Due to rough sea conditions during the South-west monsoon period, unsuitable for construction of Marine Works, the construction of Colombo Port City Development is paused from approximately April / May to August / September. High wave conditions can possibly affect and damage the constructed Marine Works so far, which are still under construction and do not have the required armour protection yet. For this reason a Desk Study Analysis is performed by CDR International on the stability of Marine Construction Works (Rock Works) during the 2015 Monsoon period. The study included statistical wave analysis, determination of possible extreme conditions, numerical modelling of wave conditions for the temporary construction phase, stability analysis of the temporary works and final recommendations for the stability of the constructed works during the monsoon period. Final conclusions and provided recommendations helped the Client to minimize damage and loss of material during the monsoon period.