Groundwater Pollution

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Groundwater Pollution

• Week 5 0407 Investigating the Site and
  Monitoring

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• Some Notes derived from
• 1.34 Waste Containment and Remediation Technology
  , As taught in Spring 2004, by Dr. Peter
  Shanahan , MIT OpenCourseWare, Creative Commons
  License, http//ocw.mit.edu/OcwWeb/Civil-and-Envi
  ronmental-Engineering/1-34Spring2004/CourseHome/

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• revision of previous week

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• Information to help with the clean-up of
  contamination can be found at http//clu-in.org/
  .
• For example http//clu-in.org/characterization/tec
  hnologies/solvr.cfm
• helps decide what is the best characterization
  technique.

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• You can click on the different technologies for
  more information.

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• You can also look at each method.

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• We then investigate the contaminant.
• Where is the contaminant plume?
• What is in the plume?
• How big is the plume?
• How long has it been there?
• Where is it going?
• How fast will it go?

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• Q. What is a contaminant plume?

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• The contaminant plume is where the contaminant is
  dissolved in the ground water.

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• Usually - The contaminant plume is where the
  contaminant is dissolved in the ground water.
• Sometimes - It can also mean where the vapor is
  dissolved in the air.

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• Q. Give a meaning for phase.

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• Vadose zone
• Floating
• Groundwater

The phases are when the pollutant is solid (solid
phase), liquid (liquid phase), vapor (gaseous
phase), or dissolved in the water (aqueous phase).
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• In the vadose zone contaminants could be present
  as
• Vapors in the void (??)
• Free product in the void
• Dissolved in the soil moisture (??)
• Adsorbed (????) onto the soil matrix
• Floating on top of the capillary fringe
• Q. Draw a picture of each of the above.

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• Collecting vapor samples from contaminated areas
  in the unsaturated zone

http//toxics.usgs.gov/photo_gallery/photos/bimidj
i/bimidji10_lg.jpg
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• Adsorption (n.)(?? ) is when molecules of gas,
  liquid, or dissolved solids stick to a surface.
• Adsorb (v)
• Adsorbed (v. and adj)

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Sorption
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• Contaminants could be in the saturated zone as
• Dissolved (???) in the groundwater
• Adsorbed onto the aquifer material
• Sitting on top of the bedrock (for dense
  nonaqueous phase liquids DNAPLs)
• Q. Draw diagrams of each of these.

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NAPLs coat the Soil Particles
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NAPLs fill the Voids
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The first steps are called remedial (???)
investigation (??) (RI) activities (??)

• Removal of contamination sources
• Doing some soil borings (????)
• Making groundwater monitoring (???) wells
• Soil sample collection and analysis
• Groundwater sample collection and analysis
• Aquifer testing

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• Questions to be answered by site
• characterization
• Nature and extent of contamination
• where is it?
• What is future migration and control
• where is it going?
• What are receptors and their risk
• what harm will it do?
• What are technical options for remediation
• how do we fix it?

Waste Containment and Remediation Technology
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• Data needed from site characterization
• 1. Contaminant sources research history as well
  as collect samples
• 2. Extent of contamination need to understand
  transport as well
• 3. Hydrogeologic setting use to understand
  items 1 and 2
• 4. Restoration potential how easy is it to
  clean up?

Waste Containment and Remediation Technology
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• Stages of investigation
• Stage 1 scoping study
• Is there a problem? How bad is it?
• Stage 2 prepare field study plan
• Includes sampling and analysis, health and
  safety, and quality assurance plans
• Stage 3 conduct on-site sampling and analysis
• Stage 4 interpretation, assessment, modeling
• (Stages 3 and 4 may be repeated several times)
• Stage 5 design remedial action

Waste Containment and Remediation Technology
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• First steps in understanding a site
• 1. Understand geographic setting, topography,
  nearby water bodies
• 2. Get background geologic data
• Consult ground-water atlas of the area.
• Get reports on geology, hydrology, meteorology
• Check for reports from government geological
  surveys

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• First steps in understanding a site
• 3. Understand site use and history
• Where were chemicals handled or disposed?
• What site structures or activities are potential
  sources?
• What chemicals are and were handled?

