More than 80 trucks loaded with concrete will be required to fill in the illegal basement in the Kowloon Tong home Henry Tang Ying-yen's wife owns. That's enough to fill six double deckers.
A person close to the rectification work ordered by the Buildings Department said the architect Tang employed to carry out the work could submit a plan for approval today.
According to the draft plan, the work does not involve solidifying the house's foundation, as the building has been proven to be structurally safe. The contractor is expected to remove items in the basement, fill it with concrete and seal it.
In order not to overload the existing foundations, the contractor will be asked to use no-fines concrete, which is of a lower density and lighter in weight.
According to the size of the basement - 19 metres long, 11 metres wide and 3.5 metres high - the amount of cement needed to fill it will be over 730 cubic metres. The massive volume will require transportation by more than 80 cement trucks, each holding 9 cubic metres.
The person familiar with the work said workers could make use of the two holes designed in the bottom of the swimming pool above the basement as a vent to pump concrete in. The holes were for windows, designed to allow visitors in the basement to watch people swimming.
The windows will be sealed, according to the demolition plan, to restore the house to its original state as specified in the approved building plan.