1. Today’s Lecture  Groundwater sampling

2. Announcements  Lecture  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

3. Announcements  Lab  Saturday, Oct 17  Lab 4 Subsurface sampling and monitoring well installation Drilling Engineers, Inc., Fort Collins, 9 am-noon  arrange rides for self- transport  7:30 am departure  Google spreadsheet sent by emailspreadsheet  only @colorado.edu accounts  Wednesday, Oct 28  Lab 5 Groundwater sampling / Slug test  East campus

4. Groundwater Sampling  Purpose  collect samples representative of groundwater  determine concentration of contaminants in groundwater

5. Groundwater Sampling  Removing water from the well  bailers  lowered and raised by hand or reel  sample poured into bottle  PVC, HDPE, Teflon , stainless steel

6. Groundwater Sampling  Removing 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

7. Groundwater Sampling  Removing 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

8. Groundwater Sampling  Removing water from the well  peristaltic pumps  install tubing in pump head  provide power source  battery, generator, AC  choose pumping rate

9. Groundwater Sampling  Removing 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

10. Groundwater Sampling  Removing 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 CO 2 out of water  limited to suction depth

11. Groundwater Sampling  Removing water from the well  positive-displacement pumps  turbine, gear-driven, bladder

13. Groundwater Sampling  Removing 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

14. Groundwater Sampling  Removing 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

15. Groundwater Sampling  Purging  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

16. Groundwater Sampling  Purging  specified volume  3-5 well volumes  calculated as water depth  well cross-sectional area

17. Groundwater Sampling  Purging  specified volume  3-5 well volumes  calculated as water depth  well cross-sectional area  stabilization of field parameters  T; conductivity; pH; E H ; dissolved oxygen; turbidity  minutes to hours T pH [O 2 ] turbidity EHEH conductivity

18. Groundwater Sampling

20.  Pumping 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

21. Groundwater Sampling  Pumping 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 of mobile contaminants  no need for filtration  less drawdown in well  less wastewater

23. well casing volumes

24. Groundwater Sampling

27.  Passive 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 following equilibration period

28. Groundwater Sampling  Sample 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

30. lazygroundwatersampling

31. Next Lecture  Water level monitoring