Building of a fish pass designed as bottom ramp and slope
Ropa River – km 39+400
place: Ropica Polska
Planned term of start:
IVth quarter 2018
Planned term of end:
Ist quarter 2019
3 701 843 Polish zloty
Why do we interfere in a river?
Weirs on the Ropa River on km 39+400 were built for the maintenance of constant water damming serving water intake for Gorlice and Ropica Polska. They are insurmountable obstacles for aquatic organisms. The modernization of this structure is necessary.
The structure consists of three parts – two weirs and the bottom diaphragm wall. The upper concrete weir has damming height about 0,9 m and the second one for about 1,15 m which is made, like a bottom diaphragm wall, from Larsen steel sheet pile cofferdam. Banks between the weirs are protected by concrete plates and below by a stone overlay. A level difference of water table between the upper weir and the bottom diaphragm wall equals about 5 m and the distance between them is about 33 m.
As a modernization of the old structure, only the upper weir with reductions of lower water level will remain. Below the weir a new, two-part fish pass with the length of 114 m will be made from boulders. In the middle of a riverbed at the right bank, a bottom ramp and slope will be created with pools made of different size boulders. Between them apertures will be left making it possible for fish migration.
The left part of a fish pass will be shaped as a stone rapid made from boulders with appropriate distances and sloping making possible larger fish species migration. In the existing weir, a cutting will be made which will create an inlet of water to a fish pass.