Odeleite Dam
The design and construction of these projects consisted of the following elements:
Odeleite Dam
Located in the District of Castro Marim, this is a dam with a rockfill embankment with a reinforced concrete water proofing layer on the upstream wall.
The principle features are:
- The crown extends over 350 m and is 12 m wide;
- Maximum height above the base is 65 m;
- Incline of the upstream slope: 1.3/1 (H/V);
- Incline of the downstream slope: 1,4/1 (H/V);
- Area of the upstream slope: 22,800 m2;
- Volume of compacted backfill: 1x106m3.
The area of the hydrological basin in the dam section is some 352 km2 with a volume in an average year of the order of 89 x 10 m3 which corresponds to an outflow of 253 mm. Modular flow is 2.8m/s.
The location and the elevation of the crown of the dam required the construction of a dyke on a porch on the left bank and an embankment in a valley on the right bank. The embankment, which operates with balanced hydrological loads both upstream and downstream, is the result of the need for the reestablishment of road links since the EN 122 became submerged on its accesses to the existing bridge. The crown for these works is located between the 63 and 75 m elevations .
The Odeleite dam is made using rockfill with a concrete waterproof seal located on the upstream slope, resting on a concrete plinth. The 12 m wide crown extends for 347 m at an elevation of 55 m. The height of the dam from the lowest point of the foundation is 65 m.
To facilitate the construction of the dam, the Odeleite was diverted using a horizontal horseshoe slab chamber with a section 7.7 m in diameter. Two abutments were built, the first upstream with its crown at an elevation of 17.3 m and the second downstream at an elevation of 11 m. The return used a dissipation basin with a trapezoidal section and an initial width of 14 m later extended to 24m with a length of 45 m.
The temporary diversion flow corresponding to a return period of 50 years is 485m3/s.
The frontal overflow sluice gate runs along the left hand side with a crest at an elevation of 42 m. It has two spans of 6.7 m fitted with automatic control sluice gate segments. On the downstream brow of the overflow discharge is a 45 degree shaft which flows into the temporary diversion chamber, discharging into the dissipation basin.
The temporary diversion chamber was subsequently adapted for the depth discharge, bringing to an end its use as a temporary diversion for the river, the chamber was closed off by a slab where the discharge at depth was located with a maximum flow of 50 m3/s.
The dam has a crown at an elevation of 55 m. The full storage level for the reservoir (NPA) is 52 m, the maximum level (nivel maxima de cheia – NMC) is at an elevation of 54 m and the minimum operational level (nivel mínimo de exploração – NME) is 26 m.
The area flooded by the reservoir at NPA is 720 hectares. The total volume stored is some 130 x 10 m3 while the useful volume is around 117 x 10 m3. The control ratio for the reservoir is 1.31 for the flows from the hydrographical basin.
A minor water outlet was also made on the Odeleite reservoir alongside the dam on the left bank. This is used for the irrigation of some 250 hectares of fields by the Odeleite up to the banks of the Guadiana.
This outlet comprises of a rectangular tower 2.o x 2.0 m2 total section with three 0.9 x 0.8 m2 openings at elevations of 26.5 m, 35.5 m and 44.5 m. The sluice gate is operated from a platform located at an elevation of 55.0 m and connected to the bank by means of a 50 m long x 1.6 m wide walkway.
The Odeleite Dam was followed by these subsequent projects:
Beliche – ETA Tavira Inlet
The following constructions were carried out at this stage of the project:
Beliche Reservoir Water Inlet: a reinforced concrete tower with a pentagonal section and a height of 33 m with three capture levels and openings equipped with sluices and gratings;
Beliche Tunnel • EE1: some 350 metres in length between the water inlet and the Number 1 balance chimney with a section identical to that of the Odeleite - Beliche Tunnel;
Equilibrium Chimney nº1: with a circular section and internal diameter of 11 m and 41 m in height;
Pumping station EE1: equipped with split body, horizontal axis electro pumps with variable speed motors: 4 of 2.6m3/s and 2 de 1.3m3/s, maximum pumped flow of 10.4m3/s, average elevation height 80 m. Installed power 14 Mw. 60 KVA substation;
Stretch of Pipe: of some 560m, from the EE1 to the Equilibrium Chimney Number 2 in reinforced and pre-stressed concrete pipe of DN 2500 mm, with rubber cord sealing joints;
Equilibrium Chimney nº 2: with a circular section and internal diameter of 11 m and 30 m in height;
Stretch of pipe: reinforced and pre-stressed pipe with rubber cord sealing joints of DN 2500 mm, some 25 km in length to the EE2, sized for pressures up to 1.4 Mpa and backfills up to 4 metres in height; along the length of the pipe are flow outlets for irrigation using 6 outlets with MONOVAR flow control valves;
Pumping station EE2: blower fitted with 3 horizontal axis 2.1m3/s electro pumps with elevation of 10 – 13 m. Installed power of 1.2 Mw;
Stretch of pipe: reinforced and pre-stressed concrete pipe with rubber cord sealing joints, DN 2500 mm, almost 3 km in length to the reservoir;
Sto. Estevão Reservoir: open air, hilly type, built using a perimeter dyke with variable heights between 0.5 and 15 m with a total capacity of 150,000 m3, surface area of some 2.8 hectares, covered with HDPE type plastic geo-membrane including a series of hydraulic security devices and outlets for the various users;
Pumping station EE3-U: installed at the reservoir, pumps the water to the Tavira ETA, equipped with horizontal axis electro pumps: 2 x 1.1m3/s and 2 x 0.55 m3/s. Elevation 21 metres. Installed power 900 Kw;
Stretch of pipe: for the supply of water to the Tavira ETA in DN 1200 mm reinforced and pre-stressed concrete with rubber cord sealing joints some 1.8 km in length.
Odeleite – Beliche Tunnel
The Odeleite and Beliche reservoirs are connected by a tunnel so that they can operate as communicating vessels. The tunnel has a chamfered corner portal type section, 3.3 m in length and a useful height area of 9.5 m. Maximum flow through the tunnel is 25 m3/s.
The elevation of the Odeleite reservoir floor is 23 m, while that of Beliche is 26 m. The tunnel stretching for some 2950 m was clad in full with reinforced concrete.
Significant dimensions:
- Rectilinear length 2,958 m;
- Area of the excavation section of 17 m2;
- Section area after final cladding with reinforced concrete: 9.5 m2;
- Circular upstream and downstream shut-off towers with an internal diameter of 4 m, average wall thickness 0.3 m and height 32 m.
Tavira Water Treatment Station (1ª Stage)
Providing treatment of water supply to Sotavento Algarvio with a maximum production capacity of 2.2 m3/s. At this stage drinking water production of 1.1 m·/s is expected.
