Desorption of tetrachloroethene (TeCE) or 1,2‐dibromo‐3‐chloropropane (DBCP) from aquifer sediment (0.19% organic carbon) was monitored following sorption for 6 or 30 d in 100 μM aqueous solutions. The compounds were desorbed by a previously developed purge technique in which a third phase of Tenax GC® polymeric adsorbent beads provided a sink for desorbed chemical, thereby simulating desorption to infinite dilution. Sorbed concentrations in the sediments were quantified by hot acetone extraction of sacrificed replicates. More than 95% of the initial sorbed compound was desorbed within the first 4 d, but a persistent fraction (8–15 μg/kg, 0.4 to 1%) remained associated with the sediments for at least 35 d. The desorption curves were little affected by the prepurge sorption time. The results may rationalize the unexpectedly high sediment‐associated concentrations of a similar compound (1,2‐dibromoethane) in a long‐contaminated aquifer.