Groundwater measurements

Groundwater measurements are covered by International Standard EN ISO 22475, which is divided into three parts covering technical principles for execution (Part 1), qualification criteria for enterprises and personnel (Part 2), and conformity assessment of enterprises and personnel by third party (Part 3).11 At the time of writing (early 2008), only Part 1 has been published and the other parts are in draft awaiting approval.

Geohydraulic testing is covered by International Standard EN ISO 22282, which is divided into six parts covering general rules (Part 1), water permeability tests in a borehole using open systems (Part 2), water pressure tests in rock (Part 3), pumping tests (Part 4), infiltrometer tests (Part 5), and water permeability tests in a borehole using closed systems (Part 6).12 At the time of writing (early 2008), all of these standards are in draft awaiting approval before publication.

4.6.1 Groundwater measuring systems covered

§3.6 of EN 1997-2 gives information about open and closed groundwater measuring systems. In open systems, the piezometric groundwater head is measured by an observation well, usually provided with an open pipe. In closed systems, the groundwater pressure is measured by a transducer at the chosen location.

4.6.2 Planning and execution

§3.6.2 of EN 1977-2 provides guidance on the factors that need to be considered when planning and executing a groundwater investigation.

Particular attention should be paid to the selection of the type and location of the pore pressure/groundwater monitoring device to ensure that it is fit for purpose. This is a key factor as there are large numbers of potential devices/installations and not all will provide the information required. For example, if rapid changes in groundwater/pore pressure are likely, a simple standpipe piezometer is inadequate — a device that takes measurements at regular time intervals, such as a diver, should be specified.

4.6.3 Applicability of groundwater measurement systems

EN 1997-2 provides guidance on the applicability of groundwater measurement systems for assessing groundwater related geotechnical parameters, is summarized in the table below.

Applicability of groundwater measurement systems for obtaining parameters_

System

t

Soil or rock type

0 0

Post a comment