sentences:  The Trust for Public Land is working in partnership with the City of Los Angeles' Community Redevelopment Agency, Bureau of Sanitation, the University of Southern California's Center for Sustainable Cities, and Jefferson High School by converting the existing 900 miles of alleys in the city to green alleys.The concept is to re-engineer existing alleyways to reflect more light to mitigate heat island effect, capture storm water, and make the space beautiful and usable by the neighboring communities.The first alley, completed in 2015, saved more than 750,000 gallons in its first year.