Reading Phase II results

A Phase II report ends in a table of concentrations next to a column of screening levels. Reading it well means knowing what those columns are and are not saying.

Screening levels are not cleanup orders

Results are compared against risk-based screening values: EPA's Regional Screening Levels federally, and each state's own tables where they exist. For most screening tables, exceeding a value does not automatically mean cleanup is required (though in some states the published values are enforceable standards with their own obligations); it means the concentration cannot be screened out and warrants evaluation, often against site-specific factors like land use and groundwater use. Different use scenarios carry different values, and a number that passes for industrial use can fail for residential.

Detection is not the same as exceedance

Laboratories report what they can detect, and modern methods detect very small amounts. A long list of detections below screening levels is a normal result, not a red flag. The comparisons that matter are the exceedances, their locations, and whether they form a coherent pattern with the conceptual site model.

Extent matters as much as concentration

One hot sample at a source is a different problem from the same concentration at the property line. A well-designed Phase II brackets the finding: how far laterally, how deep, whether groundwater carries it off-site. Findings that end at the edge of the sampled area are findings whose extent is unknown, and the report should say so.

What a clean report means

No exceedances at the locations sampled, for the analytes tested, at the depths investigated. That sentence is the honest scope of a clean Phase II. It resolves the RECs it was designed to test; it does not certify the property. Read the report's limitations section to see what was outside the design.