WATER SUPPLY/New plant reduces reliance on groundwater

Tampa Bay (Fla.) Water has opened a 66-million-gallons-per-day (mgd) surface water treatment plant in central Hillsborough County. The $84 million project, which is Tampa Bay Water’s first surface water plant, reduces the water authority’s reliance on groundwater by drawing drinking water from the Tampa Bypass Canal, and the Hillsborough and Alafia rivers.

Tampa Bay Water is the largest wholesale water supplier in Florida, serving nearly two million customers. It works collectively with its member governments of Hillsborough, Pasco and Pinellas counties and the cities of Tampa, St. Petersburg and New Port Richey. Tampa Bay Water sells treated water to its member governments, which, in turn, resell it directly or indirectly to other smaller utilities.

By the late 1990s, population growth in the Tampa Bay region had stressed the 11 regional groundwater wellfields that were the primary source of drinking water, creating the need for new water sources. Tampa Bay Water began formulating a Master Water Plan to reduce the water authority’s dependence on the wellfields. In 1998, the water authority approved the construction of the surface water plant; an adjacent 6-mgd groundwater treatment plant that is now operational; a 15-billion-gallon reservoir, slated for completion in 2004; and a 25-mgd seawater desalination facility in Apollo Beach that is expected to be running at full capacity by April.

In 2001, the water authority approved the final design and permitting of the plan’s second phase, which includes the construction of another 25-mgd seawater desalination plant and a 5-mgd brackish water desalination plant. Those projects could begin operations in 2008. In all, the Master Water Plan calls for the water authority to reduce groundwater use from the 11 regional wellfields by 68 mgd by 2008 and to generate 91 mgd of new water supply by the same year.

In 2000, Tampa Bay Water contracted with Houston-based USFilter Operating Services to design, build and operate the surface water treatment plant, which was completed in October. In the first phase of treatment, silica sand is added to the water to remove color and particles. Impurities in the water attach themselves to the sand and then collect at the bottom of the plant’s settling tanks. In the next stage, ozone is used to disinfect the water, and, in the final phase, dual-media filtration removes remaining particles.

After leaving the surface water plant, the water moves to a blending facility, where it is merged with treated water from the adjacent groundwater plant. (When the desalination plant in Apollo Beach is completed, treated water from the plant also will be blended with water from the surface water and groundwater plants.) Then, the combined water is piped to the member governments of Tampa Bay Water.

For the water produced at the surface plant, Tampa Bay Water has set standards that exceed the current EPA Safe Drinking Water Act requirements for potable water. Furthermore, the water authority has set an incentive-based performance plan that pays a fee to the plant operator when it meets specified performance measures.