Engineering of enhancing water level of Tseng Wen Reservoir to 230M through improvement of dam, spillway, and related facilities

 

編譯:林佳瑩╱Translated and edited by jia- ying, Li

Name:Engineering of enhancing water level of Tseng Wen Reservoir to 230M through improvement of dam, spillway and related facilities.

Location:In Dapu Stream, the upriver of Tseng Wen River in Chiayi County

Participated organizations:South Region Water Resource Office, Water Resource Agency, Ministry of Economic Ministry(Organizer)、Sinotech Engineering Consultants, LTD.(Designer)、Tseng Wen Dam Improvement Engineering Worksite Office(Supervisor)、BES Engineering Corporation(Executor)

Construction period:From July 30, 2008 to June 24, 2009, 330 calendar days

Funding:177,062,000NTD

Description:

1.Background:

On Oct. 31, 1967, the construction of Tzeng Wen Reservoir was started in the design of embankment and took 6 years to be finished. On Oct.31, 1973, Tzeng Wen was begun to store water to mainly supply domestic water, industrial water, and agricultural water in Southern Taiwan as the biggest target reservoir. Nevertheless, due to the rapid growth of commerce and industry and increasingly urgent needs of water use, the gap of water supply will be achieved more than 230,000 ton per day in Southern region in the estimation.  

Although Tseng Wen Reservoir has the greatest storage in Taiwan but its water collection area is only 481 KM2. Hence, the average water inflow is only 1.08 billion over the years and the full water level of reservoir only could be reached once per three years. The utilization rate is too low. On the other hand, the water system of GaoPing River has rich water resource. Without irrigation facility the utilization rate of its stream flow only reaches 12% which is far lower than national average, 18%. Hence, most water in high flow period couldn’t be used but flow to sea. To reach sustainable use for water resource, the Taiwan’s government has initiated a project to transfer water from GaoPing River to Tseng Wen Reservoir in the existing condition that the characteristics of GaoPing River and Tseng Wen River are mutually complementary. The former has water resource without reservoir but the latter has reservoir without water resource. The residual water of Laonong Stream, a branch of GaoPing River, in high flow period could be transferred to Tseng Wen Reservoir for enhancing potential of water supply of the reservoir and for satisfying future water needs in Southern region of Taiwan. At an estimate, the water supply per day can be increased to 0.6 million ton per day after the successive project of transferring water is finished. To response to this project of transferring water, the engineering to improve water storage level of Tseng Wen Reservoir will be processed and the normal water level will be enhanced from 227M to 230M. To ensure the safety of future project, this engineering will review the structures of dam, spillway and related facilities and make necessary improvement measures according to the conclusion of “the third safety assessment of Tseng Wen Reservoir”.   

2. Construction Methods:

Picture Provided:South Region Water Resources Office, Water Resource Agency, Ministry of Economic Affairs

Main construction items of “Engineering of enhancing water level of Tseng Wen Reservoir to 230M through improvement of dam, spillway and related facilities”

Picture Provided:South Region Water Resources Office, Water Resource Agency, Ministry of Economic Affairs

To safely enhance water level, the main construction items include five ones as following:

(1)Heightening inside of dam:Dig the volume 35,860m3 from dam top and infill the volume 43,620m2 into the dug space.

Picture Provided:South Region Water Resources Office, Water Resource Agency, Ministry of Economic Affairs

Sectional drawing of improvement in dam body:the dam top is sustained at original height .The inside is enhanced from EL233 to EL235 and water level was heightened from EL227 to EL230 (3M increase)
Picture Provided:South Region Water Resources Office, Water Resource Agency, Ministry of Economic Affairs

(2)Improvement of structures of dam top:destroy the original wave wall and rebuild a new one 433 m high; destructs the railing and rebuild new one 408 m high; improve the drainage system in the dam top. Picture Provided:South Region Water Resources Office, Water Resource Agency, Ministry of Economic Affairs

Construction sequence of improvement engineering.
Picture Provided:South Region Water Resources Office, Water Resource Agency, Ministry of Economic Affairs

Destruct wave wall and rebuild a new one. Picture Provided:South Region Water Resources Office, Water Resource Agency, Ministry of Economic Affairs

Destruct wave wall and rebuild a new one. Picture Provided:South Region Water Resources Office, Water Resource Agency, Ministry of Economic Affairs

 (3)Enhance the bridge on top of spillway to 85 cm;heighten the right approach of bridge and side wall; remove AC pavement and resurface a new one.

