Today’s Lecture  Water levels and groundwater flow

Announcements  Lecture  today: groundwater flow  Thursday: guest lecture Joy Jenkins, EPA: Captain Jack Superfund site  Lab  Lab 1: Phase I ESA  rewriting?  Lab 2: Surface water sampling  grading in progress?  Lab 3: Soil sampling  report due Wed Oct 21  Lab 4: Well drilling  report due Fri Oct 30

Announcements  Lab  Wednesday, Oct 28  Lab 5 Groundwater sampling / Slug test  East campus

Water Levels and Groundwater Flow  Measuring water levels in wells  single measurements  electronic water level sensors  simple tape measures inaccurate  long-term monitoring  pressure transducers  data recorders

Water Levels and Groundwater Flow  Water level meters  sensors on tapes  weighted probe on marked tape (PVDF*)  water completes circuit across electrodes  buzzer, light notification  depth  relative to known elevation; e.g., top of well casing  depths to 1,000 ft  accuracy to 0.01 ft or 1 mm * polyvinylidene difluoride

Water Levels and Groundwater Flow  Water level meters  advantages  reliable, rugged  easy to operate  accurate  disadvantages  probe, tape catches on casing joints  false readings from cascading water, condensation  a lot of reeling!

Water Levels and Groundwater Flow  Water level meters  sounders (acoustic)  travel time for sound wave  low frequency ( Hz)  depth  relative to known elevation; e.g., top of well casing  accuracy to 0.01 ft or 1 mm  advantages  quick; no decontamination  disadvantages  reflections off untrue well casing

Water Levels and Groundwater Flow  Long-term monitors  pressure transducers  accuracy 0.05%  temperature compensation  barometric compensation  data loggers  100,000s of readings

Water Levels and Groundwater Flow

 Groundwater flow contours  contours of groundwater elevation  potentiometric surface of surficial aquifer  less relevant for confined aquifers  direction and velocity of groundwater flow  important for contaminant transport  less useful for DNAPLs

Water Levels and Groundwater Flow  Groundwater flow contours  water flows from high to low head  often follows topography, but not always  slope  hydraulic gradient (L/L)  direction  planar surface defined by at least three water level measurements

Water Levels and Groundwater Flow  Calculation of groundwater flow direction  water levels in three wells

Water Levels and Groundwater Flow  Calculation of groundwater flow direction  water levels in three wells 28.1 ft 28.8 ft 28.4 ft

Water Levels and Groundwater Flow  Calculation of groundwater flow direction  water levels in three wells 28.1 ft 28.8 ft 28.4 ft 170 ft

Water Levels and Groundwater Flow  Calculation of groundwater flow direction  water levels in three wells 27.9 ft 28.8 ft 28.2 ft 170 ft

Water Levels and Groundwater Flow  Calculation of groundwater flow direction  water levels in three wells 27.9 ft 28.8 ft 28.2 ft 170 ft 113 ft

Water Levels and Groundwater Flow  Calculation of groundwater flow direction  water levels in three wells 27.9 ft 28.8 ft 28.2 ft 170 ft 113 ft

Water Levels and Groundwater Flow  Calculation of groundwater flow direction  water levels in three wells 27.9 ft 28.8 ft 28.2 ft 170 ft 113 ft

Water Levels and Groundwater Flow  Calculation of groundwater flow direction  water levels in three wells 27.9 ft 28.8 ft 28.2 ft 170 ft

Water Levels and Groundwater Flow  Calculation of groundwater flow direction  water levels in three wells 27.9 ft 28.8 ft 28.2 ft 170 ft 28.7 ft 76 ft

Water Levels and Groundwater Flow  Calculation of groundwater flow direction  water levels in three wells 27.9 ft 28.8 ft 28.2 ft 170 ft 28.7 ft 76 ft

Water Levels and Groundwater Flow  Calculation of groundwater flow direction  water levels in three wells 27.9 ft 28.8 ft 28.2 ft 170 ft 28.7 ft 76 ft

Water Levels and Groundwater Flow  Groundwater Flow Calculator doi: /gwat.12211

Water Levels and Groundwater Flow  Groundwater Flow Calculator

Water Levels and Groundwater Flow  Groundwater Flow Calculator

Water Levels and Groundwater Flow  Errors in groundwater level measurement  recording and transcription errors  condensation in well casing  poor flow through well screen  nearby infiltration sources  water line leaks  presence of LNAPL (“free product”)  leads to errors in groundwater velocity and direction LNAPL

Next Lecture  Guest lecture  Measuring aquifer properties – slug tests