3 sanakham hydropower project updated fs report€¦ · 3. earthquake safety updated of fs report...

1

2018/10/30

Lao Mekong Sanakham Hydropower ProjectUpdated FS Report

CONTENTS

Design and investigation process

Design standards

Updated FS Report based on CNR review

Discussion of critical issues

Design and investigation process

Design standards

Updated FS Report based on CNR review

Discussion of critical issues

Design and investigation process Design and investigation process

In December,2007MOU

In July,2009The cascade planning optimization of Mekong river in Laos

In August,2010The Pre-FS Report was approved by CREEI

In May,2011The FS Report was approved by CREEI

In December,2011The FS Report was finally approved by Ministry of Energy and Mines, Lao PDR.

Design and investigation process Design and investigation process

In JUNE, 2014FS for Independent Review

In November,2015The Updated FS Report was finally approved by Ministry of Energy and Mines,

Lao PDR.

Project Layout Project Layout

Dam type: Concrete dam Water retaining structure: Left auxiliary dam, ship lock, left flood sluice, powerhouse, right flood sluice, fish pass, right auxiliary dam Dam crest length: 909.9mMax. dam height: 56.2m

泄洪闸坝段 1～13#250m

船闸36m

左岸副坝70m

厂房坝段（1～12#机组段及安装间）352.2m

泄洪闸坝段 14～18#98m 右岸副坝

80m

886.2m

100m 36m 250m 350.2m 91.5m 82.2m

909.9m

229.5

Shiplock Sluicing gate PowerhouseBottom outlet Fish way

sand sluice

Project Layout Project Layout

Updated FS Report is in compliance with following standards:Updated FS Report is in compliance with following standards:

Lao Electric Power Technical Standards; Preliminary Design Guidance for Proposed Mainstream

Dams in the Lower Mekong Basin, and related MRC regulations;

Periodic Technical Bulletins on the Safety of Dams issued by the International Commission on Large Dams (ICOLD) ;

World Bank, Operational Policy 4.37; International standard：ACI、ASTM、US Army Corps of

Engineers、United States Bureau of Reclamation，etc. China Power Industry Standard;

Design Standards Design Standards

Hydrology Hydrology

1.Hydrological data

Updated of FS Report based on CNR review Updated of FS Report based on CNR review

Previous FS Report Updated FS Report

Run off data 1923~2004 1923~2012

Flood data 1923~2004 1923~2008

During 2009~2012, 4 sets of water gauges had been established at the damsite, mainly to measure water levels;

Level & discharge were measured in 2015

2. Runoff2. Runoff

Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec. Annual Remark

1690 1340 1150 1170 1670 3380 6860 11600 10800 6570 3830 2350 4390 This Review（1923-2012）

1690 1340 1150 1160 1650 3420 6920 11800 10900 6570 3840 2350 4410Feasibility

Study in 2011（1923-2004）


It can be found that this review result of the long term monthly averagedischarge is similar to the result of the feasibility study in 2011.It can be found that this review result of the long term monthly averagedischarge is similar to the result of the feasibility study in 2011.

2. Runoff2. Runoff

Mean（m3/s)

Xp(m3/s)Remark

5% 10% 25% 50% 75% 90% 95%

4390 5680 5360 4860 4340 3860 3460 3240 This Review（1923-2012）

4410 5720 5400 4900 4380 3890 3480 3260Feasibility Study in

2011（1923-2004）

-0.45 -0.70 -0.74 -0.82 -0.91 -0.77 -0.57 -0.61 Relative Error(%)


It can been seen that the difference between this review result of designrunoff and the feasibility study result in 2011 is slight less than 1%.It can been seen that the difference between this review result of designrunoff and the feasibility study result in 2011 is slight less than 1%.

Hydrology Hydrology

3.Impact of upstream hydropower stations on Sanakham HP


Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec.

Natural 1690 1340 1150 1160 1650 3420 6920 11800 10900 6570 3840 2350

Affected by upstream reservoirs

2453 2147 1938 1795 2043 3360 5594 9607 9995 6376 3706 2903

4. Flood4. Flood


Exceedance Probability(%) T(years)

Flood Flows at Sanakham project

1994 Study Estimations

DeveloperEstimations

MRC-CNR Estimations

50 2 16300 16200

20 5 19400 19000

10 10 23580 21300 21100

5 20 22900 23000

2 50 25000 25500

1 100 28780 28400 27200

0.5 200 29900 29000

0.2 500 31700

0.1 1000 33880 33100 33000(30900-34900)

0.05 2000 34400 34700(32500-36850)

0.02 5000 36100 37000(34550-39450)

0.01 10000 37300 38800(36150-41400)

It can been seen that the floodcalculation method adopted by HXECis similar to the calculation methodadopted by MRC-CNR and thedifference between the developerestimations and MRC-CNRestimations is very small, themaximum of which is less than3.87%,the minimum is only 0.86%.

