Geohydrology and ground-water quality at the Pueblo Depot activity landfill near Pueblo, Colorado

Abstract

The landfill at the Pueblo Depot Activity, a U.S. Department of the Army installation in southeastern Colorado, overlies a shallow unconfined aquifer. The Pueblo County Commissioners have required that an investigation of the geology and groundwater quality be done and that a long-terra monitor-well network be established before a certificate of designation for the landfill can be issued. Nine monitor wells and four piezometers were installed at the landfill during October 1988. The geologic data collected during drilling was used to define the geology of the shallow unconfined aquifer. The unconfined aquifer consists of upland alluvial terrace deposits of moderate permeability that are underlain by about 1,200 feet of almost impermeable shale. Saturated thickness of the aquifer at the landfill generally is between 5 and 10 feet. Ground water discharged at seeps at the edge of the terrace deposits may recharge the alluvial aquifer underlying the nearby Arkansas River valley.