Providing a reliable water source to an island nation with few freshwater resources is a daunting task, but one the Water Authority of the Cayman Islands has successfully undertaken for the past 31 years. Piped water is currently available to nearly all residents on the main island of Grand Cayman. After decades of building up the infrastructure, the public agency now provides piped water to around 40,000 residents on Grand Cayman and is in the early stages of expanding the water system on the smaller sister island of Cayman Brac. Cayman Water Company, a private company, provides water to West Bay Road, where most hotels are situated, and the district of West Bay.
The water authority was created in 1983 and began constructing its water production and pipeline distribution, and wastewater infrastructure two years later. Most of the British territory’s water supply is produced at seawater reverse osmosis facilities. On Grand Cayman, the agency has four water production facilities with a combined capacity of 23,000 cubic meters per day and a wastewater treatment plant that handles 9,500 cubic meters each day.
While Grand Cayman enjoys a built-out pipe system, the water authority has limited presence on the island of Cayman Brac, where a small water distribution system on the western end provides piped water to the residents and visitors in this area. The remainder of the population of Cayman Brac, comprising approximately 2,000 permanent residents and hundreds of visitors, is served through a trucked water delivery service. Five water trucks supply about 50 percent of the total water demand in Cayman Brac.
The next step for the water authority is expanding the piped water service to the rest of Cayman Brac, a project that started in November 2013. The agency is using one in-house crew to expand the water infrastructure across the island, a process Deputy Director Tom van Zanten expects will take more than 15 years and will cost around $35 million. If the government’s financial situation improves, additional funding would allow the water authority to add resources and increase the rate of pipeline installation, thus completing the project faster.
Cayman Brac’s existing water production plant was built in 1991 and produces about 560 cubic meters per day but is located on a site that is subject to flooding and is thus vulnerable during hurricane events. A key component of the infrastructure expansion is the planned construction within the next five years of a new water production facility located on the Bluff, a limestone plateau, at a higher elevation to ensure its reliable long-term operation and improve security of the island’s water supply. As an interim measure to meet growing water demand, the water authority has recently added a containerized reverse osmosis plant to its operation, increasing the water production capacity by 230 cubic meters per day.
Once the new water production facility on the Bluff is fully operational, van Zanten says this containerized reverse osmosis plant will be relocated to Little Cayman where it will supply the smaller island with much needed potable water, which will then be available via tanker truck to the approximately 200 permanent residents, and visitors.
Public-private partnerships have helped the water authority expand its service while meeting growing demand. The agency uses a build/own/operate/transfer model to develop the water production plants. While the water authority owns the facilities, partner companies design, build and operate the plants for a period of time, typically between seven and 10 years, depending on the contract, with the possibility of this period being extended. During that time, the water authority pays the partner to operate and maintain the facility with a separate fee for the amount of water produced, allowing the agency to keep its focus on water distribution instead of production.
The investment in water and wastewater infrastructure ties into the government’s economic recovery efforts. During the global recession of the late-2000s, the Cayman Islands suffered from a downturn in tourism. But the number of visitors to the Caribbean hot spot has since rebounded, and van Zanten says the Cayman Island must increase its water production and storage, as well as its wastewater collection and treatment capacities in anticipation of future growth. Building out the pipe network on Cayman Brac is a key part of the water authority’s multi-year capital investment plan.
Eyes On Efficiency
While the infrastructure expands, the water authority is looking for ways to make distribution more efficient to keep costs in line. Seawater reverse osmosis has proven to be a capable desalination technique to meet the Cayman Islands’ water needs, but the process uses a lot of energy. Improvements in membrane and energy recovery technologies have reduced those energy costs during the past 30 years, but van Zanten says the agency continues to refine the operation. “We constantly are looking at ways of improving the energy efficiency of the plants and their reliability.”
A new water distribution pump station will be installed on Grand Cayman later this year. All new pumping stations will be equipped with variable frequency drives that adjust the speed of the pump motor to fit the water demand at any given time, rather than using pump regulating valves which are less energy efficient. The additional investment required to switch to the variable frequency drives is returned within less than two years through the energy savings, van Zanten explains.
Improvements are being made on the customer’s end, as well. Older water meters are being replaced to ensure that all water used by the customer is properly registered.
The water authority has more than 17,000 water meters that are read on a monthly basis – a time consuming process. The agency is currently investigating upgrading its system to Advanced Metering Infrastructure (AMI) using smart meters. These wireless water meters send data on water use from each customer to a central location.
The expansion and efficiency improvement efforts ultimately tie back to the water authority’s mission to supply the best water at an affordable price to residents and businesses. While the Cayman Islands faces many challenges in providing that important resource, van Zanten says the authority remains up to the task. “Customers in general are very happy with the service we provide,” he notes.