Simulator shows how pollutants get into groundwater

July 18, 2001

TALLAHASSEE, Fla. — A sand-filled plastic box is giving some Florida school children a clearer picture of how fragile the state’s precious groundwater supply is and how not to pollute it.

With its tubes, compartments and plastic pipes, the groundwater simulator is the perfect model to help show people why it’s so important to think about what they put on the ground, pour down the sink or dump into the storm-water drain, said Cynthia Brown, Leon County extension agent with the University of Florida’s Institute of Food and Agricultural Sciences.

“This simple device clearly shows where pollutants ultimately end up and how they affect the quality of groundwater that eventually becomes drinking water. People need to consider that what they do with automobile oil, pesticides and even fertilizers can impact the environment,” she said.

Although statistics are unavailable quantifying the effects of pollution on groundwater, Florida’s aquifer is even more susceptible to contamination by pollutants dumped on the ground than other states that have a more rocky terrain, said Tyler Macmillan, a water resource planner with the Northwest Florida Water Management District.

“In many areas of Florida, the porous limestone that makes up the terrain provides little or no protection to the aquifer,” Macmillan said. “Pollutants on the land surface can flow right into the aquifer in these areas.

“This means nutrients from overfertilized lawns, contaminants dumped onto the ground or leaking septic tanks are certainly more prone to contaminate the aquifer,” he said.

Currently, Leon County is the only one of Florida’s 67 extension offices to use the device for demonstrations at schools and community gatherings. However, Orange County Extension Agent Dennis Mudge said the groundwater simulator would be a great tool to help combat what he said is a major problem in his urban county.

“Dumping even small amounts of chemicals on the ground is a bigger threat to groundwater than people think,” Mudge said. “Many people still have a misconception that we have a limitless water supply in Florida that can’t be damaged. They think the sand will act like a filter and take care of everything.”

Mudge said he is looking into the purchase of a simulator.

Sand and plastic parts in the simulator mimic different types of soil ranging from limestone to solid bedrock that water calls home until it is tapped as a drinking source. The device uses an aquarium pump to move water from sections representing lakes and streams to parts of the system that play the part of a reservoir or a septic tank.

Brown said colored dyes allow the system to show how contamination moves underground.

“Put a little bit of dye into the simulator’s underground storage tank and you can see where it would travel throughout the groundwater layers if the tank leaked,” Brown said. “It can show how quickly material leaking from a septic tank disperses throughout the groundwater.”

The device also can simulate oil being dumped on the surface and show how it seeps into the groundwater and eventually into drinking water.

The ability to let people see what happens underground is what makes the groundwater simulator unique, said Bill French, president of Crystal Scientific, the Galesburg, Mich.-based company that builds the device.

“It’s hard to teach people about groundwater because they can’t see it,” French said. “The groundwater simulator allows individuals to visualize what takes place, to see what happens to the groundwater.”

French said each simulator is assembled by hand to meet the specific needs of each customer so the simulator reflects the geology of the area in which it will be used.

“Our groundwater simulators are hydrologically correct, so what you see in the simulator happens out in the real world,” French said. “What we’ve done is change the scale of it and the length of time it takes to happen.”