In February 2010, the island of Trinidad was experiencing severe drought conditions, resulting in dangerous brush fires and limited access to fresh water. The Water & Sewerage Authority of Trinidad & Tobago (WASA) awarded Seven Seas Water a contract to deliver freshwater in the Southwestern region of the country on a fast-track basis. When the Republic experienced a change in Government in May 2010, the contract was amended resulting in a 10 year Build Own Operate agreement. Seven Seas Water was to construct the 5,500,000 gallons per day (MGD) (20,819m3/d) permanent facility to serve the community of Point Fortin and its neighbors to the South. This was the largest desalination project awarded in Trinidad in a decade and would supply shortfalls in an area where some were only receiving water one or two days per week.
The Seven Seas Water plant is located within the Petrotrin Refinery Marine Terminal Facility. The tight 1.2 acre site presented unique challenges that required supplemental site work and additional permitting before construction could begin. Additionally, construction was interrupted after the discovery of an oil well located on the site, which took 8 months to cap.
In May 2012, Seven Seas Water was finally in a position to deliver on their guarantee of bringing water to the people by starting construction, but not without facing additional unexpected adversity. The existing piping could not be utilized as planned and new lines which crossed active roadways had to be installed. The offshore marine work consisting of a 500 meter intake line and 1000 meter outfall was affected by unfavorable sea and weather conditions, and the new infrastructure for the pump house had to be constructed. The final permitting was not obtained until May 31, 2012, but construction was completed in a short 14 months.
The feed water from the Gulf of Paria is particularly challenging when it comes to seawater reverse osmosis. The salinity range fluctuates from 10,000 mg/l TDS to 35,000 mg/l TDS and conditions of the feed water is also impacted by seasonal weather patterns and the influence of silt outflows from the Orinoco River. Seven Seas Water solved these pretreatment challenges by adding flocculation tanks and clarifiers before media and cartridge filtration. A waste solids handling system allows Seven Seas Water to collect and send the solid matter to a landfill, while the clear filtrate is returned to the sea. The cleaned feed water is then pressurized and sent to the six containerized reverse osmosis (RO) units and four 1 MGD (3,875m3/d) skid-mounted RO units to remove the salt. To maximize on energy efficiency an isobaric pressure exchanger is engineered into the design. The system is recovering 43% of the feed water and delivering a fresh supply with a quality of <500 mg/l TDS.
EXPANDING TO MEET DEMANDS
In 2015, the island of Trinidad continued to be faced with drought-like conditions and the cycle of brush fires and lack of fresh water for the people continued. Seven Seas Water was asked to expand the SWRO facility at Point Fortin to supply an additional 1.2 MGD (4,542m3/d). After permitting was complete, Seven Seas Water installed the Company’s first quick deploy 1 MGD (3,875m3/d) skid, which was integrated into the existing system. With the lower than normal salinity of the seawater in Trinidad due to the Orinoco River pumping fresh water into the Gulf of Paria, Seven Seas Water can use the 1 MGD (3,875m3/d) quick deploy equipment to produce 1.2 MGD (4,542m3/d) with a specialty membrane. Construction was complete in 6 months and the plant went online in July, 2016. Currently, Seven Seas Water is delivering 6.7 MGD (25,379m3/d) to WASA for distribution in Southern Trinidad.
NO CAPITAL COSTS
With no up-front capital required from WASA, Seven Seas Water quickly deployed under a build-own-operate (BOO) arrangement, overcame many hurdles and remained steadfast in the commitment to the key objective to deliver fresh water. Seven Seas will manage and operate the facility, guaranteeing a reliable water source at a fixed cost per gallon over the entire term of the agreement.
The material contained in this case study is provided for informational purposes only. The information contained is accurate only as of the date the case study was issued. Seven Seas Water disavows any obligation to update information contained in this case study after the date of issuance.