Annex 4. Technical Guideline

Transcription

1 Annex 4 Technical Guideline 1

2 Contents 1. Purpose of Technical Guideline 2. Scope of Feasibility Study 3. Socio-economic and social/natural environments survey 4. Topographical survey 4.1 Collection of existing topographical maps 4.2 Topographical survey and mapping for preliminary design 4.3 Longitudinal river profile survey 4.4 River cross-section survey 5. Meteorological/hydrological survey and analysis 5.1 Collection of existing meteorological/hydrological data 5.2 Meteorological/hydrological survey 5.3 Length of rainfall and river runoff data 5.4 Rationale and validation of selected rainfall and runoff data 5.5 Low flow analysis 5.6 Flood analysis 5.7 Backwater analysis of the reservoir during flood time 5.8 Hydraulic analysis during flood discharge and power discharge 5.9 Hydraulic analysis against landslide effect to reservoir 5.10 Reservoir evaporation 5.11 Reservoir sedimentation 6. Geological, seismic and Construction Material Survey 6.1 Geologic survey and analysis Geological maps Aerial photo interpretation Geologic surface reconnaissance Geophysical prospecting Drilling investigation Laboratory rock test Other investigations 6.2 Seismic survey and analysis 6.3 Construction material survey Material for concrete dam and other concrete structures Material for embankment dam 7. Recommended Project 7.1 Project description 7.2 Preliminary Design 7.3 Construction Plan and Implementation Schedule 7.4 Project Cost 2

3 Technical Guideline on Feasibility Study 1. Purpose of Technical Guideline This Technical Guideline present the detail contents, requirement and recommended methodologies for Feasibility Study of hydropower project to be conducted by the Project Developer. 2. Scope of Technical Guideline This Technical Guideline is applicable for all the hydropower projects developed by IPP investors, EDL, EDL-GEN and PDEM. 3. Socio-economic and social/natural environments survey The Project Developer shall prepare, in accordance with the results of socio-economic survey and social/natural environmental survey, explanatory plan(s) on topographical maps of more than 1/50,000 scale showing both existing and future activities such as land utilizations, local development plans and other water resource development plans as well as hydropower projects for the purpose of sustainable integrated water resource and watershed management. 4. Topographical survey 4.1 Collection of existing topographical maps The Project Developer shall collect existing topographical maps of 1/100,000 and 1/50,000-scale covering the hydropower facilities of dam, waterways, powerhouse and transmission lines as well as drainage areas and temporary facilities such as access roads, camp facilities, borrow areas, quarry sites and resettlement areas. The above topographical maps of 1/100,000 and 1/50,000-scale are used only for identification of the locations of project facilities including temporary facilities. Detailed topographical maps are required for preparing preliminary designs as stated in Topographical survey and mapping for preliminary design The Project Developer shall prepare the following topographic maps required for both planning study and preliminary design. 1/5,000 map to cover the project facilities including dam, waterways, and powerhouse, access roads, and camp facilities, quarry sites, borrow areas and resettlement areas. 1/10,000 map to cover inundated areas by dam and/or weir, and transmission line 1/500-1/1,000 map to cover the above-ground structures of power facilities such as dam, weir, open channel, head tank and powerhouse 4.3 Longitudinal river profile survey The Project Developer shall conduct a longitudinal river profile survey by measuring river bed elevations covering the most upstream end of the inundated area by dams or weir and the powerhouse outlet location. The Project Developer shall also investigate and study the river profile, i.e. river-bed slope, with topographical maps of more than 1/50,000 scale in order to verify that potential heads of the river are effectively utilized by both existing and planned hydropower projects, and then shall prepare the river profile of main river and its tributaries indicating locations of existing and planned hydropower projects. 4.4 River cross-section survey The Project Developer shall conduct a river cross section survey at power outlet sites in order to study the tailrace water levels of various power discharges. In case some downstream areas of the dam or the powerhouse/outlet will be inundated during power discharges or flood discharges, the Project 3

