Pit for Spillway Dam Is under Construction at Bagaevsky Hydroelectric Complex

Pit for spillway dam

Primary activities are continuing at the construction site of Bagaevsky Hydroelectric Complex, one of the largest transport infrastructure facilities in Rostov Region. The Complex commissioning will help to resolve vessel navigation issues on the Lower Don by meeting the dimensional requirements for navigation; the Complex will also be used for the purposes of the fishing industry, as well as for domestic, industrial and agricultural water supply. Construction is carried out by Stroytransgaz Group under instruction of the President of the Russian Federation.

Wellpoint systems

The pit for a spillway dam is being constructed on Arpachinsky Island.  Dewatering measures are being taken to prevent the issue commonly encountered on hydroengineering construction projects — pit flooding and foundation washout by ground waters. Wellpoint systems are used to decrease the level of underground waters. These are pumping units consisting of wellpoint filters, water collector and a pump. As the depth of the pit increases, the wellpoint filters are re-installed in tiers. Dewatering and excavation activities are linked together cycle-wise. Once the water level has dropped, the ground is excavated, then dewatering and excavation are repeated. By now, the builders have reached -5 m elevation across the entire pit area. The wellpoint filters have been relocated to tier 2, and soil excavation down to -7.5 m elevation has commenced. While works are in progress in the pit, water is pumped out continuously. More than one million of cubic metres of soil have been excavated.

Larssen sheet pile sinking

The builders continue to construct the berthing channels required for the vessels to enter and exit the lock and await locking.

‘The mooring facilities of Bagaevsky Hydroelectric Complex are designed as an anchored bulwark. The faces of berthing channels (guide dolphins) are made of L5-UM Larssen sheet piles. As of today, the face wall of the left dolphin has already been completed at the head race, and the work on construction of anchoring slabs for the channel’s walls is proceeding on the opposite side. At the same time, we are working on the crushed stone wedge designed to prevent soil leakage through the holes in the sheet pile wall at the anchor rod fastening points in future’, says Stroytransgaz Construction Management Director at the Bagaevsky Hydroelectric Complex construction site Levani Khumarashvili.  
Similar works on construction of berthing channels are ongoing at the tail race. By now, 1,098 Larssen sheet piles have been sunk at the head race, and 557 — at the tail race.

Construction of the crushed stone wedge and the anchoring slabs

Dewatering and excavation works are continuing at the fishway/spawning channel construction site. In areas where this work has already been carried out, geotextile is laid and the bottom and slopes of the channel are reinforced with crushed stone. 27.9 thousand square metres of geotextile have been laid, and 13.4 thousand cubic metres of crushed stone have been filled by now.
The first slab of the flood bed is being poured at the main head regulator of the fishway (flood bed is an artificial bed facilitating the water flow). In the future, the main head regulator will function to maintain the optimal water flow in the fishway/spawning channel. Reinforcement work is being carried out on the remaining slabs of the flood bed and the retaining wall, designed to protect the channel from erosion by the river.

First flood bed slab pouring 

‘The work is in full swing at the site. 596 people and 154 equipment units are engaged. The work is carried out in two shifts, and creates no obstructions to navigation. At this stage, we pay special attention to construction of the main structures of the hydroelectric complex — the spillway dam and the twin lock’, says Deputy Director General for Rostransmodernizatsiya Company Denis Akhaev.

He also added that the start of construction of auxiliary onshore facilities and the settlement for the Complex’s operators is expected to commence in summer. They also plant to commence the construction of dams containing the water reservoir.

The Federal State Unitary Enterprise Rostransmodernizatsiya is the state customer of the project.

Background:

Race is an area where the water surface adjoins the hydraulic structure. The head race is upstream the river, the tail race is downstream.

Project background:
The Bagayevsky Hydroelectric Complex is the most important infrastructure project not only for the Rostov region, but also for the whole country. The hydroelectric complex under construction will be composed of a shipping lock with a central control room, upper and lower berthing channels with mooring assistance structures, a spillway and an earth fill dams, a meandering fishway and spawning channel and a fish passage lock, as well as industrial, service, engineering and auxiliary facilities, and housing for operating personnel. To ensure the navigation safety, channel-regulating dams are being constructed, as well as shore protection dams that will prevent the development of bank erosion processes (washout and collapse), protect from the impact of ship waves and reduce the negative impact of waters on the population living in these areas. In order to ensure guaranteed waterway dimensions (depth — 4 m, width — 80 m, bending radius — 500 m) in the section from the Kochetovsky Hydroelectric Complex site at the 3004.5 kilometre mark of the waterway of the Integrated Deep Water System (IDWS) to the Bagaevsky Hydroelectric Complex site at the 3089 kilometre mark of the IDWS waterway, dredging and river cut-off are envisaged.