Innovative Recharge Project at Stow Center School

Permeable paving and recharge chambers: Center Elementary School, Stow

Porous asphalt paving and a system of subsurface infiltration chambers recharge stormwater runoff from 1.3 acres of rooftop and a half acre of paving. Previously discharging to a small tributary to Elizabeth Brook, the school site, although nearly doubled in size by the renovation, now has a reduced overall impermeable footprint. The subsurface chambers have a 360,500 gallon capacity. The visitor parking lot, accessed from Great Road, and a fire lane have been constructed of porous asphalt on top of a deep sand and gravel bed which rapidly drain, filter, and recharge the rainfall and snowmelt.

This is the largest porous asphalt installation in the Assabet watershed. Porous asphalt filters pollutants out of stormwater and allows runoff to soak into the ground thus reducing flooding and pollution of local streams. Research at the University of New Hampshire Stormwater Center shows that porous asphalt drains rapidly, and is therefore less susceptible to the freeze-thaw cycles and black ice formation typical in New England. The pavement has been shown to require less plowing, salting, or sanding than standard asphalt. This benefits both the taxpayer and the environment.

The project will reduce polluted stormwater flows entering Elizabeth Brook while enhancing clean groundwater contributions to the brook’s base flow. The project was completed in 2012.

Method used: Porous asphalt on a sand and gravel bed to pave visitor parking lot and firelanes; rooftop stormwater directed to three large Cultec underground chamber systems.

Sub-watershed: Elizabeth Brook

Recharge estimate: 2.5 million gallons per year

Intel grant: $300,000 for construction

Town contribution: Engineering and staff time

Location: Center Elementary School, Stow

Contact: Building Commissioner/Elementary School Building Committee, Tel: (978) 897-2193

“From the outset we were hoping to make our new elementary school as environmentally friendly as possible. We are grateful for the Intel/OARS grant that provided early support to fund this innovative system. It will not only be good for our local watershed, but is an example to other school projects.” Ellen Sturgis, co-chair of the Elementary School Building Committee

Fire lane paved with porous asphalt at Stow Center School