Remediation geotextile device, including a geotextile mattress-like component, configured to contain an active granular material for filtering and treating contaminated groundwater and/or sediment porewater. The geotextile device including a six-sided, or substantially rectangular, mattress-like component, including an upper geotextile layer and a lower geotextile layer that are connected at intervals with sets of interior geotextile straps.