aepc guidelines for detailed feasibility study for projects

8/13/2019 AEPC Guidelines for Detailed Feasibility Study for Projects

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Mini-Grid Support Programme (MGSP)

Alternative Energy Promotion Center

Energy Sector Assistance Programme (AEPC/ESAP)

GUIDELINES FOR DETAILED FEASIBILITYSTUDY FOR PROJECTS FROM 100 kW TO1000kW

Version-1

Date: 18, 11, 2008


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Guidelines: Detailed Feasibility Study of Mini Hydropower Projects ranging from 100kW to 1MW

Alternative Energy Promotion Center/ Energy Sector Assistance Program Page 1

ABBREVIATIONS ................................................................................................................... 51. INTRODUCTION ............................................................................................................. 7

1.1 General ................................................................................................................................. 71.2 Objective and scope of works ............................................................................................. 71.3 Feasibility Study .................................................................................................................. 81.4 Application of Guidelines and content ............................................................................... 81.5 Hydropower development and the private sector ............................................................. 9

2. PROJECT DEVELOPMENT OPPORTUNITIES........................................................ 102.1 General ............................................................................................................................... 102.2 Components of a Mini Hydro Project .............................................................................. 102.3 Function of the Mini Hydro Components ....................................................................... 112.4 Power Market .................................................................................................................... 122.5 Alternatives of Supply ....................................................................................................... 132.6 Institutional Aspects .......................................................................................................... 142.7 Policy issues ........................................................................................................................ 14

2.7.1 Application Process under Electricity Act .................................................................................... 142.7.2 Government Policy ................................................................................................................. ...... 15

2.8 Opportunity of Integrated Use of Water resources ........................................................ 153. SURVEY AND INVESTIGATIONS .............................................................................. 17

3.1 General ............................................................................................................................... 173.2 Approach & Methodology ................................................................................................ 173.2.1 Site Selection of Project Components .............................................................. ............................. 17

3.2.2 Topographic Survey and Mapping ................................................................... ............................. 233.2.2.1 Available Maps and Survey Equipment........................................................................................ 233.2.2.2 Topographical Survey...................................................................................................................... 233.2.2.3 Mapping and Plotting ....................................................................................................................... 253.2.2.4 Site Photographs .............................................................................................................................. 26

3.2.3 Hydrological Investigation ........................................................................................................... 263.2.3.1 General .............................................................................................................................................. 263.2.3.2 Flow Estimation Method .................................................................................................................. 273.2.3.3 Stream flow measurement .............................................................................................................. 283.2.3.4 Flow Duration Curve (FDC) ............................................................................................................ 34

3.2.4 Geology and Geotechnical Study ..................................................................... ............................. 373.2.4.1 General .............................................................................................................................................. 373.2.4.2 Regional Geological Study.............................................................................................................. 373.2.4.3 Geology and Geomorphology of the Project Site/ Area..................... ......................... ................ 383.2.4.4 Construction Material Survey ......................................................................................................... 413.2.4.5 Geological Problems........................................................................................................................ 423.2.4.6 Conclusion and Recommendations............................................................................................... 43

3.3 Socio-economic Aspects ..................................................................................................... 433.3.1 Introduction................................................................................................................................... 433.3.2 Data/Information Requirement ............................................................................................... ...... 433.3.3 Methodology ................................................................. ................................................................ 443.3.4 Community Benefit Assessment ...................................................................... ............................. 47

3.4 Environmental Considerations ......................................................................................... 494.

TECHNICAL DESIGN AND ANALYSIS ..................................................................... 56

4.1 General Features of Hydropower Projects...................................................................... 56


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4.2 Civil Works ........................................................................................................................ 574.2.1 Planning and Layout of Diversion Headworks ............................................................................. 57

4.2.1.1 General .............................................................................................................................................. 574.2.1.2 Objectives .......................................................................................................................................... 574.2.1.3 Scope ................................................................................................................................................. 574.2.1.4 Data requirements............................................................................................................................ 57

4.2.2 Diversion Weir .............................................................. ................................................................ 584.2.2.1 Temporary Weir ................................................................................................................................ 584.2.2.2 Semi Permanent Weir ..................................................................................................................... 584.2.2.3 Permanent weir ................................................................................................................................ 594.2.2.4 Hydraulic Design .............................................................................................................................. 59

4.2.3 Undersluice .................................................................... ............................................................... 604.2.3.1 General .............................................................................................................................................. 604.2.3.2 Hydraulic Design .............................................................................................................................. 60

4.2.4 Intake ............................................................................................................................................ 604.2.4.1 General .............................................................................................................................................. 604.2.4.2 Scope of design ................................................................................................................................ 614.2.4.3 Typical Components ........................................................................................................................ 624.2.4.4 Hydraulic Design .............................................................................................................................. 62

4.2.5 Gravel Trap ............................................................................................................................. ...... 654.2.5.1 General .............................................................................................................................................. 654.2.5.2 Purpose ............................................................................................................................................. 664.2.5.3 Design Principal & Criteria .............................................................................................................. 664.2.5.4 Design Formula for Gravel Trap..................................................................................................... 66

4.2.6 Settling Basin ................................................................ ................................................................ 674.2.6.1 Purpose ............................................................................................................................................. 674.2.6.2 Design Principal & Criteria .............................................................................................................. 674.2.6.3 Typical Components ........................................................................................................................ 674.2.6.4 Design of Settling Basin .................................................................................................................. 684.2.6.5 Design of Inlet Transition ................................................................................................................ 684.2.6.6 Design of Settling Chamber............................................................................................................ 694.2.6.7 Settling Basin Design....................................................................................................................... 704.2.6.8 Outlet Zone ....................................................................................................................................... 714.2.6.9 Sediment Flushing System ............................................................................................................. 714.2.6.10 Types of Settling Basin based on flushing operations................................................................ 72

4.2.7 Water Conveyance System - Part I :Canal ................................................................... ................. 724.2.7.1 Introduction ....................................................................................................................................... 724.2.7.2 Components of Conveyance System............................................................................................ 734.2.7.3 Approach Canal ................................................................................................................................ 734.2.7.4 Headrace Canal................................................................................................................................ 744.2.7.5 Basic Design Criteria ....................................................................................................................... 744.2.7.6 Hydraulic Calculation of Free flow Canal...................................................................................... 744.2.7.7 Geometry of Channel Sections ...................................................................................................... 754.2.7.8 Transitions in canal .......................................................................................................................... 764.2.7.9 Head Losses in canal ...................................................................................................................... 764.2.7.10 Permissible Velocity in the canal.................................................................................................... 784.2.7.11 Free Board in lined and Unlined Canal......................................................................................... 794.2.7.12 Canal Lining ...................................................................................................................................... 79

