multi level ground water monitoring l.
Skip this Video
Loading SlideShow in 5 Seconds..
Multi-Level Ground-Water Monitoring PowerPoint Presentation
Download Presentation
Multi-Level Ground-Water Monitoring

Loading in 2 Seconds...

play fullscreen
1 / 37

Multi-Level Ground-Water Monitoring - PowerPoint PPT Presentation

  • Uploaded on

Multi-Level Ground-Water Monitoring. Travis von Dessonneck. Multilevel Ground-Water Monitoring. Most important discovery in the past 40 years “…is that the distribution of dissolved contaminants in the subsurface is spatially complex, especially in the vertical dimension (Nielsen 808).”.

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
Download Presentation

PowerPoint Slideshow about 'Multi-Level Ground-Water Monitoring' - nan

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
multilevel ground water monitoring
Multilevel Ground-Water Monitoring
  • Most important discovery in the past 40 years “…is that the distribution of dissolved contaminants in the subsurface is spatially complex, especially in the vertical dimension (Nielsen 808).”

Multilevel Ground-Water Monitoring

  • This is due to several factors
    • Labyrinthine distribution of residual contamination in most NAPL source zones
    • Geologic heterogeneity
    • Weak mixing mechanisms in ground-water flow systems
multilevel ground water monitoring4
Multilevel Ground-Water Monitoring
  • Weaknesses of single-interval monitoring wells
    • Plume distortion
    • Composite samples mask true vertical distribution
    • Samples strongly biased by the position and length of the well screens
why three dimensional plume delineation is necessary
Why Three-Dimensional Plume Delineation is Necessary
  • Site assessment
    • Predicting plume migration
      • Long screened wells tend to over estimate risk
    • Effective remediation
      • Especially with Permeable Reactive Barriers (PRB)
one time sampling vs permanent multilevel monitoring devices
One Time Sampling vs. Permanent Multilevel Monitoring Devices
  • One Time Sampling advantages
    • Generally faster
      • No installation, development
    • No permanent structures
    • No long term monitoring requirement
one time sampling vs permanent multilevel monitoring devices7
One Time Sampling vs. Permanent Multilevel Monitoring Devices
  • One Time Sampling disadvantages
    • Whole story not told
      • No information on hydraulic head
    • Numerous one time samples to get contaminant vs. time
      • Becomes costly
      • Holes usually grouted
    • Not long term cost effective
one time sampling vs permanent multilevel monitoring devices8
One Time Sampling vs. Permanent Multilevel Monitoring Devices
  • When to install?
    • Determining hydraulic head distribution is necessary
      • Changes in head over time
    • Monitor remediation practices
    • Time series samples
options for ground water monitoring
Options for Ground-Water Monitoring
  • Multiple Diffusion Samplers installed inside single-interval monitoring wells
    • Installation of diffusion samplers over the screened interval of a well
      • Samplers consist of dialysis cells or polyethylene bags with DI water
      • the DI water is isolated from water in the wells
      • Contaminants diffuse through the bag or cell into the water within
options for ground water monitoring11
Options for Ground-Water Monitoring
  • The samplers must stay in the well long enough for the contaminant to reach equilibrium with the aquifer
  • Assume no vertical flow in the well
  • Assume that water flows unobstructed through the well
options for ground water monitoring12
Options for Ground-Water Monitoring
  • Diffusion Multilevel System
    • Same idea as above, but individual dialysis chambers are isolated to reduce vertical flow
    • Can detect:
      • Chloride
      • Nitrate
      • Sulfate
      • DO
      • Tetrachloroethylene
      • 1,1,1-trichloroethane
      • Organic and inorganic compounds
options for ground water monitoring13
Options for Ground-Water Monitoring
  • Active Collection of Samples from Multiple Depths within a Single-Interval well using grab samplers or depth-discrete pumping
    • Grab or Thief Samplers
      • Samplers lowered to desired depth and activated
        • May yield ambiguous results
        • Vertical flow in the well
        • Sampler may cause mixing
        • Increase turbidity
        • Time demanding
options for ground water monitoring14
Options for Ground-Water Monitoring
  • Collecting depth-discrete samples by pumping from different depth in well screens
    • Pumping creates vertical flow within the well
    • Only the first sample is good
options for ground water monitoring15
Options for Ground-Water Monitoring
  • Nested Wells (multiple tubes or casing in a single borehole)
  • Bundle Wells installed in collapsing sand formations
    • Allow formation to collapse around the wells
    • Usually sampled using peristaltic pumps
    • Tube diameters as small as 0.5 inches
    • Up to 20 different wells
options for ground water monitoring18
Options for Ground-Water Monitoring
  • Well Clusters
    • Can act as vertical conduit for contaminants
options for ground water monitoring19
Options for Ground-Water Monitoring
  • Dedicated Multilevel Ground-Water Monitoring Systems
    • Advantages
      • Facilitate the collection of samples and measurement of head from many more discrete depths
      • Only one pipe/tube per borehole
      • Total project costs significantly lowered
        • Less drilling
        • Less waste
options for ground water monitoring20
Options for Ground-Water Monitoring
    • Less time spent monitoring and sampling
    • Fewer wells for decommissioning
  • Little or no purging required
    • Less cost
  • Little water stored in the well, quicker reaction time to head changes
  • Smaller “footprint” on the ground
options for ground water monitoring21
Options for Ground-Water Monitoring
  • Disadvantages
    • Fewer options for sampling
      • Due to size of tubes
    • Some training required
    • May be more difficult to decommission the wells
options for ground water monitoring22
Options for Ground-Water Monitoring
  • Currently there are four commercially available systems
    • Westbay MP® System
    • Solinst Waterloo™ System
    • Solinst CMT™ System
    • Water FLUTe™ System
westbay mp system
Westbay MP® System
  • Two parts
    • Casing system
    • Portable probes and tools
  • Each monitoring zone is valved
  • Probes are lowered inside the casing to each monitoring zone
    • The probes locate and open the valve ports
    • Multiple probes can be used at the same time on different ports
westbay mp system27
Westbay MP® System
    • Notebook accessible
  • No limitation on number of ports except space
  • Samples taken at formation pressure, no purge
solinst waterloo system
Solinst Waterloo™ System
  • Modular system
    • 2 in schedule 80 PVC
  • Each port has a 1 or 2 valved stem connected to:
    • An open tube that runs up to the surface
    • A double valve pump
    • A bladder pump
    • Pressure tansducer
solinst waterloo system31
Solinst Waterloo™ System
      • Can be connected to data logger for continuous logging
  • Typically 3-8 monitors per well
solinst cmt system
Solinst CMT™ System
  • Continuous Multichannel Tubing
  • 1.6 in OD flexible HDPE tubing
  • Up to 7 discrete zones
    • Ports are staggered around the tube
    • Channels are plugged a few inches below each port
  • Samples taken with peristaltic pumps, small diameter bailers, inertial lift pumps, or small diameter double-valve pumps
water flute system
Water FLUTe™ System
  • Flexible Liner Underground Technology
    • Flexible impermeable liner of polyurethane-coated nylon
  • More than 20 zones
  • Can monitor boreholes 2-20 inches in diameter
  • Intervals inserted at factory
    • 0.17 and 0.5 in OD tubing
water flute system36
Water FLUTe™ System
  • Tubes have two valves on them to prevent flow back into the aquifer
  • Can be installed into nearly horizontal wells