Location : 29410 pleyber-christ

  Initial issues

As part of a GRDF-led gas pipeline project in Pleyber-Christ (Finistère, France), the EIFFAGE Réseaux – LAGADEC Réseaux consortium was tasked with installing a DN160 HDPE gas pipe.

LAGADEC Yvon TP, responsible for one section of the project, was looking for a mechanised trenching method that could address several key priorities:

• Shorten the overall construction timeline and minimise disruption to local traffic
• Reduce trench width and excavation volumes
• Maximise reuse of excavated materials to avoid external supply
• Lower the project's environmental footprint, in line with their ongoing CSR certification process
• Improve operator safety, especially during pipe reel handling and changeovers

Solutions

Groupe Marais was selected to meet these requirements through its France Rental Division – Sector 1 Operations. A Marais GD2 offset wheel trencher was deployed, ideally suited for working along roadways closed to traffic.

The project was carried out with a carefully planned and streamlined process:

• The HDPE pipe was pre-wrapped with recycled geotextile by RDB-TP prior to installation
• All welded connections (sleeves) were prepared upstream to avoid complex handling on site
• The installation was performed directly into the trench, using a dedicated laying box mounted on the trencher
• The trenching work was completed over four days during week 12 (17–20 March 2025)

Results

The project was delivered on time with 4,000 linear meters of trenching completed within the planned schedule.

Key benefits included:

• Significant time savings thanks to the continuity of operations and advance preparation
• Improved safety, with fewer on-site handling operations and limited work at height
• Reduced excavation width, which lowered the environmental and logistical impact
• On-site reuse of materials, including screened rocky material through LAGADEC’s own valorisation platform in Pleyber-Christ
• Lower carbon footprint, in line with the company’s CSR strategy and commitment to green gas development

Equipment used

• Marais GD2 offset wheel trencher
• Laying box for wrapped HDPE pipe
• Pre-wrapped DN160 HDPE pipe with recycled geotextile
• GRDF-approved sleeve welding equipment

Client testimonial

Noël PERRIN – Operations Manager, LAGADEC Réseaux (29)

"The GRDF tender for this project was of particular interest to us due to its geographic proximity to our company and the opportunity it offered to test and refine our site procedures, especially regarding the new HDPE gas pipe wrapping techniques using geotextile.

Our knowledge of the area and its stakeholders enabled us to prepare a technical submission that was well adapted to the project requirements.

We can confidently say that this project is fully aligned with our company’s CSR commitments — we are currently undergoing certification.

The rural location was well suited to wrapped installation. We were able to unroll the HDPE pipe and install the recycled geotextile the week before trenching, preparing only a few conventional trenches for driveway crossings and an intersection.

After wrapping, we completed the connection sleeves between each reel before the MARAIS trencher passed through, equipped with a dedicated laying box.

Preparing the sleeves in advance was a real time-saver, as it significantly reduced the need for handling operations at each reel change — which can sometimes be delicate and involve working at height above the trencher. This helped us lower the accident risk on site.

We were also able to reuse materials extracted from the site, particularly by screening rocky areas and processing them at our own valorisation platform in Pleyber-Christ.

As a result, our carbon footprint was reduced. This method fits perfectly within our CSR policy, especially considering our involvement in green gas development."