Pipeline Project

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Z engwen/ N anhua Interconnecting Pipeline Project

Southern Region Water Resources Office, WRA, MOEA

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10-day

Water Outage

due to an Earthquake in 2016

The rainfall from August 2014 to March 2015 was at an all-time- low since records began in 1947.

6-month

Water Rationing Nanhua Reservoir in April, 2015 Tainan Cty

in Feb. 2016

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1 2

Outline

Water Usage Issues in Southern Taiwan Main Content of the Pipeline Project

3 3 Crucial Issues in the Left Abutment

of the Dam & Our Assessment

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經濟部水利署南區水資源局 4

Water Usage Issues

in Southern Taiwan

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Water Use in Southern Taiwan

嘉義台南高雄

屏東

Chia-yi County

Tainan City

Pingtung County Kaohsiung

City

280,000

(tons/day)

920,000 1,600,000 160,000

Here we are:

Zengwen Reservoir

Domestic & Industrial Water Usage

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Current Situation of Water Supply

Kaohsiung Tainan

Nanhua Reservoir

Zengwen Reservoir

Wushantou Reservoir

60%

40%

existing Nanhua-Gaoping interconnecting pipeline

(backup max. 500,000 CMD raw water for Kaohsiung)

920,000 CMD

Chia-yi

70,000 CMD

Backup treated water for Tainan

Effective Capacity 509million m³

Eff. Capacity 78million m³

Eff. Capacity

93million m³

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Tainan

1. NO raw water backup pipelines

60%

40%

Interconnecting Pipeline

of the Project

existing Nanhua-Gaoping interconnecting pipeline

Water Supply Issues~

Drought Event

132

million tons Zengwen + Wushantou

21

million Nanhua

(22^nd Apr. 2015)

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2. Water Supply Issues in Kaohsiung City

Zengwen Reservoir

existing Nanhua-Gaoping interconnecting pipeline

High Turbidity of Gaoping River

(Backup for Kaohsiung)

Gaoping River Weir

69%

Gaoping

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Tainan Nanhua

Reservoir

60%

40%

3. Pressure of water supply in Nanhua Reservoir

Capacity is less, but load is heavier.

Backup for Kaohsiung when necessary

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4. Only one route can supply water.

Water won’t be able to be sent out during an emergency.

Functions Flooding Prevention Electricity Generation Water Supply 1

2 3

Wushanling Tunnel

2 1

3

Water Supply irrigation domestic industrial

86%

12%

2%

Hydropower Plant

Effective Capacity：

509 million m³

Eff. Capacity 78 million m³

Z

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more elastic &

flexible

To improve the water supply

in southern Taiwan …

 Connect water resources of main reservoirs

 Increase a backup pipeline to support

 Dispatch water resources more flexibly

After the project reaches completion, we can…

 Lower water shortage risks

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Main Content

of the Project

2

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 Starts at

Penstock of Power plant

 Connects to

1.Nanhua Purification Plant 2.Nanhua/Gaoping Pipeline

 Total length 25 km

 Max discharge capacity 800,000 CMD

start at

Penstock of Power plant

曾庫公路

connects to Nanhua

Purification Plant

Tainan City ^Zengwen_Reservoir

Nanhua Reservoir Wushantou

Reservoir

Zengwen/Nanhua

connects to

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Period & Expenditure

Year ^{2019 2020} ²⁰²¹ ²⁰²² ²⁰²³ ²⁰²⁴ ^Total

Expenditure

(*million NTD) 39 534 967 2,251 3,346 4,325 12,000

 Period：2019~2024

 Total Expenditure：12 billion NTD (0.4 billion USD)

Basic Design

2019 2024

2018

Detail Design & Construction Management Planning &

Investigation

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曾庫公路

Tainan City

Nanhua Reservoir Wushantou

Reservoir

Zengwen/Nanhua

connects to

Intake Segment of the Pipeline

pool

dam

Left Abutment

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Plan view of Intake Segment

Power Plant

Penstock of Power Plant

pool

dam

PRO

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Sediment-Sluicing Tunnel

Design discharge：995cms

Expected Average Annual Sediment Sluicing

= 1.04 million m³

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PRO(

Permanent River Outlet)

provides water when the power plant stops running.

Ventilation Tunnel for PRO

Maintenance Tunnel for PRO

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No.1 diversion tunnel

• It connects with the hydropower plant penstock.

• Water has gone through the tunnel after generating electricity.

No.2 diversion tunnel

• No water has gone through it since the reservoir started working.

• It provides an access to PRO operating room.

