Underground storage system aims to solve water woes
Oldsmar plans to build the reservoir to collect water in the rainy season for use when it's dry.
By TERRI BRYCE REEVES, Times Correspondent
Published September 14, 2007
OLDSMAR - Think of it as a space saver, one that officials hope will solve water woes for years to come.
The city of Oldsmar plans to build an aquifer storage and recovery ASR facility, an underground reservoir surrounded by monitoring wells. The facility will store reclaimed water when rainfall is plentiful for use during drought season, when demand is high.
Why not build above-ground tanks?
It would take up too much room, officials say.
"The real fact of the matter is, you'd need to build too many tanks and couldn't make them big enough to match the capacity," said Bill Proses, city engineer.
The desired capacity?
Big enough to store more than 225-million gallons of water.
Plus, the ASR well won't need walls to hold the water.
"It will be a natural tank, created from rock formations," said Proses.
Here's how the ASR works: Water is injected into theunderground tank, where low permeability clay and rock will keep it from seeping through the storage layers. The injected water displaces the existing lower-quality groundwater.
"When they pump the water in, they will be displacing brine (saltwater). It creates sort of a bubble like in a lava lamp, but the bubble doesn't move around," Proses said.
He said the different densities of the salt and fresh water prevents mixing.
Just to make sure, monitoring wells will test to make sure water quality problems don't occur.
Jones Edmunds and Associates, an environmental engineering consultant, will design the first of the wells, an exploratory one. The construction of the first well is expected to begin in October or November and be completed by April 2008. The cost of the well is $118,000, with the Southwest Florida Water Management District chipping in about $48,000.
The results from the first well, which will be up to 800 feet deep, will help guide the installation of the ASR and other monitoring wells. The wells will be built at the city's water reclamation facility, 351 Lafayette Blvd., over the next three to four years.
Officials say the project will not only provide increased availability of reclaimed water during the dry season, but it will have a positive impact on the environment, particularly Mobbly Bay.
The city's reclaimed water plant discharges an average of 700,000 gallons of highly treated unused water into Mobbly Bay daily. In the very rainy September of 2006, when demand was very low, the plant released 1.6-million gallons a day into the bay, said Proses.
The new facility will give city officials a place to store reclaimed water and cut down on the need for discharging it, officials said.
In fact, the ASR will make reclaimed water so accessible, the city is even considering selling some to the county. During the drought earlier this summer, watering restrictions were placed on some reclaimed water users in Oldsmar and elsewhere in the county.
Currently about 37 percent of the city's residential, commercial and industrial water users have access to reclaimed water. By the fall of 2009, homeowners in the downtown area should be sprinkling their lawns with reclaimed water, Proses said.
"It's a win-win situation," Proses said. "We'll be able to reduce the need for potable water and provide more irrigation water for those who need it. At the same time, it will be good for the health of the bay."Terri Bryce Reeves can be reached at firstname.lastname@example.org.
225M Desired number of gallons for the tanks to hold.
700,000 Gallons the city's reclaimed water plant discharges on an average day.
1.6MGallons released on a recent low-demand rainy day.