4 Developer shall conduct river cross section surveys for the downstream areas at appropriate intervals in order to identify the inundated area due to the hydropower project. 4.5 Catchment area and reservoir volume The Project Developer shall measure the catchment area of the main dam and/or intake weirs by 1/50,000 or 1/10,000 topographical map, and also calculate the reservoir volume of the project by using appropriate topographical maps in two different methods of altitudinal and cross-section ones. 5. Meteorological/hydrological survey and analysis 5.1 Collection of existing meteorological/hydrological data The Project Developer shall collect existing meteorological/hydrological data as below in and near the project area. These data are utilized as bases for hydropower development planning, preliminary design and construction schedule. A location map showing existing meteorological/hydrological stations and the project shall be prepared. Rainfall (daily, monthly, annual) Temperature (daily average, daily minimum, daily maximum, monthly average) Wind velocity and direction (daily average, daily minimum, daily maximum, monthly average) River runoff (daily, monthly, annual) Flood records (hourly river discharge records during floods, or flood marks at river banks or trees or bridges) Evaporation (monthly, annual) Suspended load records during dry and rainy seasons together with river discharges Sediment records of existing dams 5.2 Meteorological/hydrological survey When the above existing data is not enough nor reliable for FS, the Project Developer shall set up gaging stations and conduct surveys to collect sufficient and reliable meteorological/hydrological data for the period of at least 1 year. It is advisable to measure river discharges at an appropriate location of the project as well as rainfalls during FS. In case of small hydropower development of run-of-river type, it is advisable to measure river discharges at a minimum 3-10 times a year including dry season in order to prepare runoff duration curve, followed by the determination of installed capacity(kw), annual energy production(kwh) and guaranteed capacity(kw) during dry season. 5.3 Length of rainfall and river runoff data The length of rainfall and river runoff data series to be collected by the Project Developer shall be greater than or equal to 10 years, and years of river runoff data series are preferable for sound and reliable hydropower planning. 5.4 Rationale and validation of selected rainfall and runoff data The Project Developer shall establish rationales of the selected meteorological/hydrological stations to be used for FS in terms of their locations, record lengths and their reliabilities. Prior to the use of measured rainfall and runoff data for FS, the Project Developer shall validate the consistency and reliability of the measured data through statistical approaches. If they are found to be inappropriate, the Project Developer shall identify the reasons of inappropriateness and eliminate them from the data series or correct them by reasonable methods. 5.5 River flow analysis When the length of river runoff data series is less than 10 years, the Project Developer shall conduct low flow analysis in order to prepare a river runoff data series at main dam site and/or intake dam/weir 4

5 sites for not less than 10 years, preferably years, through the following methods and their combinations of hydrological analysis. (1) Ratio of catchment areas between dam and gauging station (s) in the same river basin on condition that their drainage areas have similar rainfall patterns and amounts through a year Qg1 AB Qd Ag1 It is noted that the ratio of catchment area of dam site to that of gauging station is preferably several times. (2) Ratio of catchment areas considering the weight of the rainfall When the dam site and the gauging station are located separately, and rainfall amounts at the two sites are different, the runoff at the dam site is calculated by using a ratio of the catchment areas considering the weight of rainfall. The average rainfall in the catchment area is estimated by using isohyetal map or Thiessen method. Flow Qd at the dam site is expressed by the following equation; 1 Qg2 AB Ag 2 2 Ad AB1 AB Qd: runoff at dam site (m 3 /sec) Qg l : runoff at No. 1 gauging station (m 3 /sec) Qg 2 : runoff at No. 2 gauging station m 3 /sec) Ad: catchment area of dam site (km 2 ) Ag l : catchment area of No. 1 gauging station (km 2 ) Ag 2 : catchment area of No. 2 gauging station (km 2 ) AB l : catchment area of No. 1 tributary (km 2 ) AB 2 : catchment area of No. 2 tributary (km 2 ) 2 Qd=Qg Rd Ad Rg Ag Qd: runoff at dam site (m 3 /sec) Qg: runoff at gauging station (m 3 /sec) Rd: average rainfall at dam site (mm) Rg: average rainfall at gauging station (mm) Ad: catchment area of dam site (km 2 ) Ag: catchment area of gauging station (km 2 ) (3) Correlation between runoff data of gauging stations When the length of the runoff data at the dam site is not long enough, less than 10 years, and there exists other gauging station nearby with long-enough runoff data more than 10 years, the runoff data of the dam site can be extended for a longer period through a regression analysis with least-square method. Correlation coefficient of more than 0.7 is generally accepted (4) Data generation method of mathematical models When the length of the runoff data at the dam site is not long enough, less than 10 years, and there exists rainfall station nearby with long-enough runoff data of more than 10 years, the runoff data of the dam site can be generated by using mathematical models such as tank model, distributed runoff model and so on. The Project Developer shall process the monthly, weekly or daily runoff data at the main dam site or intake weir site and prepare a flow duration curve for run-of-river development project or a mass curve for reservoir development project. 5

