Fully Grouted Piezometer Performance at a Dredged Material Management Site

Fully grouted vibrating wire piezometer installations provide advantages over conventional open-standpipe piezometers because of faster installation, simpler construction details, ease of multi-sensor installation within a borehole, faster response time, and improved accuracy. However, there remains some lack of confidence in performance when compared to conventional piezometers. For this analysis, fully grouted vibrating wire piezometers were installed at a dredged material management site near the Chesapeake Bay that was subject to tidal fluctuations. The dredged material is underlain by alternating sands and clay. Fourteen new fully grouted vibrating wire piezometers were installed in two boreholes adjacent to a new set of six traditional open standpipe nested piezometers, at depths corresponding to elevations of −4.6 to −38.1 m (−15 to −125 ft). One borehole was filled with a high-permeability grout; the other borehole was filled with a low-permeability grout. Data collection was automated using a data logger and wireless modem. Data analysis focused on comparing fully grouted vibrating wire piezometer results to data from the adjacent standard piezometer. Preliminary findings support the increased usage of fully grouted vibrating wire piezometers.