SHPP "Tserovo”

Bulgaria Engineering EAD provides consulting services related to project "Sredni Iskar" for the construction of nine (9) small hydropower plants of channel type along the middle course of the river Iskar. Currently five (5) hydropower plants have been commissioned. During the last third phase, the remaining four small HPP will be constructed.

Small HPP "Tserovo” is part of the second phase of project Sreden Iskar. The hydropower plant is of channel type, located along the Iskar River, in municipality Svoge. It has been constructed in the land of village Tserovo, municipality Svoge, Sofia district. The HPP has the following design parameters: net head 8,25 m, inlet water quantity 34 m³/s and nominal power 3000 kW. This is the first project in Bulgaria, executed with the innovative Kaplan bulb-turbine.

The construction of the small HPP „Tserovo“ - similar to the most channel HPPs - requires redirection of the river and execution of relatively deep excavations for the plant building and overflows. The site itself is located along a relatively wide section of the Iskar River and, contrary to HPPs Prokopanik and Opletnya, is not close to any roads, which in turn requires construction of a longer non-overflow dike acting as a barrage. The geotechnical works are divided into two phases using the jet grouting technology. It allows construction of nearly vertical slopes, allowing both reliability and watertightness of the excavation, as well as consolidation and strengthening of the foundations of the diaphragm of the non-overflow wall.

First phase - shifting of the river course only at the left part for construction of HPP building, overflow facilities and access road platform:

• Execution of three-row jet grouting columns along the dike longitudinal to the flow and dividing the river, as well as single-row jet grouting of the two transverse dikes closing the construction site;
• Reinforcement of the 1-st and 3-rd row columns along the longitudinal dike by means of steel micro-piles, embedded in the river bed;
• Execution of watertight diaphragm at the area of the HPP building, the overflows and the platform by means of jet grouting;
• Additional inclined injections at the lowest point (below the overflows).

Second phase - letting the river flow through the overflow facilities and gradual closing of the left part of the river for construction of the non-overflow dike:

• Execution of 3 rows of jet grouting columns along the axis of the non-overflow dike, acting as a core;
• Execution of a watertight diaphragm by means of 2-row injection below the columns;
• Tests of the watertight diaphragm and the non-overflow dike.

The construction began in June 2010 and the site was commissioned in June 2012.