5.5　Waterproof and Drainage of Underground Mine

5.5.1　When surface water body poses threat to shaft mouth or surface subsidence area，the surface water body shall be relocated，sealed up，intercepted，etc.

5.5.2　When ground water poses great threat to normal production of the mine exploitation，such control measures as drainage，interception or water barrier setting shall be taken.

5.5.3　For the mine with complex hydrogeological conditions or with danger of water bursting，watertight doors shall be provided at the key roadway.

5.5.4　Design water pressure of watertight door shall meet following requirements:

1　Design water pressure should not be lower than the water column pressure value from the rest water level of the protected acquifer to the setting stage elevation of watertight door.

2　For the open pit where shaft drainage is adopted，design water pressure should be larger than the water column pressure value from setting elevation of watertight door to the allowed flooding elevation of open pit at the maximum storm frequency.