NEWSROOM

In streets south of Paris, a seemingly ordinary underground construction site. And yet, every day, engineers stopped by to see quite a unique drilling operation ...

Ever see a site that just seems too busy for a crossing (or two) ?

10 June 2025

Two parallel trenchless crossings, passing under the T7 tramway, were completed last week just north of Paris’ Orly airport. Though they weren’t the longest, they weren’t the simplest either !

Auger boring under railway tracks in Normandy

5 May 2025

Despite it's relatively short length, this auger boring crossing will have a far-reaching impact, marking another important step in energy transition.

Celtic Interconnector: All trenchless works finished !

17 April 2025

The last trenchless structure for the Celtic Interconnector project has just been completed: a 126-meter-long HDD river crossing that marks the end of 15 months of intense trenchless work in Brittany.

Tarn-et-Garonne : Mission complete !!!

10 April 2025

Proud to announce the successful completion of the final 3 HDD crossings for Teréga’s 23km network extension in the Tarn-et-Garonne region of southwestern France. From feasibility studies to construction, OPTIMUM engineers have accompanied project owner Teréga at every step of the way since 2019.

CanaMarne : All AVN 1800 microtunnels are complete !

20 March 2025

The CanaMarne project is entering its final phase, the last of the AVN 1800 tunnels having been completed this week. Work on the 500-metre-long gravity flow tunnel spanned 5 weeks, with teams negotiating the complexities linked to 24-metre-deep entry shaft.

OPTIMUM Southwest : New year, new offices !

6 January 2025

As the new year rolls in, OPTIMUM is moving its business in southwest France to new offices in Toulouse. The new premises, along with a growing team, reflect OPTIMUM’s continued success and its commitment to strengthening its proximity to customers in the region’s trenchless industry.

Celtic Interconnector ; Microtunnel ? DONE !

21 December 2024

Construction of the onshore link from the coast to RTE’s converter station is in full swing. The 84-metre-long AVN 1200 microtunnel section under the River Élorn and the Paris – Brest railway is now complete and the cable ducts installed.

CanaMarne : Microtunnel Magali now complete !

5 December 2024

Having powered 835m through marl and gravel, AVN 1800 microtunnel « Magali » successfully finished tunnelling this week. This curved section is the longest and largest microtunnel in the 9km long CanaMarne project (3km microtunnel, 6km open trenches) which will improve drainage around Paris Charles de Gaulle airport by redirecting rainwater through gravity-flow tunnels to a treatment plant and then to the River Marne.

Not only multinationals are concerned by Corporate Social Responsibility (CSR)!

30 October 2024

FACT : Electronic waste makes up to 70% of toxic waste present in the environment. OPTIMUM is excited to partner up with leading construction engineering school @ESTP, by donating its recycled laptops to the @FondationESTP; the first machines were recently delivered to the school’s main campus in Cachan, near Paris.

HDD in Calais, France: there is ALWAYS a solution !

24 October 2024

Local authority Communauté d’Agglomération Grand Calais Terres & Mers is at last able to complete the missing link in the renewal of its wastewater network. The project had been on hold for several years until OPTIMUM were contacted to find a solution.

Can just one core drill really make a difference ? Yes !!!

3 October 2024

Crossing just 40 metres under SNCF rails in Montvicq (Auvergne-Rhône-Alpes) was the missing link in a 20 km project to enable RTE to connect an industrial client in central France to its network. Following initial feasibility studies, OPTIMUM advised that an additional soil investigation was needed to ensure the geology of the job site was fully appreciated. The results were THE determining factor in selecting the right trenchless technique. Auger boring with a downhole hammer delivered all the power necessary, in the limited space available, to get through the identified granite massif and rock formations under the tracks.

Tarn-et-Garonne : 3 HDDs complete, 3 more to go !

19 September 2024

Teréga continues to reinforce its gas transport network in south-eastern France and OPTIMUM trenchless engineers continue to accompany the project owner at every step. The latest project, near Montauban (Tarn-et-Garonne), will add some 23km to the network, so crossing under key infrastructure and natural obstacles was both inevitable and critical to success. Three of the HDD (horizontal directional drilling) crossings, design engineered and supervised by OPTIMUM, are now complete :

Microtunnel under France’s busiest transport links

5 September 2024

Completion this week of an important phase of RTE’s Envision project with the successful installation of a 130-metre-long microtunnel near Arras in northern France. Within the framework of the project owner’s network extension, the DN1200 microtunnel now passes under both the Paris – Lille highspeed railway tracks as well as the 6-lane A1 motorway, two of the country’s busiest transport links.

HDD works in a saturated underground environment

18 July 2024

When energy and utility networks have to be moved ahead of the construction of an urban metro line, finding space underground is definitely not easy. This was the scenario OPTIMUM engineers were faced with in 2023 when BIR commissioned the trenchless specialists to carry out feasibility studies and find potential drill paths for 2 cable installations southwest of Paris.

Microtunnel at the foot of the Pyrénées

11 July 2024

Proud to have accompanied project owner RTE for the successful completion of a new microtunnel under the River Neste at the foot of the Pyrenees in southern France. The project falls within the framework of RTE’s ongoing network renewal and extension in the region. Despite the relatively short tunnel length, the 65-metre-long, 12-metre-deep, AVN1800 microtunnel merited close monitoring, given the complex and varied geology of the area. The hard and abrasive nature of the successive alluvium, limestone, marble and granite blocks, made for challenging conditions and called for supervision by trenchless specialists.

Increasing gas pipeline security in southwest France

4 July 2024

GRTgaz’s HDD crossing under the Limoges – Angoulême railway line is now complete. The 160-metre-long construction replaces the existing pipe bridge, increasing pipeline security and enhancing the surrounding rural area.

Preparing the Seine for the Olympics

27 June 2024

The latest tunnelling project under and around the River Seine, contributing towards making it swimmable again, is now complete.

Chevalet : First phase complete

25 April 2024

Proud to announce the successful first phase of RTE’s Chevalet project, which was completed this week in northern France. The 130-metre-long, 1.5 metre wide microtunnel, carried out by EIFFAGE GENIE CIVIL RESEAUX, crosses under the A1 motorway as well as the high-speed Paris - Lille railway link. The Chevalet project, part of France’s renewable energy development programme, called for in-depth geotechnical analysis and engineering design, which was carried out by OPTIMUM from 2020 to 2022 in collaboration with RTE’s project team. OPTIMUM also accompanied RTE during the contractor selection phase and monitored the construction work, which took place between January and April 2024, ensuring all environmental, technical and regulatory constraints were respected.

Improving irrigation in southern France

18 April 2024

Working recently with SUBTERRA, on behalf of BRL, on another big water project. The construction of a 360-metre-long HDD crossing near Narbonne will enable project owner BRL to further improve the irrigation network in the Hérault department of southern France. The crossing, passing through clayey marl, was drilled diagonally under the River Orb and its wide riverbanks, down to 22 metres below the riverbed to carry a new DN 500 HDPE duct.

Trenchless workshops

2 April 2024

Delighted to have hosted key French project owners on Tuesday for the second edition of OPTIMUM’s “Trenchless Workshops” (“Les Ateliers du Sans Tranchée”). Colleagues from Enedis, RTE, Teréga and Trapil came together to discuss issues arising from their current trenchless projects, with FGA and ACA providing expert opinion and advice.

Medusa : Europe/Africa telecom corridor

28 March 2024

Great to have accompanied project owner AFR-IX over recent weeks during an HDD landfall construction for the Medusa project, which was successfully completed on Friday in Marseille, France. The 317-metre-long HDD, housing 4 x DN160 HDPE fibre optic cable ducts, will connect to the Medusa Submarine Cable System, a telecom corridor linking south European and north African countries.

HDD and marine geothermal energy

7 March 2024

Alongside Gendry as the town of La Grande Motte, on the French Mediterranean coast, advances with its innovative project to heat and cool the towns buildings using marine geothermal energy. The construction of 5 parallel 263-metre-long HDD landfalls was successfully completed last week to house 5 x DN200 HDPE ducts. Drilling through marly sands, the ducts pass under the promenade breakwater, to transport water from the system’s heat exchangers back to the sea.

8 HDD crossings to connect new data centre

1 February 2024

Proud to have accompanied RTE for the grid connection of a major new data centre southeast Paris, which was successfully completed this week. Parallel HDPE duct bundles (3 x DN225, 1 x DN110, 2 x DN75) now pass under the busy A6 motorway, access ramp and adjoining roads through 8 HDD crossings (2 x 262ml, 2 x 217ml, 2 x 183ml and 2 x 90ml) to link the data centre to RTE’s substation.

Restoring the Adour river

25 January 2024

Great to have assisted Teréga for its pipeline deviation under the Adour River, which was successfully completed in southern France last week. The project will increase pipeline durability and allow the river to be restored back to its natural state, as the existing fish passes can now be removed. The 500-metre long DN 600 HDD crossing, which replaces a surface laid pipe, passes through marl formations, drilling down 23 metres under the riverbed. Gravelly surface conditions called for a DN1200 steel casing at the entry point as well as an 8-metre excavation at the exit.

