The use of native vegetation for structural stability in dredged material placement areas : a case study of Beneficial Use Site 4A, Chocolate Bayou, Brazoria County, Texas

Abstract

This technical note is the third in a series about using native plant communities to enhance dredge material placement areas (DMPAs), confined disposal facilities (CDFs), and projects where dredged sediments are used for various engineering purposes. DMPAs and CDFs occur in numerous locations spanning different geographic locations nationwide. Oftentimes, these containment dikes are constructed using earthen materials. The materials are either barged in from an off-site location or obtained on-site from new or virgin materials, consisting of heavy clay particles and sediments removed from the nearby channel. In the Gulf Coast region of the United States, new or virgin materials are obtained during channel deepening activities using mechanical or hydraulic dredging methods. Examples of these dredging methods include hopper dredge, pipeline dredge, and excavator or bucket dredge. When materials are considered suitable for beneficial use purposes, and following environmental compliance, the materials are often used to construct containment dikes in DMPAs and CDFs. The project site used in this study—Beneficial Use Site 4A (BUS 4A)—used dredged material during its construction and has periodically received dredged material to maintain its target elevation of 2 ft (0.67 m) above the mean lower low water; hence, this site presents an opportunity for use as a demonstration study. Project goals include (1) demonstrating the use of native plant communities to provide structural stability, (2) introducing targeted vegetation establishment on DMPAs and CDFs as a management strategy to improve engineering and environmental outcomes, and (3) providing technology transfer to the U.S. Army Corps of Engineers (USACE) districts through hands-on planting techniques and installation of natural material (in this demonstration, coir logs).