stratagem974 eng v1

8/9/2019 Stratagem974 Eng v1

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Geophysics - Instrumentation - Environmental studies

Stratagem974 is a geophysical company located in Reunion Island. Diversified

activity and solid skills allow us to find solutions to civil engineering and

environmental issues thanks to non destructive methods, high technology devices

and high qualified staff. Were also able to work in difficult access sites.

Our specialities in applied Geophysics

Electrical Resistivity Tomography (ERT) 2D or 3D: water resources, mining

prospecting, civil engineering (lava tubes detection, sediments structure, substratum), with

an investigation from some meters to over 200 meters depth.

Fig 3 : hydrogeological / mining application of ERT survey

62 bvd du Chaudron97490 Sainte-ClotildeReunion IslandTl/fax : (+262) 262 21 84 69Cell : (+262) 692 26 60 62 / 692 36 96 50Mail : [email protected]

Fig 1 : ABEM SAS4000 and multiplexer,powered by 12 V battery

Fig 2 : acquisition profile on the field


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Fig 4 : geothermal prospecting

Fig 5 : lava tubes and cavities detection

Seismic reflexion / refraction: allows to visualize geological structure from seismicwaves echo created by a source (explosion, hammer hit or vibrating truck).

Applications :civil engineering, mining deposits, geological risks,

We are able to achieve submarineelectrical resistivity studies in order to :

- identify sedimentary layers structure

- detect fresh water resurgence

Fig 6: electrical tomographydevice for lagoon operation

64 electrodes device

Fig 7: seismic refraction profile


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Cross-hole and down-hole : recording of P and S waves velocity between drills and

ground characterization. Determination of Shear modulus G, Youngs modulus E and Bulk

modulus K.

Fig 8 : cross hole device : source (a), recever (b) and determination of modulus

a b

Electromagnetic induction:

high tension lines detection, electric and

telephonic cables, underground or inside

buildings. Unconnected cables can also bedetected.

Fig 9 : watercourse detection

Ground Penetrating Radar (GPR) :

buried pipes and cables detection (electrical,

telephonic), watercourses, cavity localisation,

GPR has others applications in several fields:

- assessment of reinforced concretecorrosion in term of corrosion probability inprospected areas.

- archaeology and palaeontologyapplication in order to locate signs of buriedhuman activities, gravestone, fossils (dinosaursand giant birds eggs,)

Fig 10 : GPR campaign


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Self Potential (SP) : measurement of

natural potential differences between a

reference and several points in order to draft a

site cartography.

Applications: contaminated soils assessment

(pollution spreading), corrosion potential

cartography of reinforced concrete structure,

leak detection on a dam,

Fig 12 : SP cartography in a contaminated site

Fig 11: buried pipe detection by GPR

Deformations monitoring of civil engineering

structure (bridge, dam, tunnel) by a network of electronic

nivels (accuracy = 0,001 mrad) and differential GPS

Fig 13 : electronic Nivel (Leica Geosystems)

Fig 14 : real time deformations monitoringof abutments of a 300 meters-long bridge


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Stratagem974 is also specialized in concrete structure assessment thanks to the

combination of several geophysical methods:

- woven-wire and corrosion detection in reinforced concrete by GPR- corrosion cartography by spontaneous potential

- deformations monitoring- geological studies by ERT...

Vibrations monitoring(building sites, airport,) by measuring and recording groundmovement velocity with geophones. It also can be used to detect water leak in a pipe.

Fig 16 : vibrations monitoring

Fig 15 : reinforced concrete structure bygeoradar 2GHz


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Soil or concrete sampling

Video inspection by micro-camera: civil engineering structures, drill hole, piping,tank, Investigation until 200 m-long.

Gravimetric anomalies measurement. Applications: geothermal prospecting,

underground cavities detection

Soil gas detection: Radon, CO2.Applications: volcanic and health risks assessment.

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Fig 18 : lava tubedetection withgravimetric method

Fig 19 : measurement of radon emitted by the ground

Fig 17 : concrete samplingcampaign for a pollution diagnosis


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Hydrology - Hydrogeology - Geochemistry

Instrumentation in hydrology and hydrogeology (preliminary studies, turn-key

systems supplying and installation):- multi-parameters meteorological measurement (pluviometry, temperature, atmosphericpressure, humidity, wind velocity, sunshine.)

- river data acquisition (flow, conductivity, temperature, pH)

- drill monitoring (water level, conductivity, temperature)

- sampling

Applications : water table and watershed studies, pollution monitoring, water balance,

Partnership with Geosciences Laboratory of Reunion University

Water analysis by ion chromatography DIONEX ICS 1000 :- major cations : magnesium, sodium, potassium, calcium- major anions: fluorine, chlorine, nitrates, sulphates

Rock and water analysis by XRF (Panalytical) :- total rock- heavy metals (mercury, lead, cadmium, cover, arsenic, or, nickel, zinc, cobalt,manganese)- others elements according to Mendeleev table

Rock textural analysis: preparation of rocks samples for microscopic observation andanalysis

Fig 20 : ratio rain/flow

Fig 21 : drills and sensors (conductivity,

temperature, pressure,)


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Our main references

o Conseil Gnral Runion (1993-2003) : Hydro-Fournaise program

- Establishment and monitoring of data acquisitions stations in fields of

hydrology and hydrogeology.- Geophysical measurements program: SP, TDEM, Electrical, VLF et AMT at

the Reunion

o French Cooperation Ministry (1996-1997) : Programme FAC (Fond dAide laCoopration) to develop Mauritius water resources (TDEM et CSAMT)

o Rgion Runion (2001-2007) : Geothermic program : (gravimetry, TDEM,CSAMT, SP, ERT)

o Gosciences Runion (1996-2008) : ERT, SP, AMT, TDEM

o Internationalcooperation (UNDP Comoros Island) : geophysical campaigns on

Karthala volcano (GPR, PS, GPS diffrentiel, Gaz du sol),

o Groupe Taylor&Smith (Mauritius, 2007) : textural study of rocks samples,

o UNO (2007-2008) PNUD (Programme des Nations Unies pour le Dveloppement) Reduction Risk & Disaster geophysical instrumentation of Karthala,

o Laboratory CREGUR (UR), Reunion (2007) : multi-parameters sensorsinstallation

o VINCIGroup (2007-2008) : pipes and cables detection with georadar

o SOGEA (2008) : cavities detection by electrical tomography

o DDE Runion/SGT (2008) : preliminary geophysical study for a bridge buildingo INGV (2008) : electrical tomography, SP,

o Rgion Runion (2008-2009) : Tram-Train project, GPR

o French Defence Ministry (2008-2009) : GPR, soil pollution diagnosis

o SHLMR (2008-2009) : cavities detection by electrical tomography

o Contaminated sites monitoring (2008) : confidential

o Conseil Gnral Runion (2008-2009) : bridge deformations monitoring bygeodesic sensor (confidential)

o French electrical company (EDF) (2009) : cross-hole campaign

o BRGM (2009) : hydrogeological characterization of a river by electrical andseismic measurements.

o ARUP SIGMA (Mauritius, 2009) : ERT

STRATAGEM974

62 Bvd du Chaudron 97490 Ste Clotilde REUNION island

Tel/fax : (262)262218469 Cell : (262)692266062

mail : [email protected]

stratagem974 eng v1

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