Phase I vs. Phase II

A Phase I is investigation without intrusion: records, history, reconnaissance, interviews, professional judgment. Its output is an opinion on whether recognized environmental conditions exist. No samples are taken.

A Phase II is testing: soil borings, groundwater monitoring wells, soil vapor probes, laboratory analysis. Its purpose is to confirm or refute what the Phase I flagged, and to begin characterizing extent. Its output is data.

The relationship is sequential and targeted. A Phase II scope is designed around the specific RECs the Phase I identified: borings placed where the former tanks were, wells placed down-gradient of the suspect operation. It is not a general fishing expedition. This is why Phase I quality matters to Phase II value. A vague or padded Phase I produces an unfocused, expensive Phase II. A missed REC produces no Phase II at all where one was needed.

Cost scales accordingly: a few thousand dollars for a Phase I, while Phase II work commonly starts around $5,000 to $15,000 for a limited scope and climbs with the number of locations, depths, and analytes.

One boundary worth knowing: an inadequate Phase II (too few points, wrong locations) can produce false comfort no standard requires anyone to honor. Scope design is where the professional earns the fee.