Khayam Tunnel and Third Outlet Project
Location: Tehran
Client: Khakrizab Water Company
Objectives of Khayam Tunnel
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This tunnel will protect the central part of Tehran against floods and ultimately connect to Firouzabad Canal in the south of Tehran.
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The catchment area of this tunnel for floodwater is approximately 27.2 square kilometers.
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The intended area covers the northern part of Abbasabad Hill Development Plan, bordered by Kargar Street to the west, Ferdowsi Street to the east, and extends to Firouzabad Canal in the south.
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The total length of the main tunnel is approximately 13 kilometers and its diameter varies from 2.8 meters to 3.7 meters.
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A portion of the southernmost section of this tunnel was previously constructed using traditional methods in 1985.
Objectives of the Third Outlet Project:
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Transfer of surface water from Firouzabad Canal from the south to the southwest and ultimately to the Kan River.
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Transfer of surface water from Yakhehchibaad and Beheshti Canals to the Kan River.
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Artificial recharge of floodwater into the groundwater resources of the southern region of the Kan River.
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Recovery of the southern lands of Tehran by lowering the groundwater levels.
Description of Services:
This contract includes a portion of the Tehran Surface Water Collection Project. The length of the tunnels is approximately 13 kilometers. The executed works under this contract include:
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Section 1: Fatemi Branch - Nal Asbi Tunnel with a diameter of 2800 millimeters.
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Section 2: Modares Branch - Nal Asbi Tunnel with a diameter of 2800 millimeters.
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Section 3: North Hafez Street Branch to Vahdat Hall - Nal Asbi Tunnel with a diameter of 2800 millimeters.
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Section 4: Branch from Vahdat Hall to City Park - Circular Tunnel with a diameter of 3700 millimeters using TBM .
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Section 5: Branch from City Park to Molavi Street - Circular Tunnel with a diameter of 3700 millimeters using TBM.
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Section 6: Branch from Molavi Street to the south of the railway - Tunnel with a diameter of 3700 millimeters using TBM.
The groundwater level in sections 1, 2, and 3 is lower than the tunnel, but in most of the length of sections 4, 5, and 6, it is at the same level or higher than the tunnel.
The Third Outlet Project includes a 8.1-kilometer Nal Asbi tunnel with a diameter of 4600 millimeters, along with other related structures. The groundwater level in some parts of this section is also higher than the tunnel invert.