Monday, January 10, 2011

Green Roofs Help Clean and Attenuate Stormwater Runoff

Roof Drains, Jacksonville, Florida
The photos here are of a commercial facility adjacent to a hospital on Beach Blvd. in Jacksonville, Florida. 

The commercial facility has a large flat roof with stormwater runoff collected in the gutters and directed towards a ditch running through the hospital then down a larger creek/ditch directly into the St. Johns River and out into the Atlantic Ocean.

Roof Drains send water into the St. Johns River
The technology shown is no different that the gutters and ditches we see in excavations in old cities of the Roman Empire.

We've had well over 2,000 years as a civilization to think about our water resources and the way we treat stormwater.

The bad news is our rivers, lakes, streams and oceans have become more and more polluted.  Here in Jacksonville the St. Johns River becomes filled with green algae every summer due to the high nutrient loading in stormwater runoff.

The nutrients are primarily from residential and commercial lawn care and application.  Smog and air pollution is another source of nitrogen, one I refer to as another form of 'slow release fertilizer' becuase the smog deposits on roofs and is washed into adjacent waterbodies during a rainfall event.

The photo depicted here is of the Caloosahatchee River in Florida. 

Though the Caloosahatchee is not representative of all the rivers in Florida, it is however representative of a serious problem we have in Florida - that of nutrient runoff into our waterways.

The good news is Green Roofs can help to reverse the nutrient runoff problem by filtering atmospheric nitrogen and other nutrients from stormwater runoff, sequestering carbon and removing particulate matter that phosphorous may bind with.

Green roofs must take the lead and add zero additional fertilization to our ecosystems.

Green roofs must be designed to survive on atmospheric nutrients, leaf litter and detritus from the green roof plants and adjacent sources, bird feces and other natural sources of fertilization.

To be sustainable, green roofs must not use broadcast type fertilizer applications, fast or slow release.

Green roofs are about being eco-friendly.

The good news, again is green roofs can provide a solution.  Green roofs can:
  • Filter and clean stormwater
  • Provide much needed habitat for wildlife
  • Provide habitat for rare and endangered plants
  • Sequester Carbon, Nitrogen, Phosphorous and othe pollutants
  • Provide Oxygen and clean SMOG
  • Provide beauty to the asphalt jungle
Green roofs are one of the 'Green' answers to the global water quality crisis.

As always email your questions or comments here.

Happy green roofing!  Kevin

1 comment:

Anonymous said...

New York has similar problems with Storm Water Management. Recently they announced a Green Infrastructure Plan that should add the equivalent of 3.5 Central Parks in green roofs. Please check for more information!