Design Criteria(R0)

R0 08-02-2007 BBG VB AJ - - - - VB

REV. NO. DATE

PREPARED BY

CHECKED BY CLEARED BY

APPROVED BY

ALAKNANDA HYDRO POWER COMPANY LIMITED

330 MW SHRINAGAR HYDRO ELECTRIC PROJECT IN UTTARANCHAL STATE, INDIA

DOCUMENT NO. TCE.4816A-OT-151-DC-01

BASIC ENGINEERING AND DESIGN CRITERIA

Matulya Centre A, 1st Floor, 249, Senapati Bapat Marg,

Lower Parel (West), Mumbai 400 013, India

Owner Alaknanda Hydro Power Co. Ltd. Owners Engineer - TCE Consulting Engineers Ltd.

330 MW Shrinagar Hydro Electric Project in Uttaranchal State

TCE.4816A-OT-151-DC-01/R0 Basic Engineering and Design Criteria Sheet No. i of i

REVISION STATUS

REV. NO. DATE DESCRIPTION

R0 08-02-2007 Released for detailed design.



TCE.4816A-OT-151-DC-01/R0 Basic Engineering and Design Criteria Sheet No. i of iv

CONTENTS

SECTION - 1 - INTRODUCTION ...........................................................................................1 1.1 GENERAL................................................................................................................................. 1

SECTION - 2 - BRIEF PROJECT DESCRIPTION .................................................................2 2.1 TYPE OF PROJECT................................................................................................................. 2 2.2 GENERAL LAYOUT AND MAJOR PROJECT COMPONENTS.............................................. 2

SECTION - 3 - SALIENT FEATURES ...................................................................................5 3.1 CIVIL WORKS .......................................................................................................................... 5 3.2 HYDRO-MECHANICAL WORKS ........................................................................................... 10

SECTION - 4 - GENERAL TECHNICAL REQUIREMENTS ................................................12 4.1 GENERAL............................................................................................................................... 12 4.2 FUNCTIONAL REQUIREMENTS........................................................................................... 12 4.3 LIFETIME REQUIREMENTS ................................................................................................. 12 4.4 COMPLETENESS OF FACILITIES........................................................................................ 12 4.5 DRAWINGS AND DOCUMENTS ........................................................................................... 12 4.6 UNITS ..................................................................................................................................... 13 4.7 CODES AND STANDARDS ................................................................................................... 13 4.8 SAFETY.................................................................................................................................. 13 4.9 SEISMIC DESIGN REQUIREMENTS .................................................................................... 13 4.10 FUTURE MAINTENANCE...................................................................................................... 14 4.11 ARCHITECTURAL APPEARANCE........................................................................................ 14

SECTION - 5 - PERFORMANCE REQUIREMENTS ...........................................................15 5.1 GENERAL............................................................................................................................... 15 5.2 CIVIL WORKS ........................................................................................................................ 15 5.3 HYDRO-MECHANICAL WORKS ........................................................................................... 17 5.4 VERIFICATION OF PERFORMANCE PARAMETERS ......................................................... 18

SECTION - 6 - HYDRAULIC DESIGN REQUIREMENTS....................................................20 6.1 GENERAL............................................................................................................................... 20 6.2 HYDROLOGY......................................................................................................................... 20 6.3 WATER CONDUCTOR SYSTEM AND STRUCTURES ........................................................ 22

SECTION - 7 - GEOTECHNICAL AND GEOLOGICAL DESIGN REQUIREMENTS...........27 7.1 GENERAL REQUIREMENTS................................................................................................. 27 7.2 CODES AND STANDARDS ................................................................................................... 28 7.3 LOADS AND FORCES........................................................................................................... 28 7.4 ROCK MASS PROPERTIES.................................................................................................. 29 7.5 DESIGN OF UNDERGROUND STRUCTURES .................................................................... 30 7.6 DESIGN OF ROCK EXCAVATION ........................................................................................ 31 7.7 WATER TUNNELS ................................................................................................................. 31 7.8 DESIGN OF ROCK SUPPORT .............................................................................................. 31 7.9 LINING DESIGN ..................................................................................................................... 33 7.10 SOIL SUPPORT ..................................................................................................................... 34 7.11 FOUNDATION OF SURFACE STRUCTURES...................................................................... 34 7.12 DESIGN OF EMBANKMENT AND CUT SLOPES................................................................. 34 7.13 SETTLEMENT ALLOWANCE ................................................................................................ 34 7.14 SEEPAGE ANALYSIS ............................................................................................................ 35



TCE.4816A-OT-151-DC-01/R0 Basic Engineering and Design Criteria Sheet No. ii of iv

7.15 DESIGN OF RIPRAP AND SLOPE PROTECTION ............................................................... 35 7.16 FILTER DESIGN..................................................................................................................... 35 7.17 DESIGN OF PRESSURE RELIEF WELLS ............................................................................ 36 7.18 GROUTING ............................................................................................................................ 36 7.19 FURTHER INVESTIGATIONS ............................................................................................... 37

SECTION - 8 - ROAD DESIGN REUIREMENTS.................................................................38 SECTION - 9 - GENERAL DESIGN REQUIREMENTS .......................................................39

9.1 GENERAL............................................................................................................................... 39 9.2 ARCHITECTURAL CONCEPTS FOR BUILDINGS ............................................................... 39 9.3 ROOF ACCESS...................................................................................................................... 39 9.4 PLATFORMS AND WALKWAYS ........................................................................................... 39 9.5 STAIRS AND LADDERS ........................................................................................................ 40 9.6 ANCHOR BOLTS AND INSERT PLATES.............................................................................. 41 9.7 VERTICAL HEADROOM........................................................................................................ 41 9.8 EXPANSION /CONSTRUCTION JOINTS.............................................................................. 41 9.9 BRICK / STONE MASONRY AND PARAPET WALL............................................................. 41 9.10 DRAINAGE ............................................................................................................................. 42 9.11 WATER PROOFING OF UNDERGROUND STRUCTURES................................................. 43 9.12 ANTI TERMITE TREATMENT................................................................................................ 43 9.13 PLINTH LEVEL....................................................................................................................... 43 9.14 STATUTORY REQUIREMENTS............................................................................................ 43

SECTION - 10 - DESIGN REQUIREMENTS - LOADS AND LOAD COMBINATIONS........44 10.1 GENERAL............................................................................................................................... 44 10.2 DEAD LOADS......................................................................................................................... 44 10.3 IMPOSED LOADS .................................................................................................................. 44 10.4 WATER PRESSURE.............................................................................................................. 45 10.5 UPLIFT LOAD......................................................................................................................... 45 10.6 EARTH PRESSURE LOADS ................................................................................................. 45 10.7 WIND LOAD ........................................................................................................................... 46 10.8 SEISMIC LOADS.................................................................................................................... 46 10.9 TEMPERATURE LOAD.......................................................................................................... 46 10.10 EQUIPMENT LOADS ............................................................................................................. 46 10.11 CRANE, MONORAIL AND ELEVATOR LOADS.................................................................... 47 10.12 OTHER LOADS ...................................................................................................................... 48 10.13 BASIC LOAD CASES............................................................................................................. 48 10.14 LOAD COMBINATIONS ......................................................................................................... 48 10.15 LOAD COMBINATIONS FOR UNDERGROUND / WATER CONDUCTOR

STRUCTURES................................................................................................................... 49 SECTION - 11 - DESIGN REQUIREMENTS - REINFORCED CONCRETE

STRUCTURES AND FOUNDATIONS .......................................................50 11.1 GENERAL............................................................................................................................... 50 11.2 DESIGN METHODOLOGY..................................................................................................... 50 11.3 INCREASE IN STRESSES..................................................................................................... 52 11.4 STABILITY OF STRUCTURES .............................................................................................. 52 11.5 MINIMUM THICKNESS OF STRUCTURAL ELEMENTS ...................................................... 53 11.6 MINIMUM HEIGHTS FOR PEDESTALS OF STEEL COLUMNS.......................................... 53 11.7 MINIMUM HEIGHTS FOR ENCASEMENT TO STEEL COLUMNS ...................................... 54 11.8 CONCRETE MIX .................................................................................................................... 54



