1. Groundwater Pollution
0420 – Site Investigation 3

2. Will the material be tested in the ground or removed for testing?
- in the ground – using remote sensing
- removed for testing – using cores or pumping gas or water.

3. Remote sensing technology is being developed.

5. Photograph of a fiber optic biosensor; the functional tip with immobilized pH indicator and cells is directly over the coin.
Final Report: Fiber Optic Biosensors for Contaminant Monitoring. US DoD 2005

6. Fiber optic biosensor.
One end of the optical fiber is coated by a pH-sensitive fluorophore which is covered by cells or enzymes in Ca-alginate.
Final Report: Fiber Optic Biosensors for Contaminant Monitoring. US DoD 2005

7. 2-layer detection element of the CSU biosensor, illustrated for the ethylene dichloride biosensor. The pH-sensitive fluorophore is excited with 480-nm light and emits fluorescence at 520 nm, which is transmitted along the optical fiber to a photomultiplier.
Final Report: Fiber Optic Biosensors for Contaminant Monitoring. US DoD 2005

8. Down-hole profiling setup.
Final Report: Fiber Optic Biosensors for Contaminant Monitoring. US DoD 2005

9. Down-hole profiling results (biosensor readings vs. depth)
Final Report: Fiber Optic Biosensors for Contaminant Monitoring. US DoD 2005

10. Downhole XSD (halogen specific detector), uses oxidative chemistry.
Vapors pass through a reactor core of C, which breaks C-Cl bonds. A current forms as the chlorine atoms pick up electrons.
Direct Push Chemical Sensors for DNAPL DoD 2007

11. Direct Push Chemical Sensors for DNAPL DoD 2007
Experimental data from pushes of the halogen specific detector at a former dry cleaning site.
Direct Push Chemical Sensors for DNAPL DoD 2007

12. Direct push sensor systems
– Petroleum sensor: Laser-Induced Fluorescence (LIF)
– Metal sensor: Laser-Induced Breakdown Spectroscopy (LIBS)
– Solvents/soil characteristics: Soil Video Imaging System (GeoVIS)

15. Problems with traditional characterization methods
• Traditional methods depend on collection of samples and laboratory analysis
– difficult to know where to collect samples
– delay in getting results from laboratory
• may require several trips back to the field
– limited sample coverage
• may miss sources of contamination

21. Downhole video imaging system probe
Direct Push Chemical Sensors for DNAPL DoD 2007

22. In situ image of soil showing NAPL micro-globules
Direct Push Chemical Sensors for DNAPL DoD 2007

23. Fiber optic chemical sensors (FOCS) operate by transporting light by wavelength or intensity to provide information about analytes in the environment surrounding the sensor.

24. The sensor is placed directly into the media to be analyzed.
Interaction of the analyte with the chemically selective layer creates a change in absorbance, reflectance, fluorescence, or light polarization.
The change is detected by measuring changes in the light characteristic carried by the optical fiber.

25. Intrinsic FOCS measure:
- volatile petroleum constituents, such as benzene, toluene, ethylbenzene, and xylenes (BTEX),
- chlorinated volatile organic compounds (VOCs), such as TCE, PCE, and carbon tetrachloride, in water, air, or soil gas.

26. Extrinsic FOCS can detect:
- fluorescing hydrocarbons in the subsurface (often PAHs).
- elements in water, air, or soil.
- metals and organic chemicals in solid, air, or liquid.

28. Laser-Induced Fluorescence (LIF) detects:
- hydrocarbons (gasoline, diesel fuel, jet fuels, fuel oil, motor oil, grease, and coal tar) in undisturbed subsurface soils and groundwater.

31. Laser-Induced Fluorescence (LIF) tip

34. Components of monitoring well
Waste Containment and Remediation Technology

35. Well Logs
Waste Containment and Remediation Technology

36. Well installation Diagram
Waste Containment and Remediation Technology

37. Soil borings are often drilled to assess the extent of contamination in the vadose zone.
Samples are taken at every 2 or 3 m, and analyzed for soil properties.
Some samples are analysed in laboratories for contaminant concentrations.
From these data, a diagram is often developed to show the spread of the contaminant plume.

38. 38

39. A map can be made of the plume

40. NAPL may float on top of the water table and form a layer.
Estimate the volume or mass of the floating contaminant.
The thickness of free pollutant found in monitoring wells can be used to calculate the volume of the pollutant.

41. 41

42. Example cross section
Waste Containment and Remediation Technology

43. Laboratory Analysis Full analysis - $1100 Volatile organics - $185
(volatiles, semivolatiles, hazardous waste, pesticides, herbicides)
Volatile organics - $185
Semivolatile organics - $360
RCRA Appendix 8 metals - $110
(As, Ba, Cd, Cr, Pb, Hg, Se, Ag)
TAL metals - $240
(Al, Sb, As, Ba, Be, Cd, Ca, Cr, Co, Cu, Fe, Pb, Mg, Mn, Hg, Ni, K, Se, Ag, Na, Tl, V, Zn)
Pesticides - $145
Herbicides - $250
Source: Alpha Analytical Labs, Westborough, MA. April 2001 price list
Waste Containment and Remediation Technology

44. Groundwater can be sampled
Purging means take out old water from a monitoring well before sampling groundwater. 44

45. Two rows of monitoring points

46. When you take a sample from a monitoring well you must remove the water which is in the well before sampling the groundwater.
A few parameters are often monitored, such as conductivity, pH, and temperature, so they reach an even level before sampling.

47. Well purging before sampling

48. Purge 3 to 5 well volumes

49. He is collecting a sample of groundwater from a well

50. Purging can create problems.
It takes time
It produces waste water which needs to be treated.
Instead of purging the water it might be possible to pull out some water directly from the bottom of the well.

51. Passive diffusion sampler for water phase

52. The diffusion sampler stays in the bottom of the well for some time.
Then it is removed and the water inside it is analyzed.

53. Water samples must be analyzed.
This can be done in a laboratory or at the site (in the field).

55. Determine the number and type of microorganisms carrying out biodegradation