Today’s Lecture Groundwater sampling. Announcements Lecture today: groundwater sampling ...
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Transcript of Today’s Lecture Groundwater sampling. Announcements Lecture today: groundwater sampling ...
Today’s LectureGroundwater sampling
AnnouncementsLecture
today: groundwater sampling Thursday: HAZWOP – quiz (Bruce)
Lab Lab 1: Phase I ESA
rewriting Lab 2: Surface water sampling
grading in progress Lab 3: Soil sampling
report due Wed Oct 21
AnnouncementsLab
Saturday, Oct 17 Lab 4 Subsurface
sampling andmonitoring well installationDrilling Engineers, Inc., Fort Collins, 9 am-noon
arrange rides for self-transport
7:30 am departure Google spreadsheet sent
by email only @colorado.edu
accounts
Wednesday, Oct 28 Lab 5 Groundwater
sampling / Slug test East campus
Groundwater SamplingPurpose
collect samples representative of groundwater
determine concentration of contaminants in groundwater
Groundwater SamplingRemoving water from the well
bailers lowered and raised by hand or reel sample poured into bottle PVC, HDPE, Teflon, stainless steel
Groundwater SamplingRemoving water from the well
bailers lowered and raised by hand or reel sample poured into bottle PVC, HDPE, Teflon, stainless steel inexpensive readily portable dedicated / disposable / decontaminated
Groundwater SamplingRemoving water from the well
bailers lowered and raised by hand or reel sample poured into bottle PVC, HDPE, Teflon, stainless steel inexpensive readily portable dedicated / disposable / decontaminated slow atmospheric exposure small-diameter wells
Groundwater SamplingRemoving water from the well peristaltic pumps
install tubing in pump head provide power source
battery, generator, AC choose pumping rate
Groundwater SamplingRemoving water from the well peristaltic pumps
install tubing in pump head provide power source choose pumping rate less expensive portable disposable
material incontact withsample
Groundwater SamplingRemoving water from the well peristaltic pumps
install tubing in pump head provide power source choose pumping rate less expensive portable disposable material in contact
with sample atmospheric exposure
suction pulls VOCs out of water suction pulls CO2 out of water
limited to suction depth
Groundwater SamplingRemoving water from the well
positive-displacement pumps turbine, gear-driven, bladder
Groundwater SamplingRemoving water from the well
positive-displacement pumps turbine, gear-driven, bladder mainly inert materials
stainless steel; Teflon
depths to hundreds of feet flow control
low-flow purging and sampling steady flow versus surging flow
dedicated
Groundwater SamplingRemoving water from the well
positive-displacement pumps turbine, gear-driven, bladder mainly inert materials
stainless steel; Teflon
depths to hundreds of feet flow control
low-flow purging and sampling steady flow versus surging flow
dedicated / well-to-well decontamination between wells
expensive less portable sediment clogging
Groundwater SamplingPurging
removing water standing in well not representative of groundwater gas exchange in well casing
gain of oxygen affects redox potential gain or loss of carbon dioxide affects
pH loss of volatile organic compounds
leaching of contaminants from well casing
sorption of contaminants to well casing
(mixing with surface water in poorly-constructed well)
obtain representative sample generates wastewater for
disposal
Groundwater SamplingPurging
specified volume 3-5 well volumes calculated as water depth well cross-sectional
area
Groundwater SamplingPurging
specified volume 3-5 well volumes calculated as water depth well cross-sectional
area stabilization of field parameters
T; conductivity; pH; EH; dissolved oxygen; turbidity
minutes to hoursT
pH
[O2] turbidity
EH
conductivity
Groundwater Sampling
Groundwater SamplingPumping rate for purging and sampling
high pumping rate (> a few L min-1) less time in the field disturbance of aquifer sediments
higher total contaminant concentrations “fix” by filtering samples?
drawdown in well
Groundwater SamplingPumping rate for purging and sampling
high pumping rate (> a few L min-1) less time in the field disturbance of aquifer sediments
higher total contaminant concentrations “fix” by filtering samples?
drawdown in well low pumping rate (< few hundred mL min-
1) more time in the field undisturbed
more representative ofmobile contaminants
no need for filtration less drawdown in well less wastewater
well casing volumes
Groundwater Sampling
Groundwater Sampling
Groundwater Sampling
Groundwater SamplingPassive sampling
diffusion bags contaminants sorbed to material
within membrane contaminants extracted from material
in lab relies on groundwater flow through
well deployed weeks to months
bottles / sleeves lids closed by trigger
followingequilibration period
Groundwater SamplingSample handling
filtration total and dissolved
preservatives e.g., acid for trace elements
bottles plastic for metals glass for organic compounds air-tight seals for VOCs
storage coolers, ice
shipping chain of custody
lazygroundwatersampling
Next LectureWater level monitoring