TCE.4816A-OT-151-DC-01/R0 Basic Engineering and Design Criteria Sheet No. iii of iv

11.9 NON-SHRINK GROUTING..................................................................................................... 54 11.10 MINIMUM COVER TO FOUNDATION BOLTS...................................................................... 55 11.11 PLACING TEMPERATURE.................................................................................................... 55 11.12 MISCELLANEOUS REQUIREMENT ..................................................................................... 55

SECTION - 12 - DESIGN REQUIREMENTS - STEEL STRUCTURES................................56 12.1 GENERAL............................................................................................................................... 56 12.2 FRAMING ............................................................................................................................... 56 12.3 MATERIALS ........................................................................................................................... 57 12.4 CONNECTIONS ..................................................................................................................... 57 12.5 DESIGN METHODOLOGY..................................................................................................... 58 12.6 PERMISSIBLE DEFLECTIONS ............................................................................................. 59 12.7 MINIMUM THICKNESS AND SIZES OF STEEL ELEMENTS............................................... 60 12.8 SLENDERNESS AND DEPTH RATIO................................................................................... 60

SECTION - 13 - DESIGN REQUIREMENTS - DESCRIPTION AND TECHNICAL REQUIREMENTS OF THE WORKS..........................................................61

13.1 INTRODUCTION .................................................................................................................... 61 13.2 DAM AND SPILLWAY ............................................................................................................ 61 13.3 HEADRACE TUNNELS AND INTAKES................................................................................. 66 13.4 TROUGH SECTION ............................................................................................................... 68 13.5 DESILTING BASIN ................................................................................................................. 69 13.6 POWER CHANNEL ................................................................................................................ 70 13.7 FOREBAY AND BYPASS ARRANGEMENT ......................................................................... 72 13.8 PENSTOCKS.......................................................................................................................... 75 13.9 POWER HOUSE .................................................................................................................... 76 13.10 TAILRACE SYSTEM .............................................................................................................. 80 13.11 CROSS DRAINAGE WORKS ................................................................................................ 80 13.12 BOUNDARY WALL, SECURITY GATE AND POST.............................................................. 80 13.13 CHAINAGE MARKERS .......................................................................................................... 81 13.14 PLINTH PROTECTION .......................................................................................................... 81 13.15 HORTICULTURE AND LANDSCAPING ........................................................................................... 82 13.16 TRANSFORMER YARD......................................................................................................... 82

SECTION - 14 - ELECTRO-MECHANICAL REQUIREMENTS ...........................................83 14.1 TURBINE ................................................................................................................................ 83 14.2 MAIN INLET VALVE ............................................................................................................... 83 14.3 CRANE ................................................................................................................................... 84 14.4 COOLING WATER SYSTEM ................................................................................................. 84 14.5 DEWATERING AND DRAINAGE SYSTEM........................................................................... 84 14.6 FIRE PROTECTION SYSTEM ............................................................................................... 84 14.7 VENTILATION AND AIR CONDITIONING SYSTEM............................................................. 85 14.8 MAIN GENERATOR & BUSDUCT SYSTEM ......................................................................... 85 14.9 GENERATOR STEP UP TRANSFORMER............................................................................ 85 14.10 400 KV SWITCHYARD ........................................................................................................... 85 14.11 STATION AND DAM AUXILIARY AC SYSTEM..................................................................... 86 14.12 EMERGENCY BACKUP SYSTEM......................................................................................... 86 14.13 DC AUXILIARY SYSTEM....................................................................................................... 86 14.14 PROTECTION SYSTEM ........................................................................................................ 86 14.15 INSTRUMENTATION, CONTROL AND TELECOMMUNICATION SYSTEM ......................... 87



TCE.4816A-OT-151-DC-01/R0 Basic Engineering and Design Criteria Sheet No. iv of iv

SECTION - 15 - GENERAL ELECTRICAL REQUIREMENT...............................................89 15.1 GENERAL............................................................................................................................... 89 15.2 CABLING ................................................................................................................................ 89 15.3 AC AUXILIARY SYSTEM ....................................................................................................... 90 15.4 EARTHING SYSTEM ............................................................................................................. 93 15.5 BATTERY ROOM ................................................................................................................... 94 15.6 LIGHTING AND SOCKET OUTLETS..................................................................................... 94 15.7 CONTROL AND OPERATING MODES FOR LIGHTING .................................................... 102 15.8 SYSTEM COMPONENTS .................................................................................................... 103 15.9 INSPECTION AND TESTING............................................................................................... 105



TCE.4816A-OT-151-DC-01/R0 Basic Engineering and Design Criteria Sheet No. 1 of 106

SECTION - 1 - INTRODUCTION

1.1 GENERAL

The Shrinagar Hydro Electric project is proposed on the river Alaknanda (a major tributary of Ganga River) in Uttaranchal State. The power station will be located near (on the other bank of river) Shrinagar Town; therefore the project is named after this town. The project is located about 112 km from Rishikesh (the nearest rail head), 141 km from Haridwar, 170 km from Roorkee and 344 km from Delhi. The project is proposed to generate power utilising the perennial water flow in the river and the head of about 66 m by constructing a 95 m high dam across the major river Alaknanda.

Alaknanda river has a vast catchment area of 11,100 km2 out of which 2640 km2 (23.8%) is snow bound. Alaknanda is a perennial river and gets flooded in monsoon season (July-September) and in May-June, though lesser in magnitude due to melting of snow. The minimum observed discharge during the year 1971-1972 to 1993-94 was 69.60 m3/sec in February 1987-88. While the maximum discharge during the same year was 3954 m3/sec in August 1972-73. Dhauliganga, Pindar and Mandakini are the major tributaries of the Alaknanda River. Alaknanda river confluences with other major river called Bhagirathi River at Devprayag (33 km downstream of Shrinagar town) and further the river is called the sacred Ganga River.

The Full Supply Level (FSL) of dam of Shrinagar project is restricted by the tailrace water level (TWL) of the proposed Utyasu Dam project on the upstream. The TWL of Shrinagar project controls the FSL of the Kotli-Bhel dam located downstream. Hence there is almost no scope to revise the gross head available for power generation.

Alaknanda Hydro Power Company Limited (AHPCL), a group company of GVK (formerly Duncans North Hydro Power Co. Ltd.), is developing and implementing the Shrinagar Hydro Electric Project. AHPCL is henceforth referred as the Owner.

This document covers the basic engineering, and design criteria to be followed by the DEC while planning and designing the project. Any alternative suggestions/ proposals by the DEC shall be conveyed to the Owner along with its advantages in terms of performance, economy and reduction in construction period. Owner will study the proposal/s and may or may not accept such proposals.




SECTION - 2 - BRIEF PROJECT DESCRIPTION

2.1 TYPE OF PROJECT

As explained above, Alaknanda River being a perennial river, the proposed Shrinagar hydro electric project is planned as a run-of-the-river scheme. The main purpose of dam in the project is to create a potential head for power generation. The dam being about 90 m in height will have certain live storage capacity. The power plant may be operated as peaking power station also during low flow season to take the advantage of availability of live storage capacity.

