08-16-2017, 09:39 PM
lake tapping ppt
A lake tap involves excavating a tunnel almost to the water/rock contact and then blasting out the final protective rock to allow water to suddenly inflow into the tunnel from the lake. The first lake tapping was carried out at Koyna dam 13 years ago. For the second lake tapping, an additional tunnel, 4 km long, had been excavated, approximately 40 m below the surface of the lake.
The Koyna Hydroelectric Project is the largest completed hydroelectric power plant in India. It is a complex project with four dams including the largest dam on the Koyna River known as the Koyna Dam hence the name Koyna Hydroelectric Project. The project site is in Satara district near Patan. The village Helwak near the dam was later known as Koynanagar.
The total capacity of the project is 1,960 MW. The project consists of four stages of power generation. All the generators are located in underground powerhouses excavated deep inside the mountains of the Western Ghats. A dam foot powerhouse also contributes to the electricity generation. Due to the project's electricity generating potential the Koyna River is considered as the life line of Maharashtra.
The project takes advantage of the height of Western Ghats. Thus a very large hydraulic head is available over a very short distance.
The second lake tapping at Koyna hydro electric project was carried out successfully on Wednesday morning.
Chief minister Prithviraj Chavan and deputy chief minister Ajit Pawar witnessed the event. Chavan pressed the button at 11 am and a medium impact was felt. The water rose 15 ft high, creating waves.
A lake tap involves excavating a tunnel almost to the water/rock contact and then blasting out the final protective rock to allow water to suddenly inflow into the tunnel from the lake. The first lake tapping was carried out at Koyna dam 13 years ago. For the second lake tapping, an additional tunnel, 4 km long, had been excavated, approximately 40 m below the surface of the lake.
This tunnel is expected to carry water with a tremendous force and run turbines to generate 1,000 MW power. The water from the dam is released in Kolkewadi dam, near Chiplun tehsil of Ratnagiri district. Before releasing the water into the sea, a separate power station generates additional 320 MW power. All phases put together, Koyna dam generates 1,960 MW power.
The second tunnel, 4-B, will enable the state power utility to generate electricity during summer. The fourth stage of the Koyna project can generate power till the water level drops to 630 m. Once the water level in the reservoir drops below 630 m, the 4-B tunnel will be used, since it is deeper than the earlier tunnel and can run the turbines till the water level drops to 618 m. At the time of lake tapping, the water level in the dam was 642 m. The fourth stage commenced in 1999, when the 630 m level was sufficient.
The water distribution tribunal recommends the supply of 25 TMC water to Tembhu, Takari and Mhaisal lift irrigation projects to supply water to the drought prone areas of Satara, Sangli and parts of Solapur districts.Koyna dam is located 190 km south west of Pune. The explosives used for the lake tapping were specially bought from Denmark.