Consideration Factors of Production-Well Rehabilitation Assessment on Guam

Wednesday, December 5, 2018: 3:00 p.m.
Exhibit Hall- C4 & C5 (Las Vegas Convention Center)
Yong Sang Kim, PhD , Water & Environmental Research Institute of the Western Pacific, University of Guam, Mangilao, Guam
John Jenson, PhD , Water & Environmental Research Institute of the Western Pacific, University of Guam, Mangilao, Guam
Nathan Habana, PhD , Water & Environmental Research Institute of the Western Pacific, University of Guam, Mangilao, Guam

Currently, Guam Waterworks Authority (GWA) produces 90% of the 45 MGD potable water from its main source, the Northern Guam Lens Aquifer (NGLA). GWA is currently managing 100 to 120 deep vertical production wells in this aquifer to meet the demand. However, many of these production wells are deteriorating from age with more than 50 years in operation, thus lifespan exceeded, maintenance is no longer economically viable, and production has become unsustainable. The NGLA is a composite to complex karst aquifer with a thick vadose zone, forming an uplifted plateau (> 60 m), and a highly anisotropic and permeable porous media. This aquifer bears a meteoric recharged freshwater lens atop saltwater, divided by a volcanic basement of 7 aquifer basins that form basal and parabasal zones with varying lens thickness in different regions. On Guam, rehabilitation of abandoned production well sites is a promising way of keeping freshwater production without further developing new well sites. However, some of rehabilitated production wells drilled adjacent to the old wells have resulted in severe reduction of water production. To investigate this issue, case study wells were chosen, and their construction, operation and rehabilitation history were analyzed. Based on the analysis, main consideration factors of production-well rehabilitation assessment were categorized.
Yong Sang Kim, PhD, Water & Environmental Research Institute of the Western Pacific, University of Guam, Mangilao, Guam
Dr. Kim’s research interests include all aspects of sustainable water resource management relevant to groundwater depletion, contamination and interaction with sea/surface water. Recent work on Guam includes management of monitoring well database and the Guam Hydrologic Survey website (www.guamhydrologicsurvey.com). In addition, researches on production-recovery characteristics of Northern Guam Lens Aquifer (NGLA) to supply sustainable drinking water on Guam communities are being established.


John Jenson, PhD, Water & Environmental Research Institute of the Western Pacific, University of Guam, Mangilao, Guam
Dr Jenson is Professor of Groundwater Hydrology, and Director of the University of Guam's Water & Environmental Research Institute of the Western Pacific (WERI). His current research interests include development of the Carbonate Island Karst Model and its application to numerical modeling and sustainable management of island karst aquifers.



Nathan Habana, PhD, Water & Environmental Research Institute of the Western Pacific, University of Guam, Mangilao, Guam
Dr Habana is Assistant Professor of Groundwater Hydrology at the University of Guam's Water & Environmental Research Institute of the Western Pacific (WERI). His duties at WERI include serving as Coordinator for the Guam Hydrologic Survey Program, which compiles and analyzes basic data on Guam’s freshwater resources. His current research interests include modeling of vadose and phreatic transport, and the management of salinity and nitrate contamination in island aquifers.