CAD Drafting Design Submission ELS Works Services Steelwork ELS for Open Trench Excavation at 4.0m Depth December 11, 2011May 11, 2017 admin 1062 Views els, open excavation, steel, support Main Contractor Maeda-CREC-SELI Joint Venture Contract No. DC/2007/12 Tsuen Wan Drainage Tunnel