CONSTRUCTION OF AN ALTERNATIVE SUPPLY PIPELINE FOR THE KARDITSA WATER SUPPLY UNION FROM PLASTIRAS LAKE

The works to be carried out briefly include the following Civil Engineering and Electrical/Mechanical Engineering works: Pumping Station (P/S) – Water Intake Works The project is planned in the area where the water intake of the pipeline (tunnel) to the Plastiras Hydroelectric Plant is located, at an altitude of +792.00 m. The pumping station and the transformer building will be constructed from reinforced concrete C25/30. Counter-balancing air chambers are planned in the outdoor area. The pumping station rests on the circular water intake shaft, which will be constructed with interlocking caissons, diameter 1.20m, alternating between unreinforced and reinforced concrete C20/25. The internal diameter of the shaft, after the construction of the internal lining (wet chamber), is 6.20 m. The position of the multi-perforated water intakes is planned at a distance of 36.50 m from the axis of the pumping station shaft. The outlet shaft - water intake is planned there with interlocking caissons, diameter 1.00m, alternating between unreinforced and reinforced concrete C20/25, internal diameter 4.00m, after the construction of the internal lining. The connection of the two shafts is made with Φ600 water intake pipelines laid during the horizontal drilling phase using the pipe jacking method at levels +780.00 and +784.00. Internal configuration of the pumping station shaft – wet chamber is planned by constructing three (3) compartments of reinforced concrete C25/30 for the installation of the pumps and the configuration of the openings of the two water intakes. Force main from the Pumping Station (P/S) to the Charging Tank The length of the force main from the pumping station (P/S) to the charging tank (C/T) is 1986.03m. The pipeline made of HDPE pipes, 12.50 atm nominal diameter 630 mm, is laid continuously on an existing PPC access road with an average width of 5.50 m. Charging Tank Water from the project's pumping station (P/S) for water intake is pumped to the charging tank (C/T) approximately 2.0 km to the east at an average ground elevation of +865 m. The charging tank will be single-chamber with a total volume of ~600.00 m3. Pipeline with gentle longitudinal slopes - Section Ch. St. 0+000 ÷ 2+420.96 The pipeline is laid continuously on an existing PPC access road. An exception is a section of 120.31m with a longitudinal slope of ~44% which is laid in a trench within the zone to the left of the PPC penstock. In the section from Ch. St. 0+000÷1+300, a pipeline made of HDPE pipes 12 atm nominal diameter 630mm is planned. In the section from Ch. St. 1+300÷1+586.31 of the aforementioned 120.31m, with a steep slope, the pipeline is planned from steel pipes class X52 nominal diameter 450 mm with a wall thickness of 6.35mm. In the section Ch. St. 1+586.31÷2+420.96, the pipeline is planned from HDPE 12 atm nominal diameter 600mm. Pipeline with steep longitudinal slopes (penstock) - Section Ch. St. 2+420.96÷4+156 The pipeline is laid in a trench within the zone to the left of the PPC penstock. The pipeline along its entire length is planned from steel pipes class X70, nominal diameter 450mm and wall thickness 7.14 mm. For safe operation, the excavation of the pipe trench will be carried out with a tracked excavator, from upstream to downstream, and special tracked equipment (bulldozer or equivalent) will be provided to secure the excavating machine with a steel cable. Special provision of suitable equipment will also be required for laying the steel pipes in the trench, from downstream to upstream. The backfilling of the trench will be done progressively in sections, moving from downstream to upstream of the inclined section of the trench to be backfilled each time. Each section is defined between two consecutive stabilization works of the trench backfill and corrosion protection (trench break walls - 'kofters' - trench breakers). Pipeline with gentle longitudinal slopes - Section Ch. St. 4+156 ÷ 4+710.44 The pipeline along the entire last section under consideration, which leads to the offices and the PPC N. Plastiras Hydroelectric Plant, is planned from...