Connecting Dijon’s new datacentre

18 January 2024

Supporting project owner ENEDIS at year end for the successful completion of a 340-metre-long, fully curved, HDD to connect the newly built Fauvernay datacentre on the outskirts of Dijon. The drill path crossed clay / marl soils under the A39 motorway and the high-speed railway line between Dijon and the Swiss border. Limited access, a nearby road bridge, local housing and a 13-metre difference between the entry and exit points, called for close monitoring of drilling parameters and full-time onsite inspection.

Celtic Interconnector HDD works begin

31 December 2023

Now we’re starting ! Proud to be alongside RTE this week as the construction of the HDD landfall begins on the coast of Brittany for the 700 MW Celtic interconnector. This high-quality interconnection will link the south coast of Ireland to northern France, allowing the two countries to export / import electricity to and from each other whenever necessary, strengthening energy security. Supported by the Connecting Europe Facility (CEF) EU funding programme, this will be Ireland's first interconnection with continental Europe.

OPTIMUM in full force at JT Marseille

30 November 2023

Great to meet a wide variety of players from the energy and utility industry in Marseille on Tuesday for the FSTT’s technical day (“Les Journées Techniques”). OPTIMUM’s specialist engineers welcomed project owners as well as drilling / tunnelling contractors from all over France to discuss both current and future trenchless projects. The stand also hosted the signature of an agreement between the DCA (European Drilling Contractors Association) and the FSTT to harmonise European HDD technical guidelines.

Maintaining Abidjan’s electricity with HDD

23 November 2023

Proud to have accompanied HDI - HORIZONTAL DRILLING INTERNATIONAL for the installation of two 634m and 621m long HDD crossings under the Vridi canal in the Ivory Coast; the project is now successfully complete. Installing the cables using trenchless HDD, rather than via overhead pylons, will ensure Abidjan’s electricity supply is maintained no matter how large the ships passing through the canal to and from the newly expanded port.

Triple HDD river crossing in southern France

16 November 2023

Alongside SUBTERRA recently for the successful completion of 3 parallel 360-metre-long HDD crossings under the Gave de Pau river in southern France: a DN250 for Teréga, a DN80 and a DN50 for Arkema. Up until now, the network crossed the river via a dedicated pipe bridge. Placing it underground will ensure optimal security given the river hydrology and the geology of the site.

NeuConnect landfall works complete

30 October 2023

Alongside HDI this month for the successful completion of landfall works for the NeuConnect interconnector project. Once connected, this will create the first ever direct power link between Germany and the United Kingdom. Drilling through essentially silty clay soils, 3 parallel 420-metre-long HDD landfall crossings were completed to house DN400 HDPE ducts where the subsea cables will transition to the onshore underground cables in Kent, England.

Yeu-Noirmoutier Offshore Windfarm : problem solved

19 October 2023

No trenchless crossing is too small to benefit from the expertise of specialist engineers. Further proof of that just a few days ago as INEO’s 123-metre-long HDD was successfully completed on the French Atlantic coast, a crucial step in the connection of the Yeu - Noirmoutier Offshore Windfarm.

Another successful DCA Congress

9 October 2023

Great to be in Leipzig last week for another successful DCA Congress, where the theme was “The importance of HDD in energy transition”. Trenchless engineers, drilling contractors and suppliers from around Europe once again came together to discuss current and future industry issues and technical advances.

Appointment of Guillaume Bezombes

5 October 2023

Delighted to welcome Guillaume Bezombes who joins OPTIMUM this week as Director for southwestern France, based in our new office in Toulouse. Guillaume brings with him a wealth of experience in construction and trenchless works, including 8 years heading up one of the country’s leading drilling contractors, unparalleled technical knowledge and a thorough understanding of the distinct and complex geology of the southwest.

DN300 pipeline diversion in northern France

10 August 2023

As 6 trenchless crossings were successfully completed for a GRTgaz DN300 gas pipeline diversion in northern France recently, the importance of having trenchless expertise from a project’s outset was again apparent. The crossings pass under rivers, roads, a brownfield site, agricultural land and even a UNESCO-listed heritage railway line and range from 25m to 285m in length. As such, OPTIMUM was mandated by GRTgaz in 2021 to conduct preliminary analysis (G1 PGC) and detailed feasibility studies (G2 PRO).

Securing the Gers region’s water network

29 June 2023

Alongside SUBTERRA this month for the successful HDD installation of a 206-metre-long DN355 water pipe in Preignan, near Toulouse, in southern France, as part of the pipeline renovation programme being carried out to secure the Gers region’s water installation and distribution network.

