Sample DPR for Hydro Project (10 MW) (2012)

Sagana III Hydro Electric Project (2 x 5000 KW)

Detailed Project Report

Lucid Power Generation Limited

Kibagare Way, Next to the Mexican Embassy,

Loresho, P.O. Box 66244 – 00800,

Nairobi, KENYA

Ph: +254 736222065

Consultants

D 449, Sector 4, Phase II, New Shimla,

Near DAV School, Shimla 171 009,

H.P., India

Phone: +91 177 26 72 945

Fax: +91 177 26 72 945

http://www.scg-india.com March 2012

http://www.scg-india.com/

Contents

Chapter

Number Name of the Chapter Page Numbers

Executive summary Executive Summary 1

1. Introduction 1- 1 to 1 - 11

2. Justification of the Project 2 – 1 to 2 - 5

3. Infrastructure facilities 3 – 1 to 3 - 7

4. Survey & Investigation 4 – 1 to 4 - 3

5. Hydrology 5 – 1 to 5 - 17

6. Power Potential and Installed Capacity 6 – 1 to 6 - 10

7. Geology 7 – 1 to 7 - 6

8. Civil Engineering Structures 8 – 1 to 8 - 28

9. Electro Mechanical 9 – 1 to 9 - 17

10. Construction Plan & Program 10 – 1 to 10 - 7

11. Construction Materials 11 – 1 to 11 - 3

12. Project Organization 12 – 1 to 12 - 7

13. Environmental & ecological aspects 13 – 1 to 13 - 7

14. Estimates of cost 14 – 1 to 14 - 19

15. Financial Evaluation 15 – 1 to 15 - 18

16. Appendix I Photographs Appendix I - 1 to 5

17. Appendix II Drawings Appendix II - 1 to 51

ABBREVIATIONS

cum Cubic meter

Cumecs Cubic meter per second

DPR Detailed project Report

El. Elevation

FC Financial Charges

FSL Full Reservoir Level

GOK Government of Kenya

GWh Gigawatt Hour

ha Hectare

HEP Hydro Electric Project

hr Hour

IDC Interest During Construction

km Kilometer

kv Kilovolt

kVA Kilovolt Ampere

kW Kilowatt

kWh Kilowatt Hour

m Meter

MDDL Minimum Draw Down Level

MT Metric Tonne

MU Million Units

MVA Megavolt Ampere

MW Megawatt

Sec Second

SLD Single line diagram

TWL Tail Water Level

USD United States Dollars ($)

WARMA Water Resource Management Authority

List of Drawings

Sr. No. Drawing No. Name of drawing

CIVIL DRAWINGS

1 1 General Layout of Project (sheet 1/6)

2 General Layout of Project (sheet 2/6)





7 2 Plan of trench weir

8 3 Sections of trench weir

9 4 Water conductor system -Sections

10 5 Sections of tunnel (sheet 1/4)

11 Sections of tunnel (sheet 2/4)



14 6 Desilting tank – Plan & Section Details

15 7 Desilting tank – section details-1

16 7 Desilting tank – section details-2

17 8 Forebay Plan

18 9 Forebay Section

19 10 Plan & section of penstock

20 11 Plan of Power house

21 12 Section of Power house

22 13 Plan & section of TRP & TRC

HYDRO MECHANICAL DRAWINGS

23 14 Diversion weir trash rack-1

24 Diversion weir trash rack-2

25 15 Forebay trash rack-1

26 Forebay trash rack-2



29 16 Stop log gate panel-1

30 Stop log gate panel-2

31 17 Stop log gate embedment-1

32 Stop log gate embedment-2

33 18 Service gate panel -1

34 Service gate panel -2

Sr. No. Drawing No. Name of drawing

35 19 Service gate embedment -1

36 Service gate embedment -2

37 20 Shingle flushing gate panel – 1

38 Shingle flushing gate panel – 2

39 21 Shingle flushing gate embedment -1

40 Shingle flushing gate embedment -2

41 22 Penstock gate panel-1

42 Penstock gate panel-2

43 23 Penstock gate embedments-1

44 Penstock gate embedments-2

45 24 DT gate Panel -1

46 DT gate Panel -2

47 25 DT gate embedment - 1

48 DT gate embedment - 2

ELECTRICAL DRAWINGS

49 26 Single line diagram

50 27 Switchyard (1 of 2)

51 Switchyard (2 of 2)

Detailed Project Report Sagana-III HEP Chapter 1 – Executive Summary & Introduction

Executive Summary - 1

Executive Summary

The Ministry of Energy, Government of Kenya has invited proposals from Independent Power

Producer (IPP) companies for developing Hydro Electric Projects. To pursue the same,

promoters of Lucid Power Generation Limited have identified Sagana-III Hydro Electric Project

(2 x 5000 KW) on the Sagana River in Nyeri District (Central Province) of Kenya. Strategic

Consulting Group, a hydro power consulting firm from India has been appointed as technical and

financial advisor for the project.

The Sagana-III HEP is located approximately 180 Kms from Nairobi. The project envisages

utilizing the water of Sagana River through a diversion structure at an elevation of 1274m. The

Power house is located at an elevation of 1210 m. The main components include trench weir, de-

silting arrangement, ~4.8 Km long water conductor system (containing 2 Nos. Tunnel), Forebay

and one number main buried penstock which at later stage has been bifurcated. The scheme

proposes to utilize a gross head of 58.46m to generate 10 MW of power, with a rated discharge

of 21.26 Cumecs. The power will be evacuated through a ~7 km long 132 KV transmission line

to the 132 KV Sagana-Kutus line in Sagana Town.

The catchment area at the diversion site of Sagana-III HEP is 1460 sq. Kms. The average annual

rainfall received in the catchment area is 1200mm. Hydrology studies have been conducted

based on annual flow data from WARMA. Based on hydrology data, it is estimated that the

project will generate around 54 Million Units of electricity in a 75% dependable year.

Carbon emission reduction analysis has been done for the project. The project is likely to result

in an emission reduction of close to 38,690 tons of CO2, which will translate into around 145,120

USD of revenue for the project (assuming 75% share for the developer).

The project is likely to cost 22.97 Million USD. The major components of this cost are Civil

works (11.79 Million USD), Electromechanical works (5.76 Million USD), Indirect Charges,

Financial Charges including Interest during Construction & Construction Cost Escalation (5.42

Million USD).

Financial analysis of the project has been conducted, and results have been found to be

encouraging. The average DSCR over the loan repayment period is 1.54x, while the minimum

DSCR is 1.41x. The equity IRR in the base case is found to be 16.12%. Sensitivity results

conducted on key variables indicate that the project has cushion to absorb variations in

assumptions. The project is found to be techno-economically feasible and commercially viable,

and should be pursued further.

Detailed Project Report Sagana III HEP Chapter 1 – Introduction

Chapter 1 - 1

Chapter 1: Introduction


Chapter 1 - 2

1.1 Introduction

The Ministry of Energy, Government of Kenya has a mandate to facilitate the provision of clean,

secure, sustainable and affordable energy services for socio-economic development while

protecting the environment. In accordance with its mandate the Ministry has invited proposals

from Independent Power Producer (IPP) companies for developing Hydro Electric Projects. The

Ministry of Energy has fostered an environment conducive to private participation in such

projects which in addition to adding to the energy generation capacity of the country will help in

creating local employment opportunities as well.

1.2 Promoters

Promoters of Lucid Power Generation Limited has more than 20 years of operating presence in

Africa, and specifically in Kenya. With a vast experience in design, engineering, execution,

renovation and commissioning of hydro projects, Lucid is comfortably placed to execute a hydro

power project from concept to commissioning. Lucid Power is keen on investing in the

opportunity provided by the Ministry of Energy, Government of Kenya.

Sagana-III Hydro Electric Project (HEP) is a (2 x 5000kW) project on the Sagana river in Nyeri

District (Central Province) of Kenya, and is being considered under the same opportunity.

Specific details in terms of project location & design are provided in this report.

1.3 Consultants for the project

Strategic Consulting Group (SCG) is an Indian hydro power development and consulting firm

located in Shimla, Himachal Pradesh, India. SCG provides concept to commissioning services

for hydro and other renewable energy projects. The promoters of Lucid Power Generation

Limited have appointed SCG as technical & financial advisors for the project.

A technical team from SCG conducted a thorough topographical survey of the project area over a

period of two months. Based on the survey, the components of the project were placed. The

discharge data was collected from Water Resource Management department (WARMA) of

Government of Kenya, and analyzed. Hydraulic design studies were conducted for the sizing of

the various civil and hydro mechanical components. A study was also conducted on the

availability and cost of the raw material and labour. With the help of all the collected primary

and secondary data, a detailed techno-economic project report has been prepared for the project.

The studies conducted and the conclusions arrived at have been described in detail in this report.

The studies conducted and the conclusions arrived at have been described in detail in this report.


Chapter 1 - 3

1.4 Project location

The project is located in Nyeri district in the Central Province of Kenya. The project site is at a

distance of 180 Kms from the national capital Nairobi and is well connected by road.

Map of Kenya with location of the project

Sagana-III (10 MW)


Chapter 1 - 4

1.5 Project Description

Sagana-III Hydroelectric project (HEP) is proposed as a run-of-the-river project on River Sagana

in Nyeri district (Central province) of Kenya.

The project envisages utilizing the water of the Sagana River through a diversion structure at an

elevation of 1274m. The co-ordinates of the intake structure are 0°34'49.31"S, 37° 9'1.60"E. The

Power house is located at an elevation of 1210 m. The co-ordinates of the power house are

0°36'52.64"S, 37°10'45.79"E. With a proposed rated discharge of 21.26 Cumecs, and a gross

head of 58.46 m, the project will have a capacity of 10 MW.

The diversion structure for the Sagana-III HEP at 1274m benefits from the availability of a good

bench on the right bank. This allows for easy placement of diversion structure components such

as headworks, de-silting chamber, connecting channel etc. Not much earth work is envisaged to

be required and there is availability of construction power at the intake site.

A good gradient is available for the placement of the water conductor channel/ pipe all along the

right bank. The water conductor consists of combination of an RCC rectangular channel and

tunnels of lengths of total length ~4800 m.

From the forebay a buried penstock of ~175m length is used to draw the discharge to the turbines

which at later stage will be bifurcated. After bifurcation, the branches are of length around ~15.5

m & diameter of 1.9 m each has been envisaged which feeds 5MW turbines (2 nos.).

A Surface Powerhouse has been envisaged at an elevation of 1210m on the right bank of the

Sagana River. From the powerhouse a Tail Race Channel of about 4.65 m bed width and approx.

10m length discharging tail waters of power house back to Sagana River will be designed

The scheme thus proposes to utilize a gross head of around 58.46m & a rated discharge of 21.26

Cumecs to generate 10 MW of power. To utilize the mentioned discharges, two numbers Francis

Horizontal with runner overhung on generator shaft type turbines with a rated capacity of (5000

kW) have been proposed.

The power generated shall be evacuated from the switchyard of Sagana-III HEP via a ~7km

transmission line to the substation in Sagana town for the 132 KV Sagana – Kutus line.

As per the Net Slope Level (NSL) observed all along the project area, it is seen that adequate

bench will be available for placement of appurtenant features: e.g. Diversion structure, RCC

Channel/ pipe, Forebay, penstock (buried), Surface Power house, Switchyard etc. Area required

for construction sites is also available near the site.


Chapter 1 - 5

Photographs of project areas taken during site visit are included as Annexure 2. The location of

the project on topo-sheet (1:50,000 scale) is also shown in Annexure 2. The drawings showing

project components are included as Annexure 3.

The table below provides the salient features of the proposed scheme.

Table 1: Salient Features

Sl. No. Particulars Details

A Location:

a State Kenya

b District Nyeri

c Province Central Province

d Village Ithanji, Mutundu

e Toposheet no. 135/1

f Longitude 370 10’ 46” E

g Latitude 000 36'52” S

h Stream/Khad Sagana

i River Sagana

j Basin Tana

k Nearest town Nyeri-30 km

l Nearest Air port Nairobi -180 km

B Hydrological data

a Catchment area sq.km. 1,460.00

b Climate

c Altitude m 1210.00

d Mean Annual Rainfall mm 1200 mm

e Temperature o C 5

o to 27

o C

f Minimum Discharge cumecs

g Maximum Discharge cumecs 226.17

h Estimated Flood discharge cumecs 301.59

C Features of the project

a Project Type Run Off River

D Head works:

a Type of diversion weir Trench type

b Design Discharge cumecs 24.45

c Length of weir m 25.00

d Width of weir mm 3.80

e Depth of weir m 3.50

f Bed slope of weir 1 in 16.00


Chapter 1 - 6


g FSL in Trench weir m 1,274.00

h Upstream mat Boulder mat enclosed in wire

mesh

i Thickness of mat blocks mm 1500

j Length of mat mesh m 10

k Slope of Mat mesh 1 in 20

l Downstream mat Boulder mat enclosed in wire

mesh

m Thickness of mat blocks m 1500

n Length of mat mesh m 10

o Slope of Mat mesh 1 in 20

p High Flood Level at Weir site m 1,276.70

E Details Of Intake Gates

a Stop log gate

i No. of gates Nos. 1

ii Size of gate (Clear opening) m 3.80

iii Type of gate Screw type

b Service gate



iii Type of gate Screw type

c Silt flushing gate



iii Type of gate Valve with spindle

iv Height of stem rod 10.40

F Water Conductor System

1 Intake to D-tank

Approach Tunnel

a Design discharge cumecs 29.34

b Bed width m 4.60

c Full supply depth m 3.20

d Free board m 0.90

e Bed slope 1 in 1130

f Length of tunnel m 1260.00

g Reduced level at beginning of tunnel m 1,274.00

h Reduced level at end of tunnel m 1,272.88

2 Approach channel



Chapter 1 - 7


b Bed width m 4.60


d Free board m 0.90

e Bed slope 1 in 1130

f Length of channel m 90

g Reduced level at beginning of channel m 1,272.88

h Reduced level at end of channel m 1,272.80

3 De-silting chamber

a Length m 56.00

b Bed width m 10.00

c Water depth m 6.67

d Design discharge cumecs 29.34

e Diameter of Silt Flushing pipe mm 1,000.00

f Size of Silt gutter mm 1000 x 1000

g Slope of gutter 1 in 25.00

4 Desilting Tank to Forebay

Power channel-1


b Type Rectangular

c Bed width m 4.20

d Full supply depth m 2.90

e Free board m 0.90

f Bed slope 1 in 1010.00

g Length of channel 745.00

h Reduced level at beginning m 1272.80

i Reduced level at end m 1272.06

5 Tunnel


b Bed width m 4.20


d Free board m 0.90

e Bed slope 1 in 1,010.00

f Length of tunnel m 2,340.00

g Reduced level at beginning of tunnel m 1,272.06

h Reduced level at end of tunnel m 1,269.74

6 Power channel-2


b Type Rectangular


Chapter 1 - 8


c Bed width m 4.20


e Free board m 0.90

f Bed slope 1 in 1,010.00

g Length of channel 370.00

h Reduced level at beginning m 1,269.74

i Reduced level at end m 1,269.37

G Forebay:


b Storage capacity duration minutes 3

c Capacity m3 4,401.00

d Length of spillway m 40.00

e Breadth of spillway m 18.00

f Drawdown depth m 6.18

g Forebay top m 1,270.27

h Forebay bottom m 1,256.62

i F.S.L. level of Forebay m 1,269.37

j M D D L m 1,263.19

k Crest of Waste Weir m 1,269.37

H Penstock

1 Main Penstock

a No. of penstocks Nos. 1

b Diameter penstock Mm 2,700

c Design discharge cumecs 24.45

d Length of penstock M 175.00

e Center of penstock take off at forebay M 1,259.36

2 Branch Penstock

a No. of penstocks nos. 2

b Diameter penstock Mm 1,900.00

c Design discharge cumecs 12.23

d Length of each branch penstock M

e Center of penstock at power house M 1,209.91

I Power House

a Type of Power House Surface

b Dimensions M 28.25 x 16.8 x 18M

c Machine Hall Floor Level M 1,210.00

d Service/ unloading bay M 1,215.00

e Centre line of machine m 1209.91


Chapter 1 - 9


f Nos. of DT Gates Nos. 2

g Dimensions of DT gate m 3.0 x 2.0

h Type of gate Vertical slide Lift gate, MS Steel

i High Flood Level m 1,211.90

J Tail Race Channel

a Type & Shape RCC / Rectangular Ducts

b Length m 10.00

c Bed width m 4.65


e Free board m 0.90

f Maximum tail Water level m 1,213.50

g Minimum tail water level m 1,210.91

K Electrical And Mechanical

Equipment

1 Design data

a Rated Unit Discharge cumecs 10.63

b Net Head at Rated Discharge m 55.76

c Gross Head m 58.46

d Site Elevation m 1,210.00

e Water Temperature 0C

f Setting to Tailwater m (1.00)

g Efficiency Priority 10.00

h Rated Head/Best Eff. Head 55.76

i System Frequency Hz 50

j Minimum Net Head m 46.99

k Plant rated discharge cumecs 21.26

l Plant max. discharge cumecs 24.45

2 Turbine

a Unit capacity KW 5,000.00

b Unit capacity with overload KW 5,750.00

c Number of units Nos. 2

d Rated Plant capacity KW 10,000.00

e Max. Plant capacity KW 11,500.00

f Runner diameter mm 1,288.00

h Turbine speed Rpm 428.00

i Runaway speed Rpm 774.00

j Inlet diameter mm 1,524.00

3 Generator


Chapter 1 - 10


a Type of Generator Synchronous

b Rated Capacity kW 5000

c Maximum capacity kW 5750

d No. of Generators Nos. 2 nos.

e Generation Voltage level Kv 11KV

4 Power evacuation

a Dimensions of switchyard m

b E.L. of Switchyard m 1,215.00

c Voltage KV 11 /132

d Transmission line Km 20

e Location of feeding s/s Sagana Kutus Line

f Voltage level KV 132 KV

M Land acquisition

1 Forest/Govt. land Ha 15.62

2 Private land Ha 0.00

3 Total land requirement Ha 15.62

N Cost of the project

1 Civil Works USD MM 11.79

2 E & M USD MM 5.76

O/W Transmission Work USD MM 0.29

Total cost without IDC & FC USD MM 17.55

3 Indirect Cost USD MM 0.13

(a) Total direct & indirect cost USD MM 17.68

4 Initial Working capital, capitalized

spares

USD MM 0.27

5 Interest during Construction, Financial

Charges

USD MM 1.41

6 Escalation during construction USD MM 1.18

7 Contingency USD MM 1.24

8 DSRA Cost loaded upfront USD MM 1.20

(b) Total USD MM 5.29

9 Total (a) + Total (b) USD MM 22.97

10 Capacity 10

11 Cost per MW USD MM 2.30


Chapter 1 - 11


12 Total project cost USD MM 22.97

O Financial results

1 IRR % 16.12

2 Payback period Years 9

3 DSCR Average 1.54

4 Average cost of generation USDc/Unit 5.08

Detailed Project Report Sagana III HEP Chapter 2 – Justification of the project

Chapter 2 - 1

Chapter 2 –Justification of the Project


Chapter 2 - 2

2 Energy situation in Kenya

A fast growing power sector is crucial to sustain Kenya’s economic growth. Kenya has an

assessed hydropower potential to the tune of 9,000 MW; out of this less than 15% has been

developed so far. In the past various factors such as the dearth of adequately investigated

projects, environmental concerns, resettlement and rehabilitation issues, land acquisition

problems, regulatory issues, long clearance and approval procedures, power evacuation

problems, the dearth of good contractors, and in some cases, law and order problems have

contributed to the slow pace of hydropower development. There have been large time and cost

overruns in case of some projects due to geological surprises, resettlement and rehabilitation

issues, etc. However, considering the large potential and importance of hydropower in promoting

the country’s energy security and flexibility in system operation, the Government is keen to

accelerate hydropower development. Many of the factors that lead to delays in implementation of

power projects are being addressed through a number of legislative and policy initiatives by the

Government.

2.1 Demand & Supply situation in Kenya

The total nameplate power generation capacity of the Republic of Kenya is 1,473 MW and the

peak electricity demand (for 2009-10) was 1,107 MW. Though the name place capacity is higher

than the peak demand, this does not give a true picture of the electricity demand supply scenario

in the country. Firstly, there is lack of connectivity with only around a quarter of the population

having access to electricity. Then there are problems with the network which often result into

shutdowns. Thirdly, a significant part of the electricity generation comes from short term HFO

and HSD fired thermal plants which are expensive and are damaging for the environment.

Finally, even though the name plate capacity seems sufficient, breakdowns and inefficiencies

often result in plants operating at less than peak capacity. Also Kenya has a very low per capita

energy consumption of ~ 160 kWh/year against a world average of 2,429 kWh/year, thus leaving

an enormous room for growth. The peak electricity demand has been increasing at a CAGR of

5% for the last five years, and in 2013, the demand is expected to increase to 1,527 MW.


Chapter 2 - 3

Table 2.1: Total Power: Demand vs. Installed

2007/08 2008/09 2009/10

YoY

growth

08/09 vs

07/08

YoY

growth

09/10 vs

08/09

Peak Demand (MW) 1036 1072 1107 3% 3%

Installed capacity (MW) 1310 1345 1473 3% 10%

Effective Capacity (MW) 1267 1280 1416 1% 11%

Reserve Capacity margin % 12% 9% 15% Source: Kenya Power & Lighting Company

Chart 2.1: Kenya Power Scenario: Demand Vs Installed Capacity

Source: Kenya Power & Lighting Company

2.2 Power capacity in Kenya

According to the generation data available for the year 2009, a significant amount of power in

Kenya is produced by Hydro Power Projects (42%). The bulk of this electricity is tapped from

five generating plants along the River Tana. The five stations combined - Kindaruma, Kamburu,

Gitaru, Masinga and Kiambere - have an installed capacity of more than 400 MW. There are also

several small hydro stations - Mesco, Ndula, Wanjii, Tana, Gogo Falls and Selby Falls - all built

before independence in 1963, with a combined generation output of 40 MW.

0

200

400

600

800

1000

1200

1400

1600

2007/8 2008/09 2009/10

Peak Demand (MW) Installed capacity (MW) Effective Capacity (MW)


Chapter 2 - 4

Thermal power (HFO & HSD) together form almost 36% of the total energy generated.

Chart 2.2: Distribution of Power Source

Source: Energy Regulatory Commission; Kenya

Due to a severe shortage in power in the year 2000-01, for the first time HSD was used to

generate power (~660 GWh) after which it was used again 2006-07 onwards and still continues

to be used in spite of it being one of the most expensive sources of power.

Chart 2.3: Annual Energy (GWh) Actual (1998-99 to 2008-09)

Source: Energy Regulatory Commission; Kenya

Gas Turbine 4%

High Speed

Deisel, 17%

Heavy Fuel Oil,

19%

Geothermal,

17% Non Firm Hydro, 5%

Firm Hydro, 37%

0

200

400

600

800

1000

1998-99 1999-00 2000-01 2001-02 2002-03 2003-04 2004-05 2005-06 2006-07 2007-08 2008-09

GT High Speed Deisel Heavy Fuel Oil GeothermalNon Firm Hydro Firm Hydro Uganda Electricity Board


Chapter 2 - 5

2.3 Need for the project

Small Hydro Power is an important, reliable, eco-friendly and renewable source of energy. It has

a low environmental impact and minimal issues of displacement of the local population. Its

principle advantage is the ability to start and stop the plant quickly and instantaneous load

acceptance/rejection. The long life of the hydro power plants, the renewable nature of the energy

source, very low operating and maintenance costs, absence of inflationary pressures experienced

by the fossil fuels are some of the other advantages. Kenya is blessed with a vast hydro power

potential in its perennial river Basins. The speedy exploitation of hydroelectric power potential,

with minimum cost and with minimum environmental negative consequences, will definitely

improve the economic health of Kenya.

Sagana-III Hydro Electric Power project is a promising site for development. The perennial

Sagana River originating from the Aberdare forest, the ease of approach to the site areas, the

central location of the project, makes it an attractive and feasible site for development.

Detailed Project Report Sagana III HEP Chapter 3 - Infrastructure Facilities

Chapter 3 - 1

Chapter 3-Infrastructure Facilities


Chapter 3 - 2

3 Infrastructure facilities

Development of adequate infrastructure is a pre-requisite for timely implementation of the

project. Establishment of proper infrastructure considering the existing facilities in the nearby

area and the requirement of different worksites for various activities goes a long way in speedy

execution of the works minimizing delays in project completion.

3.1 Location of the project

Sagana-III H.E. Project is situated on Sagana River near Ithanji, Mutundu village in Nyeri

district of Central Province. This project is contemplated as a run-of-the river scheme. It

envisages Trench type weir located downstream of the power house of the proposed Sagana II

HEP.

3.2 Transportation

The Project area is 30 kms from the Nyeri Town and approximately 180 kms from the capital

city of Nairobi.

3.3 Infrastructure Facilities

The following infrastructure facilities will be required at the project site area.

Access roads in the Project area to various work sites, camps, offices, muck disposal area,

job facility sites, etc.

Bridge works.

Residential buildings for the Project staff & offices including their electricity and provision

of water supply, sanitation & drainage works.

Non-residential buildings

Telecommunication network

Construction Power

3.4 Project Roads

The Appurtenant structures of Sagana-III HEP are well connected by road. There are motorable

mud tracks running throughout the length of the project.

3.4.1 Intake


Chapter 3 - 3

The intake structure of the Sagana-III Hydro Electric project is downstream of the power

house of the proposed Sagana II Hydro Electric power project. A motorable mud track

runs parallel to the water conductor throughout its length. A ~1 km road will have to be

constructed to connect the mud track to the diversion site.

3.4.2 Power House

The power house site is connected by a motorable mud track on the right bank. However

patches totaling to a length of 700m will have to be reconstructed to make it worthy to

transport the various equipment to the power house site.

3.4.3 Other approach roads

Approach roads to Quarry sites/Borrow areas

Approach road to inlet & outlet portal of the Head Race tunnel

Haul roads to dumping areas for muck disposal

Approach roads to explosive magazine, Crusher, B&M plant, Stores, Workshops

Penstock fabrication yard, Sheds etc.

Sr. No. Description Length (m)

1 Road for intake site 1000

2 Road for Power house site 700

3 Tunnel I Inlet & Outlets 1000

4 Other approach roads 300

Total 3000

3.5 Manpower Requirement, Availability & Accommodation

3.5.1 Project Authority

The total number of permanent Operating and Maintenance staff required for the project is

estimated to be about 10 persons working in two shifts. However, during construction stage, the

staff requirement shall be more and shall be provided accordingly and housed near the flat area

available near Othaya town or Nyeri Town.

3.5.2 Contractor

Manpower for the construction of Civil, Hydro-mechanical and Electro-mechanical works will

be required to be provided by the Contractor. The total number of engineers, officers and


Chapter 3 - 4

workers of various disciplines to be deployed by the contractor will be planned commensurate

with the construction program. For the contractor staff the area will be provided near project site.

3.5.3 Labour

Unskilled labour is available near the project site. Skilled labour will have to be arranged from

the nearby towns of Nyeri, Othaya & Muranga. Labour to be deployed during construction stage

will be accommodated near work sites.

3.5.4 Accommodation

Rented Accommodation is available in Othaya, Nyeri and Muranga. These will be of use to carry

out the pre-construction activities. Temporary structures will be erected to house workmen and

labour at the site.

A workshop to carry out the fabrication work during construction is proposed near the power

house. This will work as service bay for the power house post commissioning.

3.6 Construction Plant and Job Facility

The various installations that will erected by the contractor for the construction plant for

construction works will be as follows:

3.6.1 Crushing Plant

Two crushing plants of size 80 TPH and 60 TPH shall be located near the power.

3.6.2 Batching and Mixing Plant

As per requirement of concreting at various work sites, the batching and mixing plant of

80 cum/hr capacity for Intake, Water channel, Head race tunnel, Penstock, Powerhouse

and appurtenant works.

3.6.3 Penstock Fabrication Yard

Site for fabrication of Penstock ferrules will be provided on the right bank of Sagana

River downstream to the project area. This area will also be used for storing of E & M

equipment on their receipt. Electrical & Mechanical, Heavy machinery workshop, E&M

equipment storage yard and storage area for cement & steel will be provided in the

acquired area.


Chapter 3 - 5

3.7 Construction power

The peak demand for power for construction activities is estimated to be about 1.2 MW taking

the capacities of electric driven equipment and lighting purpose. The initial requirement of power

for construction activities in the first year would be about 0.8 MW and this may subsequently

increase to 1.2 MW.

In addition to grid supply, it is also proposed to provide supplemental power by diesel sets as

standby in case of interruptions in grid supply.

