Pit Excavation and Arrangement of Fish Bypass and Spawning Channel of the Bagaevsky Hydroelectric Complex are Progressing at a High Pace

To excavate a pit for the infrastructure of the hydroelectric complex, installation of a grout cutoff of sheet pile screen is in progress. To date, backfilling and forming a hard surface of the cofferdam of the downstream side (the place where the water surface adjoins the hydraulic structure) have been completed.

Cofferdams are temporary pressure structures designed to protect the pit from flooding with water during the construction of a hydroelectric complex. Cofferdams of the upstream and downstream sides are made from soil obtained during the excavation of the gate pit. To date, backfilling and forming a hard surface of the cofferdam of the downstream side, which, in addition to the barrier function, is used as a road for transporting construction materials and equipment, have been completed. Compaction of the dumped soil along the crest of the cofferdam is carried out using compactors. The mark of the top of the cofferdams for BHC is 7.3 m as per the Baltic Height System (BHS), with account taken of the reserve in case of a flood.

Backfilling of the barrier dam of the fish bypass and spawning channel to the design level, which is almost 9 metre as per BHS, has been completed. The dam is arranged along the perimeter of the channel protect against erosion of the channel and floodplain of the river when floods come. That said, local soil obtained during pit and other excavations is used.

The meander shape of the FBSCh chosen during the design made it possible to get a fish bypass and spawning complex which includes both the channel itself and artificial spawning grounds – fish spawning spaces. Artificial spawning grounds or meanders for bream, carp, ram, roach, dace, and other fish species are located within the barrier dam and the route of the spawning channel itself. The internal territory of the FBSCh is divided into six sections (spawning grounds) of various areas from 2.24 to 8.54 ha. Layout planning of the spawning ground 2 with an area of 5.91 ha has been completed.

The high pace of construction became possible due to the implementation of the STG Production System aimed at increasing performance and quality, reducing construction time, and optimising production. During the construction of the Bagaevsky Hydroelectric Complex, for the efficient operation of special-purpose machinery, account was taken of the project features: large areas with no equipped roads. The optimal speed of all vehicles has been calculated, which makes it possible to reduce the likelihood of equipment breakdown and loss of operating time for simple and unscheduled repairs.