Gregg Dempsey

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Water Sampling and Analysis EPA Methods
and Guidance

• Gregg Dempsey
• Radiation and Indoor Environments National
  Laboratory
• Las Vegas, Nevada

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Issues

• Two radiation analyses gross alpha/beta and
  gamma spectroscopy have solids issues
• Tritium analysis has a specific collection issue
• Acidification (or not) is important
• Filtering (or not) is important
• Sampling
• Analysis issues
• Quality Assurance
• Key EPA guidance documents

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Data Quality Objectives

• EPAs 7-step process for figuring out how to
  perform an investigation
• Identifies the questions that need to be answered
  (why youre doing the project)
• Identifies the data needed to answer those
  questions
• Methods are selected and/or developed to collect
  the data that are needed
• We call this the DQO Process

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Radiation in Water

• Alpha radiation (heavy, easily stopped)
• Beta radiation (like electron, 6-8 feet range in
  air)
• Gamma (like light photon, most penetrating)
• In general, screening methods are applied first.

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Drinking Water Regulations

• Start with Gross Alpha/Beta Analysis
• Follow with other analyses as needed (or
  required)
• No real specifications for non-potable water but
  these general guidelines are traditionally
  followed.

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EPA Drinking Water Methods 900.0

• Gross Alpha and Beta radioactivity
• Drinking water samples are generally low in
  dissolved and suspended solids
• What everybody uses for every other kind of water
  (could be problems!)
• Best we have screening purposes but could
  stand improvement (research?)

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EPA Drinking Water Method 900.0

• Evaporate water sample onto 2-inch stainless
  steel planchet
• Measure alpha particle emission rate
• Measure beta particle emission rate
• Solids in the water interfere (bias low)
• Dissolved solids
• Suspended solids
• Correction factors used for solids content

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Evaporating Water
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Dry onto planchet
Water solids dried on planchet
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Weigh the sample
lt 5 mg/cm2
way over 5 mg/cm2
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Bottom line

• Too many solids in water sample and gross alpha
  results will be meaningless.
• Too many solids in water sample may also bias
  beta analysis as well.

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Method 900.0 Problems

• High solids content (gt5 mg/cm2 on planchet, equal
  to gt 100 mg total) may require
• Using less water (higher detection limits)
• Filtering for suspended solids
• We know upfront that nonpotable water (like
  from streams, lakes, rivers, etc.), will have to
  be filtered.

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Gamma Spectroscopy

• Tells us what gamma radiation is in the water

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Sediment (solids) in the sample

• When First Collected
• After About 2 Hours

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Sediment (solids) in the sample

• After About 2 Hours

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Sediment (solids) in the sample

• Shake and pour
• After About 2 Hours

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Sediment (solids) in the sample

• Sediment fell out of solution

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Gamma Spectroscopy Mistakes

• Looking at the sample does not measure solids

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Gamma Spectroscopy Mistakes

• Acidifying unfiltered sample might drive solids
  into solution
• Not acidifying sample might allow radionuclides
  to plate out on the plastic

• Uh oh, this might affect samples collected for
  tritium analysis too!

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Tritium Analysis

• Samples have to be collected in glass
• Tritium loves plastic and will go right into it
• Dont acidify samples filtering not needed

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Tritium Analysis

• Sample prep process includes distillation if done
  correctly.

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Technical Considerations to Consider in Project
Design

• Filter water for Gross A/B and Gamma Spec (you
  kind of have to)
• Analyze Filter Also!
• What is dissolved in the water
• What any suspended particles are made of
• What is stuck to the particles
• In general, the soil particles are made of
  materials that include naturally-occurring
  radionuclides and other metals

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Technical Considerations to Consider in Project
Design

• What is stuck to the particles or what the
  particles are may or may not be important
• Whether or not the particles can move with the
  groundwater can be a key question
• Analyzing unfiltered water may not give accurate
  results

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What do the analyses mean?

• If alpha is over a set point, or beta is over a
  set point what then?
• Can gamma radionuclides explain alpha or beta?
  If not, what then?
• The DQO Process should also identify additional
  analyses if trigger points are exceeded.

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Summary

• What are trigger points analyses? When are other
  analyses needed?
• Whether or not the particles can move with the
  groundwater can be a key question
• Analyzing unfiltered water may not give accurate
  results forgetting to look at filters can give
  inaccurate results too!
• Use DQOs to select sampling and analysis methods
  that serve project objectives

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Key Guidance Documents

• Greggs Big Caveat Know that theres debate
  about filtering and not filtering --- the biggest
  issue to me is how the analysis is done. Thats
  what drives the filter/nonfilter issue.
• Superfund Issue Paper Ground Water Sampling for
  Metals Analysis (1989)
• Superfund Issue Paper Low-Flow (Minimal
  Drawdown) Ground-Water Sampling Procedures (1996)
• Multi-Agency Radiological Laboratory Analytical
  Protocols Manual (MARLAP, 2001)
• Groundwater Forum Issue Paper Ground-Water
  Sampling Guidelines for Superfund and RCRA
  Project Managers (2002)
• Guidance for the Data Quality Objectives Process
  (2000)

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Web Links for Key Guidance Documents

• Superfund Issue Paper Ground Water Sampling for
  Metals Analysis (1989)
• http//www.epa.gov/ada/download/issue/gwsamp2.pdf
• Superfund Issue Paper Low-Flow (Minimal
  Drawdown) Ground-Water Sampling Procedures (1996)
• http//www.epa.gov/ada/download/issue/lwflw2a.pdf
• Multi-Agency Radiological Laboratory Analytical
  Protocols Manual (MARLAP, 2001)
• http//www.epa.gov/radiation/marlap/manual.htm
• Groundwater Forum Issue Paper Ground-Water
  Sampling Guidelines for Superfund and RCRA
  Project Managers (2002)
• http//www.epa.gov/tio/tsp/download/gw_sampling_gu
  ide.pdf
• Guidance for the Data Quality Objectives Process
  (2000)
• http//www.epa.gov/quality/qs-docs/g4-final.pdf

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Questions?