Monitoring-Well Oil Skimming
http://en.wikipedia.org/wiki/Groundwater_remediation
Monitoring-wells are often drilled for the purpose of collecting
ground water samples for analysis. These wells, which are usually six inches or
fewer in diameter, can also be used to remove hydrocarbons from the contaminant
plume within a groundwater aquifer by using a belt style oil skimmer. Belt oil
skimmers, which are simple in design, are commonly used to remove oil and other
floating hydrocarbon contaminants from industrial water systems.
A monitoring-well oil skimmer remediates various oils, ranging
from light fuel oils such as petrol, light diesel or kerosene to heavy products
such as No. 6 oil, creosote and coal tar. It consists of a continuously moving
belt that runs on a pulley system driven by an electric motor. The belt
material has a strong affinity for hydrocarbon liquids and for shedding water. The belt, which can have a
vertical drop of 100+ feet, is lowered into the monitoring well past the
LNAPL/water interface. As the belt moves through this interface it picks up
liquid hydrocarbon contaminant, which is removed and collected at ground level
as the belt passes through a wiper mechanism. To the extent that DNAPL hydrocarbons settle at the bottom of a
monitoring well, and the lower pulley of the belt skimmer reaches them, these
contaminants can also be removed by a monitoring-well oil skimmer.
Typically, belt skimmers remove very little water with the
contaminant, so simple weir type separators can be used to collect any
remaining hydrocarbon liquid, which often makes the water suitable for its
return to the aquifer. Because the small electric motor uses little
electricity, it can be powered from solar panels or a wind turbine, making the system self-sufficient and
eliminating the cost of running electricity to a remote location.