Datum Beta
Start free

← Project Planning & Design

Sheet C-102
PA PjMPPD

Environmental & Site Conditionsconcept

Environmental Site Assessment: Phase I / II / III

One-line orientation

An Environmental Site Assessment investigates possible contamination in stages. Phase I reviews records and the site without sampling; Phase II uses sampling to confirm contamination; Phase III addresses cleanup.

Key points

  • Phase I — assess potential, no sampling:
    • Site reconnaissance (walk-through), review of historical and regulatory records, and interviews with current/past owners, occupants, and neighbors.
    • No soil or groundwater sampling. Output is a list of potential environmental concerns.
    • Done properly, it provides liability protection under CERCLA (the federal Superfund law).
  • Phase II — confirm by sampling:
    • Soil and groundwater sampling and lab testing for heavy metals, petroleum hydrocarbons, pesticides, and other hazardous substances.
    • Confirms the presence, type, and extent of contamination — but does not assign liability.
    • Only triggered if Phase I flags potential contamination; Phase I also guides where to sample.
  • Phase III — remediate:
    • Design, execute, and monitor a remediation plan; clean the site to regulatory standards so it is safe for intended use.
  • ESA supports brownfield redevelopment and protects a buyer from liability for prior contamination when the All Appropriate Inquiries timing and user obligations are satisfied.

Environmental Site Assessment: sampling starts at Phase II

Phase I is records, walk-through and interviews with no sampling; sampling starts at Phase II, and only if Phase I flags a concern.

View diagram Hide diagram

Scroll horizontally to explore

The staged Environmental Site Assessment flow from Phase I to Phase III A left-to-right flow. Phase I — records review, site walk-through, and interviews — is tagged no sampling, and a note directly beneath it states that Phase I gives a liability shield under CERCLA when properly performed and current. An arrow leads to a decision diamond: potential contamination found? If yes, Phase II — soil and groundwater sampling plus lab testing — is highlighted as where sampling starts, and a note beneath it states that Phase II confirms the presence, type, and extent of contamination but does not assign liability. Then Phase III, design and monitor the cleanup, the remediation stage. A no branch from the diamond drops down to no further action. A footnote gives the All Appropriate Inquiries currency rule: generally within one year before acquisition, with key components updated within 180 days. Phase Irecords · walk-through · interviewsno samplingpotentialcontamination?yesPhase IIsoil + groundwater samplingsampling starts herePhase IIIdesign + monitor cleanupremediationLiability shield under CERCLAwhen properly performed and currentConfirms presence, type, and extentdoes not assign liabilitynono further action

All Appropriate Inquiries must generally be current within one year before acquisition, with key components updated within 180 days.

Confusions / comparison

Phase IPhase IIPhase III
GoalAssess potentialConfirm contaminationRemediate
MethodRecords, walk-through, interviewsSoil/groundwater sampling + testingCleanup plan + monitoring
Sampling?NoYesn/a (already confirmed)
Triggers next phase?Only if concerns foundConfirms extent (no liability assigned)—
LiabilityProvides CERCLA protectionDoes not assign liability—

→ Brownfields and remediation (this module): the redevelopment context an ESA enables, and ESA vs EIA · Site hazardous materials (this module): the contaminants Phase II tests for · Code / ProPractice: the architect facilitates expert recommendations rather than making remediation calls.

Spotted an issue with this card? Tell us →

Related units

BrownfieldsSite hazmat