Page 230 - Environmental Control in Petroleum Engineering

CHAPTER 8

Remediation of

Contaminated Sites

Many petroleum industry sites have been contaminated from previous
activities or can become contaminated through accidental releases of
various materials. In many cases, remediation will be required to
restore the impacted area. Sites that may require remediation include
old reserves pits, onshore release sites of hydrocarbons or contami-
nated water, and places where oil slicks from offshore releases are
blown onshore.
Unfortunately, the complex pore structure and fluid transport path-
ways of soil can make remediation difficult. Hydrocarbons can be
found in various places in soil. Most are trapped by capillary pressure
as a discrete liquid phase within the pores of the soil. If a sufficient
volume of hydrocarbons has been released, it can exist in a separate,
mobile phase that floats on top of the groundwater. Hydrocarbons can
also be dissolved into the groundwater and be transported away from
the release site. Volatile hydrocarbons can be found as a vapor in air-
saturated pores. Dissolved solids can also be found in various places
in soil. They can remain dissolved and migrate with groundwater or
they can be absorbed onto the soil solids.
Because of the complex distribution of contaminants in soil, a compre-
hensive site evaluation may be required before the optimum remediation
process can be selected and properly implemented. A number of site
remediation methods are available and are reviewed below.

8.1 SITE ASSESSMENT

An important process in the cleanup of contaminated sites is to
assess their potential to impact human health and the environment

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