Natural Source Zone Depletion (NSZD) – the collective process that reduces the concentration and toxicity of contaminants in Light Non-Aqueous Phase Liquid (LNAPL) source areas- results in significant mass losses, often at rates equal to exceeding that of active remediation systems. While NSZD is ubiquitous, the science and the regulatory acceptability of this process is just catching up.
The quantification of NSZD has long been underestimated with only the relatively minor mass removal contributions from groundwater being evaluated. Accounting for all process phases – particularly the dominant gaseous phase contributions – can help demonstrate mass loss and help change your regulators perceptions, potentially avoiding significant spending on active remedial systems. As NSZD becomes established as a valid remediation technique and gains acceptance with regulators, the methods for quantifying it are also evolving to help demonstrate this as a viable source remediation option.
Join us as EHS Support shares experiences with shortfalls in guidance documents and simple but effective methods that we have used to demonstrate the effectiveness of NSZD and overcome some of the challenges with regulatory agencies.