Stormwater runoff is generated from rain events that flow over land or impervious surfaces, such as paved streets, parking lots, and building rooftops, and does not soak into the ground. The runoff picks up pollutants like trash, chemicals, oils, and dirt/sediment that can harm our rivers, streams, lakes, and coastal waters.
On average, Miami-Dade County receives over 60 inches of rainfall per year.
Events like tropical storms and hurricanes may bring large amounts of rainfall to the region in a short period of time. However, we don’t need a hurricane for us to experience a significant rain event. Most recently, during this past Memorial Weekend, parts of the County saw over 17-inches of water in less than 4 days.
Many parts South Florida, including Coral Gables, sit on porous limestone, allowing rainfall to percolate into the ground through the limestone and help recharge our aquifer.
In the City of Coral Gables, our stormwater system consists of:
Approx. 2,700 Catch Basins
Approx. 20 miles of pipes
Approx. 53,000 LF of exfiltration trenches and slab covered ditches
2 Pumps stations
Over 42 miles of coastline/waterways
Exfiltration trenches and slab covered ditches operate by taking storm water runoff captured by inlets and catch basins, bypassing impermeable surfaces such as pavement, parking lots, driveways, sidewalks and roofs, and diverting the flow underground into the limestone subsurface. Some of these systems may include overflow connections to outfall pipes into our waterways or one of our 2 storm water pump stations.
Significant rain events may result in the saturation of the limestone subsurface, resulting in temporary ponding or flooding until this underground runoff can dissipate into our waterways. This can be exacerbated by the fall king tides and potentially future sea level rise.
Keeping our streets and stormwater system clean is crucial. Whatever ends up on our streets (litter/trash, harmful chemicals (pesticides, fertilizers, oils) and landscape debris) can clog our drains, enter our drainage system and eventually discharge into waterways and Biscayne Bay.
Better Management Practices Tips
Rainy days in South Florida and in Coral Gables are very common, and if not careful, these downpours may result in stormwater pollution. As stormwater flows over driveways, lawns and sidewalks, it can pick up debris, chemicals, silt, and other pollutants. So, what can you do to help? There are some things that you can do to prevent stormwater runoff pollution. Stormwater may flow into a storm sewer system or directly into a lake, canal or coastal water. Polluted runoff is the greatest threat to clean water.
How to prevent stormwater runoff pollution:
Minimize or eliminate fertilizer, herbicide and pesticide use (especially during summer months when rains are heavy) —or switch to organic varieties that are not harmful.
Never dump anything down storm drains or into canals, lakes, or streams.
Avoid over-watering your lawn.
Compost yard waste.
Sweep up debris.
Direct downspouts away from paved surfaces and consider a rain garden to capture runoff.
Take your car to the car wash instead of washing it in the driveway.
Check your car for leaks and recycle motor oil.
Pick up trash, pet waste and litter around your yard and home.
Difference between stormwater system and sanitary sewer system
Stormwater runoff is managed separately from our sanitary sewer system which carries human waste and sewage through a series of manholes and gravity and force mains that connect to Miami-Dade Water and Sewer Wastewater Treatment Plant at Virginia Key.