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A Sinking Feeling

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By JULIA FERRANTE, The Tampa Tribune

Published: November 6, 2007

LAND O' LAKES - Ground-penetrating radar showed that a reclaimed water reservoir under construction at Pines Parkway is prone to sinkholes, but it appears the problems run deeper than expected.

Workers have been pumping grout into the base and embankment of the reservoir for several months in the hope of plugging potential holes, but there appears to be no end in sight to the work, said Bruce Kennedy, Pasco's assistant county administrator for utilities.

Officials have shut down the operation in the hope of coming up with a less costly solution.

"We only had so much money in the construction contract for that," Kennedy said. "We needed to stop."

Kennedy is expected to give a report to the county commission today with possible solutions.

Pasco County Utilities has dumped excess reclaimed water - used to irrigate lawns, golf courses and parks - at the reservoir site for years in what is known as a rapid infiltration basin.

As part of a consent order signed last year with the state Department of Environmental Protection, however, county officials agreed to build the Land O' Lakes reservoir to store reclaimed water, which is in high demand as Pasco continues to grow.

As part of construction of the 100 million-gallon reservoir, analysts conducted tests to identify caverns and weakness in the embankment and base. They found the potential for sinkholes and determined the reservoir, which would store water during the rainy season, needed to be grouted to prevent the walls from collapsing and flooding neighborhoods.

The price tag for the project has grown several times, from $4 million at its inception to $18 million, partly because of material cost increases and other unanticipated expenses.

County leaders have turned to a consultant to find another way of avoiding sinkholes so they may finish the project, Kennedy said. One option may be to realign the embankment so it is away from sinkhole-prone areas, but going that route may be too expensive, Kennedy said. Resuming the grouting work also will come at a cost. County officials will have to pay their contractor $40,000 to "remobilize."

"We probably will have to continue to grout," he said. "We just could not continue the way we were going."

Part of the problem is that much of sinkhole prevention and repairs is guesswork, Kennedy said. "You can't see down there. You can't see how extensive the area is," he said. "We have several different geotechnical techniques to properly assess that, but it doesn't make it foolproof."

Kennedy compared the process to taking an X-ray to diagnose a disease and then finding additional problems during surgery.

A similar reclaimed water reservoir is planned near Boyette and Overpass roads in Wesley Chapel. At least one other site is under consideration, at Handcart Road, Kennedy has said. About $21 million is budgeted for the Boyette reservoir project. County officials have gone the reservoir route because, unlike neighboring counties, they do not have permits to discharge reclaimed water into Tampa Bay, rivers and deep underground.

The Southwest Florida Water Management District has committed $1.9 million to the project, but county officials may ask the agency to increase the allocation.

Pasco Utilities has about 10,000 residential reclaimed water customers, mostly in central Pasco. Officials have turned down requests from several neighborhoods because they can not meet the demands. The county utility also services golf courses, schools and parks. Reservoirs must be built near the neighborhoods or businesses they serve and where transmission lines are available.

The use of reclaimed water for irrigation can significantly reduce use of potable water, but it is costly to the utility, Kennedy has said. The utilities department pays for system improvements and other costs with fees collected from customers and revenue from construction impact fees. A rate increase is not expected.

Reporter Julia Ferrante can be reached at (813) 948-4220 or jferrante@tampatrib.com.

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