GEOTECHNICAL CHARACTERIZATION OF BALTIMORE DREDGED SEDIMENTS AS AN INFILTRATION BERM MATERIAL ON HIGHWAY SLOPES

Abstract

Baltimore Harbor dredged material has limited use in common geotechnical construction due to its soil composition. It has low shear strength for foundation applications and lack of plasticity makes it an undesirable material for seepage barrier applications. Vegetated infiltration berms, used for regulating stormwater discharge, can be suitable for beneficial reuse of the dredged materials. The scope of this research is to appropriateness of the dredged material for construction an infiltration berm that has sufficient slope stability and provides total infiltration in less than 72 hours. Unconfined compression tests, constant head permeameter tests and unsaturated hydraulic conductivity tests were conducted on the dredged material and its blends with straw, sand, and recycled glass aggregate. All amendments were chosen due to their potential of reducing infiltration time, increasing hydraulic conductivity and as well as increasing the available water content (AWC) to promote vegetation. The effects of different amendments on soil water characteristics curves were examined and related to the vegetation through percent green cover data. Results obtained through testing were implemented in finite element analysis programs, SLOPE/W and SEEP/W, to analyze slope stability and seepage behavior of the berm, respectively. Common berm geometries along with different subgrade conditions were considered during modeling. Straw amended dredged material provided adequate hydraulic conductivity, met the required minimum infiltration times, and acceptable AWC to promote vegetation, without experiencing any slope stability or piping failures.