It can been seen that the floodcalculation method adopted by HXECis similar to the calculation methodadopted by MRC-CNR and thedifference between the developerestimations and MRC-CNRestimations is very small, themaximum of which is less than3.87%,the minimum is only 0.86%.

5. Rating Curve5. Rating Curve

194.00

198.00

202.00

206.00

210.00

214.00

218.00

222.00

0 5000 10000 15000 20000 25000 30000 35000 40000

H(m

)

Q(m3/s)

Data of 2015

Data of 2010

Flood data of 2008

Review(adopted)

Feasibility Study in 2011


Sediment Sediment1.Sediment Sampling

• In May 2015, sediment sampling andtesting works was initiated.

• Taking sediment samples twice permonth.

1.Sediment Sampling

• In May 2015, sediment sampling andtesting works was initiated.

• Taking sediment samples twice permonth.


198

5-12.5x16

As for the proposal by CNR experts, the bottom elevation of the right five outlets has been lowered to 192.0, from 198.0m, which would improve sand flushing efficiency.

2. Adjustment of sand flushing facilities design


192

13-15x22

3. Calculation with mathematical model

• The outflow sediment content is basically consistent with the inflow value, and in the initial period, the sand discharge rate would surpass 70%;

Morphology for 2-D water-sediment mathematic model simulation


With the two flood sluices respectively arranged at left and right wings, the flood discharge and sand flushing efficiency is rather efficient; the right sluice is located at the thalweg of the original river channel, with small amount of deposits in front of the dam, the sand flushing efficiency is sound.


• Deposition thickness in front of sluice

• Deposition thickness in front of powerhouse

A sand barrier will be set in front of the power intake, each unit dam section will be arranged with one sand outlet which could timely flush fine sand accumulated at the intake front towards downstream, and coarse sand will be intercepted in front of the sand barrier.


• Deposition depth at upstream approach channel

Deposition at the upstream approach channel would be mainly affected by the backflow zone, mainly distributed at the inner side of the guide wall, deposition at the outer side can be basically flushed out during releasing flood. However, after 20-year operation, the minimum water depth at the upstream approach channel would still be deeper than 4.0m, which is satisfactory to the PDG’s demand. When navigation is affected, deposition could be artificially cleared off with the reservoir drawdown.


After 10-year operation of the reservoir in the proposed mode, the sediment accumulation in the reservoir area would amount to 127 million m3, with an average sediment discharge ratio of 77.8%, the average sediment content in the outflow water after sediment settling in the reservoir is 0.386kg/m3, only about 22.2% lower than the natural scenario.

After 50-year operation, the average sediment accumulation at the dam front is about 3m deep, averagely up to the elevation of 197.2m. The sedimentation in the reservoir area would not bring about threat to the operation safety of the power plant and the ship lock.

4. Reservoir Sedimentation Calculation4. Reservoir Sedimentation Calculation


150

160

170

180

190

200

210

220

230

0 10 20 30 40 50 60 70 80 90 100

Distance(km)

Elevation(m)

Thalweg

Sediment profile

Backwater profile at mean annual

Natural water profile at mean annual

Backwater profile at P=33.3%

Natural water profile at P=33.3%

Backwater profile at P=20%

Natural water profile at P=20%



Pak Lay damsite

Pak Lay town

150

160

170

180

190

200

210

220

230

0 10 20 30 40 50 60 70 80 90 100

Distance(km)

Elevation(m)

Thalweg

Sediment profile

Backwater profile at mean annual

Natural water profile at mean annual

Backwater profile at P=33.3%

Natural water profile at P=33.3%





Pak Lay damsite

Pak Lay town

Longitudinal Profiles of in Reservoir

When the water level in front of the dam is at EL. 220m , the backwater level at Pak Lay Power Station would be raised by 0.0~4.16m;

under the annual average discharge of 4410 m3/s, the level incremental due to backwater would be 0.07m;

when the discharge exceeds 5801m3/s , backwater level would have no impact on Pak Lay Power Station.

Backwater – Discharge Relation at Pak Lay Station

5. Impact on Pak Lay hydropower station5. Impact on Pak Lay hydropower station


6. Sedimentation monitoring plan

In order to monitor and analyze the impacts of reservoir sedimentation, the following items shall be observed in light of main reservoir sediment problems:

• Inflow and outflow sediment/water;• Changes of the sedimentation before dam and in reservoir;• Water surface profile of reservoir;• Change of erosion & deposition and collapse of reservoir bank.• Monitoring dam downstream erosion during the initial reservoir operation

period; • Monitoring deposition at upstream and downstream approach channels.

