The city of Anderson, Ind., recently completed a downtown beautification project utilizing green infrastructure in the streetscape. Downtown Anderson, which is 32 miles northeast of Indianapolis, has a combined sewer system, and the goal of the project was to significantly decrease first flush runoff to the combined sewers and thus decrease combined sewer overflows.
Jeremy M. VanErman, assistant storm water superintendent for the city of Anderson, designed a tree well box with Xeripave Super Pervious (SP) pavers, which provide storm water management by reducing, redirecting and reusing runoff. Through the tree well design, VanErman planned to utilize the runoff to water the trees through a natural watering routine.
After the project was installed, the city noticed that the tree wells were performing better than expected by taking in much more water than intended, which prevented the excess water from flowing to the downtown buildings. The water instead flows to the planter boxes, where the pavers filter out sand, leaves and urban debris while allowing the water to flow through. What does not flow into the well goes down the curb to the drainage system.
The drainage system consists of granular backfill and slots in the concrete walls connecting the tree wells to the planter boxes, which allow for a high level of percolation into the soil. VanErman noted that the pavers were less expensive than other options, and can be removed incrementally as the trees grow. The pavers in the tree well application also are reducing maintenance, water and material costs.