Marine geothermal energy network extension

26 June 2023

Proud to have helped Engie complete a further network extension of project Thassalia in Marseille last week, to supply both heat and cooling to city buildings through marine geothermal energy. But just a few months ago, the question of how to cross the tramway on boulevard des Dames in the heart of the city risked derailing the project. OPTIMUM engineers were contacted and, after conducting detailed geotechnical analysis and a 3D modelling of the underground networks, proposed modifying both the crossing path and the trenchless technique. The resulting design proposal, using a large diameter traditional hand boring technique to install the 4 insulated pipes (2 x DN350 and 2 x DN300) in a DN1600 concrete microtunnel, enabled the project to move ahead.

Trenchless workshops

15 June 2023

Delighted to have welcomed some of France’s key project owners this week for the first edition of OPTIMUM’s “Trenchless Workshops” (“Les Ateliers du Sans Tranchée”). Colleagues from GRTgaz, RTE and Teréga were able to exchange ideas around themes most pertinent to their own ongoing projects, be they in the study or the execution phase.

Microtunnel Léa ready for action !

1 June 2023

Proud to accompany GRTgaz yesterday for the arrival onsite of microtunnel “Léa”, ready to start the first of two tunnels under the River Durance in southern France. Crossing a combined 1300 m under not only the river, but also a motorway ramp, protected woodland, a flood barrier and vineyards, the DN1800 will tunnel over 20m deep, to ensure the pipeline will be protected from river erosions and deviations both now and in years to come. The DN750 pipeline will continue to supply the strategic gas storage facility in Manosque, which in turn supplies gas to the whole of south-eastern France.

Completion of the longest microtunnel in France

11 May 2023

An important step on Tuesday alongside SADE, RAZEL-BEC and BESSAC for the latest in a series of initiatives in the Paris area, contributing towards making the River Seine swimmable again. Lifting out the cutting wheel marked the completion of the first phase of microtunnel construction for a stormwater collector south of the capital, in Vigneux-sur-Seine ; an AVN2500 tunnelled 981 metres under the banks of the river through limestone marl, 17 metres underground, now the longest microtunnel in France.

EOLMED offshore wind turbine project

27 April 2023

Round the clock dedication accompanying HDI on the Mediterranean coast for Friday’s successful installation of an 860-metre-long HDPE pipe for RTE’s EOLMED offshore wind turbine project. The DN400 HDD landfall will connect 3 floating turbines some 24km off the coast of Port-La-Nouvelle, near Narbonne, to the French electricity network.

International expansion

30 March 2023

Proud to see our international growth continue ! With more new projects in Italy, UK, Poland, Brazil and Ivory Coast, OPTIMUM’s trenchless expertise continues to be recognised, not only by French contractors working abroad, but directly by international clients.

Underground works at Montpellier hospital

23 March 2023

Great to have supported SADE and SCAM TP during works at Montpellier university hospital recently for both a 174m long AVN 2000 microtunnel, as well as 5 open trench sections ranging from 35m to 135m in length. OPTIMUM accompanied the engineering teams for all the underground works (trenchless as well as the conventional trench sections), enabling SADE to access a OPTIMUM’s specialist geotechnical tools and expertise for the entire project.

Parallel HDDs under the Garonne and Ariège rivers

16 February 2023

Beautiful blue skies in southern France on Friday for SUBTERRA’s successful installation of a DN300 HDD gas pipeline under the Garonne River, the second of 2 parallel 364-metre-long crossings. Crossing the Garonne was another important step in Teréga’s network renewal programme, which followed the 607-metre-long DN150 / DN300 parallel crossing under the Ariège River a few weeks ago. With a 60-metre height difference between the entry and exit points on the Ariège crossing, the job was far from straightforward. The complex geology of both sites, with significant gravel layers and in flood risk areas, required careful monitoring and casing to enhance pipe stability. OPTIMUM trenchless specialists accompanied SUBTERRA during the engineering design phase and throughout the drilling works of both crossings, determining casing characteristics and analysing drilling parameters.

HDD in the Sauternes wine region

9 February 2023

Great to have accompanied Teréga for another HDD project successfully completed this week in Sauternes. The 350-metre-long DN200 pipe passed under a protected natural area and through fractured limestone crags in the heart of the region’s vineyards. OPTIMUM engineers worked with Teréga from design and feasibility (G1 PGC, G2 PRO) and throughout the 3-week drilling operations (G4), to ensure breakouts were avoided and the agricultural land preserved.

