Early in 2009, the Virgin Islands Water and Power Authority (WAPA) was experiencing challenges meeting the water demands on the island of St. Croix because of interruptions in supply caused by older desalination equipment that required significant refurbishment. As part of a plan to repair its existing thermal equipment, WAPA sought the supply of a temporary source of 500,000 gallons per day (GPD) (1,892 m3/d) of potable water for St. Croix. The short term supply was necessary to mitigate continued water shortages during the planned rehabilitation of the existing facility.
Seven Seas Water proposed a solution which utilized mobile seawater reverse osmosis (SWRO) units, that would not only satisfy the immediate needs in the shortest time possible but provided sufficient additional benefits to warrant pursuing a longer term water supply solution that would allow WAPA to refurbish additional thermal units.
NO CAPITAL COSTS
With no up-front capital required from WAPA, Seven Seas Water quickly deployed the mobile SWRO units under a build-own-operate (BOO) arrangement. SSW would also manage and operate the water facility, guaranteeing a reliable water source at a fixed cost per gallon over the entire term of the agreement.
When WAPA concluded that the Seven Seas Water SWRO proposal, utilizing membrane technology, could produce guaranteed quantities of water at a measurably lower cost than estimated, without the risks or the responsibilities of operating their own equipment, Seven Seas Water was asked to expand the scope of supply from 500,000 GPD (1,892 m3/d) to 1,500,000 GPD (5,677m3/d).
Within a record-breaking 92 days from the date the agreement was signed, six (6) sets of mobile seawater reverse osmosis units were shipped to the site, installed and producing 1,500,000 MGD (5,677m3/d) of potable water.
The Seven Seas Water plant was designed with installed redundancy to maximize on-line time and is producing potable water (permeate) with a salinity of less than 300 ppm TDS from 35,000 ppm TDS feedwater. The plant design is the most energy efficient commercially available with an energy consumption of the RO portion of the plant under 10 kWhr/kgal, about half the energy consumption of most containerized RO units. This ultra efficient design provided a low cost, temporary supply of water to WAPA and the people of St. Croix as well as operating in an environmentally sustainable manner, promoting good stewardship of the precious resources in the USVI.
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.