The United States spends around $2 billion a year on remediation at hazardous waste sites, with a large portion of this used for ground water monitoring. Yet according to Rolf Halden, a researcher at Arizona State University's Biodesign Institute, the information gathered often is of limited value.
Under a new
three-year, $1.15 million grant from the U.S. Department of Defense (DoD),
Halden, assistant director at the Institute's Swette Center for Environmental
Biotechnology, is pursuing a novel method to conduct these vital tests. His
team's efforts are part of a quest to provide more accurate results at lower
cost, and produce fewer harmful byproducts during the monitoring process.
considering techniques suitable for ground water monitoring, three components
are key – the quality of data provided, the cost of the procedure and the
environmental impact. Conventional monitoring typically accounts for at least
20 percent of the total cleanup costs incurred during site remediation. From a
project management standpoint, however, the analyses and acquired data often
can be misleading and unsatisfactory, as well as environmentally damaging.
ground water is extracted from the earth for testing and then sent to a lab for
detailed analysis. The method is financially and environmentally costly,
because the water must be transported, and the process can generate significant
amounts of hazardous waste at the surface.
technique involves monitoring ground water while it still is in place in the
subsurface, using a device known as the in-situ sampler or IS2, which may be
custom-fit into ground water monitoring wells. The IS2 is deployed downhole,
where its integrated pumps draw up ambient ground water at milliliter per day
rates. Analytes of interest are concentrated onto solid adsorption media for
analysis. One of the advantages of this in-situ approach is that effluent from
the device remains in the subsurface. Only the device itself with the extracted
analytes is removed from the well. In this way, monitoring can be conducted
without the use of purge water or the liberation of wastewater at the surface.
device has completed its work and is removed from the well, the
contaminant-charged media are shipped to the laboratory, where they undergo
automated analysis assisted by robotics, as well as standard methods including
mass spectrometry and ion chromatography. The new technology boasts extremely
low detection limits – in the ng/L to pg/L range. Further, it produces no
wastewater, and may be carried out at a low cost per sample, thanks to the use
sentinel will be applied on a pilot basis at DoD sites and used in multiple
deployments to examine a range of ground water contaminants, including volatile
organic compounds like tetrachloroethene, trichloroethene and vinyl chloride;
water-soluble fuel components (benzene and toluene); explosives (RDX and TNT);
semi-volatile compounds (phenol); polycyclic aromatic hydrocarbons (naphthalene
and phenanthrene); inorganic water contaminants (perchlorate); and heavy metals
(arsenic and lead). Each of these analytes will be captured in-situ, using a
pair of customized IS2 devices. Results will be compared to those obtained with
conventional water-monitoring approaches.
project seeks to demonstrate improved detection limits, 10 times to 100 times
lower than those achieved through current Environmental Protection Agency (EPA)
Monitoring Waste in Ground Water
March 10, 2011