The object of the “Project for the Reinforcement and Adaptation of the Cañada Honda Dam to current regulations” is the definition, justification, measurement and valuation of the work needed for the adaptation of the Cañada Honda Dam to the current regulatory requisites with regard to dam safety.
Likewise, this project will permit administrative regularisation of the dam, in line with the Second Transitional Provision, point 1, of Spanish Law 12/1990, dated July 26th, on Canary Island Waters, through its registration on the Waters Register in the terms foreseen in the current legislation.
The work will consist of the reinforcement of the dam, maintaining its concrete gravity type, and to this end the following operations are foreseen:
- The gravity dam is of mass concrete (HM-25/P/100/IIb) and set on a curve formed by a succession of alignments which from the left margin are: reverse curve, straight line, curve and straight line. The reverse curve, 14.1 metres in length, has a circular radius of 15 metres, the middle straight section, of 3.7 metres, coinciding with the separation between blocks, the main curve of the dam, of 11.1 metres, is defined by a radius of 20 metres and lastly, the straight section making up the abutment of the right margin of 8.7 m.
- The crest length of the dam is 37.6 metres, its height is 12.5 m and the volume of concrete is about 1,265.20 m³. The group of plans 2.B.1 “General Ground Plans” includes the general concept of the work, with detail of the definition of the geometry of the dam ground plan in plan 2.B.1.2 “General Plotting Ground Plan”.
- The adjustment of the dam is based on taking maximum advantage of the existing dam, to reduce the volume of excavations and of demolitions, despite the uncertainties introduced as a consequence of laying the foundation of the future structure on an auto-constructed dam, since greater relevance has been given to the environmental point of view in the design of the work, given that we are located in a protected natural space, in this case the Nublo Rural Park.
- A spillway was designed in the project, formed by an interruption of the crest parapet of 3.70 metres measured on the generatrix of the arch, occupying block 5 located above the channel, with fixed lip design and with threshold at 895.60 metres above sea level. The spillway terminates with a flashboard, at 886.10 metres above sea level with a double function, to distance the drained flow from the foundations of the dam and to produce the necessary absorption of the potential energy generated.
- The depth drains are in Block 4, an annexe to the spillway on the right margin. They comprise 2 conduits of ductile cast iron, 300 mm in diameter, with a horizontal axis outlet at 889.10 metres above sea level. A maximum drainage capacity at project flood level is 278.41 l/s with exit speed of 3.94 m/s. These allow the reservoir to be emptied in about 15 hours. Opening the drains is performed by means of a sluice valve and a butterfly valve of 300 mm nominal diameter, arranged in an arc on the body of the dam, with an exit axis at 887.10 metres above sea level and a launching angle of 15º upwards.
- Supply points are in blocks 4 and 6, annexes to the spillway on both margins. Three points are available, built in galvanised steel with a nominal diameter of 100 mm. The point currently set at 887.10 metres above sea level is maintained and a connection is made to two new points at 889.10 and 892.60 metres above sea level, sharing the volume of reservoir exploitable from each one out evenly. Calculated annual demand stands at 4,484.35 m³.
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The technical specification sheet can be downloaded for more information: