We studied the aerobic degradation of acetate in a roadside soil to assess the reduction of O2 demand imposed by an alternative highway deicing agent on groundwater. Aseptic uniform sand samples adjacent to the capillary fringe of a state highway shoulder in southeastern Massachusetts were placed in sterile serum bottles at 5°C, forming a series of aerobic soil microcosms. The samples were dosed with a reagent-grade glacial acetic acid solution, then sampled at various time intervals and analyzed by ion chromatography in a laboratory determination of the microbial degradation kinetics. The aerobic reaction rates were slower than those observed in loamy sand near the ground surface in an earlier study. A steady state transport model for the alternative highway deicing agent calcium magnesium acetate [CMA; Ca0.3 Mg0.7(C2H3O2)2] was derived, including infiltration and degradation. Simulations were run using the observed microcosm kinetics for a range of assumed snowmelt rates. The resulting profiles suggest that microbial activity within the uniform sand near the capillary fringe has the potential to reduce O2 demand by CMA on groundwater for slow (<5×10−7 m/s) snowmelt rates at 5°C under aerobic conditions. More rapid infiltration passes more CMA to the underlying aquifer.