Water channels were intended to solve the acute problem of water supply by redistributing natural surface runoff over long distances
In pumping stations with vertical pumps up to 1 meter in diameter, it is advisable to install them in a common receiving chamber. In this case, centrifugal pumps are submerged in water and equipped with a suction cone. A building of this type has simple forms, additional ballast from the weight of water, and better resistance to shear and overturning. There is no problem of combating water filtration into the building. When repairing a pump unit, it is completely taken (in foreign designs, the removable part of the stator and rotor) to the assembly site. This design of the station ensures much greater reliability of water supply than a design with small submersible capsule pumps.
Depending on the type of mounting, the pump can rest on the machine room floor or on special beams. A simplified machine building can be combined with a siphon outlet, a pressure chamber, or an outlet with a flap-type check valve. To enable repair of the check valve and increase the reliability of isolating the pump from the upper pool, a gate valve may be installed on the discharge pipe.
With separate mounting of the pump and motor, two floors are arranged. With a sealed connection of the pump flange to the lower floor, the space under the electric motor can be usefully utilized.
The conditions for water supply to the pump are improved by dividing the common flooded chamber into individual chambers for each pump. Separate walls increase the rigidity and strength of the building walls, and it becomes possible to inspect and clean the chambers of sediment while adjacent units are operating.
In pumping stations that, by analogy with similar layouts of headwork units of diversion hydroelectric power plants, can also be called diversion stations, submersible pumps usually operate on an individual short pipeline. However, in cooling systems of thermal power plants or municipal water supply, schemes of parallel operation of axial or diagonal pumps on a common conduit are sometimes used. In these schemes, check valves and gate valves appear as necessary elements.
Larger vertical pumps, as well as horizontal and inclined pumps, are typically installed in the dry underground part of the building, and water is supplied to them via a curved suction pipe.
In diversion-type pumping stations, the back wall usually has buttresses and two consoles – a foundation and an upper one. The foundation console is arranged to ease the foundation's working conditions and utilize additional soil load, while the upper console serves as support for pipelines and the room for electrical devices.
The building height is somewhat reduced when it is coupled with a water outlet with a mechanical shut-off device.
Consider the building of pumping station No. 2 of the Dnieper – Krivoy Rog canal, built to replace the previously existing one. The pumping station is designed according to a diversion scheme. The trash racks at this station are placed in a separate structure, so on the short piers there is only one groove for the emergency gate and protective screens.
The underground part, divided by a flat slab to which the pressure bend is attached, has plan dimensions of 31.5x12.9 m with a maximum height of 12.9 m and is designed as a rigid, box-type structure formed by a foundation slab, end and front walls, and intermediate floors; the rigidity of the structure in the direction of water flow is reinforced by separate piers of the suction pipes. The front wall of the upper pool is embedded with nozzles connecting the curved bends of the pumps to the metal pipelines.
The foundation slab houses the suction pipes and a drainage gallery. In the room at an elevation of 4.93 m, the main pumps OP10-145E, pumps ZKM-6 for fire-fighting water supply and for flushing the grooves (in the separate piers) and the suction pipe sill are located. On the floor at an elevation of 8.31 m, there are drainage system pumps 8K-12a, filter presses FP-3000 with a capacity of 3000 l/h, and an oil tank with a capacity of 2x10 m3.
The floor at an elevation of 13.10 m is the machine hall floor and assembly area, carrying loads from the electric motor, from the weight of dismantled equipment, and from vehicles when brought under the overhead crane. The floors at elevations 8.31 and 13.1 m have openings of 2.2x1.5 m for lifting equipment into the machine hall from the rooms at elevations 4.93 and 8.31 m, respectively. Stairs are provided for communication between floors. The underground part structures are designed in monolithic reinforced concrete.
A successful design for accommodating three to four units is the standard building of the Irtysh – Karaganda canal pumping station, developed by the OKB Gidroproekta. The enclosed-type building is located freely (without backfill) in the widened part of the supply channel. A service bridge is provided for communication with the shore and the unloading area.
