Areas of operation

Subsea Tech inspects dams and hydraulic structures with its own vehicles, designed and built in-house for the job. We inspect dam faces, water intakes, bottom outlets, gates and canals, both underwater and above water, and pinpoint the exact location of every defect.

Tractebel · Côte d'Ivoire · 2025 & 2026

Six hydropower schemes in Côte d’Ivoire: Ayamé I and II, Taabo, Fayé, Kossou and Buyo

Structure

Concrete, earthfill and rockfill dams commissioned between 1959 and 1983. Inspection of water intakes and their trash racks, stoplog slots, bottom outlets, spillways, downstream outlets and upstream faces. Depending on the site, visibility ranged from under 5 cm to 50 cm.

Equipment

Two Guardian micro-ROVs fitted with an Oculus acoustic camera, which images structures in turbid water. The equipment fits in two 23 kg cases, travels as checked luggage and is deployed by hand. Two campaigns of 2 to 4 days per site.

Expected results

Condition of the civil works and embedded parts of each structure, in video and acoustic imagery. Location and measurement of deposits in front of water intakes and bottom outlets. Data are compared from one site to the next, which helps prioritize maintenance works.

CNR · Rhône hydropower plants · 2022 to 2025

Photogrammetry of gate embedded parts

Structure

Stoplog slots, roller tracks and downstream gate bays in 10 hydropower plants on the Rhône, including Caderousse, Beauchastel, Sablons, Gervans and Chautagne. At Caderousse in 2025, gate slots were surveyed down to 8 m depth, sometimes with only 25 cm of visibility.

Equipment

TORTUGA XP4-HYDRO fitted with the HYDRO 300 photogrammetry system: two synchronized high-resolution cameras and strobe LED lighting on a tilting mount under the ROV. Oculus M3000d acoustic camera for navigation and imaging. Deployed by davit and piloted from the control truck.

Expected results

3D model of the rails and civil works of each gate slot, accurate enough for millimeter-level dimensional checks. Location and measurement of defects to assess the scope of repair works.

LEMA (Les Eaux de Mayotte) · Tsingoni, Mayotte · 2026

Combani Dam: underwater and endoscopic inspections

Structure

This dam supplies drinking water to northern Mayotte, with a reservoir of about 1.7 million m³. As part of a full diagnostic, all hard-to-reach areas were inspected. Underwater: spillway and its flap gates, bottom outlet inlet and strainer, upstream face. Inside the dam: Ø 200 and Ø 400 mm drainage trenches, drainage strips and piezometers. Visibility of about 70 cm and dense vegetation in the reservoir.

Equipment

Underwater: TORTUGA XP4 with Oculus acoustic camera and HYDRO 300 photogrammetry system, deployed by hand and positioned using an acoustic buoy designed for the mission. In the drains: endoscopic camera, video control unit and motorized crawler for the Ø 400 section. The equipment was shipped to Mayotte, and both inspections took 3 days.

Expected results

Acoustic mosaics and dimensions of the spillway. Condition of the concrete and metal parts of the bottom outlet, and detection of any blockage. Condition of the upstream face and sediment level at the bottom of the reservoir. For each drain and piezometer: diameter, length, elevations, material, water level and position of the screened section.

EDF Hydro · Durance canals · 2023 to 2026

Surface drone for leak detection

Structure

EDF canals at Salignac, Manosque, Beaumont-de-Pertuis, Mallemort and Jouques. At Salignac in 2026, the drone covered 4.5 km of canal, from the water intake to the outlet.

Equipment

AirCAT surface drone (50 kg, 150 kg payload), piloted from the control truck. It carries the self-potential and acoustic sensors of our partners MAPPEM and GEOPHY Consult, who perform the measurements and process the data. Launched from the bank with a winch, with no lifting equipment needed.

Expected results

Measurements across the full width of the canal along several parallel lines (6 at Salignac). Our partners use the data to locate potential leak zones.

EDF · Cadarache · 2019

Cadarache Dam: bathymetry after hydraulic flushing

Ouvrage

Cadarache Dam reservoir, upstream of the gravel flushing gate. After a hydraulic flushing operation, EDF wanted to measure its effectiveness. Survey of about 4,000 m², from the inlet channel to gate 1, around the intake of the flushing conduit.

Moyens

CAT-Surveyor surface drone fitted with a Norbit WBMS multibeam echosounder, a sound velocity probe and a motion reference unit. Centimeter-level RTK positioning and live survey monitoring from the control van. One day on site.

Résultats attendus

3D model and bathymetric map with 50 cm depth contours, XYZ point file at 0.2 m spacing and cross-sections at the water intake. Comparison with the previous survey shows the effect of the flushing and the remaining sediment height in front of the structure.

CNR · Isère · 2025

Sill of fixed-wheel gate no. 2

EDF · Sisteron (04) · 2023

Bathymetry and photogrammetry of Saint-Lazare Dam

Tractebel · Maroc · 2020

Inspection of 3 dams on the Oum Er-Rbia river, above and below water

Over 75 dam and reservoir projects since 2010, for public and private clients.