Project Summary 
Project location
Basic information
Key statistics
Specifications of upper and lower dams
Diversion system
Headrace Tunnels
Geotechnical aspects
Project Site Map
The development of Siah Bisheh pumped storage project dates back to the year 1970 when a study was performed on Hydro electric resources of Alborz mountain range. The study yielded an inventory of possible hydropower projects( including pump storage projects) in various valleys of the northern part of the Alborz mountain range.

In 1975, feasibility studies for three sites (selected from all of the alternatives) were started. Comparison and evaluation of these three pumped storage schemes revealed that Siah Bisheh project is the favorable one. These studies were terminated in late 1977.

In early 1983, a contract for the review of the feasibility study, the definite design and the preparation of the tender documents was awarded to a joint venture of international consultants, which was completed in 1985. From 1985 to 1992 the geotechnical site and laboratory investigations were continued and the construction design was completed by the same consultants. Simultaneously, some preconstruction works such as diversion tunnels, drainage galleries, access roads and operations complex, as well as excavation of the power intake and initial portion of the waterway tunnels were performed. The works were stopped in 1992 for economic reasons.

From 1999 to 2002, a review of the existing design documents was carried out, and the tender documents were updated, which became the starting point of the present design and built contract. The present effort includes a complete review of all previous designs (which is now completed), suggestion of the required design state-of-the art modifications (which is mostly completed), and detail design (which is currently under way).
Project Location
The project is located in the vicinity of Siah Bisheh village in Mazanderan province, 125 km to the North of Tehran, and 10 km to the North of Kandovan Tunnel on the Chalus River.  

Basic Information
Client: Iran Water & Power Resources Development
Detail Design: Kayson-Electrowatt-Ekono
Contract Period: 60 months
Location: Siah Bisheh
Partners: Kayson-Beta-Soil Engineering Services (SES)
Key Statistics
Excavation in rocky ground conditions: 1 million cubic meters
Excavation in normal ground conditions: 3 million cubic meters
Earthfill: 4.2 million cubic meters
Tunnel excavation: 190,000 cubic meters
Shotcrete: 21,000 cubic meters
Anchor bars: 250,000 meters
Grout holes: 146,000 meters
Reinforcement: 22,000 tonnes
Formwork, F1 Type: 450,000 square meters
Movable formwork: 75,000 square meters
Concrete placement: 300,000 cubic meters
The main objectives of the project can be summarized as follows:
1- To produce up to 1000 MW of hydroelectricity
2- To flatten out variations in the load on the power grid, permitting thermal power plants that provide base-load electricity to continue operating at capacity, while reducing the need to build special power plants which run only at peak demand.
3- To provide cover for demand surges in Northern provinces of Iran, thereby stabilizing the entire North Iran power grid.
4- To reduce maintenance costs of thermal power plants by as much as 19 million dollars per year.
5- To provide job opportunities for local people.
Upper dam:
Dam type: concrete face rockfill
Height: 82.5 meters
Crest length: 436 meters
Crest width: 12 meters
Foundation width: 280 meters
Lower dam:
Dam type: concrete face rockfill dam
Height: 102 m
Crest length: 332 m
Crest width: 12 m
Foundation width: 360 m
Volume: 4.3 million cubic meters
Mean annual flow: 9.13 cubic meters per second
Probable Maximum Flood: 200 cubic meters per second
Volume: 6.9 million cubic meters
Mean annual flow: 44.4 cubic meters per second
Probable Maximum Flood: 910 cubic meters per second
Spillway type: free ogee- stepped spillway
Energy dissipation system: Stilling basin
Location: left abutment
Design flow: 203 cubic meters per second
Chute Length: 490 meters
Chute width : 20 meters
Crest length: 20 meters
Spillway type: free ogee- stepped spillway
Energy dissipation system: Stilling basin
Location: left abutment
Design flow: 890 cubic meters per second
Chute Length: 200 meters
Chute width : 30 meters
Crest length: 30 meters
Upper Dam Layout Lower dam Layout
Diversion System  
Upper dam
Number of tunnels:
Tunnel diameter: 2.95 m
Tunnel length: 570 m
Lower dam
Number of tunnels:
Tunnel diameter: 4 m
Tunnel length: 700 m
Headrace Tunnels