4.2.8 Water Conveyance System - Part II : Pipe ................................................................... ................. 804.2.8.1 Pipe Flow ........................................................................................................................................... 804.2.8.2 Headrace Pipe .................................................................................................................................. 804.2.8.3 Design Considerations for headrace pipe...................... ........................ ......................... .............. 814.2.8.4 Hydraulic Design .............................................................................................................................. 814.2.8.5 Pipe Diameter Optimization............................................................................................................ 834.2.8.6 Economic Diameter and Shell Thickness..................................................................................... 834.2.8.7 Head loss in pipe flow...................................................................................................................... 83

4.2.9 Forebay ............................................................. ...................................................................... ...... 844.2.10 Powerhouse .............................................................. ................................................................ 844.2.11 Tailrace Canal ........................................................................................................ .................. 87

4.3 Hydro-mechanical Equipment ......................................................................................... 874.3.1 Penstock ............................................................ ...................................................................... ...... 87

4.3.1.1 General .............................................................................................................................................. 874.3.1.2 Type of installation ........................................................................................................................... 884.3.1.3 Conditions governing the adoption of a Pipeline......................................................................... 894.3.1.4 Hydraulic Design .............................................................................................................................. 89


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4.3.1.5 Structural Design .............................................................................................................................. 914.3.1.6 Expansion Joints .............................................................................................................................. 934.3.1.7 Branch Pipe....................................................................................................................................... 94

4.3.2 Gates, Stoplogs and trashracks ..................................................................................................... 944.3.2.1 General .............................................................................................................................................. 944.3.2.2 Gates .................................................................................................................................................. 944.3.2.3 Stoplogs ............................................................................................................................................. 944.3.2.4 Trashracks......................................................................................................................................... 94

4.4 Powerhouse Mechanical Equipment ................................................................................ 964.4.1 Introduction or general outline.................................................. .................................................... 964.4.2 Turbine Type Selection ............................................................. .................................................... 964.4.3 Unit Selection ............................................................................................................................... 974.4.4 Turbine Speed ......................................................................................................................... ...... 984.4.5 General Efficiency Trend ..................................................................... ....................................... 1004.4.6 Design Criteria .............................................................. .............................................................. 1004.4.7 Description of Equipment ....................................................................................................... .... 100

4.4.7.1 Turbines ........................................................................................................................................... 1004.4.7.2 Governors ........................................................................................................................................ 1034.4.7.3 Inlet Valves...................................................................................................................................... 1054.4.7.4 Drive System (Speed Increaser).................................................................................................. 1054.4.7.5 Other Accessories and Equipment.............................................................................................. 106

4.5 Electrical Components .................................................................................................... 1064.5.1 Generator .................................................................................................................................... 106

4.5.1.1 Types and Selection ...................................................................................................................... 1064.5.1.2 Generator capacity and power output rating.............................................................................. 1074.5.1.3 Generator voltage........................................................................................................................... 1084.5.1.4 Generator Speed............................................................................................................................ 1084.5.1.5 Insulation and temperature rise.................................................................................................... 1084.5.1.6 Excitation System........................................................................................................................... 1084.5.1.7 Generator Neutral Grounding....................................................................................................... 109

4.5.2 Transformers ................................................................. .............................................................. 1094.5.2.1 Generator Transformer.................................................................................................................. 1094.5.2.2 Station Transformer ....................................................................................................................... 110

4.5.3 Switchgear equipment................................................................................................................. 1104.5.3.1 Circuit breakers and isolators....................................................................................................... 1114.5.3.2 Surge Arresters .............................................................................................................................. 112

4.5.4 Control and Protection Systems ........................................................... ....................................... 1124.5.4.1 Control system................................................................................................................................ 1124.5.4.2 Protection Systems ........................................................................................................................ 113

4.5.5 System Grounding ...................................................................................................................... 1144.5.6 DC power supply ............................................................................................. ........................... 1154.5.7 Lighting system .......................................................................................................................... 115

4.5.7.1 Normal AC lighting system............................................................................................................ 1164.5.7.2 Emergency DC lighting system.................................................................................................... 116

4.5.8 Communication System ............................................................ .................................................. 1164.5.9 Modes of Mini hydropower station operation ............................................................. ................ 116

4.5.9.1 Isolated Mode ................................................................................................................................. 1164.5.9.2 Interconnection with grid ............................................................................................................... 116

4.6 Transmission and Distribution ....................................................................................... 1195. POWER AND ENERGY ............................................................................................... 124

5.1 Introduction ..................................................................................................................... 1245.2 Methodology ..................................................................................................................... 1245.3 Outage ............................................................................................................................... 1245.4 Input Data ........................................................................................................................ 1245.5 Results of the Study ......................................................................................................... 125

6. PROJECT CAPACITY OPTIMIZATION ................................................................... 1266.1 General ............................................................................................................................. 126


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7. Project Cost Estimate .................................................................................................... 1287.1 Introduction ..................................................................................................................... 1287.2 Assumptions ..................................................................................................................... 1287.3 General Methodology ...................................................................................................... 1287.4 Cost Estimate of Civil Works ......................................................................................... 1297.5 Unit Rates/ Unit Prices .................................................................................................... 129

7.5.1 Labour Costs ................................................................. .............................................................. 1297.5.2 Cost of Equipment tools and Plants ............................................................................................ 1307.5.3 Cost of Construction Material .............................................................. ....................................... 1307.5.4 Overhead and profit ......................................................................................... ........................... 130

7.6 Cost components .............................................................................................................. 1307.6.1 Land and Support ...................................................................... .................................................. 1307.6.2 Pre-operating expenses ............................................................................................... ................ 1307.6.3 Main Civil works ................................................................................. ....................................... 1317.6.4 Hydro mechanical works ................................................................................. ........................... 1317.6.5 Electrical and Mechanical Equipment ............................................................ ............................ 1317.6.6 Transmission Line ...................................................................................................................... 1327.6.7 Value Added Tax (VAT) ................................................................................. ........................... 1327.6.8 Contingencies ............................................................................................................................. 1327.6.9 Interest During Construction (IDC) ................................................................ ............................ 1327.6.10 Annual operation and Maintenance Cost ............................................................... ................ 132

7.7 Project Cost ..................................................................................................................... 1338. CONSTRUCTION PLANNING AND SCHEDULING .............................................. 134

