Disagreeing Evaluations for Slug Tests in Monitoring Wells: Importance of Standards

2018 ◽  
Vol 42 (5) ◽  
pp. 20160046 ◽  
Author(s):  
Robert P. Chapuis
Keyword(s):  
Slug Tests ◽  
Monitoring Wells

Direct Push Technology and Application to Vertical Profiling of Hydraulic Conductivity in Unconsolidated Formations

2003 ◽  
Author(s):  
Wesley McCall ◽  
Thomas M. Christy ◽  
James J. Butler
Keyword(s):  
Hydraulic Conductivity ◽  
Test Data ◽  
Small Diameter ◽  
Cost Effective ◽  
Depth Interval ◽  
Contaminant Migration ◽  
Slug Tests ◽  
Monitoring Wells ◽  
Direct Push ◽  
Vertical Profiling

Direct push (DP) methods provide a cost-effective alternative to conventional rotary drilling for investigations in unconsolidated formations. DP methods are commonly used for sampling soil gas, soil and groundwater; installing small-diameter monitoring wells; electrical logging; cone penetration testing; and standard penetration tests. Most recently, DP methods and equipment for vertical profiling of formation hydraulic conductivity (K) have been developed. Knowledge of the vertical and lateral variations in K is integral to understanding contaminant migration and, therefore, essential to designing an adequate and effective remediation system. DP-installed groundwater sampling tools may be used to access discrete intervals of the formation to conduct pneumatic slug tests. A small-diameter (38mm OD) single tube protected screen device allows the investigator to access one depth interval per advancement. Alternatively, a larger diameter (54mm OD) dual-tube groundwater profiling system may be used to access the formation at multiple depths during a single advancement. Once the appropriate tool is installed and developed, a pneumatic manifold is installed on the top of the DP rod string. The manifold includes the valving, regulator, and pressure gauge needed for pneumatic slug testing. A small-diameter pressure transducer is inserted via an airtight fitting in the pneumatic manifold, and a data-acquisition device connected to a laptop computer enables the slug test data to be acquired, displayed, and saved for analysis. Conventional data analysis methods can then be used to calculate the K value from the test data. A simple correction for tube diameter has been developed for slug tests in highly permeable aquifers. The pneumatic slug testing technique combined with DP-installed tools provides a cost-effective method for vertical profiling of K. Field comparison of this method to slug tests in conventional monitoring wells verified that this approach provides accurate K values. Use of this new approach can provide data on three-dimensional variations in hydraulic conductivity at a level of detail that has not previously been available. This will improve understanding of contaminant migration and the efficiency and quality of remedial system design, and ultimately, should lead to significant cost reductions.

Conducting and Interpreting Slug Tests in Monitoring Wells with Partially Submerged Screens

Ground Water ◽  
1998 ◽  
Vol 36 (2) ◽  
pp. 225-229 ◽  
Author(s):  
Gordon K. Binkhorst ◽  
Gary A. Robbins
Keyword(s):  
Slug Tests ◽  
Monitoring Wells

scholarly journals Partially penetrating slug tests in an unweathered till layer

2016 ◽  
Vol 48 (1) ◽  
pp. 117-132
Author(s):  
David W. Ostendorf ◽  
William G. Lukas ◽  
Don J. DeGroot
Keyword(s):  
Laplace Transform ◽  
Spline Function ◽  
Inverse Laplace Transform ◽  
Short Term ◽  
Slug Test ◽  
Slug Tests ◽  
Monitoring Wells ◽  
Exponential Spline ◽  
Eastern Massachusetts

This research improves field based estimates of aquitard compressibility and permeability. A semianalytical model of partially penetrating, overdamped slug tests achieves this objective. The short term solution is an existing fully penetrating model, the long term solution is the polar residue of an inverse Laplace transform, and an exponential spline function patches the solutions together. Large amplitude slug test data from ten pairs of partially penetrating monitoring wells installed in an unweathered till at Scituate Hill in eastern Massachusetts calibrate the model. The deposit is bound by weathered till and the Dedham Granite fracture zone, and both are far more permeable than the unweathered till. The calibrated till permeability of 8.4 × 10–16 m2 is about 25% less than existing model calibrations that include boundary recharge in permeability values. The calibrated till compressibility of 5.1 × 10–10 Pa–1 reflects the proper inclusion of recharge as a long term source of groundwater, rather than the unrealistically large compressibility calibrations required by fully penetrating models.

Overdamped slug test in monitoring wells: review of interpretation methods with mathematical, physical, and numerical analysis of storativity influence

1998 ◽  
Vol 35 (5) ◽  
pp. 697-719 ◽  
Author(s):  
Robert P Chapuis
Keyword(s):  
Numerical Analysis ◽  
Classical Solution ◽  
Heat Conduction Problem ◽  
Solid Matrix ◽  
Test Results ◽  
Slug Test ◽  
Slug Tests ◽  
Monitoring Wells ◽  
Pulse Test ◽  
Negligible Influence