The breakup of peak demand has been estimated as follows:

Sr. No. Description Capacity Unit Rating

(kW)

1 Capacity of Crushing Plant (at Intake) 80 TPH 240

Capacity of Crushing Plant (powerhouse) 60 TPH 180

2 Batching and Mixing Plant (near tunnel) 80 Cubic m/hour 240

3 Contractor workshops etc. 250

4

Electrification & other miscellaneous in

project areas LS - 200

Total ~1200

3.8 Construction Material

The construction material survey for availability of coarse and fine aggregates shall be carried

out during Geological mapping. Suitable sites shall be identified and a crushing plant will be

installed at suitable location near to the quarry site to crush and process the stone materials for

use as coarse and fine aggregates. Sand deposits will also be identified during Geological

mapping for use as fine aggregates.

3.9 Communication Facilities

The different work sites of the project offices, stores, laboratories, workshops and residences etc

will be connected by a telecommunication network. The telecommunication facilities will also be

provided between the project and the outside. All important sites of the works, offices and

residences of senior officers will be connected by telephone. Suitable number of mobile phones /

wireless radios (walky-talky) would also be provided.


Chapter 3 - 6

3.10 Muck Disposal Areas

The construction activities will generate a significant quantity of muck which will have to be

disposed off at appropriate locations in line with the topographic conditions. The quantity of

muck expected to be generated from various work sites is tentatively assessed to be as under.

Sl. No. Structures Approximately Muck Quantity Cum

1 Diversion works 1555.55

2 Water Channel 18150.42

3 Desilting Tank 10640.45

4 Tunnel 20412.00

5 Forebay 5359.54

6 Penstock Before Bifurcation' 2698.18

7 Penstock After Bifurcation 936.00

8 Power House 4495.14

9 Switchyard 5008.64

10 Tail Pool 4216.58

11 Tail Race Channel 118.30

Total 73590.78

Muck disposal areas for the above mentioned quantities have to be identified during construction

and will be developed by providing stable slopes and adequate berms, so that muck flow in to the

river is avoided.

3.11 Explosive Magazine

In order to cater for blasting requirements of various work sites, it is estimated that around 50

MT of gelatin will be required, along with proportionate quantity of detonators. Portable site

magazines of 500 kg capacity will also be provided to cater to the day to day requirement of

explosives. Explosive van will be used for the transport of explosives from the magazine to the

work sites. All safety codes and regulations prescribed by the Government in this respect will be

followed and magazines will be suitability guarded round the clock. Necessary permits &

licenses will be taken from the concerned authorities for use of these explosives.


Chapter 3 - 7

3.12 Transportation

Sagana-III HEP is well accessible by road. A motorable mud track connected to the

Kiawamururu road connecting Mukurwe-ini to the Thika road (A2 highway).

3.13 Site Safety & Insurances

Adequate arrangements for lighting, security etc. will be made in the project area. Adequate

preventive measures against accidents will be taken in accordance with the international

construction site safety norms. The project work sites will have restricted entry and visitors will

only be allowed on permits issued by the project authority. All work force and other project

personnel will be provided with identity cards and passes issued by the Project authority which

will be checked at the entry check posts located at suitable places. Adequate insurances will be

maintained by Project Company and contractor.

Detailed Project Report Sagana III HEP Chapter 4 - Survey & Investigation

Chapter 4 - 1

Chapter 4 - Survey & Investigation


Chapter 4 - 2

4 Topographic Survey

The Senior Engineers of the consultant have done preliminary identification of layout at site in

association with representatives of M/s Lucid Power Generation Limited. The principal

components of the project were identified. Subsequently, visits were conducted for carrying out,

topographical surveys and to freeze the layout of site and establish the feasibility of the project.

Reconnaissance of the project was carried out and location of the principal components of the

project was identified. The essential topographical surveys as detailed below were carried out to

decide upon the general layout of the project and to identify the exact location of the various

components of the scheme. The toposheet no. 135/1 in the scale of 1:50000 were procured for

the project area. The detailed topographical surveys carried out for various components of the

project are as follows:-

4.1 General Layout:

The topographical surveys for general layout of the project extending from about 500 m

upstream of the proposed diversion structure and covering the area up to the proposed power

house and appurtenant works site has been carried out in the scale of 1:500 with 1m contour

interval. Different alternatives have been studied and general layout of the various components

of the project has been marked indicating the proposed location of the diversion structure, intake,

silt flushing channel/conveyance channel, desilting tank, water conductor system, forebay,

penstock and power house and appurtenant structures. Components wise detailed surveys carried

out are as follows:-

4.1.1 Diversion structure:

Detailed topographical survey for location of diversion structure, covering about 500 m

upstream and up to the proposed desilting tank, 10 m above the anticipated highest flood

covering both the banks at the proposed location has been carried out in the scale 1:500 with

contour interval of 1m.

4.1.2 Desilting tank:

Detailed topographical survey at the proposed location of desilting arrangement in the scale of

1:500 with contour interval of 1 m.


Chapter 4 - 3

4.1.3 Water Conductor System:

Detailed topography strip survey along the proposed alignment of water conductor system

including conveyance channel, silt flushing channel, desilting tank/power channel/tunnel and

forebay tank has been carried out in the scale of 1:500 with conductor interval of 1 m covering

an area of 20 m on the hill side and 20 m on the valley side.

4.1.4 Forebay and Penstock:

Detailed topographical survey of the proposed location of forebay and surface penstock in the

scale of 1:500 with contour interval of 1 m has been done for carrying detailed engineering

studies of the structure.

4.1.5 Power house area:

Topographical surveys of the proposed power house area in the scale of 1:500 with contour

interval of 1 m covering tail race channel, switchyard and extending to the other side of the river

has been done . Water level and high flood marks have also been recorded.

4.2 Hydrological Studies

The daily flows measured at station on River Sagana (code 4AA05), River Chania (code 4AC04)

and River Gura (code 4AD01) of WARMA were procured to analyse to flow and the power

potential for Sagana III HEP. The data was made available from January 1966 to December

1986. The data points spanning over 20 years was considered sufficient to form a long term

series for all hydrological calculations. For the detailed analysis for hydrology and power

potential calculations please refer to chapter 5 & Chapter 6 respectively.

4.3 Geological investigation

Geological investigations shall be conducted at the Detailed Engineering stage. Surface geology

report for the project area will be prepared by an experienced geologist. Sub-soil explorations

will be carried out by drilling cores and testing samples in a laboratory. More details are

provided in Chapter 7.

4.4 Power evacuation

The power generated from Sagana III HEP shall be evacuated through a double/single circuit 132

kV, ~7 Km transmission line to the Sagana – Kutus line at Sagana.

Detailed Project Report Sagana III HEP Chapter 5 - Hydrology

Chapter 5 - 1

Chapter 5 - Hydrology


Chapter 5 - 2

5 General

This chapter describes the study of the hydro-meteorological characteristics of the catchment

area and the methodology used for establishing various hydro-meteorological metrics, which in

turn serves as inputs for the project planning and design. The hydrological analysis has been

carried out encompassing the following:

Assessing the availability of water for power generation by establishing a long- term

series of average 10 day daily discharge for the project site.

Establishing the design flood.

5.1 Catchment Description & Characteristics

Sagana III HEP is situated on the Sagana River which finds its origins in the dense Aberdare

Forest. The River flows in the South East direction till it meets River Gura near the town of

Ngunguru. The catchment area at the diversion site of Sagana III HEP is 1460 sq. Kms, out of

which over 50% is in dense forest area (Aberdare Forest).

5.2 Climate

Sagana III HEP (10 MW) is located in the Central Province of Kenya. The climate of Central

Province is generally cooler than that of the rest of Kenya, due to the region's higher altitude.

The temperature varies between 7ºC to 30ºC. The period from February to March is the hottest

while the one from July to August is the coldest.

5.3 Rainfall

Rainfall is fairly reliable in the Central Province. There are two rainy seasons in Kenya: one

from early March to June (the long rains) and a second during October and November (the short

rains). The average annual rainfall received in the catchment area is 1200mm (as per the Rainfall

gauges at Embu Metrological station, Sagana Technical School, Sagana State lodge, etc.). The

rainfall, being spread over two seasons and a number of months in the year, results in lower

variation in the discharge of the river over the year. The mean annual runoff at the diversion

structure is estimated to be 518.97 MCM.

5.4 Sediment Load


Chapter 5 - 3

The Sagana River carries significant sediment load during the rainy months. The river bed is

characterized by an accumulation of boulders of different sizes along the course of the River.

The size of the boulders varies from small pebbles to big boulders.

5.5 Water Quality

The water in the Sagana River is free from any kind of pollution till the intake site of the Sagana

III HEP. However it is murky and turbid during the rains. The sediment load analysis shall be

done at the detailed engineering stage.

5.6 Flow Variation

The flow in the rivers the in Aberdare and Mount Kenya region changes seasonally and differs

from year to year, due to temporal and spatial variation in precipitation. The flow pattern in the

Sagana River is no exception to this. The variation in flow in the Sagana River can be seen in the

months of March to June (the long rains) and a second during October and November (the short

rains).

5.7 Available data

The discharge data for the Sagana River has been collected over a period of 20 years from 1966

to 1986 by Water Resource Management (WARMA) department of Govt. of Kenya. We have

summed the individual discharges for River Sagana, River Chania and River Gura before their

confluence points and adjusted for the catchment area till the intake site of Sagana III HEP. The

discharge stations for River Sagana (code 4AA05) and River Chania (code 4AC04) are located

upstream of the confluence of River Chania with River Sagana. The discharge station for River

Gura (code 4AD01) is located upstream of the confluence of River Gura with River Sagana.

We have used this data to arrive at the 50%, 75% and 90% dependable flow years for Sagana,

with appropriate adjustment for flow on a catchment area proportion basis. The years with

incomplete data have been removed from the series to give a complete 20 year series. The

catchment of the river at the discharge stations are River Gura ~230sq Kms, River Chania

~370sq Kms, River Sagana ~800sq Kms (totaling to ~1400 sq Kms). The effective catchment at

the intake point of the Sagana III HEP is 1460 sq. Kms. The discharge has been suitably

increased by multiplication with the catchment area factor (1460/1400 = 1.04).

The ten daily combined discharge data for the Sagana River at the diversion structure of Sagana

III HEP is being shown in the following pages:


Chapter 5 - 4

Average Ten Day Daily Discharge of the Sagana River at the Diversion Structure

From Jan 1960 to Dec 1967 Catchment at Sagana III Intake 1460 sq. kms

PERIOD 1960 1963 1964 1966 1967

10 day

JAN 1 10.45 17.45 25.86 14.82 9.49

2 8.53 19.07 16.44 11.09 8.28

3 10.33 20.02 11.62 11.58 7.38

FEB 4 8.44 14.02 10.11 10.18 6.92

5 9.20 12.74 9.73 10.03 6.36

6 7.61 9.94 7.75 12.93 6.18

MAR 7 6.58 12.83 8.26 11.68 6.35

8 8.92 16.68 9.97 10.66 6.74

9 15.82 16.16 19.27 24.07 5.62

APR 10 22.56 15.21 41.87 50.20 9.13

11 34.77 35.64 67.42 58.04 16.73

12 31.26 110.93 103.62 103.09 12.44

MAY 13 43.32 118.02 56.16 80.25 55.60

14 21.35 109.62 56.44 42.39 75.01

15 17.36 66.48 41.27 27.14 44.68

JUN 16 15.20 98.34 29.60 23.82 34.37

17 12.37 50.43 24.20 22.62 25.86

18 11.23 33.72 16.87 19.61 21.33

JUL 19 10.97 16.75 14.14 15.07 17.23

20 9.31 12.80 13.57 13.13 18.87

21 8.27 10.71 15.62 12.11 21.03

AUG 22 7.95 11.08 19.15 11.38 17.67

23 8.35 14.57 18.08 10.88 18.54

24 10.47 10.08 16.26 13.61 17.60

SEP 25 9.86 8.60 14.03 13.44 18.27

26 11.39 6.47 14.82 11.02 15.14

27 11.80 7.14 14.06 12.27 15.14

OCT 28 14.25 7.40 17.01 9.75 15.46

29 13.85 11.77 21.27 9.79 26.53

30 20.24 8.54 23.70 22.29 62.75

NOV 31 33.29 15.56 20.39 44.61 51.93

32 34.14 16.32 19.93 35.32 56.50

33 20.08 25.17 21.83 25.20 85.17

DEC 34 12.19 52.76 30.60 17.09 38.17

35 11.62 34.60 24.71 14.04 24.80

36 11.68 30.25 21.29 10.66 19.87

Yearly Average 15.42 29.94 24.91 23.50 24.98

Inflow, Million Cu M 486.19 944.23 785.68 740.99 787.69


Chapter 5 - 5



PERIOD 1968 1969 1970 1971 1972

10 day

JAN 1 14.91 16.86 9.23 8.53 14.53

2 12.26 14.31 13.95 11.16 13.14

3 10.78 16.47 22.27 7.48 11.83

FEB 4 9.97 13.86 13.22 6.95 22.02

5 11.69 12.66 10.30 6.98 19.61

6 36.21 15.14 10.05 4.98 14.33

MAR 7 59.14 15.82 10.21 4.37 13.18

8 44.09 16.21 11.54 4.91 10.17

9 34.63 18.50 16.82 5.39 9.09

APR 10 45.91 15.32 37.44 6.79 12.22

11 59.43 19.03 31.73 13.97 12.33

12 131.77 17.13 52.64 24.69 11.65

MAY 13 79.12 39.04 64.05 56.81 24.65

14 49.32 70.93 50.07 53.19 28.03

15 47.24 32.46 28.74 42.23 39.75

JUN 16 37.73 18.99 22.98 27.56 37.45

17 34.56 14.45 19.90 18.85 30.10

18 26.95 12.33 16.47 17.25 30.04

JUL 19 23.10 11.31 15.67 15.73 20.65

20 21.07 10.57 12.60 17.89 17.03

21 19.61 10.39 11.47 15.10 14.55

AUG 22 18.16 10.33 10.67 14.77 15.88

23 18.40 10.45 11.51 18.52 20.35

24 18.90 9.99 14.03 23.66 18.03

SEP 25 14.85 9.98 14.33 17.97 12.84

26 13.98 14.39 12.92 13.70 11.58

27 12.71 9.97 11.82 13.97 13.93

OCT 28 11.94 8.82 12.01 13.35 21.74

29 14.34 14.74 23.32 16.67 34.91

30 26.76 10.02 16.59 14.30 43.15

NOV 31 36.90 10.48 17.95 14.04 65.78

32 26.27 13.44 16.36 12.80 58.97

33 85.13 23.32 18.46 15.21 60.21

DEC 34 94.70 15.25 12.30 13.18 37.35

35 37.27 10.61 10.37 11.99 24.80

36 22.30 8.87 10.19 16.69 17.81

Yearly Average 35.06 16.46 19.28 16.71 23.99



Chapter 5 - 6



PERIOD 1973 1974 1975 1976 1978

10 day

JAN 1 17.96 9.65 10.43 12.14 13.62

2 20.54 8.61 8.22 9.18 16.38

3 14.51 7.18 7.38 7.90 11.41

FEB 4 11.17 2.85 6.83 7.51 8.71

5 18.56 3.06 5.94 7.37 8.47

6 16.68 2.35 4.98 7.66 20.24

MAR 7 11.54 8.11 5.74 7.19 20.41

8 9.63 6.66 6.07 5.72 42.18

9 8.85 8.02 5.54 6.68 39.86

APR 10 7.49 25.17 5.45 7.47 58.76

11 26.45 31.67 14.71 15.88 90.13

12 39.21 33.87 27.53 15.03 70.19

MAY 13 36.46 22.55 12.60 18.30 91.49

14 28.57 19.60 25.87 25.96 62.93

15 33.03 21.80 22.91 44.44 31.05

JUN 16 29.32 23.55 17.23 20.67 20.40

17 23.05 17.92 13.05 14.66 16.83

18 18.43 19.16 13.75 15.49 13.39

JUL 19 16.86 34.48 11.99 14.52 14.22

20 14.12 41.38 13.73 20.96 13.16

21 13.01 30.13 15.56 13.29 10.71

AUG 22 17.21 22.25 16.26 10.88 12.05

23 16.12 17.24 15.10 10.05 10.83

24 13.14 18.36 16.21 11.10 10.61

SEP 25 12.09 20.43 16.75 15.32 10.71

26 10.82 16.86 15.84 9.76 9.53

27 16.42 14.97 15.29 9.85 11.88

OCT 28 11.05 14.94 20.03 12.18 10.48

29 19.31 13.10 19.92 13.17 11.31

30 19.82 16.65 30.79 13.44 19.25

NOV 31 25.22 32.90 23.81 15.97 33.94

32 36.92 34.17 20.11 13.67 22.43

33 28.52 21.91 17.79 17.06 20.56

DEC 34 17.64 16.90 19.27 23.06 19.89

35 12.27 14.22 16.21 22.30 20.00

36 11.08 11.65 12.44 14.64 16.58

Yearly Average 18.97 18.45 14.76 14.18 25.41



Chapter 5 - 7



PERIOD 1980 1981 1982 1984 1986

10 day

JAN 1 11.67 9.41 15.13 44.34 16.99

2 9.29 9.28 12.92 35.57 14.40

3 9.60 8.77 10.20 22.89 13.38

FEB 4 9.80 6.97 7.95 18.52 10.88

5 8.31 8.69 8.37 13.96 10.04

6 7.53 6.96 6.98 19.70 7.31

MAR 7 9.47 13.02 6.37 21.73 25.80

8 9.04 17.28 5.83 11.71 11.39

9 8.80 20.91 6.04 10.54 21.14

APR 10 17.05 29.87 35.57 17.80 9.16

11 27.33 58.25 21.40 32.41 18.62

12 22.23 49.68 42.07 31.56 62.77

MAY 13 29.48 41.44 68.60 25.27 63.72

14 45.36 60.01 89.25 17.73 52.73

15 33.11 53.96 108.71 13.31 66.85

JUN 16 22.58 29.84 48.58 14.81 40.64

17 16.82 19.92 27.05 12.73 30.05

18 19.61 17.97 20.60 13.28 25.55

JUL 19 15.74 15.23 16.70 11.70 16.95

20 11.86 16.36 13.67 11.49 15.12

21 10.05 14.11 13.17 12.92 12.49

AUG 22 10.33 15.43 11.86 10.30 9.96

23 9.64 15.45 10.41 8.52 10.08

24 9.58 13.14 10.72 10.66 9.17

SEP 25 8.33 12.56 9.47 12.24 8.61

26 7.55 10.89 9.97 15.86 11.04

27 6.82 13.68 10.07 17.11 9.88

OCT 28 6.16 15.19 9.64 53.00 21.87

29 10.47 14.94 26.71 43.73 23.26

30 10.02 26.54 43.11 57.05 24.70

NOV 31 19.58 18.04 56.34 59.80 25.45

32 30.42 21.24 34.03 90.70 22.02

33 28.66 18.37 34.07 70.94 14.41

DEC 34 20.22 14.56 39.73 55.64 19.23

35 17.88 22.85 29.93 39.90 16.33

36 14.76 19.57 22.95 30.97 24.77

Yearly Average 15.70 21.12 26.23 27.51 22.13



Chapter 5 - 8

Chart 5.1: Discharge Dependability

0.00

5.00

10.00

15.00

20.00

25.00

30.00

35.00

40.00

5% 10% 15% 20% 25% 30% 35% 40% 45% 50% 55% 60% 65% 70% 75% 80% 85% 90% 95% 100%

Discharge available 50% of Time = 21.12 CuM (1981)




Chapter 5 - 9

Chart 5.2: 10 Day Daily Discharge (Cumecs)

0.00

20.00

40.00

60.00

80.00

100.00

120.00

140.00

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36

1960 1963 1964 1966 1967 1968 1969 1970 1971 1972

1973 1974 1975 1976 1978 1980 1981 1982 1984 1986


Chapter 5 - 10

Chart 5.3: Flow Duration Curve (75% Dependable Year: 1969)

0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

80.00


Chapter 5 - 11

5.8 Dependable flow

We have used this data to arrive at the 50%, 75% and 90% dependable flow years for Sagana,

with appropriate adjustment for flow on a catchment area proportion basis. The flow data for

forty years was then arranged in descending order of annual flow, to calculate the 50%, 75% &

90% dependable years. The following result was obtained:

50% dependable year = 1981



5.9 Design Flood

Though there are many methods available for design flood estimation they are region specific

and Dicken’s method has been found best for design flood estimation of Hilly streams. Two

methods have been used to estimate the design flood for the project, they being:

a) Exceedance probability method

b) Gumbel's method

The calculations for the Exceedance probability method are shown below:

Sr.

No.

Year Flood

Peak

(Cumecs)

Flood Peak

Descending

(Cumecs)

Rank

(b)

Frequency

(a)= y/(b)

Chance %

=100/(a)

1 1952 71.79 226.17 1 34.00 2.9

2 1953 68.25 214.07 2 17.00 5.9

3 1954 103.81 208.28 3 11.33 8.8

4 1955 70.08 207.27 4 8.50 11.8

5 1959 60.74 201.56 5 6.80 14.7

6 1960 62.15 184.79 6 5.67 17.6

7 1961 208.28 176.58 7 4.86 20.6

8 1962 126.78 152.66 8 4.25 23.5

9 1963 207.27 149.89 9 3.78 26.5

10 1964 184.79 144.01 10 3.40 29.4

11 1965 107.43 138.92 11 3.09 32.4

12 1966 144.01 135.13 12 2.83 35.3

13 1967 152.66 131.88 13 2.62 38.2

14 1968 201.56 130.75 14 2.43 41.2

15 1969 113.76 128.71 15 2.27 44.1

16 1970 101.24 126.78 16 2.13 47.1

17 1971 85.92 113.76 17 2.00 50.0

18 1972 100.21 113.34 18 1.89 52.9

19 1973 83.81 112.84 19 1.79 55.9


Chapter 5 - 12

Sr.

No.

Year Flood

Peak

(Cumecs)

Flood Peak

Descending

(Cumecs)

Rank

(b)

Frequency

(a)= y/(b)

Chance %

=100/(a)

20 1974 85.66 107.43 20 1.70 58.8

21 1975 68.35 103.81 21 1.62 61.8

22 1976 68.11 101.24 22 1.55 64.7

23 1977 130.75 100.21 23 1.48 67.6

24 1978 128.71 85.92 24 1.42 70.6

25 1979 113.34 85.66 25 1.36 73.5

26 1980 84.96 84.96 26 1.31 76.5

27 1981 112.84 83.81 27 1.26 79.4

28 1982 176.58 71.79 28 1.21 82.4

29 1983 214.07 70.08 29 1.17 85.3

30 1984 149.89 68.35 30 1.13 88.2

31 1985 226.17 68.25 31 1.10 91.2

32 1986 135.13 68.11 32 1.06 94.1

33 1987 131.88 62.15 33 1.03 97.1

34 1988 138.92 60.74 34 1.00 100.0

No. of floods = y = 34

The magnitude of flood having frequency of 100 years = 100/100 = 1

From graph the flood discharge = 300 Cumecs


Chapter 5 - 13

Chart 5.4: Sagana River Flood

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150

160

170

180

190

200

210

220

230

240

0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 100.0 110.0

Flo

od

Pea

k i

n C

um

ecs

Chance Percent


Chapter 5 - 14

Chart 5.5: Sagana River Flood Peaks (Cumecs)

0

50

100

150

200

250

1950 1955 1960 1965 1970 1975 1980 1985 1990

FLO

OD

PEA

K C

UM

ECS

YEAR

SAGANA RIVER FLOOD PEAKS ( Cumecs)


Chapter 5 - 15

The calculations for the Gumbel’s method are shown below:

Sr.

No. Year

Flood

Peak

(Cumecs)

Flood Peak

(Qp)

Descending

(Cumecs)

Rank

(b)

Frequency

(a)=

(y+1)/(b)

Chance %

=100/(a) Qp

2

1 1952 71.79 226.17 1 35.00 2.9 51152.2

2 1953 68.25 214.07 2 17.50 5.7 45827.2

3 1954 103.81 208.28 3 11.67 8.6 43380.0

4 1955 70.08 207.27 4 8.75 11.4 42961.5

5 1959 60.74 201.56 5 7.00 14.3 40626.3

6 1960 62.15 184.79 6 5.83 17.1 34146.9

7 1961 208.28 176.58 7 5.00 20.0 31178.8

8 1962 126.78 152.66 8 4.38 22.9 23305.4

9 1963 207.27 149.89 9 3.89 25.7 22467.0

10 1964 184.79 144.01 10 3.50 28.6 20739.1

11 1965 107.43 138.92 11 3.18 31.4 19300.0

12 1966 144.01 135.13 12 2.92 34.3 18260.9

13 1967 152.66 131.88 13 2.69 37.1 17391.3

14 1968 201.56 130.75 14 2.50 40.0 17096.1

15 1969 113.76 128.71 15 2.33 42.9 16566.3

16 1970 101.24 126.78 16 2.19 45.7 16072.2

17 1971 85.92 113.76 17 2.06 48.6 12940.5

18 1972 100.21 113.34 18 1.94 51.4 12846.8

19 1973 83.81 112.84 19 1.84 54.3 12733.8

20 1974 85.66 107.43 20 1.75 57.1 11540.8

21 1975 68.35 103.81 21 1.67 60.0 10775.6

22 1976 68.11 101.24 22 1.59 62.9 10249.9

23 1977 130.75 100.21 23 1.52 65.7 10043.0

24 1978 128.71 85.92 24 1.46 68.6 7381.8

25 1979 113.34 85.66 25 1.40 71.4 7337.5

26 1980 84.96 84.96 26 1.35 74.3 7217.6

27 1981 112.84 83.81 27 1.30 77.1 7024.8

28 1982 176.58 71.79 28 1.25 80.0 5154.0

29 1983 214.07 70.08 29 1.21 82.9 4911.8

30 1984 149.89 68.35 30 1.17 85.7 4672.0

31 1985 226.17 68.25 31 1.13 88.6 4658.7

32 1986 135.13 68.11 32 1.09 91.4 4638.8

33 1987 131.88 62.15 33 1.06 94.3 3863.2

34 1988 138.92 60.74 34 1.03 97.1 3689.9

Σ 4219.92 Σ 602151.80


Chapter 5 - 16

Mean peak discharge

Qp = 4219.920912 / 34

= 124.12

Mean of squares

Qp2 =

602151.8 / 34

= 17710.35

Standard deviation σ = [ y

[Qp2 - (Qp)

2]]

1/2

y-1

= 34 / (34 - 1 )

= 48.73

Frequency factor 'k' values for 46 years for 100 years

30 3.653 Therefore for 34 years = 3.642

35 3.598

The expected peak discharge for a flood having a = Qp + kσ

frequency of 100 years

= 124.12 + 3.642 x 48.73

= 301.59 Cumecs

Detailed Project Report Sagana III HEP Chapter 6- Power Potential and Installed Capacity

Chapter 6 - 1

Chapter 6 - Power Potential and Installed

Capacity


Chapter 6 - 2

6 General

The assessment of amount of power that could be generated at the Sagana III Hydro – Electric

Power project and the related determination of generating capacity to be installed at this power

project have been made in accordance with the best internationally accepted technical practices,

recommendations and guidelines for small hydro power projects. This is a principal step towards

deriving the parameters of technically and economically suitable projects considering the

expected water availability at the intake site over the years, the seasonal variation in water flow,

the available head and the other related factors influencing the project dimensions.

The principal factors for this assessment are:

a) The available discharge of the Sagana River for different levels of dependability,

b) The appropriate head which can be developed based on actual topographic conditions,

c) The placement of the appurtenant structures of the project on the available topography.

6.1 Hydrological Data

A detailed analytical study of Hydrological data as prescribed for the project has been provided

in Chapter 5 – Hydrology. The calculations have been made on the basis of the discharge data for

the Sagana River collected over a period of 20 years from 1966 to 1986 by Water Resource

Management (WARMA) department of Govt. of Kenya. We have summed the individual

discharges for River Sagana, River Chania and River Gura before their confluence points and

adjusted for the catchment area till the intake site of Sagana III HEP. The discharge station for

River Sagana (code 4AA05) is located around11 Kms upstream of the Sagana III Intake site,

before the confluence of River Chania with River Sagana. The discharge station for River Chania

(code 4AC04) is located upstream of the confluence of River Chania with River Sagana. The

discharge station for River Gura (code 4AD01) is located around12 Kms upstream of the Sagana

III Intake site, before the confluence of River Gura with River Sagana. We have used this data to

arrive at the 50%, 75% and 90% dependable flow years for Sagana, with appropriate adjustment

for flow on a catchment area proportion basis. The years with incomplete data have been

removed from the series to give a complete 20 year series with appropriate adjustment for flow

on a catchment area proportion basis. The flow data for forty years was then subjected of the

weibull distribution analysis to calculate the 50%, 75% & 90% dependable years. The duration

curve of a 75% year is expected to give a fair approximation of the average flow over the


Chapter 6 - 3

operative range of discharges. The discharge data worked out for a 75% year can thus form the

basis for optimization of installed capacity on energy generation basis.

6.2 Calculation of Net Head

The calculations for arriving at the net head are shown below:

Sr. No.