2 1

2

1

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Hydropower Plant

56 cms

Penstock

Diameter = 3.8m

Access Tunnel

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The Intake Segment of the interconnecting Pipeline

Part 1

Pipeline in New Tunnel Part 2

Pipeline in #2 Diversion tunnel

N

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3D View of Intake Segment

Penstock of Power Plant

Pipeline

#2 Diversion tunnel

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existing Nanhua-Gaoping 23 interconnecting pipeline

曾庫公路

Zengwen/Nanhua

connects to

Energy Dissipation

Segment of the Pipeline

Muguyan Terrace

Intake Segment

Muguyan Terrace (木瓜園台地)

N

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800,000CMD

600,000 CMD

舊管-SP及流量Q=80萬CMD

EL.230m

Excess Energy

Point of connecting to existing Nanhua- Gaoping interconnecting pipeline

Elevation (m)

50m

Neimen Regulation Basin

EL.114m

86m

Distance (m)

100,000CMD

EL.144m

Neimen Regulation Basin

EL.114m

東平橋

Hydraulic Grade Line(Q=800,000~600,000 CMD)

EL.230m

Hydraulic Grade Line(Q=600,000~100,000 CMD)

EL.180m(Muguyan Terrace )

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Energy Dissipation Design

Water supply shaft

2^nd Step:

Baffle-drop Structure Regulation basin

1^st Step:

Vertical stilling well &

fixed cone valve

Baffle-drop

H=61m ,Φ7.6m RC

flow

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2

^nd

Step:

Baffle-drop Structure

1

^st

Step:

Vertical stilling well &

fixed cone valve

2-Step Energy Dissipation

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3 Crucial Issues

in the Left Abutment

3

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28 Net Width of New Tunnel= 4.6m

Pipeline : Φ2.2m SP

Φ2.2m SP 6.24 1

EL:150m

Issue 1 : Safety of Tunnel Excavation

 Impact of the new tunnel excavation in the left abutment on the safety of existing tunnels

＃２Diversion tunnel 30m

Ventilation Tunnel to PRO Maintenance Tunnel

to PRO

New Tunnel

of the Project

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“Underground Excavations” (by Hoek & Brown)

D

_h

=2.5(a

₁

+a

₂

)F.S.

D_h：Horizontal distance

a₁：radius of #2 diversion tunnel a₂：radius of new tunnel

F.S.：factor of safety a₁=6m ；

a₂=2.25m ； D_h=30m

F.S. = 1.45

^………OK!

Factor of Safety

The excavation of new tunnel won’t

influence the safety of existing tunnels.

i.e.

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 Water hammer effect on the power plant system due to closure of the new intake pipeline.

Issue 2 ： Water Hammer on Power Plant

 4 Simulation Scenarios :

Scenario A: Current condition, total load rejection

Scenario B: Total load rejection, new pipeline in operation Scenario C: Power plant in operation, new pipeline closure Scenario D: Total load rejection, new pipeline closure

(load rejection：電廠跳機, new pipeline closure：本聯通管關閉)

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Simulation Results

Elevation(m)

Distance(m)

Power Plant Zengwen

Reservoir

A

C

B &D

Fig. Analyzed Maximum Pressure Envelops due to Load Rejection and Closure of Flow Control Valve Centerline of pipe Scenario A: 166.4m

Scenario B: 166.4m Scenario C: 125.0m Scenario D: 166.5m

Water hammer on power plant

Current condition

(Current condition)

Impact on the existing power plant system from closure of new intake pipeline can be neglected.

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 Influence on ventilation required for PRO

Issue 3 : Influence on ventilation

Evaluate the lack of ventilation caused by the reduction in section area.

Sec. B

#2 Diversion tunnel (wind speed has been quite high during PRO operation.)

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Issue 3 : Influence on ventilation

Sec. B Sec. A

Ventilation Tunnel to PRO

10m 70m

#2 Diversion Tunnel

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Calculation Results

Sec. B Sec. A

Ventilation Tunnel to PRO

10m 70m

#2 Diversion Tunnel

Cross-Sectional Area

Current Condition After Construction

Sec. A 74 m²

Sec. B 109.51 m² 88.75 m²

Sec. of Ventilation

tunnel to PRO 22.39 m²

O.K

Sec. B after construction

#2 Diversion tunnel

It is judged that the project won’t have obvious effects on ventilation required for PRO.

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Short Conclusion

Issue 1

Impact of New Tunnel Excavation

Issue 2

Water Hammer effect on Power Plant

Issue 3

Influence on ventilation required for PRO

intake segment of this pipeline~

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