Happy anniversary !

2 February 2023

Proud to celebrate OPTIMUM’s 5-year anniversary this week, coinciding with the completion of its 650th trenchless project. Over 120 000 linear metres of drilling/tunnelling having now designed and supervised, including 20 km of microtunnel, 30 km of landfalls and 70 crossings under railway lines. OPTIMUM engineers continue to deliver tailor-made solutions to project owners, engineering consultancies and drilling contractors to optimise operations and minimise geotechnical risks on trenchless jobsites around the globe.

Complex double microtunnel in southern France

8 December 2022

Great to have accompanied SUBTERRA during the successful completion of a complex double DN1400 microtunnel in Portet-sur-Garonne, southwestern France, linking local water treatment facilities. Site conditions, in a dense urban environment, required both tunnels to begin from one central entry pit, tunnelling first west (for 101 metres) then east (for 172 metres) under the busy RD120.

Avoiding breakouts in HDD

1 December 2022

Avoiding breakouts is one of the biggest challenges in HDD work, especially in rural and protected environments. Ensuring the drill path is adapted to both the geology of the site and the pipe being installed is key.

610m long microtunnel under the Seine

17 November 2022

Immensely proud to have accompanied BESSAC and SADE during the now completed 610-metre-long, up to 30-metre-deep, AVN2500 microtunnel crossing under the River Seine in the centre of Paris.

Railway crossing Pont VII to Sainville

27 October 2022

Proud to have accompanied RTE throughout the Pont VII to Sainville trenchless crossing, now successfully installed. Drilling the curved 240m long HDD under an SNCF freight line in a heavily congested overground and underground environment called for the highest levels of vigilance and expertise.

DCA annual congress

13 October 2022

Last week’s DCA congress, held in the UK, was a truly pan-European event and a great knowledge sharing opportunity. In the “Role of drilling mud in the borehole” workshop, facilitated by François Gandard (OPTIMUM), Marco Reinhard (LEONARD WEISS), Henning Söker (AMC EUROPE) and Krzysztof Debicki (HEADS), trenchless engineers, drilling contractors and fluid manufacturers shared expertise and discussed the importance of drilling fluid in the success of an HDD crossing.

La Ciotat, Côte d’Azur

6 October 2022

Sunny skies last week on the Côte d’Azur for the successful HDD installation of GRTgaz’s DN100 gas pipeline under the Marseille to Ventimiglia railway line in La Ciotat. Finding the right drill path was the key challenge for this project, since the crossing is in a residential area with narrow streets, an already congested underground environment and goes through tough grey and yellow sandstone.

Trenchless technology in the water sector

8 September 2022

The lack of rain in much of Europe this summer left no one in any doubt of our collective dependence on water. Weather conditions continue to focus attention on the importance of optimising water networks, whether it be for drinking water, rainwater or sanitation. Installation using trenchless techniques, notably microtunnelling, is not only increasingly appropriate but often an imperative.

Mont – Ogenne pipeline project

25 August 2022

Great to have accompanied Teréga during the extensive Mont – Ogenne project in southwest France, a key step of which was completed a few days ago thanks to great teamwork and some pretty impressive equipment !

Supporting project owners at every step

28 July 2022

• Persan : Six 175m - 200m long HDD crossings under rivers and the A16 Paris – Calais motorway • Noyales : Four 90m – 120m long HDD crossings under rivers and roads in arable / pasture land • Romainville : Six 85m – 110m long HDD crossings in a heavily built-up urban environment

International expansion

7 July 2022

OPTIMUM continues to expand its international reach with new projects in Asia, Africa and South America. Following on from the conception of 2 outfall projects off the coast of Sri Lanka, engineers recently completed the geotechnical analysis and modelling for a significant microtunnel project in Cambodia.

OPTIMUM solution for ENEDIS

16 June 2022

Proud to have made it possible this week for ENEDIS to complete the missing link in reinforcing the electricity supply in Deauville, northern France. The project had been blocked for several years until OPTIMUM were called upon to solve the problem less than 12 months ago. OPTIMUM engineers completely redesigned the trenchless project, filed a new SNCF dossier and handled negotiations to ensure all concerns were addressed and authorisations obtained to safely cross under the Lisieux to Deauville and Deauville to Cabourg railway lines, the River Touques as well as the D27A road.

HDD landfall Provence Grand Large

2 June 2022

Great to be part of another big renewables project, accompanying EDF Renouvelables during the successful installation of the HDPE duct bundle for the Provence Grand Large offshore wind turbine pilot project. The 743-metre-long HDD landfall will ultimately connect 3 “floating” turbines 17km off the coast of Port-Saint-Louis-du-Rhône, near Marseille, to the French electricity grid.