Particulars Calculations

A Design Data

a FSL at forebay = 1,269.37 m

b MDDL in forebay = 1,263.19 m

c Tail Water Level - Min = 1,210.91 m

d Tail Water Level - Max = 1,213.50 m

e Max. head variation = 100%

f Min. Head variation = 90%

g Design discharge = Qmax = 24.45 cumec

h Diameter of penstock =Dm = 2.70 m

i Length of penstock = Lmp = 180.00 m

j No. of bends = 5 Nos

k No of reduces = 2 Nos

l No. of valves = 2 Nos

m No of Y-piece = 1 Nos

n Gravity constant =g = 9.81 m/sec2

o Co-efficient for fritional loss =f = 0.012

p coefficient for bend loss =P = 0.060

q Entrance velocity =Ve = 0.750 m/sec

r Frictional velocity =Vf = 4.270 m/sec

s Velocity in bends =Vb = 4.270 m/sec

t Velocity in reducers =Vr = 4.270 m/sec

u Velocity in Valves Vv = 4.270 m/sec

v Velocity in y piece =Vy = 4.270 m/sec

B Design Calculations

(Reference- Manual on planning & design of small HEP, page-72

(i) Entrance loss = hffe = ( 0.1 * Ve2)/(2*g)

= 0.1 x 0.75^2) / (2 x 9.81)

= 0.003 m

(ii) Friction loss = hffr = (f * Lmp * Vf2)/ ( 2 * g * Dm)

= ( 0.012 x 180 x 4.27^2) / (2 x 9.81 x 2.7)


Chapter 6 - 4

Sr. No.


= 0.74 m

(iii) No of bends = N1 = 5

Bend losses = hfb = N1*P * Vb2/2*g

= ( 5 x 0.06 x 4.27^2) / (2 x 9.81)

= 0.279 m

(iv) No of reduces = N2 = 2

Loss in reducer pipe =hfr = N2*(0.25*Vr2/2*g) m

= ( 2 x 0.25 x 4.27^2) / (2 x 9.81)

= 0.465 m

(v) No. of valves =N3 = 2

Loss in valve = hfv = N3(0.25*V2/2*g)

= ( 2 x 0.25 x 4.27^2) / (2 x 9.81)

= 0.465 m

(vi) No of Y-piece =N4 = 1

Loss in Y-Piece = hfy = N4 *(0.8*Vm2/2*g)

= ( 1 x 0.8 x 4.27^2) / (2 x 9.81)

= 0.743 m

Total Losses (say ) =hfp = hffr+hfe+hfb+hfr+hfv+hfm

= 2.70 m

Head Calculations

(i) Max. Head = Gross head =Hmax = FSL in forebay - TWL min

= 1269.37 - 1210.91

= 58.46 m

(ii) Rated Head = Hrated = Gross head / Max. Head range

= 58.46 / 1

= 58.46 m

(iii) Min. Head = Hmin = MDDL in forebay - TWL max

= 1263.19 - 1213.5

= 49.69 m

(iv) Min. Head (based on turbine parameters)

= Rated Head x min head variation

= 58.46 x 0.9

= 52.61 m


Chapter 6 - 5

Sr. No.


Min. Head –lower of above two = 49.69 m

(v) Net Max. Head =Hmax(net) = Max. Head - Head loss

= 58.46 - 2.7

= 55.76 m

(vi) Net Rated Head =Hrated(net) = Rated Head - Head loss

= 58.46 - 2.7

= 55.76 m

(vii) Net Min. Head =Hmin(net) = Min. Head - Head loss

= 49.69 - 2.7

= 46.99 m

ABSTRACT

1 FSL at forebay = 1269.37 m

2 Tail Water Level - Min = 1210.91 m

3 Tail Water Level - Max = 1213.50 m

4 Max. Head = Gross head = 58.46 m

5 Min. Head = 49.69 m

6 Max. Net Head = 55.76 m

7 Rated Head = 55.76 m

8 Min. Net Head = 46.99 m

9 Total losses = 2.70 m

6.3 Energy Generation at different installed capacities

Optimization studies have been conducted to determine the optimum installed capacity of the

project. For study of power output and generation ten daily discharges as per 75% dependability

has been considered for various installed capacities form 7 MW to 14 MW on an incremental

basis of 1 MW.

Corresponding to the minimum discharge available during the lean season in the Sagana River

and the Gross head of 58.46m, the Francis turbine has been considered for study. An overall

efficiency of 86% (91% Turbine efficiency, 96% Generator efficiency and 98.5% Gear box

efficiency), has been used.

The power output from the project both in terms of MW, as well as energy generation in MU

with installed capacities ranging from 7 MW to 14 MW has been calculated. The detailed

calculations for assessment of power potential afforded by the project for various installations

are shown below:


Chapter 6 - 6

MW 7 8 9 10 11 12 13 14

Total energy

generated in GWh 48.98 50.86 51.99 52.95 53.75 54.47 55.19 55.91

Plant Load Factor 80% 73% 66% 60.4% 56% 52% 48% 46%

Incremental energy

increase, GWh - 1.88 1.13 0.96 0.80 0.72 0.72 0.72

Generation

(GWh/MW) 7.00 6.36 5.78 5.30 4.89 4.54 4.25 3.99

% Utilization 80% 83% 85% 86% 87% 89% 90% 91%

PLF (lean season) 76% 67% 60% 54% 49% 45% 41% 38%

Rated discharge

(Cumecs) 14.90 17.02 19.15 21.28 23.41 25.53 27.66 29.79

Chart 6.1: Increase in Capacity vs. Incremental Energy:

-

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

1.80

2.00

44.00

46.00

48.00

50.00

52.00

54.00

56.00

58.00

7 8 9 10 11 12 13 14

Total energy generated in GWh Incremental energy increase, GWh


Chapter 6 - 7

Chart 6.2 Generation vs. PLF

Based on a 75% dependable year, the scheme will generate around 52.95 Million Units (at 100%

availability and no overloading) of Energy with an installed capacity of 10 MW.

6.4 Energy Generation

Power output and energy generation, both restricted and unrestricted on a ten daily basis for 75%

dependable discharge on the Sagana River are shown in the tables below:

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

44

46

48

50

52

54

56

58

7 8 9 10 11 12 13 14

Pe

rce

nta

ge

GW

h

MW

Total energy generated in GWh Plant Load Factor


Chapter 6 - 8

7

MONTH PERIOD 75% discharge 15% of lean Net Discharge Unrestricted Unrestricted

Restricted

Power Energy

10 day

Sagana III

HEP discharge cumecs Power, MW Power, GWh 7 MW GWh

JAN 1 16.86 1.32 15.54 7.30 1.75 7.00 1.68

2 14.31 1.32 12.98 6.10 1.46 6.10 1.46

3 16.47 1.32 15.14 7.12 1.71 7.00 1.68

FEB 4 13.86 1.32 12.53 5.89 1.41 5.89 1.41

5 12.66 1.32 11.34 5.33 1.28 5.33 1.28

6 15.14 1.32 13.82 6.49 1.56 6.49 1.56

MAR 7 15.82 1.32 14.49 6.81 1.63 6.81 1.63

8 16.21 1.32 14.88 6.99 1.68 6.99 1.68

9 18.50 1.32 17.18 8.07 1.94 7.00 1.68

APR 10 15.32 1.32 14.00 6.58 1.58 6.58 1.58

11 19.03 1.32 17.71 8.32 2.00 7.00 1.68

12 17.13 1.32 15.80 7.43 1.78 7.00 1.68

MAY 13 39.04 1.32 37.72 17.72 4.25 7.00 1.68

14 70.93 1.32 69.61 32.71 7.85 7.00 1.68

15 32.46 1.32 31.14 14.63 3.51 7.00 1.68

JUN 16 18.99 1.32 17.67 8.30 1.99 7.00 1.68

17 14.45 1.32 13.13 6.17 1.48 6.17 1.48

18 12.33 1.32 11.00 5.17 1.24 5.17 1.24

JUL 19 11.31 1.32 9.98 4.69 1.13 4.69 1.13

20 10.57 1.32 9.24 4.34 1.04 4.34 1.04

21 10.39 1.32 9.07 4.26 1.02 4.26 1.02

AUG 22 10.33 1.32 9.01 4.23 1.02 4.23 1.02

23 10.45 1.32 9.13 4.29 1.03 4.29 1.03

24 9.99 1.32 8.67 4.07 0.98 4.07 0.98

SEP 25 9.98 1.32 8.66 4.07 0.98 4.07 0.98

26 14.39 1.32 13.07 6.14 1.47 6.14 1.47

27 9.97 1.32 8.65 4.06 0.98 4.06 0.98

OCT 28 8.82 1.32 7.50 3.52 0.85 3.52 0.85

29 14.74 1.32 13.41 6.30 1.51 6.30 1.51

30 10.02 1.32 8.70 4.09 0.98 4.09 0.98

NOV 31 10.48 1.32 9.16 4.31 1.03 4.31 1.03

32 13.44 1.32 12.12 5.69 1.37 5.69 1.37

33 23.32 1.32 21.99 10.34 2.48 7.00 1.68

DEC 34 15.25 1.32 13.92 6.54 1.57 6.54 1.57

35 10.61 1.32 9.29 4.37 1.05 4.37 1.05

36 8.87 1.32 7.55 3.55 0.85 3.55 0.85

Total energy generated in GWh

61.45

48.98

Plant Load Factor

79.88%

Incremental energy increase, GWh

-

Generation (GWh/MW)

7.00

% Utilization

79.7%

PLF (lean season)

75.5%


Chapter 6 - 9

8 9 10 11

MONTH PERIOD

10 day 8 MW GWh 9 MW GWh 10 MW GWh 11 MW GWh

JAN 1 7.30 1.75 7.30 1.75 7.30 1.75 7.30 1.75

2 6.10 1.46 6.10 1.46 6.10 1.46 6.10 1.46

3 7.12 1.71 7.12 1.71 7.12 1.71 7.12 1.71

FEB 4 5.89 1.41 5.89 1.41 5.89 1.41 5.89 1.41

5 5.33 1.28 5.33 1.28 5.33 1.28 5.33 1.28

6 6.49 1.56 6.49 1.56 6.49 1.56 6.49 1.56

MAR 7 6.81 1.63 6.81 1.63 6.81 1.63 6.81 1.63

8 6.99 1.68 6.99 1.68 6.99 1.68 6.99 1.68

9 8.00 1.92 8.07 1.94 8.07 1.94 8.07 1.94

APR 10 6.58 1.58 6.58 1.58 6.58 1.58 6.58 1.58

11 8.00 1.92 8.32 2.00 8.32 2.00 8.32 2.00

12 7.43 1.78 7.43 1.78 7.43 1.78 7.43 1.78

MAY 13 8.00 1.92 9.00 2.16 10.00 2.40 11.00 2.64

14 8.00 1.92 9.00 2.16 10.00 2.40 11.00 2.64

15 8.00 1.92 9.00 2.16 10.00 2.40 11.00 2.64

JUN 16 8.00 1.92 8.30 1.99 8.30 1.99 8.30 1.99

17 6.17 1.48 6.17 1.48 6.17 1.48 6.17 1.48

18 5.17 1.24 5.17 1.24 5.17 1.24 5.17 1.24

JUL 19 4.69 1.13 4.69 1.13 4.69 1.13 4.69 1.13

20 4.34 1.04 4.34 1.04 4.34 1.04 4.34 1.04

21 4.26 1.02 4.26 1.02 4.26 1.02 4.26 1.02

AUG 22 4.23 1.02 4.23 1.02 4.23 1.02 4.23 1.02

23 4.29 1.03 4.29 1.03 4.29 1.03 4.29 1.03

24 4.07 0.98 4.07 0.98 4.07 0.98 4.07 0.98

SEP 25 4.07 0.98 4.07 0.98 4.07 0.98 4.07 0.98

26 6.14 1.47 6.14 1.47 6.14 1.47 6.14 1.47

27 4.06 0.98 4.06 0.98 4.06 0.98 4.06 0.98

OCT 28 3.52 0.85 3.52 0.85 3.52 0.85 3.52 0.85

29 6.30 1.51 6.30 1.51 6.30 1.51 6.30 1.51

30 4.09 0.98 4.09 0.98 4.09 0.98 4.09 0.98

NOV 31 4.31 1.03 4.31 1.03 4.31 1.03 4.31 1.03

32 5.69 1.37 5.69 1.37 5.69 1.37 5.69 1.37

33 8.00 1.92 9.00 2.16 10.00 2.40 10.34 2.48

DEC 34 6.54 1.57 6.54 1.57 6.54 1.57 6.54 1.57

35 4.37 1.05 4.37 1.05 4.37 1.05 4.37 1.05

36 3.55 0.85 3.55 0.85 3.55 0.85 3.55 0.85

Total energy generated in GWh 50.86

51.99

52.95

53.75

Plant Load Factor

72.58%

65.94%

60.45%

55.78%


1.88

1.13

0.96

0.80

Generation (GWh/MW)

6.36

5.78

5.30

4.89

% Utilization

82.8%

84.6%

86.2%

87.5%

PLF (lean season) 66.9%

59.5%

53.6%

48.7%


Chapter 6 - 10

12

13

14

15

MONTH PERIOD

10 day 12 MW GWh 13 MW GWh 14 MW GWh 15 MW GWh

JAN 1 7.30 1.75 7.30 1.75 7.30 1.75 7.30 1.75

2 6.10 1.46 6.10 1.46 6.10 1.46 6.10 1.46

3 7.12 1.71 7.12 1.71 7.12 1.71 7.12 1.71

FEB 4 5.89 1.41 5.89 1.41 5.89 1.41 5.89 1.41

5 5.33 1.28 5.33 1.28 5.33 1.28 5.33 1.28

6 6.49 1.56 6.49 1.56 6.49 1.56 6.49 1.56

MAR 7 6.81 1.63 6.81 1.63 6.81 1.63 6.81 1.63

8 6.99 1.68 6.99 1.68 6.99 1.68 6.99 1.68

9 8.07 1.94 8.07 1.94 8.07 1.94 8.07 1.94

APR 10 6.58 1.58 6.58 1.58 6.58 1.58 6.58 1.58

11 8.32 2.00 8.32 2.00 8.32 2.00 8.32 2.00

12 7.43 1.78 7.43 1.78 7.43 1.78 7.43 1.78

MAY 13 12.00 2.88 13.00 3.12 14.00 3.36 15.00 3.60

14 12.00 2.88 13.00 3.12 14.00 3.36 15.00 3.60

15 12.00 2.88 13.00 3.12 14.00 3.36 14.63 3.51

JUN 16 8.30 1.99 8.30 1.99 8.30 1.99 8.30 1.99

17 6.17 1.48 6.17 1.48 6.17 1.48 6.17 1.48

18 5.17 1.24 5.17 1.24 5.17 1.24 5.17 1.24

JUL 19 4.69 1.13 4.69 1.13 4.69 1.13 4.69 1.13

20 4.34 1.04 4.34 1.04 4.34 1.04 4.34 1.04

21 4.26 1.02 4.26 1.02 4.26 1.02 4.26 1.02

AUG 22 4.23 1.02 4.23 1.02 4.23 1.02 4.23 1.02

23 4.29 1.03 4.29 1.03 4.29 1.03 4.29 1.03

24 4.07 0.98 4.07 0.98 4.07 0.98 4.07 0.98

SEP 25 4.07 0.98 4.07 0.98 4.07 0.98 4.07 0.98

26 6.14 1.47 6.14 1.47 6.14 1.47 6.14 1.47

27 4.06 0.98 4.06 0.98 4.06 0.98 4.06 0.98

OCT 28 3.52 0.85 3.52 0.85 3.52 0.85 3.52 0.85

29 6.30 1.51 6.30 1.51 6.30 1.51 6.30 1.51

30 4.09 0.98 4.09 0.98 4.09 0.98 4.09 0.98

NOV 31 4.31 1.03 4.31 1.03 4.31 1.03 4.31 1.03

32 5.69 1.37 5.69 1.37 5.69 1.37 5.69 1.37

33 10.34 2.48 10.34 2.48 10.34 2.48 10.34 2.48

DEC 34 6.54 1.57 6.54 1.57 6.54 1.57 6.54 1.57

35 4.37 1.05 4.37 1.05 4.37 1.05 4.37 1.05

36 3.55 0.85 3.55 0.85 3.55 0.85 3.55 0.85

Total energy generated in GWh

54.47

55.19

55.91

56.54

Plant Load Factor

51.82%

48.46%

45.59%

43.03%


0.72

0.72

0.72

0.63

Generation (GWh/MW)

4.54

4.25

3.99

3.77

% Utilization

88.6%

89.8%

91.0%

92.0%

PLF (lean season)

44.7%

41.2%

38.3%

35.7%

Detailed Project Report Sagana III HEP Chapter 7 - Geology

Chapter 7 - 1

Chapter 7- Geology


Chapter 7 - 2

7. General

Kenya is located in the Eastern part of Africa. The Rift valley transverse through Kenya from

north to south. The East African Rift System (EARS) is a 50 to 60km wide zone of active

volcanoes and faulting that extends north-south in Eastern Africa for more than 3000 km (1864

miles) from Ethiopia in the north to Zambezi in the south. It is a rare example of an active

continental rift zone, where a continental plate is attempting to split into two plates which are

moving away from one another. This is the main source of seismicity in Kenya.

The Sagana III hydroelectric power project is in the central province of Kenya. The intake of the

project is located on the Sagana River. Historically no major earthquake has occurred in this

region.

Table 7.1 Major Earthquakes in Kenya

Region Magnitude Date Location

Lake Rudolf Region 5.3 22-Jan-12 549 km (341 miles) N of NAIROBI, Kenya

Lake Turkana 4.8 23-Oct-10 180 km (110 miles) N of Lodwar, Kenya

Lake Tanganyika region 6.8 5-Dec-05 960 km (590 miles) SW of NAIROBI, Kenya

To assess to true geological pattern of the project, geological and geophysical investigations

including drilling and drifting, field and laboratory tests on rocks, construction material

investigations and testing, collection of hydrological and meteorological data, hydraulic model

studies for all the appurtenant features of the project will have to be carried out. This will help in

activities such as foundation treatment measures and minimizing construction surprises. The

following summarizes the various tests that should be carried out to get an understanding of the

geological profile of the project:

7.1 Geological Investigation

A wide range of investigation techniques will have to be carried out to collect the required

geological and geotechnical data viz. surface geological mapping, exploratory drilling, drifting,

laboratory testing and in-situ rock mechanics testing for various component of the project. These

investigations will be utilized in fulfilling the following objectives:

To evaluate and optimize the layout of the different project components on geological

considerations.


Chapter 7 - 3

To collect sufficient qualitative and quantitative geological and geotechnical information

for techno economic design of the project components so that basic parameters for major

structures can be optimized.

To collect sufficient data to plan suitable construction methodology and a reasonable cost

estimate, etc.

7.2 Regional Geological Studies:

Available literature on geology of the central province of Kenya will have to be studied to

understand the geological setup of the area.

7.3 Geological Mapping:

Detailed geological mapping of the proposed project area should be carried out on 1:1000 scale.

During the surface geological mapping, different rock types and overburden material should be

classified. Geotechnical parameters of each outcrop were collected for rock mass

characterization. During reservoir geological mapping, traverses should be taken along the

reservoir rim to separate different type of overburden/rock and to identify potential zone of

landslides, if any, to establish overall stability of the structures.

7.4 Exploratory Drilling:

Appropriate number of exploratory drill holes should be drilled in proposed project area to

evaluate depth of overburden and quality of bed rock. Summary of the location of drill holes to

serve as a guideline for these drill holes are given in table below:

Sl. no. Location Number of drills

1 Diversion Structure left Bank 2

2 Diversion Structure Right Bank 3

3 Weir Axis River bed 2

4 Power House center 1

5 Power House Wall 1

6 Downstream Apron 1

7 Coffer Dam, River Bed 1

8 Head Race Tunnel Inlet 1


Chapter 7 - 4

Sl. no. Location Number of drills

9 Head Race Tunnel Outlet 1

10 Water Channel 2

11 TRC Outlet 1

7.5 Permeability Test:

Permeability test for overburden have to be conducted in exploratory drill holes using constant

head method. Water pressure tests in bed rock will also have to be conducted using single/double

packer. The length of each test section should be kept as 1.5 to 3.0m.

7.6 Exploratory Drift:

The intake area should be explored with two exploratory drifts of size 1.8m x 2.1m in the right

and left abutments to ascertain the soundness of abutments, limit of distressing and visualize the

abutment rock parameters like rock mass quality, and assess the rock material and mass

characteristics.

7.7 Laboratory Tests:

The laboratory tests on core samples/ rock samples should be conducted to determine the

following physical and engineering properties of the rock mass in project area:

Density;

Unconfined Compressive Strength (Dry & Saturated);

Water Absorption;

Modulus of Elasticity and Poisson’s ratio;

Tensile Strength (Dry & Saturated);

Ultra Sonic pulse wave velocity;

Point Load Strength Index;

Slake Durability;

Shear Parameter;


Chapter 7 - 5

7.8 Petrographic Studies:

Five number of rock core sample from different project component of the proposed project area

should be tested to determine the minerological content and its percentage.

7.9 In-situ Tests:

Following in-situ tests should been carried out-

Block Shear Test - Between Concrete and rock (C & Φ values).

Between Rock and Rock (C& Φ values).

Plate Load Test - Modulus of Elasticity/deformation

7.10 Construction Material Survey and tests

Construction material survey were carried out to estimate quality and quantity of coarse and fine

aggregate and impervious material for proposed diversion structure, coffer dam, HRT, water

channel and power house complex.

Various laboratory tests have been suggested, such as-

A) Test for coarse aggregates:

Gradation analysis;

Specific Gravity;

Water Absorption;

Aggregate Abrasion value;

Aggregate Crushing value;

Aggregate Impact value;

Soundness (5 Cycles);

Flakiness Index;

B) Test for fine aggregates:

Gradation analysis;

Specific Gravity;


Chapter 7 - 6

Fineness Modulus;

Water Absorption;

Silt and Clay content;

Soundness (5 Cycles);

Organic Impurities;

Petrographic examination (for fine and silt) etc.

Detailed Project Report Sagana III HEP Chapter 8 - Civil Engineering Structures

Chapter 8 - 1

Chapter 8-Civil Engineering Structures


Chapter 8 - 2

8. Structure & Layout

The main objective of the Sagana-III Small Hydro Electric Project is to generate power

economically and expeditiously, utilizing the local available material and labour to the extent

possible. The design for the project components has been planned to have simple and cost

effective execution of civil works. General layout of the scheme is shown in Drawing No.

‘Sagana-III-001’. The project envisages utilizing the water of Sagana River through a

diversion structure at an elevation of 1274m. The Power house is located at an elevation of

1210 m. The main components include trench weir, de-silting arrangement, a ~4.8 km long

water conductor system, Forebay & buried Penstock, with the main Penstock being ~175m,

branch penstock of ~15 m length each. The scheme proposes to utilize a gross head of

58.46m to generate 10 MW of power, with a rated discharge of 21.26 cumecs. The power will

be evacuated through a ~7 km long 132KV line to Sagana Town for Sagana - Kutus line.

8.1 General:

The major civil engineering structures of the project are as under:-

1. Diversion Structure (Intake)

2. Intake channel

3. Desilting tank

4. Tunnel

5. Power channel

6. Penstock

7. Power House

8. Tail pool

9. Tail race channel

10. Switchyard

Detailed description of each of these structures is as follows:-

8.1.1 Diversion Structure and Intake

Diversion structure is required across the stream for diverting its discharge for power

generation which should be least expensive and as simple as possible. The diversion structure

in hilly streams can be of two types:

Solid boulder type weirs

Trench type weirs

The following aspects need to be considered while selecting the type of weir.


Chapter 8 - 3

Diversion structures face a recurring problem due to choking of over ground intake

structures and are vulnerable to damage from heavy boulders and bed loads.

More often it is not possible to provide storage at the diversion site due to fast filling

up tendency of the storage space by stone and boulders.

Where the riverbed is non-rocky, maintenance and repairs of damages due to scour

may create problems in case of solid boulder type weirs.

This is a run of the river type scheme and storage cannot be provided because of its inherent fast

filling tendency. A trench type weir is thus considered suitable for this site. Trench type weirs

constructed in similar hilly terrains have proved to be successful over the years in various other

projects worldwide. The trench type weir shall be capable of diverting all the lean season flows

and the structure shall also be capable of passing safely the 100-year return period flood discharge.

A trench type weir is a simple trapezoidal/rectangular trough made up of reinforced cement

concrete (RCC) provided with sloping steel trash rack over the full width of weir on the top. The

criteria for determining the length of the trench weir is that it should be capable to pass the design

flood discharge. Length of the trench weir has been kept as 25 meters to pass the 46-year return

period flood discharge of 301.59 cumecs with HFL at EL. 1276.7 meters. The bed of the trench

weir has been provided with an adequate slope of 1 in 16 in the flow direction so that sufficient

velocity is generated to carry away small stones and heavy silt upto 25 mm size that may find

entry into the weir through the trash rack openings. The FSL in the trench weir has been fixed at

EL. 1274.00 meter. The trash rack proposed is proposed to be of the size 4.7 x 2.5 meter. The trash

rack has been given a slope of 1 in 10 in the flow direction so that stones and pebbles above 25

mm size do not enter into the weir but roll down into the stream with the flow. The trash rack area

of opening is adequate to draw the entire lean season flow and desired diversion discharge during

the flood season even if 50% of the effective area of the trash rack is clogged. The trash rack will

have to be cleaned periodically during and after rainy season to clear any deposited material.

The upstream and downstream of trench weir is protected RCC wall of 1.3 m x 25 m. with boulder

filled wire crates of size 0.5m x 1m x 1m is also put on bed of river and downstream of trench weir

has been protected with cast in SITU concrete blocks of 500 m with slope 1 in 20 upstream and

1:20 downstream along the flow.

The intake located at the end of the trench weir is a gated well structure to be constructed in RCC.

The intake gate control shall permit the release of desired discharge through (4.6m x ~4.5m x

.25m) approach tunnel and (4.6m x ~4.1m x .25m) RCC channel to the desilting tank. The top of

intake structure has been fixed at elevation EL. 1277.90 m. The intake structure has been provided

with one vertical lift gate for regulating the discharge into the water conductor system. One


Chapter 8 - 4

vertical lift slide type stoplog gate of size 4.9m x 4.2m is provided for emergency and maintenance

purpose at the upstream of the service gate. Shingle flushing pipe of diameter 1500mm has been

provided to exclude debris, wooden logs and such bigger particles at the bottom of the intake

structure having elevation of EL. 1269.50 m. One number shingle flushing gate of size 1.4m x 1.5

m has been provided at the entry of the pipe.

Plan and section of trench weir and intake well are shown in drawing no Sagana-III-002 &

Sagana-III-003 respectively.

8.1.2 Approach Tunnel

A 1260 m long tunnel of height 4.5m, width 4.9m, thickness of RCC box 0.15m has been

proposed to carry the discharge from the trench weir to the desilting basin. The bed slope

provided in the channel is 1 in 1130 which will generate a velocity of 2.0 m/s at a discharge

of 29.34 cumecs (adding 20% excess flow to the plant flow of 24.45 cumecs for desilting

basin).

8.1.3 Approach Channel

A 90 m long RCC box intake channel of base width 4.6m and the full supply depth being

3.2m, thickness of RCC box 0.25m has been proposed to carry the discharge from approach

tunnel to the desilting basin. The bed slope provided in the channel is 1 in 1130 which will

generate a velocity of 2.0 m/s at a discharge of 29.34 cumecs (adding 20% excess flow to the

plant flow of 24.45 cumecs for desilting basin). After construction the intake channel would

be backfilled to the ground level.

8.1.4 Desilting Tank

The hilly streams generally carry appreciable quantities of coarse silt and sand during the

rainy season. It is, therefore, necessary to provide desilting tank to exclude coarse particles so

as to minimize the abrasion to the turbine runner or buckets especially in high head schemes

where abrasion effect becomes more pronounced.

A desilting tank proposed is of conventional Surface Central Silt Gutter type having 2

chambers of ~82 m x 10 m each to exclude coarser particles of size exceeding 0.25 mm from

water flow. The horizontal velocity of flow and the settling velocity of flow are 0.22 m/sec

and 0.0275 m/sec respectively. Slope of 1 in 4 has been provided to flush out the accumulated

silts. The accumulated silt is proposed through 1000 mm diameter MS pipe. The flushing

operation in the pipe will be regulated by means of 1000mm diameter gate valve provided in

the pipe outside the desilting basin. Two vertical lift type gates upstream and downstream

have been provided for maintenance purpose in each chamber.


Chapter 8 - 5

8.1.5 Water Conductor System

The Water conductor system consists of the following sections:

8.1.5.1 Tunnel Ch. 01 to Ch. 1260

A 1260 m long tunnel of bed width of 4.8 m and vertical height of ~4.5 m for fair to

good rock and base width of 4.8 m for poor rocks and base width of 5.4 m for very

poor rocks have been proposed to convey the discharge. The tunnel has been provided

with bed slope of 1 in 1130. The velocity in the tunnel has been limited to 2.0 m/s.

