Hydrokarst

What Hydrokarst does

Hydrokarst is a French specialized infrastructure services group headquartered in Sassenage (Is\u00e8re), founded in 1977 by Grenoble-based speleologists and divers, with 200+ employees operating internationally. The company delivers engineering, fabrication, and on-site execution for critical infrastructure in environments where conventional construction methods cannot be applied: dams, hydroelectric plants, ports, bridges, tunnels, and natural-risk slopes. Its core technical competencies span four difficult-access domains \u2014 rope access, subaquatic/underwater operations (including saturation diving to 200m depth via the ULIS system), confined space interventions, and hydromechanical equipment \u2014 and it is the only French firm holding the triple competence in rope, underwater, and confined space work. Through its SDEM subsidiary, Hydrokarst provides integrated EPC hydromechanical projects including gates, cofferdams, obturators, water intake grates, and penstocks, supported by in-house engineering (2D/3D modeling, finite element analysis, control-command automation).

The business model is enterprise field sales: turnkey project contracts won through tendering or direct negotiation with infrastructure owners, governments, and large engineering firms, priced on a custom quote basis per project scope. Projects range from months to multiple years (e.g., Bou Heurtma Tunisia: 4 years, Kariba Spillway, Rion-Antirion bridge: 10-year program). Revenue streams include infrastructure project services (professional services), hydromechanical equipment manufacturing and installation (hardware), and specialized technical services. Customer mix is concentrated in hydroelectric dam operators, port authorities, and government infrastructure departments across France, Europe (Switzerland, Greece), Africa (Mozambique, Zambia, Tunisia, Gabon), the Indian Ocean (R\u00e9union, Mayotte), and historically Asia (Hong Kong, Cambodia, Qatar). Since 2025, Hydrokarst has operated as part of Groupe Jarnias, the European leader in height work, following prior acquisitions of SDEM (2015), SAM (2016), TSM Perrottet/Hydrokarst Swiss (2020), and Battakarst (2021).

Name

Hydrokarst

Legal name

HYDROKARST SA

Website

https://hydrokarst.fr

Company type

Private

Founded year

1977

Operating status

Operating

Headcount range

251–500 employees

Short description

Hydrokarst is a French specialized infrastructure services firm that delivers engineering, hydromechanical equipment, and on-site execution for dams, ports, bridges, and tunnels in difficult-access environments (rope, underwater, confined space, hyperbaric), serving government and enterprise clients internationally.

Ownership category

akta.pro rank

Product category

Specialized Infrastructure Services

NAICS

Water and Sewer Line and Related Structures Construction (23711)

SIC

Water, Sewer, Pipeline, Comm & Power Line Construction (1623)

akta.pro primary industry

Hydropower Plant EPC (Dam, Run-of-River, Pumped Hydro Civil Works) (EUAEAAAD)

akta.pro secondary industries

Hydro Balance-of-Plant EPC (Penstocks, Gates, Intake/Outfall, Auxiliaries) (EUAEADAH), Hydropower EPC & Civil Construction (Dams, Weirs, Tunnels, Penstocks) (EUAMADAB), Hydropower Operations, Maintenance & Asset Management (O&M, Spares, Performance) (EUAMADAE)

Keywords

• Specialized infrastructure services
• Rope access services
• Underwater construction services
• Hydromechanical equipment manufacturing
• Confined space interventions

Headquarters

HQ city

Sassenage

HQ country

France

HQ region

Europe

Offices8 records

Markets served

GTM type

B2B

Offering type

Services

Cost components

Personnel, Operations, Infrastructure, Technology or R&D, Marketing or Sales, Supply Chain

Revenue model

1. Infrastructure Project Services: Billed as turnkey project contracts including feasibility studies, engineering, manufacturing, installation, and commissioning. Revenue recognized across project lifecycle from study phase through execution and maintenance. Projects range from months to years in duration. Pricing is custom/quote-based per project scope.
2. Hydromechanical Equipment Manufacturing and Installation: Design, fabrication, installation, and maintenance of gates, bulkheads, intake screens, obturators, penstocks, and control-command systems for dams and hydroelectric plants. Includes both new construction and rehabilitation.
3. Specialized Technical Services: Diving services, rope access work, confined space interventions, hyperbaric works, and geotechnical stabilization services billed as service contracts or incorporated into larger project contracts.

