Koh Brothers Building & Civil Engineering Contractor (Pte.) Ltd. and wastewater treatment projects which was founded in 1966, and its joint venture partner, Penta-Ocean Construction Co. Ltd., have been working on Contract T-08 of the Deep Tunnel Sewerage System ("DTSS") Phase 2 project, specifically, relating to the section from South Tunnel at Tuas Road and Industrial Tunnel at Pioneer Road to the Tuas Water Reclamation Plant that will span 10 kilometres, which is about to be completed successfully. It has been about three years since Penta-Ocean's President, Takuzo Shimizu, and Koh Brothers Eco's Non-Executive and Non-Independent Chairman, Francis Koh, started working together as equity partners on 8 June 2021, when Penta-Ocean made an investment into approximately 28.74% of Koh Brothers Eco.

In 2017, the joint venture established by KBCE and Penta-Ocean ("POKB JV") received an order from Singapore's Public Utilities Board ("PUB") to complete a total of 4 shield tunnels, totaling 10 km in length, including 2 undersea tunnels, in the T-08 section project, ahead of other section projects. The disaster-free time exceeded 10 million hours in 2023 and is still ongoing. In 2022, POKB JV was awarded the PUB Construction Safety Award 2022, which is the highest honour among all construction sites of PUB, for the project progress and safety management.

In terms of quality, POKB JV collaborated with G & W Ready-Mix, a subsidiary of Koh Brothers Group Limited, to develop and manufacture sulphur-resistant acid concrete resistant to sulphide gas generated in sewer tunnels and had successfully placed the concrete for the first time in Singapore. This is expected to significantly contribute to maintaining the quality and improving the service life of sewer pipes in Singapore. Tuas Corrosion Protection Lining.

Over the past 60 years since 1964, Penta-Ocean has participated in several large-scale projects in Singapore, from marine civil engineering works such as reclamation and construction of container terminals, to land-based civil engineering works such as subways and highways, to construction works such as landmark commercial facilities and large-scale hospitals. KBCE, which enjoys a long and rich corporate history, has a strong track record ranging from design and build to general construction for residential, commercial and institutional buildings and infrastructure works. KBCE is also a BCA L6 - (ME11) graded contractor which enables it to tender for public mechanical engineering projects of unlimited value.

Over the years, KBCE has participated in projects by various public sector agencies such as the BCA, Housing & Development Board ("HDB"), PUB, Singapore's National Water Agency, Urban Redevelopment Authority ("URA"), Land Transport Authority ("LTA") and Changi Airport Group ("CAG"). Some of KBCE's major infrastructure projects include the Punggol Waterway awarded by HDB, the iconic Marina Barrage, Geylang River Make Over, Changi Water Reclamation Plant (Phase 1), and Jurong Water Reclamation Plant by PUB, the Common Service Tunnel by URA, Downtown Line 1 Bugis Station by LTA and the retention pond at Changi Airport by CAG. In addition, through a joint venture with Samsung C&T Corporation, KBCE secured a landmark S$1.12 billion project from CAG for development works to effect three-runway operations at Changi Airport.

Other landmark building projects by KBCE include Building and Electrical works at Jurong West Neighbourhood 6 Contract; Building works at Chua Chu Kang Neighbourhood 4 Contract awarded by HDB; New Halls of Residence at Nanyang Avenue for Nanyang Technological University and the development of River Valley High School and a hostel at Boon Lay Avenue, both awarded by the Ministry of Defence; and the Ministry of Defence; and The Group's Bio -Refinery and Renewal Energy division under Oiltek International Limited specialises in the Ministry of Home Affairs. The Group's Bio-Refinery and Renewal Energy Division specialises in a full range of Energy division under Oiltek International Ltd.