The Ina Road landfill as a source of ground-water pollution

Abstract

A monitoring program was established at the Ina Road landfill in Tucson, Arizona to evaluate the potential for ground-water pollution. Seven observation wells were installed as part of this study. Groundwater samples were collected monthly from July 1979 to February 1980. Mean concentrations of bicarbonate, chloride, and sulfate, and values of specific conductance were the most reliable indicators of contaminated ground water. Chemical maps of these constituents indicated a plume of contamination originating in that portion of the landfill adjacent to the Santa Cruz River and extending northward. The source of water for leachate generation was hypothesized as being major runoff events in the Santa Cruz River. The northerly direction of the plumes, instead of northwesterly along the regional gradient of groundwater flow, was attributed to flood waters of good quality percolating through the bottom of the abandoned sand and gravel pit west of the landfill.