Buried Network

Buried pipes are subject to mechanical strain due to the weight of the ground and possible wheel loading when laid under an area where traffic circulates.

Itinero® and Global Plus® range pipe systems can be used for underground applications in contact with most soils*.

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Pam Building’s underground piping solutions are designed for high-performance applications in contact with various soil conditions.

Each buried pipe faces pressure from ground weight, potential traffic above, and the environmental context. The mechanical behaviour of the pipe/soil system depends on pipe rigidity or flexibility, and the chosen installation techniques.

The mechanical performance of these pipelines is defined through advanced analysis and methods tailored to each project.

Key design factors include the depth and dimensions of the trenches, soil compaction, and pipe behavior. All systems comply with the EN 1610 code on the construction and testing of drains and sewers.

Installation parameters are defined according to:

• Soil type and structure

• Quality of embedment compaction

• Behavior of the rigid steel pipe or plastic piping

• Presence or absence of wheel loads

• Specific field conditions such as groundwater level

Backfilling recommendations for rigid pipes (DN 100–DN 300) are based on EN 1610 guidelines, using the most demanding hypothesis. These methods, developed through extensive industrial experience, help preserve pipeline integrity by minimizing soil shifts and structural stress.

These solutions make full use of cast iron’s strength, allowing deeper cover even under traffic loads. When native soil is removed and replaced with controlled material, long-term durability increases and damage risk to the environment decreases.

For corrosion resistance, especially in aggressive soils, it is recommended to use additional protection such as liquid epoxy coatings or polyethylene sleeves. These solutions are effective against low-resistivity soils, low pH, and organic or industrial contamination.

Dimensions are in mm.

* Detrimental materials = stones, tree roots, rubbish, organic material, clay lumps (>75 mm), snow and ice.

* The nature of the soil in contact with the network must be homogeneous. For aggressive soils, it is recommended to use additional protection such as polyethylene couplings or other types of appropriate external coating, particularly when the nature of the soil is as follows:

• with low resistivity, less than 1,500 cm above the water table or less than 2,500 cm below ;

• with a low pH of less than 6 ;

• contaminated by organic or industrial effluents or waste.

Based on our experience in buried pipe systems and the French origin of our company, we have applied the French Fascicule 70 calculation model (recommendations for sewage pipe systems according to the pipe material).

The table below gives values for depths of cover according to the Fascicule 70 calculation, considering rigid pipes.

^{**Does not take into account the frost-free arrangements}

^{(1) The calculation allows shallower depth of cover, but this figure includes a safety margin / ground surface proximity and related hazards}

• Maintain clearance between pipe welds and bedding (EN 1610 §8.5.4)

• Perform system tightness tests (EN 1610 §13)

• Use netting for pipe identification

• Ensure local or national regulations are not violated

• Advanced inspection methods and failure analysis processes are also required before backfilling is finalized.

For any other case, other diameters or buried systems under the bottom slab, please contact our technical support team: tc@pambuilding.com - Tel:+33 (0)3 66 88 19 47.

When setting the pipe system in concrete, at least 2.5 cm of separation on each side is required. Concrete shrinkage and carbonation impose heavy stress, which may increase risks. Installing compressible joints mitigates bending effects and conforms to best industrial practice.

Importantly, the pipe system should not be in contact with the concrete's metal reinforcements.

Final surrounding should only occur after full testing and inspection.