Armoring Tampa Bay Reservoir with soil cement

Abstract Only - Completed in early 2005, the C. W. Bill Young Regional Reservoir also know as Tampa Bay Regional Reservoir (TBRR) was built using 12 million yd 3 (9.2 million m3) of embankment materials and 365,000 yd 3 (279,000 m3) of soil-cement for upstream slope protection. Initial filling began soon after completion and when full, the reservoir holds 15 billion gallons (56.8 billion liters) in an area of 930 acres (376 hectares). This will provide enough water to sustain about 25 percent of the region's drinking water demand for more than 200 days of drought. HDR Engineering, Inc. designed the five-mile (8 km) long earthen embankment with a maximum height of 65 feet. To protect the upstream embankment of the reservoir against the erosive wave action generated from hurricane force winds, the engineer elected to armor the bank with soil-cement. Soil-cement proved to be the most cost effective solution due to the lack of locally available rip rap and the plentiful supply of sand for the soil-cement within the basin of the reservoir. Based on desired maximum height and to optimize the quantity and cost of the soil-cement slope protection design, two different methods of soil-cement placement were utilized. For the portion of the embankment where the soil-cement would be normally submerged, the soil-cement was constructed 16-in. (406 mm) thick parallel to the slope in a method referred to as "plating." Above this elevation to the crest the soil-cement was placed in 9-in. (225 mm) thick by 8 ft (2.5 m) wide horizontal lifts in stairstep fashion. The stairstep method requires more soil-cement but provides better protection for the more frequent and higher wave action expected. In addition, the stairstep method dissipates the wave action and reduces wave run-up. To provide extra protection against possible uplift from wave action, a water-cement slurry mixture was applied to bond consecutive lifts. Soil-cement was also used to construct crest and perimeter roads. This presentation will cover testing program implemented to ensure proper selection of soils that react normally with cement, soil-cement mix design, methods and means of construction, quality control during construction, and soil-cement cost.