Geotechnical Assessment of Dredged Sediments as an Infiltration Berm Medium

Dredged material (DM) refers to sediment that is excavated from the bottom of the harbor to maintain navigable waterways for shipping and port operations. Over time, sediment accumulates and must be removed to keep channels deep enough for vessels. DM currently has limited applications as a substitute for soils, owing to its variable geotechnical, physical, and chemical characteristics. Environmental and structural challenges are presented by using DM as a construction medium; its low shear strength properties and low hydraulic conductivity make it undesirable as a load-bearing material. A study was conducted to investigate the geotechnical and plant growth properties of raw and stabilized DM from Maryland as possible media for vegetated earthen berms (i.e., infiltration berms). Saturated hydraulic conductivity, unsaturated hydraulic conductivity, and unconfined compression tests were conducted to measure the geotechnical properties and use the data to model a berm in a finite element program. DM amended with straw experienced increases in both hydraulic conductivity and undrained shear strength while providing adequate allowable water content to promote vegetation, without creating any slope stability problems.