6 5.6 Flood analysis Flood analysis is carried out to estimate flood flows at a proposed dam site. These flood estimates are required for the design of dam/spillways and diversion facilities. The inflow design flood shall be carefully determined through various approaches and considerations. Dam failure might cause tremendous damage against downstream area such as loss of life and economic loss. Inflow Design Flood for dam and spillway is specified in Article 17 of LEPTS as below taking care of hazard potential against downstream area of the dam. On the other hand, design flood at dam site during construction is determined by the Project Developer based on probable flood discharge for T- year returns period in consideration of dam type, construction plan and schedule, river diversion method and construction cost. The Project Developer shall estimate Probable Maximum Flood (PMF) and Probable Floods for various return periods up to 10,000 year by using available measured meteorological and hydrologic data, and MEM shall determine Inflow Design Flood for dam and spillway according to the dam classification specified in Article 17 of LEPTS. Dam classification Loss of life Impact on economy, society & environment Inflow design flood High Large increase Excessive increase PMF Significant Some increase Substantial increase Between PMF & 1000-year flood Low No increase Low increase Between PMF & 100-year flood (1) Probable Maximum Flood (PMF) PMF is defined as theoretically anticipated flood in the worst meteorological and hydrological conditions of the concerned area. Hydrograph Analysis is generally employed to estimate the PMF. The outline of work flow for the PMF is described in the chart below. Select rain gauge station DAD analysis of rainfall (Depth-Area-Duration) Estimate PMP (Probable Maximum Precipitation) Determine area reduction factor & hourly distribution Design PMP hyeto-graph Construct Unit Hydrograph PMF Hydrograph 6

7 The Project Developer shall identify rainfall gauging stations in/around the concerned river basin and select the stations of which records are used for Depth-Area analysis to obtain the area reduction factor for estimating a mean rainfall over the river basin. In general, the relation between point rainfall depth and basin mean rainfall depth is expressed by an exponential equation below, known as Horton s equation. P b = P 0 * exp[-kan] P b : mean rainfall depth over an area A (mm) P 0 : maximum point rainfall at a storm center (mm) A: concerned area (km 2 ) k,n: constant for a given area The Project Developer shall carry out Depth-Duration analysis by collecting hourly rainfall records during storms and estimating the hourly rainfall hyet-graph of heavy rainfall storm. When there are no hourly rainfall records in/around the river basin, the Project Developer shall install a self-recording rain gauge in the river basin and collect the hourly rainfall records. The Project Developer shall estimate the PMP through appropriate methods by using available data. The following methods are generally used for hydropower projects. It is advisable to estimate the PMP by more than two (2) methods. Theoretical approach in terms of the physically maximum moisture content by using temperature, humidity, dew points and wind velocity/direction Statistical approach which was developed by Hershfield and standardized by WMO in 1986 Historical approach by examining historical maximum rainfall storms ever occurred in the concerned area U.S. Weather Bureau method for the Lower Mekong River Basin to estimate generalized PMP with little meteorological and hydrological data The Project Developer shall construct unit hydrograph(s) by an appropriate methods including SCS 1 dimensionless unit hydrograph method, construct the PMP hydrograph(s) and estimate the peak discharge of PMF. (2) Probable floods for various return periods Probable flood discharge for T- year returns period is calculated by using a data series of annual maximum peak river discharges at gauging station(s). Hourly or daily discharge records depending on the size of drainage area are used for the estimation of probable flood discharges. The number of observed annual peak discharges is required for at least 10 years, preferably years. When daily discharges are used for the estimation, it is advisable that peak discharges are calculated by multiplying observed daily discharges by a reasonable conversion coefficient. A most fitted frequency curve for observed annual peak discharges is selected from probability density functions such as Gumbel s distribution, Pearson distribution, log normal distribution, log Pearson type III distribution. 1 SCS: Soil Conservation Service (USA), now Natural Resources Conservation Center (NRCS) 7

