When the cumulative monthly rainfall CE has been triggered on a one in ten year event there is confusion as to whether the impact of this CE should be reviewed taking into account the whole month or just the subsequent days after the trigger has been hit.
The NEC 3 contract states ‘Only the difference between the weather measurement and the weather which the weather data show to occur on average less frequently than once in ten years is taken into account.’
This statement seems clear on an event such as number of days over 5mm of rain but on the cumulative rainfall in a month event there seems to be conflicting views. Would it be correct to think that the rainfall and days upto the point where the 1 in 10 year value is triggered are covered under Contractor Risk and days following the trigger are then taking into account when assessing the Compensation Event?
It is fairly easy to prove something is a compensation event. It either did or did not rain in the month for either the 1 in 10 year event number of days, or the 1 in 10 event cumulative amount of rain in the month.
The tricky and inevitably subjective bit is PROVING the impact that the extra over rain had on the project in terms of time or cost. If it rained for 3 more days than a 1 in 10, or you had 100mm more than the 1 in 10 cumulative rainfall within the period, you have to demonstrate the effect that it had on your programme and its effect on planned Completion or any sectional/key dates.
The Contractor just has yo demonstrate as clearly and objectively as possible what this has been, and the Project Manager would have to assess accordingly if they don’t agree. Ultimately if the PM assesses and the Contractor does not agree, then an adjudicator might have the final say on what was reasonable for that CE quotation to be assessed at.