A big box parking lot requires 150% more surface area than the store itself. The planning goal is to reduce the deleterious effects of urban stormwater runoff from hard surfaces using Low Impact Development (LID) technologies. To promote decentralized water infiltration, an interior “parking room” of impervious surface is drained to a bioswale edge. This facilitates treatment of polluted water while reducing the heat island effect. Second, outside the bioswale ring impervious surfaces are replaced with vegetated rain gardens, infiltration trenches, and tree box filters or permeable grass paving. This allows for a size reduction of an unsightly detention basin, whose only ecological service is storage.