Dredging up solutions

The 84m high Tichi Haf dam in Algeria was designed with practical silt removal in mind. Silt, which is continuously supplied from the surrounding mountains, is collected at specially designed conical holes near the outlet valves of the dam. The resultant necessary dredging activities at the dam – which is owned by the Agence Nationale des Barrages et Transfers (ANBT) – are carried out by a Deep Cutter Suction Dredger, type DCSD350, supplied by Damen Dredging Equipment.

Upon completion of the dam in 2007, Damen Dredging supplied not only the dredger but also a complete turnkey system, consisting of a MultiCat dredging assistance boat, a complete Navguard survey system (with reference station, software and hardware for the dredger, for a survey launch and for post processing the collected data in the office), a complete floating and semi floating discharge pipe line which connects to the dam’s outlet valves, and a large set of spare parts.

According to the company, the Deep Cutter Suction Dredger is a versatile tool designed to specific customer requirements. The layout of the DCSD350 is such that it can be adapted easily to the different dredging conditions required. The main pontoon, which is equipped with a spacious day accommodation, the engine room and a raised control cabin, can be equipped with a hinged suction ladder, to which the DOP3530LD is fixed. The DOP submersible dredge pump is provided with a hydraulically operated cutter head. In this configuration the dredging depth is –16m. To the main pontoon, a separate fore pontoon can be added with its proper A-frame, in which the DOP submersible dredge pump with an extended ladder can be hung. The dredging depth is now extended to max. –30m. Another option is to mount the DOP submersible dredge pump to a cable, hanging in the A-frame of the main pontoon. The DOP submersible dredge pump, equipped with a special jetwater assisted head, now can be lowered to max. –50m.

The DOP submersible dredge pump delivers its 1.500-2.000m³/h of mixture to a deck mounted booster pump, which is driven by a 559kW Caterpillar diesel engine. Another Caterpillar diesel of 533kW powers the hydraulic and electrical installation as well as the jetwater pump. The entire dredging process is carefully monitored by the available dredging instrumentation: the dredging depth is indicated, the vacuum, intermediate and discharge pressure of the dredge pumps is shown and the production is monitored using the data generated by a magnetic inductive flowmeter and a density meter with radioactive source. The entire dredger has been designed as a modular system where all elements can be easily dismounted and transported – the maximum item size is a 40ft container.

At Tichi Haf dam, the DCSD350 will regularly pass by all the dam’s conical holes and clean them up, optimising maintenance and maintaining the capacity of the dam. The survey system delivered with the dredger will regularly check the levels of siltation. All survey locations and the required depths are entered in the Navguard survey system enhancing dredging efficiency.

www.damendredging.com