Miracle Mile: A living streetscape designed to mitigate intense rainfalls
At a hub of local commerce, the Miracle Mile and Giralda Plaza are newly-rebuilt streetscapes well-equipped to bear the brunt of the increasingly
intense rainfall in Miami. Networked green infrastructure – consisting of large canopy trees rooted in a continuous trench of shared soil – absorbs
and filters stormwater, combats urban heat island effect, and defends the shops and restaurants from flash flooding. Designed to handle a rain
intensity of 8” pr hour, it is the most flash-flood resilient street in America. Its capacity was put to the test when Hurricane Irma struck in 2017,
unleashing 7” of water per hour. The Mile performed as designed: one business owner, who was unable to reopen another of her businesses in
Miami for months due to flood damage, was open for business on the Mile the day after the hurricane. The investment in natural systems to
combat the early impacts of climate change has paid dividends not only in protecting and stabilizing this business district, but in the additional
benefits of urban place-making, passive cooling, and sustainable groundwater management. As a designer on the project, I took an approach that
incorporates networked green infrastructure, manifested as a newly planted and transplanted large-caliper street trees connected by a shared
trench of subsurface structural soils. The space afforded by this generous, shared soil volume allowed the trees to spread their roots expansively,
giving them the stability necessary to weather hurricane winds without toppling. Porous pavement allows stormwater to infiltrate to the well-drained
subgrade, and surface drainage is directed toward the street trees. Only after these systems are fully saturated is the frail, overtaxed
existing storm pipe pressed into service: it now operates as an overflow, and thus the last line of defense instead of the first and only
intense rainfall in Miami. Networked green infrastructure – consisting of large canopy trees rooted in a continuous trench of shared soil – absorbs
and filters stormwater, combats urban heat island effect, and defends the shops and restaurants from flash flooding. Designed to handle a rain
intensity of 8” pr hour, it is the most flash-flood resilient street in America. Its capacity was put to the test when Hurricane Irma struck in 2017,
unleashing 7” of water per hour. The Mile performed as designed: one business owner, who was unable to reopen another of her businesses in
Miami for months due to flood damage, was open for business on the Mile the day after the hurricane. The investment in natural systems to
combat the early impacts of climate change has paid dividends not only in protecting and stabilizing this business district, but in the additional
benefits of urban place-making, passive cooling, and sustainable groundwater management. As a designer on the project, I took an approach that
incorporates networked green infrastructure, manifested as a newly planted and transplanted large-caliper street trees connected by a shared
trench of subsurface structural soils. The space afforded by this generous, shared soil volume allowed the trees to spread their roots expansively,
giving them the stability necessary to weather hurricane winds without toppling. Porous pavement allows stormwater to infiltrate to the well-drained
subgrade, and surface drainage is directed toward the street trees. Only after these systems are fully saturated is the frail, overtaxed
existing storm pipe pressed into service: it now operates as an overflow, and thus the last line of defense instead of the first and only