9. Financial Analysis ........................................................................................................ 1369.1 General ............................................................................................................................. 1369.2 General Assumptions ...................................................................................................... 1369.3 Financial Analysis Spread Sheet Model ........................................................................ 1379.4 Results of Financial Analysis: ......................................................................................... 1399.5 Sensitivity Analysis .......................................................................................................... 139

10. Risk Assessment ........................................................................................................ 14010.1 General ............................................................................................................................. 14010.2 Financial Risk .................................................................................................................. 14010.3 Hydrological Risk ............................................................................................................ 14110.4 Construction Risk ............................................................................................................ 14110.5 Other Risks ....................................................................................................................... 141

11. Feasibility Report Standard ...................................................................................... 14312. Glossary ..................................................................................................................... 149

12.1 Electricity Glossary ......................................................................................................... 14912.2 Hydropower glossary ...................................................................................................... 15512.3 Lighting glossary ............................................................................................................. 15812.4 Power System Terms ....................................................................................................... 161


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ABBREVIATIONS

AC Alternating Current

ACSR Aluminium Conductor Steel Reinforced

AEPC Alternative Energy Promotion Centre

amp Ampere

AVR Automatic Voltage Regulator

B/C Benefit Cost Ratio

BM Bench Marks

CAR Catchment Area Ratio

CFUG Community Forest Users' Group

CT Current Transformer

DC Direct Current

DDC District Development Committee

DHM Department of Hydrology and Meteorology

DoED Department of Electricity Development

DWRC District Water Resources Committee

EIA Environmental Impact Assessment

ELC Electric Load Controller

ESAP Energy Sector Assistance Programme

FDC Flow Duration Curve

FGD Focus Group Discussion

GoN Government of Nepal

GPS Global Positioning System

GRP Glass Reinforced Pipe

HDPP High Density Polythene Pipe

HFL High Flood Level

HH House hold

HP Hydropower

HSC Hydrological Similar Catchment

Hz Hertz

ICIMOD International Center for Integrated Mountain Development

IEE Initial Environmental Examination

INGO International Non-Governmental Organization

INPS Integrated Nepal Power System

IPP Independent Power Producer

IRR Internal Rate of Return


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km Kilometer

kVA Kilo-Volt ampere

kW Kilo Watt

kwh Kilo-Watt hour

l/s Litre per second

m Metre

m3/s Cubic meter per second

MCB Miniature Circuit Breaker

MCCB Moulded Case Circuit Breaker

MGSP Mini-Grid Support Program

MIP Medium Irrigation Project

mm Milli-metre

MoEST Ministry of Environment, Science and Technology

MoWR Ministry of Water Resources

MW Mega Watt

NEA Nepal Electricity Authority

NGO Non-Governmental Organization

NPV Net Present Value

PPA Power Purchase Agreement

PT Potential Transformer

RCC Reinforced Cement Concrete

RL Reduced Level

VDC Village Development Committee

WECS Water and Energy Commission Secretariat


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1. INTRODUCTION

1.1 General

Nepal has good hydropower potentials for generating electricity. However, harnessing

of these potentials has been minimum and about 60% of the population does not have

access to electricity. Some of the reasons are-i) shortage of funds for grid extension ii)Economic unfeasibility in extending transmission line from existing electricity grids to

remote villages and most importantly iii) Power and energy shortage being faced by

Nepals power system which at present cannot meet the supply of ever increasing

power demand. In this backdrop, The Government of Nepal (GoN) has policies to

develop hydropower projects of various capacities in the country, both on grid and off

gird. In line with this GoN policy, Alternative Energy Promotion Centre (AEPC) is

promoting rural electrification program through the development of micro and mini-

hydro projects in remote areas of the country through local entrepreneurs/ community.

The AEPC has already developed a well-defined guideline for Detailed Feasibility

Studies of micro-hydro projects ranging up to 100 kW of installed capacity. Thisguideline has proved successful in carrying out detailed feasibility and developing

micro-hydro projects.

In the near future, AEPC intends to extend its working sphere in the range of 100kW to

1000kW. Therefore, this guideline has been developed to conduct detailed feasibility

study of mini hydro projects from 100 kW to 1000 kW and is expected to undergo

continuous refinement and revisions as experiences comes by.

1.2 Objective and scope of works

The main objective of the Detailed Feasibility Study of Mini Hydropower Projects in the

range of 100 kW to 1000 kW capacity is to determine the technical feasibility and

financial viability of the project so that it can be implemented by a private

Developer/Community. The feasibility study report provides necessary information to

the Developer to make decisions for the implementation of the project.

The scope of work under a feasibility study includes:

Study and review of reconnaissance or pre-feasibility study of the project prepared

in earlier study

Carry out hydrological, topographical, geological & geotechnical field survey and

investigations. Collect information on existing infrastructure.

Conduct socio-economic survey and environmental study of the project and supplyarea

Study of multipurpose use of water resource

Assessment of power & energy requirement and load demand forecast of the

project area

Assessment of power potential of the site and determination of optimum plant

capacity

Prepare layout, design and dimensioning of the components of the power plant on

detailed feasibility study level

Study of transmission line for power evacuation and for interconnection with minigrid or central grid


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Preparation of construction planning and scheduling

Preparation of Bill of Quantities and project cost estimation

Carry out financial analysis of the project

Risk assessment of the project

Project evaluation on implementation and recommendations for further action.

The detailed feasibility study serves as the documented basis for decision making by

the investors and for entering into contract for detailed design and construction. It is

assumed that a turnkey contract is the basis for the detailed design and the

construction. In a turnkey contract, the contractor has to complete the detailed design

and have it approved before contractor enters in construction work.

The detailed feasibility study report: should provide detailed information on the project.

1) Demand Survey

2) Supply analysis3) Financial analysis

4) Community benefit assessment

5) Risk assessment

6) Project layout and recommended specifications

1.3 Feasibility Study

The feasibility study of a project is carried out after a project has been identified and its

preliminary study completed. If the preliminary study concludes that the project looks

attractive for development, then a feasibility study is carried out in order to determinethe technical and financial feasibility of the project. The feasibility report provides basis

for whether the project is worth investing and concludes whether to go ahead with the

implementation or not. Thus, the feasibility report should be a decision making tool for

its implementation. If the developer is satisfied with the return on his investment in the

project, then he proceeds for its implementation. The report will also provide a basis

for negotiation of loan from a financing institution for its development.

