This metadata record contains 15 tables with results from field and laboratory tests used to assess bioremediation in wetland areas at the Standard Chlorine of Delaware, Inc. Superfund site, New Castle County, Delaware, during 2019-2021. Included in the dataset are (1) polychlorinated biphenyl (PCB) concentrations in wetland sediment from sediment microcosm laboratory experiments, (2) chlorobenzene concentrations in wetland sediment from sediment microcosm laboratory experiments, (3) polychlorinated biphenyl concentrations from PCB microcosm laboratory experiments using polyethylene strips, (4) chlorobenzene concentrations from PCB microcosm laboratory experiments using polyethylene strips, (5) total iron and ferrous iron concentrations from compost microcosm laboratory experiments, (6) methane (aqueous phase) concentrations from compost microcosm laboratory experiments, (7) volatile organic compound concentrations from compost microcosm laboratory experiments, (8) methane concentrations from polyethylene passive diffusion bag samplers collected during field sampling in the wetland area, (9) volatile organic compound concentrations from polyethylene passive diffusion bag samplers from field sampling, (10) chlorobenzene concentrations in water from field sampling using low density polyethylene sheet passive samplers, (11) polychlorinated biphenyl concentrations in water from field sampling using low density polyethylene sheet passive samplers in the wetland study area, (12) volatile organic compound concentrations for water samples collected from compost microcosm experiments with and without granular activated carbon, (13) volatile organic compound concentrations in sediment, extracted from methanol aliquots collected from compost microcosm experiments with and without granular activated carbon, (14) total iron concentrations for samples collected from compost microcosm experiments with and without granular activated carbon, and (15) methane (aqueous phase) concentrations for samples collected from compost microcosm experiments with and without granular activated carbon.