COSTAIN is planning to complete its review of the collapsed tunnelling scheme at Gerrards Cross for supermarket giant Tesco in August.
Costain was brought in by the client in March to run the rule over the project after the original contractor, Jackson Civil Engineering, was booted off the scheme.
A spokesman said: 'We're planning to finish our review next month but the final decision over the project lies with Tesco.'
The Buckinghamshire project involved backfilling a 320 m tunnel for the construction of a Tesco store. But a 30 m section of the tunnel collapsed onto the Chiltern Railway line.
One company source said: 'Tesco is looking for a belt and braces, no risk solution to the problem, but that won't be cheap.'