Page 78 - Environmental Control in Petroleum Engineering

Drilling and Production Operations §5

The VOC and benzene levels are typically higher for this remediation
method than for other methods, but have shorter durations of emission.
2
Typical VOC emissions for a soil pile having an area of 2,000 ft are
between 50 and 200 Ibm/hr, depending on the temperature. Benzene
emissions for the pile typically range from 0.5 to 2 lbm/hr.
One way to extract the volatile hydrocarbon components in soil is
by vacuum extraction. Vacuum extraction consists of drilling a well
through the contaminated soil and pulling a vacuum in the well. The
lower pressure forces air into the pile, and volatilized compounds
are vacuumed with the air into the well and removed from the
pile. Because soil is treated in place, vacuum extraction can be less
expensive and less disruptive than other methods. Maximum emission
rates tend to be under 50 lbm/hr for VOCs and under 2 lbm/hr for
benzene, The duration of emissions tends to be on the order of weeks
to months.
Volatile hydrocarbons can also be removed from contaminated water
that has been pumped from the ground by air stripping. In this process,
the contaminated water is allowed to trickle over packing material in
an air stripping tower. Clean air is simultaneously circulated through
the packing material. The volatile hydrocarbons vaporize into the air
and are released to the atmosphere. The removal efficiency depends
on the contaminant, but is typically 99% to 99.5%. Emissions of
volatile hydrocarbons tend to be between 0.5 to 4 lbm/hr, with benzene
releases between 0.1 and 0.5 lbm/hr. Although air stripping has the
lowest emission levels of the three methods discussed here, it typically
has the longest duration,

REFERENCES

American Petroleum Institute, "NO x Emissions from Petroleum Industry
Operations," API Publication 4311, Washington, D.C., Oct. 1979.
American Petroleum Institute, "Fugitive Hydrocarbon Emissions from Petrol-
eum Production Operations: Volumes I and II," API Publication 4322,
Washington, D.C., March 1980.
American Petroleum Institute, "API Environmental Guidance Document:
Onshore Solid Waste Management in Exploration and Production Opera-
tions," Washington, D.C., Jan. 1989.
American Petroleum Institute, "Monographs on Refinery Environmental
Control-Management of Water Discharges: Design and Operation of Oil-
Water Separators," API Publication 421, Washington, D.C., Feb. 1990a,