2.2 GENERAL LAYOUT AND MAJOR PROJECT COMPONENTS

a. The proposed project is run-of-the-river type and its general layout is as shown on Exhibit No. 1 is accepted by Central Electricity Authority. DEC may suggest very minor changes in the general arrangement of the project during planning and designing stage with appropriate reasoning. However, Owner reserves the right to accept the proposed changes or otherwise without assigning a reason thereof. In case of acceptance of the alternative arrangement/ layout by Owner, responsibility of proper planning, designing and performance requirements still remains with DEC, but without affecting the total Project schedule.

b. It shall be ensured that all the structures and construction activities to complete the project are located within the land available with the Owner.

c. The Project has been cleared/ approved by the Central Electricity Authority (CEA) (vide their letter No. F.No.2 / UP / 28 / 2000 - PAC / 706-14, dated 20-07-2005) and the Ministry of Environment and Forests under certain conditions. DEC shall consider and implement all these conditions while planning and designing of various project components.

d. For convenience, the overall project execution may be divided into two or three parts.

e. The major structures / components, but not limited to, covered under each part will be as follows:

2.2.1 Part-I

a. Main concrete gravity type dam (either Roller Compacted Concrete (RCC) or conventional concrete Type) as accepted by the Owner, along with gated spillway, foundation treatment, energy dissipation arrangement, water release outlet, dam instrumentation, lifts, upstream and downstream cofferdams.

b. One/ Two numbers headrace tunnels as accepted by Owner with support system and concrete lining as per design criteria/ requirement, portals at tunnel entry and exits, along with intakes, geological treatments, etc.

c. Associated EIA and R&R works, hydro-mechanical works (gates and stoplogs) for spillway, water release outlet through dam, diversion tunnel/s, intake for headrace tunnels, trashracks, automatic trash removal/ cleaning arrangement, etc. along with their handling arrangement and permanent type enclosures, and access to them.

d. Accesses, bridges, culverts, infrastructure and enabling works.




2.2.2 Part-II

a. RCC trough crossing Supana Nala,

b. Desilting basin/ arrangement with flushing arrangements. (Adopting latest technology, model studies, etc)

c. Power Channel beyond desilting basin including excavation, banking, concrete lining, cross-drainage works, crossovers, fencing, information boards, foot bridges, etc.

d. Forebay with outlet for flushing arrangement for silt including bed / side lining, intake gates,

e. Concrete lined / RCC bypass arrangement with gates,

f. Associated EIA and R&R works, hydro-mechanical works (gates and stoplogs) at desilting basin outlet & inlet, flushing arrangement, automatic type gates at bypass arrangement, etc. along with their handling arrangement and permanent type enclosures, and access to them.

g. Accesses, bridges, culverts, infrastructure and enabling works.

2.2.3 Part-III

a. Surface steel penstocks (4 numbers) supported on ring girder supports, with intakes, anchor blocks and specials like expansion joints, manholes, reducers, drainage and emptying/ filling arrangement with piping and valves, etc.

b. Complete power house structure to accommodate the four numbers of generating units including control room, administrative building, toilet blocks, maintenance bay, providing lift, two EOT cranes (each about 140 T / 30 T capacity with a common lifting beam), unit auxiliaries and power house auxiliaries, lighting to the required flux level, etc.

c. Cooling water tank, fire water tank and make up tank, piping, pump house (for cooling water and drinking water),

d. Tailrace system including cofferdam, road diversion, etc.

e. Bridges and culverts (double lane, loading IRC 70R or the heaviest equipment to be transported, whichever is higher) crossing power channel, bypass channel, tailrace channel, etc. All the bridges for road leading to the power house shall be completed on priority considering the schedule of transport of equipment furnished by the electro-mechanical Contractor.

f. G-T yard and 400 kV switch yard and associated structures.

g. Associate EIA and R&R works, hydro-mechanical works (gates and stop logs) draft tube along with their handling arrangement, permanent type enclosures and accesses to them.

h. Accesses, bridges, culverts, infrastructure and enabling works.

2.2.4 Common (as applicable to each of above Part)

a. Upgrading existing permanent and temporary access roads, bridges, culverts, walkways, etc. as required by the Contractor for the construction of works.

b. New access roads (permanent and temporary) along with concrete bridges, culverts, cross-drainage works, etc. during the contract period.




c. Implementation of the EIA and R & R plans and the measures and activities arising out of the stipulations and conditions of the CEA clearance and the environmental clearance by the MOEF, all of which fall within the line dividing the respective civil works in parts.

d. Permanent lighting arrangement to the required flux level and voltage on dam top, dam galleries, lifts, intake, desilting basin, street lighting, electric supply to appropriate voltage to hydro-mechanical works, etc. including cabling, overhead wiring with poles/ towers, safety arrangements, electric bulbs/ tubes, all fixtures, switches, etc. complete. The Contractor shall be responsible for the maintenance of such facilities till handing over to the Owner.

e. All miscellaneous works like surface drainage arrangement, fencing, enclosures (housing) for instrumentation, site fillings considering environmental and safety aspects, landscaping, turfing, etc.

2.2.5 Interfaces

More than one Contractor will carry out project implementation. The project planning and corresponding tender and construction drawings shall clearly indicate/ specify the scope of works at the interfaces to avoid duplication or discontinuity/ omission of the works.




SECTION - 3 - SALIENT FEATURES The salient features of the project are as per the Techno-Economic Clearance accorder by CEA are attached below as a part of this section.

3.1 CIVIL WORKS

1 LOCATION

State .. Uttaranchal State, India.

District .. Tehri and Pauri

Tehsil Kirtinagar and Pauri

Longitude . 78050 E

Latitude . 30014 N

Nearest rail head . Rishikesh

2 POWER

Installed Capacity .. 330 MW (4 units of 82.5 MW each) + 10% continuous overloading

Period of Generation . Run of the river scheme, base load generation during monsoon and peaking generation during low flow period.

3 HYDROLOGY

River .. Alaknanda River, a major tributary of Ganga River

Catchment area .. 11,100 sq km

Snow bound catchment area 2,640 sq km

Maximum Probable Flood (PMF) . 26,400 cumecs

Standard Project Flood (SPF) .. 19,200 cumecs

4 DIVERSION TUNNEL

Nos. .. 1

Length .. 500 m

Finished Diameter ...... 8 m

Shape ... Horse Shoe

Diversion discharge 700 cumecs




5 DIVERSION DAM

Type .. Concrete gravity

Length .. 248 m

Maximum height of dam above deepest foundation level ..

90 m

Height of dam from deepest river bed . 66 m

Number and size of spillway bays 8 bays of 14 m width each

Spillway crest elevation . 584.50 m

Full reservoir level (FRL) .. 605.50 m

Minimum Draw Down Level (MDDL) .. 603.00 m

Maximum water level (MWL) .... 609.80 m

Gross storage .. 78 Mm3

Live storage . 8 Mm3

Dead storage ... 70 Mm3

Energy dissipation device .. Solid bucket

Road level on top of dam .. 611.0 m.

6 INTAKE

Invert level of trashrack . 593.00 m

Shape .. Circular

Design discharge ... 716 cumecs

7 HEAD RACE TUNNELS

Nos. .. 2

Length .. 1013 m and 1145 m

Diameter .. 9.5 m

Shape ... Circular

Design discharge 716 cumecs

Lining Concrete lined

8 TROUGH

Length .. 185 m

Size ... 13 m x 5.65 m

Shape Twin barrel

Shape in cross-section .. Rectangular




9 DESILTING BASIN

Length .. 240 m

Width (including divide wall) . 158.5 m

Water depth . 13.0 m

Particle size to be removed .. 0.20 mm and above

Flushing discharge . 100 cumecs

10 POWER CHANNEL

Shape in cross-section .. Trapezoidal

Length (including transition) . 3.05 km


Lining Concrete lined

Value of Rugosity coefficient 0.015 to 0.017

Cutting section

Bed width . 14.50 m

Side slope .... 1.5 : 1

Full supply depth .... 9.5 m

Longitudinal slope .. 1 in 8,000

Filling section

Bed width . 14.50 m

Side slope .... 2 : 1

Full supply depth . 8.8 m

Longitudinal slope .. 1 in 8,000

Rugosity coefficient ... 0.014 to 0.017

Type of lining .. Concrete lining

11 FOREBAY

Full Reservoir Level (FRL) 600.30 m

12 BYPASS CHANNEL

Type of fall structure at head Ogee type

Fall 11.8 m

Crest level ... 596.80 m

No. and size of bays at head ... 3 Nos. of 15 m each with

2 piers of 1.5 m each




Total width .. 48 m


13 PENSTOCKS

Numbers .. 4

Diameter .. 5.6 m

Length .. 114 m

14 POWER HOUSE

Location Right bank of river Alaknanda

Type . Surface

Size of Machine hall .. Refer drawing AHPCL-SHEP-GA-1002/P0 for tentative details. Actual dimensions will be finalized by E&M Contractor.

