Development of the PVD Permeameter

Prefabricated vertical drains (PVDs) are often used to improve soils, by speeding up the rate of consolidation, and are increasingly used for remediation of contaminated soils. When PVDs are installed in the ground there is always a zone of disturbed soil surrounding the PVDs. The extent and the impact of this smear zone is difficult to quantify and this uncertainty complicates the use of laboratory values in design. Consequently, obtaining in-situ values for the hydraulic conductivity and horizontal coefficient of consolidation that include the effects of smear would be of great use to engineers using PVDs in design. A method that utilizes PVDs to obtain in-situ measurements of these parameters is described. The primary advantages of this method are its cost effectiveness and that smear is included in the results. A trial test was conducted on San Francisco Bay Mud. This promising method yields values that are logical and compare well with published values for the Bay Mud. Additional studies are planned to investigate the effects of different end treatments and the impact of the length to diameter ratio. This work is a collaborative effort between researchers at Villanova University and the Nilex Corporation, LLC.