NEC ECC: Change in the WI between tender and construction - what should have been allowed for

At tender the WI (drawings) included a note regarding “drainage connections will be rationalised during construction where possible”. The connections shown were into the main combined sewer for which the utility drawings indicated that this was some 5m or so deep.

After issuing the Construction Issue drawings this note was removed and as it turns out all of the new road drainage has been able to make use of the existing gully tails, removing the need for these deep excavations and connections.

Should the Contractor have allowed for the deep connections at tender stage or is it reasonable for him to claim that due to the note regarding rationalisation that no deep connections where necessary so were not included in the total of the Prices at tender?

I think the note is irrelevant as it is so vague.

The Contractor should have priced for what was shown on the drawings. The issue of the rationalised construction drawings are a change to the WI which would presumably result in a negative compensation event which reduces the Prices as it is easier to construct.

This assumes that the construction drawings were issued post-contract.

However, if I was a Contractor I would be pointing at clause 63.8 !