NEC3 Clause 60.2 stating what information shall be taken into account by the Contractor. If the information does not indicate the underground condition (thousand m3 of C&D waste were found), who bears the risk? They are not the Employer’s risks stating in Clause 80.1.
You need to read clause 60.1(12) alongside clause 60.2 to understand how the CE for changed physical conditions operates.
From what you say the Site Information did not state the conditions that were found so the Contractor will be entitled to a CE for the difference (cost and time) between the conditions that the Site Information did describe and the conditions that were found. Make sure you’ve fully understood the Site Information before making a decision on this one, for example statements in there about previous use of the Site could be used to reject a CE.
thank you for your advice