[en] This study concerns the solidification of low-level and transuranic (TRU) liquid organic wastes produced during normal operations at the Rocky Flats Plant. Its purpose was to determine an acceptable and cost effective method for immobilizing liquid organic wastes. Envirostone gypsum cement; Portland cement; Portland cement with Oil Dri absorbent; Envirostone with Portland cement; and Envirostone with Oil Dri absorbent were investigated for their suitability in producing waste forms in compliance with all TRU waste acceptance criteria for the Waste Isolation Pilot Plant (WIPP) as specified in WIPP-DOE-114. Evaluation of the various solidification media was based on suitability for immobilizing organic wastes, waste loading efficiency, required set-time, and cost of production scale operation. The production scale operation costs included materials, packaging, shipping, and storage. The study indicates that Envirostone gypsum cement is most applicable to the organic wastes generated at Rocky Flats Plant. Envirostone provides a solid, homogeneous cast absent of free liquids while achieving waste loading efficiencies of up to 50 vol %. The yearly production scale costs for solidification with Envirostone would amount to about $265,000