The proposed site would drain into Cypress Creek, the main tributary of the Hillsborough River, a key source of the region's drinking water.
By JAMES THORNER
Published April 18, 2004
LAND O'LAKES - Parking lots are rarely pristine.
If it's not the candy wrappers, half-eaten hamburgers and cigarette butts, it's the splotches of motor oil, axle grease and transmission fluid leaking from cars.
Now imagine the fate of that gunk when a typical Florida downpour washes the parking lot with tens of thousands of gallons of rainwater.
In the case of Cypress Creek Town Center, a mall that developers plan to wrap with thousands of parking spaces, the tainted water would beat a path toward the natural drain of Cypress Creek along the site's southern boundary.
Mall developers suggest ponds and wetlands will contain and filter about 90 percent of the pollution before it hits the creek. Environmental scientists aren't so sure.
The debate is key for the hundreds of thousands of Tampa Bay area residents who get some or all of their drinking water from the Hillsborough River. Cypress Creek is the river's main tributary.
As of Friday, 1.1-million gallons of water an hour streamed through Cypress Creek along the 511-acre mall site at Interstate 75 and State Road 56 in central Pasco County.
"It's a super site for development and highly desirable for Pasco County, but an unfortunate site for the Hillsborough River and Cypress Creek," said Mikel Renner, the planner who scrutinized mall plans for the Southwest Florida Water Management District.
Representatives of land owner Robert "Hi" Sierra claim stormwater running off the mall site once it opens in 2007 or 2008 might actually improve water quality.
Today, cattle pasture predominates, and runoff is laced with cow manure and fecal coliform bacteria. Remove the cows, remove the bacteria. Or so the argument goes.
Betty Rushton is skeptical. An environmental scientist with the water management district, she authored a 1999 study on parking lot runoff. The study measured pollution produced by an experimental, heavily landscaped parking lot at the Florida Aquarium in Tampa.
Even when 10 percent of a parcel is paved over, degradation of nearby streams begins. Erosion tends to increase. So does exposure to pollution. Animals die.
"There are things you can do to lessen the impact," Ruston said of the influence of large developments on streams. "But you're never going to get it back to the way it was."
Parking lot runoff is an unsavory soup. Discarded food turns to mush. Petroleum products add a familiar rainbow tint to rushing rainwater. Asphalt contains its own volatile chemicals and heavy metals that seep into the environment.
It doesn't take much of certain chemicals to ruin a creek. A quart of motor oil can send a slick across 250,000 gallons of water. For a mall lot that attracts thousand of cars daily, a quart of oil is a drop in the bucket.
Mall proponents said they have yet to quantify how many petrochemicals, metals, pesticides, fertilizers and sediments would wash from their parkings lots and roofs.
The mall would top out at 1.5-million square feet, making it among the region's largest.
Engineers estimate parking spaces could surpass 6,000 at the mall and adjacent stores, hotels and offices.
In documents reviewed by government planners, mall officials cut short further inquiry, at least for now: "No in-depth analysis of pollutant loading has been conducted as specific engineering designs have not been completed."
Complicating matters is the special environmental protection afforded Cypress Creek. Since 1995, the creek, as a major branch of the Hillsborough River, has been deemed an Outstanding Florida Water. That means development can't degrade its water quality.
Only 40 of Florida's 1,700 rivers and streams are Outstanding Florida Waters. The designation isn't supposed to shut down development, but to impose more stringent pollution controls.
Sierra's mall application offers limited detail about such controls. But landscaped parking lot islands and stormwater holding ponds figure in the plans.
Scientists agree the best way to protect streams is to stem the flow of stormwater from developments. Landscaping and ponds let water seep underground or evaporate before it reaches rivers.
Oils and grease are trapped in the decaying plants at bottom of the ponds. So are heavy metals. In a successful system, bacteria set to work dissolving petroleum products. Sand acts as a further filter. The assumption is that pollutants need 14 days to settle out of the water.
In theory, the system is sound for storms producing up to 1 inch of rain. For larger rains - about 10 percent of storms central Florida - the system doesn't perform as advertised. Tainted water, albeit diluted, may flush prematurely from the ponds.
Sierra's application makes it clear that no untreated storm water will pour directly into the creek. A pond on the south side of the property near Cypress Creek would contain much of the runoff.
Only then would water spill into wetlands, further "polishing" the water before it enters the creek.
Hampering such natural filtering functions is Sierra's proposed destruction of more than 60 acres of wetlands on site.
In compensation, developers propose preserving and creating wetlands elsewhere within the Hillsborough River drainage basin, too far from the mall site to help buffer that section of Cypress Creek.
Mall spokeswoman Beth Leytham said further details await "advanced engineering" that would not take place until the project was approved by Pasco commissioners, a vote scheduled for July. "We certainly intend to comply with every requirement," Leytham said.
Tampa Bay Water, the regional water utility that taps Hillsborough River water, would sign off on the mall were all such stormwater traps installed, said Paul Dye, the utility's chief environmental planner.
"Development is compatible with the water supply," Dye said. "It just needs to be done correctly."
The mall application touts test studies performed by the water management district that show such systems removed 94 percent of solids, 90 percent of phosphates, 87 percent of zinc, 94 percent of iron and 90 percent of ammonia from stormwater.
Those numbers could be problematic. Rushton, the author of at least one of the studies, said such pollution reduction assumes developers used porous pavement.
Rushton's numbers were obtained in a lot at the Florida Aquarium using penetrable concrete. Large gardens at the end of parking rows further siphoned off rain.
"If they can build a parking lot like that then maybe they would get 90 percent but otherwise they're not going to," Rushton said.
Sierra's representatives said it's too early to tell if they will use traditional pavement or the more expensive porous varieties. Nor have plans addressed how widespread water-draining traffic islands in the parking lot will be.
"I just don't think it's that point in time yet," Leytham said. "After the plans are approved they'll decide about what kind of asphalt ... we're just not there yet."
Regulators have stressed that stormwater pollution controls are only as good as the maintenance. They've insisted on yearly engineering checks to ensure weeds haven't choked the flow or erosion hasn't breached holding ponds.
Nevertheless, suspicions remain that, despite the property's virtues as a commercial tract, it's too environmentally valuable to accommodate millions of square feet of concrete and asphalt.
Said Renner, the water district planner: "If there were a site I'd like to see preserved, this is it."
