FIELD TRIAL OF THE PVD PERMEAMETER IN WILMINGTON, DE

Prefabricated vertical drains (PVDs) may be used to increase to the rate of consolidation (soil improvement) or as small injection and extraction wells to remove contaminants from soil. The major advantage of PVDs is that they are relatively inexpensive and therefore can be placed at very close spacing (typically 1 to 2 m center-to-center). Certain soil properties must be known to effectively design a PVD system. If PVDs are used for soil improvement, the horizontal coefficient of consolidation of the soil is required; if PVDs are used for remediation, the horizontal hydraulic conductivity is required. Determining these properties is complicated by the effects of installing the PVDs and the high cost of performing in-situ measurements. To allow for direct measurement of these parameters in the field, a PVD has been modified to create a device called the “PVD Permeameter”. Research on the PVD Permeameter has been ongoing since May 2003. To date, one field trial and laboratory experiments have been completed. Recently, a second field trial was performed to determine if the refinements that were made to the PVD Permeameter were appropriate and to check the results of the laboratory experiments. The preliminary results of this second field trial indicate that the improvements to the PVD Permeameter were successful and that use of this device could improve the design of PVD systems.