Go-to-market motion1 record

Distribution channels2 records

Marketing channels6 records

Core offering

Hydrokarst delivers specialized construction, maintenance, and rehabilitation services for critical infrastructure (dams, hydroelectric plants, ports, bridges, tunnels) in difficult-access environments using rope access, underwater/subaquatic diving, confined space, and hyperbaric dry techniques. Through its SDEM subsidiary, the company also designs, manufactures, installs, and renovates hydromechanical equipment (gates, cofferdams, penstocks, water intakes), delivering turnkey EPC projects from feasibility through commissioning.

Product overview

Hydrokarst is a specialized engineering and construction group offering complex access services in rope work, underwater operations, confined spaces, and hydromechanical equipment. The company operates six core business lines: hydraulic and port installations, SDEM hydraulic equipment (a subsidiary acquired in 2015), confined space interventions, natural risk prevention, tunnel boring machine (TBM) hyperbaric interventions, and civil engineering structures. The portfolio includes turnkey projects, engineered equipment (gates, cofferdams, shut-off devices, water intakes, penstocks), and specialized sub-services for inspection, diagnostics, and maintenance. Through its subsidiaries SDEM (hydromechanics), SAM (dam instrumentation drilling), Hydrokarst Swiss, and Battakarst (pipeline painting robotics), the company delivers integrated solutions from feasibility studies through commissioning, primarily serving hydroelectric, dam, and port infrastructure clients.

Differentiator

Problem solved

Functional benefit

Brands

• SDEM: Hydromechanical equipment design, installation and renovation subsidiary specializing in hydraulic equipment, engineering, and turnkey projects (EPC).
• Hydrokarst Swiss
• Hydrokarst Océan Indien

Products and services

• Hydraulic and Port Installations (Aménagements hydrauliques et portuaires)

Quantifiable outcome

• Diving capability at depths up to 200 meters via saturation diving (unique in France)
• +2 more outcomes

Named customers11 records

Segments5 records

Ideal customer profiles5 records

Technology focussed No

API detail

Has API

No

API docs

API detail

Core technology

AI maturity

App detail

Feature5 records

Partnerships

Six partnerships are on record, tiered core and minor.

• Groupe JarniascoreStrategic or Co-development Partner · 1 January 2025Hydrokarst joined Groupe Jarnias in 2025. Groupe Jarnias is described as the European leader in height works. This represents a significant corporate consolidation, with Hydrokarst becoming part of a larger specialized access group.
• ROCS NGEminorStrategic or Co-development Partner · 1 January 2022Hydrokarst worked in a groupement (joint venture) with ROCS NGE, specialists in underwater and difficult access work, for the Longoni port rehabilitation project in Mayotte (2022-2024). ROCS NGE contributed specialized underwater works alongside Hydrokarst's diving team of 12 scuba divers.
• VALTUBEcoreStrategic or Co-development Partner · 1 January 2021VALTUBE (manufacturer) formed a consortium with Hydrokarst Swiss (consortium leader) and SDEM (engineering) for the Zmutt dam water intake project in Switzerland (2021). VALTUBE handled fabrication of the intake structure while Hydrokarst Swiss led the consortium and SDEM provided engineering and site assembly.
• SDEM (within Hydrokarst Group)coreStrategic or Co-development Partner · 1 January 2021SDEM, acquired by Hydrokarst in 2015, provides hydromechanical engineering and manufacturing. SDEM contributed engineering studies, project follow-up, and site assembly/mounting for the Zmutt project as part of the consortium with Hydrokarst Swiss and VALTUBE.
• Zambezi River AuthoritycoreOthers · 1 January 2020The Zambezi River Authority (owned equally by Zambia and Zimbabwe) is the project owner/client for the Kariba Spillway rehabilitation project. Hydrokarst was contracted to install cofferdams and execute the rehabilitation of flood gates at Kariba Dam.
• DRAGAGE Hong KongcoreStrategic or Co-development Partner · 1 January 2015DRAGAGE Hong Kong was the project initiator/client for the Tuen Mun TBM project (2015-2017), for which Hydrokarst deployed 50 hyperbaric technicians. DRAGAGE managed the overall project while Hydrokarst provided specialized hyperbaric intervention services for TBM cutting wheel replacement and maintenance. Project value: 18 million euros.