A detailed feasibility is a comprehensive study prepared after the detailed field

investigation work of a mini hydropower to supply power and energy to a certain

supply area and to the neighboring grids. The study prepares optimum design and

layout of the project with its cost estimation and then carries out the financial viability ofthe project. The study prepares the load demand in the supply area and conducts

socio-economic and environmental study of the project area. The detailed feasibility

study report helps the Developer to negotiate with a contractor for the detailed design

and construction of the project and the contractor to offer a bid and prepare the

working drawings for construction.

1.4 Application of Guidelines and content

The present guideline is prepared to assist consulting engineers and developers to

conduct the detailed feasibility study of a mini hydro project. Experience of mini hydro

development in various countries and guidelines on planning and design have been

studied and referred to prepare this guideline. In particular, the guideline is prepared in


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the context of Nepal. Guidelines are not one time job and are not final documents.

They should be updated and upgraded continuously.

The aim of this guideline is to prepare detailed feasibility reports in a definite quality

and bring uniformity in content and presentation of the report. It is expected that the

guideline will serve to design cost effective projects for the electrification in rural areas

including supply of surplus energy to the nearby grid (national or mini) through minihydro development.

The Guideline covers methods and sequence of preparation of the detailed feasibility

study of a mini hydro project. Methods of conducting field survey & investigation and

scope of design and analysis have been elaborated.

1.5 Hydropower development and the private sector

Since 1990 the government has made attempts to mobilize the local and international

private sector to invest in the hydropower sector of the country. New legislation has

been introduced since then and new policies have been put in to place. This hasresulted in the development of several hydropower plants by the private sector.

The Ministry of Water Resources, with the intention of developing small hydropower

(up to 10 MW) through the private sector, has declared policies for the purchase of

electricity by NEA from projects which can be interconnected with INPS. The policy is

reviewed time to time. The 1998 policy has the following features on power purchase

from IPPs.

NEA will buy all power produced by the private power plants of 10MW or less

capacity.

PPA period is 25 years.

Base year for energy tariff will be 2055/056 (1998-1999)

Differential tariff: For power plants of less than 5 MW installed capacity, there are

different rates for wet and dry months with an annual escalation on tariff of 6% for

the first five years and review of tariff from the 6th year.


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2. PROJECT DEVELOPMENT OPPORTUNITIES

2.1 General

The feasibility study of a mini hydro project is carried out to determine the technical

feasibility and financial viability. The feasibility study report will assist the developers,

the government agencies or donors on whether to proceed for the implementation of

the project or not. The report provides basis for appropriation of government funds or

for negotiation of a loan from financing institutions for the project implementation.

2.2 Components of a Mini Hydro Project

Hydropower projects require tailor made layout and design according to specific site

conditions like hydrology, topography, geology, socio-economic and other features.

The design and layout must be sound and performed by experienced professionals.

Nevertheless, mini hydro projects bear similarity in their technical features

standardized planning tools can be designed to a large extent. On the basis of supply

conditions mini hydro projects can be categorized as:1. projects to supply isolated load centers not connected into any grid,

2. projects interconnected with the nearby grid (national or mini-grid).

3. projects to supply both to isolated load centers and connected to the grid.

The basic components of a mini hydro project are:

A. Civil Structures

1. Diversion Weir and Intake Structure

2. Gravel Trap and Settling Basin

3. Headrace Water Conveyance (canal or conduits)

4. Forebay/ balancing reservoir

5. Penstock

6. Powerhouse

7. Tailrace Canal

B. Powerhouse Mechanical Equipment

1. Turbine

2. Governor3. Inlet Valve

C. Powerhouse Electrical Equipment

1. Generator

2. Excitation System

3. Control and Protection equipment

4. Power Transformer

5. Low Voltage Distribution and switchgear

5. Earthing and lightning arrestors


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D. Transmission/ Distribution Line

1. Switch Yard / MV switchgear room

2. Transmission Line

3. Distribution Transformer4. Distribution Line

The schematic layout of a typical mini hydro project is illustrated in the following figure.

2.3 Function of the Mini Hydro Components1. Diversion Weir: Structure placed across the river to divert a part of the river flow

to the water conveyance system through the intake.

2. Intake: An opening to draw design flow from the river and provided with trash

rack screen to prevent entry of floating debris and coarse bed load into the water

conveyance system. It is equipped with a control gate to regulate flow down the

conveyance system under various flow conditions in the main river.

3. Gravel trap: Structure to intercept bed load carried by the diverted flow. It is

equipped with gravel flushing gate followed by a flushing canal to discharge the

trapped gravel particles back to the river. A lateral side spillway also can be

located in this structure to spill excess flow entering from the intake during highfloods.

4. Settling Basin: An approach canal conveys water from the intake/ gravel trap to

the settling basin. It settles suspended sediment contained in the water. The

settled sediment is subsequently discharge back into the river through a flushing

arrangement consisting of flushing gate/ valve and canal.

5. Headrace Conveyance System: Usually a canal/ pipe/ tunnel or a combination

of these for the purpose of delivering design flow to the forebay with a minimum

energy loss.

6. Forebay (Head Tank or Surge Tank): It stores water to compensate changes indesign flow, stabilizes head on the penstock. A side spillway is provided in this

structure to spill excess water coming from the conveyance system. The forebay


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is equipped with a fine screen/ trash rack to prevent floating debris into the

penstock pipe and ultimately to the turbines. It serves as a secondary settling

basin as well and a sediment sluice to remove settled suspended particles.

7. Penstock: Conveys design flow under pressure to the turbine/s with a minimum

head loss. Anchor blocks and saddle supports are provided to stabilize forces

acting on the penstock pipe.

8. Powerhouse: Houses electricity generating units, switch gear, control equipment

and maintenance equipment.

9. Tailrace: Disposes the design flow discharged by hydraulic turbines after power

generation.

10. Switchyard: Houses HV (33KV) switchgear and power transformer (if 33KV)

where applicable and transmission line termination such as lightning arrester,

outdoor CT/PT, isolator and earthing switches.

2.4 Power MarketThe power market of mini hydro projects can be divided into two categories depending

upon interconnection of the project.

(1) Isolated Scheme

If the project is to operate in isolated mode the power market will be the load

centers envisaged to be supplied by the proposed mini hydro project. These

load centers in general exhibit the following characteristics:

Energy use is primarily for domestic lighting purpose,

Peak power demand are in evening hours,

Day time load is limited to milling of agro products and other commercialuses,

The household consumers are scattered in wide area,

The load factor of isolated system is generally low,

Load promotion activities should be identified/designed for increasing the

load factor which is essential for the financial viability of the project.

Data for power demand assessment is collected during the field visit.