Ovale & Sens win French championships

12 May 2022

Big congratulations to Ovale & Sens who won the French adapted rugby championship this weekend in Grenoble, with a hard fought 10 – 9 win in Sunday’s final. This latest victory comes after the club was crowned Ile-de-France champions in March.

The importance of fluid confinement pressures

14 April 2022

Urban microtunnel projects must ensure that works have minimal impact on both the environment and nearby infrastructure. The importance of determining the fluid injection pressures the ground can withstand is increasingly being recognised by both project owners and drilling contractors. Using unique software and analysing the specific geotechnical conditions, OPTIMUM engineers precisely calculate these values prior to tunnelling, to minimise the risk of break outs, uplifts, and ground settlements and to ensure the smooth running of jobsite operations.

Pre-tender site visits : the G2 DCE mission

17 March 2022

Great to have accompanied RTE recently on pre-tender site visits in Le Coudray and Romainville. Indeed, visiting a site with the project owner and potential drilling / tunnelling contractors often significantly increases the quality of submissions.

Happy anniversary !

17 February 2022

Just days after its 4-year anniversary, OPTIMUM celebrates the completion of its 500th trenchless project this week, having designed and supervised over 75 000 linear metres of drilling/tunnelling, including 10 km of microtunnel, 20 km of landfalls and 50 crossings under railway lines.

Calvados offshore windfarm

6 January 2022

2021 was rounded off in great fashion as OPTIMUM accompanied RTE in the successful completion of the trenchless drilling section of the Calvados offshore windfarm project on the Normandy coast. No less than 5 dual HDD crossings, from 100m to 430m long, were drilled through Caen limestone to carry the 225 kV cables under 2 roads, a dual carriageway, a canal and the river Orne. This trenchless section is a key step in connecting the offshore wind turbines to the electricity substation.

Trenchless technology and data centres

9 December 2021

Massive investment in cloud technology and the resulting boom in data centres throughout Europe continues to increase the need for underground power supply and data transmission networks. Installation using trenchless techniques in these situations is not only increasingly appropriate but often an imperative.

DCA representative for France

2 December 2021

OPTIMUM is proud to see the appointment of François GANDARD as the representative of the DCA in France. The DCA (Drilling Contractors Association) regroups the main actors in Europe’s horizontal directional drilling market and aims to promote good practices, gather and share feedback, and organize specialized training for industry professionals.

HDD under the River Adour

26 October 2021

Another great moment this weekend, accompanying RTE during the successful installation of an HDPE duct bundle for its 63 kV cable in a fully curved 250m-long HDD project in Dax, southwest France. The HDD crossing passes under the River Adour, a river with a high water flow-rate which gives rise to frequent flooding. The environmentally sensitive nature of the area and the associated need to preserve the riverbanks, aquifers and spa water table, meant that the challenge of finding the best bore path was key to success.

DCA Congress

12 October 2021

Last week’s DCA congress in Bonn was a great knowledge sharing opportunity for Europe’s HDD professionals. During the “Subsoil parameters” workshop, led by OPTIMUM’s François Gandard, DCA Vice-President Marc Schnau and Henk Kruse from Deltares, manufacturers, engineers and contractors from around the world discussed the often-complex issue of geotechnical data analysis, as well as other subjects, such as the identification of quick clays, rock testing results and the impact a poor understanding of the bedrock can have on budgets and planning.

Microtunnel in Massy

23 September 2021

Proud to accompany EIFFAGE yesterday during the successful completion of a 130m-long DN 800 PRV microtunnel in Massy, near Paris, as part of the sanitation network diversions being put in place by the Paris Saclay local authority. The entry / exit shafts were constructed using secant pile walls in a narrow road with limited access in a densely built-up urban area. The ground conditions and inherently congested underground environment made a specialist support mission all the more important.

HDD in Lozanne

12 July 2021

Despite the grey skies, OPTIMUM was delighted to accompany GRT Gaz last week during the successful installation of its 575m-long DN100 pipeline in Lozanne, near Lyon. The HDD crossing, which drilled through basalt rock and across fault lines, passed underneath housing, an equestrian centre, a road as well as a river, which will be restored to its original state. Engineered by OPTIMUM from the outset, the project would have been impossible to complete using conventional trenched techniques.

Milestones

24 June 2021

Since its creation, OPTIMUM has worked on 4 continents, designed over 350 trenchless projects and successfully accompanied 70 trenchless jobsites. Drawing on their recognised field experience, OPTIMUM engineers continue to provide invaluable support to customers, from the design to completion of their projects.

