Guadalix de la Sierra is a town from the Community of Madrid, located in “Cuenca del Manzanares” region, in the Sierra of Guadarrama. Recently, the municipality has been through a great growth caused by factors such as the rural tourism, favoured by public transport.
A water treatment plant was decided to be built on the 80s in Guadalix. Before the construction, waste water was thrown without treatment to Pedrezuela Reservoir. Nowadays, after treatment, water is thrown to Guadalix River, which is a Jarama´s tributary. Two hundred meters away from the treatment plant is placed that Reservoir (also called Vellón Reservoir), that exists thanks to a dam built in Guadalix River. That reservoir harbors huge biodiversity and allows the practice of aquatic sports. Pedrezuela Reservoir is included in “Reservoirs and Wetlands Catalogue” in the Community of Madrid, by 7/1990 law of 28th of Jun, about Reservoir and Wetlands Protection in this Community. The Ordinance Plan establishes a list of standards and use conditions, focused on promote its natural values and consequently, protect its hydraulic resources.
Pic. 2: Picture of the plant taken outdoors
It seems a regular construction, but it is not. The plant is located inside the town, near a residential area, a sports center and a park. There is a significant and disgusting smell nearby the plant, even more when it is hot. Furthermore, it is absolutely visible from the street (some years ago, there was a cypress fence). I bring this topic because I have wondered why they built a waste water treatment plant so close to the municipality instead of put it a little bit distant, so it does not disturb the neighbors living there.
Pic. 3: Guadalix in a 1:50000 map
Why the Project was placed there? It seems more reasonable to place the plant downstream its actual location, preparing for the future growth of the town too, but the engineers who objectified the project had a problem with the topography. Guadalix de la Sierra is situated in a valley and it is one of the flattest villages in the mountains of Madrid. This fact makes the waste water conduction very difficult, which is frequently done thanks to gravity.
Pic. 4: Panoramic view of the plant and nearest houses
The possibility of building the treatment plant in a further place would mean to bury it partially or completely. This decision would suppose important extra charges, because the slope needed by the pipes is bigger than the one the soil has (which is necessary to carry the waste water and self-cleaning of the pipe). In addition, the waste water entrance to the plant height is two meters above the arrival pipe height. There is a tank in this entrance and, when it is full, the water comes into the treatment plant (this fact means that the plant it is already higher than desirable). Furthermore there is another important problem. The entrance pipe has a 60 cm diameter, while the majority of modern branches have a 100 cm diameter. This incident makes pumping impossible (it would need an adaptation construction).
Pics. 5 and 6: sketch and image of waste water entrance to the plant
So, is there no solution to this situation? There is not to the plant location, due to all the reasons given. It is important to say that al the residential area was built after the waste-water treatment plant, so I conclude saying that the urbanisation developers should have thought alternative solutions in this situation.
Aurora GARCÍA GONZÁLEZ
Universidad Politécnica de Madrid