Subject

Reconstruction of the dam on the Witka River in Niedowo Performing author's supervision over the execution of the project.

THE PURPOSE OF THE INVESTMENT

The dam was designed and built along the axis of the earth dam, which was destroyed during the flood in August 2010. The damming structure is part of the thermal power plant PGE Górnictwo i Energetyka Konwencjonalna S.A. Oddział Elektrownia Turów with a capacity of over 150 MW. In accordance with the Regulation of the Minister of Environment of 20 April 2007 on technical conditions to be met by hydrotechnical structures and their location, the structure has been classified as Class I.

The goal was:

• restoration the damming of Witek's reservoir before the crash,
• ensuring water reserves for technological purposes of PGE Górnictwo i Energetyka konwencjonalna S.A. Oddział Elektrownia Turów,
• restoration of the recreational function enabling access to water for recreation centres located near the reservoir,
• restoration of the water ecosystem and natural conditions in the areas adjacent to the reservoir from the period before the disaster.

Scope of the development

The scope of the development included:

• reconstruction of the right-hand barrier connected by three-span weir with segmental closures and the left-hand barrier connected with the pumping station and hydroelectric power plant block;
•  construction of a new outlet building - labyrinth overflow with cascade and outlet basin, outlet channel and access and service roads;
• construction of a fish ladder;
• construction of control and measurement devices;
• an early warning system for flood risks;
• superstructure of the pumping station and hydroelectric power plant building;
• construction of emergency closures for drains of the existing drop building and equipping the segment closures with emergency drive powered from the power generator;
• power supply and electrical equipment of the damming structure.

Under the contract, a multi-variant concept was developed, an information sheet for the project, an environmental impact report with a decision on the environmental conditions for the implementation of the project (cross-border impact), water law reports on the execution of water structures and on specific water use with a decision on a water law permit, a construction project with a decision on a building permit, executive and cost documentation, work execution and acceptance specifications, preparation of tender materials and assistance in the selection of the Contractor for construction works. In the years 2013-2018 author's supervision was exercised during the implementation of the investment.

Basic parameters of the objects

1) Characteristic flows:

• NNQ 0,14 m3·s-1;
• SSQ 4,03 m3·s-1;
• WWQ 171,00 m3·s-1.

2) Dependable flow Qm = 371,00 m3·s-1.

3) Control flow Qk = 707,00 m3·s-1.

4) Concrete dam:

• I class of importance of hydrotechnical structures;
• backwater height 12,80 m;
• total length 214,10 m;
• width of the service road at the dam crown 4.20 m.

5) Labyrinth weir:

• length of the overflow edge 136.90 m;
• height of the overflow damming wall 5.00 m;
• transfer expenditure at NadPP Q = 77.00 m3-s-1;
• maxPP Q = 645.00 m3-s-1.

6) Three-span bridge over weir:

• one bay length 17,70 m;
• total length 53.10 m;
• load class C according to PN-85/S10030, permissible weight of vehicles up to 30 tons.

7) Fish ladder:

• total length of construction 330.60 m;
• level difference between the NPP and the lower water level of 12.80 m;
• flow rate at normal water damming level 0.30 m3-s-1;
• flow rate at higher water damming level 0.90 m3-s-1.
• equipping the fish ladder with a device for managing fish behaviour.

8) Extension of the pumping station and hydroelectric power plant building using the existing reinforced concrete frame structure. Above the level of the existing ceiling of the hall, a superstructure of one storey was designed. The extension of the hall was raised to the level of the superstructure over the hall with three separate floors.

• building length 21,85 m;
• building width 12,23 m;
• net cubic capacity of the building 3950 m3;
• four-storey building with rooms for permanent residence (servicing of the facility) and technical rooms, including 0.4 and 0.6 kV switchgears.

9) Release front locks:

• spindle gate valves with dimensions B×H = 1.00 m×2.00 m;
• load capacity of 8.00 m water column.

10) Reconstruction of drives of segmented closures:

• closure height - 6.60 m;
• span 6.70 m.