8 5.7 Backwater analysis of the reservoir during flood time The Project Developer shall carry out a backwater analysis of the reservoir during inflow design flood in order to access impacts of the reservoir water level rising in the upstream area including local villages, cultivated lands and existing structures like bridges and roads. In case serious impacts are anticipated during inflow design flood, the Project Developer shall prepare safe-guard plans to mitigate and alleviate those impacts. 5.8 Hydraulic analysis during flood discharge and power discharge The Project Developer shall carry out hydraulic analysis in the downstream area during both the normal power operation and the flood discharging through the spillway and then prepare a hazard map to indicate downstream inundated areas on topographical maps in order to examine impacts of the power discharge or flood waters over local villages, cultivated lands and existing structures like bridges and roads. 5.9 Hydraulic analysis against landslide effect to reservoir In case a large-scale landslide occurs in the reservoir area of the hydropower project, it causes huge shock waves in the reservoir which might overtop the dam crest. When the Project Developer identifies high potential locations of large-scale landslides, he shall conduct hydraulic calculations to simulate its disaster and confirm whether the dam will be overtopped or not Reservoir evaporation When the evaporation loss from the reservoir surface will not be negligible compared with river inflow into the reservoir, the Project Developer shall estimate the monthly amount of the evaporation from the reservoir by using measured data of evaporation pans. Evaporation loss from the reservoir surface is estimated by the equation below. E Loss = E open P, when E open > P E Loss = 0.0, when P > E open E Loss : monthly evaporation loss from reservoir surface E open : monthly evaporation from open water (measured value) P: monthly rainfall at reservoir surface 5.11 Reservoir sedimentation The Project Developer shall investigate and analyze suspended loads and river water quality in order to 1) estimate sedimentation volume of the reservoir, 2) design the settling basin, 3) design the sand flushing gate, and 4) ensure the durability of turbines. Sediment phenomena progresses and it reduces effective storage capacity between HWL and LWL as shown below. It is assumed that the sediment is deposited horizontally under the LWL. The LWL is determined in consideration of sediment volume and the sedimentation level and required water depth for the intake under the LWL. When the huge amount of reservoir sediment is estimated and power generation might be effected in spite of appropriate countermeasures, the Project Developer shall simulate a sediment configuration in the reservoir through mathematical analysis in order to estimate an actual sediment profile. 8

9 The Project Developer shall estimate the sediment volume deposited during 100 years after the dam completion through the two (2) different methods below. (1) Estimation by measured data of suspended load The work flow of estimation of sediment volume for 100 years is shown in the chart below. Collect measured data of suspended load Calculate annual suspended load & bed load Trap efficiency of the reservoir Calculate the average density of the sediment deposited in 100 years Estimate sediment volume for 100 years (2) Estimation by actual sediment records of existing dams When dams already exists near the proposed dam site and their sedimentation records are available, the sediment volume of the proposed dam site is estimated from the specific sediment yield, which is the sediment volume delivered to the reservoir from catchment area of 1 km 2 in a year (unit: m 3 /km 2 /year). If the condition such as climate, geology, topography and scale of reservoir are resemble in the proposed project site, the nearby sedimentation record can contribute to estimate the sediment volume with high reliability. 9

10 6. Geological, seismic and Construction Material Survey The Project Developer shall collect data and information on geology, seismicity and construction material covering the project area in order to 1) figure out geological conditions of the drainage area, dam site and waterway route, 2) study the reservoir water-tightness, 3) to identify possible landslide areas, 4) identify possibility of earthquakes and 5) study the availability of construction material such as dam embankment, concrete and aggregates. 6.1 Geologic survey and analysis Geological maps The Project Developer shall prepare the following geological maps, but not limited to, after the geologic surveys described in /5,000 geologic maps: the project area including dam, waterway, powerhouse, access roads for construction, quarry sites, borrow areas, temporary facilities and resettlement areas. 1/5,000-1/10,000 geologic plan: dam and reservoir area 1/5,000-1/10,000 geologic profile: dam and reservoir area 1/1,000-1/2,000 geologic plan and sections: dam and other power structures 1/5,000 geologic sections: quarry sites and borrow areas Aerial photo interpretation The Project Developer will be able to use aerial photos, if necessary for FS, not only for preparing topographical maps but also for a supplementary means of geologic survey through aerial photo interpretation Geologic surface reconnaissance Following literature survey and morphologic interpretation by both aerial photos and topographical maps, the Project Developer shall carry out the geologic surface reconnaissance with topographic maps below. 1/5,000 1/25,000 topographic maps: reservoir area and waterway route 1/1,000 1/2,000 topographic maps: dam, powerhouse and other structures Geologic surface reconnaissance shall observe and identify geologic and morphologic features on geological outcrops, overburdens and morphology as below; Geological outcrops Lithofacies including type of bedrocks, distribution of the stratum, joint pattern, characteristics of bedding and schistose planes and geologic ages Lithologic characters including hardness of bedrocks, conditions of weathering and alteration, conditions of crack/joint and remarkable phenomena such as secondary deposit and cavity Geologic structure including folding structure, faults, surface water and underground water Overburden Type of deposit, genesis, characteristics, distribution and vegetation Morphology Valley configuration Flat surface configuration Particular or unusual topography as karst, landslide and fault valley 10

