Article Title

Marine Archaeology Assessment in Support of the Bluewater SPM Project, Nueces and Aransas Counties, Texas and Adjoining Federal Waters

Authors

Robert Gearhart, BOB Hydrographics, LLCFollow

Agency

Texas Historical Commission

DOI

https://doi.org/10.21112/ita.2019.1.21

Abstract

BOB Hydrographics, LLC conducted a marine archaeological assessment for portions of the Bluewater SPM Project proposed in Nueces and Aransas counties and adjoining federal waters. These archaeological investigations were sponsored by Lloyd Engineering, Inc. on behalf of Bluewater Texas Terminal, LLC. The marine portion of this project comprises two segments: Offshore and Inshore. The Inshore project corridor parallels the Aransas Ship Channel from the community of Aransas Pass to Harbor Island, crossing portions of State Mineral Lease Tracts 309, 310, 313, 314 in Corpus Christi Bay, and then crosses beneath the Lydia Ann Channel to San Jose Island, including a portion of Tract 306 in Aransas Bay. The Offshore project corridor crosses portions of State Mineral Lease Tracts 693, 694, 695 (same as MI-695), 721, 836, 837, 838, 839, 844, 845, 846, 847, 848, 849, 850, and 851 on the Gulf side of San Jose Island, and then crosses portions of Federal Lease Blocks MI-695, MI-696, MI-697, MI-698, and MI-699.

The marine Area of Potential Effect (APE) is a 2,000-foot-wide corridor, offshore of San Jose Island, and a 1,000-foot-wide corridor, inshore of San Jose Island. Both Inshore and Offshore APEs are centered on the construction right-of-way and include the proposed lay barge anchorage. The APE totals 7,174 acres, including 3,079 acres in federal waters and 4,095 acres in state waters. The APE in state waters totals 288 acres Inshore and 3,807 acres Offshore in the Gulf of Mexico. Water depth ranges from 2-30 feet (ft) Inshore and from 0-92 ft Offshore. The Project proposes construction of a Deepwater Port (DWP) with two single point mooring (SPM) buoys and associated pipelines. The DWP would be located 17.3 miles offshore of San Jose Island in approximately 89.5 ft of water. The DWP would allow simultaneous loading of two Very Large Crude Carrier tankers with domestic crude oil via two 30-inch sub-marine pipelines. Pipes will be directionally drilled beneath all shorelines and Inshore waterways. Offshore pipes will be buried by a jetting sled to a depth of 6-7 ft below the seafloor with 36 inches of cover. The sled will discharge sediment back into the trench to facilitate backfilling. Subsea pipes will be separated by 10-15 ft, horizontally, within a proposed 75-ft-wide construction right-of-way. Offshore pipes will be installed from a conventional pipelay barge with an 8-point anchor system (using 4 at a time). Inshore pipes will be directionally drilled beneath all bay waters.

The purpose of this study was to assess the potential for submerged archaeological sites in the APE; however, no artifacts were collected during the survey. Submerged archaeological sites, in this context, might be historic sites, such as sunken or abandoned watercraft; or drowned terrestrial prehistoric sites dating to the late Pleistocene or Early Holocene when the APE was last above sea level. A review of the cultural background determined that 11 marine archaeological investigations have been conducted within 3 miles of this project. At least, 95 wrecks have been reported within 3 miles of the APE.

Geophysical survey was completed by Naismith Marine Services, Inc. from January 4 through April 19, 2019 under Texas Antiquities Permit 8672. A variety of equipment was used to conduct the marine survey, depending on water depths, including multi- and single-beam echo sounders, a sub-bottom profiler, sidescan sonar, and a magnetometer. Archaeologists monitored the acquisition of all data in state waters.

Analysis of geophysical survey results from this investigation discovered three significant targets, including one in federal waters (Anomaly 1), and two in state waters (anomalies 2 and 3). All three targets are potentially eligible for the National Register of Historic Places and are recommended for avoidance. The two targets in state waters also may be eligible as State Antiquities Landmarks. Anomaly 2, is confirmed as a shipwreck by sonar imagery and is designated as an archaeological site, 41AS119. No potential historic sites were discovered by the Inshore survey. There is low potential for the presence of intact prehistoric sites in the Offshore APE. The top of the Beaumont Formation is exposed at the seafloor between the 31- ft and 46-ft isobaths and is buried by Holocene sediments to varying depths beneath the remainder of the survey corridor. This former land surface had little protection from wave energy during sea-level rise and is still actively eroding along portions of the APE where exposed. The Texas Historical Commission did not require sub-bottom data in the bay, so areas of high potential for submerged prehistoric sites were not mapped there.

This study was completed in compliance with Section 106 of the National Historic Preservation Act (Public Law 89-665; 16 U.S.C. 470) and the Antiquities Code of Texas (Texas Natural Resource Code, Title 9, Chapter 191). The minimum reporting and survey requirements for marine archaeological studies conducted under a Texas Antiquities Permit are mandated by The Texas Administrative Code, Title 13, Part 2, Chapters 26 and 28, respectively. The petroleum industry is regulated in federal waters, beyond 9 nautical miles offshore, by the Bureau of Ocean Energy Management (BOEM), an agency of the United States Department of the Interior. This study also complies with archaeological requirements published by BOEM in their Notice to Lessees 2005-G07. Archaeological project records are curated at the Center for Archeological Study at Texas State University in San Marcos.

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