8.1.5.2 RCC Rectangular Channel Ch.1260 to Ch.1350

A 90 m long RCC rectangular channel of base width of 4.6 m and vertical height of 4.1

m has been proposed to convey the discharge from approach tunnel to the desilting tank.

The channel has been provided with bed slope of 1 in 1130. The velocity in the channel

has been limited to 2.0 m/s

8.1.5.3 Power Channel 1 Ch.1432 to Ch. 2177


m has been proposed to convey the discharge from desilting tank. The channel has been

provided with bed slope of 1 in 1130. The velocity in the channel has been limited to 2.0

m/s.

8.1.5.4 Tunnel 2 Ch.2177 to Ch. 4517

A 2340 m long tunnel of bed width of 4.8 m and vertical height of ~4.5 m for fair to

good rock and base width of 4.8 m for poor rocks and base width of 5.4 m for very

poor rocks have been proposed to convey the discharge. The tunnel has been provided

with bed slope of 1 in 1010. The velocity in the tunnel has been limited to 2.0 m/s.

8.1.5.5 Power Channel 2 Ch. 4517 to 4887


m has been proposed to convey the discharge from tunnel 2. The channel has been

provided with bed slope of 1 in 1010. The velocity in the channel has been limited to 2.0

m/s.

8.1.6 Forebay

To cater to the sudden surges in demand or rejection of the turbine, a depressed bed type forebay ~

(40 m x 18 m x 15m) having storage of ~4400 cu. m. (equivalent to 3 Minutes of operation at peak

load) will be designed. Land in the form of a flat field has been identified for the location of the

forebay. A provision for trash rack and penstock gates has been provided before the penstock

intake.


Chapter 8 - 6

Plan and section of forebay and other details are shown in drawing no. ‘Sagana-III- 008’ and

‘Sagana-III- 009’.

8.1.7 Penstock

Penstock alignment has been finalized after a careful study of the alternative proposals and

adopting the one, which requires minimum excavation as well as minimum number of bends.

Buried penstock has been provided suitable to the existing topography. One no. main penstock

pipe of steel 2700 mm diameter has been provided from the forebay. The length of main penstock

is ~168 meter and that of the two branches is ~15.5m. The penstock is proposed to be fabricated

from medium tensile steel plates conforming to IS: 2002-1992 grade 2 steel and properly welded.

The welded penstock shall have less hydraulic losses besides ease of transportation and erection.

The plate thicknesses of penstock will vary from 10 mm to 14 mm in various reaches. Flow

velocity of 4.3 m/sec through the penstock is proposed to reduce the losses.

The buried penstock has been anchored at both the horizontal and vertical bends to resist the

unbalanced hydrostatic forces due to change in the direction of flow and to prevent movement of

penstock on account of vibration or water hammer effect. All anchor blocks will be of RCC and

their stability has been checked as per IS Standards. The buried penstock is supported between the

anchor blocks by the saddle supports made of RCC. The main penstock shall be bifurcated into 2

unit penstocks of diameter 1.9 m and length ~15.5 m each, which will feed 2 horizontal axis

Francis turbine situated in the power house. Layout and details of penstock, bends, bellmouth, and

reducers are shown in drawing no. Sagana-III-06.

8.1.8 Power House and Tail Race Channel

A surface power house has been proposed on the right bank of Sagana River at an elevation of

1209.91 m. The proposed power house building is ~28.2 meter long and ~17 meter wide for

housing the generating unit, control panels, store cum workshop, battery room etc.. The height of

powerhouse from the floor level has been kept about ~18 meter. The sidewalls shall be made of

stone masonry and columns, beams, foundations of generating units shall be laid in RCC M-25

grade. The power house shall comprise of following components :

1) Service Bay

2) Machine Hall

3) Control Room

1) Service Bay: it has been proposed at elevation RL. 1215 m.


Chapter 8 - 7

2) Machine Hall: The machine hall dimensions are 12.05m x 23 m. It will house 2 units of

horizontal axis Francis turbine with c/c distance of 10 m. the machine hall elevation in RL.1209.91

m. And center line of Machine shall be kept at RL.1208.18 m.

3) Control Room It has an elevation of RL.1215 m and consists of battery room, office block,

toilet block, store room. Its dimensions are 4500mm x 6425mm.

A crane beam has been provided at elevation EL. 1221.5 m on both side of power house to support

operational load of EOT crane. Two Draft Tube gates have been provided dimensions of ~3 m x

2.2 m operated by rope drum hoist

8.1.9 Tail Race Channel

A RCC rectangular channel of base width 4.65 m and length 10 m has been proposed to carry

water discharge after power generation back to Sagana River with a slope of 1 in 2150. A tail pool

of 13 m x 36m with slope of 1 in 4 is considered having max tail water level at EL1213.50m.

8.1.10 Switchyard

Surface switchgear cum transformer yard has been proposed adjacent to the power house. It will

consist of a power transformer, circuit breakers, current transformers, potential transformers,

isolators etc. The equipment will be designed for stepping up from 11 kV to 132 kV for

evacuation.

A ~7 km transmission line will be constructed to evacuate the power to the newly being

constructed Sagana town substation from where it will meet Sagana-Kutus 132 KV line


Chapter 8 - 8

Annexure 8.1- Hydraulic Design of Components


Chapter 8 - 9

Hydraulic Design of Project Components for Sagana-III HEP:

Trench Weir

Sl.

No. Particulars

Units Calculations

A Design Data

a Design Discharge of plant= (Qmax) cumecs = 24.45

b Width of stream = L m = 25.00

c River bed level = (RBL) m = 1,274.00

B Design calculations

1 Width of trench weir (w)

a Width of trench weir at top = (B)

=

( )

Where

B = Width of trashrack (width of trench weir

at top) in m

Q = Diverted discharge in cumecs

E1 = Ratio of Area of opening to total area

of trash rack surface over trench

50%

E2 = Ratio of opening in the trashrack likely

to be clogged

50%

Cd = Coefficient of discharge through

opening

0.46

L = Width of stream m

25.00

g = Acceleration due to gravity m/sec2

9.81

E = Specific energy at any section of stream

in the trench weir

= (

)

C = Coefficient of discharge for broad

crested weir

1.53

Diverted discharge (Q)

=

Design Discharge of plant + 20%

extra for flushing at D-tank + 25%

extra for flushing at intake

cumecs = 24.45 + (24.45 x 0.45 )

cumecs = 35.45

Specific energy at any section of stream in

the trench weir (E) = (

)

= (35.45 /1.53 x25)^(2/3)

= 0.95

Therefore,

Width of trench weir at top m B=

√

= 35.45

0.5 x0.5 x0.46 x25 (2 x 9.81 x

0.95)^(1/2)

= 35.45

12.41

= 2.86

Provide Width

2.90

b Width by considering velocity

Allowable velocity through trashrack

opening m/sec v 0.75

Width m =

= 35.45 / ( 25 x 0.75)

= 1.89

Width required for 50% clogging criteria m = 2 x 1.89

= 3.78

Provide width, being higher m = 3.80

2 Depth of trench weir (d)


Chapter 8 - 10

Sl.

No. Particulars

Units Calculations

Area (A) = Width x depth

= 3.8 x d

Velocity head at the end of trench (H ) = (η/η+1) x (A/2w)

Where,

η= constant depending on bottom profile of

channel = 0.50

= (0.5 / 0.5 + 1) x (3.8 x d / 2 x3.8)

= 0.17000

= 0.17 d

The corresponding discharge =(Q) = ( )

35.45 = 3.8 x d x (2x 9.81 x0.17 d)^0.5

d3/2 = 5.11

d = 2.97

Provide depth at end ( From Intake criteria) m = 4.50

Therefore, Provide depth at start

m =

4.5 - ( width of stream / slope in

trench)

= 4.5 - ( 25 / 25)

= 3.50

Greater than required depth

Hence OK

Check for adequacy of waterway

Average depth = m = (3.5 + 4.5 )/2

= 4.000

Area (A) Sq. m = 3.8 x 4

= 15.20

Wetted perimeter (P) m = 3.8 +( 2 x 4 )

= 11.80

Slope provided (S) = ( 4.5 - 2.97) /25

= 0.06120

i.e. 1 in

16.00

Using Manning’s formula with value of n =

0.018

Discharge Q cumecs = (

)

=

(1/0.018) x 15.2 x (15.2 /

11.8)^(2/3) x0.0612^(1/2)

cumecs = 247.32

which is greater than design Q Hence OK

Check for adequacy of capacity with 50%

area clogged

Average depth (d) m = 4 / 2

= 2.00

Area (A) Sq. m = 3.8 x 2

= 7.60

Wetted perimeter (P) m = 3.8 +( 2 x 2 )

= 7.80

Slope provided (S) = ( 4.5 - 2.97) /25

= 0.060

Using Manning’s formula with value of n =

0.018

Discharge Q cumecs = (

)

=

(1/0.018) x 7.6 x (7.6 / 7.8)^(2/3)

x0.06^(1/2)

cumecs = 101.65

which is greater than designed Q Hence OK

3 Top RL of trench

Provide Top RL of trench m = River bed level

= 1274.00


Chapter 8 - 11

Sl.

No. Particulars

Units Calculations

Therefore, FSL in Trench weir = Top RL of trench

m = 1274.00

4 Trash rack dimensions

slope of trash rack 1 in = 10.00

Therefore, Width of trash rack

=

((3.8/10)^2 +(3.8^2))^0.5 + 2 x

0.175

m = 3.97

ABATRACT

1 Length of trench m = 25.00

2 Width of trench m = 3.80

3 Trench depth at start m = 3.50

4 Trench depth at intake m = 4.50

5 Slope provided 1 in m = 16.00

6 FSL in Trench weir m = 1,274.00

7 Bottom RL at start of trench m = 1,270.50

8 Bottom RL at end of trench m = 1,269.50

9 Length of trash rack m = 25.00

10 Width of trash rack m = 3.97

Intake Tower

Sl.

No. Particulars Units Calculations

A Design Data

a Design discharge of plant = Qmax Cumecs = 24.45

b Pond level = FSL M = 1,274.00

c Height of opening @ entry of WCS =(h) M = 3.20

e Flushing velocity = vf m/sec = 3.50

f Provision for bellmouth = hb M = 0.30

g Silt trap depth proposed m = 0.50

h HFL at trench weir site m = 1,276.70

B Design Computations

1 Computation of bottom level of Intake

Bottom of Intake = FSL in cut & cover channel -FSD

= 1274 - 3.2

= 1,270.80

Sill level of bellmouth = Bottom of Intake -hb

= 1270.8 - 0.3

= 1,270.50

Bottom of shingle flushing pipe =

Sill level of bellmouth - Dia. of

shingle flushing pipe

= 1270.5 - 1.5

= 1,269.00

Bottom of stop log gate (Allowing water

cushion) =

Bottom of shingle flushing pipe +

Water cushion

= 1269 + 0.5

= 1,269.50

2 Computation of dia. of flushing pipe

Flushing discharge = 25 % 0f design discharge

Qf = (24.45x 0.25)

= 6.11

Therefore, Dia. of flushing pipe = d m = (Qf x 4 / 3.14 x 3.5 )^0.5

= 1.49

Say = 1.50

3 Computation of depth of trench at exit

Depth of trench at exit = D = FSLp - Sill level of stop log gate

m = (1274 -1269.5)


Chapter 8 - 12

Sl.


D m = 4.50

4 Height of intake chamber = HFL + free board

= 1276.7 + 1.2

m = 1,277.90

ABSTRACT

1 Sill level of intake opening (service gate) m = 1,270.80

2 Dia. Of shingle flushing pipe m = 1.50

3 Sill RL of Shingle flushing pipe m = 1,269.00

4 Sill RL of Stop log gate = 1,269.50

5 Depth of trench at exit m = 4.50

6 Top RL of intake chamber m = 1,277.90

Tunnel 1

Sl.


From Intake to Desilting Tank

1 Design data

a Design discharge of plant =Qmax cumecs = 24.45

b FSL at the start of tunnel m = 1,274.00

c Velocity limited = V m/sec = 2.00

d Rugosity coefficient = n = 0.018

e Length of tunnel =L m = 1,260.00

2 Design calculations

Computation of bed width & FSD of tunnel

Design discharge in tunnel = (Q) cumecs = 29.34

Area required = A Sq. m = Q/V

= 29.34 / 2

Sq. m = 14.67

Provide water depth in tunnel m = 3.20

Therefore, width of tunnel m = 14.67 / 3.2

m = 4.60

Perimeter = (P) = b + 2 d

= 4.6 + (2 x3.2 )

m =

11.00

Hydraulic Radius =(R ) = A / P

= 14.67 /11

m =

1.33

Computation of slope of tunnel bed

Using Manning's Formula = v = (

)

S1/2 = (

)

S = (

)

= (2 x 0.018)/1.33^(2/3))^2

S = 0.0009

Provide slope of 1 in = 1130

Computation of FSL at end of tunnel

Reduced FSL at the beginning m = FSL at start of cut & cover tunnel

m = 1,274.00

Reduced FSL at end m = FSL1 - (Length/Slope)

= 1274- (1260 / 1130)

m = 1,272.88

Provision of free board

Free board (for 7 to 30 cumecs ) m = 0.90


Chapter 8 - 13

Sl.


ABSTRACT

1 Base width m = 4.60

2 FSD in tunnel m = 3.20

3 Free board of tunnel m = 0.90

4 Bed slope of tunnel - 1 in m = 1,130

5 Length of tunnel m = 1,260

6 FSL at beginning of tunnel m = 1,274.00

7 FSL at end of tunnel m = 1,272.88

Approach Channel

Sl.


From Intake to Desilting Tank

1 Design data


b FSL at the end of power channel-2 m = 1,272.88



e Length of power channel =L m = 90.00


Computation of bed width & FSD of channel

Design discharge in channel = (Q) cumecs = 29.34


= 29.34 / 2

Sq. m = 14.67

Provide water depth in channel m = 3.20

Therefore, width of channel m = 14.67 / 3.2

m = 4.60


= 4.6 + (2 x3.2 )

m = 11.00


= 14.67 /11

m = 1.33

Computation of slope of channel bed


)

S1/2 = (

)

S = (

)

= (2 x 0.018)/1.33^(2/3))^2

S = 0.0009


Computation of FSL at end of channel

Reduced FSL at the beginning m = FSL at start of cut & cover channel

m = 1,272.88


= 1272.88- (90 / 1130)

m = 1,272.80



ABSTRACT


Chapter 8 - 14

Sl.



2 FSD in channel m = 3.20

3 Free board of channel m = 0.90

4 Bed slope of channel - 1 in m = 1,130

5 Length of channel m = 90

6 FSL at beginning of channel m = 1,272.88

7 FSL at end of channel m = 1,272.80

Desilting Tank

Sl.


1 Design data

Propose two tanks

a Design discharge of plant =(Qmax) = 24.45

b Design discharge per D-tank =Q cumecs = 14.67

c Particle size to be removed => Ps mm = 0.25

d Flow through velocity =uf m/sec = 0.22

e Settling velocity =us cm/sec = 2.75

f FSL in desilting tank m 1,272.80

2 Design calculation

A Design of tank

Width proposed for tank =W m = 10.00

Depth required = D m = =Q/W*uf

= 14.67 / (10 x 0.22)

m = 6.67

Moderated settling velocity =um cm/sec = us - (0.132/(D)1/2 *us

= 2.75 - ( 0.132 /( 6.67)^0.5) x 2.75

cm/sec = 2.61

m/sec = 0.026

Settling length of tank

(Flow through velocity x

Depth)/Settling velocity

m Ls = (u1 / um) *d

= ( 0.22 / 0.026) x 6.67

m Ls 56.44

Say m 56.00

By providing minimum gutter slope 1 in

25

Depth at the end of silt gutter (56/25)+ 6.67

m 8.91

Bottom RL of gutter at start of tank = FSL -depth at start

= 1272.8 - 6.67

m 1266.13

Bottom RL of gutter at end of tank = FSL -depth at end

= 1272.8 - 8.91

m 1263.89

Top RL of tank = FSL + Free board

= 1272.8 + 0.90

m 1273.70

B For Silt Flushing Pipe

1 Design data

Silt flushing discharge ( 20% of design

discharge) = Qf cumecs = 18.33 x 0.20/2

cumecs =

1.83

Velocity of water in flushing pipe (Assumed) m/sec = 2.50

2 Design calculation


Chapter 8 - 15

Sl.


Diameter of silt flushing pipe = D silt = Qfp x 4 / ( 3.14 x v )

= 1.83 x 4/ (3.14 x 2.5)

m 0.966

Provide dia. of pipe mm 1,000

ABSTRACT

1 Settling tank - width m = 10.00

2 Settling tank length m = 56.00

3 FSL in De-silting tank m = 1,272.80

4 Bottom RL at start of tank m = 1,266.13

5 Bottom RL of gutter at end of tank m = 1,263.89

6 Top RL of tank m = 1,273.70

7 Dia. of slit flushing pipe mm = 1,000

Power Channel-1

Sl.


From desilting

1 Design data










= 24.45 / 2

Sq. m = 12.23



m = 4.20


= 4.2 + (2 x2.9 )

m = 10.00


= 12.23 /10

m = 1.22



)

S1/2 = (

)

S = (

)

= (2 x 0.018)/1.22^(2/3))^2

S = 0.0010




m = 1,272.80


= 1272.8- (745 / 1010)

m = 1,272.06




Chapter 8 - 16

Sl.


ABSTRACT








Tunnel - 2

Sl.


1 Design data


b FSL at the start of tunnel m = 1,272.06



e Length of tunnel =L m = 2,340.00





= 24.45 / 2

Sq. m = 12.23



m = 4.20


= 4.2 + (2 x2.9 )

m = 10.00


= 12.23 /10

m = 1.22



)

S1/2 = (

)

S = (

)

= (2 x 0.018)/1.22^(2/3))^2

S = 0.0010




m = 1,272.06


= 1272.06- (2340 / 1010)

m = 1,269.74



ABSTRACT






Chapter 8 - 17

Sl.


5 Length of tunnel m = 2,340



Power Channel - 2

Sl.


1 Design data




d Rugosity coefficient = n

= 0.018






= 24.45 / 2

Sq. m = 12.23



m = 4.20

Perimeter = (P)

= b + 2 d

= 4.2 + (2 x2.9 )

m = 10.00

Hydraulic Radius =(R )

= A / P

= 12.23 /10

m = 1.22


Using Manning's Formula = v

= (

)

S1/2

= (

)

S

= (

)

= (2 x 0.018)/1.22^(2/3))^2

S

= 0.0010

Provide slope of 1 in

= 1010



m = 1,269.74


= 1269.74- (370 / 1010)

m = 1,269.37



ABSTRACT









Chapter 8 - 18

Forebay

Sl.

No. Particulars

Units

Calculations

A Design data

a Design discharge =Qmax cumecs Qr 24.45

b Max level in forebay = FSL m FSL1 1,269.37

c TWL max m

1,213.50

d TWL min m

1,210.91

e Storage capacity (2-3 minutes ) Minutes T 3


1

Drawdown level in forebay & MDDL

Calculation

H max = MWL - TWL min = 1269.37 - 1210.91

m = 58.46

considering, Hmax = H rated m = 58.46

Minimum head considering

Head variations below rated head

10% m = 52.61

15% m = 49.69

20% m = 46.77

25% m = 43.84

30% m = 40.92

35% m = 38.00

Considering 10% below rated head

Min. Head m = 49.69

Therefore, MDDL of forebay = TWL max + H min

= 1213.5+ 49.69

m = 1,263.19

Drawdown depth =D = FSL - MDDL

= 1269.37 - 1263.19

m = 6.18

1

Storage capacity & Dimensions of forebay

tank

Volume of storage required = Vm = Qr * T *60

cum = 4,401

Area requirement for the forebay = A Sq. m = Vm / D

= 4401 / 6.18

Sq. m = 712.14

Provide length of forebay m L 40.00

Therefore,

Breadth required m B= A / L

= 712.14/40

17.80

Say

m

18.00

3 Computation of C/L of Intake opening

Area of Penstock = Pi /4 x 2.7^2

Sq. m =

5.72

Area of bellmouth Sq. m = Area of penstock / 0.6 cos (0)

(As per IS 9761) = 5.72 / 0.6 cos (0)

Sq. m =

9.53

Therefore,

Diameter of bellmouth =h = (9.53 x 4 / pi )^0.5

= 3.48

m Say 3.48

Water cushion above bellmouth = 0.6 h

(Ref-P.S.Nigam -Intake structures P-383) m = 2.09


Chapter 8 - 19

Sl.

No. Particulars

Units

Calculations

C/L of Intake opening

=

M.D.D.L.- (water cushion + 1/2

bellmouth height)

= 1263.19 - (2.09 + 3.48/2)

m = 1,259.36

Sill level of bellmouth

=

M.D.D.L - (water cushion +

Bellmouth opening Height)

= 1263.19 - (2.09 + 3.48)

m = 1,257.62

Bottom RL of Forebay = Sill level - 1

= 1257.62 - 1

m = 1,256.62

Top RL of Forebay = FSL I fore bay + Free Board

= 1269.37 + 0.90

m = 1,270.27

ABSTRACT

1 Length of forebay m = 40.00

2 Breadth of forebay m = 18.00

6 F.S.L. at Forebay m = 1,269.37

7 MDDL m = 1,263.19

8 C/L of penstock intake opening m = 1,259.36

9 Sill level of penstock opening m = 1,257.62

10 Bottom RL of forebay m = 1,256.62

Escape channel

Sl.


1 Design data

a Design discharge =Qmax cumecs Qr 24.45

b Max level in forebay = FSL m FSL1 1,269.37

c

Min. level in forebay (FSL-FSD in channel

behind) m 1,263.19

d Velocity limited = V m/sec = 2.00

e Rugosity coefficient = n = 0.018

f Length of channel =L m = 125.00


Computation of bed width & FSD of

channel



= 24.45 / 2

Sq. m = 12.23



m = 4.20


= 4.2 + (2 x2.9 )

m = 10.00


= 12.23 /10

m = 1.22



)

S1/2 = (

)

S = (

)


Chapter 8 - 20

Sl.


= (2 x 0.018)/1.22^(2/3))^2

S = 0.0010




Computation of Length of surplus escape

Crest of surplus escape = FSL in forebay

m = 1,269.37

Let head over the crest of spillway = m = 0.60

therefore, top of forebay = 1269.37 + 0.9

m = 1,270.27

Discharge through surplus escape = Q =

Where,

Q = Discharge through rect. channel cumecs = 24.45

C = Constant for rectangular opening = (2/3) x 0.62 x(2 x 9.81)^0.5

(ref- R.S.khurmi -textbook of hyd. P-331) = 1.83

1.83

H = Head over crest m = 0.60

L= length of escape channel

therefore,

Length of surplus escape = L =

= 24.45 / (1.83 x 0.6^(3/2))

m = 28.75

Provide length m = 29.00

ABSTRACT






6 Length of spillway m = 29.00

7 Top level of Forebay m = 1,270.27

8 Crest level of Spillway escape m = 1,269.37

Penstock

Sl.


A Design data

a Design discharge of plant =Qmax cumecs =

24.45

b Limiting velocity in penstock = vp m/sec = 4.30

c No. of machines Nos. = 2

d FSL at forebay m = 1269.37

e Av. Tail Water Level m = 1212.21

f Length of penstock =Lp m =

166.00

g Time constant =Ct sec =

10.00


1 Diameter of main penstock (Dm)

(i) Discharge through penstock Qb =

24.45

(ii) Area of penstock required =Am = Qmax / vp

= (24.45 /4.3)

Sq. m = 5.69

Therefore,


Chapter 8 - 21

Sl.


(iii) Diameter of penstock = Dm m = (Area x 4 / 3.14)^0.5

= (5.69 x 4 )/ 3.14)^0.5

m = 2.69

Therefore,

Provide diameter of penstock m = 2.70

2 Diameter of Branch penstock (Db)

(i) Discharge through each penstock=Qb = 12.23

(ii) Area of penstock required =Ab = Qb / vp

Sq. m = (12.225 /4.3)

m = 2.84

Therefore,

(iii) Diameter of branch penstock =Db = (Area x 4 / 3.14)^0.5

= (2.84 x 4 )/ 3.14)^0.5

m = 1.90

Therefore,

Provide diameter of penstock m 1.90

3

Calculations for Pressure Rise due to

Water Hammer

Method I :

TNEB Power Engineering handbook page

No.1.16

Penstock Diameter m = 2.70

Area of penstock provided Sq. m = (3.14 / 4) x 2.7^2

5.73

Therefore, Velocity = Q / A provided

= ( 24.45 )/ 5.73

= 4.27

Pressure rise due to closing of guide

Vanes. = H =

Where,

Pressure rise = H

Length of penstock =L m 180

Gravitational Acceleration =g m/sec2 9.81

Gide vane closing time = T sec 4.5

Therefore, H = = (2 x 180 x 4.27)/( 9.81 x 4.5)

m = 34.82

Method II :

(Ref : Environmental Engineering Vol. II,

by Santosh Kumar Garg page No. 268)

P h max = = 14.6 V / ( 1+k d/t)0.5

Where,

k = Ew/Epipe - ( for steel pipe ) = 0.01

d = Diameter of pipe m = 2.70

t = Thickness of pipe( from 3 below) m = 0.010

V= Velocity of water in pipe m/sec = 4.27

Ph max =

14.6 x 4.27 / ( 1+ 0.01 x 2.7

/0.01)^0.5

kg/cm2 = 32.41

When actual closure time T, is less than

Critical closure time Tc

P = P h max * (Tc / T)

Where,

Tc = 2 S / Up

Where,

S = Distance of valve from reservoir m = 180

UP= (Ew/e)0.5 x 1/( 1+k d/t)0.5

Where,

(Ew/e)0.5 m/sec = 1433


Chapter 8 - 22

Sl.


UP = = 1433 x 1 /( 1 +0.01 x 2.7 x 0.01)^0.5

= 744.98

Therefore,

Critical closure time Tc = = 2 S / Up

= 2 x 180 / 744.98

= 0.48

Therefore,

P = = P h max * (Tc / T)

= 32.41 x (0.48 / 4.5)

kg/cm2 = 3.46

Therefore,

H = P x 10 = 3.46 x 10

m = 34.60

Therefore,

Maximum pressure rise m = 19.84

4 Steel liner thickness

A Method-I

CWC Penstock Mannual Page No.23 / IS

11639:1995(Part 2) /Page 03

Thickness = t =

Static head = H1 = FRL - Min. TWL

1269.37 - 1212.205

m = 57.17

Rise in Head due to Water hammer m = 19.84

Total Head = H = H1 + H2

m = 77.01

Internal Pressure inclu. Dynamic m = 7.700

pressure =P

Internal radius of penstock = R cm 135

Hoop Tensile stress in steel =S kg/cm2 1192

Thickness of steel liner shell = t = ( 7.7 x 135) /1192

cm = 0.872

mm = 8.72

Add corrosion allowance(Ref:IS mm = 0.00

11639:1995 Part2/p 05)

Concrete lined = t mm = 8.72

B Method-II

Thickness of pensock considering joint

efficiency

t =

Static head = H1 = FRL - Min. TWL

= 1269.37 - 1212.205

m = 57.17

Rise in head due to water hammer =H2 m = 19.84

Total Head = H m = H1 + H2

57.17 + 19.843

m 77.01

Internal Pressure incl. dynamic =P kg/cm2 = 7.700

pressure

Internal diameter of penstock =D cm = 270.00

Safe working stress in steel =f kg/cm2 = 1192

Joint efficiency =n % = 0.90

Thickness of steel liner shell =t t = ( 7.7 x 270) / (2 x1192 x 0.9)

cm 0.969

mm 9.69


Chapter 8 - 23

Sl.


Add corrosion allowance(Ref: IS

11639:1995 Part2/p 05) Concrete lined mm mm 9.69

C Method-II

Minimum Handling thickness ( Ref :

I.S.4880 (part VII) : 1975 / P. 6

(I) Thickness of liner = t cm = ( Dia. of penstock + 50) /400

(2.7 x 100 + 50) /400

t cm = 0.800

t mm = 8.00

Therefore,

The Maximum of above criteria,

The thickness of Penstock works mm 9.69

Therefore required Thickness mm 10.00

Thickness provided mm 10.00

ABSTRACT

1 Diameter of main penstock mm = 2,700

2 Diameter of branch penstock mm = 1,900

3 Provide steel liner thickness-start mm = 8

4 Provide steel liner thickness-end mm = 10

Tail Race Channel

Sl.


From power house to river Sagana

1 Design data


b CBL of channel at beginning m = 1,210.00


d Rugosity coefficient =n = 0.018

e Length of Rect. channel =L m = 10.00



Area required =A = Q/V

= 24.45 / 1.5

Sq. m = 16.30

Provide water depth in channel =d m = 3.50

Area =A = b x d

16.30 = b x 3.5

16.30 = b x 3.5

Therefore, width ( b ) Sq. m = 4.65

Perimeter =P = b + 2d

= 4.65 + 2 x3.5

= 1.00

m = 11.65

Hydraulic Radius = R = A / P

= 16.3 / 11.65

m = 1.4



)

S1/2 = (

)


Chapter 8 - 24

Sl.


