25 Aug 2026

Wetland Elevation Change Following Beneficial Use of Dredged Material Nourishment

Abstract: The beneficial use of dredged material (BUDM) to nourish degrading wetlands is a direct solution to increase surface elevation to help wetlands keep pace with sea level rise (SLR). While there have been numerous demonstrations of BUDM in wetland environments, there is a limited understanding of the resultant spatial and temporal elevation response due to consolidation of the dredged material and underlying wetland foundation soils. To address this, surface elevations were monitored following multiple BUDM nourishments on a back-bay island in New Jersey. Field data was compared to consolidation models to assess the viability of current geotechnical modeling practices. Multispectral surveys were performed to document the revegetation of the nourished island over time. The placement of dredged material smothered the vegetation, but the site experienced significant revegetation after three full growing cycles. Approximately two years post BUDM, the nourished area experienced a 0.19 ± 0.11-m increase in elevation. The comparison of elevation immediately after nourishment and two years post-nourishment found that approximately two-thirds of elevation loss was the result of consolidation of deposited dredged material and the underlying wetland foundation. It was found that a reliance on solely laboratory data can induce a large degree of uncertainty within projected surface elevations. Thus, the implementation of in-situ geotechnical methods is strongly advised when possible. This investigation allowed for a comprehensive examination of geotechnical modeling methods for planning wetland nourishments, including predicting the ability to keep pace with sea level rise. Ultimately, the two BUDM nourishments offset the effects of SLR by approximately 18–28 years.

7 Jul 2022

Validation of the Automatic Dynamic Cone Penetrometer

Abstract: The U.S. military requires a rapid means of measuring subsurface soil strength for construction and repair of expeditionary pavement surfaces. Traditionally, a dynamic cone penetrometer (DCP) has served this purpose, providing strength with depth profiles in natural and prepared pavement surfaces. To improve upon this device, the Engineer Research and Development Center (ERDC) validated a new battery-powered automatic dynamic cone penetrometer (A-DCP) apparatus that automates the driving process by using a motor-driven hammering cap placed on top of a traditional DCP rod. The device improves upon a traditional DCP by applying three to four blows per second while digitally recording depth, blow count, and California Bearing Ratio (CBR). An integrated Global Positioning Sensor (GPS) and Bluetooth® connection allow for real-time data capture and stationing. Similarities were illustrated between the DCP and the A-DCP by generation of a new A-DCP calibration curve. This curve relates penetration rate to field CBR that nearly follows the DCP calibration with the exception of a slight offset. Field testing of the A-DCP showed less variability and more consistent strength measurement with depth at a speed five times greater than that of the DCP with minimal physical exertion by the operator.