Infiltration Control Landfill Cover Demonstration at Marine Corps Base, Hawaii

To demonstrate the effectiveness of alternative landfill caps, the Naval Facilities Engineering Service Center (NFESC) teamed with the Los Alamos National Laboratory and Colorado State University to investigate the performance of a variety of vegetative caps. Demonstration caps were installed at Marine Corps Base Hawaii (MCBH) Kaneohe Bay in 1994. The study used an innovative but simple concept to manipulate the fate of rain water falling on waste sites with moderate to high precipitation. The infiltration of water through the cap, or cover, was controlled by combining the powerful forces of evapotranspiration (ET) with engineered structures that limited infiltration of precipitation into the soil. This approach relied on diverting a sufficient amount of precipitation to control runoff so that any water that infiltrated into the soil was easily removed by ET. The study demonstrated two infiltration control (IC) designs, one involving a 20% enhancement of runoff and the other a 40% enhancement, with a conventional ET soil cover design to serve as a control (i.e., basis of comparison). This report summarizes all the data collected during the MCBH landfill cover demonstration project between 11/95-3/98. Water balance data from the study were also compared against corresponding data for a Resource Conservation and Recovery Act (RCRA) clay cap obtained from the EPA Hydrologic Evaluation of Landfill Performance (HELP), version 3.0b, water balance model. The results, based upon 28 months of field monitoring data, support the concept of using runoff enhancement to manage percolation of water through a landfill.