In a the following scenario, can someone provide guidance if indeed the PM was to make an assessment. Contractor notifies a CE due to rainfall exceeding one in ten year data. The weather centre issues out that the average number of days rainfall at the place stated in the Contract Data > 5mm is 4 days; one in ten is 9 days (>5mm) and the weather data determines that ten days in that month, the rainfall exceeded 5mm. Is is the difference between the 10 days and the average or the 10 days and 9 days that trigger the one in ten?
It is the difference between the 1 in 10 value and the actual data. The compensation event should then assess the impact of this extra days rain as to what it had in terms of time and cost. In practice this is usually very difficult/subjective to definitively determine the specific impact of this one day - but that is what the Parties have to try to determine.