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Adjudicação de rede de rega pela ARBI

17/03/2014

Award of irrigation system by ARBI

The purpose of this contract is to build two separate irrigation systems, with buried pipes and two separate water intakes, located in the Castelo Branco district, in Idanha-a-Nova, in the area to the south-west of the agricultural use area in Ladoeiro parish.

Award of irrigation system by ARBI

Distribution network

The current irrigation system is supplied by a gravity network composed of open channels. When the contract is complete, the distribution will be via low-pressure pipes.

The pipes for the distribution network will be made as follows:

  • Diameters less than or equal to 500 mm - high-density polyethylene with butt welding;
  • Diameters greater than 500 mm - ductile cast iron with automatic joints;

Water intake in the cannel for the tank

In order to cover the insufficient drainage identified, it was decided to build a new derivation structure for the tank.

This new structure will include:

  • A transition chamber between the cannel and the pipe, made of reinforced concrete;
  • A buried polypropylene pipe, Ø 630 mm, SN 8;
  • A reinforced-concrete dissipation structure, hook-mouth type;
  • Protective rockfill at the outlet from the structure;

Tank extension

The capacity of the tank will be increased so as to improve the response to farmers’ needs, which on many previous occasions it has not been possible to meet.

Water intake for irrigation

The intake for irrigation will also be refurbished, involving the following main tasks:

  • Increasing the dimensions of the intake orifice, removing the existing grille and fitting anew grille;
  • Dismantling the existing winch, removing and preparing a rustproofing treatment for subsequent application;
  • Dismantling the current gate;
  • Extending the orifice of the intake to Ø 800 mm and supplying and fitting a new gate;
  • Removing the slab and auxiliary walkway and storing for subsequent reuse;
  • Excavating the trench for the tank in the area of the water intake until the level of the current pipe is reached;
  • Dismantling the current pipe;
  • Laying a new reinforced-concrete pipe (Ø 800 mm);
  • Installing a scour outlet with a diameter of 250 mm at the end of the water-intake pipe.

Filtration plant

Immediately afterwards, downstream from the irrigation water intake, a filtration station will be built on the tank in order for the equipment installed in the network to function properly, particularly the valves and vents. The filtration station, made of reinforced concrete, will receive the supply via the water-intake pipe.