Consistent Field Sampling Of Shallow Wells With Minimum Decontamination

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Consistent Field Sampling Of Shallow Wells With Minimum Decontamination

  1. 1. GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTS The Nielsen Environmental Field School, Inc. 2012 North American Environmental Field Conference & Exposition CONSISTENT FIELD SAMPLING OF SHALLOW WELLS WITH MINIMUM DECONTAMINATION 2650 East 40th Avenue • Denver, Colorado 80205 • www.geotechenv.com
  2. 2. GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTS Agenda • Introductions • Low flow sampling • Equipment examples • Documentation of low flow samples • Decontamination 2650 East 40th Avenue • Denver, Colorado 80205 • www.geotechenv.com
  3. 3. GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTS Jeff Popiel President and CEO JeffP@GeotechEnv.com 303.320.4764 2650 East 40th Avenue • Denver, Colorado 80205 • www.geotechenv.com
  4. 4. GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTS Geotech Corporate Headquarters Denver, Colorado USA …a world leader in environmental technology, manufacturing and product training since 1978. www.GeotechEnv.com 2650 East 40th Avenue • Denver, Colorado 80205 • www.geotechenv.com
  5. 5. GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTS an environmental industry products leader since 1978 partners with federal, state, local and international government agencies over 20,000 private sector clients worldwide distribution in 72 countries provides products and product training to colleges, universities and technical schools around the globe 2650 East 40th Avenue • Denver, Colorado 80205 • www.geotechenv.com
  6. 6. GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTS Audience Introductions • Name • Company name • Experience with groundwater sampling 2650 East 40th Avenue • Denver, Colorado 80205 • www.geotechenv.com
  7. 7. GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTS Just the Facts • “Low Flow” does not refer to the flow-rate of water discharged by a pump at the surface, which can be affected by valves, tubing restrictions or flow regulators. • “Low Flow” refers to the impact on formation hydraulics of pumping the well. Water level draw down provides a measurable indication of the stress on a given formation imparted by a pumping device operated at a given flow rate. • Objective: pump in a manner that minimizes stress or disturbance to the groundwater system to the extent practical. 2650 East 40th Avenue • Denver, Colorado 80205 • www.geotechenv.com
  8. 8. GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTS Low Flow Sampling • All methods have error and bias, which can influence samples • Method evolved to improve sample accuracy • Also called; – Consistent field sampling, – Low-stress purging, – Low-impact purging, and – Minimal draw-down purging • No removal of large volumes of water from the well – Less than one half the well volume – Vs. 3 to 5 times the well volume 2650 East 40th Avenue • Denver, Colorado 80205 • www.geotechenv.com
  9. 9. GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTS Characteristics of Low Flow Sampling • Deliver representative sample of water from formation • Submerged pump • Movement of water in well is minimized • Sample at a rate equal to or less than the water entering the well from the surrounding formation 2650 East 40th Avenue • Denver, Colorado 80205 • www.geotechenv.com
  10. 10. GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTS Advantages of Low Flow Sampling • Improved sample quality • Reduced disturbance in the well/formation • Reduced purge water volume (less $) • Improved detection of contaminant distribution • Increased well life • Reduced field labor costs 2650 East 40th Avenue • Denver, Colorado 80205 • www.geotechenv.com
  11. 11. GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTS Low Flow vs. Traditional Sampling Low Flow Traditional In low flow sampling, a well is purged at a very low rate to minimize draw-down and avoid disturbance in the well, as opposed to the traditional method of purging at a high rate and removing 3 to 5 times the well volume. Minimizes Increases drawdown, drawdown, turbidity & turbidity & purge volume purge volume 2650 East 40th Avenue • Denver, Colorado 80205 • www.geotechenv.com
  12. 12. GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTS Advantages of Low Flow Sampling Low Flow Traditional • Less well disturbance leads to lower sample turbidity • Reduced variability in the sample results • Purge volume reduced up to 95% can reduce purge time and labor • Reduces problems related to excessive drawdown and pumped volumes • Dedicated equipment for low flow sampling saves field time and also eliminates contamination from Dedicated Bailer movement other wells and from equipment bladder pump surges and handling samples mixes well, • Saves time and cost of disposing of undisturbed increasing contaminated purge water well turbidity 2650 East 40th Avenue • Denver, Colorado 80205 • www.geotechenv.com
