- Kiewit Infrastructure South
- Tampa, Florida
- Our Role
- Geotechnical, Hydraulics, Mechanical, Structural, Instrumentation, Permitting, Risk Assessment, Construction Quality Control, Compliance.
- 15.5 billion gallons
- Construction Cost:
- $129 million
- Long-term solution for armoring upstream embankment slope
- Reduced operation and maintenance efforts
- Region’s water supply more drought-resistant, reliable, and flexible.
Located east of Florida’s Tampa Bay area, the 15.5 billion gallons C.W. Bill Young Regional Reservoir is a critical resource for its owner Tampa Bay Water and the more than 2.4 million customers it serves. Helping ensure the region’s drought resistance and minimizing reliance on depleting groundwater sources, surface water from the Tampa Bypass Canal and the Hillsborough and Alafia rivers is stored in the reservoir during wet times. During dry times, when surface water is unavailable, water stored in the reservoir is withdrawn and treated to serve the region.
Tampa Bay Water placed the reservoir into service in 2005, but shortly after, cracks were discovered in the soil-cement erosion protection layer on the upstream slope. Over time, the cracks became more extensive, resulting in increased operation and maintenance efforts and operational restrictions. Tampa Bay Water ultimately took the reservoir off line in 2012. A two-year long renovation initiative, with a scope that included design and construction, addressed all of the active and credible failure modes of the reservoir. As a result, the reservoir was restored to its optimum working condition and placed back into operation in 2014.
Gannett Fleming designed a renovation solution that would require minimal maintenance and low long-term repair or replacement costs. Our design called for demolition of the existing upstream armoring system, excavation of the underlying soil wedge, removal of the existing geomembrane, the addition of a PVC geocomposite, a gravel drain, and construction of stair-step soil-cement armoring on the upstream slope.
A significant geotechnical project, Gannett Fleming conducted extensive subsurface investigations and laboratory testing, seepage and stability analyses, preparation of plans and specifications, and construction monitoring. We also provided hydraulic analyses in support of an Emergency Action Plan update and designs for mechanical upgrades to the existing inlet and outlet tower, structural upgrades to the tower, modifications to the tower access bridge, and design of a replacement hypolimnetic and destratification system to maintain reservoir water quality. During construction, Gannett Fleming provided quality control and permit compliance services and in the five years following construction, is providing maintenance and monitoring services at the reservoir.
- New geomembrane
- Gravel drain
- Stair-step soil-cement over entire length of upstream slope
- Soil-cement toe buttress.
- Existing materials incorporated into the new design as embankment
- Existing HDPE geomembrane recycled.