Nature and extent of ground-water-quality changes resulting from solid-waste disposal, Marion County, Indiana

Studies of seven landfills in the Indianapolis, Indiana, area indicate that in five of the landfills movement of ground water is from the deep aquifers into the uppermost aquifer. In the other two landfills, movement of ground water is from the shallow aquifers to the deeper aquifers, so that leachate is transported into the deeper aquifers. In all the landfills, the predominant direction of ground-water movement is lateral. Placing solid waste into the landfills has occasionally altered the local, but not the regional, flow patterns. Ground-water mounding at shallow depths beneath two of the landfills has caused flow toward the edges of the two fills. Leachate at these fills is moving downward and outward and has affected water quality at shallow depths. Pumping near two other landfills has reversed the direction of regional ground-water flow, allowing leachate to move toward the pumping wells. Leachate at the three remaining landfills is moving downgradient and is discharging into single streams adjacent to each landfill. (Woodard-USGS)