S = (

)

Channel bed slope =S = (

)

= (1.5 x 0.018)/1.4^(2/3))^2

= 0.0005

Provide slope of 1 in m = 2150

Computation of TWL Maximum

CBL of channel at start m = 1,210.00

Add FSD for designed discharge m = 3.50

Therefore,

TWL Max = 1210 + 3.5

m = 1,213.50

Computation of TWL (min)

b m = 4.65

A = Q/V

= 6.378 / 1.5

Sq. m = 4.252

A = (b x d)

4.252 = (4.65 x d )

d m = 4.252 / 4.65

d m = 0.91

TWL min = CBL + d

= 1210 + 0.91

m = 1,210.91

ABSTRACT

1 Base width of channel m = 4.65




5 TWL Max m = 1,213.50

6 TWL min m = 1,210.91

Net Head

Sl.


A Design Data

a FSL at forebay m = 1,269.37

b MDDL in forebay m = 1,263.19

c Tail Water Level - Min m = 1,210.91

d Tail Water Level - Max m = 1,213.50

e Max. head variation = 100%

f Min. Head variation = 90%

g Design discharge = Qmax cumecs = 24.45

h Diameter of penstock =Dm m = 2.70

i Length of penstock = Lmp m = 180.00

j No. of bends Nos. = 5

k No of reduces Nos. = 2

l No. of valves Nos. = 2

m No of Y-piece Nos. = 1

n Gravity constant =g m/sec2 = 9.81

o Co-efficient for frictional loss =f = 0.012

p coefficient for bend loss =P = 0.060

q Entrance velocity =Ve m/sec = 0.750

r Frictional velocity =Vf m/sec = 4.270


Chapter 8 - 25

Sl.


s Velocity in bends =Vb m/sec = 4.270

t Velocity in reducers =Vr m/sec = 4.270

u Velocity in Valves Vv m/sec = 4.270

v Velocity in y piece =Vy m/sec = 4.270

B Design Calculations

(Reference- Manual on planning & design of

small HEP, page-72

(i) Entrance loss = hfe =

= 0.1 x 0.75^2) / (2 x 9.81)

m = 0.003

(ii) Friction loss = hffr =

=

( 0.012 x 180 x 4.27^2) / (2 x 9.81 x

2.7)

m = 0.74

(iii) No of bends = N1 =

5

Bend losses = hfb =

= ( 5 x 0.06 x 4.27^2) / (2 x 9.81)

m = 0.279

(iv) No of reduces = N2 = 2

Loss in reducer pipe =hfr m =

= ( 2 x 0.25 x 4.27^2) / (2 x 9.81)

m = 0.465

(v) No. of valves =N3 = 2

Loss in valve = hfv =

= ( 2 x 0.25 x 4.27^2) / (2 x 9.81)

m = 0.465

(vi) No of Y-piece =N4 = 1

Loss in Y-Piece = hfy = (

)

= ( 1 x 0.8 x 4.27^2) / (2 x 9.81)

m = 0.743

Total Losses (say ) =hfp = hffr+hfe+hfb+hfr+hfv+hfm

m = 2.70

Head Calculations

(i) Max. Head = Gross head =Hmax = FSL in forebay - TWL min

= 1269.37 - 1210.91

m = 58.46

(ii) Rated Head = Hrated = Gross head / Max. Head range

= 58.46 / 1

m = 58.46

(iii) Min. Head = Hmin = MDDL in forebay - TWL max

= 1263.19 - 1213.5

m = 49.69

(iv) Min. Head (based on turbine parameters) = Rated Head x min head variation

= 58.46 x 0.9

m = 52.61

Min. Head -lower of above two m = 49.69

(v) Net Max. Head =Hmax(net) = Max. Head - Head loss

= 58.46 - 2.7

m = 55.76

(vi) Net Rated Head =Hrated(net) = Rated Head - Head loss

= 58.46 - 2.7

m = 55.76

(vii) Net Min. Head =Hmin(net) = Min. Head - Head loss


Chapter 8 - 26

Sl.


= 49.69 - 2.7

m = 46.99

ABSTRACT

1 FSL at forebay m = 1269.37

2 Tail Water Level - Min m = 1210.91

3 Tail Water Level - Max m = 1213.50

4 Max. Head = Gross head m = 58.46

5 Rated Head m = 58.46

6 Min. Head m = 49.69

7 Max. Net Head m = 55.76

8 Rated Net Head m = 55.76

9 Min. Net Head m = 46.99

10 Total losses m = 2.70

Design Discharge

Sl.


A Design Data

a Project Capacity = P KW = 10000

b Number of units = N Nos. = 2

c Max. Head = Hmax m = 58.46

d Rated head = Hrated = 58.46

e Min Head =Hmin m = 49.69

f Max. net Head =Hmax(net) m = 55.76

g Rated net head =Hrated(net) = 55.76

h Min net Head =Hmin(net) m = 46.99

i Max. Overload = 115%

j Min. load (as specified by Manufacturer) = 60%

k Turbine efficiency =nt = 91.00%

l Generator efficiency =ng = 96.00%

m Gear box efficiency =ngb = 98.50%


I) Power Plant capacity =P KW =

Where,

P = Power in kW

Q= Rated discharge

H= Rated head

η = Combined efficiency of TG unit = ηt x ηg x ηgb

= 0.91 x 0.96 x 0.985

= 86.00%

ii) Rated discharge = Qr = P / H x 9.81 x η

= (10000 / (55.76x 9.81 x 0.86)

Cumecs 21.26

iii) Maximum Discharge = Design discharge =

Rated discharge x max. overload

capacity

= 21.26 x 1.15

Cumecs = 24.45

iv) Min. discharge per unit =Qmin =

(rated discharge/machine) x min.

load

= (21.26 / 2) x 0.6

Cumecs = 6.38

ABSTRACT

1 Design discharge -plant Cumecs = 24.45

2 Rated discharge Cumecs = 21.26

3 Min. discharge per unit Cumecs = 6.38


Chapter 8 - 27

Turbine

Sr.

No. Particulars Details

A Design data

1 Rated Discharge: 10.63 cumecs

2 Net Head at Rated Discharge: 55.76 m

3 Gross Head: 58.46 m

4 Site Elevation 1,210.00 m

5 Setting of tail water level (1.00) m

6 Efficiency Priority: 10

7 System Frequency: 50 Hz

8 Minimum Net Head: 46.99 m

9 Maximum Net Head: 55.76 m

B Turbine selection

1 Arrangement:

Horizontal with

runner overhung

on generator shaft

2 Type of turbine Francis

3 Intake Type:

spiral case with

inlet below unit

axis

4 Runner pitch Diameter: 1288 mm

5 Unit Speed: 428 rpm

6 Multiplier Efficiency Modifier 1

7 Flow Squared Efficiency Modifier 0

8

Specific Speed at Rated Net Head (

Turbine )

At 100% Turbine Output: 206.8

At peak Efficiency Condition: 206.8

C Turbine performance data

At Rated Net Head of: 55.80 m

% of Rated Discharge Output (kW) Efficiency (%) m3/s

** 115 6203 91.1 12.4

100 5403 92.9 10.6

* 100 5403 92.9 10.6

75 3869 88.7 8.0

50 2166 74.5 5.3

25 687 47.3 2.7

+ 66.6 3299 85.2 7.1

** - Overcapacity * - Best

Efficiency Condition at Rated Net

Head

+ Peak draft surging condition

D Sigma Allowable

Sigma Allowable Max. Output (kW) Efficiency (%) Discharge (m3/s)

1 At Maximum Net Head of: 55.8 m

6203 91.1 12.4

2 At Minimum Net Head of: 47 m

4839 89.7 11.7

E Summary of turbine selection

1

Maximum Runaway Speed (at

Max. Net Head): 774 rpm

2

Turbine discharge at runaway

speed 7.2 Cumecs

3

Maximum Hydraulic Thrust (at

Max. Net Head): 35961 kg

4 Approximate runner weight 1871 kg

5 Velocity at draft tube exit 2.3 m/sec


Chapter 8 - 28

Sr.

No. Particulars Details

Intake type

spiral case with

inlet below unit

axis

1 Inlet Diameter: 1524 mm

2 Inlet offset 1734 mm

Draft tube Elbow

1 Centre line to invert 2576 mm

2 Shaft axis to exit length 6955 mm

3 Exit diameter 2447 mm

4 Exit to bottom floor 1295 mm

Shafting Arrangement

Horizontal with

runner on turbine

shaft

1 Generator shaft extension 801 mm

2 Turbine shaft diameter 279 mm

Miscellaneous

Horizontal with

runner on turbine

shaft

1 Wicket gate height 353 mm

2 Wicket gate Circle diameter 1506 mm

Notes

All information listed above is

typical only.

Detailed characteristics will vary

based on turbine manufacturer's

actual designs.

Detailed Project Report Sagana III HEP Chapter 9 - Electro-Mechanical Works

Chapter 9 - 1

Chapter 9-Electro-mechanical works


Chapter 9 - 2

9. Introduction

Sagana-III Small Hydro project is a run of the river type scheme on Sagana River in Nyeri

district (Central Province) of Kenya. It consists of 2 (two) units (2 x 5 MW), operating under a

gross head of 58.46 m and rated discharge of 21.26 cumecs. The two generating units with other

associated equipment will be accommodated in a surface powerhouse. The generation voltage is

proposed to be 11 kV. This voltage will be stepped up to 132 kV voltage level by generator step-

up transformers which are located at the upstream side of the Power House. It is proposed to use

two (2) number three-phase step-up generator transformers rated (8 MVA x 2), 11 kV/132 kV.

On the LV side, transformers will be connected to the generators by means of 11 kV isolated

phase bus duct. On the HV side, transformers will be connected to 132 kV outdoor conventional

type switchyard by 132 kV overhead transmission lines (link lines).

The power generated at Sagana-III HEP will be evacuated through 132 kV Outdoor Switch Yard

through double circuit to 132 kV transmission line to Sagana town.

9.1 Drawings

The following drawings may be referred

Sl. No. Item Description Drawing No.

1 Power House Sagana-III-011

2 Power House Sec. Sagana-III-012

3 Single Line diagram Sagana-III-026

4 Switch Yard Sgaana-III-027

9.2 Turbine

As discussed in previous chapter on Power Potential studies, the optimum output of the

generating plant has been decided as (2 x 5000 kW). This is in view of the effective utilization of

the discharges and to ensure reliability of generation and flexibility in operation.

9.3 Main Electro-Mechanical Components

9.3.1 Main Inlet Valve

Two nos. main inlet valve of 1524 mm diameter butterfly valve shall be provided for controlling

the flow while discharging the water into the turbine and also required to be closed for

maintenance of the units. The M.I.V. is provided with a closing weight and hydraulic cylinder to


Chapter 9 - 3

act under an emergency as a reliable shut-off device, even when no other external power

dependent activating source is available. The torque for closing is derived from the weight from

the closing hydraulic moment acting on the disc and also from the appropriate eccentric pivoting

of the valve disc under an emergency situation; it shall be complete with pipes, hydraulic

systems, embedded parts etc.

9.3.2 Hydraulic Turbines

The scope of supply and specifications for the equipment under the same shall be generally in

accordance with the tender specifications, taking into account amendments and clarifications

thereof. Few changes in type of construction or materials of construction in the offered

equipment are either due to the advancement in technology over period of time or due to the fact

that type of construction varies slightly from manufacturer to manufacturer. The offered

materials of construction are of the equivalent or better grade than specified in tender. Below is a

typical site photograph of assembly of the complete Turbine-generator system and indicating

major assemblies for reference.

9.3.3 Choice of type of Turbine

As per the power potential studies carried out in previous chapter (two) number turbines each of

(5000 KW) capacity at 100% of rated discharge which is 21.26 cumecs for 10 MW with

efficiency of 92.5% has been suggested. The selection of type of turbine for a Hydro Power

Project is a function of its specific speed. Following are the design parameters for Sagana-III

Small Hydro Project.

FSL at Forebay = EL 1269.37 m

Minimum tail water level = EL 1210.91 m

Gross Head = 58.46 m

Total Losses = 2.70 m

Hence, Rated Net head = 55.76 m

The specific speed of turbine can be calculated from the following formula

Specific Speed ( )

N = Rotational speed of turbine in rpm

= 428

H = Rated net head = 55.76 m


Chapter 9 - 4

P = Rated turbine output in metric Horse Power

= 5403 / 0.736 (Since, 1 Metric HP = 0.736 KW)

= 7341.032 HP (~7341 HP)

( )

The range of specific speeds for various types of turbines is given below:

Sl. No. Type of runner Ns

1 Fixed Blade Propeller 300-1000

2 Adjustable Blade Kaplan Turbine 300-1000

3 Reaction- Francis 65-445

Impulse Turbine

4 Pelton turbine per jet 16-20 per jet for multiple jet

5 Cross Flow 12-80

This definitely indicates a choice of Francis turbine. For the given head condition also, Francis

is recommended turbine which shall be capable of running at 115 % of rated capacity.

Turbine shall be horizontal shaft type suitable for coupling directly to horizontal shaft

synchronous generators of 5000 KW (0.85 power factor assumed) rating. The turbine shall be

capable of giving outputs higher then rated outputs to match the over load capability of

generator. Turbine shall be designed to give a rated output corresponding to 5000 KW at bus bar

at a gross head of 58.46 m. However, the final decision in this regard shall be taken after detailed

discussions with manufacturer of the machines for the given set of conditions.

9.3.4 Turbine Description

9.3.4.1 Spiral Casing with Stay Ring and Generator Side Cover

The spiral casing shall be fabricated from several spiral plate sections to suit transportation

requirements, which shall be adapted to the side plates of the stay ring and welded in place. On

the upstream side, one welded-on flange with a distance piece provides the connection between

spiral inlets to the turbine inlet butterfly valve (through telescopic type of dismantling joint). The

stay ring shall have adequate number of stay vanes of correct profile and inlet and outlet angles.

The turbine spiral casing is mounted on the turbine floor by supporting feet and foundation

plates. The spiral case shall be equipped with tapings for Winter Kennedy Method (if applicable)

and drainage of spiral case. The required anchoring material is included in our scope of supply.


Chapter 9 - 5

The welds in the spiral casing and stay ring shall be inspected by dye-penetration test/ ultrasonic

test. Spiral casing shall be subjected to a hydrostatic pressure test as per relevant standard. For

the purpose of the pressure test, the stay ring opening shall be closed by a separate pressure test

ring. The embedding of the spiral casing in concrete shall be carried out with the casing under

suitable pressure.

9.3.4.2 Draft tube

Draft tube shall consist of:

Cone

Elbow sections

Anchoring material

Conical liner

“Draft tube cone & bend” is flanged on one side to “draft tube side head cover” and on the other

side to the draft tube liner flange.

The flange connections considerably facilitate and simplify the assembly and dismantling

operations consisting of:

9.3.4.3 Generator-side head cover

The solid plate together with the generator-side plate of the stay ring can be made either as a

single component or of bolted construction. It accommodates the guide vane drive side bearing,

labyrinth rings and the shaft sealing casing.

9.3.4.4 Draft tube side head cover

The single-part, solid plate is attached to the stay ring and accommodates the suction side guide

vane bearings and the labyrinth rings.

9.3.4.5 Stationary labyrinths

The single-stage labyrinth rings are of the non-split type, and frictionally connected to the head

cover. The chosen material guarantees a large hardness difference between the stationary and

revolving labyrinth rings.


Chapter 9 - 6

9.3.4.5 Guide vanes

The guide vanes with its trunion are castings of 13% Cr – 4% Ni stainless steel. All wicket gate

bearings, both radially and axially, are made to be maintenance-free. An `O’ ring seal does

sealing against the water flow channel.

9.3.4.6 Levers

The guide vane levers designed as links are clamped to the guide vane stems and locked in

position during assembly. A disc bolted to the stem prevents the lever from shifting axially. The

frictional connection is a safety clutch and prevents possible damage to the guide vanes in case

foreign bodies get stuck between the gates. All guide vane levers are connected by the bolts to

the vane operating ring.

9.3.4.7 Gate operating ring

The gate operating ring is connected by bolts, carried in maintenance-free bushes thereon with

the individual wicket gate levers and also supported.

9.3.4.8 Servomotor

The wicket gate servomotor is of double-acting type, operated by oil pressure and mounted on

the generator-side head cover. The piston rod is directly connected with the gate-operating ring

and the levers control the wicket gate position. The servomotor can be supplied with an integral

feedback transmitter.

9.3.4.9 Francis Runner

The Francis runner shall be integral cast of 13% Cr and 4% Ni alloy stainless steel (ASTM A-

743 Gr. CA-6NM) and shall be designed to provide the best hydraulic profile so that it gives

maximum efficiency with minimum of cavitation. The runner cone shall be stainless steel casting

/ weld plate stainless steel fabrication. All surfaces on the runner exposed to the flow of water

shall be finished smooth by grinding or other means so as to be free from hollows, depression,

cracks and projection. The water passage on the blades, crown & skirt shall be finished to correct

profiles for the prototype based on homology with the successful turbine model. The runners

shall be balanced statically at the works before dispatch. A friction-type flange coupling

guarantees a perfect interchangeability of the runner with no need for additional machining or


Chapter 9 - 7

adjustment. Hydraulically pre-tensioned bolts provide the necessary contact pressure. It is

understood that the special pretension-equipment will form part of the supply.

9.3.4.10 Shaft Sealing Arrangement

A labyrinth seal prevents the operating water to escape from between the shaft and the generator

side head cover. The small leakage flow cools the labyrinth. The leakage flow is radially

splashed off into the seal housing by a splash ring and flows off naturally through an adequately

dimensioned pipe. Admission of sealing water is not necessary.

9.3.4.11 Turbine Control & Governing System

The digital microprocessor based governor developed for double regulated turbines will be

installed in the Unit Control Board. The governor system will be complete with feedback

sensors, pressure oil pumping unit, piping, valves, instrumentation as well as all accessories and

equipment necessary for the operation. The governing system will consist of the following main

parts:

1. Digital microprocessor based governor (one no. for each unit) located in Unit Control

Board.

2. Speed measurement devices.

3. Feedback measurement devices.

4. Governor hydraulic oil supply unit including oil tank with level indicator, temperature

switch and breather.

5. Accumulator of adequate capacity for one closure with charging and gauging equipment.

6. One normal running AC motor driven pump

7. One standby electric AC motor driven pump

Following hydraulic control elements are also provided as required during detailed engineering:

1. Valve for wicket gates control.

2. Pressure relief valve.

3. Pressure gauges.

4. Pressure switches.

5. Pressure filter.

6. Emergency valves


Chapter 9 - 8

7. All interconnecting piping between the governor pressure oil pumping unit and

servomotor.

9.3.5 Mechanical Auxiliaries

9.3.5.1 Cooling Water

A pumping system would be provided to supply adequate quantity of water from the tail race for

cooling of the turbine and generator bearings, generator air coolers and selected plant services.

9.3.5.2 Fire Protection System

Water for firefighting would be taken from elevated reservoir providing both reliable operation

and ample capacity to fight fire in the power house. A back up water supply to this reservoir

would also be provided.

9.3.5.3 Material Handling in the Power House

In order to expedite the completion of various construction activities of the power house, one

EOT of 25/5 tones capacity would be installed in the power house. This crane shall primarily be

used for erection, maintenance and repair of generating units.

9.3.5.4 Compressed Air System

A compressed air plant would be installed to meet the requirements of the governor oil system

and the oil pressure system spherical valves at 120 bar pressure.

9.3.6 Electrical Equipment, Control and Protection Equipment

9.3.6.1 Generator

To convert mechanical energy achieved through turbine to electrical energy, generators shall be

provided. Generator should be able to supply 3 phase, 50 Hertz A.C. at 11 KV level. Generator

shall be synchronous, brushless type having 0.85 power factor (lag). The rated output of

generator shall be (5000kW) and it shall be horizontally and directly coupled to the turbines.

For this reason, speed of generator has been matched with the speed of the turbine. The above

capacity of generator ensures 115% load output at 0.85 p.f.

The generator manufacturer shall coordinate with the turbine manufacturer to match the speed,

Runway speed, moment of inertia, overloads capacity and coupling arrangements etc.


Chapter 9 - 9

9.3.6.2 Synchronous Versus Induction Generator

For small capacity projects, line excited induction generators can be preferred over synchronous

generators because of their low initial cost, ease of operation and maintenance simplicity. The

induction generator uses excitation power supplied from an external source, which is normally

the grid. However, in case of grid failure, black start of machines will be difficult. Since

Sagana-III Small Hydro project is of 10 MW, dependability on grid could result in loss of

power due to standstill generator. Hence, synchronous generators are proposed with the

following protections:

Stator - phase to earth faults

Stator - phase to phase faults

Over load

Single phasing

High/low voltage

Loss of load and over speeding

Reverse power flow

Poor power factor

Stator overheating

Rotor overheating

Bearing overheating

The electromechanical equipment manufacturer has to co-ordinate with the control panel

manufacturer to provide necessary protections.

9.3.6.3 Stator Frame

The stator frame is made of Welded Steel Construction and has adequate thickness to prevent

distortion under operation. The frame is robust and rugged, designed to withstand bending

stresses and deflections due to its self-weight and weight of the complete core to be supported

by it. The design takes care of safe transmission load of all types and minimizes vibration and

noise level, Stator bore is circular to ensure uniform air gap between the stator and rotor,

thereby minimizing the unbalance magnetic pull. The Frame is rugged and strong to withstand

stresses during normal operation and extreme stresses due to short circuits.


Chapter 9 - 10

9.3.6.4 Stator Core

The stator core is built-up of thin, high quality, low loss non oriented grains, cold rolled Silicon

steel Laminations. Each punching is carefully deburred and laminations are insulated on both

sides with high quality insulating varnish to minimize eddy current losses. Ventilation ducts are

provided at intervals along the stator core, being formed by means of steel spacing bars securely

welded to adjacent punching. The laminations are securely held in place by clamping flanges at

each end. The clamping flanges are made up of mild steel.

9.3.6.5 Stator Winding

The stator winding has class “F” insulation system. The stator winding is of multi-turn type,

insulated throughout with epoxy resin, mica paper tape and glass tape insulation system. Each

coil is made up of number of strands of glass braided copper of electrolytic quality, and of

rectangular cross section, to minimize eddy current loses. The coils are provided with class “F”

epoxy resin, mica paper tape and glass tape insulation. The coils are treated to eliminate void to

ensure high factor of safety against breakdown. An anti-corona shield consisting of a butt layer

of asbestos tape and a semi conducting graphite tape / paint is applied to the straight portion of

each bar. The overhang portions of the winding is braced together with packing blocks and

securely laced to support rings made of molded synthetic resins bonded fabric carried on

brackets adjacent to the stator core end plate. Sufficient gap is provided in the top and bottom

coils for good ventilation and to avoid hot spots. The coils are held in place in open type slots by

wedges of non-shrinking material of class F Epoxy glass laminates.

The whole stator is Vacuum Pressure Impregnated (VPI). After the impregnation and curing

process, the whole unit forms a rigidly supported fully consolidated, void free winding. The resin

fills all the voids in the stator winding and results in better heat transfer from conductor to stator

core.

9.3.6.6 Terminal Arrangement

The three main leads and three neutral leads of the generator windings are brought out of the

stator frame, in two separate Terminal Boxes. The Phase and Neutral end of the windings are

brought out with suitable insulating enclosure where they pass through the generator housing.

The main and neutral leads are provided with terminals suitable for connection with XLPE

cables.


Chapter 9 - 11

9.3.6.7 Cooling System

The generator is natural air cooled, rotor radial fan / axial fans is / are designed to give a smooth

and quiet flow of air, Air is drawn from one / both End and Discharged at the other end / top of

the machine, combined action of rotor poles and fans are sufficient to extract the heat generated

in the generator

9.3.6.8 Temperature Detectors

Resistance type temperature detectors of simplex / duplex type are arranged symmetrically in the

stator winding to indicate the temperature obtained during operation. An Auxiliary Terminal box

having suitable terminal blocks are mounted on the generator frame to terminate the resistor

element connections. The temperature detectors leads are kept flexible to facilitate disconnecting

them without breakage.

9.3.6.9 Rotor Core

The Rotor Core is made up Rotor Stampings skip notched to form cylindrical poles, directly

stacked on to the rotor shaft. Ventilation ducts are provided at intervals along the rotor core,

being formed by means of steel spacing bars securely welded to adjacent punching. The rotor is

designed to safely withstand all mechanical stresses imposed by the maximum runaway speed.

The rotor core clamp is securely shrink fitted on main shaft taking care of requirements both at

normal operating speed and at maximum over speed conditions. The dynamic balancing of the

complete rotor is carried out at plant to keep values of rotor vibrations within allowable limits.

9.3.6.10 Shaft

The generator shaft is made of a high quality medium carbon steel, properly heat treated and

accurately machined all over and polished at the bearing surfaces and at all accessible points for

alignment checks. The shaft will have ample strength and stiffness at all speeds to resist vibration

or twisting on short circuits. The entire shaft is properly tested to ensure that it is free from

cracks, blowholes, slag formation or any other defects. A complete set of test reports covering

metallurgical strength, & ultrasonic tests performed on each shaft will be furnished.


Chapter 9 - 12

9.3.6.11 Cylindrical Poles with Field Windings

The cylindrical poles are provided with adequate damper windings to improve stability under

fault conditions, to reduce voltage distortions under conditions of single phase to ground fault.

9.3.6.12 Field Winding

The field winding is Multi-layer type, insulated with class “F” insulation and consists of copper

strips formed into concentric winding. All pole winding overhangs & connections between

adjacent field coils are made mechanically strong and firmly secured to the rotor by Res-I-glass

banding. The whole Rotor winding is Roll Dip Impregnated with resin & cured. The field poles

are provided with adequate damper winding of the low resistance type to improve stability under

single-phase fault conditions. The damper winding bars are of circular copper section embedded

in pole faces. The ends of damper bars are short circuited together by copper stampings.

9.3.6.13 Balancing

All rotating parts of the generator unit shall be well balanced dynamically so as to run perfectly

true, smoothly and within vibration limits specified and provision is made for readily and

effectively compensating any out of balance that may occur upon erection at site or

subsequently.

9.3.6.14 Bearings

The generator is provided thrust / guide bearing, on DE side and guide bearing on NDE side. The

bearings are forced oil lubricated White metal lined journal type pedestal / end shield mounted

Sleeve bearings. Bearings are designed to take the required axial / radial load. The NDE bearing

is insulated to prevent any harmful circulating current from passing through the bearings

surfaces.

9.3.6.15 Brakes

Generator will be provided with Hydraulic operated brakes of sufficient capacity to bring

rotating parts of generator and turbine to stop from 20 % of rated speed.

9.3.6.16 Brushless Excitation System

The Brushless Excitation System consists of a three phase AC Exciter having armature winding

on rotor & field winding on stator and a full wave Rotating Rectifier Bridge, mounted on same

exciter rotor / shaft. Three phase AC voltage from exciter armature is fed to the Rotating


Chapter 9 - 13

Rectifier Bridge & the DC voltage output of the rectifier bridge is directly fed to main field

Winding of the generator, mounted on the same shaft. Main Field winding in turn generates

three phase voltage in main generator armature winding, which is housed in main stator

9.3.6.17 Governor

The Governor shall be PLC based with electronic speed transmitters, feedback transmitters,

frequency adoption transmitters etc. The design of governor should be quite compact and is

suitable for operation of the unit from one place only. This arrangement requires only one

operator in the power station, who can start synchronize and load the unit from one place only by

controlling various controls provided on the governor panel.

The governor receives signal from a toothed disc mounted on the main shaft and amplifies it and

feeds it to servo-mechanism, which in turn controls the guide vane opening-closing stroke.

Digital Electronic governor with Oil Pressure Unit (OPU) is proposed to be housed in one of the

corners of the power house. This system will serve the purpose of sequential control of the unit

and the status indication for peripheral mechanical devices.

Indication

Control

All the indications such as butterfly valve On/Off status, breaker on/off status etc. will be

indicated on the unit control board incorporated in the Electronic Governor. 220 Volt D.C. lamps

of different color codes will be used for this purpose.

9.3.6.18 Controls provided on Governor

Speed control for grid frequency adaptation.

Speed control for isolated load operation.

Droop setting points for permanent droop and temporary droop

Basic control

Over speed Protection

With this arrangement the turbine shall operate smoothly and efficiently under any operating

conditions.

Turbine shall be equipped with suitable PLC based electronic type of governor. The PLC should

monitor and control following items

1. Forebay level


Chapter 9 - 14

2. Plant power output

3. Plant rated circuit breakers

4. Reactive power control

The governor shall be of proven design capable of maintain control of speed under all conditions

of heads and loads. Such a governing system shall be complete with actuator unit comprising

speed responsive element, restoring mechanism having adjustable temporary and permanent

droop setting, load limiting device, speed control, oil pressure units etc.

