Gulf Construction Online - MAK ready for pump station handover

Kuwait

The pumping station project, Kuwait City ... ready for handover.

MAK ready for pump station handover

01 December 2011

LEADING contracting firm Mohammed Abdulmohsin Al-Kharafi & Sons (MAK) is gearing up to handover a major turnkey pumping station project, which is believed to be the largest of its kind in Kuwait.

Valued at $270 million, the project includes variation orders issued by the client Kuwait’s Ministry of Public works (MPW), and is set to become fully operational shortly.

As part of the MPW’s extensive programme to renovate the country’s sewerage network, this mega project entails the design, construction and operation and maintenance of a network of main and secondary interceptors and a new 40-m-deep pumping station with associated tunnels.

MAK had appointed the Kuwait-based Gulf Consult in association with the international consultant Montgomery Watson Harza (MWH) to provide design and supervision consultancy services for this particular development.

The work on project started in April 2002 and has involved replacing some 29 pumping stations that served the catchment areas of Kuwait City, with one single A7/A12 pumping station linked by a network of tunnels. These stations were in a deteriorating condition and were polluting the surrounding environment. In order to overcome this situation and maintain the environment, Kuwait’s Prime Minister called for the construction of new sewage networks with one major new pump station replacing the existing 29 pump stations, with all sewage water flow being continuously monitored from this new pump station.

A series of main and secondary interceptors have been constructed that drain to the newly-built A7/A12 pumping station, which is 40 m below ground level and has seven pumps plus a reserve area for three standby pumps – each capable of delivering 1,400 litres per second with a maximum head of 80 m to reach a capacity of 780,000 cu m per day by the year 2050. The sewage flow is pumped from Riggae to Ardiya in Kuwait through four pressure lines of ductile iron pipes of 1,000-mm diameter, that were laid over a total length of 3.5 km.

MAK has faced a number of major challenges with regards to the construction of tunnels, pump station and pressure lines. These challenges were faced by utilising some of the latest high-technology systems using micro-tunnelling methods for the construction of the sewage network in order to ensure durability and to avoid disturbance to the existing network and traffic. At the peak of construction eight micro-tunnelling machines, ranging in diameter from 400 to 2,250 mm, were used to construct the pipelines at depths ranging from five to 37 m in variable ground conditions with high water pressure.

For the construction of the 380 shafts, with diameters from 3.5 m to 13 m, various methods were used such as sinking caisson, sheet piles, secant piles, diaphragm walls and a VSM machine (vertical sink machine from Herrenechkt – Germany) was used for the first time in the world to construct new shafts in water-bearing ground conditions along with vortex chambers up to 10 m diameter. A state-of-the-art Scada (supervisory control and data acquisition) system monitors the day-to-day operation and running of the plant to ensure the utmost efficiency.

Also included in MAK’s scope of works were all electro-mechanical works and the construction/supply of penstocks, valves, vortex grit removal units, four 1,000-mm-diameter rising mains and 43 km of various size tunnels running up to 40 m deep. In addition, the hydraulic penstocks (30 tonnes in weight) were erected at a depth of 35 m from ground level along with the vortex grit equipment, screens and gates at the same level.

The area was dewatered by deep wells and a well point system, to lower the high ground water pressure to a depth of 45 m. To cope with the varying soil conditions, MAK erected different types of shoring systems such as sheet piles, concrete panels with anchors and secant pile walls also with anchors to suit the type of soil.

The waterproofing work for the pumping station involving an internal and external area of around 20,000 sq m was an extremely meticulous task. The project also required the installation of standby generators of a total capacity of 9 MVA to ensure the pumping station remains functional in case of any interruptions of the mains power supply.

The project has also drawn up impressive statistics as there was around 750,000 cu m of excavation as well as 120,000 cu m of concrete required to construct the massive pumping station, which has a built-up area of about 42,5000 sq m.

The project has been designed to efficiently handle the peak flow for the expected population of Kuwait up to the year 2050.