11 6.1.4 Geophysical prospecting The Project Developer shall conduct geophysical prospecting such as seismic prospecting, electric prospecting, gravity prospecting and magnetic prospecting in order to identify the underground geologic and hydrologic structures. Seismic prospecting is a most generally method used for hydroelectric power projects. The length of prospecting lines shall be at least five (5) times longer than the depth to be prospected. Prospecting results shall be compared with drilled cores collected from drillholes located at intersecting points of prospecting lines and/or along the lines Drilling investigation The Project Developer shall conduct drilling investigation when the geologic surface reconnaissance and geologic prospecting are insufficient to get geologic and subsurface hydrologic conditions at dam, powerhouse and other structures. The Project Developer shall keep utmost technical efforts for full core recovery and store the recovered cores into specified core boxes. Through the drilled core observation, the Project Developer shall prepare drillholes logs to describe the following items. Geologic name (rock name, stratum name and surface deposit) Rock color with water-saturated Weathering, hardness, joint, solubility, swelling by water Drilling records (drilling speed and supply/drain water rate) Depending on actual geologic and topographic conditions, the number of drillholes at dam site is generally as below. Dam height 50 m : Total 5 drillholes including 3 holes at river bed & 2 holes at both river banks 50m < Dam height 100m : Total 7 drillholes including 5 holes at river bed & 2 holes at both river banks 100m < Dam height : Total 9 drillholes including 7 holes at river bed & 2 holes at both river banks The depth of drillholes at dam site is generally the same as dam height, depending on actual geological condition. The Project Developer will carry out permeability tests, seismic prospecting and horizontal loading test by using drilled holes. When seasonal ground water levels in dry and rainy seasons are key factors for the design of dam and other structures, the Project Developer shall monitor groundwater levels in the drillholes through a year Laboratory rock test The Project Developer will carry out laboratory rock tests according to international standards such as ASTM, BS, JIS and others using rock samples collected from drillholes. The following tests are generally conducted for FS of hydropower projects. 11

12 Specific gravity/absorption test, ultra-sonic wave test Unconfined compression test, Splitting tensile strength test, tri-axial compression test Other investigations In case 1) extremely high pervious layer or zone exists in the reservoir, 2) groundwater levels at river banks of dam site is lower than river water level, 3) there might be potential large leakage from the reservoir or dam abutment through limestone and/or karst zone, the Project Developer will carry out the following investigations on groundwater flows in order to secure the water-tightness of the reservoir or the dam safety. Simultaneous measurement of river discharges at multiple locations in the river Water quality measurement of river at multiple locations in a river to estimate flow routes of groundwater Tracing investigation of river flow with a colored material 6.2 Seismic survey and analysis The Project Developer shall collect and analyze historical seismic records, reports and information on seismic activities, geological formation and existence of faults in/around the project area, and then he shall determine the seismic design coefficient considering seismic activity level at the project area, geologic conditions of the structures foundation, existence of geologic faults and type of dam. When possible earthquakes might significantly affect the safety and stability of power facilities, the Project Developer shall further study dynamic seismic analysis for power facilities. 6.3 Construction material survey The Project Developer shall carry out construction material survey described below in order to 1) select the dam type such as RCC dam, concrete dam or embankment dam, 2) prepare preliminary designs for power structures and 3) prepare the construction planning and schedule Material for concrete dam and other concrete structures The Project Developer shall investigate the availability of ready-mixed concrete and concrete materials including cement, concrete aggregates and fly ash in terms of quantity and quality. For example, the concrete aggregates will be procured from quarries, river bed gravels, excavated rocks, and existing concrete plants, followed by quality tests such as specific gravity test, water absorption test, grain size distribution, Los Angeles test and alkali-aggregate-reaction test to confirm whether the materials to be procured will possess the required qualities for concrete aggregates as below. Sufficient hardness, strength and durability Adequate gravel diameter and size distribution Less than permissible levels of deleterious materials The Project Developer shall confirm whether fly ash used for RCC dam and other concrete structures will satisfy required qualities. If not, unsatisfied qualities of the fly ash shall be improved or modified through appropriate measures. The Project Developer shall investigate potential quantities at candidate quarry sites by geological maps, geologic surface reconnaissance, seismic prospecting and drillholes in order to confirm whether they have enough volumes of aggregates required for the project Material for embankment dam The Project Developer shall carry out the following tests for embankment materials to confirm whether the materials possess required qualities as well as their quantities. 12

