Cox Creek Dredged Material Containment Facility Design and Construction

The Cox Creek Dredged Material Containment Facility (DMCF) is a confined disposal facility (CDF) which is a major component of the Maryland Port Administration's (MPA) dredged material management plan (DMMP) for Baltimore Harbor. After much study, design, and re-design in response to environmental, geotechnical and value engineering concerns, the 115-acre Cox Creek DMCF Dike Raising and Rehabilitation Project began construction in September 2002, with completion in the Fall of 2006. The reactivated facility will be used to meet the goals of the Dredging Needs and Placement Options Program (DNPOP) of the Port of Baltimore, and is to receive an annual capacity of 0.5 million cubic yards (MCY) of material dredged from the Baltimore Harbor channels, which are legislated as being contaminated. Total capacity is planned to be 6 MCY over an operational life of 10 to 12 years. Several environmental and geotechnical issues needed to be resolved before construction could begin. Key components of the design include the following: 1) Design and construction of a new 66-inch storm drain to reroute storm water into a water quality management pond prior to discharge; 2) Coastal engineering evaluation to design the dike sections and armor stone slope protection; 3) Optimization of the dike design with consideration given to initial construction costs vs. long-term maintenance costs; 4) Spillway design and construction including hydrodynamic modeling to evaluate mixing requirements; 5) Use of a turbidity curtain in the water to prevent suspended sediment from migrating from the site; 6) Use of dike construction materials, especially borrow sources, to meet environmental criteria; 7) Incorporation of a geotechnical stabilization berm on the outside of the dike, constructed using recycled glass as granular fill and incorporating wick drains; 8) Restoration of a 12-acre tidal wetland area adjacent to the site as mitigation for filling open water, with hydrodynamic modeling to evaluate tidal flushing; 9) Construction of the interior portions of the dikes using dewatered dredged material from on-site; and 10) Construction of a 300-ft long `L-shaped' concrete pier for mechanical unloading of dredged material.