Discussion with community helps to determine the power requirement. The

load survey consists of collecting number of households to be connected with

electricity, collecting data on population of load centers and growth rate ofpopulation, assessment of income level of households, identification of end-use

possibilities for cottage industries and commercial services in the supply area.

Prospective entrepreneurs willing to install various end-use projects should be

identified at the detailed feasibility study.

In isolated system the installed capacity is governed mainly by the domestic

demand. Other non-lighting uses should ideally complement the lighting use. If

the end uses are such that they can be operated during non-lighting hours, the

size of the scheme need not be unnecessarily increased. At any time, the total

capacity of end uses in operation is desirable to be limited to installed capacity,

which is governed by the lighting demand. Other approaches to sizing a plantmay also be proposed, provided that financial viability can be demonstrated.


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The maximum demand for which a hydro scheme is to be designed and the

load variation it has to accept have to be determined in the feasibility study of

the project. For an isolated run-of-river scheme the hydrology governs the

limitations in the output capacity.

(2) Scheme Interconnected with Other Generation Facilities

Schemes with larger potential generation sites should be studied for

interconnection with other generating facilities. During the field survey, it is

required to collect information on the adjacent power facilities and nearest

transmission line. It should be investigated whether surplus power from the

proposed project can be transmitted to the nearby local or national grids. The

voltage level, distance from the new scheme, capacity of the transmission line

to absorb the additional power supply etc. should be investigated. Grid

connected schemes have better financial viability than isolated schemes as all

the energy generated by the scheme can be sold to the grid operator.

The electricity tariff will have to be determined/ assessed both for supply in the

local load centers and for supply to the grid operator. The purchase rate of grid

operator might be less as he is supplied only the surplus energy which will be

secondary type of energy. For guaranteed power, a take or pay type of Power

Purchase agreement can be entered with the grid operator. But since most of

the mini-hydro power plants will be selling only surplus power, instead of Take-

or-pay, a simple energy contract will be best. The tariff is fixed and is same for

both types of contracts. Up to 1000 kW capacity, this facility of flexible energy

supply is available presently.

2.5 Alternatives of Supply

A feasibility study assesses alternatives of electricity supply and prioritizes them for

implementation. Electrification of rural areas away from central grid can be planned

with different alternatives. It depends on the location of the supply area, accessibility,

size of load center and power demand etc. Possible alternatives of electricity supply in

a remote rural area are:

a) Supply by constructing a new hydropower project (micro, mini and small).

b) Extension of grid line

c) Supply by diesel generators

Extension of long transmission line for electrification was considered expensive on one

hand and on the other hand the Integrated Nepal Power System is facing deficit in both

power and energy and is not meeting demand of existing electrified area. However,

NEA is extending its grid lines to many areas that are being connected by road

network. The GON has recently introduced community electrification schemes through

NEA. The government has declared that it would subsidize 80% of the cost for RE

through NEA if community contributes 20% of the electrification cost. The alternative to

electrification will be the community electrification where the electricity line is extended

with local participation together with NEA. In many cases electrification using this

scheme would be much more feasible alternative compared to establish a new mini-

grid facility with own generation.


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The rural electrification best alternative in hilly areas is considered by constructing

smaller sizes of hydropower projects where there is potential for this alternative. In

Nepal, various micro hydro plants are supplying electricity to small settlements. Larger

load centers can be electrified through mini hydro projects. It is necessary to study the

possibility of grid connection during the feasibility study of the project. Multipurpose

projects and integrated end uses of electricity from mini hydro projects should beidentified or designed to develop a viable project.

Supply of electricity by installing a diesel generating unit has high operating cost.

Transportation of costly diesel to remote inaccessible areas is very high. Contrary to

high production cost from diesel generator, the affordability of rural consumers is low.

So, this alternative is considered unfeasible for rural electrification in Nepal. The

generation cost from this alternative is Rs. 30 to 70 per kwh and more.

2.6 Institutional Aspects

Assessment of Developers capability and commitment to implement the scheme

should be made by the consultant. Financial and management ability for

implementation and operation of the project should be elaborated. Also the role of

beneficiary/ community in the project implementation and operation should be clearly

defined. The Developer must have overall knowledge of mini hydro development

process and must be aware of the risks associated with it.

Institutions such as NGOs or government line agencies that are active in the project

area and are likely to contribute in the implementation of the scheme should be

contacted and explored their interest in the scheme and possible contribution on their

part should be mentioned in the report.

2.7 Policy issues

2.7.1 Application Process under Electricity Act

Section 3 of Electricity Act, 2049 has the provision that a proponent does not require

a license for survey, construction and operation of production/ transmission/

distribution of a hydropower project with installed capacity from 100 kW to 1000 kW.

However the proponent shall submit the certain information before commencing the

work of the project as prescribed in Schedule 1 of Rule 3 of Electricity Regulation,

2050. Submittal shall be made to the Secretary of Ministry of Water resources

(MoWR) through the Department of Electricity Development (DoED).

If the proponents application is for survey of the project only, the proponent shall

submit the following information to the DoED.

a. Desk study of the proposed project which includes salient features (i.e. name of

the water body), scope of work and work schedule

b. Topographical map showing all the major components of the project (in scale of

1:25,000 or 1: 50,000).

c. Electricity distribution area and estimated number of consumers to be benefited, if

any.

d. Information regarding other water uses in the area


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e. Letter of recommendation addressed to DoED for project development (survey,

production, transmission and distribution) from concerned VDC/ Municipality with

a copy addressed to DWRC (District Water Resources Committee).

f. Boundaries of the survey area with latitudes and longitudes including VDC/

Municipalities.

2.7.2 Government Policy

A detailed feasibility study should adequately address AEPCs, the focal point of

Ministry of Environment, Science and Technology (MOEST), policy issues regarding

the eligibility for subsidy support in the scheme. Currently, these include the

following:

Renewable Energy Subsidy Policy 2063 supports rural energy projects for the

protection of environment and sustainable development.

Whether adverse environmental impacts are possible due to the implementation

of the scheme.

The project must be financially viable such that the return on equity at the

applicable discount rate for the economic life is positive.

The subsidy policy of AEPC for the study and implementation of the scheme

should be mentioned in the relevant parts of the feasibility study.

As policy requirements may change over time, it is recommended that the consultant

contact the AEPC office regarding the policies that are applicable at the time the

study is conducted. For schemes to be interconnected with the national grid (NEA)

the consultant should address and meet all the requirements of NEA for such

schemes. The procedure of power purchase agreement (PPA) for the sale of surplus

energy to NEA and its expected energy purchase rate should be used in the financial

analysis of the project.

