Site Assessment Program 

Expanded Preliminary Assessment Report Guidance

The purpose of a Preliminary Assessment or PA Equivalent is to determine whether a site is releasing, has released, or could release hazardous substances to the environment, and whether a response action is required. Occasionally, however, following the completion of a PA or PAE there is insufficient information available to make such determinations about a site. In such cases, an Expanded Preliminary Assessment can be a useful means to gather the additional data needed to formulate the further-action conclusions that are expected from PA-level investigations. While XPAs typically involve the collection of samples to obtain information about the presence, type, or magnitude of contamination at a site, they are not remedial investigations, and are not designed to fully characterize site contamination.

There are two parts to an XPA investigation: preparing a sampling plan and producing the XPA report. DEQ has developed two guidance documents to explain these two parts: the XPA Sampling Plan Guidance, and this document, which addresses XPA reports.

The XPA report should discuss: 1) the reasoning behind and procedures used to carry out the sampling portion of the investigation; 2) the results of all sampling and analyses outlined in the XPA sample plan; and 3) any additional site information obtained during the XPA investigation. In the XPA report, it is important to include information on sampling objectives, field procedures, analytical QA/QC, etc., to permit an assessment of the validity of sampling data. The XPA report should also discuss any changes to the sampling plan due to unexpected field conditions.

The XPA report should include at least the elements listed below; sometimes, additional information may also be needed, on a site-by-site basis.

The links below explain the structure and content of a DEQ XPA report.

• Introduction
  Site Background/Apparent Problem
• Sampling Objectives
  Sampling Activities Performed (by media)
  Sampling Results
• Other Data Collection
  Summary and Conclusions
  References/Attachments

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