ENVIRONMENTAL HYDROGEOLOGY. Remediation Is Enhanced Oil Recovery: Know Your Source

Abstract

Non‐aqueous phase liquids (NAPLs) represent direct and indirect sources of potential risk. NAPL can be a long‐lived source of groundwater and vapor impacts because a small volume of NAPL phase can feed very large daughter plumes. For many years, the general environmental industry has built a database of limited remediation success, particularly in terms of mitigating source NAPLs. Any method of cleanup, no matter how fundamentally suited, will likely fail if the zones of NAPL impacts are not effectively targeted. This is analogous to enhanced oil recovery in the petroleum field; recovery enhancements occur only when targeting the zones containing oil. Although cleanup to pristine conditions is usually not viable, cleanups can do a far better job at reducing potential risks when NAPL factors are considered. This said, cleanup technologies also have specific limitations, and success must be defined in terms of the risk–benefit of the applied actions. Full treatment of the NAPL zones may be difficult, but it is usually possible to mitigate risk through remediation and management. This paper provides a few field examples of cleanup failure and documents the specific reasons why the failures occurred. In none of the cases was the failure attributable to geologic complexity or the “tailing” effect of fine‐grained layers. In a last example, cleanup design shortfalls were mitigated by proactively considering the NAPL target zones. Cleanup occurred in less than <6 months using simple technologies.