1st Feb 2024 – 8 HDD crossings to connect new data centre

Proud to have accompanied RTE for the grid connection of a major new data centre southeast of 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.

OPTIMUM has worked on the project since its conception, from initial feasibility studies, drill path design, project engineering and contractor selection, through to supervision of all 8 HDD. Crossing the A6 presented particular constraints as the motorway lies 9 metres below the surrounding land. To ensure pipe stability and road safety over time, engineers designed a drill path dropping down to 21 metres below ground level to pass underneath it.

Given the clayey nature of the site and its inherent clogging / swelling characteristics, drilling and fluid parameters were closely monitored. OPTIMUM’s perfect understanding of the project history and geotechnical constraints allowed decisions to be taken quickly, minimizing risks and optimising operations.

Great teamwork with RTE, BIR, throughout the project ; mission accomplished.

25th Jan 2024 – Restoring the Adour river

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 25 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.

OPTIMUM engineers carried out both the feasibility study (G1 PGC) and the detailed engineering (G2 PRO). Sound geotechnical knowledge of the area ensured the project was designed to minimise impact on the natural environment at every stage, preserving the river’s fauna and flora as well as the nearby listed woods. The trenchless specialists then also monitored drilling operations throughout, keeping works running smoothly and in line with project owner Teréga’s specifications.

Congratulations to everyone involved: Teréga, Infra, SPAC, OPTIMUM

18th Jan 2024 – Connecting Dijon’s new datacentre

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.

Prior to the drilling works, ENEDIS commissioned OPTIMUM to draft tender documents for the project and to provide independent technical expertise during the drilling contractor selection process. This (G2 DCE) mission complete, the collaboration continued with a dedicated OPTIMUM engineer present onsite throughout the drilling operations.

Congratulations to everyone involved for their commitment to the project.

15th Dec 2023 – Celtic Interconnector HDD works begin

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.

The 3 parallel 440-metre-long landfalls (housing 2 x OD-355mm HDPE cable ducts and 1 x OD-250mm HDPE duct for fibre optics) will drill down 25m under the seabed, through extremely hard and abrasive granite, to ensure the cables are protected from tidal currents for years to come.

OPTIMUM specialist engineers have been supporting RTE on the Celtic interconnector project since 2018: conducting feasibility studies on potential coastal landfall sites, selecting the most appropriate site and trenchless technique, as well as providing technical expertise during the contractor selector phase. They will now accompany RTE throughout the operational phase of the landfall project.

Great to be part of another trenchless first ! Thanks to colleagues from CIDAC and Rte for the great teamwork so far.

30th Nov 2023 – Strong presence in Marseille

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.

In the conference sessions, Alexandre Cambier and Théo Millet, alongside Marilyn Bennet (GRTgaz), Sylvain Cozzolino (GRTgaz) and Baptiste Cornelissen (SADE), provided insights into the ongoing microtunnel crossing of the River Durance. Two microtunnels, currently in progress, will cross a total of 1300m under the river, a motorway ramp, protected woodland, a flood barrier, and vineyards, to supply the strategic gas storage facility in Manosque, which in turn supplies gas to the whole of south-eastern France.

In addition, Modvenn Sili, in collaboration with Alcyme Rambaud (HDI), presented the EolMed offshore wind turbine project. The DN400 HDD landfall, completed earlier this year, will connect 3 floating turbines off the Mediterranean coast to the French electricity network.

23rd Nov 2023 – Maintaining Adidjan’s electricity with HDD

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.

Drilling through the coastal sands and brackish groundwater called for careful monitoring of drilling parameters and fluid. Thanks to good local knowledge, OPTIMUM established the geotechnical model, validated the HDD design, and conducted breakout mitigation modelling before works began. A dedicated engineer then headed to Abidjan to support onsite teams during the critical pilot hole drilling operations.

Great team work !

16th Nov 2023 – Triple HDD river crossing in southern France

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.

