In-classroom Pumping Test

David J. Becker
,
University of Nebraska Omaha
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Summary

Students conduct a pumping test in a sand-filled basin or tank in the classroom with either a siphon drain or small fountain pump. Drawdown is measured in small piezometers and students analyze the data to determine hydraulic conductivity and storage.

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Context

Audience

This is appropriate for an undergraduate course in hydrogeology to demonstrate pumping test procedures without the need for a field trip to outdoor/field site.

Skills and concepts that students must have mastered

The students should learn/read about pumping test procedures prior to conducting the test.

How the activity is situated in the course

The in-classroom pumping test is conducted after the lectures on pumping test procedures and data analysis. This is usually mid-semester.

Goals

Content/concepts goals for this activity

Students should strengthen their understanding of the practical aspects and hurdles of starting, managing, and monitoring a pumping test.

Higher order thinking skills goals for this activity

The students will have to assess data as collected, adjusting actual practice as necessary. This is good preparation for real field tests. They will learn to analyze real data (noise and all) rather than "well behaved" textbook data. They will have to consider the incidents that occurred during collection of the data in properly analyzing the data.

Other skills goals for this activity

They will understand the need for coordination between team members monitoring drawdown and controlling the pumping flow rate.

Description of the activity/assignment

A toddler wading pool or similar tank is filled with common sand (available from home improvement stores in bags) to a depth of 15-20 cm. The sand is saturated with a slow inflow and outflow to a floor drain. A 2-inch PVC slotted screen section is buried in the sand near the center of the tank with a capped end at the bottom. Small (1 cm diameter or similar) slotted or perforated PVC or copper tubing are placed as piezometers in the sand at short distances (e.g., 10-20 cm) from the pumping "well." A fountain pump capable of discharging up to 100-150 ml/min is placed within the "well" with adequate discharge tubing to conduct the water to a drain. A stopcock is placed in the tubing to control flow. Alternatively, if the tank of sand is on a very sturdy table, a simple siphon with tubing can be used as a pump. Drawdown is determined by the difference between a pre-pumping level measurement from the top of the "piezometers" and subsequent measurements made in the same "piezometer" at times after pumping starts. Water levels may be measured using chalked wooden rods. Alternatively, a small cork with a slender wooded food skewer marked in millimeter increments can be placed in each piezometers and the students can watch the change in level of the markings relative to the top of the "piezometer." Flow is repeatedly measured using a graduated cylinder. At the start of the test, students or teams of students are assigned to either take water level measurements at a specific piezometer or to measure and control the flow rate. The data are collected on a logarithmically increasing time interval for about an hour. The flow and drawdown data are analyzed by various means (Theis curve, Jacob straight-line method, Bolton curves, etc.) either manually or using AQTESOLV or similar software. Though the drawdowns are small, the data have provided quite reasonable estimates of hydraulic conductivity for the sand.

Determining whether students have met the goals

The students are asked to rate their confidence in the concepts before and after conducting the in-classroom pumping test. Their performance during the pumping test is observed and feedback and suggestions are given directly. Questions about the processes are asked on the subsequent exam.

More information about assessment tools and techniques.

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Other Materials

Supporting references/URLs

A previously unpublished manuscript in MS Word format that describes the activity in detail is provided.

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