One of biggest challenges to treating contaminated aquifers with chemical oxidants is achieving uniform coverage of the target zone. In an effort to maximize coverage, we report the design and installation of an aerated, slow-release oxidant delivery system that can be installed by direct-push equipment. By continuously bubbling air beneath the oxidant in situ, the upward airflow causes water and oxidant to be dispersed from the top of the outer screen and drawn in at the bottom. This 24/7 circulation pattern greatly facilitates the spreading of the oxidant as it slowly dissolves from its wax matrix (i.e., oxidant candle). Given that the aeration rate controls the outward flow of oxidant from the outer screen in all directions, the radius of influence around each drive point is largely a function of the outward velocity of the oxidant exiting the screen and the advection rate opposing the up gradient and lateral spreading of the oxidant. Field results from sites treated with the aerated, oxidant delivery system show down gradient contaminant concentrations typically decrease 50 to 99% within 6 to 9 months after installation. Supporting treatability studies and oxidant release characteristics from an alternative wax-less delivery device will also be presented.

Primary Author:
Mark Christenson
AirLift Environmental, LLC
Lincoln, Nebraska, USA


Conference Presenter:
Steve Comfort
Professor of Soil and Water Chemistry
University of Nebraska-Lincoln

James Reece, AirLift Environemtnal, LLC, Lincoln, NE
Ann Kambhu, Department of Civil Engineering, University of Nebraska, Lincoln, NE
Yusong Li, Department of Civil Engineering, University of Nebraska, Lincoln, NE
Clifford Harris, Department of Chemistry, Albion College, Michigan
Steve Comfort, School of Natural Resources, University of Nebraska, Lincoln, NE