KUCHING: Kumpulan-Nishimatsu-Hock Seng Lee consortium (KNH), the contractor for the Kuching Waste Water Management project has achieved a major technical milestone with the completion of Malaysia’s longest ever under river tunnel jacking.
HIGH SPIRITS: Photo shows workers posing with the ‘Super Uncle Mole’, one of the TBMs which arrived at the receiving shaft near the Tun Salahuddin toll bridge. The construction team was in high spirits after completing the longest under river tunnelling job in Malaysia at 280m.
The 280-metre river tunnel which runs parallel to the Tun Salahuddin toll bridge is the first of its kind in Borneo. To date, the entire tunnel system consists of more than 166 shafts and measures more than 8,000 metres in length.
“Tunnelling under a major river is a significant technical feat and we are very proud of our team,” declared KNH representative, Simon Lau.
The laser-guided Tunnel Boring Machine (TBM) arrived on schedule after its arduous 280-metre journey during which its cutter head parts had to be changed three times. construction team was prepared for many eventualities during the underwater crossing.
“Fortunately, the geotechnical conditions were consistent with mostly hard rock and while this does churn through our TBM’s ‘bits’ rather quickly, it is at least predictable and stable terrain,” noted Lau.
“While we were technically well prepared for this enormous challenge, we nevertheless, were very happy to see our TBM break through into the receiving/retrieval shaft on the opposite side of the river,” added.
To complete the Sarawak river crossing, the construction team jacked a total of 92 sewerage pipes of 1.5 metre diameter into place. Construction of the deep shafts throughout the city to enable the lowering and retrieving of TBMs is now 80 per cent completed with the entire project 35 per cent completed.
Without the tunneling technology, the contractor would have to dig open trenches for the entire piping route through the city and the river crossing would have involved a costly bridge-mounted pipe and pumping station.
With the successful Sarawak River crossing, the main sewerage line now makes its final journey to the sewerage treatment plant complex near the Zecon toll in Kuching.
Once commissioned, this sophisticated facility will process the wastewater from Kuching a series of treatment stations until it is clean (Standard A) and fit for discharge. This will be a revolutionary change for the city and remove a huge source of water pollution.
Currently, sewerage or ‘black water’ was stored in septic tanks. These had to be regularly pumped out or ‘desludged’ by the local councils with solids then sent for burial and liquids discharged into waterways largely untreated.
Meanwhile, the city’s ‘grey water’, a putrid mix of soaps, chemicals, food wastes and so on generated by some half a million people, goes directly into rivers and waterways by way of the open monsoon drains.
Once the centralised waste water management system is complete, both the black and grey water will be properly treated. The main sewer line will be completed by next year with property connections within the Central Business District starting this year.