Environmental Laboratory, involves a trichloroethene (TCE) residual source area in a deep, fractured basalt aquifer that has been undergoing enhanced bioremediation since January 1999.Complete dechlorination from TCE to ethene was documented within nine months of operation, and sodium lactate injections were shown to enhance TCE mass transfer from the residual source.Since that time, optimization of injection strategies has maintained efficient dechlorination while demonstrating accelerated cleanup at a lower cost by changing to a whey powder amendment that solubilizes DNAPL.