ASTM International

Standard Test Method for Field Measurement of Hydraulic Conductivity Using Borehole Infiltration
 N D6391

Annotation

This test method covers field measurement of hydraulic conductivity (also referred to as coeff cient of permeability) of porous materials using a cased borehole technique. When isotropic conditions can be assumed and a flush borehole is employed, the method yields the hydraulic conductivity of the porous material. When isotropic conditions cannot be assumed, the method yields limiting values of the hydraulic conductivity in the vertical direction (upper limit) if a single stage is conducted and the horizontal direction (lower limit) if a second stage is conducted. For anisotropic conditions, determination of the actual hydraulic conductivity requires further analysis by qualified personnel.

This test method may be used for compacted fills or natural deposits, above or below the water table, that have a mean hydraulic conductivity less than or equal to 1X10–5 m/s (1310–3 cm/s).

Hydraulic conductivity greater than 1X10–5 m/s may be determined by ordinary borehole tests, for example, U.S. Bureau of Reclamation 7310 (1)2; however, the resulting value is an apparent conductivity.

For this test method, a distinction must be made between "saturated" (Ks) and "field-saturated" (Kfs) hydraulic conductivity. True saturated conditions seldom occur in the vadose zone except where impermeable layers result in the presence of perched water tables. During infiltration events or in the event of a leak from a lined pond, a "field-saturated" condition develops. True saturation does not occur due to entrapped air (2). The entrapped air prevents water from moving in air-filled pores, which may reduce the hydraulic conductivity measured in the field by as much as a factor of two compared with conditions when trapped air is not present (3). This test method develops the "field-saturated" condition.