To facilitate drainage of groundwater and to maintain water flow , permeable rocks will be used for recompaction . filter layer and weepholes will also be installed . these will guarantee the normal flow of groundwater 为促进排水及保持正常水流，工程将使用具渗透性的石块作重新压实，同时安装过滤层及疏水孔，以确保地下水仍可如常流出。
