There is very limited time available to lower the water level in over twenty-eight (28) potential pavement blocks areas identified. An urgent need for releasing the water from the sand layer by temporary underdrain system has been proposed with document given in Appendix D. The proposed underdrain system consists of a block of stones wrapped with geotextile placed in the subgrade sand of the pavement structure in the grassing zone adjacent to the pavement structure as shown in Figure 44. Horizontal pipes are installed to drain the water from the underdrain to the secondary canal. The pipes are kept at the lowest possible level for maximizing the hydraulic head and flow, which is at elevation of -1.0 m MSL. The first trial section will be located to the south of Taxiway G, and this will be the pilot scheme for designing the dewatering work for other areas. The effectiveness of the system can be evaluated by introducing a series of observation wells in each water blockage area. By measuring the flow rates of the water through the drainage pipes and the reduction of the water level in the observation wells, it is possible to predict the time required for the water to reach an acceptable level (at least 0.5 m below the pavement structure along the centerline only). Once the results of the trial area are interpreted, the same scheme can be applied to other water blockage areas, but keeping in mind that there are very limited areas for installing the underdrains.