OPTIMUM engineers worked on both the design and the construction phase of the Gave de Pau project. The drilling profiles for the 3 pipelines were adjusted to almost 30 metres deep to avoid localised gravel formations that had been identified during the geotechnical investigations. With surface gravel over 3 metres deep, steel casings were installed at all three entry points and the exit points were excavated to mitigate against the risk of hole collapse. Drilling logs were monitored remotely throughout the construction phase and trenchless specialists followed key stages onsite, ensuring the combined 1km+ HDD construction ran smoothly.

Congratulations to all the teams involved.

30th Oct 2023 – NeuConnect landfall works complete

Alongside HDI this month for the successful completion of the UK 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.

HDI commissioned OPTIMUM to support them with the landfall on the UK side both before and during the drilling operations: definition of a geotechnical base model, hydrofracture analysis modelling, as well as validation / adjustment of working methods, drilling tools and risk mitigation procedures. Ballast calculations ahead of time minimised pipe/ground friction, ensuring the integrity and longevity of the installation. OPTIMUM engineers then carried out a G3 mission, monitoring the HDD works both remotely and onsite.

Great to be part of another trenchless first.

19th Oct 2023 – Yeu-Noirmoutier Offshore Windfarm : problem solved

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.

The connection project was in difficulty until OPTIMUM was called upon to solve the problem on this particular section. Trenchless specialists ran targeted and more appropriate geotechnical investigations and conducted a risk analysis to ensure complete understanding of the job site’s complex geology, notably the monogranular sands, liquefaction potential and underlying brackish water table.

OPTIMUM engineers then redesigned the project, whilst sticking to the client’s key constraints, namely an HDD running along the same drill path, passing under a road and a canal. Rather than one large bundle, the crossing was reconfigured into 2 sets of 4 parallel drills, allowing the reaming diameters to be reduced, which in turn reduced the risk of hole collapse.

Proud to have enabled INEO to advance on another renewables project; mission accomplished.

9th Oct 2023 – Another successful DCA Congress

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 fluid manufacturers from around Europe once again came together to discuss current and future industry issues and technical advances.

Of note was Maxime Aera (OPTIMUM) and Carsten Brueckner’s (BM Drilling) presentation of the record-breaking Chira River HDD project in Peru, which detailed how the team overcame environmental constraints as well as the specific challenges of completing 2 x 2000m crossings in soft soil conditions to successfully finish the project ahead of schedule.

It was great to meet with colleagues from countries that were underrepresented until now, including France. This increasingly popular annual event really is a unique pan-European knowledge sharing opportunity.

Looking forward to next year in Barcelona !

5th Oct 2023 – Appointment of Guillaume Bezombes

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. This new appointment will allow OPTIMUM to support yet more customers in the region with the specific expertise they need to ensure trenchless projects run smoothly, to time and budget.

10th Aug 2023 – DN300 pipeline diversion in northern France

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)..

Trenchless specialists designed 3 HDD and 3 auger boring crossings, each one tailored to give the best technico-economic solution whilst preserving the existing structures as well as the activity of the rural and peri-rural environment. The designs were followed, with each drilling operation running smoothly, to time and budget.

29th Jun 2023 – Securing the Gers region’s water network

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.

The new HDPE pipes cross under SNCF railway tracks, an A road as well as housing, and are better suited to the risk of shrinkage and swelling inherent to the site’s clayey marl soils than the previous steel ones.

OPTIMUM trenchless specialists worked with SUBTERRA prior to the drilling works to validate the project engineering, design the crossing plans and carry out ground settlement analysis. They then accompanied SUBTERRA throughout the construction phase to advise on necessary adaptations as drilling progressed: profile adjustment, tool modification, etc.).

Great teamwork throughout, sticking to both the timeframe and the budget.

26th Jun 2023 – Marine geothermal energy network extension

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..

Having an in-depth understanding of the project and having designed the crossing, OPTIMUM then monitored the onsite works every day throughout construction in this highly congested underground environment. Despite the extremely varied and complex geology as well as a multitude of other networks, the crossing was completed without impacting on any of the existing structures.

