Project Name: Construction Supervision of BMA Drainage Tunnel (Makkasan to Chao Phraya River) Project

Name of Company: Thai Engineering Consultants Company Limited

- Thai Engineering Consultants Co., Ltd. Contract Management &

Construction Supervision

- Consulting Engineers Co., Ltd. Construction Supervision

Location: Bangkok, Thailand

Client: Department of Drainage & Sewerage, Bangkok Metropolitan Administration

Project Cost: 2,116 Million Baht

Type of Service: Construction Supervision

Project Description :

The Department of Drainage and Sewerage, Bangkok Metropolitan Administration targets to resolve the flooding problem in inner areas of Bangkok by increasing the water drainage system’s efficiency, which is currently very limited, to operate and accommodate for future city development and expansion. In order to achieve the set target, the construction of the BMA Flood Protection Tunnel from Makkasan to Chao Phraya project was executed.

The project consists of:

• flood protection tunnel with a diameter greater than 4.6 meters,
• intake stations at Bung Makkasan, Khlong Saensaab, Khlong Pai Singto, and Rama IV road
• pumping station with a 45 cubic meter per second capacity at Khlong Kut Wat Chong Lom to pump water into the Chao Phraya River.

The construction of the flood protection tunnel with a diameter greater than 4.6 meters starts from the Makkasan intake station through the Makkasan Maintenance Factory along the Makkasan – River Railway route to the Khlong Kut Wat Chong Lom pumping station. The project also includes the construction of the intake stations at Khlong Saensaab, Khlong Pai Singto, and Rama IV Road.

The Construction of the Shafts and Tunnel  Shafts utilizes the moving slipform to cast the walls. Excavation of soil inside the shaft along with applied force on the shafts top sinks the structure into the ground to the appropriate levels. After the structure is at the design level, a concrete plug is cast at the lower tip of the structure, and then the reinforced concrete base slab is constructed for the Tunnel Boring Machine assembly above.

Tunnel Boring Machine (TBM) is assembled at the bottom of the shaft. The tunnel is constructed utilizing the TBM, which is Earth Pressure Balanced. The soil excavated travels from the TBM by conveyor belts into the muck cars attached to locomotives out of the tunnel. As the TBM excavates the soil, precast tunnel segment linings are installed, then cement grout is placed between the tunnel lining and the soil to prevent settlement.

Intake Stations includes of Trash Bar Screen and Automatic Trash Rake with Conveyors, Hoppers, Roller Gates, Conveyor System, Control Room, and Shaft with capacity for water

collection into the tunnel as follows:

• Bung Makkasan Intake Station e”30 cubic meter per second
• Khlong Saensaab Inlet Structure e”25 cubic meter per second
• Khlong Pai Singto Inlet Structure e”15 cubic meter per second
• Chua Plueng Road Inlet Structure e”15 cubic meter per second

Khlong Kut Wat Chong Lom Pump Station includes a 15 m. diameter Shaft, 5 sets of 9 cubic meter per second Concrete Volute Pumps with Control Equipment, and a Sub-station. The Khlong Kut Wat Chong Lom Pump Station has more than a 45 cubic meter per second capacity to discharge water from the tunnel.

Tunnel is reinforced concrete with an inner diameter greater than 4.6 meters and a length of 6,200 meters. The Tunnel is 20 – 35 meters deep and was designed for more than 45 cubic meter per second capacity and a maximum flow rate of not less than 3.0 meters per second.