PakBeng Hydropower Project Updated FS · PDF filePakBeng Hydropower Project Updated FS Report...

August 2015

PakBeng Hydropower Project Updated FS Report

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Pak Beng HPP

Table of Content • Summary • Design standards • Updated FS Report based on CNR review • Discussion of critical issues

In Mar, 2013 Technical Report (FSL 340m, installed capacity 912MW)

In January 2010

Technical Report (FSL 340m, installed capacity 855MW)

In December 2008

FS Report (FSL 345m, installed capacity 1230MW)

In December, 2007

KHIDI Contract.

In August, 2007

MOU

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Design and investigation process

In AUG, 2015

Updated FS.

In JUNE, 2014

FS for Independent Review

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Design and investigation process

Project Layout

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lock

sand sluice

discharge sluice

sand barrier

Bottom outlet

powerhouse

Fish way

Project Layout

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lock

sand sluice

discharge sluice

Bottom outlet

intake

Fish way

Design 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;

China Power Industry Standard;

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Updated of FS Report based on CNR review

Hydrology

1.Hydrological data

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Previous FS Report Updated FS Report Run off data 1960~2004 1960~2014 Flood data 1960~2004 1960~2008


Hydrology

2. Rating curve at the dam site KHIDI established 4 groups of stage gauges near Pak Beng Dam Site, the measured series from

2008 ~2014.

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295

300

305

310

315

320

325

330

335

0 2000 4000 6000 8000 10000 12000 14000 16000

H（m）

Q（m3/s）

Calculated by Interzone Method

Rating Curve Adopted

Measured Discharge


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Hydrology 3. Impact of HPP located upstream Pak Beng project In this stage, discharge at Pak Beng dam site is extended to Jun 1960-May 2014. During

the design we have consider the influence of upstream Cascade.


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Hydrology

4. Planned operation pattern


Hydrology

5.Automatic system of hydrological data

collection and transmission

The new version of Automatic system of

hydrological data collection and transmission has

been compiled, and submitted as Appendix 4A.

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Sediment

1.Sediment Sampling After Independent review by CNR, according

to the Expert opinion, Suspended load sampling

was carried out at Pak Beng hydrologic station

during 25 June.

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Sediment

1.Sediment Sampling According to the expert's opinion, CNR sampling result is adopted during the design.

KHIDI will carry out the daily sediment tests, Monitor sediment concentration at Pak

Beng station immediately, and make another Suspended load sampling when the

discharge is big and sediment concentration is high, and adjust our result.

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Updated of FS Report based on CNR review Sediment 2. Reservoir sedimentation

According to the sediment grading result, one-dimensional model has been corrected, and the parameter sensitivity analysis is added. Two-dimensional sediment mathematical model of the project area and three-dimensional sediment mathematic model are carrying out and will provide the latest research results and subjective report after it complete.

Physical model test have been commissioned to Sichuan university, after the completion of the work will provide a research report.

Sediment tour gauging are carrying out in Pak Beng station, Test item includes sediment concentration and grading.

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Sediment

3. The design of the spillways CNR Comments “The design of the spillways as well as the outlet works has to be

improved according to the recommendations suggested by CNR. Physical modeling of the

dam area is required in particular to refine the positioning and the sizing of the dam gates

(i.e. surface spillway, low-level outlets and bottom outlets for sand flushing).”

Two low level sand sluice gates are added on the project layout(show in project layout),

bottom elevation is 302m.

Detailed instructions about this problem refer to Discussion of critical issues.

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Sediment 4. Sediment management

Sediment management report have been compiled, Detail design of sediment

management strategies are shown in Appendix4C-SEDIMENT MANAGEMENT.

Sediment management strategies include: Dam operation for sediment discharging,

sediment flushing measures, time selection of sediment flushing and Eco-friendly flushing

for sediment, etc.

Through the above measures can reduce or avoid the impact on the river due to the

construction and operation of power station .

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Sediment

5. Sediment monitoring Overall design report of sediment monitoring system have been compiled, show in

Appendix 4B. Additional details regarding techniques, devices and survey frequency are

include in the report.

