Tampa Bay Water ditches plan for expansion of reservoir amid sinkhole concerns

Tampa Bay Water officials are ditching their plan to expand Florida's largest reservoir by 3 billion gallons, saving the ratepayers money, but once again stumbling on a major project.

Instead of spending $163 million to expand the reservoir, the utility will pay closer to $121 million to fix the repeated cracking problem in the existing 15.5 billion-gallon facility.

Utility officials gave two reasons: the weight and the winter.

State Department of Environmental Protection officials say they are worried about what they've seen of the honeycombed limestone geology beneath the reservoir. Although it is sturdy enough to support the current reservoir, state officials say, they fear the higher walls and extra water in an expansion would be too much weight.

What has them particularly worried about the reservoir in rural Hillsborough County is what happens when a winter freeze hits, such as the ones that occurred last year and in 2010. During those freezes the farmers pumped so much water out of the ground to protect their crops that the aquifer suffered a dramatic drop.

During the January 2010 freeze, dozens of new sinkholes opened around Dover and Plant City. In December 2010, a sinkhole 75 feet wide and 45 feet deep opened in Hillsborough County's Southeast County Landfill, about 20 miles from where the winter pumping was going on.

That landfill sinkhole "changed the game," Tampa Bay Water general manager Gerald Seeber said Thursday. It made DEP officials much more leery about the movement of water through the limestone in that area.

In an April 13 letter, DEP officials told Tampa Bay Water they're worried that with the extra weight on an expanded reservoir, pumping by neighboring farmers during a freeze could lead to a sinkhole.

DEP officials said they were not denying the permit for the expansion yet, but they were leaning that way because "the additional loading posed by a larger reservoir is not a good idea at this location."

Tampa Bay Water's own geology experts had no such qualms. But rather than fight the DEP over a potential permit denial, Seeber told board members in an April 30 memo that he intended to ditch the expansion and instead ask DEP for a permit for just the repair by Kiewit Construction.

Seeber wrote in the memo that he couldn't wait to get permission from the board at its June 18 meeting because "time is of the essence in this project, we are draining the reservoir for construction work planned for later this year, and delays in the construction schedule can run $90,000-100,000 per week."

He said in an interview Thursday that he could not estimate how much ending the expansion will save ratepayers, but it does cut the cost of the project by an estimated $40 million.

Seeber's decision won't get an argument from at least one board member. St. Petersburg City Council member Karl Nurse contended this week that the drop in expected demand for water after Florida's real estate boom cooled off shows there's no need for additional water storage for another 10 to 15 years anyway.

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Nurse had opposed the expansion from the start, arguing last year that instead of raising the walls of the reservoir to hold more water, Tampa Bay Water should spend the extra $40 million promoting water conservation so people would use even less of it.

But at the time, the board agreed with Seeber that it would be cheaper to expand the reservoir while its cracks were being fixed, rather than wait another decade and have to spend an estimated $200 to $300 million to build a second reservoir.

The C.W. Bill Young Reservoir opened in 2005 to store water skimmed from the Alafia River, Hillsborough River and Tampa Bypass Canal. Its walls consist of an earthen embankment as wide as a football field at its base, averaging about 50 feet high. An impermeable membrane buried in the embankment prevents leaks.

The embankment's top layer, a mixture of soil and concrete to prevent erosion, is where cracks were discovered in 2006. Some cracks were up to 400 feet long and up to 15½ inches deep. Patches on the cracks didn't last.

The utility sued HDR Engineering for the way the reservoir was designed, hoping to recover at least $73 million. Instead, on April 11, a jury ruled for HDR. Tampa Bay Water is appealing.

During closing arguments, HDR attorney Wayne Mason predicted that if the utility lost it would drop the expansion, which he called unnecessary. Afterward, Seeber scoffed at Mason's prediction and said, "I believe our board will forge ahead with the work."

At the time he said that, Seeber said Thursday, "I had no clue — none of us did — that the DEP would take this tack" on the expansion.

"Isn't it curious that it happened within a couple of weeks of the verdict?" Mason asked. "Isn't it amazing?"

Times staff writer Michael Van Sickler contributed to this report. Craig Pittman can be reached at craig@tampabay.com.