1 Integrated Geophysical Approach for Rapid & Cost Effective Site Investigations for Water Resources Presented at: India Water Week- April 8-12, 2013 Presented by: PARSAN Overseas (P) Limited

About PARSAN……

3 PARSAN Overseas An ISO 9001:2008 certified geophysical company Promoters recognized as leaders in region for launching new technology. Responsible for launch of: –Ground Penetrating Radar Technology –Shear Wave Seismic Refraction –High Resolution Seismic Tomography –Passive Seismic Tomography for Oil Exploration –Innovative use of geophysical methods for high resolution non-destructive testing of dams Highly experienced and trained staff. Offices in Delhi, Kolkata, Bahrain, Egypt (agent) & Sudan (agent). Work experience in India, Singapore, Oman, Afghanistan, Greece, Saudi Arabia, Bahrain, Kuwait, Iran, Algeria, Georgia…….

4 About Speaker Professional Geophysicist, with 22 years of work experience. Gold Medalist, University of Roorkee (Now IIT-Roorkee) Member of various working committees for development of Code of Practices and Standards. Completed geophysical investigations of 72 hydro power projects. Have conducted 28 training programs on Geophysics for various companies in 4 countries. Successfully used integrated geophysical approach for investigations across flowing rivers & for dam safety Conferred Golden Achievement Award 2011.

5 Geophysical Subsurface Investigations……

6 Why Use Geophysics……. Low Cost Rapid Coverage No Exposure to buried hazards Non Destructive Minimal Surface Disturbance Easy to integrate Integrated capability

7 Geophysics- Huge ROI... Detailed investigation of site…Saving huge costs towards changed plans, project delays when surprises crop up…. No drilling, No digging…Vast information at fraction of cost of traditional methods. Early stage application…Better planning, smooth execution.

8 MethodSensitive To...Typical Applications Seismic Refraction Changes in strata type (soil, weathered rock, rock), rock quality (jointed, weathered), elastic properties Rock interface, overburden mapping, rock quality, degree of weathering/ jointing, faults, fracture mapping Resistivity Imaging Moisture content variations, conductivity, water table, porosity Soil-rock profile, water table determination, weak zone delineation, detection of weak zones under rock interface, buried channels. ReMi (Refraction Micro-tremor)Change in shear properties of medium Determination of shear wave profiles (to determine liquefaction potential, earthquake response) Crosshole/ downhole/ uphole Difference in elastic properties. Variations in S Wave or P Wave velocity. Detailed analysis to obtain P and S wave velocities with depth for dynamic moduli: Poisson’s Ration, shear modulus, bulk modulus, Young’s modulus Seismic Reflection Difference in acoustic impedance (velocity x density) Detects interfaces, maps faults/ fractures/ water lenses/ shear zones along tunnel routes Ground Penetrating RadarChange in dielectric properties Detection of buried pipes and cables, with exact location and depth. Also used for inspection of concrete structures. Micro GravityChanges in Density of SubsurfaceDetection of buried voids/ cavities

9 Electrical Tomography …..

10 What for…… Applications: Determine the underground water resources Bedrock quality and depth measurements Mineral prospecting Dam structure analysis Landfill Contamination source detection Advantages: Excellent 2-dimensional display of ground resistivity. Delineation of small features like cavity, contamination plumes, weak zones in structures like dams etc.

11 Example…… Photo Courtesy:

12 Example……

13 Example…… Photo Courtesy: GeoInvest

14 Water Well Planning…… Photo Courtesy: GeoInvest

15 Water Table Contamination…… Time-lapse monitoring Photo Courtesy: GeoInvest

16 3D Modeling…… Photo Courtesy: GeoInvest

17 Detection of soft zone under rock (Hydropower)……

18 Cave/ Cavity……

19 Contamination…….

20 River Crossings…….

21 River Crossings…….

22 River Crossing……

23 River Crossing- Shear Zone…….

24 River Bottom Profile……. Photo Courtesy: GeoInvest

25 Seismic Refraction…….

26 Velocity Model…….

27 Velocity Model…….

28 Seismic Refraction- Applications Bedrock profile, rock quality and depth. Thickness of overburden Fractures and weak zones Topography of ground water Rippability assessment in mines Slope stability studies Pipeline route studies Seismic velocity increases markedly from unsaturated to saturated zone. The acoustic velocity of a medium saturated with water is greatly increased in comparison with velocities in the vadose zone. Thus, the refraction method is applicable in determining the depth to the water table in unconsolidated sediments.

29 Ground Penetrating Radar…..

30 Field Operation………

31 GPR- Features……… Penetration of more than 40 meters in certain formations (penetration dependent on conductivity and frequency of antenna) Data acquisition at walking speed. Identification of objects measuring on few centimeters. Light portable equipment Results available immediately

32 Water Table Mapping…….

33 Water Table Mapping…….

34 Fractures……

35 GPR- Contaminant Hydrogeology & Soil Stratigraphy GPR is extremely sensitive to variations in water content. It has been widely used to map water tables and the corresponding stratigraphy that controls groundwater flow. In addition, GPR is very sensitive to changes in water chemistry, particularly soluble inorganic materials that change conductivity. Inorganic materials such as DNAPL (chlorinated solvents) can alter the groundwater distribution resulting in GPR detectable responses.

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37 Dam Investigations

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39 Electrical Resistivity Imaging- Dam Axis………

40 Electrical Resistivity Imaging- Dam Axis………

41 SP Anomaly due to leakage………

42 Dam Investigation (integrated with SP)…….

43 Ground Penetrating Radar

44 GPR- Submerged Area

45 GPR-Tomography

46 Seismic Tomography Acoustic Waves Travel Time Properties for Each Cell Colour Tomogram of Dam Weathered Concrete, Fractures Highly Detailed Information

47 Pipeline Leak Detection…..

48 Pipeline Leak Detection using Seismograph…….

49 Leak Detection using GPR………

50 Leak Detection using GPR ………

51 Leak Detection using GPR ………

52 Leak Detection using GPR ………

53 Case Study

54 Problem……. Project site was for cable stayed bridge across a river. A cavity was detected in otherwise massive sandstone, while drilling. It was of utmost importance to determine nature and extent of this cavity before finalizing the design. Investigations: Geophysical investigations consisting of crosshole seismic and electrical tomography were conducted to determine depth and extent of the cavity.

55 Results…….

56 Conclusions……….

57 Conclusions……. Geophysical Techniques- Quick assessment of subsurface conditions in non-destructive manner Geophysical Techniques- Detailed and continuous information as against drilling Geophysical Techniques- Eliminates surprises during project execution

Thanks for your attention Dr. Sanjay Rana