Thiess Services Pty Ltd v Mirvac Queensland Pty Ltd  QCA 50
The case of Thiess Services Pty Ltd v Mirvac Queensland Pty Ltd  QCA 50 involved a dispute between a Contractor (Theiss) and a principal (Mirvac) as to the remediation of a contaminated package of land.
In 2003, the parties contracted to clean up the property, which was a former gasworks, on the basis of Terms of Reference supplied by the Environmental Protection Agency. The lump sum contract stated:
‘The primary objective of the project is to fully remediate the contaminated material in order to render the entire site suitable for any land use’ The contract also provided a right of termination to Mirvac:
‘The Principal’s right to terminate for its sole convenience includes, without limitation, a right to terminate if high level contaminated material cannot be disposed of to a mono cell’
It subsequently became apparent to Theiss, that the remediation would be significantly more difficult and expensive to achieve than it had accounted for when executing the agreement, and it applied for a declaration from the court for an implied term that:
‘it need discharge that obligation only if it could be done economically’
Whether a right to terminate if the work was found to be economically unfeasible was implied?