Phase 1 Desk Study and Preliminary Land Assessment

A Phase 1 desk study brings together existing information about a site and its surroundings to assess potential contamination concerns. Combined with a walkover, it develops an initial picture of the relevant sources, possible pathways and receptors. Its value is in explaining what the evidence means for the proposed use and what remains to be established.

Phase 1 Desk Study and Preliminary Land Assessment enquiry

Set the purpose before collecting records

A purchase review, a planning requirement and a review of an operating site can need different levels of detail. The site boundary, proposed development and reason for the assessment should be clear before records are interpreted.

The same historic activity can have different significance depending on the future use. A proposed building layout, landscaped area or change in occupancy can alter which questions need attention. The study should connect its conclusions to the stated proposal rather than assume a generic end use.

A surveyor recording observations on undeveloped land.

Historical land use

Maps, records and a site walkover help identify past activities and possible contamination sources.

The proposed development

Future use determines which people, waters or buildings could be affected by conditions in the ground.

Interpret the history and environmental setting

Historic mapping, previous reports, land-use records and information about the surrounding environment help build the site history. Dates and coverage matter: an older report may describe a different boundary or an earlier development proposal.

Neighbouring activities can be relevant where there is a plausible route for contaminants to affect the site. The red-line boundary identifies the project area but does not, by itself, establish the limits of every potential environmental influence.

Gaps or inconsistencies in records should remain visible. A missing entry on a map does not establish that an activity never occurred, while a label showing a former use does not identify every material handled there.

Use the walkover to test the initial picture

Present-day observations can help connect historical information to actual features. Tank positions, drainage, storage areas and changes in ground level may support or challenge the initial interpretation.

The walkover also records what could not be observed. Buildings, hardstanding and access restrictions can leave questions unresolved. Recording those limits makes it easier to target later work where the uncertainty matters to the assessment.

Soil and rock core samples arranged in divided sample boxes.

Discuss Phase 1 desk study

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Develop the initial conceptual site model

The conceptual site model identifies potential contamination sources, the pathways through which contaminants could move and the receptors that might be affected, such as people, groundwater or surface water. These elements are considered together as potential pollutant linkages. At the preliminary stage, a linkage may be plausible without every element having been confirmed through investigation. The assessment should explain the evidence supporting each potential linkage, the uncertainties affecting its significance and whether further assessment is needed to evaluate the risk.

The LCRM risk assessment guidance describes preliminary assessment and the decisions that follow it. A Phase 1 study uses the available evidence to explain which linkages need further examination and which conclusions are proportionate at that stage.

Explain what happens next

Further investigation is justified by the questions the initial work leaves open, rather than by the Phase 1 label alone. A proposed intrusive investigation should identify what information it is intended to obtain and how that information will inform the decision.

The report should also explain when existing information supports a conclusion without further fieldwork. That conclusion remains tied to the scope, proposed use and available evidence. New site information or a materially different development proposal may require the assessment to be revisited.

Ian Bennett and Mark Lynch are environmental consultants who can speak on our behalf about our environmental services.