Allie B Grounding Site: Administrative Draft Restoration Plan/Environmental Assessment

Bourque, Amanda

The Allie B tug, with loaded barge, grounded in Biscayne National Park (BISC) on July 20, 1998 Based on coordinates obtained during the site visit in December 2004 (Tetra Tech, 2005), the Allie B tug came to rest approximately 2,000 feet (ft) (600 meters [m]) west southwest of the location where the towed barge came to rest. Following the grounding event, the National Park Service (NPS) performed a detailed assessment of the Allie B grounding. The barge, tug, and tow cable caused the grounding-related injuries. Predominant injuries associated with the tug grounding and subsequent extrication included surficial scraping of the hard bottom substrate and significant displacement of unconsolidated substrate during blowhole formations. Predominant injuries associated with the barge grounding included fractured substrate, displacement of substrate and biota, and hull paint deposition on scarred substrate. A keel scar was also reported on the reef crest at the tug grounding site. Surficial substrate scraping and biotal displacement were caused by the tug/barge cable on Ledbury Reef, north of the barge grounding site. In September 1998, Hurricane Georges crossed the lower Florida Keys and buffeted BISC with high wind and rough sea conditions for several days. After the passage of Hurricane Georges, the blowhole was found to be partially filled with sediment to a new depth of approximately 3.6 ft (1.5 m). In addition, collateral damage to the adjacent reef occurred from the movement of loose rubble from the berm. In August 1999, time-critical blowhole restoration activities were undertaken at the injury site on behalf of NPS by a contractor, Law Engineering and Environmental Services (LawGibb). This time-critical restoration consisted of covering the bottom of the blowhole with a layer of rubble from the berm. In its detailed assessment, NPS BISC staff identified injured resources at the tug grounding site as 2,689 square ft. (ft^2)(249.82 square meters [m^2]) of prop-wash blowholes, 3,229 ft^2 (300 m^2 of propwash rubble field, and 269 ft^2 (25 m^2 of keel scar and tug contact points. The barge grounding site injury consisted of truncated and impacted reef spurs at 19 stations totaling 2,089.5 ft^2 (194.12 m^2, and the tow cable injuries consisted of cable scars and coral injuries totaling approximately 269 ft^2 (25m^2. The Stipulation of Settlement required that the tug defendants pay $1,000,000 to the United States as compensation for response costs and damages for destruction, loss of, or injuries to park system resources pursuant to the Park System Restoration Protection Act (16 USC 19jj). This settlement included costs for the NPS response to the grounding incident, restoration planning activities, and restoration action implementation. NPS determined that damages will be applied "toward the restoration, replacement, or rehabilitation of the equivalent of the natural and National Park System resources or resource services which were injured, destroyed or lost as a result of the Allie B grounding." NPS developed criteria to systematically evaluate applicable restoration actions. The restoration alternatives were then evaluated by NPS using the evaluation criteria. NPS determined that the restoration alternatives for the Allie B grounding site that best comply with BISC coral reef restoration goals and objectives are the following: (After evaluation of the alternatives by NPS, the selected alternative will be added)