Technical Informations

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· Type	: Earth- fill, with clay core.
· Total volume of embankment	: 32.5^(M.m3).
· Crest level	: 234^(m.) m.a.s.l.
· Height from the Foundation	: 127^(m.).
· Crest length	: 3030^(m.).
· Crest width	: 12^(m.).
· Maximum width on the foundation	: 1100^(m.).
· Shell materials volume	: 19.6^(M.m3).
· Core materials volume	: 3.65^(M.m3).
· Excavation volume (Body & Spillway)	: 9.15^(M.m3).
· Slope of the upstream shell	: From the crest level, down to the level of 192 m.a.s.l., the slope is 1:2.25 (the shell on this location is covered with rip-rap). At this level a berm with 10^(m.) width is executed, from thereof, the slope is 1:2.25, down to the level of 163 m.a.s.l. (this part of the shell until level 140^(m.) is covered with soil- cement). At 163 m.a.s.l. level, another berm with 30^(m.) length is executed. Then the shell reaches the foundation with the slope of 1:2.50 (which is the slope of the cofferdam upstream shell).
· Slope of the downstream Shell	: At the cross section of the Kilometer 1+400, from the crest level of 234 m.a.s.l., down to the level of 200 m.a.s.l. , the slope is 1: 1.8. At this level a berm of 5^(m.) width is executed. From thereof , the Shell keeps the same slope until the level of 170 m.a.s.l. At this level another berm of 84^(m.) width is constructed. Then the Shell has been executed with the slope of 1: 1.8 , down to the level of 160 m.a.s.l. and 135 m.a.s.l., at which levels, two berms of 14^(m.) and 75^(m.) are constructed, consecutively. The Shell has been continued with the slope of 1:2 , until the toe of the Dam at the level of 116 m.a.s.l.

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1.2. Diversion System

Karkheh Dam diversion system, consists of: a concrete culvert with four waterways, intake structures, stilling basin, pre- cofferdam, cofferdam, and downstream dyke.

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1-2-1. Pre- cofferdam & cofferdam

In order to prevent the effect of water flow of the river, in the flood seasons, during construction of the Dam body, the upstream & downstream of the Dam were closed, by the means of cofferdam and downstream dyke. In this way the area between the two points became dewatered, then the construction activities of the main structure was rendered possible. Since the cofferdam of Karkheh Project is designed to be a part of the main dam, as a result, a pre- cofferdam was built, so that the Cofferdam could be constructed with the suitable technical specifications, in a dry condition.
The crest level of the pre- cofferdam, is designed to be at the level of 122.5 m.a.s.l., for a dry period, with the flood of 20- year- return- period, and the maximum discharge of 860(m3/s).
The design level of the cofferdam of Karkheh Diversion System is 163 m.a.s.l., for a flood of 100- year- return- period, with the discharge of 7240(m3/s), while a part of such flood (about 3680(m3/s)) will pass through the Diversion Galleries, and the rest, will be routed, in the Cofferdam Reservoir.

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1-2-2. Specifications of the Cofferdam

· Length	: 950^(m.)
· Height from the river bed	: 52^(m.)
· Width of the crest	: 20^(m.)
· Maximum width on the foundation	: 495^(m.)
· Volume of the body	: 4.5^(M.m3.)
· Maximum storage volume	: 433^(M.m3.)

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1-2-3. Downstream Dyke

According to the rating curve of the river, the water level on the downstream of the dyke is 115 m.a.s.l., with a discharge of 150(m3/s), and 120.5 m.a.s.l., for the flood with a discharge of 4570(m3/s). As a result, the crest of the downstream dyke is considered to be 121.5 m.a.s.l.

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1-2-4. Culvert

The diversion of the river from its original course, is a basic measure taken in the dam construction projects. Exploiting a four- concrete- waterway- culvert was considered to be the best choice for the Diversion System of Karkheh Project.
The specifications of this culvert is as bellow:

· Shape	: four openings, with an octagonal section.
· Dimension of each opening	: height: 10.5^(m.),width: 5^(m.).
· Length (including the intake & outlet structures)	: 790^(m.).
· Type of lining	: reinforced concrete.
· Excavation volume	: Apx. 1.5^(M.m3).
· Concreting volume	: 223,000^(m3).
· Inlet elevation	: 113 m.a.s.l.
· Stilling basin bottom level	: 100 m.a.s.l.
· Discharge capacity	: 3680^(m3/s), at the level of 161.70 m.a.s.l. (before turning into a bottom outlet).