Steps of enhancing the bridge in the dam top. Picture Provided:South Region Water Resources Office, Water Resource Agency, Ministry of Economic Affairs

Steps of enhancing the bridge in the dam top. Picture Provided:South Region Water Resources Office, Water Resource Agency, Ministry of Economic Affairs

Operation of heightening the top of bridge. Picture Provided:South Region Water Resources Office, Water Resource Agency, Ministry of Economic Affairs

Operation of heightening the top of bridge. Picture Provided:South Region Water Resources Office, Water Resource Agency, Ministry of Economic Affairs

(4)Protection engineering of collapsed side slopes in left part of dam and naked slope in left rear area of switch factory

Protection engineering of side slopes. Picture Provided:South Region Water Resources Office, Water Resource Agency, Ministry of Economic Affairs

Protection engineering of side slopes. Picture Provided:South Region Water Resources Office, Water Resource Agency, Ministry of Economic Affairs

(5)Other miscellaneous items of engineering

Schedule drawing of main construction items. Picture Provided:South Region Water Resources Office, Water Resource Agency, Ministry of Economic Affairs

Schedule drawing of main construction items. Picture Provided:South Region Water Resources Office, Water Resource Agency, Ministry of Economic Affairs

The main principle of engineering is minimum development (environmental conservation) and maximal benefit (economic development). The methods of sustainable engineering penetrate all stages of construction to achieve sustainable utilization of water resource.

1.Energy saving and carbon reduction:

Local materials are used in this engineering like earth, a kind of natural material. Besides, 64% of fill materials for new dam body come from destroyed old dam to reduce the materials transported and purchased from other place. At the same time, the bridge of spillway has to be heightened 0.85 m in accordance with the improvement construction of dam. After the top of pier was heightened and strengthened, the existing steel bridge of the spillway was enhanced by oil jack, a kind of machine. This method of construction could prevent to build a new bridge, use less reinforced concrete, and reduce vast emission of CO2.

Exclusion and recycling of asphalt concrete in the dam top. Picture Provided:South Region Water Resources Office, Water Resource Agency, Ministry of Economic Affairs

Exclusion and recycling of asphalt concrete in the dam top. Picture Provided:South Region Water Resources Office, Water Resource Agency, Ministry of Economic Affairs

2.Environmental Protection:This engineering is one part of “engineering of improving water level of Tseng Wen Reservoir”. Through enhancing water level, water storage can be increased to satisfy future water needs and no new reservoirs need to be built. It accord with the international trends that new reservoirs are not always necessary to be built. On the other hand, this improvement engineering also can meet the international trend of energy saving and carbon reduction and decrease vast influence on ecology and environment. At the same time, the reinforced supervision for environment and the least construction volume all accord with the principles of ecology and environmental protection.

Picture Provided:South Region Water Resources Office, Water Resource Agency, Ministry of Economic Affairs

5 indicators of energy saving and carbon reduction in the improvement engineering of water level of Tseng Wen Reservoir. Picture Provided:South Region Water Resources Office, Water Resource Agency, Ministry of Economic Affairs

3.Disaster prevention and safety:The least construction volume can reduce emission of CO2 and influence on environment. It’s also the most efficient method to ensure safety of reservoir by reducing disturbance on dam body. At the same time, the enlarged reservoir volume in this engineering also increased storage of flood peak to prevent risk of flood flow over dam and to ensure water need for citizens.

4.Quality, maintenance and management: Before construction, the characteristics of fill materials were controlled in the method of rolling and testing. A laboratory was set up for doing earth test (such as compaction test in a method of fast control, relative density, etc. )to control quality of roiling and implementation progress in the construction site. The construction of this case can extend service life of reservoir.

