In an effort to revalue the heritage of civil engineering, this article will try to give the importance it deserves to civil work which goes unnoticed for most, although it is located a few kilometers from Madrid. It is the ancient Santillana dam in the village of Manzanares El Real, which is almost entirely flooded by a more modern dam and is clearly deteriorate.
It has sought to highlight the importance of this hydraulic work from different areas, mainly on civil engineering and artistic-cultural.
The construction of the Santillana dam (1908) is included in a much larger hydraulic project undertaken by the Marquis de Santillana, whose objective was to provide water supply to Madrid and nearby villages, because The Isabel II Channel presented certain weaknesses supply. Besides, it was the first Spanish company that supplied electrical power to this city.
This project consisted of several dams located in the river of Manzanares, being the biggest and first of the Santillana and two smaller downstream, settling successive hydroelectric jumps. At the same time, they provided the required flow through an extensive network of pipelines in pressure and channels to supply Madrid, Colmenar Viejo, Alcobendas and other nearby towns.
In terms of the structural importance of Santillana Dam, it can say that is one of the first dams in Spain, along with El Villar, which is performed by using rational mechanics entering the analytical calculation of forces. It uses the theoretical profile of Sazilly, formed in the body section dam by an isosceles triangle, with the particularity that the cross section of the dam is formed by a vertical on the upstream face and parabolic arc that of downstream tangent to the hypotenuse of the triangle of Sazilly.
Figure 1: Photography of the antique Santillana Dam
In regarding to their hydraulic characteristics, the spillway is exempt body and it is located on the right riverbank, up to the crest of the dam and following a contour. As shown in the picture it has a simple lining on the left side of the body dam, running below the dewatering flow through the channel of the slope without any coating and reaching the channel restitution naturally.
Something stands out is the guideline of this dam, formed by two arcs of different curvature joined in the intake tower, saving two valleys there on site. At that time it was not known quantitatively how the arc contributed to resist efforts but it was suspected that giving this curvature to the guideline of the dam helped his stability. It is for this reason that presumably the designers of this dam did not dare run with a single curvature but preferred to rely on that little mound that divides the two valleys, constituting the peculiar guideline.
The artistic-cultural sphere, the dam is historicist recreating the artistic style of Manzanares Castle located in the next town. No doubt the intake tower is the most characteristic element of the dam, its height and aesthetics, and now to be the element that does emerge from the flood. It rises at the confluence of two sections; it reaches 35 meters tall and is octagonal in shape, decorated with stone balls on all sides as having the homage tower of the said castle.
After emphasizing the many singularities involved Santillana Dam, no doubt that it takes part of Madrid’s historical, artistic and engineering heritage. The big question is why not having preserved this great civil engineering part of the history of the Spanish capital. There are examples where was preserved the previous work such as Puentes III Dam on the Guadalentín River, placing the current dam upstream from its predecessor.
In the case of Santillana it was not thus, the current dam was constructed downstream in 1969, flooding the old one. Between possible reasons why it was run downstream the historical dam, geological or geotechnical reasons are discarded because the bedrock in the area is very competent to be composed of igneous and granitic rocks, so in broad strokes there is no problem to do the dam upstream.
In terms of the topography, although the length of coronation is somewhat larger and it would increase its cost, the location upstream of the dam continues to be quite good as far tightness is concerned, as shown in the following picture. What’s more, it can be built a gravity dam equipping, in any case, a guideline with a single curvature and not actually executed, in a way that does not help efforts to resist or adapt to the curves of her neighbor.
Finally one of the factors that could tip the construction of the dam downstream is increasing reservoir storage capacity with this location against the alternative upstream to lose some of its capacity.
Therefore, it is concluded that the construction of the new Santillana Dam at the site downstream is mainly due to reasons of cheapening the cost of the body dam and increase the stored volume, all this next to a still undeveloped professional awareness about built civil heritage, did which in its day it was lost a hallmark that marked the social, artistic and technical development of that epoch.
Carlos Javier Serrano Casillas
Andrea Pérez Velasco
Estefanía Villamayor Buzón
Mar Gesé Bordils