The Science Behind Ground-Water Sampling

• Objectives and Purposes of Ground-Water Sampling
• Data Needs and Data Quality Objectives
• Formation and Well Hydraulics Between Sampling Events and During Sampling
• Factors That Affect the Representative Nature of Ground-Water Samples
  • Agitation and Aeration of the Water Column
  • Over-pumping
  • Pressure and Temperature Changes Caused by Sampling Devices
  • Exposure of the Sample to Atmospheric Conditions
• Sampling Recommendations Based on Ground-Water Research
  • Well-Volume Purging
  • Purging to Stabilization of Indicator Parameters
  • Low-Flow Purging and Sampling
  • Sampling Low-Yield Wells
  • No-Purge/Passive Sampling

Review of Traditional Well Purging Strategies

• Objectives of Purging
• Comparison of Traditional Strategies for Purging High-Yield Wells
  • Well-Volume Purging
  • Purging to Field Indicator Stabilization
  • Using Packers to Isolate Parts of the Water Column
  • Problems with Traditional Purging Methods

Low-Flow Purging - What It Is, How It Works, Equipment Needs and Uses, Applications and Limitations, Economics

• Fundamental Concepts of Low-Flow Purging & Sampling
• Requirements for Equipment and Flow Rates
• Well Hydraulics During Low-Flow Purging and Sampling
• Procedures Used for Low-Flow Purging & Sampling
  • Measuring Drawdown to Stabilization
  • Measuring Field Indicator Parameters to Stabilization
• Dedicated vs. Portable vs. Designated Equipment
• Advantages and Limitations of Low-Flow Purging & Sampling

Procedures for Accurate Field Parameter Measurement

• Parameters Traditionally Measured and Why They May Not Be Meaningful
  • Temperature, pH, Conductivity
• More Meaningful Parameters
  • Specific Conductance, Dissolved Oxygen, ORP
• Significance and Use of Turbidity as a Field Parameter
• Instrumentation Options for Field Parameter Measurement
• Calibration of Field Parameter Measurement Instrumentation
• Common Errors in Field Parameter Measurement

No-Purge Sampling - What it is, How it Works, Equipment Needs & Uses, Applications and Limitations

• Fundamental Concepts of No-Purge Sampling
• Equipment Used for No-Purge Sampling
• Procedures Used for No-Purge Sampling
• Advantages and Limitations of No-Purge Sampling

Improved Practices for Sampling in Low-Yield Wells

• Passive Sampling as An Alternative to Purging a Well to Dryness
• No-Purge Sampling
• Purging the Well to the Top of the Well Screen and Then Sampling

Procedures for Collecting Ground-Water Samples Using Low-Flow Purging and No-Purge Sampling

Documenting Information Collected and Procedures Implemented During Low-Flow Purging and No-Purge Sampling

• Written Records
• Electronic Records
• Audio-Visual Records
• Techniques to Implement to Ensure Field Notes Are Defensible

Field Session on Low-Flow Purging and No-Purge Sampling:

• Preparing the Well for Sampling
• Continuous Water Level Measurement
• Field Measurement of Water Quality Indicator Parameters
• Low-Flow Purging with Dedicated and Portable Pumping Devices
• No-Purge Sampling Methods and Equipment
• Sample Collection and Handling for VOCs, Semivolatiles, Metals and Major Ions