2.8 Opportunity of Integrated Use of Water resources

Financial and economic viability of a hydro project is enhanced by integrating hydro

generation with other uses of the water resource for the purpose of irrigation and water

supply. The following configurations of multi-purpose use of water are practiced:

Feeding irrigation command area located downstream of the of the tailrace canal

Use canal drops in the middle of the main canal of irrigation system Supply water for irrigation or water supply from the power canal or forebay

Pumping water for irrigation or drinking water during off-peak period

For multi-purpose schemes, the following concerns should be considered in the

feasibility study:

Apart from meeting the flow requirements for power generation, excess flows are

available for the secondary purpose. For example, if the design flow required for

power generation is less than the 11-month exceedance flow (large river and low

installed capacity), excess irrigation flows can be available during the irrigation

demand period. If the command area is along the headrace alignment, irrigation

flows can be made available by sizing the headrace canal to meet both demands


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(i.e. those for power generation and irrigation). If a pipe is used for headrace, flow

control structures such as valves will be required at the irrigation outlets.

If the command area is along the tailrace alignment, irrigation flows can be made

available without increasing the conveyance capacity of the headrace.

Realignment or extension of the canal length can be the only additional costs

required.

It may also be possible to accommodate irrigation flows or other non-hydropower

flows with the same design flows or canal by water management practices. For

example, irrigating during off-peak hours by either reducing the power output or

closing the plant are viable options.

The additional costs and incremental benefits from the secondary use should be

demonstrated multi-purpose projects. For example, the increase in the cost of the

headrace canal to accommodate irrigation flows should be compared with the

benefits due to increases in crop yields over the span of the power plant. If the

accumulated benefits from the secondary uses over the life the plant for a given

discount rate as per the prevailing policy exceed the additional costs required to

accommodate such uses, then multi-purpose projects can be justified.

Multiple uses of water resources should not be considered a threat in mini hydro

projects. In fact, efforts should be made to seek technical and management solutions

that encourage power generation and integrate other uses of water resources.


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3. SURVEY AND INVESTIGATIONS

3.1 General

The objective of field survey and investigation of a mini hydro project is to obtain

necessary data and information of the identified hydropower site and the electricity

supply area to carry out the technical feasibility and financial viability of the project. Thefeasibility study of a project is carried out to meet the power demand and demand

growth of a power market (supply area) which has been established through a

reconnaissance or pre-feasibility study of a particular hydropower site. At the feasibility

stage of study, it is understood that the electricity supply area has been defined to a

reasonable extent and a matching potential hydro generation site has been identified.

The prevailing regulation requires that permission for the feasibility study (survey

license) has been received by the developer from the concerned authorities to conduct

the feasibility study from a water source within a defined area.

Generally, the following field survey and investigations are conducted for the feasibility

study of a mini hydropower project:1) Topographical survey of the project for mapping of the site

2) Hydrological survey and data collection

3) Geological and Geotechnical investigations and studies

4) Socioeconomic study

5) Environmental Study

3.2 Approach & Methodology

To fulfill the above objectives of the feasibility study certain methodologies are

adopted. Such methodologies are: Desk study, reconnaissance study, review of earlierstudies, field survey and investigations; laboratory tests and data analysis,

topographical mapping, project design, quantity and cost estimation, construction

planning and scheduling and financial analysis. It will carry out power evacuation study

and conduct environmental study as per prevailing regulations.

In mini hydro project period, hydrology and geology should be studied properly to draw

right conclusions in the field investigation stage. The cost of investigation is directly

linked to the depth of investigation, therefore a balance between limiting the cost and

satisfactory data must be maintained.

3.2.1 Site Selection of Project Components

The field survey and investigation starts with a walkover survey of the earlier

identified site by a team of multi disciplinary experts. The field team generally

consists of a hydropower engineer, civil engineer, geologist, hydrologist,

topographical survey crew and environmentalist. Depending upon the size of the

project, site conditions and experience of the team members, the survey team can be

smaller. The joint team evaluates the site conditions and defines the project layout

after on the spot discussion. The walkover survey finalizes the sitting of all the major

structures. The locations of all the major structures are noted by each team member

on the available map from the earlier study or on the existing topographical map ofthe project site. It is recommended to use a GPS to record the coordinates of the


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selected sites. Then, each member carries out his specific study in detail. Information

is shared at the field with each other.

In the investigation of a mini hydro project it is highly recommended that relatively a

larger area be investigated before finalizing the project layout for detail survey &

investigation. For example, better site for river diversion and intake may be available

with increased natural head in the upstream of an identified site. Similarly, betterpowerhouse site and penstock alignment sometimes may be identified by extending

the walkover survey further downstream. Information on such possibilities may be

collected from local residents in the area.

For selecting the water conveyance system the alignment should be studied on both

banks. Merits and demerits on each bank should be compared and better one

selected.

(1) Diversion Works

The diversion works site shall be selected based on its suitability for the principalcomponents in consideration of technical, economic and environmental factors.

The primary factors considered in the site selection are:

a) The diversion structure should be sited in a straight reach of the river as

possible

b) The river banks shall be well-defined

c) The diversion structure shall be located at a relatively narrow section of the

river to the extent that the hydraulic functions of the structural components

do not interfere with each other.

d) The site shall have ample space for construction activities and sufficient

level differences to allow flushing of the sediments.

e) The selected sites shall be geologically stable.

f) The diversion works shall be located at sites where the upstream and

downstream hazard potentials resulting from its construction and operation

are minimal.

g) The site shall preferably be located at areas where the local construction

materials are available in adequate quantities and of suitable quality.

h) The site is selected considering river diversion and flood handling during the

construction period.

i) As far as possible, the site shall be located at or near existing infrastructure

such as access road and power supply.

j) The site shall be selected with due consideration to minimizing adverse

environmental impacts.

(2) Intake

General Principles for selecting intake location:

The following principles should be considered while selecting appropriate intake

locations:

a) Minimum disturbance to the natural state of the river.

b) Location in an area that offers natural protection.


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c) Location on the outside of a bend should be chosen so that the largest

possible portion of the bed load remains in the river and not taken in the

waterways.

To hold off the bed load the following measures has to be considered:

i) Use of physical laws:

To minimize sediment load and to ensure flow availability during dry season;

an intake should be sited on the outside of a bend. The best location is

about 2/3 to 3/4 of the distance around the bend as shown in the fig below.

