Presenter: Sarah Knowles ERM NZ
Presentation title: Rethinking LNAPL recovery metrics
After decades of environmental regulation, environmental professionals are often still attempting to understand LNAPL impacted sites and the best remedial strategy to meet often vague cleanup standards which are frequently defined as “to the extent practicable”. Historically, remedial efforts were required to reduce the LNAPL thickness in wells to an arbitrary LNAPL thickness objective and/or meet some type of time based recovery rate metric. In addition, the historical reliance on LNAPL thickness as the primary metric to develop LNAPL conceptual site models (LCSMs) has frequently resulted in over simplification of subsurface conditions and poor understanding of LNAPL mobility and recoverability. The result is that the hydraulic recoverability of LNAPL impacts was frequently not well understood and resulted in implementation of remedial strategies that could not meet remedial objectives and did not address actual site risks. Understanding of the mobility and recoverability of LNAPL is increasingly being evaluated using alternate metrics including LNAPL transmissivity. Significant progress has been made in standardizing the methods and techniques to quantify LNAPL transmissivity in unconsolidated formations with development of the ASTM LNAPL transmissivity standard and American Petroleum Institute (API) baildown test analysis sheets. This presentation will provide insights into the applicability and benefits of LNAPL transmissivity as a metric to support development of accurate LCSMs, effective remedial strategies, and address site risks.
Event: WasteMINZ Conference 2013
Date: Thursday 24 October 2013