Hydroelectric plants

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ENEL - HPP Los CóndoresReferences_5507
Los Cóndores is a 150 MW HPP, including a 12 km long headrace tunnel (4.6m diam, excavated by D&B and a DS hard rock TBM), a 120 m high surge shaft (6m diam), a 480 m high pressure shaft (2.6m diam), both being excavated using a raise borer machine RBM, and a 1.6 km long subhorizontal pressure tunnel leading to an underground powerhouse accommodating 2 Pelton units. The region is volcanic, with several active volcanoes in the recent geological eras. Maule Laguna volcanic complex is one of the major and the geological formation are essentially dacitic and rhyolitic lava field with rich tuff and volcanic breccia presence in subhorizonal sedimentation and several lava and basalt domes and dikes crossing these formations. Excavation of the upper waterway (HRT) is foreseen in two phases through a central adit by TBM, in order to shorten the time for accessing and execute the vertical works. During the excavation of the HRT lower reach, the TBM got stuck in a cohesionless material, likely the seat of a paleo-basin (syncline) or a paleo-canal within the lava and breccia banks. The services targeted the understanding of the situation, definition of the operations required for the TBM to be safely unlocked from the jammed conditions and option for realizing a bypass around the TBM in case no success was provided by other means. Because of the significant modification of the working program, the evaluation was required of the options for realizing the upper reach of the HRT by other mechanized means (second TBM) or other excavation method, given the logistic conditions at site. Possible optimization of vertical works, in terms of efficiency and realization concept was also part of the required services; in particular, a preliminary study considering 5 alternatives of the scheme combined with different excavation methods options (D&B and/or RBM) were carried out, in order to analyze the possibility to disassociate the construction of the vertical works from the TBM advance and to better manage the geological and construction risks associated with vertical works construction.
Chile
Coralito HPPReferences_3739
La centrale idroelettrica si trova nelle fattorie Los Andes e Panama, nei comuni di Patulul e Santa Bárbara, Dipartimento di Suchitepéquez, Guatemala, a circa 70 km dall'Oceano Pacifico e 130 km da Città del Guatemala. L'impianto utilizza l'acqua del fiume Coralito e comprende due opere di aspirazione, una conduzione a bassa pressione lunga 1 km (Ø 0,8 m), una vasca di compensazione giornaliera (V = 3'350 m³), una paratoia lunga 3,5 km (Ø 0-7 m), una centrale elettrica con turbina Pelton ad asse orizzontale e un canale di scarico verso il fiume Coralito. Entrambe le opere di aspirazione sono dotate di schermi "Coanda", con una capacità rispettivamente di 0,25 m³/s e 0,60 m³/s; l'inondazione di progetto è di 25 m³/s e 120 m³/s. Sia la conduzione a bassa pressione che la paratoia sono realizzate in tubi rinforzati con fibra di vetro (GRP). La conduzione a bassa pressione ha diametri di 0,45 m (primo tratto) e 0,75 m (tratto successivo), la paratoia di 0,70 m; i tubi sono interrati su tutta la loro lunghezza. La produzione annua di energia prevista ammonta a circa 12 GWh, con un flusso di progetto di 0,85 m³, una prevalenza netta di 291 m e una capacità installata di 2,1 MW. I servizi Lombardi per il progetto consistevano nello studio di prefattibilità, nello studio di fattibilità, nella preparazione dei documenti di gara, nel supporto del proprietario durante l'aggiudicazione degli appalti, nella progettazione finale, nella direzione tecnica del sito, nella progettazione esecutiva (costruttiva) e nell'amministrazione del progetto. L'impianto è in funzione dal 2014 e Lombardi continua a fornire servizi di gestione per il funzionamento e la manutenzione dell'impianto.
Guatemala
HPP on the Rhone at Massongex - BexReferences_407
The hydropower plant is planned on the Rhone near Massongex-Bex above Lake Geneva. It involves the construction of a new low-pressure resp. ron-of-river power pland for hydroelectric production as part of the sustainability strategy. The impound section above the mobile weir has a very small storage volume. The annual production is estimated at 75.5 GWh/year. The main works of the powerplant are the following: - Gated weir with 4 bays for flood discharge (2’500 m³/s) - a powerhouse located on the left bank, equipped with 2 units (Hmoy=7.79 m, Q=2 x 110 m³/s, P=2 x 7.5 MW); - consolidation of the river banks both upstream and downstream; - lowering of the river bed both upstream and downstream in order to increase the head; - a fish pass; - a small unit to turbine the attraction flow of the fish pass.
Switzerland
Frankonedou and Kogbedou HPPReferences_5113
The hydroeletric complex of Frankonédou and Kogbédou will be built on the river Milo, approx. 70 km from Kankan in eastern Guinea. The 37 m high Frankonédou dam (upstream) will impound a reservoir of 1'300 hm³, which will regulate the discharge downstream. The powerhouse, located at the dam toe, will exploit a max. gross head of 26 m. it is equipped with 2 Kaplan unit. The Kogbédou scheme, located approx. 30 km downstream of Frankonédou dam, will include a 10 m weir, an headrace channel ending with a concrete forebay, 2x 5.5m diameter penstock, an open air powerhouse equipped with two Francis units. The max. gross head is 29 m. The total installed capacity of the complex is 102 MW with a design discharge of 160 m³/s for Frankonédou and 200 m³/s for Kogbédou. The expected total power generation is 468 GWh/year. Both dams will include a concrete structure in the central part with the intake and outlet works and embankments on the banks.
