Natural Attenuation of Groundwater Contaminants: New Paradigms, Technologies, and Applications

In this series of lectures, we will discuss how dilution is an attenuation process – sometimes. We start with the basics, and review groundwater flow and one of the “top ten things” that every hydrogeologist should know: the distinction between Darcy Velocity and Seepage Velocity. Next we give some examples of regulatory programs where dilution is considered an acceptable attenuation process. Then we present how dispersion and mixing in wells are dilution-related processes. Finally we show how the emerging field of mass flux/ mass discharge can be used to see if a contaminant plume is strong enough to impact water supply wells and/or streams, and to see where your plume ranks in the “Plume Magnitude Classification System.”

In this series of lectures, we will focus on several established and emerging methods for demonstrating that biological and other attenuation processes are occurring. We will start with an overview on lines of evidence for biological degradation processes, and then transition to newer molecular methods for identifying and quantifying biodegradation potential for a variety of compounds. Several of this week’s lectures also examine compound-specific isotope analysis, which has been emerging as a key resource for MNA studies. You will learn how stable isotope analyses can provide critical information on whether attenuation is occurring, the rate at which it is occurring, and even the pathway that is responsible.

In this series of lectures, we will discuss how you should perform the monitoring that is such an important part of monitored natural attenuation (after all, it’s right there in the title!). We start off with a discussion of how data are collected, including using newer high-resolution techniques, to help build a proper conceptual site model and support the selection of MNA as a remedy. Then we touch on how to design a long-term monitoring program to assess the performance of MNA. Methods for analyzing concentration trends and graphically presenting MNA data are also presented, along with a discussion of the potential sources of variability in monitoring data.

In this series of lectures, we talk about models and how they can be used to understand MNA. We first start with two key MNA questions: How Long? (will the plume get) and How Far? (how long until the site is clean). Then a review of analytical computer models, remediation timeframe models, the more complex but more powerful numerical models, and even a discussion of the “Fourth Paradigm: Big Data”.

This final series of lectures will cover a mélange of interesting MNA topicsl We start with the brand new ESTCP BIOPIC tool, then talk about the broad universe of MNA that extends to a lot of different contaminant classes. Then some new developments in the LNAPL world: Natural Source Zone Depletion, both with conventional methods and a new method based on thermal monitoring. Then we talk a little bit about low threat closures and transition assessments, and end up with a brief conversation with the three instructors. And then you are done!