AquaResource Completes Hydraulic Impact Assessment on Hawaiian Coast

AquaResource has applied the state of the art groundwater modeling software, FEFLOW, to assess the hydraulic impacts of wastewater injection off the coast of Hawaii. As part of an assessment of water management initiatives at the Oceanographic Institute / Sea Life Park, Oahu, Hawaii, a numerical modeling assessment of hydraulic impacts on local pumping and injection wells was completed.  Wastewater generated from these facilities is injected deep into underlying lava flows, while shallower wells provide the water supply for operations; both pumped and injected waters are saline.  This project was designed to quantify the area impacted by subsurface wastewater discharge and the volume of wastewater re-circulated by nearby supply wells.

A numerical model of the site was developed using the state of the art software, FEFLOW. The model developed consisted of a more than 100,000 elements, encompassing 24 billion cubic feet.  The model was calibrated to aquifer response testing and injectate re-circulation observations.  The model was then applied to predict the impact of proposed operational changes.  Quantification of impacts was accomplished by simulating groundwater flow and contaminant transport extending from the injection wells.  Advective flow paths and percentage of injected mass volumes captured by pumping wells were used to quantify the degree of wastewater re-circulation through the extraction wells.  Contaminant transport simulations were used to delineate the areas where wastewater discharges to the Pacific Ocean floor.  The modeling results provided the client with a more detailed understanding of the areas impacted by injected wastewater and facilitated further management initiatives.