Congratulations to everyone involved for their dedication.

15th Jun 2023 – Trenchless workshops

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.

These biannual workshops allow for joint reflection on current trenchless issues and promote technical exchanges between project owners. It was great to see such participant engagement and fruitful discussion, which will enable France’s trenchless industry to progress at every level.

A big “thank-you” to everyone who took part.

1st Jun 2023 – Microtunnel Léa ready for action !

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.

OPTIMUM engineers have been supporting GRTgaz on this project since its inception in 2019, with feasibility studies, engineering design, as well as during the purchasing and contractor selector phase. Their specialist knowledge enabled a safe and workable trenchless solution to be found despite the site’s numerous constraints and complex geological conditions.

A great project to be involved ; can’t wait to get started on this next phase !

11th May 2023 – Completion of the longest microtunnel in France

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.

Accompanying the works contractors directly with a G3 mission, OPTIMUM engineers conducted geotechnical investigations and analysis ahead of time and also provided onsite support throughout the 6-month tunnelling operations. Close monitoring of tunnelling parameters, drilling fluids, cutting face pressure and tunnel frictions ensured that construction of the gravity-flow tunnel ran smoothly. Phase two of the project will start from the same central entry pit, this time passing under the riverbank and following the course of the Seine, before exiting in urban Athis-Mons.

Project owner : SIAAP, the greater Paris Sanitation Authority

Construction contractors : SADE, RAZEL-BEC, BESSAC

27th Apr 2023 – EOLMED offshore wind turbine project

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.

OPTIMUM trenchless engineers provided geotechnical analysis prior to construction, as well as daily monitoring and support onsite during the works to optimise drilling operations.

This mission further highlights OPTIMUM's landfall expertise after numerous other missions around Europe and South America.

Thanks to HDI for the great teamwork and the chance to be part of another exciting renewables project.

30th Mar 2023 – International expansion

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.

After working on the trenchless design for two sizeable gas pipeline crossings on the Italian Adriatic coast as well as specific calculations for an offshore wind farm landfall in the UK, engineers are now focused on supporting an HDD shore approach off the southern Brazilian coast, before heading to Côte d'Ivoire for an HDD project installation.

23rd Mar 2023 – Underground works at Montpellier hospital

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.

The nature of the works, to create a rainwater collector in the heart of the busy hospital complex, called for meticulous planning both prior to and during construction. OPTIMUM’s engineers conducted geotechnical analysis, microtunnel engineering design, risk modelling, as well as slope stability analysis, using dedicated geotechnical software.

Congratulations to all involved on this important project.

16th Feb 2023 – Parallel HDDs under the Garonne and Ariège rivers

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.

Congratulations to everyone involved ; great teamwork !

9th Feb 2023 – HDD in the Sauterne wine region

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.

Mission accomplished, on time and on budget.

2nd Feb 2023 – Happy anniversary !

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.

Here’s to the next 5 years !

8th Dec 2022 – Complex double microtunnel in southern France

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.

The extremely varied geological formations encountered (clay, gravel, stony soil) called for the highest levels of care; OPTIMUM engineers accompanied SUBTERRA throughout the works to continuously monitor the tunnelling parameters and geotechnical conditions. This allowed any discrepancies to be identified quickly and ensured that corrective measures were put in place straight away.

Congratulations to all involved for their commitment and teamwork

1st Dec 2022 – Avoiding breakouts in HDD

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.

OPTIMUM engineers model ground behaviour before works begin to minimise break out risks and to ensure drilling operations run smoothly.

More explanation here in a new 3D animation.

17th Nov 2022 – 610m long microtunnel under the Seine

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.

In a complex geological environment, the gravity-flow tunnel had to cross not only the river, but also under the metro line 5 viaduct, metro line 10, as well as train line RER C.