Several methods are available to interpret slug tests; however, when applied to the same test data, they usually yield very different results. The methods are classified into three categories depending on their assumptions about the solid matrix deformability during the test. This paper deals with overdamped tests for elastic solids that deform instantaneously. It provides a unified interpretation of transmissivity T and storativity S based on the velocity graph for variable-head tests in monitoring wells or cased boreholes. If S has little influence, the velocity graph is a straight line. If S has some influence, the graph should give a smooth curve. However, smooth curves are exceptions in practice, thereby leading to a reexamination of the influence of S during a slug test. Three independent approaches are used. (1) A mathematical review shows that the overdamped solution, as adapted from a heat conduction problem, did not correctly treat storativity terms and the type of problem: it corresponds to a special pulse test, not a slug test. (2) A physical investigation of deformability shows that the influence of S does not exceed 1% of the initial slug for most compressible materials. Thus, it is almost impossible to detect its influence in test results. (3) Numerical analyses confirm that S has a negligible influence: test results provide straight lines, not curves. The numerical analysis of the special pulse test provides exactly the classical solution, and the correct values of T and S after eliminating the confusion about storativity terms. It is concluded that (1) S has a negligible influence in slug tests, (2) the existing classical solution giving T and S must be abandoned, and (3) the velocity-graph equation and its integral equation (Hvorslev or Bouwer and Rice) which correctly describe the process must be used.Key words: slug test, hydraulic conductivity, storativity, numerical modeling.

A dual-tube direct-push method for vertical profiling of hydraulic conductivity in unconsolidated formations

2002 ◽  
Vol 8 (2) ◽  
pp. 75-84 ◽  
Author(s):  
Wesley McCall ◽  
James J. Butler ◽  
John M. Healey ◽  
Alyssa A. Lanier ◽  
Stephen M. Sellwood ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Preferential Flow ◽  
Field Tests ◽  
Small Scale ◽  
Slug Tests ◽  
Monitoring Wells ◽  
Direct Push ◽  
Vertical Profiling ◽  
Discrete Interval ◽  
Sand And Gravel

Abstract A new direct-push procedure has been developed for the purpose of conducting discrete-interval slug tests to define vertical variations in hydraulic conductivity (K.) This approach is an extension of existing dual-tube methods developed for soil sampling. In this procedure, nested rods (tubes) are simultaneously advanced to predetermined test intervals. The inner rods are then removed and a screen is inserted into the formation for slug testing and possible water sampling. Once testing and sampling are completed, the screen is retrieved, the inner rods reinserted, and the system is advanced to the next test interval. A series of field tests were performed in a highly permeable sand and gravel aquifer to assess the effectiveness of this new approach. Dual-tube profiling results were compared to multilevel slug tests conducted in conventional monitoring wells for intervals in which hydraulic conductivity ranged from 175 ft/day to over 800 ft/day. An initial evaluation found that the dual-tube profiling results were in good agreement (< or =12 percent difference) with K values obtained from multilevel slug tests in the closest monitoring well. Two more-detailed profiles demonstrate that the dual-tube method can effectively delineate small-scale vertical and horizontal variations in hydraulic conductivity. This field assessment shows that the dual-tube method is an accurate and efficient procedure for obtaining information about spatial variations in hydraulic conductivity. This information can be useful for selecting intervals for well installations, for assessment of various remediation alternatives, and for identifying preferential flow paths and other features that can control contaminant movement in the subsurface. The information is obtained without the need for permanent wells. Because this is a direct-push procedure, drill cuttings are eliminated and the volume of development water generated is significantly reduced.

Correction to "The analysis of slug tests in the frequency domain" (WRR 25(11), pp. 2388-2396

1990 ◽  
Vol 26 (8) ◽  
pp. 1863-1863
Author(s):  
Paul Marschall ◽  
Baldur Barczewski
Keyword(s):  
Frequency Domain ◽  
Slug Tests

Using groundwater levels and Specific Yield to Estimate the Recharge, South of Erbil, Kurdistan Region, Iraq

2018 ◽  
Vol 7 (4) ◽  
pp. 191
Author(s):  
Sherwan Sh. Qurtas
Keyword(s):  
Unconfined Aquifer ◽  
Middle Part ◽  
Water Levels ◽  
Specific Yield ◽  
Aquifer System ◽  
Groundwater Levels ◽  
Monitoring Wells ◽  
Water Table Fluctuation Method ◽  
Recharge Estimation ◽  
Fluctuation Method

Recharge estimation accurately is crucial to proper groundwater resource management, for the groundwater is dynamic and replenished natural resource. Usually recharge estimation depends on the; the water balance, water levels, and precipitation. This paper is studying the south-middle part of Erbil basin, with the majority of Quaternary sediments, the unconfined aquifer system is dominant, and the unsaturated zone is ranging from 15 to 50 meters, which groundwater levels response is moderate. The purpose of this study is quantification the natural recharge from precipitation. The water table fluctuation method is applied; using groundwater levels data of selected monitoring wells, neighboring meteorological station of the wells, and the specific yield of the aquifers. This method is widely used for its simplicity, scientific, realistic, and direct measurement. The accuracy depends on the how much the determination of specific yield is accurate, accuracy of the data, and the extrapolations of recession of groundwater levels curves of no rain periods. The normal annual precipitation there is 420 mm, the average recharge is 89 mm, and the average specific yield is around 0.03. The data of one water year of 2009 and 2010 has taken for some technical and accuracy reasons.

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