If it is necessary to construct the intake on straight river section, a bend flow

can be made in order to follow natural physical laws.

ii) Technical Measures:

As technical measures, bed load deflecting structures in the form of intake

sills, under sluice etc, in the flow area can be introduced.

In order to use of natural physical laws, technical measures are always

necessary for:

Intake where the water is not dammed up.

Intake where the water is dammed up.

The intake structure in dammed up case is located in such a way that the intake silllevel should be heightened up by 0.5 to 2m based on the river sediment transport

characteristics.


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In order to minimize the entry of bed load, the flow in front of the intake on straight and

narrowing river section must be deflected. For this, the groins are arranged on the

opposite side of the intake structure.

The selection criteria for side and bottom intakes based on nature, flow and sediment

behavior of the river are summarized in the tabular form below:

SELECTION CRITERIA SIDE INTAKE BOTTOM INTAKE

Amount of water: Favorable site selection

necessary (outside of a bend

or an artificial bend by

groins) if the amount of

diverted water is greater

than 50% of the water

supplied.

The bottom screen dawns off

the river up to capacity limit

of the screen (i.e. all river

flow if screen is large

enough).

Gradient of river:

Very high ( i > 10%) to high

(10%> i >1%)

Favorable: maintenance free

operation of the intake

structure should be ensured

as far as possible

Favorable for very high

gradient; can be

maintenance free, if properly

designed.

Unfavourable if i i

>0.01%)

Favorable Unfavourable: fine bed load

into initial headrace canal

results in difficulty in flushing.Plan of river:

Straight Possible Very favorable as bottom

screen is uniformly loaded.

Winding Very favorable if the river

channel is stable; when

arranged on the outside of

the bend.

Unfavorable, as bottom

screen is not uniformly

loaded

Branched Unfavorable; damming of

river is required.

Unfavorable.

Suspended sediment

concentration.

High

Low

Suitable in combination with

very efficient settling basin.

Well suited.

Less suitable

Well suited.

Bed load transport:


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Strong

Weak

Suitable as long as sufficient

amount of water remains in

the river for flushing.

Well suited.

Less suitable.

Well suited.

(3) Settling Basin

The settling basin site is generally selected on flat and larger area to accommodate

the foreseen structures parts and facilities. Large excavation works should be

avoided specially towards hill slope. Attention should be given that it is possible to

flush the sediment and spill water from the basin without causing any problems.

There must be sufficient flushing head to flush the sediment and drain the basin

with respect to the river high flood level. It should be located as close to the intake

as possible to discharge sediment back to the river. Adequate space on fairly

leveled ground is needed to construct the structure. If suitable site is not available

immediately after the intake an approach canal can be considered to convey the

water to a site further downstream.

(4) Headrace Canal Alignment

Headrace canal is suitable in stable geological and favorable topographical conditions

to convey water for power generation. Generally, the contour elevation of the

headrace canal bed level is followed to minimize cutting and filling works. It is notrecommended to align a canal or other structure in fills as far as possible. If a

depression is to cross the canal bed has to be raised on a firm foundation. The soil

and slope stability condition along the canal alignment are the governing factor in the

selection of the canal option instead of tunnel or pipe. The canal option is practical

only for small discharge in the hilly regions of Nepal. Canal construction with large

dimension is limited due to steepness and fragile geological condition creating slope

stability problem.

Detail geological mapping along the canal alignment and test pit observation,

sampling and testing are necessary to decide the suitability of the terrain condition for

excavation and construction of headrace canal.Different structural components like cross-drainage works (aqueducts, siphons) along

the headrace canal are generally the integral parts of it. The headrace canal may

have to pass through a number of crossings. Headrace canals are more economical

in a favorable topographic condition. The canal requires considerable maintenance to

control canal seepage. Canal costs may also be excessive if it requires a substantial

number of stream crossings (aqueducts and siphons). In some topographical and

geological conditions, cut and covered canal can be provided.

The terrain condition indicating not favorable for excavation of canal may in some

case exhibit the possibility of the pipe option as the conveyance for hydropower

development because it will require minimum excavation space for pipe installation.The geological and geotechnical study for the design of the pipe route should


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emphasis on distribution and characteristics of the rock and soils, thickness of the

overburden soil, position of the unstable areas, and locations of foundation problem.

(5) Forebay

The forebay site is identified at the end of the headrace canal and represents a small

intake reservoir for the penstock. The location is normally fixed at the top of the most

suitable alignment of penstock. A relatively flat and even land area is preferable to be

identified. As it is located right over the powerhouse the forebay must be constructed

on a stable place. It is recommended to be built on undisturbed ground. Site for save

conveyance of drainage water, surface run-off and spill water to a nearby creek or

down the hillside to the main river should be fixed and mapped.

(6) Penstock

The penstock should follow a ridge rather than a depression to reduce drainage

problems. The vertical alignment can follow the slope of the terrain in order to avoidexcessive excavation. Sharp bends should be avoided to reduce head losses and

size of supports to anchor the pipe.

The position of the penstock will be guided by the respective location of the forebay

and powerhouse. As the penstock line follows the terrain towards the down slope

direction between the forebay and powerhouse, the study of the soil and rock

characteristics, overburden soil depth and the slope condition and its stability are the

important factors that require consideration while undertaking geological /

geotechnical investigation. Surface examination along the penstock line should be

supported by geological investigations of the foundation condition.

The alignment of the pipe should be straight and short to the extent possible. Largenumbers of bends (horizontal or vertical) increases the head loss and cost by

increasing anchor blocks and expansion joints. To determine the most economical

alignment of a pipeline, the designer must investigate the site and make various

layouts on topographic maps. He must then estimate material quantities for each

layout and evaluate its constructability.

When making these layouts, the penstock should be located on stable foundation

sites such as along a ridge or a bench that has been cut into the mountainside.

Troublesome sites such as underground water courses, landfill, fault zones and

potential slide areas should be avoided.

Because of low-head penstocks cost less than high-head penstock, keep the pipeline

at high elevations as long as possible before going down the mountainside into the

powerhouse. To minimize costly anchors and costly pipe transition sections, combine

vertical bends, horizontal bends, and changes in diameter shall be combined at the

same location.

(7) Powerhouse Site selection

The powerhouse houses the generating equipment, which is considered the most

expensive component of a power plant. Therefore, it is essential to locate the

powerhouse in a safe location. It is generally located at the end of the penstock andnear the river where the tailrace discharges the water after the turbine. Thus, at one


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hand it should be located in such a way that it is not damaged by rock falls or slides

down the penstock hill and on the other hand it should be at a safe distance and level

from the probable high floods.

