This guide is limited to the description of test methods typical for measurement of groundwater discharge from a control well.

Controlled field tests are the primary means of determining aquifer properties. Most mathematical equations developed for analyzing field tests require measurement of control well discharge.

Discharge may be needed for evaluation of well design and efficiency.

For aquifer tests, a conceptual model should be prepared to evaluate the proper test method and physical test requirements, such as well placement and design (see Guide D4043). Review the site data for consistency with the conceptual model. Revise the conceptual model as appropriate and consider the implications on the planned activities.

For aquifer tests, the discharge rate should be sufficient to cause significant stress of the aquifer without violating test assumptions. Conditions that may violate test assumptions include conversion of the aquifer from confined to unconfined conditions, lowering the water level in the control well to below the top of the well screen, causing a well screen entrance velocity that promotes well development during the test, or decreasing the filter pack permeability characteristics.

Some test methods described here are not applicable to injection well tests.

This guide does not apply to test methods used in measurement of flow of other fluids used in industrial operations, such as waste water, sludge, oil, and chemicals.

1.1 This guide covers an overview of methods to measure well discharge. This guide is an integral part of a series of standards prepared on the in-situ determination of hydraulic properties of aquifer systems by single- or multiple-well tests. Measurement of well discharge is a common requirement to the determination of aquifer and well hydraulic properties.

1.2 This guide does not establish a fixed procedure for any method described. Rather, it describes different methods for measuring discharge from a pumping or flowing well. A pumping well is one type of control well. A control well can also be an injection well or a well in which slug tests are conducted.

1.3 This guide does not address borehole flow meters that are designed for measuring vertical or horizontal flow within a borehole.

1.4 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only.

1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is 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. Furthermore, it is the user's responsibility to properly dispose of water discharged.

1.6 This guide offers an organized collection of information or a series of options and does not recommend a specific course of action. This document cannot replace education or experience and should be used in conjunction with professional judgment. Not all aspects of this guide may be applicable in all circumstances. This ASTM standard is not intended to represent or replace the standard of care by which the adequacy of a given professional service must be judged, nor should this document be applied without consideration of a project's many unique aspects. The word “Standard” in the title of this document means only that the document has been approved through the ASTM consensus process.