  13. 13. GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTS Low Flow Sampling Decisions • Purge flow rate – Determine a purge flow rate which will minimize drawdown, commonly less than 1 liter per minute • Purge duration – Passing the purge flow through a flowblock measures key water quality parameters, allowing observation of the point when the readings become stable. – Commonly within 10 to 20 minutes, but depends on the well. – Sample collection can begin at this point. 2650 East 40th Avenue • Denver, Colorado 80205 • www.geotechenv.com
  14. 14. GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTS Low-Flow Samples to Expect • Yes for: • Not for: Collection of ground water Collection of LNAPLs (light samples for all categories of non-aqueous phase liquids) aqueous phase or DNAPLs (dense non- contaminants and naturally aqueous phase liquids). It is occurring analytes, not appropriate for wells including VOCs, metals and that purge dry because other organics, pesticides, these wells typically purge PCBs, organic compounds, dry before all indicator radionuclides, and parameters stabilize. microbiological constituents. 2650 East 40th Avenue • Denver, Colorado 80205 • www.geotechenv.com
  15. 15. GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTS Low flow sampling requires: • A sampling device capable of consistently providing low flow rates without agitating the water in the well or altering the sample quality • A flow cell to determine completion of purging • A water level measurement device to measure drawdown 2650 East 40th Avenue • Denver, Colorado 80205 • www.geotechenv.com
  16. 16. GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTS Documentation of Low Flow Sample According to ASTM Guide D 6089 • Equipment calibration • Drawdown measurements • Equipment decontamination • Stabilized pumping water level • Equipment configuration for • Final pump rate sampling • Water quality and turbidity • Pump placement measurements, with times • Initial static water level • Final sampling flow rate • Initial pump rate 2650 East 40th Avenue • Denver, Colorado 80205 • www.geotechenv.com
  17. 17. GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTS Bonded Water Quality Sample Tubing Reel Instrument Low Flow Components Air Line Water Level Reel and Probe Water Flowblock Line Power Source (Battery) Pump Controller Pump Well 2650 East 40th Avenue • Denver, Colorado 80205 • www.geotechenv.com
  18. 18. GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTS Bladder Pumps • Flexible bladder inside a rigid housing. • Water enters the bladder from the bottom. • Gas pressure is applied to the outside of the bladder. • Water is squeezed to the surface. • Air compressor and regulator turn the pressure on and off. • Sample does not contact the compressed air. • Check valves prevent backwash from the sample tube and bladder. 2650 East 40th Avenue • Denver, Colorado 80205 • www.geotechenv.com
  19. 19. GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTS Bladder Pumps • Generate reproducible analytical results • Suitable for collecting samples of almost any constituent. • Bladder pumps are recommended for purging and sampling. 2650 East 40th Avenue • Denver, Colorado 80205 • www.geotechenv.com
  20. 20. GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTS Flowblocks • Less than 40mL of void volume with probes installed • Flow rates of 100 mL/min to 1 gpm (3.8 LPM) • Sensors in direct line of sample stream • Block design for field durability • Tubing quick-connect barbs for easy connections • Easy cleaning 2650 East 40th Avenue • Denver, Colorado 80205 • www.geotechenv.com
  21. 21. GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTS During low flow sampling, the water level in the well is continuously monitored using any water-level measurement equipment that does not disturb the water column and that provides the accuracy required by the sampling program. These devices include: Pressure transducers Electronic water level meters (for continuous measurements) (for periodic measurements) 2650 East 40th Avenue • Denver, Colorado 80205 • www.geotechenv.com
  22. 22. GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTS Portable Not Recommended • Lowering a portable device into the well mixes the water column between the upper, more stagnant zone, and the screened zone, adding significantly to the time required to complete purging. • Portable equipment requires cleaning, handling and set-up steps while dedicated systems do not. 2650 East 40th Avenue • Denver, Colorado 80205 • www.geotechenv.com
  23. 23. GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTS If Portable is Necessary: Decontamination: Change Bladder 1. Remove the intake 4. Remove the upper assembly by screwing compression ring and counter-clockwise. slide the ring off. 2. Pull to remove the 5. Slide new bladder outer housing from over the O-ring. the upper cap. 3. Slide the lower 6. Replace the compression ring off. compression rings, outer housing and intake assembly. 2650 East 40th Avenue • Denver, Colorado 80205 • www.geotechenv.com
  24. 24. GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTS Summary • Low flow sampling is not complicated • Provides more reliable sample • Following steps keeps things organized, functional and clean • There is equipment that is easy to decontaminate 2650 East 40th Avenue • Denver, Colorado 80205 • www.geotechenv.com

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