GroundwaterU Video Summary

The video demonstrates the migration of a dyed perchloroethylene (PCE), a dense non-aqueous phase liquid (DNAPL), through various subsurface layers in a water-saturated environment, which is highly relevant for understanding groundwater contamination.

In this setup, the dyed PCE is released into coarse sand saturated with water. Initially, the PCE accumulates to form a pool until it reaches a critical height. At this point, it breaks through the coarse sand and migrates downward into a medium sand layer. Eventually, the PCE encounters a sloping fine sand layer, where it changes direction and migrates laterally.

As the DNAPL reaches a break or gap in the fine sand layer, it continues to migrate downward, forming another pool on a deeper fine sand layer. This behavior repeats as the PCE forms pools at different depths, often migrating laterally and vertically depending on the subsurface stratigraphy. One key observation from the video is that the deep pools are not located directly below the release point, reflecting a common field observation of DNAPL migration at contaminated sites. Fine-grained layers act as capillary barriers, significantly influencing the downward and lateral migration of DNAPLs. Note that the duration of the experiment is approximately 80 minutes.

The relevance of this video to groundwater contamination lies in the behavior of DNAPLs in the subsurface, which are difficult to remove once they infiltrate. The ability of DNAPLs to accumulate in pools, migrate laterally along sloping layers, and bypass certain subsurface zones creates long-term contamination challenges. This illustrates the importance of understanding subsurface geology when investigating or remediating DNAPL contamination at field sites.

Authors:

Concepts and videography:
Kevin Mumford, Queen’s University, Canada
Bernard Kueper, Queen’s University, Canada
Robert Lenhard, Southwest Research Institute, USA
Script and Audio:
Eileen Poeter, Colorado School of Mines, USA

Visit The Groundwater Project (gw-project.org) for free, educational books related to groundwater. The books include links to other videos.

About this Video

Source: youtu.be/AErx9tT-HYs?si=Uvies7_SIpFlyxUZ
Video Creator: See authors above.
Recommended/Summary by: Andrew Cohen
Curated by GroundwaterU on: Sept 18, 2024

Video Language: English
Video Category: Science/Engineering
Multimedia Type: Film/Pictures
Presentation Style: Demonstration
Technical Level: Beginner