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**Significance and Use**

5.1 This test method is one of several available for determining vertical anisotropy ratio. Among other available methods are Weeks ((5); see Test Method D5473), that relies on distance-drawdown data, and Way and McKee (6), that utilizes time-drawdown data. An important restriction of the Weeks distance-drawdown method is that the observation wells must have identical construction (screened intervals) and two or more of the observation wells must be located at a distance from the pumped well beyond the effects of partial penetration. The procedure described in this test method general distance-drawdown method, in that it works in theory for any observation well configuration incorporating three or more wells, provided some of the wells are within the zone where flow is affected by partial penetration.

5.2.3 Data are obtained from a number of partially penetrating observation wells, some screened at elevations similar to that in the pumped well and some screened at different elevations.

5.3 *Calculation Requirements—*Application of this method is computationally intensive. The function, f_{s}, shown in (Eq 4) must be evaluated numerous times using arbitrary input parameters. It is not practical to use existing, somewhat limited, tables of values for f_{s } and, because this equation is rather formidable, it is not readily tractable by hand. Because of this, it is assumed the practitioner using this test method will have available a computerized procedure for evaluating the function f_{s}. This can be accomplished using commercially available mathematical software including some spreadsheet applications, or by writing programs in languages such as Fortran or C.

**1. Scope**

1.1 This test method covers an analytical procedure for determining the transmissivity, storage coefficient, and ratio of vertical to horizontal hydraulic conductivity of a confined aquifer using observation well drawdown measurements from a constant-rate pumping test. This test method uses data from a minimum of four partially penetrating, properly positioned observation wells around a partially penetrating control well.

1.2 The analytical procedure is used in conjunction with the field procedure in Test Method D4050.

1.3 *Limitations—*The limitations of the technique for determination of the horizontal and vertical hydraulic conductivity of aquifers are primarily related to the correspondence between the field situation and the simplifying assumption of this test method.

**2. Referenced Documents** *(purchase separately)* The documents listed below are referenced within the subject standard but are not provided as part of the standard.

**ASTM Standards**

D653 Terminology Relating to Soil, Rock, and Contained Fluids

D4050 Test Method for (Field Procedure) for Withdrawal and Injection Well Tests for Determining Hydraulic Properties of Aquifer Systems

D5473 Test Method for (Analytical Procedure for) Analyzing the Effects of Partial Penetration of Control Well and Determining the Horizontal and Vertical Hydraulic Conductivity in a Nonleaky Confined Aquifer

**ICS Code**

ICS Number Code 13.060.10 (Water of natural resources); 73.100.30 (Equipment for drilling and mine excavation)

**UNSPSC Code**

UNSPSC Code

**DOI:** 10.1520/D5850-95R12

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**Citation Format**

ASTM D5850-95(2012), Standard Test Method for (Analytical Procedure) Determining Transmissivity, Storage Coefficient, and Anisotropy Ratio from a Network of Partially Penetrating Wells, ASTM International, West Conshohocken, PA, 2012, www.astm.org

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