Faced with increasing demands and costs for potable (safe to drink) water, as well as increased salinity in the shallow coastal aquifer, the Ft. Lauderdale-Hollywood International Airport was searching for an alternative to potable water irrigation for 30 acres of mature tropical landscape on its property. The area, known as the Greenbelt, has become a community recreation and exercise area since it was first established more than 20 years ago. To reduce its environmental footprint, the airport asked RS&H to evaluate alternative irrigation options for the landscape.
Last year, RS&H hydrogeologists focused on a stormwater pond excavated into the highly permeable Biscayne aquifer on the northeast portion of the airport’s property. Historically, the pond’s water quality was described as being exceptionally clear. The pond also benefited from significant recharge from the airport’s runways and taxiways. With more than 70 million gallons of rainwater collected by the pond each year, the resultant groundwater mounding appeared to isolate the pond from elevated chloride levels in the area. In essence, the pond was functioning as an untapped rain barrel, a rather large 13-acre rain barrel. The analyses determined that the stormwater pond had the potential to easily satisfy the irrigation demand for the Greenbelt.
Hydrogeologic research, water quality analyses, regulatory reviews, and a constructability assessment verified that the stormwater pond was a viable collection point for the airport’s large-scale rainwater harvesting system. The pond, which is equipped with three pumps, could pump 780 gallons per minute. The South Florida Water Management District permitted this system up to 147 acres, which excluded the Greenbelt area. Review of the permitted acreage revealed the presence of more than 45 acres of roadway. The roadway was removed from the water use permit and reapplied to the 30 acre Greenbelt area.
The Florida Department of Transportation (FDOT) District 2 office, who owns the pond, was highly supportive of the initiative. The management district was supportive as well, since the innovation would reduce the amount of water being withdrawn, while conserving more than 15 million gallons of potable water each year.
Currently, the conveyancing system, which will move the water from the pond to the landscape, is being designed and construction should be completed by the end of 2014. The conceptual design approved by the airport’s board has a payback period of one year and a projected return on investment more than three times the construction cost over a five-year period. This rainwater harvesting solution preserves precious potable water resources for a coastal community that is challenged by saltwater intrusion. In addition, it also reduces the airport’s operating costs and preserves a beautifully landscaped public park and community buffer.
–By Mike McCarthy