OS35 Specialised works categories

SOA category OS35

Low environmental impact works

Requirement: Skilled workers holding the appropriate licence

OS35 covers low environmental impact works: “trenchless” or “no-dig” technologies that make it possible to lay, replace or rehabilitate pipes and cable ducts without digging trenches. It includes horizontal directional drilling (HDD), microtunnelling, pipe rehabilitation with CIPP, CCTV inspection of networks and micro-trenching for fibre. It is strategic for fibre optics and for the rehabilitation of water and sewer networks.

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OS35 types: horizontal directional drilling (HDD), shield microtunnelling, CIPP rehabilitation of existing networks

SOA certification OS35: areas of application

OS35 brings together technologies that work underground without opening up roads and pavements. The main sectors:

Horizontal directional drilling (HDD): crossing roads, railways and rivers without interrupting traffic. It is the leading technology for large fibre networks.
Microtunnelling: small tunnels, from 30 cm to 4 metres, for large-diameter sewers and water mains.
CIPP rehabilitation: a resin-impregnated liner, cured inside the old pipe, creates a new pipe without digging.
Pipe bursting and slip-lining: replacement of existing pipes by bursting them or inserting a new pipe inside.
CCTV inspection: camera robots that inspect sewers and water mains from the inside and map faults.
Micro-trenching: trenches a few centimetres wide for laying fibre optics in cities.
Spot repairs: robots that enter the pipe and repair only the damaged point.
Working shafts: launch and reception shafts and other underground access works.

In short: OS35 is the category of “underground surgery”, among the qualifications set to grow most in the coming years.

Diagram of horizontal directional drilling (HDD) to cross a watercourse without disturbing the surface or the environment

SOA categories related to OS35

OS19

Telecommunication and data transmission network systems

is the natural partner in fibre optics: OS35 lays the cable ducts, OS19 the fibre and equipment. Together they offer a complete service.

OS21

Special structural works

carries out foundations and consolidation; OS35 linear works such as pipes and cable ducts. They share equipment and staff.

OG6

Water mains, gas pipelines, oil pipelines, irrigation and drainage works

is the prevailing category in large water networks; OS35 comes in as a separable category for trenchless sections.

OG3

Roads, motorways, bridges, viaducts, railways

is the prevailing category in road and railway contracts; OS35 is needed to cross them without closing traffic.

OS22

Water treatment and purification plants

builds treatment plants; OS35 rehabilitates and connects the upstream sewer network.

OS20-B

Geognostic surveys

carries out the subsoil surveys required before a long drilling.

OS14

Waste disposal and recovery plants

handles the disposal of sludge and materials produced by rehabilitation works.

CIPP rehabilitation: a resin-impregnated fibre liner is cured inside the existing pipe, restoring its functionality and tightness

Why it pays to qualify in OS35

The OS35 has two major waves of investment ahead of it:
· widespread fibre optics, with the Italia 1 Giga, 5G, Connected Schools and Connected Healthcare plans;
· the rehabilitation of water and sewer networks, with 900 million just to reduce leaks from water mains.

If you work with HDD, microtunnelling, CIPP, CCTV inspection or micro-trenching, OS35 provides you with access to fibre-optic tenders and utility tenders for water networks.

SOA category OS35: frequently asked questions

Download PDF technical data sheets

What is the official description of category OS35?

OS35 “concerns the construction and maintenance of any underground work using non-invasive excavation technologies. It includes, by way of example, guided and unguided horizontal drilling, with the possible reuse and exploitation of existing works, as well as the use of CCTV inspection, rehabilitation, renewal and replacement technologies for underground substructures or technologies for shallow mini-excavations.”. The description was extended precisely to clarify that CIPP, CCTV inspection and shallow mini-excavations fall fully within the category.

What do “trenchless” and “no-dig” mean?

They are the international terms for technologies that build, replace or rehabilitate underground works without open-cut excavation.

What is the difference from OS21 and OG6?

OS21 covers foundations, piles and consolidation. OG6 covers water and gas networks built with traditional excavation. OS35 covers underground works built without excavation.

What exactly is CIPP?

A resin-impregnated fibre liner is inserted into the existing pipe and cured in place with steam, hot water or UV light. The result is a new pipe inside the old one.

Which works count as CEL for OS35?

HDD drilling, microtunnelling, CIPP rehabilitation, slip-lining and pipe bursting, CCTV inspections, micro-trenching and robotic repairs.

Is there a licence for OS35 operators?

Yes, for CIPP.

Your next move?

Demonstrate your requirements and turn this knowledge into action: make sure you have the right SOA qualification and don’t hesitate to invest in training and innovation.