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D5269-15 – Standard Test Method Technical Guide
📐 Scope, Units, and Limitations
ASTM D5269-15 defines the analytical procedure for determining the transmissivity of nonleaky confined aquifers. This method specifically analyzes the recovery of water levels following a period of constant-rate pumping or injection in a control well. It is designed to be used in conjunction with the field procedures outlined in Test Method D4050, with Guide D4043 providing broader context for selecting hydraulic test methods.
The valid use of the Theis recovery method is strictly limited to aquifers in hydrogeologic settings that reasonably correspond to the foundational assumptions of the Theis theory (see Section 5.2). These assumptions typically include a homogeneous, isotropic, and infinite confined aquifer.
| 🟦 Aspect | 📏 Requirement | 📐 Conformance Rule |
|---|---|---|
| SI Units | Values stated per standard metric | Must be used independently |
| Inch-Pound Units | Values stated per US customary | Must be used independently |
| Combined Values | Mixing SI and Inch-Pound | May result in non-conformance |
| Alternative Units | Reporting in other units | Not considered nonconformance |
⚙️ Referenced Documents and Terminology
This test method relies on several companion ASTM standards. Terminology follows Terminology D653. The field component is conducted per Test Method D4050, while the analytical theory relates to the nonequilibrium methods in D4105 and D4106. All observed and calculated values must conform to the guidelines for significant digits and rounding established in Practice D6026.
An observation well is defined as a well open to all or part of an aquifer. The standard defines key symbols for the geotechnical parameters involved in the analysis.
| ⚡ Symbol | 📏 Dimension | 🎯 Definition |
|---|---|---|
| b | [L] | Aquifer thickness |
| K | [LT⁻¹] | Hydraulic conductivity |
📊 Analytical Considerations and Best Practices
The primary goal of D5269-15 is the calculation of transmissivity from residual drawdown data. The Theis recovery method leverages the principle of superposition to provide an independent measure of the aquifer’s transmitting properties.
💡 Best Practice: Ensure strict adherence to Practice D6026 for significant digits and rounding. Because SI and inch-pound units are not exact equivalents, each system must be utilized independently throughout the entire calculation process to maintain conformance.
⚠️ Critical Limitation: This method is valid exclusively for nonleaky confined aquifers. Results will be unreliable for unconfined aquifers or systems where vertical leakage, partial penetration, or boundary effects violate the core assumptions of the Theis theory. The user is responsible for establishing appropriate safety and health practices and verifying the applicability of the model.
It is also the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
❓ Frequently Asked Questions
🔍 What is the standard designation and scope of D5269-15?
The standard is D5269-15. Its scope is to determine the transmissivity of nonleaky confined aquifers by analyzing the recovery of water levels after constant-rate pumping or injection.
💡 Which field procedures are referenced for collecting the data?
The standard specifically references Test Method D4050 for the field procedures involving withdrawal and injection well testing to acquire the water level data.
⚡ How are units and significant digits handled in this standard?
Values are to be reported in SI units or inch-pound units, but they must be treated independently. Combining values from the two systems may result in non-conformance. All observed and calculated values must follow the guidelines in Practice D6026.
📌 What are the main assumptions of the Theis Recovery Method?
The primary assumption is that the aquifer is confined and nonleaky, matching the Theis model. Additional assumptions include homogeneity, isotropy, infinite lateral extent, a fully penetrating well, and constant discharge during the pumping phase.