ASR Pilot Projects Deliver Hope to Lake Okeechobee Deluge Sufferers
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Dean Powell, director of the watershed management program at South Florida Water Management District, offered a promising status report last week on a little-known pilot program to store and convert bad water to good in the upper Lake Okeechobee basin.
The original Comprehensive Everglades Restoration Plan relied heavily on Aquifer Storage and Recovery (ASR) technology, though not everybody involved was a believer when CERP was approved in the Water Resources Development Act of 2000. Nevertheless, Congress directed the U.S. Army Corps of Engineers, in partnership with the SFWMD, to undertake a pair of pilot projects to see how well the technology works, or if it would at all.
ASR "plants" have been used in Florida and throughout the United States for about 30 years, Powell said. What they do is to inject and recover treated and untreated groundwater, partially treated surface water and reclaimed wastewater.
SFWMD officials say that after dealing with damaging freshwater discharges from Lake Okeechobee, what should catch everybody's attention is the technology itself, making it possible to store more water than a typical above-ground reservoir.
In fact, Ernie Barnett, aquatic biologist and assistant executive director of SFWMD, described ASR as the CERP feature that dealt with lake releases to the estuaries, and the two pilots are proving it can work as originally envisioned.
In the proper location, for example, where the Kissimmee River connects with Lake Okeechobee, the first pilot has been operational through several cycles. That facility actually stores 3,000-acre feet of water on a footprint of 2 acres with 100 percent recovery efficiency.
"A very large side benefit is that it is improving the water quality," Powell said. Inflow water comes in from the Kissimmee with 130-150 ppb phosphorous count, but goes out at between 10 and 30 ppb.
The second pilot, the Hillsboro ASR pilot, is newer. Well rehabilitation was required on the site. It has a lower recovery efficiency -- 40 percent at present -- because the aquifer is more saline. The system has had only three test cycles through 2012; its efficiency number should increase as time goes on, Powell said during his presentation.
Certainly there are challenges involved with ASR, but Powell and other scientists believe they can be overcome. Among them: initial monitoring is expensive; wells can be susceptible to clogging; and chemical reactions in the aquifer could produce arsenic, though that problem is among the easiest to resolve.
Each well costs about $4 million to construct, with a very small land footprint. Thus, land purchase is virtually negligible.
Powell says the groundwater model shows the aquifer can support 140 wells without losing its integrity.
Most ASR facilities in Florida, primarily owned by municipalities, store water in the upper Floridan Aquifer in areas where the aquifer is brackish. The injected fresh water displaces brackish water in the aquifer to form a "freshwater bubble."
Powell also gave his ASR presentation to the National Academy of Sciences when the group met in West Palm Beach on Tuesday.
Reach Nancy Smith at firstname.lastname@example.org or at 228-282-2423.