3　Hydraulic Structures

3.1　Retaining and Discharge Structures

3.1.1　Safety assessment or safety technical identification for structures in the power station shall be carried out regularly.

3.1.2　The monitoring items and times shall meet the design requirements.The monitoring results shall be analyzed and archived in time.

3.1.3　Hydraulic structures shall be inspected and toured by staff frequently or regularly.An inspection tour system shall be set up，in order to discover defects and hidden troubles in time.The inspection shall include the following contents.

1　Dam body cracks，slope leakage，bypass seepage，and abnormal leakage or unusual displacement of permeable dam foundation.

2　Earth dam slope stability；dam crest flatness and slope leveling；no cracks，subsidence，bulges，ant nests or animal caves with impacts on structural stability or seepage flow safety；complete slope protection of dam surface with no local defects like looseness，subsidence or slumping，cushion loss or hollow slope protection；no leakage pools，subsidence area，piping，abnormal growth of plants and backflow scouring in downstream surface and dam toe；no turbid seepage water.

3　Denudation，abrasion or water seepage of concrete dam body；no displacement between adjacent dam monoliths；normal performance of expansion joints and waterstop；no cracks that affect the structure or seepage safety；normal change of uplift pressure.

4　Intact structure of discharge structures；flood way without any damage；no abnormal cracks，settlements or seepage in the steep slopes，side walls and inner surfaces of flood spillways and flood discharging tunnels；energy dissipation facilities without any damage.

5　Intactness and normal operation of ancillary facilities of retaining and discharge structures.

3.1.4　Maintenance and repair of retaining and discharge structures shall be implemented according to the relevant provisions.The maintenance shall meet the following requirements.

1　Dam crest，slope，parapet wall and observation facilities shall be intact.Drain ditches shall be dredged in order to keep them clear.

2　Materials shall not be stacked on the dam crest，slope or berm.The dam surface shall not be used as a transfer dock，and the crest，slope and dam toe shall not be used as water conduits.

3　On the dam and in the upstream and downstream ranges that may affect the project safety，activities harmful to the project including digging pits，building fish ponds and drilling wells shall all be forbidden.

4　Erosion and scouring of the dam surface by rain water shall be prevented.The filtering facilities of the dam body and pressure relief devices behind the dam shall be maintained in order to ensure normal operation.

5　In the silt-laden areas，reservoir sand flushing facilities shall be opened regularly.For cold areas，ice prevention measures shall be adopted for buildings.

6　On the dam surface，no plants and crops shall be cultivated，no grazing allowed，no turf spaded，and no removal of the sands and gravels used for slope protection and seepage diversion facilities.

7　The concrete weirs with hydraulic automatic balanced gates shall not only meet the relevant requirements for concrete dams，but also ensure the opening and closing flexibility of the flap gates.

8　The deflating devices of rubber dams shall be safe and reliable.The dam bag shall be intact and meet the requirements of flood discharging.Electromechanical devices and water（air）filling pipes shall work properly.

9　The structure of the discharge structures shall be intact.If there are abnormal cracks，settlement and water seepage in the steep slopes，side walls and inner surfaces，and the energy dissipation facilities are destroyed，discharging shall be stopped for emergency repair.For those that cannot meet the conditions temporarily，an alternative discharging scheme shall be used in order to prevent worsening the accident and create conditions for emergency repair.

10　The sluiceway of the discharge structures shall be kept clear.During discharging periods，upstream drift materials shall be salvaged promptly，and rafts and shipping shall be strictly forbidden to get close to the entrance of the structures.

11　The auxiliary facilities of the retaining and discharge structures shall be in normal operation.The discharging sluices and valves shall be kept intact with normal hoisting and reliable operating power.

12　If there are any dangerous defects such as abnormal cracks，distortion or water seepage in the retaining structures，they shall be dealt with promptly.