In our option A contract the risk register has an item which is a client risk for reinforcement. The Contractor claimed the amount which was agreed and so the risk was closed. The engineer made a mistake and said additional reinforcement is now required. Who carries the risk for the additional reinforcement?
Depends what you mean by “risk register”. There are general “risk registers” used and known within the industry, and there is the NEC3 Risk Register (which under NEC4 has now been a called the Early Warning Register to avoid such confusion). The Risk Register(/Early Warning Register) is not a place to allocate risk. It identifies the risk and records the latest action to try to avoid or mitigate the risk. Outside of that register the contract should make it clear who’s risk that is. Services in the ground might be a known risk, but if Site Information shows them then the risk is with the Contractor.
In simple terms who ever the risk owner was before it went on the Risk Register is the same person who owns the risk afterwards - what ever has been discussed.
Your specific example is quite a strange thing to go on the register in the first place. Lets say the reinforcement issue was say “additional areas of steel above piles” and it is not know how many piles there will be, if the Employer has made it clear this is their risk then that is fine. It could be on the Risk Register as an item that might require significantly more than allowed for within the contract, but the Risk Register would not allocate who’s risk this was.
If additional areas of reinforcement are required, then this would be a compensation event if it is a change to the Works Information and the Contractor would be able to recover time/cost accordingly. If the Works Information made this risk a Contractor risk, then what ever is discussed at the risk reduction meeting and is recorded on the Risk Register will still be a Contractor risk.
I hope this helps/makes sense?