Before the works began, OPTIMUM engineers analysed the 10-layer geology and precisely defined the tunnelling parameters given the numerous constraints and complexity of the site. During the 3-month-long tunnelling operation, OPTIMUM continuously monitored tunnelling logs and ensured trenchless specialists were available to be despatched onsite whenever necessary to provide expertise.

Congratulations to all the teams involved for their dedication in making the project happen :

  • Groupement Impluvium : Urbaine de Travaux / BESSAC / SADE TS / Soletanche-Bachy / Sefi-Intrafor
  • Project owner : Mairie de Paris
  • Implementation : Artelia / Icaruss / Terrassol

27th Oct 2022 – Railway crossing Pont VII to Sainville

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.

OPTIMUM worked with RTE during the entire project: from design (G1 PGC, G2 AVP, G2 PRO), to drilling contractor selection (G2 DCE), and finally for the 24h/24h drilling operations (G4), monitoring works around the clock.

Great teamwork with RTE, Bouygues Energies Services, Huré Canalisations, Lynx+ and Arkogeos, ensured that drilling was completed in just one week, limiting the impact on the railway network.

The project is now complete; a great challenge, successfully met.

13th Oct 2022 – DCA annual congress

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.

Thanks to their jobsite experience, facilitators were also able to provide participants with concrete examples of how to measure, adjust and monitor drilling fluid parameters onsite.

6th Oct 2022 – La Ciotat, Côte d’Azur

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. OPTIMUM mobilised both geological and civil engineers from the outset, from feasibility to works completion, to ensure GRTgaz could safely install the pipe with minimal risk to infrastructure and the rail network.

Job done, on time and on budget. Congratulations to all the teams involved : Gendry, BESSAC-TPC, Sixense

8th Sept 2022 – Trenchless technology in the water sector

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.

Currently working on numerous water projects, OPTIMUM engineers continue to support municipalities, project owners and tunnelling / drilling contractors with the challenge of finding the best bore path and the most appropriate engineering for these sizeable structures, often in congested underground urban environments.

25th Aug 2022 - Mont - Ogenne pipeline project

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 !

Finished crossings include :

  • Two parallel 500-metre-long HDD crossings, DN160 and DN650, under the Gave de Pau river, each using a double intersect to ensure hole stability in the gravelly ground conditions
  • A fully curved 150-metre-long AVN1200 microtunnel under the Luzoué river
  • Four additional auger boring crossings under rivers and roads

Optimum provided specialist trenchless support for all the crossings, from project conception and engineering design, through soil investigations, to works supervision and monitoring for the duration of the drilling / tunnelling, allowing the project to be completed on time and on budget.

Congratulations to the teams from Teréga, Denys, Catalana de Perforacions and Jamme Kleber for this great achievement.

28th Jul 2022 - Supporting project owners at every step

  • 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

Even for relatively short trenchless crossings, support from specialist engineers is key. OPTIMUM has accompanied RTE in these three projects from A to Z ; initial feasibility studies, choice of drill path and project design, evaluation and selection of the drilling contractor, through to supervision of the drilling works.

OPTIMUM’s perfect understanding of the project history and geotechnical constraints allows for decisions to be taken quickly and for technical advice and monitoring to be more pertinent, minimizing risks and optimising operations.

7th Jul 2022 - International expansion

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.
Our engineers are now focused on the design of a combined lake and river trenchless crossing in Abidjan, Ivory Coast, as well as detailed feasibility studies for a major HDD project in northern Chile.
It's great to see OPTIMUM’s technical expertise being increasingly recognised and sought after, not only by French companies working abroad, but also directly by international clients.

30th Jun 2022 – Minifilm 4 : Assisting works contractors

OPTIMUM is happy to share the latest in its series of minifilms, this time about the G3 mission. Having specialist trenchless engineers assist works contractors before and during project execution ensures the best results during drilling / tunnelling.

