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GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTSGROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTS
CONSISTENT FIELD SAMPLING OF
SHALLOW WELLS WITH MINIMUM
DECONTAMINATION
The Nielsen Environmental Field School, Inc.
2012 North American Environmental Field Conference & Exposition
2650 East 40th Avenue • Denver, Colorado 80205 • www.geotechenv.com2650 East 40th Avenue • Denver, Colorado 80205 • www.geotechenv.com
GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTSGROUND 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
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GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTSGROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTS
2650 East 40th Avenue • Denver, Colorado 80205 • www.geotechenv.com2650 East 40th Avenue • Denver, Colorado 80205 • www.geotechenv.com
GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTSGROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTS
Jeff Popiel
President and CEO
303.320.4764
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GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTSGROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTS
www.GeotechEnv.com
…a world leader in environmental technology,
manufacturing and product training since 1978.
Geotech Corporate HeadquartersDenver, Colorado USA
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GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTSGROUND 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
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GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTSGROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTS
Audience Introductions
• Name
• Company name
• Experience with groundwater sampling
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GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTSGROUND 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.
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GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTSGROUND 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
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GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTSGROUND 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
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GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTSGROUND 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
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GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTSGROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTS
Low Flow vs. Traditional Sampling
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.
Low Flow
Minimizes drawdown,turbidity &
purge volume
Increases drawdown,turbidity &
purge volume
Traditional
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GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTSGROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTS
Advantages of Low Flow
Sampling
• 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
other wells and from equipment
handling
• Saves time and cost of disposing of
contaminated purge water
Dedicated bladder pump
samples undisturbed
well
Bailer movement surges and mixes well, increasing turbidity
Low Flow Traditional
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GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTSGROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTS
• Purge flow rate– Determine a purge flow rate which will
minimize drawdown, commonly lessthan 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.
Low Flow Sampling Decisions
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GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTSGROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTS
Low-Flow Samples to Expect
• Yes for: Collection of ground water samples for all categories of aqueous phase contaminants and naturally occurring analytes, including VOCs, metals and other organics, pesticides, PCBs, organic compounds, radionuclides, and microbiological constituents.
• Not for:Collection of LNAPLs (light non-aqueous phase liquids) or DNAPLs (dense non-aqueous phase liquids). It is not appropriate for wells that purge dry because these wells typically purge dry before all indicator parameters stabilize.
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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
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GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTSGROUND 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
• Equipment decontamination
• Equipment configuration for
sampling
• Pump placement
• Initial static water level
• Initial pump rate
• Drawdown measurements
• Stabilized pumping water level
• Final pump rate
• Water quality and turbidity
measurements, with times
• Final sampling flow rate
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GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTSGROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTS
Low Flow Components
Pump
Water Level
Reel and
Probe
Bonded
Tubing Reel
Air
Line
Water
Line
Sample
Power Source
(Battery)
Pump
Controller
Flowblock
Water Quality
Instrument
Well
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GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTSGROUND 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.
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GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTSGROUND 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.
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GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTSGROUND 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
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GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTSGROUND 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
(for continuous measurements)
Electronic water level meters
(for periodic measurements)
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GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTSGROUND 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.
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GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTSGROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTS
If Portable is Necessary:
Decontamination: Change Bladder1. Remove the intake
assembly by screwing
counter-clockwise.
2. Pull to remove the
outer housing from
the upper cap.
3. Slide the lower
compression ring off.
4. Remove the upper
compression ring and
slide the ring off.
5. Slide new bladder
over the O-ring.
6. Replace the
compression rings,
outer housing and
intake assembly.
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GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTSGROUND 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
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