Installed capacity 330 MW (4 units of 82.5 MW each) + 10% continuous overloading

Type of turbines .. Vertical Francis

Gross head .. 67.20 m

Net head ... 65.97 m

Service bay elevation . 548.00 m

Minimum Tail Water Level . 530.90 m

Normal Tail Water Level 533.10 m

Main Inlet Valves .

Type .

Size

4 nos.

Butterfly

4.90 m diameter.

Unit Auxiliary Systems .. Governing system, Oil pumping system, Cooling water system, Compressed Air System etc. along with instrumentation and control system.

Power House Auxiliary Systems . Cranes, Ventilation and Air Conditioning System, Drainage and Dewatering System etc. along with instrumentation and control system

15 TAILRACE CHANNEL

Type .. Trapezoidal lined section

Length .. 140 m




Bed width . 85 m

Full supply depth 3.10 m

Side slope 2 : 1

Bed slope . 1 in 2430

Type of lining ... Dry boulders lining / PCC lining

Value of Rugosity coefficient . 0.03

16 SWITCHYARD

400 kV Switchyard . One and Half C.B. scheme 4 incoming and 4 outgoing bays, size 135 m x 234 m (approximately)

GT Yard .. 12 nos. 11kV/ 400 kV 34 MVA Single Phase GTs

Transmission Line . 400 kV double circuit 2nos. Lines from GT Yard to Switchyard.

17 TRANSMISSION LINE

400 kV single circuit line to Rishikesh Sub-station ...

100 km (approximately)

400 kV single circuit line to Nehlaur Sub-station ...

150 km (approximately)

18 POWER GENERATION BENEFITS

90% Dependable year.. . 1397 GWh

Average year ... 1515 GWh

Secondary Energy (in average year) .. 118 GWh

Peaking Capacity ... 363 MW

19 CONSTRUCTION PERIOD .. 44 months.




3.2 HYDRO-MECHANICAL WORKS

Sr. No.

Location of gate

Type of gate

Clear size (width x height)

(m)

Nos. Design head (above gate

sill)

(m)

Operating condition

Radial 14.00 x 21.15

8 21.00 Opening / closing of gates by hydraulic hoists and rope hoist as an alternative.

1. Dam spillway

Stoplogs 14.00 x 2.00

11 21.00 Motor operated hoist located on moving crane with lifting beam.

Vertical lift gate.

9.25 x 11.00

2 16.50 Capable of controlling flow, full/ part opening and closing against full water head by hydraulic hoist.

2. Tunnel intake

Stoplogs. 9.25 x 2.00 6 16.50 Motor operated hoist with lifting beam and capable of opening and closing against full water head.

3. Desilting basin.

Vertical lift 5.00 x 11.00

2 11.00 Opening / closing of gates by hydraulic hoist.

4. Desilting basin Flushing ducts.

Radial type with hydraulic hoist

2.30 x 1.00 2 12.00 Capable of opening against water and silt load with hydraulic hoist.

Automatic type.

15.00 x 3.50

3 3.50 Capable of opening and closing against full water head.

5. Bypass channel

Stoplogs. 15.00 x 1.20

3 3.5 Motor operated hoist located on moving crane with lifting beam.

6. Penstock intake

Vertical lift hydraulic hoist

4.70 x 5.60 4 13.10 Full opening / closing of gates by hydraulic hoist. Capable of opening and closing against full water head.




Sr. No.

Location of gate

Type of gate

Clear size (width x height)

(m)

Nos. Design head (above gate

sill)

(m)

Operating condition

Stoplogs 4.70 x 1.50 4 13.10 Motor operated hoist located on moving crane with lifting beam.

7. Draft tube Vertical lift 5.00 x 4.64 8 4.50 Opening / closing of gates by motor operated hoist (located on moving crane) under balanced condition. Bypass arrangement for balancing pressure shall be included.




SECTION - 4 - GENERAL TECHNICAL REQUIREMENTS

4.1 GENERAL

Design of all the works shall be made by the DEC in two steps, namely:

a. Basic Design performed before the start of construction work.

b. Detailed Design performed before and during construction of the Project.

The DEC shall advise Owner on all additional field and laboratory investigations needed to fulfill the design and construction requirements.

4.2 FUNCTIONAL REQUIREMENTS

The DEC shall plan and design complete and fully functional civil and hydro-mechanical works for Shrinagar Hydro Electric Power Project for various components and shall be capable of fulfilling all the performance requirements.

4.3 LIFETIME REQUIREMENTS

The Civil and Hydro-mechanical works shall be designed and engineered by DEC and accordingly manufactured, delivered, constructed, completed, commissioned and tested by Contractors in such manner as to provide reasonable certainty that the minimum working life of them will be as per GOI gazette published in book titled Indias Electricity Sector, Widening Scope for Private Participation (this reasonable certainty is based on good engineering practices, manufacturer's specifications and guidelines and normal operation and maintenance).

The DEC shall inform the Owner of such specific parts or components in the design that have a shorter technical life time than those stated above. Such parts or components shall not be implemented in the Permanent Works without the approval of the Owner.

All materials and equipment specified as well as the design itself shall be from a recognised manufacturer/ standard and proven design.

4.4 COMPLETENESS OF FACILITIES

DEC through design and specifications shall ensure that all structures/ Equipment constructed/ erected will be complete in every respect with all embedments, mountings, fittings, fixtures and standard accessories normally provided with such equipment and/or those needed for erection, completion and safe operation of the equipments required by applicable codes though they may not have been specifically detailed in the respective specifications unless included in the list of exclusions. All similar standard components / parts of similar standard equipment provided, shall be interchangeable with one another.

4.5 DRAWINGS AND DOCUMENTS

All drawings shall be produced by using CAD (Computer Aided Design) technique, such as Auto-CAD, R13 or later version. Reports shall be produced with computer programs available in Microsoft Office, calculations on Excel spread sheet or MathCAD.




4.6 UNITS

All measures, calculations, numerical results, specifications, final documentation etc., demanded to fulfill the design requirements for the Works, shall be presented to the Owner / Owners engineer in SI-units. Angles shall be given in the 360-degree system for both surveyors work and Civil Works.

The co-ordinate reference system to be used for all Works in the Project shall be defined by a quadrant grid system. Each drawing shall contain a scale reflecting the appropriate meter spacing. The grid system shall be defined in accordance with the Indian national co-ordinate system. The elevation shall be given with zero at mean sea level as reference according to the Indian elevation system. Any deviation in following these norms must be brought to notice of Owner prior to commencement of work. DEC shall obtain clearance in such instances from Owner in writing prior to resolving / resorting such changes.

4.7 CODES AND STANDARDS

Except where specifically pointed out in these Project Requirements, all design and construction work including the materials used and methods applied shall be in accordance with Indian Standard code issued by BIS. However reference can be drawn from one or more internationally well-recognised standards of practice after approval from Owner. By definition such standards comprise e.g. ASTM (American Society for Testing and Materials), ISO (International Organisation for Standardisation), IEC (International Electro technical Commission), DIN (German Code), BS (British Standard), SS (Swedish Standard), EN (European Standard), ACI (American Concrete Institute), USBR (United States Bureau of Reclamation), USACE (US Army Corps of Engineer), ASCE (American Society of Civil Engineers).