16th Jun 2022 – OPTIMUM solution for ENEDIS

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.
OPTIMUM then supervised drilling operations 24h/24h during the construction of 2 parallel 150-metre-long HDD crossings, successfully executed by FNO, as well as continuous monitoring of both the rail platform (by ARKOGEOS) and the topography (by Lynx+). ENEDIS can now install and connect its cables to the grid.
Mission accomplished thanks to great teamwork with ENEDIS, SNCF, FNO, LYNX +, ARKOGEOS and DR.

2nd Jun 2022 – HDD landfall Provence Grand Large

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.
Prior to construction, OPTIMUM supported the PGL project team by optimising onshore and offshore geotechnical investigations, modelling, and validating the trenchless engineering hypotheses.
OPTIMUM’s specialist engineers then supervised HDD operations onsite for the duration of the works, continuously monitoring drilling parameters, validating the drill path and providing compliance control.
Thanks to EDF Renouvelables / Provence Grand Large and HDI for the excellent cooperation and teamwork.

12th May 2022 – Ovale & Sens win French championships

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.
OPTIMUM is proud to support parasport and congratulates MLSGP rugby club who opened Ovale & Sens for teenagers and adults with mental health issues, men and women alike, over 10 years ago.
The players are impressive in every sense. Bravo !

14th Apr 2022 – Fluid injection pressures : 3D animation

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.
More explanation here in the first of OPTIMUM’s 3D animation series.

17th Mar 2022 – Pre-tender site visits : G2 DCE mission

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.
OPTIMUM’s specialist engineers regularly accompany project owners on these visits, as part of the G2 DCE mission, to discuss site constraints, job site configuration and trenchless specifications with the works contractors. Facilitating a common understanding of both the technical requirements and the philosophy of the project at this early stage ensures that the right questions are asked on all sides, increasing the relevance of the tender bids and, ultimately, the efficiently of the drilling / tunnelling operations.

17th Feb 2022 – Happy anniversary !

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.
OPTIMUM’s ever-growing team of engineers continues to provide invaluable support to project owners, engineering consultancies and drilling contractors to optimise operations and minimise geotechnical risks on trenchless jobsites around France and beyond.
Here’s to the next 500 !
Join the team : https://www.optimum-te.fr/recrutement/

6th Jan 2022 – Calvados offshore windfarm

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.
OPTIMUM engineers reviewed the operating methods of each of the 3 drilling contractors involved, BIR, COQUART & FILS and FNO, and then supported RTE with a G4 works supervision mission throughout the 10-month-long drilling operations.
Many thanks to RTE for the opportunity to be part of another big renewables project and to the drilling contractors for their valuable cooperation over the past year.

9th Dec 2021 – Trenchless technology and data centres

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.
Currently working on a new data centre project in the north of Paris, OPTIMUM engineers continue to support key energy / utility sector customers with the challenge of finding the best bore path in these congested underground urban environments.

2nd Dec 2021 – DCA representative for France

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.
François’ appointment will allow French drilling contractors and companies to access the DCA’s information sharing opportunities and to have their say within the association.

26th Oct 2021 – HDD under the Adour

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 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.
Working with RTE over the last 36 months, OPTIMUM has provided trenchless expertise from the outset, from feasibility and engineering design (G1 PGC, G2 PRO), through the tender and purchasing phase (G2 DCE), right through to works supervision (G4) and completion this week, allowing RTE to finish the bore path on budget.

12th Oct 2021 – DCA Congress

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. It was great to see such participant engagement and lively debate, which enables Europe’s HDD industry to progress at every level.
Thanks to everyone who took part.

23rd Sept 2021 - Microtunnel in Massy

OPTIMUM is proud to have accompanied 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. OPTIMUM accompanied Eiffage during the project development phase to establish the initial engineering hypotheses and then throughout the works phase,
to continuously monitor the tunnelling parametres and the geotechnical conditions.
This allowed any discrepancies to be identified and ensured that corrective measures were put in place straight away.
Mission accomplished : congratulations to Eiffage for the project execution and the great teamwork.

