Jeff Lane, CK Associates – 616 FM 1960 West, Suite 575, Houston, Texas 77090, firstname.lastname@example.org
In some cases, recovery of LNAPL is critical to prevent plume spreading and protect receptors (i.e. discharges to surface water, persons or animals contacting impacted soil or vapors, and users of water wells) and the traditional approach to address LNAPL is mass recovery until LNAPL is no longer measurable. However, recent understanding of LNAPL characteristics and technical guidance indicates it may not be practical or necessary to remediate an LNAPL plume in all cases. Under the right circumstances, a risk-based approach considering source, receptors, contaminate, state regulations, and land use may be appropriate.
Analysis of recoverability metrics provides a technical basis for evaluating the practicability of LNAPL recovery. These metrics include transmissivity, physical/chemical LNAPL characteristics, LNAPL saturation, performance data associated with historic recovery efforts, and professional judgment combined with predictive software tools (i.e. API spreadsheets).
For situations where a risk-based evaluation is appropriate, the important questions are: Has the source been removed? Is the plume delineated and stable? Are receptors protected from risk? If “Yes”, then recovery of LNAPL may not be necessary for closure. This presentation will make a case for a risk based approach for evaluating the practicability of LNAPL recovery and provide case studies from several states.
Key Words: LNAPL, closure, recovery, protected