The main purpose of conducting a PH II ESA is to determine whether known or possible contamination might be encountered during construction. The information from a PH II ESA may be useful in developing cost-effective preventive action plans or specifications to handle any contamination found. A PH II ESA may also help to determine closure requirements of regulated facilities or contaminated areas. A PH II ESA should include the following activities:

Sampling and analysis can be very expensive. The most cost-effective approaches will vary on a case-by-case basis. Several factors determine when and how to conduct a cost-effective environmental site investigation. For example, the sampling and analysis plan should limit the number of investigations or remobilization. However, multiple or phased investigations may be necessary for some projects or individual sites; detailed information about a project's proposed excavation and de-watering requirements may be needed to develop an adequate sampling and analysis plan. One option is to perform more detailed design activities during advanced planning to facilitate the investigation. Another option is to postpone investigation until the project details are known later in the project development process. It may also be more cost-effective to combine geotechnical testing with environmental testing.

Since a preferred alternative or alignment could change during the environmental process, investigations should be performed after approval of the environmental documentation, public involvement or environmental clearance. To determine whether possible contamination exists on a proposed right of way, investigations depend on property owners providing access or right of entry. If right of entry is refused, the investigation may be postponed until the eminent domain process or until after acquisition.

FHWA has specific guidelines for projects requiring Environmental Impact Statements (EIS). Prior to selection of a project alternative, detailed design activities and additional investigations may be necessary to evaluate the impact and obtain sufficient information for the project decision-making process. Sufficient information is necessary to characterize the site, identify the type and extent of contamination, and estimate disposal, waste management or cleanup costs. It may also be necessary to determine alternative treatment, cleanup, disposal measures, and associated costs. Assuming that right of entry can be obtained, the hazardous materials assessment should be completed and documented in the Final EIS prior to circulation; however, it is not necessary to complete all investigations prior to environmental clearance. If a contaminated site cannot or will not be cleaned up prior to acquisition and it is decided to proceed with the project, then a more detailed site investigation can be performed after clearance. More detailed site investigations may be needed to determine waste characteristics, hydrogeologic conditions and/or extent of contamination.

For all projects, hazardous materials assessment should be completed prior to finalizing the Plans, Specification and Estimates (PS&E). If the analytical testing does not reveal contamination, then there is added support that contingencies or special provisions are not required in the PS&E.