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1-2-5. Intake Structure

The intake Structure of the Diversion System, with the length of 32(m.) and the width of 30.6(m.), includes: four openings, intake tower, slots for the gates, and closure gates.
In order to close the water course through the waterways, gates of different types, have been installed, as bellow:
A) At waterways I &II, two bulk- head gates, the weight of each amounts to 32 tons.
B) At the waterway III, a fixed wheel gate, weighting 62 tons.
C) At the waterway IV, a roller gate, with the weight of 82 tons.
For the lifting & installation of the parts of the culvert gates, a cantilever gantry crane, with the capacity of 120 tons, was used. This crane which had been installed at the level of 160 m.a.s.l., on the crest of the intake tower was disassembled, after impounding and permanent closure of the gates.
On the upper part of the Intake tower, there are orifices and windows, which are used as inlets for the water flowing into the bottom outlet, after turning the culvert into the bottom outlet.

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1-2-6. Outlet Structure

In order to dissipate the energy of the water, passing through the culvert, a stilling basin- with the length of 128.5(m.), the width of 35(m.), and the bottom level of 100 m.a.s.l.- was constructed.
At the outlet of each waterway, some slots were designed, through which, the stop-logs were installed. By closing the gates, when necessary, flowing water into the waterways, is prevented.

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1-2-7. Bottom Outlet

Culvert waterways, are used as bottom outlet, during the operation of the Dam. To do this, in 50(m.) length of the waterways I,II & III, required pipes & valves are installed, so that the cross section of the water flow through the waterways, is decreased from 48(m2) to 3.14(m2), while their total discharge, in normal water level, has become limited. Waterway IV is completely closed, being used as an access road to the bottom outlet and the valves installed in other waterways. In the bottom outlet system, designed for the discharge control, two emergency and service gates are applied, each of which is opened and closed by a servo- motor, with the capacity of 175 tons.

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1-3. Watertightening System of the Foundation

In order to control seepage within the dam foundation, Grouting was considered as the first option. However, results of the trail grouting tests were not satisfactory. Therefore, other options for controling seepage in the foundation were studied, and eventually, a plastic concrete
cut-off-wall was selected for this purpose.
This main Cut- Off , which is on the same axis as the Dam body , is constructed under the foundation , in the center of the clay core.
Specifications

· Length	: 2925^(m.) .
· Width	: 0.8-1 ^(m.).
· Concrete volume	: 147370 ^(m3).
· Minimum depth	: 18^(m.).
· Maximum depth	: 78^(m.).

Since the Power- house Building is located on the left abutment, and having considered the effect of impounding , and seepage through conglomerate layers, as a result a Cut- Off- Wall was constructed too , under the east of the Power- house Building , for the protection and stabilizing the slopes on the Power- house area , and to minimize the seepage. To connect this Cut- Off to the main Cut- Off- Wall , a grout curtain has been executed through the access gallery , located on the Kilometer 0+950 . Thus , water seepage into the Power- house Building area is prevented.
Specifications Cut-Off-Wall, on the east of the
Power- house Building.

· Length	: 750^(m.).
· Number of Panels	: 300.
· Depth	: 20^(m)- 70^(m).
· Apx. volume	: 30000^(m3).

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1-4. Inspection & Access Galleries

Inspection Gallery
A concrete gallery was designed and constructed with the short distance from the Cut-Off- Wall, on the downstream, for the following purposes: a) access to the foundation, under the clay core, b) access to the Cut-Off- Wall, c) monitoring the Cut-Off- Wall, d) making possible repairs, during the Dam operation,
Other applications of this gallery could be as follows:
• Monitoring, and obtaining data concerning piezometric pressure of the water in different layers, under the Dam foundation.
• Possible increase of the depth, and improvement of the seepage flowing under the Dam foundation.
• Monitoring, and controlling the settlement of the Dam foundation.
• Possible drainage, and decreasing the water pressure of each geological layers under the Dam foundation.
• Inspection and identical observation of the conditions of the Dam foundation.
Specifications of the Inspection Gallery

· Location	: under the clay core, 7.5^(m.) downstream of the Cut-Off-Wall.
· Length	: Apx. 1400^(m.).
· Height	: 3.2^(m.) .
· Width	: 2.6^(m.).

