California State University, Sacramento
Final lab- 24 hour drawdown test
Upon completion of this unit students should be able to:
Perform a 24 hour drawdown test using a downhole pump
Instrument monitoring wells for a drawdown test.
Analyze the test results
Reading for week 6:
Fetter- Groundwater Analysis, 4th ed. Non-steady state flow solutions, Theis solution, leaky aquifers
Sign up for a time to help with the 24 hour aquifer test. I will have the entire class at the wellfield to start the test. When the sampling rate drops to one measurement per hour, most of the class will go home. You will return for an 8 hour shift some time this weekend.
The groundwater modeler in your office needs values for T, K and S under the CSUS campus. This information will be used to build a groundwater flow model. What values will you give to the modeler? Use a variety of field methods, and justify your answer. Show enough work so that I can reproduce your calculations. Most of your work will involve the deeper aquifer, but you can also give an estimate of conditions in the shallower water bearing interval.
Due date: Monday, Sept. 10
Data from the aquifer test are posted here:
The sprinklers turned on 787 minutes into the test (roughly 10:45 in the evening). What happened to the drawdown curves when the sprinklers started? Remember that the sprinklers are supplied by 5 wells that produce from the deeper aquifer. What happened to the drawdown curves when the sprinklers turned off 6 hours later? These effects are especially strong in the wells near the levee and the bridge.
We did not get electronic data from MW-1A during the drawdown test.
Note: We did not get recovery data from EX-1 (logger failed).