Reservoir being filled; Tampa Bay Water has determined cause of cracks
Cracks that developed more than two years ago in the state’s largest reservoir are caused by high water pressure under an erosion-control liner, Tampa Bay Water announced yesterday. The cracks in that soil-cement layer lining the interior of the C. W. Bill Young Regional Reservoir in southeast Hillsborough County have been temporarily patched and now water is being pumped in.
The area’s recent heavy rains mean that flows in the Alafia River and the Tampa Bypass Canal are high enough for water to be pumped from those surface-water sources into the reservoir. The 15.5-billion-gallon-capacity reservoir -- which was essentially empty about a month ago – now contains about 1.6 billion gallons.
Standing on top of the reservoir’s embankment Friday morning, Gerald Seeber -- the general manager of Tampa Bay Water -- points out the grayish grout that has been used for temporary repair.
“The grouting has been applied to preserve the erosion control features of that flat-plate soil-cement. It’s designed to prevent any erosion from affecting the embankment that holds the water in the reservoir. The reservoir is safe. The geomembrane facility that provides the water stop in the embankment has not been compromised – that’s in excellent condition and the reservoir doesn’t leak. We just have a problem with the erosion control on the inside of the reservoir.”
It will take several years, Seeber says, for Tampa Bay Water to undertake a full-scale permanent repair of the cracked soil-cement layer; the grout is only a temporary fix for the cracks in the reservoir.
“Those cracks appear whenever you take water out of the reservoir. We don’t expect any problem with the reservoir as we fill it. But next spring, in 2010, as we draw water down, we expect to see some cracking to occur once again. And we will again return and perform the maintenance on the erosion-control feature to keep it in good condition. That’s not a long term answer, that’s not a permanent answer to the problems that we face here.”
An alligator swims in the reservoir as a great blue heron and other wading birds congregate along the shore littered with the shells of freshwater mussels and clams. A single osprey soars above the reservoir’s 5-mile circumference. Seeber says that after a thorough analysis by consulting engineers, Tampa Bay water has determined the cause of the cracks, and a long-term solution.
“The water that saturates the soil just underneath that erosion-control layer is built up – the pressure that’s causing the cracking. We have to undertake a project to drain that water or to eliminate that water in the soil wedge underneath the erosion control flat-plate. That work will take about two years to complete once the construction is underway. We don’t anticipate that construction getting underway, though, for about another three years because we have a lot of work to do to ensure that we get best value and best solution for the permanent repair that’s undertaken.”
The reservoir will be closed during the two years the repair will take, potentially leading to severe regional water availability issues. Tampa Bay Water provides wholesale water to the public utilities in Hillsborough, Pinellas, and Pasco counties. Seeber says they will seek input about a permanent repair plan from experts on a peer review panel.
“We don’t have a real good estimate yet what the costs would be. … We have given an estimate to our [board] of $125 million.”
Additional costs to ratepayers could be offset by the amount that Tampa Bay Water can recover through litigation. Their board voted last October to sue the companies that designed, constructed, and provided quality control over the construction of the reservoir. HDR Engineering designed the reservoir; it was constructed by Barnard Construction Co.; and construction quality assurance was overseen by Construction Dynamics Group. Richard Harrison, with the law firm of Allen Dell in Tampa, is representing Tampa Bay Water against the three companies they believe are at fault for the excess water pressure in the soil layer that is causing the cracks.
“The only people that can be responsible for it are the people who designed it, built it, and oversaw the project. We do believe fundamentally it is a design error. We continue to investigate the effect of any construction problems as well. … The damages in a general sense are going to be whatever it costs to fix it.”
Harrison says the court has given Tampa Bay Water a trial date of two years from now: July 2011.
“All those parties have certain responsibilities that are recognized within the law. If you make a mistake on a grand scale, you’re generally responsible for a lot of money.”
The reservoir opened in 2005. Its water level is measured as feet above sea level. Tampa Bay Water’s Gerald Seeber says the level on Friday morning was 86 and the reservoir is considered full at 135. If the level reaches 100 -- which may occur in July -- local water use restrictions could be eased slightly, according to Seeber. But he still urges conservation.
The Tampa Bay Water board will discuss fixes to the cracking problem at their upcoming board meeting on June 15 in Clearwater.comments powered by Disqus