of In-situ Remedial Technologies,
Hydrocarbon Plume, Phoenix, Arizona
and diesel releases from an active fuel station created a groundwater
hydrocarbon plume that eventually migrated 1/4 mile from the
facility. Previous remedial efforts were hampered by high arsenic
concentrations and an off-site TCE plume commingled with the
hydrocarbon plume. The client requested that Hydro Geo Chem
manage remedial efforts, and specifically develop, test, and
implement in-situ containment and source reduction technologies
that would not result in additional waste streams or extracted
Geo Chem Approach
and effective containment solutions were needed because of the
plume's migration beyond the facility boundaries. We developed
and field tested a sequence of air sparging tests using both
horizontal and vertical wells. Tracer gases were injected and
analyzed to evaluate the effective sparging radii. Oxygen injection
and transport through closely spaced soil borings was also tested
to evaluate its effectiveness in enhancing aerobic degradation.
Both sparging and oxygen transport and consumption were numerically
simulated to evaluate their effectiveness and optimize their
use in full-scale remediation.
simulations agreed with test results from more than 50 oxygen
release points, pointing to their limited effectiveness of only
a few well radii. The field tests and modeling showed the usefulness
of oxygen injection was restricted to small areas of the plume.
The effectiveness of horizontal air sparging
at containing downgradient plume migration was well demonstrated
in the field tests, and full-scale systems were developed using
numerical models. Hydro Geo Chem is currently managing
the engineering design and construction of the remediation system.
Figure: Idealized representation
of sparging well zones of influence.