12 July 2021 – HDD in Lozanne

Despite the grey skies, OPTIMUM was delighted to accompany GRTgaz 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. Engineered by OPTIMUM from the outset, the project would have been impossible to complete using conventional trenched techniques.
OPTIMUM accompanied GRTgaz from A to Z, from the feasibility studies (G1 PGC, G2 PRO), through the soil investigations (G2 AVP), the purchasing and tender assistance (G2 DCE),
Project completed on time and on budget ; great team work throughout

24th Jun – Milestones

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.

3rd Jun 2021 - Natural gas pipeline in Peru

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.
The project, a 2000m Horizontal Directional Drilling (HDD) crossing under a vast river delta in the north of Peru, will form part of a new natural gas pipeline being installed within the framework of the country’s energy transition policy.
OPTIMUM engineers will now monitor the geotechnical and geophysical investigations, draft the method statement and design the drilling profile. Given the jobsite environment and the potential for surface breakouts, specific modelling and hydrofracture analysis will also be conducted to mitigate risks and ensure smoother drilling operations.

22nd Apr 2021 – Tender Support

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.
In recent months, OPTIMUM has helped contractors not only in France, but also in Italy and South America to develop successful bids for trenchless projects. Great return on their investment !

8th Apr 2021 – Trois-Villes

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.

Congratulations to the teams from HDI and SPIECAPAG for this great achievement.

31st Mar 2021 – No-Dig 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 :

  • the design challenges in curved microtunnel shore landings
  • the mathematics of pilot hole drilling
  • matrix development for quality assurance, inspection, and risk management during construction
  • hydraulic fracture risks in sedimentary rock formations
  • HDD river crossings in seismic activity zones

As the world’s largest trenchless technology trade fair and conference, the No-Dig Show provides a wealth of technical insight. By participating every year, OPTIMUM ensures its engineers can support clients by integrating best practise and key analysis at every stage of their trenchless projects.

18th Feb 2021 - Capens Pamier gas pipeline

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, TEREGA 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. Reassured by OPTIMUM’s approach and expertise
TEREGA then also commissioned them to supervise onsite operations for 6 crossings (2 x rail, 2 x river, 2 x road) ; just 12 months later, these crossings are now complete.
Finding the best solution for every project, without any preconceptions, is how OPTIMUM were able to help TEREGA reduce the project timeframe significantly and divide the initial drilling cost estimate by 4.

5th Feb 2021 - France’s 3rd offshore wind farm

After Saint Nazaire and Saint Brieuc, 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.
In 2019, RTE had already commissioned OPTIMUM to project manage the preparation and monitoring of a railway crossing further along the drill path. A year later, OPTIMUM continues to supervise operations, this time for the whole underground link. Together with axe ingénierie, the two companies supervise the land-side works in their entirety for RTE: OPTIMUM for the trenchless sections and axe ingénierie for the conventional pipe laying.
In this way, all RTE's needs can be met for the supervision of the underground power line construction.

1st Dec 2020 - Trenchless calculations unique in France

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.
OPTIMUM, which had already carried out G1 PGC and G2 PRO studies for the two drills, reworked the geotechnical model and simulated soil resistance / drilling pressure whilst also evaluating the surface settlement by finite elements, a combination that only OPTIMUM offers in France.
The calculations confirmed the feasibility of the drill path change ; RTE was able to go ahead, entrusting drilling to Groupe Gendry, which completed the project without any impact to the ring road ; mission accomplished.

2nd Nov 2020 - Landivisiau microtunnel

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 a river and the Paris – Brest railway lines.
The extreme complexity of the gas pipe project in Brittany called for expert advice and hands-on assistance both prior to and during microtunnelling operations. Contracted by SADE TS, OPTIMUM engineers reworked the geotechnical aspects of the project to ensure complete alignment with geological conditions onsite. Daily monitoring of the boring operations allowed for progress rates to be maintained and safeguarded against technical risks such as tunnel narrowing, fluid dispersion or excessive wear on the cutting tools.
The microtunnel is now complete, excellent teamwork throughout.