Project Management Plan

Construction supervision plan

Prepared in FS stage

Instrument plan

Operation and maintenance

plan

Quality assurance

plan

Emergency preparednes

s plan

Improved in construction stage

Dam Safety Management System

Dam safety1. Dam Safety Management System

Dam safety1. Dam Safety Management System


2. Design Criteria

• The Lao Electric Power Technical Standard（LEPTS）

• Preliminary Design Guidance for Proposed Mainstream Dams in the

• Lower Mekong Basin，Aug ,2009

• The International Commission on Large Dams （ICOLD)

• World Bank, Operational Policy 4.37

• International standard：ACI、ASTM、US Army Corps of Engineers、

• United States Bureau of Reclamation，etc.

• Chinese Standard

Dam safety Dam safety


• No earthquake above 5 magnitude has ever occurred within

100km of the dam site in 553 years;

• Seismic safety evaluation had been completed by the

Earthquake engineering research institute of Yunnan (China);

• The horizontal seismic peak ground acceleration for standard of

design and check is 0.063g (ah) and 0.1g (ah), respectively.

• No earthquake above 5 magnitude has ever occurred within

100km of the dam site in 553 years;

• Seismic safety evaluation had been completed by the

Earthquake engineering research institute of Yunnan (China);

• The horizontal seismic peak ground acceleration for standard of

design and check is 0.063g (ah) and 0.1g (ah), respectively.

Dam safety

3. Earthquake safety

Dam safety

3. Earthquake safety


Dam type Work condition

Return period(year)

Flood discharge(m3/s)

Gravity dam

Design flood 2000 34700

Check flood 10000 38800

The proposed maximum navigable water level for navigation structures is based on 3-year frequency floods.


• Dam safety

4. Flood Standard

• Dam safety

4. Flood Standard

5-Right Bank sluices,Size 12.5mx16m

13-Left Bank sluices,Size 15mx22m Check flood: 38800m3/s

Design flood: 34700m3/s

Max. flood level upstream of the dam is 6.2m lower than the dam crest elevation.


Dam safety

5. Safe passage of flood

Dam safety

5. Safe passage of flood

10000-year flood with two outlets closed during flood discharge，Max. flood level upstream of the dam is 4.9m lower than the dam crest elevation.

• The envisaged second-stage shiplock arrangement and estimated cost are included.

• Navigation design during construction period is included.

• Sanakham HPP will be operated for power generation at inflow rate without consideration of reservoir capacity regulation and dead water level is designed for multiple operation choices. Generally, the normal operation level is maintained at EL.220.0m.

• The one-way lockage time：T=5 (entrance) + 2(lock closing) +10 (filling or water release) +2 (lock opening)

+4(exit) +5 (interval)=28 min＜30min

Navigation Navigation


Additional explanation on the lengths of the upstream and downstream approach channels and flow velocities in the channels has been reflected. Measurement and justification of flow velocities at the entrances of the upstream and downstream approach channels will be made in the next stage on the physical hydraulic model test or numerical simulation model based on the adjusted sluice structure arrangement.

As requested by PDG, the fire control requirements for the ship lock equipment are added.

As requested by PDG, the service life of gate parts is added.



Fish way Fish way


With reference to the latest investigation on fish and historical data, we studied the kinds, quantity of fish resource, and living habit. And referring to the experience on the world, A natural-like fishway is selected.

Passages for fish passing through Sanakham dam: fishway, turbine, sluice.Turbine generators for Sanakham are bulb type units, which are environmental friendly.With 18 flat-bottom flood sluices arranged for Sanakham, the upstream-downstreamlevel difference during the flood release period would be not much.

Fish way Fish way


flood sluice gate section

powerhouse section

Fish passWidth :5m;Length:2.39kmSlope:0.075%

Switchyard

flood sluice gate section

Exit

Blocking fish with electric screen

Entrance 1MEKONG

Namhueng

Entrance 2

Monitoringroom

Lure fisfacility


Fish way Fish way

Water quality Water quality


Based on the study and research on the velocity, depth, flow, and other hydrological data, together with the pollution source and present water quality, we predict the changing trends of water quality during the operation period. In order to ensure water quality safety, we propose the following environment protection measure, and monitoring plan:

• The tributaries protection both upstream and downstream the dam including the Nam Tha , Nam Ngao, Nam Ing and Nam Beng River.

• Cleaning of reservoir zone before impoundment.• Water treatment of sewage.• According to the MRC and EMMP, environmental management and monitor plan is presented .

The parameter include: Temperature, pH, Dissolved oxygen, Biochemical oxygen demand, Total nitrogen, Total phosphorus, Total solids, Transparency, Chlorophyll-a, Coliforms, Harmful substances, and so on.


Maximum longitudinal forces are designed according to China’s “Ship lock water conveyance system design specification”（JTJ306-2001) standard, and on this bases we compare the design between china standard and the USA standard, it is show in the table below:

Discussion of critical issues Discussion of critical issues

Comparison between hawser force design

And also the hawser force of 500t vessel is obtained from physical test, the maximum hawser force is 16KN, it is less than the allowable force(25KN), so the design is safe.

Thank you for your attention!Thank you for your attention!

3 sanakham hydropower project updated fs report€¦ · 3. earthquake safety updated of fs report...

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