The Lynden Pindling International Airport (LPIA) is located in the central part of New Providence Island and provides local and international air travel connections. LPIA is the busiest airport in The Bahamas and is undergoing an expansion. The airport expansion includes the addition of a new building that will handle passenger traffic traveling to and from destinations within The United States of America.
The most cost-effective way to cool the large buildings like those at LPIA in The Bahamas is through heat-exchange. This process basically takes large quantities of groundwater, which is at a constant temperature of 70-72 degrees Farenheit, and a heat exchanger is used to transfer the cooling capacity of the groundwater to the air that is then circulated through the building.
Wellspring Consultants, Inc. was subcontracted through Sentinel Drilling of The Bahamas, Ltd. to assist with the hydrogeological services for the LPIA project. Our services included assisting with the design and testing of groundwater wells for the heat exchange system. The wells include two production wells and two return wells. The groundwater production wells remove groundwater at a depth of 320 to 400 feet below land surface, and are each 12†in diameter.
Our services included determining if the groundwater withdrawals would have an adverse affect on the surficial freshwater lens, a valuable resource that the local government would like to preserve. The freshwater lens present in the subsurface on New Providence Island is aerially extensive and used locally as a water source tapped by private wells. The freshwater lens is recharged by the infiltration of rainwater, as rainfall at this location exceeds the local evapotranspiration. Generally, the geometry of the lens is such that it is thickest in the central part of the island, and thins toward the coast. The freshwater lens is between 20 and 50 feet thick in the area of the airport.
A large-scale pump test was performed to assist in determining if the new groundwater withdrawals at the airport would affect the freshwater lens. Water levels were monitored in the shallow and deep aquifers during the pump test. The information collected in the field was complied and analyzed, and it has been determined that there does not appear that an impact to the freshwater lens will occur through the use of the groundwater wells at the airport. The deep aquifer is very porous, and the groundwater wells installed at the site have a large capacity to produce groundwater. Additionally, the groundwater return wells installed at the property are designed to assist in eliminating impacts to the shallow freshwater lens. The return wells are open from 200 to 300 feet below land surface, and are located northeast of the production wells. The return wells provide discharge of the heat-exchange discharge water to the aquifer at a shallower depth than the production wells, helping to block affects to the shallow freshwater lens.
This project has been very exciting to work on. I’m very grateful to Sentinel Drilling and the Swaby’s for the opportunity to assist with this high-profile project. It is always a pleasure to work with the people of The Bahamas.