Sheep's Foot Roller。Picture Provided:South Region Water Resources Office, Water Resource Agency, Ministry of Economic Affairs

Sheep's Foot Roller。Picture Provided:South Region Water Resources Office, Water Resource Agency, Ministry of Economic Affairs

Density test in the construction site. Picture Provided:South Region Water Resources Office, Water Resource Agency, Ministry of Economic Affairs

Density test in the construction site. Picture Provided:South Region Water Resources Office, Water Resource Agency, Ministry of Economic Affairs

Proctor compaction test. Picture Provided:South Region Water Resources Office, Water Resource Agency, Ministry of Economic Affairs

Proctor compaction test. Picture Provided:South Region Water Resources Office, Water Resource Agency, Ministry of Economic Affairs

Field Density Test.Picture Provided:South Region Water Resources Office, Water Resource Agency, Ministry of Economic Affairs

Field Density Test.Picture Provided:South Region Water Resources Office, Water Resource Agency, Ministry of Economic Affairs

5.Innovative technology:From the stage of design and plan, the concept of sustained public infrastructure was introduced and the idea of sustainable development was brought in life cycle of construction (plan, design, construction, maintenance and management). At the same time, the latest three dimensional numerical analysis (SEEP3D) was used to analyze porous flows of dam body.

Assessment and Review:

After water level of Tseng Wen Reservoir was heightened to 230 M, the safety of dam meets the standard of USBR (1990) and the storage of reservoir was enlarged 54.7million ton, which is equal to the storage of HuShan Reservoir. Under the prerequisite that no new reservoirs are built to destruct ecology, this engineering practiced the concept of sustainable public infrastructure and was awarded for its construction quality by Ministry of Economic Affairs in 2009. The benefits of engineering are as following:

1. Economic and social benefit:After the engineering was finished, the storage of reservoir was enlarged a volume of HuShan reservoir but the funding is only 1/53 of total expenditure of HuSahan reservoir and dam. In the future, Tseng Wen Reservoir can add 0.6 million ton of water supply in the future. Hence, under the fruit of engineering, the dispatch of water resource in Southern region can be improved, the living standard of citizens can be enhanced and the comprehensive economic benefit can be enlarged.

2. Extending service life of construction: The principle of green design was taken in this engineering. The least construction volume reduced the disturbance on dam body. It’s the most efficient method to ensure safety of reservoir, to effectively extend service life, and to enhance operation quality for achieving sustainable development.

3. Flood prevention and disaster reduction: Safety and disaster reduction are emphasized in sustained public infrastructure. After the completion of engineering, the effective storage will be increased to reduce frequency of flood discharge and flood control operation, to effectively enhance operation efficiency of reservoir, to strengthen function of flood prevention of reservoir, and to increase utilization rate of water resource.

4. Benefit of construction technology:3-D numerical analysis (SEEP3D) was introduced to analyze porous flows of dam body and concept of sustainable development of water resource was guided in life cycle of construction (plan, design, construction, maintenance and management). Under the limitation of existing dam, the engineering was promptly processed in dry period when the reservoir could be normal operated. This challenging experience can be inherited to future improvement for the reservoir.

5. Benefit of ecology and environmental protection: 64 percent of fill materials in the engineering are recycled and reused to meet the principle of “green material”. At the same time, the ecological engineering method was used to enhance bridge. In this stage of construction, the utilization of reinforced concrete was decreased to reduce emission of CO2. Besides, the construction of new reservoir was prevented to reduce influence on environment. The above-mentioned approaches all meet current public policy of energy saving and carbon reduction.

Organizers:陳永超、林穆琳

Reference:

「曾文水庫蓄水位提高至標高230公尺大壩溢洪道及附屬設施改善工程」主辦單位簡報

「曾文水庫蓄水位提高至標高230公尺大壩溢洪道及附屬設施改善工程」監造單位簡報

經濟部公共工程優質獎主辦單位簡報

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