The following is about a new kind of green infrastructure planned for Minneapolis, as part of their new light rail system. It's quoted from The Minnesota Daily.
Tree trenches are urban infiltration systems used to filter runoff and ease street flooding and environmental issues.
Storm water will seep through permeable brick pavers passing through several layers of soil and drainage rock. The runoff will in turn water 1,200 newly planted trees along the light rail’s route in St. Paul.