California State University, Sacramento
- Three hour drawdown test: look for leakage
- Under-damped slug test solutions (Van der Kamp)
- Specific capacity
- Step tests
Upon completion of this unit students should be able to:
Make an initial assessment of leakage in the deeper water-bearing interval- using type curves for Theis solution,
Estimate well efficiency using drawdown data from an extraction well and two nearby monitoring wells
Estimate Specific capacity of the deeper water bearing interval
Use specific capacity to estimate transmissivity
Evaluate slug tests using an underdamped solution (Van der Kamp method)
Reading for week 5:
Your readings and references this week come from several different sources:
1) Specific capacity and aquifer transmissivity
Fetter, 4th ed., pp. 205-207
Fetter, 3rd ed., pp. 256-257
2) Leakage from an overlying confining layer:
Hantush, M.S., 1960, Journal of Geophysical Research, v. 65, pp. 3713 - 3725.
Walton, W.C., 1970, Groundwater Resource Evaluation: New York, McGraw Hill.
Fetter, 3rd ed., pp. 236-237
Fetter, 4th ed., pp. 205-207
3) Leakage with no storage in the overlying confining layer:
Walton, W.C., 1962, Illinois State Water Survey Bulletin 49.
Fetter, 4th ed., pp. 177-180 (Walton graphical method, 1962)
4) Underdamped slug test response (Van der Kamp method):
Fetter, 4th ed., pp. 200-204
Tuesday evening (Aug. 21):
Plan 24 hour test next weekend- sign up for time slots
Calculate specific capacity
Use Specific capacity to estimate transmissivity
Step tests- background and theory
Underdamped slug test solutions- Van der Kamp solution
Evaluate Saturday's field data (3 hour drawdown test). Plot by hand on the 3.5 log paper that I passed out (see link below). Be prepared to discuss the shape of the drawdown curve, how complete it is, and whether it matches leaky aquifer type curve shapes. I will bring sets of type curves to class.
Field data files from 3 hour step test, Saturday Aug 25: Hint: Open MS Excel first, then import the file.
Saturday activities (Aug 25):
Conduct a three hour step test at the CSUS wellfield
Assignment for week 5:
For Saturday Sept. 1
- Plot the results of the step test. Did we exceed the capacity of the aquifer to produce water?
- Use the data from our distance drawdown test to estimate well efficiency (see week 4 results). Look at actual drawdown in the pumped well. Use nearby wells (MW-1A, MW-3A) to project an ideal drawdown to the pumped well.
- Analyze the pneumatic slug test data that we collected on Saturday, August 11. Use an under-damped solution to account for the elastic response (oscillation) that we saw in the test. Your solution can be graphical (see the iterative method by Van der Kamp in Fetter, 4th ed.) or you can use a computer solution (Butler's Kansas Geological Survey solution).
Format of the report: Answer this question in 5 pages or less (cover letter to the client and figures are extra, and may go beyond 5 pages). Please double space your report, with normal margins and standard font (times or arial). Refer to all figures in the text. Citations are optional. Use appropriate technical writing style, and include the following sections in your report:
Cover page (letter to the client): Provide a cover letter and company logo that introduces your report to the client.
Introduction and purpose:State the purpose of the study: Use an overdamped solution to estimate K from the slug tests we conducted on Saturday, Aug. 11.
Hydrogeologic setting: Geologic, hydrologic, land use, construction, hazards, etc. as appropriate. Which wells did you use?
Methods: Field methods (pneumatic test), method of solution (either Van der camp or Butler)
Results: Summarize results.
Conclusions and recommendations Based on slug tests in deeper wells at the CSUS wellfield, what is your estimate of hydraulic conductivity (K) in the deeper water-bearing interval?
Due: Saturday, Sept. 1