Soil pollution diagnosis: why, how and with whom to act?

Written by: Joseph OLIVIER

Published on October 29, 2025

Time to read 3 min

Summary

Introduction What is a "soil pollution assessment"? Why conduct a soil pollution assessment? Who is a soil pollution assessment for? How is a soil pollution assessment carried out? When should a soil pollution assessment be carried out? What pollutants are looked for in a soil pollution assessment? How much does a soil pollution assessment cost? What to do after the assessment? Frequently Asked Questions (FAQ) Why trust Pouryère for your soil analysis? To learn more

Introduction

When acquiring land, landscaping a garden, or transforming a vacant lot into a vegetable garden, it's essential to ask one question: is the soil healthy? A soil pollution assessment is the professional answer to this question. It allows for an evaluation of the potential contamination of a plot of land, assesses the risks to health and the environment, and ensures the compatibility between the intended use of the site and its actual condition.

At Pouryère, we put our expertise at your service: from sample collection and laboratory analysis to the delivery of a clear report and actionable recommendations. This diagnostic service empowers you to make informed decisions—especially important in sensitive situations such as buying or selling land, planning a vegetable garden, or undertaking a construction project.

What is a "soil pollution diagnosis"?

A soil pollution assessment is a mission to evaluate the soil's condition in terms of pollution. It involves:

to carry out a historical and documentary study of the site: previous uses, industrial or service activities, storage, tanks, depots.
If necessary, carry out technical investigations : soil sampling, groundwater sampling, laboratory analyses.
to establish a diagnostic report that identifies the pollutants present, the associated risks, and provides recommendations for the management or remediation of the site.

In short: this assessment answers the question, "Is the land suitable for my intended use?" It is a tool for ensuring legal, environmental, and financial security.

Why carry out a soil pollution assessment?

Health and environmental safety

Polluted soil can be a source of contamination for crops, groundwater, and local residents. Soil testing can detect the presence of heavy metals, hydrocarbons, solvents, and persistent chemicals.

Legal and regulatory responsibility

In France, Articles L 125-6 and L 125-7 of the Environmental Code stipulate that soil condition and pollution must be taken into account. If the land is located within a SIS (Soil Information Sector) or is a former industrial site (ICPE), a soil assessment may be mandatory.

Project valuation and security

Before a sale, development, construction or change of use of land, carrying out a soil pollution diagnosis helps to avoid unpleasant surprises, to negotiate calmly and to guarantee environmental compatibility.

Pouryère relies on this logic: to support you so that your land or development choices are based on reliable data.

Who is the soil pollution assessment for?

For individuals : garden owners, land buyers, vegetable garden planners wishing to check for the absence of contamination.
For professionals : property developers, planners, industrialists, cessation of activity of an ICPE, rehabilitation of brownfield sites.
For local authorities : land management, transformation of former sites or redevelopment of urban spaces.

At Pouryère, we adapt our approach according to the public: from the amateur gardener to the demanding project owner, we offer a professional but accessible service.

How is a soil pollution diagnosis carried out?

Phase 1 – Documentary and historical study

This phase consists of:

consult the archives, maps, old aerial photographs, previous uses of the site.
identify if there are any SIS, classified installations, landfills, underground tanks.
identify risks, establish a typology of potential pollutants.

At the end of this phase, a decision can be made as to whether or not samples are necessary.

Phase 2 – Technical characterization and analyses

If phase 1 has identified a potential risk, we proceed to:

sampling of soil, water or soil gas according to a defined sampling plan.
analyses in accredited laboratory (COFRAC) to measure pollutant concentrations.
interpretation of results, comparison to guideline values, assessment of health and environmental risks.

Report and recommendations

Soil pollution assessment does not stop at the analyses: it includes an expert report with:

Mapping of pollutants, depth, contaminated areas.
compatibility with the future use of the site.
Proposal for a management, monitoring, or remediation plan. ( prestations.ineris.fr )

Example of a simplified process

You are contacting Pouryère.
We collect your information (previous uses, geographical area).
A literature review is conducted.
If necessary, samples are taken (soil, water).
Laboratory analysis.
Report sent with recommendations.
Follow-up or support depending on the results.

When should a soil pollution assessment be carried out?

Here are some typical situations:

Land located in a SIS or former industrial site.
Sale of land or real estate with suspected pollution.
Cessation of activity of an ICPE, change of use (e.g. from industrial use to residential use).
Development of a vegetable garden on a former service site, garage, petrol station.
Construction project, infrastructure development or housing estate.

In all these situations, soil pollution diagnosis is a tool for prevention and reliability.

What pollutants are sought during a soil pollution diagnosis?

Among the most frequently searched:

Heavy metals (lead, cadmium, mercury, arsenic).
Hydrocarbons (gasoline, fuel oil, PAHs).
Solvents, volatile organic compounds (VOCs).
Other pollutants: pesticides, plastics (microplastics), persistent substances.
Pollutants in groundwater, soil gas, excavated soil.

The study adapts to the context of the site: former uses, activity zones, industry, transport.