If, for any reason, the above or equivalent standards are not available, neither applicable nor reasonable, other relevant standards shall be proposed and, if accepted, used instead.

4.8 SAFETY

The design shall be safe and robust with allowance for corrosion, unforeseen loads and varying geotechnical conditions. The design shall take full account of constructional and operational risks, including provision of a high level of safety.

The design shall be done in a timely manner to support an aggressive and well co-ordinated construction schedule also taking into account adverse weather conditions, and performed in a safe manner so that on-time completion of the Project is ensured.

4.9 SEISMIC DESIGN REQUIREMENTS

The Design of Permanent Works shall account for seismic loads basically characterised by a peak horizontal ground acceleration as recorded in the seismic parametric report prepared by CWPRS, Pune, in April 2005. DEC is expected to reconfirm from the National committee on seismic design parameters (NCSDP) as advised by CEA regarding the revised latest parameters to be adopted in design and base his designs on the same.




4.10 FUTURE MAINTENANCE

The design and composition of construction materials shall ensure sufficient durability, considering the structural details of which they form part as well as the effect of environment to which they may be exposed.

Provisions of roads, accesses etc shall be made for inspection and maintenance of all Permanent Works and to ensure easy access and safety during these operations.

The design should be made to ease commissioning, required inspections and maintenance and as well minimise loss of energy production during maintenance.

4.11 ARCHITECTURAL APPEARANCE

Powerhouse and other civil structures including dam shall have an architectural design, which fits in with the original environment and give the best exterior appearance. The interior architectural design shall be of a standard equal to or better than hydropower plants located in India.

The architectural design shall also include landscaping etc. for all areas, which are affected by the Project.




SECTION - 5 - PERFORMANCE REQUIREMENTS

5.1 GENERAL

The Contractor will construct all the structures based on the construction drawings prepared by the DEC. The DEC shall indicate the minimum acceptable criteria and accordingly Contractor shall guarantee the performance like maximum permissible leakages, head loss, opening and closing times, vibration level, ratings, capacities, shape, size, alignment and other performance figures required as per BIS codes and Technical Specification of the system/ equipments after conducting the performance tests. The DEC shall note that in the event of any deficiencies in meeting the guaranteed figures, Owner may at his discretion accept the system/ structure/s after deducting the liquidated damages as specified in the bidding documents or get the defects repaired by any other agency and recover the cost of repair. Adequate instrumentation and control systems shall be installed in the dam and appurtenant works for continuous surveillance of performance period of 12 months after taking over by the Owner.

5.2 CIVIL WORKS

A Test Programme of all tests for the civil works that are to be carried out by the Contractor shall be prepared and furnished by the Owner for review and acceptance. The Test program and procedure shall be included in the Specification to be prepared by DEC. In addition to as given in relevant BIS codes, the Test Program shall include the following minimum:

a. General Performance requirements:

i. Watering-up and dewatering tests

ii. Leakage/ water tightness tests

iii. Cracking

iv. Seepage

v. Out of size, shape and alignment

vi. Others

b. Structure-wise Specific Performance requirements are as given in the subsequent paragraphs. The target date/ month indicated is the calendar month starting from signing of Contract Agreement.

5.2.1 Dam and Spillway

a. Water availability in the dam i.e. the reservoir is filled up to the FRL before start of commissioning of the 1st unit in 36th month.

b. DEC shall prepare the reservoir filling procedure and criteria.

c. Reservoir levels:

i. MWL 609.800 m measured with an accuracy of + 0.005 m.

ii. FRL 605.500 m measured with an accuracy of + 0.005 m.

iii. MDDL 603.000 m measured with an accuracy of + 0.005 m.

d. Verticality test as specified in the relevant codes




e. Seepage on the downstream and in galleries 2 Lugeons.

f. Erosion on the stilling basin not acceptable.

g. The discharge facilities including the Spillway should be capable of passing the PMF taking into account to routing effect of the reservoir without the reservoir level with minimum specified freeboard shall be available under all operating conditions including during extreme floods or extreme wind conditions or winds subsequent to earthquakes or large floods.

h. All discharge facilities including spillway shall be capable in operational conditions at all times. Any deposition of silt/ debris near to dam / discharge facilities shall be minimum so that routing of floods is not impaired.

i. Hill slopes shall be adequately protected to remain stable so that they do not constitute an unacceptable risk to the safety of the dam.

5.2.2 Intake and Headrace Tunnels

a. Invert level of Intake as measured with an accuracy of + 0.005 m.

b. Intake shall have sufficient water cover under MDDL condition and no vortices should form. Based on the revised designs conforming to physical model test results, if any, DEC shall rectify formation of vortices, if any.

c. Preferably, there shall not be settlement of sediment in the tunnel. However, the reduction in cross-sectional area of the tunnel by 2% due to settlement of sediments will be the governing criteria. The non-silting velocity shall be corresponding to the design discharge in the tunnel.

d. No cracks, falling of concrete

e. No stagnant water in the tunnel after dewatering.

f. Above items will be checked by taking outage of each tunnel after 6 months of its operation.

5.2.3 Trough Over Supana Nala

No visible cracks, leakages and settlement shall occur.

5.2.4 Desilting Basin

a. Requirements on the operational scenarios in wet and in dry season shall be specified and strictly fulfilled.

b. During maintenance of any one half of the basin portion, other half portion shall operate as efficient as when the complete basin works.

c. The flushing shall be efficient with discharge not exceeding 100 m3/sec.

5.2.5 Power Channel

a. Loss of water shall not be more than 0.60 m3/sec per million m2 of wetted perimeter of lining as specified in CBIP Manual No. 171.

b. Settlement of sediment The reduction in area due to siltation shall be lesser of 2% of cross-section area of channel within one year of its operation or as specified in the BIS code or in CBIP Manual No. 171.




c. The channel shall be capable of carrying of the design discharge plus 10% overloading with sufficient (minimum) free board. The discharge shall be measured and recorded by Contractor at least two locations using current meters during commissioning/ performance tests.

5.2.6 Bypass Channel

a. The channel shall be capable of passing a required discharge under all extreme conditions.

b. No erosion or damage to the concrete lining of chute will be accepted.

c. The bypass channel shall have efficient energy dissipation arrangement on the downstream.

5.2.7 Penstocks

a. Head loss shall not be more than specified, during handing over and also after one year of its operation. The head loss shall be measured at the unit inlet valve on the calibrated pressure gauge, which is to be installed by the Contractor.

b. The acceptable limit in variation in diameter (out of roundness) and in straightness of alignment shall not be more than the specified.

c. The penstocks shall be vibration free. The acceptable vibration limit is 100 microns.

5.2.8 Powerhouse and Tailrace Channel

a. Elevation of surrounding wall of powerhouse and tailrace channel shall be above the water level with respect to HFL corresponding to 40,000 m3/sec, a landslide induced flood with provision of free board.

b. Finishing items shall be as per specifications.

c. Waterproofing of the roof shall have Guarantee during the performance period.

5.2.9 Road Works

a. The road works shall be without any potholes and unevenness.

b. All the structures shall be accessible by roads at all times including earthquake/ extreme flood condition.

5.2.10 Bridges

a. All the bridges shall be of RCC and non-submersible type and hence should not get submerged during extreme floods.

b. There shall not be failure during the highest loading for which they are designed.

c. Bridges shall meet all design requirements in terms of sizes (dimensions), cracking, and deflection as specified in MOST/ IRC standards.

5.3 HYDRO-MECHANICAL WORKS 5.3.1 Radial and Vertical Gates

a. Leakage shall under no circumstances exceed the values specified in the respective BIS codes/ specifications.




b. The operating times defined in the technical data sheets furnished by the DEC shall be guaranteed by the Contractor for the full head ranges with an accuracy of 5%.

c. Undesirable incomplete gate closure will not be allowed.

d. Wherever required, hoists shall be capable of holding intermittent position without any oil pressure loss.

e. Gates and hoists shall satisfy all shop/ performance tests as per BIS codes/ specifications.

f. Shall have vibration free and cavitations free operation at all positions and conditions.