Specification of Access Galleries

· Number

: 3, constructed in the kilometers: 0+950. 1+450, and 2+160.

· Total length of the 3 galleries

: Apx. 500^(m.).

· Total volume of concreting of the inspection & access galleries

: 50,000^(m3).

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1-5. Instrumentations

In order to inspect the behavior of the foundation and the Dam body- during construction & operation- concerning pore pressure , earth pressure , seepage , and possible deviation of the body- about 1000 instruments have been installed in Karkheh Dam. These instruments are distributed in 23 sections of the body , according to the conditions of the foundation and the Dam height.
770 of which are of Cable Type , connected to the control room , on the left side of the body , the readings of which are done by the means of computer. While the readings of the rest are carried out on the installation locations , with the specific appliances of measurement. The data obtained from the instruments are inspected and analysed by the experts, periodically.

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1-6. Spillway

Having considered such parameters as the Dam height , the Reservoir volume , the type of the Dam , and its importance in: irrigation, hydroelectric power supply , the location of the Dam , regarding the downstream residential areas ,and the financial & social damages resulted from the Dam possible fracture , hence , the Spillway of Karkheh Dam has been designed based on the reliable discharge of probable maximum flood , considering suitable free – board.

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1-6-1. Specifications

· Type	: gated.
· Location	: right bank.
· Discharge capacity	: 18260^(m3/s)-(at PMF).
· Total length	: 1118^(m)(including the lengths of stilling basin & outlet channel).
· Width	: 110^(m) (excluding the middle piers, with the width of 90^(m.)).
· Stilling basin length	: 164^(m).
· Stilling basin width	: 110^(m).
· Design head on ogee crest	: 17^(m).
· Crest level of the ogee	: 209^(m) m.a.s.l.
· Excavation volume	: 5.5^(M.m3).
· Concrete volume	: 758000^(M.m3).

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1-6-2. Spillway inlet Structure

The inlet structure of the spillway , which is a huge concrete structure , with the dimension of 110(m.) *59(m.) , includes : the ogee, the middle & the abutment piers , radial & stoplog gates , access bridge on the Dam crest , the bridge for the gantry crane , and hydromechanical equipment for the possible repairs of the gates. The ogee crest of the spillway is placed at the level of 209 m.a.s.l. , with the difference of 8(m.) height , comparing with the bottom of the approach channel at the level of 201 m.a.s.l.
Slope of upstream face of the ogee is 1 : 1 and the width of each of the middle piers of the spillway is 4(m.).
Six sets of radial gates are employed , to control the flow of water through the spillway , each with 18(m.) height , 15(m.) width , 22(m.) radius , and 170 tons of weight. This is one of the largest types , of radial gates, which, are manufactured in Iran. Each gate is operated by two servomotors, each of which, with the capacity of 26 tons and stroke of 11(m.) .
In order to repair the radial gates , four stoplogs are used , each with the 15(m.) of width , 3(m.) of height , and 30 tons of weight. For the purposes of shifting around or replacement of stoplogs , a gantry crane of 35 tons, with the rail length of 130(m.) , is exploited.

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1-6-3. Energy Dissipation System

A stilling basin has been constructed for reliable dissipation of energy, produced in the outlet flow. The stilling basin is of the U.S.B.R. 1 Type. Considering the secondary depth of hydraulic jump , and the level of the tail race, the level of the bottom of the stilling basin is designed to be at 95 m.a.s.l. The stilling basin length is 164(m.) , and its width is 110(m.). On the end part of the bottom of the stilling basin , the slope of 1:5 (V:H), from the level of 95 m.a.s.l. (along 65(m.) ) reaches up to the level of 108 m.a.s.l. The crest level of the side walls of the basin designed based on the maximum water level at the flood with 1000- year- return - period , including the free – board, amounting to 122.5 m.a.s.l.

