Up to £645,000 of work to fill in an abandoned mine is needed before new housing can be built on the site of a former care home.
East Lothian Council demolished Fa'side Lodge five years ago as part of a plan to build new council housing on the land in Tranent.
However the site sits over coal deposits known locally as the Great Seam, and the local authority is now bringing in a private contractor to "consolidate the abandoned mine-workings" on the site ahead of building the new homes.
In a report to the elected members' library service it has been revealed Nottinghamshire company Groundsource Drilling and Contracting Ltd have been awarded the contract to carry out the work.
The report says the work, which is expected to take 14 weeks, will "involve the consolidation of mine-working in the Great Seam Coal beneath the site by means of drilling and the pressure injection of grout to prepare the site for the proposed construction work."
And it says it will cost at least £139, 720 and at most £644, 975 - warning the extent of work required is not yet known.
Fa'side Lodge closed as a care home in October 2014 after the new Crookston home opened in the town.
It was demolished after removal of asbestos and the council then bought the neighbouring Church of Christ meeting hall which was also demolished and increased the site.
The plans for 28 housing units include a mix of wheelchair accessible bungalows and flats.
The Great Seam refers to coal deposits which ran under Tranent and were said to be at least seven ft thick and near the surface.
Mining work in the town dates back to the 13th century and carried on until the deposit was depleted in the early 20th century.
