Construction of the left embankment of the Biała River, km 6+600-8+345, Koszyce settlement, Tarnów – Phase III construction works

Construction of a left-bank flood protection embankment on the Biała River in the Koszyce settlement: erection of an earth embankment and a reinforced concrete boulevard/wall, including functionally related flood protection structures. The earth embankment has a height of up to 5.5 m, a total length of 1,357 m, and a crown width of 4.0 m. A slope bench is planned in the section km 1+270 – 1+690. The water-side slope will be reinforced with bio-nonwoven fabric on 15 cm fertile soil and 5 cm humus, or with 30 cm thick mesh-stone mattresses on geotextile. The air-side slope will be reinforced by humification and grass seeding, or with 30 cm thick mesh-stone mattresses on geotextile. The embankment body will be sealed with a geomembrane on the water-side slope, and the subsoil with a 4.5 m deep cement-bentonite diaphragm (CDMM technology) or by jet-grouting (where utilities/culverts are present). An animal protection net made of galvanized steel wire (min. 2.5 mm diameter, 5x5 cm mesh) will be installed on the water-side slope, fixed with min. 30 cm long steel pins. The boulevard/wall is a monolithic reinforced concrete structure with expansion joints and stone cladding, total length 346 m. Included are 3 dry culverts (600 mm diameter pipelines) with precast reinforced concrete docks, 20 cm thick stone riprap for ground reinforcement, a rare grate at the inlet, and a check valve at the outlet. One road ditch reconstruction with culvert and reinforcements, one partial liquidation of a ditch bed and a new ditch section with an embankment culvert. Three embankment crossings (3.0 m wide road plates + 2x0.5 m shoulders, except for km 1+695 with asphalt concrete surface), 6 maneuvering areas, 1,275 m of technological roads (3 cm gravel surface on a 15 cm geogrid base filled with gravel on geotextile, 3.0 m road width between concrete curbs), slope stairs at 8 locations (precast elements adapted to embankment slope) and the removal of stairs at 2 locations. Linear drainage at the air-side slope along the embankment and boulevard using concrete channels and stone drainage with outlets. The river bank of the Biała will be reinforced in two sections: Section 1 (near Krakow Street bridge) with 80-100 cm heavy stone riprap on a 30 cm fascine lining and toe protection by wooden piles (15 cm diameter, 200 cm long), slope height 2-3 m. Section 2 (along the reinforced concrete boulevard) with 30 cm thick mesh-stone mattresses on geotextile, stabilized with wooden piles (10 cm diameter, 100 cm long), slope height 4-7 m. Another partial liquidation of a ditch bed and a new ditch section with an embankment culvert (1 unit at km 0+568 / river km 7+187) with an 800 mm diameter pipeline, precast reinforced concrete docks, 30 cm thick stone riprap on geotextile, wooden pile palisade, a rare grate at the inlet, and a check valve at the outlet. A road ditch reconstruction at km 1+697 of the embankment by constructing culvert No. 4 (600 mm diameter pipeline) with stone-paved inlet and outlet and a flanged check valve at the outlet. Additionally, environmental supervision is required, including monitoring before construction begins for protected plant and animal species and their habitats in the riverbed and flood zone. further items as per the tender documents.

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