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Sediment

5. Sediment monitoring Main items of the sediment observation include:

• (1)Monitoring water and sediment in/out the reservoir;

• (2)Monitoring of water surface line in front of the dam and at the tail section of the

reservoir;

• (3)Monitoring of sediment deposition in the reservoir area;

• (4)Monitoring of sediment deposition in the project area;

• (5)Monitoring of downstream river course;

• (6)Monitoring of bank deformation in the reservoir area. 19


Dam safety For dam safety, the best International practice is adopted. Our design, engineering, construction and operation of the plant are in accordance with the following standards : Lao Electric Power Technical Standards; The World Bank Operational Policy 4.37 on the Safety of Dams; Periodic Technical Bulletins on the Safety of Dams issued by the International

Commission on Large Dams (ICOLD) Preliminary Design Guidance for Proposed Mainstream Dams in the Lower Mekong

Basin, and related MRC regulations;

China Power Industry Standard;

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Dam safety The following management document will be finished and updated as work going on: (i) a construction supervision plan (ii) a quality assurance plan (iii) an instrument plan (iv) an operation and maintenance (O&M) plan, and (v) an emergency preparedness plan (EPP). All of these will be the guide line for our actual work to ensure dam safety.

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Navigation After the final review of CNR the final design of navigation lock is shown below.

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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, by pass channel of fish passage is selected.

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Updated of FS Report based on CNR review Fish passage

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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:

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

2、Cleaning of reservoir zone before impoundment. 3、Water treatment of sewage. 4、 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.

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Discussion of critical issues

Sand sluice The CNR experts suggested some comparatively large bottom outlets for discharging coarse sediment. But we suggest design with two bottom outlets of present size, not larger outlets, based on the following consideration: -- Comparatively large bottom outlets will be operating comparatively unsteady under water; --- Comparatively large bottom outlets will cause the downstream water level changing dramatically, this is a thread to downstream navigation. -- The lower outlets operate, the more problems would occur, such as blockness and abrasion .

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Sand sluice Sediment deposition in the reservoir area is controlled by the operating water level of the power station, to add low level outlets or to reduce the elevation of spillway will only improve the situation of sediment at the dam base partially, and will not solve the problem of Sediment deposition in the reservoir completely. Compared the design with the added now two bottom outlets with previous design without bottom outlets at this position, we did two-dimensional sediment mathematical model of the project area, the result shows that:

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Sediment flushing effect without the sand sluice gates

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Sediment flushing effect with the sand sluice gates

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Sand sluice • We think it is not so effective, in terms of flushing, to add the two low level sand sluice

gates, secondly investment increase a lot, thirdly the two low level sand sluice would operate with potential risk.

• So we suggest that we do not add the two low level sand sluice gates, and the previous design will be adopted.

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Navigation According to MRC guidelines and the review comments of CNR, the design reference of codes and norms are as following: According to China’s “Overall design specification of navigation lock”, the occurrence probability of maximum water head of navigation lock is only 5%, so it won’t last long. And after the next cascade dam is built the downstream water level will be EL.310m, so the navigation lock water head is under 30m at most time.

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Discussion of critical issues Navigation

During the design process of navigation lock the following tests have been done;

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Navigation Data collection equipment

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Navigation Valve test video

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Discussion of critical issues Navigation

Conclusion: Based on the physical model results of navigation lock, the operation conditions under different conditions are reasonable, so when the maximum water head occurs the one step navigation lock can operate safely. And in China and world many navigation locks of water head exceeding 30m have been built and comes into service, so the design of ship lock (water head exceeding 30m) can also operate well, the examples are as follows:

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Navigation Five-step ship lock of Three Gorges on Yangtze River

The maximum water head of the middle step is 45.2m

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Navigation Ship lock of Wan An HPP on Ganjiang River (in Jiangxi Province)

The maximum water head of lock is 32.4m 37


Navigation Ship lock of Yin Pan HPP on Wujiang River (in Chongqing Municipality)

The water head of lock is 36.46m.

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Navigation water head over 30m on the world

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No. HPP Name Country Type Max. Head (m) 1 Uuski-Camino Alsky HPP Soviet Union One-Step Lock 42.0

2 Walter Pudding HPP U.S.A One-Step Lock 39.6

3 Dnieper HPP Soviet Union One-Step Lock 38.7

4 Calem Batllo HPP Portugal One-Step Lock 34.5

5 John Day HPP U.S.A One-Step Lock 34.5

6 Vale Ira HPP Portugal One-Step Lock 33.0

7 Sobral Reading HPP Brazil One-Step Lock 33.0

8 Pavlov HPP Soviet Union One-Step Lock 32.0

9 Lower Granite HPP U.S.A One-Step Lock 32.0

10 Ice Harbor HPP U.S.A One-Step Lock 31.4

11 Lower Monumental HPP U.S.A One-Step Lock 31.4

12 Little Goose HPP U.S.A One-Step Lock 30.8

13 New Wilson HPP U.S.A One-Step Lock 30.5

14 Perumishin HPP Brazil One-Step Lock 30.3


Navigation 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:

Comparison between hawser force design And also the hawser force of 500t vessel is obtained from physical test, the maximum hawser force is 16.5KN, it is less than the allowable force(25KN), so the design is safe.

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Thank you

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