Page 22 - Materials Chemistry, Second Edition

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Site Assessment and Remedial Investigation

2.1 Introduction
The initial step, often the most critical one, of a typical soil and/or ground-
water remediation project is to define the problem. It is accomplished by site
assessment and remedial investigation (RI).
Site assessment (also referred to as site characterization) is to understand
what has happened at a site. When site remediation is deemed necessary,
RI will be employed. RI activities consist of additional site characteriza-
tion and data collection. The data are needed in making engineering deci-
sions on control of plume migration and selection of remedial alternatives.
The common questions to be answered by the RI activities include the
following:

• What media (surface soil, vadose zone, underlying aquifer, air) have
been impacted?
• Where is the plume located in each impacted medium?
• What are the vertical and areal extents of the plume?
• What are the concentration levels of compounds of concern (COCs)?
• How long has the plume been there?
• Where is the plume going?
• Has the plume gone beyond the property boundary?
• How fast will the plume go?
• What are the on-site sources of the COCs?
• Are there potential off-site sources to this plume (now and/or in
the past)?

Subsurface contamination from spills and leaky underground storage
tanks (USTs) creates environmental conditions that usually require corrective

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