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1-7. Borrow Pits

Borrow Pit		Borrow Pit area (Km²)	Borrow Pit depth (m)	Distance from the Site (Km)	Exploitable volume (M.m³)	Material type	Location
Coarse aggregate	G1	4	5-10	4-8	20	GW , GP	Shell, drain, filters, transition zones & concrete materials
	G2	0.8	average 2	11-14	1.75	GW, GP, & a little GC
	G3	8	average 3	9-12	2.5	GW, GP
Fine aggregate	C1	2.5	3-5	10-13	6.2	Weathered mudstone of CH	Clay core
Chenareh Mine				45		Limestone	rip-rap on the upstream face

GP : Poor graded sandy gravel.
GW : Well graded sandy gravel.
GC : Sandy gravel with clay.
CH : Non- organic clay, with high placticity.
* According to the test results, these materials are suitable for compaction, and their maximum dry density are more than 2.08(g/cm3).
** Insitu incompactibility test results indicate that the materials are suitable for the clay core.

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2. Hydroelectric power plant
2-1. General specifications

· Power plant capacity	: 400^(M.w.).
· Number of the generators	: 3, each with the capacity of 133.3^(M.w).
· Annual average power production	: 934^(G.wh.).

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2-2. Power plant Equipment
2-2-1. Cranes
Main cranes

Karkheh power plant has two over- head cranes , with each capacity of 225 tons. These cranes, by the means of a lifting beam- with the weight of about 20 tons- make possible the displacement & installation of the rotor of the generator (the heaviest equipment of the power- house , with the weight of 420 tons).
Each crane has an assisting winch , with the capacity of 40 tons , using for displacing and installing equipment , lighter than 40 tons.

Gantry Crane

This crane , with the capacity of 32 tons , is used for the installation of the stop- logs of the draft tube , at its outlet opening.

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2-2-2. Draft Tube Closure Gates

· Type	: Stop- log.
· Number of the gates	: 4 sets, totally 8 parts, which are able to close draft tubes of the two Units, simultaneously.
· Weight of the lower part	:12924^(kg.) (design weight).
· Weight of the upper part	:13022^(kg.) (design weight).
· Total weight of the 4 sets of the gates	: 104 tons.
· Operation mechanism	: hydraulic balance pressure, which is maintained by the means of bypass valves.
· Gate pressure design head	: 24.48^(m.).
· Seal level of the bottom part of the gate	: 98.1 m.a.s.l.
· Seals	: rubber J32 85^(m.m),on the side and upper parts, and flat- 12 70^(m.m), on the lower part.
· Location of the seals	: downstream.
· Required time for the draft tube to be filled	: about 70 minutes.

The gates are placed (or displaced) by a lifting beam and the gantry crane , to or from the exact locations.

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2-2-3. Inlet Valves

· Type	: Biplane Butterfly.
· Number	: 3 sets.
· Diameter	: 5.3^(m.).
· Design pressure	: 15 bars (1.5 ^(M.pa.)).
· Hydrostatic test pressure	: 22.5 bars (2.25 ^(M.pa.)).
· Maximum inlet discharge	: 159.54^(m3.s).
· Installation level of the valve center line	: 110.6 m.a.s.l.
· Required time for the valve to be closed	: 60-90^(s.).
· Required time for the valve to be opened	: less than 120^(s.).
· Allowable leakage, at leakage test pressure of 1.154^(M.pa.)	: maximum 13 liters per minute.
· Number of servomotors of each valve	: 2 sets.
· Diameter of each servomotor	: 700^(mm.).
· Servomotor stroke	: 1655^(mm.).
· Operational oil pressure of each servomotor	: 60 bars (4 ^(M.pa.)).
· Total weight of the complete set of each butterfly valve of a Unit	: 223 tons (including its upstream & downstream pipes,bodies, bypass set, relief valve , and its control equipment, such as sump tank & oil pressure tank , electro- pumps, and servomotors).

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2-2-4. Weight of the Butterfly Valves Main Parts

· Valve body	: 55.1 tons.
· Disc	: 59 tons.
· Upstream pipe	: 13.86 tons.
· Downstream pipe	: 21.52 tons.
· Total weight of the bypass pipes	: 3.32 tons.

The disc of the butterfly valve is closed under the force of the counter weights , connected to the valve shaft by the arms. It is opened by the servomotor force. In order to balance the hydraulic pressure of the two sides of the disc , when opening the hydraulic valves , two bypass pipes are exploited to allow water in the upstream pipes flow into downstream disc.