Generally, a flat land is identified with sufficient area to layout the powerhouse,

tailrace and switch yard facilities. For mini hydro projects, surface powerhouse should

be considered with the minimum excavation works. It is recommended that thetailrace invert is fixed above high flood level (HFL) and the flood level should be that

for 100 years return period flood magnitude. The HFL can be obtained from the rating

curve (stage discharge curve).

Rating or stage discharge curve at a particular cross section of a river provides

information on water level in the river a different magnitude of flows. The river flows/

floods are shown in the abscissa and the water depth the ordinate. The powerhouse

floor level should be above 100 years period return flood.

Transformer and switchyard area should be identified close to the powerhouse on a

flat area.

3.2.2 Topographic Survey and Mapping

3.2.2.1 Available Maps and Survey Equipment

Available Maps

Topographic Maps prepared by the Survey Department of Government of Nepal are

available in the scales of 1:25,000 and 1:50,000, which are used as a basis for

further topographic survey and mapping of the site. These days digitized topo maps

are also available in the Survey Department and can be purchased. Topographical

maps provide Important information, such as ground elevation, nature of river

stretches/ bends, areas of forest, cliff, agro land, slides, settlements, existing trails,

roads, electricity line etc., which are very useful for the survey team.

Contour maps from pre-feasibility or earlier study, if available, should be referred in

the preliminary study and used for planning of subsequent field survey works.

Survey Equipment

Survey equipment required for topographical survey are listed below:

1) Global Positioning System (GPS)/ altimeter, compass

2) Total Station or Theodolite and Level Instrument

3) Prisms, survey staff (3m/ 5m), ranging rods in required numbers

4) Measuring tapes ( 3m/5 m, 50m/100m)

5) Chisel for engraving in rock/boulders, enamel paints (red or yellow), wooden

pegs, concrete monuments with pegged nails etc.

3.2.2.2 Topographical Survey

A team of multi disciplinary experts visit the project site identified earlier. This team

evaluates the site conditions and defines the project configuration after on the spot

discussion. After a walkover survey of the project site and finalizing the layout of the

project and fixing the locations of major structural components (headwork, canal


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alignment, forebay, penstock alignment, powerhouse and tailrace alignment), the

following works are carried out:

1) Establish control points and benchmarks.

2) Carry out close traverse survey to establish required ground control points at

various locations in the project area.

3) Carry out topographical survey covering the complete project area. The major

structural components should be surveyed in detail. Details of existing features

like survey points, streams, forest area, high flood marks, test pits, river banks,

cultivated land, foot trails, roads, houses, springs, ponds, electricity supply line,

rocky cliff, landslide etc. should be surveyed for mapping.

4) Strip survey of water conveyance route (canal, aqueduct, siphon) with detailed

cross section of cross drainage, lying across the headrace conveyance route

(s) and penstock route with coverage of most promising alternatives to produce

maps. The width of the survey corridor should be at least 20m on each side

from the centre line of the canal alignment.

5) River cross section survey should be carried out both at intake and

powerhouse/ tailrace sites covering at least 200m upstream and downstream at

each site. The intervals should be 50m to 100m depending upon river

conditions. High flood marks and existing water levels must be shown in the

cross section. Similarly, the detailed cross-section survey of sites of cross-

drainage works is also need to be carried out.

6) The survey may include impoundment or peaking pondage area.

7) Conduct strip survey of access road alignment with fixing of bench marks, in an

interval of 500m and at major cross drainage locations.

8) Conduct walkover survey along transmission routes using available 1:25,000scale topo-sheets to compare with socio-environmental settings including

forested areas to be crossed for potential alternatives. GPS will be used for

getting coordinates of the transmission line route.

9) The Bench Marks (BMs) reference points should be clearly defined in

Topographic maps as well as in the report. The reduced level and co-ordinates

will be transferred from nearest permanent survey station (National

Trigonometric Grid) established by the Department of Survey. Alternatively

benchmarks with an arbitrary reduced level (RL) will be adopted by using RLs

from GPS or available topographical maps. A separate reference should be

prepared and concrete monuments with embedded nails should be establishedas BMs. BMs established on large boulders should be engraved in an encircled

cross and the BM number also engraved as enamel paints disappear in a short

period. D-cards (description cards) should be prepared for all control points of

topographic survey. Also the photographs of the control points should be taken

to include in the survey report.

10) BMs should be established at Headworks (diversion weir, intake and settling

basin) site, along headrace canal @1 km, forebay site and powerhouse site.


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3.2.2.3 Mapping and Plotting

1) Prepare contour map in 1:5000 scale with contour interval of 5m for the whole

project area. All the features mentioned in c of (ii) above must be shown in the

contour maps.

2) Prepare contour maps in 1:200 with 1m contour intervals for diversion weir,

intake, settling basin, forebay and spillway, penstock alignment, powerhouse

and tailrace canal.

3) Other maps, cross sections, profiles should be developed according to the

scales of relevant drawings required for the detailed feasibility study.

Scales of Drawings (Paper Size: A3 Paper)

S.N. Types of Drawing Scale Counter

Interval

1 Alternatives Considered 1:5000 5 m

2 General Arrangement of Selected Project 1:5000

3 Headworks

a) General Arrangement 1:500 1 m

4 Diversion Weir and Intake


b) Elevations and Sections 1:100

5 Settling Basin

a) Plan 1:200 1 m

b) Section 1:100

6 Headrace Water Conduit System

a) Plan & Longitudinal Profile 1:2000 2 m

b) Section 1:200

7 Forebay to tailrace

a) Plan and Profile 1:2000 2 m

b) Section 1:200

8 Forebay (Elevations and Sections 1:500)

a) Plan 1:200 1 mb) Section 1:100

9 Powerhouse


b) Plan and Elevations 1:200

c) Sections 1:100

10 Powerhouse Switchyard Layout 1:500

11 Cross Drainage Works

a) Plan 1:200b) Sections 1:100


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11 Access Road Interval 1:5000 5 m

Transmission Line (T/L)

A walkover survey of transmission routes using available 1:25,000 or 50,000 scaletopographic sheets should be carried out The route of the transmission line should beplotted on the map. The coordinates of distinct features should be recorded and given inthe route map. Important physical and social features falling in the right of way ofalignment should be noted down Socio-environmental impacts of the transmission lineshould also be assessed. Transmission line can be measured by preparing the T/Lprofile from the topo-map. The T/L should be surveyed to each load center. ]

3.2.2.4 Site Photographs

aepc guidelines for detailed feasibility study for projects

Documents