5.3.2 Hydraulic Hoist

a. The operating speeds defined in the technical data sheets furnished by the DEC shall be guaranteed for the full head ranges with an accuracy of + 5%.

b. Working Oil Pressure as defined in the technical data sheets.

c. Test Oil Pressure as defined in the technical data sheets

5.3.3 Stoplogs

a. Leakage rates shall under no circumstances exceed the values specified in the IS codes/ specifications.

b. A vibration free and cavitations free operation in all positions.

5.3.4 Trashrack

a. Size and spacing of vertical bars shall be as specified without any tolerance.

b. Trash racks shall be vibration free.

5.3.5 Trashrack Cleaning Machine

a. The lifting capacity shall not be less than specified in the technical data sheets.

b. The operating speeds defined in the technical data sheets furnished by the DEC shall be guaranteed for the full load ranges with an accuracy of 5%.

5.3.6 Gantry Cranes

Hoists shall be electrically cum manually operated with their capacity, speed of travel, approach, access, lift, etc. shall be as specified.

5.3.7 Automatic Gates

a. The maximum rise in water level when the gates are completely open shall not be more than specified in technical data sheets.

b. The gates shall be rigid, stable and shall not hunt for small change in water level.

c. All the gates shall operate (open/ close) at water level specified in the bypass channel

5.4 VERIFICATION OF PERFORMANCE PARAMETERS

a. In order to demonstrate compliance with the Performance Guarantees, DEC to ensure that the Contractor shall prepare a detailed test procedure to be submitted for Owners acceptance not later than 90 calendar days prior to the undertaking of the performance tests.




b. The Contractor shall be responsible for carrying all the complete tests including provision of all labour, materials, instruments, instrument calibration and the cost of commissioning manager. DEC/ Owner will witness and DEC will certify all these tests.

c. In case of non-compliance of any structure or instrument to the performance requirements, Contractor shall repair, correct or replace all the defects to the satisfaction of Owner.




SECTION - 6 - HYDRAULIC DESIGN REQUIREMENTS

6.1 GENERAL

The Project shall be planned and designed by the DEC so that:

a. The needed turbine flow is conveyed at the acceptable limit of head losses (specified herein under) in accordance with the capacity requirements in a safe and dynamically acceptable manner.

b. Part of the silt that accumulates in the reservoir can be flushed through the spillway gates and low-level bottom outlets in the dam, if provided. This shall be designed for continuous operation in the wet season when the river discharge is more than the design discharge for power plant and for periodic intermittent flushing in order to save water in the dry season.

c. The design flood requirements of the Indian Standard IS: 11223 shall be fulfilled.

d. The desilting arrangement shall be capable of flushing hydraulically with either of two or both at a time, flushing systems. Both shall be designed for continuous operation in flood season and also for periodic intermittent flushing in order to save water.

e. The Contractor shall measure, verify at site and prove to the Owner of the proper functioning of the hydraulic designs, which are the results of proper operation simulations, analytical calculations and hydraulic model tests results/ recommendations.

f. Following paragraphs describe in detail the hydraulic design requirements for major structures/ project components. DEC shall ensure that these requirements are strictly met to ensure the expected power generation and smooth operation.

6.2 HYDROLOGY 6.2.1 Data

a. River flow data for 30 years, on 10 daily basis is available. The Part-I Contractor shall measure the daily flow in the river on the upstream of dam and keep record during the construction period (staring from signing of Contract till handing-over).

b. Observed silt data and ambient temperature data is also available with the Owner.

6.2.2 Floods

a. Design Floods

i. The Shrinagar dam has been classified as a large dam in conformance with Indian design safety standards. The design flood for safety of the dam shall be the Probable Maximum Flood (PMF). The relevant Indian Standards shall be followed for designs. The design floods shall be considered together with assumed failure to open one of the spillway gates. Freeboard requirements shall be met, except that the dam, being a concrete structure will require minimum freeboard during passage of the PMF.

ii. No structural damage to the main structures will be acceptable during discharge of the PMF. All structures, including the dam, spillway with energy dissipating




arrangements and appurtenant works, shall be designed so that the flood can be discharged without damages.

iii. Beyond the synthetic unit hydrograph methods, estimation of flood peaks were made by statistical methods. The following table summarises the results from the previous hydrological flood studies.

Return period in years or flood

Peak discharge (m3/sec)

100 10,300

500 12,000

1000 14,100

SPF 19,200

PMF 26,400

b. Land Slides

Floods related to landslides shall be considered in the studies. Since the Shrinagar catchment area is prone to landslides and there have been landslide-related flood events recorded in history, the design criteria must be adapted accordingly. Design criteria have therefore also been established for slide-induced floods and reservoir flood waves, respectively.

c. Slide-induced floods

i. The dam shall be safe for floods caused by such slides as could possibly occur in the catchment area upstream from the reservoir during the technical lifetime of the project. The technical lifetime of the project/ structures shall be as per the guidelines laid down by Government of India.

ii. The tender design shall facilitate the release of a slide-induced flood of 40,000 m3/s with all gates open, without jeopardising the stability of the dam. Overtopping of the dam is acceptable, provided it is demonstrated that the dam will withstand the overtopping. Significant repair works are accepted in this extreme event.

iii. Before the Basic Design period, the DEC shall perform a supplementary study of the effects of landslide-related scenarios, based on historical information, topographical maps and hydrological information together with empirically based assessments etc., to determine the size of the flood at the dam with reasonable accuracy. Such study may result in a modification of the above-stipulated requirement of 40,000 m3/s, which shall be communicated to the Owner before the Basic Design.

d. Slide-induced flood-waves

i. The dam shall also be safe for impact waves caused by slides that could possibly occur directly into the reservoir during the technical life of the project.

ii. It is required that the dam can safely withstand a slide-induced flood-wave with a height of 10 m above the Full Supply Level. Overtopping of the dam is




acceptable, provided it is demonstrated that the dam will withstand the overtopping.

iii. Before the Basic Design period, the DEC shall perform a supplementary study of the effects of waves caused by slides into the reservoir, based on historical information, topographical maps, geological information for sensitive areas including field surveys and empirically based assessments or mathematical/ physical modeling to determine wave-heights (super-elevations) at the dam and at other sensitive areas along the reservoir.

iv. Such study if result in a modification of the above stipulated requirement of a 10 m design wave height (super-elevation), which shall be communicated to the Owner before the Basic Design.

v. In the Basic Design the DEC shall demonstrate that the safety of the dam is not threatened by reservoir slide-induced waves. Destruction of gates and limited structural damage to the dam and other parts of the Project are acceptable in the flood-wave scenario.

e. Dam Break Studies

The DEC shall carryout the dam break studies. The study shall cover effect of dam failure on the downstream in terms of water spread, water levels, possible damages to the property, etc.

f. Design Flood for Temporary River Diversion Structures

The selection of the design flood for temporary river diversion structures shall be made by DEC with regard to the consequences of failure, as well as the period of operation of the structure.

Furthermore, the dimensioning of the structures depends on the Contractors schedule, construction methods and risk assessment. One objective of the design of the temporary river diversion structures shall be to avoid consequential delays of the finalisation of permanent structures. The design shall include a method statement for evaluation.

