Spillway device

The spillway wellSPILLWAY DEVICE (EN: spillway installation; DE: Wasserablaßvorrichtung; FR: installation d'evacuation d'eau; ES: instalacion de vertido; RU: водосбросное устройство) serves for the diversion of the clarified water beyond the limits of the aggradation structures (dams, hydraulic waste dumps, storage facilities for the tailings, and so on), and for the passing of the freshet and rainstorm waters.

They distinguish the following spillway devices: the spillway (stoplog) wells (most used), floating pump stations, and others. The choice of the method for the diversion of the water depends on the type of the aggradation built structure, on the scheme for the water supply, on the particle size composition of the pumped rock, on the degree of the clarification of the water. In general, the structure of the spillway device is determined by the necessary throughput for the clarified and freshet water, by the height of the structure, which is constructed using the hydraulic method, and by the sizes of this structure in the horizontal plane.

They construct the spillway wells (most often with the size of 1.25x1.25 metres in the horizontal plane) mainly of the wooden frame structures, less often of the reinforced concrete elements and bricks. They use the wooden wells during the aggradation of the hydrotechnical structures with the height of up to 10 metres with the small duration of operation; in case of the height of more than 10 metres, they use the wooden wells with the sectioned metallic pipeline within the well (during the process of the aggradation, the space between them is filled with the soil). The clarified water is discharged into the well over the threshold, which is formed using the stoplogs (the beams or wooden boards, which are stacked one onto another into the slots on the struts of the frame of the well, or which are nailed to these struts), and this water is diverted from this well beyond the limits of the surrounding dam using the free gravitational flow through the spillway pipeline (see the Figure). The bottom of the well is constructed as the double wooden floor with the foundation, which is made of the layer of the gravel and sand. In case of the existence of the permeable soil foundation, they construct the reverse filter under the bottom of the well. Depending on the bearing capacity of the soils within the bed of the aggradation structures, they install the wells onto the pile or crib (the shell of the logs or beams, which has been filled with the stone or gravel) foundation. For the connection of the water diverting pipe with the wall of the well, they use the multi-layer tarpaulin couplings, which have been impregnated with the bitumen. Depending on the required throughput, the spillway wells are constructed with one, two, or three sections. For the ensurance of the safety of the works, and of the conditions for the passing of the freshet waters, at the dumps for the hydraulic wastes, besides the major floating pump station, they include the reserve stations, and the monitoring spillway wells.

They situate the spillway device within the zone of the most clean water of the settling pond, within the places, which are allowing us to use the water diverting pipes with the minimal length. For the prevention of the clogging of the spillway device, they install before the spillway device the fencing, which has been made of the metallic wire mesh, or the floating fencing, namely, the booms, which have been made of the logs. The spillway devices are served using the boat or the special pontoon. The failure of the spillway device leads to the pollution of the external sources of the water, and to the emergency status of the aggradation structure. Sometimes they use the spillway device for the intake of the water.