Guinea
Santiago HPPReferences_1520
The design of the Santiago HPP on the Santiago river in Ecuador, realized by the Comisión Federal de Electricidad (CFE) of Mexico, consists of a 190 m high RCC arch gravity dam connected to an underground powerhouse equipped with 6 units with a total installed capacity of 3’600 MW. During the design phase, Lombardi has been charged with a technical assessment of the feasibility study and the basic design by the final client, Celec EP of Ecuador. The proposed design is very challenging in many aspects, like the installed capacity (the project will be the 19th in the world and the 3rd in South America), the magnitude of the flood (PMF=21'000 m³/s), the seismicity of the area, geologic challenges (such as the large unstable area on the right river bank downstream of the dam) and the accessibility of the area. Lombardi effectively collaborated both with CFE and Celec to optimize the design of the plant, working both on the general layout and on the details of the design of the individual components like the dam and all the underground works. The services provided by Lombardi required the collaboration of many senior experts in different technical fields.
Ecuador
Gere HPP - Lot 2References_5374
The Gere HPP was conceived in previous design phases as a traditional high-head scheme with a nearly horizontal, approx. 2 km long low-pressure headrace and an 800 m long buried penstock. The low-pressure headrace was designed as a tunnel with an exposed pressure line inside, being the tunnel intended also for acceding the headworks in the winter season. During the offer preparation for engineering services including tender, detail design, site supervision and commissioning, Lombardi as a member of the JV IGSL proposed a scheme modification with a 2.6 km long inclined tunnel from the powerhouse area up to the desander facilities and the Tirolean intake. The winter access function of the tunnel was maintained as in the original layout. The project was awarded to IGSL adopting this layout optimization. Drill-and-blast underground excavation was carried out from the d/s portal only. The tunnel portal is located close to the powerhouse, easily accessible and just approx. 300 m from the designated dumping area. After excavation completion, the GRP-line was installed in the tunnel from u/s to d/s. Site logistics could be dramatically simplified compared to the original project layout: the two cableways for conveyance of the excavation material to the dumping area and for penstock installation were no more needed and the project environmental impact could be further reduced. Lombardi was in charge of all conceptual and design project issues whereas our JV partner is responsible for project management and site supervision.
Switzerland
Solu Khola HPP (86MW)References_5903
The Solu Khola Hydropower Project is of the Run-Of-River (ROR) type. The project comprises an ungated 15m high and 31.80 m long concrete weir with a horizontal floor stilling basin built across the Solu river. The weir crest is located at elevation 1262 m a.s.l. A concrete intake is located on the left bank of the Solu river, formed by 3 orifices equipped with intake gates of 4.0 m x 2.0 m each. A gravel trap 5.0 x 5.0 m is provided behind the intake. Three underground concrete desilting basins (L x H x W = 85.0 m x 9.0 m x 5m), achieve a trap efficiency of 90% for particles larger than 0.15mm and include a S4 flushing system for cleaning of the basins. A 4500 m long partially concrete lined headrace tunnel (Inlet to Valve Chamber), D-shape (section 4.3 m x 4.5 m) and a 1850 m long steel penstock pipe (2.5 to 2.1 m diameter, including drop shafts and horizontal underground stretches) convey the water to the powerhouse located at the right bank of Dudh Koshi River at Maiku Besi. The powerhouse, housing 3 Pelton turbines is located about 1 km upstream of the suspension bridge across the Dudh Koshi River. A 375.0 m long inclined surge tunnel (D-shape 4.0 m x 4.0 m) is provided to reduce hydraulic transients in the pressure waterways. Between the surge tunnel and the penstock, a valve chamber equipped with a safety shut-off butterfly valve is provided. The project also includes 4 construction adits.
Nepal
Dietikon HPPReferences_2046
In autumn 2017, the canton of Zurich, after a positive decision for the concession renewal for a further 60 years, granted building permission for the refurbishment of the historical Dietikon run-of-river power plant. Construction works started in early 2018, whereby in the existing main power plant, both Kaplan turbines dating back to the years 1931/32 were replaced (new Q = 2 × 47.5 m3/s, HN = 3.4 m, P = 2 × 1.7 MW) and an ecological discharge power plant (Q = 25 m3/s, HN = 3.1 m, P = 770 kW) was built nearby the existing weir. Compared to the previous plant layout, from 2019, the new scheme generates 19.70 GWh/a, about 14% more than before. Particular attention was given to ancillary works that facilitate the free fish migration and ensure their protection. For the upstream migration, two new fish ladders were built, while the downstream migration is ensured through a trash rack with horizontal bars (B x H = 22.8 x 5.9 m, clearance 20 mm) before the main powerhouse and the adjustment of an existing ice channel into a bypass. The existing boat ladder was also replaced.
Switzerland
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