The Broadous School demonstration project was part of the Los Angeles Department of Water and Power's Cool Schools program, of which TreePeople was a major partner.
The campus of the Hillery T. Broadous Elementary School in Pacoima was suffering from periodic flooding that sometimes reduced student attendance by as much as 15 percent.
A sustainable solution
With the support of the school district, the site was retrofitted to capture, treat and hold all the rain falling there, reducing the flood risk and recharging the groundwater.
An underground infiltration system, a swale, permeable ground cover, and strategically planted trees replaced over 30 percent of the asphalt that once covered the campus. Energy use was also reduced by shading and cooling the buildings and their air conditioning units.
Construction of the infiltration system was completed in February 2001. Three tree-planting events, involving the school’s students and community members, completed the transformation of the campus.
A collaborative effort
The Broadous retrofit was a collaboration involving TreePeople, the L.A. Unified School District, the Department of Water and Power, Pacoima Beautiful (a community action group), the city council district, landscape architects and the engineering firm of Montgomery Watson (now MWH).
The project’s three components – a swale, a stormwater separator and an infiltration basin – work together to capture and clean stormwater runoff and recharge the groundwater. They also reduce flooding in the downstream area.
A swale is a mulched or vegetated strip that slows runoff and enables the water to soak into the soil. It also begins the process of cleaning the runoff by filtering pollutants from it.
Originally, the swale we created for the Broadous school was planted with vegetation. Unfortunately, the school district removed the vegetation and paved the swale to simplify the movement of delivery trucks.
This means that the swale no longer serves its primary function of slowing and cleaning runoff. But it still helps channel water to the treatment and infiltration systems we created on site.
The separator is a stormwater treatment device that uses the mechanics of moving water to settle sediment, skim off pollutants and separate trash from the runoff before it's delivered to the infiltration basin. The unit used for the Broadous project is a Vortechs 9000.
Two hundred twenty plastic chambers shaped like inverted “U”s make up the infiltration basin. They create temporary underground storage for campus runoff, which gradually percolates through the soil to recharge the groundwater.
The separator and infiltrators work silently beneath a new grassy playing field.
Further details on this project can be found in Rainwater as a Resource, TreePeople’s report on three of its stormwater demonstration sites.