6.3 WATER CONDUCTOR SYSTEM AND STRUCTURES 6.3.1 General

a. The hydrological and hydraulic performance of the water transfer structures shall be sustained for normal operation conditions during the technical lifetime of the Project. The leakages out of these facilities shall meet the minimum performance criteria.

b. The water transfer structures shall be designed to take the full design flow of the power station including necessary flow to cater for overloading of generating units (by 10%) and flushing requirements.

c. Head losses in the water transfer system shall be evaluated for hydraulic purposes and accounted for in design for all normal operation conditions. This implies that the dimensions of the water conductor system are dictated by the design flow and the ruling hydraulic conditions upstream, downstream and within the structures themselves.




d. In case of load rejections in the power station, the water conductor system shall be designed to avoid over-topping due to open channel surges and shall have a minimum freeboard above the maximum water level shall be as per relevant BIS code.

e. The need for energy dissipating structures shall be evaluated for hydraulic and erosion purposes and be accounted for in design reports. Physical Model tests shall be got carried out by DEC to verify the function of the

i. Energy dissipating arrangements of the dam.

ii. Desilting basin

iii. Tailrace channel, etc.

f. The project shall include a valve-controlled facility in the immediate vicinity of the dam or through one of the spillway piers, adjustable for release in the range of 0 - 5 m3/sec.

g. Water conductor system structures shall be designed to be emptied by gravity only. No pumping shall be involved. To facilitate normal inspection and maintenance, the water conductor structures shall have inverts suitable for vehicle traffic, avoiding circular shape at the bottoms of conduits that may carry bed load.

h. For the optimum operation of the Project, reliable monitoring functions for the water conductor system are required. Necessary instrumentation to collect and transfer information on gate positions, reservoir and forebay water levels, as well as canal and/or tunnel water levels immediately upstream the power intake, flow measurement shall be identified in the Basic Design.

i. The tunnel intake gates shall be capable of throttling to enable controlling the discharge passing through tunnel. The gate shall be able to receive the command/ signal from instruments and operate accordingly for this purpose.

6.3.2 Reservoir

The mode of reservoir operation is quite important from the consideration of possibilities to defer sedimentation and retain sufficient storage for daily peaking generation in the future. Physical Model studies may be suggested by DEC on how best to operate the reservoir to achieve this. The model studies shall provide information on whether a draw-down below the indicated minimum draw-down level (MDDL) will be required in the future and if so this shall be quantified and accounted for in the design of the project.

The model studies shall also provide information on whether further preparations should be made at initial construction of the project to facilitate future removal or exclusion of coarse sediment particles (gravel) from the turbine flow at the river intake.

6.3.3 Dam

Many potential hydro power project sites have been identified and planned on the Alaknanda River, in cascading form, by the Government of Uttaranchal. Therefore, considering the projects planned on the upstream of the Shrinagar Hydro Electric Project following levels shall be strictly followed:

a. Full Reservoir Level (FRL) at EL 605.500 m

b. Maximum Water Level (MWL) to EL 609.800 m.




c. The minimum Draw-Down Level (MDDL) of the reservoir shall be as far as possible close/ nearest to the FRL in to enable water diversion in the water conductor system and shall not be less than EL 603.00 m.

The Contractor shall plan the construction activities of dam in such a way that the reservoir is filled up to the Full Reservoir Level well before the time of start of commissioning and testing of the first generating unit.

6.3.4 Tunnel Intakes

a. The hydraulic performance of the intakes shall be sustained so that the net flow area of the intakes is not reduced by unfavourable sedimentation build-up.

b. The intakes shall be designed and evaluated for hydraulic purposes. The entry shall be bell-mouth shaped and entrance losses shall be accounted for in design. Furthermore, the intakes shall have sufficient water cover (i.e. submergence) at MDDL condition and be designed to prevent development of vortices, which may affect proper function of desilting arrangements or increase head losses.

c. Intakes shall be designed for a maximum velocity of 1.5 m/sec calculated on the gross area (at MDDL) through the trash racks with maximum clear 10 cm spacing. The calculated head loss through intake shall not be more than 0.50 m.

d. The possible need for a bed load (gravel) excluder, possibly combined with the outlet for release of ecological flows, shall be investigated in the Basic Design.

e. The performance of the intakes may be verified in physical models as required.

6.3.5 Tunnels

a. Both the tunnels shall be identical in terms of physical sizing and hydraulic characteristics.

b. The combined water carrying capacity of both the tunnels at MDDL condition shall be equal to total design discharge for generating units (560 m3/sec) plus 10% for overloading the generating units plus the discharge required for flushing the desilting basin (maximum 100 m3/sec).

c. The surface finish of concrete lining shall be smooth with rugosity coefficient between 0.014 and 0.016. The total head loss through tunnel corresponding to discharge of 716 m3/sec shall not be more than 1.75 m.

6.3.6 Desilting

a. Desilting shall be carried out to prevent bed load and suspended sediment from entering the power channel and further to power house. The desilting arrangement shall be designed to remove all particles larger than 0.20 mm. The flushing discharge for desilting shall not be more than 100 m3/sec.

b. Requirements on the following two operational scenarios shall be fulfilled:

i. Wet season: power station operating at the design discharge or over-loaded condition - Continuous removal of 100% of particles coarser than 0.20 mm carried by the water. Reservoir inflow assumed as (steady-state) greater than 750 m3/s.




ii. Dry season: Removal (settling and flushing) of at least 100% of particles coarser than 0.20 mm carried by the river to the dam area. Reservoir inflow assumed as (steady-state) 100 m3/s.

c. The Owner wishes to minimise wastage of water due to flushing and method statements on the procedures for flushing and necessary time and amount of water for such activities shall be presented.

d. In order to verify the above requirements physical model studies are required, which shall be carried out at the reputed research institute like Central Water and Water Research Station, Khadakwasla, Pune or equivalent research station.

e. The head loss across the desilting basin shall not be more than 0.10 m.

6.3.7 Power Channel and Bypass Arrangement

a. Channel shall be provided with reinforced concrete abrasive resisting lining with smooth surface finish. The Mannings n Coefficient shall be between 0.014 and 0.017.

b. The velocity in the channel shall be non-silting and non-erosive and shall be between 1.0 and 1.8 m/sec.

c. The channel shall have prismatic section and uniform flow conditions.

d. The longitudinal slope shall be very mild and flatter than 1 in 8,000.

e. The design discharge capacity for power channel as well as for bypass channel shall be equal to the discharge required by generating units (560 m3/sec) plus 10% for overloading i.e. for 616 m3/sec.

f. The channel shall have only horizontal curves and shall be smooth. Super-elevation shall be provided to the curves, wherever required.

g. The cross-drainage works shall not obstruct the flow in channel resulting in head loss.

h. Channel shall be designed so that no material (gravel, boulders etc.) will be transported into the canals as a result of heavy rains, i.e. storm water.

i. The performance of the bypass channel, including surplus escapes at the streams shall be verified in the basic design.

6.3.8 Forebay

a. For the efficient and successful operation of the power plant, it is essential to maintain highest water level at the forebay. Water level at forebay shall be minimum at FSL 600.300 m and maximum operating water level of 601.300.

b. The automatic gates shall be capable of maintaining water surface in between these two levels

6.3.9 Penstocks

a. The penstock diameter shall be most economical.

b. The penstocks bends shall be smooth for minimum head loss. Bend centerline radius shall be three times the internal diameter of penstock and angle of each bend segment shall not be more than 60.

c. The painted inside surface shall be smooth with Rugosity Coefficient of 0.012.




d. The total head loss through penstock corresponding to design discharge shall not be more than 1.15 m.

e. Corrosion allowance of 2 mm shall be considered.

6.3.10 Power House And Tailrace

a. The power station shall be designed to sustain structurally and shall be protected against the flooding even for the discharge caused by land slides upstream or into the reservoir.

b. A tailrace channel shall have a efficient hydraulic design and of rectangular in section in RCC.

c. The channel shall be guarded against the long-term negative effects of flood-related settlement of material (boulders, gravel) in it.

d. The procedures for removal of the settled material, if any and necessary time for such activities shall be presented. In the Basic Design, the performance of the tailrace channel and potential risk of sediment deposition during flood season shall be studied in hydraulic model tests.

e. A tailrace rating curve shall be established by DEC in the Basic Design.




