A method for treating contamination in subsurface formations includes
fracturing the soil to produce a network of fractures in the formation
and simultaneously injecting a slurry containing an optional proppant and
a solid-phase or nonaqueous-phase treatment agent into the network of
fractures. The proppant is for keeping the fractures open, and the
treatment agent accelerates conversion of the contaminants into immobile
or less toxic forms. Chitin is an illustrative solid-phase treatment
agent, which functions as an electron donor for anaerobic reductive
dechlorination mediated by dechlorinating bacteria.