Document Type

Report

Publication Date

8-24-2001

Abstract

The Calypso Natural Gas Pipeline Project (project) will include a 24-inch pipeline which will extend from the Exclusive Economic Zone (EEZ) off the southeast Florida coastline to a shore approach at Port Everglades in Fort Lauderdale, Florida.

This report, which was commissioned in May 2001 and completed in July, 2001, documents the results of a detailed biological survey of underwater marine habitats from 5 to 200 feet water depth for the pipeline route. The route, which was established based on the subsea survey that was completed in May 2001 by Williamson & Associates, Inc., includes a shore approach from the north of the Port Everglades entrance channel to a pipeline landing site south of the Port Everglades entrance channel. The purpose of this biological survey report was to identify benthic characteristics within the nearshore pipeline corridor and to identify and evaluate potential temporary impacts to the marine ecosystems. The pipeline corridor investigated was 300 feet wide and extended from the shoreline to the 200 foot water depth, a distance of approximately 14,000 feet. In addition, some video surveying was conducted to approximately the 250-foot depth contour (an additional distance of approximately 500 feet).

Underwater survey methods included use of SCUBA diving to conduct underwater quantitative biological transects and integrated video mapping using a vessel towed system which provided a permanent record together with a DGPS location. Remote sensing information included use of aerial photographs and LIDAR bathymetry to guide habitat delineation.

A total of eight (8) benthic habitats were defined within the pipeline corridor. These habitats included: 1. First Reef 2. Submerged Breakwater/Spoil 3. Second Reef 4. Second Reef-Sand Complex 5. Sand 6. Third Reef 7. Third Reef-Sand Complex, and 8. Third Reef Transitional.

Density (number per m2) of hard corals, soft corals, and sponges was determined at several representative transects within certain habitats. Results of the study indicated that overall coverage by hard corals, soft corals, and sponges is very low in the proposed project area. Along the proposed pipeline route, percent hard coral coverage ranged from 0.16% in the Submerged Breakwater / Spoil Area to 1.34% in the Third Reef habitat. Soft coral density was lowest in Second Reef-Sand Complex (0.02 soft corals per m2) and highest at the Third Reef (11.85 soft corals per m2). Sponge density varied from 0.23 sponges per m2 in the Submerged Breakwater / Spoil Area to 19.48 sponges per m2in the Second Reef zone. Previous surveys in the general project vicinity indicate that no zooxanthellate reef-building hard corals occur in water depths greater than about 120 feet of seawater (FSW).

Direct impacts of approximately 1.60 acres of hardbottom habitat characterized by very low coverage by hard corals, sponges and soft corals are expected. These impacts will occur at proposed horizontal directional drilling exit or entrance holes, laydown areas of pipeline, trenching, and blanketing to bury pipeline from the Port Everglades entrance channel from the shoreline to the 200-foot depth contour, as shown in Tables 5, 6, and 7. A further approximately 4.34 acres of area would be affected adversely by temporary indirect effects (i.e., sedimentation and turbidity) effects as shown in Tables 8, 9, and 10. Table 11 provides a summary total that 5.94 acres of hardbottom habitat would be directly or indirectly affected. In addition, approximately 0.008 acres of very sparse seagrass (Halophila decipiens) will be directly impacted. Finally, no threatened or endangered species (including the federally threatened seagrass Halophila johnsonii) were observed in the project area. Observations were conducted to the approximate 250-foot depth contour. Video surveys to that depth indicated benthic conditions consistent with those of the Third Reef Transitional complex and open sand. Project activities beyond 200 FSW will consist only of pipe placement directly on the sea bottom.

Publication Title

NCRI Report

Comments

"Submitted to: Calpyso Pipeline, LLC" From page 1.

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