|ENEL - PH Los Cóndores||References_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.
The existing Ritom hydroelectric plant, owned by the Swiss Federal Railways (SBB), has been using the gross head of more than 800 m between Lake Ritom and the powerhouse Piotta since 1920. The plant essentially consists of an intake, a penstock (L = 900 m, D = 1.7 m), a surge chamber and 2 pressure tunnels (L = 1400 m, D = 1.10 m) to the power house, where 4 Pelton units with horizontal axis and a total nominal capacity of 40 MW are installed.
The expiry of the concession in 2005, the age and wear of the electromechanical equipment as well as the continuing demand for electric power prompted SBB to study various options of renewal works and expansion of the plant.
The new project envisages an extension of the plant by replacing the existing turbines with new, more powerful turbines (2 Pelton turbines each with a capacity of 60 MW, Q = 2 x 8.5 m³/s) located in a new building next to the powerhouse Stalvedro owned by the Azienda Elettrica Ticinese (AET). In addition, a 60 MW pump unit (Q = 7.8 m³/s) will be installed to enable pumped storage operation of the system.
The existing headrace system will be abandoned, and the water will be fed to the machines through a new underground pressure tunnel (Q=20 m³/s).
In order to reduce the impact of fluctuating discharges into the Ticino river caused by the pumped storage operation, a new downstream compensating reservoir will be constructed.
The project also includes a series of environmental compensatory and landscape enhancement works in the Piora region and along the Ticino river.
The detailed design, with the common owners SBB and AET (Ritom SA) is scheduled to start at the end of 2019.
The Nenskra HPP is a hydropower project on the Nenskra River in the Svaneti region in Georgia, some 260 km north-west of Tbilisi.
The project includes the following main works:
- a 125 m high and 860 m long Asphalt Faced Rockfill Dam (AFRD), which will
impound a reservoir with a storage capacity of 176 Mm³, covering an area of
approximately 2.7 km²;
- a water intake on the river Nakra with a 12.5 km long and 3.5 m diameter
transfer tunnel, excavated with TBM;
- a 14.9 km long and 4.4 m diameter headrace tunnel, excavated with TBM;
- a 1.8 km long and 3.0 m diameter buried penstock;
- an outdoor powerhouse equipped with three Pelton units of 96 MW each, for
a total installed capacity of 288 MW (Q=46.8 m³/s). The gross head of the
plant is 725 m.
The EPC Contractor Salini-Imregilo engaged Lombardi to carry out basic design, detailed design and site assistance services.
In addition to the basic and detailed design activities, the following services, among others, have been carried out: revision of the project documentation including climate change topics, preparation of the Emergency preparedness plan during construction and operation, analysis of river flood scenarios and dam break analysis, geological hazards risk assessment for the project.
|Pamco Shura - Gilboa PSP, Expert assessment||References_5376|
Gilboa PSP is a pump storage plant in the Gilboa mountain in central-eastern Israel, at the border with the Cigiordania looking over the Jordan River valley.
Its scheme includes an upper reservoir at el. 427 m.a.s.l., an approx. 500 m deep shaft (dia 4.5 m), a 956 m long high pressure tunnel (dia 4 m, then 3 m at the feeder near the PH), a 2x150 MW turbines cavern with turbine el. -147.5 m.a.s.l. and relevant transformer cavern, a 1'512 m long low pressure tunnel (dia 3.6 m along the outlets from the PH and 5 m when unified) with a 95 m high surge shaft (lower dia 5 m H 21.5 m, with steel diaphragm, upper part dia 10 m H = 60 m) and the lower reservoir at el. -84 m.a.s.l.
After an initial construction phase assigned to a Korean contractor, the Client reassigned the finishing works (some excavation and the final lining of the shaft, the HP and LP tunnel and the concrete inlet and outlet) to the Israeli contractor (JV) Pamco-Shura already providing for the loose soil excavation portion and relevant lining and cut&cover portal at the lower reservoir.
Services to be provided to the Contractor are expert assessments regarding the water leakages and the head loss along the powerplant, and repair works on waterway concrete linings.
The hydropower plant is located in the Los Andes and Panama farms, in the municipalities of Patulul and Santa Bárbara, Department of Suchitepéquez, Guatemala, about 70 km from the Pacific Ocean and 130 km from Guatemala City.
The plant uses the water of the river Coralito and comprises two intake works, a 1 km long low-pressure conduction (Ø 0.8 m), a daily compensation tank (V = 3'350 m³), a 3.5 km long penstock (Ø 0-7 m), a powerhouse with a horizontal-axis Pelton turbine and a discharge channel to the Coralito river.
Both intake works are equipped with "Coanda" screens, with a capacity of 0.25 m³/s and 0.60 m³/s respectively; the design flood is 25 m³/s and 120 m³/s. Both the low-pressure conduction and the penstock are made of glass fiber reinforced pipes (GRP). The low-pressure conduction has diameters of 0.45 m (first stretch) and 0.75 m (following stretch), the penstock of 0.70 m; the pipes are buried over their entire length.
The expected annual power generation amounts to about 12 GWh, with a design flow of 0.85 m³s, a net head of 291 m and an installed capacity of 2.1 MW.
Lombardi services for the project consisted of the prefeasibility study, the feasibility study, the preparation of the tender documents, owner's support during the awarding of contracts, the final design, the technical site supervision, the detailed design (constructive) and the project administration of the project.
The plant is in operation since 2014 and Lombardi continues to provide management services for the operation and maintenance of the plant.
|Frankonedou and Kogbedou HPP||References_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.
|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.
As part of the concession renewal of the hydropower plant Dietikon the main central will be completely renewed.
The two existing vertical Kaplan units of the years 1931/32 will be replaced by new units of the same type. The raking system will be replaced by a new horizontal rake, which creates optimal conditions for the fish bypass and allows additionally the transfer of floating debris. For the fish ladder a special slot passable for salmon is provided below the boat ramp.
In order to be able to fully use the significantly higher ecological flow, a new power plant (bulb turbine), including a fish ladder with a special slot passable for salmon, will be built at the existing weir.
The EIA 1st stage (concession project) for the concession renewal was submitted to the building directorate of the Canton Zurich in June 2014.
The construction permit has been delivered in March 2017 and the works on site should start in early 2018.