13 Pervious and semi-pervious material: specific gravity test, water absorption test, grain size distribution test, uniaxial compression test Impervious material: natural water content, specific gravity test, liquidity/inelastic limit, grain size distribution test, compaction permeability test, triaxial compression test 7. Recommended Project 7.1 Project description The Project Developer shall provide detail features and descriptions on a recommended project scheme in accordance with the results of alternative study and optimization study. Required items of project descriptions are listed below. (1) Reservoir: catchment area (km 2), annual basin rainfall (mm), annual mean runoff (million m 3 ), reservoir surface area (km 2 ) at HWL, High Water Level (EL.m), Low Water Level (EL.m), gross reservoir capacity (million m 3 ), effective reservoir capacity (million m 3 ), available draw-down depth (m) (2) Main dam: dam type, dam height (m), dam crest length (m), dam width (m), dam volume (m 3 ) (3) Auxiliary dam: dam type, dam height (m), dam crest length (m), dam width (m), dam volume (m 3 ) (4) Intake dam/weir: catchment area (km 2 ), annual basin rainfall (mm), annual mean runoff (million m 3 ), intake water level (EL.m), dam type, dam height (m), dam crest length (m), dam width (m), dam volume (m 3 ) (5) Spillway: inflow design flood (m3/sec), type of spillway gate, number and size of spillway gates (6) Power intake: location and type of power intake, type of intake gate, number and size of intake gate (7) Headrace/Tailrace tunnel: number of tunnels, length and diameter of tunnels (m) (8) Headrace/Tailrace channel: number of channels, length and size of channels (m) (9) Head tank/surge tank: type of tank, size of tank (m) (10) Penstock: number of penstocks, type of penstocks (tunnel or exposed), material of penstocks, length and diameter of penstocks (m) (11) Power plant: design power discharge (m 3 /sec), rated head (m), plant capacity (MW), power supply for domestic use and/or export (MW), annual power generation (Gwh), type of powerhouse (open or underground), size of power house (m) (12) Turbine: type of turbines, number of turbines, rated output (MW)/rated head (m)/rated speed (rpm) of turbines (13) Generator: type of generators, number of generators, rated output (MVA)/rated speed (rpm) of generators, power factor of generators (14)Transformer: type of transformers, number of transformers, voltage ratio (kv), rated capacity 13

14 (MVA) of transformers (15) Transmission line: type and length (km) of transmission line (16) Substation: type of substation, size of substation (m) (17) Access road/bridge: length and width of permanent access road/bridges (m) (18) Resettlement/relocation: number of villages, number of households, number of people, relocation of existing road or bridge (19) Environmental/ecological flow: flow discharge (m 3 /sec), discharge method, length of recession area of the river (km) (20) Economy: total project cost (million USD), unit cost (USD/kw), EIRR, FIRR 7.2 Preliminary Design Hydropower civil engineering facilities According to Chapter 2 of LEPTS the Project Developer shall design hydropower civil engineering facilities for the recommended project in the following manners and prepare design drawings of plans, profiles and typical sections for dam/intake weir, intake, headrace, head tank/surge tank, penstock, powerhouse and outlet/tailrace. The Project Developer will prepare and submit structural calculation reports and/or stability calculation reports of dam, spillway and other key structures, if requested by MEM or PDEM. To use topographical maps of 1/1000-1/2000, To base on the results of hydrological survey and analysis, To decide physical/geotechnical properties of rocks and construction materials by accessing results of geotechnical investigation, various tests and literature survey To set up design criteria including design loads and safety coefficients for assumed design conditions, When the hydropower project is planned to locate its dam at the Mekong mainstream in the Lower Mekong Basin, this preliminary design shall be in compliance with the document Preliminary Design Guidance for proposed mainstream Dams in the Lower Mekong Basin (Mekong River Committee, 2009 August) in order to prevent any social and environmental impacts or other potential risks in the four MRC member countries. The impacts and risks are particularly with respect to navigation, fisheries, sediment transport and river morphology, water quality and aquatic ecology, and safety of dams. For the preliminary design the Project Developer shall study the following points for respective facilities, but not limited to. Main dam and auxiliary dams: its location in topographical and geological/geotechnical points of view, alternatives of dam types, availability of dam body materials, foundation treatment including gallery and grouting, method of river diversion, floods during construction, instrumentation during construction and after completion Intake dam/weir: its location for placing intake and settling basin, geological/geotechnical condition, access for maintenance 14

