Sentence:  Excavate the soil to a depth of at least 1 metre (3 feet) and make sure that the soil in the <WSD>tree well</WSD> or within at least 2 metres (6 feet) of the tree is free of rocks and debris. 
Meaning of the word marked with <WSD> tags:  A structure designed to protect the base and roots of a tree, typically used in an urban setting.