Planned events

In order to maintain the river in a state that ensures its ecological well-being, this project provides for the following activities: cleaning the water area of ​​the river from explosive objects; cleaning the bottom from foreign objects; cleaning the bottom from bottom sediments; Clearing the river bed (section - from source to mouth), 4670 m long, 20-40 m wide, is carried out to a depth of 2,75 m BS with a hydraulic slope of its calculated water level (see Volume 4 longitudinal design profile). The slope of the river bed according to the project is 0,0000107. The last time the river bottom was cleaned from bottom sediments was in 1997-1999. The drift of the river to critical levels occurs after 6-8 years. The channel should be cleared regularly, in accordance with monitoring data (on drift, qualitative composition of water and bottom sediments, overgrowth of algae, etc.) after the development of an appropriate project, including engineering surveys in accordance with the Order of the Committee for Nature Management, Environmental Protection and ensuring environmental safety. Carrying out dredging works on the rivers and canals of the city will solve the following problems: improve the ecological and hydrobiological parameters of the city's water bodies; to prevent secondary pollution by accumulated bottom sediments of the aquatic environment of the river delta; create conditions for ensuring sanitary and epidemiological parameters of the city's aquatic environment; improve the recreational environment in the area of ​​the river and create the necessary conditions for using it as a transport artery for a small fleet. The planned volume of dredging works in the water area of ​​the river up to the design level of the watercourse, according to calculations, for soils of natural composition is 64059 m3, excluding enumeration. The volume of work performed is determined by calculation, by comparing mathematical models of the bottom according to preliminary and executive measurements, taking into account the allowable searches of no more than 0,2 m. Previously, before the start of work, depth measurements were made to determine the volume of dredging work. The project provides for the storage of the developed contaminated soil on the dump of bottom sediments at the mouth of the river. Schematically, the volume of the developed soil, distributed by pollution classes, located along the entire length of the river, is shown in the bottom sediment pollution cartogram by hazard class. The study of bottom sediments according to SanPiN 2.1.7.1287-03 showed the impossibility of further economic use of the extracted soil.

Technology for cleaning the bottom from silt deposits

In order to reduce the degree of negative impact on the environment, the most environmentally friendly scheme of work has been adopted. In the water area free from communications, the bottom is cleaned of silt from the water by dredging equipment - a single-bucket clamshell dredger with a capacity of 50 m3 / h with loading of the developed bottom sediments into scows. On 80% of the water area, the river is crossed by various kinds of communications (see the building plan, book 5). In the protection zones of communications, the development of bottom sediments by a KZR-type dredger (dredging and washing out complex with a soil pump capacity of 400 m3 / h for water, an average productivity for erosion on soil in dense addition of 8 m3 / h and 30 m3 / h for suction) has been tested and successfully applied. Part of the bottom sediments (10% of the volume developed in the protected areas) is washed off by a hydromonitor with the help of divers. KZR with a hydromonitor installation develops bottom sediments outside the buffer zone into a pit, previously prepared by a clamshell dredger. The dredger develops soil in the pit to the design level, downstream from the buffer zone. Bottom sediments are loaded into scows by a dredger. For the production of works on the development of bottom sediments along the embankment, an additional nozzle is provided for the trunk of the hydromonitor (part of the KZR) with a bend at an angle of 45o. To reduce the angle of inclination of the hydromonitor shaft and bring the jet closer to the bottom of the watercourse, two removable inserts 1 and 1,5 m long are provided, the angle is adjusted using a winch “for lifting the hydromonitor shaft”. Placement of the extracted soil is provided for on the dump of bottom sediments, located at the mouth of the river. Water areas free from communications alternate with buffer zones of various kinds of obstacles (cartogram of volumes for silt removal).