SECTION - 7 - GEOTECHNICAL AND GEOLOGICAL DESIGN REQUIREMENTS

7.1 GENERAL REQUIREMENTS

a. The requirements regarding geotechnical and geological design are given in order to ensure the quality, lifetime, future maintenance and overall safety of structures depending on geological / geotechnical design within the Works. The design work itself shall be conducted using best engineering as per satisfaction to the Owner.

b. The geotechnical design shall include verification measures relevant to the function of specific structures. Such measures shall be carried out continuously during construction works in order to verify the appropriateness of the design.

c. DEC shall prepare geotechnical design documents and submit them to the Owner for review, including drawings and reports containing input data, calculations and results, thereby rendering a full understanding of the design.

d. The geotechnical design requirements refer to the following project components:

i. Soil and Rock foundations including dam foundations

ii. Soil and Rock cuts

iii. Earth and Rock fill embankments

iv. Earth and Rock slopes

v. Tunnel excavation

vi. Any other structure or work defined during the Basic Design

e. The DECs Basic Design as well as Detailed Design of earth and rock structures shall include the following:

i. Comprehensive evaluation of existing geotechnical data.

ii. Additional site investigations that the DEC deems necessary in order to provide sufficient data for safe and uniform geotechnical design, e.g. detailed drilling investigations, study of groundwater conditions, testing of rock and soil samples, engineering geological mapping, etc.

iii. Site characterisation, i.e. establishing the engineering characteristics of the rock and soil masses.

iv. Rock mass classification.

v. Mechanical analysis of rock and soil to determine properties and derive failure mechanisms.

vi. Support and stabilisation measures including calculations to verify that the design fulfils long-term stability requirements.

vii. Definition of the proper construction methods to meet the geotechnical design requirements.

DEC is fully responsible for the design as well as the functioning of structures associated with the Works. Furthermore, the DEC shall be responsible for the sampling and interpretation of the geotechnical and geological data as well as the characterisation of the rock and soil masses connected with the Works.




7.2 CODES AND STANDARDS

Except where pointed out in this specification, all materials and test methods used in the design and construction phases of geotechnical structures shall be in accordance with relevant IS standards.

IS: 4880 Code of practice for design of tunnels conveying water (All parts)

IS: 4756 Safety code for tunneling work

IS: 5878 Code of practice for construction of tunnels (All parts)

IS: 4081 Safety of code for blasting and related drilling operations

If, for any reason, the above standards are not available or clearly neither applicable nor reasonable, other internationally, well-recognised standards shall be proposed.

7.3 LOADS AND FORCES 7.3.1 General

The following loads are to be considered for geotechnical and/or civil design of structures:

a. Dead loads

b. Pore pressure and uplift

c. Water pressure

d. Earth pressure

e. Silt load

f. Earthquake loads

g. In-situ stresses

h. Live loads

7.3.2 Special Design Considerations

a. Pore Pressure/Uplift

Pore pressures shall be derived from existing site-specific information or from additional site investigation results.

b. Active pressure

Static active pressure against vertical or nearly vertical structural surfaces shall be calculated using Rankine or Coulomb's theory, as appropriate. For active conditions to exist, the structure must yield or tilt at least 1/1,000 of its height under this pressure. For seismic loading, dynamic earth pressure shall be considered.

c. At rest pressure

At rest soil pressure shall be applied wherever the structure does not yield or tilt under the load of a compacted fill.

d. Passive pressure

Passive soil pressure on vertical or nearly vertical structural surfaces shall be calculated using Rankine or Coulomb's theory as appropriate. In order to develop full




passive pressure, the structure must yield or tilt toward the soil at least 1/100 of its height.

e. Earthquake

The DEC shall consider seismic loads as per seismic parametric study report and relevant IS codes.

Earthquake loads are assumed to have no effect on the water pressures considered for uplift.

7.3.3 Earth Retaining Structures

a. Stability

i. Design factor of safety of structures for sliding and overturning shall be based on relevant IS codes of standards for different structures. Wherever applicable sliding factor of safety incorporate partial factor of safety in respect of friction and partial factor of safety in respect of cohesion.

ii. Maximum bearing pressure shall always be less than allowable bearing pressure for occasional loads, increase in allowable bearing pressure values shall also be taken wherever applicable.

b. Design

In estimating earth pressures on retaining structures, at-rest pressures (Ko) shall normally be used. Design shall be carried out based on relevant IS codes along with applicable permissible stresses.

c. In Situ Stress Magnitudes and Orientations

From the design requirements stated for geotechnical structures and/or foundations of such structures it is explicit that the DEC shall present how the three-dimensional stress state has been calculated, what assumptions have been made and, if necessary, how stresses and their orientations will be observed or assessed. Therefore, the DEC shall include for stress measurements should the DEC expect that such actions must be taken in order to provide valid input data for optimised design according to the requirements.

It shall be noted that the horizontal/vertical stress ratio is strongly effected by topographic conditions. Analyses shall be performed so as to assess the impact of differing in-situ stress environments on stress concentrations.

7.4 ROCK MASS PROPERTIES 7.4.1 Rock Mass Classification

For the rock mass classification in the underground excavations, the Rock Tunneling Quality Index (Q) proposed by the Norwegian Geotechnical Institute shall apply. The final definitions of rock classes shall be determined jointly by the DEC and the Owner when the geotechnical conditions have been made fully available and satisfactorily recognised.

The need for classification of rock outside of underground excavations shall be determined by the DEC and presented to the Owner in the Basic Design along with suggested applicable classification system.




7.4.2 Assessment of Discontinuity Properties

Average shear strength values shall be determined for the principal discontinuities based on precedent experience and an assessment of the nature of the discontinuity surfaces recovered during the complementary site investigation programme managed by the DEC.

7.4.3 Rock Mass Failure Criterion

For stability analyses in the design process, the DEC shall use either Mohr-Coulombs or Hoek-Browns failure criterion as appropriate.

7.4.4 Intact Rock Strength

The intact uniaxial compressive strength of the rock values shall be determined by means of point load testing and/or unconfined compression strength testing on selected rock core samples obtained from the vicinity of relevant rock structures.

7.4.5 Rock Mass Deformability

Deformation modulus values for the rock mass shall be determined on the basis of correlation between the rock mass classification system(s) proposed by the DEC and deformation modulus established and as per engineering practices.

7.4.6 Sliding Stability Analyses

The DECs method for sliding stability analyses shall be identified in the Basic Design. Shear strength parameters for use in the assessment of the sliding stability of structures founded on rock shall be calculated based on an assessment of the expected condition of the foundation or discontinuity surface, the nature of the sliding surface, the strength of the rock or concrete on either side of the sliding surface and the normal stress condition which will exist under the loading condition analysed.

Parameter values used in the analyses shall be established on the basis of testing of representative rock core samples where such are available, or by using conservative lower bound estimates for the parameters as determined from data available for similar rock types.

7.5 DESIGN OF UNDERGROUND STRUCTURES

The design requirements given in this section apply to the permanent underground structures for the Works including:

a. Tunnels

b. Any other critical underground structures which may be identified during the Basic Design

Temporary access tunnels, adits and alike shall be excavated and supported so as to ensure the safety during the underground works and the scheduled advancing rate. Temporary access tunnels shall further be sealed / plugged as required. The design of the underground structures shall include:

a. Design of rock excavation, i.e. excavation method, equipment, advancing rate etc.,

b. Design of rock supports




7.6 DESIGN OF ROCK EXCAVATION

Rock excavations shall be designed so that the surrounding rock is disturbed as little as possible and no surrounding property belongings to Owner or by others is damaged or disturbed. DEC shall ensure that the Contractor shall be liable for compensation for such damages / disturbances. The design of the rock excavation shall account for ambient conditions, type of rock support, final finishes of the underground structures, etc.

The design and technical specification for the rock excavation shall comprise:

a. Excavation methods for tunne

Documents

Design Criteria(R0)