Tampa Bay Water Identifies Cause of Cracking of Erosion Control Layer, Announces Future Plans for Regional Reservoir

CLEARWATER (June 5, 2009) - After a thorough analysis by consulting engineers, Tampa Bay Water stated today the cause of the soil-cement cracking at the C.W. Bill Young Regional Reservoir is attributed to high water pressures underneath the erosion control liner on the interior of the reservoir. The utility also announced a detailed plan for procuring a long-term fix.

The reservoir’s erosion control layer consists of soil-cement that lines the reservoir’s interior and a soil wedge that lies between the soil-cement layer and a deeper geomembrane that protects the rest of the embankment. Tampa Bay Water’s system engineer reports that water becomes trapped in the soil wedge causing high water pressure which leads to soil-cement cracking, soil wedge movement and soil erosion (See Attached Fact Sheet and Diagram).

Inspection and analysis continue to conclude the reservoir is safe, according to Gerald Seeber, general manager of Tampa Bay Water.

Short-term patching of the cracks has allowed the reservoir to remain in limited use. However, without a long-term fix, the cracking will continue and will interfere with reliable use of the reservoir in the future.

“Tampa Bay Water’s system was built on a working 15.5 billion gallon reservoir for storage, and without it our surface water system becomes vulnerable to surface water shortages,” said Seeber. “The facility is an essential component to the region’s diverse water supply and requires a long-term fix.”

The agency also announced a detailed procurement process to solicit competitive solutions and proposals for the fix.

“In order to select the best solution for the best value, Tampa Bay Water will have a competitive design and construction process that will include an independent, expert peer review group as part of the process,” said Seeber. “Improving our procurement process will help protect the public’s investment in their drinking water supply.”

The process for fixing the interior of the reservoir is expected to take several years.

“We want to make sure the agency’s focus is on getting it right,” said Seeber. “Quality and results, rather than schedule, will govern the fix.”

Tampa Bay Water’s system engineer has identified three basic approaches to fixing the problem. These include:

1. Adding drains to the soil wedge.
2. Removing the soil wedge and replacing it with a well-drained layer.
3. Adding weight to the soil-cement erosion control layer to prevent further movement.
   

The topic will be discussed at the Tampa Bay Water board meeting on June 15, 2009.

Tampa Bay Water provides wholesale water to the public utility systems of Hillsborough, Pasco and Pinellas counties as well as the cities of New Port Richey, St. Petersburg and Tampa.

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