15 Spillway: its location and types, cavitation during discharging, operation rule of spillway gates during floods, downstream effects during discharging, Intake: its location and alignment not to breathe air or flow in whirls, flow capacity and velocity, structure types, geological and geotechnical conditions Headrace/Tailrace: its alignment, flow capacity and velocity, structure types, geological and geotechnical conditions for tunnel, lining pattern for tunnel, landslides and/or flush floods for headrace, maintenance after completion Head Tank/Surge Tank: its location, structure types, tank capacity, geological and geotechnical conditions, access for maintenance Penstock: its alignment, materials of penstock pipes, flow capacity and velocity, structure types, geological and geotechnical conditions, installation method of penstock pipes, access for maintenance, instrumentation after completion Powerhouse: its location, geological and geotechnical conditions, safety against floods during construction and after completion, cavern stability and supporting design of underground powerhouse, installation method of turbine and generators, regulating pond/dam downstream, warning system at the time of power discharging Reservoir: flood management system including rainfall/inflow monitoring method, discharge process and measures from spillway, warning system to downstream communities, environmental discharge, reservoir operation rule, water sharing rules between power, irrigation, industrial water, navigation and tourism Others: capacities of disposal areas and its utilization after completion, utilization plan of temporary facilities areas after completion, utilization and plantation plans of borrow areas and quarries, resettlement plans, tree trimming plan in the reservoir area before impounding the reservoir Hydro-mechanical facilities According to Chapter 2 of LEPTS the Project Developer shall design hydraulic gates, high pressure valves and trash-racks such as spillway gate, intake gate, sediment flush gate, draft gate, outlet gate, fish-way gate, navigation lock gate, conduit valve, outlet valve, etc. in the following manners. To select the type, shape, size and number of hydraulic gates and valves To select the type of hoisting device of hydraulic gates To determine operating conditions of hydraulic gates and valves in normal and emergency cases Electro-mechanical facilities The Project Developer shall determine the type, number and specification of turbine, generator and other electrical facilities in consideration of design power discharge with planned monthly available output and effective heads with water volume. According to Chapter 3 of LEPTS the Project Developer shall design turbines, generators, main transformers and their auxiliary facilities, followed by the preparation of drawings presenting layout plans of electrical facilities at power station and substation. Environmental conditions shall be carefully studied and adequate countermeasure shall be provided. Major items to be concerned are as follows; 15

16 Vibration and noise from turbine/generator and transformers. Oil/water separation system for turbine/ generator and transformer. Firefighting system for the necessary place, Indoor type Vacuum Circuit Breaker (VCB) for medium voltage, The Project Developer shall prepare general arrangement and single line diagram for the power station in view of technical, economical, energy conservation and reliable points as below: Applicable standard: IEC and/or LEPTS Number and capacity of generators Synchronous generator [kva], [V], [SCR] with pf=0.8 Selection of transmission line voltage Communication method of Remote Terminal Unit (RTU) for SCADA with Load Dispatching Center (LDC) Building code or standards of Lao PDR for powerhouse? Safe and easy operation and maintenance? Transmission line The Project Developer shall study and determine an optimal route of transmission line with right of way and connection point to the existing substation. Sectional view and river crossing if any, shall be provided by using 1/5,000 topographical maps in consideration of meteorological data. Highest point of the transmission line shall be indicated. Following certificate and agreement shall be concluded by the end of feasibility study. Environmental certificate issued by MONRE Agreement on transmission line issued by EDL. According to Chapter 3 of LEPTS, the Project Developer shall design transmission system including substation and connection point to the existing substation with their auxiliary facilities, and then prepare drawings presenting layout plans of electrical facilities. Control and protection relay panel related to the existing substation may be provided. Environmental conditions shall be carefully studied. Major items to be concerned are as follows; Number of resettlement households Legal restrictions of land uses No passage to the environmental protected area Height of overhead conductors Crossing points to the existing 22/115/230/500kV lines Oil/water separation system for transformer with fire-fighting system Indoor type VCB for medium voltage and outdoor type SF6 CB for 115, 230 or 500kV system Optical fiber overhead ground wire (OPGW) The Project Developer shall prepare general route map, detail route map with right of way, details of crossing section at the river and road. Technical items to be concerned are as follows; Local development plans and future project such as road, other public facilities Short circuit current and other system requirement Communication method of RTU for SCADA with LDC Protection and insulation coordination to the existing facility? Alternative transmission line route and connection point? Seismic zone map Requirement of Lao Grid Code? 16