22nd October 2020 - Black Sea landfall

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).
OPTIMUM has been involved in this project since 2018 at the request of the contractor, Black Sea Oil & Gas, providing technical expertise to support the engineering and project preparation teams.

8th October 2020 - From study to drilling completion

  • 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.
Three technical challenges, three projects successes.

7th Sept 2020 - Réseaux VRD

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

22nd July 2020 - 250 projects and counting !

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.
Despite the current climate, OPTIMUM continues to support its customers on trenchless jobsites throughout France, and beyond, further consolidating its position as THE trenchless engineering expert in the French market. Here’s to the next 250 !

22th June 2020 - BRL : Aqua Domitia project

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 :

  • During site preparation : geotechnical dossier analysis and definition of a programme of additional investigations to finalise engineering plans
  • During drilling of the first pilot hole : deepening the HDD profile following observation of a geological deviation causing drilling fluid losses
  • During boring : optimization of the boring sequence

Effective teamwork, based on mutual trust, once again led to a great result.

18th June 2020 - Technical emergency, OPTIMUM solution

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.
OPTIMUM mobilized teams to deliver a complete engineering study, from determining the bore path to supervising the geotechnical surveys and sizing the final tunnelling works, all in a record 4 months and during the Coronavirus crisis.
Despite the urban location and the considerable environmental challenges, the team completed this fully curved, 185-metre-long HDD crossing, on time and on budget.

12th May 2020 - France / UK interconnection

As part of RTE’s French-UK interconnection project, the dual trenchless crossing in Frénouville is now finished. Both of the 140 metre-long, 10 metre-deep HDD crossings, passing under one of Normandy's busiest rail routes, required precision control at every stage.
OPTIMUM assigned specialist engineers from the document validation phase through to works completion, ensuring round the clock monitoring on site, day and night.
Finalised in April 2020, the project was not only completed on time and in compliance with strict SNCF requirements, but also whilst preserving the health and safety of the dedicated engineers who worked despite the Covid-19 pandemic.

5th February 2020 - Rail crossing in Normandy

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. The enhanced security mechanisms put in place (including continuous monitoring of the rail platform, topographic controls before, during and after drilling), coupled with the expertise of the dedicated project engineers enabled this curved,260m long HDD crossing to be drilled on time, despite adverse geotechnical conditions. The crossing is now complete; a great challenge, successfully met.

20th December 2019 - G3 Missions

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.

5th November 2019 - 30th SNCF railway crossing

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.
Subsequently, OPTIMUM is also able to monitor and control the drilling operations, in line with the SNCF stipulation that this be delegated by the contracting authority to an independent, specialist project manager.

11th Oct 2019 – Dual pipeline crossing at Cubzac

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.
We are proud to have been able to support Coquart & Fils in this great achievement, now its longest ever directional drilling project (2x850m). Great teamwork

3rd Oct 2019 – Ovale & Sens sponsorship

Sponsorship choices speak volumes about a company’s ethics. As the Rugby World Cup continues in Japan, OPTIMUM is delighted to announce its sponsorship of Ovale & Sens, a rugby club near Paris open to teenagers and adults, men and women alike, with mental health issues.
Runners up in the French adapted rugby championship in 2017-2018 and winner of the Ile-de-France shield during the 2018-2019 season, the team never ceases to amaze us. Bravo !

17th August 2019 - Landfall expertise expands overseas

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.

Comment prévoir les résurgences

19th June 2019 - OPTIMUM at VST 2019

How to predict the resurgence of drilling fluids ?
François Gandard discusses the issue at the "HDD Forum" at the VST trade fair in Chatou, France from 18 - 19 June 2019. The crossing is now complete; a great challenge, successfully met.

6th June 2019 - Ingénierie Territoriale

The trenchless technology focus dossier in this month’s edition of Ingénierie Territoriale reinforces the relevance of these techniques in today’s congested environment Good preparation is the key to success,
OPTIMUM’s analytical method is detailed at the front of the dossier.