Natural gas pipeline in Peru

3 June 2021

OPTIMUM continues to grow its portfolio of international clients in the oil and gas industry with a new contract in Peru. Acutely aware of the importance of a thorough site visit from the outset, OPTIMUM flew a trenchless specialist to Lima this week to see the context and constraints for himself.

Tender support

22 April 2021

Investing in trenchless expertise at the bidding stage not only demonstrates a contractor’s commitment to and understanding of a project, but also significantly increases the likelihood of winning the tender. OPTIMUM engineers help drilling / tunnelling contractors analyse the technical dossiers in a tender package, validate geotechnical models and add value by ensuring the most appropriate trenchless technique and tools are proposed for the job. In addition, OPTIMUM will alert the contractor to potential geotechnical and / or geological risks that may otherwise go unnoticed, allowing for contingency plans to be made ahead of time, minimising downtime and, ultimately, saving money.

Trois-Villes

8 April 2021

A beautiful sunny afternoon yesterday in the Basque country: OPTIMUM was proud to see TEREGA’s DN650 gas pipeline be successfully installed under the river Saison, near Trois-Villes. OPTIMUM accompanied TEREGA throughout the drilling works in complex geological conditions, which called for several technical modifications and dedication in abundance.

No-Dig 2021

3 March 2021

The 2021 NASTT No-Dig Show was a bit different. What remained unchanged was the breadth and quality of knowledge sharing. OPTIMUM engineers were present remotely this year, accessing over 150 conferences on topics as varied as :

Capens Pamier gas pipeline

18 February 2021

Replacing and rerouting a 50km long gas pipeline and crossing multiple train lines, rivers and motorways in the process is a project that needs expert intervention at every stage. When opinion was divided in initial road and rail studies, TERÉGA commissioned OPTIMUM to determine the most appropriate technique for several trenchless sections of the project. Given the coarse alluvium typical of southwestern France, OPTIMUM advised using a DTH hammer rather than a microtunnel, reducing the pipe dimensions from a DN1600 to a DN450 and reducing the depth of the works. OPTIMUM then reworked the project engineering accordingly, ensuring risks were minimised, especially those inherent with railway crossings.

France’s 3rd offshore wind farm takes shape

5 February 2021

After Saint Nazaire and Saint Brieux, Fécamp will soon be France’s third offshore wind farm. To this end, Rte is currently building a dual electric link ; an 18km maritime connection going underground for a further 43km onland. By 2023, the two 225 kV lines will connect the Fécamp wind farm to the Pont-Sept substation, near Le Havre on France’s north coast.

Trenchless calculations unique in France

1 December 2020

OPTIMUM’s unique trenchless calculation capacity proved invaluable on a recent HDD project for RTE under the Nantes ring road, near FC Nantes’ Beaujoire stadium. RTE wanted to reduce the drill path depth of planned HDD crossings under the ring road to limit the project’s impact on nearby municipal sports facilities. Since this would increase the risk not only of drilling fluid break outs on the ring road but also settlement levels, RTE wanted to carefully evaluate the changes before validating the new profile.

Landivisiau microtunnel

2 November 2020

Boring a 530 metre-long, 2.15 metre-wide microtunnel in one of the hardest and most abrasive rocks calls for the highest levels of vigilance. Add to that a 26-metre height difference between the entry and exit points as well as a crossing both a river and the busy Paris – Brest railway line.

Black Sea landfall

22 October 2020

OPTIMUM continues to expand its international reach with its latest mission in Romania. The 1500m long horizontal curve landfall project, which used an anchored lay barge during pull-back, will connect two natural gas fields 120kms out in the Black Sea to the inland gas treatment plant. OPTIMUM’s engineers were present in Romania for over 6 weeks and supervised HDD operations onsite 24/7 given the geotechnical complexities of the project, now one of the longest landfalls ever drilled in soft soils (sand, silt and clay).

From study to completion

8 October 2020

• Echirolles : a 65 metre-long urban pipe ramming project under the Grenoble ring road • Brioude : a 140 metre-long HDD crossing to bypass new motorway construction • Albias : 3 parallel 310 metre-long HDD crossings under the rural Aveyron river Three projects, all in complex geotechnical and / or geological environments, in which OPTIMUM teams accompanied their clients from the very beginning to the very end of their trenchless projects. These recently completed, diverse gas pipeline projects all highlight the significant advantages in having OPTIMUM’s specialist engineers at the contracting authority’s side to analyse, develop and monitor trenchless projects from their inception (feasibility studies) through to works completion (onsite drilling supervision). A perfect understanding of the project history as well as all relevant geotechnical constraints allow for decisions to be taken quickly and for technical advice and monitoring to be more pertinent, minimizing risks and optimising operations.

