Water supply for Sóller
This project consists of carrying out a set of measures necessary for taking in the waters flowing from Ses Fonts de Verger, more commonly known as Sa Costera, and that of the surplus from Torrente Major de Sóller, as well as building the necessary infrastructures for the use thereof in replenishing the S'Estremera aquifer and connecting the supply systems of the urban centers of Sóller, Bunyola, Palmanyola and Palma.
The average annual catchment achieved by way of this project amounts to 10 Hm3/year, representing nearly one fourth of the city of Palma's annual consumption.
In order to be able to catch the water, a loading chamber was built right at the outlet of the natural fountain serving to prime the underwater pipe. This chamber occupies an irregular are of 250 m2 with an interior clearance of 1.80 m. The loading chamber is connected to the underwater pipe. The underwater-to-land connection is made insider a collection box serving as a stopcock chamber, the scraper chamber, where the control, power generation and hydro-mechanical elements are located.
Once the water has been collected, it is transported by means of an underground pipe measuring 9,670 m in length, designed for a flowrate of 1.4 m3/s, leading to mouth of the Major current into the bay at Soller port. Through a steel pipe, it flows up the current, buried in a trench, over a length of 640 m up to the new storage which has been built beside the current.
The underwater pipe rests directly on the sea bottom, except in the vicinity of the coastline, where it is laid inside a trench. For digging the trench, it was necessary to dredge a length of 800 m in Sóller Bay and 100 m in Sa Costera. The trenches are 2-4 m in depth and 3 m. in width at the bottom.
For the dredging, the means employed were those suited to the type of land encountered, ranging from sandy bottom and loose soil in Sóller Bay, to large rocks in Sa Coaster. For dredging, a backhoe was used on a spud pontoon equipped with a grab and buckets Also, on the Sa Costera side, it was necessary to break up some large rocks which were lying along the designed path of the pipe by way of work doneby divers equipped with immersible jackhammers and chemical expansion bolts, plus the support of the Multicat ship.
The processing of assembling and laying the underground pipe is a complex process. This work was done using the Crawler, measuring 145 m. in length by 34 m in breadth, with a draught of solely 14 m.
The underwater pipe was shielded to prevent the wave effect in the vicinity of the breaking area. On Soller Bay, which is a well-protected area, the protecton consists of covering the pipe directly with the material from the dredging process. In the Sa Costera area, due to the force of storms, it was necessary to protect it to a greater degree. For this purpose, in the emerged area, a solution comprises of 2 rockfill beds reclaimed in the area proper was built.
In addition to the flow of water from Sa Costera, another flow of water which can be harnessed, pertaining to the surplus of the Major current, also flows into the new Sóller tank. The water is collected by means of a surface catchment in the current proper in the area known as S'Olla. By means of a pipe 600 mm in diameter, following 3,275 meters of trenched piping, the water flows into the new Sóller tank. This pipe is designed for transporting 0.4 m3/s, the annual catchment rate being estimated at 4 Hm3/year. The tank, occupying an area of 7,000 m2, is divided into 2 modules, respectively of 2,600 m2 and 4,400 m2. The volume of water stored totals 21,000 m3. Attached to the larger module is the pumping station, which has been built as an independent reinforced concrete structure, inside which the equipment for delivering the water to its final points of destination are located. The main pumping sends the water toward Palma and the S'Estremera wells, following load break in Alfabia, the Soller pumping serving as a back-up for the supply to the town of Soller.
The main pumping is comprised of an 8+1 pump system, 850 KW power, powered at 6,000 V, each capable of delivering 230 l/s flowrate at 265 m altitude. At full throttle, the system is capable of delivering 1.8 m3/s.
After being impelled over 9 Km, the water reaches the Alfabia load breaking chamber, not outside of the Soller Valley. The water is impelled over a length of 3,870 m inside a pipe on the inside of the Major current up to the header tank in the municipality of Soller.
A 66 Kv electric power substation has also been built, occupying the upper level of the pumping station at +8msnm. The installed power totals 12.6 megawatts.
The water from the Alfabia chamber flows by gravity after 14,575 m to the Son Pacs water tank in Palma. This main line has 3 branches branching off from it at different pints. The first, 2,657 m in length, is for supplying the municipality of Bunyola. The second, 32º m in length, is for connecting to the Palmanyola municipality supply system. The third, 3,700 m, is for carrying water to the parcel of land on which the S'Estremera aquifer wells are located.
This project is outfitted with the hydro-mechanical equipment necessary for controlling flowrates and pressures. The entire facility is automated and controlled by means of 12 remote stations interconnected with closed optical fibre loop and connected to the Son Pacs control center.
In this project, due to the fact that the worksite is located in an area of maximum environmental protection, all measures taken have been aimed at causing the least possible environmental impact and adapting to the currently-existing environment. The environmental integration of the structures is achieved by means of exterior finishings with local materials. Meticulous work has been done which has culminated in this structures built being perfectly well-adapted to their environment.