Conducting an Aquifer Slug Test

Conducting aquifer pumping tests can be expensive and can require significant investments in labor and time. Contaminated water must be treated or transported out of the test area. As an alternative to pumping tests, many hydrologists perform slug tests for the following reasons: to determine many point estimates of hydraulic conductivity (K); to obtain results more quickly than with a pumping test; to develop small scale studies; to collect very good data in low K layers; and to reduce expenses.
Slug tests require the depression or elevation of static water in a well and the measurement of time it takes to equilibrate. This is accomplished by inserting a slug into a well, causing the water level to rise, or by removing the slug, causing the water level to fall. Time is measured until the water level returns to its original static position.
Measurements are logged at an extremely rapid sampling rate, typically as fast as the instrument will allow.
Alternatively, a logarithmically decaying sampling rate can be used. A valuable reference for all facets of slug testing is The Design, Performance, and Analysis of Slug Tests by J.J. Butler, Jr. (1997).
An aquifer slug test is typically conducted at a single well location. Before performing a slug test, the following field equipment is required: water level instrument with rapid or true logarithmic measurement capabilities, software for analysing data and modeling results, water level tape, personal protective equipment, and a slug. A slug can consist of a solid object that can slide into a well or a known volume of water.
In-Situ® Inc offers one of the most accurate and complete ranges of water level instruments on the market today. The Level TROLL® 700 instrument offers fast linear (4 times/second) and true logarithmic sampling rates for slug testing. Win-Situ® 5 software allows real-time viewing and graphing of the data as it is being logged to the Level TROLL 700 instrument’s memory. Data is available for analysis within Win-Situ 5 software and can be exported to AQTESOLV™ software (AQTESOLV is a trademark of HydroSOLVE, Inc.) for further analysis and to
apply the desired solution (e.g., Bouwer-Rice) to the data.
Please visit www.in-situ.com for details on Level TROLL instruments and to download the technical note titled, Slug Test Using the In-Situ Level TROLL® 500 and Level TROLL 700 Instruments and AQTESOLV Software.