Réseaux VRD

7 September 2020

Understanding the full scope of a trenchless project and propose relevant solutions at every step of the way; the exhaustive article published in the latest edition of Réseaux VRD underlines the intelligence of OPTIMUM’s involvement in the Dordogne river crossing.

250 projects and counting !

22 July 2020

In just 30 months, OPTIMUM has conceived over 250 trenchless projects, examining and supervising 51 000 linear metres of crossings as well as 15 km of landfalls. Its growing team of specialist engineers reinforces the pertinence of each assignment by optimising operations, cutting drilling costs and timeframes, minimising geotechnical risks and simplifying bore paths.

BRL : Aqua Domitia project

22 June 2020

The second DN560 pipeline allowing the BRL - Aqua Domitia project to cross the River Thongue is now installed. This double 170 metre HDD crossing was drilled by Coquart & Fils, who commissioned OPTIMUM to provide geotechnical monitoring (G3 mission). As such, the engineers provided expertise at every stage to optimise the drilling process :

Technical emergency, OPTIMUM solution

18 June 2020

BIR, on behalf of Orange, has successfully pulled a DN500 HDPE tube containing 15 fibre optic lines. The technical urgency of the project arose at the end of January 2020 as the need to divert a sensitive network installed in a precarious dam became apparent.

France / UK interconnection

12 May 2020

As part of RTE’s French-UK interconnection project, the dual trenchless crossing in Frénouville is now finished. Both 140 metre-long, 10-metre-deep, HDD crossings, passing under one of Normandy's busiest rail routes, required precision control at every stage.

Rail crossing in Normandy

5 February 2020

Drilling 20m below the busiest railway in Normandy calls for the highest levels of vigilance and expertise. By accompanying RTE’s trenchless project in Harfleur on a daily basis and assisting drilling operations around the clock, OPTIMUM ensured the railway network was preserved throughout. • Continuous monitoring of drilling operations by dedicated engineers, present on site 24 hours a day. • Validation of execution documents • Enhanced security mechanisms (continuous monitoring of the rail platform and topography)

G3 missions

20 December 2019

Contracting authorities are increasingly aware of the importance of geotechnical issues in trenchless projects, leading to an more G3 missions. As such, OPTIMUM is expanding its offer to assist drilling contractors in controlling geotechnical risks and identifying possible deviations during drilling operations. Its most recent G3 contract will contribute to the extension of the hydraulic network in the Languedoc, south-west France in early 2020.

30th SNCF railway crossing

5 November 2019

This week OPTIMUM will finalize its 30th railway crossing project. These must not only integrate a “classic” trenchless study but also adhere to the strict SNCF criteria necessary for drilling authorization. They enable the complexity and the multiple risks inherent in working under railway lines to be managed proactively and effectively.

Dual pipeline crossing at Cubzac

11 October 2019

The dual gas pipeline crossing of the Dordogne at Cubzac is complete. By reworking the project engineering and assisting technical operations on a daily basis, OPTIMUM managed to halve both the drilling costs and the project timeframe.

Ovale & Sens sponsorship

3 October 2019

La qualité d’une entreprise passe aussi par ses engagements éthiques. Alors que la Coupe du Monde de Rugby se poursuit au Japon, OPTIMUM est ravi d’annoncer son parrainage de l’association Ovale & Sens, club de rugby yvelinois qui s’adresse à des adolescents et adultes, femmes et hommes, en situation de handicap mental ou psychique. Vice-champions de France du rugby adapté en 2017-2018 et vainqueur du bouclier Ile-de-France pendant la saison 2018-2019, l’équipe ne cesse de nous surprendre. Allez « Les Machines » !

Landfall expertise expands overseas

17 August 2019

OPTIMUM broadens its international scope with an AMO contract in Portugal. The landfall project, with over 600 m of horizontal directional drilling (HDD), will link an offshore wind farm to the Portuguese coast. This mission further highlights OPTIMUM's landfall expertise after other missions in France, Italy, Romania and the Reunion Island.

OPTIMUM at VST 2019

19 June 2019

How to predict the resurgence of drilling fluids ? François Gandard discussed the issue at the "HDD Forum" at the VST trade fair in Chatou, France from 18 - 19 June 2019 (lien vers PPT en pop up)

The relevance of trenchless technology

6 June 2019