Trenches have been dug in the Botanical Gardens to supply water for a cooling system for King Edward VII Memorial Hospital’s new facilities.The excavations, which can be seen near the park’s South Shore Road entrance, will carry pipes for well water, according to a spokesman for construction company Paget Health Services.The water supply, to be pumped from four new wells, will be salt rather than fresh.In a process used by many of the Island’s large commercial buildings, the seawater will go back into the ground after passing through a heat exchanger. It will help cool the hospital’s chilled water system.New pipes will also have to be laid along South Shore Road as well.The job, which will temporarily affect traffic, is expected to start in a few weeks’ time.