Scale indicators8 records

Recent moves7 records

Expansion highlights5 records

Broad incumbents

• Soletanche Bachy: VINCI subsidiary specialized in foundations, ground engineering, and underground works. Comparable to Hydrokarst on the confined-space and underground works side (tunnels, deep foundations, special geotechnical interventions) but at significantly larger scale.
• Voith Hydro: Global incumbent in hydro turbine/generator supply and hydropower plant services. Overlaps with SDEM in hydromechanical scope and with Hydrokarst in plant rehabilitation, but operates as a broad incumbent across the full hydro value chain.
• Demathieu & Bard: Independent French infrastructure and civil engineering contractor. Comparable as a broad French infrastructure player that competes with Hydrokarst on dams, bridges, tunnels, and complex-access projects across France and selected international markets.
• Eiffage Génie Civil: French civil engineering division of Eiffage Group, active in dams, tunnels, ports, and large infrastructure. Comparable as a broad incumbent bidding for the same large-scale public infrastructure projects as Hydrokarst in the French and European markets.
• VINCI Construction: Major French and global infrastructure contractor (parent of Entrepose and Soletanche Bachy). Comparable as a broad incumbent competing for the same dam, port, and tunnel bids that Hydrokarst targets, albeit at much larger scale and broader portfolio.
• Bouygues Travaux Publics: French infrastructure and civil engineering arm of Bouygues Construction. Comparable as a broad incumbent on major dam, port, and tunneling projects where Hydrokarst competes, particularly in France and Francophone Africa.
• Subsea 7: Global subsea construction contractor for offshore oil & gas and renewables. Comparable on underwater installation, intervention, and seabed works, though focused on offshore rather than the inland water/port infrastructure where Hydrokarst operates.

Direct peers

• Andritz Hydro: Global supplier of hydro turbines, generators, and hydromechanical equipment. Comparable to Hydrokarst's SDEM subsidiary in scope of dam-related electromechanical equipment supply, although at much larger scale and OEM scope.
• Comex: French specialist in commercial and saturation diving for subsea and industrial projects. Hydrokarst acquired the ULIS saturation system from Comex Pro in 1998, and the two firms compete head-to-head in French and European subsea intervention work.
• Entrepose Group: French-based subsea pipelines and offshore infrastructure contractor. Comparable in delivering complex marine and underwater civil engineering projects, particularly in port and offshore environments where Hydrokarst also operates.

Market position

Strengths5 records

Weaknesses5 records

Competitive moat5 records

Key risks7 records

Key highlights7 records

Customer concentration

• YouTubeyoutube.com/user/hydrokarstcompany
• Facebookfacebook.com/Hydrokarst
• LinkedInfr.linkedin.com/company/hydrokarst-sa
• Instagraminstagram.com/hydrokarst

Compliance4 records

Revenue estimate

Valuation estimate

Number of profiles

Profiles4 records

Subsidiaries10 records

Funding overview

Funding rounds

Investors

Funding detail is available on the Subscription and Enterprise plan.Contact sales →

M&A

Investments

M&A and investment is available on the Subscription and Enterprise plan.Contact sales →

Frequently asked questions about Hydrokarst