Cornerstone
of a new
HEP powerhouse

budarhalsvirkjun

The President of Iceland, Mr. Ólafur Ragnar Grímsson, layed the cornerstone of the Búðarháls HEP powerhouse on October 26th, 2012.

The Búðarháls HEP is located in the lower highlands of southern Iceland on the rivers Tungnaá and Kaldakvísl at Búðarháls in the Rangárvallasýsla County.  The Project Area extends over the Búðarháls ridge between the river Kaldakvísl and the existing Sultartangi reservoir, some 150 km east of Reykjavík.

The Búðarháls HEP will utilize the head difference of approximately 40 metres between the Hrauneyjafoss HEP tailrace and the Sultartangi Reservoir.

Preliminary works of the Búðarháls HEP was carried out in 2001 and 2002 until it was postponed.  In 2008, the tender design for the project was revised and in late 2010, the construction resumed.  It is envisaged that the Búðarháls HEP will be in operation by the end of 2013.

The main features of the project are summarized below:

  1. The Sporðalda reservoir will be formed mainly by two rockfill dams, the NW-dam that crosses the river Kaldakvísl, just upstream from the confluence with the river Tungnaá and the SE-dam that crosses the Sporðaldakvísl just upstream of its confluence with the river Tungnaá. The Sporðaldakvísl conveys the discharge from Hrauneyjafoss HEP tailwater into the river Tungnaá.  The NW-dam will be about 1100 m long whereas the SE-dam will be approximately 170 m long.  Both dams will have a maximum height of around 25 m.  The reservoir normal water level (NWL) will be 337,0 m a.s.l and the reservoir will store some 50 hm3 (Gl) of water with a surface area of 7 km2.

  2. A conventional drill and blast Headrace Tunnel around 4 km long through the Búðarháls ridge will convey water from the reservoir to a Surge Basin immediately upstream of the Penstock Intake.  Two 60 m long steel lined Penstocks connect the Penstock Intake to the Powerhouse.

  3. The Powerhouse will be a conventional surface structure provided with two 47,5 MW Kaplan type turbines. The rated net head is 36,0 m, rated discharge is 280 m³/s and the total installed capacity 95,0 MW.  The energy generating capacity of the station is estimated at 585 GW/h annually.

  4. The generators will be connected to the unit transformers by isolated phase busbars.

  5. A Tailrace Canal about 0,4 km long will convey the discharge from the powerhouse to the Sultartangi reservoir.

  6. The unit transformers will be located outside at the front of the Powerhouse.  High voltage cables will connect the transformers to Landsnet´s Substation Building which is located just south of the Powerhouse.

  7. The Substation Building is connected to a 220 kV transmission line crossing the Búðarháls ridge and connecting to the main grid just east of Tungnaá river.

EFLA Consulting Engineers is in charge of all civil design of the Búðarháls HEP and Landsnet´s Substation Building.  EFLA Consulting Engineers is also responsible for overseeing and coordinating all design, scheduling and cost estimating in both these projects.

Some new features were introduced and emphasized in this project.

  • Value Engineering – In 2002, a Value Engineering was conducted, where for instance the Bottom Outlet for the Sporðalda Reservoir was eliminated and a Diversion Tunnel was introduced. This modification alone saved a significant amount of money.

  • Risk Assessment - In 2010, EFLA Consulting Engineers performed a Risk Assessment of the project as a whole and established a Risk Management System, which has been utilized successfully as part of the project management, both during design and construction.

  • FIDIC Conditions of Contract – The Condition of Contracts for some of the Contracts in the project, including the civil construction, are based on FIDIC.

  • Coordination between engineering disciplines – To facilitate all coordination between engineering disciplines and with the Electro Mechanical suppliers, and to avoid any collisions between equipment, all structures and equipment are drafted in 3D.  The 3D models are made accessible to everybody, including contractors.

  • Phase modeling of the Headrace Tunnel – In order to determine the final rock support for the Headrace Tunnel, a model was constructed using the Phase program.  Various data was sampled from site as well as measurements in order to determine the parameters for the model.

  • Leassons learned – The Employer conducts regularly so called "Lessons learned" meetings, where key members of the project identify systematically those areas that have been successful and those areas that can be improved.

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