Disclosed herein are in situ waste remediation methods and systems configured to hydraulically isolate waste material from groundwater. Methods for enclosing and/or remediating waste impoundments, landfills and the like using discrete in situ solidification/stabilization techniques are provided. The disclosed methods and systems provide containment techniques to create a vertical barrier to further isolate waste from groundwater and enhance geotechnical stability by increasing embankment strength, reducing saturated conditions and increasing the overall factor of safety for slope failure.