £6million bill for having the land cleared of contamination – which is likely to delay the project by at least 15 months.

Site owner Groveholt Ltd has submitted revised plans to build 26 of the houses on an uncontaminated area of the site near Snitterton Road in order to generate cash for the clean-up operation.

A report by the client's representative, EWP Associates, states: "This delay has major cash flow significance to the developer and is a disappointment to all those who wish to see residential development on the site as soon as possible in order to continue the momentum following the opening of Sainsbury's."

Planning permission was granted for the project in December 2001, based on site investigation reports carried out before Groveholt's purchase.

In order to prevent the site reverting to a previous owner, the company needed to achieve full planning permission before March 2002, and said it had insufficient time to carry out further tests.

But new analysis has revealed widespread hydrocarbon contamination in large areas of the former stone and limestone quarry, which would cost around £6million to clear.

The report states: "The one exception is the area of the site adjacent to Snitterton Road which is not quarried or contaminated and effectively separate from the quarry."

The new proposals seek permission to change the route of the collector road, forming a boundary which the company believes would prevent cross contamination between the main quarry and the houses to be built on the unaffected area.

Matlock's mayor, Cllr David Barker, was philosophical about the potential delay.

He said: "I would be very surprised if they were not still building houses there in five or eight years' time because Matlock cannot absorb that many houses in a short space of time anyway.

"I don't think Matlock is desperate for the houses just yet because there is plenty of choice. We have never looked at the scheme as anything other than a long-term project."

Eifion Phillips, development manager for EWP Associates, declined to comment ahead of impending negotiations with planners at Derbyshire Dales District Council.