Waste Containment and Remediation Technology
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• The following types of data are collected
• Types of contaminants present in soil and
  groundwater
• Concentrations of contaminants in the samples
• Vertical and areal spread of contaminant plumes
  in soil and groundwater
• Vertical and areal spread of free-floating
  product or the DNAPLs
• Soil characteristics including the types of soil,
  density, moisture content, etc.
• Groundwater elevations
• Drawdown data collected from aquifer tests

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http//mn.water.usgs.gov/bemidji/results/fact-shee
t.pdf
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• Engineering calculations help site remediation.
• These could include
• Mass and volume of soil removed during tank
  removal
• Mass and volume of contaminated soil left in the
  vadose zone
• Mass of contaminants in the vadose zone
• Mass and volume of the free-floating product
• Volume of contaminated groundwater
• Mass of contaminants in the aquifer
• Groundwater flow gradient and direction
• Hydraulic conductivity of the aquifer

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• Understanding the geology and physical
  contaminants.

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• Geophysical Methods

Method Object
Electrical resistivity Map conductive or nonconductive contaminants stratigraphy
Electromagnetic induction Map conductive or nonconductive contaminants metal objects stratigraphy
Seismic refraction Stratigraphy (top of bedrock) depth to ground water
Seismic reflection High resolution mapping of top of bedrock
Ground penetrating radar (GPR) Buried objects (plastic and metal) stratigraphy depth to ground water
Magnetometry Buried metal objects
Gravity survey Overburden thickness landfill boundaries
Waste Containment and Remediation Technology
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• Ground penetrating radar

Waste Containment and Remediation Technology
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• Electromagnetic Induction

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• Electrical resistivity

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• Seismic
• reflection

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• Geophysics
• suite

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• Sampling the gas phase

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• Soil gas sampling system

Waste Containment and Remediation Technology
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• Output from field GC

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• Soil gas survey results

Waste Containment and Remediation Technology
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• There are two main methods of getting into the
  ground.
• - Drilling
• - Direct Push

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Drilling deep test hole http//nevada.usgs.gov/ad
rs/images/photos/studyareas/StudyAreasandExperimen
talS/study9.html
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• Drilling techniques

Waste Containment and Remediation Technology
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• Hollow Stem Auger

Waste Containment and Remediation Technology
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• Direct-push
• technology
• (Geoprobe)

Waste Containment and Remediation Technology
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• Direct-push monitoring well

Waste Containment and Remediation Technology
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• Direct push - Advantages
• Inexpensive to install, replace and abandon
• Minimal waste cuttings
• Fewer well development wastes
• Rapid installation and site characterization
• Less worker exposure to contaminants
• Representative chemistry and field parameter
  measurements
• Improved landowner relations

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• Direct push - Disadvantages
• Not applicable when cobbles or consolidated
  materials are present
• May not be accepted for long term monitoring in
  most states
• Debate remains regarding aquifer testing
  capabilities
• Well diameter limitations
• Pump diameter limitations
• Potential for higher turbidity in wells with no
  filter pack

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Demonstration/Validation of Long-Term Monitoring
Using Wells Installed by Direct Push Technologies
and Enhanced Low-Flow Groundwater Sampling
Methods. DoD 2009
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• Percentage Savings for DP Well Installations
  Based on Well Diameter and Depth.

Demonstration/Validation of Long-Term Monitoring
Using Wells Installed by Direct Push Technologies
and Enhanced Low-Flow Groundwater Sampling
Methods. DoD 2009
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• http//www.frtr.gov/decisionsupport/index.htm
• http//www.clu-in.org/characterization/technologie
  s/solvr.cfm