17 Safe and easy operation and maintenance? According to Section 3-5 Transmission Lines of LEPTS, the Project Developer shall select overhead conductors, supporting structures, etc. considering design manual of transmission system of EDL. In case the hydropower project will be linked to the national grid of Lao or neighboring countries, the PD shall conduct the power system analysis in order to confirm reliability, power flow and short circuit current List of Drawings of Preliminary Design General layout covering dam, reservoir, waterways, powerhouse, transmission line, access roads, temporary facilities, disposal areas, borrow areas and quarries General plan of dam, auxiliary dam, intake dam/weir Upstream and downstream view of dam, auxiliary dam, intake dam/weir Typical sections of dam, auxiliary dam, intake dam/weir Foundation treatment plan of dam River diversion method Plan and profiles of spillway section and stilling basin/energy dissipator including spillway gates Plan and profiles of power intake including intake gates Plan and profiles of sediment settling basin Plan and profiles of headrace tunnel or headrace channel Plan and profiles of head tank or surge tank Plan and profiles of penstocks Plan, profiles and floor plans of powerhouse Plan and profiles of tailrace and outlet Floor arrangement plans and profiles of electro-mechanical equipment including turbines, generators and auxiliary equipment Plan and profiles of switchyard including arrangement of electrical equipment Overall single line diagram including transmission and substation to be connected Single diagram of power station Route map of transmission line with right of way Highest point of transmission line Profiles of transmission tower including foundation bases Sectional views of transmission line at river crossing points, if any Plan and profile of disposal areas Plan and profiles of borrow areas and quarries General layout plan of temporary facilities including camps, concrete plant, turbid water treatment plant, steel processing yard, parking lots for construction equipment, warehouses, and other facilities 7.3 Construction Plan and Implementation Schedule 7.3.1Basic data for construction plan and schedule The Project Developer shall collect the following data and information prior to preparation of construction planning and schedule. Meteorological data including temperature, rainfall, number of rainy days, etc. Hydrologic data including flood discharge, frequency of floods, etc. River water properties including temperature, quality, turbidity, ph Topographical and geological maps of 1/5,000 covering project facilities and temporary facilities Site conditions including geographical location of the project and living conditions in its vicinity Construction conditions including availability of construction machines, materials and labors 17

18 Transportation conditions of roads and bridges near the project area Electricity for construction including availability of existing power transmission lines near the project area Construction plan and schedule The Project Developer shall prepare construction/installation plans and schedules of the following works in consideration of local meteorological/hydrological conditions, transportation/shipping conditions and availabilities of construction materials/machine and workers. Preparatory works including access roads, temporary bridges and distribution lines for the construction Temporary facilities including camps, concrete plant, turbid water treatment plant, steel processing yard, parking lots for construction equipment, warehouses, and other facilities Civil works of dam, waterway, powerhouse, etc. Electro-mechanical works of turbines, generators, transformers and auxiliary equipment Hydro-mechanical works of gates, valves and steel penstocks Transmission line works Resettlement works Environmental mitigation works and safe-guard measures works All main milestones and risks shall be clearly identified and addressed; in addition, the critical path shall be indicated in the construction schedule. Main milestones are summarized below, but not limited to. Completion of dam excavation Commencement of river diversion Commencement of initial reservoir pounding Commencement of dry test of electro-mechanical equipment Commencement of wet test of electro-mechanical equipment Commencement of commercial operation 7.4 Project Cost The Project Developer shall estimate the project cost by local currency (LAK) and foreign currency (US$), present the total construction cost in US$ by changing the cost for local currency (LAK) to foreign currency (US$), and prepare a summary of the project cost shown in the following table as well as Bill of Quantity sheets by work items. Bill of Quantity sheets for respective work items shall indicate lengths, number, volume and weight of concrete, excavation, steel bars, and other construction materials. When work items such as hydro-electrical equipment cannot be expressed as above, their lump sum prices are accepted. The Project Developer shall describe clearly 1) how the above respective cost items are estimated and 2) how the unit costs are derived,. The Project Developer shall also prepare the disbursement schedule of the project cost according to the construction schedule stated in Construction Plan and Schedule. 18

19 Cost Item Work Item 1. Base Cost 1.1 Development cost Feasibility study, Basic design & Detail design prior to construction 1.2 Preparation works & temporary facilities Access roads, temporary bridges, distribution lines for the construction, camps, concrete plant, turbid water treatment plant, steel processing yard, parking lots for construction equipment, warehouses, and other faciliti 1.3 Land acquisition & compensation Cost for land acquisition, land lease and compensation for local villages and local people during construction as well as during operation 1.4 Safeguarding works Environmental mitigation works to safeguard the environment to be affected by the project 1.5 Civil works Main dam, auxiliary dam, spillway, intake weir/dam, sediment settling basin, intake, headrace tunnel/channel, surge tank/head tank, penstock, powerhouse, tailrace tunnel/channel, outlet 1.6 Hydro-mechanical equipment Hydraulic gates, high pressure valves and trash-racks such as spillway gate, intake gate, sediment flush gate, draft gate, outlet gate, fish-way gate, navigation lock gate, conduit valve, outlet valve, trash-racks, steel penstocks 1.7 Electro-mechanical equipment Turbines, generators, transformers and auxiliary equipment 1.8 Transmission and distribution line works Transmission line, distribution line, steel tower structures, electricity concrete poles 1.9 Administration cost Administration cost for headquarter and site office 1.10 Engineering service cost Construction drawings and construction supervision 1.11 Physical Contingency Unexpected increase of work volume/quantities Sub-total Total of Basic Cost 2. Price contingency Unexpected increase of unit cost 3. Taxes & Royalties 4. Interest during construction Total Total of 1, 2, 3 and 4 19