Dewatering can be used to assist the construction of canals, ports and marine structures. When working next to open water it is common that works are undertaken within a form of cofferdam. Often this is a temporary enclosure that allows an area to be pumped out of water forming a dry working environment. Shoring such as sheet piles, secant piles and diaphragm walls can also be used to form part of the permanent structure. Dewatering and shoring can be designed to complement each other to cut off unstable zones and provide a dry and stable excavation.
WJ experience dewatering next to open water includes dewatering canals at the Pearl Qatar and Dubai Water Canal Extension in the UAE, dewatering the Burj Al Arab in Dubai, a large gas terminal on reclaimed land off the shores of Nigeria, the London Gateway Port and Cardiff Bay Barrage in the UK, and open cut sections adjacent to the sea at Lusail Expressway in Doha, Qatar.
Consideration needs to be taken to the quality of water discharge into the marine environment. Use of suitable well screen and filter materials, sump pits, settlement tanks and ponds are all commonly used methods to ensure discharged water meets quality criteria set by authorities.
Special attention to system reliability, automatic backup functions, experienced supervision, remote monitoring and alarms are required when working in or adjacent to open water. High flows, tidal variations and quick recovery times means that care and consideration is key. Once this is understood and suitable systems are put in place, dewatering has been used with great success and reliability to not only dewater cofferdams, but also reduce the amount of propping and shoring that would have otherwise been required. WJ can offer proven solutions that bring confidence and that can reduce overall programme time and costs.