Technical director Adrian Judd said: "These projects clearly exemplify our value beyond engineering approach, as we worked to create forward-thinking and inspiring projects that improve places for both people and nature."
His practice won a team achievement award for Southend-on-Sea seafront regeneration, which created more space for pedestrians, new planting and high-mast lighting.
The other two ICE awards went to a West Cambridge infrastructure project for the University of Cambridge including a new square, terraced gardens, bio-diverse lake and new pedestrian and cycling routes.
The three awards follow success in June at the RIBA Awards where judges praised a sustainable urban drainage scheme that improved site biodiversity at a student village for the Royal Veterinary College.
Leeds-based Grontmij took over the practice Whitelaw Turkington four years ago and rebranded to the parent name in 2011.
The group has more than 100 landscape architects and urban designers.