An innovative new groundwater modeling tool called MODular ALLocation, or MODALL, can be used to shorten remediation projects and for assessing project performance. This program developed by ARCADIS / Malcolm Pirnie, was used at Reese Air Force Base in Texas and it proved efficient at remediating groundwater contamination.
Reese Air Force Base opened in 1941 as a pilot training facility and was closed in 1997 because of its high level of contaminants. Contamination at the site consists mostly of hydrocarbons and chlorinated solvents, which were used to clean aircraft. These contaminants degrade local groundwater resources and drinking water. A conventional pump-and-treat system was adopted in 1990 to try to remove the contaminants from the groundwater. In 2004, ARCADIS / Pirnie started a Remediation Program with two main goals:
- Cleanup the base
- Optimize the system and reduce the time required to complete the remediation objectives
How does MODALL work exactly?
This new pumping model was completed in 2005. It captures and treats more contaminants of concern than before, and in less time. This tool can capture the plumes and provide information on the plumes which can enable more efficient treatment. The groundwater system enables the model to examine flow allocations and the model can then generate contour maps depicting the capture of treatment systems remediating the plume. Thus, ARCADIS figures out exactly where the existing treatment system is operating effectively. As a result, ARCADIS can reduce the amount of groundwater extracted for treatment while still capturing the plume. The plume is better driven toward the extraction point, by better targeting the injection points.
What were the results of the model ?
- A reduction of the rate of groundwater extraction from 651 gallons per minute (gpm) to 350 gpm
- An improvement of the speed with which the plume is captured. ARCADIS captured the plume at a rate of two to three acres per week
- A major cost savings by more than $ 22 million
- An acceleration of remediation elsewhere at the site. The deadline for the remediation program is 2014 but ARCADIS expects to complete the work before. The firm already shortened the program by 20 years.
If you have any questions about groundwater systems, please contact John McAllister at firstname.lastname@example.org or at (508) 747 - 7900 x 117.
Information in this article taken from November 2011, article ‘’Groundwater Model shortens remediation projects by 20 years ‘’ by Jay Landers, published in Civil Engineering.