Number of tunnels: 2
Tunnel diameter: 5.7 meters
Tunnel capacity during power generation: 130 m/s (each one)
Tunnel capacity for pumping: 100 m/s
Approximate tunnel length: 2000 m
Number of headrace shafts: 2
Headrace shaft diameter: 5 m
Headrace shaft length: 760 m
Geotechnical Aspects of Upper Dam
The upper dam is situated in an asymmetric V-shaped valley of the upper Chalus river.
The well exposed rock strata on the left abutment for the dam spillway, and access road to the power intake are an asymmetric synclinal structure.
The strata are built up by a rock sequence consisting of siltstone with sandstone and shale intercalations belonging to Shemshak formation.
The drilling results revealed that, except along faults, a slight weathering occurs on joints, which are in general iron stained down to a depth of 30 to 40 m.
The right abutment is located in a slided mass called Duna landslide. It is built up by the disturbed rocks of Shemshak formation and loose materials.
The valley bottom in the area of the dam is covered by river deposits composed of rounded to sub-rounded cobbles and boulders with subordinately intercalated gravels, sands and silts. The thickness of the deposits is approximately 8 to 10 m.
Upper Dam Plan  
Geotechnical Aspects of Lower Dam
The lower dam is situated in a symmetric V-shaped valley of the lower Chalus River.
The dam axis is located about 500 meters down stream of the confluence of Chalus and Garmrudbar rivers.
The foundation area of the dam consists of well bedded sandstones, limestones, shaly siltstones and intruded volcanic rocks belonging to the Dorud formation.
Structurally, the ridges forming the left and right abutments are formed by an anticline with its axis striking in NW-NE direction. The strata display flat angles of dip in the central part of the ridges. To the North, the anticline is followed by a narrow faulted syncline. To the South, the anticline crest zone (ridges) is affected by a 5-10 m wide fault zone, forming lateral gullies on both banks.
Two faults cross the plinth and foundation area on the left abutment. A fault 10-15 m wide, accompanied by parallel minor faults, will cross the plinth in the upper reaches of the right bank.
Only 30% of the dam area shows outcropping rock and the remaining part is covered by soil of different origin and composition.
Lower Dam Plan  
In the 20th and 21st  centuries, 8 earthquakes happened with magnitudes ranging from 5.2 Richter in Mobarakabad in 1930 to 7.7 Richter in Rudbar- Manjil in 1990.
The latest earthquake was the 6.4 Richter Firouzabad-Kojour earthquake which shook the western parts of Mazandaran province on May 28, 2004.
Major faults in the region:
The Mosha, Mazandaran-Khazar, North Tehran, North Ghazvin, Taleghan and North Alborz are the most important seismic faults which have caused large and destructive earthquakes in the area.

Instrument Location Quantity
Hydrostatic Settlement cell Right Abutment 5
Left Abutment 5
Central Section 10
Electrical piezometer Plinth Foundation 9
Both Sides of the grout curtain 4
Dam Foundation along the river bed 8
Electro level Instrumentation Sections 22
In place inclinometer Central Section 1
Vertical joint meter Face Tension Zone 4
Perimeter joint meter Along the Perimeter Joint 5
Total pressuremeter Central Section 6
Vertical inclinometer Dam Axis 1
Downstream Shell 1
Cross arm extensometer Along the Dam Axis 3
Cross arm extensometer Left Abutment 2
Right Abutment 2
Central Section 3
Project Site Map    


 Copyright © 2010 Kayson Company. All rights reserved.