Water supply to the building is circular (in a sector of 240 degrees). All units of the station are located in one block. The building shape is a dodecagon, with radial placement of units. Each unit occupies a 60-degree sector. The suction pipes are low, short, and wide; at the inlet, they are divided into two spans by piers. The suction pipe openings are covered by removable screens. During inspection or repair of the pump, flat sliding metal gates are installed in the same grooves. The gates and screens are serviced by a telpher with a lifting capacity of 5 t, which moves along a circular rail track mounted on brackets of the support columns of the superstructure.
The overlapping at elevation 19.55 m divides the building by height into the underwater part and the superstructure. The underwater part is designed as a box-shaped continuous structure with rigid fixing of piers, walls, and the central column into the foundation slab and rigid connection of floor slabs with external walls and the central column. The building height is 14.4 m for rock soils and 14.6 m for non-rock foundations. Building dimensions in plan: circumscribed circle diameter 21.56 m, inscribed circle diameter 19.8 m. The thickness of the external walls of the building is 1.0 m, the walls of the central hollow column are 0.46 m. The foundation slab with a thickness of 1.45 m for non-rock and 1.25 m for foundations on rock has sections with minimum thickness at the insertion points of suction pipes of 0.8 and 0.6 m respectively. In the sector of the suction pipes and drainage gallery, the foundation slab is a multi-span single-tier spatial frame of variable cross-section, whose posts are the walls and the crossbars are the suction pipe slabs with embedded suction nozzles of the pumps; the height of the structure is 4.17 m for non-rock foundations and 3.97 m for rock. The sector of the station building on the upstream side, free from suction pipe structures, is filled with soil with a 5 cm thick concrete cover.
The overlapping at elevation 12.5 m divides the underwater part into two rooms. The lower "pump" room houses instrumentation and control devices, drainage water and suction pipe dewatering pumps, drives for controlling drain valves, manholes into the gallery and into the suction nozzles of the pumps. This room is equipped with two telphers with a lifting capacity of 3 t each, moving along circular rails.
The upper room houses, in an isolated compartment on the upstream side, protection control and telemechanics panels and auxiliary power panels, while in the common room there is an oil tank and a rotary pump. Through this room pass the curved outlets of the pumps, and from here, from special platforms, the adjustment of pump blade pitch and servicing of the guide bearings of the pump shafts are carried out.
The ends of the curved outlets of the pumps are rigidly embedded in the floor slabs at elevation 12.7 m – the load on the slab is alternating, acting upward when the pump is operating and downward when it is stopped. The floor slab at elevation 19.55 m is the support for the electric motors and bears loads from equipment and from the building structures of the superstructure; in this slab, in its reinforced part on the upstream side, the outlet nozzles of the pump flow path are located.
Communication between rooms is via a staircase located in the central column. In the slabs, cargo hatches measuring 2.4x1.2 m are provided, through which technological and construction equipment can be delivered by the machine hall circular crane with a lifting capacity of 20/5 t from the unloading platform to the lower rooms.
Seepage water drainage is carried out through troughs located along the external walls, with subsequent drainage from the troughs into a drainage sump. The external walls of the buildings of most pumping stations of the Irtysh–Karaganda Canal are made of monolithic concrete. At stations No. 1 and 2, they are made of prefabricated reinforced concrete from panels 40 cm thick, with the subsequent construction of an external continuous casing 60 cm thick of monolithic reinforced concrete.
For pumping station No. 2, standing on a rock foundation, a design of an attached building has been developed. It retains the equipment layout with radial arrangement of units and the superstructure design. The underwater part adjoins closely to the rock excavation, the anchor support of the pipeline is moved towards the building.
In layouts using high-capacity vertical axial pumps, the pump station buildings have a significant height. With a linear arrangement of units, the buildings experience large horizontal loads and require the construction of retaining walls that limit the forebay from backfills and mandatory drainage of the latter. Designing the building in monolithic concrete is not difficult, but the use of prefabricated reinforced concrete entails a large variety of standard sizes of precast elements.
In terms of main work volumes and construction costs, the frontal type of building proved to be less economical compared to the building layout option with circular water intake. A serious drawback of the considered building is the large height of the underwater part, due to the low cavitation qualities of the axial pumps and their large height. This drawback is especially evident at stations drawing water from a canal with small water level fluctuations.
Other examples of pumping stations with large vertical axial pumps with impeller diameters of 250-260 cm are the stations of the Moscow Canal, the Karshi Main Canal, and the Kakhovka Irrigation System.
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