PROJECT SUMMARY
The Tampa Bay region of Florida, which is located within the Southwest Florida Water Management District, has traditionally acquired its drinking water supply from groundwater pumped from nearby aquifers. In the 1990s, population growth began to outpace current drinking water supplies and the development of new ones. As drought further aggravated the shortage, Tampa Bay Water, the wholesale water developer and supplier that serves the Greater Tampa Bay region, began to look for an alternative to groundwater. Tampa Bay Water’s members include the Counties of Hillsborough, Pasco and Pinellas and the Cities of New Port Richey, St. Petersburg and Tampa.

Tampa Bay Water commissioned the construction of a seawater desalination plant in 1998 for $110 million. Due to unforeseen bankruptcies of the contracted development and construction firms and inefficiencies of the filtering process, Tampa Bay Water re-acquired the facility and contracted with American Water-Pridesa in 2005 for a complete overhaul and management of the treatment facility. The facility is responsible for the supply for 25 million gallons of water per day (mgd). The 2008 daily average totaled 15 mgd.

Co-located with an existing coal-fired power plant, the Tampa Bay Seawater Desalination Plant began producing high-quality drinking water in January 2008. To produce the required 25 mgd, the plant reuses 44 mgd of the nearby power plant’s cooling system. From those 44 mgd, 25 mgd of drinking water is created and distributed throughout the region. The remaining 19 mgd of concentrated seawater is diluted with the cooling system’s remaining 1.356 billion gallons per day and deposited into the Tampa Bay. This innovative system has decreased the costs typically associated with desalination because it reuses already warmed water, from which it is easier to extract salt.

The plant maintains a 70:1 dilution ratio, which has not adversely affected the bay’s salinity and is within federal salinity standards. This new water source, serving 2.5 million people, now supplies ten percent of the region’s drinking water.

PROJECT OBJECTIVES
Tampa Bay Water sought to decrease groundwater pumping, protect the environment from undue stress and meet the needs of a growing community. In order to deliver drinking water to its customers effectively, Tampa Bay Water embarked on the construction of the largest desalination plant in the United States.

PROJECT DESCRIPTION
Partners
The public sector partner for the plant is Tampa Bay Water, a utility agency that supplies water to the Counties of Hillsborough, Pasco and Pinellas as well as the Cities of New Port Richey, St. Petersburg and Tampa. With nearly 2.5 million people living in the region, it is necessary to supply approximately 25 mgd to the area.

The private sector partner is American Water-Pridesa, a joint venture subsidy of American Water and Acciona Agua. American Water-Pridesa took over the existing desalination plant in 2005, and after three years of repairs and improvements, the plant re-opened in January 2008.

Implementation Environment—Legislative and Administrative
Florida state statute allows public entities to contract with private entities for the provision of services “when such services can be provided in a more efficient manner by private entities” (Florida Statutes, title XXXIII, ch. 489 § 146, [2008]).

Financial Agreement
The initial project cost totaled $110 million, but remediation of the plant cost an additional $48 million, bringing the total project cost to $158 million. The Southwest Florida Water Management District will contribute $85 million to the project over the first 18 months of operation. This financial partnership earmarks locally collected ad valorem taxes for water supply creation.

American Water-Pridesa entered into a contract for remediation, construction and operation with Tampa Bay Water in 2004 for $29.1 million. The contract also included an owner’s allowance of $2.5 million. During the contract length, American Water-Pridesa took over full-operation of the plant. In December 2007, Tampa Bay Water accepted the plant, taking over full ownership duties, per the agreement. American Water-Pridesa no longer operates the plant.

Tampa Bay Water charges its member governments $2.2451 per 1000 gallons (plus a variable rate for electrical and chemical costs). This cost is revenue neutral and only covers expenses, including debt service payments. Members may determine the per gallon price to charge their customers.

Contract Provisions
 Because of significant inefficiencies of the already built plant, American Water-Pridesa’s main objective was to remediate the site as efficiently as possible to meet the goals of the contract. Upon completion of the facility, the plant needed to produce 25 mgd; the plant now has the capacity to process approximately 28.75 mgd and, with minor improvements, increase the amount to 35 mgd. Originally scheduled to open in 2006, the plant remediation concluded in 2007 and operation began in early 2008.

Implementation Metrics
To produce 25 mgd, American Water-Pridesa uses a three-step system of pre-treatment, desalination and post-treatment combination. Seawater is sent through a multi-step screening, filtering and settling process. This pre-treated water is then desalinated by a process called reverse osmosis, which uses high pressure to trap salt and minerals in semi-permeable membranes. The purified water is then treated with additional minerals and combined with other water at the Tampa Bay Water facilities.

Commentary
The inefficiencies in this project extended the completion timeline from 2002-2003 until early 2008. The development firm selected in the initial Request for Proposals process declared bankruptcy in 2000; the construction firm failed to obtain the necessary private financing. When financing had not been obtained by 2002, Tampa Bay Water bought the facility from the project’s second developer. Shortly after the facility failed two weeks’ worth of performance tests, the construction firm filed for bankruptcy.

Though the process to build and operate a desalination plant was long and difficult, Tampa Bay Water did not terminate the project, which in the long-term has benefited 2.5 million people. The Tampa Bay Seawater Desalination Plant now supplies the region with ten percent of its drinking water.