Conducting Subsurface Environmental Investigations in Urban Watersheds - Urban Watersheds: Geology, Contamination, and Sustainable Development - page 137

TABLE 4.1
Types and Purposes of En vironmental Investigations

Investigation Type Purpose

Phase I ESA Qualitative review of a specific site to evaluate if there is any scientific basis the

site poses any environmental risk

Phase II Quantitative study that finds, defines, and refines the nature and extent of

contamination

Geophysical Investigation Used to supplement and add geologic and hydrogeologic information to Phase II

investigations; helps identify and locate buried objects, utilities or other buried
structures

Risk Assessment Evaluate whether the presence of contamination poses an unacceptable risk to

human health and the environment

Feasibility Study Evaluate potential remedial alternatives with the objective of selecting the most

appropriate technology(s) to lower risk to an acceptable level

Remedial Investigation Defines the nature and extent of contamination at large sites likely posing

significant risk to human health and the environment

NRDA Assess damages to natural resources

EIS Evaluate potential impacts of future development on natural resources and the

environment

RAP Plan outlining what actions will be conducted to lower risk to an acceptable level

Completion Study Quantitative investigation conducted to confirm that the remediation at a site is

sufficient and complete

• Statistical methodology, if statistical methods are used
• Cleanup criteria for each COC
• Contingency plan in case one or more samples indicate remediation has not been
completed

4.2.12 Summary of Environmental Investigations

Table 4.1 lists each type of environmental investigation and its major purpose. The Phase II
Investigation, Remedial Investigation, and the Geophysical Investigation typically gener-
ate the most geological and hydrogeological information—and in some instances—gener-
ate a large volume of detailed information. In addition, the Phase I ESA often has valuable
information useful for geological purposes, especially if a Phase II or other investigation
is subsequently conducted.

4.3 Common Environmental Sampling Methods
Sampled items during an environmental investigation typically include soil, groundwater,
sediment, surface water, or air. The primary objectives when collecting any sample during
an environmental investigation are (1) collecting a representative sample and (2) ensuring
the integrity of samples collected by taking measures not to contaminate or cross-contam-
inate the samples, or altering any of the original properties of the sample (USEPA 1988).