WEST PALM BEACH — Aquifer Storage and Recovery (ASR) wells planned as part of the Lake Okeechobee Watershed Restoration Project (LOWRP) were on the agenda at the Feb. 27 Water Resources Accountability Collaboration (WRAC) meeting at the South Florida Water Management District Office.
Jennifer Leeds, of the SFWMD Everglades Coordination Division, explained the ASR wells are situated within confining layers of the aquifer. She said these layers are clay-based.
ASRs store and recover volumes of water underground. The water might be stored for several months or more than a year. Because ASR wells have a small footprint, they can be installed on property already in state ownership, and no additional land purchases will be needed.
She said from pilot projects, they found ASRs tend to remove phosphorus from the water. She said they can also temporarily liberate arsenic at the startup, depending on the geology. Testing helps them determine the most productive sites for the wells.
“An ASR well is not a disposal well,” she said. When you put water down a disposal well you can’t recover it. With an ASR well you can have a high rate of recovery.
The ASR wells planned north of Lake Okeechobee will target the upper and middle zones within the Floridan Aquifer, Ms. Leeds explained. A well pair might have one well that goes into the upper Floridan and one that goes into the middle Floridan, but the water will not move between the two because the confining layer between the aquifer prevents the movement of water.
“The locations we are looking at are all north of the lake,” said Ms. Leeds. They will also target areas such as the Kissimmee River and Taylor Creek/Nubbin Slough. These locations would also allow them to pull water from Lake Okeechobee.
Putting water into a well is called “recharge.”
“It is meant to capture water that would otherwise go into the lake,” she said.
“This will help us with high lake levels by capturing water before it goes into the lake,” she explained.
Before the water is pumped into the ASRs, it will be treated to drinking water standards, she continued. This process is regulated by FDEP.
Taking water out is called “recovery.” Recovery can be used when the lake is low to deliver more water to the lake and bring it back up to the ecologically preferred band.
Two test wells have successfully demonstrated the objectives of the Comprehensive Everglades Restoration Plan (CERP) with high capacity and high recovery rates, she said. The Kissimmee ASR was constructed in 2009 and tested from 2009 through 2013. It has been idle since 2013. The L-63N well was constructed and tested by SFWMD in the 1980s. It has been sitting idle since then.
The Kissimmee ASR can deliver about 15 acre-feet of treated water per day or about 5 million gallons per day. The L-63N well could have capacity up to 10 million gallons a day.
The wells will be installed in clusters.
“We are looking at refurbishing both of these wells and getting them back up and running,” she said.
Two new sites are under consideration for exploratory wells. Both are on the Kissimmee River.
SFWMD received funding for fiscal year 2020. In 2020, the two existing wells will go through permitting process for refurbishment. Two new well pairs will go through design and permitting.
Fiscal year 2021 and 2022, existing ASRs will be up and functioning. Construction will be done at the two locations for new wells and cycle testing will begin.
Bob Verrastro, SFWMD lead hydrologist on the project, said “ASR wells were never intended by themselves to capture peak flow.” He said they will work with other CERP projects. ASR wells are considered just one “tool in the toolbox.”
“The power of ASR is we do get storage without buying land,” he said.
He said CERP initially called for more than 300 ASR wells. He said after testing and modeling they reduced the plan to 80 wells.
Gene Duncan with the Miccosukee Tribe said the tribe does not support ASR. He said shallow impoundments would give the state “more bang for the buck” because above ground impoundments also provide habitat for wildlife.
“These are relatively small amounts of water,” said Dr. Albrey Arrington, executive director of the Loxahatchee River District. ‘But if I am experiencing pain, if I can reduce that pain even a little bit, I am pretty happy. The estuaries experience pain with excessive freshwater flows, so any excessive flows that can be not discharged to the estuary is a good idea.”
Dr. Arrington suggested they consider co-locating a disposal well with each network of ASRs. He said if an ASR can’t be used for any reason, an injection well is a way to dispose of water without sending it through an estuary. If the science shows on the first flush there are high arsenic levels, that could be disposed of through the injection well.
“I’ll remind people the leachate from the landfill is pretty nasty stuff. That gets thrown away through a deep injection well. Deep injection wells are used throughout Florida to get rid of some pretty nasty stuff,” he added.
Another WRAC member pointed out ASR is a critical tool because it provides a way to store water when above-ground storage areas are already at capacity, and the water is available for use when needed in the dry season for environmental use and/or urban and agricultural water supply.