Former oil waste storage sites in Brittany

Background

For more than sixty years, the Breton coastline has been affected by several major oil spills: the Torrey Canyon (1967), the Olympic Bravery (1976), the Boehlen (1976), the Amoco Cadiz (1978) and the Tanio (1980).

At the time, clean-up operations led to the creation of numerous storage sites for contaminated sediments and oil waste near the coast.

Some of these deposits were subsequently treated or removed, but several dozen sites still exist today.

Surveys carried out by the BRGM in Finistère and the Côtes-d’Armor have identified more than 160 former storage sites.

Although these studies conclude that the overall situation is reassuring, several questions remain regarding how these sites will evolve over time, particularly as a result of:

coastal erosion;
storms;
coastal retreat;
changes in coastal land use.

These phenomena may lead to the re-exposure of former storage sites or the release of residual hydrocarbons.

Why this project?

In order to improve our understanding of these ancient sites and to devvelop a decision-making tool, a PhD thesis was launched in November 2025.

This work is being carried out as part of a partnership between CEDRE and the University of Western Brittany, within the LETG laboratory (Coastal Zone – Environment – Remote Sensing – Geomatics).

The aim is to develop a method for identifying, assessing and prioritising the risks associated with former hydrocarbon waste storage sites.

Objectives

The project has several complementary objectives.

Centralising knowledge

To create a single database bringing together all available information on the historic sites identified in Brittany.

Improving understanding of risks

To supplement existing inventories through documentary and field investigations.

The analyses focus in particular on:

coastline dynamics;
coastal erosion;
current land uses;
proximity to residential areas or sensitive infrastructure;
protected natural areas
Drinking water catchments;
economic activities.

Prioritising sites

Develop a multi-criteria method to classify sites according to their level of environmental, health and territorial risk.

This prioritisation must be capable of being updated over time to take account of changes to the coastline.

A GIS-based approach

At the heart of the project lies the development of a Geographic Information System (GIS).

This tool will enable all available data to be centralised and will produce dynamic maps of the former sites.

The GIS will incorporate, in particular:

historical inventories;
environmental data;
geographical characteristics;
vulnerability levels;
field data.

This approach will facilitate the updating of knowledge and the monitoring of changing risks.

Results to support decision-makers

Beyond the scientific work, the project has a strong operational focus.

The knowledge gained should enable local authorities and government departments to manage these former sites effectively.

The aim is, in particular, to provide reliable information to:

guide intervention priorities;
anticipate risks associated with coastal changes;
define appropriate management strategies;
improve the information available to the stakeholders concerned.

Deliverables

The project will result in several complementary outputs.

A thesis manuscript

Presenting the project’s scientific findings.

A database

Compiling all available information on former storage sites.

A WebGIS

Enabling the visualisation of the sites, their characteristics and their risk levels.

Site-specific fact sheets

Intended for government departments and local authorities to facilitate decision-making.

A decision-support tool

Enabling the prioritisation of interventions and the definition of appropriate management strategies.

Better knowledge to better anticipate risks

By providing a comprehensive, evolving and updatable overview of former hydrocarbon waste storage sites in Brittany, this project will help to strengthen public sector stakeholders’ preparedness for environmental risks.

The knowledge generated will also help to improve the dissemination of objective information and facilitate the development of management policies adapted to changes in the coastline.