9.3.6.19 Metering System

Power generated shall be metered at generator terminals through metering C.T. and P.T. The

power transferred to 132 kV feeders shall also be metered through CTs and PTs. The metering

instruments shall be provided on relevant panels. The digital multifunctional meters shall be

provided on each generator control panel suitable for indicating following parameters

continuously rolling with selection facility.

9.3.6.20 Protection

The following protections will be provided by using integrated numerical protection relays for

generator, generator transformer and feeders.

a) Generator Electrical Protections

1) Generator Differential Protection

2) Negative Phase Sequence Protection

3) Generator Reverse Power Protection

4) Voltage Restrained Over Current Protection

5) Stator Earth Fault Protection

6) Loss of Excitation Protection

7) Over Speed (Electrical) Protection

8) Rotor Earth Fault Protection

9) Over Voltage Protection

10) Fuse Failure Protection

11) Under Voltage Protection


Chapter 9 - 15

Master tripping relays for controlled action shutdown, immediate action shutdown, critical

shutdown, emergency shutdown etc. shall be used separately in the system.

b) Mechanical Protections

1) RTQ (PT-100) in stator winding/core and in bearing for indication, alarm,

recording and shutdown of the unit.

2) Governor oil pressure low.

3) Over speed mechanical for normal and emergency shutdown.

c) Generator Transformer

1) Overall differential protection

2) Over current and earth fault protection with high Inst. Element

3) Stand by earth fault protection

4) T/F Winding Temperature High Alarm/Trip.

5) T/F Oil Temperature High Alarm/Trip.

6) Buchholtz relay - Alarm/Trip.

d) 132kV Line Protection

1) Digital over current and earth fault relay with high set unit.

2) Under voltage

3) Over / Under frequency

e) Station Aux. Transformer Protection

1) Fuse set on 11kV side

2) Digital over current and earth fault relay with high set unit on L.T. side.

9.3.6.21 D.C. Equipment

Float and boost type 220 Volt, 200 AH battery charger and tabular battery will be provided for

feeding power to indication lamps, protection relay coils, initial impulse to the self-excitation

system by means of field flashing and to operate few emergency lights.

9.3.7 Auxiliary Power Supply

1 Nos. 3 Phase, 11KV/415V, Dyn11, 315 KVA step down Unit Auxiliary transformer will be

used for feeding the station lighting and heating load for power house, staff colony, illumination

for approach road and switch yard.


Chapter 9 - 16

Emergency lights on important places will be operated by D.C. battery provided in the power

house. 100 KVA diesel generator set will also be provided for illumination in power house, staff

colony, street lights & switch yard during shut down of machines.

9.3.8 Cables and Terminations

XLPE type H.T. cables/ Bus Ducts shall be used connecting generator to generation

transformer, neutral grounding end.

9.3.9 Switchyard

A comparatively flat terrace is available near power house where step-up transformer will be

kept on plinth. Earth mat will be laid underground. Proper fuse sets, switches etc. will be

mounted on M.S. poles. The total area will be strongly fenced as per Indian electrical safety

rules. High voltage cable will be laid underground in cable trenches. The power cable will

connect low voltage side of the step-up transformers. 2 Nos. 11KV/132KV, 8 MVA, YNd11

step up transformer is used to carry the power generated to the bus duct. The transformer would

be ONAN type in accordance with BIS/IEC standards.

9.3.10 Grounding Systems

9.3.10.1 General

The following equipment/systems are required to be earthed:

a. Neutral points of different voltages

b. Equipment frame work and other metallic parts

c. Boundary fence, steel structures etc.

9.3.10.2 Design

The grounding system shall conform to IS 3043-1987 or latest edition and Indian Electricity

Rules 1956 along with latest amendments. The voltage between any two earthed points shall not

exceed 32 volts. The resultant value of earthing resistivity shall not exceed 1.82 ohm-m.

Earthing electrodes shall be uniformly distributed and located adjacent to fencing of switchyard

and power house. Three earthing connections to lightning arrestor shall be made directly.

Earth mats for switch yard and power house will be made with the help of 50mmx6mm G.I.

strips buried underground. Earthing electrodes may be 19mm diameter, 2m long M.S. rods

driven straight into the ground with the help of sledge hammers. Alternatively G.I. plate of size


Chapter 9 - 17

600mmx600mm may be used along with G.I. strip and G.I. pipe with funnel to achieve better

results.

9.3.11 Transmission System for Evacuation of Power

Power is to be evacuated from Sagana-III switchyard to Sagana town for further Sagana-Kutus

Line using a double circuit transmission line

9.3.12 Diesel Generating Set

Diesel generator of 100KVA, 415 V shall be provided at the project along with its accessories,

control panel, battery and cooling systems, indicating/measuring instruments, protection and

alarm systems etc.

Detailed Project Report Sagana III HEP Chapter 10 - Construction Plan & Program

Chapter 10 - 1

Chapter 10 - Construction Plan & Program


Chapter 10 - 2

10.1 General

Proper selection of construction methodology and tight project scheduling followed by strict

monitoring during construction are the major tools available in the hand of developers for

ensuring completion of projects within scheduled time and cost. The actual implementation of

the scheme is proposed to be divided in to three stages:

Pre- construction Activities

Construction Activities

Testing and commissioning

Various activities each of these stages in described below in detail.

10.2 Pre-Construction Activities

The activities proposed to be undertaken during Pre-construction work include the following:

Additional testing for construction materials

Tie-up for supply of construction materials

Site office

Forest clearance, if required

Acquisition of forest and private land for road, project components, Transmission

line, contractor’s camp and colony

Clearance from other agencies like Pollution control board, Public health, Irrigation.

New detailed topographical survey and Detailed design and preparation of tender

documents for Civil, Electro-mechanical, Hydro mechanical

Financial closure

Construction power

Construction of Approach road

Construction / Strengthening of bridges

Transmission line

Mobilization of Project team

It is proposed that critical activities like forest clearance, land acquisition, construction power

and preparation of tender documents be started immediately after signing of PPA. The

hydrological observation for the River Sagana would be continued during the entire Pre-

construction period of the scheme to firm up the discharge availability studies. As shown in


Chapter 10 - 3

enclosed bar chart, pre-construction activities are expected to be completed in a period of 6

months.

10.3 Construction Activities

10.3.1 Civil Works

The civil works of Sagana-III HEP include:

Trench weir

Upstream and downstream launching aprons

Intake pipe

Desilting basin

Power channel

Tunnel

Forebay

Penstock anchor blocks and saddle supports

Powerhouse

Tail race

Switchyard foundations

a) Diversion weir

The construction of trench type diversion weir involves the diversion of water in the river

Sagana. The construction is proposed in two stages. The first stage involves diversion of river

towards the left bank and construction of intake structure and trench weir on the left bank of

the river. In the second stage, the river will be diverted towards the other bank and

construction of trench weir along with the construction of launching apron completed. Both

the stages of work will be constructed during the low flow season in the river. The work may

have to be discontinued during rainy season. All the activities relating to the construction of

Trench weir are expected to be completed within 8 to 10 months period.

b) Approach Tunnel & Tunnel - 2

Excavation work for tunnel can be taken up immediately on start of construction work. The

work may have to be discontinued during rainy season. The construction of approach Tunnel


Chapter 10 - 4

(Approach Tunnel: Length 1260m) is estimated to be completed within ~14 months and

construction of Tunnel –2 (length 2340m) is estimated to be completed within ~21 months.

c) Approach Channel

Excavation work for the various sections of the power channel can be taken up immediately

on start of construction work. A trace cut will first be done and thereafter, the full excavation

for channel will be carried out. Concreting for power channel will then be undertaken. The

construction of power channel is estimated to be completed within 10 to 12 months.

d) Desilting basin

Base concrete for intake pipe and excavation for desilting basin can be taken up as an

independent activity. After laying the steel pipe, concreting of intake pipe and desilting basin

can be taken up. The construction of intake pipe and desilting basin is estimated to be

completed within 7 to 8 months from start of construction.

e) Power Channel - 1, Power Channel - 2 & Tail Race Channel

Excavation work for the various sections of the power channel can be taken up immediately

on start of construction work. A trace cut will first be done and thereafter, the full excavation

for channel will be carried out. Concreting for power channel will then be undertaken. The

construction of power channel is estimated to be completed within 10 to 12 months.

f) Forebay

The construction of forebay is proposed to be started after a period of six months from start

of construction activity. During this period, the embedment parts of gates and penstock are

likely to be available. The construction of forebay is estimated to be completed within 7 to 8

months

g) Penstock

A ~175 m penstock (main length) with the branch length (two nos.) being ~15.5 m, is being

proposed. The excavation for the Penstock works is estimated to take 7-8 months. The

fabrication and associated work of penstock which will start a two or three months after the

start of excavation is estimated to be completed within 09 to 10 months.


Chapter 10 - 5

h) Power House

The construction of powerhouse falls on the critical path. The excavation for powerhouse

will be taken up first and will be completed in 12 months. After receiving the details of

embedded parts of turbine and generator and valves, the concreting for powerhouse raft will

be carried out. Powerhouse walls and columns will then be completed up to service bay level.

There after the construction work for powerhouse columns and crane beam will be done to

enable erection of roof truss and roofing material. The construction of tailrace channel will

be done simultaneously with powerhouse construction. The crane beam is proposed to be

made available to the turbine manufacturers by the end of 6th month for erection of turbine

and generator. Finishing works for powerhouse will be carried out in parallel with machine

erection. The complete civil works for powerhouse are expected to be completed in 16

months from start of construction. Work at powerhouse may be disrupted for 4 months due to

climatic conditions.

f) Gates at Weir Site & Penstock Intake

The work of block outs for 2nd stage embedment will carry out along with other civil

engineering works. After laying the embedded parts, the 2nd stage concreting will be carried

out. The total work including 2nd stage concreting, installation of gates, Penstock shall be

completed in 45 days after completion of civil engineering structures.

g) Transmission Lines

A detailed topographic survey has been carried out for ascertaining the route length and

number of poles and other materials for construction of Transmission Line. Based upon the

requirements so worked out, materials shall be procured and the Contractor shall be finalized

for execution of the construction works. Supervision of construction shall be ensured by the

implementing agency. In case any technical assistance is required from the Consultant the

same shall be provided. The execution of construction of Transmission Line shall be done

concurrently with Powerhouse and Switchyard and shall be completed within 12 months

starting from 8th

month onward.


Chapter 10 - 6

10.3.2 Electro-Mechanical Works

Tendering and Order Placement: For timely completion and efficient monitoring of project,

complete electro-mechanical works shall be awarded to single contractor on the basis of Limited

International Competitive Bidding process or any other competitive process that is feasible and

time efficient. Tenders for the Electro-Mechanical works shall be floated during pre-construction

stage and order shall be placed to match the progress of work of civil works. Electro mechanical

work is estimated to complete in 17 months.

10.3.3 Engineering

Immediately on confirmation of the order, the electro-mechanical supplier shall start his detail

engineering and shall be asked to submit the first stage embedment drawing and other drawings

to consultant for approval. Consultant shall give comments / approval of drawings within 10

days of submission of drawings. All manufacturer drawings shall be submitted within six months

of award of work.

10.3.4 Manufacturing & Supply

Supplier shall be asked to submit the complete quality assurance and quality control program for

consultant approval. After approval of quality plan, supplier shall start his manufacturing and

erection- work. The first stage embedment viz., drainage water pipes, draft tubes embedment

etc., shall be supplied during sixth month of construction period. The supply of other equipment

shall start latest by 9th month from the placement of order and entire supply shall be completed

by the 13th month from award of supply order.

10.4 Erection & Commissioning

The crane shall be made available for electro-mechanical erection during 6th month and

powerhouse shall be handed over to contractor thereafter for erection of equipment. The

switchyard foundations shall be made available to contractor during 15th month. Contractor shall

complete erection work of powerhouse and switchyard in all respect before 20th

month. After

completion of erection works, pre-commissioning test of all equipment shall be completed within

one month and commissioning of first unit shall be done in 15 days and second unit shall be

commissioned in another 15 days. Thus, the project shall start generating by the end of 24th

month after award of work to the contractor


Chapter 10 - 7

10.5 O&M Manual & As Built Drawings

Soon after commissioning of project equipment, manufacturer shall submit the complete six sets

of as built drawings for consultant / developer record. The equipment supplier shall also furnish a

detailed operation and maintenance manual to the consultant for approval.

10.6 Handing Over:

After commissioning of project and successful operation of plant, project shall be taken over by

the developer. However, a team of contractor engineers shall be at project site for another two

months for any trouble shooting and training of personnel.

Detailed Project Report Sagana III HEP Chapter 10 - Construction Plan Program

Sagana-III Small Hydro-Electric Project (10 MW)

Bar Chart

S.NO. ACTIVITIES 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36

1 Pre-const.Activities & Mobilisation

2 Surveys, Hydrometrerological Data,Geological Data,Misc.

3 Firm up Designs i/c Model Studies

4 Permission to acquire Govt./Forest land

5 Acquisition of land

6 Intake Excavation

7 Intake concreting

8 Power channel Excavation & Concreting

9 De-silting chamber Excavation & Concreting

10 Tunnel (1260m) Excavation & Concreting

11 Tunnel (2340m) Excavation & Concreting

12 Forebay

13 Penstock Excavation

14 Proc.,Feb.,Transportation of penstock

15 Power House Ecavation

16 Power House concreating

17 Tail Race Channel ( 25 m ) Excavation & Concreting

18 Proc., & supply of Hydro Gen. Unit

19 Erection of Hydro Gen. Unit

20 Testing & Commissioning of Unit

21 Switchyard

22 Erection of transmission system

FIRST YEAR THIRD YEARSECOND YEAR

Chapter 10 - 8

Detailed Project Report Sagana III HEP Chapter 11 - Construction Material

Chapter 11 - 1

Chapter 11 - Construction Materials


Chapter 11 - 2

13. General

The main items of work for civil works have been estimated on the basis of drawings

prepared after carrying out the preliminary designs of civil components. Surveys have been

conducted to assess the availability and suitability of construction materials in the vicinity of

the project area. This chapter describes the estimated quantity of main construction

materials, their suitability for construction purposes and their availability.

13.1 Quantity of Work Involved

The civil components for Sagana-III HEP include Infrastructure roads, River diversion

works, Trench weir and launching aprons, Intake structure, Desilting chamber, Power

channel, Tunnel, Forebay, Penstock, Anchor blocks, embedded parts, Power house building,

Tail race channel, Switchyard and appurtenant works. The major items of work involved in

construction of these components include excavation, lean concrete, reinforced cement

Concrete, stone/brick masonry, gabions, boulder protection, and structural steel fabrication.

The materials required for construction viz., coarse aggregate, fine aggregate, cement,

reinforcement steel, structural steel, rubble, bricks shall be procured in required quantities to

match the construction schedule. The total quantity of material estimated is indicated below-

Sl. No. Description Quantity

1 Cement 16656 MT

2 Sand 9186 cum

3 Coarse Aggregate 18371 cum

4 Reinforcement Steel 914 MT

5 Structural steel 93 MT

6 Boulder Crates 4626 cum

7 Mild Steel grade 2 208 MT

13.1.1 Cement

Cement can be procured from the nearby towns of Nyeri, Othaya, and Muranga or from the

capital city of Nairobi which is around 180 km from project site. Trucks shall be used for

transportation of cement bags. Cement bags shall be stored in cement stores as per

specifications.


Chapter 11 - 3

13.1.2 Steel

Steel will be brought from steel stockyard at Nyeri, which is about 35 km from project site

and shall be the main source of structural steel and reinforcement TOR steel. Required

quantities of reinforcement and structural steel shall have to be stored at site from time to

time in advance of construction to avoid any hindrance in project construction. Penstock

steel plates, however, will have to be procured by the contractor directly from the

manufacturers as per design specifications.

13.1.3 Coarse Aggregate

Coarse aggregate and stones shall be quarried from the riverbeds of River Sagana. It has

been found that abundant quantity of rock is available within couple of kilometers of the

project area, which can then be crushed to cater to the requirements of coarse aggregates. A

stone crusher shall be installed at appropriate position along the length of the project.

The fine aggregate is available in various pockets of the River Sagana with in 15 km

distance of the Project area. The material will be screened and transported to the project site

by mules and tippers.

13.1.4 Other Materials

Explosives, POL, CGI sheets, industrial gas and other materials required for the project will be

transported from Nairobi which is 180 km from project site.

Detailed Project Report Sagana III HEP Chapter 12 - Project Organization

Chapter 12 - 1

Chapter 12 - Project Organization


Chapter 12 - 2

12. General

The construction of Sagana-III HEP will have to be supported by relevant infrastructure works

such as permanent and temporary colonies, office, roads and bridges, workshops, etc. situated

within the projected area. The project is planned to be completed in a construction period of 18

months and a 6 months period will be devoted for creation of infrastructure facilities.

The construction of the project is proposed to be carried out through contracting agencies

entrusted with suitable contract packages. Following packages have been envisaged for the civil

works for various project components:

Package I:

Infrastructure: Access road, Mule tracks, Ropeway, Colonies etc.

Package II:

Trench Weir, Intake Structure, Desilting basin, Water Conductor system, Forebay,

Penstock, Power House, Tail race and Switchyard.

Package III:

Hydro mechanical works viz. Penstock and its accessories, Trash Racks, Gates, Stoplog

Stilling racks, Gates valve. Beside above civil packages, the following packages have

been envisaged for the Electro-Mechanical works. (This scope can be further sub-divided

into parts to be allotted to different contractors.)

Package IV:

Turbine, Generators, Spherical valve, auxiliary, equipment, Cranes and 132 kv

switchyard equipment.

Package V:

Transmission Line and its allied items

It is also proposed that contract relating to preparation of detail designs, technical specifications

and construction drawings for various components of the project would be executed through a

separate contract package by a competent consultant. Keeping in view the hilly terrain in which

the project is located and the quantum of design and construction work involved, close

coordination would have to be maintained to avoid time and cost over–runs. The organization of

the project has been planned keeping the above in the view. Broad features of this organization

structure are described in the following paragraph.


Chapter 12 - 3

12.1 Project Organization

The works of Sagana–III hydro-electric project would be looked after by a project team set up

for the purpose under the overall control of M/s Lucid Power Generation Limited. The unit is

proposed to be headed by General Manager for the overall management of the project. All

engineering and project services would be accountable to the General Manager. The General

Manager would be assisted by separate departments to look after the planning, material

procurement, construction management, quality control, administration, financial and accounts

aspects of the projects. The organization set up above will be supported by the necessary

complimentary staff.

12.1.1 Organization for Construction of Civil and Electrical Works

The proposed organization for peak construction period will comprise of the following:

One General Manager, responsible for the overall execution of the works.

Four engineers, out of which two for civil and one each for electrical and transmission

line works shall assist the General Manager.

One Financial Controller along with necessary complimentary staff for ensuring proper

financial control.

One Human Resource Manager with necessity complementary staff to look after

personnel & administration, public health, liaison work, etc.

The above mentioned officers shall be overall in-charge of their respective offices and shall

function as an integrated team, every member of which will not only be conversant with his

duties and responsibilities, but will also get necessary report/feedback regularly from his

respective division for taking timely corrective measures wherever required. Each Division will

have technical and secretarial supporting staff as per requirement. The team has the bandwidth to

support more than one project, in the same vicinity, especially at the senior managerial level.

12.1.2 Functions and Responsibilities of Project Team Members

12.1.2.1 General Manager (Complete Project)

He will be responsible to complete Infrastructure works, construction of all civil, electrical and

transmission line activities as stated in Package I to V. He will also be responsible for pre-

construction investigations, material testing, quality control and control survey.


Chapter 12 - 4

He will be assisted by Four (4) engineers for execution of these works and one material testing

engineer. The key responsibilities of the team members attached to the General Manager will be

as under.

12.1.2.2 Engineer (Civil-I)

He will be responsible for construction of infrastructure works and shall be officer in-charge for

civil works relating to construction activities under Package I.

12.1.2.3 Engineer (Civil - II)

He will be responsible for execution of Package II.

12.1.2.4 Engineer (Electrical)

He will be responsible for the execution of all the electrical works involved in Package IV.

12.1.2.5 Engineer (Transmission line)

He will be responsible for execution of Package V.

12.1.2.6 Material Testing Engineer

He will be responsible for organizing testing of materials and quality control for the entire civil

works and would be in charge of up keep and maintenance of all laboratories. In addition, he will

be responsible for control survey of the whole project. For this purpose, he will be assisted by

supporting staff.

12.1.2.7 Need Based Units

The number of unit headed by one General Manager as proposed above, are based on the

function and physical requirements of the works. The works between all team members have

been so distributed that progress is achieved for the critical items of the works without affecting

progress on other works.

12.1.3 Project Monitoring and Quality Control

General Manager will be assisted at Project headquarters by the two managers (Co-ordination &

Monitoring), one for Civil and one for E&M and Transmission line works. Each manager will be

assisted by one engineer in carrying out the function of monitoring the progress of works, quality

control, co-ordination and liaison with various agencies, safety aspects etc. For this purpose, the


Chapter 12 - 5

Material testing Engineer would be reporting directly to General Manager in all technical

matters.

12.1.4 Finance and Accounts

The General Manager will have a Financial Controller (F.C.) supported by one Accounts Officer

(AO) attached to his office. The FC & AO will deal with work accounts, costing regular and

work-charged staff establishment etc.

12.1.5 Project Administration

Regarding project administration including maintenance of colonies, public relations, welfare

etc., the General Manager will be assisted directly by a Manager (Admin.) posted in his office.

The Manager (Admin.) will be assisted by a Security Officer along with supporting staff to look

after the vigilance and security aspects of the project areas.

The organization structure will be reviewed and firmed up as part of the detailed planning in the

pre-construction stage.

M/s Lucid Power Generation Limited will ensure adequate review of project activities, and

provide financial and administrative approvals and render policy guidance to the General

Manager of the project.

The project management shall function as a fully integrated team dedicated to the

implementation of the project. Every member of the team shall report regularly to his officer-in-

charge and shall be subject to review of his performance. They would periodically review the

progress of works, identify the problem areas suggest remedial measures, see through the

implementation of such measures, and have a realistic forecast of the status of the project in the

intermediate time frame.

12.2 Technical Advisory Committee

M/s Lucid Power Generation Limited will constitute a technical advisory committee comprising

of renowned experts. This committee will advise the project team through General Manager on

all critical aspects of project planning, design and construction activities.

12.3 Consultants

M/s Strategic Consulting Group (SCG) Shimla has been appointed the consultant for the project

and is assigned with Investigation, DPR Preparation and finalizing the project components. Other


Chapter 12 - 6

consultants/ service providers will be hired at an appropriate time as per requirements of the

project.

12.4 Reporting / Reviews

The project will be subject to monthly reviews so that all concerned are aware of progress to

date. The monthly report will give details of manpower, productivity, schedule and costs. The

purpose of these reviews will be to highlight the problem areas and provide the required

additional supervision and action to resolve the problem. The reports will be prepared using

inputs from consultants, contractors, construction supervisors, procurement officers etc. so that a

realistic picture of the project is available for review and report.


Chapter 12 - 7

General Manager (Project Head

Quarter)

Package I:

Infrastructure:

Access road, Mule

tracks, Ropeway,

Colonies etc.

Engineer Civil I

Package II:

Trench Weir, Intake

Structures, Water

Conductor system,

Power House, Tail

race etc.

Engineer Civil II

Package IV:

Turbine,

Generators,

Spherical valve,

Cranes, 132 kv

switchyard, etc.

Engineer Electrical

Package IV:

Transmission Line

and its allied items

Engineer Electrical

Testing of materials

and quality control

for the entire civil

works

Engineer Material

Testing

Personnel &

administration,

Public Health,

Liaison work

Human Resource

Manager

At Project

Headquarters

Co-ordination &

Monitoring team

(Civil)

Co-ordination &

Monitoring team

(E&M &

Transmission

works)

Financial Controller

(F.C.)

Accounts officer:

Work accounts,

Costing regular &

Work-charged staff

establishment etc.

Detailed Project Report Sagana III HEP Chapter 13 - Environmental & Ecological aspects

Chapter 13 - 1

Chapter 13- Environmental & ecological

aspects


Chapter 13 - 2

13. Introduction

The Sagana River is one of the major rivers of Kenya. It has a total Catchment of up to 1460 Sq.

Km. at proposed intake site. Around the intake site on both of the banks of Sagana River, the

area is mostly covered under farming. The powerhouse is envisaged at an elevation of 1209.91 m

on right bank of Sagana River.

The co-ordinates of the intake structure are 0°34'49.31"S, 37° 9'1.60"E. The Power house is

located at an elevation of ~1210 m. The co-ordinates of the power house are 0°36'52.64"S,

37°10'45.79"E (Toposheet No. 135/1).

The project site is located near Ithanji and Mutundu villages in Nyeri district of the Central

Province of Kenya. The project site area is well connected by road and is 180 Kms from the

capital city of Nairobi.

The area around the proposed project is largely covered with overburden in the riverbed and

adjoining terraces. Overburden consists of deep fill of ravine sediments whereas hill slopes are

covered with slope-wash materials. Rock outcrops are scanty. However the hill slopes around the

proposed project are stable and the area is conducive for constructing a small hydropower,

scheme on geological considerations. Also, the danger of erosion and disturbance to hill slopes is

minimal. A very small approach road to powerhouse shall need to be constructed.

The excavated material shall be deposited at previously, identified and approved sites so as to

minimize any adverse effects on the environment. A small colony shall be needed to

accommodate the skilled and specialist labour that would be brought from outside.

The flow conditions in the river would be left undisturbed except the diversion of design

discharge at diversion weir site for the purpose of power generation. Flows diverted for power

generation shall be led back to the Sagana River at the powerhouse location through the tailrace

channel.

The scheme shall take care not to endanger the flora and fauna species in and around the area.

All efforts shall be made so that no ecological disturbances or backlashes are brought in that

could upset the existing ecological balance in the project area.

13.1 Catchment Area Treatment

The catchment area at the diversion site of Sagana III HEP is 1460 Sq. Kms, out of which over

50% is in dense forest area (Aberdare Forest). This area comprises of forests with dense mixed


Chapter 13 - 3

jungles (Equatorial). The catchment in the uppermost reaches of the river is unapproachable. It is

proposed to provide engineering measures such as contour drainage, easing of critical slopes etc.

wherever required around the project area.

Afforestation is proposed in the catchment and an adequate monetary provision has been

earmarked in the project budget for this purpose.

13.2 Base-Line Data

13.2.1 Vegetation Profile

The project components are proposed to be constructed on private land. The ~4.8 Km long water

conductor system is proposed to run as various sections of closed RCC box type channel,

rectangular channel, and tunnel sections along the contour of the hills, up to the forebay.

Adequate compensatory afforestation shall be carried out and all efforts shall be made during

detailed designing of project components to avoid clearing of the existing trees as much as

possible.

Adequate compensation shall be made to all land owners for cost of land and any standing crop,

if any.

13.2.2 Seismicity

Kenya is located in the Eastern part of Africa. The Rift valley transverse through Kenya from

North to South. The East African Rift System (EARS) is a 50 to 60km wide zone of active

volcanoes and faulting that extends north-south in Eastern Africa for more than 3000 km (1864

miles) from Ethiopia in the north to Zambezi in the south. It is a rare example of an active

continental rift zone, where a continental plate is attempting to split into two plates which are

moving away from one another. This is the main source of seismicity in Kenya.

13.2.3 Climate

Sagana III HEP (10 MW) is located in the Central Province of Kenya. The climate of Central

Province is generally cooler than that of the rest of Kenya, due to the region's higher altitude.

The temperature varies between 7ºC to 30ºC. The period from February to March is the hottest

while the one from July to August is the coldest. The average annual rainfall received in the

catchment area is 1200mm (as per the Rainfall gauges at Embu Metrological station, Sagana

Technical School, Sagana State lodge, etc.).


Chapter 13 - 4

13.2.4 Land Use Pattern

The land to be acquired for project construction is partly cultivated. It is estimated that ~15.62

Ha of land will have to be acquired for the project. Over 90% of the -land requirement for the

project falls in private land. The project components or parts falling within the private land are

parts of the intake structure, desilting basin, water channel, forebay, penstock, power house and

switchyard. The portion of water conductor system in box type channel has been so planned that

there is minimum acquisition of land required and so it will induce minimal environment related

problems. Further there will not be any population displacement.

13.2.5 Public Health

Hospitals are available at Othaya, Nyeri and Muranga.

13.2.6 Human Settlements

The village near project area is Ithanji and Mutundu. The nearest towns around the project area

are Ngunguru ,Othaya and Nyeri. Chief’s office, Police station, and bank like KCB are available

in Othaya.

Basically, the village and towns mentioned above are well developed and are connected via a

tarmac road. Four-wheel drive vehicles are commonly used for transportation of goods as well as

passengers.

Though most of the villages are connected with mobile phones. Mobile phone operators such as

Airtel, Safaricom and Orange provide their service in the project area.

