· Hollow - stem augering is the recommended drilling method for vent wells;
however, a solid- stem auger is also acceptable in more cohesive soils. Whenever
possible, the diameter of the annular space will be at least two times greater than
the vent well outside diameter. The annular space corresponding to the screened
interval will be filled with silica sand or equivalent.
· Sites with the majority of the soil c ontamination in the capillary fringe may benefit
from a vent well that is designed with a shorter screened interval that will focus air
into the capillary fringe. These wells may h ave several feet of screen below the
water table to take advantage of seasonal water level changes. During high water
seasons, these wells may actually function as sparging wells. Sparging will
introduce oxygen to the capillary fringe more effectively than a vent well screen
constructed above the capillary fringe.
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