Tender Vs Construction Drawings (NEC3 Option A)

At Tender Stage our client issued drawings along with the ITT to carry out the civils element of the works. Part of the work-scope was to divert existing services prior to allow the construction of a new RC tank in the footprint. Within the diversion scope was the diversion of 2 existing drainage routes.

The tender information was not detailed, particularly with regards to the drainage requirements, and the relevant drawing appeared to show the diversion to be at a depth of 200mm referring to the MH Schedule. However we were able to scale from this drawing for the remaining works in this area correctly, and therefore assumed the depth of the drainage by scaling the Manhole Diameters and assuming a depth based on Standard Manhole Details. The depth assumed was 1.5m based on the lack of information. There was no other information available on drainage depth at this stage other than as described above.

While its clear that there was a failing on the Bid Team stating their assumptions to the Client, or submitting a Tender Query at the very least. The Works Information available to us was unclear

Subsequently, just prior to the bid being submitted, the Client issued further drawings. This included, relevant to the drainage diversion, a service drawing. The service drawing which showed all buried services for the scheme, including very faintly a depth of circa 4m for one of the existing drainage lines to be diverted.

The drawing was disregarded, or more accurately, not picked up by the Tender Team as showing a depth for the proposed diversion or as being somewhere they would look for this information. This was the only other piece of information that would point to a deeper diversion being required.

Subsequently the construction drawings were issued when in contract, which fully detailed the drainage diversion and new cover and invert levels given. This in turn gave rise to a diversion depth of circa 4m, vastly increased from what was priced/allowed for at Tender.

Q1. In this instance would there be a route for recovery through the ambiguity clause 17.1, with the obligation that the Works Information should be a complete and precise statement of the Employer’s requirements. If it is not, there is a risk that the Contactor will interpret it differently from the Employer’s intention.

Q2. With construction drawings not being an NEC term, would it be best dealt with as just a straight change from the Tender Drawing perhaps? (ie with the tender drawing which showed the shallow depth diversion against the up-revved drawing at construction stage showing the deeper diversion)

1 Like

I would first check the Contract Data to clarify what this references for Works Information, which should represent the ‘baseline’ Works Information. Any subsequent changes to this would most likely be a change to the baseline and constitute a compensation event, whether or not the matter was notified as such at the time. One point to note, however, is to clarify who issued these construction drawings and whether that person has authority under the contract to instruct such matters.

Unfortunately Works Information is not always a complete and precise statement of the Employer’s requirements, which often creates uncertainty as to what the scope of works actually is.

To clarify, any ‘change’ (compensation event) would be based on what is stated in the Contract Data as Works Information, compared with any subsequently instructed information, where instructed by a person with appropriate authority under the contract.