13.2.7 Project Impacts

The impacts on the environment, anticipated due to the project are divided under the following

heads:

i) Impact due to Project location

ii) Impact due to Project Design

iii) Impact due to Construction Works

iv) Impact due to Project Operation

All the above are discussed in the following sections.

i) Impact due to Project location

Rehabilitation


Chapter 13 - 5

There is no displacement of any local inhabitants and a very small area of land is required for

the project. Therefore, no rehabilitation measures are required.

ii) Impact due to Project Design Seismicity

There is no immediate threat perception to human life due to occurrence of an earthquake

specifically by the project.

Effect on Climate

As the project is very small having no submergence and impoundment of the order that could

even influence the microclimate of the region, there will not be any adverse effects on the

climate due to the project.

iii) Impact due to Construction Works

Air/Water Pollution

The only anticipated air pollution would be during the construction phase of the project due to

dust levels in the air. Simple procedures like spraying water to keep dust and SPM levels low

would be followed during the construction of the project components.

Soil Erosion

Afforestation is proposed in the catchment and an adequate monetary provision has been

earmarked in the project budget for this purpose.

Sanitary & Health effects from Construction camps

There would be no increase in incidence of diseases due to the setting up of colonies, as proper

health and sanitation arrangement shall be made in the proposed colonies. Locally available

labour would be suitably employed for the project construction activities. Skilled labour may

also be drawn from Sagana or Muranga that is at a manageable distance from the powerhouse

site. Eligible local persons shall also get employment according to their suitability during both

the construction and implementation phases of the project.

Adequate sanitary provisions would be maintained for the colony. Thus, this would not lead to

any increase in diseases or disease vectors, etc.

iv) Impact due to Project operation

Land inundation

The project is a run-of-the-river scheme, therefore it does not involve any storage reservoir.

Thus, the project operation would not lead to any inundation of the surrounding area. Also,

siltation would be negligible because sedimentation in the forebay tank would be minimal. The


Chapter 13 - 6

water shall be diverted through the diversion weir in the riverbed itself; therefore there would

be no changes in downstream water flows. The diverted water shall be led back into the Sagana

River.

Water logging & Salinity

Water logging and subsequent salinity aspects are not going to pose any problems. No

reservoir is involved and water is not allowed to remain stagnant in the proposed hydro project.

Salinity is not applicable.

Preventive Measures

During both the project construction and operation phases, the following precautionary measures

are proposed to be adopted.

1) Restoration of Construction Areas and Disposal of Muck

The entire construction area shall be properly landscaped when the project is completed so as

to merge the project with the natural surroundings. Major portion of the muck generated during

excavation of diversion channel, desilting tank, forebay shall be dumped in the properly

demarcated sites. These dumping sites shall have proper protection works like wire crates etc.

to make the slopes stable.

ii) Provision of Fuel for Labour Force

Fuel wood shall be purchased from depots of the Forest Department and shall be provided free

of cost to the labour force to ensure that such requirements do not compel the work force to fell

trees during the construction of the project. The project staff shall be provided with electricity

connection, and LPG cylinders. A provision in the cost estimate has been kept for this purpose.

Project Benefits

The foremost reason for promoting micro hydel schemes is their environmentally benign

character. Hydropower, unlike the conventional energy sources entails zero generation of

harmful chemical wastes or toxic gases. It is virtually free from pollution and its establishment

helps in the economic development of the region and should therefore be encouraged for the

rural, remote and far-flung areas.

The generation of environmentally benign energy at low cost shall help in curbing the gap

between high demand and low supply of power, thereby reducing the demand for fuel wood and

resultant global warming impacts.


Chapter 13 - 7

The socio-economic conditions of the local people from surrounding villages like Ithanji and

Mutundu shall be improved by means of employment generation.

Detailed Project Report Sagana III HEP Chapter 14 - Estimates of Cost

Chapter 14 - 1

Chapter 14 - Estimates of cost & Financial

Evaluation


Chapter 14 - 2

14. General

The estimates of cost have been prepared to arrive at the total capital cost of the project. The

estimates are based on the prices prevailing in December 2011 for materials, equipment, labour, etc.

Interests during construction period and financing charges have been worked out separately.

The estimates of cost have been prepared in two parts - Part - I cover the civil works of the project,

while Part - II covers Electrical works and transmission works of the project.

14.1 Cost of Civil Works

The detailed estimates of cost of civil works are based on the conceptual layout planning and

preliminary design of different components of works after review of site conditions, analysis and

studies etc. General arrangement and layout details of various structures as well as their features are

shown in drawings.

The rates for major items of civil works have been analysed as per civil engineering guidelines and

rates prevalent during the time of material survey. Rates for minor item of works and lump sum

provisions for some works have been made on the basis of experience of similar works on other

projects which have been recently completed or are under construction.

The rates for hydraulic gates, hoists, and cranes etc. are based on the prevalent market rates for such

works.

14.1.1 Provisions for civil works

The provisions under various sub-heads are derived as per international standards. Broad provisions

made under various sub-heads of civil works are briefly described below:

A - Preliminary

Under this head provision has been made for the feasibility studies to assess the true potential of the

site. Provision has been made for consultant's fees for preparation of the detailed project report, the

cost of detailed engineering, and other project development expenses such as legal fees, overheads

etc. The total provision under this sub-head is USD 789,091.


Chapter 14 - 3

Table 14.1 Development Budget

S. No. Particulars USD

1. Feasibility studies 43182

2. DPR 129545

3. Legal 250000

4. Tax & Audit 100000

5. Carbon finance 21591

6. Vehicles 80000

7. Environment studies 21591

8. Miscellaneous 43182

9. Overheads 100000

Total 789091

B - Land

This sub-head covers the provision for acquisition/purchase of land for permanent works, approach

roads, camp sites, workshops, stores, offices and permanent colony for the maintenance staff etc.

The table below summarises the total land requirement:

Table 14.2 Land requirement Summary

S.

No. Description

Length

(m)

Width

(m)

Length

(m)

Width

(m)

Area

(Ha)

Fraction

of total

Land

which is

govt. (Ha)

Govt.

Land

Pvt.

Land

Amount

(In USD)

1 Intake site 59 48 81 58 0 100% 0 0 6,876

2 Intake channel C&C 6 4 6 10 0 0 0 0 128

3

Auxiliary land for

Intake Structures

(work bench)

25 25 25 25 0 0 0 0 1,375

4 Desilting basin 71 21 71 41 0 0 0 0 6,386

5 Power channel

a) Cut & Cover 1115 4 1115 10 1 0 0 1 23,794

b) Open rectangular. 0 6 0 12 0 0 0 0 -

7

Job facility for

tunnel ( 3 at intake

and outlet each)

120 108 120 108 1 0 0 1 28,512

8 Forebay 36 13 56 33 0 0 0 0 4,066

9 Penstock before

bifurcation 186 2 186 10 0 0 0 0 4,174

10 Penstock after

bifurcation 10 15 10 23 0 0 0 0 506

11 Power House 28 19 59 49 0 0 0 0 6,387


Chapter 14 - 4

S.

No. Description

Length

(m)

Width

(m)

Length

(m)

Width

(m)

Area

(Ha)

Fraction

of total

Land

which is

govt. (Ha)

Govt.

Land

Pvt.

Land

Amount

(In USD)

12 Switchyard 86 56 106 112 1 0 0 1 26,118

13 Tail race channel 10 6 10 12 0 0 0 0 255

14 Tail Pool 36 9 42 19 0 0 0 0 1,756

15

Auxiliary land for

PH Structures (work

bench)

50 30 50 30 0 0 0 0 3,300

16 Dumping yard

1 0 0 1 26,400

17

Approach road to

power house and

other component

location

3000 8 3000 9 3 0 0 3 59,400

18 Explosive

Magazines 10 10 10 10 0 0 0 0 220

19 Colony 50 50 50 50 0 0 0 0 5,500

20

Transmission line

7.044Km long in

forest land (15 m

wide corridor has

been considered)

7044 10 7044 10 7 0 0 7 154,968

21

Crop compensation

at pole location in

Pvt. land (approx.

Rs. 30000/ pole

location)

0

22

Crop / tree

compensation along

corridor in Pvt. land

0

Total 11942 443

17

360,121

The total land requirement sums to ~17 Ha. The total provision under this sub-head is USD 0.36

million.

C - Civil Works

This covers the cost of river diversion works and diversion structure including cost of hydraulic

gates and hoists and upstream and downstream protection works. The total provision under this sub-

head is as below:

Table 14.3 Intake channel


Chapter 14 - 5

S. No. Item of Work Amount

1 Common Excavation 7,932

2 Excavation in Rock 25,704

3 Earth Filling 4,113

4 Concrete M-25 39,127


6 Steel Reinforcement 37,923

7 Water Stop 3,000

8 Dewatering 188

9 Filter Sand 900

Contingencies 7,263

Total 152,514

Table 14.4 Trench Weir

S. No. Item of Work Amount (in USD.)


2 Excavation in Rocks 26,025

3 Backfilling 4,164

4 Concrete M 10 2,090




8 Boulders & Crates 39,109

9 Boulder Pitching 110,000

10 Stone work in cement mortar 1:4 3,000

11 River Diversion during construction 50,000

12 Dewatering 7,500

13 Water stop 3,000

14 Trash rack 29,670

15 Embedded & non-embedded metal works 2,300

16 Intake Stop Log Gate

a) 1st and 2nd stage embedded parts 1,150

b) Hoisting / lifting 2,300

c) Gate 55,200

d) Chain Pulley 2,350

17 Intake Service Gate


b) Gate Leaf 3,853


Chapter 14 - 6

S. No. Item of Work Amount (in USD.)

c) Hoisting/lifting 4,700

d) Screw type 12,000

18 Shingle Flushing Gate


b) Gate Leaf 1,725


d) Chain Pulley 2,200

Contingencies 24,084

Total 505,770

J - Power House plant Civil Works:

Under this sub-head provision has been made for the following works:

Table 14.5 Power House plant Civil Works break up

Sr. No. Particulars Amount (USD)

1. Desilting Tank 1,104,241

2. Power Channel / Tunnel 4,786,856

3. Forebay 336,631

4. Penstock, Anchor blocks and Saddle Supports 922,075

5. Powerhouse Complex 1,538,362

Total 8,688,165

The details of the quantities used and their costs are as follows:

Table 14.5.1 Desilting Basin

Sl. No. Item of Work Amount (USD.)


2 Excavation in rocks 179,046



5 Concrete M-25 547,570


7 Stone Masonry (1:6) 4,900

8 Water Stop 12,000

9 Silt flushing pipe 900mm 14,400

10 Stilling Rack 2,100

11 Dewatering 3,750

12 Gate valves 1000 600

13 PVC pipe 30,000

14 Filter Sand 18,000


Chapter 14 - 7

Sl. No. Item of Work Amount (USD.)

15 Upstream Gates

a) 1st and 2nd stage embedded parts 920

b) Gate Leaf 9,400


d) Chain Pulley Block 6,000

16 Downstream Gates

a) 1st and 2nd stage embedded parts 920

b) Gate Leaf 9,400


d) Chain Pulley Block 6,000


Total 1,104,241

Table 14.5.2.1 Power Channel

Sr. No. Item of Work Amount (USD)




4 Concrete M-25 510,940


6 Water Stop 120,000

7 Dewatering 375


Total 1,380,843

Table 14.5.2.2 Tunnel


1 Common Excavation U/G 437,400


3 Rock Bolt(3-5m) 90,000

4 Concrete M-20 1,124,082

5 Concrete M-10 506,543


7 Water Stop 120,000

8 Dewatering 375

9 Structural Steel 38,376


Total 3,406,013

Table 14.5.3 Forebay


Chapter 14 - 8

Sr. No. Item of Work Amount (USD.)

1 Stripping & grubbing 300

2 Excavation in soft soil 30,920

3 Excavation in hard soil 128,835

4 PCC M-25 24,254

5 RCC M-20 68,653

6 Reinforcement Steel 25,889

7 PVC water stop 5,000

8 Trash Rack

a) Embedded parts 1,150

b) Structural, Steel 6,900

9 Railing 800

10 Stone Pitching 3,500

11 RR Masonry for escape channel 2,500

12 Penstock Gate

a) Gate Leaf 5,875

b) Embedded parts 1,725

c) Hoisting and lifting structure 2,300

d) Rope Drum Hoist 12,000


Total 336,631

Table 14.5.4 Penstock, Anchor blocks and Saddle Supports


1 Common excavation 47,174


3 Concrete M-25 167,640

4 Steel reinforcement 61,950

5 Penstock Steel 499,200

6 Y-piece saddle supports exp. Joints, manhole and pipe for

emergency escape

40,250

8 Air vent pipe 800


Total 922,075

Table 14.5.5 Powerhouse Complex


1 Common excavation 23,340



Chapter 14 - 9




5 Concrete M-25 561,880

6 Steel Super Structure 34,500

7 Railing and miscellaneous and non-embedded metal work,

rolling shutter

2,400

8 Installation of embedded metal work 2,300


10 PVC water stop 7,200

11 Bricks 18,176

12 Geotextile Textile 7618 or equivalent 5,400

13 Dewatering 1,350

14 Boulder protection 1,125

15 Drainage material around power house 1,376

16 Crushed stone (5-20 mm grade) 2,025

17 Gabion wall with wire crate 990

18 C.G.I sheeting (0.63 mm thick) 91,665

Misc. Item

19 Wall (230 thick)(brick masonry) 10,800

20 Cement plaster in 1:4 11,000

21 Doors and windows in powerhouse 9,000

22 Painting inside walls 1,620

23 Painting outside walls 1,620

24 Cement concrete flooring with hardener 14,000

25 Quarry tiles (Red stone) 3,600

26 Ceramic floor and wall tiles 2,160

27 Acid resistant floor titles 720

28 Water proofing ceiling compound 165

29 False ceiling 6,300

30 Misc. Steel Works (hand rails, safety chain etc.) 8,000

31 Embedded pipe 132

32 Embedded pipe of different diameter 600

33 Misc. sanitary fix. (Geyser, urinal, WC, sink, septic tank, soak

pit, etc.)

2,000

Tailrace



36 Earth Filling 319

37 Concrete M-25 13,894


39 Boulder Protection 2,188

40 D.T. Gates

a) Gate Leaf 9,400

b) Embedment 2,300


Chapter 14 - 10


c) Hoisting / Lifting 3,450

d) Rope Drum Hoist 24,000

Switchyard




44 Concrete M-20 141,501


46 GI Chain Link Fencing 5,000


Total 1,538,362

K - Buildings

Provision has been made under this sub-head for permanent and temporary residential buildings

for various categories of staff, non-residential buildings for offices, workshops, stores, rest

houses and field hostels and other service buildings such as hospital, school, police station and

utility services etc. Provisions for land development, lawns and gardens, fencing, internal water

supply, sanitation and electrical fittings have been made as per norms for various types of

buildings as per norms.

The total provision under this sub-head is USD 175,584.00, well within permissible limits.

M - Plantation

A provision of USD 27,440 has been made under this sub-head for plantation near the Barrage and

reservoir area, colony and camp sites etc.

Sr. No. Item of Work Unit Rate (USD)

1 Plants / Trees to be planted 9000

2 Making pit 0.5m x 0.5mx 0.5m 2250

3 Engaging three gardeners for one year 180

4 Cost of protection work for barbed wire 30000

5 Watchmen cum Gardner-2 Nos. for protection and plantation

for 3 years

180

Total 49,890

O - Miscellaneous

Under this sub-head provision has been made for the following items:

Recreation, Security arrangements, Medical assistance,

Fire fighting equipment, telephone, telegraph, wireless and other communication facilities.


Chapter 14 - 11

M. Boundary pillars and stone distances marks and benchmarks

N. Anti-malaria measures, Running of rest house for 2 years, Publicity information

Recreation facilities and beautification of project area.

Maintenance services for electrification, water supply etc. and other services including

security arrangement and fire fighting arrangement.

Other items such as visit of dignitaries, technical record of works, power supply,

compensation to workmen, writing of completion report and history of project etc.

Construction power arrangements for construction of civil works and for camp sites and

workshop etc. during the construction period.

The total provision under this sub-head is USD 48,955.

P - Maintenance

The provision has been made under this sub-head for maintenance of buildings and roads, and main

civil works during the construction period. The total provision is around USD 97,709 which is about

1% of Works less Preliminary, Land and Special Tools & Plant.

Q - Special Tools and Plant

Provision has been made under this sub-head for equipment such as Needle Vibrator, wheel loader,

canal trimmers, Wagon drill, Sump Pump, Pumps 5-10 HP, Water Sprinkler, vehicles such as cars,

jeeps, buses, ambulances etc. Provision for major construction equipment for civil works has not

been made under this head, as the construction of civil works will be carried out by a separate

construction agency. The total provision under this subhead is USD 100,000.

R - Communication

Provision has been made under this sub-head for construction of roads including approach roads.

Provision has also been made for remodelling and strengthening of main highway and bridges to

make them suitable for transport of heavy equipment for power station. The total provision under

this subhead is USD 150,000.00

X - Environment and Ecology

Provision under this sub-head has been made for compensatory afforestation, measures for

maintaining environment and ecological balance of the area, public health measures,


Chapter 14 - 12

establishment of fuel depots etc. Provision has also been made for treatment of catchment area

for prevention of soil erosion etc.

The total provision under this sub-head is USD 27,000.00

Y - Losses on Stock

Provision under this sub-head has been made at 0.25% of I-work less A - preliminary, B - land

and Q - special T & P.

Establishment

Provision has been made @5% of I-Works less B-land. This provision also includes

establishment for carrying out detailed designs, site supervision, quality control and cost control

cell. The total provision under this head is USD 558,477.00

Tools and Plants

Provision @ 1% of I-Works has been made to cover survey instruments, camp equipment, office

furniture, office equipment etc. The total provision under this head is USD 111,695.00

Receipts and recoveries on capital account

Under this head estimated recoveries by way of transfer of temporary buildings, resale of special T

& P and other miscellaneous recoveries have been provided. The total recovery of USD 50,000.00 is

estimated under this head.

Audit and Accounts

It has been taken as 1.0% of the cost of I-Works. The total provision under this head is USD

111,695.00

S - Power Plant (Cost of Electromechanical Works)

Cost of generating plant and equipment is based on current market prices for the proposed

machinery of 10 MW capacity.

The following table shows a detail of all the Electro mechanical equipment:


Chapter 14 - 13

Table 14.6 Electro-Mechanical equipment

Sr.

No.

Description Unit Qty. Total Price -

FOB,

Mumbai

(USD)

1 Turbines

1.1 Horizontal Francis Turbine comprising runner, guide vanes,

guide apparatus & regulating mechanism, indicating and

recording instruments, safety devices piping, in a complete

shape to develop rated output of 5000 KW at generator

terminals at rated head and discharge.

Nos. 2

1.2 Governing system including digital Electro hydraulic

governor, speed signal generator and TACP.

Nos. 2

1.3 Oil pressure Unit Nos. 2

1.4 Main inlet valve (Butterfly ) ( To suit turbine inlet) Nos. 2

1.5 Cooling water system provided with two pumps (main and

standby), one duplex filters, non-return valves, isolating

valves, pressure gauges, piping, mountings to supply cooling

water to seals and coolers.

Lot 1

1.6 Drainage & Dewatering System Set 1

2.1 Generator

Horizontal Shaft AC Syn. Generators Natural Cooled,

Cylindrical pole type, 5000 KW , 11KV, 500 rpm, 0.85 p.f.,

50 Hz. With Brushless excitation system with AVR, Lube Oil

System & Braking System.

Sets 2

2.2 Control, Protection, Metering System consisting of :

2.1 Generator LAVT and Surge capacitor panel Nos. 2

2.2 Generator neutral grounding (NGT) panel with neutral

grounding transformer

Nos. 2

2.3 Synchronizing Panel for Generators and 132 kV lines No. 1

2.4 Generator C/R Panel Nos. 2

2.5 Gen. Transformer C/R Panel Nos. 2

3 Power & Auxiliary Transformer consisting of:

3.1 Generator Transformer 8 MVA, 11/132KV, Ynd11, ONAN,

OCTC +/- 5% @2.5% Steps complete with all accessories

Nos. 2

3.2 Station Aux. Trfs., 315 KVA 11/0.415KV, Dyn11, ONAN,

OCTC +/-5%@2.5% steps

No. 1

4 415 V - LT Switchgear panel No. 1

5 DC System comprising of : Set 1

5.1 110 V, 150 AH DC Battery bank (VRLA Type)

5.2 110 V, 150 AH DC Battery Charger (Float & Boost charger)

5.3 110 V, DCDB

6 DG Set - 415V- 100 KVA with AMF panel Set 1

7 - 11 KV & 1.1 KV XLPE insulated Aluminum conductor

armored Power Cable with cable trays, termination kits

Lot 1


Chapter 14 - 14

Sr.

No.

Description Unit Qty. Total Price -

FOB,

Mumbai

(USD)

and accessories.

- Multicore PVC insulated Copper Conductor armored

control cable with cable tray

8 132 KV Switchyard Equipment at Power House (outdoor

type ) consisting of :

Lot 1

8.1 132 kV, outdoor type 1250 Amps, Isc=25 KA, SF6 circuit

breaker

Nos. 4

8.2 132 kV Isolator with earth switch = 1250 Amp. (Motorized) No. 2

8.3 132 kV Isolator without earth switch = 1250 Amp. (

Motorized)

Nos. 5

8.4 130 kV 10kA Lightning arrestors Nos. 4

8.5 132 kV Current Transformer (150 /1 Amp.) Nos. 4

8.6 132 kV Potential Transformer ( Bus & Line) 132KV/√3

/110/√3/110/√3

Nos. 3

8.7 Marshaling Box for switchyard equipment Lot 1

8.8 Switchyard structures/Gantry/Tower etc. /Structure

CT,PT,LA, Isolator etc.

Lot 1

8.9 ACSR Conductor with hardware and accessories and Misc.

Items

Lot 1

8.10 132 KV Manually operated DO fuse. No. 1

9 Supervision of Erection & Commissioning Lot 1

10 List of Spares ( as per our offer) Set 1

11 Tools and Tackles ( as per our offer) Set 1

Grand Total Price

5,019,991

A total provision of USD 5,019,991.00 has been kept under this head.

T - Transmission

Provision for construction of a 7.04 km long transmission line from Power house site to the 132

KV Sagana-Kutus line in Sagana town has been made. The following table shows the breakup of

the cost estimate:


Chapter 14 - 15

Table 14.7 Transmission works

Sl. No Item Description Total Cost

1 11.5 ISMB Poles for (Double Pole) Tr. Lines 17,200

2 ACSR ' DOG' conductor 232,485

3 Disc insulator of 70kN with attachments and accessories 26,316

4 132 KV Pin insulator with electrolytic binding wire for conductor 1,161

5 Hardware Fittings for Disc insulator 516

6 Danger plate, anti-climbing devices 215

7 Stay set with stay wire 10,800

8 Earthing system of 2.8m long 25mm hot dip galvanized iron rod 1,075

9 MS flat for pin insulators & hardware for double pole 946

10 MS 50 x 6 mm for fixing earth wire on pole 86

11 8 S.W.G. G.I. wire 1,409

Total 292,209

The total provision under this head is USD 292,209.00.


Chapter 14 - 16

Estimated Direct and Indirect Cost of the Project

Total cost of the Project at Dec, 2011 price level works out as under:

Table 14.8 Direct and Indirect Cost

S No. Item Civil E&M Total

USD Mn USD Mn USD Mn

A Direct Cost

I I - Works

A - Preliminary 0.79

0.79

B - Land 0.36

0.36

C - Civil Works 0.66

0.66

J - Power plant civil work 8.69

8.69

K - Buildings 0.18

0.18

M - Plantation 0.05

0.05

O - Miscellaneous 0.05

0.05

P - Maintenance during construction 0.10

0.10

Q - Special Tools and Plants 0.10

0.10

R - Communication 0.15 0.15

S - Power Plant

5.02 5.02

T - Transmission

0.29 0.29

X - Environment, Ecology and Afforestation 0.03

0.03

Y - Losses on stock 0.02

0.02

Total: I - Works 11.17 5.31 16.48

II Establishment 0.34 0.22 0.56

III Tools and Plants (T&P) 0.34 0.22 0.56

IV Receipts & Recoveries (0.05)

(0.05)

Total Direct Cost 11.79 5.76 17.55

B. Indirect Cost

Capitalization of abatement of land revenue 0.02

0.02

Audit and account charges 0.07 0.04 0.11

Total Indirect Cost 0.09 0.04 0.13

Total direct & indirect cost 11.87 5.80 17.68


Chapter 14 - 17

To this the Initial Working capital, capitalized spares, Interest during Construction, Financial

Charges, Escalation during construction, Contingency, upfront loaded DSRA Cost shall be added to

arrive at the total project cost.

A summary of the table above is shown below:

Table 14.9 Summary of Costs

Sr. No. Cost Components USD mn

1 Civil Works 11.79

2 E & M 5.76

O/W Transmission Work 0.29

Total cost without IDC & FC 17.55

3 Indirect Cost 0.13

(a) Total direct & indirect cost 17.68

The summary of the rates of items is shown below:

Table 14.10 Summary of Rates of items

Sl. No. Items Unit Rate

(USD/Unit)

1 Cement Per bag 6.00

2 Cement Concrete M-7.5 m3 90.00

3 Cement Concrete M-10 m3 95.00




7 Cement Concrete Lining,100 mm thick,M-10 Grade m2 15.00

8 Cement Concrete Lining,100 mm thick,M-25 Grade m3 60.00

9 Random Rubble Masonry in CM 1:6 m2 40.00

10 Stone Masonry (1:6) m3 70.00

11 Brick Masonry m3 80.00

12 Cement Pointing in CM 1:3 m2 6.00

13 Cement plaster 20 mm thick CM 1: 4 m2 5.00

14 Damp Proof Course,40 mm thick, with Bitumen Coating m2 15.00

15 Cement Concrete Flooring, 75 mm in M-15 m2 14

16 Marble Chip Flooring 40 mm m2 12

17 Dry Stone Pitching m2 90.00

18 Crated Bolder pitching With Cement Concrete m3 110.00

19 Tor Steel Reinforcement MT 1050


Chapter 14 - 18


(USD/Unit)

20 Structural Steel MT 1150

21 Penstocks MT 2400.00

22 Steel Works in Gates MT 2350.00

23 Steel Works in Stop logs MT 2350.00

24 Steel Works in Trash Racks MT 2350.00

25 Railing MT 800

26 Steel Truss MT 2200.00

27 Fine Sand m3 90.00

28 Coarse Sand m3 95.00

29 Stone Boulders m3 25.00

30 Aggregates 16-20 mm m3 45.00

31 Aggregates 20-50 mm m3 45.00

32 Marble Chips 100 kg. 35.00

33 Marble Dust 100 kg 20.00

34 Earthwork in Soil Mixed With soft soil and Shingles m3 6.00

35 Earthwork in Soil Mixed With Shingles and Boulders m3 15.00

36 Earth work In Rock Requiring Blasting m3 25.00

37 Extra for Additional Lead of 30m or Lift of 1.5m m3 5.00

38 Earthwork in Filing including Compaction m3 7.00

39 Earthwork in Mixed Soil m3 0.88

40 CGI Roofing m2 8.00

41 Carriage cost by Road MT/km 7.00

42 Head load per km- Cement MT/km 15.00

43 Head load per km- Steel MT/km 15.50

44 Head load per km-Others MT/km 15.00

45 Contractors profit % 15.00

46 Overhead Charges % 5.00

47 Extra Leads, average 2 man-day Man-day 0.66

48 Wetting And Compaction Charges Cum 0.79

49 Sundries T & P L.S. 0.42

50 Bitumen Kg 1.05

51 Wire Gauge m2 2.60

52 Rivets / Welders Nos. 4.90

53 G I Sheets m2 146

54 G I Bolts and Nuts Kg 3

55 Dewatering KWh 0.75

56 Stone fill crates in wire mesh for Gabion Wall m3 22


Chapter 14 - 19


(USD/Unit)

57 Water Stop m 20

58 Steel Pipe 900mm MT 1200

59 PVC m 100

60 Gate valves 500 Nos. 300

61 Chain Pulley Block Nos. 3000

62 Rope Drum Hoist 2 MT Nos. 4000

63 Rope Drum Hoist 7 MT Nos. 12000

64 Anchor bolt Nos. 20

65 Rock Bolt Nos. 15

66 Stripping & grubbing m2 2

67 RR Masonry for escape channel m3 50

68 Air vent pipe L.S. 400

69 GI Chain Link Fencing MT 1000

70 Saplings / Trees Nos. 2

71 Gardner wage per month USD 60

72 Watchmen cum Gardner USD 90

73 Road USD/km 50000

74 Drainage material around power house USD/ m3 16

75 Rate of Pvt. land USD/Ha 22,000

76 Rate of Govt. land USD/Ha 14,800

77 Geotextile Textile 7618 or equivalent USD 10

78 Doors & windows USD/ m2 800

79 Paint inside/outside walls USD/ m2 1.5

80 Quarry tiles- stone m2 10

81 Ceramic floor and wall tiles m2 15

82 Acid resistant floor titles m2 20

83 False ceiling m2 20

84 Embedded pipe 40 mm dia. pipe m 6

85 Embedded pipe 100 mm dia. m 12

86 Misc. sanitary fix. (Geyser, urinal, WC, sink, septic tank,

soak pit, etc.)

