Boston Architectural College Green Alley Initiative

The Boston Architectural College (BAC) installed a green alley demonstration project on its campus located in the Back Bay area of Boston along the Charles River.  The green alley used permeable pavement to allow stormwater to percolate through the road bed to recharge groundwater and filter pollutants.  The project was designed to be replicable and to help with public education on the benefits and design of green infrastructure. The purpose of the green alley is to reduce polluted runoff by filtering and redirecting rainfall to the groundwater table. The BAC estimates that its project conveys 361,400 gallons of rainfall annually to groundwater recharge and that the project reduces annual rainfall runoff by 83%. Along with their stormwater management benefits, green alleys are also used as a strategy for reducing urban heat islands.  Boston is expected to become hotter and receive more precipitation with climate change, thus green alleys could be an effective strategy at mitigating impacts from these climate change effects.

The BAC green alley was designed with permeable asphalt and permeable unit paver systems, which were layered on a gravel bed.  The project was designed to collect, store, and filter rainwater from the green alley’s surfaces. The green alley also collects rainwater through downspout re-routing from two BAC rooftops on the college’s 951 Boylston Street building and 320 Newbury Street building. The permeable paving allows stormwater to percolate into the earth below rather than be conveyed across a paved, impermeable surface to the nearby Charles River via a conventional storm sewer. By conveying rainwater directly into the ground, the green alley separates stormwater from wastewater and replenishes the Back Bay’s water table. The project is also designed to protect Bay Back infrastructure; the Back Bay is built upon wooden piers that need to be constantly submerged or they decay.  Because of impervious coverage in the region, the groundwater table is unable to recharge and the lack of water is causing the piers to decay.  By creating permeable surfaces the green alley project will help to recharge groundwater to provide the water needed to preserve the wooden piers. The BAC is also monitoring the effectiveness of the green alley project over time as well as sampling the quality of the Back Bay groundwater table.

The U.S. Department of Energy provided $1.6 million in financial assistance to fund the green alley project and a geothermal well to provide heating and cooling for campus buildings, pursuant to a Congressional earmark to the BAC. The BAC funded the remainder of the project, contributing about $2.1 million.

 

This Adaptation Clearinghouse entry was prepared with support from the Federal Highway Administration. This entry was last updated on January 14, 2015.

 

Publication Date: October 2013

Related Organizations:

  • Boston Architectural College
  • U.S. Department of Energy (DOE)

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  • Best practice
  • Case study
  • Education/training materials

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