Contaminated sediment is remediated using a sedimentation capping system comprising composite particles having a core and a coating containing a statin composition. The statins are useful for inhibiting the growth of methanogens, known anaerobes that produce methane from organic materials found in sediments. The reduction in methane production avoids several problems in capping systems, including reduced ebullition that may breach the barrier cap, reduced mobilization and bioavailability of methylated toxins to aquatic life above the cap.
