Port of Miami Project - Protecting Marine Species During Underwater Blasting

摘要

The Port of Miami, Miami-Dade County, Florida (Port) is the largest container port in the State of Florida. However, it is located in the center of a diverse ecosystem. Biscayne Bay surrounds the Port and portions of the bay have been designated as a National Park, a Florida Aquatic Preserve and a stale Critical Wildlife Area. The bay is home to many protected, threatened and endangered species including the Florida manatee, five sea turtle species, American crocodile and bottlenose dolphin, in addition to important recreational and commercial fish species. In 1990, Congress authorized the deepening and expansion of the Port including deepening of the Dodge Lummus Island Turning Basin and Fisherman's Channel to -42 feet. The Port previously attempted to complete the project without underwater blasting. The contractor and subsequent surety company were unable to successfully complete the authorized work primarily due to the limestone bedrock that was resistant to dredging. In 2000, the Port approached the Jacksonville District, U.S. Army Corps of Engineers (District) to complete this project. The District determined that blasting would be required as a construction technique and that Miami Harbor is occupied by a number of species that are protected under the Endangered Species Act (ESA) including the manatee, two species of sea turtles and the crocodile. As a result the District initiated consultation with the National Marine Fisheries Service (NMFS) and the U.S. Fish and Wildlife Service (USFWS) under Section 7 of the ESA. The District also determined that bottlenose dolphins, a species protected under the Marine Mammal Protection Act (MMPA), had been documented transiting through the Port and could also be affected by the proposed blasting. The District submitted an application for an Incidental Harassment Authorization under the MMPA in June 2002, which was issued in 2004 and renewed in April 2005. Construction blasting began in June 2005 and was completed in August 2005. A key determination made by NMFS and the USFWS was that protected marine species were unlikely to be seriously harmed by the detonations due to the District's conservative monitoring and mitigation measures aimed to ensure that protected marine species would not be within a pre-determined safety zone when the detonations occurred. This paper reviews the results from protected species watch program; an overview of acoustic and pressure measurement data collected during construction; and potential implications for future work using blasting as a construction technique in Florida or elsewhere.