48 Ravenhill Ave Flood Alleviation Scheme
separate stormwater from 9 hectares of impermeable ground , and provide first-time storm sewer services to 572 properties .
One of the unique aspects of the Ravenhill Avenue project was the use of an NEC4 ECC Option C contract - a form of contract that promotes cost transparency , collaboration , and risk-sharing between the client and contractor .
Under this contract type , GEDA Construction was appointed as the main contractor , with AtkinsRéalis and AECOM leading design , modelling , and project management .
The Option C contract is structured around a target cost and a pain / gain share mechanism , where both client and contractor share the financial risks and rewards . This encouraged the project team to innovate and find costeffective solutions , resulting in £ 850,000 in savings and shortening the construction schedule by six months .
The engineering challenges posed by the project were significant , particularly due to the densely populated residential setting and the aging infrastructure , some of which dated back to the early 20th century .
The project ’ s early phase involved tunnelling to upgrade the combined sewer network , followed by the replacement of the dilapidated 1050mm brick sewer with a new 1800mm combined sewer . This process was not without its complexities , including the need for major flow control measures and excavation up to six meters deep in a narrow street .
Despite these challenges , the project saw multiple examples of value engineering , including a proposal to retain the existing sewer structure instead of full replacement , reducing both cost and construction risk . Another innovative solution involved using non-man entry manholes to reduce health and safety risks while maintaining efficiency .
The Ravenhill Avenue Flood Alleviation Scheme stands as an example of how collaborative contracting , innovative engineering , and strong project management can deliver
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