L.S. 2000

Detailed Project Report Sagana III HEP Chapter 15 - Financial Evaluation

Chapter 15 - 1

Chapter 15 - Financial Evaluation


Chapter 15 - 2

15. General

Based on estimates, material survey and calculations, the project is likely to cost 22.97 Million

USD. This cost includes preliminary estimates for civil works, electromechanical works, indirect

costs, financing costs including interest during construction, and construction cost escalation.

Provision for initial working capital & capitalized spares is also made in the estimates. The

summary of project cost break up is provided in table below.

Table 15.1: Project cost break up

Sr. No. Cost Components USD Mn

1 Civil Works 11.79

2 E & M 5.76

O/W Transmission Work 0.29

Total cost without IDC & FC 17.55

3 Indirect Cost 0.13

(a) Total direct & indirect cost 17.68

4 Initial Working capital, capitalized spares 0.27

5 Interest during Construction, Financial Charges 1.41

6 Escalation during construction 1.18

7 Contingency 1.24

8 DSRA Cost loaded upfront 1.20

(b) Total 5.29

9 Total (a) + Total (b) 22.97

10 Capacity 10

11 Cost per MW 2.30

12 Total project cost 22.97

Table 15.2: Construction cost drawdown

Year No. Quarter Construction

Cost

Drawdown

without

Financing cost

Financing Cost Promoter

Equity

Senior

Debt

1 Quarter 1 0.21 0.00 0.21 0.00

1 Quarter 2 0.19 0.00 0.19 0.00

1 Quarter 3 1.19 0.00 1.19 0.00

1 Quarter 4 0.57 0.00 0.57 0.00

Year 1 Total 2.15 0.00 2.15 0.00


Chapter 15 - 3

Year No. Quarter Construction

Cost

Drawdown

without

Financing cost

Financing Cost Promoter

Equity

Senior

Debt

2 Quarter 1 3.53 0.37 3.53 0.37

2 Quarter 2 3.55 0.05 1.20 2.40

2 Quarter 3 1.96 0.09 0.00 2.05

2 Quarter 4 1.33 0.12 0.00 1.45

Year 2 Total 10.37 0.63 4.74 6.27

3 Quarter 1 2.63 0.15 0.00 2.78

3 Quarter 2 1.05 0.18 0.00 1.24

3 Quarter 3 1.60 0.20 0.00 1.80

3 Quarter 4 3.75 0.24 0.00 3.99

Year 3 Total 9.03 0.78 0.00 9.81

Total Construction 21.56 1.41 6.89 16.08

Table 15.3: Debt Repayment Schedule

Debt amount: USD 16.08 Million

Interest rate: 7% (Per annum)

Year Quarter Debt repaid

during period

Interest

expense for

period

Total Debt

Service

Debt

outstanding at

the end of

period

1 i 0.40 0.28 0.68 15.68

ii 0.40 0.27 0.67 15.28

iii 0.40 0.26 0.67 14.87

iv 0.40 0.26 0.66 14.47

2 i 0.40 0.25 0.65 14.07

ii 0.40 0.24 0.64 13.67

iii 0.40 0.24 0.64 13.27

iv 0.40 0.23 0.63 12.86

3 i 0.40 0.22 0.62 12.46

ii 0.40 0.21 0.62 12.06

iii 0.40 0.21 0.61 11.66

iv 0.40 0.20 0.60 11.26

4 i 0.40 0.19 0.60 10.85

ii 0.40 0.19 0.59 10.45

iii 0.40 0.18 0.58 10.05

iv 0.40 0.17 0.57 9.65

5 i 0.40 0.17 0.57 9.25

ii 0.40 0.16 0.56 8.84

iii 0.40 0.15 0.55 8.44

iv 0.40 0.14 0.55 8.04


Chapter 15 - 4

Year Quarter Debt repaid

during period

Interest

expense for

period

Total Debt

Service

Debt

outstanding at

the end of

period

6 i 0.40 0.14 0.54 7.64

ii 0.40 0.13 0.53 7.24

iii 0.40 0.12 0.53 6.83

iv 0.40 0.12 0.52 6.43

7 i 0.40 0.11 0.51 6.03

ii 0.40 0.10 0.50 5.63

iii 0.40 0.09 0.50 5.23

iv 0.40 0.09 0.49 4.82

8 i 0.40 0.08 0.48 4.42

ii 0.40 0.07 0.48 4.02

iii 0.40 0.07 0.47 3.62

iv 0.40 0.06 0.46 3.22

9 i 0.40 0.05 0.45 2.81

ii 0.40 0.05 0.45 2.41

iii 0.40 0.04 0.44 2.01

iv 0.40 0.03 0.43 1.61

10 i 0.40 0.02 0.43 1.21

ii 0.40 0.02 0.42 0.80

iii 0.40 0.01 0.41 0.40

iv 0.40 0.00 0.41 0.00

Key Financial Assumptions

The key assumptions used in the financial analysis are:

1. The debt: equity ratio considered for analysis is 70:30.

2. The interest rate on debt is considered as 7% p.a. The term for repayment of loan is

considered as ten years (post commissioning).

3. The tariff for power is considered as 8 c/kWh, for the life of the project.

4. The initial development period is considered as 12 months, and construction period is

assumed as 24 months.

5. Interest on working capital loan is assumed to be 14% p.a.

6. The capital cost estimates are as per equipment supplier quotes and as per expected costs

for civil works.

7. Power generation is considered as per the 75% dependable year with a 15% overload

when water flow is available.


Chapter 15 - 5

8. O&M cost is considered as 250,000 USD per year for the first year of operation. The cost

is escalated at 4% per year for further years.

9. Life of the project assets is considered as 35 years and depreciation is considered at a

uniform rate over the life of the asset.

10. No income tax holiday is assumed and corporate income tax rate of 30% has been

assumed.

11. Carbon credit benefits are assumed to accrue to the project developer at a rate of 5

USD/CER.

The assumptions used in the financial calculations have been tabulated below:

Table 15.4: Capacity Assumptions

Unit

Installed Capacity MW 10

Maximum overrating % 10.0%

Annual availability of plant % 92.0%

Auxiliary consumption % 0.5%

Transformation Losses % 0.5%

Transmission losses to Interconnection point % 0.0%

Table 15.5: Carbon credit assumptions

Unit

Grid intensity for Kenya t CO2/ MWh 0.78

CER Value USD/ CER 5

Table 15.6: Capital Structure

Unit Mn USD

Equity + Quasi Equity 30% 6.89

Debt 70% 16.1

Debt Assumptions

Type

Local

Currency

USD

Facility Amount Mn USD 16.08

Interest rate % per annum 7.0%

Commitment fee % per annum 1.0%

Upfront fee % 2.0%


Chapter 15 - 6

Unit Mn USD

Tenor (post construction) Years 10

Moratorium (post construction) Years 0

Table 15.7: Construction Cost Escalation

Unit

Escalation during construction % per annum 3.21%

Monthly escalation factor % per month 0.26%

Timelines Unit Total

Development Period months 12 12

Construction Period months 24 36

Operation Period years 20

Table 15.8: Power potential at 100% availability

MU at 100% availability Base PLF

With

overloading

90% Dependable Year 54.55 62.28% 64.21%

75% Dependable Year 52.95 60.45% 62.18%

50% Dependable Year 62.18 70.98% 75.43%

Selected PLF 62.18%

Table 15.9: Weighted average cost of capital (WACC)

Cost of equity (weighted) 16.00%

Cost of debt 7.00%

WACC for discount rate 8.23%

Table 15.10: Operating Expenditure

Unit

Operating Expenditure

USD Million per

year 0.25

Escalation of O&M % per year 4.00%

Interest on Working capital % per annum 14.00%

Table 15.11: Working capital sizing

Unit

Number of months of O&M Days 30

Number of months of receivables Days 60

Spares as a % of R&M expenses % 15.0%

Rebate on prompt payment of bills % 0.0%

Corporate Income tax rate % 30.0%

Income tax holiday years 0.0


Chapter 15 - 7

Carbon credit income

It is estimated that Sagana III HEP (10 MW) will export around 54 million units of energy,

which will result in an emission reduction of ~38,690 tons of CO2, and generation of equivalent

number of CERs. At an assumed selling price of USD 5 per CER, this will result in an income of

around 145,120 USD (assuming 75% share for the project developer).

Table 15.12: Financial Parameters - With & without CER income

Sr. no. Particulars With CERs Without

CERs

1 Equity IRR (%) 16.12% 14.83%

2 Project Payback period Years 9 9

3 Debt service coverage ratio Avg. DSCR 1.54x 1.50x

4 Minimum DSCR Min DSCR 1.41x 1.36x

The CER income will help in increasing the average DSCR to 1.54x form 1.50x (without CER).

Table 15.13: Calculation for carbon credit benefits

Sr. No. Particulars Unit

1 Net Energy exported MWh 49,614

2 Grid carbon intensity factor t CO2 / MWh 0.78

3 Emission Reduction # of CER 38,699

4 Rate USD/CER 5

5 Revenue USD 145,120

Sensitivity Analysis

Sensitivity of the financial results with respect to key input variables has been analyzed in detail

and the results have been included in this report. The various cases (including the base case) that

have been considered for sensitivity analysis are included in Table 15.14 below. The results of

the sensitivity cases are included in Table 15.15. Results indicate that financial parameters like

DSCR have sufficient cushion to absorb negative effects of input variables.


Chapter 15 - 8

Table 15.14: Sensitivity Analysis cases

Sr No Case Description

0 Base Case - Base assumptions

1 Case 1 - Increase in Capital Cost Capital Cost increased by 5% above base case assumption

2 Case 2 - Increase in Capital Cost Capital Cost increased by 10% above base case assumption

3 Case 3 - Decrease in Annual Plant Availability Plant availability lower than base case by 5 percentage points

4 Case 4 - Decrease in Annual Plant Availability Plant availability lower than base case by 8 percentage points

5 Case 5 - Increase in O&M cost O&M cost higher than base case by 5%

6 Case 6 - Increase in O&M cost O&M cost higher than base case by 10%

7 Case 7 - Lower Hydrology Hydrology lower than base case by 5%

8 Case 8 - Lower Hydrology Hydrology lower than base case by 10%

9 Case 9 - Drought years Every fifth (5th) year is a drought year

10 Case 10 - Higher inflation Inflation rate 5 percentage points higher than base case

11 Case 11 - Spare [Spare]

12 Case 12 - Lower number of carbon credits Number of Carbon Credits lower than base case by 10 %

13 Case 13 - Lower price for carbon credits Price for Carbon Credits lower than base case by 10 %

14 Case 14 - Increase in construction period Increase in construction period by 12 months

15 Case 15 - Spare [Spare]

16 Case 16 - Combined downside Case A Lower annual availability by 5 percentage points, O&M cost higher

than base case by 5%, Power potential lower than base case by 5

percentage points, Increase in construction period by 12 months

17 Case 17 - Combined downside Case B Capital Cost increased by 5% above base case assumption, Hydrology

lower than base case by 10%

18 Case 18 - Combined downside Case C Lower annual availability by 5 percentage points, Increase in

construction period by 12 months


Chapter 15 - 9

Table 15.15: Results of Sensitivity analysis

Sr.

No

Case Run Project

Cost,

Million

USD

Equity,

Million

USD

Senior

Debt,

Million

USD

Generation,

MU

Levelized

cost, US

c/KWh

Min.

DSCR

Senior

Debt

Avg.

DSCR

Senior

Debt

0 Base Case - No Change 22.97 6.9 16.1 49.61 5.08 1.41 1.54

1 Case 1 - Increase in Capital Cost by 5 % 24.05 7.9 16.2 49.61 5.04 1.41 1.55

2 Case 2 - Increase in Capital Cost by 10 % 25.14 9.0 16.2 49.61 4.98 1.41 1.57

3 Case 3 - Decrease in Annual Plant

Availability by 5 percentage points 22.97 6.9 16.1 46.92 5.20 1.33 1.48

4 Case 4 - Decrease in Annual Plant

Availability by 8 percentage points 22.97 6.9 16.1 45.30 5.28 1.28 1.44

5 Case 5 - Increase in Base operating cost by 5

% 22.97 6.9 16.1 49.61 5.11 1.41 1.53

6 Case 6 - Increase in Base operating cost by

10 % 22.97 6.9 16.1 49.61 5.13 1.40 1.53

7 Case 7 - Lower Hydrology by 5 % 22.97 6.9 16.1 47.13 5.19 1.34 1.48

8 Case 8 - Lower Hydrology by 10 % 22.97 6.9 16.1 44.65 5.30 1.26 1.43

9 Case 9 - Bad year every five years (10 % less

water) 22.97 6.9 16.1 49.61 5.17 1.28 1.49

10 Case 10 - Higher inflation by 5 % points 22.97 6.9 16.1 49.61 5.11 1.41 1.53

11 Case 11 - [Spare} 22.97 6.9 16.1 49.61 5.08 1.41 1.54

12 Case 12 - Lower number of carbon credits by

10 % 22.97 6.9 16.1 49.61 5.07 1.41 1.53

13 Case 13 - Lower price for carbon credits by

10 % 22.97 6.9 16.1 49.61 5.07 1.41 1.53

14 Case 14 - Increase in construction period by

12 months 24.10 7.9 16.2 49.61 5.05 1.40 1.55

15 Case 15 - Spare 22.97 6.9 16.1 49.61 5.08 1.41 1.54

16 Case 16 - Combined downside Case A 24.10 7.9 16.2 47.13 5.17 1.32 1.49

17 Case 17 - Combined downside Case B 24.05 7.9 16.2 44.65 5.21 1.26 1.46

18 Case 18 - Combined downside Case C 24.10 7.9 16.2 46.92 5.15 1.32 1.50


Chapter 15 - 10

Annexure 1 Financial Statements

Balance Sheet

Profit & Loss Account

Cash Flow Statement

Cost of Power Generation

Financial Ratios


Chapter 15 - 11

Balance Sheet

Operation Year Ending 1 2 3 4 5 6 7 8 9 10

Current Assets

Cash Balance 0.28 - - - - - - - - 0.24

DSRA 0.66 0.63 0.60 0.57 0.55 0.52 0.49 0.46 0.43 -

Accounts receivable 0.34 0.34 0.34 0.34 0.34 0.34 0.34 0.34 0.34 0.34

Total 1.28 0.97 0.94 0.91 0.88 0.86 0.83 0.80 0.77 0.57

Fixed Assets 19.54 18.72 17.90 17.08 16.26 15.44 14.62 13.81 12.99 12.17

Capitalized financing costs 1.31 1.21 1.12 1.02 0.92 0.82 0.72 0.62 0.52 0.42

Total 20.85 19.93 19.02 18.10 17.18 16.26 15.34 14.43 13.51 12.59

Work In Progress - - - - - - - - - -

Total Assets 22.13 20.90 19.96 19.01 18.06 17.12 16.17 15.22 14.28 13.17

Current Liabilities

Accounts payable 0.05 0.05 0.05 0.05 0.06 0.06 0.06 0.06 0.07 0.07

Taxes payable - - - - - - - - - -

Total 0.05 0.05 0.05 0.05 0.06 0.06 0.06 0.06 0.07 0.07

Long term Liabilities 14.47 12.86 11.26 9.65 8.04 6.43 4.82 3.22 1.61 -

Working Capital Facility 0.29 0.29 0.29 0.28 0.28 0.28 0.28 0.28 0.27 0.27

Shareholders' Funds

Promoter Equity 6.89 6.89 6.89 6.89 6.89 6.89 6.89 6.89 6.89 6.89

Retained Earnings 0.43 0.81 1.47 2.14 2.80 3.46 4.12 4.78 5.44 5.94

Total 7.32 7.70 8.36 9.03 9.69 10.35 11.01 11.67 12.33 12.83

Total Liabilities 22.13 20.90 19.96 19.01 18.06 17.12 16.17 15.22 14.28 13.17


Chapter 15 - 12

Balance Sheet

Operation Year Ending 11 12 13 14 15 16 17 18 19 20

Current Assets

Cash Balance 1.08 1.91 2.75 3.59 4.36 5.10 5.84 6.58 7.32 -

DSRA - - - - - - - - - -

Accounts receivable 0.34 0.34 0.34 0.34 0.34 0.34 0.34 0.34 0.34 0.34

Total 1.41 2.25 3.09 3.93 4.70 5.44 6.18 6.92 7.66 0.34

Fixed Assets 11.43 10.69 9.95 9.21 8.47 7.73 6.99 6.25 5.51 4.77

Capitalized financing costs 0.32 0.23 0.13 0.03 - - - - - -

Total 11.75 10.91 10.07 9.24 8.47 7.73 6.99 6.25 5.51 4.77

Work In Progress - - - - - - - - - -

Total Assets 13.17 13.17 13.17 13.17 13.17 13.17 13.17 13.17 13.17 5.10

Current Liabilities

Accounts payable 0.07 0.07 0.08 0.08 0.08 0.09 0.09 0.09 0.10 0.10

Taxes payable - - - - - - - - - -

Total 0.07 0.07 0.08 0.08 0.08 0.09 0.09 0.09 0.10 0.10

Long term Liabilities - - - - - - - - - -

Working Capital Facility 0.27 0.26 0.26 0.26 0.26 0.25 0.25 0.25 0.24 -

Shareholders' Funds

Promoter Equity 6.89 6.89 6.89 6.89 6.89 6.89 6.89 6.89 6.89 6.89

Retained Earnings 5.94 5.94 5.94 5.94 5.94 5.94 5.94 5.94 5.94 (1.89)

Total 12.83 12.83 12.83 12.83 12.83 12.83 12.83 12.83 12.83 5.00

Total Liabilities 13.17 13.17 13.17 13.17 13.17 13.17 13.17 13.17 13.17 5.10


Chapter 15 - 13

Profit & Loss Statement

Operational Year 1 2 3 4 5 6 7 8 9 10

Revenue from power sales 3.97 3.97 3.98 3.97 3.97 3.97 3.98 3.97 3.97 3.97

Revenue from CDM 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15

Total Revenue 4.11 4.11 4.13 4.11 4.11 4.11 4.13 4.11 4.11 4.11

Total O&M Cost 0.29 0.30 0.31 0.32 0.34 0.35 0.36 0.38 0.39 0.41

EBITDA 3.83 3.82 3.82 3.79 3.78 3.77 3.76 3.74 3.72 3.71

EBITDA as a % of Revenue 93% 93% 92% 92% 92% 92% 91% 91% 90% 90%

Depreciation expense 0.82 0.82 0.82 0.82 0.82 0.82 0.82 0.82 0.82 0.82

Amortization expense 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10

Depreciation + Amortization 0.92 0.92 0.92 0.92 0.92 0.92 0.92 0.92 0.92 0.92

EBIT 2.91 2.90 2.90 2.87 2.86 2.85 2.84 2.82 2.80 2.79

Interest expense (Senior-Debt) 1.10 0.98 0.87 0.76 0.64 0.53 0.41 0.30 0.19 0.07

Interest payments on working capital 0.03 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04

Total Interest paid 1.13 1.03 0.91 0.80 0.68 0.57 0.45 0.34 0.22 0.11

Profit before Tax 1.78 1.87 1.98 2.08 2.18 2.28 2.39 2.48 2.58 2.68

Tax - - - 0.25 0.44 0.54 0.63 0.71 0.79 0.85

Profit after tax 1.78 1.87 1.98 1.83 1.74 1.74 1.76 1.77 1.79 1.83

Profit margin 43% 46% 48% 44% 42% 42% 43% 43% 44% 44%


Chapter 15 - 14

Profit & Loss Statement


Revenue from power sales 3.98 3.97 3.97 3.97 3.98 3.97 3.97 3.97 3.98 3.97

Revenue from CDM 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15

Total Revenue 4.13 4.11 4.11 4.11 4.13 4.11 4.11 4.11 4.13 4.11

Total O&M Cost 0.43 0.44 0.46 0.48 0.50 0.52 0.54 0.56 0.59 0.61

EBITDA 3.70 3.67 3.65 3.63 3.63 3.59 3.57 3.55 3.54 3.51

EBITDA as a % of Revenue 90% 89% 89% 88% 88% 87% 87% 86% 86% 85%

Depreciation expense 0.74 0.74 0.74 0.74 0.74 0.74 0.74 0.74 0.74 0.74

Amortization expense 0.10 0.10 0.10 0.10 0.03 - - - - -

Depreciation + Amortization 0.84 0.84 0.84 0.84 0.77 0.74 0.74 0.74 0.74 0.74

EBIT 2.86 2.83 2.81 2.80 2.86 2.85 2.83 2.81 2.80 2.76

Interest expense (Senior-Debt) - - - - - - - - - -

Interest payments on working capital 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.03 0.03

Total Interest paid 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.03 0.03

Profit before Tax 2.82 2.79 2.78 2.76 2.82 2.82 2.80 2.78 2.77 2.73

Tax 0.90 0.92 0.94 0.95 0.97 0.97 0.98 0.99 0.99 0.99

Profit after tax 1.92 1.87 1.84 1.80 1.85 1.84 1.82 1.79 1.77 1.74

Profit margin 47% 46% 45% 44% 45% 45% 44% 44% 43% 42%


Chapter 15 - 15

Cash Flow Statement


Cash beginning balance 0.44 0.72 0.44 0.44 0.44 0.44 0.44 0.44 0.44 0.44

EBIDTA 3.83 3.82 3.82 3.79 3.78 3.77 3.76 3.74 3.72 3.71

Tax paid - - - (0.25) (0.44) (0.54) (0.63) (0.71) (0.79) (0.85)

Total 4.27 4.54 4.26 3.99 3.78 3.67 3.57 3.47 3.38 3.30

Net Working Capital

Working capital Revenue side 1.35 1.35 1.35 1.35 1.35 1.35 1.35 1.35 1.35 1.35

Working capital cost side 0.19 0.20 0.20 0.21 0.22 0.23 0.24 0.25 0.26 0.27

Net Working Capital 1.16 1.16 1.15 1.14 1.13 1.12 1.11 1.10 1.09 1.08

Change in Working Capital (0.29) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Working Capital financing 0.29 (0.00) (0.00) (0.00) (0.00) (0.00) (0.00) (0.00) (0.00) (0.00)

Debt repayment

Interest on Senior Debt 1.10 0.98 0.87 0.76 0.64 0.53 0.41 0.30 0.19 0.07

Interest on working Capital 0.03 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04

Actual Principal repayment (Senior Debt) 1.61 1.61 1.61 1.61 1.61 1.61 1.61 1.61 1.61 1.61

Total Debt Service (Senior Debt) 2.71 2.59 2.48 2.36 2.25 2.14 2.02 1.91 1.79 1.68

Cash flow after debt repayment 1.53 1.91 1.74 1.58 1.49 1.49 1.51 1.52 1.55 1.58

Cash flow (in to) out of DSRA 0.54 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.43

Cash available for equity holders 2.07 1.93 1.77 1.61 1.52 1.52 1.54 1.55 1.58 2.01

Dividend paid 1.35 1.49 1.32 1.17 1.08 1.08 1.09 1.11 1.13 1.33

Cash ending balance 0.72 0.44 0.44 0.44 0.44 0.44 0.44 0.44 0.44 0.68


Chapter 15 - 16

Cash Flow Statement


Cash beginning balance 0.68 1.52 2.36 3.20 4.04 4.80 5.54 6.29 7.03 7.77

EBIDTA 3.70 3.67 3.65 3.63 3.63 3.59 3.57 3.55 3.54 3.51

Tax paid (0.90) (0.92) (0.94) (0.95) (0.97) (0.97) (0.98) (0.99) (0.99) (0.99)

Total 3.48 4.27 5.07 5.88 6.69 7.42 8.14 8.85 9.57 10.28

Net Working Capital

Working capital Revenue side 1.35 1.35 1.35 1.35 1.35 1.35 1.35 1.35 1.35 1.35

Working capital cost side 0.28 0.29 0.30 0.32 0.33 0.34 0.36 0.37 0.38 0.40

Net Working Capital 1.07 1.06 1.05 1.04 1.03 1.01 1.00 0.98 0.97 0.95

Change in Working Capital 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Working Capital financing (0.00) (0.00) (0.00) (0.00) (0.00) (0.00) (0.00) (0.00) (0.00) (0.24)

Debt repayment

Interest on Senior Debt - - - - - - - - - -

Interest on working Capital 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.03 0.03

Actual Principal repayment (Senior Debt) - - - - - - - - - -

Total Debt Service (Senior Debt) - - - - - - - - - -

Cash flow after debt repayment 3.44 4.23 5.03 5.84 6.66 7.39 8.10 8.82 9.54 10.01

Cash flow (in to) out of DSRA - - - - - - - - - -

Cash available for equity holders 3.44 4.23 5.03 5.84 6.66 7.39 8.10 8.82 9.54 10.01

Dividend paid 1.92 1.87 1.84 1.80 1.85 1.84 1.82 1.79 1.77 9.57

Cash ending balance 1.52 2.36 3.20 4.04 4.80 5.54 6.29 7.03 7.77 0.44


Chapter 15 - 17

Cost of Power Generation

Op. year 1 2 3 4 5 6 7 8 9 10

Cost of Power in US c/KWh

O&M Cost

0.60 0.62 0.65 0.68 0.70 0.73 0.76 0.79 0.82 0.60

Interest

2.07 1.84 1.61 1.37 1.14 0.91 0.68 0.45 0.22 2.07

Tax

- - 0.50 0.89 1.09 1.28 1.44 1.58 1.72 -

Principal

3.24 3.23 3.24 3.24 3.24 3.23 3.24 3.24 3.24 3.24

Total

5.91 5.69 6.00 6.18 6.18 6.15 6.12 6.07 6.00 5.91

Levelized Cost over 20 years in US

c/KWh 5.08

Discount rate for levelization 8.23%

Period of levelization 20.00

Contribution US c/ KWh

2.38 2.60 2.30 2.11 2.11 2.14 2.17 2.22 2.29 2.38

Op. year 11 12 13 14 15 16 17 18 19 20

Cost of Power in US c/KWh

O&M Cost

0.86 0.89 0.93 0.97 1.00 1.05 1.09 1.13 1.18 1.23

Interest

0.08 0.08 0.08 0.07 0.07 0.07 0.07 0.07 0.07 0.07

Tax

1.82 1.86 1.90 1.92 1.95 1.97 1.98 1.99 1.99 1.99

Principal

- - - - - - - - - -

Total

2.75 2.83 2.90 2.97 3.03 3.08 3.14 3.19 3.24 3.29

Levelized Cost over 20 years in US

c/KWh 5.08

Discount rate for levelization 8.23%

Period of levelization 20.00

Contribution US c/ KWh

5.54 5.46 5.39 5.33 5.27 5.21 5.15 5.10 5.05 5.00


Chapter 15 - 18

Debt Service Coverage ratio

Op. year 1 2 3 4 5 6 7 8 9 10

EBITDA MM USD 3.82 3.82 3.79 3.78 3.77 3.76 3.74 3.72 3.71 3.82

EBITDA Margin % 92.77% 92.49% 92.17% 91.85% 91.52% 91.20% 90.82% 90.44% 90.06% 92.77%

Tax MM USD - - (0.25) (0.44) (0.54) (0.63) (0.71) (0.79) (0.85) -

Net Profit MM USD 1.87 1.98 1.83 1.74 1.74 1.76 1.77 1.79 1.83 1.87

Total Principal

Payment MM USD 1.61 1.61 1.61 1.61 1.61 1.61 1.61 1.61 1.61 1.61

Interest on Senior-debt MM USD 0.98 0.87 0.76 0.64 0.53 0.41 0.30 0.19 0.07 0.98

Total Debt service

(Senior-debt) MM USD 2.59 2.48 2.36 2.25 2.14 2.02 1.91 1.79 1.68 2.59

DSCR (Senior Debt)

1.47x 1.54x 1.50x 1.48x 1.51x 1.55x 1.59x 1.64x 1.70x 1.47x

DSCR (Average) 1.54x

DSCR (Min) 1.41x

Detailed Project Report Sagana III HEP Appendix I - Photographs

Appendix I - 1

Appendix I- Photographs


Appendix I - 2

Site for intake (Diversion Structure)

Slope for Water Conductor (channel)

Location for

Diversion

Structure on the

right bank

Slope for Water conductor channel


Appendix I - 3

Slope for proposed Penstock

Rocky strata near proposed Power House

Penstock Alignment on right bank

Rocky strata just before Power house (on right bank)


Appendix I - 4

Bench on Right bank for Power house

Road connectivity to power house location

Location of Power house bench on Right Bank


Appendix I - 5

Image 1: Project area on Toposheet (135/1)

Project Area Sagana III HEP (10 MW)

Detailed Project Report Sagana III HEP Appendix II - Drawings

Appendix II - 1

Appendix II- Drawings

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