Elevated levels of fecal coliform are found at six homes in Hernando County after holes open in retention ponds near the Suncoast Parkway

BROOKSVILLE -- Daniel Hrivnak picked up a glass of water from his kitchen table and pointed to the think layer of grit that had accumulated on the bottom.

"Look at this," Hrivnak said lat week. "Our water is tan."

Hrivnak's well is one of six in his northern Hernando County neighborhood contaminated after a large sinkhole opened up in the bottom of a Suncoast Parkway retention pond last month.

Though a small amount of find sediment in the water is the most obvious pollutant, the most dangerous is fecal coliform, said Al Gray, environmental manager for the Hernando County Health Department.

His agency has recommended residents avoid drinking, cooking with or bathing in water from the tainted wells. Hrivnak and his neighbors are instead using water from a 300-gallon tank provided by the county.

"I never thought I'd have to live next to an expressway and draw my water from a damn tank when I was 56 years old," said Hrivnak, a mechanic on leave from his job because of a neck injury.

The construction of the parkway and the sinkhole are probably -- though not definitely -- related, said John Parker of the Southwest Florida Water Management District. The retention pond is on the west side of the parkway, about 3 miles north of State Road 50 and about 8 miles south of the Citrus County line.

In early July, several small sinkholes opened in this pond, as well as in one near the northern end of the parkway, said Joanne Hurley, parkway spokeswoman.

The digging of retention ponds can contribute to sinkhole formation in two ways, Parker said. By thinning the top layer of soil, it makes it weaker. And the water that collects in retention ponds weighs down on voids in the limestone subsurface.

On July 11, a group of workers from the district was watching the repair of sinkhole damage in the southernmost retention pond, Parker said. One of the holes suddenly widened, allowing thousands of gallons of muddy runoff to drain into the aquifer.

"By dumb luck we had a field team out there for observation and they actually saw some new holes form while the water was pouring in," Parker said. "Any time you have surface water running directly in the groundwater, you almost always have coliform. Fecal coliform --- that is an indication that you have some direct avenue to the aquifer.

The levels of bacteria found indicate it did not come from a concentrated source but from the waste of animals that live in this rural area, Gray said.

The average level of contamination in the six wells was about 20 unites per 100 milliliters (about 3 ounces) of water, he said. This makes it unsafe for drinking, but for example, perfectly safe for swimming, Gray said. The health department does not close swimming areas unless they find concentrations higher than 800 units per 100 milliliters.

Switfmud performed the initial tests and found four contaminated wells. The Health Department found fecal coliform in two additional wells, Gray said, and plans to test all residential wells within a quarter mile of the sinkhole.

All the residents have flushed their wells with chlorine and the wells will be retested periodically, Gray said. Though it seems obvious that the wells were polluted by the runoff, parker said, the proof will come from the results of tests over the next few weeks.

The large sinkholes, as well as all the smaller ones, have been filled to the specifications of the water management district, Hurley said. The voids were filled with tons of sand and gravel, she said, and sealed with clay.

Because no runoff has entered the sinkhole for several weeks, the levels of bacteria in the wells should begin to decline. If they do not, parker said, the contamination is almost certainly coming from another source.

Hurley said the Turnpike District of the state Department of Transportation knew the path of the road was riddled with potential sinkholes and worked hard to avoid them. Tapping into the expertise of the federal Natural Resources Conservation Service, workers used soil boring, ground penetrating radar and other techniques to locate sinkhole -prone areas.

The path of the parkway was altered to avoid one such spot, she said, as was the location of one retention pond.

Hrivnak, though, said more could be done. He rinsed chicken he was preparing to bake from water he had drawn from the nearby tank and stored in old 2-liter soda bottles.

He pointed out it was the county that had provided residents with drinking water. No one from DOT has come to the neighbors' homes or telephoned them, he said.

"They destroy your well and they don't do nothing," he said. "It seems like someone from there could come out and see what they could do to make it right."